光谱仪中的成象系统包括准直镜和成象物镜,它们是由简单透镜或球面反射镜组成.成象系统在光谱仪中的作用是使发散光束变成平行光束,平行光束成为会聚光束并使物体在一定位置成象。但我们在几何光学中讨论透镜成象时,范围仅限于光学系统的近轴区域,此外,还假定了介质的折射率不随光的波长而变。只有在物点和光线都限制在近轴区域的条件下,才能实现理想成象.而我们所遇到的大多是具有连续光谱的复色光,由于介质的折射率是随波长而 Imaging systems in spectrometers include collimating mirrors and imaging objectives consisting of simple lenses or spherical mirrors.The effect of the imaging system in the spectrometer is to make the divergent beams into parallel beams and the parallel beams to act as converging beams The object is imaged in a certain position. However, when discussing the imaging of a lens in geometric optics, the range is limited to the paraxial region of the optical system. In addition, it is also assumed that the refractive index of the medium does not vary with the wavelength of light. Only in the object point and the light are limited to the paraxial region in the conditions, in order to achieve the ideal image and we are mostly encountered with the continuous spectrum of complex color light, the refractive index of the medium is with the wavelength