Design method of dual-band synchronous zoom microscope optical system based on coaxial Kohler illumination

The intrinsic properties of the observed object are closely related to its spectral information, to extend the imaging spectral range of a continuous zoom microscope to obtain more detailed intrinsic properties of the object, this paper proposes a design method of dual-band simultaneous zoom microscope optical system based on the coaxial Koehler uniform illumination. First, the imaging principle of the dual-band simultaneous zoom microscope optical system is theoretically analyzed, and we propose to split the front fixed group of the zoom system into a collimation lens group and a converging lens group to realize the compact design of the system. Then, two different rear fixed groups are used to correct the residual aberration, and a method for solving the initial structure of the dual-band simultaneous zoom microscope optical system is proposed. Finally, a dual-band synchronous zoom microscope optical system is designed using the method proposed in this paper. The design results show that the imaging magnification of the visible (VIS) band is -0.4 to -4.0, the simultaneous imaging magnification ranges are -0.4 to -0.8 in the VIS and short-wave infrared (SWIR) bands, and the magnification difference of its simultaneous zoom imaging is less than 1.25%. In addition, the system has the advantages of good imaging quality, clever design of coaxial illumination, and compact structure, thus verifying the feasibility of the design method.