CN108444381B - Correction method for eliminating nonlinearity of frequency modulation interference signal of semiconductor laser - Google Patents
Correction method for eliminating nonlinearity of frequency modulation interference signal of semiconductor laser Download PDFInfo
- Publication number
- CN108444381B CN108444381B CN201810459743.3A CN201810459743A CN108444381B CN 108444381 B CN108444381 B CN 108444381B CN 201810459743 A CN201810459743 A CN 201810459743A CN 108444381 B CN108444381 B CN 108444381B
- Authority
- CN
- China
- Prior art keywords
- modulation
- frequency
- signal
- frequency modulation
- semiconductor laser
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02055—Reduction or prevention of errors; Testing; Calibration
- G01B9/0207—Error reduction by correction of the measurement signal based on independently determined error sources, e.g. using a reference interferometer
- G01B9/02072—Error reduction by correction of the measurement signal based on independently determined error sources, e.g. using a reference interferometer by calibration or testing of interferometer
- G01B9/02074—Error reduction by correction of the measurement signal based on independently determined error sources, e.g. using a reference interferometer by calibration or testing of interferometer of the detector
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Instruments For Measurement Of Length By Optical Means (AREA)
- Semiconductor Lasers (AREA)
Abstract
The invention relates to the technical field of frequency modulation interference sensing and measurement of semiconductor lasers, in particular to a method for correcting nonlinearity of a frequency modulation interference signal of a semiconductor laser. A correction method for eliminating nonlinearity of a semiconductor laser frequency modulation interference signal is characterized in that a second-order or above polynomial time domain transformation relation is built, a beat frequency interference signal of a frequency modulation continuous wave laser interference measurement system is extracted from time positions of a plurality of adjacent extreme points, a multivariate linear equation set related to a modulation transformation coefficient is built and solved to obtain an actual numerical value of the modulation transformation coefficient, the built second-order or above polynomial time domain transformation relation is substituted, and an actually measured beat frequency signal is transformed, so that nonlinearity correction of the semiconductor laser frequency modulation continuous wave interference signal is realized.
Description
Technical Field
The invention relates to the technical field of frequency modulation interference sensing and measurement of semiconductor lasers, in particular to a method for correcting nonlinearity of a frequency modulation interference signal of a semiconductor laser.
Background
Displacement, stress, temperature sensors based on the principle of optical Frequency Modulated Continuous Wave (FMCW) interference, and fiber optic gyroscopes, all require the use of a coherent light source with continuous linear modulation of frequency. At present, a single-mode semiconductor laser is considered as the most suitable frequency modulation coherent light source, because the semiconductor laser frequency modulation method is simpler, and the frequency modulation can be realized by directly modulating the driving current. However, the non-linear relationship between the driving current and the output frequency of the semiconductor laser makes the output frequency of the semiconductor laser not change linearly with time under the control of the linear modulation driving current, which brings great measurement errors to a sensing measurement device or system based on the optical frequency modulation continuous wave interference principle. Therefore, how to eliminate the nonlinearity of the frequency modulation interference signal of the semiconductor laser is the key of the optical frequency modulation continuous wave interference measurement.
In a frequency-modulated continuous wave interferometry system, nonlinearity of a frequency-modulated interference signal of a semiconductor laser is usually eliminated by directly correcting the nonlinearity of the output frequency of the semiconductor laser. There are two main methods, one is an open-loop calibration method and the other is a closed-loop calibration method. The basic approach of open loop correction is to find a specific form of non-linear modulation drive current, so that the output frequency of the semiconductor laser changes in a linear form with time. By measuring the output frequency under the constant current input condition, a database is established to fit a drive current waveform that linearizes the laser output frequency. The closed-loop correction method is to establish a feedback loop by adopting a time-delay self-heterodyne photoelectric phase-locked loop, namely to convert a laser frequency modulation slope value into an interferometer beat frequency signal frequency by using an interferometer light path structure, to compensate the frequency difference of the beat frequency signal in a negative feedback mode by taking the frequency or the phase as a closed-loop correction value, and to realize the stabilization of the laser output signal modulation slope by stabilizing the beat frequency signal frequency of the interferometer, namely to realize the linearization correction of the laser output frequency modulation signal. The open loop correction method has the advantages of simple hardware system structure and easy implementation, but has the problem of low linear frequency modulation precision. The closed-loop correction method can realize high-precision nonlinear correction, but the system is complex, and the linear frequency modulation range is greatly limited because the locking range of the photoelectric phase-locked loop is limited. Both the open-loop correction method and the closed-loop correction method belong to pre-correction, a correction optical path is additionally used, and the semiconductor laser output frequency modulation linearization is realized in advance by adjusting the drive current of the semiconductor laser, so that the aim of correcting the nonlinearity of the frequency modulation interference signal is fulfilled.
