TIR lens for waveguide injection

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TIR LENS FOR WAVEGUIDE IN.JECTION art, and to provide a means to collect and employ radiant energy in a very cost-effective and efficient manner, using a

This application is a continuation-in-part of prior U.S. new basic tool with applications that include the collection, application Ser. No. 08/415,274 filed Apr. 7, 1995, now U.S. concentration, redirection, and wavelength separation of Pat. No. 5,577,492, issued on Nov. 26, 1996, which is a 5 radiant energy.

continuation-in-part of prior U.S. application Ser. No. The present invention, which improves over the Subject 07/869,003 filed Apr. 16, 1992, now U.S. Pat. No. 5,404, matter of U.S. Pat. No. 4,337,759, is basically characterized

by the use of a transparent means employing elements to

BACKGROUND OF THE INVENTION redirect radiant energy by means of TIR alone, or in con This invention relates generally to radiant, particularly junction with refraction, Such means positioned between the electromagnetic, energy concentration, redirection, and radiant energy Source and a receiver. Each element redirects manipulation, and improves over the Subject matter of U.S. radiant energy upon a common target Zone or Zones, during Pat. No. 4,337,759. It more particularly concerns apparatus the energy's internal passage through the element. A prop and method for employing a transparent lens means with erly oriented ray enters through the entry face and Strikes the elements thereof using Total Internal Reflection (TIR), in 15 reflective face, which redirects it toward the exit face, the conjunction with a focusing Second lens and a wavelength three faces comprising the active faces for that ray. In Selection filter, for use Such as in laser Spectrometry. addition, the lens means is associated with at least one of the Radiant energy is redirected to or from a predetermined faces for redirecting radiant energy passing between the Zone or Zones, Such redirection having a predetermined entry and exit faces via the TIR face.

degree of concentration and/or chromatic dispersion. The Accordingly, the present invention is characterized by the Zones have Sources of light, as in photoillumination, or passage of redirected radiant energy entirely through the 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 25 nation in general consists of two major types, as exemplified energyforms of concentrators that also has applications to other radiant energy redirection than concentration, Such by refractive and reflective astronomical telescopes: a as wavelength refractive lens positioned in front of a receiver or light the element mayseparation or collimation. Other Surfaces of Source, or a retro-reflective mirror positioned behind a in Solar energy concentration for be inactive

the ray of interest (e.g., as relatively parallel rays) but receiver or light Source. The corresponding devices in the 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 to passcover means, or Separated to allow undeflected light tracking) position with only Seasonal adjustments, but the 35 upon thebetween them, for example to be focused by a mirror disadvantage of requiring relatively large reflector areas and from all directions.the target, which is thereby illuminated back of 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 f/ratioS and bulky 40 directions, with or without wavelength Separation, which concentrator Structure. Moreover, linear Fresnel lenses 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 protective given diameter transparent means to be much closer to the transparent cover means about the receiver will merely target than a means limited to refraction alone, thereby reduce the System's optical efficiency. greatly reducing the necessary Support Structure. Another reflecting System has appeared in the literature, 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 or rim of the means, thereby doubling Solar concentration doubling intercept efficiency for a light Source.

two TIR faces to redirect radiant energy out the same side as 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 60 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. pletely independent of bend angle and can have any positive, The relative facet positions, as determined by the non Zero, or negative values desired for Such wavelength which interference criterion, determine the overall lens profile, Separation applications as Solar illumination or bandgap should be low or high depending upon the applica tailored photovoltaic cells. Unlike the parabolic reflector, the tion. In a Solar concentrator, the lens height should be redirective bend angle of an element is independent of its minimized toor reduce Spot size of the Solar image. In a location, greatly adding to design flexibility. (Since the converging collimating TIR illumination System, it is parabolic reflector is a Smooth continuum, there can be no advantageous to have Somewhat more lens height, So that the arbitrary variations in redirective bend angle from one spot apparent Size of the Source is reduced at the central facets, to a neighboring one.) 15 and the output beam is thereby tightened. This consideration The first of the present invention's improvements over the does not hold for diverging TIR lenses, because only efficiency, and not beam tightness, is required.

subject matter of U.S. Pat. No. 4,337,759 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 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 red lamps 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 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 Sources 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 40 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 TIR 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 vidualimage magnification that broadens the focal spot. The indi thermodynamic efficiency; and conveX curvature on each of the facet faces is vital to 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, facet inwards 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 60 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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S 6

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. powered fluorescent lanterns, which currently cannot pro Another advantage of the TIR lens for this application is vide any focusing whatsoever.

that it azimuthally Smears out any Structure in the Source, 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 art here 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 Vision new kind of infrared illuminator, as found in many night objectives typically have a focal length equal to their Systems.

diameter, so that they subtend about 50 and collect 5% of application The Superiority of the present invention can be seen in its the diffusely emitted output. 25 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 A TIR lens that redirects light from a source in order to mirrors, and more efficient focusing than ellipsoidal mirrors. Another object of the invention is to provide a radiant form a diverging cone of light, as in floodlighting energy redirecting System comprising: applications.

