It is difficult for traditional CMOS camera to obtain clear images under extremely low-light conditions for example the new moon or the quarter moon because the photons generated are so few that the signal-to-noise ratio (SNR) is much lower than what is necessary to resolve finer details. Being different from traditional CMOS camera, intensified CMOS, named as ICMOS camera can greatly amplify the very limited arriving photons through external photoelectric effect and thus the corresponding SNR could be improved a lot for low-light conditions. In previous studies, by fusing a series of low-light images having sub-pixel displacement between each other through classical iterative back projection (IBP) reconstruction algorithm, not only the resolution is enhanced but also the SNR increases as well. However why the SNR can be improved through super-resolution reconstruction is not theoretically answered yet. Therefore in this manuscript two contributions are made. In the first place, the characteristics of sub-pixel super-resolution low-light imaging are firstly further investigated. By introducing the concept of spectral SNR, the analytical expression of the SNR before and after super-resolution reconstruction is established, based on which it is concluded that the MTF boosting generated by super-resolution reconstruction is one important factor that can bring in the SNR increment besides inherent noise reducing characteristic of the super-resolution reconstruction algorithm itself. In the second place, by combing the IBP based super-resolution reconstruction algorithm, the FFT (Fast Fourier Transform) based single image amplification and image enhancement methods together, better reconstruction results could be obtained.
In recent years, besides higher spatial resolution, higher temporal resolution and higher spectral resolution, extending the effective working time of satellite platform based aerospace paid much attention. And Low-Light-Level (LLL) remote sensing technology in visible band is one of the ways to achieve the goal. LLL remote-sensing camera has become a novel subject for the development of aerospace optical remote-sensing payloads. In this manuscript, first the status quo and trend of LLL remote sensing technology is made a comprehensive introduction. After that, centering on the crucial technique to realize the Low-Light-Level sensing, several different implementation ways are made a comparison both from the theoretical viewpoint and experiment demonstration. Finally, some advices are given on how to develop aerospace LLL remote sensing techniques based on the existing research results.
In recent years, besides higher spatial resolution, higher temporal resolution and higher spectral resolution, extending the effective working time of satellite platform based aerospace paid much attention. And Low-Light-Level (LLL) remote sensing technology in visible band is one of the ways to achieve the goal. LLL remote-sensing camera has become a novel subject for the development of aerospace optical remote-sensing payloads. In this manuscript, first the status quo and trend of LLL remote sensing technology is made a comprehensive introduction. After that, centering on the crucial technique to realize the Low-Light-Level sensing, several different implementation ways are made a comparison both from the theoretical viewpoint and experiment demonstration. Finally, some advices are given on how to develop aerospace LLL remote sensing techniques based on the existing research results.
In recent years, Low-Light-Level (LLL) remote -sensing camera has become a novel subject for the development of aerospace optical remote-sensing payloads. LLL remote sensing camera works in ultra-low light conditions, the image signal is very weak and requires image intensified technology to achieve. In order to make better use of LLL remote sensing data, it is necessary to establish the quantitative relationship between the amount of radiation received by the camera and the digital signal output to process the image. That's radiation calibration technology. Therefore, the radiation calibration of the LLL remote sensing camera is particularly important. In this article, first the requirements for calibration of LLL remote sensing cameras are analyzed in theory. After that, a radiation calibration scheme of the LLL remote sensing camera is put forward. Finally, the radiation calibration test is carried out, and the calibration data are analyzed. The results show that the calibration scheme of LLL remote sensing camera is reasonable and feasible.
Intensified CCD (ICCD) imagers have been widely used in low light level imaging system. While the ICCD has
smaller dynamic range in ubiquity, and its output image is prone to saturation in high light level. In this paper, the
auto-gated power supply method is put forward to implementing automatic brightness control (ABC). Consequently, the
ICCD camera imaging dynamic range is improved. Firstly, the principle of the auto-gated power supply is described
briefly, and the design scheme is carried out in detail. The pulse power control mode is adopted to the photocathode
instead of the traditional high voltage DC power supply, and the analog adjustment mode is adopted to the micro
channel plate (MCP). Secondly, an imaging experiment for ICCD camera was made to validate the auto-gated power
supply design, and the experiment results are presented. The results indicated that the design is valid, and the auto-gated
power supply method helps to improve the image quality of the ICCD camera. Finally, the key problems in the design
are analyzed and summarized in detail.
Image intensifiers are always used to amplify low light level (LLL) images in a wide wavelength range to observable
levels. As a leader in image intensifiers for industrial and scientific applications, intensified CCD (ICCD) is an
innovative product which is a hybrid of image intensifier and CCD. Over the past few decades ICCDs have been
increasingly developed and widely used in a variety of fields such as LLL television system and medical diagnostics. In
this paper, we present the application of ICCD in the field of LLL remote sensing. General LLL imaging devices are
introduced briefly, and their advantages and disadvantages are compared. ICCD technology which includes fundamental,
configuration and development, is expatiated on. The major parameters which incarnate the performance of the LLL
remote sensing ICCD camera are analyzed in detail, such as signal noise ratio (SNR), dynamic range, spatial resolution,
etc. An ICCD camera is designed, and an imaging experiment is made to validate the imaging ability of it in LLL
condition. The experiment results are discussed and summarized. At last, the most important issues to the application of
ICCD in LLL remote sensing are generalized in detail.
In this paper, the fundamental of the TDICCD mapping camera is introduced, and the influence of the satellite buffeting on the image quality of the TDICCD camera is analyzed. In order to reduce the influence, a regulated resolution is put forward. Compared with the traditional TDICCD mapping camera, a special TDICCD focal plane which several TDICCD devices splited joint end to end is designed. A great deal of information are captured through the focal plane, and a mathematical model is established to analyze the data information. Then the results are feed back to the satellite, and the attitude of the satellite is actively regulated in real time. Finally, make experiments and simulation to validate it. The experiment result indicate that the design is valid.
KEYWORDS: Charge-coupled devices, Signal processing, CCD cameras, Imaging systems, Digital signal processing, Field programmable gate arrays, Interference (communication), Analog electronics, CCD image sensors, Digital electronics
In this paper,compared with the traditional CCD camera imaging circuits, a kind of integrated
solution for CCD imaging circuits is put forward.The principle of the traditional CCD camera imaging
circuits is described briefly, and the foundational functions are introduced. CCD imaging circuits are the
most important parts of the CCD camera, and they are mainly made up of CCD driver circuits and CCD
signal processing circuits. The CCD signal processing circuits mainly consist of timing generator,
preamplifier circuits, CDS circuits, low-pass filter circuits, PGA circuits, ADC circuits, storage circuits,
output interface circuits, and so on. The popular solution is that all the circuits are made with separate
components.Complex circuit configuration, difficult debugging, uptight power dissipation are evident.
However, it goes without saying that the integrated solutions which combine ADC with FPGA device are
high integration, simple configuration and better agility. Finally, the integrated solution for CCD imaging
circuits is illustrated, and the problems of the circuits are analyzed and summarized in detail.
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