Spatial heterodyne spectroscopy for long-wave infrared identifies an ozone line near 1133 cm-1 (about 8.8 μm) as a suitable target line, the Doppler shifts of which are used to retrieve stratosphere wind and ozone concentration. The basic principle of Spatial Heterodyne Spectroscopy (SHS) is elaborated. Theoretical analyses for the optical parameters of spatial heterodyne spectroscopy are deduced. The optical system is designed to work at 160 K and to maximize the field of view (FOV). The optical design and simulation is carried on to fulfill the requirement. The principle prototype was built and a frequency-stable laser was used to conduct the experiment. Result shows that the designed interferometer can meet the requirement of spectral resolution (0.1 cm-1 ) and that the spatial frequency of fringe pattern is consistent with the theoretical value at normal temperature and pressure.
As a new type of wind field detection technology, Doppler Asymmetric Spatial Heterodyne（DASH）can invert information such as atmospheric wind speed by monitoring the Doppler frequency shift of the absorption line or emission line of the atmospheric composition. It is widely used in the detection of middle and upper atmospheric wind fields. In this paper, a flexible support structure suitable for DASH interferometer is designed, so that the bonding process between different materials has a high safety margin in environmental testing. After modal analysis and random vibration analysis of the whole structure, the results show that the design meets the requirements. First, the fundamental frequency of the interferometer (765.79Hz>100Hz) meets the requirements of general satellites for the load; secondly, the random vibration analysis results show that the bonding stress between the surfaces is less than the allowable stress of the material (2MPa<14MPa), and it has a certain safety margin (>2); finally, the optical parts and structural parts did not collide with the structural parts during the vibration process, and the flexible structure did not undergo plastic deformation, and the whole structure of the interferometer was safe and reliable
In order to solve the image rotation in Sagnac transverse shearing interferometer, a model system is built on ray vector tracing and rotation matrix theory, as well as the theoretical imaging orientation and the actual imaging orientation with the angle error are demonstrated. Besides, the relation between the angle error and the rotation of the image body is concluded, which provides a theoretical guidance for optical alignment in Sagnac transverse shearing interferometer. Finally, an optimized optical alignment scheme is provided by the discussion of the angle error in the assembly and system-level loading process, which is also validated by optical alignment instance.
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.