基于波前编码技术的红外系统温度敏感性的研究

波前编码技术是在成像系统的光阑面插入一个非球面相位板,得到一个中间模糊图像,并通过数字图像处理得到清晰图像。波前编码使得成像系统对很多离焦像差不敏感,例如温度引起的像差。这使得该技术可以应用于红外成像系统中,同时可以增大系统的焦深。设计了一个有效焦距f′为35mm,光圈F为2,工作波长为8~12μm的红外成像系统,并且通过数值模拟温度-20°C至60°C的改变,得出波前编码系统在不同温度不同物距下的MTF和PSF基本一致,最后通过数字滤波,可以在大温差的情况下重建大景深清晰图像。

The research on temperature sensitivity of infrared system based on wavefront coding technique

Wavefront coding is two-step imaging technique.By adding an aspheric phase mask at the pupil of an optical system,an intermediate blur image is obtained,and the sharp image can be obtained with the digital image process.Wavefront coding can make the system insensitive to many defocus aberrations,such as the aberration which is caused by the temperature change.So this technique can be applied in the infrared imaging system,and can also extend the depth of field.This paper provides an infrared imaging system whose effective focal length f′=35mm,F=2,and operating wavelength is between 8μm and 12μm.The results show that there is consistency of the modulation transfer function(MTF) and point spread function(PSF) within large temperatures range from-20°C to 60°C.Consequently,sharp images can be obtained with digital filter within large field depth and large temperature range.