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. of the body from the side of the incidence, and a Totally Two types of linearly symmetric TIR lenses for cylindri 40 Internally Reflecting face angled relative to the entry and exit faces to redirect towards the exit face the cal Sources (Such as fluorescent tubes): radiant energy incident from the entry face, One that confines its output to a relatively narrow off-axis angle. With the prior art, this is possible only c) the body means generally redirecting incident radiant with quite deep and bulky reflectors. energy towards a predetermined target Zone situated One that reduces its on-axis output and enhances the 45 apart from and on the reverse side of the body relative lateral output, in order to produce uniform illumi to the Side of the incidence, nance on a nearby Surface that is being used for d) first lens means associated with at least one of the faces indirect lighting. Such a shape appears very different for redirecting radiant energy passing between the entry from other TIR lenses. and exit faces via the Totally Internally Reflecting face, Linear TIR lenses have somewhat of a handicap from 50 the redirected radiant energy being collimated, Sagittal ray internal reflection, whereby rays emitted from e) and Second lens means spaced from the exit face to the linear Source at a large out-of-plane angle with the lens receive the collimated radiant energy and to redirect croSS Section will encounter the exit face at a total incident Same toward the target Zone. angle that exceeds the critical angle for total internal reflec Yet another object of the invention is to provide a TIR lens tion. Most of the facet designs used in radially Symmetric 55 and waveguide System, wherein light passed by the lens is lenses will, when put into linear lenses, be Subject to this optically coupled into the waveguide. The lens and whenever the out-of-place angle exceeds 40, which encom waveguide may be directionally elongated and may taper in passes half of all rays emitted from a Lambertian, or that direction; and the TIR lens may couple between a light uniformly emitting, Source. This trapping of light within the Source, Such as an LED, and the waveguide. The waveguide lens can be remedied by corrugation along the outer face of 60 may comprise a plate having elongated edges, and the TIR the lens, which unfortunately precludes manufacturing by lens may extend adjacent Such an edge or edges. Multiple extrusion because the croSS Section is no longer constant. TIR lenses and associated LEDS may be located along Such Another method is binary optics outcoupling through min a Waveguide edge or edges, as Will appear.

iature Stepped patterns on the outside of the lens. These and other objects and advantages of the invention, A more useful lens design would be applied to a toroidal 65 as well as the details of an illustrative embodiment, will be fluorescent lamp. The TIR lens profile would have its axis of more fully understood from the following Specification and Symmetry over the circular croSS-Section of the toroidal drawings, in which:

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DRAWING DESCRIPTION DETAILED DESCRIPTION

FIG. 1 is a vertical section in elevation showing one form As described in U.S. Pat. No. 4,337,759, and referring to of apparatus embodying the invention; FIG. 1, radiant energy transmitting body means 10, in the FIG. 2 is a vertical Section in elevation showing another shape of a cover or dome, has multiple facets or elements as form of apparatus embodying the invention; at 11, each facet having an entry face to receive impinge FIG. 3 is an enlarged section on lines 3-3 of FIG. 2; ment of Such radiation, an exit face to pass energy to the FIGS. 4a-4e are enlarged sections through elements of relative toof the exterior the body, and an internal reflection face angled entry and exit faces to reflect radiant energy 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 1O example, in FIGS. 1 and 4d, a selected facet 11 has, in optical concentrator of Somewhat different and employed 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; 15 entering the body means 10 at flat face 12a and normal

FIG. 7 is an enlarged Section through a collimator as used 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, 10a, 10b, 11, 13, 14 and 15 are schematics reflected rays 16c then pass toward and through exit face 13, showing different applications of the radiant energy concen normal thereto, and directly toward the target Zone. trating means, 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 ments, 25 extend in parallel relation (normal to the plane of FIG. 1) at FIGS. 19a–19c. are sections producing light rays of vary opposite sides of a plane as alternatively represented by 18, ing angularity, as shown; and which is normal to the plane of FIG.1. In either event, FIG. 20 is a section of a facet with three curved faces, corresponding points on the facets define a concave Surface, illustrating the general principles of facet design; as for example at 21 (defined by the tips 22 of the facets 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 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 The series of facets in FIG. 1 is further characterized by energy concentrating means made of Silicon to pass infrared 35 the 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 inactive Surfaces, i.e., do not pass the radiation. See for body means, as in FIG. 21a, directing converging light 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 40 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 C. (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 f (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 45 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 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 FIG. 28 is an enlarged perspective view of a TIR lens which 50 energy toward target 15, is located in the path of rays 30, injecting light into a planar waveguide; are redirected the least, i.e., at the Smallest angles, toward the target. Lens 29 may be integral with lens 10, for

