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Claims  |
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What is claimed is:
1. An interferometer for analyzing a dimension of an object based on
interleaved multiple phase-shifted interference information, comprising:
a transmitting portion that directs first and second differently polarized
lights from a coherent light beam to a reference element and an object,
respectively, combines the first and second differently polarized lights
returned from the reference element and the object into a combined
wavefront, and outputs the combined wavefront; and
a multiple phase shift image generating portion arranged to input the
combined wavefront, the multiple phase shift image generating portion
comprising:
at least a first relative retardation array arranged along at least a first
optical path, the first relative retardation array comprising at least two
respective pluralities of relative retardation portions, each respective
plurality of relative retardation portions comprising relative retardation
portions of a single respective type that produces a respective amount of
relative phase shift when transmitting the first and second differently
polarized lights, the at least two respective pluralities of relative
retardation portions arranged in an interleaved pattern within the first
relative retardation array, and
a first polarizer element arranged along the first optical path; and
a detector portion comprising at least a first detector array arranged
along the first optical path;
wherein:
the first relative retardation array receives at least a sub-wavefront of
the combined wavefront including the first and second differently
polarized lights;
each of the at least two respective pluralities of relative retardation
portions transmits the first and second differently polarized lights of
the sub-wavefront through the first polarizer element, each respective
plurality of relative retardation portions in combination with the first
polarizer element producing at least one respective plurality of
interference portions along the first optical path, each of the respective
pluralities of interference portions produced along the first optical path
comprising interference light having a single respective relative phase
shift; and
the multiple phase shift image generating portion outputs interleaved
multiple phase-shifted interference image information from at least the
first optical path, the interleaved multiple phase-shifted interference
image information output from the first optical path comprising the
respective pluralities of interference portions produced along the first
optical path, mutually interleaved in a pattern determined at least
partially by the interleaved pattern of the respective pluralities of
relative retardation portions in the first relative retardation array.
2. The interferometer of claim 1, wherein the interleaved multiple
phase-shifted interference image information from the first optical path
is output to form an interleaved multiple phase-shifted interference image
on the first detector array.
3. The interferometer of claim 2, wherein each of the individual respective
interference portions produced along the first optical path has nominal
extents in the interleaved multiple phase-shifted interference image on
the first detector array, and the nominal extents are nominally aligned to
coincide with the boundaries of a coextensive set of pixels of the first
detector array.
4. The interferometer of claim 3, wherein the coextensive set of pixels on
the first detector array is N pixels wide and M pixels high, where M and N
are integers.
5. The interferometer of claim 4, wherein M is at most equal to 16 and N is
at most equal to 16.
6. The interferometer of claim 5, wherein M is at most equal to 8 and N is
at most equal to 8.
7. The interferometer of claim 1, wherein the respective relative phase
shift of a first respective plurality of interference portions produced
along the first optical path differs from the respective relative phase
shift of a second respective plurality of interference portions produced
along the first optical path by one of (360N)+90 degrees, (360N)+120
degrees, (360N)+180 degrees, (360N)+240 degrees and (360N)+270 degrees,
where N is an integer.
8. The interferometer of claim 1, wherein the at least two respective
pluralities of relative retardation portions comprise at least three
respective pluralities of relative retardation portions, at least three
respective pluralities of interference portions are produced along the
first optical path, and the at least three respective pluralities of
interference portions comprise respective interference lights having
respective relative phase shifts of (360N) degrees, (360N)+120 degrees,
and (360N)+240 degrees.
9. The interferometer of claim 1, wherein the at least two respective
pluralities of relative retardation portions comprise at least four
respective pluralities of relative retardation portions, at least four
respective pluralities of interference portions are produced along the
first optical path, and the at least four respective pluralities of
interference portions comprise respective interference lights having
respective relative phase shifts of (360N) degrees, (360N)+90 degrees,
(360N)+180 degrees and (360N)+270 degrees.
10. The interferometer of claim 1, wherein a structure of the first
relative retardation array that at least partially determines the
interleaved pattern of the first relative retardation array is positioned
proximate to a detector surface of the first detector array, within a
distance that is smaller than a depth of focus of the interleaved multiple
phase-shifted interference image information output from the first-optical
path.
