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ID Date Author Typeup Category Subject
  2103   Thu May 18 12:46:08 2017 awadeLaserWOPOInitial testing Innolight Diabolo

We are planning on using the Innolight Diabolo (given to us by Ron Drever's lab several years ago) as a source of 532 nm and 1064 nm photons for the WOPO experiment.  The status of the Diabolo is not known so I'm doing some checks.

This the 2004 edition of the Diabolo so the datasheet is difficult to find online.  I've scaned the manual + test sheets and put on the ATF wiki HERE.

---

The Diabolo unit consists of a regular 1.5 W Nd:YAG NPRO laser (pumped with two banks of diode lasers) with most of this light tapped off to an SHG unit for conversion to 532 nm.  The SHG is a hemolytic Fabry-Perot cavity made with a Lithium Niobate crystal. One end of the crystal acts as an HR/AR mirror in 1064/532 nm and the other is a HR/HR curved mirror that is mounted on a PZT.  Inside the Diabolo unit there is a EOM, MM lenses, alignment mirrors and RF+DC transmission diode to generate a PDH signal for locking.  All of the locking and cavity scanning is automatically handled by the SHG control electronics.  Details of operation are in the manual.  There is a laser control box and a separate SHG control box.  The SHG control box provides feedback control for the temperature of the crystal (nominally ~100-101 C for unpolled LiNb) and all of the modulation and demodulation electronics for PDH control. 

Initial settings on the laser, as I found it, were

Laser diode A temp = 19.69 C
Laser diode B temp = 20.39 C
Injection current  = 0 A (i.e. ramped down to off)
Laser crystal temp  = 23.42 C
 

SHG unit settings were

Double crystal temp = 102.87 C
Offset = 5.09
Gain  = 0.4
Scan amplitude  = 0 (you turn this up to scan SHG cavity)

The range of the doubling crystal temp was 102.87 C to ~ 110 C.  This seems too high for phase matching of the LN.  There is no obvious way to make a course adjustment.  Other units I've worked with (at ANU) gave a much bigger range of adjustment on SHG crystal temp centered around 100 C. We need to check the refractive indexes of LiNb for 1064 nm/532 nm as a function of temp and work out what the expect phase matching temperature is.  It might be that the temperature sensor has some kind of placement that doesn't reflect the bulk LiNb bulk temperature and the higher course offset compensates for this.  It might be worth tuning around more of the temperature space to get an idea of idea phase matching.

---

I made a few adjustments to settings on laser to bring them back to the testsheet values in the manual:
Laser diode A temp = 21.3 C
Laser diode B temp = 26.75 C
Injection current  = 2.2 A (max)
Laser crystal temp  = 23.42 C

The typical operating current was 2.4 A, but the current clamp value on the current has been reduced down to 2.2 A, this will mean a slightly lower nominal operating power.

With maximum allowable diode current (2.2 A) the output of the laser was 303 mW @ 532 nm and 302.3 mW @ 1064 nm. This was measure with a Thorlabs S302C thermal power sensor. Nominal output should be 910 mW @ 532 nm and  380 mW @ 1064 nm.  So 1064 nm is 80% of spec (expected with slightly lower current).  But the SHG 532 nm output is 33% of spec (well below).

---

As a check, I hooked up and oscilloscope to the monitor ports on the Diabolo SHG controller.  An attached plot shows a ramp of the PZT actuation signal and the 1064 nm power on transmission (measure using unit's built in PD).  Clearly there is a misalignment into the cavity, there are a bunch of HOM peaks that represent a heap of wasted light.  To fix this I need to open the Diabolo up and tweak the alignment into the SHG sub-unit.  Its not very involved but because the Eigen mode of the cavity comes to a ~25 µm waist it is highly sensitive.  Need to tweak and allow some settling time for mounts to relax. 

Attachment 1: SHGLenthScan_TransmissionAndPZTSig.pdf
SHGLenthScan_TransmissionAndPZTSig.pdf
  2104   Sun May 21 21:11:43 2017 awadeLaserWOPOInitial testing Innolight Diabolo

Koji gave me another copy of the Diabolo manual.  The test sheets and specs stapled to the inside are different from the version previously posted in ATF:2103.  These match up better with the limits of the Diabolo unit I actually have in the ATF lab. I've scanned and put it on the ATF wiki as 'copy B'

LINK TO MANUAL + TESTSHEETS (COPY B)

  2112   Thu May 25 16:28:21 2017 DhruvaLaserWOPOInitial testing Innolight Diabolo

 

Quote:

We are planning on using the Innolight Diabolo (given to us by Ron Drever's lab several years ago) as a source of 532 nm and 1064 nm photons for the WOPO experiment.  The status of the Diabolo is not known so I'm doing some checks.

This the 2004 edition of the Diabolo so the datasheet is difficult to find online.  I've scaned the manual + test sheets and put on the ATF wiki HERE.

 

I am attaching a schematic of the Diabolo laser and a bit of the experimental setup outside the laser. 

The beam waist of the 532nm laser is around 25 microns and is expected to expand to about 565 microns in about 10cm where we expect to place the faraday isolator.  Assuming a 900mW beam as written in the data sheet, the intensity of the beam at the Faraday isolator (10cm) is around 89.65W/cm^2. 

Attachment 1: Diabolo_for_WOPO.pdf
Diabolo_for_WOPO.pdf
  2113   Fri May 26 18:29:59 2017 DhruvaLaserWOPOBeam Profiling of Diabolo's 1064nm laser
Today, Andrew and I attempted to profile the Diabolo Laser's 1064 beam using the DataRay Scanning Slit Profiler. These are the results for the x and y spot size vs axial distance measurements. We used two single surface coated laser windows( W1-PW1-1025-UV-1064-0) to attenuate the beam down to 3mW. I have attached two images of the beam profiling setup, having indicated the z=0 reference on one of them.
 
