CN111929692B - Laser angle measuring device and method - Google Patents
Laser angle measuring device and method Download PDFInfo
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- CN111929692B CN111929692B CN202010776541.9A CN202010776541A CN111929692B CN 111929692 B CN111929692 B CN 111929692B CN 202010776541 A CN202010776541 A CN 202010776541A CN 111929692 B CN111929692 B CN 111929692B
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Abstract
The invention relates to the technical field of angle measurement, and provides a laser angle measuring device and method. The device comprises: the device comprises an optical interference module, a detection module, a phase feedback control module and a signal extraction module; the optical interference module divides incident laser into transmission laser and reflection laser, and the reflected reflection laser and the transmission laser are converged to obtain third laser; the detection module measures the light spot intensity and the spatial position information of the third laser; the phase feedback control module controls the optical interference module to change the phase difference between the transmitted laser and the reflected laser according to the light spot intensity; and the signal extraction module calculates the deflection angle of the incident laser according to the spatial position information of the third laser spot based on the weak value amplification principle. The invention enlarges the offset of the light spot at the detection end, thereby improving the measurement sensitivity, simultaneously relaxing the precision requirement on the detector and obtaining the high-precision detection performance by using the detector with low precision.
Description
Technical Field
The invention relates to the technical field of laser attitude measurement, in particular to a laser angle measurement device and method.
Background
The concept of weak measurement and weak value was proposed by y.aharonov, d.z.albert and l.vaidman in 1988, which originally only led to a theoretical discussion, whereas in the last 10 years, due to the constant emergence of various weak measurement verification experiments, weak measurement techniques gained more extensive attention. At present, the research of weak measurement technology is mainly divided into two aspects: the method is used for direct measurement of quantum state wave functions and characterization of quantum mechanical non-classical characteristics in the field of quantum foundation research; the other is used in the field of precision measurement, namely weak value amplification measurement technology. The weak value amplification measurement technology can convert unknown physical quantities such as tiny displacement and deflection angle into larger displacement and deflection angle, and then carries out measurement, meanwhile, the influence of technical noise, detector saturation and other factors on measurement in a real environment can be relieved, and even if large loss is caused to a signal in an amplification process, the overall sensitivity and precision of a detection system can be improved in a plurality of practical applications.
The first experimental verification of the weak value amplification measurement technology was already done in 1991 by ritchae et al, which uses the front and back selection of polarization states to achieve amplification of beam deflection, and this experiment also achieves the measurement of weak values for the first time, but only limited to the experimental conditions and configuration at that time, they achieve 20 times amplification effect, and thus do not fully embody the application value of the weak value amplification measurement technology. The true turn is the measurement of the optical spin quantum hall effect in 2008, which is accomplished by Hosten and kwat with weak value amplification. The experiment measures the transverse deviation of light beams caused by the optical spin Hall effect based on a weak value amplification technology, the detection sensitivity reaches 0.1nm due to the adoption of the experiment configuration of an imaginary weak value, the 10000-fold amplification effect is realized, and any noise suppression measures such as vacuum, vibration isolation and the like are not used in the whole measurement process. The series of excellent characteristics arouse strong interest, and people apply weak value amplification measurement technology to the observation of various physical quantities urgently, and the subsequent experiments successively realize the amplification measurement of beam deflection, angle rotation, charge induction, frequency shift, time delay, phase change, speed change and temperature drift.
A great deal of research has been carried out on weak value amplification measurement of a deflection angle so far, and the main idea is to use a path superposition state in an interferometer as a system state, use the transverse momentum of a light beam as a probe state, select a dark end of an interferometer outlet as a selected state after orthogonality, and when the phase difference of two arms of the interferometer is adjusted to deviate from the dark end state with complete interference cancellation, the imaginary weak value enables the deflection of the light beam to be reflected on the transverse displacement of a final interference light spot, so that the amplification measurement of the deflection angle is finally realized.
However, the conventional relevant deflection angle measurement schemes measure the deflection angle of the internal mirror of the interferometer, and for applications such as laser attitude measurement, the conventional measurement schemes cannot amplify the deflection angle, but reduce the measurement sensitivity of a detection system to the deflection angle.
Disclosure of Invention
The embodiment of the invention provides a laser angle measuring device and method.
