Laser interferometer
AssigneeSeiko Epson Corporation
InventorKohei Yamada
Life of this patent
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Abstract
A laser interferometer includes a light source that emits first laser light, an optical modulator that includes a vibrator and modulates the first laser light by using the vibrator to generate second laser light including a modulated signal, a photodetector that receives interference light between third laser light including a sample signal generated by reflecting the first laser light on an object and the second laser light to output a light reception signal, a demodulation circuit that demodulates the sample signal from the light reception signal based on a reference signal, and a signal generator that outputs the reference signal input to the demodulation circuit and outputs a drive signal input to the optical modulator, in which Vd/Vr<10, where Vr is a voltage of the reference signal and Vd is a voltage of the drive signal.
Claims19
A laser interferometer comprising:
- a light source that emits first laser light;
- an optical modulator that includes a vibrator and modulates the first laser light by using the vibrator to generate second laser light including a modulated signal;
- a photodetector that receives interference light between third laser light including a sample signal generated by reflecting the first laser light on an object and the second laser light to output a light reception signal;
- a demodulation circuit that demodulates the sample signal from the light reception signal based on a reference signal;
- and
- a signal generator that outputs the reference signal input to the demodulation circuit and outputs a drive signal input to the optical modulator, wherein
- Vd/Vr<10, where Vr is a voltage of the reference signal and Vd is a voltage of the drive signal,
- the vibrator has a crystal AT resonator, and the crystal AT resonator is configured to vibrate by thickness sliding along a vibration direction,
- a diffraction grating is formed on a surface of the crystal AT resonator, and the diffraction grating is configured with a plurality of grooves,
- the second laser light is formed by modulating the first laser light at the plurality of grooves, and
- an extending direction of each of the plurality of grooves is perpendicular to the vibration direction.
Dependencies are inferred from the claim text.