KR20230155844A - Apparatus for detecting optical beat signal and operating method thereof - Google Patents

Abstract

The optical beat signal detection device includes an optical frequency bit and an optical coupling unit that combines a signal to be measured at a specific frequency, a spectrometer that splits the combined signal in space in the optical coupling unit, and, among the split signals, the measurement target. A measurement unit including a narrow-band filter that passes an optical signal in a frequency band in which the signal overlaps, and a photodetector that detects an optical beat signal related to the specific frequency from the optical signal that passes the narrow-band filter, and the measurement object. and a control unit that aligns the spectrometer and the measurement unit so that the signal passes through the narrowband filter.

Description

Optical beat signal detection device and operating method thereof {APPARATUS FOR DETECTING OPTICAL BEAT SIGNAL AND OPERATING METHOD THEREOF}

This disclosure relates to optical beat signal detection.

Optical frequency comb is expressed as a discontinuous spectrum with a certain frequency interval (f _rep ) in the frequency domain, and is used as a frequency ruler in various research fields. In particular, laser frequency stabilization and absolute frequency measurement technology using optical frequency combs are continuously developing, and stabilized lasers can be used in various precision technologies. For example, an optical frequency comb can be used for optical heterodyne detection, which detects the optical characteristics of a laser through combination with the laser to be measured.

Optical heterodyne detection is a technology that detects a combined signal of adjacent signals output from different lasers, that is, an optical beat signal. Therefore, in order to detect an optical beat signal with a high signal-to-noise ratio, it is important to rectify only the laser signals in the overlapping band by removing surrounding signals. However, conventional optical beat detection technology rectifies laser signals using a narrow-band optical fiber filter. Additionally, conventional optical beat detection technology aligns the optical system in a passive manner. Therefore, the conventional optical beat detector has no choice but to detect only optical beats in a limited frequency band, and is sensitive to external environments (temperature changes, vibration, etc.), which may cause instability in the optical beat signal and cannot provide frequency variability.

The present disclosure provides a device for actively detecting an optical beat signal and a method of operating the same.

An optical beat signal detection device according to an embodiment, comprising an optical frequency comb and an optical coupling unit for combining a signal to be measured at a specific frequency, a spectrometer for dispersing the combined signal combined in the optical coupling unit in space, and a spectroscopic unit for splitting the combined signal in space. Among the signals, a narrow-band filter that passes an optical signal in a frequency band overlapping with the signal to be measured, and a photodetector that detects an optical beat signal related to the specific frequency from the optical signal that passes the narrow-band filter. and a control unit that aligns the spectrometer and the measurement unit so that the signal to be measured passes through the narrow-band filter.

The control unit generates a control signal to move the spectrometer and/or the measurement unit based on the signal intensity for each position measured by the photodetector, and transmits the control signal to the rotation stage on which the spectrometer is mounted and/or the measurement unit. It can be transmitted to the motion stage.

The photodetector may be an array photodetector in which a plurality of photosensors are arranged.

The control unit may control the measurement target signal to pass through a narrowband filter by moving the spectrometer and/or the measurement unit based on the spectral position of the measurement target signal.

The optical beat signal detection device may further include a beam position tracker that provides the control unit with the spectral position of the signal to be measured.

The spectrometer may include a diffraction grating (optical grating).

The narrow-band filter may separate and pass a frequency mode near the signal to be measured among the optical frequency bits.

The measuring unit may continuously detect the optical beat signal according to the frequency of the signal to be measured, which changes in the spectral range of the optical frequency beat.

An optical beat signal detection device according to another embodiment includes an optical frequency comb, an optical coupling unit that combines a signal to be measured at a specific frequency, and a diffraction phenomenon, and the combined signal from the optical coupling unit is spectralized in space. A spectroscopic unit that detects an optical beat signal related to the specific frequency from an optical signal incident through a narrow-band filter, and a spectral position of the signal to be measured using the signal to be measured included in a first diffraction mode. A beam position tracker that tracks, and a control unit that controls the movement of the measurement unit so that the measurement target signal included in the second diffraction mode passes through the narrowband filter based on the spectral position of the measurement target signal. The first diffraction mode and the second diffraction mode are symmetric modes.

