Nichia 365nm UV Light offerings (NEW 5-12-17)

[LarsB]

Re: Nichia 365nm Light offerings

Hi Don!

Hi LarsB,
I have only met a few of the Scripps PhD students and advisers who are studying some of the reef activity over here. The primary focus for them is the competition between algae and coral for reef real estate and contributions of various herbivores in keeping the algae in check. I can count the number of times I have been out on the reef at dark with UV light sources on one hand and still pick my nose.

And doesn't it make you long for more?

I have never taken a biology class and my incredibly poor memory for names would make doing so a waste of time. :duck:

I don't believe a word about your poor memory!

I have picked up some knowledge from discussions and personal observations

So much for your bad memory!

and I am curious as to how and why life forms proceed as they do. That coral is partly animal, plant and mineral is pretty fascinating. Can I assume that the fluorescing takes place in the alga within the coral and a bleached coral would not flouresce the same as it would while hosting the alga?

As far as I know (but I'm not an expert), both the symbiotic algae and the corals themselves contain fluorescing proteins.
It is still a mystery however what the purpose of these is, besides maybe acting as a sunscreen against damaging radiation and providing the symbiotic algae with light they can use for photosynthesis, allowing the corals to dwell deeper and thus giving them an advantage over corals who can't do this.
But research is really just beginning.
An interesting recent find was that apparently the fluorescent proteins can act as electron donors, just as Chlorophyll (the green substance in plants responsible for photosynthesis) does (electron donation is a necessary first step in photosynthesis).
This might shatter the conventional wisdom/definition that plants are the organisms that are capable of photosynthesis and animals are the organisms which are incapable of photosynthesis.

I find it interesting to consider that when viewing some of the life underwater like coral and say squid or jelly fish, you can't be certain that what you see is based on reflected light or emissive light. That statement assumes or includes fluorescence as emissive in nature which may be incorrect.

That simply depends on how you define it, but there clearly *is* a difference between reflected and fluorescent light.
And indeed, sometimes you don't even realize that what you see is actually fluorescence, such as in the following picture:



This image shows an anemone displaying red fluorescence, at a depth (about 18m or 60ft) at which red ambient light is normally absent, due to its absorption through water on its way down.

I would imagine that one way to determine fluorescent light VS reflected light from coral would be by illuminating it with either narrow bands or a fuller spectrum of light that is absent the UV and near UV or even blue bands. For example, if a yellow coral under ambient light changes color or relative intensity drastically when illuminated by a spectral source including its apparent color but no light from the spectrum typically associated with fluorescing.

On a related note, I recall discussions years back here on the forum relating to the most efficient light source for UW illumination. Although monochromatic, it would seem that in "clear" water, an optimal blue LED source might be best at illuminating and contrasting objects at distance. A white target viewed at distance probably tells you the most efficient spectrum in terms of penetration by virtue of what color it appears to be in reflection.

You lost me a bit here, unfortunately I didn't fully understand what you meant.

Cheers,
LarsB

 

[LarsB]

Re: Nichia 365nm Light offerings

LarsB,
I checked with my Scripps friends and they are friends of the two you mentioned.

Hi Don, thanks for letting me know!

Apparently Melissa is now doing post doctorate at Berkeley. They also mentioned that the Jaffe Laboratory might be of interest. You are probably aware of these folks and their "stuff".

Actually I'm not, our contact has been very brief, and I've only found some of their works accidentally by googling around for pages related to underwater fluorescence.

 

[McGizmo]

Re: Nichia 365nm Light offerings

Hi LarsB,
Let me try again.

If an object appears to the viewer to be red under a full spectrum of light it is red because:
1)It reflects the red portion of the spectrum
2)absorbs the full spectrum but emanates red light either by fluorescing or actually generating red light
If you place the object in the dark and you still see red then it is generating this light.
If you place the object in the dark and flood it with a light source missing red and yet still see the object as red then I would venture that it is fluorescing.

If that makes sense, cool and if it doesn't no worries.

My last comment could be otherwise stated in recognition that water filters out light but non uniformly. If one were to determine what band of light has the greatest transmission through water and selected a LED matching this band you would have a monochromatic source with the greatest efficiency in terms of penetration. Admittedly, this monochromatic source of illumination is only as good as the objects being illuminated are apt to reflect it. I would imagine inorganic materials as well as sea life that spends time near the surface would be more apt to show up than deep dwelling critters.

I find it fascinating to ponder the why of light absorption or reflection and how this might have come about for a reason that enhances the survival of a species.

When one chooses a flashlight for illumination, the proper choice is based on what objects of interest reflect and not on so much on what comes out the front of the flashlight. That is to say it's what comes back to us that matters. A UV light with little visible light is a good example of this. A red light source at any depth is also a good example. At least that's my take.

 

[LarsB]

Re: Nichia 365nm Light offerings

Hi Don!

Hi LarsB,
Let me try again.

