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WO2010020338A1 - Flaw detection - Google Patents

Flaw detection Download PDF

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Publication number
WO2010020338A1
WO2010020338A1 PCT/EP2009/005517 EP2009005517W WO2010020338A1 WO 2010020338 A1 WO2010020338 A1 WO 2010020338A1 EP 2009005517 W EP2009005517 W EP 2009005517W WO 2010020338 A1 WO2010020338 A1 WO 2010020338A1
Authority
WO
WIPO (PCT)
Prior art keywords
polariser
light
image recorder
image
reflected
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2009/005517
Other languages
French (fr)
Inventor
Adam Philip Chir
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rolls Royce PLC
Original Assignee
Rolls Royce PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rolls Royce PLC filed Critical Rolls Royce PLC
Publication of WO2010020338A1 publication Critical patent/WO2010020338A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84Systems specially adapted for particular applications
    • G01N21/88Investigating the presence of flaws or contamination
    • G01N21/8806Specially adapted optical and illumination features
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/21Polarisation-affecting properties

Definitions

  • This invention concerns a method of detecting flaws in a surface, and also apparatus for detecting flaws in a surface.
  • monitoring has been carried out using an ultrasound transducer connected to a diagnostic machine. This is passed over the surface being monitored which requires to have a couplant such as oil or water thereon. Monitoring may be carried out by one of two methods :
  • a reflection (or pulse-echo) system which utilises the transducer to perform both the transmission and the reception of the pulsed waves.
  • the ultrasonic waveform is reflected by interfaces on the sample such as the back surface of the object or from an imperfection within the object. Imperfections within the object decrease the return time for the ultrasonic waveform.
  • Attenuation (or through-transmission) which requires a separate receiver installed on the opposite surface of the object. The receiver detects the intensity that has reached the surface after travelling through the medium. Imperfections in the space between the transmitter and receiver reduce the amount of sound transmitted.
  • the surface must be accessible to transmit ultrasound and for a coupling medium to be located thereon. This presents a particular barrier for instance when inspecting in service aero engines. Furthermore, before a coupling medium can be applied the surface must be prepared by cleaning. Also, such a system is not usable with exceptionally thin materials nor non homogeneous materials . Linear defects parallel to the transducer may not be detected. Reference standards are also required for equipment calibration and also the characterization of flaws . Unpolarised light is partially polarised upon reflection from material surfaces, described by the intensity of reflected light components parallel and perpendicular to the plane of incidence. The intensity of reflected parallel and perpendicular components is dependent upon both the angle of light incidence and the angle of observation.
  • a method of detecting flaws in a surface comprising recording light reflected off the surface through a polariser at a number of different orientations of the polariser, and calculating the variation in light intensity recorded across the surface at different locations on the surface at different polariser orientations, whereby a significant light intensity variation at any point suggests the presence of a flaw.
  • Unpolarised light may be shone onto the surface.
  • the polariser may be rotated between different orientations, and the polariser may be rotated in axial increments between measuring positions, and the light intensity may be recorded at each measuring position.
  • An image of reflected light from the surface may be produced for each polarised orientation, with the images being compared to determine the variation of reflected light intensity across the surface.
  • apparatus for detecting flaws in a surface comprising a polariser, a mounting arrangement for the polariser which permits rotation of the polariser, and an image recorder assembly arranged to produce an image of light reflected from the surface which passes through the polariser.
  • the apparatus may include a light source for shining unpolarised light onto the surface.
  • the light source may extend in an annular configuration around a receiving part of the image recorder assembly.
  • the image recorder assembly may include a receiving part with an optical relay extending therefrom to an image recorder.
  • the image recorder may be a CCD digital camera.
  • the light source may include a plurality of illumination fibres, which fibres may surround the optical relay in an annular configuration.
  • the image recorder assembly may include a computer arranged to compare images of reflected light at different orientations of the polariser.
  • the mounting arrangement may include a frame which mounts the polariser, and a motor for sequentially rotating the frame.
  • the frame may include a plurality of openings surrounding the polariser, the openings being aligned with respective ones of the illumination fibres such that light from the fibres can pass through the openings .
  • Fig. 1 is a diagrammatic cross sectional side view through flaw detection apparatus according to the invention
  • Fig. 2 is a diagrammatic end view of the apparatus of Fig. 1;
  • Fig. 3 is a diagrammatic view illustrating operation of the apparatus of Fig. 1;
