Editing Endoscope (section)

=== Rod-lens endoscopes ===
There were physical limits to the image quality of a fibroscope. A bundle of 50,000 fibers would only give a 50,000-pixel image, and continued flexing from use breaks fibers and progressively loses pixels. Eventually, so many are lost that the whole bundle must be replaced at a considerable expense)
. [[Harold Hopkins (physicist)|Harold Hopkins]] realised that any further optical improvement would require a different approach. Previous rigid endoscopes suffered from low light transmittance and poor image quality. The surgical requirement of passing surgical tools as well as the illumination system within the endoscope's tube which itself is limited in dimensions by the human body left very little room for the imaging optics.{{citation needed|date=July 2022}} The tiny lenses of a conventional system required supporting rings that would obscure the bulk of the lens' area. They were also hard to manufacture and assemble and optically nearly useless.{{citation needed|date=July 2022}}

The elegant solution that Hopkins invented was to fill the air-spaces between the 'little lenses' with rods of glass. These rods fitted exactly the endoscope's tube making them self-aligning and requiring of no other support.{{citation needed|date=July 2022}} They were much easier to handle and utilised the maximum possible diameter available.

With the appropriate curvature and coatings to the rod ends and optimal choices of glass-types, all calculated and specified by Hopkins, the image quality was transformed even with tubes of only 1mm in diameter. With a high quality 'telescope' of such small diameter the tools and illumination system could be comfortably housed within an outer tube. Once again, it was Karl Storz who produced the first of these new endoscopes as part of a long and productive partnership between the two men.<ref>{{cite web |title=History |url=http://www.haroldhopkins.org/history.html |work=Harold Hopkins Society}}</ref>

Whilst there are regions of the body that will always require flexible endoscopes (principally the gastrointestinal tract), the rigid rod-lens endoscopes have such exceptional performance that they are still the preferred instrument and have enabled modern key-hole surgery.{{citation needed|date=July 2022}} (Harold Hopkins was recognized and honoured for his advancement of medical-optic by the medical community worldwide. It formed a major part of the citation when he was awarded the Rumford Medal by the Royal Society in 1984.)