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Message ID: 101     Entry time: Mon Aug 22 16:59:13 2016
Author: Gabriele, Alastair 
Type: Optics 
Category: Daily Progress 
Subject: Laser polishing of the disk edges 

We set up a test facility for laser polishing the disk edges, using the CO2 laser in the TCS laboratory. We focused the beam with a 10" focal length lens, and installed the disk on a "rotation stage" that we motorized with a hand drill. We used a HeNe optical lever and a small container with water to define the horizontal plane and adjusted the disk as well as we could.

We first tested the procedure on the MO02 disk, which is the one already scared with the electrostatic drive burn mark. This disk is now definitely in bad shape. However, we felt confident in our procedure, so we took out the MO03 disk that was into the measurement system and proceeded to laser polish the edges. Things went quite smothly. Unfortunately we added some small damages to the disk surface in a couple of spots where the CO2 laser went out of alignment and melted the fused silica support of the disk. The edge however looks quite good now.

Q measurement is on-going at the timw of writing

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