Study On Correcting Secondary Spuctrum Of Diffactive/Refractive Hybrid Optical System

The possibility of the Optical systems of Hyper-spectral Imaging Spectroscope(HIS) to get higher quality pictures by using hybrid diffractive/ refractive optical system, under the conditions of wide spectrum(spectrum range 420.0-900.0nm) , long focus(450mm) , wide aperture (D= 100mm, F/3.5), wide field angle(2 ω = 3.0° ) has been studied in this dissertation.The method and steps of correcting secondary spectrum have been studied in this dissertation and the focus distribution formula is deduced for 3 pieces diffractive/refractive hybrid optical system to correct secondary spectrum. 3 kinds of apochromatic systems are designed, two of the three are diffractive/ refractive hybrid optical systems, and another one is refractive systems. The comparison of these differences is given.The primary aberration equation of the diffractive/ refractive hybrid thin lens system is solved by the method of P-W-C firstly. Through the combination of 3 pieces of lenses, the diffractive/ refractive hybrid optical system is designed: No.1 and No.3 are common glasses, and No.2 is binary optical lens (BOL). Configuration parameters of binary optical lenses are: the number of steps is 8, the number of ring strips is 60, the minimum line width is 0.0521mm. The longitudinal aberration is good enough in 0.6 and 0.8, 0.9 aperture for the lenses. The maximum inner distance of paraxial (0 aperture) focal of all wave length is 0.25mm. When frequency is 301p/mm, the modulation transfer function(MTF) is near diffractive limit under 0.5 field angle, the modulation transfer function (MTF) is near 0.7 in edge field. The contrast of the two kinds of design shows : the design of diffractive/refractive hybrid optical system is better than the design by using common glasses in every indexes and quality of image, the weight of diffractive/refractive hybrid optical system is 30% lighter than the weight of system designed through using of common glasses. The design of diffractive/refractive hybrid optical system meets the optical design demand of Hyper-spectral Imaging Spectroscope(HIS).The vacuum effect on diffractive/refractive hybrid apochromatic optical system has been studied for the first time, the formula of the pressure corresponding to the effect of image plane is deduced. When thetemperature is changing, the thermal dilatation coefficient of diffractive element is the function of the differential coefficient of base linear dilatation coefficient and image space refractive index, and has no relationship with the refractive index of the base material and the derivative of temperature.