The traditional concept of graybody in IR application is investigated and new viewpoints are proposed. It is found that the spectral distribution of thermal radiation of a real body with emissivity (epsilon) < 1, compared with that of absolute blackbody, will shift to shortwave region, i.e. the blue shift phenomena will appear. This conclusion is obtained from studies on, first, the analyses and research of radiation characteristic of snow in visible and IR regions, second, the physical and mathematical analyses of thermal radiation of pure metals, and finally, the concept study of radiation temperature, luminance temperature and color temperature. Some reviews and suggestions are given to related problems in RI technology.
In China, one kind of remote sensing satellite development and applied at the very beginning is film-recovery photographic satellite. The camera systems of these satellites had been developed in two generations and three classes. Altogether China had successfully launched seventeen recoverable remote sensing satellites. Since 1980's, Chinese aerospace establishment has developed two types of meteorological satellites.In later 1998, ZY-1 earth-resource observation satellite, which is developed cooperatively by China and Brazil, is going to be launched into space. Chinese Academy of Space Technology, Beijing Institute of Space Machine and Electricity, and Shanghai Institute of Technical Physics, are the major space technology research establishments of China in providing remote sensing satellite platform and its payload. The presentation describes a survey of earth observation satellite and its payload instrument in China, and gives a picture to the future Chinese satellite remote sensing technology.
128 by 128 diffractive microlens arrays have been designed by considering the independent optical and processing parameters for 3-5 micrometers wavelength with a microlens size of 100 micrometers . The lens F number and array pitch are 1.5 and 100 micrometers , respectively. The diffractive microlens arrays have been fabricated on the surface of Si substrates by successive photolithography and Ar+ ion-beam-etching technique. The practical and fabrication method are discussed. The optical characteristics and measurements of the diffractive microlens arrays are presented.
The techniques of signal extracting and processing for remote sensing system are discussed in this paper. We are now developing a ten-band ocean color and temperature scanner for observing the ocean color. Because each spectral bandwidth is quite narrow and the reflectivity of water is very low, it is very important for the sensor to have a high sensitivity. The performance of detector limits the performance of sensor. Two kinds of detector are used in this sensor. The parameters and the operating modes of these detectors are introduces in this paper. Two kinds of preamplifier are also introduced. One is transimpedance amplifier that converts the output current from Si PV detectors to voltage signal. The other is instrument amplifier, which is used to amplify the output voltage of HgCdTe photoconductor. The equivalent input noises of these circuits are analyzed in detail. The parameters of the ten- band sensor are calculated finally.
China's first geostationary meteorological satellite FY-2 was successfully launched on June 10th 1997. The main effective payload on-board the satellite - the multi-channel scanning radiometer - was developed by the Shanghai Institute of Technical Physics, Chinese Academy of Sciences. The scanning radiometer can acquire the earth images from three channels of visible, IR and water vapor simultaneously. From the images obtained one can see that the images are very clear with enough signal to noise ratio. This paper takes a brief look back at the design and development of the optical system of the scanning radiometer.
An Ocean Color CCD Imager (OCCI) has been developed. It has three bands with nominal spectral region 430nm-520nm, 580nm- 670nm and 760nm-860nm. It is composed of three separate subsystem, each for one band, which have the same structure and operate in push-broom mode with 1024-pixel linear array CCD detectors. The specifications and characteristics of the OCCI are given, low nose and high signal-to-noise ratio ensure the excellent ability of the OCCI to observe ocean color and coastal zone. Data processing algorithm including radiance correction, atmosphere correction and imagery rebuilding also have been developed.
For an optical remote sensor with the large bandwidth, its output is quite influenced by the spectral shapes of the measured objects because of the unevenness of its spectral response in band; particularly for OCCI with nominal bandwidth of 90nm-100nm, so does it further. This paper calculates the equivalent blackbody temperatures for the integrated sphere used in the calibration of OCCI and on- orbit typical input radiance; and the output of OCCI for different temperature blackbodies also is computed, based on the measured relative spectral response of each band, Finally we give the correction factors for OCCI.
The paper describes the definition, the measurement and the calculation methods of the wave band detectivity and the wave band responsivity, and introduces the typical result of the detector array which manufactured at Kunming Institute of Physics. According to the space application of the IR detectors, the relations between the wave band detectivity and the temperature of the radiant sources are discussed. And the wave band detectivity instead of the peak wavelength detectivity is suggested.
A Schmit system with diffractive optical element (DOE) for wavefront correcting has been designed perfectly. The DOE is made by composition. All errors produced in manufacture process have been analyzed. Also the influence on optical performance of IR Schmit system has been calculated.
