CN111258081A - Optical system installation and adjustment method and device based on optical fiber interconnection - Google Patents
Optical system installation and adjustment method and device based on optical fiber interconnection Download PDFInfo
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Abstract
The application discloses an optical system installation and adjustment method and device based on optical fiber interconnection, comprising the following steps: the light beam emitted by the laser is divided into N paths of light beams with equal energy through the first optical fiber coupler; wherein N is the number of separator apertures; transmitting the light with 90% of energy split from each path of light beam to the N separated small-caliber parallel light tubes through each second optical fiber coupler, and transmitting the rest light to the fringe tracker; according to the fringe tracking result, the root mean square of the emergent wave front of the control system is reduced to be within 0.05 wavelength; moving the separated small-caliber collimator to cover the whole aperture frequency domain surface and reconstruct an airspace; the direction of the separated small-caliber collimator is changed, and different view fields of the telescope to be detected are detected. The separated small-caliber parallel light tube and the optical fiber interconnection are used, so that the coherence of wave front synthesis can be ensured, the wave front is close to the sampling of the whole ideal wave front, the adjustment of the optical system is realized at lower cost, and the dependence on the large-caliber parallel light tube is reduced.
Description
Technical Field
The invention relates to the technical field of optics, in particular to an optical system adjusting method and device based on optical fiber interconnection.
Background
In order to obtain higher spatial resolution and limit detection capability and realize deeper and more detailed exploration of the universe, the calibers of telescopes used for astronomical observation and spatial situation perception are increasingly larger, the future ground-based telescope is in the magnitude of 30-40 meters, and the calibers of the spatial telescope are also developed from the six meters to the ten meters. The construction of these large-caliber telescopes not only expands the human understanding range of universe to the initial dark period of universe, namely realizes the observation of 'first light', but also combines the large caliber with the adaptive optics, so that the universe structure observed by the telescope is more precise, and the large-caliber telescopes have very important significance for realizing important astronomy problems such as black holes, dark matter, dark energy, geosynchronous planets and the like. Besides astronomy application, the large-caliber telescope can play an irreplaceable role in occupying space and detecting the threat of asteroid to human problems.
The telescope is in whole installation and debugging and the whole wave front quality testing's of system in-process, all need detect its wave front, generally divide into two technical genres: namely, the plane mirror autocollimator and the collimator emit plane wave front. Because the next generation of large-aperture telescopes need more alignment components and scientific terminals, the use of plane mirror auto-collimation in the light path without intermediate image surface can not be realized, and moreover, because the auto-collimation method light rays are transmitted twice in the system, the dynamic range of detection can be reduced, and the nonlinear degree of maladjustment state detection can be increased; therefore, the collimator is the best choice for the whole system detection of the large-aperture telescope.
However, as the aperture of the telescope increases, it becomes more difficult to construct a large aperture collimator to match the aperture. At present, the caliber of a collimator with a large caliber is generally 400-500 mm, and the caliber of a collimator with a larger caliber is rapidly increased along with the increase of the caliber in terms of cost and technical risk.
Therefore, how to perform the whole wavefront quality detection on the large-aperture telescope and adjust the whole wavefront quality to a required state is a technical problem to be solved urgently by those skilled in the art.
Disclosure of Invention
In view of the above, the present invention provides an optical system adjusting method and device based on optical fiber interconnection, which can make the wavefront close to the whole ideal wavefront for sampling, achieve the adjustment of the optical system at a lower cost, and reduce the dependence on the large-aperture collimator. The specific scheme is as follows:
an optical system installation and adjustment method based on optical fiber interconnection comprises the following steps:
the light beam emitted by the laser is divided into N paths of light beams with equal energy through the first optical fiber coupler; wherein N is the number of separator apertures;
transmitting each divided light beam to each second optical fiber coupler;
transmitting the light with 90% of energy split from each path of light beam to N split small-caliber parallel light tubes arranged in front of the telescope to be detected through each second optical fiber coupler, and transmitting the light with 10% of energy split to a stripe tracker for stripe tracking;
according to the fringe tracking result, the root mean square of the emergent wave front of the control system is reduced to be within 0.05 wavelength;
moving each separated small-caliber collimator, covering the whole aperture frequency domain surface, and reconstructing a space domain;
and respectively changing the direction of each separated small-caliber collimator, detecting different view fields of the telescope to be detected, and controlling the emergent wavefront comprehensive wave aberration value to be adjusted to be within 0.1 wavelength.