 
 
z(cm) w_x(microns) w_y(microns)
0 1972 1882
2.54 1976 1928
5.08 2004 1988
7.62 2113 2050
10.16 2124 2097
12.7 2135 2137
15.24 2177 2194
17.78 2218 2246
20.32 2226 2288
22.86 2254 2322
25.4 2284 2370
27.94 2328 2413
30.48 2354 2438
33.02 2366 2478
35.56 2405 2512
38.1 2453 2571
40.64 2498 2591
The z = 0
 
On attempting to fit this data, I got these results for the beam waist size and waist location
 
x : 262micron waist at z =-1.5m
 
y : 192micron waist at z = -1.08m
 
Now there is obviously something wrong with this as the beam waist location is behind the laser and there's a 50cm difference between the x and y waists. 
Attachment 1: 1064_WOPO_1.jpg
1064_WOPO_1.jpg
Attachment 2: 1064_WOPO_2.jpg
1064_WOPO_2.jpg
Attachment 3: 1064_profile.pdf
1064_profile.pdf 1064_profile.pdf
  2116   Fri Jun 2 15:16:00 2017 DhruvaLaserWOPOInitial testing Innolight Diabolo

 

Quote:

I am attaching a schematic of the Diabolo laser and a bit of the experimental setup outside the laser. 

Following Rana's advice, I installed Inkscape today and remade the diagram. Except for the beam dump, nothing is 100% opaque and all fonts are Helvetica Neue/

 

Attachment 1: Diabolo.pdf
Diabolo.pdf
  2120   Mon Jun 12 17:18:19 2017 DhruvaLaserWOPOBeam Profiling of Diabolo's 532nm laser
 
Using the same setup as before, I profiled the 532nm beam of the Diabolo Laser 
 
 
 
z (cm) w_x(microns) w_y(microns)
2.54 1034 1099
5.08 1154 1226
7.62 1259 1341
10.16 1350 1428
12.7 1454 1548
15.24 1570 1685
17.78 1672 1789
20.32 1758 1887
22.86 1800 1961
25.4 1891 2052
27.94 1951 2088
30.48 2077 2187
33.02 2192 2272
35.56 2244 2358
38.1 2344 2420
40.64 2417 2500
43.18 2470 2542
 
 
The results look more reasonable than those obtained for the 1064nm profiling (60.5(x) and 56.6(y) microns approxiamately 31 centimetres behind z=0)
Attachment 1: profile.pdf
profile.pdf profile.pdf
  2121   Tue Jun 13 16:45:38 2017 DhruvaLaserWOPODiabolo Profiling

I reprofiled the 1064 beam today. I also found that the DataRay software gives me the beam diameter and not the spot size. So I adjusted the fit of the 532 beam too.

Attachment 1: 532_profile.pdf
532_profile.pdf
Attachment 2: 1064_profile.pdf
1064_profile.pdf
  2123   Thu Jun 22 16:45:17 2017 DhruvaLaserWOPOAdvR Waveguide Spec Sheet

Here is the spec sheet for the squeezing waveguide

Please, don't place proprietary documents on public web pages (=ELOGs).
Instead, place them on secured wikis and place only links to the
elogs. Thanks (Koji)

 

Edit - 

I have put the spec sheet on the ATF wiki. Here's the link - 

https://nodus.ligo.caltech.edu:30889/ATFWiki/lib/exe/fetch.php?media=main:experiments:wopo:advr.pdf

  2378   Mon Jul 29 15:46:50 2019 KojiLaser2micronLasersOptical Phase noise of 2 um Mach Zehnder Interferometer.

Great! Can you convert this into the laser frequency noise Hz/rtHz? I believe this [rad/rtHz] was still the measured phase noise and was neither the laser phase noise nor frequency noise yet.

  2421   Tue Sep 17 23:42:41 2019 Shalika SinghLaserPD QEMeasuring Quantum Efficiency of Extended InGaAs Photodiode

**[Internal Quantum Efficiency added]

[Koji, Shalika]

Further measurements were done after elog:2419 for Quantum Efficiency of Extended InGaAs Photodiodes(X8906). A Laser of wavelength 2um was used with an incident power of 0.80+0.02mW.  The Ophir RM9 power meter was used to check the incident power and also measure the reflectivity.

Attachment 1: The Setup. A Fibre launcher was used to project the laser along with a converging lens of the focal length of 40.0 mm which was further arranged with a subsequent converging lens of  150mm focal length. A mirror was used to reflect the laser light on the photodiode at an angle of 45o. The bias voltage was provided to pin 4 of photodiode using a Sallen Key low pass filter and the output at pin 3 of the photodiode was fed to a transimpedance amplifier (with a gain of 5.1k) which converted the photocurrent to voltage.

Attachment 2: The Quantum Efficiency is plotted with respect to different bias voltages, It was observed that the quantum efficiency increases with an increase in bias voltage. An External Quantum Efficiency of 77.4% was observed at 1V(maximum bias voltage for the photodiode). The Internal Q.E was observed to be 83.8% taking into account Reflectivity of (60.0+1) uW at an angle of 17deg. 

Attachment 3: To recreate all data

Attachment 1: IMG_8915.JPG
IMG_8915.JPG
Attachment 2: QE_X8906.pdf
QE_X8906.pdf
Attachment 3: Extended_InGaAs.zip
  2438   Thu Oct 31 18:31:10 2019 KojiLaserPD QEPD EQE vs Spot size

InAsSb PD QE Test

The relationship between the spot radius and the apparent QE (EQE) was measured.

1) The spot size was checked with DataRay Beam'R2. The beam scanner was mounted on the post with a micrometer stage in the longitudinal direction. (Attachment1 upper plot)
It was confirmed that the beam is focused down to ~22um. The incident power was about 0.9mW.

2) The InAsSb detector (Sb3513A2) was mounted on the PD holder and then mounted on the stage+post. The photocurrent was amplified by a FEMTO's transimpedance amp (V/A=1e3Ohm). The dark current and the total photocurrent were measured at each measurement point with the beam aligned to the PD every time. The estimated EQEs were plotted in the lower plot of the attachment.

Note that P2, P3, and P6 elements have the size of (500um)^2, (750um)^2, and (1000um)^2, respectively.

The absolute longitudinal position of the sensor was of course slightly different from the position of the beam scanner. So the horizontal axis of the plots was arbitrary adjuted based on the symmetry.

The remarkable feature is that the QE goes down with small spot size. This is suggesting a nonlinear loss mechanism such as recombination loss when the carrier density is high.

With the present incident power, the beam size of 100um is optimal for all the element sizes. For the larger elements, a bigger beam size seems still fine.

The next step is to estimate the clipping loss and the saturation threshold with the Gaussian beam model.

