US 12,313,448 B2
Laser interferometer
Kohei Yamada, Shiojiri (JP); and Nobuhito Hayashi, Chino (JP)
Assigned to SEIKO EPSON CORPORATION, (JP)
Filed by SEIKO EPSON CORPORATION, Tokyo (JP)
Filed on Aug. 30, 2022, as Appl. No. 17/898,618.
Claims priority of application No. 2021-140894 (JP), filed on Aug. 31, 2021.
Prior Publication US 2023/0079613 A1, Mar. 16, 2023
Int. Cl. G01H 9/00 (2006.01); G01B 9/02 (2022.01); G01B 9/02002 (2022.01)
CPC G01H 9/00 (2013.01) [G01B 9/02 (2013.01); G01B 9/02002 (2013.01); G01B 9/02045 (2013.01); G01B 9/02083 (2013.01); G01B 2290/70 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A laser interferometer comprising:
a laser light source configured to emit laser light;
a light shield having an opening through which the laser light passes;
an optical modulator configured to modulate the laser light into reference light having a different frequency; and
a light receiving sensor configured to receive object light generated by reflecting the laser light by an object to be measured and the reference light and output a light receiving signal, wherein
0.10 [mm]≤φpin≤10.0 [mm], wherein φpin is a diameter of the opening,
the laser light that is incident on the optical modulator is collimated light,
an optical axis of the collimated light is a first optical axis,
when return light obtained by the reference light or the object light traveling toward the laser light source is generated, an optical axis of the return light is a second optical axis,
a position at which the collimated light is generated is a reference position, and
the first optical axis and the second optical axis are shifted from each other such that 0.10 [mm]≤Δy≤10.0 [mm], wherein Δy is a shift width between the first optical axis and the second optical axis at the reference position.