Laser interferometer
AssigneeSeiko Epson Corporation
InventorsKohei Yamada, Takeshi Shimizu
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 an oscillation circuit that outputs the reference signal to the demodulation circuit, and the vibrator is a signal source of the oscillation circuit.
Claims8
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 from 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
- an oscillation circuit that includes a first capacitor and outputs, by making the vibrator oscillate, the reference signal to the demodulation circuit,
- wherein a first end of the vibrator is coupled to the first capacitor, and
- the vibrator serves as a signal source for the oscillation circuit.
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 from 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
- an oscillation circuit that outputs, by making the vibrator oscillate, the reference signal to the demodulation circuit,
- wherein the vibrator is a signal source of the oscillation circuit, and
- fosc−fQ≤600 [Hz] is satisfied, where fosc is an oscillation frequency of the oscillation circuit and fQ is a natural frequency of the vibrator.
Dependencies are inferred from the claim text.