This PDF file contains the front matter associated with SPIE Proceedings Volume 10837, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

In this paper, a novel fiber bundle probe which can transfer energy and provide a real-time feedback signal of fiber positions simultaneously is proposed and demonstrated experimentally to improve the fiber positioning accuracy of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). The fiber bundle probe is composed of four asteroid cores around a transmitting energy core at the center of the fiber bundle probe. The excitation characteristics were investigated numerically when a light spot illuminates on the end of the five-core fiber bundle probe. The calculated result shows that the fiber bundle probe can provide a real-time feedback signal when the offset between the center of end of probe and the light spot is in the range of -349.5 ~ -99.5 μm and 99.5 ~ 349.5 μm. Then the fiber bundle probe is fabricated by stacking-capillary method.

To ensure the dimensional stability of the opto-mechanical structure of the space optical remote sensor is an important prerequisite for the acquisition of high quality images. The change of the relative position between the primary and secondary mirrors has a great influence on the imaging quality of the long focal length optical remote sensor. Several common forms of supporting structure between the primary and secondary mirrors and the secondary mirror support of lightweight, high stiffness have been analyzed. This paper has designed a baffle tube between primary and secondary mirrors of high modulus carbon fiber M55J/cyanate ester material, carbon fiber composite main body with titanium alloy inserts integral the secondary mirror supporting structure. Through static and dynamic analysis, it is proved that the designed optical remote sensor has good structural stability and dynamic characteristics, and meets the requirements of engineering application.

As one of the largest aerospace countries in the world, China’s National Space Administration has officially launched the China Mars Exploration Project in 2016. The zoom lens, in contrast to a fixed focal length lens, has a continuously variable focal length that provides more intuitive information for probing activities. Therefore, it is particularly important to design a zoom lens and use it as a Mars probe imaging payload. In this paper, a zoom system is designed for the climatic environment of Mars and the condition requirements of the lander during transportation work. At the same time, different types of structures were discussed. Finally, a cam rotation mechanism was used in the zoom mechanism. Examining the complexity of the space thermal environment, the thermal characteristics of the system structure will have a great impact on the system performance. To prevent the adverse effects of different thermal expansion coefficients on the system over a wide operating temperature range, select the appropriate materials and the overall structure It is very important to carry out finite element analysis. In this paper, thermal deformation analysis of Aluminum Alloys, Titanium Alloys and Invar Steel materials was performed. The results show that the thermal deformation of Aluminum Alloy materials is maximum at the working temperature of -55°C to +55°C, the thermal deformation of the Aluminum Alloy material is the largest, and the titanium alloy and Invar Steel are relatively small. Finally, the axial displacement is analyzed. The analysis results show that Invar Steel material has the smallest axial displacement. However, considering the weight reduction, it has met the rocket launch requirements. Finally, titanium alloy material is used as the system structural material, and the cam curve is compensated according to the axial displacement.

Ultraviolet (UV) detection and imaging technology has developed rapidly in military applications due to its simple environment and clean background. Especially in the ultraviolet communication, UV alarm, UV detection and UV guidance has a unique advantage. A medium telephoto transmission type UV optical system was designed using optical software. This system consisting of two aspheric surfaces and one binary diffractive surface and the other 10 spherical surfaces is adopted to realize the long-wavelength infrared image design parameters: UV operating waveband of 240- 300nm, focal length of 200mm, field of view (FOV) of 24.8 degree, the F number of 2, and total length of 210mm. By optimizing materials and distributing power properly the system characteristics have been greatly improved. After optimization, the MTF is higher than 0.7 at the 20lp/mm and the maximum RMS radius is only about 10 μm, which is much smaller than pixel size of the detector whose pixel size is 13.5μm×13.5μm. The energy concentration in UV CCD receiving surface is greater than 82%. Under the premise that the system meets the UV warning and detection optical properties, the use of aspheric surfaces reduces aberrations, simplifies the structure. This system has high imaging quality and simple structure. In terms of warning, it has good concealment, small size and light weight advantages.

This paper mainly introduces the motion analysis and the stress of some components of the full-disc vector magnetograph (FMG). As the connecting part of the FMG and the satellite platform, its main function is to adjust the optical axis of the FMG so that its imaging of the sun remains in the center of the CCD, thus achieving pitch and yaw of the optical axis. The maximum adjusting range is ±12′ and the regulation precision is ±5′′. The kinematic support is used to connect the optical box and the satellite platform. The two Monopods are respectively mounted on the two YZ planes of the optical cabin. The Bipod is mounted on the XZ plane of the optical capsule, which can adjust the pitch and yaw of the optical capsule. The movement of the Bipod is mainly powered by two motors. This paper simulates the force condition of the motor's screw sleeve to calculate the parameters of the motor. This article simulates the upward, downward, leftward and rightward movements of the pitch and yaw motions of the FMG's on-orbit pointing adjustment mechanism. Compared with the results of MATLAB theoretical calculations, the maximum error of the simulation results is 0.7969mm, and the minimum error is 0.0212mm, which basically accords with the ideal sports condition.

