CN111551351B - Piston error detection system between adjacent splicing mirrors - Google Patents
Piston error detection system between adjacent splicing mirrors Download PDFInfo
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- CN111551351B CN111551351B CN202010519042.1A CN202010519042A CN111551351B CN 111551351 B CN111551351 B CN 111551351B CN 202010519042 A CN202010519042 A CN 202010519042A CN 111551351 B CN111551351 B CN 111551351B
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Abstract
The application discloses piston error detection system between adjacent concatenation mirror includes: an emission unit for providing broadband light; the modulation unit comprises a spatial light modulator and a scattering medium and is used for dynamically modulating the broadband light; the light splitting unit is used for splitting light and transmitting the split light to the spectrum measuring unit and the reflecting surface of the splicing sub-mirror respectively; the spectrum measuring unit is used for measuring the spectrum distribution modulated by the spatial light modulator and the scattering medium; the splicing sub-mirror is used for reflecting the light beam split by the light splitting unit to the imaging unit; an imaging unit for collecting a diffraction pattern; and the processing unit is used for controlling the spatial light modulator to adjust the spectral shape and the distribution to a specified shape, and is also used for analyzing and processing the diffraction pattern to obtain a pixel error value between two adjacent splicing sub-mirrors. The system overcomes the 2 pi fuzzy effect, enables the range of error detection of adjacent splicing mirrors to be dynamically adjustable, and can simultaneously realize large measurement range and high measurement precision.
Description
Technical Field
The invention relates to the field of spliced mirror surface detection, in particular to a piston error detection system between adjacent spliced mirrors.
Background
The resolving power of the imaging system of the ground-based telescope is related to factors such as the aperture of the telescope, the observation wavelength, the atmospheric vision and the like, the influence of the atmospheric vision can be well corrected through a self-adaptive optical technology, the resolving power of the imaging system of the ground-based telescope is in direct proportion to the effective aperture of the telescope under the specific observation wavelength, but with the continuous progress of astronomy, astronomy people put forward higher requirements on the aperture of the telescope for observing an astronomical target in a deeper position in the universe. However, the aperture of the single primary mirror telescope cannot be increased all the time due to a series of factors such as mirror blank preparation, optical processing, transportation, installation and adjustment, structural design and technical risk. In order to break through the technical barrier of the mirror surface of the single-aperture telescope, a spliced mirror surface technology is generated.
The splicing mirror surface technology enables the caliber of the built telescope to be increased sharply, and the urgent need of astronomers for telescopes with larger calibers is solved. However, the use of the tiled mirror technology also faces many new problems and challenges, among which the common phase problem of tiled sub-mirrors is urgently to be solved. The phase of the spliced sub-mirrors is consistent in the common phase requirement, and the imaging effect which is completely the same as that of a single mirror with the same caliber can be realized only when the common phase is achieved. This requires that the co-phasing be achieved by adjusting the piston of the splice sub-mirrors. The adjustment process is realized by a high-precision micro-displacement actuator positioned at the back of the spliced sub-mirrors, so that the high-precision detection of the piston between the adjacent spliced mirrors is required.
When the splicing telescope executes an observation task, the relative position between the splicing sub-lenses is changed under the influence of factors such as gravity action direction change, vibration, thermal gradient and the like, the confocal detection of the splicing sub-lenses is generally sensed by a Shack-Hartmann wavefront detection technology, and only a piston error is left after the adjustment of a displacement actuator positioned at the back of the splicing sub-lenses. At present, methods for detecting the piston error between splicing mirrors mainly comprise a wavefront curvature method, a Shack-Hartmann method, a pyramid sensor method, a phase recovery method, a phase difference method and the like. The above methods are all based on monochromatic or polychromatic light sources. However, in practical applications, technical measurements based on monochromatic light sources are subject to periodic variations due to the modulation of the wavelength of the monochromatic light, thereby creating a 2 π blur effect. The 2 pi fuzzy effect enables the measurement range based on the monochromatic light measurement technology to be changed into +/-lambda under the influence of the wavelength of the monochromatic light, thereby greatly reducing the application range of the technology. Although the technology based on the multicolor light source solves the 2 pi fuzzy effect in the monochromatic light source technology to a certain extent, other series of problems are introduced, for example, the selection of the multicolor light source needs to accurately calculate the wavelength of the selected light source, and a plurality of monochromatic light lasers can introduce non-common-path errors; although the mode of filtering the white light source by the optical filter is simple and easy, the spectrum obtained by filtering is fixed, and the optical filters with certain specific spectral distribution are difficult to select the optical filter meeting specific requirements due to the influence of material properties, thereby causing difficulty in engineering application; that is, in the multicolor light source technology, since the wavelength of the adopted light source is fixed, the measurement range is also fixed, and the measurement range of the piston error between the spliced mirrors cannot be dynamically adjusted. In the process of detecting the piston error between the splicing mirrors, the technical scheme of high measurement accuracy and large measurement range is required, however, the pair of spear bodies needs monochromatic light to improve the measurement accuracy, and needs to increase the spectral range to improve the measurement range, and the two are incompatible.
