 Wed Feb 15 11:34:01 2012, steve, Update, , under the shouth end optical table 
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| I added an U channel based bottom shelf at the south end today. |
 Thu Apr 26 09:22:17 2012, steve, Update, , under the east end optical table
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Quote:
I added an U channel based bottom shelf at the south end today. |
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Wed Jun 27 11:27:49 2012, Liz, Update, , First Week Update!
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This week, the other SURF students and I got
acquainted with the caltech campus, LIGO 40m lab and the expectations of the SURF program.
We went to a lot of safety meetings and lectures that established a framework for the jobs we will be doing over the course of the summer. I went |
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Mon Aug 13 19:29:10 2012, Manasa, Summary, , Ringdown measurements
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I tried to make ringdown measurements at the IMC using the DC falling edge as the trigger. Input to the MC was switched off by changing the polarity
of the MC servo. But it does not seem to give the needed data as there seem to be several DC falling edges as soon as the polarity is switched. We should
think about a better trigger or try to setup data recording from the oscilloscope seamlessly. |
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Thu Aug 23 12:17:39 2012, Manasa, Update, , IMC Ringdown
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The ringdown measurements are in progress. But it seems that the MC mirrors are getting kicked everytime the cavity is unlocked by either changing the
frequency at the MC servo or by shutting down the input to the MC. This means what we've been observing is not the ringdown of the IMC alone. Attached
are MC sus sensor data and the observed ringdown on the oscilloscope. I think we need to find a way to unlock the cavity without the mirrors getting |
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Thu Aug 23 15:35:33 2012, rana, Update, , IMC Ringdown
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It is HIGHLY unlikely that the IMC mirrors are having any effect on the ringdown. The ringdowns take ~20 usec to happen. The mirrors
are 0.25 kg and you can calculate that its very hard to get enough force to move them any appreciable distance in that time. |
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Thu Aug 23 17:51:25 2012, Manasa, Update, , IMC Ringdown
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Quote:
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Thu Aug 30 12:01:27 2012, janosch, Manasa,Steve, Update, , ETMX
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We have done some work at ETMX today. We installed the baffle and placed two mirrors on the table.
The baffle position/orientation still needs to be checked more thoroughly to make sure that the beam will pass through the center of the baffle
hole. |
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Thu Aug 30 17:03:32 2012, janosch, Manasa, Steve, Update, , ETMX
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The baffle has been moved away from ETMX towards the edge of the table (in fact, it is a little beyond the edge). It is also rotated so that its long
edge is horizontal. In this way it was possible to center the baffle hole with respect to the optical axis, but also make it possible that the camera looks
over the baffle. |
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Fri Aug 31 10:16:02 2012, janosch, Steve, Update, , ETMX, scattering preps
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The alignment of the pick-off mirror near ETMX is done. Everything turned out to be easy once we realized that there is no sense getting the alignment laser
(going through viewport to pick-off to ITMX) back to ETMX. It is only necessary to hit ITMX somehow, since this makes sure that there is one scattered
beam that will make it from ITMX to pick-off through viewport. |
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Thu Sep 6 17:11:40 2012, janosch, Manasa, Steve, Update, , pick-off and baffle at ETMY
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We have installed the pick-off mirror at the ETMY table for the small-angle scattering measurement on ITMY. As we had already done for the
X arm pick-off, the pick-off mirror at ETMY was aligned shooting a green laser normally through the viewport on the pick-off and steering it onto
ITMY. |
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Fri Sep 7 00:08:10 2012, janosch, Metaphysics, , baffle clipping loss
