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ID Date Authordown Type Category Subject
  2661   Wed Sep 8 14:35:22 2021 AidanDailyProgress2um PhotodiodesRunning automated testing suite on A1 PD

[Aidan]

I turned off the cryocooler and the A1 PD is slowly coming up to room temperature from ~53K (it's currently at 78K).

There is an automated script (autorun2021.sh) running to acquire data from the PD during this process (it is attached):

  1. Record dark current sweep with Keithley
  2. Record PD noise spectra (in DAQ) with different biases [-100, 0, 300, 600, 1000]mV. This involves steppnig the bias and waiting for 60s while fast AC data from the diode goes into the frames. Preamp setting = 1E3, SR560 setting is attached. Note that the SR560 photo shows an OVERLOAD light. This is only when the laser is on and the bias is high. When running the bias stepping up, the overload light only came on for a moment when the bias reached 1000mV - it stayed on for about 2-3s during this time. It's possible that the SR560 may saturate as the noise level increases with temperature. I might have to drop the amplification a touch.
  3. Record the QE for the PD for different bias settings. Bias is set to [-100, 300, 600, 800, 1000]mV. The laser current is turned on for 10s and off for 15s. The laser current output has a 0.15Hz pole on it so the current slowly ramps up and down. This allows us to record the reference PD and JPL PD levels for increasing intensities (as the PD is observed to saturate since the beam is close to a waist/focus on the PD).
  4. Get bright current sweeps with the Keithley for 20mA and 100mA going to the laser
  5. Run the maximize_output_power.py Python script that makes small changes to the piezo steering mirror to maximize the output of a CALC channel which is the ratio of the JPL PD to the REF PD (JPL_PD/REF_PD) - this removes first order power fluctuations from the alignment process.
  6. Dump all measurements into a directory identified by the GPS time and measurement number
    1. ~/JPL_PD/data/A1/<GPS_TIME>-<MEAS_NUM>/

Example output is attached.

Note - I was originally running the code with a manual realignment each time. I switched to maximize_output_power.py around the 2:30PM mark (~78K) and this yielded a 30% increase in photocurrent. So QE results below this are going to be low.

CALC channel (~/JPL_PD/Ioc/QIL/db)

record(calc, "C4:TST-PD_RESPONSE")
{
    field(SCAN, ".1 second")
    field(INPA, "C4:TST-FM29_OUT16")
    field(INPB, "C4:TST-FM30_OUT16")
    field(CALC, "ABS(B/A)<2?(B/A):2")
}

---

Notes from the lab:

Wednesday 8-Sep-2021

11:47AM – Script is ready to record data

  1. Record dark current sweep with Keithley
  2. Record PD noise spectra for different biases
  3. Measure QE for different biases
  4. Get photocurrent sweep vs bias with Keithley at 100mA and 20mA

 

12:15PM – start run with chiller on

  • 1315163811-1001 (first directory) – 53.6K

12:26PM- chiller off

  • 1315164407-1002 – 53.66K

12:36PM – third loop

  • 1315165029-1003 – 57.92K

12:48PM – 1315165720-1004: 60.98K

12:59PM – 1315166396-1005: 63.2K

1:10PM – 1315167064-1006: 65.2K

1:24PM – 1315167908-1007: 67.6K

1:35PM – 1315168569-1008 :69.4K

1:47PM – 1315169251-1009: 71.3K

  • Added a channel C4:TST-PD_RESPONSE which is PD_OUT/REF_PD. Cancels out the power fluctuations to first order to help when aligning.
  • This is running is an adHoc softIOC channel

1:57PM – 1315169873-1010: 72.9K

  • Might need to add heat into the base plate

2:07PM – 1315170489-1011 :74.45K

  • SR560 overloads a tiny bit on the bias = 1000mV setting for 3 or 4s after it reaches that setting.

2:26PM – running the max power script. Getting 30-40% more power!!

