| 摘要 |
The reflector unit (8), such as a glass prism, is arranged to receive light, such as infrared light, from a length measuring unit placed at a point whose position is to be determined. A motor rotates the housing relatively to the base part (5) in order to align the reflector unit (8) with the length measurement unit. The housing supports a number of sensors (17) which monitor light emitted from a light transmitter arranged in the length measurement unit, so that dependent upon which sensors monitor the light the motor is controlled to align the reflector unit with the light transmitter. The sensors monitor pulsed light and the housing (3) has a front opening (7) in which the reflector unit (8) is arranged, and supports partly two front sensors arranged somewhat in front of the housing, and partly two rear sensors arranged somewhat behind the housing. |
