In order to accomplish the software definition micro-nano satellite demands, which includes that its payload functions and parameters could be reconstructive and controllable by uploading software as needs, we have to break through the design limitations between traditional satellite platform and ordinary optical camera, one new type of optical imaging camera technology is developed based on software definition micro-nano satellite here. we gave full consideration to the possible development joint designing space between the software and the hardware of the payload. Then we analyze the influence of sub-pixel information, satellite platform parameters, optical system parameters, detector parameters, noise and atmosphere on image data processing, especially the super-resolution reconstruction. we establish the physical model and the error model according to the physical mechanism of each factor, as a priori information of the reconstruction method, we apply these prior information constraints in favor of super-resolution to the design of the camera, enabling the images captured by the camera to match the super resolution method very well. This method can simultaneously improve visual resolution and substantial resolution, while maintaining the ability of suppressing noise and may reduce the size and development difficulty of traditional cameras. At the same time, we also carry out high dynamic range imaging technology based on the definition of CMOS software, which assists multi frame image superposition, and fit in the image processing algorithm, breaking through the digital dynamic range enhancement technology, and realizing the ability of high dynamic range clear imaging over high performance CCD. We have developed a general purpose computing optical imaging camera, which integrates the super resolution imaging, dynamic range enhanced imaging, video imaging and other multi intelligent controllable imaging modes. Finally we have completed the related camera integration, testing and experiment.
The super-resolution imager based on the coded aperture is a novelty technology. It breaks the constraints of conventional
optical imager in techniques and principles. The spatial resolution of the optical system is increased 1-fold than the
conventional system. In this paper, we have studied and analyzed the principle of super-resolution imager based on coded
aperture. We can add a high robust coded aperture in the stereotyped low-resolution camera to achieve improvement of the
original camera image resolution. In order to fully prove the advantages, we have designed a complete and
easy-to-experiment optical system based on the principle of the system.The Optical system focal length is 90mm. It is
coaxial optical path and its total length is 538.5mm. The MTF value is near the diffraction limit at 56lp / mm. We can obtain
good quality images by the system.Laboratory experiments verify that the spatial resolution of the optical system is 1 times
higher than that of the conventional ones.
With the rapid development of remote sensing imaging technology, the micro satellite, one kind of tiny spacecraft, appears during the past few years. A good many studies contribute to dwarfing satellites for imaging purpose. Generally speaking, micro satellites weigh less than 100 kilograms, even less than 50 kilograms, which are slightly larger or smaller than the common miniature refrigerators. However, the optical system design is hard to be perfect due to the satellite room and weight limitation. In most cases, the unprocessed data captured by the imager on the microsatellite cannot meet the application need. Spatial resolution is the key problem. As for remote sensing applications, the higher spatial resolution of images we gain, the wider fields we can apply them. Consequently, how to utilize super resolution (SR) and image fusion to enhance the quality of imagery deserves studying. Our team, the Key Laboratory of Computational Optical Imaging Technology, Academy Opto-Electronics, is devoted to designing high-performance microsat-borne imagers and high-efficiency image processing algorithms. This paper addresses a multispectral image enhancement framework for space-borne imagery, jointing the pan-sharpening and super resolution techniques to deal with the spatial resolution shortcoming of microsatellites. We test the remote sensing images acquired by CX6-02 satellite and give the SR performance. The experiments illustrate the proposed approach provides high-quality images.
In order to satisfy the strict requirements of the lightweight ratios and high dimensional stability for space mirror, the design method of lightweight structure and the flexible supporting structure of the primary mirror is proposed. Subsequently, the surface deformations of two different lightweight structures for primary mirror are discussed for analyzing the influence of the mirror weight on its surface. Finally, the finite element models for primary mirror assembly are built for calculating the surface deformation caused by different gravity orientations and various thermal environments. It is proved that the weight, stiffness and surface accuracy of the structure design for primary mirror can meet the engineering requirement.
