ENCODER DEVICE, OPTICAL DEVICE AND EXPOSURE DEVICE

摘要

PROBLEM TO BE SOLVED: To suppress a light amount loss of reference light upon measurement of a relative movement amount using a diffraction grating.SOLUTION: An encoder 10 comprises: a diffraction grating 12 that is provided in a first member 6 and has an X direction as a periodical direction; a laser light source 16 that emits measurement light MX and reference light RX; a polarization beam splitting (PBS) member 24X that is provided in a second member 7, enters the measurement light MX almost vertically to the diffraction grating 12 and emits the reference light RX in a direction different from the measurement light MX; and a reference member 32X that is provided in the second member 7, deflects the reference light RX via reflection surfaces 32Xa and 32Xb by the almost same angles as mutually different two diffraction angles in the diffraction grating 12 and reflects the deflected reference light RX to the PBS member 24X as reference light RX1 and RX2.