Spatial wavefront analysis and 3D measurement

• US 7,609,388 B2
• Filed: 10/16/2002
• Issued: 10/27/2009
• Est. Priority Date: 01/24/2002
• Status: Active Grant

• Current Assignee: ICOS Vision Systems Incorporated (Eli Lilly and Company)
• Original Assignee: ICOS Vision Systems Incorporated (Eli Lilly and Company)
• Inventors: Lanzmann, Emmanuel, Wolfling, Shay, Banitt, David, Levavi, Shay, Saban, Yoram, Weitzman, Yosi, Arieli, Yoel
• Primary Examiner(s): Lee; Hwa S
• Application Number:
  US10/499,758
• Publication Number:
  US 20050007603A1
• Time in Patent Office: 2,568 Days
• Field of Search: 356/450, 356/521, 356513-516, 356/499, 356/489, 356/495
• US Class Current: 356/512
• CPC Class Codes: G01B 9/02087 Combining two or more images of the same region
• CPC Class Codes: G01J 9/02 by interferometric methods using interferometers for measuring optically the linear dimensions of objects G01B9/02
• CPC Class Codes: G11B 7/005 Reproducing G11B7/0065 takes precedence
• CPC Class Codes: G11B 7/0051 involving phase depth effects
• CPC Class Codes: G11B 7/24088 for storing more than two values, i.e. multi-valued recording for data or prepits

Abstract

A method of wavefront (100) analysis including applying a transform to the wavefront, applying a plurality of different phase changes (110, 112, 114) to the transformed wavefront (108), obtaining a plurality of intensity maps (130, 132, 134) wherein the plurality of different phase changes are applied to region of the transformed wavefront, corresponding to a shape of the light source.

Claims

1. A method of wavefront analysis comprising:

utilizing a light source to illuminate an object and to obtain a wavefront having an amplitude and a phase;

obtaining a plurality of differently phase changed transformed wavefronts corresponding to said wavefront being analyzed, including;

applying a transform to said wavefront being analyzed thereby to obtain a transformed wavefront; and

applying a plurality of different phase changes to said transformed wavefront, thereby to obtain a plurality of differently phase changed transformed wavefronts;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts by phase manipulation; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed, wherein said plurality of different phase changes are applied to a region of said transformed wavefront, said region having a shape of said light source.

2. A method according to claim 1 and wherein said light source comprises an elongate light source.

3. A method of wavefront analysis comprising:

utilizing a light source to illuminate an object and to obtain a wavefront having an amplitude and a phase;

obtaining a plurality of differently phase changed transformed wavefronts corresponding to said wavefront being analyzed, including;

applying a transform to said wavefront being analyzed thereby to obtain a transformed wavefront; and

applying a plurality of different phase changes to said transformed wavefront, thereby to obtain a plurality of differently phase changed transformed wavefronts;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts by phase manipulation; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed, wherein said plurality of different phase changes are applied to regions of said transformed wavefront, said regions having the form of a grating.

4. A method of wavefront analysis comprising:

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed, and wherein obtaining a plurality of differently phase changed transformed wavefronts comprises;

applying a transform to said wavefront being analyzed thereby to obtain a transformed wavefront; and

applying a plurality of different phase changes to said transformed wavefront, thereby to obtain a plurality of differently phase changed transformed wavefronts, and wherein said transformed wavefront comprises a plurality of different polarization components; and

said plurality of different phase changes are effected by using a birefringent phase changer to apply different phase changes to said plurality of different polarization components of said transformed wavefront.

5. A method of wavefront analysis comprising:

obtaining two differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase;

obtaining two intensity maps of said two phase changed transformed wavefronts;

employing interference between said two intensity maps to generate a third intensity map; and

employing said two intensity maps and said third intensity map to obtain an output indicating said amplitude and phase of said wavefront being analyzed.

