1. Hard Endoscopy stage (1806--1932): The hard endoscope stage was initiated by the German Philipp Bozzini. It consists of a vase-shaped light source, a candle and a series of lenses, mainly for bladder and urethra examination. In 1895, the rigid endoscope developed by Rosenhein was concentrically arranged by three tubes. In 1911, Elsner improved the Rosenhein-type gastroscope, but the lens was dirty and could not be observed as a major defect. However, the Elsner-style gastroscope was still in the position of commander before 1932.
2. Semi-flexible Endoscopy Camera stage (1932-1957): Schindler co-developed a gastroscope from excellent instrumental operator Georg Wolf in 1928 and finally succeeded in 1932, named Wolf-Schinder type gastroscope. After that, many people have carried out transformations to make them more functional and practical. 3, optical fiber endoscopy stage (1957 to present): In 1954, the British Hopkins and Kapany invented the optical fiber technology. In 1957, Hirschowitz and his assistant presented the self-developed fiberoptic endoscope at the American Society of Endoscopy. In the 1960s, Olympas in Japan used an external cold light source to increase the brightness and further expand the field of view. In the past 10 years, with the continuous improvement of the accessory device, the fiber endoscope can be used not only for diagnosis but also for surgical treatment.
4. The era of electronic endoscopy (after 1983): In 1983, Welch Allyn developed an electronic camera endoscope. The front end of the mirror is equipped with a high-sensitivity miniature camera that transmits the recorded image to the television information processing system by electrical signal, and then converts the signal into an image that can be seen on the television camera.
