| 摘要 |
PURPOSE:To obtain an inexpensive laser length measurement system while allowing a connection with a counter for two-phase (sin and cos) input which is used generally and conventionally by interposing a circuit between the optical system of an interferometer and a counter circuit. CONSTITUTION:An REF signal (d) is used by a pulse generating circuit to generate a 90 deg. and a 0 deg. pulse signal and a DOP signal (e) is inputted to an automatic gain circuit AGC to control its amplitude to a constant value and inputted to a sample holding circuit to generate a 90 deg. and a 0 deg. hold signal. Namely, the amplitude values of the signal (e) at positions a1, a2, a3... of the 90 deg. phase angle of the signal (d) are held and positions b1, b2, b3... are coupled to generate a solid-line signal (e); and the amplitude values of the signal (e) at positions c1, c2, c3... are held at positions of the 0 deg. phase angle to generate a solid-line signal (h). Then, this signal is passed through a low-pass filter circuit to obtain two sinesigma(X) and cossigma(X) signals (i) and (g). Those signals are used as input signals to the two-phase input counter whose quantity (X) of displacement is already known.
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