A first aspect of an embodiment of the present invention provides a laser angle measuring apparatus, including: the device comprises an optical interference module, a detection module, a phase feedback control module and a signal extraction module;
the optical interference module is used for dividing incident laser into transmission laser and reflection laser, reflecting the reflection laser, and converging the reflected reflection laser and the transmission laser after reflection to obtain third laser;
the detection module is used for measuring the light spot intensity and the spatial position information of the third laser;
the phase feedback control module is used for controlling the optical interference module to change the phase difference between the transmitted laser and the reflected laser according to the spot intensity, so that the third laser is in a destructive interference state at the emergent end of the optical interference module;
the signal extraction module is used for calculating the deflection angle of the incident laser according to the spatial position information based on a weak value amplification principle.
Further, the optical interference module includes: the device comprises a first beam splitter, a reflector and a second beam splitter;
the first beam splitter is used for splitting incident laser into transmission laser and reflection laser;
the reflecting mirror is arranged on a first position of the first beam splitter and used for reflecting the reflected laser to the second beam splitter;
and the second beam splitter is arranged at a second position of the first beam splitter and is used for converging the reflected laser and the transmitted laser after reflection to obtain third laser.
Further, the optical interference module further includes: at least one of a polarization filtering device, a beam collecting lens, and a beam shaping device disposed between the first beam splitter and a laser that emits the incident laser light.
Further, the reflection coefficient of the second beam splitter satisfies:
(1-R 1 )R 2 R 3 ＝R 1 (1-R 3 )
wherein R is 1 Is the reflection coefficient, R, of the first beam splitter 2 Is the reflection coefficient of the mirror, R 3 Is the reflection coefficient of the second beam splitter.
Further, the detection module is a four-quadrant detector or a CCD camera.
Further, the phase feedback control module comprises: a feedback controller and a shifter;
the feedback controller is connected with the detection module and used for controlling the shifter to change the position of the reflector according to the light spot intensity;
and the shifter is arranged on the reflector and used for controlling the position of the reflector so that the reflector changes the phase difference of the transmission laser and the reflection laser.
Further, the laser angle measuring device further comprises: a phase-locked amplifier;
and the phase-locked amplifier is connected with the shifter at a first end and connected with the detection module at a second end, and is used for denoising the third laser signal with the preset frequency when the position of the shifter and the third laser signal are modulated with the preset frequency.
Further, the spatial position information includes: a lateral spatial displacement of the third laser;
the signal extraction module is specifically configured to:
and reading the transverse spatial displacement, and calculating the deflection angle of the incident laser according to the transverse spatial displacement based on a weak value amplification principle.
A second aspect of an embodiment of the present invention provides a laser angle measurement method, including:
dividing incident laser into transmission laser and reflection laser through an optical interference module, reflecting the reflection laser, and converging the reflected reflection laser and the transmission laser to obtain third laser;
measuring the spot intensity and the spatial position information of the third laser by a detection module;
controlling the optical interference module to change the phase difference of the transmitted laser and the reflected laser according to the spot intensity, so that the third laser is in a destructive interference state at the emergent end of the optical interference module;
and calculating the deflection angle of the incident laser according to the spatial position information based on a weak value amplification principle.
Further, the optical interference module includes: the device comprises a first beam splitter, a reflector and a second beam splitter;
the method for dividing incident laser into transmission laser and reflection laser through an optical interference module, reflecting the reflection laser, and converging the reflected reflection laser and the transmission laser to obtain third laser comprises the following steps:
dividing incident laser light into transmission laser light and reflection laser light by the first beam splitter;
reflecting the reflected laser light to the second beam splitter by the mirror disposed in a first orientation of the first beam splitter;
and converging the reflected laser and the transmitted laser after reflection to obtain third laser through the second beam splitter arranged on the second direction of the first beam splitter.
Compared with the prior art, the laser angle measuring device and method of the embodiment of the invention have the following beneficial effects:
the device mainly comprises an optical interference module, a detection module, a phase feedback control module and a signal extraction module, and has simple structure and high precision; the optical interference module interferes the incident laser and successfully applies the weak value amplification measurement technology to laser angle measurement; the detection module measures the spot intensity and the spatial position information of the third laser, the phase feedback control module controls the optical interference module to change the phase difference between the transmitted laser and the reflected laser according to the spot intensity, the signal extraction module calculates the deflection angle of the incident laser according to the spatial position information of the spot of the third laser based on the weak value amplification principle, the offset of the spot of the detection end is amplified, the precise measurement of the change of the laser deflection angle is realized, the precision requirement on the detector is relaxed, and the high-precision detection performance can be obtained by using the low-precision detector.
