Photodetektorvorrichtung für ein streuendes Medium mit Phasendetektion

摘要

Intensity modulated light irradiates the scattering and absorption medium which is to be measured. After propagation in the scattering and absorption medium, the modulated light emerges therefrom and is incident to the photodetecting unit. The photodetecting unit converts the incident light into an electric signal. The feedback unit extracts the ac component from this signal, compares the intensity with a preset adjusting value, and controls the intensity tuneable light irradiating unit. The gain of the photodetecting means is fixed. Then the phase difference between the modulated incident light and the transmitted light is detected.