2:32PM – 1315171982-1001: 78.145K

NOW WITH AUTOALIGNMENT

2:34PM – 1315172074-1001: 78.3K

2:45PM – restarted code with longer pause (60s) between end of loop and maximize output power

3:18PM – restarted code with 120s pause between end of loop and Maximize Output

3:43PM – ADDED OFFSET OF 141 to FM29 (REF PD) which sets the zero power level to about zero. (in the middle of 1315176124-1003 measurement at 87.5K)

-----------

Channels:

Physical Variable Channel Name
Laser current setting C4:TST-FM12_OUT16
PD bias setting C4:TST-FM13_OFFSET
REF PD reading C4:TST-FM29_OUT16
JPL PD reading (DC) - preamp only C4:TST-FM30_OUT16
JPL PD reading (AC) - preamp + SR560 C4:TST-FM31_OUT
Keithley/Preamp switch C4:TST-FM15_OFFSET

 

Attachment 1: autorun2021.sh
#diode name
i=1001
diode=A1
caput C4:TST-FM15_OFFSET 0
sleep 1
while :; do
        #-----------------------------------------------------
        # dark current
        echo =======================
        echo ----- TOP OF LOOP -----
... 139 more lines ...
Attachment 2: maximize_output_power.py
# script to maximize the output power of the piezo
import serial
import time
import os, sys, subprocess
import numpy as np

def slowDownJog(ser):
    ser.write('1SU50\r\n')
    time.sleep(0.1)
... 195 more lines ...
Attachment 3: 1315172753_conditions.txt
C4:CTC-MS_WORKPIECE_TEMP_VAL 79.933
C4:CTC-MS_OUTERSHIELD_TEMP_VAL 241.116
C4:CTC-MS_INNERSHIELD_TEMP_VAL 86.579
C4:CTC-MS_COLDHEAD_TEMP_VAL 129.619
spectra_start 1315172767
PD_gain_DC FM30 C4:TST-FM30_GAIN 2
QE_v_bias_start 1315173068
Keithley_bright_start 1315173226
C4:CTC-MS_WORKPIECE_TEMP_VAL 81.07
C4:CTC-MS_OUTERSHIELD_TEMP_VAL 241.188
... 3 more lines ...
Attachment 4: IMG_4627.jpg
IMG_4627.jpg
Attachment 5: IMG_4628.jpg
IMG_4628.jpg
Attachment 6: Screen_Shot_2021-09-08_at_3.05.19_PM.png
Screen_Shot_2021-09-08_at_3.05.19_PM.png
Attachment 7: Screen_Shot_2021-09-08_at_3.05.51_PM.png
Screen_Shot_2021-09-08_at_3.05.51_PM.png
  2662   Thu Sep 9 09:23:56 2021 AidanDailyProgress2um PhotodiodesRunning automated testing suite on A1 PD

We're at 170K as of 9AM this morning. At the current rate, we should reach 273K tomorrow morning. 

  2663   Fri Sep 10 09:11:05 2021 AidanDailyProgress2um PhotodiodesRunning automated testing suite on A1 PD

9AM: At 232K this morning at 9AM. Turned on the heater to 1W around 9:07AM to speed up the return to room temperature. 

10AM - set heater to 7W

11:50AM - At GPS = 1315334850 - Set heater to 20W. Also noticed that SR560 output was railing so set gain to 500

Quote:

We're at 170K as of 9AM this morning. At the current rate, we should reach 273K tomorrow morning. 

 

  2664   Fri Sep 10 20:13:12 2021 AidanDailyProgress2um PhotodiodesRunning automated testing suite on A1 PD

I terminated the data taking around 5PM when the photodiode was at about 4C (277K).

 

Quote:

9AM: At 232K this morning at 9AM. Turned on the heater to 1W around 9:07AM to speed up the return to room temperature. 

10AM - set heater to 7W

11:50AM - At GPS = 1315334850 - Set heater to 20W. Also noticed that SR560 output was railing so set gain to 500

Quote:

We're at 170K as of 9AM this morning. At the current rate, we should reach 273K tomorrow morning. 

 

 

  2667   Wed Sep 15 08:22:32 2021 AidanDailyProgressCryo vacuum chamberCONTAMINATION: Black paint flecks throughout chamber

I was setting up for some characterization measurements of the JPL PD and I noticed that there are flecks of black paint all through the chamber. There were a couple of visible bare sections on the wall of the inner shield where paint had been removed.

Quote:

Monday I completed the vent that Aidan had started by turning off the cryocooler. During the afternoon I turned off the pumps, unbolted the chamber lid, and removed the radiation shield lids.

Next, Aidan was going to run some characterization measurements and determine whether to swap the diode or repeat with A1.