The beam position tracker measures the signal to be measured included in the first diffraction mode, and provides the angular difference between the measurement position and the reference position as the spectral position of the signal to be measured, and the reference position is not diffracted in space. It may be a zero-order mode position.

The control unit may generate a control signal that positions the narrowband filter at a position separated by the angle difference from the reference position.

The spectral position of the signal to be measured included in the first diffraction mode may be symmetrical to the spectral position of the signal to be measured included in the second diffraction mode.

The spectrometer may include an optical grating and be fixed.

The narrow-band filter may separate and pass a frequency mode near the signal to be measured among the optical frequency bits.

An optical beat signal detection device according to another embodiment uses an optical frequency bit, an optical coupling unit that combines a measurement target signal of a specific frequency, and a diffraction phenomenon to spectrally analyze the combined signal from the optical coupling unit in space. A spectroscopic unit that detects an optical beat signal related to the specific frequency from an optical signal incident through a narrow-band filter, and a spectral position of the signal to be measured using the signal to be measured included in a first diffraction mode. A beam position tracker that tracks, and a control unit that controls the movement of the spectrometer so that the measurement target signal included in the second diffraction mode passes through the narrowband filter, based on the spectral position of the measurement target signal. . The first diffraction mode and the second diffraction mode may be symmetric modes.

The beam position tracker is arranged in space so that the target position for the measurement signal is symmetrical to the center position of the narrowband filter, and after measuring the measurement target signal included in the first diffraction mode, the measurement position and the target The distance difference between positions can be provided as the spectral position of the signal to be measured.

The control unit may generate a control signal to rotate the spectrometer so that the distance difference is canceled out.

The optical beat signal detection device may further include a Dove Prism that inverts the first diffraction mode incident on the beam position tracker.

The spectrometer may include a diffraction grating (optical grating).

The narrow-band filter may separate and pass a frequency mode near the signal to be measured among the optical frequency bits.

According to the embodiment, an optical beat signal with a high signal-to-noise ratio can be detected.

According to the embodiment, the optical beat signal can be actively detected regardless of the change in frequency of the signal to be measured.

According to an embodiment, an optical beat signal can be detected in a broadband corresponding to the spectral range of the optical frequency beat.

1 is a conceptual diagram of an optical beat signal detection device according to an embodiment.
Figure 2 is a configuration diagram of an optical beat signal detection device according to an embodiment.
Figure 3 is a configuration diagram of an optical beat signal detection device according to another embodiment.
Figure 4 is a configuration diagram of an optical beat signal detection device according to another embodiment.

Below, with reference to the attached drawings, embodiments of the present disclosure will be described in detail so that those skilled in the art can easily practice them. However, the present disclosure may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present disclosure in the drawings, parts that are not related to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification, when a part is said to “include” a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary.

1 is a conceptual diagram of an optical beat signal detection device according to an embodiment.

Referring to FIG. 1, the optical beat signal detection device 100 includes an optical frequency comb output from the pulse laser 10, and a measurement target signal (continuous wave) of a specific frequency output from the measurement target laser 20. signal) is input. The optical beat signal detection device 100 detects an optical beat signal between a signal to be measured and an optical frequency beat close to its frequency. Here, the optical frequency bit is a reference signal with a known frequency.

The optical beat signal detection device 100 is based on optical heterodyne detection, combines an optical frequency beat and a signal to be measured, and actively detects an overlapping frequency band in which the signal to be measured is present in the combined signal, thereby Beat signals can be detected. The optical beat signal has a frequency difference between the two signals, and detecting the optical beat signal may mean detecting the frequency of the optical beat signal, that is, the optical beat frequency (f _beat ). Among the optical frequency beats, the optical beat signal is detected by the frequency mode near the signal to be measured.

The pulse laser 10 outputs an optical frequency beat expressed as a discontinuous spectrum at a certain frequency interval (f _rep ) in the frequency domain. In the frequency domain, the nth comb-line of the optical frequency comb is called the nth frequency mode v _n . Each frequency mode v _n of the optical frequency bit is the carrier envelope offset frequency (simply referred to as “offset frequency”) (f _ceo ) and repetition rate (f _rep ), as shown in Equation 1. It is expressed as an integer multiple (n=1, 2, 3, …). n can simply be called the mode number.