Attachment 1: QE_vs_spotsize.pdf
QE_vs_spotsize.pdf
  2439   Fri Nov 1 12:47:18 2019 KojiLaserPD QEPD EQE vs Spot size

Clipping and saturation were investigated by the semi-analytical model. In the analysis, the waist radius of 20um at the micrometer position of 8mm is used.

1) Clipping

Firstly, the clipping loss was just geometrically calculated. Here the saturation issue was completely ignored. The elements P6, P3, and P2 have the sizes of (500um)^2, (750um)^2m, and (1000um)^2, respectively. However, these numbers could not explain the clipping loss observed at the large spot sizes. Instead, empirically the effective sizes of (350um)^2, (610um)^2, and (860um)^2 were given to match the measurement and the calculation. This is equivalent to have 70um of an insensitive band at each edge of an element (Attachment 1). These effective element sizes are used for the calculation throughout this elog entry.

2) Saturation modeling

To incorporate the saturation effect, set a threshold power density. i.e. When the power density exceeds the threshold, the power density is truncated to this threshold. (Hard saturation)

Resulting loss was estimated using numerical integration using Mathematica. When the threshold power density was set to be 0.85W/mm^2, the drop of QE was approximately matched at the waist (Attachment 2). However, this did not explain the observed much-earlier saturation at the lower density. This suggests that the saturation is not such hard.

In order to estimate the threshold power density, look at the beam size where the first saturation starts. The earlier sagging of the QE was represented by the threshold density of 0.1W/mm^2. (Attachment 3)

Attachment 1: QE_vs_spotsize_no_saturation.pdf
QE_vs_spotsize_no_saturation.pdf
Attachment 2: QE_vs_spotsize_saturation_0_85.pdf
QE_vs_spotsize_saturation_0_85.pdf
Attachment 3: QE_vs_spotsize_saturation_0_1.pdf
QE_vs_spotsize_saturation_0_1.pdf
  2443   Tue Nov 12 03:40:39 2019 KojiLaserPD QEPD EQE vs Spot size

The QE of the (500um)^2 element has been tested with a half-power (0.51mW) instead of 0.92mW.
It is clear that the central dip depth is reduced by the lower power density.

 

Attachment 1: QE_vs_spotsize_half_power.pdf
QE_vs_spotsize_half_power.pdf
  2474   Tue Dec 10 16:35:03 2019 AidanLaser2micronLasersCalibrated cryo-PD REF PD output in units of power incident on cryo chamber window

We placed a power meter after the fiber collimator, 75mm focal length lens and HR mirror at 45 degrees - basically, we placed the power meter immediately before the input window to the cryo chamber after all the intervening optics from the fiber output.

For a series of laser diode current levels, we measured the power on the power meter and the corresponding voltage on the reference photodetector that is monitoring a 10% pick-off from the laser. The calibration is as follows:

Diode current (mA) REF PD (V) Laser Power (mW)
100.83 1.048 1.171
90.75 0.941 1.043
80.66 0.827 0.904
70.56 0.708 0.763
60.47 0.596 0.627
50.45 0.48 0.485
39.92 0.357 0.338
29.82 0.237 0.191
19.73 0.117 0.045
9.64 0.080 0.000
0.00 0.080 0.000

 

  2635   Thu Aug 5 09:20:44 2021 AidanLaser2um PhotodiodesOptical design for 2um PD in new cryo chamber

I've sketched out a way to change the beam size on the in-vacuum PD. I think the beam diameter coming from the collimator is 1.2mm, but I need to check this. If we add a telescope outside the vacuum system and put the second lens of this on a translation stage, then this provides us with wide control of the beam size on the PD inside the vacuum system (about 400mm away).

 

 

 

Attachment 1: Cryo_Chamber_optical_layout.pdf
Cryo_Chamber_optical_layout.pdf
  2637   Thu Aug 5 12:39:56 2021 AidanLaser2um PhotodiodesOptical design for 2um PD in new cryo chamber

Here's a more detailed layout of the in-air design for the PD testing. Things to note:

  1. I've changed the telescope to a ~1:2 beam expander using a 40mm lens and a 75mm lens. This allows for greater tuning of the beam size on the PD
  2. I added the picomotor mirror for fine-tuning of the beam steering onto the PD (I have to check how much control this translates to on the PD inside the vacuum system).
  3. The picomotor mirror is open loop, so there is a QPD to monitor the actual pointing of the mirror
Quote:

I've sketched out a way to change the beam size on the in-vacuum PD. I think the beam diameter coming from the collimator is 1.2mm, but I need to check this. If we add a telescope outside the vacuum system and put the second lens of this on a translation stage, then this provides us with wide control of the beam size on the PD inside the vacuum system (about 400mm away).

 

 

 

 

Attachment 1: Cryo_in-air_setup.pdf
Cryo_in-air_setup.pdf
  2639   Thu Aug 5 14:29:42 2021 StephenLaser2um PhotodiodesOptical design for 2um PD in new cryo chamber

Actions on my to-do list, once we are warm and up to air, before Aidan and I are able to run the JPL PD test. This list complements the optical setup tasks and data acquisition setup tasks that are also mentioned by Aidan in this thread.

Update 23 August - using this list to [comment on details] and highlight items which are still outstanding instead of duplicating in a daily progress log entry :)

