| 摘要 |
PURPOSE:To improve the measurement precision by allowing a measuring member to face the outside circumference of a rotating body with a proper gap between them and scanning this gap with a spot light and detecting a prescribed higher harmonic component of the transmitted light to measure the width of the gap. CONSTITUTION:The tip of measuring member 2 is allowed to approach the outside circumference of a rotating body 1 to form a gap between Them. The laser light emitted from a laser oscillator 4 scans the gap as a scanning beam through an oscillating mirror 9. The light transmitted through the gap is converged by a light receiving optical system 15 and is converted photoelectrically by a photoelectric multiplier 14. The electrical signal is inputted to a lock-in amplifier 17 through a preamplifier 16. The amplifier 17 detects and outputs a prescribed higher harmonic component out of Fourier series components of the electrical signal. This output signal corresponds to the width of the gap, and the rotation precision of the rotating body 1 is measured on a basis of this signal. |
