Wavefront coded imaging systems

Abstract

The present invention provides improved Wavefront Coding imaging apparatus and methods composed of optics, detector, and processing of the detected image. The optics are constructed and arranged to have the characteristic that the transverse ray intercept curves form substantially straight, sloped lines. The wavefront coding corrects for known or unknown amounts of “misfocus-like” aberrations by altering the optical transfer function of the imaging apparatus in such a way that the altered optical transfer function is substantially insensitive to aberrations. Post processing then removes the effect of the coding, except for the invariance with regard to aberrations, producing clear images.

What is claimed is:  
     
         1 . Imaging apparatus for imaging an object onto a detector comprising: 
 a lens structure;    the lens structure constructed and arranged to produce transverse ray intercept curves which are sloped substantially straight lines;    a wavefront coding element positioned between the object and the detector;    the coding element being constructed and arranged to alter the optical transfer function of the imaging apparatus in such a way that the altered optical transfer function is substantially insensitive to focus-related aberrations over a greater range of aberrations than was provided by the unaltered optical transfer function; and    means for post processing;    wherein the coding element affects said alteration to the optical transfer function substantially by affecting the phase of light transmitted by said wavefront coding element.    
     
     
         2 . The apparatus of  claim 1  wherein the aberrations include one or more of the following: 
 misfocus;  
 spherical aberration;  
 petzval curvature;  
 astigmatism;  
 field curvature;  
 chromatic aberration;  
 temperature induced misfocus aberration;  
 pressure induced misfocus aberration;  
 mechanical induced misfocus aberrations.  
 
     
     
         3 . The apparatus of  claim 1  wherein the coding element is formed substantially at an aperture stop of the imaging system.  
     
     
         4 . The apparatus of  claim 1  wherein the lens structure comprises an IR imaging system.  
     
     
         5 . The apparatus of  claim 1  wherein the post processing means comprises a digital filter.  
     
     
         6 . The apparatus of  claim 1  wherein the lens structure comprises a microscope objective.  
     
     
         7 . The apparatus of  claim 1  wherein the lens structure comprises a single lens.  
     
     
         8 . The apparatus of  claim 7  wherein the coding element is formed on the single lens.  
     
     
         9 . The apparatus of  claim 1  wherein the detector is an analog detector.  
     
     
         10 . The apparatus of  claim 1  wherein the detector is a digital detector.  
     
     
         11 . A single lens imaging system for imaging an object onto a detector comprising: 
 a lens constructed and arranged to produce transverse ray intercept curves which are sloped substantially straight lines;    a wavefront coding element formed on a surface of the lens; the coding element being constructed and arranged to alter the optical transfer function of the imaging system in such a way that the altered optical transfer function is substantially insensitive to focus-related aberrations over a greater range of aberrations than was provided by the unaltered optical transfer function; and    a post processing element;    wherein the coding element affects said alteration to the optical transfer function substantially by affecting the phase of light transmitted by said wavefront coding element.    
     
     
         12 . The system of  claim 11 , wherein the post processing element comprises a digital filter.  
     
     
         13 . The system of  claim 12 , wherein the digital filter comprises a rectangularly separable filter.  
     
     
         14 . The system of  claim 11 , wherein the wavefront coding element is formed on the surface of the lens furthest from the object.  
     
     
         15 . The system of  claim 11 , wherein the lens length is under 10 mm.  
     
     
         16 . The system of  claim 11 , wherein the lens length is under 5 mm.  
     
     
         17 . A microscope objective for imaging an object onto a detector comprising: 
 an element with optical power;    the element with optical power being constructed and arranged to produce transverse ray intercept curves which are sloped substantially straight lines;    a wavefront coding element;    the coding element being constructed and arranged to alter the optical transfer function of the microscope objective in such a way that the altered optical transfer function is substantially insensitive to focus-related aberrations over a greater range of aberrations than was provided by the unaltered optical transfer function; and    a post processing element;    wherein the coding element affects said alteration to the optical transfer function substantially by affecting the phase of light transmitted by said wavefront coding element.    
     
     
         18 . The microscope objective of  claim 17 , wherein the post processing element comprises a digital filter.  
     
     
         19 . The microscope objective of  claim 17 , wherein the element with optical power comprises a single lens.  
     
     
         20 . The microscope objective of  claim 19 , wherein the lens is aspheric.