WO2002099332A1

WO2002099332A1 - Lightweight high-intensity head-mounted illumination source

Info

Publication number: WO2002099332A1
Application number: PCT/US2002/012215
Authority: WO
Inventors: David Wayne Davis; Charles Y. Park; Thomas K. Park; Anthony K. Park
Original assignee: Ego Scientific, Inc.
Priority date: 2001-04-17
Filing date: 2002-04-17
Publication date: 2002-12-12

Abstract

A lightweight headlight (10) is disclosed. The headlight (10) has a head piece (12) with one or more light sources (16), preferably LED arrays, secured thereto. A light projector (14), such as a lens (22), reflector (24), or some combination thereof, is affixed to the head piece (12), and a fiber optic cable (56) operably connects each light source (16) to the light projector (14). The light sources (16) may be pulsed at a frequency sufficiently high to be undetectable to a human eye. Heat sinks (34), thermal insulation (36), and radiation reflectors (38) may also be disposed between the arrays (16) and the head piece (12). A power source (18) housing may be affixed to the head piece (12), to the user, or the other clothing worn by the user.

Description

LIGHTWEIGHT HIGH-INTENSITY HEAD-MOUNTED ILLUMINATION SOURCE

This application claims priority from U.S. provisional patent application serial number 60/284,540, filed on April 17, 2001.

Background of the Invention This invention relates to the field of head-mounted illumination sources, with particul^ regard to surgical headlights.

The invention may of course be used in a variety of other fields, such as assembly of small parts, home inspecting, spelunking, hobbies, and in general any application in which movable illumination that does not encumber the user's hands is desired. Surgical headlights are the most demanding of the above mentioned applications, as they require a high-intensity light source providing a collimated, high brightness, light spot having a diameter of several inches on a surgical work area, such as a patient's body. Due to the particular requirements of surgical work, it is mandatory that the light source follow the movements of the surgeon's head. The headgear or head piece must be comfortable and securely fastened to the surgeon's head so that the light spot is consistently positioned in the middle of the surgeon's field of view. Furthermore, a reliable long-lasting power supply is required to avoid unexpected power failure at a critical moment of a long operation. Last but not least, care must be taken to shield the user from exposure to damaging radiation such as ultraviolet (UV) rays and from excessive heat generated by the light source.

Many kinds of surgical headlights have been designed, such as described in U.S. Patent 5,355,285 by Hicks, the disclosure of which is incorporated herein by reference. In this patent, a xenon lamp is used as a high-intensity light source, and the light is brought to the surgeon's head piece through fiber optics. Due to the weight of the lamp and power supply .and the heat generated by it, the light source is necess< rily placed away from the surgeon's body and the light is delivered through an extended length of fiber optics, that can be fixed to the surgical room's ceiling or extend directly from the surgeons' head to the lamp. These types of headlights have the drawback that the movements of the surgeon's head are restricted due to the stiffness of the fiber optics cable. Furthermore, the weight and stiffness of the cable make such headlight systems extremely uncomfortable for extended wear. In addition, while xenon lamps are substantially reliable, there exists the possibility of .an abrupt failure of the lamp in the middle of an operation. Also, due to the high cost of xenon lamps, these headlights are very expensive. Further still, there is an undesirable loss of light intensity because of the length of fiber optic cable through which the light must pass from the light source to the light projector of the head piece. An alternative source of light, that to the best of our knowledge has not been applied to the field of surgical headlights or wearable high intensity light sources in general, is represented by light emitting diodes (LED), particularly LEDs and LED arrays capable of providing high intensity light. Such diodes, that have recently become commercially available, can be formed of materials such as for example gallium nitride, but other materials are being researched and should become available in the future. These LEDs provide a lightweight source of high intensity light that requires low power to operate, generate low heat, and can be mounted in arrays. Arrays of LEDs have been disclosed for use in other fields or areas, such as shown for example in U.S. Patent 5,598,068 by Shirai, the disclosure of which is incorporated herein by reference. Still, it is not believed that LEDs or LED arrays have been used in headlights, such as surgical headlights.

Summary of the Invention

It is therefore an object of the present invention to provide an improved, lightweight, comfortable headlight.

It is a further object of the present invention to provide a headlight of the above type that is particularly well suited as a surgical headlight.