6. A method of wavefront analysis comprising:

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed, and wherein obtaining a plurality of differently phase changed transformed wavefronts comprises;

applying a transform to said wavefront being analyzed thereby to obtain a transformed wavefront; and

applying a plurality of different phase changes to said transformed wavefront, thereby to obtain a plurality of differently phase changed transformed wavefronts, and wherein;

said plurality of different phase changes includes spatial phase changes;

said plurality of different spatial phase changes are effected by applying a spatially uniform, time-varying spatial phase change to part of said transformed wavefront;

said transform applied to said wavefront being analyzed is a Fourier transform;

said plurality of different spatial phase changes comprises at least three different phase changes, said plurality of intensity maps comprises at least three intensity maps; and

said employing step comprises;

expressing said wavefront being analyzed as a first complex function which has an amplitude and phase identical to said amplitude and phase of said wavefront being analyzed;

expressing said plurality of intensity maps as a function of said first complex function and of a spatial function governing said spatially uniform, time-varying spatial phase change;

defining a second complex function, having an absolute value and a phase, as a convolution of said first complex function and of a Fourier transform of said spatial function governing said spatially uniform, time-varying spatial phase change;

expressing each of said plurality of intensity maps as a third function of;

said amplitude of said wavefront being analyzed;

a square of said absolute value of said second complex function;

a difference between said phase of said wavefront being analyzed and said phase of said second complex function; and

a known phase delay produced by one of said at least three different phase changes which each correspond to one of said at least three intensity maps;

solving said third function to obtain said amplitude of said wavefront being analyzed, said absolute value of said second complex function and said difference between said phase of said wavefront being analyzed and said phase of said second complex function;

solving said second complex function to obtain said phase of said second complex function; and

obtaining said phase of said wavefront being analyzed by adding said phase of said second complex function to said difference between said phase of said wavefront being analyzed and said phase of said second complex function, said square of said absolute value of said second complex function is obtained by approximating a square of said absolute value to a polynomial of a given degree; and

said employing step comprises computing a confidence level map characterizing confidence in each of a plurality of portions of said phase of said wavefront being analyzed, by comparing said square of said absolute value of said second complex function to said polynomial of a given degree, the confidence level map comprising a plurality of confidence levels respectively corresponding to a plurality of portions within said intensity maps.

7. A method according to claim 6 wherein said step of applying a plurality of different phase changes is performed at least twice using at least two pluralities of different phase changes and wherein said step of employing is performed at least twice using said at least two pluralities of different phase changes, thereby to obtain at least two values for said phase of said wavefront being analyzed, and wherein the method also comprises using the at least two confidence level maps resulting from performing said confidence level map computation step at least twice, to combine said at least two values for said phase of said wavefront being analyzed into a single value.

8. A method according to claim 7 wherein said step of combining comprises selecting one value from among said at least two values for said phase of said wavefront being analyzed, wherein said selected value is the value of the phase having the highest value of said confidence levels.

9. A method according to claim 7 wherein said step of combining comprises computing a weighted average of said at least two values for said phase of said wavefront being analyzed, using the confidence levels included in said at least two confidence level maps as weights for the at least two values respectively.

10. A method according to claim 6 and also comprising computing the confidence in each of a plurality of portions of said phase, using, for at least one portion, a phase value which is different from that measured for the at least one portion and, if the confidence computed for an individual portion using the different phase value exceeds the confidence computed using the measured phase value, replacing the measured phase value for the individual portion with the different phase value.

11. A method according to claim 6 wherein the wavefront being analyzed comprises a plurality of wavefront components having different wavelengths, and said plurality of differently phase changed transformed wavefronts are obtained by applying a phase change to said plurality of different wavelength components of said wavefront being analyzed, and wherein said wavefront being analyzed comprises a plurality of different wavelength components;

and said plurality of differently phase changed transformed wavefronts are obtained by applying a phase change to said plurality of different wavelength components of said wavefront being analyzed.

12. A method according to claim 11 wherein said step of applying a plurality of different phase changes is performed for each of the plurality of wavefront components, and wherein said step of employing is performed for each of the plurality of wavefront components, thereby to obtain a corresponding plurality of values for said phase of said wavefront being analyzed, and wherein the method also comprises using the at least confidence level maps resulting from performing said confidence level map computation step a plurality of times, to combine said plurality of values for said phase of said wavefront being analyzed into a single value.

13. A method of wavefront analysis comprising:

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed, and wherein said step of employing also comprises normalizing each of the plurality of intensity maps to obtain a plurality of intensity maps having the same sum of intensity values.

