SYSTEMS AND METHODS OF PHASE DIVERSITY WAVEFRONT SENSING

• US 20090185132A1
• Filed: 10/28/2008
• Published: 07/23/2009
• Est. Priority Date: 10/29/2007
• Status: Active Grant

• Current Assignee: AMO Development LLC (Johnson & Johnson)
• Original Assignee: Amo Wavefront Sciences LLC (Johnson & Johnson)
• Inventors: GREENAWAY, Alan H., FAICHNIE, David M., CRAIK, Graham N., PULASKI, Paul, CAMPBELL DALGARNO, Heather I., RAYMOND, Thomas D., NEAL, Daniel R., FARRER, Stephen W.
• Granted Patent: US 8,118,429 B2
• Time in Patent Office: Days
• US Class Current: 351/205
• 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
• CPC Class Codes: G01M 11/0292 of objectives by measuring the optical modulation transfer function photometry G01J

Abstract

A phase diversity wavefront sensor includes an optical system including at least one optical element for receiving a light beam; a diffractive optical element having a diffractive pattern defining a filter function, the diffractive optical element being arranged to produce, in conjunction with the optical system, images from the light beam associated with at least two diffraction orders; and a detector for detecting the images and outputting image data corresponding to the detected images. In one embodiment, the optical system, diffractive optical element, and detector are arranged to provide telecentric, pupil plane images of the light beam. A processor receives the image data from the detector, and executes a Gerchberg-Saxton phase retrieval algorithm to measure the wavefront of the light beam.

Claims

1. A phase diversity wavefront sensor, comprising:

an optical system including at least one optical element for receiving a light beam;

a diffractive optical element having a diffractive pattern defining a filter function, the diffractive optical element being arranged to produce, in conjunction with the optical system, images from the light beam associated with at least two diffraction orders; and

a detector for detecting the images and outputting image data corresponding to the detected images,

wherein the optical system, diffractive optical element, and detector are arranged to provide telecentric, pupil plane images of the light beam.

2. The phase diversity wavefront sensor of claim 1, wherein the filter function is quadratic.

3. The phase diversity wavefront sensor of claim 1, wherein the filter function is non-quadratic and has non-mixed symmetry.

4. The phase diversity wavefront sensor of claim 1, wherein the diffractive optical element is a diffraction grating.

5. The phase diversity wavefront sensor of claim 1, further comprising a processor adapted to receive the image data from the detector, and to execute a Gerchberg-Saxton phase retrieval algorithm to measure the wavefront of the light beam.

6. The phase diversity wavefront sensor of claim 1, wherein the optical system includes a plurality of optical elements all having fixed positional relationships to the diffractive optical element and the detector.

7. The phase diversity wavefront sensor of claim 1, wherein none of the optical elements in the optical system are adjustable.

8. The phase diversity wavefront sensor of claim 1, wherein the at least one optical element is at least one of a lens, a mirror, or a second diffractive optical element.

9. The phase diversity wavefront sensor of claim 1, wherein the at least one optical element and the diffractive optical element are combined into a single optical element.

10. A method of measuring a wavefront of an optical system including a multifocal element, the method comprising:

providing a light beam to a lens, the lens being a refractive multifocal lens, a diffractive multifocal lens, or a diffractive monofocal lens;

directing light from the lens to a phase diversity wavefront sensor, comprising an optical system including at least one optical element for receiving a light beam, and a diffractive optical element the shape of which is defined by a filter function, the diffractive optical element being arranged to produce in conjunction with the optical system images of the light beam associated with at least two diffraction orders; and

a detector for detecting the images and outputting image data corresponding to the detected images; and

measuring the wavefront of the light from the lens using the image data output by the detector.

11. The method of claim 10, wherein the optical system, diffractive optical element, and detector are arranged to provide telecentric, pupil plane images of the light beam.

12. The method of claim 10, wherein the filter function is quadratic.

13. The method of claim 10, wherein the filter function is non-quadratic and has non-mixed symmetry.

14. The method of claim 10, wherein the diffractive optical element is a diffraction grating.

15. The method of claim 10, further comprising processing the image data from the detector with a Gerchberg-Saxton phase retrieval algorithm to measure the wavefront of the light beam.

