Instrumentation

Endoscopy can be described as looking inside an object, person, or an animal with a tool designed to provide visualization of an internal target object or body cavity. Endoscopy is also utilized to explore enclosed spaces hidden from direct visualization. Although we usually relate the use of an endoscope to the medical profession, endoscopy has been widely applied to the industrial arena as well. Early endoscopes were essentially straight tubes of varied lengths and diameters (Figure 4.1). A light source was secured to the insertion end, and visualization was accomplished by looking through the tube. In the early 1970s, fiberoptic technology had advanced to the point where fiber-optic bundles could be tightly bound in an insertion tube encased in flexible material. This gave the endoscope flexibility

Figure 4.1 Author using a straight endoscope to examine the internal features of a plastinated heart at the University of Maryland School of Medicine. Note the endoscopic image of the chordae tendineae seen on the monitor.
Figure 4.2 Flexible fiber-optic endoscopes. shown here are an industrial videoscope (A) and a standard medical bronchoscope (B).

while still providing a lighted viewing area and enhanced visualization through a lens located at the distal tip of the instrument (Figure 4.2). Maneuverability is provided by fine-wire remote control of the tip of the scope, giving the operator the ability to navigate the endoscope within body cavities or organs.

Medical endoscopes were, and continue to be, developed and configured for diameter and length related to the medical need and target organ anatomy. Industrial endoscopes were developed related to their specific application requirements as well. In order to provide documentation of the endoscopic field of view, a 35 mm still camera was attached to the eyepiece of the endoscope and internal parts of a human or an object could then be photographed (Figure 4.3). Soon, small video cameras attached to the eyepiece of the endoscope were added, enhancing the way endoscopic data could be collected. It was not until the 1990s that true videoendoscopes (VEs), or videoscopes, were developed. A VE is different from standard endoscopes in that the video camera itself has been miniaturized and positioned at the distal end or tip of the flexible instrument (Figure 4.4). This allowed for greater video resolution, and the data collected therefore had greater interpretability. Current VEs can now collect and record images in high-definition formats using compact flash cards or digital video cassettes. Endoscopes can use various light sources, including "cold" light sources, which can be quite compact, making the instrument extremely portable. The only other necessary instrumentation required for the VE is a camera control unit, which controls the exposure conditions of the video signal. The camera control unit is also compact and easily portable.

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