11. The interferometer of claim 1, wherein the first polarizer element is
fabricated on a surface of the first relative retardation array that faces
the first detector array and the first polarizer element is positioned
proximate to a detector surface of the first detector array.
12. The interferometer of claim 11, wherein the first polarizer element
comprises a wire-grid polarizer element.
13. The interferometer of claim 1, wherein at least the first relative
retardation array, the first polarizer element, and the first detector
array form an integrated monolithic phase-shift imaging element.
14. The interferometer of claim 1, wherein:
the first polarizer element comprises a first polarizer array including a
plurality of first polarizing portions having a first polarization
direction and a plurality of second polarizing portions having a second
polarization direction, the first and second polarizing portions arranged
in a pattern within the first polarizer array;
the first polarizer array is aligned relative to the first relative
retardation array along the first optical path such that:
for the first polarizing portions that are aligned with a relative
retardation portion of a first respective type, the first polarizing
portions transmit the first and second differently polarized lights of the
sub-wavefront to produce a first respective plurality of interference
portions along the first optical path comprising interference light having
a first respective relative phase shift;
for the second polarizing portions that are aligned with a relative
retardation portion of the first respective type, the second polarizing
portions transmit the first and second differently polarized lights of the
sub-wavefront to produce a second respective plurality of interference
portions along the first optical path comprising interference light having
a second respective relative phase shift;
for the first polarizing portions that are aligned with a relative
retardation portion of a second respective type, the first polarizing
portions transmit the first and second differently polarized lights of the
sub-wavefront to produce a third respective plurality of interference
portions along the first optical path comprising interference light having
a third respective relative phase shift;
for the second polarizing portions that are aligned with a relative
retardation portion of the second respective type, the second polarizing
portions transmit the first and second differently polarized lights of the
sub-wavefront to produce a fourth respective plurality of interference
portions along the first optical path comprising interference light having
a fourth respective relative phase shift; and
the interleaved multiple phase-shifted interference image information
output from the first optical path comprises at least the first, second,
third and fourth respective pluralities of interference portions along the
first optical path mutually interleaved in a pattern determined at least
partially by the pattern of the first polarizing portions and the second
polarizing portions in the first polarizer array in combination with the
interleaved pattern of the respective pluralities of relative retardation
portions in the first relative retardation array.
15. The interferometer of claim 14, wherein the first respective relative
phase shift differs from the second respective relative phase shift by 180
degrees and the third respective relative phase shift differs from the
fourth respective relative phase shift by 180 degrees.
16. The interferometer of claim 14, wherein the interleaved multiple
phase-shifted interference image information from the first optical path
is output to form an interleaved multiple phase-shifted interference image
on the first detector array, each of the individual respective
interference portions produced along the first optical path has nominal
extents in the interleaved image on the first detector array, and the
nominal extents are nominally aligned to coincide with the boundaries of a
coextensive set of pixels of the first detector array.
17. The interferometer of claim 14, wherein:
the pattern of the plurality of first polarizing portions and the plurality
of second polarizing portions in the first polarizer array comprises a
striped polarization pattern, the interleaved pattern of the at least two
respective pluralities of relative retardation portions of the first and
second respective types in the first relative retardation array comprises
a striped relative retardation pattern; and the striped relative
retardation pattern is nominally orthogonal to the striped polarization
pattern.
18. The interferometer of claim 14, wherein:
the pattern of the plurality of first polarizing portions and the plurality
of second polarizing portions in the first polarizer array comprises a
checkerboard polarization pattern, the interleaved pattern of the at least
two respective pluralities of relative retardation portions of the first
and second respective types in the first relative retardation array
comprises a striped relative retardation pattern; and an individual stripe
of the relative retardation pattern is nominally aligned with one of an
individual row and an individual column of the checkerboard polarization
pattern.
