The paper outlines the optical systems applied in present hyperspectral imagers. The principle and characteristics of three spectrum-dividing methods with prism

grating and FT(Fourier Transform) are discussed

prism dispersion spectrometer results in high utilization rate of input light energy

but large volume and unreliability limit its application in spaceborne hyperspectral imager

grating dispersion spectrometer has low diffraction efficiency

small volume and stability in space

FT spectrometer only has no more than 50% efficiency due to beam splitter. The paper gives some representative optics adopted by present spaceborne hyperspectral imagers. Finally

an optical system with TMA telescope and two Offner convex grating spectrometer

used in a compact spaceborne hyperspactral imager is designed

small volume

high imaging quality and no spectral distortion make it applicable in spaceborne hyperspectral imager. Enlarging relative aperture of optical system can recuperate low diffraction efficiency.