worked especially closely with Louis Streifeneder, a talented instrument maker from Cameron's firm, who later formed his own company (the Eder Instrument Company) for producing high-quality laparoscopes. During World War II, with German instruments no longer available, Cameron's company introduced the Cameron Omniangle Gastroscope, a modification of the Wolf-Schindler gastroscope, which became a widely used standard instrument in the United States.

It seems clear that, both in Germany and the United States, Schindler was responsible for numerous initiatives in the improved design of the gastroscope, in addition to his pioneering role in introducing it as a tool for extracting information from the patient's gastrointestinal (GI) tract. But the difficulties and limitations in gastroscopy before the advent of fiber optics are hard to exaggerate. It remained an unusual diagnostic procedure. At best, it afforded the examiner fleeting and partial visual impressions of only portions of the stomach as the gastroscopist attempted to manipulate a semiflexible instrument, with an incandescent light bulb at its distal tip, inside the gut of a (presumably) very uncomfortable and apprehensive patient.

The innovation that was responsible for the transformation in endoscopy that began in the 1950s was the emergence of fiber optics. In principle, fiber optics allowed the design of flexible endoscopes, which offered the technical possibility of providing visual inspection of internal organs that were not readily accessible with rigid instruments or that were accessible to only a limited degree with the use of Schindler-type semiflexible endoscopes, for example, the duodenal bulb. The earliest applications of this new capability were on the GI tract, where flexibility was essential. But, as we will see, flexible endoscopy later had applications elsewhere where flexibility was also a critical feature.

The Fiber-Optic Era

Scientific research on the properties of light that are relevant to fiber-optic endoscopy has a long history. Fiber optics make it possible to transmit both light and images along a curved path through the use of bundles of long thin fibers of optical glass. The basic science underlying light transmission had been first expounded by the great Dutch scientist Christiaan Huygens in the seventeenth century. His formulation of the wave theory of light provided an explanation of refraction (bending) and reflection (Salmon, 1974). In 1870, at the Royal Society, John Tyndall demonstrated experimentally how light could be conducted along a curved path, the curved path in this case being a stream of water. Further experimentation was conducted in the 1920s and 1930s, and a patent on a technique for transmitting light through flexible quartz or glass fiber bundles had been taken out by Logie Baird in England in 1928. But these experiments led to no immediate useful applications.

Fiber-optic endoscopy had its origins in the early 1950s, when research was begun on the possibility of transmitting images along an aligned bundle of flexible

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