US5225690A
Expired / Lapsed
US
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Gap measuring device and method using frustrated internal reflection
Assignee: Dainippon Screen Manufacturing Co Ltd
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Filing: 1991-05-29
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Granted: 1993-07-06
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Expires: 2011-05-29
Abstract
Abstract A narrow gap or unevenness of a surface of a specimen is measured by utilizing the tunnel effect of a light wave reflected at a boundary plane on the condition of total reflection. A laser beam emitted from a laser source is reflected at a surface of a prism on the condition of total reflection in terms of geometrical optics. If a gap between the surface of the prism and the specimen is about the wavelength of the laser beam, part of the laser beam is transmitted into the specimen, and the intensity of the transmitted beam depends on the gap width. A portion of the laser beam is reflected at the boundary plane back into the prism. Therefore, the gap can be measured by measuring the transmittance of the laser beam and comparing the same with the calculated relation between the transmittance and the gap calculated in advance. In practice, the gap width is determined by measuring intensity of the reflected laser beam in the presence of the gap and comparing it to the intensity of the reflected laser beam in the absence of the gap, i.e, when the specimen surface is more than several wavelengths away from the reflecting surface.
Inventors
- 👤 Takamasa Sakai
- 👤 Motohiro Kouno
- 👤 Sadao Hirae
- 👤 Ikuyoshi Nakatani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 10:24
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/02; G01B11/026; G01B11/30; G01B11/306
Claims Analysis
Total Claims: 66
Claim 1
Independent Claim
176 words
A device for measuring a gap between a surface of a specimen and a specific member comprising: a laser source for emitting a laser beam of linearly polarized light having a known wavelength; a light transmission reflector having a reflecting surface comprising said specific member located substantially parallel to said surface of said specimen across the gap for reflecting said laser beam at said reflecting surface such that geometric optical total reflection occurs; a photosensor for measuring intensity of said laser beam reflected by said reflecting surface of said reflector; a base on which said laser source, said reflector, and said photosensor are mounted; a first driving mechanism for relatively moving at least one of said base and said specimen in a first direction defining said gap; and gap determining means for comparing said intensity of said reflected laser beam with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam.
Claim 2
Independent Claim
176 words
A device for measuring a gap between a surface of a specimen and a specific member comprising: a laser source for emitting a laser beam of linearly polarized light having a known wavelength; a light transmission reflector having a reflecting surface comprising said specific member located substantially parallel to said surface of said specimen across the gap for reflecting said laser beam at said reflecting surface such that geometric optical total reflection occurs; a photosensor for measuring intensity of said laser beam reflected by said reflecting surface of said reflector; a base on which said laser source, said reflector, and said photosensor are mounted; a first driving mechanism for relatively moving at least one of said base and said specimen in a first direction defining said gap; and gap determining means for comparing said intensity of said reflected laser beam with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam.
Claim 3
Dependent Claim
31 words
A gap measuring device in accordance with claim 1, wherein: said gap is in the range of one tenth of a wavelength of said laser beam to two times said wavelength.
Claim 4
Dependent Claim
17 words
A gap measuring device in accordance with claim 2, wherein: said gap is less than 1 μm.
Claim 5
Dependent Claim
26 words
A gap measuring device in accordance with claim 3, wherein: said first driving mechanism comprises a piezoelectric element, and said light transmission reflector comprises a prism.
Claim 6
Dependent Claim
36 words
A gap measuring device in accordance with claim 1, further comprising: a second driving mechanism for relatively moving at least one of said base and said specimen in a second direction perpendicular to said first direction.
Claim 7
Dependent Claim
51 words
A gap measuring device in accordance with claim 5, wherein: said gap determining means comprises means for comparing said intensity of said reflected laser beam with a calculated value of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap.
Claim 8
Dependent Claim
51 words
A gap measuring device in accordance with claim 6, wherein: said first drive mechanism comprises means for relatively moving said base and said specimen so that a value of said gap determined by said gap determining means becomes equal to a prescribed value, thereby maintaining said gap at said prescribed value.
