The first endoscopes were made of rigid tubes and were invented more than 100 years ago. Although they gradually improved, they still failed to be widely used. Later, in the 1950s, endoscopes were made from flexible tubes and could thus be easily bent around corners inside the body. In 1965, Harold Hodgkins attached a columnar lens to the endoscope to provide a clearer view, and today's endoscopes usually have two fiberglass tubes through which light enters the body and is viewed by doctors through the other tube or through a video camera, and some endoscopes even have miniature integrated-circuit sensors that feed the observed information to a computer.
Figure: An early endoscope made in 1870. It has a rigid tube instead of a rubber hose.
Some surgeries can be done with an endoscope and a laser. The endoscope's light-guided fiber delivers a laser beam that cauterizes unwanted growths or tumors and seals off bleeding blood vessels.
To put it simply, an endoscope has a number of reflective surfaces that can be mirrored, and information from inside the body can be seen by the doctor through multiple reflections
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