Collimating TIR lens devices employing fluorescent light sources

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United States Patent 19 11 Patent Number: 5,676,453 Parkyn, Jr. et al. 45 Date of Patent: Oct. 14, 1997 54 COLLMATING TRLENS DEVICES 4.737,896 4/1988 Mochizuki et al.. EMPLOYNG FLUORESCENT LIGHT 4,755,921 7/1988 Nelson.

SOURCES 4,794,501 121988 Bartenbach ......................... 362/260 X 5,079,681 1/1992 Baba et al........................... 362,260 X 75 Inventors: William A. Parkyn, Jr., Costa Mesa; 5,128,848 7/1992 Enders et al..

David G. Pelka, Los Angeles, both of 5.193,899 3/1993 Oe et al.

Calif. 5,241,462 8/1993 Sugimoto.

a. 5,404,869 4/1995 Parkyn, Jr. et al..

73 Assignee: TR Technologies, Inc., Carson City, 5,485,319 1/1996 Lemons. NeW.

FOREIGN PATENT DOCUMENTS

21 Appl. No.: 445,547 1325086 8/1973 United Kingdom.

995 1325087 8/1973 United Kingdom -

8 1546792 5/1979 United Kingdom.

Related U.S. Application Data 1546793 5/1979 United Kingdom.

63 Continuation-in-part of Ser. No. 415,274, Apr. 7, 1995, Pat. E. g E. E. - No. 5,577,492, which is a continuation-in-part of Ser. No. 2239939 f1993 United E.d 869,003, Apr. 16, 1992, Pat. No. 5,404,869. nated Kingdom.

52 U.S. Cl. ........................ 362/260;362/339; 362/291; Primary Examiner-Larry Jones 362/.328 Attorney, Agent, or Firm-William W. Haefliger 58 Field of Search ............................ 362/260, 33, 147, 362,216,291,292,298.309,326,337. 57 ABSTRACT 338,339, 340, 80,328 A radiant energy redirecting system comprising a radiant

energy transmitting body structure; the structure comprising

References Cited multiple elements, each of which acts as a radiant energy

an entry face to receive incidence of the energy into the 1,421,506 7/1922 Limpert. interior of the perimeter, an exit face to pass the energy to 3,915,148 y13: Er et al. . the exterior of the perimeter in a direction towards the 3,941,993 96 Hubert. reverse side of the body from the side of the incidence, and

a Totally ing fface angled relative to the

Internally Reflecting 4,022,186 5/1977 Northrup, Jr. . entry and exit faces to redirect towards the exit face the 4,074,704 2/1978 Gellert. radiant energy incident from the entry face; the body struc 4,103,673 8/1978 Woodworth et al.. ture generally redirecting incident radiant energy towards a 4,108,540 8/1978 Anderson et al.. predetermined target Zone situated apart from and on the 4,116,223 9/1978 Wasilantone. reverse side of the body relative to the side of the incidence; 4,124,917 11/1978 Paul. and lens structure associated with at least one of the faces for 3: 1 SE A. redirectingradiant energy passing between the entry and exit 4. 94549 3,980 Stark. faces via the Totally Internally Reflecting face.

4,488,208 12/1984 Miller ...................................... 362/339 13 Claims, 29 Drawing Sheets

CUSP REFLECTOR CIRCULAR

FLUORESCENT

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COLLMATING TR LENS DEVICES art, and to provide a means to collect and employ radiant EMPLOYNG FLUORESCENT LIGHT energy in a very cost-effective and efficient manner, using a SOURCES new basic tool with applications that include the collection, concentration, redirection, and wavelength separation of

This application is a continuation-in-part of prior U.S. 5 radiant energy.

application Ser. No. 08/415,274 filed Apr. 7, 1995, now U.S. The present invention, which improves over the subject Pat. No. 5,577,492, which is a continuation-in-part of prior

U.S. application Ser. No. 07/869,003 filed Apr. 16, 1992, by matter of U.S. Pat. No. 4.337.759, is basically characterized now U.S. Pat No. 5,404,869. the use of a transparent means employing elements to

redirect radiant energy by means of TIR alone, or in con junction with refraction, such means positioned between the

This invention relates generally to radiant, particularly radiant energy source and a receiver. Each element redirects electromagnetic, energy concentration, redirection, and radiant energy upon a common target zone or zones, during manipulation, and improves over the subject matter of U.S. the energy's internal passage through the element. A prop Pat No. 4337,759. It more particularly concerns apparatus erly oriented ray enters through the entry face and strikes the and method for employing a transparent lens means with 15 reflective face, which redirects it toward the exit face, the elements thereof using Total Internal Reflection (TIR), in conjunction with a focusing second lens and a wavelength three faces comprising the active faces for that ray. In addition, the lens means is associated with at least one of the selection filter, for use such as in laser spectrometry.

Radiant energy is redirected to or from a predetermined faces entry for redirecting radiant energy passing between the and exit faces via the TIR face.

zone or zones; such redirection having a predetermined 20 Accordingly, the present invention is characterized by the degree of concentration and/or chromatic dispersion. The passage of redirected radiant energy entirely through the zones have sources of light, as in photoillumination, or radiant energy-receiving means for conversion of the redi transmitting body means and out the opposite side from rected energy to thermal, electric, chemical, or mechanical which it entered after transmission via associated lens forms. means. This invention constitutes a third class of radiant

The prior art of radiant energy concentration and illumi energy concentrators that also has applications to other nation in general consists of two major types, as exemplified forms of radiant energy redirection than concentration, such by refractive and reflective astronomical telescopes: a as wavelength separation or collimation. Other surfaces of refractive lens, positioned in front of a receiver or light the element may be inactive for the ray of interest (e.g., as source; or a retro-reflective mirror, positioned behind a in solar energy concentration of relatively parallel rays) but receiver or light source. The corresponding devices in the 30 may impinge upon improperly oriented rays (e.g., diffuse prior art of solar energy concentration are the Fresnel lens skylight of off-angle sunlight).

and the parabolic reflector, which focus solar energy on a The TIR elements may be contiguous, forming a trans target. Furthermore, there are non-imaging, reflecting con parent centrators that have the advantage of fixed daily (non 35 to pass cover between means, or separated to allow undeflected light them, for example to be focused by a mirror tracking) position with only seasonal adjustments, but the upon the back of disadvantage of requiring relatively large reflector areas and from all directions.the target, which is thereby illuminated delivering only relatively low energy concentrations.

Fresnel lenses are devices comprising purely refractive Each element may redirect all of the parallel rays entering elements, but they have physically inherent limitations of it into a single new direction, or split them into several redirecting radiant energy that give high fratios and bulky directions, with or without wavelength separation, which concentrator structure. Moreover, linear Fresnellenses have, can be controllably achieved by the independent, non for off-angles in the direction of the grooves, focusing errors, normal angling of the entry face and/or the exit face to the that are also inherent in the laws of refraction, and that limit parallel rays being redirected, or achieved by diffraction one-axis tracking configurations to relatively low concen gratings upon the exit face, which can be implemented by tration. 45 the replicative techniques of binary optics. Parabolic reflector concentrators have seen widespread While TIR alone is limited to incident angles greater than use, but are subject to losses of received radiant energy the critical angle and therefore to any redirective bend because the receiver is situated between the source and the angles less than 180°-2 critical angle (about 96 for acrylic), reflector, which is thereby shaded, preventing in particular additional redirection is possible with or without wavelength the utilization of large heat engines at the focus. 50 separation by the above-mentioned, non-normal angling of Furthermore, the receiver is exposed to environmental deg the entry and exit faces. Such large bend angles enable a radation and thermal losses; and the inclusion of a given diameter transparent means to be much closer to the protective, transparent cover means about the receiver will target than a means limited to refraction alone, thereby merely reduce the system's optical efficiency. greatly reducing the necessary support structure. Another reflecting system has appeared in the literature, 55 Furthermore, a transparent means employing up to 90° bend as reported by Rabl in Solar Energy Vol. 19, No. 5. It angles can utilize a flat mirror extending from the target to employs a retro-reflecting means with elements that have the rim of the means, thereby doubling solar concentration two TIR faces to redirect radiant energy out the same side as or doubling intercept efficiency for a light source. it came in. Its only improvement over a metal mirror of the Since a given acceptance angle (of deviation from same shape is a potentially higher reflectivity; but the double parallelism) produces a proportional requirement for target internal reflection doubles the sensitivity to manufacturing size, the target can be bisected by the plane of the mirror, and error over that of the present invention, which redirects result in an actual target of half the original size, with no radiant energy through itself with only a single reflection. decrease in acceptance angle, by insulating the half of the SUMMARY OF THE INVENTION target facing away from the redirected body means. 65 Conversely, the target can be doubled in size to give a

