阅读说明：本技术 一种激光波长测量装置及方法 (Laser wavelength measuring device and method ) 是由 崔建军 张鹏 陈恺 康岩辉 于 2021-08-10 设计创作，主要内容包括：本发明公开一种激光波长测量装置及方法包括:标准激光源、被测激光源、谐振平面镜、角锥反射镜、精密位移台、控制系统、解调系统、第一光电探测器、第二光电探测器；标准激光与被测激光平行送入到Fabry-Perot腔内进行干涉,形成主副测量干涉光束,然后分别被两个光电探测器接收形成主副测量干涉信号,解调模块按照光学游标原理对其进行解调得到光学游标长度,再通过光学游标长度、标准激光波长与被测激光波长的关系,即可计算得到被测激光波长。本发明结构简单,操作方便,能能够实现大范围高精度的波长测量。(The invention discloses a laser wavelength measuring device and a laser wavelength measuring method, wherein the laser wavelength measuring device comprises a standard laser source, a laser source to be measured, a resonant plane mirror, a pyramid reflecting mirror, a precise displacement table, a control system, a demodulation system, a first photoelectric detector and a second photoelectric detector; the standard laser and the laser to be measured are parallelly sent into a Fabry-Perot cavity to be interfered to form main and auxiliary measuring interference light beams, then the main and auxiliary measuring interference light beams are respectively received by two photoelectric detectors to form main and auxiliary measuring interference signals, the demodulation module demodulates the main and auxiliary measuring interference signals according to an optical vernier principle to obtain the length of an optical vernier, and then the laser wavelength to be measured can be calculated through the relationship among the length of the optical vernier, the standard laser wavelength and the laser wavelength to be measured. The invention has simple structure and convenient operation, and can realize large-range high-precision wavelength measurement.)

1. A laser wavelength measuring device is characterized in that: the device comprises a standard laser source, a laser source to be detected, a resonant plane mirror, a pyramid reflector, a precise displacement table, a control system, a demodulation system, a first photoelectric detector and a second photoelectric detector; the standard laser source emits laser with determined wavelength, the laser is emitted into a Fabry-Perot cavity formed by a resonant plane mirror and a pyramid reflecting mirror fixed on a precise displacement table to perform interference to form a main measurement interference light beam, and then the main measurement interference light beam is received by a first photoelectric detector to form a main measurement interference signal; the laser source to be measured emits laser with unknown wavelength, the laser is emitted into the Fabry-Perot cavity to perform interference to form a secondary measurement interference light beam, and then the secondary measurement interference light beam is received by the second photoelectric detector to form a secondary measurement interference signal; the main and auxiliary measuring interference signals are sent to a demodulation system for demodulation; the demodulation module demodulates the optical vernier according to the optical vernier principle to obtain the length of the optical vernier, and then calculates to obtain the wavelength of the laser to be measured according to the relationship between the length of the optical vernier, the standard laser wavelength and the wavelength of the laser to be measured; the control system is communicated with the demodulation system and the precision displacement table.

2. The laser wavelength measurement device according to claim 1, wherein the resonant mirror is a mirror having a first reflectivity at two ends and a second reflectivity in the middle, the first reflectivity is 2.5% to 97.6%, and the second reflectivity is 2.5% to 97.6%.

3. The laser wavelength measuring device according to claim 1, wherein the demodulation module obtains the length of the optical vernier by detecting the positions of the interference peak points where the primary and secondary measurement interference signals simultaneously arrive, and then performs the conversion to obtain the measured laser wavelength.

4. A laser wavelength measuring method is characterized by comprising the following steps:

step 1, emitting wavelength of a standard laser source to be lambda₀Laser of wavelength lambda emitted by the laser source to be measured₁Unknown laser is emitted into a Fabry-Perot cavity formed by a resonant plane mirror and a pyramid reflecting mirror fixed on a precise displacement table to perform interference to form primary and secondary measurement interference beams, and the primary and secondary measurement interference beams are received by a first photoelectric detector and a second photoelectric detector respectively to form primary and secondary measurement interference signals.