Drawings
FIG. 1 is a schematic diagram of a laser angle measuring device provided by an embodiment of the invention;
FIG. 2 is a schematic diagram of another laser angle measuring device provided in the embodiment of the present invention
Fig. 3 is a schematic flow chart of an implementation of the laser angle measurement method according to the embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details.
In order to illustrate the technical means of the present invention, the following description is given by way of specific examples.
Referring to fig. 1, a schematic diagram of the laser angle measuring device provided in this embodiment is shown, and the present invention is applicable to the technical field of laser attitude measurement, and has high precision and high flexibility. For convenience of explanation, only the portions related to the present embodiment are shown.
The laser angle measuring device of the embodiment mainly comprises: optical interference module 100, detection module 5, phase feedback control module 200 and signal extraction module 7. The incident end of the optical interference module 100 receives the incident laser of the laser, the exit end of the optical interference module 100 emits the laser to the detection end of the detection module 5, the output end of the detection module 5 is connected to both the receiving end of the phase feedback control module 200 and the receiving end of the signal extraction module 7, and the control end of the phase feedback control module 200 is connected to the controlled end of the optical interference module 100.
In the prior art, the deflection angle of the interferometer internal reflector 2 is measured by the deflection angle measuring scheme, while for applications such as laser attitude measurement, the deflection angle of an incident beam relative to the whole measuring device needs to be measured, and the conventional measuring scheme cannot amplify the deflection angle but reduces the measurement sensitivity of a detection system to the deflection angle. Therefore, the embodiment provides a Mach-Zender (Mach-zehnder) type interference optical path, improves a common weak value amplification angle measurement interference optical path, can directly measure the deflection angle of an incident beam, namely, the change of the deflection angle of the incident beam is reflected on the transverse displacement of an interference light spot instead of the deflection angle of a lens in an interferometer, and amplifies the offset of the light spot at a detection end compared with a direct laser angle measurement scheme, thereby improving the measurement sensitivity and being applied to the aspect of measuring various laser postures.
Specifically, the optical interference module 100 receives an incident laser emitted by a laser, divides the incident laser into two paths of a transmission laser and a reflection laser, reflects one path of the reflection laser, and merges the reflected laser and the transmission laser to obtain a third laser, i.e., divides the laser with an incident angle to be measured into two paths and then merges the two paths of the laser to be measured and then performs interference; the detection module 5 measures the spot intensity and the spatial position information of the third laser; the phase feedback control module 200 controls the optical interference module 100 to change the phase difference between the transmitted laser and the reflected laser according to the light spot intensity, so that the third laser is in a destructive interference state at the exit end of the optical interference module 100, that is, the phase difference of the two paths of interference light is feedback controlled according to the measured interference light spot intensity, so as to ensure that the detection end approaches the destructive interference state; the signal extraction module 7 calculates the deflection angle of the incident laser according to the spatial position information based on the weak value amplification principle. Optionally, the signal extraction module 7 may also determine the incident angle of the incident laser light based on the calculated deflection angle.
The laser angle measuring device has simple structure and high precision; the optical interference module 100 interferes the incident laser light; the detection module 5 detects the intensity and spatial position information of the interference light spot, that is, the change of the deflection angle of the incident light is reflected on the transverse displacement of the interference light spot, the phase feedback control module 200 controls the optical interference module 100 to change the phase difference between the transmitted laser and the reflected laser according to the intensity of the light spot, the signal extraction module 7 calculates the deflection angle of the incident laser according to the spatial position information based on the weak value amplification principle, and successfully applies the weak value amplification measurement technology to laser angle measurement, that is, the offset of the light spot at the detection end is amplified, thereby realizing the precise measurement of the change of the laser deflection angle, simultaneously relaxing the precision requirement on the detector, and obtaining the high-precision detection performance by using the low-precision detector.