It is a major object of the TIR lens to overcome the doubled acceptance angle, and then halved by the mirror above-described problems of, and difficulties with, the prior back to its original area. This surprising potential for halving

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thermal losses is unique to the present invention, being The angle of this fourth, optically inactive, side of the unavailable for the parabolic reflector of 90° rim angle facet would typically be set at the minimum draft angle for because the plane mirror would shade the aperture, and also pulling the lens from a mold (about 2). In the case of small unavailable for the Fresnel lens because of its far lower rim lenses with only a few facets, there is also the possibility of angle. an adjacent facet being larger or Smaller than its neighbors, Unlike the Fresnel lens, chromatic aberration is com in order to raise the lens height and improve collimation. The relative facet positions, as determined by the non pletely independent of bendangle and can have any positive, interference

Zero, or negative values desired for such wavelength which shouldcriterion, be low determine the overall lens profile, or high depending upon the applica separation applications as Solar illumination or bandgap tailored photovoltaic cells. Unlike the parabolic reflector, the 10 tion. In a solar concentrator, the lens height should be minimized to reduce spot size of the solar image. In a redirective bend angle of an element is independent of its converging location, greatly adding to design flexibility. (Since the advantageousortocollimating have

TIR illumination system, it is somewhat more lens height, so that the parabolic reflector is a smooth continuum, there can be no apparent size of the source is reduced arbitrary variations in redirective bend angle from one spot and the output beam is thereby tightened.atThis the central facets, consideration to a neighboring one.) 15 does not hold for diverging TIR lenses, because only

The first of the present invention's improvements over the efficiency, and not beam tightness, is required. subject matter of U.S. Pat. No. 4337,759 is the curvature of An important use of facet curvature is in a small TIR lens the faces of the individual lens elements. This curvature may with only a few facets, such as a collimator for a light be provided at one, two or all three of the faces (entry, exit 20 emitting diode. Molding very small facets may be undesir and TIR) and, for example, may constitute a concave entry able because of difficulties in making the mold. Curved facet face, a convex exit face, and/or a convex TIR face. faces enable relatively large facets to perform as accurately Radiant energy handling is thus improved over a flat as small ones. Lenses for light-emitting diodes are of interest faceted face system, as for example in redirection of rays for redlamps at the rear of automobiles. In fact, the TIR lens from a line or point source, within constraints of interior 25 can be incorporated into the conventional transparent cover shadowing and TIR face slope, to produce either parallel or of an LED, greatly improving its luminous efficiency. converging output beams in a system using multiple faces. Further improvements over the subject matter of U.S. Pat. Also, improvements in ray collimation and focusing are No. 4,337.759 are: a lens that redirects light from a source realized, and design freedom is enhanced, since each face in order to focus it on a spot in front of the lens. can be individually curved or various combination of face There are two reasons that the TIR lens is superior to curvatures can be employed to minimize aberrations, due to 30 conventional ellipsoidal reflectors for this application. First, the finite size of the facets. the lens and its associated planar back mirror collect all of For ease of quality control of manufacturing, the curved the output of a light source and focus it. The ellipsoidal facet faces can form spheres with centers on the axis of reflector typically collects only a fourth of a source's output. rotational symmetry of the lens. When an axially symmetric 35 Second, facet configurations are possible with efficient lens is made by molding a rigid material, undercut interior focusing power; that is, at the center of the focal spot, the faces are precluded, which limits the curvature of those entire lens would appear to be as bright as the light source faces. This constraint is not applicable to elastomeric lens itself, a condition known as "full flashing”, important for the materials. proper functioning of microfiche and slide projectors. The facet design of the TIR lens has four degrees of Because of astigmatic aberrations inherent in the ellipsoidal freedom: the angle of the entry face, the angle of the TIR reflector, it is never fully flashed, producing instead a much face, the angle of the exit face, and the position of the broader focal spot. Full flashing by the TIR lens is made inwardly adjacent facet. A full design solution requires that possible by faceting of the exit so that stairsteps have their four requirements be used to derive these four angles. In "risers” parallel to inner rays then emerging from the exit many of the designs illustrated below, prearranged choices 45 face. Then, the full exit face of the facet must be illuminated restricted the degrees of freedom. In general, however, the by light from the TIR face, a condition that can be fulfilled requirements are: by curvature of the TER face.

a) the redirection of light from source to target; Furthermore, the exit face can have about the same b) the full interception of light by the TIR face; refractive bending as the entry face, preventing unwanted c) the full illumination of the exit face, for maximum 50 image magnification that broadens the focal spot. The indi vidual convex curvature on each of the facetfaces is vital to thermodynamic efficiency; and d) the non-interference of a facet's input and output rays the success of this design:

by the next facet inwards. entry-face curvature enables the entire TIR facet to be Typically, a TIR lens is generated from the outermost, or utilized, through a slight convergence that prevents any rim, facetinwards in a facet-by-facet, numerically controlled 55 light from missing the TIR face; iteration. The four requirements form a set of nonlinear TIR-face curvature enables the entire exit face to be equations in four unknowns to be solved for their roots. illuminated, by preventing any light from striking the Because there is no general method of solving such stairstep risers or the adjacent TIR face; and equations, typical computer routines apply a matrix inver exit-face curvature focuses light onto the target, eliminat sion method that assumes quasi-linearity in the neighbor ing the effects of finite facet size. hood of the solution hyperspace. This requires some prior This focusing configuration would have two prominent knowledge of this hyperspace so that a starting point for the applications that considerably improve the light utilization solution search is within the quasi-linear regime. This prior efficiency of the prior art: imaging projectors for slides, knowledge depends upon whether the facet is triangular or motion pictures, or microfiche. Current designs use ellip quadrilateral. The former give wider interfacet slot angles 65 soidal reflectors that have inherently low intercept efficiency and thus are easier to make; but the latter add another degree (i.e., the fraction of the source output that actually ends up of freedom, enabling a wider choice of overall lens shapes. in the output image of the device).

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The TIR lens of the present invention can be used in lamp. The complete lens would be a figure of revolution with conjunction with an aspheric lens, in order to remove the its axis being that of the toroid rather than the center of the cosine-4th illumination non-uniformity typical of the prior lens profile. The more slender the toroidal lamp, the better art. This version of the TIR lens typically has stepped exit could its light be controlled by the lens. faces, with the risers angled parallel to the converging rays, Presently, there are no reflectors that can collect the light to ensure spatial continuity of the focal cone. The faces of of such a lamp and put most of it into a forward-going beam. the facets can be curved so as to augment the action of the This toroidal TIR lens would be very useful for battery auxiliary lens.

Another advantage of the TIR lens for this application is powered vide any fluorescent lanterns, which currently cannot pro focusing whatsoever, that it azimuthally smears out any structure in the source, 0 A collimating TIR lens made of silicon: because of the removing a source of pattern noise that is inherent in the high refractive index of this material, the refractive faces of imaging action of an ellipsoidal reflector. its facets would be somewhat differently angled than those Illumination injector for optical fiber bundles and light of a glass lens. The application for a silicon lens is for the pipes. Prior arthere also uses ellipsoidal reflectors. The collimation of infrared light and the exclusion of visible TIR lens would have a focal cone half angle matched 15 light (because silicon absorbs all wavelengths shorter than to the acceptance angle of the target. 1.1 micrometers).