Therefore, how to simultaneously ensure a large range and high measurement accuracy and eliminate a 2 pi fuzzy effect in the process of detecting the piston error between the splicing mirrors is a technical problem to be solved urgently by the technical personnel in the field.
Disclosure of Invention
In view of this, the present invention provides a piston error detection system between adjacent splicing mirrors, which has a large measurement range and high measurement accuracy, and can eliminate the 2 pi fuzzy effect. The specific scheme is as follows:
an inter-adjacent-mosaics piston error detection system, comprising: the device comprises an emission unit, a modulation unit, a light splitting unit, a spectrum measurement unit, two adjacent splicing sub-mirrors, an imaging unit and a processing unit; wherein the content of the first and second substances,
the emission unit is used for providing broadband light;
the modulation unit comprises a spatial light modulator and a scattering medium and is used for dynamically modulating the broadband light provided by the emission unit;
the light splitting unit is used for splitting the light beams output by the modulation unit and respectively transmitting the light beams to the spectrum measurement unit and the reflecting surfaces of the two adjacent splicing sub-mirrors;
the spectrum measuring unit is used for measuring the spectrum distribution modulated by the spatial light modulator and the scattering medium;
the two adjacent sub-splicing mirrors are used for reflecting the light beams split by the light splitting unit and transmitting the light beams to the imaging unit;
the imaging unit is used for collecting diffraction patterns;
the processing unit is respectively connected with the spatial light modulator, the spectrum measuring unit and the imaging unit, and is used for controlling the spatial light modulator to adjust the spectrum shape and distribution to a specified shape, and analyzing and processing the diffraction pattern acquired by the imaging unit to obtain a piston error value between the two adjacent splicing sub-mirrors.
Preferably, in the system for detecting a piston error between adjacent splicing mirrors provided in the embodiment of the present invention, the transmitting unit includes a wide-spectrum light source for emitting a beamlet, and a beam expander, a linear polarizer, an entrance pupil, a first converging lens and a first collimating lens sequentially disposed on a transmission light path; wherein the content of the first and second substances,
the beam expander is used for changing the thin beam into a thick beam and transmitting the thick beam to the linear polarizer;
the linear polaroid is used for polarizing the coarse light beam to obtain polarized light;
the entrance pupil is used for limiting the effective aperture of the polarized light;
the first converging lens is used for converging the polarized light;
the first collimating lens is used for converting the light converged by the first converging lens into parallel beams so as to obtain the broadband light and transmitting the broadband light to the spatial light modulator.
Preferably, in the system for detecting a piston error between adjacent splicing mirrors provided in the embodiment of the present invention, the modulation unit further includes a mirror;
the reflecting mirror is used for reflecting the light beams modulated by the spatial light modulator and the scattering medium and transmitting the reflected light beams to the light splitting unit.
Preferably, in the system for detecting a piston error between adjacent splicing mirrors provided in the embodiment of the present invention, the light splitting unit is a light splitting prism, and is specifically configured to split the reflected light beam transmitted by the mirror into two paths, where a first path of the light beam is parallel to the reflected light beam and is transmitted to the spectrum measuring unit, and a second path of the light beam is perpendicular to the reflected light beam and is transmitted to the reflection surfaces of the two adjacent splicing sub-mirrors.