0. Remove Aaron and Shruti’s Si cantilever clamp, and return to them for safekeeping [I set the clamp aside, need to coordinate return of cantilever to with Aaron!]
1. Solder a connector equivalent to the testpiece (ref. QIL/2465) but with the cryo wire, In-Ag solder on the connector end, and crimped plug pins on the free end. The crimped plug pins interface the with receptacle pins of the existing leads, which are connected to in-vac side of DB9 feedthrough).
 - need to locate some In-Ag solder! [done, and checked connectivity - used standard lead-tin solder following Rana's recommendation (ref. QIL/2418) born out by Koji's testing (ref. QIL/2462 and QIL/2465)]
2. Confirm which PD holder will be most useful for this effort (Koji’s newly machined holders might be useful?) and mount to cold baseplate. If using the tombstone from the IRLabs dewar, which is likely shorter than the beam height, it sounds like we would need to mount it on a pedestal or post. [Aidan used Koji's taller PD mount from the same purchase (ref. QIL/2459). The beam height required no modification, nice!]
3. Mount RTD to PD holder, likely with cryovarnish (unless there is a lucky extra hole for a screw/clamping post). [Radhika and Aidan's G2100807 demo shows the problem with the prior lug, not super stable mounting for the RTD as the same hole is being used to host two screws. Instead, I retrofitted the upper screw from the mount's retaining ring to host one of the trusty spring clamps, see Attachment 1. I checked for clipping or connector interference throughout, and found none.]
4. Mount heater to ___ (TBD, ideally on PD holder but possibly on cold baseplate nearby). [dog-clamped the heater to the baseplate, directly adjacent to the mount - see overview images in Attachment 2 and Attachment 3. We may go through some PID growing pains with this configuration, and we also need to learn whether the 22 W heater power locally applied can overcome the cryocooler's  ~50 W cooling power at our operating temperatures (ref. Radhika's QIL/2585). Might be necessary to intermittently power cycle the cryocooler.]
5. Confirm alignment of shields and PD. [aligned both shields, clamped inner shield, but could reposition if there is an issue.]
6. Verify electrical continuity of PD cable, RTDs, and heater. [note need to add indium and finalize clamping of PD holder, also note routing of pins to be connected to PD connector per Koji's QIL/2605 as described in Attachment 3]
7. Close up (shield lids, chamber lid). [note that in particular, the covering up (with foil sheets) of unused shield apertures is still WIP but wasn't originally mentioned!]
8. (anytime, optional) complete RTD and Heater disconnection junctions with in-vac crimped pins. [done, with mounting isolation achieved by kapton tape as ptfe tubing has not yet arrived. Attachment 4 shows one example, from the inner shield.]
 - crimped plug pins were in 40m lab parts tower, but didn’t see any receptacle pins in the vicinity. [ordered a few hundred new socket pins, I should share some with the 40m parts tower]

Pending Aaron and Shruti’s measurements, it is likely that heater-assisted warmup will occur starting Tuesday, in time for Wednesday/Thursday access. Friday 13th August could be the start of the cool down if everything goes to plan. [Nothing goes well on Friday the 13th. Aaron and Shruti do not need in-vacuum measurements anytime soon. The current plan is for cooldown to begin Tuesday and, if everything goes to plan, we will collect data through the week, then likely swap out the PDs on Monday for another run next week. The next experiment slated for the QIL Vacuum Cryostat is another Si mass radiative cooling run w/ black paint on inner surfaces of inner shield.]
 

Attachment 1: IMG_9685.JPG
IMG_9685.JPG
Attachment 2: IMG_9687.JPG
IMG_9687.JPG
Attachment 3: routing_markup_of_IMG_9688.png
routing_markup_of_IMG_9688.png
Attachment 4: IMG_9682.JPG
IMG_9682.JPG
  2650   Tue Aug 24 15:01:25 2021 StephenLaser2um Photodiodes2um PD in new cryo chamber

[Aidan, Stephen]

Worked toward aligning and characterizing beam on PD. Will complete next session.

Log:

Some difficulty aligning to the 2um beam, which is sensed by a thermal card. Aidan intends to upgrade with a fiber coupled visible laser, which could then be swapped interchangably for alignment.

The 1" mirror at the top of the periscope doesn't make sense, given larger apertures in shields and viewport. We looked for a nearby 2" replacement but did not have luck. Ended up swapping back in the gold-coated 2" mirror, even though it is thin enough to be a pain to mount.

Instrumented connector pins to DB9 pins using the following translation (ref Aidan's drawing for connector / PD pinout, ref drawing from QIL/2639)

            DB9   - 1 6 2 7 3 8 

    Connector - 2 3 4 5 6 7

 

  2651   Thu Aug 26 14:31:46 2021 Aidan, StephenLaser2um PhotodiodesIncident power calibration of 2um PD in new cryo chamber

We're getting close to running this (2um beam is focussed onto the PD and we have piezo mirror steering and beam size tuning). However, all DAC channels are currently non-responsive. I'm going to rebooting the front-end.

Incident power calibration was performed with a S148C power meter head placed directly in front of the PD. For varying current levels, I recorded the pick-off PD voltage and the power meter reading.

Current (mA) REF PD (V) Power Meter (mW)
101.04 1.01 0.803
101.03 1.012 0.805
100.41 1.01 0.805
93.11 0.935 0.735
85.03 0.846 0.664
79.97 0.792 0.618
75.01 0.74 0.573
69.97 0.684 0.524
65 0.629 0.478
55.01 0.52 0.384
44.96 0.405 0.284
35 0.291 0.1834
25 0.176 0.0844
20 0.119 0.0348
0.03 0.079 3.00E-04

POW [mW] = 0.862[mW/V]*REF_PD [V] -0.067[mW]

Quote:

[Aidan, Stephen]

Worked toward aligning and characterizing beam on PD. Will complete next session.

Log:

Some difficulty aligning to the 2um beam, which is sensed by a thermal card. Aidan intends to upgrade with a fiber coupled visible laser, which could then be swapped interchangably for alignment.

The 1" mirror at the top of the periscope doesn't make sense, given larger apertures in shields and viewport. We looked for a nearby 2" replacement but did not have luck. Ended up swapping back in the gold-coated 2" mirror, even though it is thin enough to be a pain to mount.

Instrumented connector pins to DB9 pins using the following translation (ref Aidan's drawing for connector / PD pinout, ref drawing from QIL/2639)

            DB9   - 1 6 2 7 3 8 

    Connector - 2 3 4 5 6 7

 

 

Attachment 1: IMG_4420.jpg
IMG_4420.jpg
Attachment 2: REF_PD_POW_CAL_cryo.pdf
REF_PD_POW_CAL_cryo.pdf
  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 ...
  2680   Thu Oct 21 15:32:32 2021 Aidan, RadhikaLaser2um PhotodiodesImproved measurement of QE on photodiodes ~89% at 140K

[Aidan, Radhika]

We turned off the heater and the cryocooler this morning to around 11:30AM when the temperature of the diode was around 123K and are letting it gradually warm up.

Through the next 30K, we experimented with different distances between the fiber output and the collimating lens. Bias voltage always set to 1000mV. Laser diode current was set manually on the controller (the input from the DAC was unplugged as this is a little noisy). 

