Abstract

With the development of optical electronics and a variety of its applications, the challenge of measuring ultraweak intensities of light from various types of faint source which releases merely a small number of photons is of considerable interest and attractive. With this aim, the photon counting technique has been developed and is now customarily utilized to detect very weak light intensities less than about 10^-12 W in the visible and near infrared regions in conjunction with the high-sensitive photomultiplier. As a fascinating and interesting application of this technique to photobiology and photochemistry, we have detected extremely weak bioluminescence¹ and chemiluminescence^2,3 from various biological and chemical systems, such as living tissues like tumors and organs, and enzymatic reactions, and also analyzed their exceedingly weak spectra using a specially designed spectral analyzer system⁴.

© 1984 Optical Society of America