 

Attachment 1: IMG_4686.jpg
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Attachment 2: IMG_4687.jpg
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  2668   Wed Sep 15 08:33:39 2021 AidanUpdate2um PhotodiodesVideo review of 2um testing setup post A1 testing

https://dcc.ligo.org/LIGO-G2102040

 

  2669   Thu Sep 16 10:33:59 2021 AidanComputing2um PhotodiodesAutomation and analysis scripts for 2um data taking

The attached files are the scripts used to take data during the PD temperature cycling/testing and to retrieve and analyze data after the fact.

  • ~/JPL_PD/scripts/autorun2021.sh
    • ~/JPL_PD/scripts/piezo_mirror/maximize_output_power.py
  • ~/JPL_PD/data/A1_analysis/A1_analysis.py
Attachment 1: autorun2021.sh
#diode name
i=1001
diode=A1
caput C4:TST-FM15_OFFSET 0
sleep 1
while :; do
        #-----------------------------------------------------
        # dark current
        echo =======================
        echo ----- TOP OF LOOP -----
... 141 more lines ...
Attachment 2: maximize_output_power.py
# script to maximize the output power of the piezo
import serial
import time
import os, sys, subprocess
import numpy as np

def slowDownJog(ser):
    ser.write('1SU50\r\n')
    time.sleep(0.1)
... 195 more lines ...
Attachment 3: A1_analysis.py
# analysis od the A1 JPL PD diode
# Aidan Brooks - 10-Sept-2021

import cdsutils
import numpy as np
import matplotlib.pyplot as plt
import os, glob
import scipy.signal

... 172 more lines ...
  2671   Wed Sep 22 16:40:19 2021 AidanLaser2um PhotodiodesBeam size measurements of the 2um beam on the PD

I performed some occlusion measurements of the 2um laser going into the cryo chamber. For different values of dz on the collimating lens translation stage, I moved the power meter into the beam using it's translation stage by an amount dx.

One the beam was on the power meter (aperture = 5mm diameter) the power stayed constant for several MM before dropping again (indicating all the laser beam was on the power meter).

There was a big inrcease in incident power as dz was increased. This, and the constant power across the PD aperture, indicates that the beam is clipping or sees an aperture somewhere like the focussing lens (f=75mm) or further upstrean. I will review the expected beam size as a function of position, assuming the given NA fof the fiber.

 

Attachment 1: PD_measurement_layout.png
PD_measurement_layout.png
Attachment 2: PD_occlusion_measurements.txt
	Length from Focussing lens to POW METER = 80mm															
																
																
2.73mm			3.73mm			dz	4.73mm	5.73mm	6.73mm	7.73mm	8.73mm	9.73mm	10.73mm	11.73mm	12.73mm	13.73mm
																
dx (0.01mm)	PM(uW)		dx	PM(uW)		dx	PM(uW)	PM(uW)	PM(uW)	PM(uW)	PM(uW)	PM(uW)	PM(uW)	PM(uW)	PM(uW)	PM(uW)
60	191		40	3		200	241.9	272	305	348	395	454	523	605	697	798
50	189		50	7.25		175	241.7	270	307	346	394	452	519	595	685	777
35	181.7		65	23.6		150	234.5	262	296	333	377	432	492	563	645	727
20	169		75	85.5		130	218.8	243.6	274	308	356	395	445	507	579	657
... 7 more lines ...
  2672   Tue Sep 28 08:23:11 2021 AidanUpdate2um PhotodiodesDistances between optics, collimating lens, focussing lens and photodiode

Precise distances required between:

  • fiber launcher and collimating lens
  • focussing lens and beam waist 

accounting for thickness of optic mounts, sunken fiber launcher plane, back focal length of lenses, dispersive variation in focal lengths of lenses  from nominal and distance between PD surface and base of PD mount. Also shown are the distances between the steering mirrors (PZT steering mirror, lower periscope mirror and upper periscope mirror).

Beam propagation through this system is shown in the attached PDF. The upper plot shows a paraxial beam propagation as the collimating lens is displaced from the nominal position. The purpose is to indicate the beam size (radius) all the way through the system. We would like this to be less than about 6mm radius (12mm diameter) on all of our 1 diameter optics. The second plot shows the waist size at the PD as the collimating lens is moved by +/- 2mm. The purpose is to allow us to tune the beam size on the PD without clipping the beam on intervening optics. 

