PURPOSE: To facilitate discriminating the in-focus state and improve the reproducibility, by providing an aperture plate, which can be moved together with a condenser lens and a target, and crossing lines of a slit pattern directed to the light source side of the target.
CONSTITUTION: A condenser lens 3 and a target 4 consisting of a transmissive face having no diffusing property are provided. An optical system indicating focusing by coincidence of a divided image is provided which is constituted with an aperture plate 11 which can be moved in the direction of the optical axis together with the condenser lens 3 and the target 4 and is arranged near the front-side focus of the condenser lens 3, crossing line of the slit pattern directed to the light source side of the target 4, and two polarizing prisms 12 respective substrate directions cross and are orthogonal to each other.
SHINDOU OSAMU
AIURA HIROCHIKA
HARA TADAO
| JPS4950957A | 1974-05-17 | |||
| JPS5469455A | 1979-06-04 |
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