Abstract: A method and apparatus for measuring the heterogeneity of oxygen delivery to perfused and in situ organs. A laser is employed as a flying spot scanning excitation fluorometer source which provides excitation for either oxidized flavoprotein of the mitochondrial space or reduced nucleotide of mitochondrial and cytosolic spaces. Emission from the two fluorochromes is acquired at 10.sup.4 to 10.sup.5 data points per sec. and histograms of the fluorescence intensity versus the number of occurrences of that intensity are displayed. The histograms show alterations of the intensity and the degree of heterogeneity of the redox states of the organ tissue under study.

Abstract: A multi-wavelength time-sharing apparatus usable in various different configurations of optical measuring equipment to provide a plurality of time-shared optical channels and including appropriate circuitry. The apparatus employs a turbine-driven filter wheel having a shaft position-encoding arrangement consisting of a hollow shaft portion which is internally illuminated. The hollow shaft portion has two sets of spaced apertures cyclically communicating with respective angularly spaced pairs of externally fixedly mounted phototransistors which are sequentially illuminated as the shaft portion rotates and which produce timing pulses which drive Schmitt triggers, which, in a typical embodiment, in turn produce pulses compatible with a logic circuit employed to decode the phototransistor signals into triggers for driving a 4-channel switched gain equalizer, a dark current clamp, and detector gates. Appropriate selection of the signals enables the instrument to function as a fluorometer or a spectrophotometer.