Step 2, the control system controls the precise displacement table to move so that the pyramid reflecting mirror moves; the main and auxiliary measuring interference signals are sent to a demodulation system for demodulation, when the main and auxiliary measuring interference signals reach an interference peak point for the first time, the position l of the precision displacement table at the moment is recorded₀Then continuing to demodulate, and recording the position l of the precision displacement table when the primary and secondary measurement signals reach the interference peak point for the second time₁The optical vernier length is L_y＝l₁-l₀。

Step 3, finally, according to the measured laser wavelength lambda₁And optical vernier length L_yThe laser wavelength to be measured is obtained as follows:

the measured laser wavelength lambda is obtained₁。

5. The laser wavelength measurement method according to claim 4, wherein the resonant mirrors are mirrors having a first reflectivity at both ends and a second reflectivity in the middle, the first reflectivity is 2.5% to 97.6%, and the second reflectivity is 2.5% to 97.6%.

6. The laser wavelength measurement method according to claim 4, wherein in step 2, when the primary and secondary measurement interference signals are simultaneously fed into the demodulation system, the demodulation system performs demodulation judgment on the primary and secondary measurement interference signals to judge whether the primary and secondary measurement interference signals simultaneously reach the interference peak point; if the main and auxiliary measuring interference signals do not reach the interference peak point at the same time, the demodulation system sends a signal that the main and auxiliary measuring interference signals do not reach the interference peak point at the same time to the control system, after the control system receives the signal, the control system controls the precise displacement platform to move backwards, the pyramid reflector fixed on the precise displacement platform moves backwards, and meanwhile, the precise displacement platform feeds back the position of the pyramid reflector to the control system in real time.

7. The laser wavelength measurement method according to claim 6, wherein in step 2, when the demodulation system detects that the primary and secondary interference signals reach the interference peak point at the same time, the demodulation system sends the control system a signal indicating that the primary and secondary interference signals reach the interference peak point at the same time, and after receiving the signal, the control system records the position l of the cube-corner mirror fed back by the fine displacement stage at that time₀And marked as a first time zero position; meanwhile, the control system sends a command for demodulating the interference level through which the main and auxiliary measurement interference signals pass to the demodulation system, and the demodulation system records the change of the interference level of the main and auxiliary measurement interference signals from this moment; the control system continues to control the precise displacement platform to move backwards, simultaneously the main and auxiliary measurement interference signals are sent to the demodulation system for demodulation and judgment, and when the demodulation system detects that the main and auxiliary measurement interference signals simultaneously reach the interference peak point again, the demodulation system sends the main and auxiliary measurement interference signals to the control system and simultaneously reaches the interference peak point and the main and auxiliary measurement interference signalsInterference order M of each passing interference signal₀、M₁After the control system receives the signal, the position l of the pyramid reflector fed back by the precision displacement table is recorded₁And marked as the second zero point position, the detected optical vernier length is L_y＝l₀-l₁。

8. The laser wavelength measurement method according to claim 7, wherein in step 3, when the control system finds that the second zero point position occurs, it is determined according to the measured laser wavelength λ₁And optical vernier length L_yWavelength of standard laser λ₀The relation of (a) is calculated according to the following formula to obtain the wavelength value of the laser to be measured:

1) when M is₀Greater than M₁：

2) When M is₀Less than M₁：

This completes the wavelength measurement.

Technical Field

The invention belongs to a laser wavelength measuring device and a laser wavelength measuring method, and particularly relates to a laser wavelength measuring device and a laser wavelength measuring method based on optical vernier Fabry-Perot interferometry.

Background

Laser wavelength is a very important parameter of a laser, and the accurate measurement of the laser wavelength plays an important role in the fields of laser spectrum research and precision measurement as well as in the frequency stabilization technology of semiconductor lasers and the demodulation technology of fiber bragg grating measurement signals.

The existing laser wavelength measurement method is mainlyThere are two main categories: spectral and coherent. The spectral laser wavelength measuring method adopts modes such as grating or optical filter and the like to measure the laser wavelength, and the precision is relatively low. The coherent laser wavelength measuring method adopts interference technology to measure laser wavelength, and is mainly based on three interference technologies at present: fizeau (Fizeau) interference techniques, Fabry-Perot (Fabry-Perot) interference techniques, and Michelson (Michelson) interference techniques. The highest precision of the Fizeau interference type laser wavelength measurement technology can reach 10^-7Magnitude. The accuracy of Fabry-Perot interference technique can reach 10^-8The Michelson wavemeter calculates the wavelength of the light to be measured by calculating the ratio of the number of interference fringes of the reference light and the light to be measured, and the method can also reach 10^-7～10^-8But the structure is complicated.

