With the demand of quantitative remote sensing technology growing, high reliability as well as high accuracy radiometric calibration technology, especially the on-orbit radiometric calibration device has become an essential orientation in term of quantitative remote sensing technology. In recent years, global launches of remote sensing satellites are equipped with innovative on-orbit radiometric calibration devices. In order to meet the requirements of covering a very wide dynamic range and no-shielding radiometric calibration system, we designed a projection-type radiometric calibration device for high dynamic range sensors based on the Schmidt telescope system. In this internal radiometric calibration device, we select the EF-8530 light source as the calibration blackbody. EF-8530 is a high emittance Nichrome (Ni-Cr) reference source. It can operate in steady or pulsed state mode at a peak temperature of 973K. The irradiance from the source was projected to the IRFPA. The irradiance needs to ensure that the IRFPA can obtain different amplitude of the uniform irradiance through the narrow IR passbands and cover the very wide dynamic range. Combining the internal on-orbit radiometric calibration device with the specially designed adaptive radiometric calibration algorithms, an on-orbit dynamic non-uniformity correction can be accomplished without blocking the optical beam from outside the telescope. The design optimizes optics, source design, and power supply electronics for irradiance accuracy and uniformity. The internal on-orbit radiometric calibration device not only satisfies a series of indexes such as stability, accuracy, large dynamic range and uniformity of irradiance, but also has the advantages of short heating and cooling time, small volume, lightweight, low power consumption and many other features. It can realize the fast and efficient relative radiometric calibration without shielding the field of view. The device can applied to the design and manufacture of the scanning infrared imaging system, the infrared remote sensing system, the infrared early-warning satellite, and so on.
Natural light will be partially polarized or totally polarized after the reflection, scattering, absorption and refraction of the objects. When detecting the ocean from the satellite orbit, the remote sensing signal of water is mainly composed of three parts: radiation signals of atmosphere after photon scattering, the direct reflection of light when the sunlight reaches the surface of the water, and the light after scatting backward. The sunlight will be polarized when it passes the atmosphere. Also, the polarization state of the incident light will be changed when it passes in the water. For remote sensing cameras with quantitative detection application, it is necessary to suppress the polarization sensitivity of the system as far as possible. Through the layout of the optics, the film layer design, the design of the depolarizer, we can achieve low polarization sensitivity.
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.
The bidirectional oversampling imaging detection system solved the difficulties of infrared point target detection
under the traditional single sampling system, effectively improved the image target detection SNR and reduced the
false alarm, and improved the target detection performance. The mathematical modeling and system simulation of
both traditional line scanning method and bidirectional oversampling scanning system proved that under the same
conditions, the detection rate of bidirectional oversampling system is higher than conventional sampling, while the
false alarm rate of bidirectional oversampling system is less than conventional sampling.
Infrared camera, which works on cryogenic or normal temperature, has thermal radiation inside. It is called interior radiation. In the space optical remote sensor, interior radiation will produce a lot of bad effects. Firstly, it can depress image contrast. What is more, dynamic range and integral time will be decreased. Lastly, interior radiation is one of the main factors that affect the measurement accuracy. So, restraining interior radiation is one of the key technologies to enhance the quality of infrared thermal imaging technology. In this paper, the typical technology of restraining interior radiation is summarized. At the end of the paper, blue prints for restraining interior radiation are proposed.
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.
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.
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.
With the uprating requirements of space remote sensing, the aperture of the optical remote sensor is getting larger and larger. The influences of both the support of optical elements and gravity deformation on the optical system are difficult to conquer. Therefore, it is necessary to compensate the descending optical performance which is caused by the surface error of primary mirror by means of adjusting the position parameters of the optical elements on-orbit. A large aperture coaxial three-mirror optical system is introduced in the paper. Matlab and MetroPro are used to simulate the surface error of the primary mirror. The surface error of the primary mirror is compensated by adjusting the position freedoms of the secondary mirror. The results show that the adjustment of the position freedoms of the secondary mirror can compensate both the coma and some astigmatism of the primary mirror, but not the spherical aberration.
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.
For argumentation of feasibility of LST (Land Surface Temperature) retrieval using 8-10 μm infrared band, this paper focuses on design of long-wave infrared band based on theory research. Basis of thermal infrared radiative transfer and atmospheric simulation, the paper analyses atmospheric effect on different long-wave infrared and obtain a preliminary selection of potential spectral channels. Several configurations of long-wave infrared spectral band were selected to perform in Split-Window algorithm and the relation of LST retrieval precision with error source was analyzed. Results indicate the scheme of LST retrieval using 8.0-9.0μm long-wave infrared is feasibility for needed retrieval precision.
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.
While executing tasks such as ocean pollution monitoring, maritime rescue, geographic mapping, and automatic
navigation utilizing remote sensing images, the coastline feature should be determined. Traditional methods are not
satisfactory to extract coastline in high-resolution panchromatic remote sensing image. Active contour model, also called snakes, have proven useful for interactive specification of image contours, so it is used as an effective coastlines extraction technique. Firstly, coastlines are detected by water segmentation and boundary tracking, which are considered initial contours to be optimized through active contour model. As better energy functions are developed, the power assist of snakes becomes effective. New internal energy has been done to reduce problems caused by convergence to local minima, and new external energy can greatly enlarge the capture region around features of interest. After normalization processing, energies are iterated using greedy algorithm to accelerate convergence rate. The experimental results encompassed examples in images and demonstrated the capabilities and efficiencies of the improvement.
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.
The launched space optical Remote Sensors, including the three generations of space
film remote sensor, the space CCD remote sensor and the IRMSS for resources survey, the first
generation CCD and IR remote sensor for disaster monitoring, the first generation CCD and IR
camera for ocean monitoring, the related remote sensor in polar orbit and geostationary orbit for
meteorological detection and forecasting, the first generation related remote sensor for deep space
exploration, etc, are presented in detail in the paper. The related technologies, including system
design technology, the lens technology, the FPA video technology, the manufacture technology,
the AIT technology, etc, are also introduced in the paper. The Chinese great achievements in the
field of space optical remote sensor are shown. The prospects on future development of the space
serial optical remote sensors and the related technologies are made.