  1. We increased the distance between collimator and the lens by 1.4mm (from stage reading of 9.41mm to 10.8mm) and there was a small increase in the response (PD output/REF PD output)
  2. For each new setting, we set the laser diode current to 100mA and run the maximize script on the piezo mirror, adjusting the alignment to maximize the output power.
  3. We then stepped up the laser diode current in steps of 10mA from 25mA to 95mA and one last measurement at 101mA. The PD response dropped by 30-40% through this range.

It looked like the optimum translation stage setting was 9.75mm - however, i discovered something very interesting ...

If you run the maximize power script at 100mA to the laser diode, then drop the laser current to 30mA and rerun the script, you find that there is a different optimum alignment. This means that the output beam shape/pointing is power dependent. In other words, the output of the fiber is not properly mode-cleaned by the 2m patch cord we have.

Switching to 25mA, I optimized the alignment and continued exploring the optimum translation stage position. Dropping the stage position to 8.0mm maximized the response (at 25mA). Note that the code maximizes an EPICS channel called C4:TST-PD_RESPONSE which is (JPL_PD - DarkV)/REFPD. The reference PD filter bank has an offset applied so OUT16 has a mean value of zero when the laser is off. DarkV for the JPL PD is the PD voltage when the laser is off and this was manually updated every 5-10 minutes or so. C4:TST_PD_RESPONSE is not stored but the JPL_PD and REFPD channels are stored in frames.

On 27-Sept, I measured the ratio of power incident on the JPL PD to the voltage output from the REF PD: dP/dV = 9.3E-4 W/V. The JPL PD DC photocurrent sees a transimpedance gain of 1000Ohm. Therefore, QE is calculated using the following formula:

QE = (RESPONSE)*(1E-3/9.3E-4)*  h*c/(e*lambda) = RESPONSE*0.667

Using this calculation and a peak response value of 1.334 at about 145K, the peak QE was estimated to be about 89%. An error analysis is needed on this. And we need to figure out how to get a better output beam shape from the optical fiber (use a really long fiber?)

Note that the translation stage reading of 8.0mm corresponds to a fiber holder to lens mount distance of 30.9mm

 

Attachment 1: IMG_5305.jpg
IMG_5305.jpg
  2681   Thu Oct 21 16:52:26 2021 ranaLaser2um PhotodiodesImproved measurement of QE on photodiodes ~89% at 140K

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.

  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%
  2684   Fri Oct 22 12:04:13 2021 ranaLaser2um PhotodiodesImproved measurement of QE on photodiodes ~89% at 140K

agreed. You should put into Voyager chat and cryo/ET slack questins about 2 um beam profiling. We'll want it for anything 1.8-2.1 um.

Quote:

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.

  2685   Fri Oct 22 13:31:36 2021 ChrisLaser2um PhotodiodesImproved measurement of QE on photodiodes ~89% at 140K

Somewhere around the labs there should be a DataRay Beam'R2 scanning slit profiler, with an extended InGaAs detector that works out to 2.5 µm.

Quote:

agreed. You should put into Voyager chat and cryo/ET slack questins about 2 um beam profiling. We'll want it for anything 1.8-2.1 um.

Quote:

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.

 

  3   Mon Oct 22 20:04:28 2007 ranaMiscGeneralMagnetic Levitation
Links

Wikipedia article

Virgo Magnetic Suspension Idea from Monica

A paper by Giazotto on electrostatic mirrors is attached here.

And a document from Ron Drever on his magnetic levitation scheme:
here

Fender produces electric guitar pickups using Samarium Cobalt Noiseless (SCN) pickups.
Attachment 1: Giazotto-ESmirror.pdf
Giazotto-ESmirror.pdf Giazotto-ESmirror.pdf Giazotto-ESmirror.pdf Giazotto-ESmirror.pdf Giazotto-ESmirror.pdf Giazotto-ESmirror.pdf
  104   Thu Jan 8 19:59:50 2009 AidanMiscGeneralEarthquake ...

Just felt the building shake. Didn't feel as a large as last year's quake.

Apparently a 5.0 in San Bernadino ...
  142   Thu Jun 25 10:44:46 2009 MichelleMiscGeneralWeekly Summary 1

Over the course of the first week here I've done several things. The first thing we're going to try to do in the lab (once we have all our parts in) is lock a simple cavity using Pound-Drever-Hall. I've been reading some of the literature on that and familiarized myself with that technique. Through these readings, I've come across various terms and equipment used in optical setups that I was unfamiliar with, so I've become acquainted with those. I attended the laser safety training meeting and have started to find my way around the lab. Connor and I also began characterization of the Nd-YAG laser. While I will not be working with that one, I will have to do the same thing for the one I will be working with. We first made some measurements of its output power versus the drive current, and results from that can be found in an entry to the eLog on 6-23-09. Today we are going to use the BeamScan to figure out the divergence of the laser.

Various other things that I've done over the past week include learning how to work with Matlab and Linux (both of which I am relatively unfamiliar with), and attending talks about the LIGO project by Dr. Weinstein.

  145   Wed Jul 1 15:34:26 2009 Connor MooneyMiscFiberWeekly Report
Most of this week was spent on three tasks: characterizing the beam divergence of the NPRO Laser and fitting a curve to the data, the progress report, and contending with serious computer problems. The information on the beam divergence can be accessed in a previous log. The waist size is around 120 micrometers, and according to a least-squares fit, it is located 21cm behind the aperture. My understanding of the fiber suppression setup and its relationship to the second-harmonic generation system was strengthened, but nowhere near completed, in the process of writing the progress report. We plan to send the NPRO beam through an AOM driven at f1, then double-pass it through a 50m fiber (not to be bent at a 90 degree angle as drawn in the meeting today) and another AOM driven at f2. This signal will be interferometrically mixed with the original beam from the NPRO, producing beats at 2(f2-f1), then run through a multiplying mixer driven at 2(f1-f2) and a low-pass filter so the final signal consists mostly of the noise acquired when travelling through the fiber. A computer characterizes this noise, and sends a signal to the first AOM which actuates on the original beam so as to suppress the noise. ********************NOTE: Aidan plans on changing the setup slightly, and I'll give the details on that in the next report************************* Finally, my computer acquired a terrible virus yesterday morning when I clicked on an innocuous-looking facebook message that was sent to my email and titled "hi." All of yesterday and the first part of today was spent rebuilding the computer. Don't trust facebook. I now have a centos operating system, so I'll be learning to use Linux fast (hopefully).
  146   Wed Jul 1 16:37:33 2009 Connor MooneyMiscFiberWeekly Report

