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LarsB

Member Since 17 May 2012
Offline Last Active May 05 2015 09:30 AM
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Posts I've Made

In Topic: Cheaper blue lights for fluo diving

05 May 2015 - 09:21 AM

I think the simplest approach is to use the dichroic filter glued onto the front glass using UV cure adhesive but you still need to get the blue lights into the torch. Not simple at all as Lars points out. There are up conversion phosphors but they are expensive. There are a bunch of blue LED torches on ebay, waterproofing them might be an option.

BVA

 

If the glue is applied only to the rim of the dichroic filter and the front glass, the air pocket caught between filter and front glass will inevitably cause the dichroic filter to shatter under water pressure.

If OTOH the glue is applied to the entire surface of both the dichroic filter and the front glass, the glue may not be fully transparent, e.g. might contain small air bubbles, or might dampen the light output (even without air bubbles), which is not very desirable either.

 

What you can do for example however is to use some piece made of rubber to hold the filter and attach it to the torch, e.g. a rubber collar used in plumbing to connect tubes of different diameters, something like that.

Or make your own mount, e.g. of rubber or plastic.

The idea is that the water should be able to flow relatively freely, in order to avoid captured air bubbles and in order to make cleaning easy after a dive, while at the same time providing some protection to the filter.

The water flow may also be important for cooling.

 

When replacing white LEDs with blue LEDs, check out the specs whether there are compatible types.

Some Cree LEDs for instance have both white and blue variants, such as the XR-E and the XT-E, for example.

Check out http://www.cree.com/.../Products/XLamp

You'll always want "Royal Blue".


In Topic: Cheaper blue lights for fluo diving

04 May 2015 - 08:31 PM

Hi ChrisD82,

first of all, there are no blue equivalents for the white Cree XM-L type of LEDs.

Replacing them with other LEDs may exceed the LED's and/or the torch's specs, which may cause damage to either, or both.

You may not even notice at first, it can be that the LEDs will simpy age much faster than normal and lose brightness rather quickly.

Moreover in many torches access to the LEDs can be difficult (e.g. the torch may be glued shut and/or require special tools to open) and the LEDs may be soldered in place through flow-soldering, which may be difficult to unsolder and even more difficult to resolder, because this is difficult to do at home and because you may not be able to get the parts out of the torch, or there may be others components soldered on such as SMD electronic components which might get damaged in the process.

Finally, replacing the front glass with a dichroic excitation filter is a very bad idea, because the filter's glass substrate is thin and brittle. It is certain to break at a certain depth and to flood your torch, probably ruining it, or at least the batteries and/or the electronics inside.

Often there is no space inside the torch for an additional filter, and having the original front glass coated by the manufacturer is expensive and tricky, some glasses have a protective coating which makes coating them with the filter impossible. And last but not least you have to know exactly which type of filter to apply/order.

Some torches are indeed easier to modify than others, the difficulty is finding them (without spending a fortune).

In Topic: DIY LED and UV dive lights

05 July 2014 - 11:25 AM

Even more great info about underwater fluorescence and fluorescence diving can be found here:

http://www.fluomedia.org/science/
http://www.fluopedia.org/publications/