If an object appears to the viewer to be red under a full spectrum of light it is red because:
1)It reflects the red portion of the spectrum
2)absorbs the full spectrum but emanates red light either by fluorescing or actually generating red light
If you place the object in the dark and you still see red then it is generating this light.
If you place the object in the dark and flood it with a light source missing red and yet still see the object as red then I would venture that it is fluorescing.

The latter is exactly what happens in the image above with the red anemone; the ambient light is a full spectrum source of light missing red at that depth under water.

If that makes sense, cool and if it doesn't no worries.

It's all clear now!

My last comment could be otherwise stated in recognition that water filters out light but non uniformly. If one were to determine what band of light has the greatest transmission through water and selected a LED matching this band you would have a monochromatic source with the greatest efficiency in terms of penetration.

This is exactly what we do with our blue lights. Water is most transparent to blue light. Blue light penetrates the sea the deepest, where all other colours have been filtered out by the water column above.
Which is probably why underwater organisms fluoresce best with blue light, because they adapted to this property of water during evolution, allowing some corals to even dwell in the deep sea.

Admittedly, this monochromatic source of illumination is only as good as the objects being illuminated are apt to reflect it. I would imagine inorganic materials as well as sea life that spends time near the surface would be more apt to show up than deep dwelling critters.

Well, you can see exactly that in our fluorescence pictures, because our yellow mask and camera filters actually let pass a tiny little bit of blue light:
https://picasaweb.google.com/104533009596514075381/DahabSeptember2012

I find it fascinating to ponder the why of light absorption or reflection and how this might have come about for a reason that enhances the survival of a species.

Indeed, this is the great mystery at the moment.

When one chooses a flashlight for illumination, the proper choice is based on what objects of interest reflect and not on so much on what comes out the front of the flashlight. That is to say it's what comes back to us that matters. A UV light with little visible light is a good example of this. A red light source at any depth is also a good example. At least that's my take.

Of course what comes back matters (as opposed to what comes out of the front of a flashlight), because that's precisely how we see things, by the light which bounces off of them.

 

[absolutc]

Re: Nichia 365nm Light offerings

Was wondering if these were still available? Really looking for a flashlight that has a powerful UV light for making items fluoresce when I need it.

 

[McGizmo]

Re: Nichia 365nm Light offerings

Yes, these are still available.

 

[absolutc]

Re: Nichia 365nm Light offerings

Yes, these are still available.

What would the cost be for a complete, ready to use product? Which one do you recommend?

 

[gunga]

Nichia 365nm Light offerings

How much modification of the reflector is needed to put this uv light engine into an aleph a19 head?

 

[McGizmo]

Re: Nichia 365nm Light offerings

How much modification of the reflector is needed to put this uv light engine into an aleph a19 head?

You will need to remove some material off the front end of the reflector so the LE can digest further into the head.

 

[gunga]

Nichia 365nm Light offerings

Any idea how much? A little scary sanding the front if the reflector.

 

[McGizmo]

Re: Nichia 365nm Light offerings

Any idea how much? A little scary sanding the front if the reflector.

I would guess 2-3 mm. It's easy to figure out because you can see how much the LE is sticking out the back end of the head to determine how much is left to remove.

 

[gunga]

Nichia 365nm Light offerings

Thanks Don! Is the beam pattern okay in an A19 head?

 

[McGizmo]

Re: Nichia 365nm Light offerings

Thanks Don! Is the beam pattern okay in an A19 head?

It's a very tight spot.

 

[BenChiew]

Nichia 365nm Light offerings

It's a very tight spot.

And will throw that UV beam across a good size room.

 

[gunga]

Nichia 365nm Light offerings

Hmmm. I may put some diffusion film in if I get this setup. Maybe widening the spot would be useful. I feel a mule may be too diffuse for norland work etc.

 

[jalibass]

Re: Nichia 365nm Light offerings

I've been wanting a 365nm light for quite sometime to locate scorpions on our AZ reptile photo shoots. I also would like it to work well in hotel rooms to justify always bringing a sleeping bag. What current set up would your recommend?

 

[LarsB]

Re: Nichia 365nm Light offerings

I've been wanting a 365nm light for quite sometime to locate scorpions on our AZ reptile photo shoots. I also would like it to work well in hotel rooms to justify always bringing a sleeping bag. What current set up would your recommend?

How about this one?
http://www.firedivegear.com/products/bargains/#ukc4led
I'm giving it away for half my net cost.

 

[McGizmo]

Re: Nichia 365nm Light offerings

I've been wanting a 365nm light for quite sometime to locate scorpions on our AZ reptile photo shoots. I also would like it to work well in hotel rooms to justify always bringing a sleeping bag. What current set up would your recommend?

From my current offerings I think the SunDrop head would be the most appropriate choice given you applications. It offers a nice middle ground between full flood (Mule) and tight concentrated spot (Haiku).

 

[samuraishot]

Re: Nichia 365nm Light offerings

Has anyone ever tried this UV LE in a Makai head? Just wondering.

 

[LarsB]

Re: Nichia 365nm Light offerings

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

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