19. The interferometer of claim 1, wherein:
the multiple phase shift image generating portion further comprises:
a beam-splitting surface,
a second relative retardation array arranged along at least a second
optical path, the second relative retardation array comprising at least
two respective pluralities of relative retardation portions, each
respective plurality of relative retardation portions comprising relative
retardation portions of a single respective type that produces a
respective amount of relative phase shift when transmitting the first and
second differently polarized lights, the at least two respective
pluralities of relative retardation portions arranged in an interleaved
pattern within the second relative retardation array, and
a second polarizer element arranged along the second optical path; and
the detector portion further comprises a second detector array arranged
along the second optical path;
wherein:
the beam-splitting surface is arranged to receive the combined wavefront
and to transmit a first sub-wavefront of the combined wavefront including
the first and second differently polarized lights along the first optical
path and a second sub-wavefront of the combined wavefront including the
first and second differently polarized lights along the second optical
path;
the second relative retardation array receives the second sub-wavefront of
the combined wavefront including the first and second differently
polarized lights;
each of the at least two respective pluralities of relative retardation
portions of the second relative retardation array transmits the first and
second differently polarized lights of the second sub-wavefront through
the second polarizer element, each respective plurality of relative
retardation portions, in combination with the second polarizer element,
producing at least one respective plurality of interference portions along
the second optical path, each of the respective pluralities of
interference portions produced along the second optical path comprising
interference light having a single respective relative phase shift;
the first relative retardation array receives the first sub-wavefront of
the combined wavefront and, in combination with the first polarizer array,
transmits the first and second differently polarized lights of the first
sub-wavefront to produce the respective pluralities of interference
portions produced along the first optical path based on the first
sub-wavefront;
the multiple phase shift image generating portion outputs the interleaved
multiple phase-shifted interference image information from the first
optical path comprising the respective pluralities of interference
portions produced along the first optical path based on the first
sub-wavefront; and
the multiple phase shift image generating portion further outputs
interleaved multiple phase-shifted interference image information from the
second optical path, the interleaved multiple phase-shifted interference
image information output from the second optical path comprising the
respective pluralities of interference portions produced along the second
optical path, mutually interleaved in a pattern determined at least
partially by the interleaved pattern of the respective pluralities of
relative retardation portions in the second relative retardation array.
20. The interferometer of claim 19, wherein:
the interleaved multiple phase-shifted interference image information from
the first optical path is output to form a first interleaved multiple
phase-shifted interference image on the first detector array;
the interleaved multiple phase-shifted interference image information from
the second optical path is output to form a second interleaved multiple
phase-shifted interference image on the second detector array; and
the second interleaved multiple phase-shifted interference image
corresponds to the first multiple phase-shifted interference interleaved
image.
21. The interferometer of claim 20, wherein each of the individual
respective interference portions produced along the first optical path and
the second optical path has nominal extents in the corresponding
interleaved multiple phase-shifted interference images on the
corresponding detector arrays, and the nominal extents are nominally
aligned to coincide with the boundaries of coextensive sets of pixels of
the corresponding detector arrays, and the coextensive set of pixels are
each N pixels wide and M pixels high, where M and N are integers at most
equal to 16.
22. The interferometer of claim 19, wherein the respective relative phase
shift of at least one respective plurality of interference portions
produced along the first optical path differs from the respective relative
phase shift of at least one respective plurality of interference portions
produced along the second optical path by one of (360N)+90 degrees,
(360N)+120 degrees, (360N)+180 degrees, (360N)+240 degrees and (360N)+270
degrees, where N is an integer.
23. The interferometer of claim 19, wherein:
the multiple phase shift image generating portion further comprises a first
reflective surface and a second reflective surface;
the first reflective surface is arranged to receive the first sub-wavefront
from the beam splitting surface and reflect the first sub-wavefront along
a portion of the first optical path that extends along a first direction;
the second reflective surface is arranged to receive the second
sub-wavefront from the beam splitting surface and reflect the second
sub-wavefront along a portion of the second optical path that is parallel
to the first direction;
the first relative retardation array and the second relative retardation
array are nominally coplanar;
the first polarizer element and the second polarizer element arc nominally
coplanar; and
the first detector array and the second detector array are nominally
coplanar.
24. The interferometer of claim 23, wherein at least one of a) the set of
the relative retardation array and the second relative retardation array,
b) the set of the first polarizer clement and the second polarizer
element, and c) the set of the first detector array and the second
detector array comprise first and second portions of the same element.
25. The interferometer of claim 19, wherein at least the elements of the
multiple phase shift image generating portion and the first detector array
form an integrated phase-shift imaging element.
