CARRIER LIFE MEASURING DEVICE

摘要

PURPOSE:To eliminate the influence of the interfacial level of a sample, the fluctuation of circuit constant of a measuring system etc. by a method wherein an optical beam with wave length subject to small photoabsorption coefficient of sample and another optical beam with wave length subject to large photoabsorption coefficient are converted into pulses to irradiate the same place alternately and the first and second optical voltages generated by the sample are detected by capacity coupling to calculate the ratio of their amplitude. CONSTITUTION:A laser 1 oscillates with a wave length lambda1 subject to large absorption coefficient alpha while another laser 2 oscillates with another wave length lambda2 subject to small absorption coefficient alpha. A laser power supply 13 can select the laser 1 or 2 by means of transferring a switch S1 to A side or B side. Optical modulators 3 and 4 receive the reference wave signal of a tunning and detecting amplifier 12 as input signal to chop optical beams respectively with wave length lambda1 and lambda2 by the frequency (f) of the reference wave signal. A dichroic mirror 6 permeates the optical beam with wave length lambda1 but reflects the optical beam with wave length lambda2. Any optical voltage generated may be detected by the tunning and detecting amplifier 12 and processed by a signal processing circuit 21 to calculate the mirror carrier life (tau) by the results displayed in a display unit 24.