| 摘要 |
PURPOSE:To detect the deviation of the focus of an objective lens and an objective plane using a simple optical system by irradiating light emitted from a light source on the surface of a body through an objective lens and receiving reflected light by a photodetector placed on an optical axis on a plane perpendicular to an optical axis and at a position off from the optical axis. CONSTITUTION:Light emitted from a light source 1 is reflected by a semitransparent mirror 2 and irradiates an objective plane 4 through an objective lens 3. Reflected light passes through the objective lens 3 and the semitransparent mirror 2 and enters a photodetector 5 placed on the optical axis Z put on X-Y plane perpendicular to the optic axis Z and photodetectors 6, 7 off from the above-mentioned detector. By detecting a signal obtained by subtracting the output of the photodetector 5 from the sum of the output of photodetectors 6 and 7, the deviation (e) of the focus of the objective lens 3 and the objective plane 4 can be detected using a simple optical system. |
