Patent ID: 7616317

Claim:
A reflectometer for use with a chemical analyzer, which comprises: a plurality of light emitting diodes, at least some of which emit light of substantially the same wavelength and at least some of which emit light of a different wavelength than other light emitting diodes, the light emitting diodes of substantially the same wavelength being arcuately arranged about a circle having a predetermined radius, and being positioned to direct light emitted therefrom on a reagent test slide in proximity to an illumination plane, adjacent light emitting diodes being spaced apart from each other a predetermined distance, at least two of the light emitting diodes emitting light of substantially the same wavelength and being illuminatable simultaneously to provide a volume of substantially homogeneous irradiance at the illumination plane, each of the at least two of the light emitting diodes which emit light of substantially the same wavelength and are illuminatable simultaneously having a semiconductor die and exhibiting a non-peak intensity in emitted light which is less than the peak intensity at a non-peak light intensity axis extending from the die which is different from and peripheral to the peak light intensity axis, the at least two light emitting diodes being positioned to illuminate the reagent test slide at an angle to the peak light intensity axis of each of the at least two light emitting diodes, the peak light intensity axis of each of the at least two light emitting diodes not being directed at the reagent test slide, the peripheral, non-peak light intensity axis of each of the at least two light emitting diodes being directed at the reagent test slide to illuminate the reagent test slide; and an optical sensor, the optical sensor receiving light emitted by the plurality of light emitting diodes and reflected from a reagent test slide situated in proximity to the illumination plane and within the volume of substantially homogeneous irradiance.