I want to use the light in a watertight nclosure，Can the light run in the air for a long time？
Are you talking about using a Lumens light inside an enclosure?
If so, i would not advise it. They are designed to be cooled in water. If you want light in an enclosure you can just use any LEDs you want really. The Lumens can get pretty hot when run out of water.
Are you trying to illuminate outside of the ROV or just inside the enclosure?
The Lumen lights are designed to be able to run in air indefinitely. They are typically used in applications where the casings are water cooled, but each Lumen has a built-in temperature sensor and firmware that will automatically dim the output of the light to prevent overheating. Be careful, however, as the cases can reach ~60˚C when run for prolonged periods of time in room-temperature air at high power. This may be higher in an enclosed space like a watertight enclosure.
The LEDs used in the Lumen lights are very efficient at low power outputs (<50% or 1500 µs on Lumen R2s), so you likely won’t need to worry about overheating if you only use the Lumens at these low powers.
However as Matt mentioned, pretty much any LED can be used inside an air-filled enclosure. High-power LEDs will have the same problems as the Lumens (i.e. overheating), but low-power LEDs should be fine.
I want to use this light in an enclosure of underwater camera system and i expressed inaccurately, the enclosure will be evacuated.
wow cool globe !!!
Im guessing thats an ordinary PTZ webcam by the looks?
The would think your biggest problem is flaring. The light will partially reflect internally by the glass onto your camera lens and cause your camera to see distorted bight images, its possible you may see nothing but bright flared out light on your camera entirely depending where you put the lights.
Im guessing you dont want an external light due to the fact that it would need to track your camera orientation to provide light in the right direction?
Iv have seen a scenario once before where an external light actually moved on the outside of the glass. The light was held in place by magnets inside the glass and powered via induction coils but it was a different application to what it looks like your doing.
One option could be that you use several external lights ringed around the bottom facing in different directions, then you have them set so only the light in the same zone as your camera orientation lights up? This would only work if your PTZ Webcam there has position feedback or you added something yourself to know where the camera is.
Hopefully some others here on the forum have some better ideas?
On the note of “enclosure will be evacuated” … do you mean your going to remove the air and put it under vacuum? I would not advice that as you essentially will be reducing the domes ability to hold back water pressure. The air pressure inside, 1 bar, is part of the calculations for depth rating. If your Dome there has only a small depth rating of a few meters you could be reducing this and cause a collapse. I would advice filling the globe with Nitrogen if moisture is a concern for you.