Wavefront coding is a technology which combination of the optical design and digital image processing. By inserting a phase mask closed to the pupil plane of the optical system，the wavefront of the system is re-modulated. And the depth of focus is extended consequently. In reality the idea is same as the athermalization theory of infrared optical system. In this paper, an uncooled infrared dual field optical system with effective focal as 38mm/19mm, F number as 1.2 of both focal length, operating wavelength varying from 8μm to 12μm was designed. A cubic phase mask was used at the pupil plane to re-modulate the wavefront. Then the performance of the infrared system was simulated with CODEV as the environment temperature varying from -40℃ to 60℃. MTF curve of the optical system with phase mask are compared with the outcome before using phase mask. The result show that wavefront coding technology can make the system not sensitive to thermal defocus, and then realize the athermal design of the infrared optical system.
As a high-resolution imaging instrument, angular resolution is the most important index of Lyman-α ultraviolet telescope. In this paper a new allocation and budget method is introduced. An resolution error allocation of surface roughness, figure error and alignment error was developed early in the program. And the allocation was used to guide the design. Though testing the surface roughness and figure error in visible light, the variation of diffraction encircled energy can be obtained by non-sequence model and Zernike coefficients brought into optical design software. The numerical results show that the effective RMS surface roughness of primary and secondary mirrors are 0.49nm and 0.40nm in the spatial frequency from 1/D (D is the diameter of the mirror) to 1/λ (λ is an incident wavelength). And the effects of the surface roughness are both less than 0.1″. The figure error of the primary and secondary mirrors are 0.009λ and 0.007λ (Λλ=632.8nm). The resolution errors which were brought by the figure error are 0.33″ and 0.16″. Then the effect of alignment error on angular resolution was gotten by testing visual resolution. Finally the angular resolution in ultraviolet band can be calculated. The focal length of Lyman-α ultraviolet telescope is 2000mm and the pixel size of detector is 14μm. So the pixel resolution is 1.4″. Experimental results show that the angular resolution of Lyman-α ultraviolet telescope is 0.59″, which is approached to the estimate and meet the requirement.
As key components of the optical system of the space optical remote sensor, Space mirrors’ surface accuracy had a direct impact that couldn’t be ignored of the imaging quality of the remote sensor. In the future, large-diameter mirror would become an important trend in the development of space optical technology. However, a sharp increase in the mirror diameter would cause the deformation of the mirror and increase the thermal deformation caused by temperature variations. A reasonable lightweight structure designed to ensure the optical performance of the system to meet the requirements was required. As a new type of lightweight approach, topology optimization technology was an important direction of the current space optical remote sensing technology research. The lightweight design of rectangular mirror was studied. the variable density method of topology optimization was used. The mirror type precision of the mirror assemblies was obtained in different conditions. PV value was less than λ/10 and RMS value was less than λ/50(λ = 632.8nm). The results show that the entire The mirror assemblies can achieve a sufficiently high static rigidity, dynamic stiffness and thermal stability and has the capability of sufficient resistance to external environmental interference . Key words: topology optimization, space mirror, lightweight, space optical remote sensor
In order to improve high-speed laser space optical communications terminal receive energy and emission energy, meet the demand of mini-type and light-type for space-based bear platform, based on multiple-reflect coaxial optical receiving antenna structure, while considering the installation difficulty, a high-efficient optical system had been designed, which aperture is off-axial, both signal-receiving sub-optical system and emission sub-optical system share a same primary optical path. By the separating light lens behind the primary optical path, the received light with little energy will be filtered and shaped and then transmitted to each detector, at the same time, by the coupling element, the high-power laser will be coupling into optical antenna, and then emitted to outside. Applied the power-detected optical system evaluate principle, the optimized off-axial optical system's efficiency had been compared with the coaxial optical system. While, analyzed the Gauss beam energy distribution by numerical theory, discussed that whether off-axis optical system can be an emission terminal, verify the feasibility of the theory of the design of the system.
In space reflective optical system, the back-point support is one of the widely used support means. For back-point support method, the support points position are important for the deformation of the reflective surface, find the best support points position of the mirror is particularly important. A new technique of mass allocation was discovered by using the theory of circular plate in this paper, and then the mass allocation method was used to look for the locations of the back support points on a single ring for a circular mirror having a central hole (primary mirror of Cassegrain telescope）. Then the Ansys software was used to calculate the deformation of the reflective surface when the mirror supported under different radius. It was validated that the mirror surface deformation is minimized due to gravity when supported in these positions which confirmed by mass allocation. It was proved that mass allocation is a simple and effective way to find the optimum support location of back-point support.
Solar Polar ORbit Telescope (SPORT) was originally proposed in 2004 by the National Space Science Center, Chinese
Academy of Sciences, which is currently being under background engineering study phase in China. SPORT will carry a
suite of remote-sensing and in-situ instruments to observe coronal mass ejections (CMEs), solar high-latitude magnetism,
and the fast solar wind from a polar orbit around the Sun. The Lyman-alpha Imager (LMI) is one of the key remotesensing
instruments onboard SPORT with 45arcmin FOV, 2000mm effective focal length and 1.4arcsec/pixel spatial
resolution . The size of LMI is φ150×1000mm, and the weight is less than10kg, including the 7kg telescope tube and 3kg
electronic box. There are three 121.6nm filters used in the LMI optical path, so the 98% spectral purity image of
121.6nm can be achieved. The 121.6nm solar Lyman-alpha line is produced in the chromosphere and very sensitive to
plasma temperature, plasma velocity and magnetism variation in the chromosphere. Solar Lyman-alpha disk image is an
ideal tracker for corona magnetism variation.
We present the Fringe Zernike coefficients of the parent system pupil can be converted into coefficients of off-axis system, it is show that the coefficients of the Fringe Zernike polynomials in the off-axis pupil only contain orders equal to or lower than the Fringe Zernike polynomials originally placed on the parent pupil, and for the 3rd aberration the pupil transformation matrix has been finding. Using nodal aberration, we get the misaligned matrix of rotational symmetry parent optical system. Then with the pupil transformation matrix, the misaligned matrix of off-axis two-mirror system was found, the amounts of the misalignments are calculated by the off-axis misaligned matrix.