Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1997-10-14
2000-11-07
Le, Que T.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
2502018, 359399, G01J 120
Patent
active
061440213
ABSTRACT:
A surveying apparatus, such as a level, includes an autofocus system. An object to be observed through a telescope of the surveying apparatus, is brought into focus through the autofocus system. The autofocus system includes a pair of image forming lenses, each forming an image of the object, and a pair of line sensors, each having a plurality of light receiving elements defining a light receiving area. The object images are respectively formed on the light receiving areas through the pair of image forming lenses. A focusing lens group is provided in the telescope. A mechanism moves the focusing lens group along an optical axis of the telescope in accordance with data output from the pair of line sensors. A device for detecting a position of the focusing lens group and a mechanism for selecting a number of the plurality of light receiving elements of each of the pair of line sensors to be used in a focusing operation are provided. The number of light receiving elements is selected depending on the position of the focusing lens group detected by the detecting device. A device is provided for controlling the moving mechanism in accordance with data output from the selected number of the plurality of light receiving elements.
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Asahi Kogaku Kogyo Kabushiki Kaisha
Le Que T.
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