Elli, Kiwamu, (under WP 5166)

In response to Evan's report from the last night (alog 18020) about the ITM cameras not reproducing good recycling gain, we took a close look at the ITM digital cameras. As a part of the activity, we removed the lexan plates from the following cameras in order to improve quality of the images:

• ITMX infrared spool camera (VP2)
• ITMX green spool camera (VP1)
• ITMY infrared spool camera (VP5)
• ITMY green spool camera (VP6)

This is going to be a permanent configuration. The removal of the lexan got rid of unwanted stripes that had been seen on the ITMX green camera. The attached files show the ITMX green camera before and after the lexan removal. Hopefully this will help the reproducability of the initial alignment. Note that the oval shape shown in the attached pictures are due to the software aperture masking. The ITMY camera did not have stripes from the beginning and therefore no drastic change between before and after. We did not check the quality of the infrared cameras yet as they had not been an issue. We are still in the middle of figuring out optimum combination of the analog gain and exposure time, but we handed the interferometer to the evening commissioners.

Prior to the removal, John came with us to the LVEA and we went through all four cameras in order to see if they are mounted properly such that they don't accidentally hit the viewport within the movable range of the mount. Partly because of this test, we had to readjust the camera angles afterwards which then required us to renew the ALS ASC camera reference positions. We started the alignment process from TMS on both arms using the baffle PDs and subsequently optimized the ITM and ETM angles by maximizing the green transmission. Then we updated the camera positions.