FIG. 29 is a side view of a planar waveguide, with TIR example.

lens facets at its edge, for injecting light from LEDS into the Further, a reflector or mirror surface is shown at 30 spaced waveguide, and showing light from the waveguide illumi 55 from and facing the facets at the target Side thereof. Surface nating a liquid crystal display; 30 is arranged to reflect stray or divergent radiation from the FIG. 30 is a perspective view of linear TIR lens facets extreme outward facets toward the target. See ray 31 in this extending edgewise of a planar waveguide; regard, and reflection point 31a. This allows target 15 to FIG. 31 is like FIG. 30 but substitutes multiple discrete halve the area exposed to heat loss that it would have TIR lenses arrayed along an edge or edges of a planar 60 without Surface 30, since the bottom non-illuminated half waveguide, could be well insulated.

FIG. 32 is an edge View of an elongated waveguide with Also shown in FIG. 1 is one form of means to controllably a TIR lens at one end thereof; tilt the assembly of lenses 10 and 29 and reflector 30 to cause FIG.33 is an enlarged endwise view of the FIG. 32 TIR axis 18 to remain directed toward a relatively moving Source lens, and 65 of radiation, as for example the Sun. In that example, a base FIG. 34 is a view like FIG. 32 showing the waveguide plate 32 supports reflector 30, as well as the dome-shaped having an optical fiber or rod continuation. lens 10 and 29, via extreme outer edge portion 10a of the

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body means 10. A ring gear 33 Supports plate 32, and meshes 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 62. In general, the length of a TIR face relative to facet width Such manner that the photocells remain directed toward the 65 is:

light source. The photocells are suitably carried at 99 by the TIR LENGTH =cos 8/(cos m cos m) where m is the plate 32, as for example near its periphery. incident angle of ray 63a with surface normal 66, 8 is Target 15 may for example comprise a fluid receptacle the angle of the refracted ray 63b with 66, K the incident which is heat conductive, to transmit heat to fluid in the angle of reflected ray 63c with exit surface normal 67, receptacle, as for example water in a pipe. and 2 the angle of refracted by 63d with 67. The In FIGS. 2 and 3, the numerals 100 and 129 designate relationships of these angles are given by Snell's law: lenses corresponding to lenses 10 and 29 described above. sin m=n sin 8, and sin W=n sin K They are elongated in the direction of arrow 149 and are carried by supports indicated at 150 and 151. V-shaped 15 where n is the index of refraction of the body means shroud 152 has edge portions 152a connected to the opposite material. For contiguous elements to redirect to a target all edges of lens body 100, so that the shroud and lenses define the parallel rays incident upon them, neighboring elements must be relatively positioned everywhere on or above a an enclosure.

A second and insulative tubular shroud 153 extends parabola with the target as its focus and a rim Slope equal to within that enclosure, about a tank 154 which has fixed half the rim angle (i.e., the redirective bend angle of the (nonrotatable) position. A Support for the tank may take the outermost elements).

form of legs indicated at 155 and 156, bearings being inward In FIG. 4d, “extreme' ray 16c must clear tip 22 of the provided at 157 and 158 to allow tank and shroud rotation clear topadjacent 27 of facet, while the other extreme ray, 16b, must slot 23. These clearance conditions require about central axis 159, along with the lens assembly. The that the lens slope angle m be greater than or equal to the TIR shroud 153 is cut-away at locations 160 and 161 to allow 25 tilt angle, which is geometrically entry of radiant energy from the lens assembly, to be 22 being on or above the parabola.equivalent to tangent line absorbed by the tank, while heated air is prevented from Note that all of the configurations of FIG. 4 have the same escaping gap 162 by wiperS 163; the enclosure has a bend angle C, and except for FIG. 4c, the same normal entry reflecting interior surface 152b. and exit faces. See for example the elements 311 of the Cool liquid, Such as water, enters the tank via pipe 164, is “cover”310 heated therein, and discharges into the tank lower end at tips 322. Seeinalso FIG. 5, above the parabola 321 tangent to the line 324. Those tips below the parabola, 164a. Warmed liquid slowly flows at 200 back up the tank, Such as for a quarter-circle 325 with the same slope at the being further heated by contact with the exterior of pipe 164, rim, would in this stairstep configuration Suffer Some inter the liquid leaving the tank at outlet 165. A sacrificial anode element impingement, about 10% for both cylinders and 166 in the water 200 is adapted to corrode, electrolytically 35