Preferably, in the system for detecting a piston error between adjacent splicing lenses provided by the embodiment of the present invention, the spectral measurement unit includes a second converging lens, a second collimating lens and a spectrometer; wherein the content of the first and second substances,
the second converging lens is used for converging the light beams split by the light splitting unit;
and the second collimating lens is used for converting the light converged by the second converging lens into parallel light beams and transmitting the parallel light beams to the spectrometer.
Preferably, in the system for detecting a piston error between two adjacent splicing mirrors provided in the embodiment of the present invention, a first mask is disposed between the light splitting unit and the two adjacent splicing sub-mirrors; the opening of the first mask plate corresponds to the splicing position of the two adjacent splicing sub-mirrors.
Preferably, in the system for detecting a piston error between adjacent splicing lenses provided by the embodiment of the present invention, the imaging unit includes a third converging lens, a second mask, a third collimating lens and an imaging system; wherein the content of the first and second substances,
the third converging lens is used for converging the light beams reflected by the two adjacent splicing sub-mirrors, and a converging point is arranged at the opening of the second mask plate; the second mask is a quasi-Hole mask;
the third collimating lens is used for converting the light passing through the second mask into parallel beams and transmitting the parallel beams to the imaging system;
the imaging system is used for converting the received parallel light beams into diffraction patterns.
Preferably, in the system for detecting a piston error between adjacent splicing mirrors provided by the embodiment of the present invention, the wide-spectrum light source is a multicolor LED light source.
Preferably, in the system for detecting a piston error between adjacent splicing mirrors provided in the embodiment of the present invention, the spatial light modulator is a liquid crystal spatial light modulator.
Preferably, in the system for detecting a piston error between adjacent splicing mirrors provided by the embodiment of the present invention, the imaging system is a CCD detector.
According to the technical scheme, the system for detecting the piston error between the adjacent splicing mirrors comprises: the device comprises an emission unit, a modulation unit, a light splitting unit, a spectrum measurement unit, two adjacent splicing sub-mirrors, an imaging unit and a processing unit; the emission unit is used for providing broadband light; the modulation unit comprises a spatial light modulator and a scattering medium and is used for dynamically modulating the broadband light provided by the emission unit; the light splitting unit is used for splitting the light beams output by the modulation unit and respectively transmitting the light beams to the spectrum measurement unit and the reflecting surfaces of the two adjacent splicing sub-mirrors; the spectrum measuring unit is used for measuring the spectrum distribution modulated by the spatial light modulator and the scattering medium; the two adjacent sub-splicing mirrors are used for reflecting the light beams split by the light splitting unit and transmitting the light beams to the imaging unit; an imaging unit for collecting a diffraction pattern; and the processing unit is respectively connected with the spatial light modulator, the spectrum measuring unit and the imaging unit, is used for controlling the spatial light modulator to adjust the spectrum shape and the distribution to the specified shape, and is also used for analyzing and processing the diffraction pattern acquired by the imaging unit to obtain a pixel error value between two adjacent spliced sub-mirrors.