  • FIG. 4 is a further diagrammatic view illustrating operation of the apparatus of Fig. 1;
  • Fig. 5 is a still further view illustrating operation of the apparatus of Fig. 1; and
  • Fig. 6 is a yet further view illustrating operation of the apparatus of Fig. 1.
  • Figs. 1 and 2 show a flaw detection apparatus 10, which in Fig. 1 is shown detecting flaws in a surface 12 of an article 14.
  • the apparatus 10 includes an image recorder in the form of a CCD digital camera 16 connected to a control computer 18.
  • An elongate optical relay 20 extends from the camera 16.
  • the relay 20 is surrounded in an annular configuration by a plurality of illumination fibres 22.
  • An objective lens 24 is provided on the distal end of the optical relay
  • a polarising arrangement 26 is mounted to the optical relay 20 and illumination fibres 22.
  • the arrangement 26 includes a rotating frame 28 which centrally mounts a linear polariser 30.
  • a linear polariser 30 Arranged around the polariser 30 in an annular ring are a plurality of smaller openings 32 which provide light passages alignable with the illumination fibres 22 to permit light to pass through the passages .
  • a gear 34 is provided around the outside of the frame
  • gear 34 is engageable with a drive gear 36 which is drivably connected to a miniature motor 38.
  • a lead 40 extends from the motor 38 to provide signals thereto from the computer 18.
  • the apparatus 10 can operate as follows. Light is shone from the illuminating fibres 22 through the openings 32 onto the surface 12. Some reflected light from the surface 12 will pass through the polariser 30 and along the optical relay 20 to the camera 16. This will produce an image 42 of the reflected light as shown diagrammatically in Fig. 3. The image 42 shows a flaw 44 on the surface 12. The motor 38 is then operated to rotate the drive gear 36 and hence frame gear 34 a small amount, and a further image is obtained by the camera 16. The polariser 30 can for instance be rotated through 15° increments to produce twelve images 42 through a 180° rotation as shown in Fig. 4, which illustrates the different light intensity reflected off the flaw 44 shown in Fig. 3, for different orientations of the polariser 30.
  • the images 42 at the different orientations are interrogated using the computer 18 to find the minimum and maximum recorded intensities at each pixel location.
  • Smooth areas 46 (Fig. 5) on the surface 12 will not exhibit much polarisation so the minimum and maximum intensities detected are similar.
  • Features on the surface 12 such as the flaw 44 will produce changes in the amount of reflected intensity at different orientations of the polariser 30, and this point is illustrated in Fig. 5 where there is little or no distinction between the maximum and minimum detected intensities from the smooth parts, but there is a measurable distinction between the maximum and minimum intensities for the flaw 44.
  • a normalised polarisation function (p) is calculated at each pixel location using the equation:
  • I max and I m i n are the maximum and minimum detected intensities from the image samples at each pixel location.
  • An image 48 is then constructed based on the normalised polarisation function which has value 0 - 1) as shown in Fig. 6. This shows that the smooth parts 46 of the surface 12 have little or no polarization, but the flaw 44 has a very strong normalised polarisation function and can easily be detected by standard techniques. Further standard image processing can be applied to automatically detect intense polarisation areas to indicate cracks or other flaws, for instance using image edge detection algorithms.
  • the present method and apparatus can be used within confined spacings .
  • the arrangement of the present invention is capable of detecting surface defects on any surface irrespective of thickness, and as all materials will demonstrate a degree of reflective polarisation.
  • the invention is thus usable in a wide range of applications, including for instance inspecting in service aero engines which has previously been a difficult task.
  • the effect exploited in the present invention is that of "partial polarisation" of un-polarised light. It is important to note the absence of a first polarising lens, as used in prior art devices; the present invention only features the so-called “analysis” polarising lens. Methods disclosed in the prior art require calibration and characterisation of surface flaws (against a known sample) that are then compared to the subject sample. Further those that are reliant on polarised incident light require prior knowledge of the relative angle between the incident light and the detector. The thrust of the present invention is that no such sample or understanding of the lighting condition is required as interrogation of the relative change in the partial polarisation parameter searching for rapid changes in the parameter indicative of surface defects.
  • the advantage of this technique arises as there is no requirement to understand or control the illuminating source, thus the technique can be applied for remote inspection (by boroscoping or otherwise) of defects for (amongst others) gas turbine components, remote inspection of boiler / heat exchanger internals, etc where physical access is restricted.
  • the proposed inspection head is compact relative to prior art arrangements and enables access to space constrained locations.
  • a flexible fiber optic relay could be used. If the optical relay material is non polarising, the polariser could be mounted at the proximal end of the optical relay.
  • the image recorder may be other than a CCD digital camera.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)