Preferably, in the method for adjusting an optical system based on optical fiber interconnection provided by the embodiment of the present invention, all light beams are transmitted in the polarization maintaining optical fiber.
Preferably, in the method for adjusting an optical system based on optical fiber interconnection provided in an embodiment of the present invention, the detecting different fields of view of the telescope to be detected includes:
establishing a sensitivity matrix;
performing singular value decomposition on the established sensitivity matrix, and establishing a Zemax model;
moving a certain optical element of the telescope to be detected by a set amount by using the matlab;
and extracting corresponding emergent wavefront comprehensive wave aberration values through the established Zemax model under different fields of view of the telescope to be detected.
Preferably, in the method for adjusting an optical system based on optical fiber interconnection provided in an embodiment of the present invention, the transmitting each divided optical beam to each second optical fiber coupler includes:
and transmitting each divided light beam to each second optical fiber coupler through the optical fiber delayer respectively.
Preferably, in the method for adjusting an optical system based on optical fiber interconnection provided by the embodiment of the present invention, the performing fringe tracking includes:
detecting by the fringe tracker to obtain an interference fringe image;
and sampling four points of the obtained interference fringe image, and calculating the phase delay of the system to obtain a fringe tracking result.
Preferably, in the method for adjusting an optical system based on optical fiber interconnection provided in an embodiment of the present invention, the controlling the root mean square of the wavefront exiting from the system to be reduced to within 0.05 wavelengths according to the fringe tracking result includes:
according to the fringe tracking result, the optical path difference between the N paths of light beams with equal energy is adjusted by driving the optical fiber delayer, and the root mean square of the emergent wave front of the control system is reduced to be within 0.05 wavelength.
Preferably, in the method for adjusting an optical system based on optical fiber interconnection provided in an embodiment of the present invention, the method further includes:
and determining the arrangement mode of the separated small-caliber parallel light tubes by modulating a transfer function.
Preferably, in the method for adjusting an optical system based on optical fiber interconnection provided in an embodiment of the present invention, the method further includes:
establishing a BP neural network;
inputting the interference fringe image obtained by the fringe tracker to the BP neural network;
and optimizing the weight value and the scale factor of the BP neural network, the translation factor, the weight value and the threshold value between nodes by utilizing error back propagation and combining a genetic algorithm, so that the secondary error between the output of the BP neural network and the phase delay of the system is minimum.
The embodiment of the invention also provides an optical system adjusting device based on optical fiber interconnection, which comprises: the device comprises a laser, a first optical fiber coupler, N second optical fiber couplers, N separated small-caliber parallel light tubes arranged in front of a telescope to be detected, a stripe tracker and a controller; wherein N is the number of separator apertures;
the laser is used for emitting a light beam;
the first optical fiber coupler is used for dividing the light beam emitted by the laser into N paths with equal energy and transmitting each divided light beam to each second optical fiber coupler;
the second optical fiber coupler is used for transmitting the light with 90% of energy split from each light beam to the split small-caliber parallel light pipe and transmitting the light with 10% of energy split from each light beam to the fringe tracker;
the stripe tracker is used for carrying out stripe tracking;
the controller is used for controlling the root mean square of the emergent wave front of the system to be reduced to be within 0.05 wavelength according to the fringe tracking result; the device is also used for moving each separated small-caliber collimator, covering the whole aperture frequency domain surface, reconstructing a space domain, changing the direction of each separated small-caliber collimator respectively, detecting different fields of view of the telescope to be detected and controlling the emergent wavefront comprehensive wave aberration value to be adjusted to be within 0.1 wavelength.
Preferably, in the optical fiber interconnection-based optical system adjusting apparatus provided in an embodiment of the present invention, the apparatus further includes: n fiber delays respectively located between the first fiber coupler and the second fiber coupler;
and the optical fiber delayer is used for adjusting the optical path difference between the N paths of light beams with equal energy.