Quote:
Most of this week was spent on three tasks: characterizing the beam divergence of the NPRO Laser and fitting a curve to the data, the progress report, and contending with serious computer problems. The information on the beam divergence can be accessed in a previous log. The waist size is around 120 micrometers, and according to a least-squares fit, it is located 21cm behind the aperture. My understanding of the fiber suppression setup and its relationship to the second-harmonic generation system was strengthened, but nowhere near completed, in the process of writing the progress report. We plan to send the NPRO beam through an AOM driven at f1, then double-pass it through a 50m fiber (not to be bent at a 90 degree angle as drawn in the meeting today) and another AOM driven at f2. This signal will be interferometrically mixed with the original beam from the NPRO, producing beats at 2(f2-f1), then run through a multiplying mixer driven at 2(f1-f2) and a low-pass filter so the final signal consists mostly of the noise acquired when travelling through the fiber. A computer characterizes this noise, and sends a signal to the first AOM which actuates on the original beam so as to suppress the noise. ********************NOTE: Aidan plans on changing the setup slightly, and I'll give the details on that in the next report************************* Finally, my computer acquired a terrible virus yesterday morning when I clicked on an innocuous-looking facebook message that was sent to my email and titled "hi." All of yesterday and the first part of today was spent rebuilding the computer. Don't trust facebook. I now have a centos operating system, so I'll be learning to use Linux fast (hopefully).

 FORMAT PLEASE!

  147   Wed Jul 1 17:06:30 2009 MStephensMiscGeneralNew Gyro Design and Week 2 Summary

I've done a few things this week. Connor and I characterized his laser's beam divergence, the results of which can be found on a previous entry. I'll do the same measurement for my laser once we're allowed to turn it on. The table now has a mock-up of the Fabry-Perot cavity locking scheme, it's still missing a few mirrors but the gist of it is there. I also changed the setup for our actual gyro design. In order to increase the finesse of the cavity, we got rid of one of the partially transmitting mirrors in the triangular cavity. So there is now a setup with two highly reflective mirrors and one partially transmitting, and both the clockwise and the counterclockwise beams will be injected into that one. We're also going to set it up so the clockwise mode goes through the AOM twice in order to double the effect. My first progress report is attached to my 40m wiki page. (Sorry, no LaTeX yet, will figure that out).

Attached here is the new diagram for the gyro setup.

 

Attachment 1: NewerGyroDesign.PNG
NewerGyroDesign.PNG
  148   Thu Jul 2 15:37:57 2009 AidanMiscFiberWeekly Report - query on previous reply

Quote:

Quote:
Most of this week was spent on three tasks: characterizing the beam divergence of the NPRO Laser and fitting a curve to the data, the progress report, and contending with serious computer problems. The information on the beam divergence can be accessed in a previous log. The waist size is around 120 micrometers, and according to a least-squares fit, it is located 21cm behind the aperture. My understanding of the fiber suppression setup and its relationship to the second-harmonic generation system was strengthened, but nowhere near completed, in the process of writing the progress report. We plan to send the NPRO beam through an AOM driven at f1, then double-pass it through a 50m fiber (not to be bent at a 90 degree angle as drawn in the meeting today) and another AOM driven at f2. This signal will be interferometrically mixed with the original beam from the NPRO, producing beats at 2(f2-f1), then run through a multiplying mixer driven at 2(f1-f2) and a low-pass filter so the final signal consists mostly of the noise acquired when travelling through the fiber. A computer characterizes this noise, and sends a signal to the first AOM which actuates on the original beam so as to suppress the noise. ********************NOTE: Aidan plans on changing the setup slightly, and I'll give the details on that in the next report************************* Finally, my computer acquired a terrible virus yesterday morning when I clicked on an innocuous-looking facebook message that was sent to my email and titled "hi." All of yesterday and the first part of today was spent rebuilding the computer. Don't trust facebook. I now have a centos operating system, so I'll be learning to use Linux fast (hopefully).

 FORMAT PLEASE!

 

Who was the author of the previous entry? It wasn't Connor apparently.

  153   Mon Jul 6 15:31:07 2009 Aidan, AlastairMiscGeneralEquipment moved from 58C

The following equipment was from 58C (old mesa beam lab) into 58D during the clean out of the former lab.

2x SR560s ([Ligo Project Property (LPP) C20862, Caltech 44961], [LPP: n/a, Caltech 44782])

2x Phillips PM 5193 programmable function generators (0.1 - 50MHz): ([LPP: n/a, Caltech 9313], [LPP: C20365, Caltech: 1348])

1x SRS DS345 function generator (<30MHz): (no tag - serial # 36560)

1x Tektronix AFG3102: (no tag - serial# AFG3102 C020795)

1x HP 8656B signal generator 1-990MHz: (LPP: n/a, Caltech 23616)

These have all been labelled "John Miller Lab" to indicate where they came from. (None of the equipment was plugged in)

  159   Wed Jul 8 10:36:44 2009 MichelleMisc Week 3 Update

We have mirrors! And clamps! And posts! In short, everything we need to actually put all the optics in their proper places. Thus, this week I have successfully placed the steering mirrors and the high reflectance mirrors into their mounts without touching/breaking any of them, and soon I'll be clamping them in their proper locations.

Connor and I  found out that Aidan's laser isn't behaving itself. The manufacturer specifies the waist as being in a different location than where we calculated it to be. We sent the beam through a half-wave plate and then a polarizing beam splitter and then measured the power along each axis, and the ratios are strange. We can't get the beam to be entirely transmitted along one axis by rotating the half-wave plate, like we should be able to if the beam is coming out linearly polarized. So the hypothesis is...it's not coming out linearly polarized. It may be elliptical. For the time being we're going to split the beam from the other NPRO and use it for both experiments, at least while the alignment is taking place. In the case of the gyro, we'll actually be feeding back to the laser and altering its frequency, so we'll definitely need separate lasers for each experiment at that time.