Keeping the collimating lens Delta Z to a range of +/- 2mm is safe for beam propagation in terms of clipping on apertures or on the 1.5mm diameter PD.

Attachment 1: JPL_PD_collimating_lens_Optical_layout.pdf
JPL_PD_collimating_lens_Optical_layout.pdf
Attachment 2: JPL_PD_optical_propagation_and_beam_size.pdf
JPL_PD_optical_propagation_and_beam_size.pdf
  2675   Sun Oct 3 08:22:49 2021 AidanSummary2micronLasersStarting data taking and second test of JPL PD A1
  • Output going to JPL_PD/data/A1_test2 and DAQ
  • Test commenced at 8:20AM and cryo cooler started shortly afterwards
  • Once trhough the loop takes about 20 minutes
  • Cryocooler on at 8:42AM
  2676   Wed Oct 6 13:50:18 2021 AidanSummary2micronLasersStarting data taking and second test of JPL PD A1
  • Turned cryocooler off around 1317588441 (about 1:46PM)
  • Restarted measurement with output going to JPL_PD/data/A1_test3
  • Room is noticeably quieter without the cryocooler on.
Quote:
  • Output going to JPL_PD/data/A1_test2 and DAQ
  • Test commenced at 8:20AM and cryo cooler started shortly afterwards
  • Once trhough the loop takes about 20 minutes
  • Cryocooler on at 8:42AM

 

  2677   Thu Oct 7 08:07:03 2021 AidanSummary2micronLasersStarting data taking and second test of JPL PD A1
  • We're at 164K as of 8AM this morning.
  2678   Mon Oct 11 08:35:21 2021 AidanSummary2micronLasersStarting data taking and second test of JPL PD A1

Terminated the data taking at 8:35Am this morning. The termperature traces of the cryo chamber show a couple of discontinuities in the gradient. I don't know what the cause is,

Quote:
  • We're at 164K as of 8AM this morning.

 

Attachment 1: Screenshot_from_2021-10-11_08-36-06.png
Screenshot_from_2021-10-11_08-36-06.png
  2679   Mon Oct 18 15:25:14 2021 AidanSummary2micronLasersStarting data taking and second test of JPL PD A1

Initial running of analysis code puts the max QE at ~62 + /- 1% around 130-150K. I want to explore this temperature regime manually and see if we're saturating the PD or not.

3:30PM - Chamber is still under vacuum. Cryocooler turned back on.

Quote:

Terminated the data taking at 8:35Am this morning. The termperature traces of the cryo chamber show a couple of discontinuities in the gradient. I don't know what the cause is,

Quote:
  • We're at 164K as of 8AM this morning.

 

 

  2682   Thu Oct 21 17:48:33 2021 AidanLaser2um PhotodiodesImproved measurement of QE on photodiodes ~89% at 140K

Definitely. I think the lack of beam profiling/imaging equipment is something we want to address too. We will waste a lot of time in Mariner if we can't profile our beams.

Quote:

its worth looking into how fiber optic mode cleaning actually works:

https://doi.org/10.1201/9780203739662

In order to get a lot of cleaning you have to have a clean beam to begin with. There's a way to pre-clean by putting the laser output into a pinhole before coupling int othe single-mode fiber. Also, use a ~40-50m fiber to make sure the mod-mistanatched beam actually goes into the cladding rather than recombine into the Gaussian beam.

 

  2683   Fri Oct 22 09:20:13 2021 AidanLaser2um PhotodiodesImproved measurement of QE on photodiodes ~89% at 140K

Some of the data recorded during the current/micrometer scanning yesterday.

  • Distance between fiber/lens housings = Micrometer + 22.9mm
  • QE = Response / (1000Ohm*9.3E-4W/V) *(h*c/[e*L]) = Response * 0.667

Highlighted change to 25mA and also highest QE.

