| 摘要 |
A focus detecting device which comprises an objective lens for forming an image of an object, a condenser lens, located behind a predetermined focal plane of the objective lens, for converging the light passed through the objective lens, a pair of image re-forming lenses, located behind the condenser lens, for re-forming a pair of secondary images of the image formed by the objective lens on an off-axial region of the objective lens located at a position far from the optical axis thereof, a light direction changing device, located nearby the condenser lens, for changing the direction along which light bundles forming the secondary images passes towards the optical axis, and a light receiving device for receiving the pair of the secondary images formed by the secondary image forming means to produce a light intensity distribution signal representing the light intensity distribution of the secondary images, a focus condition calculating device for calculating a focus condition of the objective lens by means of detecting the positions of the pair of the secondary images in accordance with the light intensity distribution signal.
|
