| 摘要 |
An ophthalmoscopic instrument includes a main optical system, with a focusing optical device, for producing an image of the fundus of an eye on an imaging plane, on illuminating optical system for illuminating the fundus, and a target projecting optical system for producing images of a plurality of target marks on the fundus. A photoelectric sensor produces electrical signals based upon the images of the target marks formed on the fundus, and the signals are processed to determine the distances between the images of the target marks. The instrument further includes a circuit for receiving the electrical signals based upon the images of the target marks and discriminating between these electrical signals and anomalous signals, a circuit for controlling the focusing optical device based upon information concerning the distances between the images of the target marks, and a circuit for restricting the focusing optical device when an anomalous signals is detected.
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