In order to analyze the influence of laser irradiation on high-order aberrations of the deformed mirror, the finite element model of a 37-element deformable mirror was built. The deformation and high-order aberrations were calculated after applying the laser irradiation to the mirror. Based on the results, we found the high-order aberrations became larger and larger while the thickness of the mirror decreasing. The high-order aberration presented a honeycomb shape of the piezoelectric actuator when the mirror thickness is 1 mm. The PV decreased from 0.128 μm to 0.104 μm when the mirror got thicker from 1 mm to 3 mm, and the corresponding removed low-order Zernike coefficient residual error was reduced from 0.107 μm to 0.0504 μm. The high-order aberrations of the deformed mirror were very little when the mirror surface thickness was 3 mm. The results have practical engineering application for the design of deformable mirrors in future laser systems.

Large-aperture telescope with its high spatial resolution and high light gathering capability plays an important role in military, astronomy and other fields. The demand for large aperture imaging telescope is increasingly urgent, the aperture becomes larger and larger, and the splicing main mirror has become the development trend of large-aperture telescope which brings great challenges to the optical processing and testing. This paper proposes phase-diversity phase retrieval technology which can provide a strong basis for the online testing of the future larger diameter astronomical telescope optical system and solve the difficulties in the detection of optical systems in large-aperture telescopes. Therefore, this study has important practical significance and application value in the online testing of the large-aperture telescope optical system.

To realize ultra-lightweight ratio, mirrors were fabricated with CFRP (carbon fiber reinforced plastic composites) by replication technology. The replication technology was aimed to improve surface accuracy. Though replication technique, the surface accuracy was improved to 0.098 λ (λ=632.8nm, RMS), and the roughness of 1.9 nm (Ra) can be achieved. The CFRP mirror presented poor dimension stability, the surface accuracy increased gradually in air. In order to solve this problem, a polymer coating was carried on mirror surface. The polymer coating exhibited better dimension stability, the surface accuracy can be maintained under 0.15 λ for more than 200 days.

A Φ450mm primary mirror subsystem of a space-based astronomy telescope was designed with mass, optical surface distortion and reflectivity requirement. The open-back primary mirror was made of pressure-less sintering silicon carbide, light-weighted at a ratio of approximately 70%. Three side supporting invar flexure bipods were designed to minimize the assembling stress and the thermal stress. The high reflection was obtained from the optical surface cementite. The mirror weighted 7kg and the reflectivity was 97% after optical polishing. The mirror subsystem was precisely assembled under the strict technical condition. The optical test with interferometer showed that the optical surface distortion is less than 1/40λ rms, which met the critical optical requirements for the primary mirror of the space-based astronomy telescope.

The 470mm lightweight primary mirror of a space telescope is made of ULE, and supported on a titanium hexapod. The hexapod consists of six bond pads, six titanium struts with flexures and three support parts. The hexapod provides a quasi-kinematic mount for the lightweight mirror, and the flexures are used to isolate optical elements from the mechanical and thermal deformations of the support structure, then the surface figure distortion of the mirror is minimized. In this paper, the finite element method is used to analyze the static and dynamic characteristics of the mirror assembly. Then, six pads are bonded to the mirror and the support hexapod is assembly. The vertical optical test of the primary mirror assembly is implemented. Vibration test of the mirror assembly is performed, and the test results are consistent with the results of the finite element analysis.

Space optical remote sensors play an important role in earth observation, space situation awareness and astronomy exploration. The optical resolution of space remote sensing system is constantly improved. Several new techniques for realizing ultra-high resolution of spatial optical remote sensors are reviewed. The research status and application prospects of these new technologies are discussed, mainly including synthetic aperture optical system, Fourier ptychography and intensity correlation imaging. The critical technical problems of these new technologies in spacebased and ground-based optical remote sensing engineering are summed up.

Synthetic aperture lidar is a new ultra-high resolution optical imaging instrument, but its reception field is very narrow which is subject to the "antenna theory". In this paper, the antenna efficiency theory is used to explain the antenna theory and the method of enlarging the field of view of the synthetic aperture laser radar. Then the increase range of the field angle of the three methods is deduced by heterodyne efficiency simulation. The simulation results show that the focal plane heterodyne detection optical path of the wide-beam local oscillator beam focal plane has the ability to improve the heterodyne efficiency of the edge field of view by reducing the heterodyne efficiency of the central field of view. The focal plane heterodyne detection optical path of the array detector requires the detector whose pixel size less than 3 times Airy spot radius covers the whole field of view, which can increase the maximum 1.83N times compared to the antenna theory. The effective field of the pupil plane heterodyne detection optical path of the array detector has nothing to do with the magnification of the telescope, the pupil diameter, the size of the detector, etc., which can be increased by N times as compared with the antenna theory.

