| 摘要 |
PURPOSE:To detect the change quantity of physical quantity with high sensitivity and high accuracy, by processing the interference fringe formed by reference light and object light by a signal processing circuit through an array sensor. CONSTITUTION:The linear or circular polarized beam emitted from a coherent laser beam source 17 is guided to a polarizing beam splitter 19 to obtain reference linear polarized beam 18a and position sensing linear polarized beam 18b of which the planes of polarization cross each other at a right angle. These polarized beams 18a, 18b are respectively guided to corner cubes 20, 21 to respectively obtain beams 18c, 18d parallel to the polarized beams 18a, 18b. Herein, the beam 18d changes in its phase according to the position of the corner cube 21 and the beams 18c, 18d are respectively reflected from and transmitted through the beam splitter 19 to become beam 18e. This beam 18e becomes equidistant linear interference fringes through a mirror 22, an objective lens 23, a double refraction wedge element 24 and a polarizing plate 25. Said interference fringes 26 are detected by an array sensor 27 and the output signal 28 thereof is processed by a signal processing circuit 29 to calculate the position of the corner cube 21 with high accuracy.
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