Time Temperature (K) Laser current (mA) Micrometer (mm) Peak Response (JPL/REF) QE
2:07PM 131.4 30 9.10 1.070 71.0%
2:14PM 133.5 30 9.10 1.090 73.0%
2:20PM 134.8 30 9.00 1.100 75.0%
2:25PM 136.4 30 8.80 1.134 75.6%
2:29PM 137.6 30 8.70 1.140 76.0%
2:31PM 138.1 30 8.60 1.120 74.7%
2:35PM 138.8 25 8.60 1.288 85.9%
2:42PM 140.5 25 8.80 1.246 83.1%
2:45PM   25 8.60 1.285 85.7%
2:249PM 142.2 25 8.40 1.310 87.4%
2:53PM 143 25 8.20 1.322 88.0%
3:01PM 144 25 8.00 1.328 88.6%
3:10PM   25 8.00 1.334 89.0%
3:14PM 147.5 25 7.80 1.314 87.6%
3:16PM 148.05 25 7.60 1.316 87.8%
3:19PM   25 8.00 1.328 88.6%
3:23PM 149.3 25 8.00 1.320 88.0%
3:30PM 151 25 8.00 1.315 87.7%
3:47PM 154 25 8.00 1.315 87.7%
4:02PM 157 25 8.00 1.300 86.7%
4:14PM 159.6 25 8.00 1.305 87.0%
  2686   Mon Oct 25 16:10:51 2021 AidanUpdateCDSRestarted computers and front-end model following campus power outage

Rebooted the workstations and FB4.

 Restarted the model on the FB4:

  • sudo /opt/rtcds/caltech/c4/target/c4iop/scripts/startupC4rt
  • sudo /opt/rtcds/caltech/c4/target/c4tst/scripts/startupC4rt
  2687   Mon Oct 25 16:13:47 2021 AidanUpdateCryo vacuum chamberHeater left on - chamber got warm

The cryocooler was switched off last Thursday to do testing on the JPL_PD. I turned the heater back on during this testing and neglected to turn it off when I finished at the end of the day. As a result, the workpiece reached ~400K over the weekend.

We are now allowing it to slowly cool down.

The CTC100 has a feature to specify an upper limit on temperature and then shut off the heater if that temperature is exceeded. We should engage this going forward.

Attachment 1: Screenshot_from_2021-10-25_16-19-39.png
Screenshot_from_2021-10-25_16-19-39.png
  2689   Tue Oct 26 07:32:52 2021 AidanUpdateCryo vacuum chamberHeater left on - chamber got warm

We're at 300K as of 7AM this morning.

Quote:

The cryocooler was switched off last Thursday to do testing on the JPL_PD. I turned the heater back on during this testing and neglected to turn it off when I finished at the end of the day. As a result, the workpiece reached ~400K over the weekend.

We are now allowing it to slowly cool down.

The CTC100 has a feature to specify an upper limit on temperature and then shut off the heater if that temperature is exceeded. We should engage this going forward.

 

  2690   Tue Oct 26 08:43:38 2021 AidanUpdateCryo vacuum chamberCTC100 temperature alarm and heater shutoff

Instructions on how to enable the alarm and heater shut off for the CTC100.

Status: This reports the status of the alarm. If LATCH is enabled, this must be manually set to OFF once it has been enabled.

Mode: Set to "Level"

Latch: Optional to set to "YES" if desired.

Output: Set to "Heater"

Max: Set to desired maximum temperature.

The attached photos show:

  • the menu where the settings are ALARM entered
  • the main display just before the alarm is enabled (at 300.350K with a 1s delay)
  • the main display just after the alarm is enabled - note that the Heater Output has been set to 0W.
Attachment 1: Screenshot_from_2021-10-26_08-42-57.png
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Attachment 2: IMG_5371.jpg
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  2692   Fri Nov 12 08:21:22 2021 AidanSummary2um PhotodiodesResults from JPL PD: A1-Test3

[Aidan]

Here is the analyzed data from Test 3 of the A1 JPL PD.

Note about the QE measurement: 

  • HOM beam QE was performed during the warm up phase. Collimating lens was fixed and beam pointing was optimized at 100mA before each measurement. Likely that not all power was on PD but that distribution was constant throughout measurement. Therefore, good proxy for shape of QE response.
  • Manual QE was performed with 25mA current, optimized collimating lens position (and thus the beam size on the PD). The data corresponds to 8.0mm between the lens mount and fiber mount. The beam pointing was optimized before each measurement at 25mA.
  • QE projection scales the "HOM beam QE" result to the manual QE measurements to project out expected QE performance vs temperature

Dark current is the output from the Keithley scan - the vertical scale is correct in Amps [ignore question mark]

Dark noise spectra are included for different bias levels and at different temperatures. Stll need to add ADC noise floor for these plots.