Claim 9
Dependent Claim
53 words
A gap measuring device in accordance with claim 7, wherein: said gap determining means comprises means for determining unevenness of at least a part of said surface of said specimen on the basis of movement of said first drive mechanism in said first direction at each position in said part of said surface.
Claim 10
Dependent Claim
32 words
A gap measuring device in accordance with claim 8, wherein: said gap is in the range of one tenth of a wavelength of said laser beam to two times of said wavelength.
Claim 11
Dependent Claim
17 words
A gap measuring device in accordance with claim 9, wherein said gap is less than 1 μm.
Claim 12
Dependent Claim
17 words
A gap measuring device in accordance with claim 10, wherein said laser beam is linearly polarized light.
Claim 13
Dependent Claim
28 words
A gap measuring device in accordance with claim 11, wherein said first and second driving mechanisms comprise a piezoelectric element, and said light transmission reflector is a prism.
Claim 14
Independent Claim
141 words
A method for measuring the gap between the surface of a specimen and a specific member comprising the steps of: (a) emitting a laser beam of linearly polarized light having a known wavelength incident on a reflecting surface of a light transmission reflector, said reflecting surface comprising said specific member located substantially parallel to said surface of said specimen across a gap; (b) reflecting said layers of beam at said reflecting surface such that geometric optical total reflection occurs; (c) measuring intensity of said laser beam reflected by said reflecting surface; and (d) determining said gap by comparing said intensity of said reflected laser beam with calculated values of said intensity according to Maxwell's equation on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam.
Claim 15
Independent Claim
141 words
A method for measuring the gap between the surface of a specimen and a specific member comprising the steps of: (a) emitting a laser beam of linearly polarized light having a known wavelength incident on a reflecting surface of a light transmission reflector, said reflecting surface comprising said specific member located substantially parallel to said surface of said specimen across a gap; (b) reflecting said layers of beam at said reflecting surface such that geometric optical total reflection occurs; (c) measuring intensity of said laser beam reflected by said reflecting surface; and (d) determining said gap by comparing said intensity of said reflected laser beam with calculated values of said intensity according to Maxwell's equation on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam.
Claim 16
Dependent Claim
31 words
A gap measuring method in accordance with claim 13, wherein: said gap is in the range of one tenth of a wavelength of said laser beam to two times said wavelength.
Claim 17
Dependent Claim
17 words
A gap measuring method in accordance with claim 14, wherein: said gap is less than 1 μm.
Claim 18
Dependent Claim
54 words
A gap measuring method in accordance with claim 13, wherein: said step (d) comprises the step of: (d-1) relatively moving said light transmission reflector and said specimen in a direction defining said gap so that a value of said gap becomes equal to a prescribed value, thereby maintaining said gap at said prescribed value.
Claim 19
Dependent Claim
70 words
A gap measuring method in accordance with claim 16, wherein: said step (d-1) is performed at plural positions of at least a part of said surface of said specimen, and said step (d) further comprises the step of: (d-2) determining unevenness of said part on the basis of relative movement of said light transmission reflector and said specimen in said direction at each position in said part of said surface.
Claim 20
Dependent Claim
31 words
A gap measuring method in accordance with claim 17, wherein: said gap is in the range of one tenth of a wavelength of said laser beam to two times said wavelength.
Claim 21
Dependent Claim
17 words
A gap measuring method in accordance with claim 18, wherein: said gap is less than 1 μm.
Claim 22
Dependent Claim
26 words
A gap measuring method in accordance with claim 13, wherein: said step of emitting a laser beam comprises emitting a laser beam comprising linearly polarized light.
