LIGO Document T1100490-v1
- About half of our CPs show spots when examined under the CSIRO dark field microscope. We took a risk and coated one of them, CP03. We have examined one spotty CP03 and one pristine CP09 in a forward scatter configuration using the CASI instrument. On average the spotty CP has a 1% greater signal than the pristine CP. Since our estimates of these surfaces are in the 3ppm level for microroughness and comparable Rayleigh scattering, we find a 1% difference is quite encouraging and have determined to go ahead and use the CP optics.
Confirmed by e-mail with Fritschel, Gustafson and Yamamoto.
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