Abstract

A method of and apparatus for detecting flaws in a surface (12) is disclosed. The method comprises recording light reflected off the surface (12) through a polariser (30) at a number of different orientations of the polariser (30), and calculating the variation in light intensity recorded across the surface (12) at different locations on the surface at different polariser orientations, whereby a significant light intensity variation at any point suggests the presence of a flaw. The apparatus (10) comprises a polariser (30), a mounting arrangement (26) for the polariser (30) which permits rotation of the polariser (30), and an image recorder assembly (16) arranged to produce an image (42) of light reflected from the surface (12) which passes through the polariser (30)

Description

FLAW DETECTION
This invention concerns a method of detecting flaws in a surface, and also apparatus for detecting flaws in a surface.
It is often required to monitor for flaws in a surface of a component, such as for instance the formation of cracks or other defects. Such monitoring may be required as part of a maintenance or inspection program in applications such as aircraft or other transport systems.
Conventionally such monitoring has been carried out using an ultrasound transducer connected to a diagnostic machine. This is passed over the surface being monitored which requires to have a couplant such as oil or water thereon. Monitoring may be carried out by one of two methods :
• A reflection (or pulse-echo) system which utilises the transducer to perform both the transmission and the reception of the pulsed waves. The ultrasonic waveform is reflected by interfaces on the sample such as the back surface of the object or from an imperfection within the object. Imperfections within the object decrease the return time for the ultrasonic waveform. • Attenuation (or through-transmission) which requires a separate receiver installed on the opposite surface of the object. The receiver detects the intensity that has reached the surface after travelling through the medium. Imperfections in the space between the transmitter and receiver reduce the amount of sound transmitted.
There are a number of drawbacks with such arrangements. Firstly the surface must be accessible to transmit ultrasound and for a coupling medium to be located thereon. This presents a particular barrier for instance when inspecting in service aero engines. Furthermore, before a coupling medium can be applied the surface must be prepared by cleaning. Also, such a system is not usable with exceptionally thin materials nor non homogeneous materials . Linear defects parallel to the transducer may not be detected. Reference standards are also required for equipment calibration and also the characterization of flaws . Unpolarised light is partially polarised upon reflection from material surfaces, described by the intensity of reflected light components parallel and perpendicular to the plane of incidence. The intensity of reflected parallel and perpendicular components is dependent upon both the angle of light incidence and the angle of observation.
According to a first aspect of the present invention there is provided a method of detecting flaws in a surface, the method comprising recording light reflected off the surface through a polariser at a number of different orientations of the polariser, and calculating the variation in light intensity recorded across the surface at different locations on the surface at different polariser orientations, whereby a significant light intensity variation at any point suggests the presence of a flaw. Unpolarised light may be shone onto the surface. The polariser may be rotated between different orientations, and the polariser may be rotated in axial increments between measuring positions, and the light intensity may be recorded at each measuring position.
An image of reflected light from the surface may be produced for each polarised orientation, with the images being compared to determine the variation of reflected light intensity across the surface. According to a second aspect of the invention there is provided apparatus for detecting flaws in a surface, the apparatus comprising a polariser, a mounting arrangement for the polariser which permits rotation of the polariser, and an image recorder assembly arranged to produce an image of light reflected from the surface which passes through the polariser.
The apparatus may include a light source for shining unpolarised light onto the surface. The light source may extend in an annular configuration around a receiving part of the image recorder assembly.
The image recorder assembly may include a receiving part with an optical relay extending therefrom to an image recorder. The image recorder may be a CCD digital camera. The light source may include a plurality of illumination fibres, which fibres may surround the optical relay in an annular configuration.
The image recorder assembly may include a computer arranged to compare images of reflected light at different orientations of the polariser.
The mounting arrangement may include a frame which mounts the polariser, and a motor for sequentially rotating the frame. The frame may include a plurality of openings surrounding the polariser, the openings being aligned with respective ones of the illumination fibres such that light from the fibres can pass through the openings .
An embodiment of the present invention will now be described by way of example and with reference to the accompanying drawings, in which :- Fig. 1 is a diagrammatic cross sectional side view through flaw detection apparatus according to the invention;
Fig. 2 is a diagrammatic end view of the apparatus of Fig. 1; Fig. 3 is a diagrammatic view illustrating operation of the apparatus of Fig. 1;
Fig. 4 is a further diagrammatic view illustrating operation of the apparatus of Fig. 1; Fig. 5 is a still further view illustrating operation of the apparatus of Fig. 1; and
