US3823604A
Expired / Lapsed
US
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Method of and apparatus for detecting surface form irregularities
Assignee: Holotron Corp
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Filing: 1972-08-04
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Granted: 1974-07-16
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Expires: 1992-08-04
Abstract
Abstract Method of and apparatus for detecting surface form irregularities by means of the pattern of interference fringes produced when a three-dimensional image of a reference surface form is superimposed upon a surface form having such irregularity.
Inventors
- 👤 J Burch
- 👤 R Wilton
- 👤 C Reid
- 👤 M Wall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:15
CPC Classifications
G; G01; G01B; G01B9/00; G01B9/02; G01B9/021; Y; Y10; Y10S; Y10S359/00; Y10S359/90; Y10S359/902
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
250 words
A method for detecting small differences between at least part of the surface form of a test object at the time of detection and a reference surface form to which said part of the surface form of the test object ''''closely approximates,'''' comprising the operations of: preparing a hologram representing the reference surface form including exposing a photosensitive medium to coherent light, part of which is in the form of a reference beam and part of which is reflected from at least one object to arrive at the photosensitive medium at a finite angle with respect to the reference beam, simultaneously illuminating with coherent light the hologram and said part of the surface form of the test object, the illumination of the hologram being by means of a beam which arrives at the hologram in the same manner as the reference beam arrived at the photosensitive medium during the preparation of the hologram whereby there is reconstructed a three-dimensional image of the reference surface form, the test object being disposed so that the said image is as nearly as possible superimposed on said part of the surface form of the test object, and the illumination of the test object being such that light reflected from the test object arrives at the hologram in substantially the same manner as the reflected light arrived at the photosensitive medium during the preparation of the hologram, and observing the resultant pattern of interference fringes between said image and the surface of the test object.
Claim 2
Independent Claim
250 words
A method for detecting small differences between at least part of the surface form of a test object at the time of detection and a reference surface form to which said part of the surface form of the test object ''''closely approximates,'''' comprising the operations of: preparing a hologram representing the reference surface form including exposing a photosensitive medium to coherent light, part of which is in the form of a reference beam and part of which is reflected from at least one object to arrive at the photosensitive medium at a finite angle with respect to the reference beam, simultaneously illuminating with coherent light the hologram and said part of the surface form of the test object, the illumination of the hologram being by means of a beam which arrives at the hologram in the same manner as the reference beam arrived at the photosensitive medium during the preparation of the hologram whereby there is reconstructed a three-dimensional image of the reference surface form, the test object being disposed so that the said image is as nearly as possible superimposed on said part of the surface form of the test object, and the illumination of the test object being such that light reflected from the test object arrives at the hologram in substantially the same manner as the reflected light arrived at the photosensitive medium during the preparation of the hologram, and observing the resultant pattern of interference fringes between said image and the surface of the test object.
Claim 3
Dependent Claim
18 words
A method according to claim 1 in which the reference surface form is part of an actual object.
Claim 4
Dependent Claim
24 words
A method according to claim 2 in which the test object and the object having the reference form are one and the same object.
Claim 5
Dependent Claim
58 words
A method according to claim 2 as applied to a test object having a surface with a substantial degree of specular reflection, in which the object having the reference form is a master object and the test object is a separate object nominally having an identical form to the test object at least in the portion under examination.
Claim 6
Dependent Claim
23 words
A method according to claim 4 in which a substantial proportion of the light diffusely reflected by the test object is stopped off.
Claim 7
Dependent Claim
34 words
A method according to claim 1 in which the differences in form revealed by the pattern of fringes are evaluated from the spacing and number of fringes and the parameters of the apparatus used.
Claim 8
Dependent Claim
15 words
A method according to claim 1 in which the pattern of fringes is photographically recorded.
Claim 9
Dependent Claim
168 words
A method according to claim 4 in which said part of the surface form of the test object and the reference surface form are cylindrical, in which during the preparation of the hologram the photosensitive medium is disposed to intersect the axis of the reference surface form beyond one end of the reference surface form and is exposed to coherent light derived from a beam directed substantially in the direction of said axis from beyond the other end of the reference surface form, part of the light arriving directly at the photosensitive medium to constitute the reference beam and part of the light being directed to fall at oblique incidence on the reference surface form whence it is reflected to the photosensitive medium, and in which a similar beam of coherent light is subsequently used to illuminate the hologram and the test object while they are disposed in the same spatial relationship as applied to the photosensitive medium and the reference form during the preparation of the holograms.
Claim 10
Dependent Claim
26 words
A method according to claim 8 in which the redirected light is redirected to fall on the reference surface form at a constant angle of incidence.
Claim 11
Dependent Claim
33 words
A method according to claim 3 as applied to examination of an object in vibration in which the pattern of interference fringes between the image and object is visually examined under stroboscopic illumination.
