| 摘要 |
PURPOSE:To identify a target body to be measured by detecting information for identifying the body to be measured from a light beam which is incident from the body to be measured. CONSTITUTION:A semiconductor optical position detection element (PSD) 1 supplies a light beam emitted by a spot light source on the body to be measured to a current-voltage converting circuit 2, which converts it into voltage signals x1 and x2, and y1 and y2. An adding circuit 31 and a subtracter circuit 41 calculate x1+x2 and x1-x2 and an adder circuit 32 and a subtracter circuit 42 output y1+y2 and y1-y2, whose amplitudes are extracted by an AC processing circuit 5. The dividing circuits 61 and 62 perform subtraction between them and outputs a subtraction signal. A multiplexer 8, a sample/hold circuit 9, and an A/D converter 10 are controlled by a processor 11. The processor 11 outputs position coordinates (x) and (y) inputted from the A/D converter 10 to an output circuit 2 together with discrimination data on the body to be measured when the discrimination data inputted from a frequency detecting circuit 7 matches with one of set modulation frequencies.
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