14. A method according to claim 13 and wherein said plurality of differently phase changed transformed wavefronts are obtained so as to maximize contrast between said plurality of intensity maps and to minimize effects of noise on said phase of said wavefront being analyzed.

15. A method of phase change analysis comprising:

obtaining a phase change analysis wavefront which has an amplitude and a phase;

applying a transform to said phase change analysis wavefront thereby to obtain a transformed wavefront;

applying at least one phase change to said transformed wavefront, thereby to obtain at least one phase changed transformed wavefront;

obtaining at least one intensity map of said at least one phase changed transformed wavefront; and

employing said at least one intensity map to obtain an output indication of said at least one phase change applied to said transformed phase change analysis wavefront.

16. A method according to claim 15 and wherein said obtaining a phase change analysis wavefront comprises reflecting light off a known object and using the light reflected off the known object as said phase change analysis wavefront.

17. A method according to claim 15 and wherein said obtaining a phase change analysis wavefront comprises transmitting light through a known object and using the transmitted light exiting the known object as said phase change analysis wavefront.

18. A method according to claim 15 and wherein said applying at least one phase change to said transformed wavefront comprises applying a phase delay value to an area within said transformed wavefront and wherein said step of employing said at least one intensity map comprises obtaining an output indication delimiting said area.

19. A method according to claim 18 wherein said obtaining a phase change analysis wavefront comprises reflecting light off a known object and using the light reflected off the known object as said phase change analysis wavefront.

20. A method according to claim 18 wherein said obtaining a phase change analysis wavefront comprises transmitting light through a known object and using the transmitted light exiting the known object as said phase change analysis wavefront.

21. A method according to claim 15 wherein said step of employing said at least one intensity map comprises deriving at least one contrast map from the at least one intensity map and employing said at least one contrast map to obtain an output indication of said at least one phase change applied to said transformed phase change analysis wavefront.

22. A method of wavefront analysis comprising:

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed, the method also comprising;

performing said obtaining steps and said employing step wherein said wavefront being analyzed comprises a wavefront originating from a known object having known amplitude and phase values;

computing amplitude and phase calibration values by comparing the output of the employing step performed on said known object to said known amplitude and phase values; and

when performing said obtaining and employing steps on an unknown object, using said amplitude and phase calibration values to correct the output for said unknown object generated in said employing step.

23. A method according to claim 22 wherein said wavefront originating from the known object comprises a wavefront reflected from the known object.

24. A method according to claim 22 wherein said wavefront originating from the known object comprises a wavefront transmitted through the known object.

25. A method according to claim 22 wherein said known object comprises a flat mirror.

26. A method according to claim 22 wherein said known object comprises a window.

27. A method of wavefront analysis comprising:

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed, and also comprising using an iris to block off a portion of a wavefront, thereby to generate said wavefront being analyzed, and wherein the plurality of intensity maps are obtained using a camera having an imaging area which is larger than the image of said iris on the imaging area.

30. A method according to claim 27 and wherein:

said obtaining a plurality of differently phase changed transformed wavefronts comprises;

applying a transform to said wavefront being analyzed thereby to obtain a transformed wavefront; and

applying a plurality of different phase changes to said transformed wavefront, thereby to obtain a plurality of differently phase changed transformed wavefronts;

said plurality of different phase changes includes spatial phase changes;

said plurality of different spatial phase changes are effected by applying a spatially uniform, time-varying spatial phase change to part of said transformed wavefront;

said transform applied to said wavefront being analyzed is a Fourier transform, said plurality of different spatial phase changes comprises at least three different phase changes;

said plurality of intensity maps comprises at least three intensity maps; and

said employing includes;

expressing said wavefront being analyzed as a first complex function which has an amplitude and phase identical to said amplitude and phase of said wavefront being analyzed;

expressing said plurality of intensity maps as a function of said first complex function and of a spatial function governing said spatially uniform, time- varying spatial phase change;

defining a second complex function, having an absolute value and a phase, as a convolution of said first complex function and of a Fourier transform of said spatial function governing said spatially uniform, time-varying spatial phase change;

expressing each of said plurality of intensity maps as a third function of;

said amplitude of said wavefront being analyzed;

said absolute value of said second complex function;

a difference between said phase of said wavefront being analyzed and said phase of said second complex function; and

a known phase delay produced by one of said at least three different phase changes which each correspond to one of said at least three intensity maps;

solving said third function to obtain said amplitude of said wavefront being analyzed, said absolute value of said second complex function and said difference between said phase of said wavefront being analyzed and said phase of said second complex function;

solving said second complex function to obtain said phase of said second complex function; and

obtaining said phase of said wavefront being analyzed by adding said phase of said second complex function to said difference between said phase of said wavefront being analyzed and said phase of said second complex function, and wherein the square of the absolute value of the second complex function is derived from the portion of the imaging area which is external to the image of said iris on the imaging area.

