摘要 |
The ratio of the intensity of two light beams is determined by an apparatus which includes a chopper wheel for chopping one of the light beams, a photodetector for detecting the intensity of both light beams applied simultaneously thereto, and a logarithmic amplifier for amplifying the current produced by the photodetector. The AC component of the logarithmically amplified current represents the ratio of the intensity of the two light beams.
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