Abstract: A displacement calculation device 30 calculates a displacement based on two or more displacement detection signals differing in phase. The displacement calculating device 30 includes a detected displacement calculation unit 32 calculating a detected displacement based on the displacement detection signals, a signal analysis unit 33 calculating an amplitude error, a vibration center error, and a phase error between the displacement detection signals and a reference signal, a periodic displacement error calculation unit 34 calculating a periodic displacement error and a period of the displacement error based on the errors calculated by the signal analysis unit 33, and a displacement correction unit 35 correcting the detected displacement calculated by the detected displacement calculation unit 32, based on the displacement error and its period calculated by the periodic displacement error calculation unit 34, and outputting a corrected calibrated displacement.

Abstract: A rotary encoder 1 includes a rotary scale 2 having a cylindrical surface 2a as a detected surface and having a relative angle track 2b formed circumferentially on the cylindrical surface 2a, a sensor head 3 arranged with an interval from the cylindrical surface 2a and detecting the relative angle track 2b and outputting a detection signal, and a first angle calculator 4 calculating a rotation angle of the rotary scale 2 based on the detection signal from the sensor head 3. The rotary encoder 1 includes an angle error storage 7 storing an angle error corresponding to the size of the interval at each rotation angle calculated based on the detection signal from the sensor head 3, and an angle compensator 8 compensating the rotation angle calculated by the first angle calculator 4 based on the angle error at each rotation angle stored in the angle error storage 7.

Abstract: A displacement detecting device includes a non-contact sensor having a light source, an objective lens focusing output light from the light source onto a measurement surface, and a light receiving element detecting displacement information based on a focal length of the objective lens by using reflected light from the measurement surface; a control unit adjusting the focal length based on the displacement information; a displacement-amount measuring unit having a linear scale attached to the objective lens with a link member therebetween and measuring an amount of displacement of the linear scale when the focal length is adjusted. A light adjustment member is disposed between the light source and the objective lens or between the objective lens and the light receiving element and has an aperture section transmitting the output and/or reflected light therethrough and a light blocking section that blocks a specific light component of the output and/or reflected light.