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Tue Jul 2 11:21:24 2013, Erica, DailyProgress, fiber optic, mode matching        Wed Jul 3 09:46:48 2013, Erica, DailyProgress, fiber optic, mode matching           Thu Jul 11 01:40:19 2013, Erica, DailyProgress, fiber optic, mode matching              Fri Jul 12 00:51:39 2013, Erica, Notes, fiber optic, mode matching                 Tue Jul 16 10:27:47 2013, Erica, Notes, fiber optic, mode matching, beam recombination                    Tue Jul 16 11:02:47 2013, Erica, Notes, fiber optic, mode matching, beam recombination                       Wed Jul 17 11:58:47 2013, Erica, Notes, fiber optic, mode matching, beam recombination                          Wed Jul 17 18:29:37 2013, Erica, DailyProgress, fiber optic, reducing drift in the recombined beam                             Sat Jul 20 23:39:09 2013, Erica, DailyProgress, fiber optic, reducing drift in the recombined beam                                Tue Jul 23 10:29:12 2013, Erica, DailyProgress, fiber optic, reducing drift in the recombined beam                                   Tue Jul 23 11:43:00 2013, Evan, DailyProgress, Electronics Equipment, Zach's op-amp recommendations                                   Fri Jul 26 11:07:44 2013, Erica, DailyProgress, BEAT, circuit for measuring temperature fluctations on CTN table                                      Fri Jul 26 11:22:45 2013, Erica, DailyProgress, BEAT, circuit for measuring temperature fluctations on CTN table                                         Fri Jul 26 11:45:28 2013, Erica, DailyProgress, BEAT, circuit for measuring temperature fluctations on CTN table                                            Mon Jul 29 13:30:26 2013, Erica, DailyProgress, BEAT, adding resistor, capacitor, and sockets                                               Tue Jul 30 12:23:41 2013, Erica, DailyProgress, BEAT, addressed noise problem, DC signal                                                  Thu Aug 1 00:25:02 2013, Erica, DailyProgress, fiber optic, insulating foam                                                     Fri Aug 2 12:38:41 2013, tara, DailyProgress, fiber optic, insulating foam                                                        Tue Aug 6 12:31:24 2013, Erica, DailyProgress, fiber optic, insulating foam                                                           Wed Aug 7 13:27:00 2013, Erica, DailyProgress, fiber optic, more foam, calculations for convertion from voltage to frequency                                                              Wed Aug 7 18:53:20 2013, Erica, DailyProgress, fiber optic, noise budget, Matlab notes.                                                                 Tue Aug 13 12:39:36 2013, Erica, DailyProgress, fiber optic, rewrote calculations for converting from voltage noise to frequency noise                                                           Tue Aug 13 12:28:20 2013, Erica, Notes, Electronics Equipment, new AD 590 circuit and its noise calculation, beam alignment                                                              Fri Aug 16 10:35:44 2013, Erica, Notes, Electronics Equipment, AD590 msrmt, conversion to freq noise                       Tue Jul 30 16:19:32 2013, Erica, Notes, fiber optic, setup for beam recombination                       Mon Aug 5 12:21:00 2013, Erica, Notes, fiber optic, calculation: phase change for fiber        Tue Jul 30 15:48:47 2013, Erica, DailyProgress, fiber optic, noise for GYRO

Message ID: 1245     Entry time: Sat Jul 20 23:39:09 2013     In reply to: 1243     Reply to this: 1251 Author: Erica  Type: DailyProgress  Category: fiber optic  Subject: reducing drift in the recombined beam

July 18 Redid inventory of the lenses and printed out a new sheet because there are fused silica and BK7 lenses, which have different focal lengths for a given radius of curvature. It only has the lenses in the box. Tara had like 6 to 8 other ones but I don't know where they are. Looked for papers that give numbers for noise added... Like before, I'm having trouble. got login for SVN to work Evan helped come up with other solutions to try to reduce the drift on signal from the recombined beam. We put UHV aluminum foil on the coil of fiber to reduce the acoustic noise but it didn't seem to have much effect on the drift. Acoustic sound affected the fiber because the drift seemed to speed up a little bit when we closed the cabinet door and jumped around. When the lab door was closed, there was a spike in the signal but thing settled down fairly quickly. We turned off both Hepa filters but like yesterday, it also didn't seem to do much. We elevated the coil off the table by using the black rectangular clamps to dampen possible transfer of movement from the table to the coil. We locked the laser to the cavity to reduce the laser noise. The error and control signals were very steady compared to the drift in the beam signal. We calculated the change in frequency over 1 period of drift is about 5 MHz, and for the fiber to change by 1 wavelength, it would take a temperature change of 16 mK. Looking at Rana's graph of for noise calculations (http://nodus.ligo.caltech.edu:8080/PSL_Lab/1205), we calculated the rms temperature noise due to ambient air at 100 mHz (because the period of the drift was on the order of 10s) was 100mK rms, which is an order of 10 larger than the calculated change in temperature. The fiber passes by the laser, which is emitting a bit of heat, which may be a part of what is causing the drift.

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