| 摘要 |
PURPOSE:To check and adjust the measuring range and measuring sensitivity easily in matching with the surface runout of a plane to be measured by using the method where the radius of a measuring point is detected and the measured value is corrected and the method where the measuring optical device is designed so as to make the measured value independent of the radius. CONSTITUTION:A differential amplifier 31 obtains a difference signal between outputs 20A, 20B of an optical spot detector 7 in a figure. This signal corresponds to the position of an optical beam. A capacitor 33 and a resistor 34 pick up an AC component only, which is applied to a divider 35. Further, an adder 32 forms a sum signal of the outputs 20A, 20B, which is given to the divider 35 and the AC component of the difference signal is divided at the sum signal. The output of the divider 35 is supplied to a divider 36 and divided with the output of a sensor 21C. The output of the sensor 21C is proportional to the raius of the upper and lower runout measuring points, then the radius dependancy of the measuring value is eliminated by using the output of the divider 36. |