[Equation 1]

_vn = nf _rep + f _ceo

The offset frequency and repetition rate of the optical frequency bit can be stabilized, for example, to an atomic clock, which is an absolute frequency reference. Through this stabilization, the frequency mode of the optical frequency bit has an accurate value and can be used as a reference signal.

The laser 20 to be measured is a single frequency laser that outputs a continuous wave signal of a single frequency (f _cw ). Meanwhile, the measurement target laser 20 may be a frequency tunable laser that can scan/sweep a wide frequency band.

The optical beat signal detection device 100 can detect the optical beat frequency corresponding to Equation 2. Since the repetition rate f _rep is a stabilized value, the frequency f _cw of the signal to be measured can be known through the optical beat frequency f _beat .

[Equation 2]

f _beat = v _n - f _cw

Ultimately, the optical beat signal detection device 100 must detect an optical beat signal with a high signal-to-noise ratio to accurately measure the frequency of the laser 20 to be measured. To this end, the optical beat signal detection device 100 can combine the optical frequency bit and the signal to be measured using an optical system and disperse the combined signal in space using a diffraction grating. Due to the diffraction phenomenon, the combined signal is divided into diffraction modes depending on the diffraction order, for example, the non-diffracted 0th order mode (m = 0), the diffracted 1st order mode (m = 1), and the -1st order mode (m =-1), etc. are distributed in space. In addition, a narrow-band filter (eg, Iris) is disposed so that the frequency band containing the signal to be measured in space is detected by the photodetector. A narrowband filter separates the frequency modes near the signal to be measured from the optical frequency bit. The optical beat signal detection device 100 can detect an optical beat signal from an optical signal that has passed through a narrow-band filter. The optical beat signal detection device 100 may detect the optical beat signal using an arrayed photodetector in which a plurality of optical sensors are arranged, or a photodetector consisting of a photodiode.

Meanwhile, the optical beat signal detection device 100 tracks the spectral position of the signal to be measured in space and actively aligns the diffraction grating and the narrow-band filter so that the signal to be measured passes through the narrow-band filter. To this end, the optical beat signal detection device 100 generates a control signal that aligns the diffraction grating and the narrow-band filter (eg, rotation angle of the diffraction grating, movement information of the narrow-band filter, etc.). The diffraction grating can be rotated by the control signal, and the measuring unit including the narrow-band filter can be moved. Through this active control, the optical beat signal detection device 100 can maximize the power of the signal to be measured passing through the narrow-band filter.

Through this active control, the optical bit signal can be stabilized and robust to the external environment. Additionally, unlike conventional technology that detects an optical beat signal in a fixed frequency band, the optical beat signal detection device 100 can actively detect the optical beat signal according to a change in the frequency of the signal to be measured. The optical beat signal detection device 100 can continuously detect the optical beat signal according to the frequency of the measurement target signal that changes in the spectral range of the optical frequency beat.

Figure 2 is a configuration diagram of an optical beat signal detection device according to an embodiment.

Referring to FIG. 2, the optical beat signal detection device 100A includes an optical coupling unit 110 that combines an optical frequency bit (OFC) and a measurement target signal (continuous wave signal, CW) of a specific frequency, and the combined signal is spatially It includes a spectrometer 120 that specifies light and a measurement part 130A that detects an optical signal that has passed through a narrow-band filter among the spectral signals. In addition, the optical beat signal detection device 100A may include a control unit 140A that controls the rotation stage on which the spectrometer 120 is installed and/or the motion stage on which the measurement unit is installed through a feedback control signal. The control unit 140A may include at least one processor that generates a control signal based on information obtained from optical elements. In addition, the optical beat signal detection device 100 may further include a driving device such as a motor that moves the rotation stage and/or the motion stage by a control signal, but detailed description will be omitted.