Suppressing any corrosion of the tank itself. Also, a back-up spheres; but the use of a thin, flexible, inflatable dome for a transparent cover means might be worth Such a loSS, espe heater 167 in water 200 is supplied with electrical current to cially since the untargeted rays would still be redirected to heat water in the tank as when Solar radiation is blocked or non-existent, as at night. An air-gap may be provided at 162 by a locus within the cover means, to assist the pressurization heating the enclosed air. See FIG. 11 for a non-impinging between shroud 153 and the tank itself. Sun tracking mecha 40 circular configuration.

nism is indicated at 170, to rotate the assembly to maintain An alternative facet Style seeks to minimize Such the Sun's rays incident normally toward the lenses 100 and impingement losses by concentrating the rays before they 129, i.e., in direction 171 in FIG. 3. strike the TIR face, which can thereby be smaller to reduce In operation, all radiation directed parallel to arrow 171 Said impingement. ConveX and concave entry and exit faces and striking the lenses 100 and 129, is redirected toward the 45 will do this, though with some decrement of the cover's tank, as facilitated by gaps 160 and 161, to heat the liquid in concentration ratio or acceptance angle, which for Some the tank. Also note windows 162 and 163. Wide angle, i.e., applications is far outweighed by bringing the transparent almost 180, collection of the Solar rays is employed, as redirecting means even closer to the target. described above in FIG.1. The gap walls 153a are reflective, For the Smaller bendangles, difficulties are encountered in and may have other, curved shapes besides the Straight lines 50 the narrowness required of the tunnels or slots 23 in FIG. 4d shown here, for the purpose of Secondary concentration. forming the TIR faces of the low bend-angle elements. This Stray radiation from the diffuse Sources, Such as Skylight, is can be Somewhat alleviated by raising the profile of the absorbed by blackening the surface 153a of shroud 153 and transparent means 310 above the parabola 321 to widen the of lens support fin at 130. slots and tunnels beyond their minimum widths. Another Various geometric configurations of elements and arrayS 55 form of Such an alleviation is a backbending exit face, 311 of elements are possible, wherein various element configu of FIG. 5, so angled that its refractive redirection opposes rations have the same relative angles of the three active the redirection of the TIR face, which can thereby have a faces, but differing deployments within the transparent greater redirective bend angle with a leSS Steep slope, giving means, e.g., the TIR face can be in faceted slots on either wider tunnels or slots.

side of the body means or on the walls of tunnels within the 60 In FIG. 5, note that ray 330 strikes the exit face 11 latter, while the entry faces can be on faceted Steps or even non-normally, so that ray 330a is bent back toward the on a completely Smooth cover Surface. target. This enables a wider slot 323 than if the exit face was In FIG. 4a, tunnel 40 forms TIR face 41, while exit face normal and the TIR face was at a Steeper angle. The 42 has stairsteps 42a and 42b. In FIG. 4b, slot 50 is on the above-mentioned convex entry face will also widen the slots entry side of the body means, having TIR face 51 and entry 65 or tunnels.

face 54. Exit face 52 has stairsteps 52a and 52b. In FIG. 4c, Another method of widening the slots is the faceted exit tunnel 60 forms TIR face 61, and entry face 62 and exit face face, shown in FIG. 4e. Here slot 70 has been opened until

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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 Fresnel lens, 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, 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 configu while TIR face 454 is the exit face for ray 452. This rations are derivatives of the basic method of this invention: 15 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. 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 25 310 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 redirect it. See rays 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. 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 regarded as a collimator.

in FIG. 1) lying on opposite sides of the cover. The cover 35 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 refracted at face 551. Also in FIG. 14, the exit faces 551 may Surface, as referred to above. The entry Surface has a faceted 40 be considered to refractively redirect radiant energy in Stairstep configuration. The exit Surface of the cover lies partial opposition to the redirection by the TIR faces 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 45 551 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. 5.