It is a still further object of the present invention to provide a headlight of the above type that provides for improved mobility, that evenly distributes weight about a user's head, and that reduces neck fatigue by the user.

It is a still further object of the present invention to provide a headlight of the above type that provides an efficient, reliable, high intensity light beam while protecting the user from heat and radiation.

It is a still further object of the present invention to provide a headlight of the present invention that uses pulsing light to decrease power demands and to increase the operating life of the light source.

It is a still further object of the present invention to provide a headlight of the present invention that provides light source redundancy to greatly reduce the risk of sudden failure. It is a still further object of the present invention to provide a headlight of the above type that provides a power supply that may be quickly and easily replaced without the need to remove the headlight from the user's head. It is a still further object of the present invention to provide for high efficiency light transfer by reducing the distance that light must travel through fiber optic cables.

Toward the fulfillment of these and other objects and advantages, the headlight of the present invention comprises a head piece with one or more light sources, preferably LED arrays, secured thereto. A light projector, such as a lens, reflector, or some combination thereof, is affixed to the head piece, and a fiber optic cable operably connects each light source to the light projector. The light sources may be pulsed at a frequency sufficiently high to be undetectable to a human eye. Heat sinks, thermal insulation, and radiation reflectors may also be disposed between the arrays and the head piece. A power source housing may be affixed to the head piece, to the user, or to other clothing worn by the user.

Brief Description of the Drawings The above brief description, as well as further objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of the presently preferred but nonetheless illustrative embodiments in accordance with the present invention when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is an overhead schematic view of a headlight of the present invention; FIG. 2 is a partial, elevation view of a direct coupling between a fiber optic cable and a lens in a light projector of the present invention; FIG. 3 is a partial, elevation view of a compound coupling between a fiber optic cable and a lens in a light projector of the present invention;

FIG. 4 is a partial, elevation view of an alternate embodiment of a compound coupling in a light projector of the present invention;

FIG. 5 is a partial, side elevation, schematic view of headlight of the present invention; .

FIG. 6 is an overhead schematic view of an alternate embodiment of a headlight of the present invention; FIGS. 7 - 10 are partial, side elevation views of alternate manners of coupling a fiber optic cable with an LED array for use in the present invention;

FIG. 11 is a side, schematic view of an alternate embodiment of the present invention;

FIG. 12 is a schematic diagram of an electronic drive for use in the present invention; FIG. 13 is a schematic diagram of an alternate embodiment of an electronic drive for use in the present invention;

FIG. 14 is a partial, side elevation view of an alternate manner of coupling a fiber optic cable with an LED array for use in the present invention;

FIG. 15 is atop view of an alternate manner of directly coupling a fiber optic cable with an LED; and

FIG. 16 is a side view of the alternate embodiment depicted in FIG. 15.

Detailed Description of the Preferred Embodiment

Referring to FIG. 1, the reference numeral 10 refers in general to a headlight of the present invention. The headlight 10 has a head piece 12. A light projector 14 and one or more light sources 16 are affixed to the head piece 12. A power source or supply 18 is operably connected to the light sources 16 and may be affixed to the head piece 12.

The head piece 12 will typically comprise one or more headbands 20 but may take any number of forms, shapes, sizes, and configurations. As used herein, the term head piece

12 includes but is not limited to headbands 20, helmets, nets, caps, hats, or straps designed to be worn on a user's head, and combinations thereof.

The light projector 14 is affixed to the head piece 12. The light projector 14 can assume different designs depending on the type of fiber optics used, and can include lenses 22 and mirrors 24 as needed to produce a uniform high intensity light beam 26 having a diameter of several inches. For example, as best seen in Figs. 2 and 3, light projectors 14 may use direct coupling between the output end of a fiber optic cable and a lens 22 or may use compound coupling wherein a reflector 24, such as a turning mirror 24, or other lenses or filters are disposed between the output end of the fiber optic cable and the lens 22. Such light projectors 14, light projection systems, or collimating optical arrangements are well known in the art and are commercially available or can be easily assembled from standard components. For example, U.S. Patent No. 5,430,620, by Li et al., the disclosure of which is incorporated herein by reference, discloses various embodiments of light projectors 14 or light projection systems. A light projector 14 having a low profile and light weight is of course preferred. Referring to Fig. 4, the light projector 14 may also include any number of different combinations of lenses, reflectors, and filters. For example, the light projector 14 may include a holographic filter 28 for diffusion of, among other things, multichannel fiber optics, and may include a color filter 30 to provide for the desired optical bandpass. In this manner, light from light sources 16, such as LED arrays, may be conditioned by the filters 28 and 30 before reaching the lens 22 (not shown). Although the light projector 14 preferably uses a lens 22, it is understood that a reflector 24, such as a reflective concentrator may be used in place of or in combination with a lens 22.