The 495 mW NPRO's SOP has finally been (mostly) approved and it first lased on Monday. This laser's power supply is a bit weird - the display for the power it thinks the laser is putting out doesn't match at all with what the powermeter actually says the laser is putting out. So we're not paying attention to the power display. The drive current goes up to 1.00 A, and at this maximum current, the laser is putting out ~150 mW. Apart from not being able to get a higher power than this, the laser is fairly well behaved - the power fluctuations as measured by the powermeter are small. The results of output power vs. drive currentmeasurements are on the eLog.

Connor and I also measured the electronics noise and intensity noise at various different powers, and then did a theoretical shot noise calculation for each of these. The setup and procedure are described in more detail in a recent eLog entry, which also includes graphs and the matlab code used to generate them.

Over the next week I'll be setting up the optics table for a simple PDH lock using a fabry-perot cavity, aligning the laser, and setting up the proper feedback using the DAQ. (Which I'll need to talk to Dmass about).

Oh, and we found out yesterday that Connor and I can't do any hazardous tasks in the lab without supervision, which includes aligning the lasers, even at low power. Aidan and Alastair will both be gone from tomorrow until next week Friday, so this poses a slight challenge. Hopefully Dmass will be around?

That's about it for now, I think.

  160   Wed Jul 8 10:46:58 2009 ConnorMiscGeneralWeekly Report #3

          The majority of this week has been spent learning about sources of intensity noise and the methods we use to characterize it.  The sources that I focused on were the "electronics noise" associated with various instruments (this week the instrument used was a photodetector, contributing fluctuations in intensity called "dark noise"), shot noise, and the noise produced by source itself (in our case, a 495 mW NPRO Laser).

          The theoretical method of characterizing a noisy time series is called a Power Spectrum, which is defined as the Fourier transform of the series' autocorrelation.  Intuitively, this is a frequency-domain representation of the extent to which a given frequency is represented in the time series.  Experimentally, it is more convenient to take advantage of a couple of theorems relating the Power Spectrum of a time series to its Fourier transform over a finite time interval;  The SRS spectrum analyzer that we used this week calculates the discrete Fourier transform of an input signal over a given time interval, squares that value, and divides by the time interval to get an estimation of the Power Spectrum.  Typically, we run the signal into the spectrum analyzer for many of these time intervals, and the values computed over each of these intervals are averaged.

          We measured the dark noise and the total intensity noise of a 495 mW NPRO laser using a PDA10CS photodetector, and made a theoretical prediction for shot noise based on the output power of the laser.  The data we collected is contained in yesterday's entry.

          Aidan has been working hard on getting the DAQ to its operating point, which will make measurements such as those described above easier to make.

          The plan of action for the upcoming days is to set up a Mach-Zehnder Interferometer for the same laser and characterize the phase noise its beam acquires, hopefully with the assistance of the DAQ.

 

  173   Wed Jul 15 12:36:17 2009 Connor MooneyMiscGeneralWeekly Report #4

     Aidan was in Hanford this week, so I switched gears and worked mostly on modematching the 35W PSL with Dmass.  This requires passing the beam through a couple of lenses to alter the waist size and location before it enters the PMC. Last year, he took some beamscans post-lenses. We wanted to see if this data matched with the pre-lens beam parameter. I used ray transfer matrices to perform the inverse calculation. We found a mismatch between the calculated and expected waist location, which could not be fully explained by the engineering tolerance of the lenses or by the lens orientation.

     Dmass also noticed something funny about the head of one of the lenses, so he made some changes to that and made more beamscans that we will look at.

     There are a number of objectives for the upcoming week:

     1) We believe that the 1W NPRO is elliptically polarized. I learned about Jones vectors and Jones matrices, which are a convenient linear-algebraic representation of a beam's polarization and how it changes as it passes through various optics. The beam can be linearly polarized by passing it through a quarter-waveplate (QWP) whose fast axis is correctly angled. To test this, I will pass the beam through a QWP, and aligned a half-waveplate (HWP) and polarizing beamsplitter (PBS) to find its extinction ratio for various QWP angles. (The extinction ratio is the ratio of the minimum to maximum transmitted powers of the beam as the HWP is rotated.)

     2) I'll work on coupling the 1W NPRO into a 50m fiber.

     3)I'll align a Mach-Zehnder interferometer to measure the phase noise of the 1W NPRO, and also single pass the beam in one arm through the 50m fiber and characterize the phase noise it acquires.

    

 

  189   Wed Jul 22 09:43:53 2009 ConnorMisc Weekly Report #5

Most of this week has been spent aligning optics for the fiber stabilization experiment.  Part of the setup is shown here

The next step is to couple the beam into the fiber, single pass it and interferometrically beat it with the original signal so we can characterize the acquired phase noise.

Mode matching to various optical elements involves changing the beam parameter (i.e., beam width and radius of curvature) to fit specifications. We do this using lenses. Given the incoming beam parameter, the desired outgoing beam parameter, and lens focal lengths, we can find solutions (lens positions) to the problem.

  190   Wed Jul 22 11:09:45 2009 MichelleMisc Weekly Update 5

Over the course of the past week I've done a few things. When I began alignment I discovered that our laser was periodically shutting itself down. This was a very perplexing problem for about 2 days before Alberto came in with the diagnosis: the diode was overheating. We'll be sending that in to get it fixed, and we'll also put a heat sink on its casing. Hopefully that will be up and running by the time we really need it.

Right now, Aidan's laser is set up with a 50/50 beamsplitter, and then a half wave plate at each output of that. That way we can run the laser at full power, and each of us can independently adjust the power going into our respective experiments. This is working well while we're aligning things, but it clearly won't work long-term - we need to act directly on the laser's frequency to lock it to a cavity. This may not fare so well for fiber noise suppression.

We have our setup mostly aligned. The beam is going through some steering mirrors, through a lens, into the Faraday Isolator, through another set of steering mirros and a lens, and into the EOM. There is very little loss inside the isolator (putting in ~35 mW and getting out 33-34 mW), however I have not been able to get the power at the output of the EOM higher than ~ 24 mW. I don't think this is normal, but I will check that with people who know better than I do. I think it is probably the fault of poor alignment - the aperture is ~ 2mm and it's about 2 cm from the lens in the middle of the table, so it's hard to reach it or even view it properly to see what needs tweaking.

Over the next week I plan to finish the alignment and hopefully get a lock. I'll get a picture up once the rest of the setup is in place and aligned.

