Patent ID: 8610050

Claim:
An optical displacement detection apparatus that detects a displacement in a predetermined direction of a displacement detection target, the optical displacement detection apparatus comprising: a light source that emits a light beam; a scale in which a first track pattern and a second track pattern are formed while the predetermined direction is set to a longitudinal direction of each of the first track pattern and the second track pattern; a sensor head including a first photodetector that detects the light beam emitted from the light source through the first track pattern and generates a first signal and a second photodetector that detects the light beam emitted from the light source through the second track pattern and generates a second signal; and a signal processing unit that calculates the displacement based on the first signal and the second signal, wherein the scale or the sensor head is coupled to the displacement detection target, the first signal and the second signal include at least a first component that is offset by performing predetermined calculation of the first signal and the second signal and a second component that remains after the predetermined calculation and corresponds to an absolute displacement of the scale, and the first track pattern, the second track pattern, the first photodetector, the second photodetector, and the light source are disposed such that the detection of the first photodetector and the detection of the second photodetector are performed while correlated with each other.