| 摘要 |
A computer cursor control device includes ( 1 ) a light source generating light directed toward a stationary surface, ( 2 ) an optional phase modulator, ( 3 ) an optional function generator causing the phase modulator to periodically phase shift the light, and ( 4 ) a signal processor determining a direction in which the device is moving from a beat frequency or an asymmetry in the light intensity. Another computer cursor control device includes ( 1 ) an optical element combining reference and measurement beams to form a heterodyned beam, ( 2 ) a phase modulator located in an optical path of the reference beam or the measurement beam, ( 3 ) a function generator causing the phase modulator to phase shift the reference beam, and ( 4 ) a signal processor determining a direction in which the device is moving from a beat frequency of the heterodyned beam.
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