Referring to Fig. 1, one or more light sources 16, preferably LED arrays having one or more LEDs, are affixed to the head piece 12. The LEDs can be for example gallium nitride LEDs, but any other LED capable of producing high intensity illumination is suitable for the invention. The number of arrays 16 and the number of LEDs in each array 16 depends on the desired illumination intensity and on the characteristics of the LEDs. The LED arrays 16 are preferably disposed remotely from one another, distributed about the head piece 12, and therefore, distributed about the user's head 32. The LED arrays 16 are positioned so that the center of mass of the headlight 10 is near the center of mass of the user's head 32. This weight distribution makes the headlight 10 more comfortable to wear and decreases neck fatigue. The distribution of the arrays 16 is of course dependent on the number of arrays and their weight, as well as the presence, weight, and positioning of other components of the headlight 10, such as the light projector 14 and power source 18, if a power source is affixed to the head piece 12.

Although fiber optics have been used in the past to connect a remotely disposed light source 16 to a head piece 12 mounted light projector 14, it is not believed that fiber optics have been used to connect a head piece 12 mounted light source 16 to a head piece mounted light projector 14. Instead, in the past, when a light source 16 was mounted to a head piece 12, the light source 16 was typically mounted in or adjacent to the light projector 14. An example of this can be seen in U.S. Patent No. 3,947,676, by Battilana et al., the disclosure of which is incorporated herein by reference. It was in large part the present inventors' desire to make a more comfortable headlight 10 that led the inventors to go against the teachings of the prior art and move the head piece 12 mounted light source 16 away from the head piece 12 mounted light projector 14. It was also this desire for greater flexibility in the placement of a head piece 12 mounted light source 16 that led to the use of fiber optics. For reasons to be described below, the LED arrays 16 are preferably disposed no further th.an approximately 1 foot from the lens 22 or reflector 24 and are more preferably disposed no further than approximately 6 inches from the lens 22 or reflector 24. It is understood that these are straight line measurements and are not measurements taken around a user's head 32 when the headlight 10 is worn.

Similarly, the number of LEDs in each array 16 and the configuration of each array is determined by the LEDs' characteristics and/or commercial availability. A further advantage of this arrangement is that the LED arrays 16 can be cheaply and easily replaced in case of failure of some LEDs over time, so that the lifetime of the light source 16 can be greatly extended at minimal cost with respect to the prior art devices.

As best seen in Fig. 5, to prevent discomfort to the user due to excessive heat generated by an LED array 16, a heat sink 34, thermal insulation 36, and a radiation reflector 38 are disposed between the LED array 16 and the head piece 12. The heat sink 34 or heat dissipating device is similar to those used to dissipate the heat generated by electronic components and may assume different shapes and sizes and be formed of different materials, as desired. For example, the heat sink 34 or heat dissipating device can have a decorative shape to make the light source assembly pleasant to the eye, or can be designed to minimize its size or simplify machining, depending on the manufacturer's design choice. To minimize the weight of the assembly, the heat sink 34 may be formed of a lightweight thermally conductive substance such as porous graphite. In the preferred embodiment, a microfan 39 is also used for cooling. The microfan 19 may be secured to the headlight 10 in any number of locations and may provide for cooling of not only the light source 16 but also other components prone to generate excessive heat.