Fig. 6 is a yet further view illustrating operation of the apparatus of Fig. 1.
Figs. 1 and 2 show a flaw detection apparatus 10, which in Fig. 1 is shown detecting flaws in a surface 12 of an article 14. The apparatus 10 includes an image recorder in the form of a CCD digital camera 16 connected to a control computer 18.
An elongate optical relay 20 extends from the camera 16. The relay 20 is surrounded in an annular configuration by a plurality of illumination fibres 22. An objective lens 24 is provided on the distal end of the optical relay
20. A polarising arrangement 26 is mounted to the optical relay 20 and illumination fibres 22. The arrangement 26 includes a rotating frame 28 which centrally mounts a linear polariser 30. Arranged around the polariser 30 in an annular ring are a plurality of smaller openings 32 which provide light passages alignable with the illumination fibres 22 to permit light to pass through the passages .
A gear 34 is provided around the outside of the frame
28, and the gear 34 is engageable with a drive gear 36 which is drivably connected to a miniature motor 38. A lead 40 extends from the motor 38 to provide signals thereto from the computer 18.
In use, the apparatus 10 can operate as follows. Light is shone from the illuminating fibres 22 through the openings 32 onto the surface 12. Some reflected light from the surface 12 will pass through the polariser 30 and along the optical relay 20 to the camera 16. This will produce an image 42 of the reflected light as shown diagrammatically in Fig. 3. The image 42 shows a flaw 44 on the surface 12. The motor 38 is then operated to rotate the drive gear 36 and hence frame gear 34 a small amount, and a further image is obtained by the camera 16. The polariser 30 can for instance be rotated through 15° increments to produce twelve images 42 through a 180° rotation as shown in Fig. 4, which illustrates the different light intensity reflected off the flaw 44 shown in Fig. 3, for different orientations of the polariser 30.
The images 42 at the different orientations are interrogated using the computer 18 to find the minimum and maximum recorded intensities at each pixel location. Smooth areas 46 (Fig. 5) on the surface 12 will not exhibit much polarisation so the minimum and maximum intensities detected are similar. Features on the surface 12 such as the flaw 44 will produce changes in the amount of reflected intensity at different orientations of the polariser 30, and this point is illustrated in Fig. 5 where there is little or no distinction between the maximum and minimum detected intensities from the smooth parts, but there is a measurable distinction between the maximum and minimum intensities for the flaw 44.
A normalised polarisation function (p) is calculated at each pixel location using the equation:
_j max nun max nun
Where Imax and Imin are the maximum and minimum detected intensities from the image samples at each pixel location. An image 48 is then constructed based on the normalised polarisation function which has value 0 - 1) as shown in Fig. 6. This shows that the smooth parts 46 of the surface 12 have little or no polarization, but the flaw 44 has a very strong normalised polarisation function and can easily be detected by standard techniques. Further standard image processing can be applied to automatically detect intense polarisation areas to indicate cracks or other flaws, for instance using image edge detection algorithms.
There is thus described a method and apparatus for detecting flaws such as cracks in a surface which provide a number of advantages relative to previous arrangements . The present method and apparatus can be used within confined spacings . The arrangement of the present invention is capable of detecting surface defects on any surface irrespective of thickness, and as all materials will demonstrate a degree of reflective polarisation. There is no requirement for the use of a coupling medium or actual surface contect. The invention is thus usable in a wide range of applications, including for instance inspecting in service aero engines which has previously been a difficult task.
The effect exploited in the present invention is that of "partial polarisation" of un-polarised light. It is important to note the absence of a first polarising lens, as used in prior art devices; the present invention only features the so-called "analyser" polarising lens. Methods disclosed in the prior art require calibration and characterisation of surface flaws (against a known sample) that are then compared to the subject sample. Further those that are reliant on polarised incident light require prior knowledge of the relative angle between the incident light and the detector. The thrust of the present invention is that no such sample or understanding of the lighting condition is required as interrogation of the relative change in the partial polarisation parameter searching for rapid changes in the parameter indicative of surface defects.
The advantage of this technique arises as there is no requirement to understand or control the illuminating source, thus the technique can be applied for remote inspection (by boroscoping or otherwise) of defects for (amongst others) gas turbine components, remote inspection of boiler / heat exchanger internals, etc where physical access is restricted. The proposed inspection head is compact relative to prior art arrangements and enables access to space constrained locations.
Various modifications may be made without departing from the scope of the invention. For instance the method may be carried out using different apparatus. A flexible fiber optic relay could be used. If the optical relay material is non polarising, the polariser could be mounted at the proximal end of the optical relay. The image recorder may be other than a CCD digital camera.