The invention adopts the form of combining the spatial light modulator and the scattering medium to dynamically adjust the filtering characteristic of the scattering medium, controls the phase distribution of the spatial light modulator to modulate the spectrum shape and distribution of the broadband light, and adopts the imaging unit to convert the piston information between adjacent sub-mirrors into diffraction pattern information, thereby not only overcoming the 2 pi fuzzy effect, but also enabling the range of the piston error detection of the adjacent splicing mirrors to be dynamically adjustable, greatly increasing the detection range, improving the efficiency of the piston error detection between the adjacent sub-mirrors of the splicing mirror surface, avoiding introducing non-common optical path errors, improving the dynamic characteristic and the measurement precision of the system, and being suitable for the common-phase detection of the splicing telescope splicing mirror surface which needs high-precision common phase; in addition, compared with other measuring methods, the optical filter does not need to be replaced, and the system has no relative moving part, so that the introduction of position errors is avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or technical solutions in related arts, the drawings used in the description of the embodiments or related arts will be briefly introduced 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 schematic structural diagram of a piston error detection system between adjacent splicing mirrors according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a piston error detection system between adjacent splicing mirrors 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 a piston error detection system between adjacent splicing mirrors, as shown in figure 1, comprising: the device comprises an emission unit 1, a modulation unit 2, a light splitting unit 3, a spectrum measurement unit 4, two adjacent splicing sub-mirrors 5, an imaging unit 6 and a processing unit 7; wherein the content of the first and second substances,
an emission unit 1 for providing broadband light;
a modulation unit 2 including a Spatial Light Modulator (SLM)21 and a scattering medium 22 for dynamically modulating the broadband light provided by the emission unit 1; preferably, the spatial light modulator 21 may be selected as a liquid crystal spatial light modulator (LC-SLM), the phase of the spatial light modulator 21 may be modified by the processing unit to achieve the effect of modulating the spectrum of the polychromatic light, and the polychromatic light with the specific distribution and the specific shape is generated to be used for the pixel error detection between the adjacent splicing mirrors;
the light splitting unit 3 is used for splitting the light beams output by the modulation unit 2 and respectively transmitting the light beams to the spectrum measurement unit 4 and the reflecting surfaces of the two adjacent splicing sub-mirrors 5;
a spectrum measuring unit 4 for measuring the spectrum distribution modulated by the spatial light modulator 21 and the scattering medium 22;
two adjacent sub-lenses 5 for reflecting the light beam split by the light splitting unit 3 and transmitting the light beam to the imaging unit 6;
an imaging unit 6 for collecting a diffraction pattern;
the processing unit 7 is respectively connected with the spatial light modulator 21, the spectrum measuring unit 4 and the imaging unit 6, and is used for controlling the spatial light modulator 21 to adjust the spectrum shape and distribution to an appointed shape, and analyzing and processing the diffraction pattern acquired by the imaging unit 6 to obtain a piston error value between two adjacent splicing sub-mirrors 5; preferably, the processing unit 7 may be a computer.
In the system for detecting the piston error between the adjacent splicing mirrors, provided by the embodiment of the invention, the filtering characteristic of the scattering medium is dynamically adjusted in a mode of combining the spatial light modulator and the scattering medium, the phase distribution of the spatial light modulator is controlled to modulate the spectral shape and distribution of broadband light, and the imaging unit is adopted to convert the piston information between the adjacent sub-mirrors into diffraction pattern information, so that not only is the 2 pi fuzzy effect overcome, but also the range of the piston error detection of the adjacent splicing mirrors is dynamically adjustable, the detection range is greatly increased, the efficiency of the piston error detection between the adjacent sub-mirrors of the splicing mirror surface is improved, the introduction of non-common-path errors is avoided, the dynamic characteristic and the measurement precision of the system are improved, and the system is suitable for the common-phase detection of the splicing mirror surface of the splicing telescope needing high-precision common phase; in addition, compared with other measuring methods, the optical filter does not need to be replaced, and the system has no relative moving part, so that the introduction of position errors is avoided.
In practical application, the invention adopts a method of combining a spatial light modulator and a scattering medium to dynamically adjust the filtering characteristic of the scattering medium, obtains light with proper spectral distribution for the photosensing error detection between splicing mirrors, and increases the width of a filtering spectrum to solve the 2 pi fuzzy effect; when the 2 pi fuzzy effect is eliminated, the range of the piston error between the splicing mirrors is reduced to be within the monochromatic light measurement range, the phase distribution of the spatial light modulator is adjusted, so that the scattering medium filters light emitted by the light source to obtain narrow-band light with narrow and sharp spectral distribution, and the piston error between the splicing mirrors with the 2 pi fuzzy effect eliminated is precisely measured, so that the large measurement range and the high measurement precision are ensured at the same time.
It should be noted that the capture range of the piston error between the splicing mirrors can be dynamically adjusted by adjusting the spectral distribution of the broadband light, and the measurement accuracy of the piston error between the splicing mirrors can be dynamically adjusted by adjusting the spectral width of the broadband light.