28. A method of wavefront analysis comprising:

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed, and wherein obtaining a plurality of differently phase changed transformed wavefronts comprises;

applying a transform to said wavefront being analyzed thereby to obtain a transformed wavefront; and

applying a plurality of different phase changes to said transformed wavefront, thereby to obtain a plurality of differently phase changed transformed wavefronts, and wherein said plurality of different phase changes includes spatial phase changes, and wherein said plurality of different spatial phase changes are effected by applying a spatially uniform, time-varying spatial phase change to part of said transformed wavefront, and wherein;

said transform applied to said wavefront being analyzed is a Fourier transform;

said step of employing includes;

expressing said wavefront being analyzed as a first complex function which has an amplitude and phase identical to said amplitude and phase of said wavefront being analyzed;

expressing said plurality of intensity maps as a function of said first complex function and of a spatial function governing said spatially uniform, time-varying spatial phase change;

defining a second complex function, having an absolute value and a phase, as a convolution of said first complex function and of a Fourier transform of said spatial function governing said spatially uniform, time-varying spatial phase change;

expressing each of said plurality of intensity maps as a third function of;

said amplitude of said wavefront being analyzed;

said absolute value of said second complex function;

a difference between said phase of said wavefront being analyzed and said phase of said second complex function; and

a known phase delay produced by one of said different phase changes which each correspond to one of said intensity maps;

solving said third function to obtain said amplitude of said wavefront being analyzed, said absolute value of said second complex function and said difference between said phase of said wavefront being analyzed and said phase of said second complex function;

solving said second complex function to obtain said phase of said second complex function; and

obtaining said phase of said wavefront being analyzed by adding said phase of said second complex function to said difference between said phase of said wavefront being analyzed and said phase of said second complex function, wherein said step of obtaining an output indicating said amplitude and phase of said wavefront being analyzed comprises employing said plurality of intensity maps and said square of the absolute value of the second complex function to obtain said output.

29. A method for analyzing a wavefront having an amplitude and a phase, the method comprising:

using an iris to block off a portion of a wavefront, thereby to generate a wavefront being analyzed;

Fourier-transforming said wavefront being analyzed and effecting a spatial phase change on a portion of the transformed wavefront, thereby to generate at least one partially phase changed transformed wavefront, including a known phase changed wavefront portion and a phase unchanged wavefront portion;

obtaining at least one intensity map of said at least one partially phase changed transformed wavefront, the map representing interference between the phase changed portion and the phase unchanged portion, wherein said map is obtained using a camera having an imaging area which is larger than the image of said iris on the imaging area, thereby to define inside and outside map portions representing intensity of light impinging on the imaging area portion inside and outside the iris image respectively; and

employing said at least one intensity map to obtain an output indicating said amplitude and phase of said wavefront being analyzed, including;

expressing said wavefront being analyzed as a first complex function which has an amplitude and phase identical to said amplitude and phase of said wavefront being analyzed;

expressing said intensity map as a function of said first complex function and of a spatial function; and

defining a second complex function, having an absolute value and a phase, as a convolution of said first complex function and of a Fourier transform of said spatial function;

wherein said absolute value of said second complex function is obtained by approximating said absolute value to a polynomial of a given degree, and wherein the square of the absolute value of the second complex function is derived from the portion of the imaging area which is external to the image of said iris on the imaging area, assuming that the phase of the second complex function is constant over the imaging area; and

computing the amplitude and phase of the wavefront being analyzed by assuming said inside map portion represents interference between said wavefront being analyzed and a wavefront having said absolute value of said second complex function as an amplitude and having a phase which is constant over the imaging area.

