LIGO Document E0900074-v3

Advanced LIGO Compensation Plate (CP) Coating Specification

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E - Engineering documents
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19 Oct 2009, 11:57
24 Mar 2009, 07:19
11 Mar 2009, 09:51
CP Coating Spec.
Referenced Polishing Specification and Drawing are for the custom compensation plates (with concave lens) SP03 and CP04. This coating specification is otherwise the same as the aLIGO coating specification, with small refinements noted in the "notes and changes" section.
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Notes and Changes:
This Coating specification is modified for coating the two custom CPs, CP03 and CP04. This specification also incorporates changes that we made during the CSIRO contract.

1. Specify the total transmission of the optic rather than each side, addressed as an average.

2. Remove the spectral scans of the witness samples; we found them to be expensive and not too useful because the witness pieces are placed outside the OD of the CP during the run and so, have a different response than the center of the optic. This is significant when dealing with an AR coating. It is more accurate to use a measurement at 1064, then tie the design response to that measurement.

3. S1 and S2 have the same specs, These are now combined and the extraneous N/As are removed from the original.

4. Remove the dark field inspection as well as the defect density requirement.
Rationale: This specification does not define the size of “a defect” in any way. With the dark field microscope inspection, the native microroughness of the part can appear as defects of significant density to cause the coater some concern.

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