Wavefront coded imaging systems

• US 6,940,649 B2
• Filed: 04/04/2003
• Issued: 09/06/2005
• Est. Priority Date: 02/03/1995
• Status: Expired due to Term

• Current Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Original Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Inventors: Dowski, Edward Raymond Jr.
• Primary Examiner(s): Assaf, Fayez G.
• Application Number:
  US10/407,708
• Publication Number:
  US 20040004766A1
• Time in Patent Office: 886 Days
• Field of Search: 359/558, 359/559, 359/563, 359/564, 359/11, 359/29, 382/312, 382/210, 382/212, 356/3, 356/394
• US Class Current: 359/558
• CPC Class Codes: G02B 27/0012 Optical design, e.g. procedures, algorithms, optimisation routines
• 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 5/00 Optical elements other than lenses light guides G02B6/00; optical logic elements G02F3/00

Abstract

The present invention provides improved Wavefront Coding imaging apparatus and methods composed of optics, a 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, thereby producing clear images.

Claims

1. Imaging apparatus for imaging an object onto a detector, comprising:

a lens structure constructed and arranged between the object and the detector to produce transverse ray intercept curves which are sloped substantially straight lines;

a wavefront coding element constructed and arranged between the object and the detector to affect a phase of light transmitted by the wavefront coding element such that a modulation transfer function of the lens structure and wavefront coding element has reduced variation, over a range of spatial frequencies and caused by aberrations of the lens structure, as compared to a modulation transfer function of the lens structure without the wavefront coding element; and

means for post-processing data from the detector to generate an image with an improved modulation transfer function, over the range of spatial frequencies, as compared to the modulation transfer function of the lens structure and the wavefront coding element.

2. The apparatus of claim 1 wherein the aberrations include one or more of the following:

spherical aberration;

petzval curvature;

astigmatism;

field curvature;

temperature induced misfocus aberration;

pressure induced misfocus aberration; and

mechanical induced misfocus aberrations.

3. The apparatus of claim 2, the mechanical induced misfocus aberrations comprising one or more of a fabrication error, an assembly error, drift, and wear.

4. The apparatus of claim 1 wherein the wavefront coding element is formed substantially at an aperture stop of the imaging apparatus.

5. The apparatus of claim 1 wherein the lens structure comprises a single lens, a lens length from a front surface of the single lens to the detector being less than 10 mm.

6. The apparatus of claim 5 wherein the wavefront coding element is formed on the single lens.

7. The apparatus of claim 1 wherein the detector is an analog detector.

8. The apparatus of claim 1 wherein the detector is a digital detector.

9. Imaging apparatus for imaging an object onto a detector, comprising:

a lens structure constructed and arranged between the object and the detector, and at an aperture stop or conjugate of the aperture stop of the apparatus, to produce transverse ray intercept curves which are sloped substantially straight lines; and

at least one surface of the lens structure forming a wavefront coding element to affect a phase of light transmitted by the wavefront coding element so as to alter an optical transfer function of the imaging apparatus such 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.

10. The apparatus of claim 9 wherein the lens structure comprises a single lens, a lens length from a front surface of the single lens to the detector being less than 5 mm.