Light-gathering means for spectrometers that analyze the The purpose of this application is the jamming of the diffusely emitted light of samples that have been stimu guidance sensors of heat-seeking, anti-aircraft rockets by lated to produce Raman or fluorescent light. focused beams of pulsating infrared light. The prior art uses Conventional spectrometers typically collect this light much less efficient parabolic reflectors in conjunction with a with microscope objectives, which also deliver tightly silicon window. The silicon TIR lens would be an important focused (50 micrometers) laser light to the sample. These new kind of infrared illuminator, as found in many night objectives typically have a focal length equal to their vision systems.

diameter, so that they subtend about 50° and collect 5% of The superiority of the present invention can be seen in its the diffusely emitted output. 25 application to prisms with curved cross sections, arrays of The converging TIR lens can collect over half of this connected linear or toroidal prisms acting in concert, redi emission, a factor of ten improvement, greatly aiding spec rection of rays from a line or point source, concentration of tral analysis because of the greater signal to noise ratio. spherical or plane waves, better collimation than parabolic ATER lens that redirects light from a source in order to mirrors, and more efficient focusing than ellipsoidal mirrors. form a diverging cone of light, as in floodlighting Another object of the invention is to provide a radiant applications. energy redirecting system comprising: For cone angles of 45 or less, this lens is more efficient a) a radiant energy transmitting body means, than a conventional congruent reflector and much b) that means comprising multiple elements, each of more compact. This divergence can either be for which acts as a radiant energy redirecting module, uniform illumination, or it can take the appearance of 35 having on its cross-sectional perimeter an entry face to effectively coming from a virtual source located receive incidence of the energy into the interior of the behind the lens, with appropriate facet-face curva perimeter, an exit face to pass the energy to the exterior tures compensating for the different distances of the of the perimeter in a direction towards the reverse side facets from the source.

Two types of linearly symmetric TIR lenses for cylindri of the body from the side of the incidence, and a Totally cal sources (such as fluorescent tubes): Internally Reflecting face angled relative to the entry and exit faces to redirect towards the exit face the one that confines its output to a relatively narrow radiant energy incident from the entry face, off-axis angle. With the prior art, this is possible only with quite deep and bulky reflectors; c) the body means generally redirecting incident radiant one that reduces its on-axis output and enhances the 45 energy towards a predetermined target zone situated lateral output, in order to produce uniform illumi apart from and on the reverse side of the body relative nance on a nearby surface that is being used for to the side of the incidence, indirect lighting. Such a shape appears very different d) first lens means associated with at least one of the faces from other TR lenses. for redirecting radiant energy passing between the entry Linear TIR lenses have somewhat of a handicap from 50 and exit faces via the Totally Internally Reflecting face, sagittal ray internal reflection, whereby rays emitted from the redirected radiant energy being collimated, the linear source at a large out-of-plane angle with the lens e) and second lens means spaced from the exit face to cross section will encounter the exit face at a total incident receive the collimated radiant energy and to redirect angle that exceeds the critical angle for total internal reflec same toward the target zone. tion. Most of the facet designs used in radially symmetric 55 Yet another object of the invention is to provide a system, lenses will, when put into linear lenses, be subject to this as referred to, wherein the second lens means is a focusing whenever the out-of-place angle exceeds 40°, which encom Fresnel lens. A wavelength selective filter may be provided passes half of all rays emitted from a Lambertian, or in the path of collimated radiant energy, redirected toward uniformly emitting, source. This trapping of light within the the target Zone; and that filter may extend in close proximity lens can be remedied by corrugation along the outer face of to the second lens means and between the latter and the first the lens, which unfortunately precludes manufacturing by lens means. Further the first and second lens means may extrusion because the cross section is no longer constant. define a principal axis which passes through the target Zone, Another method is binary optics outcoupling through min and that axis may extend normal to parallel planes defined iature stepped patterns on the outside of the lens. by the second lens means and the filter. A more useful lens design would be applied to a toroidal 65 A further object concerns the provision of a central fluorescent lamp. The TIR lens profile would have its axis of portion about which the entry, exit and Totally Internally symmetry over the circular cross-section of the toroidal Reflective faces extend, the central portion comprising a

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microscope objective; and a mirror may be positioned FIG. 28 is a section showing a toroidal TTR lens and a between said first and second lens means to reflect light toroidal light source, such as a fluorescent lamp; toward said central portion of said body means. FIG. 28a is a schematic plan view showing reflector and An additional object is to provide aluminaire comprising: lamp surfaces, as seen in FIG. 28;

a) a TIR lens having multiple facets and extending 5 FIG. 29 is a graph;

lengthwise, FIG. 30 is a view like FIG. 28 showing a modification b) a light source facing the TIR lens and also extending with cusp-shaped reflector structure;

lengthwise in generally directionally symmetrical rela FIG. 31 is a schematic showing of comparative bright tion to the lengthwise-extending TIR lens. O neSSeS;

As will be seen, the light source may extend linearly, or FIG. 32 is a perspective view showing a linear TIR lens; along an arc (such as toroidaly); the TTR lens may also extendlinearly, or along an arc (such as toroidaly). The light FIG. 33 is a section taken through the FIG. 32 lens, and source may then advantageously comprise afluorescent tube formingcombined with an elongated light source, and reflector, and or bulb, oriented as described. an aperture lamp;

These and other objects and advantages of the invention, 15 FIGS. 34,35a, 35b, and35c are ray trace representations; as well as the details of an illustrative embodiment, will be and more fully understood from the following specification and FIGS. 36 and 37 are geometrical representations. drawings, in which: DETALED DESCRIPTION

DRAWING DESCRIPTION

As described in U.S. Pat. No. 4,337,759, and referring to

FIG. 1 is a vertical section in elevation showing one form FIG. 1, radiant energy transmitting body means 10, in the of apparatus embodying the invention; shape of a cover or dome, has multiple facets or elements as FIG. 2 is a vertical section in elevation showing another at 11, each facet having an entry face to receive impinge form of apparatus embodying the invention; ment of such radiation, an exit face to pass energy to the FIG. 3 is an enlarged section on lines 3-3 of FIG. 2; 25 exterior of the body, and an internal reflection face angled FIGS. 4a, 4b, 4c. 4d and 4e are enlarged sections through relative to the entry and exit faces to reflect radiant energy elements of various configurations; incident on the reflection face toward the exit face. For FIG. 5 is a view like FIG. 1 showing a portion of a solar example, in FIGS. 1 and 4d, a selected facet 11 has, in optical concentrator of somewhat different and employed 30 vertical cross section, an entry face 12 made up of configuration; stairstepped faces 12a and 12b, an exit face 13 facing the FIG. 6 is a schematic showing two devices, operating in zone of target 15, and an internal reflection face 14. Radiant conjunction, one of which is like that of FIG. 1 or 5, and the energy, such as light, is represented by rays 16a and 16b other being a collimator; entering the body means 10 at flat face 12a and normal FIG. 7 is an enlarged section through a collimator as used 35 thereto, and passing internally of the facet for reflection by in FIG. 6; face 14. For this purpose, the face may be silvered at 17. The FIGS. 8, 9, 10, 11, 13, 14 and 15 are schematics showing reflected normal rays 16c then pass toward and through exit face 13, thereto, and directly toward the target Zone.

different applications of the radiant energy concentrating neanS, The body means 10 may consist of solid transparent FIGS. 12a and 12b are fragmentary sections showing material, Such as glass or plastic, for example. modified concentrators; The multiple facets 11 shown in FIG. 1 may extend FIGS. 16-18 show various curved lens surface arrange annularly about and define a common axis 18; or they may extend in parallel relation (normal to the plane of FIG. 1) at ments;

FIGS. 19a, 19b, 19c. are sections producing light rays of 45 opposite sides of a plane as alternatively represented by 18, and which is normal to the plane of FIG.1. In either event, varying angularity, as shown; corresponding points on the facets define a concave surface, FIG. 20 is a section of a facet with three curved faces, as for example at 21 (defined by the tips 22 of the facets illustrating the general principles of facet design; closest the target), and characterized in that radiant energy FIG. 21 is a section showing a further modified radiant passing through the exit faces is directed generally toward energy concentrating means for use with a light-emitting 50 the target zone. Tips 22 are formed at the intersections of the diode; faces 13 and 14. Surface 21 is parabolic. FIG. 22 is a section showing yet another modified radiant energy concentrating means made of silicon to pass infrared theThe series of facets in FIG. 1 is further characterized by existence of tapered gaps 23 between adjacent faces 24

(IR) rays; and 14 of the projecting portions of the facets. Faces 24 are FIG. 23 is a section showing a radiant energy transmitting 55 body means, as in FIG. 21a, directing converging light inactive surfaces, i.e., do not pass the radiation. See for example representative rays 25 and 26 in FIG. 1. Ray 25 is toward a light pipe; redirected by its associated facet almost 90° toward the FIG. 24 is a section showing a radiant energy transmitting target, near the outer edge 27 of the TIR lens 10. Study of means, directing diverging light as in a floodlight; FIGS. 1 and 4 will show that angle o (the bend angle of the FIG. 25 is a section showing a radiant energy transmitting ray) increases for facets increasing in distance from axis or means, directing light from a layer-stimulated sample to plane 18; and that angle B (the angularity of face 14 relative converge into a spectroscopic analyzer; to a line or plane parallel to line or plane 18) increases for FIG. 26 is a section showing a radiant energy transmitting facets increasing in distance from 18. Also, the entry faces means, directing light from a toroidal source; 12 form stairstep patterns.