In specific implementation, in the above-mentioned piston error detection system between adjacent splicing mirrors provided in the embodiment of the present invention, as shown in fig. 2, the transmitting unit 1 may include a wide-spectrum light source 11 for emitting a beamlet, and a beam expander 12, a linear polarizer 13, an entrance pupil 14, a first converging lens 15, and a first collimating lens 16, which are sequentially disposed on a transmission optical path; wherein, the beam expander 12 is used for changing the thin beam into a thick beam and transmitting the thick beam to the linear polarizer 13; the linear polarizer 13 is used for polarizing the coarse light beam to obtain polarized light; an entrance pupil 14 for limiting the effective aperture of the polarized light; a first condensing lens 15 for condensing the polarized light; and a first collimating lens 16 for converting the light converged by the first converging lens 15 into a parallel beam to obtain broadband light and transmitting the broadband light to the spatial light modulator 21. Preferably, the wide-spectrum light source 11 is a frequency-stabilized wide-spectrum light source, and can be configured as a multi-color LED light source.
In specific implementation, in the above-mentioned piston error detection system between adjacent splicing mirrors provided in the embodiment of the present invention, as shown in fig. 2, the modulation unit 2 may further include a mirror 23; and a reflecting mirror 23 for reflecting the light beam modulated by the spatial light modulator 21 and the scattering medium 22 and transmitting the reflected light beam to the light splitting unit 3. Figure 2 shows that the mirror can reflect the beam parallel to the broadband light.
In specific implementation, in the above-mentioned piston error detection system between adjacent splicing mirrors provided in the embodiment of the present invention, as shown in fig. 2, the light splitting unit 3 may be a light splitting prism, and is specifically configured to split the reflected light beam transmitted by the reflecting mirror 23 into two paths, where the first path of light beam is parallel to the reflected light beam and is transmitted to the spectrum measuring unit 4, and the second path of light beam is perpendicular to the reflected light beam and is transmitted to the reflecting surfaces of two adjacent splicing sub-mirrors 5.
In specific implementation, in the above-mentioned piston error detection system between adjacent splicing lenses provided in the embodiment of the present invention, as shown in fig. 2, the spectrum measuring unit 4 includes a second converging lens 41, a second collimating lens 42, and a spectrometer 43; the second converging lens 41 is configured to converge the light beam split by the light splitting unit 3 (i.e., the first light beam); and a second collimating lens 42 for converting the light condensed by the second condensing lens 41 into a parallel beam and transmitting the parallel beam to the spectrometer 43.
In specific implementation, in the system for detecting a piston error between two adjacent splicing mirrors provided in the embodiment of the present invention, as shown in fig. 2, two adjacent splicing sub-mirrors 5 include a first splicing sub-mirror 51 and a second splicing sub-mirror 52; a first Mask (Mask)53 is arranged between the light splitting unit 3 and the two adjacent splicing sub-mirrors 5; the opening of the first mask 53 corresponds to the joint of two adjacent splicing sub-mirrors 5 (i.e. the joint between the first splicing sub-mirror 51 and the second splicing sub-mirror 52).
In specific implementation, in the above system for detecting a piston error between adjacent splicing lenses provided in the embodiment of the present invention, as shown in fig. 2, the imaging unit 6 includes a third converging lens 61, a second mask 62, a third collimating lens 63, and an imaging system 64; the third converging lens 61 is used for converging the light beams reflected by the two adjacent splicing sub-mirrors 5, and the converging point is at the opening of the second mask 62; the second Mask 62 is a quasi-Hole Mask for diffraction; a third collimating lens 63 for converting the light passing through the second mask 62 into a parallel beam and transmitting to an imaging system 64; an imaging system 64 for converting the received parallel beams into a diffraction pattern. Preferably, the imaging system 64 may be configured as a CCD detector.
