| 摘要 |
PROBLEM TO BE SOLVED: To invariably stably keep a focal position at the optimum state by accurately detecting the focal point of an inspection system without being affected by mechanical vibration or the disturbance of air. SOLUTION: An image from a sample 8 illuminated by a laser beam from a laser light source 1 is formed on a CCD line sensor 13 through an image forming optical system 12, and the sample 8 is inspected based on the image signal. A part of the laser beam illuminating the sample 8 is guided to a focal point detecting projector optical system 34 through an optical fiber 33 as a detection laser beam, and the detection beam is converted into parallel light. The detection beam is reflected on a half mirror 35 arranged in the image forming optical system 12, and it is radiated to the sample 8 through an objective lens 10. The detection laser beam reflected on the sample 8 is image-formed by the image forming optical system 12, it is received by a focusing sensor 36, and the position having the highest light reception quantity is detected as the focal position of the image of the sample 8. |