FIG. 27 is a section like FIG.25 but showing provision of 65 FIG. 1 further shows a Fresnel lens 29 associated with a second lens, and a filter, in the path of collimated light or TIR lens or body 10, and located at a mid-portion of the radiation; latter; thus Fresnel lens 29, which refracts incident radiant

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energy toward target 15, is located in the path of rays 30, and may have other, curved shapes besides the straight lines which are redirected the least, i.e., at the Smallest angles, shown here, for the purpose of secondary concentration. toward the target. Lens 29 may be integral with lens 10, for Stray radiation from the diffuse sources, such as skylight, is example. absorbed by blackening the surface 153a of shroud 153 and Further, areflector or mirror surface is shown at 30 spaced of lens support fin at 130.

from and facing the facets at the target side thereof. Surface Various geometric configurations of elements and arrays 30 is arranged to reflect stray or divergentradiation from the of elements are possible, wherein various element configu extreme outward facets toward the target. See ray 31 in this faces,rations have the same relative angles of the three active regard, and reflection point 31a. This allows target 15 to but differing deployments within the transparent halve the area exposed to heat loss that it would have 10 means; e.g., the TIR face can be in faceted slots on either without surface 30, since the bottom non-illuminated half side of the body means or on the walls of tunnels within the could be well insulated. latter, while the entry faces can be on faceted steps or even Also shown in FIG. 1 is one form of means to controllably on a completely smooth cover surface.

tilt the assembly of lenses 10 and 29 and reflector 30 to cause 15 In FIG. 4a, tunnel 40 forms TIR face 41, while exit face axis 18 to remain directed towardarelatively moving source 42 has stairsteps 42a and 42b. In FIG. 4b, slot 50 is on the entryside of the body means, having TIR face 51 and entry of radiation, as for example the Sun. In that example, a base plate 32 supports reflector 30, as well as the dome-shaped face 54. Exit face 52 has stairsteps 52a and 52b. In FIG. 4c, lens 10 and 29, via extreme outer edge portion 10a of the tunnel 60 forms TIR face 61, and entry face 62 and exit face body means 10. Aring gear 33 supports plate 32, and meshes 20 64 are on Smooth continuous surfaces. However, TIR face with spur gear 34. Drive motor 35 rotates gear 34 to 61 must be longer than TIR faces 41 of FIG.4a or 51 of FIG. controllably rotate ring gear 33, and control unit 36 controls 4b, because of the refractive bending of ray 63 by entry face motor 35. Unit 36 is responsive to photocells 37 and 38 in 65 62. In general, the length of a TIR face relative to facet width

such manner that the photocells remain directed toward the light source. The photocells are suitably carried at 99 by the 25 TIRLENGTH=cos 8/(cosm cosm) where m is the incident plate 32, as for example near its periphery. angle of ray 63a with surface normal 66, 8 is the angle Target 15 may for example comprise a fluid receptacle of the refracted ray 63b with 66, K the incident angle of which is heat conductive, to transmit heat to fluid in the reflected ray 63c with exit surface normal 67, and the receptacle, as for example water in a pipe. angle of refracted by 63d with 67. The relationships of In FIGS. 2 and 3, the numerals 100 and 129 designate 30 these angles are given by Snell's law: lenses corresponding to lenses 10 and 29 described above. wheresinn m=n is sin 6, and sin =n sin K the index of refraction of the body means

They are elongated in the direction of arrow 149 and are material. For contiguous carried by supports indicated at 150 and 151. V-shaped the parallel rays incident elements upon to redirect to a target all them, neighboring elements shroud 152 has edge portions 152a connected to the opposite must be relatively positioned everywhere edges of lens body 100, so that the shroud and lenses define 35 parabola with the target as its focus and a rimonslope or above a equal to an enclosure.

A second and insulative tubular shroud 153 extends half the rim angle (i.e., the redirective bend angle of the outermost elements).

within that enclosure, about a tank 154 which has fixed In FIG. 4d, "extreme" ray 16c must clear tip 22 of the (nonrotatable) position. A support for the tank may take the inward adjacentfacet, while the other extreme ray, 16b, must form of legs indicated at 155 and 156, bearings being 40 clear top 27 of slot 23. These clearance conditions require provided at 157 and 158 to allow tank and shroud rotation that the lens slope anglem be greater than or equal to the TIR about central axis 159, along with the lens assembly. The tilt angle, which is geometrically equivalent to tangent line shroud 153 is cut-away at locations 160 and 161 to allow 22 being on or above the parabola.

entry of radiant energy from the lens assembly, to be Note that all of the configurations of FIG. 4 have the same absorbed by the tank, while heated air is prevented from bend angle O, and except for FIG. 4c, the same normal entry escaping gap 162 by wipers 163; the enclosure has a and exit faces. See for example the elements 311 of the reflecting interior surface 152b. "cover”310 in FIG. 5, above the parabola 321 tangent to the Cool liquid, such as water, enters the tank via pipe 164, is tips 322. See also line 324. Those tips below the parabola, heated therein, and discharges into the tank lower end at such as for a quarter-circle 325 with the same slope at the 164a. Warmed liquid slowly flows at 200 backup the tank, rim, would in this stairstep configuration suffer some inter being further heated by contact with the exterior of pipe 164, element impingement, about 10% for both cylinders and the liquid leaving the tank at outlet 165. A sacrificial anode spheres. But the use of a thin, flexible, inflatable dome for 166 in the water 200 is adapted to corrode, electrolytically a transparent cover means might be worth such a loss, suppressing any corrosion of the tank itself. Also, a back-up especially since the untargeted rays would still be redirected heater 167 in water 200 is supplied with electrical current to 55 to a locus within the cover means, to assist the pressurization heat water in the tank as when solar radiation is blocked or by heating the enclosed air. See FIG. 11 for a non-impinging non-existent, as at night. An air-gap may be provided at 162 circular configuration.

between shroud 153 and the tankitself. Sun tracking mecha An alternative facet style seeks to minimize such nism is indicated at 170, to rotate the assembly to maintain impingement losses by concentrating the rays before they the sun's rays incident normally toward the lenses 100 and strike the TIR face, which can thereby be smaller to reduce 129, i.e., in direction 171 in FIG. 3. said impingement. Convex and concave entry and exit faces In operation, all radiation directed parallel to arrow 171 will do this, though with some decrement of the cover's and striking the lenses 100 and 129, is redirected toward the concentration ratio or acceptance angle, which for some tank, as facilitated by gaps 160 and 161, to heat the liquid in applications is far outweighed by bringing the transparent the tank. Also note windows 162 and 163. Wide angle, i.e., 65 redirecting means even closer to the target. almost 180°, collection of the solar rays is employed, as For the Smallerbend angles, difficulties are encountered in described above in FIG.1. The gap walls 153a are reflective, the narrowness required of the tunnels or slots 23 in FIG. 4d