 

Oh, and I also helped clean the lab this week. It's pretty shiny, except for the heaps of garbage boxes now sitting in the hallway. We'll take care of that soon.

  229   Wed Aug 5 10:10:11 2009 MichelleMiscGeneralWeekly Update (7?)

A number of things made the past week somewhat unproductive, until yesterday. I was at a conference Mon-Wed. last week and was sick that Friday. This Monday I finished my second progress report (now on the wiki).

Yesterday we made major progress in the setup and alignment of the cavity. It was really helpful to have optics people (Zach and Frank) down in the lab, I learned a lot about alignment. We replaced the two lenses we had initially (one before the FI and one before the EOM) with one slowly converging lens which would place the waist in the EOM. Frank also said there was no need to have two steering mirrors before different optics, since our laser height is fixed. We were initially going to use a curved mirror for the high reflectance mirror at one end of the cavity, but Rana suggested that we would get a lock faster if we just used two flat mirrors with a lens in between them (since the finessed of the cavity doesn't really matter right now). We're also not going to worry about mode-matching just yet.

The cavity is now roughly aligned. It will need some fine-tuning, but we should be able to start trying to lock today. We're going to start with an analog system to get a feel for the parameters and just to get some sort of error signal, and then later we'll switch everything over to the DAQ. That's about all for now.

  250   Tue Aug 11 18:14:49 2009 AidanMiscGeneralHive of activity ...
Attachment 1: 00001.png
00001.png
  265   Thu Aug 13 20:46:37 2009 KojiMiscDoublingPhase Matching Curve Measured

What I helped was only ... this

darkside.jpg

Quote:

With Koji's help, I figured out that my problem with the prism was an insufficiently steep angle of incidence. I now have split the beams nicely. The prism is uncoated, so I have visible reflection losses (which I am dumping with razor blades).

 

  283   Sun Aug 23 12:41:18 2009 AidanMiscGeneralLower lab temperature 3 degrees. Too warm in here.

Changed the set point on the temperature in the lab to 61F from 64F.

  352   Mon Sep 28 16:53:07 2009 ZachMiscGeneralAOMs

 There are three AOMs in the cabinet downstairs, two of which are not labeled beyond their model numbers. I tracked down some information on them and am posting them here so that we have it in the future.

First, the one that was labeled with a center frequency:

  • Crystal Technologies
    • Model No.: 3200-1113
      • f_center = 200 MHz

Now, the party crashers:

  • IntraAction Corp.
    • Model No.: AFD-402
      • Flint glass (F7)
      • Deflector
      • f_center = 40 MHz
      • Aperture: 2 mm
      • Serial No.: 1002
    • Model No.: AOM703M
      • Flint glass (FF8)
      • Frequency modulator
      • f_center = 70 MHz
      • Aperture: 3 mm
      • Serial No.: 6805

I have attached pictures of the latter two for reference (the first one is still packaged, labeled, and located in its own marked compartment).

Attachment 1: AFD-402.png
AFD-402.png
Attachment 2: AOM703M.png
AOM703M.png
  353   Mon Sep 28 17:17:08 2009 KojiMiscGeneralAOMs

Hm. L_gyro = 3e8/(2*70e6) ~ 2m in a round trip. The 70MHz sounds nice for gyro. Do we have dedicated AOM drivers for them?

Quote:

 There are three AOMs in the cabinet downstairs, two of which are not labeled beyond their model numbers. I tracked down some information on them and am posting them here so that we have it in the future.

First, the one that was labeled with a center frequency:

  • Crystal Technologies
    • Model No.: 3200-1113
      • f_center = 200 MHz

Now, the party crashers:

  • IntraAction Corp.
    • Model No.: AFD-402
      • Flint glass (F7)
      • Deflector
      • f_center = 40 MHz
      • Aperture: 2 mm
      • Serial No.: 1002
    • Model No.: AOM703M
      • Flint glass (FF8)
      • Frequency modulator
      • f_center = 70 MHz
      • Aperture: 3 mm
      • Serial No.: 6805

I have attached pictures of the latter two for reference (the first one is still packaged, labeled, and located in its own marked compartment).

 

  355   Mon Sep 28 17:56:42 2009 ZachMiscGeneralAOMs

Not as far as I know, but I can try to find something. We just received a new driver from NEOS but it is for 80 MHz and is only rated for 75-85.

Quote:

Hm. L_gyro = 3e8/(2*70e6) ~ 2m in a round trip. The 70MHz sounds nice for gyro. Do we have dedicated AOM drivers for them?

Quote:

 There are three AOMs in the cabinet downstairs, two of which are not labeled beyond their model numbers. I tracked down some information on them and am posting them here so that we have it in the future.

First, the one that was labeled with a center frequency:

  • Crystal Technologies
    • Model No.: 3200-1113
      • f_center = 200 MHz

Now, the party crashers:

  • IntraAction Corp.
    • Model No.: AFD-402
      • Flint glass (F7)
      • Deflector
      • f_center = 40 MHz
      • Aperture: 2 mm
      • Serial No.: 1002
    • Model No.: AOM703M
      • Flint glass (FF8)
      • Frequency modulator
      • f_center = 70 MHz
      • Aperture: 3 mm
      • Serial No.: 6805

I have attached pictures of the latter two for reference (the first one is still packaged, labeled, and located in its own marked compartment).

 

 

  356   Mon Sep 28 20:40:53 2009 AidanMiscstuff happensPlease do not leave the permanent marker by the whiteboard ...
  362   Thu Oct 1 11:05:09 2009 ZachMiscGeneralTelemarketers

 Apparently, the ATF lab could have received free passes aboard a cruise to Nassau, Bahamas if it had answered 10 questions correctly. 

  364   Wed Oct 7 00:05:17 2009 AidanMiscFiberIntraaction 70 MHz AOM - photos

Here are some photos of the inside of the 70MHz Intraaction AOM that we're using temporarily in the FS experiment. I'm not sure what the crazy red glue is all about.

Attachment 1: aom1.jpg
aom1.jpg
Attachment 2: aom2.jpg
aom2.jpg
Attachment 3: aom3.jpg
aom3.jpg
Attachment 4: aom4.jpg
aom4.jpg
Attachment 5: aom5.jpg
aom5.jpg
  367   Wed Oct 7 02:47:41 2009 AidanMiscstuff happensDigital camera is in my office
ELOG V3.1.3-