Claim 23
Dependent Claim
182 words
Apparatus for measuring a gap between a surface of a specimen and a substantially parallel surface comprising: a source of radiant energy for emitting a radiant energy beam of linearly polarized light having a known wavelength; a radiant energy transmission reflector having a reflecting surface, said reflecting surface comprising said parallel surface, said reflecting surface reflecting said radiant energy such that, if a gap is at least several wavelengths of said radiant energy, said reflecting surface substantially totally reflects' said radiant energy; a photosensor for measuring the intensity of said radiant energy reflected by said reflecting surface of said reflector; a base for supporting said radiant energy source, reflector and said photosensor; first driving means for relatively moving said base and said specimen in a direction corresponding to the direction of said gap; and gap determining means for comparing said intensity of said reflected radiant energy with calculated values of said intensity according to Maxwell's equation on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected radiant energy.
Claim 24
Dependent Claim
182 words
Apparatus for measuring a gap between a surface of a specimen and a substantially parallel surface comprising: a source of radiant energy for emitting a radiant energy beam of linearly polarized light having a known wavelength; a radiant energy transmission reflector having a reflecting surface, said reflecting surface comprising said parallel surface, said reflecting surface reflecting said radiant energy such that, if a gap is at least several wavelengths of said radiant energy, said reflecting surface substantially totally reflects' said radiant energy; a photosensor for measuring the intensity of said radiant energy reflected by said reflecting surface of said reflector; a base for supporting said radiant energy source, reflector and said photosensor; first driving means for relatively moving said base and said specimen in a direction corresponding to the direction of said gap; and gap determining means for comparing said intensity of said reflected radiant energy with calculated values of said intensity according to Maxwell's equation on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected radiant energy.
Claim 25
Dependent Claim
25 words
Apparatus in accordance with claim 21, wherein said radiant energy source comprises a laser source and said radiant energy beam comprises a reflected radiant energy.
Claim 26
Dependent Claim
27 words
Apparatus in accordance with claim 22, wherein: said gap is in the range of one-tenth of a wavelength of said laser beam to two times said wavelength.
Claim 27
Dependent Claim
14 words
Apparatus in accordance with claim 23, wherein: said gap is less than 1 μm.
Claim 28
Dependent Claim
23 words
Apparatus in accordance with claim 24, wherein: said first driving means comprises a piezoelectric element, and said light transmission reflector comprises a prism.
Claim 29
Dependent Claim
33 words
Apparatus in accordance with claim 22, further comprising: a second driving means for relatively moving at least one of said base and said specimen in a second direction perpendicular to said first direction.
Claim 30
Dependent Claim
48 words
Apparatus in accordance with claim 26, wherein: said gap determining means comprises means for comparing said intensity of said reflected laser beam with a calculated value of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap.
Claim 31
Dependent Claim
48 words
Apparatus in accordance with claim 27, wherein: said first driving means comprises means for relatively moving said base and said specimen so that a value of said gap determined by said gap determining means becomes equal to a prescribed value, thereby maintaining said gap at said prescribed value.
Claim 32
Dependent Claim
50 words
Apparatus in accordance with claim 28, wherein: said gap determining means comprises means for determining unevenness of at least a part of said surface of said specimen on the basis of movement of said first driving means in said first direction at each position in said part of said surface.
Claim 33
Dependent Claim
27 words
Apparatus in accordance with claim 29, wherein: said gap is in the range of one-tenth of a wavelength of said laser beam to two times said wavelength.
Claim 34
Dependent Claim
13 words
Apparatus in accordance with claim 30, wherein: said gap is less than μm.
Claim 35
Dependent Claim
18 words
Apparatus in accordance with claim 31, wherein; said laser source generates a laser beam comprising linearly polarized light.
Claim 36
Dependent Claim
26 words
Apparatus in accordance with claim 32, wherein: said first and second driving means each comprise a piezoelectric element, and said light transmission reflector comprises a prism.