The method of beat frequency can also be used for measuring the laser wavelength, and the measurement precision is high, but the wavelength measurement range of the method is limited by the measurement range of a frequency meter, so the wavelength measurement range is small.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a laser wavelength measuring device and method, wherein two sets of Fabry-Perot interferometers are constructed to be mutually coordinated to form main and auxiliary measuring interference signals, the laser wavelength is demodulated and calculated through the optical vernier principle, and the 10-degree wide-range laser wavelength measuring device and method can be realized^-8Wavelength measurement of the above accuracy.

In order to achieve the purpose, the invention adopts the following technical scheme:

a laser wavelength measuring device comprises a standard laser source, a measured laser source, a resonant plane mirror, a pyramid reflector, a precise displacement table, a control system, a demodulation system, a first photoelectric detector and a second photoelectric detector; the standard laser source emits laser with determined wavelength, the laser is emitted into a Fabry-Perot cavity formed by a resonant plane mirror and a pyramid reflecting mirror fixed on a precise displacement table to perform interference to form a main measurement interference light beam, and then the main measurement interference light beam is received by a first photoelectric detector to form a main measurement interference signal; the laser source to be measured emits laser with unknown wavelength, the laser is emitted into the Fabry-Perot cavity to perform interference to form a secondary measurement interference light beam, and then the secondary measurement interference light beam is received by the second photoelectric detector to form a secondary measurement interference signal; the main and auxiliary measuring interference signals are sent to a demodulation system for demodulation; the demodulation module demodulates the optical vernier according to the optical vernier principle to obtain the length of the optical vernier, and then calculates to obtain the wavelength of the laser to be measured according to the relationship between the length of the optical vernier, the standard laser wavelength and the wavelength of the laser to be measured; the control system is communicated with the demodulation system and the precision displacement table.

Preferably, the resonant flat mirrors have first reflectivity at two ends and second reflectivity in the middle, the first reflectivity is 2.5-97.6%, and the second reflectivity is 2.5-97.6%.

Preferably, the demodulation module detects the positions of the main and auxiliary measurement interference signals reaching the interference peak point at the same time to obtain the length of the optical vernier, and then the length of the optical vernier is converted to obtain the wavelength of the laser to be measured.

The invention also provides a laser wavelength measuring method, which comprises the following steps:

step 1, emitting wavelength of a standard laser source to be lambda₀Laser of wavelength lambda emitted by the laser source to be measured₁Unknown laser is emitted into a Fabry-Perot cavity formed by a resonant plane mirror and a pyramid reflecting mirror fixed on a precise displacement table to perform interference to form primary and secondary measurement interference beams, and the primary and secondary measurement interference beams are received by a first photoelectric detector and a second photoelectric detector respectively to form primary and secondary measurement interference signals.

Step 2, the control system controls the precise displacement table to move so that the pyramid reflecting mirror moves; the main and auxiliary measuring interference signals are sent to a demodulation system for demodulation, when the main and auxiliary measuring interference signals reach an interference peak point for the first time, the position l of the precision displacement table at the moment is recorded₀Then continuing to demodulate, and recording the position l of the precision displacement table when the primary and secondary measurement signals reach the interference peak point for the second time₁The optical vernier length is L_y＝l₁-l₀。

Step 3, finally, according to the measured laser wavelength lambda₁And optical vernier length L_yTo obtain the laser to be measuredThe wavelength is as follows:

the measured laser wavelength lambda is obtained₁。

Preferably, the resonant flat mirrors have first reflectivity at two ends and second reflectivity in the middle, the first reflectivity is 2.5-97.6%, and the second reflectivity is 2.5-97.6%.

Preferably, in step 2, when the main and auxiliary measurement interference signals are simultaneously sent to the demodulation system, the demodulation system performs demodulation judgment on the main and auxiliary measurement interference signals, and judges whether the main and auxiliary measurement interference signals simultaneously reach an interference peak point; if the main and auxiliary measuring interference signals do not reach the interference peak point at the same time, the demodulation system sends a signal that the main and auxiliary measuring interference signals do not reach the interference peak point at the same time to the control system, after the control system receives the signal, the control system controls the precise displacement platform to move backwards, the pyramid reflector fixed on the precise displacement platform moves backwards, and meanwhile, the precise displacement platform feeds back the position of the pyramid reflector to the control system in real time.

