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Due to its wide wavelength coverage, multi-resolution mode, and high transmission efficiency, the wide field multi-object spectrograph becomes the most common-used universal instrument in extremely large telescopes. It's still a great challenge to build the wide field multi-object spectrograph for a 30 m class telescope because of its sharply increased volume and budget. With the rapid development of astronomy and astrophysics, the innovation of astronomical technology is fundamentally required. In this paper, the research progress of different kinds of wide-field multi-object spectrographs is illustrated and reviewed, the recent status of conceptual designs and the instrument features of the wide field multi-object spectrographs of the three 30 m class telescopes in the world, especially the current effort made by the Chinese team for the wide field multi-object spectrograph of the Thirty Meter Telescope (TMT) are introduced.

The magnetic field computation and performance characteristics analysis for a novel transverse flux permanent-magnet linear motor with the concentrated flux mover have been discussed. The following issues have been emphasized as: the construction of the transverse flux linear motor, magnetic flux distribution, winding flux linkage, and thrust force characteristic. The force ripple coefficient is theoretically derived from the mechanism of production of a force ripple, i.e., improving the waveform of back-EMF. The influence of structure parameters on the thrust force and cogging force characteristics is analyzed in detail. A special attention is paid to the pole pitch ratio between stator and mover, the ratio between slot width and pole pitch of stator. Finally, a prototype of transverse flux permanent magnet linear motor has been developed.

A new type of multi-microporous stainless steel plate has been developed, and it has a lot of interconnected micropores on its surface and inside. The test results show that the pore size ranges from 0.1 to 15 μm and has regular shape. It is found that the plate has good air permeability by gas permeation test. The porous aerostatic thrust bearing is prepared by using this material, and the test results show that the bearing has high static bearing capacity. In FLUENT, the static characteristics of the porous gas hydrostatic bearing are simulated, and the simulation result is highly consistent with the experimental data, which verifies the correctness of the simulation and provides convenience for the study of the static characteristics of the porous gas hydrostatic bearing. The multi-microporous stainless steel plate can be used in ultra-high speed and ultra-precision instruments such as air lubricated motorized spindle and air bearing guide rail.

The optical design softwares ZEMAX and Python were used to realize the precision solution of optical path difference (OPD) for spatial gravitational wave telescope.The dynamic data exchange(DDE) closed-loop communication between ZEMAX and Python was realized. First, the Python software processed the data of telescope mirror after the finite element analysis, and transmitted the analysis results to the ZEMAX with DDE for tracing ray.Secondly, the ZEMAX software transferred the ray coordinate value to the Python software through the DDE. Lastly, the Python software calculated the OPD and wavefront changes caused by rigid body translation through the global coordinate system. Through simulating the deformation of the gravitational wave telescope with the temperature change of 1 mK, the OPD and wavefront variation of the spatial gravitational wave telescope was solved by means of ZEMAX software and Python software. The results show that the OPD precision reaches the order of 1e-13 meter, which can satisfy the requirements of telescope for pico-level stability.It is concluded that the method is feasible to calculate the OPD, and it provides a technical reference for the OPD analysis for the further mechanism design of the gravitational wave telescope.

This study proposes a new method to design and implement the baseline of a geosynchronous Earth orbit synthetic aperture radar (Geo-SAR) tomography system. Due to the satellite's orbital property, its ideal revisit cycle is 1 day, and it could be changed through raising or lowering the orbital height. As a result, the local ascending node longitude would move because of the orbital shifting, and all the passes' trajectories are nearly parallel. A baseline designing and implementation approach is advanced according to this characteristic. The cell array configuration and baseline length are illustrated by considering the demand of cross-range resolution and ambiguity. This study analyses and simulates the Geo-SAR tomography system baseline properties. Furthermore, a series of parallel trajectories are implemented by controlling orbital altitude as demanding during each cycle. A simulation experiment is performed to verify the efficiency and superiority of this approach, and the results show that it has a good effect on an L-band mode Geo-SAR tomography system with three-dimensional resolution ∼10 m.