Claim 37
Dependent Claim
211 words
Apparatus for maintaining a gap between a surface of a specimen and a specific member at a prescribed value, comprising: a laser source for emitting a laser beam of linearly polarized light having a known wavelength; a light transmission reflector having a reflecting surface comprising said specific member located substantially parallel to said surface of said specimen across the gap for reflecting said laser beam at said reflecting surface; a photosensor for measuring intensity of said laser beam reflected by said reflecting surface of said reflector; a base on which said laser source, said reflector and said photosensor are mounted; first driving means for relatively moving at least one of said base and said specimen in a first direction defining said gap; gap determining means for comparing said intensity of said reflected laser beam with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam, said first driving means comprising means for relatively moving said base and said specimen so that a value of said gap determined by said gap determining means becomes equal to said prescribed value, thereby maintaining said gap at said prescribed value.
Claim 38
Dependent Claim
211 words
Apparatus for maintaining a gap between a surface of a specimen and a specific member at a prescribed value, comprising: a laser source for emitting a laser beam of linearly polarized light having a known wavelength; a light transmission reflector having a reflecting surface comprising said specific member located substantially parallel to said surface of said specimen across the gap for reflecting said laser beam at said reflecting surface; a photosensor for measuring intensity of said laser beam reflected by said reflecting surface of said reflector; a base on which said laser source, said reflector and said photosensor are mounted; first driving means for relatively moving at least one of said base and said specimen in a first direction defining said gap; gap determining means for comparing said intensity of said reflected laser beam with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam, said first driving means comprising means for relatively moving said base and said specimen so that a value of said gap determined by said gap determining means becomes equal to said prescribed value, thereby maintaining said gap at said prescribed value.
Claim 39
Dependent Claim
27 words
Apparatus in accordance with claim 34, wherein: said gap is in the range of one-tenth of a wavelength of said laser beam to two times said wavelength.
Claim 40
Dependent Claim
14 words
Apparatus in accordance with claim 35, wherein: said gap is less than 1 μm.
Claim 41
Dependent Claim
23 words
Apparatus in accordance with claim 36, wherein: said first driving means comprises a piezoelectric element, and said light transmission reflector comprises a prism.
Claim 42
Dependent Claim
29 words
Apparatus in accordance with claim 36, further comprising: a second driving means for relatively moving said base and said specimen in a second direction perpendicular to said first direction.
Claim 43
Independent Claim
227 words
A device for measuring the unevenness of a surface of a specimen comprising: a laser source for emitting a laser beam of linearly polarized light having a known wavelength; a light transmitting reflector having a reflecting surface comprising a surface located substantially parallel to the surface of said specimen, thereby defining a gap between said surface of said specimen and said substantially parallel surface, said reflecting surface reflecting said laser beam; a photosensor for measuring intensity of said laser beam reflected by said reflecting surface of said reflector; a base on which said laser source, said reflector and said photosensor are mounted; a first driving means for relatively moving said base and said specimen in a first direction defining said gap; gap determining means for comparing said intensity of said reflected laser beam with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam, said gap determining means comprising means for controlling said first driving means to maintain said gap at a prescribed value, the unevenness of at least a part of said surface of said specimen being determined on the basis of movement of said first drive means in said first direction at each position in said part of said surface.
Claim 44
Independent Claim
227 words
A device for measuring the unevenness of a surface of a specimen comprising: a laser source for emitting a laser beam of linearly polarized light having a known wavelength; a light transmitting reflector having a reflecting surface comprising a surface located substantially parallel to the surface of said specimen, thereby defining a gap between said surface of said specimen and said substantially parallel surface, said reflecting surface reflecting said laser beam; a photosensor for measuring intensity of said laser beam reflected by said reflecting surface of said reflector; a base on which said laser source, said reflector and said photosensor are mounted; a first driving means for relatively moving said base and said specimen in a first direction defining said gap; gap determining means for comparing said intensity of said reflected laser beam with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam, said gap determining means comprising means for controlling said first driving means to maintain said gap at a prescribed value, the unevenness of at least a part of said surface of said specimen being determined on the basis of movement of said first drive means in said first direction at each position in said part of said surface.
Claim 45
Dependent Claim
27 words
Apparatus in accordance with claim 39, wherein: said gap is in the range of one-tenth of a wavelength of said laser beam to two times said wavelength.