31. A method of wavefront analysis comprising:

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed, and wherein obtaining a plurality of differently phase changed transformed wavefronts comprises;

applying a transform to said wavefront being analyzed thereby to obtain a transformed wavefront; and

applying a plurality of different phase changes to said transformed wavefront, thereby to obtain a plurality of differently phase changed transformed wavefronts, and wherein said plurality of different phase changes includes spatial phase changes, and wherein said plurality of different spatial phase changes are effected by applying a spatial phase change to part of said transformed wavefront, wherein said step of applying a plurality of different phase changes comprises duplicating the transformed wavefront into several wavefronts and wherein said step of applying a plurality of different phase changes comprises applying a different spatial phase change to each of said several wavefronts.

32. A method according to claim 31 wherein said step of duplicating comprises splitting the beam forming the transformed wavefront.

33. A method of providing simultaneous surface and layer thickness measurements of a multilayer object comprising:

illuminating the multilayer object with broadband illumination;

analyzing illumination emerging from said multilayer object to provide a spectral analysis output; and

utilizing said spectral analysis output to provide simultaneously both surface and layer thickness information regarding said multilayer object.

34. A method according to claim 33 and wherein said method comprises:

obtaining a reflected wavefront having an amplitude and a phase, by reflecting radiation from a surface; and

analyzing said reflected wavefront by;

obtaining a plurality of differently phase changed transformed wavefronts corresponding to said reflected wavefront;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wave fronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said reflected wavefront.

35. A method according to claim 34 and wherein said radiation reflected from said surface has at least two narrow bands, each centered about a different wavelength, providing at least two wavelength components in said surface mapping wavefront and at least two indications of said phase of said surface mapping wavefront, thereby enabling an enhanced mapping of said surface to be obtained by avoiding an ambiguity in the mapping which exceeds the larger of said different wavelengths about which said two narrow bands are centered.

36. A method according to claim 34 and wherein:

said wavefront being analyzed comprises a plurality of different wavelength components; and

said plurality of differently phase changed transformed wavefronts are obtained by applying a phase change to said plurality of different wavelength components of said wavefront being analyzed.

37. A method of wavefront analysis according to claim 34 and wherein:

said plurality of intensity maps comprises at least four intensity maps; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed includes employing a plurality of combinations, each of at least three of said plurality of intensity maps, to provide a plurality of indications of said amplitude and phase of said wavefront being analyzed.

38. A method according to claim 34 and wherein:

said wavefront being analyzed comprises at least two wavelength components;

said obtaining a plurality of intensity maps also includes dividing said phase changed transformed wavefronts according to said at least two wavelength components in order to obtain at least two wavelength components of said phase changed transformed wavefronts and in order to obtain at least two sets of intensity maps, each set corresponding to a different one of said at least two wavelength components of said phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed includes obtaining an output indicative of the phase of said wavefront being analyzed from each of said at least two sets of intensity maps and combining said outputs to provide an enhanced indication of phase of said wavefront being analyzed, in which enhanced indication, there is no ambiguity.

39. A method according to claim 33 wherein said broadband illumination includes multi-wavelength illumination including illumination having a number of known wavelengths, said number at least equal to the number of layers in said multilayer object.

40. A method according to claim 39 wherein said analyzing comprises generating an emerging illumination intensity map for each of a number of known wavelengths, said number at least equal to the number of layers in said multilayer object.

41. A method according to claim 39 wherein said emerging illumination comprises at least one of reflected illumination and transmitted illumination.

42. A method of analyzing a wavefront, comprising a plurality of different wavelength components, after the wavefront exits an object, the method comprising:

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase, including;

applying a transform to each of the plurality of different wavelength components, thereby to generate a plurality of transformed wavefront components; and

applying a plurality of scalable phase changes to the plurality of transformed wavefront components respectively;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed.

43. A method according to claim 42 wherein said plurality of scalable phase changes are each in a different plane.

44. A method according to claim 42 wherein said plurality of different wavelength components are generated by light sources disposed at various distances from the object.

45. A method of wavefront analysis comprising:

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed, and wherein obtaining a plurality of differently phase changed transformed wavefronts comprises;

applying a transform to said wavefront being analyzed thereby to obtain a transformed wavefront; and

applying a plurality of different phase changes to said transformed wavefront, thereby to obtain a plurality of differently phase changed transformed wavefronts, wherein said applying a plurality of different phase changes comprises providing an optical system having a selectable plurality of optical configurations creating a corresponding plurality of phase changes respectively.