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forming the TTR faces of the low bend-angle elements. This zone. Radiant energy emitted by the source means 430 is can be somewhat alleviated by raising the profile of the redirected by the body means 435 (like 10 or 310) in reverse transparent means 310 above the parabola 321 to widen the relation. See ray 436.

slots and tunnels beyond their minimum widths. Another FIGS. 10a and 10b show two variations of a "uni-bend" form of such an alleviation is a backbending exit face, 311 lens with uniform facets extending annularly about a cylin of FIG. 5, so angled that its refractive redirection opposes drical target. In FIG. 10a, all the facets 444 of conical body the redirection of the TIR face, which can thereby have a means 440 bendrays 443 through 90° onto cylindrical target greater redirective bend angle with a less steep slope, giving 441. In FIG. 10b, flat body means 445 has identical facets wider tunnels or slots. 448 bending rays 447 through 45° upon cylindrical target In FIG. 5, note that ray 330 strikes the exit face 11 1.O 446.

non-normally, so that ray 330a is bent back toward the target. This enables a wider slot 323 than if the exit face was 461FIG. 11 shows a structural means 460 enclosing the space normal and the TTR face was at a steeper angle. The 310), so thatthe behind exit face of the cover means 459 (like 10 or pressurization of the atmosphere of space 461 above-mentioned convex entry face will also widen the slots will hold the flexible cover means in its distended or circular or tunnels.

Another method of widening the slots is the faceted exit 15 shape, with center of curvature at point 426. See target Zone face, shown in FIG. 4e. Here slot 70 has been opened until 462, pressurization means such as a pump 463 and ray 464. it nearly impinges upon extreme ray 73b. Exit face 74 has A thin film 465 adheres to the inside of cover means 459, miniature stairsteps 74a and 74b, respectively normal to and having miniature sawtooth facets 467 as shown in the insert. parallel to reflected ray 73b. Alternatively, a thin, micro FIG. 12a shows a plurality (two for example) of target structured series of elements of high refractive index (say zones 470 and 471 to receive radiant energy from the n=4) can be embedded in the body means to form more transmitting body means 472 (like 10 or 310). Each element favorably shaped elements. The particular manufacturing 473 redirects energy in a plurality of directions, toward the method and design application will determine the place of target zones. Thus, each element 473 may be like element 10 transition to a Fresnellens, or alternatively to a window, that or 310 described above but have a TIR face divided into two passes rays to a small parabolic reflector below the target, 25 sub-faces 474 and 475 at slightly different angles to accom which is thereby illuminated from a full circle of directions. plish the reflection of the two rays 476 and 477, respectively Another possible configuration would have the outer parts directed by the faces 474 and 475 toward the two target of the redirecting means sending radiant energy to a central ZOCS target, while the inner parts redirected energy to outer targets In FIG. 12b, TIR face 453 is the exit face for ray 451; using only large bend angles throughout. All these configul 30 while TIR face 454 is the exit face for ray 452. This rations are derivatives of the basic method of this invention: symmetrical case of twin 60° bends may be varied to give upon multiple TIR-transmitting elements, properly placed two different right and left hand bends, with differing entry, exit, and TIR faces redirect radiant energy to a division of the incoming radiant energy. predetermined target zone, or into a predetermined target In FIG. 13, the cover means 480 (like 10 or 310) has Solid angle. 35 different groups of elements redirecting radiant energy Also usable is a cover means (as at 10 or 110) whose focal toward different target zones. Thus, the elements at locus length can be shorter than any parabolic mirror with con 481 direct radiant energy toward target 482; and the ele centrations twice as high, but which is free from shading and ments at locus 483 direct energy toward target 484. See rays presents a convex surface with lower aerodynamic drag than 485 and 486.

the concave parabolic mirror. Its target is near the center of In FIG. 6, cover or body means 510 corresponds to 10 or gravity and closer to the ground than that of the parabolic 310 described above. A secondary radiant energy redirecting reflector making fixed receiver means easier to design and means is provided at 520 to intercept the radiant energy from maintain. Finally, the nearly 100% reflective efficiency of body 510 and to redirectit. Seerays 521 with segments 521a the TIR faces give much greater potential for high efficien falling on body 510; redirected segments 521b falling on cies than does the parabolic mirror. 45 body 520; and secondarily redirected segments 521c trans In FIGS. 1 and 5, it will be understood that the elements mitted by body 520.

11 and 311 join together, integrally and continuously, to FIG.7 shows body 520 in detail, with entry faces 530, exit form a radiant energy transmitting means in the general form faces 531, and TIR faces 532. The rays 521c are parallel, in of a cover. The latter has an energy entry surface (top surface this instance, i.e., collimated, so that means 520 may be in FIG. 1, for example) and an exit surface (bottom surface 50 regarded as a collimator.

in FIG. 1) lying on opposite sides of the cover. The cover The means 550 shown in FIG, 14 is like 10 and 300, causes radiant energy leaving the exit surface to have a except that the exit faces 551 are individually angled relative generally different direction than the direction of energy to radiant energy passing through them, so as to cause incidence on the entry surface. Also, multiple TIR faces are reflective redirection of the radiant energy. See beam 552 situated on the exit surface adjacent slots proximate the exit 55 refracted at face 551. Also in FIG. 14, the exit faces 551 may surface, as referred to above. The entry surface has a faceted be considered to refractively redirect radiant energy in stairstep configuration. The exit surface of the cover lies partial opposition to the redirection by the TIRfaces 553, the beyond and further from the target than a parabola (see 21 latter extending at less steep angles (than in FIGS. 1 and 5) and 321). The cover may be constructed of transparent so as to widen the slots 554. Note also in FIG. 14 that the material, as for example plastic. entry face is smooth and unfaceted, at 556, and that exit face FIG. 8 schematically shows a means 410 corresponding to 551 is parallel to refracted ray 552b, giving the maximum the means 10 of FIG. 1 or 310 of FIG. 5, or equivalent. A backbend and the lowest possible slope of entry surface 556, target zone is shown at 415. A retro-reflector means 412 is which in fact is lower than the parabola 321 or the quarter spaced behind and facing the target zone so as to redirect circle 325 in FIG. S.

radiant energy upon the target Zone. See ray 413. 65 In FIG. 15, the body means 560 is like that at 10 or 310, FIG. 9 schematically shows a radiant energy source except that it utilizes the variation index of refraction that means (as for example a light source) at 430 at the target varies with the wavelength of the radiant energy, so as to

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constitute a wavelength separating, radiating energy -continued redirecting, transmitting body means. Two target zones 561. flat COWex COC2VC and 562 are shown, and are spaced apart to receive different wavelengths of the wavelength separated, redirected, radiant B energy. See incident ray 563 which separates into ray 563a of one wavelength directed toward target 561, and ray 563b entry face exit face

of another wavelength directed toward target 562. TR face x Also in FIG. 15, either target may be considered as a C means to convert radiant energy to electricity. One such means is a photovoltaic cell. Such a device may be located entryface face X at the target zones in FIGS. 1 and 5. In FIG. 15, one target exit TR face

may comprise a photoillumination means receiving visible wavelengths; and the other target may comprise a thermal receiver receiving invisible wavelengths at zone 561. In FIGS. 19a, 19b and 19e, the bodies 650, 660 and 670 When a source of radiant energy is placed in zone 562, the 15 21.are closely similar to body 740 shown and described in FIG. visible wavelength rays will follow the reverse path of rays so that The angularities of the annular facets are slightly varied, 563, i.e., be collimated, while the invisible longer wave body 650theproduces body 660 produces collimated light rays 664; converging light rays at 654; and a body length heat rays will be diverged more outward from the 670 produces diverging visible beam, so that spotlights on actors will not subject each case is shown at 680.light In rays 674. The light source in each case, the top surface 659, them to a heat load several times greater than that of the 20 669, and 679 of the lens is circularly curved in the section visible radiation. shown, or spherically curved for an annular lens. Certain aspects of FIGS. 1-15 were also discussed in prior In FIG. 20, lens body 700 acts as a converging TIR lens, U.S. Pat. No. 4,337,759. in the same manner as lens 650 in FIG. 19a. Its performance FIG. 16 may be considered to correspond generally to is superior because of its full flashing, which gives more FIG. 4a or FIG. 4b, i.e., to present a lens body 600 having 25 effective focusing, and higher profile, and which leads to an entry face 601, a TIR face 602, and an exit face 603 on Smaller angular magnification of the light source, and a the body 600. Such faces 601 and 603 may be faceted, as in smaller focal spot. Upper light ray 701 and lower light ray the styles shown in FIGS. 1, 3, 7, 8, 9, 10, and 13. Rather 702 are the defining rays for the calculation of the angles of than all such faces being flat, face 601 is convexly curved, 30 the boundaries of facet 703 and of the position of inwardly away from the body 600, as shown; whereas faces 602 and adjacent facet 704. The slope of lens profile line 705 is to be 603 are flat, as previously described. Diverging entry rays maximized. The defining rays are generally diverging but 605 are refracted at 605a for reflection at 605b, and travel at can come from different parts of the light source; for 605c toward face 603. The rays pass through exit face 603 example, upper ray 701 comes from the bottom of the light and are in general refracted to travel externally at 605d, as 35 source, while lower ray 702 comes from the top of the light shown. If exit face 603 was convexly curved, then rays 605d source, so that they constitute the extreme rays of all light could be converging. The curvature of entry face 601 emitted by the source.

