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 LAMOST completed its first five years of operation in June 2017, and 9 million low resolution spectra are obtained. The spectrographs have been upgraded in 2017, and the resolution can reach up to 7500(with 2/3 slit). In the midresolution mode, the wavelength can cover 495nm-535nm(blue band) and 630nm-680nm(red band). The LAMOST will carry out the middle resolution spectroscopic survey in September 2018, and 3 million middle resolution spectra will be obtained. This paper describes the requirements, optical design and mechanical design of the LAMOST-MRS (the LAMOST middle resolution spectrograph)
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.