Optical device and spectroscopic device
An optical device includes: an incident optical system; an analysis optical system; and a length measurement optical system. The incident optical system includes a laser light source, and an incident light dividing element that divides the laser light. The analysis optical system includes a first light dividing element that divides the first divided light and then mixes the light, a first mirror that adds a first modulation signal to the one first divided light by movement and reflection, a second mirror, and a first light receiving element that receives the first divided light including a sample-derived signal and the first modulation signal. The length measurement optical system includes a second light dividing element that divides the second divided light and then mixes the light, an optical feedback unit that feeds back the one second divided light to the second light dividing element, and a second light receiving element that receives the second divided light including a displacement signal generated by the first mirror.
1 . An optical device comprising:
an incident optical system;
an analysis optical system; and
a length measurement optical system, wherein
the incident optical system includes
a laser light source that emits laser light, and
an incident light dividing element that divides the laser light into first divided light and second divided light,
the analysis optical system includes
a first light dividing element that divides the first divided light into one and the other and then mixes the one first divided light and the other first divided light,
a first mirror that adds a first modulation signal to the one first divided light by moving in an incident direction of the one first divided light and reflecting the one first divided light,
a second mirror that reflects the other first divided light, and
a first light receiving element that receives the first divided light including the first modulation signal and a sample-derived signal generated by a sample, and outputs a first light receiving signal, and
the length measurement optical system includes
a second light dividing element that divides the second divided light into one and the other and then mixes the one second divided light and the other second divided light,
an optical feedback unit that feeds back the one second divided light emitted from the second light dividing element to the second light dividing element, and
a second light receiving element that receives the second divided light including a displacement signal generated by reflection of the other second divided light by the first mirror and outputs a second light receiving signal.
2 . The optical device according to claim 1 , wherein
the optical feedback unit includes a light reflector that reflects the one second divided light toward the second light dividing element.
3 . The optical device according to claim 1 , wherein
the optical feedback unit includes an optical modulator that is driven by a drive signal and adds a second modulation signal to the one second divided light.
4 . The optical device according to claim 3 , wherein
the optical modulator includes a resonator element that vibrates in response to the drive signal, and adds the second modulation signal to the one second divided light by reflecting the one second divided light by the resonator element that vibrates.
5 . The optical device according to claim 4 , wherein
the resonator element is a quartz crystal resonator, a silicon resonator, or a ceramic resonator.
6 . The optical device according to claim 1 , further comprising:
a wavelength conversion element configured to convert a wavelength of the first divided light.
7 . The optical device according to claim 6 , further comprising:
a light synthesizing unit configured to synthesize, after the first divided light is divided into one and the other, the one first divided light whose wavelength is converted by the wavelength conversion element and the other first divided light.
8 . The optical device according to claim 7 , further comprising:
a rotational phase difference plate configured to change a polarization ratio of the first divided light by rotation.
9 . The optical device according to claim 1 , wherein
the laser light source is a semiconductor laser element.
10 . A spectroscopic device comprising:
the optical device according to claim 1 ;
a signal generation unit configured to output a reference signal;
a moving mirror position calculation unit configured to generate, based on the reference signal, a moving mirror position signal indicating a position of the first mirror by performing calculation on the second light receiving signal;
a light intensity calculation unit configured to generate, based on the first light receiving signal and the moving mirror position signal, a waveform indicating an intensity of the first light receiving signal at each position of the first mirror; and
a Fourier transform unit configured to perform Fourier transform on the waveform to obtain spectrum information.
11 . The spectroscopic device according to claim 10 , wherein
the optical feedback unit includes an optical modulator that adds a second modulation signal to the one second divided light,
the optical modulator includes a resonator element that vibrates in response to a drive signal, and is configured to add the second modulation signal to the one second divided light by reflecting the one second divided light by the resonator element that vibrates, and
the signal generation unit includes an oscillation circuit that operates using the resonator element as a signal source, and outputs the reference signal and the drive signal.