Research On The Modified Image Quality Analysis Model For Hybrid Refractive/Diffractive Systems

The modified image quality analysis model for hybrid refractive/diffractive systems is studied in this disquisition, and the characteristic of diffractive optical elements (DOEs), the diffraction efficiency, the modulate trasfer function (MTF) of hybrid refractive/diffractive systems and the manufacture of DOE are discussed simultaneously. From the studies about the design, manufacture and test of DOE, and from some other countries′investigations about the correlative research, we found that the measured MTFs of some hybrid refractive/diffractive systems were similar as the designed MTFs, and that some measured MTFs were lower than designed MTFs which make the effective working waveband narrow. These investigations illuminate that the image quality analysis models for hybrid refractive/diffractive systems are not precision and not perfect in the current optical design software. We build a more precise image quality analysis models for hybrid refractive/diffractive systems base upon the research on the image quality analysis models for the existing hybrid refractive/diffractive systems. An example application is analyzed by the optical design software and the mathematic software, and which ensure the application of hybrid refractive/diffractive systems in the wide waveband. This work perfect the image quality analysis models for hybrid refractive/diffractive systems, provide a direction for the accurate design of hybrid refractive/diffractive systems, and the result can be applied into the optical design field widely.Several elementary characteristics of the DOE are sdudied firstly in this paper: the dispersion characteristics are analyzed for diffractive elememts which include DOE, harmonic diffractive optical element (HOE) and multi-layer diffractive optical element (MOE); the expression of diffraction efficiency of DOE is deduced for the continuous relief surface structure and N-step approximate surface structure; the design method and the diffraction efficiency of MOE are addressed with the illustration of the double-layer diffractive optical element; and in addition, the relationship between the diffraction efficiency and MTF is discussed.Based upon the research on the tradition image quality analysis models of hybrid refractive/diffractive systems, a modified phase function model of DOE in the hybrid refractive/diffractive system is built. This model modified the ideal phase function of DOE provided by common optical design software by calculating the additional phase diffrence (APD) introduced by dispersion, incidence angles and manufacture errors. With this model, the MTF of hybrid refractive/diffractive systems is also modified by the data exchange between the optical design software and mathematic software, and the accurate image quality analysis result is obtained. To verify the validity and practicability of the model, the image quality of an existing lightweight hybrid refractive/diffractive CCD camera system is analyzed with the new model, and the actual MTF of the CCD camera system is measured to make a comparation with the analysis result.Partial research on the manufactue of DOE is gone along in the paper. Several tadition manufacture methods of DOE are intoduced, and a new method to fabricate the DOE with 3-D relief surface in hybrid sol-gel glass material on curved substrate using the laser direct writer is advanced. Three types DOEs with different periods are fabricated, and the optical tests are processed on the fabricated DOEs. The feasibility and the potential of this method are testified by the comparation between the test result and simulation result.