eliminates the divergence and keeps any rays from missing If the facet-defining upper and lower rays are not the TR face 602. extreme rays of the light source, then some fraction of its In FIG. 17, entry face 611 is flat, as is exit face 613; rays. output light will be redirected by the lens into the output however, TIR face 612 is concave toward the incident ray this Such a case may occur if there is a tradeoff between side of that face, as shown. Diverging entry rays 615 pass fraction and the tightness of the focusing, to be resolved through face 611 and travel at 615a, within body 610, for by the particular application of the lens.

reflection at 615b, at different points and angles, for travel at Facet 703 is defined by notch 703n (shown here as a 615c toward face 613. The rays pass through that face, and 45 fillet), tip 703t, upper point 703u of entry face 706, and on are in general refracted, and travel externally at 615d, as exit face 707, outer point 706o and inner point 706i. shown. The curvature of the TIR face 612 has made rays Inwardly adjacent facet 704 provides three limiting points that act analogously to pupils of conventional optical sys 615d parallel, while restricting the amount of exit face 613 tems: tip 704t defines upper ray 701, while both notch 704n that is used, enabling the entire lens to have a higher profile.

In FIG. 18, entry face 621 is flat, as is TIR face 622; 50 The convexexitcurvature and outer face 704o must be cleared by lower ray 702.

of entry face 706 accommodates the however, exit face 623 is concave away from the body 620, divergence of the defining rays by assuring that upper ray i.e., away from TER face 622, as shown. Entry rays 625, 701 does not miss TIR face 708 and that lower ray 702 does which may be parallel, pass through face 621 and travel at miss notch 704n.

625a, within body 620, for reflection at 625b at different For the sake of diagrammatic clarity, exit face 707 is points and angles, for travel at 625c toward face 623. The 55 relatively rays then pass through that face and are in general refracted distant exitclose to TIR face 708. A thicker lens with a more to travel externally at 625d, as shown. Exit face 623 is fully TIR face 708c) towouldface employ convex curvature (as on the assure that the defining rays do not miss flashed, as would be desirable for a converging TIR lens. the edges of exit face 707. If they did miss, they would not Other possibilities are as follows: be lost, since they would totally internally reflect on riser faces 709 or 710, and enter the lens output with only modest flat convex concave angular errors. Riser face 709 is angled to just clear lower ray 702, after it has left the lens. Optically inactive face 711

A. is kept at a minimum draft angle determined by the manu entry face facturing method (for injection molds, it is typically 2 off exit face K 65 the mold-pulling direction). Face 711 assists maximizing of lens profile by enabling entry face 706 to be angled more downward than is the case with lens 650 of FIG. 19a, where

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there is a straight line between a facet tip and the notch of 770 refracts rays, as shown. The arc light source at 764 may the inwardly adjacent facet. be produced by anode and cathode elements 764a and 764b. In summary, a unique determination of the four angulari Top exit surface 759 is circularly curved in the section ties of the facet (three for its faces and one for the lens shown; but the lens may have external, stairstep faceting. profile) requires four conditions: (1) overall bend angle; (2) Protective transparent envelope 769 keeps outside air away upper ray falling on the TIR face; (3) lower ray clearing from the arc.

notch of the inwardly adjacent face; and (4) lower ray In FIG. 23, the body means 780 may have the same or clearing the outer edge of exit facet of the inwardly adjacent similar facet. The curvatures of the three optically active faces of the directingconstruction convergent as that of FIG. 19a, for producing and light at 781 into the entrance end 782 facet are individually determined: 10 of a light pipe 783. The lens has an upwardly convex arcuate 1) entry-face curvature helps to maximize the slope of the upper exit surface or face 785, an entrance face or faces 786, lens profile line, by allowing the tip of the inwardly and a TIR face or faces 787. Faces 786 and 787 taper adjacent facet to rise while keeping the higher upper downwardly toward plane 790, corresponding to plane 710 ray from missing the TIR face (this reduces the diver in FIG. 21. A central light source 788 is positioned in the gence of the output light of the inner facets of the lens 15 manner of the LED in FIG. 21. A planar back mirror 789 by increasing their height above the source); extends in plane 790 corresponding to plane 710 and faces 2) TR-face curvature also helps to maximize lens slope upwardly. This device may input up to 80% of the light into by allow the notch of the inwardly adjacent facet to pipe 783, rather than 10% of the light as via a conventional rise; in addition, TIR-face curvature enables the exit ellipsoidal reflector.

face to be fully flashed, an important characteristic for 20 In FIG. 24, the body means 800 may have the same or several illumination applications; similar construction as that of FIG. 21c. Circularly curved 3) exit-face curvature minimizes the size of the focal spot top surface 801 is curved downwardly. The lens axis, in the of converging TIR lenses, and minimizes the beam case of an annular set of facets, is indicated at 802. Facets divergence of collimating TIR lenses. are seen from 803 to 812. Atypical annular facet 809 has an Non-circular profiles of these curved faces may be selected 25 entrance face 809a and a TIR face 809b. Note ray 820 path in order to provide uniform illumination by the facet. passing through face 809a and face 801, and totally reflected In addition, all the facets of the lens could be designed to at face 809b. In the section shown, each of the faces 809a have the same size focal spot, which would then be uni and 809b is flat. All entry faces have draft in the direction formly illuminated. This discussion of FIG. 20 may be 822, for ease of molding. The lens is transparent and may considered an important aspect of the invention, improving 30 consist of molded plastic material. over or not suggested by, subject matter of U.S. Pat. No. A light source 825 is located on axis 802, and just above 4.337,759. the plane 826, is within the confines of the hollow lens, as In FIG. 21, the axis of the annular, radiant energy trans in the above examples; and the rays 827 emanating from mitting body 740 appears at 751. The body has multiple face 802 diverge, as in a floodlight application. The circular annular facets 742 to 746 which are generally concentrically 35 section half-angle subtended by the surface 801 is typically arranged but having tips 742d to 746d progressively closer less than 45° and greater than 25°, and is typically about 35. to plane 750 normal to axis 751. Face 742a of facet 742 is In FIG. 25, lens body 850 is the same as that of FIG.21a, convex toward face 742b; and face 742b is concave toward except that the central refractive means has been replaced by face 742a in the section shown. This relationship obtains for microscope objective 854, which can slide axially inside the other facets, as shown. lens to focus on sample 851. Characteristic diffuse (i.e., in all A light-emitting diode (LED) 758 is located at the inter directions) emission 856 from sample 851 is collected by section of plane 750 with axis 751 and emits light rays lens 850 and focused on analyzer entrance slit 852. Colli toward the body 740. Ray 753 passes through face 742a, is mated laser beam 855 is reflected by mirror 853 into refracted toward TDR face 742b and is reflected toward and objective 854 and focused on sample 851. Mirror 853 is passes through upper flat face 748. See also ray 752 passing 45 removable in order to use microscope objective 854 to view through face 743a, reflecting at TIR face 743b, and passing sample 851 and exactly adjust its position. Lens body 850 through upper face 748a, angled as shown. All rays passing could extend downward below sample 851 to collect even upwardly beyond faces 748 and 748a are collimated. The more of the diffuse emission. Sample 851 may be a glass transverse width of the body 740 may be from 0.12 to one capillary containing a gas or liquid, a gold hemisphere inch, for example, and the transparent body 740 may consist 50 coated with a sample substance, an integrated circuit on a of molded plastic material. A refractive section without production line (checking material composition or facets appears at 719. Smallerratios of lens diameter to LED contamination), or a biological tissue sample. size may have outermost facets large, and successively In FIG. 26, lens body 860 has a cross-section with axis inward facets smaller, in order to have a higher lens profile 863, in order to accommodate toroidal (typically and better collimation curved facets are necessary for. 55 fluorescent) light source 861. Beneath this lamp is annular In FIG. 22, the radiant energy transmitting body 760 may involute reflector 862, with disc-shaped, planar mirror sec have the same general construction as shown in FIGS. 20 tion 864 inside it and annulus mirror 86.5 outside it. Annular and 21. The lens body 760 consists of silicon, or a similar lens 866 refracts ray 868, which was reflected from involute material, for passing infrared rays, but blocking visible light 862. Ray 869 is exactly analogous to ray 820 in FIG. 24. Ray rays, while transmitting infrared rays. An arc lamp radiant 867 is redirected by facet 870. The overall device of lamp, energy source is shown at 764, at the same position as the lens, and reflector comprise a compact floodlamp that offers LED in FIG. 20. much narrower divergence and much higher efficiency than A reflector surface 765 may be employed to extend in possible with the prior art of reflector design. plane 766 corresponding to plane 750 in FIG. 21 with a Referring now to FIG. 27, the lens body 950 is the same parabolic section 762. The infrared rays emanating at 767 65 as shown in FIG. 19b or as in FIG. 25, modified to collimate are typically collimated but may be divergent or convergent, light or a laser beam, supplied as indicated at 955. A light as in FIGS. 19a and 19C. Note that unfaceted central section source or light-emitting target (laser for example) 951 trans

