| 摘要 |
PROBLEM TO BE SOLVED: To provide a focus detecting device easy to adjust, simple to control, wide in focus detectable range and capable of guiding focus direction without making position recognition impossible. SOLUTION: This device is equipped with a two-split photodetecting element 60 by which a surface to be measured is irradiated with the light from a light source output a signal corresponding to the quantity of the reflected light from the surface, a photodetection optical system which includes an objective 57 for guiding the reflected light to the two-split photodetecting element 60, photodetecting elements 61 and 62 which are arranged opposite at positions distant from the two-split photodetecting element 60 and output a signal corresponding to the quantity of light from the measured surface at a position that can not e detected by the two-split photodetecting element 60, and a signal processing system 63 which decides the position of the said measured surface according to the output signals of the two-split photodetecting element 60 and photodetecting elements 61 and 62. |