Through the description of the above components, the optical path transmission of the piston error detection system between the adjacent splicing mirrors provided by the embodiment of the present invention may specifically be: as shown in fig. 2, the wide-spectrum light source 11 emits a thin light beam, the thin light beam is converted into a thick light beam by the beam expander 12, and then the thick light beam is incident on the linear polarizer 13, the polarized light passes through the entrance pupil 14 after being polarized by the linear polarizer 13, the polarized light passes through the first converging lens 15, the first collimating lens 16 and then reaches the spatial light modulator 21, and the wavefront phase is modulated by the spatial light modulator 21. The light modulated by the spatial light modulator 21 is reflected by the reflecting mirror 23 and reaches the light splitting unit 3 (i.e., a light splitting prism), and the light beam is split into two paths by the light splitting prism. One path of light beams sequentially passes through the second converging lens 41 and the second collimating lens 42 to reach the spectrometer 43, the spectrometer 43 measures the spectral distribution modulated by the spatial light modulator and the scattering medium, the processing unit 7 (namely, a computer) controls the spatial light modulator 21 to adjust the spectral shape and distribution to a specified shape, the spectrometer 43 can specifically collect the modulated spectrum, and a subsystem consisting of the spatial light modulator 21, the spectrometer 43 and the computer is used for realizing feedback adjustment to adjust the spectrum to a specified distribution form. The other path of light reaches the reflecting surfaces of the first splicing sub-mirror 51 and the second splicing sub-mirror 52 after passing through the Mask 53 and is reflected, the reflected light beam sequentially passes through the beam splitter prism, the third converging lens 61, the Hole Mask 62 and the third collimating lens 63 and reaches the imaging system 64, the imaging system 64 collects far-field diffraction patterns, and the pixel error value between the first splicing sub-mirror 51 and the second splicing sub-mirror 52 is obtained after data processing of the computer.
It should be noted that, the technical problem mainly faced in the current splicing mirror common-phase technology is the 2 pi fuzzy effect caused by the periodic change of the wavelength of the monochromatic light, and in order to solve the problem, the piston error detection system between the adjacent splicing mirrors provided by the invention utilizes a dual-wavelength method and a dual-band coherence measurement method in the detection process.
The following is a detailed description of the principle of the above-mentioned piston error detection system between adjacent splicing mirrors provided by the present invention:
dual wavelength (lambda)1λ2) The range of the pixel error capture of the method is +/-Lambda/2
Double-waveband dry method: the optical filter has a coherence length of
Wherein λ is0At center wavelength, δ λFIs the spectral width.
Assuming a gaussian band pass:
Δλ＝λ2-λ1 (5)
λ0＝(λ1+λ2)/2 (6)
the traditional broadband light measuring method needs to provide broad spectrum light by a white light source, a filter wheel is added in a light path, light emitted by the light source is filtered by different filters in the filter wheel, and light in a specific wave band is intercepted.
Wherein the content of the first and second substances,
is the spectral density of the incident light,<·>representing the envelope mean, tmn(λ) denotes the transfer matrix of the scattering medium at the wavelength of the incident light λ,
in order to make the light field incident,
is the phase at which light of wavelength λ passes through the nth tile of the phase-only SLM.
Assuming at the design wavelength λ0To modulate the phase
Varies linearly between 0 and 2 pi, the modulation term being
At different wavelengths λ, the modulation characteristics of each LC-SLM pixel can be used to match the reference wavelength λ0Is expressed by the modulation characteristics of:
wherein b isqAre fourier coefficients. From a physical point of view, this means at the wavelength λ0A modulation operating at wavelength lambda can be understood as a combination of multiple order scaled copies of the original modulation effect. Furthermore, formula (8) is substituted for formula (7) to derive a filtered field after wavefront modulation in the case of non-monochromatic:
equation (9) shows that a suitable phase map
The scattering response can be adjusted, which indicates that the scattering medium can be used as an active spectrum filter to realize dynamic filtering of the active spectrum.
In order to control the response of the whole broadband light, a correlation coefficient is used as a feedback signal in the form of
Wherein the content of the first and second substances,
when P is the number of wavelength components of the spectrometer, lambdaiAt a wavelength of ith component, Isp(λi) Lambda representing the spectrometer collectioniIntensity of component, and Iref(λi) Is the intensity of the target spectrum. The correlation coefficients are distributed between-1 and 1, corresponding to a complete negative and positive correlation between the target and the collected scatter spectrum, respectively. However, the correlation coefficients defined in the formula depict the spectral profile regardless of the intensity magnitude. To solve this problem, the present invention introduces a zero intensity band that does not cover the wavelength range of the light source. During the optimization, this band is kept at zero, thus being the intensity level of the target spectrum. Thus, the target spectrum consists of a spectrum shaping and zero intensity bands.