Liquid rotating about a vertical axis takes a parabolic form, and can be used as the primary mirror in a reflecting telescope. It is a convenient way to get big primary mirror for astronomical telescope. But this kind of Newton type telescope with a parabolic surface has limited field of view, which is not capable for the detection of astronomical and orbital objects. It is necessary to design corrector lens with large field of view to improve the detection efficiency. In this paper, a prime focus corrector with a field of view of 2°, a focal length of 1.5 m, and wavelength coverage of 0.4-0.8 μm is designed for a liquid telescope with a clear aperture of 1 meter. The corrector is optimized by choosing different types of glass for achromatic design. The final corrector consists of 5 lenses and one filter, in which the largest one has a clear aperture of 280 mm and there is only one conic surface is used on a concave lens. The design result shows that 80% encircled energy is limited in one pixel, that is 12 μm for our F9000 3K×3K CCD camera, corresponding to 1.67″ resolution. The distortion is optimized to 0.01% which is very suitable for a Time Delay Integration (TDI) observation. The tolerance analysis for fabrication and assembly is also presented. Space debris and astronomical objects will be observed when the telescope is constructed.

The ply angle misalignment has a significant influence on the surface accuracy of the carbon fiber reinforced polymer (CFRP) composite mirrors after curing. In order to investigate the sensitivity of two arrangement methods of layup sequences to the form error after cure, the finite element method (FEM) was used to discuss the influence. 18 different layup sequences have been investigated: 500 models with a normal distribution of random angular alignment errors were generated for each layup sequence, and the mirror’s deformation was calculated to obtain the values of mean M and standard deviation a of the surface error after curing. The results reveal that as the number of plies increases, the curing deformation of the two arrangement methods will gradually decrease; with the same number of plies at different increment angle, the “Optimized” sequences reduce M by about 8% to 16% relative to the clockwise sequences, which reduces a by about 9% to 22%. The improvement is obvious, especially when the number of plies is no larger than 24. This shows that the regularized stiffness coefficient method (corresponding to the “Optimized” sequences) can effectively reduce the form error compared to clockwise sequences; the general trend is that the smaller the optimization target value, the smaller the deformation; this positive correlation is established with a high probability under the same number of layers and the same increment angle, or when there is a large difference between the target values. The regularized stiffness coefficient method can get the layup sequence accurately, and thus has certain theoretical basis and manufacturing advantages. It is, therefore, a layup sequences design method worthy of study.

Pupil off-axis optical system has the advantages of imaging unobscured and restraining the stray light for the next generation space telescope. However, non-rotationally asymmetric aberrations lead by the pupil off-axis structure becomes the main influencing factor of imaging quality. Since the freeform surface can provide more degrees of freedom for optical design, it is widely used to control the non-rotationally asymmetric aberrations. In order to guide designer optimize the pupil off-axis optical systems with freeform surfaces efficiently, an aberration analysis method for pupil off-axis optical system with Fringe Zernike polynomial freeform surfaces is proposed. The analysis expressions of third-order astigmatism and coma of the pupil off-axis freeform system are deduced. The freeform impacts on aberration nodal properties are analyzed. According to the aberration distribution, a pupil off-axis space telescope freeform optical system is designed by optimizing the Zernike terms pointedly. The effective focal length is 25m, the pupil diameter is 2m. By stitching multi-detectors to realize the field of view (FOV) of 1.2°×1.2°. Because of introducing freeform surfaces, the third-order astigmatism and coma nodes are both moved back to the FOV. Therefore, the asymmetric aberrations lead by pupil off-axis are balanced. The final imaging quality is closed to the diffraction limit, which meets the requirements.

In order to ensure the consistency of the images in different waveband, a common aperture ultraviolet and mid wave infrared dual band microscope is designed. Based on the analysis of the factors that affect the image consistency, the condition of the equal focal length is derived. Fitting the curve of the focal length difference changing with the wavelength, and making the focal length of the two wavebands equal by reasonable matching of the focal power, thus ensuring the good consistency of different band images.The working range of the optical system is 0.24~0.28μm and 3~5μm; the field is 0.8mm, the numerical aperture is 0.25,the focal length is 13.86mm, and the magnification is 10X. The transfer function value of UV is higher than 0.75 at the spatial frequency of 37 lp/mm, The transfer function value of MWIR is higher than 0.35 at the spatial frequency of 30lp/mm

Successful fabricating of φ4m silicon carbide (SiC) mirror blank after 20 years of research in Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP). Preparing 12 monolithic SiC green bodies with a partially closed back by lost foam and gelcasting technology, joining 12 SiC monolithic green bodies by reaction-formed technology, and densifying SiC mirror blank by reaction sintering technology. The testing results show that the performances of CIOMP-SiC could meet requirements, and the root mean square (RMS) value of φ4m CIOMP-SiC surface shape is better than λ/30 (λ=632.8nm).

The influence of adhesive bonding and curing on the accuracy of mirror surface shape was analyzed to realize low-stress assembly of large aperture mirror. Firstly, based on Hooke's law, a curing shrinkage stress equation was deduced, taking deformation of the mirror and support structure into account under the boundary condition of continuous edge bond, and key parameters effecting mirror deformation were obtained. Secondly, for a 514mm ULE spectrometer primary mirror with an inserts structure mosaiced and bonded on mirror-back, an equivalent linear expansion coefficient method was used for finite element modeling. The shrinkage stress at the bond edge of mirror and the mirror surface shape were analyzed. It’s found that adhesive shrinkage has a significant effect on the mirror surface shape. Finally, the inserts structure of mirror assembly was optimized. In contrast to the non-optimum structure, the average stress of adhesive surface caused by adhesive curing shrinkage reduced from 0.28MPa to 0.18MPa, and the mirror surface shape (Root Mean Square, RMS) reduced from 0.029λ to 0.017λ. Finite element analysis results of the mirror assembly were given at last, surface shape accuracy (RMS) of mirror is 0.012λ under a load case of 1g gravity, and the first-order natural frequency of the component is 216 Hz. The obtained results showed that a suitable optimized support structure can effectively relieve adhesive curing stress, and also satisfy the design requirements for both the static and dynamic stiffness.

