A new photometric detector in the visible spectral range based on a silicon photodiode

摘要

From the equivalent circuit of a photodiode it is shown that the lighthyphen;induced current of the photodiode is expected to be characterized by a linear function of the light intensity in a range of eight decades. The electrical circuit of the detector based on a silicon photodiode (S1722hyphen;02; Hamamatsu) in combination with an operation amplifier used as a currenthyphen;voltage converter and its realization is specified. It exhibits 10percnt;ndash;90percnt; rise times between 200 ns and 5 mgr;s depending on the internal amplification selected out of five stages. The wavelength dependence of the signalhyphen;tohyphen;noise ratio of this photodiode system is determined and compared with that of a detector based on a photomultiplier (1P28; RCA, Lancaster). At wavelengths above 580 nm the photodiode system exhibits a signalhyphen;tohyphen;noise ratio up to 20 times better than the photomultiplier system. Employing a HeNe laser as light source, a signalhyphen;tohyphen;noise ratio as high as 2times;104is found with a time resolution of 1 mgr;s. thinsp;