Fog on the mirrors?

What kind of precautions do you take to stop fog/haze entering the scanner and building up on the optics?

My home made scanner has a fairly well constructed air flow, but the fans still cause air to be sucked through the beam exit hole.

Can this be avoided?

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Originally Posted by shobley

What kind of precautions do you take to stop fog/haze entering the scanner and building up on the optics?

My home made scanner has a fairly well constructed air flow, but the fans still cause air to be sucked through the beam exit hole.

Can this be avoided?

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Yep,

If you seal the optics from the rest of the laser

Usually you want a positive air pressure within the projectors case. That would cause only filtered air to be pulled in and keep the dirty air out. That doesn't entirely work all the time, because sometimes your projector is off and sometimes you dont have effective enough filters.

Then you can do what Dave suggested. Many people use acrylic sheets (or plexi-glass) to enclose the optical area of the beam table so that no dust can go in or out. There are no fans in this area either.

At the exit path of the beam there is a piece glass with an Anti-Reflective coating on it acting as the laser projector aperture.

Thanks - I do have the optics in their own "sub-chamber" but there's still some intake through the exit port.

Can you give me a link to the kind of glass I should be using to seal off the exit hole?

Quote:

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Originally Posted by shobley

Can you give me a link to the kind of glass I should be using to seal off the exit hole?

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Probably the cheapest and most convenient way is a Camera UV filter. They come in various diameters, just be careful to check the specs to make sure they transmit all light above ~400nm. Also, make sure that you get a clear multi antireflection coated one, some of them have slight tints on them which is something you definately don't want.

Cheers

Jem

Thanks for the replies...

Looking at the problem from another way, what would you recommend as a filter material for the fans? I've been using the black spongy stuff from PC supplies, but is there anything out there better for fog/haze filtering?

Steve

I've been thinking about buying a cheaper small HEPA filter.

Haven't tried it yet though.

http://www.laser-man.co.uk/2006/inde...d=51&Itemid=71

if you look at this page, its from the last meet. fluff aka mark was showing me a laser that has a galvos ect sealed.

its right near the top