Ryan Short, Tony Sanchez, Sheila
We took beam profiles of the sqz beam in the homodyne path using the Thorlabs M2Ms beamprofiler extension. It made collecting data for a variety of psams settings much faster than using a scanning slit profiler alone.
Tips for using this very nice extender kit:
- The visible alignment laser made alignment easy.
- We used the lens LA1461-C for 1064nm, the list of lenses and wavelengths is here: lens list
- make sure that the unit is plugged in, powered on with the power button, and connected to the laptop before you start the software. Close and re-open the software if "translation stage control" and "M2 set" don't show up for you at the bottom of the "beam settings" window. Once they show up you just have to go to the M^2 button and hit play to make a measurement.
- You can get the fit beam parameters by saving a pdf by clicking the button that says "Save test Protokol", you have to hit save twice on the screen where you type a file name and again on the next screen. "Save Measurement Data and results" gives you all the data, but not the fit beam parameters. You again have to hit save twice.
- Sivananda Reddy contacted Thorlabs and posted a diagram of where the reference plane is in the dcc: T2500077
We spent some time refinding the IR beam on the SQZT7 IR PD, documented this in it's own alog so it's easy to search: 90183
We set the profiler as shown in the attached photo. The flipper mirror is 50.75" from the bottom persicope mirror, a steering mirror is 225mm from that, and the reference plane is 260mm from the steering mirror, so the reference plane is 1.774 meters from the bottom periscope mirror. Leo Schrader has a helpful list of distances in the google document linked to T2500228.
- In 85282 Leo measured the beam distance from the top to bottom periscope mirrors to be 574mm.
- The distance from the top of the persicope to the beam diverter was measured to be 84.5" in 61755.
- In 75749 the distance from the beam diverter to ZM5 is listed as 1183.54mm based on a CAD drawing from Don Griffith.
- This means the total distance from the reference plane to ZM5 is 5.678 meters. We have left the profiler and temporary mirrors in place so that we can use them during the upcoming HAM7 vent.
Keita, Ryan Short, Tony, Sheila
In the saved PDFs, the units on "Beam Waist Position" are listed as um, but in the text file (which does contain all the same information), the values are the same but the units are mm. mm must be the correct units.
Looking at T2500077 we believe that to get from the reported Beam Waist position in the text file we need to add (z_stage_min - 4.4 mm= 122.9mm) to the distance from the reference plane as depicted in that diagram to the waist position. We believe that this waist position being positive means that the waist is after the reference plane (on the sensor side of the reference plane), I think a negative number would mean the waist is before the profiler.
I asked Claude to write a script to collect the data from the txt files in the archive above and save it in a yml, the script is attached here in case someone else wants it.
