Abstract: A readhead for illuminating a sample carrier and receiving light from the sample carrier, including a housing for receiving a sample carrier, an array of light sources mounted within the housing in a fixed position relative to the sample carrier, and including first and second light-emitting diodes for emitting substantially monochromatic light of a two different wavelengths, a light guide mounted in the housing between the light-emitting diodes and the sample carrier, and a light detector coupled to receive light from the sample carrier. The readhead also includes a light source for directing excitation light of a predetermined wavelength to the sample carrier, and a light filter positioned between the sample carrier and the light detector and adapted to prevent passage therethrough of the excitation light. The readhead allows both fluorescence spectroscopy and reflectance spectroscopy to be conducted on the sample carrier.

Abstract: A laser system comprises a reflective chamber capable of housing a laser medium and at least two laser diodes emitting light at different respective wavelengths into the reflective chamber. The wavelength of each respective laser diode may be selected to minimize fluctuations in absorption by the laser medium of light emitted by the diode bars as the wavelength of each respective laser diode changes due to changes in an operating temperature of the laser system. The wavelength of each respective laser diode may be selected such that absorption by the laser medium of the wavelength of light emitted by one laser diode increases and absorption by the laser medium of the wavelength of light emitted by another laser diode decreases as the operating temperature changes within a predefined range.

Abstract: A readhead for a photometric diagnostic instrument for illuminating a target area substantially uniformly via only a single light-emitting diode (20) and receiving light from the target area so that reagent tests may be performed is provided with a housing (12, 14, 16) adapted to be incorporated in a photometric diagnostic instrument, first and second light sources (20) mounted in a fixed position relative to the housing (12, 14, 16), a light guide (26) mounted to receive light from each of the light sources (20) which conveys, when only one of the light sources (20) is illuminated, substantially all of the light from the light source (20) to illuminate a target area substantially uniformly, and a light detector (70) coupled to receive light from the target area. Each of the first and second light sources (20) is composed of only a single light-emitting diode (20) for emitting substantially monochromatic light of a different wavelength.