| 摘要 |
A system for detecting movement of a camera having a variable optical element (2). The system comprises a beam splitter (7) for capturing a part of the light traversing the lens and for splitting into at least a pair of light beams (8, 10). For each of the light beams the system comprises a light sensor (9, 11). Each sensor is provided with a grating (9g, 11g) in the light path for each of the light sensors. The gratings of the sensors have substantially the same pitch, but are positioned with a shift (S) that in respect of the light beam impinging on said sensor differ. The system further comprising a comparator (5) for comparing time shifted signals from the light sensors.
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