Lights in Murky water

chaetodon

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Hi I see Z-max was doing experiments with the best color light penetration in murky water.
Has anyone gone any further with this? I was thinking of trying a powerful laser pointer with the most suitable penetrating wavelength and spreading the beam a little with a lens so that it acts like a torch beam. Has anyone tried this, or does anyone know if it could possibly work? lasers are much more powerful than sunlight. I dive in 2 to 3 meters vis sometimes and any info anyone has I would like to hear from them
 

chillinn

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Welcome to CPF!

Though the article I'm linking is answering a different question, and concerns ocean water depth, this very likely is related to your question.
Red light has the longest wavelength and, therefore, the least amount of energy in the visible spectrum. Wavelength decreases and energy increases as you move from red to violet light across the spectrum in the following order: red, orange, yellow, green, blue, and violet.

As light wavelength decreases from red to blue light, so does the ability of light to penetrate water. Blue light penetrates best, green light is second, yellow light is third, followed by orange light and red light. Red light is quickly filtered from water as depth increases.

It would seem to follow then that the best penetrators of all water, including murky water, in order of effectiveness, is gamma rays, followed by x-rays, followed by UV-C, UV-B, UV-A, violet, royal blue, blue, blue-green, green, yellow-green, yellow... I think you see where this is going. Although it might depend somewhat on what exactly the stuff is that is making the water murky and which wavelengths that stuff is absorbing, most of murky water is water, and the higher the energy the light is, the more penetration it will have.
 

chaetodon

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Welcome to CPF!

Though the article I'm linking is answering a different question, and concerns ocean water depth, this very likely is related to your question.


It would seem to follow then that the best penetrators of all water, including murky water, in order of effectiveness, is gamma rays, followed by x-rays, followed by UV-C, UV-B, UV-A, violet, royal blue, blue, blue-green, green, yellow-green, yellow... I think you see where this is going. Although it might depend somewhat on what exactly the stuff is that is making the water murky and which wavelengths that stuff is absorbing, most of murky water is water, and the higher the energy the light is, the more penetration it will have.

Thanks Chillin, I did realize about the power penetration of the different wavelengths, that's probably why (so I am told) that some sea creatures can see further because their eye construction can see ultra violet spectrum. I see the problem I have is I may also have to consider is the light reflecting from the water particles back to the eye. This may be part of the problem. I read a comment on this forum by Z max but this was from 2009. he was experimenting with this and found amber light to penetrate further. I suppose that's why they use sodium vapor lamps at foggy intersections. I was wondering if even red although it doesn't penetrate water very far is less reflective on the particles back to the eye, and you could actually see further with a red light ? Perhaps the happy medium is in the yellow orange range. lasers are much more powerful than sunlight and I guess the only way to know is to try one. I imagine the military would have experimented with everything if it could be done. Maybe I need a high tech virtual reality headset that can convert ultra violet in to virtual reality, something like the military nigh vision goggles !! just joking I don't think this could be done at present :^) chaetodon <><
 

nbp

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McGizmo is probably one of the more experienced divers/light experts on the board. Perhaps he would have some input? Just an idea. :)
 

chillinn

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+1 his underwater pictures are stunning to say the least. We know his lights are so amazing:)

McGizmo's underwater photography is quite exceptional. I have someone close to me that has become an exceptional photographer, like the camera is a part of him, even all of his throwaway snaps are as perfect as I can determine, and I am hypercritical of such things. But he started diving a few years ago, and is now taking underwater pictures, and though fascinating, they don't have the punch that McGizmo's photography has, but are washed out with poor contrast and colors. McGizmo has figured something out; he knows.
 