Claim 12
Dependent Claim
202 words
Apparatus for use in the inspection of a test object having a cylindrical surface which exhibits a substantial degree of specular reflection and which has a form nominally identical to that of a cylindrical surface of a given master object, comprising: illuminating means for producing from a source of coherent light a pattern of illumination which is distributed substantially symmetrically around an axis and is such that when the test object is disposed with the cylindrical surface in a given position so as to be coaxial with the pattern of illumination some of the light will fall on this surface at oblique incidence and will thence be reflected to a region of a plane lying perpendicular to said axis while some of the light will reach said region directly, optical means enabling observation to be made of the cylindrical surface of the test object by virtue of the light reflected from this surface to said region, and means for positioning in said region a photographic plate on which has been recorded a hologram from which may be reconstituted, by virtue of the light reaching said region directly, an image disposed in said given position of the cylindrical surface of the master object.
Claim 13
Dependent Claim
202 words
Apparatus for use in the inspection of a test object having a cylindrical surface which exhibits a substantial degree of specular reflection and which has a form nominally identical to that of a cylindrical surface of a given master object, comprising: illuminating means for producing from a source of coherent light a pattern of illumination which is distributed substantially symmetrically around an axis and is such that when the test object is disposed with the cylindrical surface in a given position so as to be coaxial with the pattern of illumination some of the light will fall on this surface at oblique incidence and will thence be reflected to a region of a plane lying perpendicular to said axis while some of the light will reach said region directly, optical means enabling observation to be made of the cylindrical surface of the test object by virtue of the light reflected from this surface to said region, and means for positioning in said region a photographic plate on which has been recorded a hologram from which may be reconstituted, by virtue of the light reaching said region directly, an image disposed in said given position of the cylindrical surface of the master object.
Claim 14
Dependent Claim
30 words
Apparatus according to claim 11 in which the means enabling observation to be made is a telescope system incorporating a stop in the path of direct light from the source.
Claim 15
Dependent Claim
32 words
Apparatus according to claim 11 for inspection of the external surface of a cylinder in which said illuminating means comprises a diffusing screen which allows some light to pass directly through it.
Claim 16
Dependent Claim
31 words
Apparatus according to claim 11 for inspection of a cylindrical bore in which the same illuminating means comprises an annular conical lens to direct light at oblique incidence on said surface.
Claim 17
Independent Claim
187 words
A method of determining small differences in position or shape of an object due to successive first and second conditions comprising the steps of, directing coherent light onto the object when subject to the first condition to provide an object-bearing beam from the object, positioning a detector sensitive to said coherent light at a distance spaced from the object and in the path of the object-bearing beam, directing light coherent with said first-named coherent light as a reference beam onto the detector at a finite angle with respect to the object-bearing beam to produce an interference pattern of fringes on the detector by interaction of a wavefront from the first object and the reference beam, illuminating with coherent light the interference pattern and the object when subject to the second condition to produce a virtual image of the object when subject to the first condition so that its wavefront coincides with a wavefront from the object when subject to the seconD condition, and detecting the differences between the object due to the different conditions by noting the interference fringes resulting from any point where said object varies.
Claim 18
Independent Claim
187 words
A method of determining small differences in position or shape of an object due to successive first and second conditions comprising the steps of, directing coherent light onto the object when subject to the first condition to provide an object-bearing beam from the object, positioning a detector sensitive to said coherent light at a distance spaced from the object and in the path of the object-bearing beam, directing light coherent with said first-named coherent light as a reference beam onto the detector at a finite angle with respect to the object-bearing beam to produce an interference pattern of fringes on the detector by interaction of a wavefront from the first object and the reference beam, illuminating with coherent light the interference pattern and the object when subject to the second condition to produce a virtual image of the object when subject to the first condition so that its wavefront coincides with a wavefront from the object when subject to the seconD condition, and detecting the differences between the object due to the different conditions by noting the interference fringes resulting from any point where said object varies.
