The acquisition of hyperspectral image dataset of the earth from space with high accuracy of spectrum and radiation is the objective that a number of space missions dedicate to, which is critical to studying and quantifying aquatic environments, wildfires, coastal ecosystem, and atmospheric composition. In this paper, a hyperspectral imager in geostationary orbit ranging from ultraviolet to longwave infrared is proposed. Geostationary perspective has the capability to provide high temporal, spatial, and spectral resolution measurements. The optical system employed in the proposal is composed of an ultra-large aperture afocal system, three telescope subsystems, and five spectral channels with area array image detectors. The key parameters of the system are identified through analyzing and optimizing of system architecture and specification.
Diffractive membrane imaging can be widely used in infrared band due to its longer minimum linewidth and loose requirement of RMS to fabricate more easily and reduce production period and manufacturing cost than used in visible band. A deployable infrared diffractive membrane imaging system was designed, consisting of Φ200mm imaging aperture (actual aperture is Φ500mm) and deployable structure that supports the infrared membrane under tension. Its spectral band width is >1.2μm, field of view is >1°, and diffractive efficiency can be >60%. Stowed size is 150mm×150mm×400mm. Research result of this project can promote the application of diffractive membrane imaging in infrared band and provide an effective and feasible means for achieving extremely large optical primary mirror from compact, lightweight payload.
Diffractive optical imaging is a new method to realize high-resolution imaging from geostationary orbit(GEO). Technical advantages of diffractive optical imaging is analyzed in the field of space optics. For application of super large diameter space optical system, the system scheme and a new achromatic method is proposed. An imaging system is developed and tested, the result of optical system wavefront is 0.169λ(RMS), optical system MTF is 0.85, and the imaging system MTF is 0.19. Test results show the new achromatic method is feasible. The above conclusions have reference significance for the development of super large diameter diffractive optical imaging system.
Transmissive diffractive membrane optic can be used in space optical telescope to reduce the size and mass of imaging system. Based on the international research results about transmissive diffractive membrane, a 4-level diffractive substrate with 100mm apertures was designed and transmissive diffractive membrane was fabricated by spin coating. High-precision support structure for diffractive membrane with surface precision 0.12λ RMS (λ=632.8nm) was introduced, and that can meet the diffractive imaging requirements. Diffraction efficiency of the diffractive membrane supported by support structure was tested, and the test results showed that diffraction efficiency was >50%. The step figure test results illustrated the etched deep precision was less the 10nm. The imaging wavefront test result demonstrated a wavefront error of about 38 nm RMS. The transmissive diffractive membrane optic can be very useful for large aperture imaging system to realize low mass and low cost.
Solar blind UV detecting system has many advantages such as strong environmental adaptability, low error rate, small volume and without refrigeration. To in-depth develop UV solar blind detection system research work has important significance for further improving solar blind UV detection technology. The working principle of solar blind UV detection system and the basic components were introduced firstly, and then the key technology of solar blind UV detection system was deeply analyzed. Finally, large coverage solar blind UV optical imaging system was designed according to the actual demand for greater coverage of the solar blind UV detection system. The result shows that the system has good imaging quality, simple and compact structure. This system can be used in various types of solar blind UV detection system, and is of high application value.
Squeezed light is an important non-classical light field. In this paper, we demonstrated a designed active imaging system
which use squeezed state light instead of coherent light as light source. The squeezed state light is generated by utilizing
the degenerate optical parametric amplifier based on periodically poled KTiOPO4 crystal. In order to obtain better
imaging results, microlens arrays are used for homogenizing the squeezed light. We describe experiment setup and
present some design result.