Diffractive telescope has the advantages of lightweight and loose tolerance, so it can become the next generation space telescope. In order to realize no central obscuration, compact structure and large field of view (FOV), the off-axis three mirror is used as eyepiece in diffractive telescope system. According to the Schupmann’s achromatic theory, an optical design example of diffractive telescope with 0.8m aperture of objective lens, 0.46~0.54μm spectral bandwidth and 0.08° FOV is presented. By using the function of coordinate break in optical design software ZEMAX, an unobscured diffractive telescope system based on off-axis three mirror eyepiece is realized. After optimized original structure parameters, the diffractive telescope system has a good performance with 39.1m short total length. Here, at the spatial frequency of 50lp/mm, the values of modulation transfer function (MTF) within full FOV are greater than 0.574. Furthermore, the values of RMS radius are less than airy radius diameter. The optimized results clearly show that the system is achromatic and near diffraction limited imaging quality.

The Thirty Meter Telescope (TMT) project will design and build a thirty-meter diameter telescope for research in astronomy in visible and infrared wavelengths. The primary mirror of TMT is made up of 492 hexagonal mirror segments under active control. The highly segmented primary mirror will utilize edge sensors to align and stabilize the relative piston, tip, and tilt degrees of segments. The Support System Assembly (SSA) of segmented mirror utilizes a Guide Flexure to decouple the axial support and lateral support while its deformation will bring in measurement error of edge sensor. We have analyzed the theoretical relationship between the segment movement and the measurement value of edge sensor and proposed an error correction method with matrix. The correction process and the simulation results of the edge sensor will be described in this paper.

Tertiary mirror of thirty meter telescope (TMT) has the tracking and pointing capabilities, and its structure is similar to an alt-az telescope. The cradle serves a similar function to the center block of the track frame, its structure directly affects the performance of the system. M3 prototype as an example, in order to improve stiffness to weight ratio of the cradle, the mathematical model of topology optimization design of the cradle was established and the optimization was performed. Then a spliced truss structure for cradle was designed based on the result of the topology optimization. By using finite element method, the static and dynamic analysis of cradle under different conditions was done according to the working characteristics. The results showed that under the conditions of the gravity vertical along the x, y, z, the maximum deformation of cradle was 0.064mm, 0.015mm, 0.025mm respectively, and the first modal frequency is 74.4Hz. Results showed the structure designed meets the requirement.

The Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) team is developing Giant Steerable Science Mirror (GSSM) for Thirty Meter Telescope (TMT). This paper will combine PSSn to analyze the error characteristics of GSSM. To evaluate the performance of the large telescope under different kinds of error source, the normalized point source sensitivity is introduced, which is firstly studied by the group of thirty meter telescope team to balance all the deviation of the telescope and also budget the error. First and foremost, the character of the normalized point source sensitivity is studied in the very first part and the advantage in the evaluation in all the frequency domain. Then the PSSn is compared with the traditional metric, such as RMS and the multiplication property is discussed. The experienced formula is used to show the relationship between the PSSn and the error sources, static and dynamic. Lastly, the method is applied to a large aperture telescope.

Large telescopes are developing, and promoted by new technological developments. In order to study the method of mirror seeing detection for large aperture optical system, the relationship between mirror seeing and slope information is derived first. In order to evaluate the results more comprehensively, the normalized point source sensitivity was introduced to evaluate the results. Finally, according to the previous analysis, the experiment was carried out. The change normalized point source sensitivity under different conditions is calculated. By comparing with RMS of wavefront, the better statistical characteristic of sensitivity of normalized point source was verified.

Shack-Hartmann wavefront sensors calculate the position of focal spot in each sub-aperture from intensity distributions, the noises of the detector itself would have a certain impact on the detecting accuracy and would lead to inaccurate wavefront detections using conventional centroiding method. It has been demonstrated that the correlation algorithms with template matching is able to improve the accuracy. In this paper, several correlation algorithms such as absolute difference function, absolute difference function-squared, square difference function, cross-correlation function and normalized cross-correlation are compared at different signal-to-noise ratios. To further improve the accuracy, interpolation algorithms including equiangular line fitting, parabola interpolation, gauss interpolation and least square method are brought in, which turns out that least square method could minimize the detecting error. Besides, simulations within single aperture and full aperture both illustrate that cross-correlation function is most robust but needs more calculations, so is least square method. Moreover, although absolute difference function would be inaccurate at low signal-to-noise ratios, it still can obtain high detecting accuracy at high signal-to-noise ratios and it minimizes the calculations.