Notes from Test 3

~/JPL_PD/data/A1_test3/README

6-Oct-2021: done with cryocooler off and temperature increasing

PREAMP GAIN = 1E3

SR560 gain = 500

LD temp set point = 20.2kOhm

 

 

 

Attachment 1: A1_test3_nominal_QE.pdf
A1_test3_nominal_QE.pdf
Attachment 2: A1_test3_darkcurrent.pdf
A1_test3_darkcurrent.pdf
Attachment 3: A1_test3_noise_spectra_rev.pdf
A1_test3_noise_spectra_rev.pdf A1_test3_noise_spectra_rev.pdf A1_test3_noise_spectra_rev.pdf A1_test3_noise_spectra_rev.pdf A1_test3_noise_spectra_rev.pdf
  2739   Mon Mar 28 16:09:57 2022 AidanSafetyCleanlinessLab flooding

Some photos of affected areas in B265A and B265B (elog shows some preview photos - click on PDF for full set).

Stephen did a great job cleaning up and drying up. Most equipment is powered off and we're leaving it off for a couple of days to dry completely. We'll want to check the stuff on the red lab cart thoroughly. 

Quote:

When I went into QIL today there was a lot of flooding from water dripping from the ceiling at several places in the lab. Images attached.

 

Attachment 1: Flood_in_sub-basement-20220328.pdf
Flood_in_sub-basement-20220328.pdf Flood_in_sub-basement-20220328.pdf Flood_in_sub-basement-20220328.pdf Flood_in_sub-basement-20220328.pdf Flood_in_sub-basement-20220328.pdf Flood_in_sub-basement-20220328.pdf Flood_in_sub-basement-20220328.pdf Flood_in_sub-basement-20220328.pdf
  2741   Tue Mar 29 09:13:20 2022 AidanSafetyCleanlinessLab flooding

Facilities placed a blower and dehumidifier in B265B. I checked the airflow and the air around the tables is comparitively still. The North table is covered and the South table is over pressurized by HEPA filters, so there should be little risk of dust being stirred up.

Quote:

Flood photo album: https://photos.app.goo.gl/BZAG8DyQzFVTfMNz6 (This link is read-only who has no access to the account)

 

 

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  2766   Tue May 10 14:27:26 2022 AidanLab InfrastructureCleanlinessCeiling tile replacement - Day 1

Henry from the Carpentry Shop has started replacing ceiling tiles. They need to be cut to fit each location. There was a lot of set up getting equipment across to Bridge before lunch so not that much progress was made replacing tiles in QIL and TCS Labs. Expect work will speed up as we find our groove. 

Attachment 1: IMG_8782.jpg
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  2767   Wed May 11 15:53:06 2022 AidanLab InfrastructureCleanlinessCeiling tile replacement - Day 2

Tiles are replaced.

Quote:

Henry from the Carpentry Shop has started replacing ceiling tiles. They need to be cut to fit each location. There was a lot of set up getting equipment across to Bridge before lunch so not that much progress was made replacing tiles in QIL and TCS Labs. Expect work will speed up as we find our groove. 

 

Attachment 1: IMG_8806.jpg
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  2779   Mon Jun 6 14:05:08 2022 AidanElectronicsPurchasesReturn me to WB265B: Location of Thorlabs S130C (silicon photodiode 5mW/500mW settings)

[Aidan]

I bought a new photodiode for the West Bridge Labs. It will be housed in the QIL (WB265B) in the central cupboards. There is a QR code on it linking to this page. 

 

Attachment 1: S130C_calibration.pdf
S130C_calibration.pdf S130C_calibration.pdf S130C_calibration.pdf S130C_calibration.pdf
Attachment 2: IMG_9289.jpg
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  1445   Fri Jul 8 12:19:46 2011 ???Mystery contributor???LaserGYRONoise in temp measurement...

??....this looks like its all ADC noise.

How about a plot showing the spectrum of the ADC noise and the sensor noise and the measured temperature noise all on one plot with the y-axis in units of temperature (i.e. not cubits/sqrt(furlong))

 

  939   Mon Aug 16 18:56:28 2010 1954 B-movieLab InfrastructureANTS!How do we get rid of ants?

ANTS!

Quote:

Quote:

It's that time of year again in Pasadena and the ants are going a bit crazy.  There are about 10 on the floor in the ATF, and no doubt there will soon be about 1e6 of them.  Do we have a standard ant removal scheme for cleanrooms?  The stuff I use at home is a spray and probably not very nice for optics.  We could use some of the slightly illegal ant chalk I guess.