According to the technical scheme, the optical system adjusting method and device based on optical fiber interconnection provided by the invention comprise the following steps: the light beam emitted by the laser is divided into N paths of light beams with equal energy through the first optical fiber coupler; wherein N is the number of separator apertures; transmitting each divided light beam to each second optical fiber coupler; transmitting the light with 90% of energy split from each path of light beam to N split small-caliber parallel light tubes arranged in front of the telescope to be detected through each second optical fiber coupler, and transmitting the light with 10% of energy split to a stripe tracker for stripe tracking; according to the fringe tracking result, the root mean square of the emergent wave front of the control system is reduced to be within 0.05 wavelength; moving each separated small-caliber collimator, covering the whole aperture frequency domain surface, and reconstructing a space domain; the direction of each separated small-caliber collimator is changed respectively, different fields of view of the telescope to be detected are detected, and the emergent wave front comprehensive wave aberration value is controlled to be adjusted to be within 0.1 wavelength.
The invention uses the separated small-caliber collimator to form an optical comprehensive caliber system, uses the optical fiber interconnection to ensure the coherence of wavefront synthesis, leads the wavefront to be close to the sampling of an integral ideal wavefront, and ensures that the PV value of the emergent wavefront synthesis wave is superior to 0.1 lambda (lambda is the working wavelength) and the RMS value is superior to 0.05 lambda, thus the separated small-caliber collimator is used to realize the function of the large-caliber collimator, the detection and adjustment of the optical system of the large-caliber telescope can be realized with lower cost, the dependence on the large-caliber collimator is reduced, and the separated small-caliber collimator is less influenced by the atmosphere, the imaging quality can be improved, and after the image is formed on the target surface of the telescope to be detected, the imaging quality is improved by using the image recovery function.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a flowchart of an optical system installation and adjustment method based on optical fiber interconnection according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of a process in which each of the split small-aperture parallel light pipes covers the entire aperture frequency domain surface and reconstructs a spatial domain according to the embodiment of the present invention;
fig. 3 is a schematic structural diagram of an optical system adjusting device based on optical fiber interconnection according to an embodiment of the present invention.
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.
The invention provides an optical system installation and adjustment method based on optical fiber interconnection, which comprises the following steps as shown in figure 1:
s101, dividing a light beam emitted by a laser into N paths of light beams with equal energy through a first optical fiber coupler; wherein N is the number of separator apertures;
s102, transmitting each divided light beam to each second optical fiber coupler;
s103, transmitting the light with 90% of energy split from each light beam to N split small-caliber parallel light tubes arranged in front of the telescope to be detected through each second optical fiber coupler, and transmitting the light with 10% of energy split to a stripe tracker for stripe tracking;
in practical applications, the current research on discrete aperture detection equipment mostly focuses on detecting the parallelism of multiple optical axes by using mechanical reference and geometric optics, and the research on the detection of wavelength precision (such as one tenth of the operating wavelength) is not further advanced. A coherent system constructed by a traditional optical element is most typically an optical integrated aperture system (OPA), also called a partially filled aperture system (partially filled aperture), and mainly comprises two basic forms of a Michelson type and a Fizeau type; the optical synthetic aperture array only partially fills the ideal mirror surface of the imaging system in any form. The invention uses the discrete small-caliber parallel light tube (also can be a separate small-caliber transmitting telescope) to form an optical synthetic aperture system to realize partial filling of wavefront; it should be noted that, in the prior art, the aperture of the large-aperture telescope is generally 400-500 mm, and the sum of the apertures of the N discrete small-aperture collimator tubes can be approximately within the range of 400-500 mm;
s104, according to the fringe tracking result, the Root Mean Square (RMS) of the emergent wave front of the control system is reduced to be within 0.05 wavelength;
s105, moving each separated small-caliber collimator, covering the whole aperture frequency domain surface, and reconstructing a space domain;
s106, respectively changing the direction of each separated small-caliber collimator, detecting different view fields of the telescope to be detected, and controlling the emergent wave front comprehensive wave aberration value to be adjusted to be within 0.1 wavelength;
in practical application, aiming at detection of different fields of view, each separated small-caliber collimator can be respectively rotated; the separated small-caliber parallel light tubes are in flexible connection by adopting optical fibers, so that array change can be realized, and better space frequency coverage rate is provided.
