Wavefront coding interference contrast imaging systems
AssigneeThe Regents of the University of Colorado
InventorsEdward Raymond Dowski, Jr., Carol Jean Cogswell
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Abstract
Contrast Imaging apparatus and methods with Wavefront Coding aspheric optics and post processing increase depth of field and reduce misfocus effects in imaging Phase Objects. The general Interference Contrast imaging system is modified with a special purpose optical element and image processing of the detected image to form the final image. The Wavefront Coding optical element can be fabricated as a separate component, can be constructed as an integral component of the imaging objective, tube lens, beam splitter, polarizer or any combination of such.
Claims32
Apparatus for increasing depth of field and controlling focus related aberrations in an Interference Contrast Imaging system having an illumination source, optical elements for dividing light polarizations, and illumination optics placed before a Phase Object to be imaged, and elements for recombining light polarizations and objective optics after the Phase Object to form an image at a detector, the improvement comprising:
- an optical Wavefront Coding mask having an aperture and placed between the Phase Object and the detector,
- said coding mask being constructed and arranged to alter the optical transfer function of the Interference Contrast Imaging system in such a way that the altered optical transfer function is substantially insensitive to the distance between the Phase Object and the objective optics over a greater range of object distances than was provided by the unaltered optical transfer function,
- wherein the coding mask affects the alteration to the optical transfer function substantially by affecting the phase of light transmitted by the mask;
- and
- a post processing element for processing the image captured by the detector by reversing the alteration of the optical transfer function accomplished by the coding mask.
A method for increasing depth of field and controlling focus related aberrations in a conventional Interference Contrast Imaging system having an illumination source, optical elements for dividing light polarizations, and illumination optics placed before a Phase Object to be imaged, and elements for recombining light polarizations and objective optics after the Phase Object to form an image at a detector, the method comprising the steps of:
- between the Phase Object and the detector, modifying the wavefront of transmitted light with a wavefront coding mask;
- the wavefront modification step selected to alter the optical transfer function of the Interference Contrast Imaging system in such a way that the altered optical transfer function is substantially insensitive to the distance between the Phase Object and the objective optics over a greater range of object distances than was provided by the unaltered optical transfer function;
- and
- post processing the image captured by the detector by reversing the alteration of the optical transfer function accomplished by the mask.
A Wavefront Coding Interference Contrast Imaging system for imaging a Phase Object comprising:
- an illumination source for providing illumination;
- polarizing optics for splitting the illumination into distinct juxtaposed polarizations;
- illumination optics placed between the illumination source and the Phase Object;
- polarizing optics for recombining the illumination polarizations;
- a detector;
- objective optics placed between the Phase Object and the detector to form an image at the detector;
- an optical Wavefront Coding mask having an aperture and placed between the Phase Object and the detector, said mask 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 the distance between the Phase Object and the objective optics over a greater range of object distances than was provided by the unaltered Imaging system optical transfer function, wherein the mask affects the alteration to the optical transfer function substantially by affecting the phase of light transmitted by the mask;
- and
- a post processing element for processing the image captured by the detector by reversing the alteration of the optical transfer function accomplished by the mask.
In an imaging system of the type having partially coherent radiation between an object and an image of the object, the improvement comprising:
- a wavefront coding optical element for modifying a phase function of the partially coherent radiation to increase a depth of field of the image;
- and
- a post processing element for processing the image to modify effects induced by the wavefront coding element in the image so as to generate a final image of the object.
An interference contrast imaging system, comprising:
- an illumination source;
- a polarizer for generating polarized light from the illumination source;
- illumination optics for focusing the polarized light onto a phase object;
- a detector;
- an objective lens, tube lens and wavefront coding element for forming an image of the phase object on the detector, the wavefront coding element modifying phase of a wavefront generating the image;
- a post processor connected with the detector for post processing images from the detector to generate a final image by reversing phase effects induced by the wavefront coding element.
Dependencies are inferred from the claim text.