1. Field of Endeavor
The present invention relates to measuring and more particularly to optically measuring interior cavities.
2. State of Technology
U.S. Pat. No. 5,432,543 issued Jul. 11, 1995 to Jun Hasegawa et al for endoscopic image processing device for estimating three-dimensional shape of object based on detection of same point on a plurality of different images provides the following state of technology information: “When the relative arrangement of the imaging means disposed with overlap in a visual field is known, various methods are known which estimate the shape of an object from the images formed, i.e., for estimating the shape from stereo-images. In recent years, some methods have also been proposed for determining a three-dimensional structure from information about the movement of an object. The methods employ the technique of estimating the relative movement of imaging means from a plurality of images.”
U.S. Pat. No. 6,009,189 issued Dec. 28, 1999 to David F. Schaack for apparatus and method for making accurate three-dimensional size measurements of inaccessible objects provides the following state of technology information: “In the past several decades, the use of optical endoscopes has become common for the visual inspection of inaccessible objects, such as the internal organs of the human body or the internal parts of machinery. These visual inspections are performed in order to assess the need for surgery or equipment tear down and repair; thus the results of the inspections are accorded a great deal of importance.”
U.S. Pat. No. 6,459,481 issued Oct. 1, 2002 to David F. Schaack for simple system for endoscopic non-contact three-dimensional measurement provides the following state of technology information: “Making accurate dimensional measurements of objects viewed through endoscopes is important to aerospace as well as other industries in which expensive equipment must undergo periodic internal inspections to maintain safe operation. Such measurements also have medical applications, where the internal condition of a patient is evaluated prior to or during surgery by viewing through an endoscope. The fundamental problems in making an accurate measurement through an endoscope are that the magnification of the image varies rapidly with the range of the object, and that objects of interest (defects) lie on surfaces which are curved in three dimensions; thus the magnification varies from one point on the object to another. What is needed is a fully three-dimensional measurement, that is, one which determines the depth, as well as the height and width, of an object. Endoscopes are long and narrow optical systems, typically circular in cross-section, which can be inserted through a small opening in an enclosure to give a view of the interior. They almost always include a source of illumination which is conducted along the interior of the scope from the outside (proximal) end to the inside (distal) end, so that the interior of the chamber can be viewed even if it contains no illumination. Endoscopes are divided into two basic types: these are the rigid “borescopes” and the flexible “fiberscopes” or “videoscopes.”