In the optical system assembling and adjusting method based on optical fiber interconnection provided by the embodiment of the invention, the separated small-caliber collimator is used for forming an optical comprehensive caliber system, the optical fiber interconnection is utilized to ensure the coherence of wavefront synthesis, the wavefront is close to the sampling of an integral ideal wavefront, the PV value of the emergent wavefront comprehensive wave aberration is superior to 0.1 lambda (lambda is the working wavelength), and the RMS value is superior to 0.05 lambda, so that the function of the large-caliber collimator is realized by utilizing the separated small-caliber collimator, the detection assembling and adjusting of the optical system of the large-caliber telescope can be realized at lower cost, the dependence on the large-caliber collimator is reduced, the separated small-caliber collimator is less influenced by the atmosphere, the imaging quality can be improved, and the imaging quality is improved by utilizing the image recovery function after an image is formed on the target surface of the telescope to be detected.
In practical implementation, in the method for adjusting an optical system based on optical fiber interconnection provided by the embodiment of the invention, all light beams are transmitted in the polarization maintaining optical fiber. Therefore, the polarization state of the system emergent optical fiber can be well ensured by utilizing the polarization maintaining optical fiber, the polarization transfer function of the optical system can be measured, specifically, two polarized lights in the vertical directions are respectively adopted for detection, and the result is analyzed.
In specific implementation, in the optical system adjustment method based on optical fiber interconnection provided in the embodiment of the present invention, the step S106 of detecting different fields of view of the telescope to be detected may specifically include: firstly, establishing a sensitivity matrix; then, carrying out singular value decomposition on the established sensitivity matrix, and establishing a Zemax model; then, moving a certain optical element of the telescope to be detected by a set amount by using the matlab; and finally, extracting corresponding emergent wavefront comprehensive wave aberration values through the established Zemax model under different view fields of the telescope to be detected.
In particular, the detection of the aberrations obtained and the misalignment between the various elements of the system can be related by a sensitivity matrix. Because the optical system of the large-caliber large-view-field telescope is complex, the adjustment variables are more, and the correlation easily occurs between the adjustment variables, thereby causing matrix morbidity. If the linear correlation degree of the column vectors in the coefficient matrix is large, the normal matrix presents ill conditions, the inversion of the normal matrix is unstable, and the estimation value obtained by the least square method obviously deviates from the true value in consideration of the influence of observation noise. To address the disadvantage of the least squares method, the result is estimated by damped least squares. The principle of the invention for optical adjustment by using the sensitivity matrix is shown as follows:
(ATA+εI)ΔD＝ATΔZ
wherein:
ΔD＝(ATA+εI)-1ATΔZ
Singular value decomposition of A, A ═ U ∑ VTWherein ∑ diag (λ)1,λ2,L,λl) Is the singular value of a.
After a Zemax model is established, a certain optical element of the telescope is moved by a small amount by utilizing matlab, and then the corresponding wavefront aberration is extracted in a certain field of view. This process is then repeated for another adjacent field of view, instructing the establishment of its sensitivity matrix.
In a specific implementation, in the method for adjusting an optical system based on optical fiber interconnection provided in the embodiment of the present invention, the step S102 transmits each divided optical beam to each second optical fiber coupler, respectively, where the method includes: and transmitting each divided light beam to each second optical fiber coupler through the optical fiber delayer respectively. It should be noted that the interference array needs to adjust the error between the interference arms by a system to be less than one tenth of the working wavelength, and the interference fringe is blurred, i.e. the visibility is reduced, due to temperature variation, atmospheric disturbance, polarization, light intensity fluctuation, vibration, optical system aberration, etc., so that the optical path needs to be modulated, i.e. an optical fiber retarder, which is a common device in laser communication, is introduced, and in order to achieve matching with the device, the adopted wavelength may be 1310nm or 1550 nm. The optical fiber delayer can adjust and compensate the optical path difference between each path of light beam, and particularly can select an air stroke compensator to compensate the system error of a large stroke.
