Magic fluorescence in night dives with HiTecLEDs

horstartur

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Hi all divers,

I just returned from Diving in ElQuseir, Egypt. There I tested a HiTec Fluorescence lamp in Night-Dives. I have constructed the lamp with parts of Sandwhich Shoppe> McR-20 reflectors and stepdown coverters (Shark Buck 3A). The emittors are 4 blue OSRAM SMT modules (4 LEDS per module each). A desciption can be found on the PR-Page of OSRAM under Success Stories http://www.osram-os.com/osram_os/EN...ies/OSTAR-LED-in-HiTec-fluorescence-lamps.jsp
On my home page
http://www.uni-due.de/zoophysiologie/ you will find an explanation what the technique is good for and also a 12 minutes movie (stream).
For Fun-dives the technique it is a new underwater world. It is the magical transformation of drab-colored to brightly glowing color-saturated specimens that makes fluorescence so magical.
The diver gets the impression that he (she) dives in underwater flower garden. This is indeed the case since my lamp illuminates larger areas in contrast to commercial available lamps with one LED only (16 in our lamp, 16fold brighter).
Also on YouTube you will find the movie about this technique. From 6 hours night dive I have selected the highlights in this 10 minute version. http://www.youtube.com/results?search_query=night+dives+fluorescence+&search_type=&aq=f
 

horstartur

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Thank you. It would be much more informative if I could have included the comparison between dead coral areas and the living ones. However, fortunately in this bay near ElQuseir, Egypt (they name it ecological intact bay) the damage of the coral reef is not visible now. Other parts in Egypt and other areas in the world are not so lucky. May be that somebody of responsible people will be interested in this scanning technique in large scale.
Regards

Horst
 

Linger

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Thank you. It would be much more informative if I could have included the comparison between dead coral areas and the living ones.
Indeed. Heart wrenching too, perhaps.


**re: building hand light
Is there anything particular about: Wavelength: 470 nm blue?
Efficiency is low, 9 lm/W.
Will a range of blues be effective? rough approximation of lumen output for your lamp? There's a whole range of blues that are available to me, but not much coral reef.
 
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gcbryan

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Wouldn't this light be effective in bring out bioluminescence in most waters?

Indeed. Heart wrenching too, perhaps.


**re: building hand light
Is there anything particular about: Wavelength: 470 nm blue?
Efficiency is low, 9 lm/W.
Will a range of blues be effective? rough approximation of lumen output for your lamp? There's a whole range of blues that are available to me, but not much coral reef.
 

horstartur

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Hi gcbryan,

there is a lot of backbround information needed to explain everything. You make me think about additional informations on my home page. Indeed I use blue light with 465 nm (exciting) and a blocking filter on the diving mask and the camera of about 500 nm. UV light would be in the range around 260 nm. Therefore our blue light should not be harmful for animals and plants (of course also not for corals).
I have also to explain the difference between fluorescence and bioluminescence. The fluorescence effect in corals is correlated with special pigments (GFP >green fluorescent protein-like proteins in the coral polyps). They adsorbed light (even below 5 meters) provides their symbionts (zooxanthellae) with the necessary light energy for photosynthesis.
Biolouminescence (cold light) on the other hand originates from a biochemical reaction with a special substance > Luciferin will be oxidized by Luziferin, which results in lightening > see lightening bugs or deep sea angler fishes > in the later bacteria with a similar metabolic activity are the reason for the light. Resumé: my lamp will not cause bioluminescence.
 

Linger

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Is the blocking filter on the face mask to then remove much of the blue light that you're putting out? So that only the flourescence (and ambient light) come through? < - If that is the case this will not be great for 'recreational use' dive light as if you need a filter it suggests effect is not that strong.

(I understand not wanting to use UV light. When I first saw many spectacular underwater pictures I thought it would be interesting to replicate, UV emitters so very easy to get, but my conscience got the better of me and I decided possibly harmful UV light was not an option for me.)
 

Norm

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Working fine here Bill, it's in Quicktime. Excellent Video :thumbsup:

Norm
 
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DIWdiver

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Efficiency is low, 9 lm/W.
Will a range of blues be effective? rough approximation of lumen output for your lamp? There's a whole range of blues that are available to me, but not much coral reef.

The efficiency (mW/W) isn't low. The efficacy (lm/W) is low. They're not the same thing. Lumens are the ability to make things visible to the human eye. Since the eye has poor sensitivity in the blue part of the spectrum, a given optical power, say 100 mW, will be a lower number of lumens in blue than the same optical power in a color like green. In the other direction, in ultraviolet, any amount of optical power still generates zero lumens.

If you doubt this, consider that the 120 lm/W white LEDs are actually blue LEDs with phosphor on them to turn some of the blue light into other colors, turning some into waste heat in the process.
 

bvanant

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The efficiency (mW/W) isn't low. The efficacy (lm/W) is low. They're not the same thing. Lumens are the ability to make things visible to the human eye. Since the eye has poor sensitivity in the blue part of the spectrum, a given optical power, say 100 mW, will be a lower number of lumens in blue than the same optical power in a color like green. In the other direction, in ultraviolet, any amount of optical power still generates zero lumens.

If you doubt this, consider that the 120 lm/W white LEDs are actually blue LEDs with phosphor on them to turn some of the blue light into other colors, turning some into waste heat in the process.
The luminosity function (which has a few different definitions) is why it is a royal PITA to try to calculate lumens from any other power/intensity measurements.

Bill
 
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