Warping Harness is a mechanism which can periodically correct the low order surface errors of mirror. The main correction objects are the residual error of the mirror machining, the stress distortion caused by the coating, the surface error caused by the temperature load, even with the errors caused by the gravity change, and so on. In principle, the zero moment point of the Whiffletree structure can be adjusted by changing the deflection of the warping harness blade. Due to the closed force system, once the moment induced by the warping harness changes, the load distribution on the whiffletree structure varies too. In practice, the structure of Warping Harness is installed on each group of Whiffletree joints and works with the structure of Whiffletree. The servo stepping motor is employed to control the bending of the spring blade to change the distribution of the support force, and then the correction of the main mirror surface figure is completed. This paper mainly introduces the correction principle of Warping harness and its principle, and demonstrates the preliminary design of the system.

The optical alignment of telescopes is essential to satisfy the high request of image quality. One of the most easy and efficient approaches to correct the misalignments is based on the far-field images in the focal plane by maximizing sharpness metrics. To analyze the aberrations corresponding to different fields and various working conditions of telescopes, the image segmentation becomes an indispensable process. After image segmentation, aberrations can be studied in detail. What’s more, it can also simplify the calculation. In this paper, OTSU method based on one-dimension histogram is adopted to segment the telescope images. First, images corresponding to different fields of the telescope in both designed and misaligned working conditions are simulated. Second, these images are segmented by the OTSU method to obtain a series of binary images. To verify the anti-noise capability of this method, noise images are simulated by adding Gaussian noise with different standard deviations. These noise images are also segmented by OTSU method. Then, edge checks are carried out to compare the segmentation results of noiseless images with noise images. The results indicate that for noiseless images and noise images simulated in designed working condition, the segmentation processes are accurately, while for noise images simulated in misaligned working condition, the segmentation results are influenced by noise.

The Thirty Meter Telescope (TMT) is one of the largest ground-based telescopes currently under construction in the world. Changchun Institute of Optics, Fine Mechanics and Physics(CIOMP) took the task of design and manufacture Tertiary Mirror System (M3S), which is also named Giant Steerable Science Mirror(GSSM). CIOMP decided to design and manufacture a 1/4 scaled prototype of M3S(M3SP) to verify the technical feasibility of M3S design. The tertiary mirror was support by 18 points whiffletree structure along axial direction and 12 points whiffletree structure along lateral direction. Finite Element Model was built to evaluate the system performance. Based on the Finite Element Analysis, the SlopeRMS of tertiary mirror surface figure would be 1.9 μrad when the mirror was pointed vertical under gravity, and was 0.46μrad when the mirror was pointed horizontally. By applying adjust moment on the pivot of axial whiffletree system, the surface figure SlopeRMS when mirror was pointed vertically could be improve to 0.95μrad. The support system’s resonance frequency was 53.7Hz, which indicated that the system stiffness was high enough. Mirror and structure stress level and meet the requirement of system safety.

To satisfy a space patrol telescope system with high angular resolution, large space area and high stray light suppression, the stray light environmental characteristics at low earth orbit are summarized. In accordance with the parameters, which diameter is 1.5m, focal length is 20m, field of view is 1.1°×1°, and the optical and mechanical structure joint-design stray light suppression is compared and analyzed for on-axis cross type, off-axis back end type and off-axis sideway type. A method of optical and mechanical structure joint-design stray light suppression is proposed to reduce the stray light suppressing angle to enhance the efficiency of the observation time and sky patrol efficiency in orbit. The detailed stray light suppression design and optimization of off-axis sideway type is given. The simulation and analysis of total optical and mechanical periodic line is presented, and the major stray ray path is simulated and analyzed.Compared with the other two types, the off-axis sideway type presents the best performance of image quality and stray light suppression. The modulation transfer functions (MTF) approach the diffraction limit at all fields. When the evadable angle out of the field is 40°, the PST is less than 10^-11 and the system can approach to the stray light suppression limitation.

Detection and recognition of space objects with ground-based photoelectric systems is one of the major technical ways for space situational awareness. During the past thirty years, there has been significant development of optical telescopes dedicated to wide-field surveys of time-dependent deep space phenomena, slow-moving near-earth objects (NEOs) and fast-moving earth-orbiting space debris. While telescope fields of view have gradually increased, a single technical approach has not emerged as the dominant design. To design an effective wide-field telescope for sky survey or space surveillance, It is necessary to carefully match the characteristics of the optical system (layout, aperture, focal ratio and modulation transfer function) with those of the observing site (sky brightness, transparency, seeing and elevation), the detector (pixel pitch, quantum efficiency, read rate and read noise), and the observing program (target brightness, target motion, observing strategy and feature extraction software). In this paper, we design a telescope with wide field of view (≥2.5°×3.5°) and large aperture (1.1m). The focal length of the system is 1.5m, F/# is 1.36. Because of the small Fnumber and wide field of view, we choose the prime focus corrector structure which has single mirrors with refractive prime focus correctors. Moreover, the especial requirements of the Modulation Transfer Function (MTF), spot, energy concentration, and distortion etc. are all satisfied.