Preferably, in step 2, when the demodulation system detects that the primary and secondary interference signals reach the interference peak point at the same time, the demodulation system sends the primary and secondary interference signals to the control system, and after receiving the signals, the control system records the position l of the pyramid reflector fed back by the precision displacement stage at that time₀And marked as a first time zero position; meanwhile, the control system sends a command for demodulating the interference level through which the main and auxiliary measurement interference signals pass to the demodulation system, and the demodulation system records the change of the interference level of the main and auxiliary measurement interference signals from this moment; the control system continues to control the precise displacement platform to move backwards, simultaneously the main and auxiliary measuring interference signals are sent to the demodulation system for demodulation and judgment, and when the demodulation system detects that the main and auxiliary measuring interference signals simultaneously reach the interference peak point again, the demodulation system sends the main and auxiliary measuring interference signals and the main and auxiliary measuring interference signals to the control systemRespectively passing interference order M₀、M₁After the control system receives the signal, the position l of the pyramid reflector fed back by the precision displacement table is recorded₁And marked as the second zero point position, the detected optical vernier length is L_y＝l₀-l₁。

Preferably, in step 3, when the control system finds that the second zero point position occurs, the control system determines the position according to the measured laser wavelength λ₁And optical vernier length L_yWavelength of standard laser λ₀The relation of (a) is calculated according to the following formula to obtain the wavelength value of the laser to be measured:

1) when M is₀Greater than M₁：

2) When M is₀Less than M₁：

This completes the wavelength measurement.

The invention has the beneficial effects that:

(1) the invention adopts the optical vernier principle to analyze the laser wavelength, and can realize 10^-8Wavelength measurement of accuracy.

(2) The invention realizes the structure of the double Fabry-Perot interferometer by utilizing the laser with space separation, and can realize laser wavelength measurement with large range and high precision.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a schematic diagram of the apparatus and method of the present invention;

fig. 2 is a schematic diagram of an optical vernier.

In the figure: 1. the device comprises a standard laser source, 2 a laser source to be detected, 3 a resonant plane mirror, 4 a pyramid reflector, 5 a precise displacement table, 6 a control system, 7 a demodulation system, 8 a first photoelectric detector, 9 a second photoelectric detector.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

The vernier effect was originally applied to improve the resolution of length measurement (e.g. vernier caliper), and its working principle lies in that the small scale difference between the main scale and the vernier is used to measure the length. The optical vernier principle is the application of vernier effect in optical interference, when two lasers with wavelength difference perform Fabry-Perot interference, two interference signals with small difference can be formed, and the interference signals have the same work as that of a main scale and a vernier of a vernier caliper.

Fabry-Perot interference is multi-beam interference, according to the formula of multi-beam interference:

wherein, I is the light intensity of transmitted light, a is the amplitude of incident light, R is the light intensity reflectivity of the Fabry-Perot cavity resonator mirror, d is the length of the Fabry-Perot cavity, and lambda is the wavelength of the incident light. The relationship between the separation Δ d of the folded Fabry-Perot cavity interference peaks and the interference wavelength λ can be expressed as:

if the two interference wavelengths are different, the peak intervals of the main and auxiliary measurement interference signals are different, for example, the two wavelengths are 632nm and 628nm, respectively, and the interference peak intervals are 158nm and 157nm, respectively. As shown in FIG. 2, I (Z) is the main measurement interference signal, and I (Y) is the auxiliary measurement interference signal, and the main and auxiliary measurement interference signals reach the interference peak point at the same time every certain distance. When the main and auxiliary measuring interference signals reach the peak point twice at the same time, the Fabry-Perot cavity changes by an optical vernier length L_yThe theoretical optical vernier length is: l_y＝24806nm。

