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Ultraviolet (UV) radiation of 200nm-300nm waveband from the sun is absorbed by atmosphere, which is often
referred to the solar-blind region of the solar spectrum. Solar-blind characteristics of this waveband have important
application value, especially in military fields. The application of solar-blind waveband has developed very
rapidly, which is receiving more and more attention. Sometimes, to test the performance of a UV optical system, a
standard solar-blind UV target simulator is needed as the UV light source. In this paper, an optical system of a solar-blind
UV target simulator is designed with waveband 240nm-280nm. To simulate a far UV target, the focal length of this UV
optical system needs to be long. Besides, different field of view (FOV) of the system should meet aplanatic condition.
The optional materials are very few for UV optical systems, in which only CaF2 and JGS1 are commonly used. Various
aberrations are difficult to be corrected. To save production cost and enhance the precision of fabrication and test,
aspheric surfaces and binary elements are not adopted in the system. Moreover, doublet or triplet cannot be used in UV
optical system considering possible cracking for different thermal expansion coefficients of different materials. After
optimization, the system is composed of 4 lenses with focal length 500mm. MTF curves of different FOV coincide
together. The maximum RMS radius of the optimized system has almost the same size as Airy disk, which proves the
good image quality after system optimization. The aplanatic condition is met very well in this system. In the spot
diagram, root mean square (RMS) radius changes from 3 microns to 3.6 microns, which has similar size with Airy disk
and meets aplanatic condition very well. This optical system of solar-blind UV target simulator also has relatively loose
tolerance data, which can prove the system is designed in an optimal state.
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