| 摘要 |
PURPOSE:To reduce the size of a photodetection system without reference to the scanning width of a laser by constituting an optical system for light reception by arranging a mirror, which has an opening for passing laser light and refleceting surfaces on both sides of the opening adjacently, between a laser light source and a rotary polygon mirror. CONSTITUTION:Laser light emitted by the laser light source 1 passes through the opening 3 of the mirror 2 and is reflected by the rotary polygon mirror 6 and converged on the object surface of a body to be inspected through an f.theta lens 7. In this case, the mirror 2 which has the opening and reflecting surfaces is arranged between the laser light source 1 and rotary polygon mirror to make the laser light, converged on the surface to be inspected, scan through the rotary polygon mirror, but converged spots on photodetectors 11a and 11b are almost conjugate to the laser light, so they are independent of the scanning and shift in convergence position a little. Consequently, the light reception system can be constituted by interposing the small-sized mirror and condenser lenses 10a and 10b in the optical path without reference to the scanning width. Further, an observation can be made at nearly the same angle as the laser irradiation angle to the surface to be inspected. |