The power source 18 or supply is housed in a power source housing 40 such as a battery pack connected to the light sources 16 by lightweight flexible electric wires 42. As best seen in Fig. 6, the housing 40 is preferably provided with a fastener 44, such as a clip, pin, strap, belt, harness, or the like, so that the housing 40 can be attached to the user or to clothing of the user. For example, the power supply can be connected to the user's clothing

(such as to the back of the surgical gown or to a belt) or to a nearby support such as a table or a cart. Other examples of fasteners 44 would include, but not be limited to, a backpack-like harness, a strap extending across the user's chest, or other arrangements known in the art. Similarly, hook and loop fasteners, such as Velcro® brand fasteners, could be provided with instructions for the user to fashion a preferred custom arrangement to fit any figure and taste. It is understood that supplemental or alternate power sources 46 may be provided, such as solar panels or cells affixed to the head piece 12. The use of solar cells 46 as a supplemental power source further extends the life of batteries used as the primary power source 18. The solar cells 46 receive light from external lighting surrounding the user, such as the bright overhead lights in a surgical room. It is understood that the primary or sole power source 18 may also be affixed to the head piece 12 (Fig. 1). An indicator 48, such as a red LED, can be incorporated into the power source housing 40 to warn the user when the batteries are becoming exhausted. Such indicators 48 are well known in the art. An easily accessible door 50 may also be used to allow for the quick replacement of batteries as necessary. Alternatively, the wires 42 or conductors may be operably connected to the housing 40 and power source 18 using a plug 52. This would enable the user to replace the whole power source housing 40, including batteries, with a quick unplug-plug in movement, .and to postpone the replacement or recharging of the batteries in the exhausted power source housing 40 to a more convenient time. Several types of batteries, such as lithium batteries, can be used as the power source 18. The batteries may for example be disposable and non-rechargeable; rechargeable and detachable; or rechargeable and non-detachable. The power source 18 may allow for DC or AC input for battery override, or any number of different combinations may be used. It is noted that in the surgical headlight 10 application the power source housing 40 replacement could be easily performed by a person other than the surgeon, such as a nurse, so that the disruption to the surgeon's work would be minimal. It is also noted that in all the cases discussed above, the replacement of the batteries or power source housing 40 does not require any displacement of the headlight 10 from the user's head 32. A multiple position switch 54 may also be provided for selectively turning on or off different combinations of light sources 16 or LED .arrays.

As best seen in Figs. 1 and 6, one or more fiber optic cables 56 operably connect the light sources 16 to the light projector 14. Multichannel fiber optic cable 56 is preferred, but multichannel or single channel fiber optic cable 56 may be used. Referring to Figs. 7 -10, the fiber optic cables 56 may be operably connected to the light sources 16 in any number of ways. For example, the fiber optic cables 56 may be operably connected to the light sources 16 using lenses 58 (Fig. 7) or spheres 60 (Fig. 8). Air gaps of a few microns may be provided between the lenses/spheres 56/58 and the light sources 16, or the lenses 56 or spheres 58 may be bonded or affixed to the light sources 16. The fiber optic cables 56 may also be directly coupled to the light sources 16 (Fig. 9). In one preferred embodiment, depicted in Fig. 10, an optical sphere 62 is provided. A circular board 64 is affixed to and partially encircles the optical sphere 62 , and a plurality of LEDs 66 are affixed to the board. A multichannel or single channel fiber optic cable 56 is affixed to the optical sphere 62.

In another preferred embodiment depicted in Fig. 14, an alternate method of bonding a fiber optic cable 56 to an LED is depicted. In this embodiment, a flex circuit is used. The flex circuit has a board 67, with foldable tabs 69. The LEDs 66 are affixed to the foldable tabs 69. The tabs 69 may be folded out of the plane of the board 67 to reduce the bends, twists, or turns needed to directly couple a fiber optic cable 56 to an LED 66. As better seen in Figs. 15 and 16, a modification has also been made to the LED 66 to provide for improved performance. Like typical LEDs, the depicted LED has an anode lead 82, a cathode 84, and a substrate 86. As best seen in Fig. 15, the metalized anode contact 88 is bonded to the light emitting surface of the diode but otherwise differs from prior art contacts. Unlike a typical anode contact, which is centrally located with open sides, the anode contact 88 of the present invention covers the entire upper surface with the exception of one centrally located opening 90. Providing only one, centrally located opening allows a better bonding location for a fiber optic cable 56, and provides for more efficient light transfer. As seen in Fig. 16, a side coating 92 with reflective interior surfaces, such as chrome or gold, are also bonded to the sides of the substrate 86 to trap light generated by the LED and to allow the light to escape only through opening 90. This method allows each fiber optic cable to be bonded to the emitter of each diode at the die or chip level, or optical package form, singularly or in a bundle. It also allows for more efficient light transfer into and through the fiber optic cable

56.

