Method and apparatus for viewing and measuring damage in an inaccessible area

• US 4,078,864 A
• Filed: 07/08/1976
• Issued: 03/14/1978
• Est. Priority Date: 07/08/1976
• Status: Expired due to Term

• Current Assignee: United Technologies Corporation (Rtx Corporation)
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Howell, Robert E.
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Rosenberger, R. A.
• Application Number:
  US05/703,402
• Time in Patent Office: 614 Days
• Field of Search: 356/3, 356/16, 356/21, 356/127, 356/171, 356/241, 350/10
• US Class Current: 356/397
• CPC Class Codes: G01B 9/04 Measuring microscopes
• CPC Class Codes: G02B 23/2476 Non-optical details, e.g. housings, mountings, supports

Abstract

An optical viewing tube having an eyepiece at one end and a viewing prism at an optical tip at the other end is provided with an optical system therebetween which will provide a focus for an object being viewed. A distance indicating disk or device on said tube is movable by a focusing mechanism to indicate the distance from the optical tip of the viewing tube to a viewed object. A camera is provided to be attached to the viewing tube to take a picture of the viewed object, and an eyepiece with a properly marked reticle is placed on the photograph taken, to indicate proper distances between spaced points on the object as seen in the photographs. The viewing tube is calibrated along its length so that tube penetration can be accurately known and a retention adapter is used with the tube to rigidly fix it in place. The retention adapter includes a compass rose which indicates the position of the viewing prism. An alignment adapter can also be used to insure proper alignment of the tube with a housing to which it is being connected. A modification of the tube has a focus numeral indicating device and an eyepiece containing a measuring device, with this modification the proper distance between spaced points on an object is obtained by obtaining a focus numeral from the indicating device and after obtaining units of distance between the spaced points from a measuring device, a divisional value for a specific reference numeral indicating unit size is multiplied by the number of units obtained from the measuring device to get the actual distance.

Claims

1. An apparatus for viewing and measuring an object through a small opening within a housing which is generally inaccessible, including an optical viewing tube of fixed length, viewing means having an eyepiece at one end of said optical viewing tube, optical lens at the other objective end of said optical viewing tube for producing an image, a movable optical system located within said tube of fixed length between said viewing means and objective end for transmitting said image for viewing at said eyepiece, means for moving said optical system for focusing the image at said eyepiece, means for viewing divisional units through said viewing means, numeral indicating means connected to said optical viewing tube, said numeral indicating means being movable with said focusing means, said numeral indicating means indicating a number which is related to an actual length represented by a divisional unit of said eyepiece at the distance of the object from the objective end as viewed when the object is in focus, a retention tube positioned around said viewing tube of fixed length, said optical viewing tube of fixed length having a sliding and rotating movement within said retention tube, means for fixing said retention tube to a housing around a small opening, means for locking said optical viewing tube, in a fixed position within said retention tube, said viewing means having a micrometer controlled cursor to count the number of divisional units covered by the cursor as it moves between two predetermined points on said focused object wherein the product of said actual length represented by a divisional unit and said counted number of divisional units provides the actual length between the two predetermined points.

2. A combination as set forth in claim 1 wherein said viewing tube is calibrated along its length so that tube penetration within a housing can be accurately known.

3. A combination as set forth in claim 1 wherein said means for fixing said retention tube being located at one end of said tube, said retention tube includes an annular flange on its opposite end, said annular flange containing a compass rose, said viewing tube having a longitudinal line extending along its length which, if extended, would intersect the center of the optical lens at the objective end wherein said line indicates with said compass rose the angular position of the optical lens.

4. A method for measuring between two predetermined points on an object within a housing with an optical viewing tube having an eyepiece at one end and an optical lens at its objective end which comprises the steps of:

(1) axially moving and rotating the objective end of said viewing tube in a housing to locate a desired viewing area on an object;

(2) fixing said optical viewing tube with relation to the area of an object being viewed at a particular distance;

(3) focusing the area of the object in the optical viewing tube at that particular distance;

(4) optically placing a scale of divisional units over said object;

(5) obtaining a number indicating the actual length represented by a divisional unit at the particular distance of the area of the object from the objective end of the optical viewing tube;

(6) counting the number of divisional units between two predetermined points on the object wherein a product of the actual length represented by a divisional unit and said counted number of divisional units provides the actual length between the two predetermined points on said object.

5. A method as set forth in claim 4 wherein step (5) the number indicating the actual length represented by a divisional unit at the particular distance is obtained by:

(a) placing an object having a larger known length at said particular distance from said optical lens;

(b) placing the object in focus;

(c) moving a micrometer controlled cursor capable of counting said maller divisional units across the object having a larger known length while reading the number of divisional units wherein the number of divisional units is then divided into the larger known length to obtain the actual length of a smaller divisional unit at said particular distance.

6. A method for viewing and measuring the actual distance between two points on an object in an aircraft engine with an optical viewing tube having an optical lens at its objective end which comprises the steps of:

(1) forming an opening in the side of the engine;

(2) mounting said optical viewing tube for axially sliding and rotative movement in said opening in said engine;

(3) moving said optical viewing tube to locate a desired viewing area on an object having the distance between two points to be measured;

(4) fixing said optical viewing tube with relation to the area being viewed at a particular distance;

(5) focusing the area of the object in the optical viewing tube at that particular distance;

(6) optically placing a scale of divisional units over said object;

(7) obtaining the actual length represented by a divisional unit at that particular distance of the area of the object from the objective end of the optical viewing tube;

(8) counting the number of divisional units between the two points on the object where a product of said counted number of divisional units and the actual length represented by a divisional unit provides the actual length between the two points.