26. The interferometer of claim 1, wherein the first relative retardation
array comprises a birefringent material formed such that each respective
plurality of relative retardation portions has a corresponding respective
thickness in the birefringent material along the direction of the first
optical path.
27. The interferometer of claim 26, wherein the birefringent material
comprises at least one of a substrate and a material layer of the first
relative retardation array.
28. The interferometer of claim 1, wherein the first relative retardation
array comprises a birefringent material that can be processed to vary the
fast axis direction within the birefringent material, and each respective
plurality of relative retardation portions has a corresponding respective
fast axis alignment direction in the birefringent material.
29. The interferometer of claim 28, wherein the birefringent material that
can be processed to vary the fast axis direction has a substantially
constant nominal thickness throughout the first relative retardation
array.
30. The interferometer of claim 28, wherein the birefringent material that
can be processed to vary the fast axis direction is formed with a pattern
of at least two thicknesses, such that the respective amount of relative
phase shift produced by each respective plurality of relative retardation
portions depends on a respective combination of the respective thickness
and the respective fast axis alignment direction corresponding to that
respective plurality of relative retardation portions.
31. An interferometer for analyzing a dimension of an object based on
interleaved multiple phase-shifted interference information, comprising:
a transmitting portion that directs first and second differently polarized
lights from a coherent light beam to a reference element and an object,
respectively, combines the first and second differently polarized lights
returned from the reference element and object into a combined wavefront,
and outputs the combined wavefront;
a multiple phase shift image generating portion arranged to input the
combined wave front, the multiple phase shift image generating portion
comprising:
at least a first relative retardation array arranged along at least a first
optical path, the first relative retardation array comprising at least two
respective pluralities of relative retardation portions, each respective
plurality of relative retardation portions comprising relative retardation
portions of a single respective type that produces a respective amount of
relative phase shift when transmitting the first and second differently
polarized lights, the at least two respective pluralities of relative
retardation portions arranged in an interleaved pattern within the first
relative retardation array, and
a first polarizer element arranged along the first optical path; and
a detector portion comprising at least a first detector array arranged
along the first optical path, wherein:
the multiple phase shift image generating portion generates and outputs
interleaved multiple phase-shifted interference image information from at
least the first optical path, the interleaved multiple phase-shifted
interference image information output from the first optical path
comprising respective pluralities of interference portions produced along
the first optical path, the respective pluralities of interference
portions mutually interleaved in a pattern determined at least partially
by the interleaved pattern of the respective pluralities of relative
retardation portions in at least the first relative retardation array.
32. A method for using an interferometer that analyzes a dimension of an
object based on interleaved multiple phase-shifted interference
information, comprising:
directing first and second differently polarized lights from a coherent
light beam to a reference element and an object;
combining the first and second differently polarized light returned from
the reference element and object into a combined wavefront;
directing at least a sub-wavefront of the combined wavefront including the
first and second differently polarized lights to be received by at least a
first relative retardation array arranged along at least a first optical
path, the first relative retardation array comprising:
at least two respective pluralities of relative retardation portions, each
respective plurality of relative retardation portions comprising relative
retardation portions of a single respective type that produces a
respective amount of relative phase shift when transmitting the first and
second differently polarized lights, the at least two respective
pluralities of relative retardation portions arranged in an interleaved
pattern within the first relative retardation array;
transmitting the first and second differently polarized lights of the
sub-wavefront received by the first relative retardation array through
each of the at least two respective pluralities of relative retardation
portions and through a first polarizer element arranged along the first
optical path such that each respective plurality of relative retardation
portions, in combination with the first polarizer element, produces at
least one respective plurality of interference portions along the first
optical path, each of the respective pluralities of interference portions
produced along the first optical path comprising interference light having
a single respective relative phase shift; and
outputting interleaved multiple phase-shifted interference image
information from at least the first optical path to a detector portion
comprising at least a first detector array arranged along the first
optical path;
wherein the interleaved multiple phase-shifted interference image
information output from the first optical path comprises the respective
pluralities of interference portions produced along the first optical
path, mutually interleaved in a pattern determined at least partially by
the interleaved pattern of the respective pluralities of relative
retardation portions in the first relative retardation array.