Referring to Figs. 11-13, an electronic drive or pulse creator 68 is also provided, disposed between the power source 18 and the light sources 16 to provide for, among other things, pulsed operation of the light sources 16. In the embodiment depicted in Fig. 12, the electronic drive 68 comprises a DC converter 70, a pulse generator 72, and a distributor 74.

A control unit 76 allows a user to adjust the pulse, shape, repetition, and width of pulses for maximum efficiency. The adjustment may be manual, or a detector 78 may be provided and coupled with the control unit 76 for automatic control and adjustment. In the preferred embodiment depicted in Fig. 13, the electronic drive 68 comprises a pulse width modulated DC to DC generator 80 and a distributor 74. A detector 78 is coupled to a control unit 76 to provide for automatic control. This embodiment eliminates the power supply rectifier stage and the pulse forming electronics in the pulse generator 72. In the embodiment depicted in Fig. 11, the power source 18 and electronic drive 68 are heat managed in the same or similar way as the light sources 16, as discussed above in connection with Fig. 5. When the light sources 16 are operated in pulse mode, the pulse frequency chosen is sufficiently high so that the pulsing is not detectable by the human eye. Using the pulse mode of operation increases battery life by reducing the power demand and increases the life of the LED devices.

In operation, the user secures the head piece 12 to his head 32. If the power source housing 40 is not affixed to the head piece 12, the user secures the power source housing 40 to his body or clothing. The user operates the switch 54 to activate the desired number and combination of light sources 16. The user also selects pulsed or non-pulsed operation. Electrical power passes from the power source 18 to the electronic drive 68 for conditioning. The electronic drive 68 passes the electrical power along to the LED arrays 16 in pulsed or non-pulsed condition to activate the LED arrays. The LED arrays 16 generate light, and the fiber optic cables 56 deliver that light to the light projector 14. Because the LED arrays 16 are disposed in relatively close proximity to the lens 22 or reflector 24 of the light projector 14, losses due to transmission through fiber optic cables 56 are reduced. In the light projector 14, the light from the various LED arrays 16 is conditioned, such as by passing through holographic and color filters 28 and 30. The light from the various LED arrays 16 is also combined to form a high intensity beam 26, and the lens 22 or reflector 24 focuses and directs the high intensity beam 26 to a work area 82, such as a surgical work area. Other modifications, changes and substitutions are intended in the foregoing, and in some instances, some features of the invention will be employed without a corresponding use of other features. For example, the headlight 10 need not use an electronic drive 68 or incorporate features directed toward pulse mode operation. Further, although LED arrays 16 are preferred, other light sources may be used. Similarly, although multiple LED arrays 16 are preferred, a single LED array 16 may be used. Also, any number of different power sources 18 may be used alone or in combination with other power sources. Further still, although it is preferred to use a multiple position switch 54 with the flexibility to activate different combinations of light sources 16, a simple on/off switch may be used that simultaneously activates or deactivates all light sources 16. Although the invention has been disclosed as being particularly useful in connection with surgical headlights, it is understood that the device and methods may apply to any number of different uses. It is also understood that all quantitative information given is by way of example only and is not intended to limit the scope of the present invention. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.

Claims

What is claimed is:

1. An apparatus, comprising: a head piece; a light projector secured to said head piece; a first light source secured to said head piece; a first fiber optic cable operably connecting said first light source to said light projector; a second light source secured to said head piece; a second fiber optic cable operably connecting said second light source to said light projector.

2. The apparatus of claim 1, further comprising: a power source housing; a fastener disposed on said power source housing for fastening said power source housing to a user or to clothing of said user; and conductors for operably connecting a power source housed by said power source housing to said first and second light sources.

3. The apparatus of claim 1, wherein said first light source comprises a first LED array, said first LED array comprising at least one LED.

4. The apparatus of claim 3, wherein said first LED array comprises at least one gallium nitride LED.

5. The apparatus of claim 1 , wherein said first light source is disposed remotely from said second light source.

6. The apparatus of claim 3, further comprising a heat sink disposed between said first LED array and said head piece.

7. The apparatus of claim 6, wherein said heat sink comprises graphite.

8. The apparatus of claim 6, further comprising thermal insulation disposed between said first LED array and said head piece.

9. The apparatus of claim 8, further comprising a radiation reflector disposed between said first LED array and said head piece.