The optical coupling unit 110 is a free-space heterodyne optical system that combines the optical frequency comb, which is a reference signal, with the signal to be measured. The optical coupling unit 110 can configure optical elements to maximize the power of two optical signals output coaxially. The optical coupling unit 110 may be configured in various ways, but for example, a half-wave plate (HWP) (111, 112, 114), and a polarization beam splitter (PBS) (113, 115) may be included. The half-wave plate (HWP) (111, 112, 114) is an optical element that delays the wavelength of the incident beam by half a wavelength, and the polarizing beam splitter (PBS) (113, 115) splits the incident beam into a reflective S -It is an optical element that separates a polarized beam (reflected at 90 degrees) and a transmitted P-polarized beam (directly directed). The polarizing beam splitter (PBS) 113 combines the optical frequency comb and the measurement target signal in space with alternating polarization. The polarizing beam splitter (PBS) 113 makes the optical frequency comb and the signal to be measured into the same polarization. At this time, the half-wave plate (HWP) 111, 112, and 114 is used to adjust the polarization state of the incident/output laser beam.

The spectrometer 120 specifies signals with overlapping frequencies in space. The spectrometer 120 may be composed of a diffraction grating (optical grating). The spectrometer 120 diffracts the combined signal from the optical coupling unit 110 into a non-diffracted 0th order mode (m=0), a diffracted 1st order mode (m=1), and -1st order mode ( m=-1), etc. to disperse in space. Since the combined signal incident on the spectrometer 120 overlaps white light and monochromatic light, they are separated in space using a diffraction grating. Through this, the pattern of the optical bit signal can be simplified.

Meanwhile, the spectrometer 120 is mounted on a rotation stage and can be rotated by a control signal. Through this, the optical paths of the spectrometer 120 and the measurement unit 130A can be aligned.

The measurement unit 130A may include a narrowband filter 131A and an array photodetector 132A. The narrowband filter 131A may include at least one opening through which an optical signal may be incident. The array photodetector 132A may have a plurality of optical sensors arranged in a row and may be composed of N pixels. The measuring unit 130A is mounted on a motion stage and can be moved by a control signal. Through this, the optical path can be aligned so that the signal to be measured, split in a specific diffraction mode (for example, primary mode) of the spectrometer 120, is incident on the measurement unit 130A.

The narrowband filter 131A is aligned with the spectrometer 120, and an optical signal overlapping the signal to be measured is incident on the array photodetector 132A. Through the narrow-band filter 131A, only specific frequency modes close to the signal to be measured can be separated and incident among the optical frequency bits. The array photodetector 132A can detect an optical beat signal from the measurement target signal and the specific frequency mode signal that passed through the narrowband filter 131A. The optical signal passing through the narrow-band filter may be photoelectrically converted into an optical beat signal by the photodetector 132A.

The control unit 140A aligns the spectrometer 120 and the measurement unit 130A so that the signal to be measured passes through the center of the narrowband filter 131A. The control unit 140A may generate a control signal through beam position auto tracking technology and transfer the control signal to the spectrometer 120 and/or the measurement unit 130A to align them. Through the control signal, the signal to be measured at maximum intensity may be incident on the array photodetector 132A.

The control unit 140A may generate a control signal based on the signal strength of each measured position of the array photodetector 132A. Among the pixels of the array photodetector 132A, the signal intensity of the optical signal incident on the pixels corresponding to the opening of the narrowband filter 131A is measured. At this time, the control unit 140A may measure the signal intensity difference between the left and right pixels based on the center pixel corresponding to the center of the opening of the narrowband filter 131A, and generate a control signal based on the signal intensity difference. there is. That is, the control unit 140A aligns the spectrometer 120 and the measurement unit 130A through a control signal, and controls the maximum signal intensity to always be measured at the center pixel corresponding to the center of the opening of the narrowband filter 131A. .

The control unit 140A may feed back a control signal to the rotation stage on which the spectrometer 120 is installed and/or the motion stage on which the measurement unit 130A is installed. The rotation stage control signal may include the rotation angle of the diffraction grating. The motion stage control signal may include movement information of the narrowband filter 131A. By the motion stage control signal, the narrowband filter 131A and the array photodetector 132A can be moved together or either one of them can be moved.

Meanwhile, the frequency of the signal to be measured may vary. Then, the control unit 140A can automatically align the spectroscopic unit 120 and the measurement unit 130A by generating a control signal based on the signal intensity measured at the pixels of the array photodetector 132A. Through this, even if the frequency of the signal to be measured changes and approaches the arbitrary frequency mode of the optical frequency beat, the optical beat signal can be continuously measured.

Figure 3 is a configuration diagram of an optical beat signal detection device according to another embodiment.