33. The method of claim 32, wherein outputting the interleaved multiple
phase-shifted interference image information from at least the first
optical path to a detector portion comprises forming an interleaved
multiple phase-shifted interference image on the first detector array.
34. The method of claim 33, wherein each of the individual respective
interference portions produced along the first optical path has nominal
extents in the interleaved multiple phase-shifted interference image on
the first detector array; and
forming the interleaved image on the first detector array comprises
projecting the individual respective interference portions produced along
the first optical path onto the first detector array such that the nominal
extents nominally coincide with the boundaries of a coextensive set of
pixels of the first detector array.
35. The method of claim 34, wherein the coextensive set of pixels on the
first detector array is N pixels wide and M pixels high, where M and N are
integers and M is at most equal to 16 and N is at most equal to 16.
36. The method of claim 32, wherein
the first polarizer element comprises a first polarizer array including a
plurality of first polarizing portions having a first polarization
direction and a plurality of second polarizing portions having a second
polarization direction, the first and second polarizing portions arranged
in a pattern within the first polarizer array;
the pattern within the first polarizer array and the interleaved pattern
within the first relative retardation array are in a nominal alignment
along the direction of the first optical path; and
transmitting the first and second differently polarized lights of the
sub-wavefront received by the first relative retardation array through
each of the at least two respective pluralities of relative retardation
portions and through the first polarizer element arranged along the first
optical path comprises:
transmitting the first and second differently polarized lights of the
sub-wavefront received by the first relative retardation array through
relative retardation portions of a first respective type and through the
first polarizing portions that are aligned with the relative retardation
portions of the first respective type to produce a first respective
plurality of interference portions along the first optical path comprising
interference light having a first respective relative phase shift;
transmitting the first and second differently polarized lights of the
sub-wavefront received by the first relative retardation array through
relative retardation portions of the first respective type and through the
second polarizing portions that are aligned with the relative retardation
portions of the first respective type to produce a second respective
plurality of interference portions along the first optical path comprising
interference light having a second respective relative phase shift;
transmitting the first and second differently polarized lights of the
sub-wavefront received by the first relative retardation array through
relative retardation portions of a second respective type and through the
first polarizing portions that are aligned with the relative retardation
portions of the second respective type to produce a third respective
plurality of interference portions along the first optical path comprising
interference light having a third respective relative phase shift;
transmitting the first and second differently polarized lights of the
sub-wavefront received by the first relative retardation array through
relative retardation portions of the second respective type and through
the second polarizing portions that arc aligned with the relative
retardation portions of the second respective type to produce a fourth
respective plurality of interference portions along the first optical path
comprising interference light having a fourth respective relative phase
shift; and
outputting the interleaved multiple phase-shifted interference image
information from at least the first optical path to a detector portion
comprises outputting at least the first, second, third and fourth
respective pluralities of interference portions along the first optical
path mutually interleaved in a pattern determined at least partially by
the pattern of the first polarizing portions and the second polarizing
portions in the first polarizer array in combination with the interleaved
pattern of the respective pluralities of relative retardation portions in
the first relative retardation array.
37. The method of claim 36, wherein the first respective relative phase
shift differs from the second respective relative phase shift by 180
degrees and the third respective relative phase shift differs from the
fourth respective relative phase shift by 180 degrees.
38. The method of claim 32, further comprising:
directing at least a second sub-wavefront of the combined wavefront
including the first and second differently polarized lights to be received
by at least a second relative retardation array arranged along at least a
second optical path, the second relative retardation array comprising:
at least two respective pluralities of relative retardation portions, each
respective plurality of relative retardation portions comprising relative
retardation portions of a single respective type that produces a
respective amount of relative phase shift when transmitting the first and
second differently polarized lights, the at least two respective
pluralities of relative retardation portions arranged in an interleaved
pattern within the second relative retardation array;
transmitting the first and second differently polarized lights of the
sub-wavefront received by the second relative retardation array through
each of the at least two respective pluralities of relative retardation
portions and through a second polarizer element arranged along the second
optical path such that each respective plurality of relative retardation
portions produces at least one respective plurality of interference
portions along the second optical path, each of the respective pluralities
of interference portions produced along the second optical path comprising
interference light having a single respective relative phase shift;
wherein
outputting the interleaved multiple phase-shifted interference image
information from at least the first optical path to a detector portion
further comprises outputting interleaved multiple phase-shifted
interference image information from at least the second optical path to a
detector portion comprising at least a second detector array arranged
along the second optical path; and
the interleaved multiple phase-shifted interference image information
output from the second optical path comprises the respective pluralities
of interference portions produced along the second optical path mutually
interleaved in a pattern determined at least partially by the interleaved
pattern of the respective pluralities of relative retardation portions in
the second relative retardation array.