As shown in fig. 1, the laser wavelength measuring device provided by the invention comprises a standard laser source 1, a laser source 2 to be measured, a resonant plane mirror 3, a pyramid reflecting mirror 4, a precise displacement table 5, a control system 6, a demodulation system 7, a first photoelectric detector 8 and a second photoelectric detector 9; the standard laser source 1 emits laser with determined wavelength, the laser is emitted into a Fabry-Perot cavity formed by a resonant flat mirror 3 and a pyramid reflecting mirror 4 fixed on a precise displacement table 5 to perform interference to form a main measurement interference light beam, and then the main measurement interference light beam is received by a first photoelectric detector 8 to form a main measurement interference signal. The laser source 1 to be measured emits laser with unknown wavelength, and the laser is emitted into the Fabry-Perot cavity to perform interference to form a secondary measurement interference light beam, and then the secondary measurement interference light beam is received by the second photoelectric detector 9 to form a secondary measurement interference signal. The main and auxiliary measuring interference signals are sent to a demodulation system 7 for demodulation. The control system 6 is communicated with the demodulation system 7 and the precision displacement table 5. The length of the optical vernier is obtained by detecting the position where the main and auxiliary measuring interference signals simultaneously reach the interference peak point, and then the measured laser wavelength is obtained by conversion.

Further, the resonant plane mirror is a plane mirror with first reflectivity at two ends and second reflectivity in the middle, the first reflectivity is 2.5% -97.6%, and the second reflectivity is 2.5% -97.6%.

The invention also provides a laser wavelength measuring method which is realized by adopting the laser wavelength measuring device and has the following implementation process:

the standard laser source 1 emits light with a wavelength λ₀Laser of wavelength lambda emitted by the laser source 2 to be measured₁Laser, the optical vernier length at this time is:

two beams of laser are parallelly emitted into a Fabry-Perot cavity formed by a resonant plane mirror 3 and a pyramid reflecting mirror 4 fixed on a precise displacement table 5 for interference and then are respectively received by two photodetectors to form a main measurement interference signal I₀Secondary measurement interference signal I₁。

Interference signal I of primary and secondary measurement₀、I₁Simultaneously, the signals are sent to a demodulation system 7, and the demodulation system 7 measures interference signals I of the main and the auxiliary signals₀、I₁Performing demodulation judgment to judge the interference signal I of the primary and secondary measurement₀、I₁Whether or not the interference peak points are reached at the same time.

If the primary and secondary measurement interfere with signal I₀、I₁If the interference peak point is not reached at the same time, the demodulation system 7 sends a main and auxiliary measurement interference signal I to the control system 6₀、I₁And after the control system 6 receives the signal, the precise displacement table 5 is controlled to move backwards, the pyramid reflecting mirror 4 fixed on the precise displacement table moves backwards, and meanwhile, the precise displacement table 5 feeds back the position of the pyramid reflecting mirror 4 to the control system 6 in real time.

While the pyramid reflector 4 moves, the primary and secondary measurement interference signals I₀、I₁Sending to a demodulation system 7 for demodulation judgment, and when the demodulation system 7 detects a main and auxiliary measurement interference signal I₀、I₁When reaching the interference peak point at the same time, the demodulation system 7 sends a main and auxiliary measurement interference signal I to the control system 6₀、I₁Meanwhile, the signal reaching the interference peak point is recorded by the control system 6 after the signal is received, and the position l of the pyramid reflector 4 fed back by the precision displacement stage 5 at the moment is recorded₀And marked as the first zero position. At the same time, the control system 6 sends a demodulation main and auxiliary measurement interference signal I to the demodulation system 7₀、I₁Command of the order of interference passed through, from which moment the demodulation system 7 records the main and auxiliary measuring interference signals I₀、I₁The change in the interference order.

The control system 6 continues to control the precision displacement table 5 to move backwards, and the main and auxiliary measurement interference signals I are simultaneously moved₀、I₁Sending to a demodulation system 7 for demodulation judgment, and when the demodulation system 7 detects the main and auxiliary measurement interference signals I again₀、I₁When reaching the interference peak point at the same time, the demodulation system 7 sends a main and auxiliary measurement interference signal I to the control system 6₀、I₁Signal reaching interference peak point simultaneously and main and auxiliary measuring interference signal I₀、I₁Respectively passing interference order M₀、M₁After the control system 6 receives the signal, the position l of the pyramid reflector 4 fed back by the precision displacement stage 5 is recorded₁And marked as the second zero point position, the detected optical vernier length is L_y＝l₀-l₁。

When the control system 6 finds the second zero position, it will measure the laser wavelength lambda₁And optical vernier length L_yWavelength of standard laser λ₀The relation of (a) is calculated according to the following formula to obtain the wavelength value of the laser to be measured:

1) when M is₀Greater than M₁：

2) When M is₀Less than M₁：

The measurement of the wavelength of the present invention is completed.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.