16. The method of claim 10, wherein the optical system includes a plurality of optical elements all having fixed positional relationships to the diffractive optical element and the detector during the measurement.

17. The method of claim 10, wherein the lens is an intraocular lens (IOL) or a contact lens.

18. The method of claim 10, wherein the lens is implanted in a human patient.

28. The method of claim 18 where the object is a human cornea and the first surface is the anterior corneal surface and the second surface is the posterior corneal surface.

19. A method of measuring a wavefront of an object having first and second surfaces, the method comprising:

providing a light beam to the object;

directing light from the lens to a phase diversity wavefront sensor, the lens being a refractive multifocal lens, a diffractive multifocal lens, or a diffractive monofocal lens, the phase diversity wavefront sensor comprising an optical system including at least one optical element for receiving a light beam, and a diffractive optical element the shape of which is defined by a filter function, the diffractive optical element being arranged to produce in conjunction with the optical system images of the light beam associated with at least two diffraction orders; and

a detector for detecting the images and outputting image data corresponding to the detected images; and

simultaneously measuring the first and second surfaces of the object using the image data output by the detector.

20. The method of claim 19, wherein the optical system, diffractive optical element, and detector are arranged to provide telecentric, pupil plane images of the light beam.

21. The method of claim 20, wherein the filter function is quadratic.

22. The method of claim 19, wherein the filter function is non-quadratic and has non-mixed symmetry.

23. The method of claim 19, wherein the diffractive optical element is a diffraction grating.

24. The method of claim 19, further comprising processing the image data from the detector with a Gerchberg-Saxton phase retrieval algorithm to measure the wavefront of the light beam.

25. The method of claim 19, wherein the optical system includes a plurality of optical elements all having fixed positional relationships to the diffractive optical element and the detector during the measurement.

26. The method of claim 19, wherein the object is a contact lens.

27. The method of claim 26, wherein the contact lens is implanted in a human patient.

29. A method of designing a phase diversity wavefront sensor, the method comprising:

providing one or more analytic solutions for paraxial equations that govern an optical configuration of the phase diversity wavefront sensor;

providing a set of input design parameters for the phase diversity wavefront sensor;

generating a set of output values from the analytical solutions and the input design parameters; and

determining whether the output parameters meet a viability threshold.

30. The method of claim 29, wherein the set of input design parameters include parameters of the optical configuration.

31. The method of claim 30, wherein the set of input design parameters include an input pupil diameter of the optical configuration, a standoff distance between a diffractive optical element and a detector of the phase diversity wavefront sensor, and a wavelength of light to be processed by the phase diversity wavefront sensor.

32. The method of claim 29, wherein the set of input design parameters include parameters of a detector of the phase diversity wavefront sensor.

33. The method of claim 32, wherein the set of input design parameters include a pixel size of the detector and digitization depth of the detector.

34. The method of claim 29, wherein the set of input design parameters include performance characteristics of the phase diversity wavefront sensor.

35. The method of claim 34, wherein the performance characteristics include a spatial resolution of the phase diversity wavefront sensor and a defocus dynamic range of the phase diversity wavefront sensor.

36. The method of claim 29, wherein the set of output design parameters include focal lengths and positions of optical elements in the optical configuration.

37. The method of claim 29, wherein the set of output design parameters include parameters of a diffraction grating of the phase diversity wavefront sensor.

38. The method of claim 29, wherein the set of output design parameters include a defocus sensitivity of the phase diversity wavefront sensor.

39. A phase diversity wavefront sensor, comprising:

an illuminating optical system for delivering light onto a retina of an eye;

a receiving optical system for receiving light reflected by the retina, the receiving optical system comprising a diffractive optical element including a diffraction pattern defining a filter function, the diffractive optical element being arranged to produce, in conjunction with the optical system, at least two images from the light beam associated with at least two diffraction orders;

a detector for detecting the at least two images;

a memory containing instructions for executing a Gerchberg-Saxton phase retrieval algorithm on data produced by the detector in response to the detected images; and

a processor configured to execute the Gerchberg-Saxton phase retrieval algorithm so as to characterize a wavefront produced by the reflected light.

40. The phase diversity wavefront sensor of claim 39, wherein the wavefront is located in a plane through a pupil of the eye.