39. The method of claim 38, wherein:
outputting interleaved multiple phase-shifted interference image
information from at least the first optical path to the first detector
array comprises forming a first interleaved multiple phase-shifted
interference image on the first detector array;
outputting interleaved multiple phase-shifted interference image
information from at least the second optical path to the second detector
array comprises forming a second interleaved multiple phase-shifted
interference image on the second detector array; and
the second interleaved multiple phase-shifted interference image
corresponds to the first interleaved multiple phase-shifted interference
image.
40. The method of claim 38, wherein:
each of the individual respective interference portions produced along the
first optical path and the second optical path has nominal extents in the
corresponding interleaved multiple phase-shifted interference images on
the corresponding detector arrays;
the nominal extents are nominally aligned to coincide with the boundaries
of coextensive sets of pixels of the corresponding detector arrays; and
the coextensive set of pixels are each N pixels wide and M pixels high,
where M and N are integers at most equal to 16.
41. The method of claim 38, wherein the respective relative phase shift of
at least one respective plurality of interference portions produced along
the first optical path differs from the respective relative phase shift of
at least one respective plurality of interference portions produced along
the second optical path by one of (360N)+90 degrees, (360N)+120 degrees,
(360N)+180 degrees, (360N)+240 degrees and (360N)+270 degrees, where N is
an integer.
42. The method of claim 38, wherein:
directing at least a sub-wavefront of the combined wavefront including the
first and second differently polarized lights to be received by at least a
first relative retardation array arranged along at least a first optical
path comprises:
directing the first sub-wavefront to a first reflective surface, and
directing the first sub-wavefront from the first reflective surface to the
first relative retardation array along a portion of the first optical path
that extends along a first direction; and
directing at least a second sub-wavefront of the combined wavefront
including the first and second differently polarized lights to be received
by at least a second relative retardation array arranged along at least a
second optical path comprises:
directing the second sub-wavefront to a second reflective surface, and
directing the second sub-wavefront from the second reflective surface to
the second relative retardation array along a portion of the second
optical path that that is parallel to the first direction;
wherein:
the first relative retardation array and the second relative retardation
array are nominally coplanar;
the first polarizer element and the second polarizer element are nominally
coplanar; and
the first detector array and the second detector array are nominally
coplanar.
43. A method for using an interferometer that analyzes a dimension of an
object based on interleaved multiple phase-shifted interference
information, comprising:
directing first and second differently polarized lights from a coherent
light beam to a reference element and an object;
combining the first and second differently polarized light returned from
the reference element and object into a combined wavefront;
directing at least a sub-wavefront of the combined wavefront including the
first and second differently polarized lights to be received by at least a
first relative retardation array arranged along at least a first optical
path, the first relative retardation array comprising:
at least two respective pluralities of relative retardation portions, each
respective plurality of relative retardation portions comprising relative
retardation portions of a single respective type that produces a
respective amount of relative phase shift when transmitting the first and
second differently polarized lights, the at least two respective
pluralities of relative retardation portions arranged in an interleaved
pattern within the first relative retardation array;
transmitting the first and second differently polarized lights of the
sub-wavefront received by the first relative retardation array through a
first polarizer element arranged along the first optical path to produce
interleaved multiple phase-shifted interference image information from at
least the first optical path; and
outputting interleaved multiple phase-shifted interference image
information from at least the first optical path;
wherein the interleaved multiple phase-shifted interference image
information output from the first optical path comprises the respective
pluralities of interference portions produced along the first optical
path, mutually interleaved in a pattern determined at least partially by
the interleaved pattern of the respective pluralities of relative
retardation portions in the first relative retardation array. |
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