radiant energy upon the target Zone. See ray 413. In FIG. 15, the body means 560 is like that at 10 or 310, FIG. 9 Schematically shows a radiant energy Source 50 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 Zone. Radiant energy emitted by the source means 430 is constitute a Wavelength separating, radiating energy redirected by the body means 435 (like 10 or 310) in reverse redirecting, transmitting body means. Two target Zones 561 relation. See ray 436. and 562 are shown, and are spaced apart to receive different FIGS. 10a and 10b show two variations of a “uni-bend 55 wavelengths of the wavelength separated, redirected, radiant lens with uniform facets extending annularly about a cylin energy. See incident ray 563 which separates into ray 563a drical target. In FIG. 10a, all the facets 444 of conical body of one wavelength directed toward target 561, and ray 563b means 440 bend rays 443 through 90 onto cylindrical target of another wavelength directed toward target 562. 441. In FIG. 10b, flat body means 445 has identical facets Also in FIG. 15, either target may be considered as a 448 bending rays 447 through 45 upon cylindrical target 60 means to convert radiant energy to electricity. One Such 446. means is a photovoltaic cell. Such a device may be located FIG. 11 shows a structural means 460 enclosing the space at the target Zones in FIGS. 1 and 5. In FIG. 15, one target 461 behind the exit face of the cover means 459 (like 10 or may comprise a photoillumination means receiving visible 310), so that pressurization of the atmosphere of space 461 wavelengths, and the other target may comprise a thermal will hold the flexible cover means in its distended or circular 65 receiver receiving invisible wavelengths at Zone 561. shape, with center of curvature at point 426. See target Zone When a source of radiant energy is placed in Zone 562, the 462, pressurization means Such as a pump 463 and ray 464. visible wavelength rays will follow the reverse path of rays

Page 32

563, i.e., be collimated, while the invisible longer wave In FIG. 20, lens body 700 acts as a converging TIR lens, length heat rays will be diverged more outward from the in the same manner as lens 650 in FIG. 19a. Its performance Visible beam, So that Spotlights on actors will not Subject is Superior because of its full flashing, which gives more them to a heat load Several times greater than that of the effective focusing, and higher profile, and which leads to visible radiation. Smaller angular magnification of the light Source, and a Certain aspects of FIGS. 1-15 were also discussed in prior smaller focal spot. Upper light ray 701 and lower light ray U.S. Pat. No. 4,337,759. 702 are the defining rays for the calculation of the angles of FIG. 16 may be considered to correspond generally to the boundaries of facet 703 and of the position of inwardly FIG. 4a or FIG. 4b, i.e., to present a lens body 600 having adjacent facet 704. The slope of lens profile line 705 is to be an entry face 601, a TIR face 602, and an exit face 603 on maximized. The defining rays are generally diverging but the body 600. Such faces 601 and 603 may be faceted, as in can come from different parts of the light Source; for the styles shown in FIGS. 1, 3, 7, 8, 9, 10, and 13. Rather example, upper ray 701 comes from the bottom of the light than all such faces being flat, face 601 is convexly curved, Source, while lower ray 702 comes from the top of the light away from the body 600, as shown; whereas faces 602 and Source, So that they constitute the extreme rays of all light 603 are flat, as previously described. Diverging entry rays 605 are refracted at 605a for reflection at 605b, and travel at 15 emitted by the Source.

If the facet-defining upper and lower rays are not the 605c toward face 603. The rays pass through exit face 603 and are in general refracted to travel externally at 605d, as extreme rays of the light Source, then Some fraction of its shown. If exit face 603 was convexly curved, then rays 605d output light will be redirected by the lens into the output could be converging. The curvature of entry face 601 rayS. Such a case may occur if there is a tradeoff between eliminates the divergence and keeps any rays from missing this fraction and the tightness of the focusing, to be resolved TIR face 602. by the particular application of the lens. In FIG. 17, entry face 611 is flat, as is exit face 613; Facet 703 is defined by notch 703n (shown here as a however, TIR face 612 is concave toward the incident ray fillet), tip 703t, upper point 703u of entry face 706, and on Side of that face, as shown. Diverging entry rayS 615 pass exit face 707, outer point 7060 and inner point 706i. through face 611 and travel at 615a, within body 610, for 25 Inwardly adjacent facet 704 provides three limiting points reflection at 615b, at different points and angles, for travel at that act analogously to pupils of conventional optical Sys 615c toward face 613. The rays pass through that face, and tems: tip 704t defines upper ray 701, while both notch 704n are in general refracted, and travel externally at 615d, as and outer exit face 704O must be cleared by lower ray 702. shown. The curvature of the TIR face 612 has made rays The convex curvature of entry face 706 accommodates the 615d parallel, while restricting the amount of exit face 613 divergence of the defining rays by assuring that upper ray that is used, enabling the entire lens to have a higher profile. 701 does not miss TIR face 708 and that lower ray 702 does miss notch 704n.

