Cleaning of substrates
The quality of the coatings is a critical point in the production of high power laser components. And that quality starts with the cleaning of the substrates before coating, to eliminate all possible contamination.
At LASEROPTIK all suitable substrates are automatically cleaned in one of three available multi chamber ultrasonic cleaning lines.
A robot system moves the substrates automatically, following identical process steps. The total process takes 30 to 50 minutes.
If substrates are not suited for automatic cleaning (for example hygroscopic material), they are manually cleaned under laminar flow conditions. This process is similar to the one described below, "Cleaning of coated optics".
Both, substrate cleaning and coatings are performed in well maintained cleanrooms. In any case cleaned substrates are inspected for 100% under a stereomicroscope before mounting them into the substrate holders and fixing them in the coating machine immediately afterwards.
Cleaning line process
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| 1.-------------------> Cleaning with ultrasonic (generators for 40/80 kHz). Power and duration are varied due to the needs of the material to clean and its condition. Used detergents are alkalescent. |
2. -------------------> The cleaning goods are rinsed with reverse osmosis (RO) water. |
3.-------------------> Repeat step 1. |
4.-------------------> Repeat step 2. |
5.----------------------- Pure water rinse with DI water (de- ionized), produced in circulating systems. |
------------------------> Lift-out, slowly lifting out of the DI water to guarantee residue-free drying. |
6. Final drying by IR- radiation. |
We recommend to clean coated optics with clean air only. If the surface is very dirty you can try the following steps:
1) Blow off the optic with clean air or nitrogen to remove particles.
2) Fold cleaning tissue (like lens cleaning tissue Whatman 105) or microfiber cloth (Toraysee MK14.5H) into a suitable form according to the size of the surface to be cleaned.
3) Moisten the tissue or cloth with recommended solvents like isopropanol or ethanol.
4) Clean the coated surface with uniform circular movements and low pressure. Coated optics produced by IAD, IP, MS and IBS can normally resist some more pressure.
5) The removal of the tissue or cloth from the coated surface should be straight and without any pressure.
6) Check the cleaning results with a bright light source and/or under a microscope.
7) Repeat the cleaning processes if the optic is still dirty.
Please note the following:
• To avoid fingerprints use powder free clean gloves (latex, nitrile).
• If you use tweezers to hold the substrate use tweezers with protected tips (e.g. rubber or cork).
• When cleaning small optics hold the folded tissue or cloth with clamp tweezers.
• Change the tissue or cloth as often as possible.
This cleaning recommendation refers to optics which are coated with metal oxide layers and / or with a protective layer.
Please contact us for more information about cleaning of coated optics. We can assist you even on the phone.
