referring to the accompanying drawings in which like reference numbers indicate like elements , fig1 illustrates the ophthalmic illumination system shown generally at 10 of the present invention . the illumination system of the present invention includes user interface 12 , controller 14 , power supply 16 , first power amplifier 20 , second power amplifier 22 , third power amplifier 24 , first light emitting diode ( led ) 30 , second led 32 , third led 34 , mixing device 40 , and exit lightguide 42 . preferably , and thus shown in fig1 but not required , is first condensing lens 50 , second condensing lens 52 and third condensing lens 54 . preferably , first led 30 is a blue led , second led 32 is a green led , and third led 34 is a red led . however , other led colors are conceivable , such as blue , yellow or red . in general , three leds or sources of different emitting wavelength are required . it is also conceivable that more than three leds or more than three wavelengths may be used . in operation , a user inputs the desired light intensity and / or color into user interface 12 . based on the demanded light intensity and / or color , controller 14 determines the appropriate power level and amplifier gain for each led . the determination of the color ratios and intensities that are required to produce a desired color output are well known . the blue , green and red sources are the same color sources that are used to produce color in television sets . additional discussion of the measurement and analysis of color is provided in the photonics design and applications handbook ( 1997 ), pp . h - 52 to h - 60 , and is hereby incorporated by reference in its entirety . in addition , the determination of the color ratios and intensities that are required to produce a desired color output are provided as a cie standard , as described in astm e308 - 95 “ standard practice for computing the colors of objects using the cie system ” which is hereby incorporated by reference in its entirety . after determining the proper color ratios and intensities , controller 14 sends power signal to power supply 16 , a first gain signal to first power amplifier 20 , a second gain signal to second power amplifier 22 , and a third gain signal to third power amplifier 24 . as a result , first led 30 , second led 32 , and third led 34 emit light . preferably , but not required , the light from first led 30 is condensed by first condensing lens 50 ; the light from second led 32 is condensed by second condensing lens 52 ; and the light from third led 34 is condensed by third condensing lens 54 . condensing lenses are used commonly in telecommunications systems and are widely available . condensing lenses may take many forms , and range from crude single element molded plastic devices to multi - element aspherical precision assemblies . the purpose of a condensing lens is to focus the diffuse light emitted by each led . upon the light &# 39 ; s entering and then exiting from the condensing lenses 50 , 52 , and 54 , light enters mixing device 40 . mixing device 40 is any device that will mix light from multiple sources and are well known in the lightguide arts . examples of mixing device 40 include glass rods , bifurcated or trifurcated fiber optic cables , integrating spheres , or the like . upon exiting from mixing device 40 , the light enters into exit lightguide 42 . exit lightguide 42 is then inserted into ocular tissue 44 to provide illumination for surgical procedures . unlike the fifty ( 50 ) hour life span of a tungsten light source , the illumination system of the present invention contemplates a life span of approximately twenty thousand ( 20 , 000 ) hours . accordingly , the present invention provides increased reliability over tungsten light sources due to increased life span , less heat generated as compared to tungsten light sources , and the ability to select a color output in an ophthalmic illumination system by inputing a color output selection into a user interface . in view of the foregoing , it will be seen that the several advantages of the invention are achieved and attained . the embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated . as various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention , it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting . for example , condensing lenses may be eliminated such that the leds 32 , 34 , and 36 emit light directly to mixing device 40 . alternatively , mixing device 40 may simultaneously incorporate a condensation of light from leds 32 , 34 , and 36 without the use of a separate condensing lens elements 50 , 52 , and 54 . thus , the breadth and scope of the present invention should not be limited by any of the above - described exemplary embodiments , but should be defined only in accordance with the following claims appended hereto and their equivalents .
an ophthalmic illumination system is provided that emits a light that is controllably variable in color . because the light originates from leds , less heat is generated from the emitted light as compared to conventional ophthalmic illumination systems using tungsten or discharge sources .