The position of optical plane for a space remote sensing instrument will be changed in severe launching process and complex working thermal environments, which affects the imaging quality of the remote sensing instrument seriously. based on traditional R-C optical systems designed a new type of initiative thermal controlling focusing device, which was driver by the change of thermal according to the basic concepts of thermal expansion properties, the apparatus selectively adjusting the position of the secondary mirror to compensate for the amount of defocus, analysis the main factors of affecting the accuracy of focusing device, and using finite element analysis software for simulation data, while the device for the corresponding experimental verification according to the actual working environment .The results showed that the focusing device designed to meet the required shaking volume requirement 15."
As a novel spectrum imaging technology was developed recent years, push-broom coded aperture spectral imaging (PCASI) has the advantages of high throughput, high SNR, high stability etc. This coded aperture spectral imaging utilizes fixed code templates and push-broom mode, which can realize the high-precision reconstruction of spatial and spectral information. But during optical lens designing, manufacturing and debugging, it is inevitably exist some minor coma errors. Even minor coma errors can reduce image quality. In this paper, we simulated the system optical coma error’s influence to the quality of reconstructed image, analyzed the variant of the coded aperture in different optical coma effect, then proposed an accurate curve of image quality and optical coma quality in 255×255 size code template, which provide important references for design and development of push-broom coded aperture spectrometer.
Coded aperture spectroscopy allows for sources of large field to be efficiently coupled into dispersive spectrometers by
replacing the traditional input slit with a patterned mask. Spectral calibration is requisite for spectroscopy to obtain the
spectrum information exactly. In this paper, we described the spectral calibration’s principle and methods of coded
aperture spectral imaging, and then gave the results of the experiment using a monochromatic extended source, at last we
tested the accuracy of spectral calibration. The results indicate that this method can calibrate the coded aperture imaging
spectrometer with high accuracy.
In many modern optical systems, the resolution is limited not only by the diffraction caused by physical dimensions of the optics lens, but also by the CCD’s nonzero pixel size. Especially for the traditional incoherent illumination, the restriction of CCD pixel is greater than that of optical diffraction. Here we develop a novel approach to enhancing resolution beyond the limit set by CCD’s pixels, in which a two-dimensional and orthogonal encoding mask is attached before the imaging lens to modulate frequency on input target spectrum. Here we focus on the design about a 4f optical imaging system, considering the ability of Fourier transformation to achieve the equivalent conversion between space and frequency domain. And to prevent the loss of frequency in the overlapping regions when sampled by classical CCD, there must be some proportion between the spatial range of object plane and corresponding frequency plane. Meaning while, the wavefront aberration of Fourier lens needs to be controlled to fulfill the mathematical features of Fourier transformation. We apply to improving and revising the theoretical design for the encoding mask based on the design limit of opticalmechanical engineering, and we analyze the different orthogonal forms of encoding masks which can bring the spectra diffraction to the imaging area. According to the theoretical discussion, revision and algorithm simulation, the results in the preliminary testing system show that the encoding mask can be used to produce enhancement of resolution by a factor of 2 in-exchange for decreasing the field of view by the same factor.
Coded aperture spectral imaging is a new system to captures multiframes images and reconstructs them into spectral
image cube based on compressive sensing theory (CS). However, using dynamic transformed coded aperture pattern can
cause two primary problems, firstly the whole exposure procedure needs to be staring on the same surface feature which
is depended on a high quality stable platform; secondly the coded aperture’s transformation might reduce the system’s
stability. To avoid these problems without a loss of information for precise reconstruction, in the paper we propose
dividing the single image panel into encoding spatial overlapped sub-districts. We design a pushbroom scan pattern to
ensure each sub-district have enough sampling measurements. In each sub-district, we infer its measurement matrix can
satisfy the sparsely requirements needed for accurate estimation and final reconstruction with CS sampling. Considering
with efficiency and accuracy, we design a orthogonal self-loop coding mask (lines irrelevant) to guarantee the coding are
irrelevant among distinct snapshot of the same scene. The simulation experiment reveals the design helping reconstruct
the scene spectral cube with high throughput and resolution.