A novel imaging system with superresolution is introduced in the paper. The system is consisted of a high resolution lens, the dichroic beam-splitter and the four same area- array CCD sensors which the pixel size is b micrometers square. The five prisms are designed to divide the incident light beam into four beams. The four sensors are set up in the four imaging planes of the imaging system and their central coordinates are respectively (0,0), (b/2, 0), (0, b/2) and (b/2, b/2). Four different images would be simultaneously received through the imaging system for any object. Processing specially, a new image which has higher spatial resolution than the original four images would be achieved. The novel imaging system will be suitable for space application because the configuration is stable and rugged. If this new method is used in the design of high resolution remote sensing payloads to perform Earth observation, the focal length of the new remote sensing system could be reduced about 50 percent keeping the same spatial resolution comparing with the traditional imaging system.
The High Resolution Imaging Spectrometer (HIRIS) produces tremendous amounts of raw data. Transmission of these data to an earth receiving station is constrained by downlink communication bandwidth. To alleviate limitation, the data must be compressed. In this paper, we present a compression algorithm for hyperspectral image by using the 3D discrete cosine transform coding (3-D DCT). The 3D DCT includes a 1D DCT on spectral direction followed by 2D DCT on the DCT coefficient images produced by the 1D DCT. The main effect of the 1D DCT is to remove the data correlation on the spectral direction, and produces the spectral band corresponded DCT coefficient images. The resulting spectrally decorrelated DCT coefficient images are then compressed by the JPEG algorithm. The compression ratio is controlled by the quantization of JPEG. In the technology of Transform Coding, the quantization error of the transform coefficients is an important factor affecting the error of compression system. According to the statistical characteristics of the 1D DCT coefficients, we design a combined quantization. In utilizing JPEG to compress DCT coefficient images we apply different quantizations to different spectral bands for better compression.
Airship Remote Sensing System (ARSS) for obtain the dynamic or real time images in the remote sensing of the catastrophe and the environment, is a mixed complex system. Its sensor platform is a remote control airship. The achievement of a remote sensing mission depends on a series of factors. For this reason, it is very important for us to analyze reliability of ARSS. In first place, the system model was simplified form multi-stage system to two-state system on the basis of the result of the failure mode and effect analysis and the failure tree failure mode effect and criticality analysis. The failure tree was created after analyzing all factors and their interrelations. This failure tree includes four branches, e.g. engine subsystem, remote control subsystem, airship construction subsystem, flying metrology and climate subsystem. By way of failure tree analysis and basic-events classing, the weak links were discovered. The result of test running shown no difference in comparison with theory analysis. In accordance with the above conclusions, a plan of the reliability growth and reliability maintenance were posed. System's reliability are raised from 89 percent to 92 percent with the reformation of the man-machine interactive interface, the augmentation of the secondary better-groupie and the secondary remote control equipment.
The development of technology of space rapid location, geographical information system (GIS), spectral radiation measurement, computer manipulation of image and picture, and communication provides advantage environments the engineering the remote sensing technology. However, for the remote sensing information identification, because of the differences between ares, local environments, seasons, ground object features, and so on, though the same type of ground object spectral curve may be concluded a standard ground object spectrum of certain regular pattern in the macroscopic, there are great differences in the spectrum radiation characters of every ground object in the microscopic. In order to collect automatically remote sensing information of the ground objects to decide exactly the type and characteristics of the ground object, the key is to obtain the synchronous ground object radiation spectrum surveyed by remote sensing data. On the basis of the ground object radiation spectrum, with the reference to the background provided by the normal ground spectrum, the data from GIS, space orientation system and expert system,the target will be identified reliably and exactly by using digital image and graphic processing method supported by computer. It is necessary to use the observing station of radiation spectrum on the ground to design and develop the automatic ground spectrum surveying instruments corresponding to space remote sensing. Thus, the spectrum information at different areas, environments and time can be observe,d recorded and transferred to the ground station of space remote sensing form corresponding communication means. As a basis part of remote sensing data, it can be directly provided to consumers, makes the remote sensing technology become an engineering means, and can be used widely.
In this paper, a software system is described. It not only can simulate the satellite imaging process and make simulation image based on designed parameters, but also do image pre-processing, so it is very useful to both satellite designer and users.
This paper describes a new method for geometric correction of NOAA AVHRR data by using Landsat TM data. In this method, it mainly includes these procedures: (1) spatial degradation of Landsat TM data; (2) interpolation of AVHRR data; (3) preprocessing of degraded TM and interpolated AVHRR images; (4) image registration between the degraded TM image and interpolated AVHRR image at a same spatial resolution. With this method, we can get GCP's to implement accurate geometric correction of NOAA AVHRR Image, and achieve subpixel accuracy in geometric registration of AVHRR images.
