With continuous development, the hyperspectral imaging has become a hot topic in the field of remote sensing, since its enormous advantage in obtaining the material composition of atmosphere, land resources, battlefield environment and marine resources while observing the Earth in space. However, some challenges have hindered the application of space-based hyperspectral imaging system. To fulfill the requirements of the spectral imager especially for space use, the lightweight and stable structure is especially important. Here the implementation of a Large Aperture Hyperspectral Imaging Optical System is presented. The optical system achieves hyperspectral imaging from ultraviolet to infrared spectral bands. The different spectral bands share a large common aperture of Ø1.8m. A lightweight primary mirror is designed and supported by bipod structure. To keep the large distance between the primary mirror and second mirror, a Lightweight and high-strength truss has been applied. A hierarchical structure is adopt as the main structure of the whole system. With the diffraction gratings and optical slits, the image information of different spectral bands are detected by the different lines of pixels in a focal plane of planar array. By the creative works of the optical and mechanical design, a hyperspectral imaging optical system is implemented and shows the extensive application potential in space remote sensing.
KEYWORDS: Black bodies, Body temperature, Calibration, Temperature metrology, Resistance, Control systems, Satellites, Platinum, Infrared radiation, Cameras
This article elaborates on the working principle of the on-board blackbody calibration system, through the high-performance design and accurate index accuracy of the key indicators of high and low large-aperture surface blackbody (effective emission surface normal emissivity, temperature stability, temperature uniformity) Effective control, so as to obtain high and low temperature blackbody normal emissivity 0.98, temperature stability ≤ ± 0.15K/30min, temperature uniformity ±0.25K high-performance calibration indicators. By adding different thermal control measures to the high temperature black body and the low temperature black body, the temperature stability of the working temperature control interval required by each can be obtained. Among them, the temperature of the high-temperature black body is realized by applying a heat sheet with a reasonable cloth, while the temperature of the low-temperature black body is lower than the ambient temperature in the camera, and the temperature compensation is realized by installing a heat sink in the cold space, and then attaching the heating sheet to the heat pipe. For both high temperature blackbody and low temperature blackbody, precision platinum resistance thermometers are used to accurately monitor their temperature in real time. By reasonably arranging the position of the platinum resistance and the platinum resistance test line, the blackbody temperature measurement accuracy can be controlled within ±0.05°C. In the end, the high-stability large-aperture blackbody calibration system through the comprehensive work of various structural components, thermal control components and the main optical system to obtain the high-precision infrared temperature calibration requirements required by the load, which provides for subsequent model development. Successful engineering experience.
This paper discussed the main technical specifications and applications of the recent typical infrared optical remote sensor in the world, analyzed and summarized the trends, and speculated the development direction of infrared detection technology in future.
Imaging spectropolarimetry has been explored as a method that increment in our capability to respond to existing requirements, as well as to our insatiable need for more information in remote sensing applications. Spectrometry enables detailed comparison of target and background spectra. The polarimetric state of received radiation contains valuable information about source object surface roughness and orientation, it has the potential to highlight manmade objects despite spectral camouflage. A laboratory breadboard spectropolarimetric system has been design for operation in the visible waveband to demonstrate the potential of this technique for future airborne and spaceborne systems. The experiment setup and some experimental results are presented in this paper.
Traditional video imagers require high-speed CCD, we present a new method to implement video imagers with low speed CCD detector imager system based on video compressed. Using low speed CCD detector and transmissive liquid crystal (LC) instead of high speed CCD to get data cube; by the method of data processing method , we make high precision reconstruction of compressed video data, theoretical analysis and experimental result show that it is not ensures the video imaging quality but also reduced the frame rate of the detectors and complexity of video imaging system greatly.
The spectrometers capture large amount of raw and 3-dimensional (3D) spatial-spectral scene information with 2- dimensional (2D) focal plane arrays(FPA). In many applications, including imaging system and video cameras, the Nyquist rate is so high that too many samples result, making compression a precondition to storage or transmission. Compressive sensing theory employs non-adaptive linear projections that preserve the structure of the signal, the signal is then reconstructed from these projections using an optimization process. This article overview the fundamental spectral imagers based on compressive sensing, the coded aperture snapshot spectral imagers (CASSI) and high-resolution imagers via moving random exposure. Besides that, the article propose a new method to implement spectral imagers with linear detector imager systems based on spectrum compressed. The article describes the system introduction and code process, and it illustrates results with real data and imagery. Simulations are shown to illustrate the performance improvement attained by the new model and complexity of the imaging system greatly reduced by using linear detector.
Climate warming has become a serious problem facing all countries in the world, the impact of global climate change on
the human environment subject to widespread international concern. In recent years, American and European countries
invest a lot of manpower and resources to carry out the detection load of Atmospheric and Environmental Research, and
the ultra-high spectral resolution capability is an important prerequisite for the realization of atmospheric trace
constituents exact retrieved, the development of ultra-high spectral resolution load has become an important trend. This
paper presents a new compact spectrometer for atmospheric and environmental exploration, which uses a narrow-band
interference filter type, filter through different angles of incidence of the light beam spectral drift characteristics , to
achieve ultra- fine spectral splitting . This spectrometer while achieving ultra-high spectral resolution , the structure of a
compact camera with good engineering can be realized , and has broad application prospects.
