Push broom type spectrum imaging optical system with high resolution and wide visual field

Abstract

The invention discloses a push broom type spectrum imaging optical system with high resolution and wide visual field. The push broom type spectrum imaging optical system with the high resolution and wide visual field comprises an off-axis three-mirror telescope objective and a spectrometer based on light splitting of prism-grating-prism, the spectrometer based on the light splitting of prism-grating-prism comprises a slit, a collimating lens, a dispersion device, a converging mirror and a plane array detector, and the field diaphragm slit is disposed on a focal plane of the telescope objective. Based on actual needs, a plurality of channels can be designed to share one telescope objective, and when a surface subject enters the telescope objective, a diachronic mirror performs light splitting in the rear, and then each light images through the spectrometer, and thus, different spectral widths can be realized according to needs. Furthermore, the system is compact, lightweight, flexible and practical. The invented high-resolution and wide-field spectrum imaging system is capable of effectively solving the problems of small general field of view, low resolution and low operating efficiency in an existing push-broom imaging system.

Description

technical field [0001] The invention relates to an improved design of a hyperspectral imager to achieve high resolution and wide field of view, in particular to an optical system with high resolution and wide field of view for spaceborne and airborne pushbroom hyperspectral imagers design. Background technique [0002] Hyperspectral imager is a new generation of space optical remote sensing instrument developed on the basis of multispectral remote sensing imaging technology in the 1980s. Multispectral images are being widely used in land, atmosphere and ocean observations. [0003] The push-broom hyperspectral imager provides spectral dimension information while acquiring spatial information of ground objects. The existence and composition of substances are revealed through the specific spectral characteristics of substances, so as to achieve the remote sensing goal of identifying substances on the earth's surface from space. Its working principle is: the ground object ra...

AI Technical Summary

Problems solved by technology

For traditional telescopic system design, there are two options: refraction system and reflective system. The refraction system needs to use special materials and structures to eliminate secondary spectral chromatic aberration. The reflective system does not produce chromatic aberration, and the aperture and focal length can be made large. , and suitable for lightweight. Although the structure of the existing two-mirror system is simple, the system has few independent variables, only the point imaging on the axis is ideal, and the field of view cannot be made very large. Can not meet the large field of view, large relative aperture requirements. In the three-mirror system, although the structure of the coaxial three-reflector system is relatively simple, the imaging quality is greatly affected by the obstruction of the secondary mirror, and the radiation utilization rate is not high, which reduces the resolution of the optical system. On the other hand, it is necessary to increase the aperture to ensure a certain amount of received radiation energy; the optical design of the spectral imaging system mainly involves the design of the spectroscopic system. Acousto-optic tunable filters, liquid crystal tunable filters, gradient filters, etc.

The prism and grating spectroscopic technology appeared earlier and the technology is relatively mature. Most aeronautical and aerospace imaging spectrometers have adopted this kind of spectroscopic technology. The disadvantage of using prism spectroscopic is that the linear dispersion rate is related to the wavelength, which will cause the spectrum of each line of the area array CCD The sampling interval is not the same, which is not conducive to the selection of channel bandwidth programming; the grating spectroscopic method is adopted, and in the case of a large incident angle, the line dispersion rate of the spectrum has nothing to do with the wavelength, which can meet the requirements of the constant value of the line dispersion rate of the spectroscopic system. and has higher spectral resolution than prisms

However, in the traditional transmission grating, the zero-order main maximum without dispersion in the diffraction pattern occupies a large part of the total light energy, and the light energy is dispersed in all levels of spectrum, resulting in low diffraction efficiency.

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