Disclosure of Invention
The invention provides a correction method for eliminating nonlinearity of a frequency modulation interference signal of a semiconductor laser, which can realize the nonlinearity correction of the frequency modulation interference signal without changing the drive current of the semiconductor laser in advance and without any extra hardware overhead.
In order to achieve the purpose, the invention adopts the technical scheme that:
a correction method for eliminating nonlinearity of a semiconductor laser frequency modulation interference signal is characterized in that a second-order or above polynomial time domain transformation relation is built, a beat frequency interference signal of a frequency modulation continuous wave laser interference measurement system is extracted from time positions of a plurality of adjacent extreme points, a multi-linear equation set related to a modulation transformation coefficient is built and solved to obtain an actual numerical value of the modulation transformation coefficient, the built second-order or above polynomial time domain transformation relation is substituted, and an actually measured beat frequency signal is transformed, so that nonlinearity correction of the semiconductor laser frequency modulation continuous wave interference signal is achieved.
A correction method for eliminating nonlinearity of a frequency modulation interference signal of a semiconductor laser comprises the following steps:
the method comprises the following steps: the semiconductor laser is driven by linearly modulated sawtooth waves or triangular waves, in a frequency modulation continuous wave interference measurement system, a photoelectric detector is used for carrying out photoelectric conversion on a frequency modulation continuous wave interference beat frequency signal, and the converted frequency modulation continuous wave interference beat frequency signal is expressed as follows:
wherein T is the beat frequency period, I0For signal amplitude, V is signal modulation degree, and the optical wave frequency can be expressed as:
step two: extracting a plurality of extreme point corresponding time positions from the frequency-modulated continuous wave interference beat frequency signals after photoelectric conversion according to a rule, adopting a polynomial of 2-N order for a time domain transformation formula, establishing an N +1 element linear equation set related to a modulation transformation coefficient, and finally solving a linear equation set related to the modulation transformation coefficient of the time domain transformation formula to obtain a modulation transformation coefficient;
step three: and carrying out time domain transformation on the measured beat frequency signal by the obtained modulation transformation coefficient to obtain a transformed frequency modulation interference signal, thereby realizing the nonlinear correction of the frequency modulation interference signal.
Further, in the second step, in the frequency modulation continuous wave interference beat frequency signal, the corresponding time positions t of 4 adjacent extremum points are extracted1、t2、t3And t4And solving the modulation transformation coefficient K related to the time domain transformation formula0、K1And K2The system of three-dimensional linear equations of:
to obtain K0、K1And K2Three modulation transform coefficients;
the third step is that: and according to the obtained modulation transformation coefficient, carrying out coordinate transformation on the beat frequency signal in a time domain:
t'＝(K0+K1t+K2t2)t，
here, t' is a new time coordinate, and the result is the corrected signal without the effect of the nonlinear frequency modulation:
further, in the second step, the time positions t corresponding to the N +2 adjacent extremum points are taken1、t2、...、tN+2And establishing a transform coefficient K for modulation0、K1、...、KNN +1 element linear equation set:
solving the system of linear equations, K can be obtained0、K1、...、KNN +1 modulation transformation coefficients；
The third step is that: and according to the obtained modulation transformation coefficient, performing time domain transformation on the measured beat frequency signal: t' ═ K0+K1t+K2t2+...KNtN) t, obtaining a transformed frequency-modulated interference signal
Further, in the second step, the time positions t corresponding to the N +2 extreme point points are selected in a jumping manner1、t2、...、tN+2Let t beiAnd ti+1K-1 extreme points are arranged between the corresponding extreme points, and the transformation coefficient K is modulated in an N +1 linear equation set0、K1、...、KNThe linear equation of (a) is:
K1、...、KNby analogy, solving the corresponding linear equation set to obtain K0、K1、...、KNN +1 modulation transform coefficients;
and step three, according to the obtained modulation transformation coefficient, performing time domain transformation on the measured beat frequency signal, wherein t ═ K0+K1t+K2t2+...KNtN) t, obtaining a converted frequency modulation interference signal,
further, in the second step, when the corresponding linear equation set is solved, the modulation transformation coefficient is solved by using a least square method.
