实现同步轨道(GEO)高分辨力对地观测的技术途径(下)

在地球静止同步轨道(GEO)上实现高分辨力对地观测,具有一系列独特优点,远为其它轨道所不及。然而,对于36 000 km的远程高分辨力可见波段观测,要求望远镜必须具备20 m以上口径的主镜。传统的空间相机,如果要有如此大的口径,其总质量将超过1 000 t,无法发射到GEO上。无支撑薄膜望远镜和大口径衍射望远镜,可以大幅度降低主镜质量面密度,从而降低整个相机系统的总质量,可算是一种极好的技术途径。分步发射与在轨装配,则提供了可供此类观测系统实施从地面转运到GEO的技术手段。基于变换成像原理的傅里叶望远镜，将高分辨力的取得，由增大接收口径转变为加大发射间隔，用大面积回波能量探测加上傅里叶分量重构，取代常见的目标图像直接探测，突破了远程高分辨力观测的致命瓶颈。近完美透镜为突破衍射极限提供了可能性,从而为超分辨力观测开拓出一片科学的新天地。负折射率材料(左手型材料)可制成完美透镜,而光子晶体是负折射率材料的热门选择之一,基于表面等离子激元(SPP)的光子器件则是其另一种选择。

Realization of high resolution visible earth observation on geostationary earth orbit

High resolution visible earth observation on the Geostationary Earth Orbit（GEO） has a series of unique advantages over that in the other orbits. However, long range and high resolution visible observation requests a large primary mirror more than 20 m in the diameter. The traditional Space Telescope(ST) with such a large primany mirror can not be launched to GEO, for its total mass is more than 1 000 t. An unsupported membrane ST and a large diameter diffraction ST can significantly reduce mirror surface density and lower down the total mass of the ST, which offers an excellent technologic approach to earth observation. Moreover, both the launching by module and the assembly in an orbit provide the technological means to tranport these kinds of observation systems from ground to GEO. Fourier telescope based on the theory of transform imaging changes the acquirement for high resolution from increasing the receiving diameter into ncreasing the illumination interval, and from detecting the object image directly into receiving the echo energy and reconstructing Fourier components. It breaks through the fatal bottleneck of the long range and hign resolution observation. Recently, a near perfect lens has been developed to provide the possibility for breakthrough of diffraction limit, so that a new science field will be set up for super resolution observation. The perfect lens makes of negative refractive index materials(left handed materials) and the negative refractive index materials come from both of the photonic crystals and the photonic devices based on Surface Plasmon Polariton(SPP).