Referring to FIG. 3, like the optical beat signal detection device 100A, the optical beat signal detection device 100B is an optical beat signal that combines an optical frequency bit (OFC) and a measurement target signal (continuous wave signal, CW) of a specific frequency. It includes a combining unit 110 and a spectroscopic unit 120 that specifies the combined signal in space. At this time, it is assumed that the spectrometer 120 is fixed.

The optical beat signal detection device 100B includes a measuring unit 130B that detects an optical signal that has passed a narrow-band filter among spectral signals, a control unit 140B that controls a motion stage on which the measuring unit 130B is installed, and a signal to be measured. It may include a beam position tracker (150B) that tracks the position of.

As explained in FIG. 2, the optical coupling unit 110 combines the optical frequency bit, which is a reference signal, and the signal to be measured. The spectrometer 120 specifies the incident combined signal in space through a diffraction grating (optical grating).

The measuring unit 130B may include a narrowband filter 131B and a photodetector 132B. The measuring unit 130B is mounted on a motion stage and can be moved by a control signal. Through this, the optical path can be aligned so that the signal to be measured is split in a specific diffraction mode (for example, primary mode) of the spectrometer 120 and is incident on the measurement unit 130B.

Through the narrow-band filter 131B, only specific frequency modes close to the signal to be measured can be separated and incident among the optical frequency bits. The photodetector 132B can detect the optical beat signal from the measurement target signal and the specific frequency mode signal that passed through the narrowband filter 131B. The optical signal passing through the narrow-band filter may be photoelectrically converted into an optical beat signal by the photodetector 132B.

The control unit 140B aligns the spectroscopic unit 120 and the measurement unit 130B based on the spectral position of the signal to be measured so that the signal to be measured passes through the center of the narrowband filter 131B. The control unit 140B may generate a control signal for controlling the motion stage of the measurement unit 130B based on the spectral position of the signal to be measured. The spectral position of the signal to be measured can be expressed as an angular difference from the reference position. The reference position may be a zero-order mode position that does not diffract in space. The control unit 140B may obtain the spectral position of the signal to be measured from the beam position tracker 150B.

The beam position tracker 150B is arranged to measure the diffracted signal to be measured in a diffraction mode (-1st order mode) that is symmetrical to the measurement diffraction mode (1st order mode) of the measurement unit 130B. The beam position tracker 150B calculates the angle difference (θ-) between the measured position and the reference position. The beam position tracker (150B) measures the signal to be measured using a camera consisting of an optical sensor such as a CCD (Charge-Coupled Device), an array photodetector, etc., and calculates the angle (θ-) from the fixed reference position to the measurement position. You can.

The spectral position (θ-) of the signal to be measured received from the beam position tracker 150B is symmetrical to the spectral position (θ+) of the signal to be measured in the measurement diffraction mode (first order mode). Accordingly, the control unit 140B may generate a control signal that positions the narrowband filter 131B at a position separated by an angle difference from the reference position. The control unit 140B may align the narrowband filter 131B of the measurement unit 130B with the measurement target signal position (θ+) in the measurement diffraction mode (first order mode) through a control signal.

Figure 4 is a configuration diagram of an optical beat signal detection device according to another embodiment.

Referring to FIG. 4, the optical beat signal detection device 100C, like the optical beat signal detection devices 100A and 100B, combines an optical frequency bit (OFC) and a measurement target signal (continuous wave signal, CW) of a specific frequency. It includes an optical coupling unit 110 that specifies the combined signal in space and a spectroscopic unit 120 that specifies the combined signal. At this time, it is assumed that the spectrometer 120 is mounted on a rotating stage.

The optical beat signal detection device 100C includes a measurement unit 130C that detects an optical signal that has passed a narrow-band filter among the spectral signals, a control unit 140C that controls the rotation stage on which the spectrometer 120 is installed, and a signal to be measured. It may include a beam position tracker (150C) that tracks the position of.

The optical coupling unit 110 combines the optical frequency bit, which is a reference signal, and the signal to be measured. The spectrometer 120 specifies the incident combined signal in space through a diffraction grating (optical grating).

The measuring unit 130C may include a narrowband filter 131C and a photodetector 132C, like the measuring unit 130B described in FIG. 3 . At this time, it is assumed that the measuring unit 130C is fixed.