 Steve has the cleanroom janitor mop the 40m floor in the LVEA/IFO room with diluted ant poison.

 

  288   Thu Aug 27 21:40:20 2009 (not) AlastairLab Infrastructurestuff happensLenses

Quote:

I ordered some lenses for the lens kit.

 What focal lengths/coatings

  504   Fri Dec 18 13:27:12 2009 DmassLaserDoublingConfusion Abounds ^3

Quote:

What's confusing? It looks fine. Should take the TF of the DC and AC signals and compare that with the expected TF of the electronics.

** also, lower case names for channels are illegal. I suggest naming the PDs with what wavelength they have as well, e.g.   PD_1064_1_DC, PD_532_2_AC, etc.

 

Here are the spectra and transfer functions for all four channels. If the DC channel is really just DC (and is not loaded by the AC coupling circuit), then I would expect this to just reproduce the high pass filter itself.

  • I put a white noise source into the ADC
  • I piped this signal to five output channels of the DAC (DIODE_34_CUR_OUT_DAQ, DIODE_12_CUR_OUT_DAQ, NPRO_CUR_OUT_DAQ, NPRO_PZT_OUT_DAQ recorded)
  • I put four of these outputs to the input of my AC Couple circuit
  • I put the other DAC output to the input of my ADC
  • I measured the transfer function between the input of my noise and the signals i am sending from the DAC to the AC coupler
  • I took the transfer function of the spare ADC channel and the eigth outputs of my AC coupler as recorded by the DAQ
  • I noticed funniness (below).

I really don't understand what's going on with the differences I see in my filters. This may have to wait until I get back from Xmas vacation unless someone knows the answer immediately.

For later reference: This setup is recorded in the DAQ from 1:28:00 PST - 1:40:00 PST on Fri Dec 8th

Attachment 1: MZACCoupTFALL.pdf
MZACCoupTFALL.pdf
  505   Fri Dec 18 15:42:22 2009 DmassLaserDoublingConfusion Abounds ^3

Quote:

Quote:

What's confusing? It looks fine. Should take the TF of the DC and AC signals and compare that with the expected TF of the electronics.

** also, lower case names for channels are illegal. I suggest naming the PDs with what wavelength they have as well, e.g.   PD_1064_1_DC, PD_532_2_AC, etc.

 

Here are the spectra and transfer functions for all four channels. If the DC channel is really just DC (and is not loaded by the AC coupling circuit), then I would expect this to just reproduce the high pass filter itself.

  • I put a white noise source into the ADC
  • I piped this signal to five output channels of the DAC (DIODE_34_CUR_OUT_DAQ, DIODE_12_CUR_OUT_DAQ, NPRO_CUR_OUT_DAQ, NPRO_PZT_OUT_DAQ recorded)
  • I put four of these outputs to the input of my AC Couple circuit
  • I put the other DAC output to the input of my ADC
  • I measured the transfer function between the input of my noise and the signals i am sending from the DAC to the AC coupler
  • I took the transfer function of the spare ADC channel and the eigth outputs of my AC coupler as recorded by the DAQ
  • I noticed funniness (below).

I really don't understand what's going on with the differences I see in my filters. This may have to wait until I get back from Xmas vacation unless someone knows the answer immediately.

For later reference: This setup is recorded in the DAQ from 1:28:00 PST - 1:40:00 PST on Fri Dec 8th

 

I also swapped the cables going in to my AC Coupler at Rob's suggestion and had the same channels misbehaving.

 

  11   Wed Nov 28 16:20:04 2007 Andrey Lab InfrastructureGeneralEnclosure cleaning
Previous Tuesday, Nov. 20, I tried to wipe the curtain plastic enclosure around the optical table with the laser using methanol. It turned out, though, that methanol damages the surface of the enclosure, dissolving it and leaving lines/ traces. I stopped my activities with methanol after I realized that negative effect on three corner strips of enclosure.

Lesson for everyone: NEVER USE METHANOL FOR THOSE CURTAINS!

I tried 25% solution of isopropil alcohol in water on Wednesday, Nov. 21, and such mixture did not have any bad effect on the surface of the enclosure. I wiped the curtains, so they should be clean of dust now.

Andrey.
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