Cleaning of Optical Surfaces

Workspace

Precleaning

1. Clean hands with soap.
2. Dry hands.
3. Use appropriate gloves.
4. Blow off dust from all sides.
5. Moisten tissue with acetone. Do not contaminate the bottle! Compared to alcohol, acetone is the better solvent. It evaporates quickly and thus reduces the formation of streaks significantly.
6. Remove coarse dirt from edge and chamfer of substrate.

Cleaning

1. First fold new tissue along the long side several times. Then fold across until you have a round edge.
2. Moisten tissue with acetone. Only moist, not dripping wet. Otherwise, there will be streaks.
3. Grab moistened tissue or use tweezer. Hold sample with second tweezer. Slide tissue from one edge of the sample to the other once.
4. Do not use the same part of the tissue again. Turn tissue inside out (at most once!). If the surface is not clean then, use a new tissue.

Attention: Use acetone only for sputtered surfaces!

Little Hints

1. Fingerprints on sputtered coatings: Moisten surface by breathing on it, slide acetone-moistened tissue over surface as long as water film is still visible. – Never do this with hygroscopic substrates (CaF₂,…)!
2. Clean concave surfaces using a tissue that is folded fewer times and can bend slightly in the center. Use your thumb to gently press the tissue onto the curved surface.
3. When cleaning, fix small samples on a concave support (polished, clean glass) using tweezers.
4. Store samples on concave polished glass support that has been cleaned using tissue + acetone.