Two Physics Questions On Endoscopes.? HELP!?

Question

Just two questions I am stuck on and can't find anywhere:

1. How does light travel through an endoscope to allow a doctor to see the patient's stomach?

2. The light that travels through an endoscope has a source which also emits heat. Explain why the patient's insides are not harmed by any of this heat.

Pleaseeeeee Help ?!?

Answer 1

1. the light undergoes repeated and successive total internal reflection off the inside of the optical glass fibres.

2. the source of the light (lamp) does not go inside the patient - only the optic fibres.

Answer 2

1. The light is refracted off of the sides of Optial fibres



2. The source of the heat/light does not actually go inside the patient , only down the optical fibres



Hope this helps :)

Answer 3

Here is a serarch result listing lots of endoscope info including manufacturers sites and guides. Notice the search term.

http://www.google.com/search?q=light+guide+endoscope&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-GB:official&client=firefox-a . . . . .



1. Light travels thtough an endoscope along a light guide which is normally an optical fibre bundle encased in an insulating sheaf. The optical fibres are normally very fine glass fibres which can transmit the light both directly and by total internal reflection from the walls of the fibres.

http://physix_jun.tripod.com/fibres_4.htm . . . . .



2. Not all light sources for endoscopes emit enough heat to be a problem. Cold light sources are very common in endoscopy, microscopy, profressional photographic enlargers, and in many other applications.

http://www.industrial-needs.com/technical-data/endoscope-PCE-CLE-150.htm . . . .

http://endoscopy4you.com/html/endoscopy_light_source_quides.html

Where sifficient heat is emitted by the light source to present a problem a heat filter can be inserted into the beam. A heat filter is normally simply a plate of heat absorbing glass. They are used in many applications, including photographic slide and film projectors to avoid the intense heat from powerful projrctor bulbs melting the film base and in endoscopy and microscopy.

The distal end of endoscope light guides is also normally sealed with a heat absorbing glass cover.

Larger sizes of endoscope tubes have a water supply which can be used for temperature control.



A wedge of glass can also be used, called a Herschel Wedge, after F.W.Herschel who was the first to show the presence of infra-red light (heat) in a spectrum of the sun which he did by simply using thermometers

The Herschel Wedge refects only 5% of the heat and light rays hitting it and transmits 90% straight through. The other 5% is absorbed.

http://www.hkastroforum.net/files/herschel_wedge_diagram_101.jpg . . . . .

http://www.practicalphysics.org/go/Resources_16.html . . . .

http://coolcosmos.ipac.caltech.edu/cosmic_classroom/classroom_activities/herschel_experiment2.html . . . . .



Both plane and parabolic mirrors have been used by some manufacturers to separate the heat and light in a beam so that only light is transmitted to the part to be observed.

There are references in the search list, including manufactures diagrams and specification sheets.

Answer 4

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