The application of remote sensing is, to a greater extent, based on the quality of the sensors. The prelaunch radiant calibration and post-launch validation, which are the process of quantitatively defining the system response to known, controlled signal inputs, are among the key stages of the development procedure of a remote sensor. Calibration of a remote sensor is to develop the calibration equations that allow conversion of the counts for the sensor into Earth- exiting radiance. These radiances are the geophysical properties the instrument has been designed to measure. With solar radiation-based calibration, sphere radiation-based calibration, on-orbit calibrator and ground-based calibration, the remote sensor data can be quantitatively applied on atmosphere, environment. The precision of several methods is mentioned in the paper. The Chinese meteorological satellites had used the procedures to calibrate the sensors.
Atmosphere pollution is a serious problem now. There are many chemical components of atmosphere pollution sources which have special spectrum characteristics in 8-12 micrometers wavelength region. It is the physics base of monitoring atmosphere with the passive IR remote sensing system. We have developed a real time passive IR remote sensing and auto-discrimination alarm system for monitoring atmosphere pollution. The system includes an IR optical system, a FTIR, a signal processor and a controller. It is operated according to a parallel-pipeline work formula. The results prove that this system has high sensitivity, satisfactory discrimination result, correct and stable operation feature. In this paper, we will introduce the system and the algorithm.
A simulation system of CCD camera, by which the remote sensing image data may be obtained for small military target, is presented in the paper. The system can be used to determine the necessary pixel resolution requirement for remote sensing system, especially for reconnaissance satellite; to train interpreters for target recognition from remote sensing images; to examine the efficiency of camouflage technology. Some interesting results are given: airplanes, tanks and soldiers with pixel resolution 4.5m, 3.0m, 2.1m, 1, 1m, 0.3m and 0.2m.
The development of effective methods in environmental pollution control is a main task of environmental research. Fourier-transform IR spectroscopy is an efficient technique for the detection and quantification of molecules in gas mixtures. A passive IR system designed to detect specific pollution clouds in the atmosphere and sound an alarm in time. The sensor is a Fourier transform spectrometer operating in the 8-12 micrometers atmosphere window region of the spectrum. The system can be operated unattended and be highly reliable and accurate in its decisions. An on-board microcomputer will be applied to achieve automatically control of system, acquire data, process it and make decisions. The paper describes the signal processing and spectral pattern recognition techniques. Measurement results for ambient air with the spectrometer are reported.
Georeferenced image, a kind of digital ground image with 3D geographic coordinates, is an important data source of Global Information System (GIS). In constructing georeferenced images and considering its application, the positioning precision of geographic coordinates is a key specification. Remote sensing is a promising method for the data acquisition of georeferenced image. Using an integrated system of airborne remote sensing technique can high efficiently acquire georeferenced image and its geographic coordinates with better precision. In this thesis, that integrated technique and system is introduced first, which consists of laser ranging, whiskbroom imaging, differential global position system, and inertial reference system. Then the effect of each part on the system precision especially elevation precision is analyzed in detail, and the mathematics expression and data result are yielded. Furthermore, for obtaining high positioning precision of georeferenced image, some technical designs and methods are discussed.
As a remote sensing instrument, pushbroom hyperspectral imager demonstrates its advantages in many application operations. It brings people better spectral resolution with high signal-to-noise-ratio. As increase of the demand of environment study and city planning. In 1997 Pushbroom Hyperspectral Imager (PHI) was built in Shanghai. It has a refractive optical system with reflective grading as spectral divergence device and area array silicon CCD as detector. It upgrades SAIS with optimized optical system, 12 bit digitizer and PENTIUM in-bed computer. Special efforts are mae on parallel data recording to save more information with an inexpensive hardware configuration. The system can be easily mounted on gyro stabilize platform and work with dynamic GPS. PHI has succeeded in remote sensing operation for city planning of Beihai, Guangxi province. This paper will introduce the development of PHI, including system design, calibration and performance in operation. Plans for further studies, including real-time data process for pixel binning and data bus improvement for data rate speeding, are also introduced.
In order to fulfill the special requirements of space application on the spectral response properties and curve uniformity of multielement PC HgCdTe device, many measures have taken to improve the uniformity of multielement spectral response curve. We have deposited anti-reflecting coating on the surface of multielement HgCdTe detector chip, and the problem of deposition has been solved, better anti- reflecting coating has been prepared. The spectral response measurement results confirm that the spectral properties and the curve uniformity of multielement PC HgCdTe detector are improved obviously after depositing anti-reflecting coating, and fulfill the special requirements of multispectral scanner used for space application.
In this article we give opinion on how to design and manufacture the moving parts better. The article tells the necessity and the possible of making an expert system, according to the importance and the particularly of the work. And it also gives the frame of the system.
To the remote sensing devices on the satellite, there are often clouds in their field of view. From statistics, clouds usually cover about 40 percent of the earth surfaces. Most of the clouds will prevent signals in 0.3-3 micrometers from arriving the remote sensors except for thin cirrus. To those remote sensing devices or cameras aimed at getting signals from earth surface, they can only get some useless information at this time.Some research on the reflected spectrum of clouds and other main kinds of objects on earth surface is necessary to find an effective way to tell them apart. We make an analysis to the reflectance of clouds and other objects in this paper, then two spectral channels are chosen to give a judgement. A stand alone prototype device is also developed for this purpose.