In FIG. 18, entry face 621 is flat, as is TIR face 622;

however, exit face 623 is concave away from the body 620, For the sake of diagrammatic clarity, exit face 707 is i.e., away from TIR face 622, as shown. Entry rays 625, relatively close to TIR face 708. A thicker lens with a more which may be parallel, pass through face 621 and travel at 35 distant exit face would employ convex curvature (as on the 625a, within body 620, for reflection at 625b at different TIR face 708c) to assure that the defining rays do not miss points and angles, for travel at 625c toward face 623. The the edges of exit face 707. If they did miss, they would not rays then pass through that face and are in general refracted be lost, since they would totally internally reflect on riser to travel externally at 625d, as shown. Exit face 623 is fully faces 709 or 710, and enter the lens output with only modest flashed, as would be desirable for a converging TIR lens. 40 angular errors. Riser face 709 is angled to just clear lower Other possibilities are as follows: ray 702, after it has left the lens. Optically inactive face 711 is kept at a minimum draft angle determined by the manu facturing method (for injection molds, it is typically 2 off flat COWCX COCaWe the mold-pulling direction). Face 711 assists maximizing of 45 lens profile by enabling entry face 706 to be angled more

A downward than is the case with lens 650 of FIG. 19a, where entry face X there is a Straight line between a facet tip and the notch of exit face X the inwardly adjacent facet.

TIR face

X In Summary, a unique determination of the four angulari 50 ties of the facet (three for its faces and one for the lens entry face X profile) requires four conditions: (1) overall bend angle; (2) exit face X upper ray falling on the TIR face; (3) lower ray clearing TIR face

notch of the inwardly adjacent face; and (4) lower ray clearing the outer edge of exit facet of the inwardly adjacent entry face X 55 facet. The curvatures of the three optically active faces of the exit face X facet are individually determined:

(1) entry-face curvature helps to maximize the slope of the lens profile line, by allowing the tip of the inwardly

In FIGS. 19a, 19b and 19c, the bodies 650, 660 and 670 adjacent facet to rise while keeping the higher upper are closely similar to body 740 shown and described in FIG. 60 ray from missing the TIR face (this reduces the diver 21. The angularities of the annular facets are slightly varied, gence of the output light of the inner facets of the lens so that the body 660 produces collimated light rays 664; by increasing their height above the Source); body 650 produces converging light rays at 654; and a body (2) TIR-face curvature also helps to maximize lens slope 670 produces diverging light rays 674. The light source in by allow the notch of the inwardly adjacent facet to each case is shown at 680. In each case, the top surface 659, 65 rise; in addition, TIR-face curvature enables the exit 669, and 679 of the lens is circularly curved in the section face to be fully flashed, an important characteristic for shown, or spherically curved for an annular lens. Several illumination applications,

Page 33

(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. A typical annular facet 809 has an Non-circular profiles of these curved faces may be entrance face 809a and a TIR face 809b. Note ray 820 path selected in order to provide uniform illumination by the passing through face 809a and face 801, and totally reflected facet. at face 809b. In the section shown, each of the faces 809a In addition, all the facets of the lens could be designed to and 809 b is flat. All entry faces have draft in the direction have the same size focal Spot, which would then be uni 822, for ease of molding. The lens is transparent and may formly illuminated. This discussion of FIG. 20 may be consist of molded plastic material. considered an important aspect of the invention, improving A light source 825 is located on axis 802, and just above over or not suggested by, Subject matter of U.S. Pat. No. 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 15 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 TIR 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 removable in order to use microscope objective 854 to view through face 743a, reflecting at TIR face 743b, and passing 25 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 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. Smaller ratios 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. fluorescent) light source 861. Beneath this lamp is annular In FIG.22, the radiant energy transmitting body 760 may 35 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 865 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 40 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 as shown in FIG. 19b or as in FIG. 25, modified to collimate are typically collimated but may be divergent or convergent, 45 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 770 refracts rays, as shown. The arc light source at 764 may mits light to faceted side of the TIR lens body 950, the latter be produced by anode and cathode elements 764a and 764b. redirecting the light rays, as shown by the broken lines 956 Top exit surface 759 is circularly curved in the section and 980, to pass through first refracting lens means at shown; but the lens may have external, Stairstep faceting. 50 surface 950a and emerge as collimated light at 955. Such Protective transparent envelope 769 keeps outside air away light then impinges on and passes through the wavelength from the arc. selective filter 982 and then through a second lens means In FIG. 23, the body means 780 may have the same or 983 indicated in the example as a focusing Fresnel lens. The similar construction as that of FIG. 19a, for producing and latter redirects or focuses light at 984 onto the sample, or an directing convergent light at 781 into the entrance end 782 55 analyser, 952.

