Iterative fourier reconstruction for laser surgery and other optical applications

• US 7,731,363 B2
• Filed: 03/18/2008
• Issued: 06/08/2010
• Est. Priority Date: 06/20/2003
• Status: Expired due to Term

• Current Assignee: Amo Manufacturing Usa, Llc (Johnson & Johnson)
• Original Assignee: Amo Manufacturing Usa, Llc (Johnson & Johnson)
• Inventors: Gross, Erik, Chernyak, Dimitri, Dai, Guangming, Campbell, Charles E., Somani, Seema
• Primary Examiner(s): Schwartz; Jordan M.
• Assistant Examiner(s): JONES, JAMES
• Application Number:
  US12/050,651
• Publication Number:
  US 20080212031A1
• Time in Patent Office: 812 Days
• Field of Search: 351/246
• US Class Current: 351/246
• CPC Class Codes: A61B 3/1015 for wavefront analysis
• CPC Class Codes: G01J 9/00 Measuring optical phase difference devices or arrangements for controlling the phase of light beams G02F1/01; Determining degree of coherence; Measuring optical wavelength spectrometry G01J3/00

Abstract

Methods, systems and software for determining an optical surface model for an optical tissue system using Fourier transformation algorithms. A method of reconstructing optical tissues of an eye comprises transmitting an image through the optical tissues of the eye. The surface gradients from the transmitted image are measured across the optical tissues of the eye. A Fourier transform algorithm is applied to the surface gradients to reconstruct an optical surface model that corresponds to the optical tissues of the eye.

Claims

1. A method of determining an optical surface model for an optical tissue system of an eye, comprising:

inputting optical data from the optical tissue system of the eye, the optical data comprising a set of local gradients within an aperture;

establishing a gradient field based on the set of local gradients;

applying a first reconstruction algorithm to the set of local gradients at a first spatial frequency limit to provide a first reconstruction;

applying a second reconstruction algorithm to the set of local gradients at a second spatial frequency limit to provide a second reconstruction, wherein the second spatial frequency limit is less than the first spatial frequency limit;

determining which of the first reconstruction and the second reconstruction is more accurate; and

determining the optical surface model based on the more accurate reconstruction.

2. The method according to claim 1, wherein the first reconstruction algorithm comprises a Fourier reconstruction algorithm.

3. The method according to claim 1, wherein the second reconstruction algorithm comprises a Zernike reconstruction algorithm.

4. The method according to claim 1, wherein the step of determining which of the first reconstruction and the second reconstruction is more accurate comprises determining an accuracy of a wavefront elevation map of the first reconstruction, determining an accuracy of a wavefront elevation map of the second reconstruction, and comparing the accuracy of the wavefront elevation map of the first reconstruction with the accuracy of the wavefront elevation map of the second reconstruction.

5. The method according to claim 1, wherein the step of determining which of the first reconstruction and the second reconstruction is more accurate comprises determining an accuracy of a gradient map of the first reconstruction, determining an accuracy of a gradient map of the second reconstruction, and comparing the accuracy of the gradient map of the first reconstruction with the accuracy of the gradient map of the second reconstruction.

6. The method according to claim 1, wherein the step of determining which of the first reconstruction and the second reconstruction is more accurate comprises determining an accuracy of a surface of the first reconstruction, determining an accuracy of a surface of the second reconstruction, and comparing the accuracy of the surface of the first reconstruction with the accuracy of the surface of the second reconstruction.

7. The method according to claim 1, wherein the first spatial frequency limit comprises a Nyquist limit.

8. A method of determining an optical surface model for an optical tissue system of an eye, comprising:

inputting optical data from the optical tissue system of the eye, the optical data comprising a set of local gradients within an aperture;

establishing a gradient field based on the set of local gradients;

deriving a reconstruction from the gradient data by applying a first reconstruction algorithm at a first spatial frequency limit, and by applying a second reconstruction algorithm at a second spatial frequency limit, wherein the second spatial frequency limit is less than the first spatial frequency limit; and

determining the optical surface model based on the reconstruction.

9. The method according to claim 8, wherein the first reconstruction algorithm comprises a Fourier reconstruction algorithm.

10. The method according to claim 8, wherein the second reconstruction algorithm comprises a Zernike reconstruction algorithm.

11. The method according to claim 8, wherein the first spatial frequency limit comprises a Nyquist limit.

12. A method of reconstructing optical tissues of an eye, the method comprising:

transmitting an image through the optical tissues of the eye;

measuring surface gradients from the transmitted image across the optical tissues of the eye;

applying a Fourier transform algorithm to the surface gradients to reconstruct a surface that corresponds to the optical tissues of the eye; and

correcting an off-center alignment in the reconstructed and

computing a correction ablation pattern based on the optical tissues of the eve as indicated by the Fourier reconstructed surface, the computing comprising deriving a proposed change in elevations of the optical tissue so as to effect a desired change in optical properties of the eye.

13. The method according to claim 12, comprising adding a mean gradient field to remove a tilt from the reconstructed surface.

14. The method according to claim 12, comprising aligning the reconstructed surface of the optical tissues of the eye with an image of the eye that was obtained during the measuring of the surface gradients.

15. The method according to claim 12, further comprising modifying the optical tissue surface according to the correction ablation pattern by laser ablation.

16. The method according to claim 12, wherein measuring the surface gradients comprises uniformly sampling the transmitted image over an aperture.

17. The method according to claim 16, wherein the aperture comprises a pupil of the eye.

18. The method according to claim 12, wherein measuring surface gradient data is carried out with a Hartman n-Shack sensor assembly.