jeffrey.bartlett@LIGO.ORG - posted 11:04, Friday 03 August 2018 (43226)
ITM Optics Photos - No green light
With the green light shuttered (gate valves shut) took the opportunity to take a few shots of ITM-X and ITM-Y. The objective of these photos was to understand how the ITM OpLevs light pollutes the images of the ITM optics. When these shots were taken, there was a little 1064nm light present, which is visible as the purple areas on the optics. There is a small amount of OpLev light on the ITM optics from the up and down stream OpLevs. This light does not represent an issue for ITM optics face photos.
These photos demonstrate the ITM OpLevs will need to be switched off to get good images of the entire optic face. Need to repeat this study with stronger 1064nm light on the optic to see if it can dominate over the OpLev scatter.
| Arm | Frame | Exposure | Focus | OpLev-X | OpLev-Y | Notes |
|---|---|---|---|---|---|---|
| ITM-Y | Y-F1 | 3.0 sec | #2 - 65 | On | On | OpLev light pollution dominates upper left of optic. |
| Y-F2 | 3.0 sec | #2 - 65 | On | Off | Still some light pollution from OpLev X. | |
| Y-F3 | 10.0 sec | #2 - 75 | Off | Off | Increase exposure to replace OpLev light - Seeing some spots on the optic. | |
| Y-F3 | 10.0 sec | #2 - 85 | Off | Off | Tighter focus - See spots left edge to bottom - Some spots near center. | |
| ITM-X | X-F1 | 3.0 sec | #1 - 1755 | On | On | OpLev light pollution dominates upper right of optic. |
| X-F2 | 3.0 sec | #1 - 1755 | Off | On | Still some light pollution from OpLev Y. | |
| X-F3 | 6.0 sec | #1 - 1755 | Off | Off | Under exposed - Some IR visible in upper left. - Some OpLev light lower right. | |
| X-F4 | 30.0 sec | #1 - 1755 | Off | Off | Longer exposure - Some light from other OpLevs - No surface spots visible. |
Images attached to this report