By utilizing the mode, the dynamic interception of the broadband light source frequency spectrum can be realized, the wider the interception bandwidth is, the larger the capture range of the splicing mirror common-phase detection is, the narrower the interception bandwidth is, and the higher the precision of the splicing mirror common-phase detection is. In the initial stage of the joint mirror common-phase detection, the spatial light filter (SLM) is adjusted to intercept a larger bandwidth of a spectrum, the capture range of the piston error between the joint mirrors is improved, after 2 pi fuzziness in the piston error is eliminated, the spatial light filter (SLM) is adjusted to intercept a narrow-band spectrum, and the piston error between the joint mirrors is accurately measured, so that a large measurement range and high measurement precision can be realized simultaneously, and a light source and a light filter do not need to be replaced.
To sum up, the system for detecting the piston error between adjacent splicing mirrors provided by the embodiment of the invention comprises: the device comprises an emission unit, a modulation unit, a light splitting unit, a spectrum measurement unit, two adjacent splicing sub-mirrors, an imaging unit and a processing unit; the emission unit is used for providing broadband light; the modulation unit comprises a spatial light modulator and a scattering medium and is used for dynamically modulating the broadband light provided by the emission unit; the light splitting unit is used for splitting the light beams output by the modulation unit and respectively transmitting the light beams to the spectrum measurement unit and the reflecting surfaces of the two adjacent splicing sub-mirrors; the spectrum measuring unit is used for measuring the spectrum distribution modulated by the spatial light modulator and the scattering medium; the two adjacent sub-splicing mirrors are used for reflecting the light beams split by the light splitting unit and transmitting the light beams to the imaging unit; an imaging unit for collecting a diffraction pattern; and the processing unit is respectively connected with the spatial light modulator, the spectrum measuring unit and the imaging unit, is used for controlling the spatial light modulator to adjust the spectrum shape and the distribution to the specified shape, and is also used for analyzing and processing the diffraction pattern acquired by the imaging unit to obtain a pixel error value between two adjacent spliced sub-mirrors. Thus, the filtering characteristic of the scattering medium is dynamically adjusted in a mode of combining the spatial light modulator and the scattering medium, the phase distribution of the spatial light modulator is controlled to modulate the spectral shape and distribution of broadband light, and the imaging unit is adopted to convert the pixel information between adjacent sub-mirrors into diffraction pattern information, so that the 2 pi fuzzy effect is overcome, the range of pixel error detection of the adjacent splicing mirrors is dynamically adjustable, the detection range is greatly increased, the efficiency of pixel error detection between the adjacent sub-mirrors of the splicing mirror surface is improved, the introduction of non-common optical path errors is avoided, the dynamic characteristic and the measurement precision of the system are improved, and the method is suitable for the common-phase detection of the splicing mirror surface of the splicing telescope needing high-precision common phase; in addition, compared with other measuring methods, the optical filter does not need to be replaced, and the system has no relative moving part, so that the introduction of position errors is avoided.
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 last description is made in detail on the system for detecting the piston error between adjacent splicing mirrors provided by the invention, and a specific example is applied in the text to explain the principle and the implementation mode of the invention, and the description of the above embodiment is only used for helping to understand the method and the core idea of the 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 inter-adjacent-mosaic-lens piston error detection system, comprising: the device comprises an emission unit, a modulation unit, a light splitting unit, a spectrum measurement unit, two adjacent splicing sub-mirrors, an imaging unit and a processing unit; wherein the content of the first and second substances,
the emission unit is used for providing broadband light;
the modulation unit comprises a spatial light modulator and a scattering medium and is used for dynamically modulating the broadband light provided by the emission unit;
the light splitting unit is used for splitting the light beams output by the modulation unit and respectively transmitting the light beams to the spectrum measurement unit and the reflecting surfaces of the two adjacent splicing sub-mirrors;
the spectrum measuring unit is used for measuring the spectrum distribution modulated by the spatial light modulator and the scattering medium;
the two adjacent sub-splicing mirrors are used for reflecting the light beams split by the light splitting unit and transmitting the light beams to the imaging unit;
the imaging unit is used for collecting diffraction patterns;
the processing unit is respectively connected with the spatial light modulator, the spectrum measuring unit and the imaging unit, and is used for controlling the spatial light modulator to adjust the spectrum shape and distribution to a specified shape, and analyzing and processing the diffraction pattern acquired by the imaging unit to obtain a piston error value between the two adjacent splicing sub-mirrors.