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With a curvature radius of about 57m for the ETMs, flat ITMs at the beam waist, and using 39m for the arm lengths, one finds that the beam radius
at the ETMs is about 5.3mm. The clipping power loss of a 5.3mm beam through a 20mm radius baffle hole would be less than a ppm of a ppm if the beam was
perfectly centered. If the baffle hole had 15mm radius, the clipping loss would be 0.01ppm. If the baffle hole had 10mm radius, the loss would be |
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Fri Sep 7 15:58:29 2012, Rijuparna Chakraborty, Update, , cavitymode scan
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| IMC transmission photodiode has been aligned. |
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Fri Sep 7 17:37:16 2012, Jenne, Update, , cavitymode scan
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Quote:
IMC transmission photodiode has been aligned. |
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Sat Sep 8 00:15:57 2012, Rijuparna Chakraborty, Update, , cavitymode scan
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Quote:
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Wed Sep 12 19:26:08 2012, Rijuparna Chakraborty, Update, , cavitymode scan 7x
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Summary: Recorded the presence of higher order modes in IMC
What I did: Misaligned the flat mirror MC1 by small amount in both pitch and yaw (it was needed to be done cause at the beginning of the experiment
no higher order modes were present) and scanned the cavity for frequency-range 32MHz to 45MHz. |
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Thu Oct 4 23:01:49 2012, Rijuparna, Configuration, , cavitymode scan
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Here I am attaching the schematic diagram of the experimental set-up for IMC cavitymode scanning. A 30- 45MHz scanning signal generated by Agilent
4395A network analyzer enters EOM, which in turn modulates the laser beam entering IMC. The cavity response can be verified from reflected/transmitted
beam. |
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Wed Oct 10 15:31:59 2012, Rijuparna, Update, , cavitymode scan
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Rijuparna, Jenne
Today I checked the optical lay-out in MC REFL board of the MC REFL path on the AS table (I will put the updated diagram
in a few hours), and took a record of the reflected power of unlocked MC and power entering MC REFL PD. The power coming out of MC cavity when unlocked |
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Wed Oct 10 15:46:23 2012, Jenne, Update, , cavitymode scan
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Quote:
Rijuparna, Jenne |
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Fri Oct 12 15:31:03 2012, Rijuparna, Configuration, , cavitymode scan
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Rijuparna, Manasa
Today I have checked the optical layout of the MC transmission RFPD table and measured the laser powers at different points. Manasa helped me for
that. I found the power entering the RF photodiode is 0.394mW while the transmitted power of the cavity is 2.46mW. (I will give the diagram later). |
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Wed Oct 24 19:55:06 2012, jamie, Update, , my assesment of the folding mirror (passive tip-tilt) situation
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We removed all the folding mirrors ({P,S}R{2,3}) from the IFO and took them into the bake lab clean room. The idea was that at the very least we
would install the new dichroic mirrors, and then maybe replace the suspension wires with thinner ones.
I went in to spend some quality time with one of the tip-tilts. I got the oplev setup working to characterize the pointing. |
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Wed Oct 24 20:09:41 2012, jamie, Update, , installing the new dirchoic mirros in PR3/SR3
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When installing the dichroics we need to pay attention to the wedge angle. I didn't, so the ghost beam is currently point up and to the right (when
facing the optic). We should think carefully about where we want the ghost beams to go.
I also was using TT SN003, which I believe was being used for PR2. However, I don't think we want to install dichroics in the PR2, and we |
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Thu Oct 25 02:10:22 2012, Koji, Update, , my assesment of the folding mirror (passive tip-tilt) situation
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The thinner wire has a history that it did not improve the hysteresis (ask Jenne). Nevertheless, it's worth to try.
If you flip the clamp upside-down, you can lift the clamping point up. This will make the gravity restoring torque stronger.
