| 摘要 |
An electro-optical distance meter has a light-emitting element that is directed through a shutter to a target and returned from the target to a photodetector. Internal and external optical paths are continuously switched by the shutter with a predetermined time ratio. The internal optical path is used for calibrating the distance being measured. The meter reduces the measurement time and enhances accuracy. In one form, the shutter comprises a disc having a C-shaped opening with an index thereon for providing a reference signal. In another form, the shutter comprises a liquid crystal switch.
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