Compared with the prior art, the invention has the advantages that:
1. the invention carries out post-correction on the nonlinearity of the frequency modulation interference signal, and the method does not need an additional correction auxiliary device and eliminates the nonlinearity of the output frequency of the frequency modulation continuous wave semiconductor laser, thereby being very easy to implement without adjusting the driving current of the semiconductor laser.
2. The method utilizes the extreme point data of the original interference signal to calculate the nonlinear modulation conversion coefficient of the frequency modulation interference signal of the semiconductor laser, and then corrects the nonlinear frequency modulation interference signal through simple time domain conversion, so that the phase discrimination error caused by the frequency modulation nonlinearity (including the central frequency offset of the semiconductor laser) of the semiconductor laser can be greatly reduced, and the measurement precision of the frequency modulation interference sensing system of the semiconductor laser is obviously improved.
3. And any extra hardware overhead is not needed, so that the cost is saved, and the original equipment is easy to modify. The method can be used for various frequency modulation continuous wave interference measurement systems based on the semiconductor laser, and improves the measurement precision of the optical frequency modulation continuous wave interference measurement system taking the semiconductor laser as a transmitting light source.
Drawings
FIG. 1 is a waveform of a nonlinear frequency modulated continuous wave laser interference beat signal before correction.
Fig. 2 is a waveform after correction of a non-chirped beat signal using the method of the present invention.
Detailed Description
The invention will be explained in more detail below with reference to specific embodiments and the accompanying drawings.
The invention provides a correction method for eliminating nonlinearity of a semiconductor laser frequency modulation interference signal, which is characterized in that a photoelectric detector is used for converting the semiconductor laser frequency modulation interference signal into an analog electric signal, and after filtering, amplification and AD conversion, extreme value extraction is carried out on data.
The method comprises the steps of constructing a time domain transformation formula in a second-order or higher-order polynomial form containing a plurality of modulation conversion coefficients, extracting the time positions of a plurality of adjacent (or nonadjacent) peak values by carrying out frequency modulation interference beat signals on a semiconductor laser after photoelectric conversion into an established multivariate linear equation set related to the modulation conversion coefficients, solving to obtain the modulation conversion coefficients, and realizing mathematical conversion from actually measured nonlinear frequency modulation interference signals to linear beat signals by the time domain transformation formula in the polynomial form.
According to the theory of optical frequency modulation continuous wave interference, if the laser frequency is linear modulation, for any two-beam optical frequency modulation continuous wave interference system, a beat frequency signal is generated by two frequency modulation laser interferences which are subjected to different time delays. Assuming that the average intensity of the reference light is I1Average intensity of signal light is I2Then the beat signal can be expressed as:
wherein, I0＝I1+I2V is the contrast of the beat signal, an
Δ v is the optical frequency modulation width, vmIs the frequency of the modulated signal, c is the speed of light, t is the time, λ0Wavelength of light wave in vacuum, vbFor the beat frequency signal frequency, phi0Is the initial phase of the beat signal. OPD is the optical path difference between the reference light and the signal light, and it is obvious that:
when the reference light and signal light optical path OPD are transformed due to external physical quantity, the initial phase of the beat frequency signal is changed correspondingly. When an external physical quantity causes a change in OPD of delta OPD, accordingly,
the beat frequency variation is:
phi of initial phase0The offset is:
from the above analysis, the optical path and the optical path variation can be reversely deduced by measuring the beat frequency and the initial phase, and the method is used for measuring and sensing the external physical quantity. Obviously, due to the nonlinearity of the frequency modulation signal of the semiconductor laser, the initial phase and the frequency cannot be accurately acquired, and the measurement accuracy of the frequency modulation continuous wave interference sensing is seriously affected. To this end, the invention provides the following method:
example 1:
a correction method for eliminating nonlinearity of a frequency modulation interference signal of a semiconductor laser comprises the following steps:
step 1: assuming that the mathematical expression of the ideal frequency modulated continuous wave interference beat signal i (t) is:
here, T is 1/vbThe optical path difference between the two paths of frequency modulated laser is determined.