The manufacturing and testing of a surface modified silicon carbide mirror with a bowl-shaped structure was introduced. The entire process flow includes pre-modification silicon carbide substrate processing, silicon carbide substrate surface modification, and silicon modified layer processing. Firstly, before the modification, the conventional processing method of silicon carbide was used, and the effect of the support form on the figure was eliminated by multiple direction rotation testing.At the same time, the self-aligned compensation cross-test was completed and the accuracy of the aspherical surface coefficient was verified. In addition, the polishing process of the silicon modified layer material was studied, and the optimum process parameters suitable for polishing the silicon modified layer material were found out. Based on the above experiments, the modified optical processing adopts a combination of two kinds of polishing technology: flexible chemical mechanical polishing (FCMP)and ion beam figuring (IBF).The surface roughness and surface finish of silicon modified layer are improved by flexible chemical mechanical polishing technology. The high figure accuracy of silicon modified layer is achieved finally by ion beam figuring technology. Finally, the final result of the mirror after IBF is:the RMS values of the figure and roughness in the Φ450 mm aperture is 0.01λ (λ=632.8 nm) and 0.52 nm. The mirror's processing results fully meet the design specifications.

Wavefront matching, i.e. phase control of an arbitrary input wavefront (IW) to produce target output wavefront (OW), can be realized using an optical freeform surface (OFS). The accuracy of wavefront matching is dependent on the discrete sampling data of OFS, categorized as feature point coordinates and surface slopes, especially for surface generation with modal Zernike method. To find out the optimum sampling data type, first we propose an exact ray mapping process ruled by Snell’ law and the constancy of optical path length from IW to OW to derive the feature point coordinates and surface slopes of OFS simultaneously. Then, wavefront error is numerically calculated by ray tracing for OFS generated from different sampling data types to demonstrate the effectiveness and accuracy of wavefront matching. We find that OFS generation method based on feature point coordinates has superior performance in wavefront matching than that based on surface slops under the condition of high density sampling of IW regardless of complexity of IW. Additionally, in the case of complex IW, the accuracy of wavefront matching benefits from heavy weight of low-order aberrations especially defocus and astigmatism in IW.

To improve the reflecting properties of all CFRP mirror, a high reflecting coating must be prepared on the mirror surface. In this paper, the effect of the roughness, film material and the deposition temperature on the reflecting rate was discussed. In the experiments, it was observed that the film exhibited higher reflecting rate on the smoother surface; meanwhile, the deposition rate must be controlled below the soften point of the surface replicated resin; if not, pits will generate on the surface and reduce reflecting rate. Ag film system exhibited higher reflecting rate than Al films. Finally, a multilayer film Ag and SiO₂ was deposited on CFRP mirror, with a reflecting rate over 95% between 450nm and 800 nm.

Based on the wavefront aberration theory and the coordinates transform, the free form optical induced aberration’s characteristic of optical system has been analyses in this paper. The optical wavefront error and the free form surface can be express as Fringe Zernike polynomial; the free form optical on the surface (Stop or Entrance pupil or Exit pupil) affects all the field angles equally. If the surface is not the pupil of optical system, the aberration observed is different from the free form itself because the footprint of the beam for an off-axis field point only covers part of the surface. For the Fringe Zernike surface figure on a surface not at pupil, it will transform into lower order Fringe Zernike aberration in the optical system, the relationship between different Fringe Zernike aberration and field is different, and the location zero for the lower aberration always reside at the center of the field of view.

In order to obtain a wider imaging field of view, freeform surface is used to design a large field of view space optical imaging system. The system uses an off-axis three-mirror optical structure with focal length of 1600 mm, F number of 8, and field of view angle of 20°×1°. Because of the large field of view, the image quality of general aspheric optimization design system cannot meet the requirements. In order to improve the freedom of system design, the Zernike polynomial freeform surface is applied to the tertiary mirror of the system, which enables the sagittal field of view to reach 20° further widening the imaging field of view. Degrees of freedom are increased effectively by the addition of the freeform surface. After optimization design, the optical transfer function of the system is better than 0.5 at 63 lp/mm, and the diffusion spot is optimized into Airy circle. The system energy concentration is high, and the imaging quality is close to the diffraction limitation.

High resolution, wild field of view (FOV) and high image quality are required in space and airborne remote sensing and space photography. However, the refraction system must use special materials or complex structures to eliminate the secondary spectrum, the two-mirror system possesses limited degrees of freedom in correcting aberrations, and the coaxial system has serious central shielding problem in the case of wild FOV. According to geometry optical theory and primary aberration theory, an off-axis three-mirror (TMA)system with long focal length and wide FOV was designed based on the coaxial three-mirror systems. The spectral range is visible light range, the focal length is 5000mm, the FOV is 10°, and the relative aperture is 1:12. The primary mirror and the third mirror are aspheric surfaces while the second mirror is quadratic surface. In this system, the central shielding problem is solved and the modulation transform function (MTF) is more than 0.6 at Nyquist spatial frequency 50lp/mm which is close to the diffraction limitation. Moreover, the full field diffusion plaque is controlled into 5μm. In all, the analysis results show that the image quality and each specification of the off-axis three-mirror system satisfy the application requirements.

