红外双波段折衍混合光学-数字联合系统设计

Optical-Digital Joint Design of a Dual-Waveband Infrared Refractive-Diffractive System

传统单层衍射元件的衍射效率在入射波长偏离中心波长时急剧下降,因此在宽波段红外系统中应用时会导致成像模糊。通过分析视场对含衍射元件系统点扩散函数(PSF)模型的影响,提出了减小视场影响的光学-数字联合设计方法;该方法通过将优化的权重赋予不同的衍射级次,使系统的PSF不随视场变化,同时将单层衍射元件中心波长设计在中波,在长波波段利用所构建的PSF模型通过图像重建达到双波段成像的目的。采用该方法设计了红外双波段折衍混合系统,在中波波段,该系统在17 lp/mm处的MTF为0.7;长波重建图像在主观上明显清晰,多个图像质量评价函数均有所提高。结果表明,该设计方法可以实现单层衍射元件在红外双波段上的应用。

The diffraction efficiency of the traditional single-layer diffractive optical elements(SLDOEs)decreases drastically when the wavelength deviates from the center wavelength,causing image blurring when the elements are used in a wide-waveband infrared system.In this study,we analyze the influence of the field of view on the point spread function(PSF)model of the system containing diffractive optical elements.In addition,we propose an optical-digital joint design method for reducing the influence of the field of view.In this method,the PSF is constant with respect to the field of view by assigning optimization weights to different diffractive orders.Further,the center wavelength of the SLDOE is designed in the medium waveband.The PSF model is used for reconstructing the blurred image in the long waveband to achieve dual-waveband imaging.A dual-waveband infrared refractive-diffractive system is designed using this method.The MTF with respect to the medium waveband at 17 lp/mm is 0.7.The reconstructed image in the long waveband is subjectively clear,and several image quality assessment function values are improved.Results show that the proposed design method enables the application of SLDOEs in dual-waveband infrared systems.