(i.e. Equivalent effect to increasing the mass) |
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Thu Oct 25 06:49:49 2012, Koji, Update, , my assesment of the folding mirror (passive tip-tilt) situation
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Quote:
My big question right now is: is the plan to install new dichroics in PR2 and SR2 as well, or just in PR3 and SR3, where the green beams |
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Mon Nov 26 19:27:59 2012, Riju, HowTo, , Testing AG4395A+GPIB
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Riju, Jenne
We have checked the transfer function of a bandpass filter using AG4395A network analyzer and retrieved the data through GPIB. The RF out signal
of AG4395A had been divided by splitter with two outputs of the splitter going to through R and the filter which was connected to the A channel of the |
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Tue Nov 27 19:06:16 2012, Riju, Update, , Testing AG4395A+GPIB
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I ve tested another bandpass filter today with similar set-up. This time I took the data with corrected reference level. To set this reference-level
the filter was disconnected and the cable was connected "thru" according to the instructions provided in the manual of AG4395A at http://cp.literature.agilent.com/litweb/pdf/04395-90040.pdf,
page 3-10. The transfer functions are as follows |
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Wed Dec 5 17:38:41 2012, Riju, HowTo, , Photodiode transimpedance
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| I have started making the circuit to measure the transimpedance for the photodiode PDA10CF using Jenne's laser. I will continue it tomorrow. |
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Wed Dec 12 17:26:47 2012, Riju, Update, , Testing AG4395A+GPIB
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I repeated my experiment to get noise level. To get that I disconnected the bandpass filter SBP-10.7 from channel A of network analyzer AG4395A
and terminated both the open ends (open end of filter and open end of channel A) with 50ohm terminator.
Reference level had been corrected, signal and noise data had been collected separately w.r.t that level. |
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Fri Dec 14 14:40:31 2012, Riju, Update, , Photodiode transimpedance
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Photodiode PDA10CF was under test. The RF out signal of AG4395A had been divided by splitter with one output of the splitter going to R channel of the
network analyzer and the other to the laser. The splitted laser beams - splitted with beam splitter - fall on two photodiodes - one reference and the other
on PDA10CF. The outputs of these two photodiodes go to channel B and A respectively of the network analyzer. The measured transimpedance data had been |
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Tue Dec 18 16:44:00 2012, riju, Update, , Photodiode transimpedance
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Today I measured the dark current of the PDA10CF. The output of the PD was connected to the A channel of the network analyzer, when there was no light
falling on it. The response is collected using GPIB.
I will upload the result shortly. |
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Fri Dec 21 19:49:39 2012, Riju, Update, , Photodiode transimpedance
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I have repeated the transimpedance measurement of PDA10CF. Also made the dark current noise measurement by connecting the PDA10CF output to the A channel
of network analyzer. The results are as follows. I I started to take the reading for shot noise intercept current using a light bulb in front of
the PD, changing the current through the bulb, but at higher current the bulb filament got broken, so |
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Thu Jan 3 20:34:43 2013, Riju, Update, , Photodiode transimpedance
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Today I have measured the transimpedance and dark-noise of the MC-REFL PD.
For transimpedance measurement I first collected the data of the reference Newfocus PD connecting it at channel B of Network-analyzer using the
set-up of Jenne's laser. The data for the MC-REFL PD had been collected by connecting it to the A channel of Network Analyzer. To do that I shifted the |
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Fri Jan 4 15:11:28 2013, Jenne, Update, , TT
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[Jenne, Koji]
D - UL
B - UR |
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Tue Jan 8 14:01:21 2013, Riju, Update, , Photodiode transimpedance
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Here I upload the plots corresponding to my last day's measurements.
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Wed Jan 9 19:32:24 2013, Riju, Update, , Photodiode transimpedance
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Summary:
Today I have tested the MC transmission-end RF photodiode PDA255 for transimpedance and dark noise using Jenne's Laser and AG4395A network/spectrum
analyzer. The dark noise voltage distribution for the transmission and reflection PDs of MC and the analyzer has been compared. |
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Mon Jan 14 15:15:04 2013, Jenne, Update, , TT
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[Manasa, Jenne]
First plug in only one of the quadrupus cables, find out what coil it corresponds to according to screen, then plug in 2nd cable, don't test already-determined |
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Mon Jan 14 19:56:48 2013, Manasa, Update, , TT
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[Manasa, Jenne]
The motion of the magnets (~1.5mm estimated by looking at the magnets moving) correspond to ~2deg. tilt of the mirror. This would mean almost 1.5m |
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Wed Jan 16 18:58:08 2013, Riju, Update, , Photodiode transimpedance
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Today I have taken the reading for shot noise intercept current for the PDA255 - MC transmission RF PD. To do that I have put an incandescent bulb (JKL
lamps, 222 bulbs, voltage and current rating 2.25V and 0.25A) in front of the PD and varied the current through it from 0A to 0.29A at 2.2V. I measured
the corresponding DC voltage and took the noise data (4395A spectrum analyzer/ format noise, channel attenuation 0dB) through GPIB . |
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Tue Jan 22 17:29:29 2013, Riju, Update, , Photodiode transimpedance
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Riju
Summary: I am stuck with the measurement of shot-noise-intercept-current of PDA255. Seeking help.