Claim 19
Independent Claim
175 words
A method of determining small differences in position or shape of an object due to successive first and second conditions comprising the steps of: directing coherent light onto the object when subject to the first condition to provide an object bearing beam from the object, positioning a detector sensitive to said coherent light at a distance spaced from the object and in the path of the object-bearing beam, directing reference light coherent with said first-named coherent light onto the detector to produce an interference pattern of fringes on the detector by interaction of a wavefront from the first object and the reference light, illuminating with coherent light the interference pattern and the object when subject to the second condition to produce a virtual image of the object when subject to the first condition so that its wavefront coincides with a wavefront from the object when subject to the second condition, and detecting the differences between the object due to the different conditions by noting the interference fringes resulting from any point where said object varies,
Claim 20
Independent Claim
175 words
A method of determining small differences in position or shape of an object due to successive first and second conditions comprising the steps of: directing coherent light onto the object when subject to the first condition to provide an object bearing beam from the object, positioning a detector sensitive to said coherent light at a distance spaced from the object and in the path of the object-bearing beam, directing reference light coherent with said first-named coherent light onto the detector to produce an interference pattern of fringes on the detector by interaction of a wavefront from the first object and the reference light, illuminating with coherent light the interference pattern and the object when subject to the second condition to produce a virtual image of the object when subject to the first condition so that its wavefront coincides with a wavefront from the object when subject to the second condition, and detecting the differences between the object due to the different conditions by noting the interference fringes resulting from any point where said object varies,
Claim 21
Independent Claim
63 words
A method of analyzing the vibrations of an object comprising the steps of: producing a hologram of the object at rest, illuminating the hologram and the object with coherent light to produce an image of the object which coincides with said object, vibrating the object, and detecting the interference fringes produced by the interaction of wavefronts from the image and the vibrating object.
Claim 22
Independent Claim
63 words
A method of analyzing the vibrations of an object comprising the steps of: producing a hologram of the object at rest, illuminating the hologram and the object with coherent light to produce an image of the object which coincides with said object, vibrating the object, and detecting the interference fringes produced by the interaction of wavefronts from the image and the vibrating object.
Claim 23
Independent Claim
125 words
A method of comparing wavefronts of similar objects utilizing the reconstruction of an image of a first object recorded as a hologram produced from a pattern of interference fringes resulting from illuminating the first object with coherent light together with a background of coherent light comprising the steps of: illuminating the hologram and a similar object with coherent light in the same manner as in the construction of the hologram to produce a virtual image of said first object separated from the real image thereof so that the wavefront of said virtual image coincides with a wavefront from the similar object, and detecting the difference between said objects by noting interference fringes resulting from any point where said similar object varies from said first object.
Claim 24
Independent Claim
125 words
A method of comparing wavefronts of similar objects utilizing the reconstruction of an image of a first object recorded as a hologram produced from a pattern of interference fringes resulting from illuminating the first object with coherent light together with a background of coherent light comprising the steps of: illuminating the hologram and a similar object with coherent light in the same manner as in the construction of the hologram to produce a virtual image of said first object separated from the real image thereof so that the wavefront of said virtual image coincides with a wavefront from the similar object, and detecting the difference between said objects by noting interference fringes resulting from any point where said similar object varies from said first object.
Claim 25
Independent Claim
145 words
The method of detecting small displacements of an object resulting from small forces thereon comprising the steps of: making a hologram of the object while it is stationary comprising the steps of, directing coherent light from the object against a first surface of a photographic recording medium at a first angle, and directing a reference coherent light beam, phase related to the light from the object, against the first surface at a second angle, displacing at least part of the object, making a second hologram of the object in its displaced position comprising the steps of directing coherent light from the displaced object against the first surface of the hologram recording medium at the first angle, and directing a reference coherent light beam, phase related to the light from the displaced object, against the first surface of the hologram recording medium at the second angle.
Claim 26
Independent Claim
145 words
The method of detecting small displacements of an object resulting from small forces thereon comprising the steps of: making a hologram of the object while it is stationary comprising the steps of, directing coherent light from the object against a first surface of a photographic recording medium at a first angle, and directing a reference coherent light beam, phase related to the light from the object, against the first surface at a second angle, displacing at least part of the object, making a second hologram of the object in its displaced position comprising the steps of directing coherent light from the displaced object against the first surface of the hologram recording medium at the first angle, and directing a reference coherent light beam, phase related to the light from the displaced object, against the first surface of the hologram recording medium at the second angle.
Claim 27
Independent Claim
86 words
A method of determining the difference between similar objects comprising the steps of: producing a hologram of a first object, illuminating said hologram and a second similar object with coherent light to produce a virtual image of said first object separated from the real image thereof so that the wavefront of said virtual image coincides with a wavefront from said second object, and detecting the difference between said objects by noting interference fringes resulting from any point where said second object varies from said first object.
Claim 28
Independent Claim
86 words
A method of determining the difference between similar objects comprising the steps of: producing a hologram of a first object, illuminating said hologram and a second similar object with coherent light to produce a virtual image of said first object separated from the real image thereof so that the wavefront of said virtual image coincides with a wavefront from said second object, and detecting the difference between said objects by noting interference fringes resulting from any point where said second object varies from said first object.
Claim 29
Dependent Claim
96 words
A meThod according to claim 4 as applied to a cylindrical test object in which during the exposure of the hologram and subsequent observation the object is disposed with its axis extending in the same direction as a beam of coherent light which is directed towards one end of the object, part of the light being directed past and parallel to the object and part being redirected to fall on the surface of the object at oblique incidence, the photosensitive medium in which the hologram is recorded being located beyond the other end of the object.
