US Patent 8390932 Device for acquiring equally blurred intermediate images

A device for acquiring equally blurred intermediate image to realize Extension of DOF imaging is characterized in that: the lens of said device produces space-invariant and approximately equal psf output in the designed range of the depth-of-field; the lens realizing space-invariant transfer characteristic is a multi-focal points lens with ray compensation; the angle of the ray guided by the multi-focal point changes in response to the object distance, but the corresponding position and energy distribution of the light spot on the image surface remain constant substantially.