Motivation: It is to measure the shot noise intercept current for PDA255 - the MC transmission RF photodiode to get an idea for the noise current |
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Tue Jan 22 19:51:52 2013, Koji, Update, , Photodiode transimpedance
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- The data should be plotted in a log-log scale.
- The data points were only taken in the high current region.
- The plot may suggest that the amplifier saturate at the RF. |
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Wed Jan 23 11:43:19 2013, Riju, Update, , Photodiode transimpedance
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Quote:
- The data should be plotted in a log-log scale. |
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Wed Jan 23 20:27:05 2013, Riju, Update, , Photodiode transimpedance
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Today I have repeated the expt for shot noise intercept current. Koji found that the Spectrum analyzer is going to saturation, so we have used one DC
blocker (MCL - 15542 model) in PD signal.
I will analyze the data and report. |
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Mon Jan 28 17:59:02 2013, Riju, Update, , Photodiode transimpedance
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Summary: Measurement and plot of shot-noise-intercept-current for PDA255.
Motivation: |
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Tue Jan 29 18:40:20 2013, Riju, Update, , Photodiode transimpedance
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Today I have taken data for shot noise intercept current for PDA10CF. I will process the data and report.
Note: GPIB address changed, new command for AG4395A network/spectrum analyzer: ./netgpibdata.py -i 192.168.113.108 -d AG4395A -a 10 -f filename |
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Thu Jan 31 12:44:42 2013, Riju, Update, , Photodiode transimpedance
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Today I collected the data for shot noise intercept current for MC REFL PD. I didn't get many data points at higher DC voltage of the photodiode, cause
the incandescent bulbs get burnt at that level; two bulbs I have burnt today. I will process the data and report. |
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Thu Jan 31 15:56:38 2013, Riju, Update, , Photodiode transimpedance
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Summary: Measurement
and plot of shot-noise-intercept-current for PDA10CF.
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Fri Feb 1 14:47:17 2013, Riju, Update, , Photodiode transimpedance
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Summary: Measurement
and plot of shot-noise-intercept-current for MC REFL PD.
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Thu Feb 7 19:24:57 2013, Riju, Update, , Photodiode transimpedance
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Summary: Measurement
and plot of shot-noise-intercept-current for MC REFL PD.
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Tue Feb 12 17:26:31 2013, Chloe, Update, , QPD circuitry to test mount vibrations
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I spent awhile today reading about op-amps and understanding what would be necessary to design a circuit which would directly give pitch and yaw
of the QPD I am using. After getting an idea of what signals would be summed or subtracted, I opened up the QPD to take better pictures than last time
(sorry, the pictures were blurry last time and I didn't realize). It turns out some of the connections have been broken inside the QPD, which would explain |
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Fri Feb 15 17:11:13 2013, Chloe, Update, , QPD circuit pictures
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I took better pictures of the circuits of the QPD and spent a couple of hours with a multimeter trying to figure out how all the connections worked.
I will continue to do so and analyze the circuits over the weekend to try to understand what is going on. I also have an old SURF report that Eric sent
me that is similar to the design I was planning to use to sum the pitch and yaw signals. I will try and look at this over the weekend. |