Method and apparatus for wavefront measurement that resolves the 2-pi ambiguity in such measurement and adaptive optics systems utilizing same

Abstract

An improved wavefront sensor for characterizing phase distortions in incident light including optical elements that spatially sample the incident light and form a dispersed spot with a fringe pattern corresponding to samples of the incident light. An imaging device captures an image of the dispersed spot with said fringe pattern formed by said optical elements. And an image processor that analyzes the spectral components of the fringe pattern of a given dispersed spot to derive a measure of the local phase distortion without ambiguity in the corresponding sample of incident light. The optical elements may comprise refractive elements, diffractive elements or a combination thereof (such as a grism). The wavefront sensor may be part of an adaptive optic system (such as a large-aperture space telescope) to enable the measurement and correction of large phase steps across adjacent mirror segments of a deformable mirror.

1 - 21 . (canceled)  
   
   
       23 - 24 . (canceled)  
   
   
       25 . A dispersed Hartmann sensor, comprising: 
 a Hartmann lenslet in combination with a dispersive element, whereby a Hartman spot formed by light passing through said Hartmann lenslet is dispersed at an angle to a phase step of said light.    
   
   
       26 . A sensor according to  claim 25 , wherein said angle is zero so that said light passing through said Hartmann lenslet is dispersed parallel to said phase step of said light.  
   
   
       27 . A sensor according to  claim 25 , wherein said dispersive element is a refractive element.  
   
   
       28 . A sensor according to  claim 25 , wherein said dispersive element is a diffractive element.  
   
   
       29 . A sensor according to  claim 25 , wherein said dispersive element is a combination of a diffractive element and a refractive element.  
   
   
       30 . A sensor according to  claim 29 , wherein said dispersive element is a grism.  
   
   
       31 . A sensor according to  claim 29 , wherein said dispersive element is a holographic grating.  
   
   
       32 . A mirror array, comprising: 
 a first layer having a plurality of mirror segments, each mirror segment consisting of a center portion and a surrounding non-center portion;    a second layer having a plurality of Hartmann subapertures and a plurality of dispersed Hartmann subapertures;    said Hartmann subapertures being arranged over said center portions of said plurality of mirror segments; and    said dispersed Hartmann subapertures being arranged over those edges where said plurality of mirror segments join one another.    
   
   
       33 . A method for measuring the size of a discontinuity in a wavefront of light, comprising the steps of: 
 forming a single image of said wavefront;    dispersing said image in wavelength using a combination of a Hartman lenslet and a dispersive element; and    analyzing said dispersed image along a dispersion direction of said dispersed image to measure the size of said discontinuity.    
   
   
       34 . A system for measuring the size of a discontinuity in a wavefront of light, comprising: 
 means for forming a single image of said wavefront;    means for dispersing said image in wavelength using a combination of a Hartman lenslet and a dispersive element; and    means for analyzing said dispersed image along a dispersion direction of said dispersed image to measure the size of said discontinuity.    
   
   
       35 - 37 . (canceled)