In a specific implementation, in the method for adjusting an optical system based on optical fiber interconnection provided in the embodiment of the present invention, the step S103 of performing fringe tracking may include: detecting by a fringe tracker to obtain an interference fringe image; and sampling four points of the obtained interference fringe image, and resolving the phase delay of the system to obtain a fringe tracking result.
Specifically, the fringe tracker includes a fringe sensor (fringe sensor), and mainly includes methods for obtaining real-time phase offset (real-time offset) by fitting a group envelope curve to calculate envelope delay, calculating group delay of dispersive spectral channels, calculating phase delay by an ABCD method, and the like; the method adopts an ABCD method, namely, the phase delay of the system is solved by sampling four points of interference fringes, the sensitivity reduction caused by the increase of the number of apertures is overcome, and the fringe tracking is realized.
In a specific implementation, in the method for adjusting an optical system based on optical fiber interconnection provided in the embodiment of the present invention, the step S104 is to control the root mean square of the wavefront exiting from the system to be reduced to within 0.05 wavelengths according to the fringe tracking result, and includes: according to the fringe tracking result, the optical path difference between the N paths of light beams with equal energy is adjusted by driving the optical fiber delayer, and the root mean square of the emergent wave front of the control system is reduced to be within 0.05 wavelength.
In practical application, although spatial filtering is performed between the sub-apertures through a single-mode fiber, an optical path difference exists, and a piston error exists in the emergent wavefront, so that an optical fiber retarder is required to be adopted to ensure that the emergent wavefront has an ideal combination of a plane wave and the sub-apertures, and a system common-phase state is maintained.
In specific implementation, in the optical system installation and adjustment method based on optical fiber interconnection provided in the embodiment of the present invention, the method may further include: the arrangement mode of the split small-caliber collimator is determined by a Modulation Transfer Function (MTF).
Here, MTF is used to determine the arrangement of the split small-aperture light pipes, and common sub-aperture arrangements include circular, three-arm, Golay type, and composite type. According to the fourier optics theory, different forms of sub-aperture sampling correspond to different MTFs. To accurately cover the spatial frequency range of interest, a combination of sub-aperture size, number and arrangement is required. Therefore, it is necessary to research an MTF rule corresponding to the target band design and an optimization method of the corresponding sub-aperture arrangement mode. Based on this, when step S105 is executed, as shown in fig. 2, Zernike polynomial order and subaperture arrangement are selected, orthogonalization is performed in the pupil, then wavefront data fitting is performed, then the target is covered according to MTF, and when the requirements are met, the target frequency band profile is output; if the requirement is not met, the frequency band coverage capability is insufficient, and the aperture arrangement and the fitting order need to be adjusted. Each Zernike polynomial has corresponding expression in the frequency domain, the characteristic peak value corresponding to each term can be obtained by substituting the expression into a calculation formula of a power spectrum, and the required number of substrates is determined according to the characteristic peak value and the target frequency band to be covered. And obtaining a power spectrum of airflow disturbance in the sub-aperture by using a method of combining the prior statistical information with the power spectrum, and decoupling the turbulence disturbance in a frequency domain filtering mode.
It should be noted that, the position and the aperture of the split small-aperture collimator are designed through MTF, so that partial filling of wavefront can be realized, and the frequency components to be covered in the final adjustment stage of the covering system are ensured, so that the MTF of the optical comprehensive aperture system formed by the split small-aperture collimator matches with the MTF of the large-aperture telescope to be detected.
In specific implementation, in the optical system installation and adjustment method based on optical fiber interconnection provided in the embodiment of the present invention, the method may further include: establishing a BP neural network; inputting an interference fringe image obtained by detecting by a fringe tracker into a BP neural network; and optimizing the weight value and the scale factor of the BP neural network, the translation factor, the weight value and the threshold value between nodes by utilizing error back propagation and combining a genetic algorithm, so that the secondary error between the output of the BP neural network and the phase delay of the system is minimum.