The results of an experimental study of the relationship between the ground resolution and pixel resolution for CCD camera is presented in the paper. For a long sloping grating pattern target the ratio between resolutions is equal to 2.83-4.
In airborne earth positioning and terrain mapping, scanning laser ranging plays an important role. It uses pulse laser range finder and its scanning beam to measure the distance between the sampled ground site and the flying platform along each laser beam pointing. The laser sounding effect determines ranging reliability and operation height. But under the condition of dynamic scanning sounding, there would be no complete overlap between the receiving field of view and the radiating laser beam. This directly leads to lower power sounding effect and finally limits effective operation height. In this paper the rule of the dynamic sounding effect is analyzed in detail and the mathematics expression of the dynamic overlap factor of the laser beam and receiving field of view is obtained. The conclusion opens out the effect of every affecting factor on the dynamic overlap factor, which includes laser beam divergence, instantaneous receiving field of view, scanning speed, operation height and scanning beam obliquity. Some technical methods are discussed to obtain larger dynamic overlap factor.
A new 64 by 64 CMOS readout integrated circuit has been designed for the signal readout of HgCdTe and InSb IR photodetector arrays. The readout integrated circuit comprises a 64 by 64 MOS switching array, a horizontal decoder, and two 32-channel CTIA amplifiers in which the direct injection current of each photodetector is integrated and amplified. It is convenience to adjust the integration time and readout rate of the photodetector array separately. The test result of the readout circuit chips were shown, and the performance of the readout integrated circuit were evaluated.
PtSi Schottky-barrier (SB) FPAs have been developed for ground-based thermal imaging and spaceborne remote sensing applications, making the best possible use of its process compatibility with Si LSIs. The FPAs for mid wavelength IR thermal imaging are large format 2D arrays with several array sizes up to 1040 X 1040. An original readout architecture called the Charge Sweep Device has contributed to enhancing their sensitivities, and our state-of-the-art technology has reached a level which realizes FPAs with NETDs of the order of 30 mK. Extending the SB FPA technology to the short wavelength IR spectral region has made it possible to exploit spaceborne remote sensing applications. The space-grade performance and reliability have been demonstrated with a 4096 element and 2100 element linear FPAs.
The paper describes an approach to parametric optimization of an IR imaging system. This approach is based on minimization of image distortion of a multi-bar test object. The quality of imaging system is defined by a probability of correct pixel classification. This probability characterizes an error of image binarization. The paper represents the mathematical model that binds the probability of correct pixel classification with parameters of an imaging system such as focal length, aperture diameter, dimensions of photosensitive element, integration time and etc. It allows to get the merit function for parametric optimization and to identify the optimal relationship between spatial resolution and temperature resolution.
It had been discussed earlier existing of the controlled photoconductivity (PC) in gapless semiconductor Hg1-xCdxTe which is induced within the millimeter (MM) and IR ranges by uniaxial stress or high magnetic field. These forces open the energy gap following to Eg(P)-bx(s11-s12) xP or Eg(H)-heH/4mnc respectively and influence the generation and recombination processes in the material. Here, b is a deformation potential constant, sij is an elastic strain tensor components and m is an electron effective mass in conduction band. In this report a possibility is analyzed of effective detecting of the MM and submillimeter (SMM) thermal radiation by means of the above mentioned controlled PC in combination with a parametric heterodyning of frequencies. The problem seems to be resolvable because the number of spectral lines can be generated with tunable lasers of high enough power within the MM and SMM radiation range. The features are also taken into account that arise in connection with the spectral 'quality' of black-body radiation and in the cases when radiator has a size of order of the wavelength to be detected. It is shown that the ratio can drastically influence the efficiency of detecting process because the time which is necessary to detect this radiator, or object consist of small-size particles.
In this paper we present new results from the characterization of a fully depleted CCD on high resistivity silicon. The CCD was fabricated at Lawrence Berkeley National Laboratory on a 10-12 K(Omega) -cm n-type silicon substrate. The CCD is a 200 by 200 15-micrometers square pixel array. The high resistivity of the starting material makes it possible to deplete the entire 300 micrometers thick substrate. This results in improved red and near IR response compared to a standard CCD. Because the substrate is fully depleted, thinning of the CCD is not required for backside illumination, and the result presented here were obtained with a backside illuminated device. In this paper we present measured quantum efficiency as a function of temperature, and we describe a novel clocking scheme to measure serial charge transfer efficiency. We demonstrate an industrial application in which the CCD is more than an order of magnitude more sensitive than a commercial camera using a standard CCD.