Transmitting Images through a Coherent Fiber Bundle

[petr1243]

A coherent fiber bundle is very useful in transmitting images. Let's say we have a gaussian beam from a laser as our source. Now the acceptance angle(2*alpha) is determined from the location of the beam waist, right? The light ray will then go down the fiber core with the use of a converging lens. So, for us to successfully transmit an image(e.g. the letter "A") from end to end of the fiber, then the incidence angle outside of the fiber must be greater than the acceptance, and then the incident angle inside the core must be greater than the critical angle. Is this correct? What other key components do I need, in order to observe a transmitted image with minimal dispersion(e.g. single mode fiber)? Thanks

 

[Cthugha]

What other key components do I need, in order to observe a transmitted image with minimal dispersion(e.g. single mode fiber)? Thanks

Not really a component, but to keep the dispersion at a minimum, you will need to use light with a matching wavelength. In this case it won't be in the visible range, but somewhere in the IR. The zero-dispersion-wavelength for usual fibers used for applications in telecommunication is somewhere around 1300 nm. However, there are also some single mode fibers, where this wavelength is shifted to about 1550 nm.

 

[petr1243]

I haven't tried the experiment yet, but I'm geared towards starting it next week. Just need to get all the facts straight, before stepping into the lab. 1310, and 1550 nm sounds right. I've been reading many papers that have been using color coding, by using numerous amounts of dispersive prisms or gratings and lens'.(e.g. parallel image transmission by a single optical fiber by Friesem and Levy). I don't see why these complications are necessary?There must be a simpler way to produce an image through a coherent fiber bundle. He used a non-scanning method with the multimode fiber. It makes sense to work with the multi-mode fiber, then dive into the single mode fiber, so that's what I'll probably do. Also, I believe that it is possible to get no image from single mode fiber, since only one ray in a TEM mode is present, due to a possibility of leakage of that ray when the incident angle is less than the critical angle. What do you think? Thanks again.


Pete