View Full Version : How to get rid of dust inside a projector?

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09-25-2011, 03:16
Using a small vacuum cleaner? Compressed air seems to much force?
Can it also be used on galvos and lenses or will that make scratches? (ofcource using a brush)

09-25-2011, 03:46
whatever you do, DON'T use compressed air for galvo mirrors

try first contact. for the other parts, you could use a small brush, or compressed air sprayed from a DISTANCE

then, you can try stopping the dust getting back in by installing fan filters etc

09-25-2011, 04:17
I already have a fan filter and everything sealed off but still got alot of dust from all the construction and building i did.

But with a compressor wont that put the dust everywhere including on the galvo's and dichro's?

09-25-2011, 08:09
First contact is your friend. That and a steady hand and patience.

09-25-2011, 08:35
Using a small vacuum cleaner? Compressed air seems to much force?
Can it also be used on galvos and lenses or will that make scratches? (ofcource using a brush)

Wrong philosophy, you don’t want to clean optical components, you want to prevent them from getting contaminated. I hermetically isolate all optical components in a cell where there are just 3 input apertures for the lasers which are coupled to the cell via foam rubber tubing. A bag of silica dehydrant in the cell keeps everything nice and dry for about 6 months.

Laser Wizardry
09-25-2011, 08:59
" 15 characters"

09-25-2011, 09:24
Steve's mods to Karl's most excellent post:

When dropping and dragging, you wait until the drop of solvent on the optic is starting to evaporate. Then you slowly pull the tissue across the lens, watching the white line that forms where the solvent is rapidly evaporating. If you don't get the "white line" you slow down the dragging The "Interface" between the wet tissue and the drying tissue is where the cleaning occurs. The "crud" does not stick to wet tissue, it sticks to dry tissue. The solvent wets, dissolves, and "picks up" the crud.

I know that sounds like a art, but if you do it one or two times on a dry day, as practice, it becomes obvious.

Steves other mod:

Use cotton swabs on wood sticks, without glue. Do NOT use VCR cleaning swabs with the foam.
Sticks with foam heads and swabs that have glue, cardboard sticks, or plastic sticks can leave plasticizers on the optic. Standard throat swabs from a pharmacy have no glue and wood sticks, and are very inexpensive. Sometimes you can get the excellent ones that are individually wrapped like chopsticks in
sterile paper packages.

Tip two, flush the swab with solvent once before cleaning, then "fling" the excess solvent off. Then rewet the swab with fresh solvent. This cleans the cotton before it cleans the optic.

Tip three, never use a eye-dropper to dispense your solvent, the rubber in the eye dropper will mess up your nice pure solvent. Instead, pour the solvent onto the swab, or get a lab grade pump dispenser, designed for the task. Spectra Physics used to think this was so important that they used to ship the dispenser with ion lasers.

It is, as Karl stated, important to not back contaminate your solvents.

And I agree, it is best to design your projectors to keep smoke and dust off the optics. Once a optic has micro-scratches, you never get a "clean" beam off it. Diffraction from dirty optics looks like crap. If you cannot do that, at least pressurize them with HEPA filtered air. A aquarium pump with a good filter can do wonders for keeping set of galvo mirrors clean. AR coated windows are inexpensive.

Laser Wizardry
09-25-2011, 09:37
" 15 characters"

09-25-2011, 09:50
thanks for both the advanced answers.

So i should buy a squeeze bulb wich my brother also uses for his expensive camera lens?
that can already do wonders?

i already purchased first contact as well since everyone recommends it.

i already have my projector 99% dust sealed but still have alot of dust inside from the contruction of the laser outside.

09-25-2011, 11:08
Would it be ok to clean optics and mirrors with Isopropanol 99,9% ?