| 摘要 |
PROBLEM TO BE SOLVED: To provide a focus detecting device which securely detects a focus position based upon reflected light on a surface of a transparent sample and an autofocus device using the same. SOLUTION: The focus detecting device for focusing an objective of an optical system for observation on the transparent sample includes a lighting optical system which is provided separately from the optical system for observation and lights up the sample with luminous flux emitted by a light source emitting the low-coherent light through the objective, a first mirror which reflects the luminous flux emitted by the light source and made incident on a part of a pupil of the lighting optical system to shield the part of the pupil, a second mirror which deflects the low-coherent light reflected by the sample and passed through the objective, an interference optical system which returns the luminous flux reflected by the first mirror to guide the luminous flux to the same optical path with the luminous flux deflected by the second mirror, and a decision means of deciding whether the object is in focus on the surface of the sample to be observed based upon an observation result of interference between the two pieces of luminous flux whose optical paths are aligned with each other by the interference optical system. COPYRIGHT: (C)2007,JPO&INPIT |
