A multiwavelength time-sharing dual beam spectrophotometer for biological tissues

Abstract

The utility of the dual wavelength spectrophotometer is extended by providing the monochromators with stepping motors to control wavelength, and providing regulation of the photomultiplier gain to give constant output on one channel. Under control of a small microprocessor, the instrument can alternate rapidly between four pairs of wavelengths, giving a time-sharing presentation of the kinetics of four pigments during the same experimental run. Additionally, by driving the two wavelengths synchronously with a small offset, a wavelength derivative spectrum can be obtained, which can be integrated to produce a difference spectrum from a single piece of tissue. These techniques are especially applicable to epithelial tissue and other biological material not available as homogeneous suspensions.