Edge-trimming experiment of a reflective mirror is carried on in the paper to study the influence of edge-trimming on the surface figure of a reflective mirror. First, the influences of both self-gravity and the supporting method in measuring on the surface figure of the same mirror before and after edge-trimming are simulated. The simulation results show that both self-gravity and the supporting method in measuring have little influence on the surface figure. Second, the real surface figure of the mirror before edge-trimming is calibrated. Third, edge-trimming experiment of the mirror is carried on the ultrasonic grinding machine. Forth, the real surface figure of the mirror with the same effective aperture after edge-trimming is calibrated. The measuring results show that the surface figure of the mirror after edge-trimming is changed greatly in comparison of that of the mirror before edge-trimming: the surface figure of the mirror before edge-trimming is that the root-mean-square value (RMS value) is about λ/40 (λ=632.8nm), while the RMS value of the surface figure of the mirror after edge-trimming is about λ/15. At last, the mirror is polished again. The final RMS value of the surface figure of the mirror is about λ/40. The experimental results show that edge-trimming can bring stress to the mirror. Therefore, edge-trimming influences the surface figure of the mirror considerably. The consequent polishing experiment can erase the influence. The experiment shows that edge-trimming can be carried on with the reflective mirror with lower surface precision. The whole experiment will provide some helpful reference on the choice of edge-trimming occasion of the reflective mirror if it is necessary.

With the excellent optical performance especially some aspherical surfaces enhanced, aluminum alloy mirrors are widely used in many optical systems. The technique of Single-point diamond turning (SPDT) applied in the IR optical application directly. However, it is difficult to obtain higher precision for some complex mirrors and the remaining periodic diamond turning structure can cause scatter losses for shorter wavelengths. Hence, additional polishing steps are necessary. In this paper, a process chain contains SPDT and Magnetorheological finishing (MRF), is put forward for machining an aluminum alloy cylindrical mirror. A high accurate measurement setup, composed of an interferometer and an advanced Computer generated hologram (CGH) is built, and the data distortion is analyzed and corrected. Additionally, normal positioning error caused by tool setting is analyzed and simulated, and a workpiece self-localization system in MRF is used to control the error. The experimental result shows that the surface texture converges to PV 0.233λ (λ=632.8nm, 90% aperture), rms 0.040λ (90% aperture). It is concluded that the form accuracy of the aluminum alloy cylindrical mirror is improved by the process chain, moreover, the process chain is the reference for the fabrication of aluminum alloy mirrors with complex surfaces.

Full-disc vector magnetograph (FMG) is one of the main loads in the Advanced Space-based Solar Observatory. FMG is used to realize scientific goals of observing full-disk vector magnetic field with center wavelength of 532.4 nm. The optical system of FMG consists of polarized optical system and imaging optical system, and the imaging optical system composes of the front window and telescope system. The front window has the capability for providing proper situation for scientific observation by absorbing high energy of solar irradiance coming from space while reflecting wavelength of non-scientific investigation beyond wavelength of 532.4±5 nm. The study analyzed the influence of complex space environment on optical glasses. As a result, the material of fused silica, while two pieces of flat glass parallel with 3mm separation structure and thickness of 15mm are determined. Finally, the results show that design for the front window meet the required specifications.

In order to meet the requirements of high imaging quality and high resolution for high magnification continuous zoom TV, the main factors affecting the imaging quality are analyzed. The effects of eccentricity on the MTF of the optical system were analyzed by CODE V optical software. According to the analysis results, the lenses of the former group are most sensitive to the optical system and have the greatest influence on the image quality of the system. The tolerance value of the center deviation control of the lens is determined. Aiming at each lens of the front mirror group, a centering structure of the micro stress adhesive lens is proposed. The center error control method of lens is realized by optical axis calibration technology. As the moving component of the system, the zoom lens group and the compensation lens group are the key factors affecting the system image quality during the zooming process. It is proposed that the mechanical centering method is used to make the axis of motion consistent with the axis of the front mirror group. Then, The optical axes of the zoom group, compensation mirror group, rear mirror group, and front mirror group are consistent by a reflective optical centering method. By comparing the test results with the theory, the accuracy and feasibility of the center deviation control method are verified, and the design requirements of the system are satisfied.

With the development of optical machining and testing, the gap between freeform surface fabrication and design has been filled. Based on the freeform surfaces’ extraordinary feature for balancing asymmetric aberration and compressing system volume, an volume-compression optical design method for off-axis, three-mirror system is presented. Based on the guide of Nodal Aberration Theory for balancing asymmetric aberration, some optimization rules and tricks are shared during the optimization process. In the end, a highly-compact optical system with wide field of view, large entrance pupil and small F number is shown, the image quality is close to diffraction limit at Nyquist frequency.

The fully continuous spiral phase plate (SPP) can produce high quality vortex beams, which has important application value in the field of high-power lasers. For the stitching test of large aperture SPP with large gradient characteristics, the error factors that affect the accuracy of stitching are analyzed, and the corresponding error correction methods are proposed. On the basis, the stitching test of 235 mm×175 mm aperture SPP is achieved. Multiple test results indicate that the RMS repeatability of stitching is up to 0.0016 λ and the RMS accuracy can reach 4.52 nm.