When the laser light source has nonlinear frequency modulation, the frequency of the frequency modulation interference beat frequency signal changes, so that nonlinearity exists. Utilize photoelectric detector to convert semiconductor laser frequency modulation interference optical signal into analog signal, after filtering, enlargiing and AD conversion again, the beat frequency signal that obtains can be represented by quadratic polynomial, and this moment beat frequency signal mathematical expression is:
here, I0For the signal amplitude, V is the signal modulation degree, T is the signal period, and K0, K1, and K2 are the modulation coefficients of the beat signal frequency. FIG. 1 shows a waveform of a nonlinear frequency modulated continuous wave laser interference beat signal before correction.
Step 2: as for the original signal after the AD conversion,extracting the corresponding time t of 4 adjacent extreme points1、t2、t3And t4A ternary system of linear equations for the modulation coefficients K0, K1, and K2 is established:
wherein, T is determined by the optical path difference of two paths of frequency-modulated lasers participating in beat frequency interference, so that the ternary linear equation set is solved to obtain the modulation transformation coefficient K of the beat frequency signal frequency0、K1And K2；
And step 3: and according to the obtained modulation transformation coefficient, carrying out coordinate transformation on the beat frequency signal in a time domain:
t'＝(K0+K1t+K2t2)t，
here, t' is a new time coordinate. The result is the corrected signal with the effect of the nonlinear frequency modulation removed:
in fig. 2, the waveform of the nonlinear frequency modulated continuous wave laser interference beat signal shown in fig. 1 after being corrected by the correction method of the present invention is shown, and it can be seen that the signal period inequality caused by the frequency nonlinearity in the original waveform is not corrected to be the waveform with the same period, i.e. the frequency nonlinearity is well eliminated.
Example 2:
a correction method for eliminating nonlinearity of a frequency modulation interference signal of a semiconductor laser comprises the following steps:
step 1: as in example 1, the beat signal is obtained by the mathematical expression:
step 2: in this embodiment, the time domain transformation formula may adopt third order and N order of more than third orderPolynomial corresponding to modulation transform coefficient of K0、K1、...、KNFor the third order and the N-order polynomials above the third order, the time positions t corresponding to the N +2 adjacent extreme points are taken1、t2、...、tN+2And establishing a transform coefficient K for modulation0、K1、...、KNN +1 element linear equation set
Solving the system of linear equations, K can be obtained0、K1、...、KNN +1 modulated transform coefficients, and,
and step 3: and according to the obtained modulation transformation coefficient, performing time domain transformation on the measured beat frequency signal: t' ═ K0+K1t+K2t2+...KNtN) t, obtaining a transformed frequency-modulated interference signal
The nonlinearity of the frequency modulation interference signal is corrected.
Example 3:
a correction method for eliminating nonlinearity of a frequency modulation interference signal of a semiconductor laser comprises the following steps:
step 1: as in example 1, the beat signal is obtained by the mathematical expression:
step 2: in this embodiment, the time positions t corresponding to the N +2 extreme point points can be selected in a jumping manner1、t2、...、tN+2That is, any two extreme points selected in sequence may not be adjacent, such as tiAnd ti+1K-1 extreme points between the corresponding extreme points, and the corresponding modulation conversion coefficient K in the N +1 linear equation set0、K1、...、KNBecomes:
other concerning modulation of transform coefficient K0、K1、...、KNBy analogy, solving the corresponding linear equation set to obtain K0、K1、...、KNN +1 modulation transform coefficients;
step 3, according to the obtained modulation transformation coefficient, time domain transformation is carried out on the measured beat frequency signal,
t'＝(K0+K1t+K2t2+...KNtN) t, obtaining a converted frequency modulation interference signal,
From the viewpoint of computational efficiency and real-time performance, embodiment 1 is the best embodiment, and if it is desired to improve the correction of the nonlinearity of the frequency-modulated interference signal, the conversion relationship of three or more orders in embodiment 2 or embodiment 3 may be considered.
The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.
