After puzzling over last night's (UT Oct. 18) data we realized the phase signal was not being reliably calculated. Elwood scrubbed the code, and the afternoon of Oct. 18 we were able to show that we could control the pathlength of the interfereometer via the 2 um fringes.
This is a video of Elwood demonstrating the loop. We are looking at the FFT image of the 2um detector. The plot (barely visible) is showing the angle of the spots on the screen. As we are watching it, he changes it from 0 to 90 degrees.
The artificial source we were using showed 100-300 nm RMS pathlength variations. This suggests something is creating vibrating in our instrument. While this will not hold up further engineering, it is certainly something we need to fix before regular interferometric observations.
We also notice a drift of ~100-200 um in pathlength difference as the telescope slews from horizon to zenith.
/groups/lbti/search/index.rss?tag=hotlist/groups/lbti/search/?tag=hotWhat’s HotHotListHot!?tag=hot1/groups/lbti/sidebar/HotListAdded tag - hotphinzPhil Hinz2010-10-15 20:37:53+00:002010-10-15 20:37:53addTag3phinzPhil Hinz2010-10-15 13:18:40+00:002010-10-15 13:18:40updated2First createdphinzPhil Hinz2010-10-15 13:05:39+00:002010-10-15 13:05:39created1weblog2010-10-15T13:18:40+00:00groups/lbti/weblog/b808eFalseFirst Night Results/groups/lbti/weblog/b808e/First_Night_Results.htmlPhil Hinz3 updatesFirst Night Results
It was an eventful first night on the LBT. Network connections failed, hardware refused to turn on, all the typical problems of a new instrument. Aft...Falsephinz2010-10-15T13:18:40+00:00hot/groups/lbti/search/index.rss?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcomelist/groups/lbti/search/?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcomeRecent ChangesRecentChangesListUpdates?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcome0/groups/lbti/sidebar/RecentChangesListmodifiedDateallRecent ChangesRecentChangesListUpdateswiki/welcomeNo recent changes.reverse5searchlist/groups/lbti/calendar/Upcoming EventsUpcomingEventsListEvents1Getting events…