This article introduces the modification of single crystal silicon cylindrical mirror that combined immersed CCOS polishing with IBF polishing. In the processing of smoothing and modifying, the quality of the mirror’s surface has been further improved. In this experiment, we optimize the CCOS polishing process and improve the traditional CCOS polishing apparatus to polish the single crystal silicon convex cylindrical mirror. During the CCOS polishing process, the parameter were set as follows: pressure 0.4kPa, speed 25 r/min, polishing liquid concentration 4.5% (pH 10), polishing time 20 min. After polishing by CCOS, IBF is used on its heels. The parameter were set as follows: energy 1000-1200eV (Ar⁺ ion beam with low energy), incident angle of ion beam 90°, polishing time 30 min. The immersed CCOS polishing process and IBF polishing process iterated repeatedly until the surface quality of the single crystal silicon convex cylindrical mirror meets the requirement. After the polishing process, the sub aperture stitching method and Zygo interferometer are used to detect the surface. The PV value of the single crystal silicon convex cylindrical mirror is 0.265 lambda, the roughness is 0.679nm the residual Zernike is 70.5 nm after testing. The errors over the whole frequency band were significantly reduced. It could be seen from the above that the single crystal silicon convex cylindrical mirror had high accuracy and better profile on the surface after polishing process. The error over the whole frequency band also converged obviously. Therefore, the method that had been described in this paper could be used for the surface modification of single crystal silicon cylindrical mirror.

An centering alignment technique of collimation lens group based on the optical axis of primary mirror is introduced in this paper, so as to meet up with the deviation requirements in the assembly of high-quality Common Path Optical system. A non-aberration system is designed in the first place in order to analyse the conjunction between the Wave-front aberration and eccentric error,then construct the simulation model of cassegrain system and collimation lens group based on test result,formed the eccentric error mapping relationship between the two variables. The collimation lens group is then assembied and aligned on the basis of the axis of the aspheric primary mirror. The technique has been verified through both simulative tests and actual measurements, and the results suggest the eccentric error is less than 0.04mm, and the Common Path Optical system Wave-front aberration RMS less than 0.03um.

During the course of super smooth surface processing, grinding procedure is a very important link, for one thing the subsurface damage induced by cutting can be removed, for another its quality determines the subsurface damage depth of the mirror which influences some important index such as strength, stability, coating quality and so on. Therefore, the accurate measurement of subsurface damage depth is the prerequisite to ensure the removal amount in the subsequent processing and make sure that the subsurface damage is removed completely. In this paper, based on fused silica mirror as the experimental object, free abrasives of W28 size are used to grind the mirror blank, then two destructive measurement methods are adopted respectively. The result shows that, comparing with angle polishing method, differential chemical etching method could describe the subsurface damage depth accurately.

Laser communication terminal is the key point of the satellite laser communication system. In order to improve the pointing and tracking efficiency, an afocal off-axis optical system was designed for laser communication Terminal. So the precise alignment an afocal mirror telescope of all-reflective off-axis optical system is great significance. In this paper, computer-aided alignment methods utilizing Zernike polynomial coefficients have been developed for an afocal mirror telescope. The misalignment state is simulated in CODEV and computer-aided alignment software. The relation of component deflexion and the place of exit pupil have been simulated by computer model reverse optimization. At a wavelength of 632.8nm, the main characteristics are a WFE of ≤0.035nm. These results show that it can meet the precision requirement and accelerate the convergence of misalignment variables. Ultimately, the image quality and precision of exit pupil was effective operated according to the request of satellite laser communication system.

Electroless nickel is an excellent material for making optical molding dies, because of its machinability with both single-point diamond turning and polishing, as well as its suitable hardness and durability. This paper deals with the ultra-precision polishing of molding dies for telescope mirrors with a super smooth surface with a roughness below 1 nm root-mean- square (rms). According to the probability density distribution function of different sizes of abrasive grains cut into the workpiece, a surface roughness model combining the micro contact model and the force balance principle was established. A surface roughness of 0.316 nm Ra was obtained on slab molding dies of 30 mm in diameter.

Variable curvature mirror (VCM) is a long-history technique used to correct the defocus and spherical aberrations caused by thermal lens effect in solid-state laser. In recent years, the probability of VCM in realizing non-moving element optical zoom imaging has been paid much attention and how to generate a large enough saggitus variation while still maintaining good enough surface figure accuracy is the research hot topic. In this manuscript, two kinds of VCM has been studied and the advantages of pressurization actuation based VCM having variable mirror thickness has been confirmed. Compared with the traditional annular force actuation based VCM with constant mirror thickness, the pressurization actuation based one having variable mirror thickness is capable of providing a saggitus variation of larger than 35um and still maintaining its surface figure accuracy superior to 1/10λ(λ=632.8nm). Besides that, it is found that spherical aberration plays a main role in leading to the degradation of surface figure accuracy and the surface figure accuracy at extreme curvature could be improved to about 1/40λ(λ=632.8nm) by only removing spherical aberration. Therefore, when applying pressurization actuation based VCM to realize non-moving element optical zooming, the wavefront sensing and subsequent digital correction to eliminate the spherical aberration will become a necessary step.