Fluorescent penetrant measurement borescope

• US 5,202,758 A
• Filed: 09/16/1991
• Issued: 04/13/1993
• Est. Priority Date: 09/16/1991
• Status: Expired due to Fees

• Current Assignee: Everest Visual Inspection Technologies, Inc. (GE Aerospace)
• Original Assignee: Welch Allyn Incorporated
• Inventors: Tamburrino, Richard A.
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Burgess, Glenton B.
• Application Number:
  US07/760,495
• Time in Patent Office: 575 Days
• Field of Search: 358/98, 358/107, 358/117, 358/110, 128/6, 128/4, 250/461.1, 324/219
• US Class Current: 348/68
• CPC Class Codes: A61B 1/05 characterised by the image sensor, e.g. camera, being in the distal end portion
• CPC Class Codes: G01B 11/02 for measuring length, width or thickness G01B11/08 takes precedence
• CPC Class Codes: G02B 23/2469 using optical fibres
• CPC Class Codes: H04N 23/555 for picking-up images in sites, inaccessible due to their dimensions or hazardous conditions, e.g. endoscopes or borescopes
• CPC Class Codes: H04N 23/56 provided with illuminating means

Abstract

A fluorescent borescope is provided that provides target measuring capabilities. The device includes a primary ultraviolet light source and a secondary visible light source that has a light path spaced apart from the primary light source. The secondary light source is associated with a shadow bar that projects a shadow onto a target to be measured in a way that its video image changes position or size in proportion to the distance of the image sensing head of the borescope from the target. Calibration and measurement circuitry are provided to determine the size of the target in relation to the magnification of the projected shadow.

Claims

1. A fluorescent type borescope having an elongated insertion tube that has a proximal end, a distal end, a distally disposed optical pickup for viewing remotely located targets, and target measuring means including:

a first light source that emits light causing an illuminated indication to fluoresce;

a second light source that emits visible light;

auxiliary image creating means operatively associated with said second light source, and being disposed to cause an image created to change at least one characteristic in proportion to the distance between an indication to be measured and the distal end of said insertion tube;

measuring means for determining the change in characteristic of said created image, so that the true physical size of the indication to be measured can be determined;

a first fiber optic bundle extending from said proximal end to said distal end of said insertion tube and being connected to said first light source; and

a second fiber optic bundle extending from the proximal end to the distal end of said insertion tube, having an optical axis, and being connected to said second light source, said first and second fiber optic bundles terminating in spaced apart relationship at the distal end of the insertion tube, whereby a target that may include an indication can be viewed.

2. The borescope of claim 1, wherein said first light source emits ultraviolet light.

3. The borescope of claim 1, wherein said image creating means comprises a shadow bar that is disposed in a path of light being emitted by said second light source, whereby a shadow line is created on the indication being viewed and on the image thereof.

4. The borescope of claim 1, further including bandpass filter means for removing wave components that may interfere with visualization of fluorescence.

5. The borescope of claim 1, wherein said image creating means comprises a shadow bar positioned closely adjacent the termination of said second fiber optic bundle and offset from the optical axis of said second fiber optic bundle so that a shadow line is created on the indication being viewed and on the image thereof.

6. The borescope of claim 1, wherein said measurement means comprises a video display, circuit means for counting pixels in said video display from one edge thereof to an image displayed thereon, and means for determining said parameter of said contrasting shadow.

7. The borescope of claim 6, further including cursors for locating a starting pixel and an ending pixel so that pixels are counted therebetween.

8. A method of quantitative fluorescence penetrant borescopy, comprising the steps of:

illuminating a surface with a first light source that is projected through a borescope through a first fiber optic bundle, said first light source being capable of exciting fluorescence on indications that may be on said surface;

illuminating the surface with a second light source that is projected through the borescope through a second fiber optic bundle that terminates within said borescope in spaced apart relationship to said first fiber optic bundle, said second light source being operatively associated with an auxiliary image creating means, whereby said second light source and said auxiliary image creating means cast a contrasting shadow on the surface that can be viewed in conjunction with said fluorescing indications;

viewing an image of the surface through said borescope; and

measuring a fluorescent indication in accordance with a parameter of the contrasting shadow, wherein said parameter varies with the distance between said auxiliary image creating means and the surface.

9. A method of quantitative fluorescence penetrant borescopy, comprising the steps of:

applying a penetrant to a surface to be examined;

removing excess penetrant;

treating said target with a developer that has a blotting action, whereby penetrant that is retained within discontinuities in the surface are drawn onto the surface;

illuminating the surface with a first light source that is projected through a borescope through a first fiber optic bundle, whereby the penetrant fluoresces;

viewing an image of the surface through said borescope;

identifying fluorescing indications on the surface;

illuminating the surface with a second light source that is projected through the borescope through a second fiber optic bundle that terminates within said borescope in spaced apart relationship to said first fiber optic bundle, said second light source being operatively associated with an auxiliary image creating means, whereby said second light source and said auxiliary image creating means cast a contrasting shadow on the surface that can be viewed in conjunction with said fluorescing indications;

measuring an indication in accordance with a parameter of the contrasting shadow, wherein said parameter varies with the distance between said auxiliary image creating means and the surface.