Global warming has become a very serious issue for human beings. The substantial increase of column carbon dioxide (CO2) results in temperature raised of the earth’s surface. One important specification is that it must have an ultra-spectral ability to measure concentration inversion of CO2, developing ultra-spectral remote sensors is an significant direction. This paper brings a new spectrometer on atmospheric sounding, that splits spectrum with a new type of narrow-band interference filter. It can simultaneity get super finely spectrum, compact configuration, and easy to achieve. That has broad applied foreground.
A new kind of polarization modulation is presented in this paper-sinusoidal polarization modulation. It can acquire the
full linear polarization information of targets. The large advantage of this modulation is that it is very compact and with
low mass and there is no moving parts in it. Moreover the demodulation algorithm is not only simple but also with high
precision. It’s especially suitable for spaceborne atmosphere detecting sensor, providing a new kind of polarization
modulation for it. After the incident lights passing through the modulator, it is modulated into sinusoidal with amplitude
scaling with the degree of linear polarization and phase scaling with the angle of linear polarization. With a dedicated
algorithm, the degree and angle of linear polarization can be acquired directly while traditional polarization modulation
methods need I、Q、U、V parameters of the Stokes vector for further calculation. In this paper, theoretical and simulation
analysis on spectral modulation are presented, the results of analysis point out the feasibility of this technology in theory.
Spectral video is crucial for monitoring of dynamic scenes, reconnaissance of moving targets, observation and tracking
of living cells, etc. The traditional spectral imaging methods need multiple exposures to capture a full frame spectral
image, which leads to a low temporal resolution and thus lose their value as spectral video. The new code aperture
snapshot spectral imaging (CASSI) method has been emerging in recent years, which is suitable for spectral video
acquisition, due to its high-speed snapshot and few-amount measurements. Based on the CASSI, this paper proposes a
compressive spectral video acquisition method with double-channel complementary coded aperture. The method can
achieve the spectral video with a high temporal resolution by directly sampling the 3D spectral scene with 2D array
sensor in only one snapshot. Furthermore, by using the double-channel complementary coded aperture in compressive
measurement and the sparse regularity in the optimization recovery together, we can obtain the higher PSNR and better
visual effects compared with the single-channel CASSI. Simulation results demonstrate the efficacy of the proposed
method.
By the success of compressive sensing (CS), coded aperture snapshot spectral imager (CASSI) computationally
obtains 3D spectral images from 2D compressive measurement. In CASSI, each pixel of the detector captures
spectral information only from one voxel in each band with binary weights (i.e., 0 or 1), which limits the variety
of superposition relationship among the 3D voxels in the underlying scene. Moreover, the correspondence of each
pixel of detector to each pixel of coded aperture cannot be readily achieved in the presence of dispersive prism,
due to the small pixel sizes of these elements (often in micrometer). In this paper, we propose a flexible design to
improve the performance of CASSI with currently employed optical elements in CASSI. Specifically, the proposed
design integrates a kind of flexible alignment relationship along the coded aperture, the dispersive prism and
the detector. Each measurement of the detector is manifested as the summation of several voxels in each band
with random decimal weights and different measurements corresponds to overlapped voxels, which provides more
sufficient superposition relationship of the scene information. This flexible design favors the sensing mechanism
better satisfy the requirement of CS theory. Furthermore, the proposed design greatly reduces the alignment
complexity and burden of system construction. Preliminary result achieves improved image quality, including
higher PSNR and better perceptual effect, compared to the traditional design.
Spectropolarimetry is the technique that spectrally resolves polarisation properties of light. The conventional spectropolarimeter generally suffer from vibration, electrical noise, and alignment difficulty introduced by the mechanical or electro-optic device for polarization control, such as a rotating compensator and a liquid crystal device, such a polarization controlling element generally requires the considerable volume as well as the electronic driving cables, which has been the major obstacles for the reduction in the size of the spectropolarimeter. This paper presents a compact configuration of the channeled spectropolarimeter designed to increase the stability of the state of polarization measurement, the whole spectropolarimeter system without any internal moving parts, electrically controllable or micro-components, which enables us to determine all the parameters related to the spectral dependence of the state of polarization of light at once from a single measurement. In this spectropolarimeter system, multiple-order retarders are utilized to generate a channeled spectrum carrying information about the wavelength-dependent multiple parameters of polarization of light. The theory analysis and some aspects of our proof of concept experiments are given in this paper.
Polarization hyperspectral imagers combine polarization technology, spectral technology and imaging technology, get both the image of the target and the polarization and spectrum of the pixel to recognize the materials on the objects,have broad applied foreground on airborne remote sensing domain. That arrests extensive attention abroad.
This paper brings hyperspectral technology and polarization image together. On the basis of geometrical optics theory
and polarization theory, puts forward a new polarization hyper-spectral Imaging technology. That could get hyper-spectral information and whole Stokes elements spectral from the object on the measuring the power spectral from
the modulator only one time, and that raise the ability of recognization greatly. The paper carries out a project to the new airborne polarization hyperspectral imager.
This paper brings hyperspectral technology and compute image together, on the basis of
geometrical optics theory and compressed sensing theory, put forward a new computational
spectral Imaging technology. That raises two to four times on spatial resolution and double on
spectral resolution compared conventional hyperspectral imagers. Owing to have finished
compressing when getting the imaging signal, that could resolve the conflict between the mass of
data bringing with high resolution and transfers and storage. The paper carries out a project to the
new hyperspectral imager.
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