Offgridled

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McGizmo's underwater photography is quite exceptional. I have someone close to me that has become an exceptional photographer, like the camera is a part of him, even all of his throwaway snaps are as perfect as I can determine, and I am hypercritical of such things. But he started diving a few years ago, and is now taking underwater pictures, and though fascinating, they don't have the punch that McGizmo's photography has, but are washed out with poor contrast and colors. McGizmo has figured something out; he knows.
Photography is a great art . Takes time to figure out the right camera lighting etc. I'm super impressed with those with this talent. Mcgizmo is among the best for sure..
 

island

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Just an observation but with 2m or 3m viz in murky water you probably will get alot of backscatter from particles.
Are you diving in the day or night?
Are you scuba diving or freeding/snorkeling?
What depths?
Fresh or salt water?

I've been night freediving in the sea and someone was shining a green laser at us from the shore about 50m away. We were coming back in and had about 5m viz in 5m depth. The laser made a visible beam in the water.
(The guy wasn't there when we got out... I was planning on having a word about eye safety :) )
 

ssanasisredna

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It's an old thread, but anyone is following this, other than blue light is absorbed less by liquid water than red, the rest of it is wrong.


Welcome to CPF!

Though the article I'm linking is answering a different question, and concerns ocean water depth, this very likely is related to your question.


It would seem to follow then that the best penetrators of all water, including murky water, in order of effectiveness, is gamma rays, followed by x-rays, followed by UV-C, UV-B, UV-A, violet, royal blue, blue, blue-green, green, yellow-green, yellow... I think you see where this is going. Although it might depend somewhat on what exactly the stuff is that is making the water murky and which wavelengths that stuff is absorbing, most of murky water is water, and the higher the energy the light is, the more penetration it will have.
 

KITROBASKIN

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It's an old thread, but anyone is following this, other than blue light is absorbed less by liquid water than red, the rest of it is wrong.

If you think it is so wrong, how about shedding some light on this? Let's see some research. So much of the time you have an interesting perspective and knowledge base. Calling someone an insulting name with the backwards letters of your forum name? You are better than that.
 

ssanasisredna

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If you think it is so wrong, how about shedding some light on this? Let's see some research. So much of the time you have an interesting perspective and knowledge base. Calling someone an insulting name with the backwards letters of your forum name? You are better than that.

I am not here to be a personal Google. This knowledge is well known by most that study light, atmosphere, water, etc. Feel free to research absorption spectra.
 

KITROBASKIN

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I am not here to be a personal Google. This knowledge is well known by most that study light, atmosphere, water, etc. Feel free to research absorption spectra.

You seem to be here, mostly to tell people that they are wrong? Come on. You have a special perspective on the subjects we care about.
 

TheMediocrePirate

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I would love to see some sort of experiment with tint colours, and see if it makes a difference.

In the 5 years I've been a public safety diver, and over 100 dives in zero to low vis. (<1m) conditions I really haven't found a light that works better then an other regardless of weather a light is LED, Halogen, or Xenon. The one area where I have seen a difference is with the width of the beam; the more focused a beam and with the least amount of spill, the better it seems to reduce the amount of light which is reflected off of suspended in the water (what we call turbidity) directly in front of you. I have seen the same thing above surface during smoke-filled rooms during structure fires.

There's something to be said for a specific tint working better in a certain condition (i.e. yellow fog lights in a snowstorm), but with an almost infinite amount of composition of stuff floating in the water that's constantly changing with the seasons one would constantly need to test and adjust tints for optimum performance for the colour of the particles it will be reflecting off of. Its not really an "one size fits all" kind of situation, and for visible wavelengths of light I think there will be a negligible difference. There comes a point that the density, size, and composition of suspended particles is just too much to allow any light through, and the more light one has, the more is reflected off of a particle to it's immediate neighbours making a big glowing impenetrable cloud. We all dive with small backup lights with our gear, but they're rarely of any use, and mostly used to charge up our luminous gauges so we can see them when we hold them up to our masks. If we have to document anything for an investigation, we normally bring a big ziplock bag filled with clean and clear water to make a gap of "not crap-filled water" between the thing we're trying to document (VIN numbers on cars, license plates, weapons, etc.)
 
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