| 摘要 |
PURPOSE: To detect a small variation of distance accurately through an inexpensive laser by arranging a beam splitter and a reference plane between the objective lens of a miscoscope and the reference plane. CONSTITUTION: An approximately parallel beam flux 11a is partially reflected on a split cube 12 toward a detector 13 and a luminous flux transmitting the cube 12 is focused through the objective lens 14 of a miscoscope to a measuring plane 15. The converged luminous flux is split through a beam splitter 16s into a measuring beam 11m and a comparison beam 11v which are reflected reflected on the splitter 16s and returned back to the cube 12 while being combined. The beam is reflected on the cube 12 toward a detector 18. In the detector 18, a beam having one polarizing direction is led to a detector 18d while the other is led to a detector 18e through a beam splitter 18s. When an optical path difference of aboutλ/4 is produced between the beams 11m, 11v through a delay element for two polarizing directions, the detectors 18d, 18e receive different signals and the variation of distance is detected accurately for the measuring plane 15 based on these signals. |
