| 摘要 |
PURPOSE:To make a compensating calculation for the time lag of a measurement system in which the measured value distribution in forward and backward movements are approximately identical to each other without being dependent on scan speed by providing mainly a sensor unit, a traveling direction judgment part, a measuring position detecting part, and a sensor position compensating part. CONSTITUTION:Multiple sensors are mounted on a sensor unit 20, and each time lag of a measuring system has a specific value. When a unit 20 is moved to a reference measuring position by a sensor drive device 30, a measurement timing as a reference of each sensor is determined by a measuring position detecting part 40. Also a sensor position compensating part 70 outputs a position shift signal according to the traveling direction of the unit 20 to compensate it so that it measures the same point by moving forward/moving backward relative to the reference measuring position determined by the detecting part 40. Like this, because the response speed and traveling speed of the sensor are compensated, the affection of the lag of response of the measuring system and a variation of traveling speed is eliminated so as to make the top and bottom of a profile coincide with each other regardless of whether the traveling direction of the sensor is forward or backward. |
