| 摘要 |
PURPOSE:To lower the error of a measured value due to transverse swinging of a measurement object and carry out measurement by overlaying scanning beams having 180 deg. different scanning phase to the measurement object and simultaneously carrying out reciprocal scanning. CONSTITUTION:Light from a laser light source 1 is divided into two by a half mirror 4. The polarization direction of one light is changed by 90 degree by an oscillator reflection mirror 11 of a tuning fork oscillator 3 and the polarization direction of the other light is changed by 90 degree by a 1/2 wavelength plate 5 and they are radiated to an oscillator reflection mirror 12. The lights are totally reflected by mirrors 11, 12 due to deflection oscillation of oscillating pieces 3a, 3b following the angle alteration of the oscillator 3. The lights having 180 deg. different phase mutually are converted into lights scanned sinusoidally and then overlaid on the same flat plane and reciprocally scan a measurement object W. That is, scanning beams having 180 deg. different scanning phase with synchronous time T are overlaid and simultaneous reciprocal scanning of the measurement object is carried out. As a result, the error of the measured value due to the transverse swinging of the measurement object is lowered and the measurement in the process of constantly precise in-line becomes possible. |
