DIY fiber optic snoot

Wurkkos

Glübzork

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Aug 23, 2015
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Hi,

I am buiding accessories for a UW strobe. I have everything that's needed : a 3D model I designed, a 3D printer, unused Loclines I had laying around for years in the workshop, and fiber optic.
The fiber optic is multicore, 5mm diameter or so, and made of thousands of individual glass fibers. Easy to cut but nasty (mask required because of the debris).
I slavaged this extremely flexible fiber from an old but high quality laboratory lighting (the lightbox had a 150W halogen bulb). It's 1.5 meter, and I want to make two 0.50 meter fiber optic snoots

My problem is : how to seal the ends of the fiber optics ? The individual fibers are really thin (0.01mm or so, much thinner than a hair), the sealant has to be as fluid as possible so it can go everywhere between the fibers (10-20mm would be enough) ; next, I will polish the ends (emery + diamond). Rest of the fibers will be held together with heatshrink.

I've been thinking of using cyanoacrylate, but they tend to cure too quickly, and could cause some issues :

Wikipedia says : "Applying cyanoacrylate to some natural materials such as cotton (jeans, cotton swabs, cotton balls, and certain yarns or fabrics), or leather or wool results in a powerful, rapid, exothermic reaction. This reaction also occurs with fiberglass and carbon fiber. The heat released may cause serious burns[33] or release irritating white smoke. Material Safety Data Sheets for cyanoacrylate instruct users not to wear cotton (jeans) or wool clothing, especially cotton gloves, when applying or handling cyanoacrylates."

(no explanations, but I suspect it has something to do with the surface/adsorption : thousands of cylindric fibers represent a huge surface !)

What sealant could I use ?

Some thoughts ?
 

lucca brassi

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Kocevje , Slovenia, Europe
Some kind of epoxy transparent resin which is also waterproof for instance:

https://www.epodex.com/en/epoxy-resin/
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First you have to fit these fibres in some stainless steel (nickel brass ) form together or better smomething with screw on outside housing for later easy fix.

Maybe you use metal housing for classic led 5mm like ''5mm led metal holder''

https://www.alibaba.com/product-detail/MLH-5-3-metal-flat-type_60276286525.html

https://www.google.com/search?q=5mm...WMK3cKHQi8AeQQ_AUoAXoECAEQAw&biw=1280&bih=657

or even ''quick dissconect fitings '' for air like https://www.dwyer-inst.com/Product/Miscellaneous/Accessories/PneumaticFittings/SeriesA-3000

But you have to cure it in vacuum to get it between fibres and get out air bubles which weak fibre sheaf.
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I can imagine your optics fibres , I have them on Olympus microscope something like

https://www.olympus-lifescience.com/en/microscope-resource/primer/anatomy/sources/
 
Last edited:

Glübzork

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Aug 23, 2015
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Sorry for the late answer, I forgot to activate notifications...

I finally changed my mind because I really hate this fiber glass. I ordered 100 meters of PMMA 0.75mm fiber optic (it's cheap : 15€ on Amazon), and I was planning to seal the ends in small bits of aluminium or stainless tubing, with epoxy, exactly as you suggested ! It will probably be much easier than 0.01mm fiberglass. I simulated a 5 mm fiber made of 0.75mm strands : 1 + 6 + 12 + 18 = 37 strands, approximating a circular section with concentic hexagons. Searching about PMMA fiber optics and UW snoots, I found an example on Instructables : someone using 1.5mm fibers. Seems to be easy. Funny fact : for the same strobe : Inon D2000. I am designing and printing something that looks a bit like this (in the CAD software ATM) : https://www.backscatter.com/ReefNet-Snoot-Mount-Base-Micro-Fiber-Optic-Arm-Inon-Z240-D2000 ; there will be two fiber optics, as the D2000 has two strobes. As you can see on this page, everything is 3D printed except the loclines of course. But it will not cost 300 USD ! At most 50€ including the iterations.

Fiber should be at home tomorrow.

I have a vacuum pump and a large vacuum chamber salvaged from an autoclave, so I can do what you suggested.

candlepowerforums does not host pictures :( ; so I am unable to show the first prototype for the conical snoot (printed with PETG), and the 3D model of the 2nd iteration intended for the fiber optics.

[EDIT] attempting with GitHub : I can't link the images, but images are on this repo : https://github.com/yet-another-average-joe/snoot

I have another question maybe you could answer : the DSLR enclosure has a weak vacuum pump. Is it safe to use a powerfull one that pulls 0.1 bar or so for ultimate testing ? (the photographer is my daughter, she would kill me if I ruin her gear, and she goes abroad for 4 months of diving). I see no reason it would be dangerous, it would just simulate 30 feet... But I don't know if the embeded pressure probes do like very low pressures...
 
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Glübzork

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I answer to myself about high vacuum pumps and DSLR enclosures, just in case someone reads this thread.

Do NOT use a high vacuum pump. The valve is a very precise and expensive silicone component, and chances are high vacuum will destroy it. It happened to someone I know (a professional), using the pump that comes with the enclosure... After we took a look at this tiny valve made this obvious.
 
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