46. A method according to claim 45 wherein said optical system comprises a spatial light modulator (SLM) including a central inactive area and a peripheral active area.

47. A method according to claim 45 wherein said optical system comprises a phase plate having a plurality of portions each corresponding to an individual phase change and a phase plate portion selector operative to position a selected one of the phase plate portions along a light path.

48. The method according to claim 45 wherein said optical system comprises two mirrors at an adjustable distance from one another whose relative configuration is such that a first portion of the light impinging at the two mirror configuration arrives at the first mirror and a second portion of the light impinging at the two mirror configuration arrives at the second mirror, and wherein said distance between said two mirrors is adjusted to effect said phase change.

49. The method according to claim 48 wherein said two mirrors comprise a first mirror preceding a second mirror along the light path, said first mirror having an aperture defined therewith, thereby allowing said second portion of the light to reach said second mirror via the aperture.

50. The method according to claim 48 wherein said two mirrors comprise a first mirror preceding a second mirror along the light path wherein at least one dimension of the first mirror'"'"'s surface area is less than at least one corresponding dimension of the cross-section of the wavefront and less than the corresponding dimension of the second mirror'"'"'s surface area, thereby allowing said second portion of the light to reach the second mirror.

51. The method according to claim 48 and also comprising at least one piezo-electric actuator operative to allow a user to control the distance between the two mirrors.

52. An apparatus for wavefront analysis comprising:

a light source, to illuminate an object and to obtain a wavefront having an amplitude and a phase;

a wavefront transformer, obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed having a phase and an amplitude, including;

a transformed wavefront generator, applying a transform to said wavefront being analyzed thereby to obtain a transformed wavefront; and

a phase changer, applying a plurality of different phase changes to said transformed wavefront, thereby to obtain a plurality of differently phase changed transformed wavefronts;

an intensity map provider, obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts by phase manipulation; and

an intensity map utilizer, employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed, wherein said plurality of different phase changes are applied to a region of said transformed wavefront, corresponding to a shape of said light source.

53. An apparatus for wavefront analysis comprising:

a wavefront transformer, obtaining two differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase;

an intensity map provider, obtaining two intensity maps of said two phase changed transformed wavefronts; and

an intensity map utilizer, employing said two intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed; and

wherein;

said intensity map provider is also operative for employing interference between said two intensity maps to generate a third intensity map; and

said obtaining two differently phase changed transformed wavefronts comprises;

applying a transform to said wavefront being analyzed thereby to obtain a transformed wavefront; and

applying a plurality of different phase changes to said transformed wavefront, thereby to obtain a plurality of differently phase changed transformed wavefronts.

54. A method of optical property analysis of an object by analyzing a wavefront exiting the object, the method comprising:

providing an imaging system having a defined depth of focus;

repeating the following steps focusing on each of several depths within the object;

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase and which is exiting an object;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed; and

combining the several outputs generated by repeating said obtaining and employing steps in order to obtain a slice-by-slice optical transmission profile of the object.

55. A method according to claim 54 wherein said optical transmission profile comprises an optical path length for each of the several depths within the object.

56. A method of wavefront analysis operative to analyze a wavefront exiting from an object, the method comprising:

focusing an imaging system on the object without changing the distance from the object to the imaging system and obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has an amplitude and a phase;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed.

57. A method of wavefront analysis comprising:

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain a modulo 2 output indicating said amplitude and phase of said wavefront being analyzed, wherein said step of employing comprises computing at least one characteristic of the object'"'"'s surface geometry by analyzing a Moiré

pattern generated by projecting stripes on the object and viewing the object through a grating; and

resolving the 2π

ambiguity of the modulo 2π

output using at least one characteristic of the object'"'"'s surface geometry.

58. A method according to claim 57 wherein said stripes are generally linear.

59. A method according to claim 57 wherein said step of projecting stripes comprises illuminating the object via a grating.

60. A method according to claim 57 wherein said step of projecting stripes comprises using a plurality of coherent illumination sources to illuminate the object, thereby to generate an interference pattern on the object.