Claim 30
Independent Claim
74 words
A method of determining small differences in position or shape of an object due to successive first and second conditions comprising the steps of: producing holographic information of an object when subject to the first condition, producing holographic information of the object when subject to the second condition, comparing the holographic information obtained under both of said conditions, and detecting the differences in said holographic information resulting from any point where said object varies.
Claim 31
Independent Claim
74 words
A method of determining small differences in position or shape of an object due to successive first and second conditions comprising the steps of: producing holographic information of an object when subject to the first condition, producing holographic information of the object when subject to the second condition, comparing the holographic information obtained under both of said conditions, and detecting the differences in said holographic information resulting from any point where said object varies.
Claim 32
Independent Claim
76 words
A method of determining differences between similar objects comprising the steps of: producing first holographic information of a first object, storing said first holographic information, producing second holographic information of a second similar object, comparing the stored holographic information of the first object with the second holographic information of the second object, and detecting the differences in said first and second holographic information resulting from any point where said second object varies from said first object.
Claim 33
Independent Claim
76 words
A method of determining differences between similar objects comprising the steps of: producing first holographic information of a first object, storing said first holographic information, producing second holographic information of a second similar object, comparing the stored holographic information of the first object with the second holographic information of the second object, and detecting the differences in said first and second holographic information resulting from any point where said second object varies from said first object.
Claim 34
Independent Claim
92 words
A method of measuring small dimensional changes in an object by hologram interferometry, comprising the steps of: illuminating an object in first and second conditions to form first and second reflected object beams respectively, generating a reference beam, combining said first reflected object beam with said reference beam and said second reflected object beam with said reference beam to form individual first and second interference patterns respectively, and comparing said first and second interference patterns to detect any differences in said interference patterns as a measure of dimensional changes in the object.
Claim 35
Independent Claim
92 words
A method of measuring small dimensional changes in an object by hologram interferometry, comprising the steps of: illuminating an object in first and second conditions to form first and second reflected object beams respectively, generating a reference beam, combining said first reflected object beam with said reference beam and said second reflected object beam with said reference beam to form individual first and second interference patterns respectively, and comparing said first and second interference patterns to detect any differences in said interference patterns as a measure of dimensional changes in the object.
Claim 36
Independent Claim
99 words
A method of measuring small dimensional changes in an object by hologram interferometry, comprising the steps of: illuminating an object in first and second conditions to form first and second reflected object beams respectively, generating a reference light beam, combining said first reflected object beam with said reference beam and said second reflected object beam with said reference beam to form individual first and second interference patterns respectively, producing visual outputs from each of said interference patterns and comparing said visual outputs to detect any differences in said interference patterns as a measure of dimensional changes in the object.
Claim 37
Independent Claim
99 words
A method of measuring small dimensional changes in an object by hologram interferometry, comprising the steps of: illuminating an object in first and second conditions to form first and second reflected object beams respectively, generating a reference light beam, combining said first reflected object beam with said reference beam and said second reflected object beam with said reference beam to form individual first and second interference patterns respectively, producing visual outputs from each of said interference patterns and comparing said visual outputs to detect any differences in said interference patterns as a measure of dimensional changes in the object.
Claim 38
Independent Claim
100 words
A method of measuring small dimensional changes in an object by hologram interferometry, comprising the steps of: illuminating an object in a first condition to form a reflected object beam, generating a reference light beam, combining said reflected object beam with said reference beam to form an interference pattern, storing said interference pattern, producing a visual output from said stored interference pattern, illuminating the object in a second condition, and comparing said visual output with a wavefront from said illuminated object in its second condition to detect any differences by noting interference fringes resulting from dimensional changes in the object.
Claim 39
Independent Claim
100 words
A method of measuring small dimensional changes in an object by hologram interferometry, comprising the steps of: illuminating an object in a first condition to form a reflected object beam, generating a reference light beam, combining said reflected object beam with said reference beam to form an interference pattern, storing said interference pattern, producing a visual output from said stored interference pattern, illuminating the object in a second condition, and comparing said visual output with a wavefront from said illuminated object in its second condition to detect any differences by noting interference fringes resulting from dimensional changes in the object.
Claim 40
Dependent Claim
72 words
A method according to claim 24 in which after an exposure of a photosensitive medium to produce a hologram corresponding to said first condition at least one fresh exposure is made under at least said second condition before the photosensitive medium is processed, whereby a multiple hologram is prodUced which records diffraction patterns of at least two forms of the object and a pattern of fringes corresponding to the changes in form.
References Cited (Backward Citations)
US3083615A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-15 | 1978-01-14 | 1978-07-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-15 | 1982-01-14 | 1982-07-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-15 | 1986-01-14 | 1986-07-16 | $7700.00 | Window Closed / Lapsed |