| 摘要 |
PURPOSE:To constitute the device for measuring the length and configuration, by measuring the amount of movement of an optical system in the direction of an optical axis so that the average diameter of a speckle pattern of coherent light generated in reflected light indicates the maximum value. CONSTITUTION:The coherent light from a semiconductor laser 10 passes through lenses 11 and 12, and a Gaussian beam with a beam waist of omega0 is formed. Electrooptical element 13 is arranged in the lenses 11 and 12 and driven by a signal from a signal generator 14, and the length of the light path is equivalently varied. A body O is irradiated by said Gaussian beam, the reflected light is focussed on a light receiving element 20 through lenses 18 and 19, and an image signal corresponding to the speckle grain size is outputted. Said output passes an amplifier 21, a frequency to voltage converter 22, and a band pass filter 23, and the phase of the output is compared with the phase of the signal from the signal generator 14 in sensitive phase detector 24. The output is inputted to a servoamplifier 17. The lens 11 is moved along the optical axis by a linear actuator 16 so that the output of the servoamplifier 17 becomes zero, and the length and the configuration are measured from the amount of movement. |
