Aperture-divided ultraviolet multiband imaging optical system

Ultraviolet radiation of characteristic free radicals and blackbody radiation in combustion flames is essential to the quantitative analysis of flame temperature and fuel composition. An aperture-divided ultraviolet multiband imaging optical system is designed, which consists of an aperture-divided system and an image-combined system. The lens materials are fused silica and calcium fluoride. By placing multiband ultraviolet filters in each divided channel, the combustion flame can be imaged on the detector's four regions with four ultraviolet bands, including 240 similar to 280 nm, 308 nm, 300 similar to 360 nm, and 390 nm. The parameters of the system are: a 2.85 F-number, a 10 degrees field-of-view, and a 277.2 mm total length. The entrance pupil diameter of the aperture-divided system is 10 mm, and the single-channel focal length is 43.88 mm. The Modulation Transfer Function (MTF) is close to the diffraction limit. The MTF value of the object surface at the edge of the image-combined system reaches 0.45 at 45 lp/mm. After optimizing the combination of the two parts, the MTF value of the total system surpassed 0.5 at 45 lp/mm in Nyquist frequency. Monte Carlo analysis on the tolerances gives a yield rate of more than 20%. The results show that this system is suitable for research and has practical value.