Through the narrow-band filter 131C, only specific frequency modes close to the signal to be measured can be separated and incident among the optical frequency bits. The photodetector 132C can detect the optical beat signal from the measurement target signal and the specific frequency mode signal that passed through the narrowband filter 131C. The optical signal passing through the narrowband filter may be photoelectrically converted into an optical beat signal by the photodetector 132C.

The control unit 140C aligns the spectrometer 120 and the measurement unit 130C based on the spectral position of the signal to be measured so that the signal to be measured passes through the center of the narrowband filter 131C. The control unit 140C may generate a control signal for controlling the rotation stage of the spectrometer 120 based on the spectral position of the signal to be measured. The spectral position of the signal to be measured can be expressed as a distance error from the reference position. The reference position may be the center position of the narrowband filter 131C. The control unit 140C may obtain the spectral position of the signal to be measured from the beam position tracker 150C.

)를 계산할 수 있다. 빔 위치 추적기(150C)는 CCD(Charge-Coupled Device)와 같은 광센서, 어레이 광검출기 등으로 측정 대상 신호를 측정할 수 있다. 이때, 빔 위치 추적기(150C)로 입사되는 분광 신호는 도 3에서 설명한 바와 같이 1차 모드에 대칭된 -1차 모드가 입사될 수 있다. 또는, 빔 위치 추적기(150C)로 입사되는 분광 신호는 도브 프리즘(Dove Prism)(121)에 의해 회절각이 반전된 -1차 모드가 입사될 수 있다. The beam position tracker 150C is arranged in space so that the target position for the measurement signal is symmetrical to the center position of the narrowband filter 131C. The target position of the beam position tracker 150C and the center position of the narrowband filter 131C may be symmetrical with respect to the zero-order mode. The beam position tracker 150C measures the diffracted measurement target signal in a diffraction mode (-1st order mode) that is symmetrical to the measurement diffraction mode (1st order mode) of the measurement unit 130C, and measures the distance between the target position and the measurement position. difference(

) can be calculated. The beam position tracker (150C) can measure the signal to be measured using an optical sensor such as a charge-coupled device (CCD) or an array photodetector. At this time, the spectral signal incident on the beam position tracker 150C may include a -1st order mode that is symmetrical to the 1st order mode, as described in FIG. 3. Alternatively, the spectral signal incident on the beam position tracker 150C may be a -1st order mode whose diffraction angle is inverted by the Dove Prism 121.

The control unit 140C controls the measurement target signal in the measurement diffraction mode (first order mode) and the narrowband filter 131C based on the spectral position, that is, the distance difference (Δ), of the measurement target signal received from the beam position tracker 150C. You can see the difference in distance. Accordingly, the control unit 140C rotates the spectrometer 120 so that the distance difference between the target position and the measurement position is canceled out, and causes the measurement target signal in the measurement diffraction mode (first order mode) to be incident on the narrowband filter 131C. You can.

Meanwhile, the optical beat signal detection devices described with reference to FIGS. 2 to 4 are examples, and their components may be combined and modified in various ways.

In this way, through the optical bit signal detection device of the present disclosure, an optical bit signal with a high signal-to-noise ratio can be detected. Through the optical beat signal detection device of the present disclosure, the optical beat signal can be actively detected regardless of the change in frequency of the signal to be measured. Through the optical beat signal detection device of the present disclosure, the optical beat signal can be detected in a broadband corresponding to the spectral range of the optical frequency beat.

The embodiments of the present disclosure described above are not only implemented through devices and methods, but may also be implemented through programs that implement functions corresponding to the configurations of the embodiments of the present disclosure or recording media on which the programs are recorded.

Although the embodiments of the present disclosure have been described in detail above, the scope of the rights of the present disclosure is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present disclosure defined in the following claims are also possible. It falls within the scope of rights.

