84. Fiber-optic Endoscopes, Videoendoscopes, Construction and clinical importance

yaboiemil's version from 2016-02-14 22:17


1. A fiber-optic cable exploits total internal reflection in order to transport information through it.
2. Total internal reflection occurs when a propagating wave strikes a medium boundary at an
angle larger than a particular critical angle and the refractive index is lower on the other side of
the boundary, rendering the wave unable pass through and is entirely reflected.
3. A fiber-optical cable will have a cross section that looks like this:



Where the inner ring (n1) will have a higher index of refraction that the outer ring (n2), enabling
total internal refraction.


4. In an endoscope, there are usually 2 optical fibres - one for LIGHT transmission and one for
IMAGE transmission.
5. The endoscope will also have other components, such as air or water channels to permit the taking
of samples
6. There is a viewing objective at the distal end
7. There is a viewing ocular at the proximal end
8. There is mechanical control at the proximal end
9. The light source is Halogen or Xenon
10. With a Videoendoscope, the viewing objective is replaced with a camera. The image can be examined
on a TV.

Remember dis u ho:


Question Answer
Total Internal ReflectionAngle of incidence > Critical Angle & Refractive Index Lower on other side.
Proximal End of EndoscopeViewing Ocular and Mechanical Control
Distal End of EndoscopeViewing Objective
Light source of EndoscopeHalogen / Xenon