10. The apparatus of claim 3, wherein said second light source comprises a second LED array, said second LED array comprising at least one LED, and further comprising a multiple position switch operably connected to said first and second LED arrays for selectively turning on or off one or more of said first and second LED arrays.

11. The apparatus of claim 1, further comprising: a power source operably connected to said first light source; and a pulse creator disposed between said power source and said first light source.

12. The apparatus of claim 1, further comprising a power source, said power source being secured to said head piece and being operably connected to said first and second light sources.

13. The apparatus of claim 3, wherein said first LED array comprises: an optical sphere; a board affixed to said optical sphere; and a plurality of LEDs affixed to said board.

14. A surgical headlight, comprising: a head piece; a first LED array secured to said head piece, said first LED array comprising at least one LED; a light projector secured to said head piece; and a first fiber optic cable operably connecting said first LED array and said light projector.

15. The surgical headlight of claim 14, further comprising: a second LED array secured to said head piece, said second LED comprising at least one LED; and a second fiber optic cable operably connecting said second LED array to said light projector.

16. The surgical headlight of claim 15, further comprising: a power source housing; a fastener disposed on said power source housing for fastening said power source housing to a user or to clothing worn by said user; and conductors for operably connecting a power source housed by said power source housing to said first and second LED arrays.

17. The surgical headlight of claim 14, further comprising: a power source operably connected to said first LED array; and a pulse creator disposed between said power source and said first LED array.

18. A method, comprising: (a) supporting a first LED array on a user's head, said first LED array comprising at least one LED;

(b) supporting a second LED array on a user's head, said second LED array comprising at least one LED; (c) activating said first and second LED arrays to provide first and second light sources, respectively;

(d) combining light from said first and second light sources to form a beam; and

(e) directing said beam toward a work area.

19. The method of claim 18, wherein step (c) comprises pulsing said first and second LED arrays to provide first and second light sources, respectively.

20. The method of claim 18, wherein step (c) comprises pulsing said first and second LED arrays at a frequency to provide first and second light sources, respectively, said frequency being sufficiently high so that pulsing of said first and second LED arrays is not detectable by a human eye.

21. A method, comprising :

(a) supporting a lens or a reflector on a surgeon's head;

(b) disposing a first light source no further than approximately one foot from said lens or said reflector;

(c) disposing a second light source no further than approximately one foot from said lens or said reflector, said second light source being disposed remotely from said first light source;

(d) passing light from said first and second light sources to said lens or said reflector; and

(e) directing said light from said lens or said reflector to a surgical work area.

22. The method of claim 21, wherein step (b) comprises disposing said first light source no further than approximately six inches from said lens or said reflector.

23. The method of claim 21, wherein: said first light source comprises a first LED array, said first LED array comprising at least one LED; and step (b) comprises disposing said first LED array no further than approximately one foot from said lens or said reflector.

24. The method of claim 21, wherein step (d) comprises passing light from said first and second light sources through first and second fiber optic cables, respectively, to said lens or said reflector.

25. The method of claim 21, wherein step (d) comprises passing pulses of light from said first and second light sources to said lens or said reflector.

26. The method of claim 21, wherein step (a) comprises supporting a lens and a reflector on a surgeon's head.

27. The method of claim 21, wherein step (d) comprises passing light from said first and second light sources through one or more color or holographic filters and to said lens or said reflector.

28. The method of claim 21, further comprising: providing a power source, said power source being operably connected to said first and second light sources; and fastening said power source to said surgeon or to clothing worn by said surgeon.

29. The apparatus of claim 3, wherein said first LED array comprises an LED die or a packaged LED die bonded to a flex circuit board.

30. The surgical headlight of claim 14, wherein said first LED array comprises an LED die or a packaged LED die bonded to a flex circuit board.

31. The apparatus of claim 3, wherein said at least one LED comprises: a substrate having a front, light emitting surface; and a metalized anode contact bonded to said front, light emitting surface, said anode contact covering substantially all of said front, light emitting surface and having an aperture passing through a central portion of said anode contact to provide a path for light to escape from said substrate.

32. The surgical headlight of claim 14, wherein said at least one LED comprises: a substrate having a front, light emitting surface; and a metalized anode contact bonded to said front, light emitting surface, said anode contact covering substantially all of said front, light emitting surface and having an aperture passing through a central portion of said anode contact to provide a path for light to escape from said substrate.