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Window Wipers

Window Wipers

(OP)
I have an application where we have an optical window mounted above the ocean. We need to keep it clean. There will be several windows, all optically flat, all AR coated for various wavelengths. All of them will get hydrophobic coatings so that water will drip off. The windows will be mounted vertically, I hope.

I am planning to attach a window wiper to the system. Our optical people are concerned that the wipers will wear off the optical coatings.

Has anyone out there experience with window wipers on coated optical class?

--
JHG

RE: Window Wipers

Not personally, but there are existing systems that do that on military ships. Typically, though, coatings that wind up getting abraded, either by sand or whatever, have a diamond-like or hard-carbon coating, which may or may not be compatible with your hydrophobic coatings.

TTFN
I can do absolutely anything. I'm an expert!
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers

RE: Window Wipers

(OP)
IRstuff,

Cool! That is sort of what we want to do. Our's won't be very accessible for repairs and cleaning though.

The gadget I have seen that really looks nifty is called a clearview. Those round things you see in ships' windows spin at 1500rpm to shed water. Unfortunately the geometry does not work for us.

--
JHG

RE: Window Wipers

If you have a hydrophobic coating already, I would want to squirt water on it from time to time and blast it with an air sheet to remove any water droplets that decide to hang around. No external mechanical stuff necessary.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Window Wipers

(OP)
MacGyverS2000,

We are looking into some of that. The system is not very accessible. I have asked if compressed air is available. I doubt I can get windshield wiper fluid to it.

--
JHG

RE: Window Wipers

Perhaps you could use a filter system that would allow for much of the fluid to be cleaned and sent back into the reservoir. It would increase time between maintenance, but then maintenance itself would take longer (change filters, fluid, etc.).

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Window Wipers

Where is the dirt and grime coming from? The systems we built were located up on a radar mast, and no one seemed to be complaining about grimy windows. Generally, the condensated dew did an OK job of keeping the windows relatively clean. Speaking of which, you could possibly come up with a water condenser from the humidity in the air; it might get you enough water for a once a week spritzing, particularly if the location has high humidity. Or alternately, you could cool the windows to below the dew point, and use the water that does condense on the windows to do the cleaning.

TTFN
I can do absolutely anything. I'm an expert!
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers

RE: Window Wipers

(OP)
IRstuff,

We don't know where the dirt is coming from. We have not done this before. Our system will sit up a mast too.

--
JHG

RE: Window Wipers

Another option is a continuous plastic sheet wrapped in front of the lens face. Once a day (or what have you) a motor rotates the sheet past a velvet "wiper" (again, "or what have you"). Maintenance would consist of cleaning the wiper, and/or replacing the sheet if it became pitted, scratched, etc.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Window Wipers

I was thinking along the same line as MacGyverS2000 statement"...a blast of air..." except I would propose testing forceful blasts of warm hot air. I wouldn't be surprised if that method has not already been tested by the military and proved unworkable.

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