| 摘要 |
In an optical conversion and focusing system, the focusing is detected by means of an optical converter 24 with concentric radiation detector 25, 25', which produces all necessary electrical signals, from which one obtains the information content of the reflected beam, along with the information required for correction of the focus. In one embodiment, the detectors 25, 25' receive the light beam 23 through an additional magnifying lens. Changes in the focus have different effect on the beam impinging on the individual detectors, which results in corresponding changes in the output signal of the individual detectors 25, 25'. A focusing system with converter 24 moves a focusing lens 20 in dependence on the differential output signal from the individual detectors. An electrical difference circuit connected to the photodetectors 25, 25' produces a signal to operate a motor 32 moving a lens 20 in order to shift the focusing lens 20 along the beam axis. <IMAGE>
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