FOCUSING SERVO DEVICE, IMAGE MEASURING DEVICE, AND FOCUSING SERVO METHOD

摘要

PROBLEM TO BE SOLVED: To provide a focusing servo device realizing the improvement of measuring accuracy without being influenced by the delay of the response speed of a moving means in the case of profile measurement.;SOLUTION: The focusing servo device is equipped with an image pickup unit 2 having a plurality of photodetectors for detecting the quantity of reflected light from an objective, respectively and a positional deviation detection means 27 outputting a focus error signal showing the deviation of the position of the objective from a focal position on the basis of the quantity of the reflected light detected by the photodetectors, respectively, and performing the profile measurement, a moving means 11 moving the unit 2 along a Z-axis, a position detection means 10 detecting the actual measured value of the position of the unit 2 moved by the moving means 11 in a Z-axis direction and a control means 3 controlling the driving of the moving means 11 so that the focus error signal outputted from the detection means 27 becomes zero. The control means 3 obtains a measured result value by adding a correction value previously set according to the output value of the focus error signal to the actual measured value of the unit 2 detected by the detection means 10.;COPYRIGHT: (C)2004,JPO