Claim 46
Dependent Claim
14 words
Apparatus in accordance with claim 40, wherein: said gap is less than 1 μm.
Claim 47
Dependent Claim
23 words
Apparatus in accordance with claim 41, wherein: said first driving means comprises a piezoelectric element, and said light transmission reflector comprises a prism.
Claim 48
Dependent Claim
29 words
Apparatus in accordance with claim 39, further comprising: a second driving means for relatively moving said base and said specimen in a second direction perpendicular to said first direction.
Claim 49
Independent Claim
196 words
A method for measuring a gap between a surface of a specimen and a surface substantially parallel to the surface of the specimen comprising the steps of: (a) emitting a radiant energy beam of linearly polarized light having a known wavelength incident on a reflecting surface of a radiant energy transmission reflector, said reflecting surface comprising said substantially parallel surface; (b) reflecting said radiant energy beam at said reflecting surface such that when said radiant energy beam reflects from said reflecting surface once said gap is substantially more than several wavelengths of said radiant energy, said radiant energy is substantially and entirely reflected, but once said gap is on the order of less than two wavelengths of said radiant energy, a portion of said radiant energy is transmitted through said gap to said surface of said specimen; (c) measuring the intensity of said radiant energy reflected by said reflecting surface; and (d) comparing said intensity of said reflected radiant energy with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected radiant energy.
Claim 50
Independent Claim
196 words
A method for measuring a gap between a surface of a specimen and a surface substantially parallel to the surface of the specimen comprising the steps of: (a) emitting a radiant energy beam of linearly polarized light having a known wavelength incident on a reflecting surface of a radiant energy transmission reflector, said reflecting surface comprising said substantially parallel surface; (b) reflecting said radiant energy beam at said reflecting surface such that when said radiant energy beam reflects from said reflecting surface once said gap is substantially more than several wavelengths of said radiant energy, said radiant energy is substantially and entirely reflected, but once said gap is on the order of less than two wavelengths of said radiant energy, a portion of said radiant energy is transmitted through said gap to said surface of said specimen; (c) measuring the intensity of said radiant energy reflected by said reflecting surface; and (d) comparing said intensity of said reflected radiant energy with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected radiant energy.
Claim 51
Dependent Claim
30 words
A gap measuring method in accordance with claim 44, wherein: said gap is in the range of one-tenth of a wavelength of said laser beam to two times said wavelength.
Claim 52
Dependent Claim
17 words
A gap measuring method in accordance with claim 45, wherein: said gap is less than 1 μm.
Claim 53
Dependent Claim
54 words
A gap measuring method in accordance with claim 44, wherein: said step (d) comprises the step of: (d-1) relatively moving said light transmission reflector and said specimen in a direction defining said gap so that a value of said gap becomes equal to a prescribed value, thereby maintaining said gap at said prescribed value.
Claim 54
Dependent Claim
70 words
A gap measuring method in accordance with claim 47, wherein: said step (d-1) is performed at plural positions of at least a part of said surface of said specimen, and said step (d) further comprises the step of: (d-2) determining unevenness of said part on the basis of relative movement of said light transmission reflector and said specimen in said direction at each position in said part of said surface.
Claim 55
Dependent Claim
38 words
A gap measuring method in accordance with claim 48, wherein: said radiant energy comprises a laser beam; and said gap is in the range of one-tenth of a wavelength of said laser beam to two times said wavelength.
Claim 56
Dependent Claim
17 words
A gap measuring method in accordance with claim 49, wherein: said gap is less than 1 μm.
Claim 57
Dependent Claim
26 words
A gap measuring method in accordance with claim 50, wherein: said step of emitting a laser beam comprises emitting a laser beam comprising linearly polarized light.
