Mirror Mechanics: For each mirror a support has been machined (INFN Perugia+Cern) to guarantee best possible protection during the production procedures, gluing activity, storage and installation
Glass substrate cleaning: The glass substrates pass through a standard cleaning procedure: soap /water /distilled water /alcohol
Each mirror is rinsed many times first with tap water and after with distilled water.
Controlled drying: The remaining alcohol is dried with help of compressed nitrogen jets to avoid any cleaning traces.
The cleaned substrate is carefully positioned on the round turning plate where the evaporation process is taking place
3 fixation pieces on the edges prevent falling and 3 V-pieces in the corners avoid rotation.
The plate including substrate is turned upside down and then fixed to the rotation mechanics in the evaporator.
Preparation of the evaporator
With about 4KV applied voltage on the solid aluminum block the substrate surface is cleaned via Ion bombardment in vacuum (for about 4min). This procedure is also improving the attachment of the first metallic layer (Cr)
Cleaning Traces:Due to an improved drying procedure of the alcohol on the substrate surface we have only very few cleaning traces observed on the coating of the mirror.
Optical inspection of reflective coating
Final stocking: Mirrors are carefully protected in their mechanics (mirror surface looking down). Enwrapped with a dry nitrogen filled plastic bag they are protected against oxidation and dust.
The corresponding samples for each mirror are stored in the lab for future possible crosschecks