61. A method for wavefront analysis utilizing a propagated wavefront, the method comprising:

utilizing a propagated wavefront, which corresponds to a wavefront being analyzed, having an amplitude and a phase, for obtaining a plurality of differently phase changed transformed propagated wavefronts;

obtaining a plurality of intensity maps of said plurality of phase changed transformed propagated wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed.

62. A method for wavefront analysis according to claim 61 and wherein said employing comprises:

employing said plurality of intensity maps to obtain an output corresponding to said propagated wavefront; and

employing said output corresponding to said propagated wavefront to obtain an output indicating said amplitude and phase of said wavefront being analyzed.

63. A method according to claim 61 and also comprising:

utilizing said output indicating said amplitude and phase of said wavefront being analyzed in order to obtain a second output indicating amplitude and phase of a propagated wavefront obtained by propagating said wavefront being analyzed to any given plane.

64. A method according to claim 63 wherein said propagating said wavefront being analyzed to any given plane also includes propagating through optical elements.

65. A method for wavefront analysis comprising:

in a first mode of operation;

obtaining a plurality of differently phase changed transformed wavefronts corresponding to an wavefront being analyzed which has an amplitude and a phase;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said wavefront being analyzed; and

in a second mode of operation;

carrying out an interferometric measurement on said wavefront being analyzed employing a reference in order to provide an output indicating the location of a source of said wavefront being analyzed.

66. A method of wavefront analysis according to claim 65 and wherein said source of said wavefront being analyzed comprises an object.

67. A method of wavefront analysis according to claim 65 and wherein said reference comprises a mirror.

68. A method of wavefront analysis comprising:

obtaining a wavefront being analyzed which has an amplitude and a phase;

obtaining a modified wavefront which has an amplitude and a phase in which estimated known differences of the wavefront being analyzed from a planar-like wavefront are removed by an optical element;

obtaining a plurality of differently phase changed transformed modified wavefronts corresponding to said modified wavefront;

obtaining a plurality of intensity maps of said plurality of phase changed transformed modified wavefronts;

employing said plurality of intensity maps to obtain an output indicating said amplitude and phase of said modified wavefront; and

obtaining an output indicating said amplitude and phase of said wavefront being analyzed, by reintroducing said estimated known differences from said planar-like wavefront to said output indicating said amplitude and phase of said modified wavefront.

69. A method according to claim 68 and wherein:

said wavefront being analyzed is approximately a spherical wavefront; and

said optical element is a lens operative to remove the spherical components of said wavefront being analyzed.

70. A method according to claim 68 and wherein:

said wavefront being analyzed is a tilted wavefront with additional features, and said optical element is a prism operative to remove the tilt component of said wavefront being analyzed.

71. A wavefront analysis system comprising:

a wavefront generator, operative to obtain a wavefront being analyzed which has an amplitude and a phase;

an optical element, operative to modify said wavefront to obtain a modified wavefront which has an amplitude and a phase in which estimated known differences of the wavefront being analyzed from a planar-like wavefront are removed by said optical element;

a phase changer, operative to provide a plurality of differently phase changed transformed modified wavefronts corresponding to said modified wavefront;

an intensity map generator, operative to generate a plurality of intensity maps of said plurality of phase changed transformed modified wavefronts;

an intensity map utilizer, employing said plurality of intensity maps to provide an output indicating said amplitude and phase of said modified wavefront; and

a wavefront reconstructor, operative to obtain an output indicating said amplitude and phase of said wavefront being analyzed by reintroducing said estimated known differences from said planar-like wavefront to said output indicating said amplitude and phase of said modified wavefront.

72. A system according to claim 71 and wherein:

said wavefront being analyzed is approximately a spherical wavefront; and

said optical element is a lens operative to remove the spherical components of said wavefront being analyzed.

73. A system according to claim 71 and wherein:

said wavefront being analyzed is a tilted wavefront with additional features; and

said optical element is a prism operative to remove the tilt component of said wavefront being analyzed.

74. A method of wavefront analysis comprising:

obtaining a plurality of differently phase changed transformed wavefronts corresponding to a wavefront being analyzed which has a polarization;

obtaining a plurality of intensity maps of said plurality of phase changed transformed wavefronts; and

employing said plurality of intensity maps to obtain an output indicating said polarization of said wavefront being analyzed.