Claims (20)

An optical coupling unit that combines an optical frequency bit and a signal to be measured at a specific frequency,
A spectrometer that specifies the combined signal in the optical coupling unit into space,
Among the split signals, a narrow-band filter that passes an optical signal in a frequency band overlapping with the measurement target signal, and a photodetector that detects an optical beat signal related to the specific frequency from the optical signal that passes the narrow-band filter A measuring part that does, and
A control unit that aligns the spectrometer and the measurement unit so that the signal to be measured passes through the narrow-band filter.
An optical beat signal detection device comprising: In paragraph 1:
The control unit
A control signal is generated to move the spectrometer and/or the measurement unit based on the signal strength for each position measured by the photodetector, and the control signal is transmitted to a rotation stage on which the spectrometer is mounted and/or a motion stage on which the measurement unit is mounted. An optical bit signal detection device that transmits to. In paragraph 2,
The photodetector is an array photodetector in which a plurality of optical sensors are arranged. In paragraph 1:
The control unit
An optical beat signal detection device that controls the measurement target signal to pass through a narrowband filter by moving the spectrometer and/or the measurement unit based on the spectral position of the measurement target signal. In paragraph 4,
A beam position tracker that provides the control unit with the spectral position of the signal to be measured.
An optical beat signal detection device further comprising: In paragraph 1:
The spectrometer is
An optical beat signal detection device comprising an optical grating. In paragraph 1:
The narrowband filter is
An optical beat signal detection device that separates and passes a frequency mode near the signal to be measured from among the optical frequency bits. In paragraph 1:
The measuring part
An optical beat signal detection device that continuously detects the optical beat signal according to the frequency of the measurement target signal that changes in the spectral range of the optical frequency beat. An optical coupling unit that combines an optical frequency bit and a signal to be measured at a specific frequency,
A spectrometer that specifies the combined signal in space using a diffraction phenomenon,
a measuring unit that detects an optical beat signal related to the specific frequency from an optical signal incident through a narrow-band filter;
A beam position tracker that tracks the spectral position of the measurement target signal using the measurement target signal included in the first diffraction mode, and
Based on the spectral position of the signal to be measured, it includes a control unit that controls the movement of the measurement unit so that the signal to be measured included in a second diffraction mode passes through the narrow-band filter,
The first diffraction mode and the second diffraction mode are symmetrical modes. In paragraph 9:
The beam position tracker is
Measures the signal to be measured included in the first diffraction mode, and provides the angular difference between the measurement position and the reference position as the spectral position of the signal to be measured,
The reference position is a zero-order mode position that is not diffracted in space. In paragraph 10:
The control unit
An optical beat signal detection device that generates a control signal to position the narrowband filter at a position separated by the angle difference from the reference position. In paragraph 9:
The spectral position of the signal to be measured included in the first diffraction mode is symmetrical to the spectral position of the signal to be measured included in the second diffraction mode. In paragraph 9:
The spectrometer is
An optical beat signal detection device comprising an optical grating and being stationary. In paragraph 9:
The narrowband filter is
An optical beat signal detection device that separates and passes a frequency mode near the signal to be measured from among the optical frequency bits. An optical coupling unit that combines an optical frequency bit and a signal to be measured at a specific frequency,
A spectrometer that specifies the combined signal in space using a diffraction phenomenon,
a measuring unit that detects an optical beat signal related to the specific frequency from an optical signal incident through a narrow-band filter;
A beam position tracker that tracks the spectral position of the measurement target signal using the measurement target signal included in the first diffraction mode, and
Based on the spectral position of the signal to be measured, a control unit that controls the movement of the spectrometer so that the signal to be measured included in a second diffraction mode passes the narrow-band filter,
The first diffraction mode and the second diffraction mode are symmetrical modes. In paragraph 15:
The beam position tracker is
The target position for the measurement signal is arranged in space to be symmetrical to the center position of the narrowband filter, and after measuring the measurement target signal included in the first diffraction mode, the distance difference between the measurement position and the target position is calculated. An optical beat signal detection device that provides the spectral position of the signal to be measured. In paragraph 16:
The control unit
An optical beat signal detection device that generates a control signal to rotate the spectrometer so that the distance difference is canceled out. In paragraph 15:
An optical beat signal detection device further comprising a Dove Prism that inverts the first diffraction mode incident on the beam position tracker. In paragraph 15:
The spectrometer is
An optical beat signal detection device comprising an optical grating. In paragraph 15:
The narrowband filter is
An optical beat signal detection device that separates and passes a frequency mode near the signal to be measured from among the optical frequency bits.