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Angle measurement is widely used in various fields as an important part of geometric metrology. Optical angle measurement methods stands out from many angle measurement methods because of its high measurement accuracy. Due to the limitation of grating line density, it is difficult to further improve the measurement accuracy of grating angle measurement method which was widely used in industrial field. The creatively new angle measurement method combined the regular pyramid with the right-angle reflector is proposed in this paper. The rotation angle of the measured object is transformed into a rotating laser through the regular pyramid, the variation of the rotating laser is geometrically amplified through the right angle mirror to realize the amplification of the variation of the angle and laser displacement is measured by position sensitive detector (PSD). The measured angle is divided into several equal parts by the pyramid, which reduces the angle measurement range of each PSD. Through the alternating measurement of several PSDs, the large range of continuous angle measurement can be achieved. The measurement principle of angle sensor based on optical arm amplification is researched in this paper, the mathematical model is established, and the correctness of the principle is verified through simulation analysis and actual measurement experiment by the prototype of angle sensor. The experimental results showed that the measurement error is ± 2 “in the range of 0.78°.
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