The structure and supporting components of the primary mirror system of space gravitational wave telescope were designed and optimized. The side three-point support was used to restrain the mirror body with the primary mirror, and the selection and layout of support points were studied. The mirror adopted a semi-enclosed structure with back drill holes, which can achieve large bending stiffness. The lightweight structure of the mirror was optimized by finite element calculation combined with multi-objective genetic algorithm. The lightweight ratio of the mirror structure reached 74% without reducing the surface accuracy. An adjustable bi-axis bipod flexure hinge structure composed of two non-barrier series flexibility elements was designed, which can compensate the surface error of the mirror. The mathematical model of the flexible hinge parallel mechanism acting on the mirror was established, and the parameters were analyzed based on MATLAB. The parameters were corrected by finite element method. Finally, the analysis of mirror shape under space thermal load was carried out. The results show that the error of mirror shape is better than λ/60, which meets the design requirements.

The non-redundant aperture masking techniques transforms telescope into a Fizeau interferometer by a simple action of placing an aperture mask over the pupil, the limited resolution set by atmospheric fluctuations can be overcome by closure phase techniques to obtain diffraction-limited images. For binary stars, the closure phases can not only eliminate the influence of atmospheric fluctuations on ground-based optical telescope, but also have a functional relationship with contrast and angular separation of binary stars. In this paper, basing on the mathematical model of non-redundant aperture masking detecting binary stars, we carry out the computer simulation and laboratory experiment by using the Golay-6 mask.

The design and performance of a three-channel image and long-slit spectrograph for the new 4-m telescope in China are described. The direct imaging covers a 3 arcmin by 3 arcmin field of view and a large wavelength range 370-1,600 nm, it has two optical channels and one near infrared channel with different filters. The spectrograph with a long slit is to provide two observing modes including the following spectral resolutions: R1000 and R5000. For dispersing optical elements it use volume-phased holographic grisms (VPHG) at each of the spectroscopic modes to simplify the camera system. The low resolution mode (R1000) is provided by consecutive observations with the spectral ranges: 360-860 nm, however it adopts only one VPHG for the first light. The spectral range of medium resolution mode (R5000) is 460- 750nm, it is constrained with the use of a 4k × 4k CCD detector of 15 μm pixel size. Peak efficient in the spectrograph are achieved to be higher than 50% in different resolution mode.

The Next Generation Palomar Spectrograph (NGPS) is designed for Cassergrain focus of the Hale 200-inch telescope to replace the old Palomar Double Spectrograph (DBSP). NGPS have higher throughput, efficiency and realities spectrograph. NGPS is designed as three channels to cover the wavelength from 365nm to 1050nm with no spectral gap and delivers a resolving power with a 1.5” slit exceeding R=1800 overall the observable range. The peak efficiency of the whole throughput (from sky to detector) at the wavelength is 35.3% which is consistent with throughput achieved by some of the world’s most efficient spectrographs.

The transverse flux permanent magnet linear motor is different from the traditional motor in the magnetic circuit structure. It can increase force density in a certain range by increasing the magnetic energy change rate as a result of decoupling between the electric load and the magnetic load. The paper proposes a novel transverse flux permanent magnet linear motor with the concentrated flux of three side wall in the mover which has the characteristics of high force density and strong fault tolerance operation. The force ripple coefficient is derived by theatrically derived from the mechanism of production of force ripple, i.e. improving the waveform of back-EMF. The influence of structure parameters on the thrust force and cogging force characteristics is analyzed in detail. Special attention is paid to the pole pitch ratio between stator and mover, the ratio between slot width and pole pitch of stator. The changing rule of basic electromagnetic force with current was revealed at last. The analysis results provide a foundation for the optimum design of vertical lift system.

Design a best light-weighting collimator to conform to the requirements of opto-mechanical design. Good surface accuracy is our aim, based on a less mass. The ratio of diameter to thickness, the type ,size and thickness of pocket, the thickness of the mirror, the support size and position, the thickness of the wall and so on is concerned. Besides, comparing two kinds material is also discussed. In addition, we consider the situation that the orientation vary in support plane. Use the orthogonal table to analyze these elements, and find the better methods. According to the analysis in ANSYS, the collimator mass can reduce to 103 kg, below 159 kg; the ratio of light-weight can reach 70%; the peak-valley value is below 100 nm, that meets the request of below 200 nm.