Lighting


#1

Is there a combination of different colored lights that don't reflect off the algae and suspended solids in inland waterways.On a recent test the white lights on the camera reflected causing very limited visionin approximately six feet of water.


#2

I just found these lights as a potential replacement for a much cheaper LED module.

http://www.dealextreme.com/p/39mm-2w-9-smd-led-126-lumen-6500k-white-dome-light-dc-12v-51002

think they would work? I just ordered some to prototype with.


#3

This all varies greatly based on the water conditions for the particle environment you plan on using your ROV in. talk to a local scuba shop and they can tell you what filters they put on there lenses to get ride of back scatter and silt reflection. the rule of thumb is a lot of light spaced a good distance from the camera and use a technique called side lighting.


#4

Thanks Mike filtering is an avenue i have not gone down yet,seems to me that maybe the way forward also the most cost effective way of tackling the problem i will keep you posted cheers


#5

From my experience inspecting ship hulls by ROV, if you are going to be looking at a lot of red bottom paint or red rust from close up you benefit from adding 10% to 20% red LEDS to the lighting.

The best way to deal with suspended solids in the water is to have the lights far from the camera. You have a volume of water illuminated by the lights, and another volume seen by the camera. You want the only place those volumes intersect to be the object you want to look at. You do not want to illuminate the whole water column between the camera and the object with all the gunk it contains or all you will see is the gunk. This may require a "far" bank of white lights and a "near" bank of pink lights that are switchable and pointed at different distances.


#6

Definitely! In fact, Digitron (who makes the white LED arrays we are currently using) sells similar arrays with the same form factor in Green and Blue.

http://www.digitrondisplays.com/products/led-light-engines/

I think there is some really interesting spectroscopy that could be done simply with different colored lights.


#7

Thanks Douglas the camera i have has white light surrounding the lens i will change some too pink and mount some above and below the rov and give it a go, the gunk is plant solids as i am planning to use the rov on what they call in the U.K canals with little or no current keep you posted Ian


#8

Thanks Eric i will check out the digitron web site the answers are probably there cheers Ian