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mits light to faceted side of the TIR lens body 950, the latter brightness range, however, is well below the 200-2,000 redirecting the light rays, as shown by the broken lines 956 cd/cm range of incandescent filaments. and 980, to pass through first refracting lens means at Because of their small sizes, incandescent light sources surface 950a and emerge as collimated light at 955. Such can be used to make very narrow beams. But for light then impinges on and passes through the wavelength floodlighting, the intensity pattern of a toroidal TIR lens is selective filter 982 and then through a second lens means extremely compact and quite cost effective. 983 indicated in the example as a focusing Fresnel lens. The Fluorescent battery-powered lanterns are popular, but latter redirects or focuses light at 984 onto the sample, oran their light output is omnidirectional. With the toroidal TIR analyser, 952. lens, such lamps have much greater efficiency for area A wavelength-selective filter 982 is used to remove pas 10 lighting, while their compactness serves needs of sively scattered light of the collimated laser beam.955, while backpackers, campers, and plumbers, among others. For allowing passage of fluorescence wavelengths, such as those indoor gardening, ordinary fluorescent grow lights must generated in Raman spectroscopy, for stimulated emissions typically be levels. placed close to plants, to produce suitable at 952. The filter 982 extends in a plane normal to principal illumination are required; and

With the toroidal TIR lens, fewer lamps they can be elevated above the plants and axis 986 defined by the lens 950 and by lens 983, the filter 15 requiring normal incidence of light for good wavelength stillInbeanyeffective.

situation requiring highlight levels, a bank of

TIk selection, since the filter wavelength depends upon the angle of incidence. The filter typically removes the laser wave toroidal-lamp luminaires provides an energy-efficient alter lengths. The auxiliary or second lens means 983 can also act native to conventional fluorescent ceiling fixtures. Their to reduce any aberrations introduced by the annular TIR lens 20 total thickness, including power supply, would typically be 950. under two inches, enhancing their versatility. Two TIR Also shown, as in FIG. 27, is a microscope objective lens lenses on both sides of a full toroidal light source makes a 954 which can slide axially in a bore in lens 950, and focus competitive “wall-washer" lamp. Finally, the ability to dim auxiliary source light 965 onto the target or laser 951. Note the brightness of the lamp adds an attractive energy conser the cylindrical periphery 970 of 954 parallel to axis 986, and 25 vative feature. See brightness control 1055 in FIG. 28. sliding in bore 967 of lens 950. Ameans to adjustably move Reference is now made to FIGS. 30 and 31, showing a objective lens 954 axially is schematically shown at 968. modified toroidal (doughnut) shaped, fluorescent lamp, the Auxiliary source light 965 may be redirected by mirror 953, TIR lens offering a compact means of efficiently producing as shown, toward lens 954, for focusing onto the target 951.

Reference is now made to FIGS. 28, 28a, and 29. For 30 a floodlamp pattern hitherto unattainable with fluorescent toroidal (doughnut) shaped, fluorescent lamps, the TIR lens lamps. Note the toroidal fluorescent tube 1066 facing the offers a compact means of efficiently producing a floodlamp TIR lens 1067, like that shown at 1050 in FIG. 28. A cusp pattern hitherto unattainable with fluorescent lamps. TIR reflector is shown at 1068, to reflect back light from 1066 lenses have had either circular or linear symmetry about the back toward facets 1067a of 1067. The annular cusp reflec center of their cross sections, where the light source is 35 tor serves to optically "unroll” the bulb 1066 into a flat, located. A new approachistolocate a TIR lens 1050 over the washer-shaped ring. Its flashed area is shown in FIG. 31, tube 1051 of a circular fluorescent lamp, the lens formed by lower sweeping it around a circle over the center of the lamp's annularleft. This makes it optically equivalent to a flat, (washer-shaped) lamp, but now its light is emitted cross section and about axis 1057.

FIG. 28 shows the resulting lens, along with its toroidal on only one side, whereas the bare lamp emits light both fluorescent lamp. The outer diameter D of such a lens is ways-along its axis of symmetry.

generally twice that of its lamp; but its height is only Aoth The 1 to 2 lumens/cm’ of light emitted by the surface of of the lens diameter, for the device illustrated. the lamp is totally diffused, in that it goes into a-90° pattern, The fundamental performance of the toroidal TDR lens as which amounts to omnidirectional emission, when consid shown can be understood under the general optical principle 45 ering the circular shape of the lamp. In order to confine this of “the larger the lens, the tighter the beam". The configu light into a smaller angle to form a beam, the surface area of ration is a torus, with a planar mirror 1052 facing the TIR emission must be increased, at a minimum, by a factor of the lens facets 1050a. For comparison purposes, a current non-toroidal lamp has a major radius R=1.25 inches, a square a +30° of the sine of the half angle of the beam. For example, beam would need at least 1/sin30°=4 times the lamp

a luminance of 10,000 ft-L, or 3.4 candela per square surface area, for a total of 2000 cm, or a 10 inch radius. centimeter. The surface area of the lamp is half that of a full Thus, illumination within the beam is over twelve times torus (i.e., 21Rr=8.9in), although its projected area (47trr= brighter than from the bare lamp, since the lumens are 2.8 in) is the same as that of a full torus. The projected area confined to a small, solid angle (1 steradian). of the toroidal TIR lens, on the other hand, as seen in FIG. 55 A linear TIR lens, as seen at 1150 in FIGS. 32 and 33, is 28, is 19.6 in, seven times as much. At the center of the formed simply by sweeping a two-dimensional faceted illumination pattern of the lens, the illuminance is seven profile, such as shown in FIG. 32, in a direction, 1151 to times that of the lamp alone. form flat, prism faces defining the facets 1150a'. As shown In general, the gain of a TIR lens for a toroidal lamp is Rfr. in FIG. 33, an aperture lamp is a fluorescent lamp with part As a result, the light coming out of the lens has a somewhat of the glass envelope of the tube 1154 silvered, as at 1155, focused intensity pattern. FIG. 29 shows this pattern in percent relative to maximum (solid line), as a function of in this case half, to form a semi-cylindrical source. When it viewing angle off the lens axis, while the dotted line shows is mounted in the plane of planar mirror 1156, it appears to the cumulative intensity. the TIR lens 1150 as a cylindrical source, elongated in Fluorescent lamps have luminous efficiencies in the range 65 direction 1151.

