Extended Depth Of Field Optical Systems

• US 20090109535A1
• Filed: 10/13/2008
• Published: 04/30/2009
• Est. Priority Date: 02/03/1995
• Status: Active Grant

• Current Assignee: Edward Raymond Jr. Dowski, Wade Thomas Jr. Cathey
• Original Assignee: Edward Raymond Jr. Dowski, Wade Thomas Jr. Cathey
• Inventors: Dowski, Edward Raymond JR., Cathey, Wade Thomas JR.
• Granted Patent: US 8,004,762 B2
• Time in Patent Office: Days
• US Class Current: 359/558
• CPC Class Codes: G01S 11/12 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 3/7835 using coding masks
• CPC Class Codes: G02B 21/14 affording illumination for phase-contrast observation
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 27/46 Systems using spatial filters
• CPC Class Codes: G02B 27/52 Phase contrast optics in microscopes G02B21/14
• CPC Class Codes: G02B 5/00 Optical elements other than lenses light guides G02B6/00; optical logic elements G02F3/00
• CPC Class Codes: G02B 7/365 by analysis of the spatial frequency components of the image
• CPC Class Codes: G02B 7/40 using time delay of the reflected waves, e.g. of ultrasonic waves

Abstract

A system for forming an image includes a lens and a phase mask. The image is characterized by an optical transfer function that has no zeros within detected spatial frequencies of a detector that detects the optical image over a larger depth of focus than without the phase mask. The phase mask does not reduce an optical bandpass limited by an aperture of the lens or of the phase mask. A method for generating an optical image includes forming the image with at least one element of an imaging system while modifying wavefront phase without reducing an optical bandpass limited by an aperture of the imaging system. The method also includes detecting the optical image without introducing zeros in an optical transfer function of the imaging system, over detected spatial frequencies within the optical bandpass over an extended depth of focus.

Claims

1. A method for generating an optical image, comprising:

forming an optical image with at least one optical element of an optical imaging system while modifying wavefront phase, wherein modifying phase does not reduce an optical bandpass limited by an aperture of the optical imaging system, and

detecting the optical image over a range of spatial frequencies such that there are no zeros in an optical transfer function of the optical imaging system over detected spatial frequencies within the optical bandpass over an extended depth of focus that is larger than a depth of focus occurring without modifying wavefront phase.

2. The method of claim 1, the step of modifying phase comprising utilizing an optical mask.

3. The method of claim 2, further comprising the step of

post-processing the optical image to remove effects induced by the optical mask, to render an electronic image that is clearer over the extended depth of focus as compared to an electronic image formed without utilizing the optical mask and over the extended depth of focus.

4. A system for forming an image, comprising:

a lens and a phase mask that cooperate to form an optical image characterized by an optical transfer function that has no zeros within detected spatial frequencies of a detector that detects the optical image over a larger depth of focus than without the phase mask, wherein the phase mask does not reduce an optical bandpass limited by an aperture of the lens or of the phase mask.

5. The system of claim 4, further comprising means for post-processing a detected optical image to reverse a phase modification induced in the optical image by the phase mask, to generate an electronic image that is clear over an extended depth of field.