In one embodiment, referring to FIG. 2, optical interference module 100 can comprise: a first beam splitter 1, a mirror 2 and a second beam splitter 3. One end of the incident beam of the first beam splitter 1 is an incident end of the optical interference module 100, one end of the emergent beam of the second beam splitter 3 is an emergent end of the optical interference module 100, and the controlled position of the reflector 2 is a controlled end of the optical interference module 100.
Wherein the mirror 2 is arranged in a first orientation of the first beam splitter 1 and the second beam splitter 3 is arranged in a second orientation of the first beam splitter 1. Illustratively, referring to fig. 2, the reflecting mirror 2 is disposed above or below the first beam splitter 1, and the second beam splitter 3 is disposed in the horizontal direction of the first beam splitter 1. Alternatively, the reflecting mirror 2 is provided on the left or right side of the first beam splitter 1, and the second beam splitter 3 is provided in the vertical direction of the first beam splitter 1, and so on. The present embodiment does not limit the specific positions of the reflecting mirror 2 and the second beam splitter 3, as long as the reflected laser light of the first beam splitter 1 is reflected to the second beam splitter 3 through the reflecting mirror 2, and the transmitted laser light can be emitted to the second beam splitter 3.
Specifically, the first beam splitter 1 splits incident laser light into transmission laser light and reflection laser light, and the transmission laser light is directly emitted to the second beam splitter 3; the reflecting mirror 2 reflects the reflected laser light to a second beam splitter 3; the second beam splitter 3 converges the reflected laser light and the transmitted laser light to obtain a third laser light, that is, the second beam splitter 3 combines and interferes the two paths of beams of the reflected laser light and the transmitted laser light, and the combined beam intensities of the two paths of the transmitted and reflected laser light are equal by selecting a proper reflection coefficient of the lens, so that destructive interference can be realized at the exit end of the optical interference module 100.
Optionally, the reflection coefficient of the second beam splitter 3 in this embodiment satisfies:
(1-R 1 )R 2 R 3 ＝R 1 (1-R 3 )
wherein R is 1 Is the reflection coefficient, R, of the first beam splitter 1 2 Is the reflection coefficient, R, of the mirror 2 3 Is the reflection coefficient of the second beam splitter 3. By properly selecting the reflection coefficient of the lens, complete interference cancellation can be realized after the reflected laser and the transmitted laser are combined.
In one embodiment, the optical interference module 100 of the present embodiment may further include: at least one of a polarization filtering device, a beam collection lens, and a beam shaping device. At least one of the polarization filter device, the beam collecting lens and the beam shaping device is arranged between the first beam splitter 1 and the laser for emitting the incident laser, so that the incident laser can be subjected to operations such as polarization filtering or shaping, and the interference contrast after final beam combination is improved.
Optionally, the detection module 5 of this embodiment is a four-quadrant detector or a CCD camera. The detection module 5 can record the spot intensity and the spatial position information of the interference spot (third laser) output by the optical interference module 100, and this embodiment is implemented by a four-quadrant detector or a CCD camera, both of which can accurately reflect the position offset of the interference spot.
In one embodiment, referring to fig. 2, the phase feedback control module 200 may include: a feedback controller 6 and a displacer 4.
The input end of the feedback controller 6 is connected with the output end of the detection module 5, the output end of the feedback controller 6 is connected with the input end of the shifter 4, and the control end of the shifter 4 is arranged on the reflector 2 of the optical interference module 100.
The feedback controller 6 can control the shifter 4 to change the position of the reflecting mirror 2 according to the light spot intensity; the shifter 4 controls the position of the reflector 2 to make the reflector 2 change the phase difference between the transmitted laser and the reflected laser, so that the light beam emitted from the second beam splitter 3 reaches the state of destructive interference. Namely, the feedback controller 6 is connected with the shifter 4 and the detection module 5, and the feedback controller 6 performs feedback control on the position of the reflector 2 according to the light intensity of interference light spots measured by the detector, so as to adjust the phase difference of the transmitted and reflected two light beams, finally ensure that the light beam at the emergent end of the optical interference module 100 is in an interference cancellation state, and can perform stable adjustment on the phase difference according to actual measurement requirements.
Alternatively, the displacement accuracy of the displacer 4 is more than the order of the wavelength of the light beam. The displacer 4 of the present embodiment may be a piezoelectric ceramic device, and displacement accuracy is sufficiently high.
