3
$\begingroup$

Why is the jacket or sheath of fibre optic endoscopes always black? Is it just a convention, or is there a more logical explanation for this?

$\endgroup$
  • 2
    $\begingroup$ This could very well be an inertial design decision. In other words, a design decision that was made early in the original design of the first prototypes, was found to be largely unimportant, and then forgotten by the entire industry because it wasn't worth passing on that design knowledge. So now everyone manufactures them in black because they've always been manufactured in black. That doesn't mean, of course, that it's an optimal design decision, merely that it is believed to be uneconomical to investigate changes. $\endgroup$ – wwarriner Oct 24 '15 at 18:12
3
$\begingroup$

I really have no idea, but I did come up with the following possibilities.

  1. To minimize reflections from the instrument itself. Light reflecting off the endoscope could interfere with the doctor's view.

  2. Because little (if any) body tissue inside the body is black, thus making it easier to distinguish the instrument from body parts.

  3. Because that's the natural color of the plastic including additives. Adding dyes could be undesirable if they leech over time, and since it's not a typical consumer item there's no need to make it colorful and flashy.

  4. To shield the fibers from outside light, thus minimizing interference.

$\endgroup$
  • $\begingroup$ The "natural" color of most polymers are browns and dirty whites. The CHON bonds tend to absorb light strongly in the infrared region of the EM spectrum and not interact strongly with visible light. Occasionally specific polymer bonds will interact with a specific visible band, especially in organometallic complexes, but I can't think of how a polymer would be made to absorb all wavelengths of visible light without additives of some kind. This leads me to believe there must be some other reason, and (2) seems most likely (read: useful) to me. $\endgroup$ – wwarriner Oct 24 '15 at 17:47
  • $\begingroup$ @starrise, I agree, can't think of any plastic that's black naturally. I'm editing the question to correct that. $\endgroup$ – Carlton Oct 24 '15 at 17:54
  • $\begingroup$ I vote for 1 and 4 depending on which caused the early developers some noticeable problems. $\endgroup$ – KalleMP Oct 24 '15 at 18:38
  • $\begingroup$ Some liquid light guides for endoscopes are grey. $\endgroup$ – D Duck Mar 29 at 9:22
0
$\begingroup$

To prevent ambient light from "leaking" into the fiber optic cables. It's mainly a redundancy (extra layer of protection)

$\endgroup$
0
$\begingroup$

Industrial polymers are often black by default because carbon black pigment is added to stabilise them against environmental degradation, especially the effects of UV light. This is certainly the reason why tyres are almost always black.

And black goes with everything :P

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.