of a light pipe 783. The lens has an upwardly convex arcuate A wavelength-selective filter 982 is used to remove pas upper exit surface or face 785, an entrance face or faces 786, sively scattered light of the collimated laser beam 955, while and a TIR face or faces 787. Faces 786 and 787 taper allowing passage of fluorescence wavelengths, Such as those downwardly toward plane 790, corresponding to plane 710 generated in Raman spectroScopy, for Stimulated emissions in FIG. 21. A central light source 788 is positioned in the 60 at 952. The filter 982 extends in a plane normal to principal manner of the LED in FIG. 21. A planar back mirror 789 axis 986 defined by the lens 950 and by lens 983, the filter extends in plane 790 corresponding to plane 710 and faces requiring normal incidence of light for good wavelength upwardly. This device may input up to 80% of the light into Selection, Since the filter wavelength depends upon the angle pipe 783, rather than 10% of the light as via a conventional of incidence. The filter typically removes the laser wave ellipsoidal reflector. 65 lengths. The auxiliary or second lens means 983 can also act In FIG. 24, the body means 800 may have the same or to reduce any aberrations introduced by the annular TIR lens similar construction as that of FIG. 21c. Circularly curved 950.

Page 34

Also shown, as in FIG. 27, is a microScope objective lens of its edges 1063a and 1063b, which extend at 90° relative 954 which can slide axially in a bore in lens 950, and focus to one another. The illumination Sources are circular TIR auxiliary source light 965 onto the target or laser 951. Note lenses 1060, as described above, but made integral with the the cylindrical periphery 970 of 954 parallel to axis 986, and waveguide edges, as by embossing. Each lens has its own sliding in bore 967 of lens 950. A means to adjustably move light source, indicated at 1064. The annular facets of the objective lens 954 axially is schematically shown at 968. lenses face outwardly, i.e., away from the waveguide, but are Auxiliary source light 965 may be redirected by mirror 953, not illustrated in this view. (See, however, circular TIR lens as shown, toward lens 954, for focusing onto the target 951. and their facets, discussed and shown above.) In FIG. 28, a linear TIR lens 1027 is elongated in direction FIGS. 32-34 show a waveguide 1069 that tapers endwise, 1028, as are the lens facets 1027a. An elongated light source away from the TIR lens 1071, coupled to the waveguide. is indicated at 1029, along the focal line 1029a. A planar Note circular cross section wall 1072 of the waveguide that mirror 1030 extends across the faceted side of the lens, and taperS endwise, in the form of a tapering rod. The latter is reflects backlight from the Source toward the facets. coupled at its narrowest end 1069a in FIG. 34 to an optical The exit Side or face of the lens is coupled to a waveguide fiber 1069b that conducts light endwise in direction 1076. A 1025, as better shown in FIG. 29; and light is injected in light source 1080 emits light toward the faceted side of the direction 1026 edgewise into the waveguide. The lens may 15 TIR lens 1071.

be integral with the waveguide, or attached to its edge, as Tapered rod 1069 serves to conduct and to spread light out indicated by plane 1040 in FIG. 29. into the full angular range 0, carried by the plastic fiber FIG.29 also incorporates known optical means, indicated 1069b.

here by a reflector 1025a, to redirect light 90 in the planar dependsThis upon range is typically 30. The amount of taper the angular range 0, of the light leaving the waveguide, as shown by arrows 1070. A liquid crystal display is shown at 1042 at the upper side of the flat, planar facets (typically up to 10), which is in turn determined by waveguide, and may be used for the Screen of a portable the ratio of lens diameter to Source size. The lens diameter computer. d, and fiber diameter d, are related by The TIR lens facets fulfill two functions:

1) light from the source is efficiently collected and 25 injected into the waveguide, within the angular range Depending upon its type, light may propagate along a fiber's appropriate for guided propagation within the length to its opposite end, or it may be emitted out the sides waveguide; of the fiber, for illumination purposes. In the first case, a 2) light from the Source is transversely spread, producing transparent casing 1091 is placed around the fiber to confine Spatial uniformity of illumination acroSS the upper face the propagating light. Known as “cladding”, its refractive of the waveguide. index n is lower than the refractive index n of the fiber. The central Fresnel facets of the linear lens are in this case These indices determine the fibers angular range according are replaced by a concave cylinder seen at 1027c, for those to its numerical aperture (N.A.): rays of the Source that can directly pass into the waveguide.

