Beam delivery with fibers

[Geola]

Guys, what fibers you are using in your setups? How long they are and what laser power they can withstand?
I need this info for latest edition of "Practical holography". If you have some drawings of your fiber setups, please, post them here or send me to stas@geola.com.

[John Klayer]

I've been in some private communication with Stas, but I thought the rest of you may be interested. A few days ago I stumbled upon a "Toslink" fiber cable at a local hardware store (!). My initial tests look promising, the output is about the same or better than the obsolete HP fiber I was using. The mini- Toslink uses standard 3.5 mm electronics connectors and is available in about any length.

[Jem]

This may prove to be an interesting read for anyone who can gain access...

https://www.academia.edu/7253869/Optica ... vironments

[Dinesh]

The single mode fibre has an NA of 0.12, which means a beam divergence of about 12 deg. and the multi-mode fibre has an NA of 0.2 which means a beam divergence of about 20 deg. These angles are further reduced due to the Gaussian nature of the beam profile. The former is too small for real display holography and the latter is only just adequate. In the case of the multi-mode fibre, the path lengths are uncertain, therefore the source needs a fairly long coherence length.

[John Klayer]

In the case of the multi-mode fibre, the path lengths are uncertain, therefore the source needs a fairly long coherence length.

Right, that's why it works with the C315M which has a very long coherence length.

[John Klayer]

This may prove to be an interesting read for anyone who can gain access...

https://www.academia.edu/7253869/Optica ... vironments

I read the paper several times. If the hologram of the chess pieces was made with the 12 strand 8.3 um multi core single mode fiber delivering the object beam to the holo plate could the shown parallax views be possible? I can't see where more than one view would be possible - the view seen by the small receiving end of the multi core fiber.

[John Klayer]

I ordered some Toslink fibers and splitters to try out an idea that hit me:
Launch the laser into a fiber through several 50/50 splitters linked one after another till the last output is weak enough to use as a reference through one fiber. Each of the other 1/2, 1/4, 1/8... are routed with other fibers for object illumination. Yeah, I know there is going to be a lot of connector losses. Maybe by this weekend I'll have something slapped together.

[Holomark]

John, Would love to see (or hear about) the results.
I presume you will be using the fibers to illuminate the object an the plate, but not the wavefront from the object as they did in the paper because, as you pointed out, it would be a very limited viewpoint.
I am interested in how much light loss there is using the fiber.
Also interested in the output from the fibers - do you use a lense after the fiber to expand beams?
Why use multiple 50/50 splitters? Why not use an 80/20 to separate object beam from reference then use a 50/50 to split object beam - This would result in fewer splits and thus lower amount of light loss.

[John Klayer]

Holomark asked: "Why use multiple 50/50 splitters? Why not use an 80/20 to separate object beam from reference then use a 50/50 to split object beam - This would result in fewer splits and thus lower amount of light loss."

Because only 50/50 splitters are made for Toslink. I'm just trying to take advantage of the fibers, connectors and splitters that are easily and cheaply available for digital electronics and repurpose them for holography.

[Ed Wesly]

Funny how history repeats itself, or how many people ar reinventing the wheel.

http://edweslystudio.com/Publications/F ... rpaper.pdf