2. The system for detecting the piston error between the adjacent splicing mirrors as claimed in claim 1, wherein the transmitting unit comprises a wide-spectrum light source for emitting the thin light beams, and a beam expander, a linear polarizer, an entrance pupil, a first converging lens and a first collimating lens which are arranged on a transmission light path in sequence; wherein the content of the first and second substances,
the beam expander is used for changing the thin beam into a thick beam and transmitting the thick beam to the linear polarizer;
the linear polaroid is used for polarizing the coarse light beam to obtain polarized light;
the entrance pupil is used for limiting the effective aperture of the polarized light;
the first converging lens is used for converging the polarized light;
the first collimating lens is used for converting the light converged by the first converging lens into parallel beams so as to obtain the broadband light and transmitting the broadband light to the spatial light modulator.
3. The system for detecting a piston error between adjacent splicing mirrors of claim 2, wherein the modulation unit further comprises a mirror;
the reflecting mirror is used for reflecting the light beams modulated by the spatial light modulator and the scattering medium and transmitting the reflected light beams to the light splitting unit.
4. The system for detecting the piston error between the adjacent splicing mirrors as claimed in claim 3, wherein the light splitting unit is a light splitting prism, and is specifically configured to split the reflected light beam transmitted by the mirror into two paths, a first path of light beam is parallel to the reflected light beam and is transmitted to the spectrum measuring unit, and a second path of light beam is perpendicular to the reflected light beam and is transmitted to the reflection surfaces of the two adjacent splicing sub-mirrors.
5. The system for detecting the piston error between the adjacent splicing mirrors as claimed in claim 4, wherein the spectrum measuring unit comprises a second converging lens, a second collimating lens and a spectrometer; wherein the content of the first and second substances,
the second converging lens is used for converging the light beams split by the light splitting unit;
and the second collimating lens is used for converting the light converged by the second converging lens into parallel light beams and transmitting the parallel light beams to the spectrometer.
6. The system for detecting the piston error between the adjacent splicing mirrors as claimed in claim 5, wherein a first mask is arranged between the light splitting unit and the two adjacent splicing sub-mirrors; the opening of the first mask plate corresponds to the splicing position of the two adjacent splicing sub-mirrors.
7. The system for detecting the piston error between the adjacent splicing mirrors as claimed in claim 6, wherein the imaging unit comprises a third converging lens, a second mask, a third collimating lens and an imaging system; wherein the content of the first and second substances,
the third converging lens is used for converging the light beams reflected by the two adjacent splicing sub-mirrors, and a converging point is arranged at the opening of the second mask plate; the second mask is a quasi-Hole mask;
the third collimating lens is used for converting the light passing through the second mask into parallel beams and transmitting the parallel beams to the imaging system;
the imaging system is used for converting the received parallel light beams into diffraction patterns.
8. The system for detecting a piston error between adjacent spliced mirrors of claim 2, wherein the wide-spectrum light source is a multi-color LED light source.
9. The system for detecting a piston error between adjacent splicing mirrors according to claim 1, wherein the spatial light modulator is a liquid crystal spatial light modulator.
10. The system for detecting a piston error between adjacent spliced mirrors of claim 7, wherein the imaging system is a CCD detector.
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| CN112880986B (en) * | 2021-03-26 | 2021-12-21 | 北京理工大学 | Spliced telescope translation error detection method based on convolutional neural network |
| CN113324540B (en) * | 2021-06-03 | 2023-07-07 | 合肥工业大学 | System and method for testing pose of spliced mirror based on scanning galvanometer |
| CN114076670B (en) * | 2022-01-19 | 2022-07-08 | 中国科学院西安光学精密机械研究所 | Splicing primary mirror common-phase error detection method, system and storage medium |
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