Claims

1. A method of detecting flaws in a surface (12), the method comprising recording light reflected off the surface (12) through a polariser (30) at a number of different orientations of the polariser (30) , and calculating the variation in light intensity recorded across the surface
(12) at different locations on the surface at different polariser orientations, whereby a significant light intensity variation at any point suggests the presence of a flaw.
2. A method according to claim 1, characterised in that unpolarised light is shone onto the surface (12) .
3. A method according to claims 1 or 2 , characterised in that the polariser 30 is rotated between different orientations .
4. A method according to claim 3 , characterised in that the polariser (30) is rotated in axial increments between measuring positions, and the light intensity is recorded at each measuring position.
5. A method according to any of the preceding claims, in which an image (42) of reflected light from the surface (12) is produced for each polarised orientation, with the images (42) being compared to determine the variation of reflected light intensity across the surface (12).
6. Apparatus (10) for detecting flaws (14) in a surface (12) , the apparatus (10) comprising a polariser (30) , a mounting arrangement (26) for the polariser (30) which permits rotation of the polariser (30) , and an image recorder assembly (16) arranged to produce an image (42) of light reflected from the surface (12) which passes through the polariser (30) .
7. Apparatus according to claim 6, characterised in that the apparatus (10) includes a light source (22) for shining unpolarised light onto the surface.
8. Apparatus according to claim 7, characterised in that the light source (22) extends in an annular configuration around a receiving part (20) of the image recorder assembly.
9. Apparatus according to claims 7 or 8, characterised in that the image recorder assembly includes a receiving part (24) with an optical relay (20) extending therefrom to an image recorder (16) .
10. Apparatus according to claim 9, characterised in that the image recorder is a CCD digital camera (16) .
11. Apparatus according to any of claims 7 to 10, characterised in that the light source includes a plurality of illumination fibres (22).
12. Apparatus according to claim 11 when dependent on claims 9 or 10, characterised in that fibres (22) surround the optical relay (20) in an annular configuration.
13. Apparatus according to any of claims 6 to 12, characterised in that the image recorder assembly includes a computer (18) arranged to compare images of reflected light at different orientations of the polariser (30) .
14. Apparatus according to any of claims 6 to 13 , characterised in that the mounting arrangement includes a frame (28) which mounts the polariser (30), and a motor (38) for sequentially rotating the frame (28) .
15. Apparatus according to claim 14 when dependent on claim 11, characterised in that the frame (28) includes a plurality of openings (32) surrounding the polariser (30), the openings (32) being aligned with respective ones of the illumination fibres (22) such that light from the fibres (22) can pass through the openings (32).
16. A method of detecting flaws in a surface, the method being substantially as hereinbefore described and with reference to the accompanying drawings .
17. Apparatus for detecting flaws in a surface, the apparatus being substantially as hereinbefore described and with reference to the accompanying drawings.
PCT/EP2009/005517 2008-08-18 2009-07-30 Flaw detection Ceased WO2010020338A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0814947A GB0814947D0 (en) 2008-08-18 2008-08-18 Flaw detection
GB0814947.8 2008-08-18