FIG. 30 shows in perspective the elongated TIR lens 35 extending along the Sides of the planar waveguide. See lens For example, a polycarbonate fiber, with n=1.59, and an elongated sections 1027 and 1027", oriented at 90 to one acrylic cladding, with n=1.495, have an N.A.=0.54 and another. The waveguide may consist of plastic, Such as 0=32.8°.

acrylic, as shown at 1027d. Light from the lens sections In general, this form of the invention provides efficient travels in the waveguide in directions indicated by arrows 40 coupling of an LEDs radiation into a multi-mode optical 1038 and 1039. fiber, for a variety of purposes, both in illumination, as In addition to use with Small fluorescent lamps and Small shown here, and communication, where LEDs are already in incandescent lamps, this configuration is especially Suitable wide use. Besides LEDs, this configuration can be used for for use with light-emitting diodes (LEDs), which are very any much light Source, Such as Small incandescent lamps, that is smaller than a fiber's diameter.

Small and can be placed on the focal line of the linear lens. 45

In this way, the light of red, green, and blue LEDs will be Numeral FIG. 33 shows the TIR lens 1071 in greater detail. mixed to a uniform white. Alternatively, the three groups of 1081 indicated a reflector in FIG. 32. LEDS may be separately triggered, So that only those of one We claim:

color are emitting light at any one time, for Sequential-color 1. In combination, liquid crystal displays, which have three times the Spatial 50 a) a TIR lens having multiple facets, and resolution of conventional color displayS. b) a waveguide optically coupled to the TIR lens, FIG. 30 shows, by way of example, red, green, and blue c) said waveguide having an edge portion, LEDS, in repeated groups, and identified as follows: d) said TIR lens including multiple TIR lenses located proximate Said edge portion,

LED emitted light color 55 e) and including multiple light Sources, each Source asSociated with and facing one of Said TIR lenses,

red green f) and wherein there are multiple like groups of three of

Said Sources.

2. The combination of claim 1 wherein the waveguide has 60 a longitudinally endwise elongated body, and the TIR lens is

The spacing of the LEDs along 1027 and 1027", and their located to direct light into waveguide to travel longitudinally groups, is greatly exaggerated. A control 1055 is connected therein.

to the LEDs via the illustrated leads, to control ON-OFF 3. The combination of claim 2 wherein the waveguide States, whereby color control at the upper Side of the body tapers endwise.

waveguide panel is achieved. 65 4. The combination of claim 2 wherein the TIR lens has FIG. 31 illustrates a rectangular and planar waveguide facets facing away from the waveguide, and including a light 1063, similar to waveguide 1025. It is illuminated along two Source directing light toward Said facets.

Page 35

5. The combination of claim 4 wherein a continuation of 16. The combination of claim 14 including a liquid crystal the waveguide comprises an optical fiber. display located in light-receiving relation relative to the 6. The combination of claim 4 wherein the waveguide is waveguide.

an optical fiber or fibers. 17. The combination of claim 1 wherein said TIR lenses 7. The combination of claim 1 wherein the waveguide is are circular.

an optical fiber or fibers. 18. The combination of claim 1 including means to cause 8. The combination of claim 1 wherein the light sources the Sources to emit light of different colors. are LEDS.

9. The combination of claim 8 wherein each TIR lens has 19. The combination of claim 1 wherein the TIR lenses multiple facets facing an LED, the facets receiving light and waveguide are integral.

from the LED for propagation into the waveguide. 20. In combination, 10. The combination of claim 1 wherein the waveguide is a) a TIR lens having multiple facets, and a plate having at least one edge, and Said TIR lens extending b) a waveguide optically coupled to the TIR lens, proximate Said edge.

11. The combination of claim 10 wherein said edge is 15 c) the waveguide being a plate having at least one edge, elongated, and Said TIR lens is also elongated in the direc the TIR lens extending proximate Said edge, tion of edge elongation. d) Said edge being elongated and said TIR lens comprises 12. The combination of claim 10 wherein said edge is multiple TIR lens distributed along Said plate edge, elongated, and Said multiple TIR lens distributed along Said e) and including multiple light Sources, each Source plate edge. asSociated with and facing one of Said TIR lenses, and 13. The combination of claim 10 including a liquid crystal means to cause the Sources to emit light of different display located in light-receiving relation relative to the colors, waveguide.

14. The combination of claim 11 wherein said TIR lens is f) and wherein there are multiple like groups of three of an elongated linear TIR lens, Said waveguide being a planar 25 Said Sources, one Source in each group emitting light of waveguide. a first color, a Second Source in each group emitting 15. The combination of claim 11 wherein the elongated light of a Second color, and a third Source in each group TIR lens defines a focal line, and including LEDs spaced emitting light of a third color. apart along Said focal line to emit light transmitted via the

TIR lens into the waveguide. k k k k k