| 摘要 |
PURPOSE:To measure variation in the relative angle between both bodies by mounting a light source on one body and a reception system with optical paths of two systems on the other body, performing phase detection mutually and measuring an interference amplitude, and reading the angle of incident light. CONSTITUTION:The light source is placed on the body 6' and light from it is converged by two condenser lenses 8 and 8' and converted by collimator lenses 9 and 9' into parallel beams. One beam is guided in the order of the lens 9, an optical attenuator or optical amplifier 14, an optical phase shifter 15, and an optical multiplexer 11 and the other beam is guided in the order of the lens 9', an optical attenuator or optical amplifier 14', an optical phase shifter 15', and the optical multiplexer 11. The body is moved from the direction of 5' to the direction of 6' and a shift in phase is calculated from the output levels of a photodetecting element 12 in the facing state and offset state at this time; and the relative angle variation theta between the bodies 5' and 6' can be measured from the wavelength of the light and light source distance (d).
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