KEYWORDS: Target detection, Sensors, Signal to noise ratio, Cameras, Stray light, Satellites, Space reconnaissance, Space operations, Quantum efficiency, Information security
For the current ground-based space target surveillance system in China, the task response time is long, the target monitoring system is time-sensitive, and the space-based on-orbit monitoring current monitoring system usually has a small field of view, and the field of view is generally 6°, the monitoring range is limited, and the tracking arc is limited. This paper proposes a design of space-based large field of view monitoring camera. The selection and experimental analysis of high quantum efficiency and low noise detectors, detector refrigeration design and thermal test verification, big angle and high suppression ratio stray light design, this key points of high sensitivity detection camera for dim target are discussed in this paper, and lay the foundation for quickly acquiring the position and orbit information capability of long-range dim targets, providing high-precision cataloging of fast-moving dark space targets, improving the monitoring performance and real-time performance of surveillance systems in China.
The difficulty or even the impossibility of manufacturing of lenses with large apertures results in optical systems holding at least two mirrors, serving as the primary and the secondary mirrors respectively, are widely used in space application to realize large apertures, long focal lengths and high resolution, etc. Some of these optical systems fall into the catadioptric group, and others are all-reflective ones. What is more, the latter ones take the advantage of chromatic-aberration-free and the possibility of further lightening. To get an achromatic, light-weighted and compact zoom optical system with a large aperture, a long focal length and high solution, the all-reflective zoom system becomes an ideal choice. A method is described for the design of mechanically compensated reflective zoom systems with 3 mirrors. The method is based on the 3rd-order aberration theory. The advantage of this method is that, through constrained optimization of a set of Seidel aberration coefficient functions, it allows the designer to achieve the initial construction parameters of the optical system, and the design results prove the feasibility of this method.
The stray light analysis is always carried out after the optical system design is completed. However, for the off-axis system with 3 mirrors, if the space between the mirrors is not enough to place baffles, the optical system must be redesigned. To avoid this, a new design method for 3-mirror off-axis optical system with the consideration of stray light analysis based on vector aberration theory is presented. At the initial stage of the optical design, the correction of varied aberrations, such as spherical aberration, coma, astigmatism, etc., and the reservation of enough space for different baffles by decentering and tilting mirrors are carried out at the same time. Considering that in order to get enough reserved space, the decenters and tilts of some mirrors may be not a small amount, and the third-order aberration theory must have large deviations in guiding the design of off-axis optical system with 3 mirrors. For the convenience and efficiency of aberration correction, the vector aberration theory is also applied to the design to make sure the decenters and the tilts of mirrors will introduce minimum interference to image quality. Based on the vector aberration theory, we can obtain the initial results by solving the aberration equations with proper constrains. The initial structure can be served as the starting point for optimization design. At the end of the paper, a design example is illustrated and its stray light analysis is also finished in the software Fred, which a professional stray light analysis software. And the design and analysis results show that the optical system has a very high imaging quality and a good ability of suppression of stray light.
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 summary of hyperspectral polarization remote sensing detection is presented, including the characteristics and mechanism of polarization detection, the expression of polarization light and the detection method. The present research of hyperspectral polarization remote sensing is introduced. A novel method of hyperspectral polarization imaging technique is discussed, which is based on static modulation adding with the double refraction crystal. The static modulation is composed of one polarizer and two retarders. The double refraction crystal is used to generate interference image. The four Stokes vectors and spectral information can be detected only by one measurement. The method of static modulation is introduced in detail and is simulated by computer. The experimental system is also established in laboratory. The basic concept of the technique is verified. The simulation error of DOP (polarization degree detection) is about 1%. The experimental error of DOP is less than 5%. The merits of the novel system are no moving parts, compactness and no electrical element.
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.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.