The mignon lamp illuminated endoscopes until fiber-optics took center stage in the mid-1950s. With this technology, doctors could transmit images by flooding the bladder and other interiors with light traveling along glass-fiber bundles.
British scientist John Tindell had established the principle of internal light reflection inside glass rods in 1872 and German Heinrich Lamm confirmed that optic fibers could transmit body images in 1930. But fiber-optics wouldn't emerge as a practical medical technology until 1954 when British physicist Harold H. Hopkins (with N.S. Kapany) produced the first usable system. It was Dutch optics professor Abraham van Heel who proposed protecting those fibers from "leaking" light by "cladding" or coating them with a transparent sheath. Van Heel's suggestion unlocked the secret of continuous illumination. Both contributions inspired the first fiber-optic gastroscope in February 1957 and a ureteroscope in 1960. Refinements followed, including Hopkins' own rigid