In one embodiment, the laser goniometer device may further include: a lock-in amplifier. The first end of the phase-locked amplifier is connected with the shifter 4, and the second end of the phase-locked amplifier is connected with the detection module 5.
The lock-in amplifier is used for denoising the third laser signal with the preset frequency when the position of the shifter 4 and the third laser signal are modulated with the preset frequency. The lock-in amplifier can suppress ambient noise in the beam. Specifically, when the position of the shifter 4 is modulated at a certain frequency, the interference light spot signal (third laser) on the detector is also modulated at the same frequency, and the lock-in amplifier can distinguish the interference light spot signal at the certain frequency from the environmental noise at other frequencies, so as to finally remove the environmental noise and retain the required interference light spot signal.
Further, the spatial location information may include: the transverse spatial displacement of the third laser, namely the transverse spatial displacement of the interference light spot; correspondingly, the signal extraction module 7 is specifically configured to:
and reading the transverse spatial displacement, calculating the deflection angle change of the incident laser by utilizing an internal signal operation electronic device based on a weak value amplification principle, and outputting a calculation result to a display screen.
Further, referring to fig. 2, the structure of the laser angle measuring device provided in this embodiment will be described according to the working principle:
the physical system considered is a photon entering the measurement device, the initial quantum state | Ψ of which is the photon in this embodiment, as in conventional weak value amplification measurement schemes i (otherwise known as the pre-selection state) can be decomposed into a probe state | φ i >And system state | ψ i >Tensor product form of (a):
wherein the probe state | φ i >Is the lateral momentum state of a photon, can be expanded according to eigenstates as:
wherein k is x Is the lateral momentum of the photons and,
as a function of the transverse momentum eigenstates,
is a transverse momentum of k x Is used as an operator for photon generation. And system state | ψ i The initial state is a state of superposition of paths of the long and short arms (reflected laser and transmitted laser) of the optical interference module 100, and can be written as:
wherein L and S represent the path states of the long and short arms, respectively, and α represents the adjustable phase difference between the two arms, determined by the shifter 4 attached to the mirror 2.
When photons pass through the optical interference module 100, the probe state and the system state are defined by the following unitary operator
Coupling occurs:
wherein k is the variation of the transverse momentum of the light beam,
is a function of the path identifier operator and,
operator for the lateral position of the probe. For long and short path states
Has eigenvalues of +1 and-1, respectively, because it can be seen from fig. 2 that, when the incident beam is deflected to a certain extent, the long and short path beams interfere with each other at the interference point of the second beam splitter 3 andthe detection modules 5 are deflected to different directions, so that the path information of the light beam can be obtained from the deflection direction of the emergent light. It is further assumed here that the deflection angle in our embodiment is sufficiently small that an approximation in the above equation can be established.
Adjust the phase difference between two arms of length through the position of adjustment speculum 2 for the exit end of optical interference module 100 is close to the interference and cancels, and it should be noted here that the reflection coefficient who chooses suitable second beam splitter 3 and speculum 2 makes the light intensity of two arms of exit end equal, and the reflection coefficient of first beam splitter 1, second beam splitter 3 and speculum 2 needs to satisfy the relation promptly: (1-R) 1 )R 2 R 3 ＝R 1 (1-R 3 ). Under the above conditions, the post-selection state is:
the probe states selected after the passage are therefore:
normalizing the above probe states to obtain normalized probe states | Ψ' >:
wherein the weak value is:
according to the front and back selection states of the path
And
can deduceWeak value
This is a pure imaginary weak value. Finally, we can deduce the photon detection probability distribution on the detection module 5 as:
wherein
A light field operator being a positive frequency component, wherein
Is a transverse momentum k x The annihilation operator of photons. Assuming that the beam has a gaussian light field distribution, the beam radius is σ, and considering a to be small,
in case (2), the detection probability distribution is:
it follows that the centers of the interference spots that are finally detected will be shifted
Is much larger than the offset distance Dk/k of the direct laser goniometry scheme 0 Where D is the focal length of the front-end collecting lens, k 0 Is the photon wave vector.
Illustratively, the basic workflow of the apparatus of the present embodiment is explained with reference to fig. 2: the device is mainly divided into two parts: calibration and deflection angle measurement.