It can be understood that the method for correcting instrument errors by using the error model has the characteristics of short period, low cost and quick response, and because the large-caliber large-view-field telescope belongs to a customized product, a calibration manual directly utilized by some commercial devices can not be used, a more complicated modeling means needs to be used, but the common modeling method can not take into account the relationship between low-frequency drift and high-frequency disturbance at the same time. Taking the current sliding autoregressive model as an example, the coverage capability of the high-frequency error is limited under the condition of lower order, but the low-time and space-frequency errors caused by the factors such as temperature, gravity and the like cannot be well represented by using a higher order. The method of wavelet analysis can be adjusted according to the resolution of the time domain and the space domain, but the selection of the decomposition order can seriously affect the representation capability of the model. Therefore, the BP neural network is adopted for data modeling, the process of processing information by the human brain is simulated by adjusting the weight between different connected nodes, the nonlinear excitation function and the back propagation of the fitting junction residual error, and the method has the characteristics of good nonlinear fitting effect and strong generalization capability. Aiming at the problem of correcting the connection weight by error back propagation, a network with more targeted performance is obtained by combining an external optimization algorithm such as a genetic algorithm. The image detected in the fringe tracking unit is used as input, error back propagation is utilized, and the weight value of the network, the scale factor, the translation factor, the weight value between nodes and the threshold value are optimized by combining a genetic algorithm, so that the secondary error between the output of the neural network and the actual phase delay of the system is minimized. Therefore, various errors of the small-caliber collimator with the technical risk can be reduced, the optical path difference introduced by the processing and manufacturing errors of the small-caliber collimator is compensated by a subsequent algorithm, the error change in the motion process is corrected by an open loop, and the compensation precision can be ensured due to the small volume and the small weight of the small-caliber collimator.
In addition, the performance evaluation and error distribution of the large-aperture telescope system are complex system engineering, and the acquisition of the surface shape evaluation index from the frequency domain is an important technical route in the system engineering. In specific implementation, after the detection is completed, the estimation of the system PSSn on the premise of the discrete small-aperture collimator detection can be established by using the relationship between the normalized Point Source Sensitivity (PSSn) and the wavefront and optical transfer function.
Specifically, according to the definition of PSSn:
wherein:
f is the spatial frequency in units of (circle/rad) and λ is the wavelength. OTF is the convolution of the wavefront light field, and thus, for long exposure systems, its optical transfer function is an autocorrelation function of the pupil function, characterizing ideal diffraction system imaging. Another term represents the impact of a particular system on imaging, representing the lost imaging quality of the system due to its own characteristics.
Wherein the content of the first and second substances,
for the wavefront structure function, f is the spatial frequency in units of (circle/rad) and λ is the wavelength.
The weight of the component with small influence on imaging can be reduced by adopting a reasonable error evaluation criterion, so that the required information can be better extracted. The invention establishes an error model taking PSSn as an index, realizes the comprehensive consideration of the sensitivity of system errors and factors such as actual processing, production capacity, cost and the like, and realizes the error modeling of the surface shape obtaining process, including the influence of out-of-plane and non-out-of-plane errors on the surface shape. The system can not only carry out auto-collimation test on a single-lens large-aperture optical system, but also obtain integral wavefront information and adjust rigid displacement of sub-lenses in layout on a large-aperture telescope in a spliced mirror surface form.
Based on the same inventive concept, embodiments of the present invention further provide an optical system installation and adjustment device based on optical fiber interconnection, and as the principle of solving the problem of the optical system installation and adjustment device based on optical fiber interconnection is similar to that of the optical system installation and adjustment method based on optical fiber interconnection, the implementation of the optical system installation and adjustment device based on optical fiber interconnection may refer to the implementation of the optical system installation and adjustment method based on optical fiber interconnection, and repeated parts are not described again.
