| 摘要 |
A three-dimensional measuring apparatus has an optical probe built therein The optical probe includes a laser source onto a surface to be measured, a beam laser source, an objective lens for condensing a light from splitter for separating from an incident optical path a laser light reflected from the surface to be measured, a non-polarizing beam splitter for separating a separated light into two separated lights by a fixed separating ratio, independent of a direction of polarization, a first pin hole provided in front of a condensing point of one of the two separated lights separated by the non-polarizing beam splitter, a first photodetector for receiving the light passing through the first pin hole, a second pin hole provided in the rear of a condensing point of the other of the two separated lights separated by the non-polarizing beam splitter, a second photodetector for receiving the light passing through the second pin hole, and a driving means for driving the objective lens by a difference of outputs between the first and second photodetectors as an error signal for automatic focus control. Thus, the optical probe is free of focusing errors even if the inclining direction of the surface to be measured is changed.
|