A calibration part: firstly, a beam of reference light for calibration is additionally introduced into the incident end of the optical interference module 100, the incident angle of the reference light is adjusted to make the beams of the two arms of the optical interference module 100 coincide at the second beam splitter 3, and then the position of the initial light spot is calibrated on the detection module 5. Then, the phase feedback control module 200 adjusts the position of the mirror 2 by using the shifter 4 according to the intensity of the interference light spot measured by the detection module 5, so as to adjust the phase difference between the two arms of the optical interference module 100 until the point of complete destructive interference is found as the initial position of the mirror 2 and the initial position of the phase. Therefore, the calibration of the whole system is completed, and then the actual measurement of the deflection angle is carried out.
Deflection angle measurement section: and selecting a proper two-arm phase difference according to the required detection precision, adjusting the position of the reflector 2 according to the selected two-arm phase difference, and stabilizing the two-arm phase difference of the optical interference module 100 by using the feedback controller 6. Then, the relative deflection angle of the incident beam is calculated according to the transverse space displacement of the interference light spot relative to the initial position, which is measured by the detection module 5, and the measured deflection angle has high precision and high sensitivity.
In the above embodiment, the laser angle measuring device includes the optical interference module 100, the detection module 5, the phase feedback control module 200, and the signal extraction module 7, and has a simple structure and high sensitivity; through the angle measuring structure, the weak value amplification measuring technology is successfully applied to laser angle measurement, the change of a laser deflection angle is precisely measured, the detection sensitivity of the system is improved, meanwhile, the requirement on the performance of a detector is reduced, the resistance of the detection system to environmental noise is also improved, and the laser angle measuring structure is favorably applied to the field of laser attitude measurement.
The present embodiment provides a laser angle measuring method corresponding to the laser angle measuring apparatus described in the above embodiments. Fig. 3 is a schematic flow chart of an embodiment of the laser angle measuring method in this embodiment. The details are as follows:
step S301, dividing incident laser into transmission laser and reflection laser through an optical interference module, reflecting the reflection laser, and converging the reflected reflection laser and the transmission laser to obtain third laser.
And S302, measuring the spot intensity and the spatial position information of the third laser through a detection module.
Step S303, controlling the optical interference module to change a phase difference between the transmitted laser and the reflected laser according to the light spot intensity, so that the third laser is in a destructive interference state at the exit end of the optical interference module.
And step S304, based on the weak value amplification principle, calculating a deflection angle of the incident laser according to the transverse spatial displacement, and determining the incident angle of the incident laser according to the deflection angle.
Optionally, the optical interference module includes: the device comprises a first beam splitter, a reflector and a second beam splitter. Further, the specific implementation flow of step S301 includes:
dividing incident laser light into transmission laser light and reflection laser light by the first beam splitter; reflecting the reflected laser light to the second beam splitter by the mirror disposed in a first orientation of the first beam splitter; and converging the reflected laser and the transmitted laser after reflection by the second beam splitter arranged on the second direction of the first beam splitter to obtain third laser.
Optionally, the reflection coefficient of the second beam splitter satisfies:
(1-R 1 )R 2 R 3 ＝R 1 (1-R 3 )
wherein R is 1 Is the reflection coefficient, R, of the first beam splitter 2 Is the reflection coefficient of the mirror, R 3 Is the reflection coefficient of the second beam splitter.
Further, the phase feedback control module comprises: a feedback controller and a shifter; the specific process of step 203 includes:
the feedback controller controls the shifter to change the position of the reflecting mirror according to the intensity of the light spot; the shifter controls the position of the reflecting mirror, so that the reflecting mirror changes the phase difference of the transmitted laser and the reflected laser.
Further, the spatial position information includes: the step S304 of the lateral spatial displacement of the third laser includes: and calculating the deflection angle of the incident laser according to the transverse spatial displacement based on a weak value amplification principle.
According to the laser angle measurement method, the interference is carried out on incident laser, and the weak value amplification measurement technology is successfully applied to the laser angle measurement; and then measuring the spot intensity and the spatial position information of the third laser, controlling the optical interference module to change the phase difference between the transmitted laser and the reflected laser according to the spot intensity, calculating the deflection angle of the incident laser according to the spatial position information based on the weak value amplification principle, amplifying the offset of the spot at the detection end, realizing the precise measurement of the change of the laser deflection angle, simultaneously relaxing the precision requirement on the detector, and obtaining the high-precision detection performance by using the low-precision detector.