Claims (5)
1. A correction method for eliminating nonlinearity of a frequency modulation interference signal of a semiconductor laser is characterized by comprising the following steps: the method comprises the following steps:
the method comprises the following steps: the semiconductor laser is driven by linearly modulated sawtooth waves or triangular waves, in a frequency modulation continuous wave interference measurement system, a photoelectric detector is used for carrying out photoelectric conversion on a frequency modulation continuous wave interference beat frequency signal, and the converted frequency modulation continuous wave interference beat frequency signal is expressed as follows:
wherein T is the beat frequency period, I0For signal amplitude, V is signal modulation degree, and the optical wave frequency can be expressed as:
step two: extracting a plurality of extreme point corresponding time positions from the frequency-modulated continuous wave interference beat frequency signals after photoelectric conversion according to a rule, adopting a polynomial of 2-N order for a time domain transformation formula, establishing an N +1 element linear equation set related to a modulation transformation coefficient, and finally solving a linear equation set related to the modulation transformation coefficient of the time domain transformation formula to obtain a modulation transformation coefficient;
step three: and carrying out time domain transformation on the measured beat frequency signal by the obtained modulation transformation coefficient to obtain a transformed frequency modulation interference signal, thereby realizing the nonlinear correction of the frequency modulation interference signal.
2. A correction method for eliminating semiconductor laser frequency modulation interference signal nonlinearity as claimed in claim 1, wherein: in the second step, extracting the time positions t corresponding to 4 adjacent extreme points from the frequency modulation continuous wave interference beat signals1、t2、t3And t4And solving the modulation transformation coefficient K related to the time domain transformation formula0、K1And K2The system of three-dimensional linear equations of:
to obtain K0、K1And K2Three modulation transform coefficients;
the third step is that: and according to the obtained modulation transformation coefficient, carrying out coordinate transformation on the beat frequency signal in a time domain:
t'＝(K0+K1t+K2t2)t，
here, t' is a new time coordinate, and the result is the corrected signal without the effect of the nonlinear frequency modulation:
3. a correction method for eliminating semiconductor laser frequency modulation interference signal nonlinearity as claimed in claim 2, wherein: in the second step, the time positions t corresponding to the N +2 adjacent extreme points are taken1、t2、...、tN+2And establishing a transform coefficient K for modulation0、K1、...、KNN +1 element linear equation set:
solving the system of linear equations, K can be obtained0、K1、...、KNN +1 modulation transform coefficients;
the third step is that: and according to the obtained modulation transformation coefficient, performing time domain transformation on the measured beat frequency signal: t' ═ K0+K1t+K2t2+...KNtN) t, obtaining a transformed frequency-modulated interference signal
4. A correction method for eliminating semiconductor laser frequency modulation interference signal nonlinearity as claimed in claim 2, wherein: in the second step, the time positions t corresponding to the N +2 extreme point points are selected in a jumping manner1、t2、...、tN+2Let t beiAnd ti+1K-1 extreme points are arranged between the corresponding extreme points, and the transformation coefficient K is modulated in an N +1 linear equation set0、K1、...、KNThe linear equation of (a) is:
K1、...、KNby analogy, solving the corresponding linear equation set to obtain K0、K1、...、KNN +1 modulation transform coefficients;
and step three, according to the obtained modulation transformation coefficient, performing time domain transformation on the measured beat frequency signal, wherein t ═ K0+K1t+K2t2+...KNtN) t, obtaining a converted frequency modulation interference signal,
5. a correction method for eliminating nonlinearity of a semiconductor laser frequency-modulated interference signal according to claim 2, 3 or 4, wherein: and in the second step, when solving the corresponding linear equation set, solving the modulation transformation coefficient by using a least square method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810459743.3A CN108444381B (en) | 2018-05-15 | 2018-05-15 | Correction method for eliminating nonlinearity of frequency modulation interference signal of semiconductor laser |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810459743.3A CN108444381B (en) | 2018-05-15 | 2018-05-15 | Correction method for eliminating nonlinearity of frequency modulation interference signal of semiconductor laser |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108444381A CN108444381A (en) | 2018-08-24 |
| CN108444381B true CN108444381B (en) | 2020-02-14 |
Family
ID=63203664
