| 摘要 |
PURPOSE:To eliminate speckles produced on the observation surface of an observation device so as to make observation with always excellent brightness by performing the observation by stopping a scanning light wheel at a desired point and inserting a removable diffusing plate into an observation system. CONSTITUTION:The rotary polygon mirror 13 of a scanning system is stopped from a rotating state through a stopping means 13a and a scanning light wheel which illuminates a wafer 2 is stopped at a desired position. The reflected light from the wafer 2 produced when the wafer 2 is irradiated with the scanning light of the light wheel is received by means of a photoelectric converting section 34 through beam splitters 17 and 61 and, at the same time, made incident on an observation system and visually observed through the erector 52 of a diffusing plate which can be removed by means of an observation system driving means 52a. When the observations are made, variation in brightness is reduced and observations can be always made with excellent brightness, since the occurrence of speckles is reduced by means of the erector 52. |