In specific implementation, the optical system adjusting device based on optical fiber interconnection provided by the embodiment of the present invention, as shown in fig. 2, may specifically include: the system comprises a laser 1, a first optical fiber coupler 2, N second optical fiber couplers 3, N separated small-caliber parallel light tubes 5 arranged in front of a telescope 4 to be detected, a stripe tracker 6 and a controller (not shown in the figure); wherein N is the number of separator apertures;
a laser 1 for emitting a light beam;
the first optical fiber coupler 2 is used for dividing the light beam emitted by the laser 1 into N paths with equal energy and transmitting each divided light beam to each second optical fiber coupler 3;
the second optical fiber coupler 3 is used for transmitting the light with 90% of energy split from each light beam to the split small-caliber collimator 5 and transmitting the light with 10% of energy split from each light beam to the fringe tracker 6;
a streak tracker 6 for performing streak tracking;
a controller (controller), which may be a Kalman controller, for controlling the root mean square of the outgoing wavefront of the system to be reduced to within 0.05 wavelength according to the fringe tracking result; the device is also used for moving each separated small-caliber collimator 5 (the movement of each separated small-caliber collimator 5 can be realized through a moving mechanism 7 in fig. 2), covering the whole aperture frequency domain surface, reconstructing a space domain, changing the direction of each separated small-caliber collimator 5 respectively, detecting different view fields of the telescope 4 to be detected, and controlling the emergent wavefront comprehensive wave aberration value to be adjusted to be within 0.1 wavelength.
In the optical system adjusting device based on optical fiber interconnection provided by the embodiment of the invention, the coherence of wavefront synthesis can be ensured through the interaction of the laser, the first optical fiber coupler, the second optical fiber coupler, the separated small-caliber collimator, the fringe tracker and the controller, so that the wavefront is close to the sampling of an integral ideal wavefront, the PV value of the emergent wavefront synthesis wave aberration is better than 0.1 lambda (lambda is the working wavelength), the RMS value is better than 0.05 lambda, the detection and adjustment of the large-caliber telescope optical system are realized at lower cost, and the dependence on the large-caliber collimator is reduced.
In specific implementation, in the optical system installation and adjustment method based on optical fiber interconnection provided by the embodiment of the present invention, the method further includes: n fiber delays 8 respectively located between the first fiber coupler 2 and the second fiber coupler 3;
and the optical fiber delayer 8 is used for adjusting the optical path difference between the N paths of light beams with equal energy.
For more specific working processes of the above components, reference may be made to corresponding contents disclosed in the foregoing embodiments, and details are not described herein again.
To sum up, the optical system installation and adjustment method and device based on optical fiber interconnection provided by the embodiment of the invention comprise: the light beam emitted by the laser is divided into N paths of light beams with equal energy through the first optical fiber coupler; wherein N is the number of separator apertures; transmitting each divided light beam to each second optical fiber coupler; transmitting the light with 90% of energy split from each path of light beam to N split small-caliber parallel light tubes arranged in front of the telescope to be detected through each second optical fiber coupler, and transmitting the light with 10% of energy split to a stripe tracker for stripe tracking; according to the fringe tracking result, the root mean square of the emergent wave front of the control system is reduced to be within 0.05 wavelength; moving each separated small-caliber collimator, covering the whole aperture frequency domain surface, and reconstructing a space domain; the direction of each separated small-caliber collimator is changed respectively, different fields of view of the telescope to be detected are detected, and the emergent wave front comprehensive wave aberration value is controlled to be adjusted to be within 0.1 wavelength. The separated small-caliber parallel light tube is used for forming the optical comprehensive caliber system to realize the function of the large-caliber parallel light tube, the optical fiber interconnection is utilized to ensure the coherence of wavefront synthesis, the wavefront is close to the sampling of an integral ideal wavefront, the PV value of the emergent wavefront comprehensive wave aberration is superior to 0.1 lambda (lambda is the working wavelength), the RMS value is superior to 0.05 lambda, the detection and adjustment of the large-caliber telescope optical system can be realized with lower cost, the dependence on the large-caliber parallel light tube is reduced, the separated small-caliber parallel light tube is less influenced by the atmosphere, and the imaging quality can be improved.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The method and apparatus for adjusting an optical system based on optical fiber interconnection provided by the present invention are described in detail above, and the principle and the implementation of the present invention are explained in detail herein by using specific examples, and the description of the above examples is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (10)
1. An optical system installation and adjustment method based on optical fiber interconnection is characterized by comprising the following steps:
the light beam emitted by the laser is divided into N paths of light beams with equal energy through the first optical fiber coupler; wherein N is the number of separator apertures;
transmitting each divided light beam to each second optical fiber coupler;
transmitting the light with 90% of energy split from each path of light beam to N split small-caliber parallel light tubes arranged in front of the telescope to be detected through each second optical fiber coupler, and transmitting the light with 10% of energy split to a stripe tracker for stripe tracking;
according to the fringe tracking result, the root mean square of the emergent wave front of the control system is reduced to be within 0.05 wavelength;
moving each separated small-caliber collimator, covering the whole aperture frequency domain surface, and reconstructing a space domain;
and respectively changing the direction of each separated small-caliber collimator, detecting different view fields of the telescope to be detected, and controlling the emergent wavefront comprehensive wave aberration value to be adjusted to be within 0.1 wavelength.