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810459743.3A Active CN108444381B (en) | 2018-05-15 | 2018-05-15 | Correction method for eliminating nonlinearity of frequency modulation interference signal of semiconductor laser |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108444381B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109870677B (en) * | 2019-03-13 | 2023-02-24 | 西安工业大学 | Frequency modulation continuous wave interference signal amplitude normalization method |
| CN110146012B (en) * | 2019-06-11 | 2021-07-02 | 西安工业大学 | Semiconductor laser nonlinear frequency modulation pre-correction method |
| CN110375864B (en) * | 2019-07-18 | 2021-07-02 | 西安工业大学 | Method for expanding frequency modulation continuous wave laser interference measurement range |
| CN114096873A (en) * | 2020-03-17 | 2022-02-25 | 深圳市速腾聚创科技有限公司 | Linear frequency sweep correction method, device, storage medium and system |
| CN112083401B (en) * | 2020-09-16 | 2023-07-28 | 浙江光珀智能科技有限公司 | Nonlinear correction device and method for frequency modulation continuous wave laser radar |
| CN114063032B (en) * | 2022-01-11 | 2022-04-29 | 杭州洛微科技有限公司 | Calibration method and calibration device |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101839686B (en) * | 2010-03-26 | 2012-05-23 | 中国计量科学研究院 | Nonlinear error correction method of laser interferometer, device and interferometer applying method and device |
| CN103176173B (en) * | 2013-02-16 | 2014-07-30 | 哈尔滨工业大学 | Non-linear correction method for LFMCW (linear frequency modulated continuous wave) laser radar frequency modulation based on optical fiber sampling technology |
| CN103928835B (en) * | 2014-03-20 | 2016-10-26 | 华侨大学 | The nonlinear response bearing calibration of a kind of semiconductor laser light source and device |
| CN103837870B (en) * | 2014-03-20 | 2016-01-20 | 华侨大学 | Continuous Wave with frequency modulation laser radar Nonlinear frequency modulation response coefficient measuring method |
| CN107104736B (en) * | 2016-02-19 | 2019-08-30 | 光联通讯有限公司 | A kind of optical transmission and its operating method with Mach-Zhan De modulator |
-
2018
- 2018-05-15 CN CN201810459743.3A patent/CN108444381B/en active Active
Non-Patent Citations (1)
| Title |
|---|
| 半导体泵浦全固态Nd:YVO4线性宽带调频激光技术研究;徐新瑞;《中国优秀硕士学位论文全文数据库》;20171231;全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108444381A (en) | 2018-08-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108444381B (en) | Correction method for eliminating nonlinearity of frequency modulation interference signal of semiconductor laser | |
| US10502632B2 (en) | High precision wavelength measurement and control of a tunable laser | |
| CN108120378B (en) | Sine phase modulation interference absolute distance measuring device and method based on femtosecond optical frequency comb | |
| CN104237894A (en) | Interferometric determination of distance change with laser diode | |
| JP2017181115A (en) | Optical frequency domain reflection measurement device and optical frequency domain reflection measurement method | |
| Deng et al. | Precision improvement in frequency-scanning interferometry based on suppressing nonlinear optical frequency sweeping | |
| JP2015060961A (en) | Wavelength control system and wavelength control method | |
| CN111562564B (en) | Frequency modulation continuous wave laser ranging nonlinear correction device and method | |
| Melchionni et al. | Development of a design tool for closed-loop digital vibrometer | |
| US20140300900A1 (en) | Optical fiber sensor | |
| CN106092162B (en) | A kind of fiber grating sensing demodulation Peak Search Method of Feedback of Power formula | |
| JP2017005487A (en) | Digital temperature/voltage compensated oscillator | |
| CN110146012B (en) | Semiconductor laser nonlinear frequency modulation pre-correction method | |
| CN112083401B (en) | Nonlinear correction device and method for frequency modulation continuous wave laser radar | |
| CN116131095A (en) | Linear frequency modulation continuous wave laser, calibration method and algorithm processing flow in calibration process | |
| CN113074713B (en) | High-dynamic control method of fiber-optic gyroscope | |
| US6275328B1 (en) | Amplifier control | |
| CN115220054A (en) | Double-optical-comb distance measurement system and method based on micro heater for adjusting repetition frequency | |
| US10756671B2 (en) | Temperature compensation for a voltage controlled oscillator | |
| Deng et al. | Suppression of nonlinear optical frequency sweeping in frequency-scanning interferometry for absolute distance measurement | |
| CN104677295B (en) | Laser interference nonlinearity erron method of self compensation and device | |
| KR20020084437A (en) | Monitoring method and apparatus for wavelength division multiplexed optical signal | |
| KR102254289B1 (en) | Method for automatically controlling sweeping linearization of wavelength swept laser, and an apparatus performing the same | |
| JP7089184B2 (en) | Optical deflector parameter measuring device, method and program | |
| RU2453890C1 (en) | Method of automatic control in nonlinear system and servo system to this end |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |