Optical system and reflection-type diffraction grating thereof

The invention discloses an optical system and a reflection-type diffraction grating of the optical system. The optical system comprises an input part, a preset output surface and the reflection-type diffraction grating. The input part is used for receiving optical signals. The reflection-type diffraction grating comprises a plurality of diffraction structures and a grating contour surface which is a non-arc surface. The diffraction structures are used for separating the optical signals into a plurality of spectral components and arranged on the grating contour surface at a plurality of grating intervals respectively, wherein part of the grating intervals are different from one another, so that the spectral components are output to the preset output surface in the mode of being perpendicular to the preset output surface substantially. The grating contour surface is used for focusing the spectral components on the preset output surface.