of 50 to 65 lumens per watt, considerably superior to the There are two major fluorescent-lamp applications for the 10-20 lumens per watt of incandescent lamps. Their surface linear TIR lens: general illumination and backlights. The

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primary concern in the form is with efficiency, while for the TIR face angle P, and the interfacetangle Ras free variables. latter, it is uniformity of appearance. This leads to somewhat The angle P is selected to redirect the rays into a desired different design approaches and manufacturing methods. For pattern (as in FIG. 34), while the angle R is kept just large illumination, the TIR lens would be larger, have a curved enough that the TIR face is fully illuminated, but no more, profile, and be produced by extrusion for larger sizes. else efficiency is compromised by light that goes over the Smaller linear TIR lenses would be compression or injection TIR face instead of being redirected out the top of the lens. molded, and for LCD backlights would have a flat top. The uniformity criterion has two aspects: spatial and FIG. 34 shows the profile of a linear TIR lens 1150a for angular. At the top of the lens, there is a spatial pattern of backlighting, designed for a relatively small source. The top 10 illumination. The smaller the facets, the easier it is to remove 1150b is flat, so that no gaps appear between the illumination any pattern with diffusers. Angular uniformity refers to the patterns of each facet. This uniformity requirement also appearance of the lens when seen at a distance from a mandates very small radii in the notches at the top of each particular direction. That is, the entire lens may not be lit up TIR face. The rays shown are in the plane of the profile. This 15 with an image of the source. For example, FIG. 34 shows set of rays comes from a single point, in order to illustrate that viewing the lens normal to its top face will show a collimation by the lens. nearly completely light-filled lens. FIGS. 35a-35c, however, In a linear TR lens with a diffuse source, however, most show that viewing the lens at 45° to its length will reveal of the rays are not in the plane of the profile. These "skew" some dark Zones. Similarly, viewing the lens from off-axis rays, when projected onto the cross section, take somewhat 20 angles (right or left in FIG. 34) will show the entry faces as different paths, depending upon the particular lens profile. dark lateral transport of brightness by a diffuser will remove FIGS. 35a to 35c show three views of 45° skew rays. In this such patterns.

Another aspect of angular uniformity is the variation case, there is not much change in their projected paths. In general, some profiles have smaller differences than others across the lens of the angular range of the pencil of rays in how these skew rays behave, depending upon the differ 25 generated by each facet. This is a simple function of source ence between refraction at the entry and exit faces. Large geometry and the facet's distance from the source. Increas differences can cause rays to be trapped within the lens, by ing the height-to-width ratio of a non-tubular source can being totally internally reflected a second (undesired) time, reduce this non-uniformity, which is an inherent part of the at the exit face of the lens. This greatly reduces efficiency, 30 low profile of the TIR lens. FIG. 37 shows the apparent but can be alleviated by wrapping the fluorescent lamp with angular diameter of the source at several facets. In addition, Brightness Enhancing Film (BEF), which reduces the skew the facets nearer the center will have an output of somewhat ray angles to 35° and under. The BEF grooves go around the narrower angle, because there is only entry-face refraction, tube's circumference. In LCD backlights, a BEF would which In demagnifies the source's angular diameter.

conclusion, the linear TIR lens shows considerable reduce the angular output along the lenses' longitudinal 35 direction (i.e., perpendicular to the lens profile). This is promise for general fluorescent illumination. For LCD desirable because of the angular limits of the light an LCD required, and diffusersaand backlighting, it offers reduction in the number of lamps brightness-enhancing films are

Cal SC.

FIG. 36 illustrates the general form of a TIR facet. Aray useful.

is shown with all the angles at which it encounters the facet, Other forms of TIR lens, as disclosed herein, can be Net refraction by a facet exists when the external incidence employed We with fluorescent lamps.

claim:

angle A is greater than E (consequently, the internal angle B is greater than D). Just as a TIR lens facet without net 1. A luminaire, comprising, in combination: refraction has no astigmatism or chromatic aberration, so 45 a) lengthwise a TIR lens having multiple facets, and extending along a first arc, and also does it lack skew-ray deflection. That is, the ray shown b) a light source facing said TIR lens and extending in FIG. 36 could, in a linear lens, beat some arbitrary angle lengthwise along a corresponding second arc spaced to the plane of the paper. The greater the difference between from said first arc,

A and E for the meridional (i.e., in-plane) ray, the more a 50 c) said first arc defining a first looping path, and said skew ray will differ from the meridional ray. Consequently, second arc defining a second looping path, the beam generated by skew rays will not be the same as that d) said first looping path having a first overall diameter at of the meridional rays. In fact, with enough net refraction, the locus of an outermostfacet, and said second looping skew rays beyond about 40° out of plane will be trapped in path having a second overall diameter, said first overall the lens. Net refraction is thus a key design consideration for 55 diameter being at least about twice said second overall linear TIR lenses. diameter.

Design methods developed to reduce chromatic aberra 2. The combination of claim 1 wherein at least one of said tion in circular lenses can be applied to linear lenses to looping paths is toroidal.

reduce skew-ray aberrations. They are of particular interest 3.The combination of claim2 including a back-reflecting for illumination applications, but less so for backlighting, mirror positioned to reflect backlight from said source where uniformity is the paramount criterion. For toward said TIR lens, said mirror having one of the follow illumination, ease of manufacturing, optical efficiency, and ing shapes:

control of the illumination pattern are the primary criteria. i) flat

With linear TIR lenses used for backlighting, the lens 65 ii) cusp-shaped.

entry face is kept close to vertical, so that the existing rays 4. The combination of claim 1 wherein said second have no gaps, and the exit face is flat. This leaves only the looping path is annular.

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5. The combination of claim 1 wherein said light source 11. The combination of claim 10 wherein said perimeters comprises a fluorescent lamp, which is tubular. of said elements project from said cross section to extend 6. The combination of claim 5 wherein said second annularly about, and define a common axis, said entry faces looping path defines a central axis normal to a plane defined facing said incident radiant energy. by said second looping path, and said first looping path 5 12. A luminaire, comprising, in combination: extends about said axis. a) a TIR lens having multiple facets, and extending 7. The combination of claim 6 wherein a plane containing lengthwise along a first arc, and said axis intersects said TIR lens along two arcs and inter b) a light source facing said TIR lens and extending sects said tubular lamp at two circular cross sections toward 10 lengthwise along a corresponding second arc spaced which said TIR lens arcs are respectively concave. from said first arc, 8. The combination of claim 6 including a back-reflecting c) and including a back-reflecting mirror positioned to mirror positioned to reflect backlight from said source reflect backlight from said source toward said TLR lens, toward said TIR lens. d) said mirror having a cusp projecting toward the light 9. The combination of claim 1 including a back-reflecting 15 source along its length along said second arc. mirror positioned to reflect backlight from said source 13. The combination of claim 12 wherein said TIR lens toward said TLR lens. comprises 10. The combination of claim 1 wherein said TIR lens a') a radiant energy transmitting body means, comprises:

a') a radiant energy transmitting body means, 20 b) said means comprising multiple elements, each of which acts as a radiant energy redirecting module, b) said means comprising multiple elements, each of having on its cross-sectional perimeter an entry face to which acts as a radiant energy redirecting module, receive incidence of said energy into the interior of said having on its cross-sectional perimeter an entry face to perimeter, an exit face to pass said energy to the receive incidence of said energy into the interior of said 25 exterior of said perimeter in a direction towards the perimeter, an exit face to pass said energy to the reverse side of the body from the side of said incidence, exterior of said perimeter in a direction towards the and a Totally Internally Reflecting face angled relative reverse side of the body from the side of said incidence, to said entry and exit faces to redirect towards said exit and a Totally Internally Reflecting face angled relative face the radiant energy incident from said entry face. to said entry and exit faces to redirect towards said exit 30 face the radiant energy incident from said entry face. ck. : :: * :