Patent ID: 7055986
Filing Date: 2006-06-06
Classification: G01J

Abstract:
1. An apparatus for emulating spectral signatures comprising: a plurality of electrically-powerable LEDs disposed in an array, the LEDs having respective spectral curves centered at different wavelengths in the visible to the short wave infrared wavebands; means for fixing the temperatures of the LEDs to avoid temperature-induced changes in their spectral curves; means for varying the light intensities of the individual LEDs so that the combination of their spectral curves matches the spectrum of an illumination condition to be emulated; and means for regulating the total amount of light collected from the array so that the cumulative spectrum has the same intensity as the illumination condition to be emulated, wherein the light-regulating means includes an integrating sphere attached to the LED array, the integrating sphere having an input opening for collecting light from the array and an output opening for outputting a uniform distribution of the collected light, and an iris mounted on the output opening of the integrating sphere for adjusting the size of the output opening.