Claim 58
Independent Claim
173 words
A method for maintaining a gap at a prescribed value between a surface of a specimen and a surface substantially parallel to the surface of the specimen comprising the steps of: (a) emitting a laser beam of linearly polarized light having a known wavelength incident on a reflecting surface of a light transmission reflector, said reflecting surface comprising said specific member located substantially parallel to said surface of said specific member across the gap; (b) reflecting said laser beam at said reflecting surface; (c) measuring intensity of said laser beam reflected by said reflecting surface; (d) comparing said intensity of said reflected laser with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam; and (d) relatively moving said light transmission reflector and said specimen in a direction defining said gap so that the value of said gap becomes equal to the prescribed value, thereby maintaining said gap.
Claim 59
Independent Claim
173 words
A method for maintaining a gap at a prescribed value between a surface of a specimen and a surface substantially parallel to the surface of the specimen comprising the steps of: (a) emitting a laser beam of linearly polarized light having a known wavelength incident on a reflecting surface of a light transmission reflector, said reflecting surface comprising said specific member located substantially parallel to said surface of said specific member across the gap; (b) reflecting said laser beam at said reflecting surface; (c) measuring intensity of said laser beam reflected by said reflecting surface; (d) comparing said intensity of said reflected laser with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam; and (d) relatively moving said light transmission reflector and said specimen in a direction defining said gap so that the value of said gap becomes equal to the prescribed value, thereby maintaining said gap.
Claim 60
Dependent Claim
30 words
A gap measuring method in accordance with claim 52, wherein: said gap is in the range of one-tenth of a wavelength of said laser beam to two times aid wavelength.
Claim 61
Dependent Claim
17 words
A gap measuring method in accordance with claim 53, wherein: said gap is less than 1 μm.
Claim 62
Dependent Claim
70 words
A gap measuring method in accordance with claim 54, wherein: said step (e) is performed at plural positions of at least a part of said surface of said specimen, and said step (d) further comprises the step of: (d-2) determining unevenness of said part on the basis of relative movement of said light transmission reflector and said specimen in said direction at each position in said part of said surface.
Claim 63
Independent Claim
220 words
A method for determining the unevenness of the surface of a specimen comprising the steps of (a) emitting a laser beam of linearly polarized light having a known wavelength incident on a reflecting surface of a light transmission reflector, said reflecting surface comprising said specific member located substantially parallel to said surface of said specimen across a gap; (b) reflecting said laser beam at said reflecting surface; (c) measuring intensity of said laser beam reflected by said reflecting surface; (d) comparing said intensity of said reflected laser beam with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam; and (e) relatively moving said light transmission reflector and said specimen in a direction defining said gap so that a value of said gap becomes equal to a prescribed value, thereby maintaining said gap at said prescribed value, said step of relatively moving being performed at plural locations at least a part of said surface of said specimen, and further comprising the step of determining unevenness of said part on the basis of said relative movement of said light transmission reflector and said specimen in said direction at each position in said part of said surface.
Claim 64
Independent Claim
220 words
A method for determining the unevenness of the surface of a specimen comprising the steps of (a) emitting a laser beam of linearly polarized light having a known wavelength incident on a reflecting surface of a light transmission reflector, said reflecting surface comprising said specific member located substantially parallel to said surface of said specimen across a gap; (b) reflecting said laser beam at said reflecting surface; (c) measuring intensity of said laser beam reflected by said reflecting surface; (d) comparing said intensity of said reflected laser beam with calculated values of said intensity according to Maxwell's equations on the condition of total reflection with respect to said gap, thereby determining said gap as a function of said intensity of said reflected laser beam; and (e) relatively moving said light transmission reflector and said specimen in a direction defining said gap so that a value of said gap becomes equal to a prescribed value, thereby maintaining said gap at said prescribed value, said step of relatively moving being performed at plural locations at least a part of said surface of said specimen, and further comprising the step of determining unevenness of said part on the basis of said relative movement of said light transmission reflector and said specimen in said direction at each position in said part of said surface.
Claim 65
Dependent Claim
28 words
A method in accordance with claim 56, wherein: said gap is in the range of one-tenth of a wavelength of said laser beam to two times said wavelength.
Claim 66
Dependent Claim
15 words
A method in accordance with claim 57, wherein: said gap is less than 1 μm.
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