| 摘要 |
PURPOSE:To enhance measuring accuracy and a measuring range and to shorten a measuring time, by finely adjusting a precise detection means corresponding to the detection result of a rough detection means receiving the reflected light from a measuring surface. CONSTITUTION:Light is allowed to irradiate a measuring surface such as a rotary surface and the reflected light therefrom is received by a rough detection part 16 having a wide measuring range and rough detection output corresponding to a surface state is converted to a digital value by an A/D converter 27 through an amplifier 25 to be supplied to a memory 28 or a display device 29. The output of the amplifier 25 is also supplied to a piezoelectric element 20 through a switching circuit 26 and the precise detection part 19 having a small opening of an objective lens is automatically and finely adjusted corresponding to the rough detection result to detect the surface state with high accuracy. By this method, measuring accuracy is enhanced and a measuring range is enlarged and a measuring time is shortened by automatic adjustment.
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