Publications (1)

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WO2010020338A1 true WO2010020338A1 (en) 2010-02-25

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PCT/EP2009/005517 Ceased WO2010020338A1 (en) 2008-08-18 2009-07-30 Flaw detection

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8744166B2 (en) 2011-11-03 2014-06-03 United Technologies Corporation System and method for multiple simultaneous automated defect detection
US8761490B2 (en) 2011-11-03 2014-06-24 United Technologies Corporation System and method for automated borescope inspection user interface
US8781209B2 (en) 2011-11-03 2014-07-15 United Technologies Corporation System and method for data-driven automated borescope inspection
US8781210B2 (en) 2011-11-09 2014-07-15 United Technologies Corporation Method and system for automated defect detection
US8792705B2 (en) 2011-11-03 2014-07-29 United Technologies Corporation System and method for automated defect detection utilizing prior data
US9471057B2 (en) 2011-11-09 2016-10-18 United Technologies Corporation Method and system for position control based on automated defect detection feedback

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030836A (en) * 1975-10-28 1977-06-21 The United States Of America As Represented By The Secretary Of The Air Force Method for mapping surfaces with respect to ellipsometric parameters
US5028138A (en) * 1989-05-23 1991-07-02 Wolff Lawrence B Method of and apparatus for obtaining object data by machine vision form polarization information
US5774212A (en) * 1997-03-19 1998-06-30 General Electric Co. Method and apparatus for detecting and analyzing directionally reflective surface flaws
US20070206183A1 (en) * 1999-07-08 2007-09-06 Ppt Vision, Inc. Method and apparatus for auto-adjusting illumination

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030836A (en) * 1975-10-28 1977-06-21 The United States Of America As Represented By The Secretary Of The Air Force Method for mapping surfaces with respect to ellipsometric parameters
US5028138A (en) * 1989-05-23 1991-07-02 Wolff Lawrence B Method of and apparatus for obtaining object data by machine vision form polarization information
US5774212A (en) * 1997-03-19 1998-06-30 General Electric Co. Method and apparatus for detecting and analyzing directionally reflective surface flaws
US20070206183A1 (en) * 1999-07-08 2007-09-06 Ppt Vision, Inc. Method and apparatus for auto-adjusting illumination

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8744166B2 (en) 2011-11-03 2014-06-03 United Technologies Corporation System and method for multiple simultaneous automated defect detection
US8761490B2 (en) 2011-11-03 2014-06-24 United Technologies Corporation System and method for automated borescope inspection user interface
US8781209B2 (en) 2011-11-03 2014-07-15 United Technologies Corporation System and method for data-driven automated borescope inspection
US8792705B2 (en) 2011-11-03 2014-07-29 United Technologies Corporation System and method for automated defect detection utilizing prior data
US8781210B2 (en) 2011-11-09 2014-07-15 United Technologies Corporation Method and system for automated defect detection
US9471057B2 (en) 2011-11-09 2016-10-18 United Technologies Corporation Method and system for position control based on automated defect detection feedback

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