It should be understood by those skilled in the art that the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein.
Claims (9)
1. A laser goniometer device, characterized by comprising: the device comprises an optical interference module, a detection module, a phase feedback control module and a signal extraction module;
the optical interference module is used for dividing incident laser into transmission laser and reflection laser, reflecting the reflection laser, and converging the reflected reflection laser and the transmission laser to obtain third laser;
the detection module is used for measuring the spot intensity and the spatial position information of the third laser, wherein the spatial position information comprises the transverse spatial displacement of the third laser;
the phase feedback control module is used for controlling the optical interference module to change the phase difference between the transmitted laser and the reflected laser according to the light spot intensity, so that the third laser is in a destructive interference state at the emergent end of the optical interference module;
and the signal extraction module is used for reading the transverse spatial displacement and calculating the deflection angle of the incident laser according to the transverse spatial displacement based on a weak value amplification principle.
2. The laser goniometer device according to claim 1, characterized in that the optical interference module comprises: the device comprises a first beam splitter, a reflector and a second beam splitter;
the first beam splitter is used for splitting incident laser into transmission laser and reflection laser;
the reflecting mirror is arranged at a first position of the first beam splitter and used for reflecting the reflected laser to the second beam splitter;
and the second beam splitter is arranged at a second position of the first beam splitter and is used for converging the reflected laser and the transmitted laser after reflection to obtain a third laser.
3. The laser goniometer device of claim 2, wherein the optical interference module further comprises: at least one of a polarization filtering device, a beam collecting lens, and a beam shaping device disposed between the first beam splitter and a laser that emits the incident laser light.
4. The laser angle measuring device according to claim 2, wherein the reflection coefficient of the second beam splitter satisfies:
(1-R 1 )R 2 R 3 ＝R 1 (1-R 3 )
wherein the content of the first and second substances,R 1 is the reflection coefficient, R, of the first beam splitter 2 Is the reflection coefficient of the mirror, R 3 Is the reflection coefficient of the second beam splitter.
5. The laser goniometer device of claim 1, where the detection module is a four quadrant detector or a CCD camera.
6. The laser goniometer of claim 2, where the phase feedback control module comprises: a feedback controller and a shifter;
the feedback controller is connected with the detection module and used for controlling the shifter to change the position of the reflector according to the light spot intensity;
and the shifter is arranged on the reflector and used for controlling the position of the reflector so that the reflector changes the phase difference of the transmission laser and the reflection laser.
7. The laser goniometer device of claim 6, characterized in that the laser goniometer device further comprises: a phase-locked amplifier;
and the phase-locked amplifier is connected with the shifter at a first end and the detection module at a second end, and is used for denoising the third laser signal with the preset frequency when the position of the shifter and the third laser signal are modulated with the preset frequency.
8. A laser goniometry method, comprising:
dividing incident laser into transmission laser and reflection laser through an optical interference module, reflecting the reflection laser, and converging the reflected reflection laser and the transmission laser to obtain third laser;
measuring, by a detection module, spot intensity and spatial position information of the third laser, wherein the spatial position information includes a lateral spatial displacement of the third laser;
controlling the optical interference module to change the phase difference of the transmitted laser and the reflected laser according to the spot intensity, so that the third laser is in a destructive interference state at the emergent end of the optical interference module;
and reading the transverse spatial displacement, and calculating the deflection angle of the incident laser according to the transverse spatial displacement based on a weak value amplification principle.
9. The laser goniometry method of claim 8, wherein the optical interference module comprises: the device comprises a first beam splitter, a reflector and a second beam splitter;
the method for dividing incident laser into transmission laser and reflection laser through an optical interference module, reflecting the reflection laser, and converging the reflected reflection laser and the transmission laser to obtain third laser comprises the following steps:
dividing incident laser light into transmission laser light and reflection laser light by the first beam splitter;
reflecting the reflected laser light to the second beam splitter by the mirror disposed in a first orientation of the first beam splitter;
and converging the reflected laser and the transmitted laser after reflection to obtain third laser through the second beam splitter arranged on the second direction of the first beam splitter.
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