Abstract: A method of spectrographic measurement is disclosed. The method generates light energy using a solid state low capacitance excitation source, the light energy being caused to fall on a sample to be assayed, causing the sample to output an output optical signal. The method generates a plurality of modulation frequencies, and a plurality of heterodyne frequencies to form a set of heterodyne signals at the heterodyne frequencies. Each of the heterodyne frequencies is associated with one of the modulation frequencies. Coupling the modulation frequencies to the excitation source, causes the excitation source to generate excitation energy modulated in intensity in proportion to the modulation frequencies. A sampling a portion of the substantially incoherent excitation energy forms a reference substantially incoherent excitation signal.

Abstract: The invention relates to methods and devices for luminescent (e.g., fluorometric) measurement. The disclosure includes frequency domain and single photon counting methods and utilizes low capacitance semiconductor light emitting devices.

Abstract: A method of spectrographic measurement is disclosed. The method generates light energy using a solid state low capacitance excitation source, the light energy being caused to fall on a sample to be assayed, causing the sample to output an output optical signal. The method generates a plurality of modulation frequencies, and a plurality of heterodyne frequencies to form a set of heterodyne signals at the heterodyne frequencies. Each of the heterodyne frequencies is associated with one of the modulation frequencies. Coupling the modulation frequencies to the excitation source, causes the excitation source to generate excitation energy modulated in intensity in proportion to the modulation frequencies. A sampling a portion of the substantially incoherent excitation energy forms a reference substantially incoherent excitation signal.