Endoscope
Sometimes called the fiberscope, the endoscope is an optical instrument that allows doctors to view the inner workings of the human body without having to perform surgery. The endoscope is a flexible narrow tube containing several bundles of hair-thin glass fibers that are covered with a reflective coating. A highly intense light source, usually a halogen lamp, is used to transmit light along one bundle of fibers toward the target area inside the body. Another bundle of fibers carries an image of the target area back up the tube where it is viewed through an eyepiece.
Endoscopes are primarily used in the health care field, but they may also be used for industrial purposes examining such inaccessible places as the inside of fuel tanks and nuclear reactors. Crude versions of the endoscope were used as early as the nineteenth century and included long, rigid tubes illuminated by candles. In 1854, Manuel Patricio Rodriguez Garcia, a Spanish-born vocal teacher, designed the forerunner of the laryngoscope; it allowed a clear view of the glottis (the vocal cords and the opening between them) and made it possible to see obstructions in the larynx.
The first efforts to develop the kind of glass fibers that would eventually be used in endoscopes were made by the Atomic Energy Authority and by the Rank Organization in Britain. By 1965, a 25-micron (a micron is one-thousandth of a millimeter) fiber had been produced. An American company, Bausch and Lomb, subsequently developed a 15-micron fiber used in their "Flexiscope," which could be used for industrial inspections because it gave off a "cold" light that was safe even in fuel tanks. When the American Cytoscopic Company succeeded in sterilizing glass fibers, the possibilities for medical uses of the endoscope increased greatly.
The modern endoscope can perform an amazing variety of medical procedures. In addition to the fiber optic bundles that transmit light, the endoscopic tube also contains air and water channels for flushing water through or inflating targeted areas. Tiny forceps can be placed at the tip of the endoscope to take specimen samples for laboratory analysis and to perform simple operations such as removing colon polyps or gallstones. Endoscopes can also be used to stop hemorrhaging by delivering laser beams directly to the point of bleeding; the blood coagulates and the bleeding is stopped.
Different types of endoscopes are specially designed to examine specific parts of the body. The angioscope passes through the arteries that carry blood to the heart; the arthroscope is used to explore the interiors of joints; the bronchoscope is used with a special dye and fluorescent light to detect lung malignancies; the gastroscope probes the stomach and upper intestinal tract; and the laparoscope is used for diagnosis and treatment of abdominal conditions.
Endoscopes can be used for a variety of remote sensing applications. They can be connected to spectrometers to perform sophisticated chemical analysis optically. The endfaces of the fibers can be impregnated with molecules that are sensitive to certain compounds, allowing researchers to detect minute concentrations of pollutants and toxins.
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