2. The method of claim 1, wherein all light beams are transmitted in a polarization maintaining fiber.
3. The method for adjusting the optical system based on the optical fiber interconnection as claimed in claim 1, wherein the detecting different fields of view of the telescope to be detected comprises:
establishing a sensitivity matrix;
performing singular value decomposition on the established sensitivity matrix, and establishing a Zemax model;
moving a certain optical element of the telescope to be detected by a set amount by using the matlab;
and extracting corresponding emergent wavefront comprehensive wave aberration values through the established Zemax model under different fields of view of the telescope to be detected.
4. The method for adjusting the optical system based on the optical fiber interconnection as claimed in claim 1, wherein the transmitting each of the divided optical beams to the second optical fiber couplers respectively comprises:
and transmitting each divided light beam to each second optical fiber coupler through the optical fiber delayer respectively.
5. The method of claim 4, wherein performing fringe tracking comprises:
detecting by the fringe tracker to obtain an interference fringe image;
and sampling four points of the obtained interference fringe image, and calculating the phase delay of the system to obtain a fringe tracking result.
6. The method of claim 5, wherein controlling the Root Mean Square (RMS) of the system's emergent wavefront to be reduced to within 0.05 wavelengths according to the fringe tracking result comprises:
according to the fringe tracking result, the optical path difference between the N paths of light beams with equal energy is adjusted by driving the optical fiber delayer, and the root mean square of the emergent wave front of the control system is reduced to be within 0.05 wavelength.
7. The method of claim 6, further comprising:
and determining the arrangement mode of the separated small-caliber parallel light tubes by modulating a transfer function.
8. The method of claim 7, further comprising:
establishing a BP neural network;
inputting the interference fringe image obtained by the fringe tracker to the BP neural network;
and optimizing the weight value and the scale factor of the BP neural network, the translation factor, the weight value and the threshold value between nodes by utilizing error back propagation and combining a genetic algorithm, so that the secondary error between the output of the BP neural network and the phase delay of the system is minimum.
9. An optical system installation and adjustment device based on optical fiber interconnection, comprising: the device comprises a laser, a first optical fiber coupler, N second optical fiber couplers, N separated small-caliber parallel light tubes arranged in front of a telescope to be detected, a stripe tracker and a controller; wherein N is the number of separator apertures;
the laser is used for emitting a light beam;
the first optical fiber coupler is used for dividing the light beam emitted by the laser into N paths with equal energy and transmitting each divided light beam to each second optical fiber coupler;
the second optical fiber coupler is used for transmitting the light with 90% of energy split from each light beam to the split small-caliber parallel light pipe and transmitting the light with 10% of energy split from each light beam to the fringe tracker;
the stripe tracker is used for carrying out stripe tracking;
the controller is used for controlling the root mean square of the emergent wave front of the system to be reduced to be within 0.05 wavelength according to the fringe tracking result; the device is also used for moving each separated small-caliber collimator, covering the whole aperture frequency domain surface, reconstructing a space domain, changing the direction of each separated small-caliber collimator respectively, detecting different fields of view of the telescope to be detected and controlling the emergent wavefront comprehensive wave aberration value to be adjusted to be within 0.1 wavelength.
10. The fiber optic interconnect-based optical system tuning device of claim 9, further comprising: n fiber delays respectively located between the first fiber coupler and the second fiber coupler;
and the optical fiber delayer is used for adjusting the optical path difference between the N paths of light beams with equal energy.
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