大焦深成像系统的特性研究

PROPERTY STUDY ON LARGE DEPTH OF FOCUS IMAGING SYSTEM

如何增大非相干光学成像系统的焦深已成为一项有意义的研究主题。为了增大焦深 ,通常的做法是缩小相对孔径 ,但这种做法会降低光学系统的光通量、调制传递函数 (MTF)及分辨率 ,而大焦深成像系统通过在光学系统光路中加入一特殊设计的非球面掩模板 ,并用图像处理技术对相位掩模板编码后的图像进行解码得到清晰图像 ,保证了光学系统在维持原有相对孔径的同时扩大其焦深范围 ,使光学系统在离焦范围内有好的图像质量。从光线图和系统的 MTF两个方面对大焦深成像系统的特性进行了分析 ,并对结果进行了讨论。

It has been an active research topic for many years to extend the depth of focus of incoherent optical systems. The traditional method achieving an extended depth of focus is by stopping down the aperture, but the method has suffered two significant deficiencies:decrease of optical power at the image plane, and decrease of image resolution. The large depth of focus imaging system uses generalized aspheric optics to encode images to be invariant to defocus, and digital signal processing to decode the images.The property of the large depth of focus imaging system is analyzed with light chart and MTF, and the result is discussed.