TMS Meeting Minutes, May 20, 2021

Attendees: Andrew, Breann, Heejoo, John, Matthieu, Olga, Trenton, Yang (Zoom Meeting)

Etalon Finished Port Closure Testing
  • When TMS code run via TCP/IP for over one hour, the Etalon system crashes with the port left open
  • Problem traced back to a third party driver
  • Etalon has since fixed the code and uploaded it to our system
  • Running for 24 hours, the TCP/IP TMS code was successful without any crashes
    • Pinged data from all 28 channels every 10 seconds for 24 hours
    • No errors encountered
    • No restarts required
  • Andrew curious if Etalon has logged the number of times errors were encountered during the 24 hour test (Heejoo to look into this)
  • Unfortunately, the testing finished just yesterday, so there was no time to test the bino code
Bino Code, Closed-Dome Testing (next Tuesday)
  • Bino code testing planned for two hours on Tuesday
  • There are no urgent telescope scheduling items on Tuesday, so we may be able to go longer
  • Andrew will focus his work on the commissioning document to specifically make it useful for Tuesday's testing
Thermal Focus Analysis
  • Trenton is conducting ongoing work
  • Thus far, appears to be fairly good correlation between thermal and Z4 (-0.8579 Pearson's correlation coefficient)
  • More difficult to determine correlation with highly varying data
  • Will reach out to Breann for assistance with mirror thermal gradient vs. Z4 correlation analysis
Kill-a-Watt Power Consumption Testing
  • Heejoo planning to purchase a unit to test the consumption of the Etalon system (will first check with LeRoy about current purchasing status)
  • Need to reach out to Mark from Etalon to figure out what the percieved load should be
  • If anything, the system is currently plugged in to a 20 Amp outlet, so we think the Kill-a-Watt system should probably be fine
Commissioning Plan
  • Normally, during a commissioning plan, there is a whole bunch of other work being done, with a set of system reqmts. which must be met
  • For TMS, this is an organic development, and we must produce our commissioning doc from the top down with our own idea of specs
  • Want the document to be something that someone like Rick P. can pick up and read and understand
  • Will include references to other relevant documents, for the reader's personal edification
  • Want this not to be a black box just for the TMS team, but useful to all groups at LBT, including observers who might use this to assess risk of using TMS
  • This is not a comprehensive reqmt. document, as would be required for GMT PDR etc.
  • Rather, Andrew focusing on which reqmts. necessary for transitioning TMS into frequent use during science observations
  • Broad categories of reqmts.: hardware, software, operations, RAMS (reliability, availibility, maintenance, and safety)
  • Compliance matrix at the end summarizes all of the results
  • Requirements:
    • Hardware:
      • Available Channels:
        • Basic min. of 6 available channels
        • (At least 6 channels received on) 3 retroreflectors at dif. locations on the target objects receiving at least one channel
        • At least two retroreflectors will receive at least two channels
      • Channel measurement resolution
        • Measure differential length changes over periods of 10 to 20 seconds with resltn. of < 2 micron
      • Channel measurement noise
        • Standard deviation threshold of 5 microns
        • Justification: min. 6 channels, noise can compromise this reqmt., std. dev. filter helps with satisfying ch. reqmt.
      • Long-term stability
        • Positional stability over long periods quantified by 1-sigma error in gauge length arising from "node instability"
        • Current collimators are NOT stable enough, and are uncorrelated (multiple microns of change in collimators over time)
        • Mark II collimators should help to improve this stability, but we aren't there yet
      • Short-term stability
        • Now, shorter time scale, with FPIA resets
        • How stable does the collimator have to be over short periods?
        • As of now, have some fiber drag, loose-ish mounting of collimators, etc.
        • Amplification factor is something like 5 per pose term, and we are most sensitive to Z (focus)
        • 1 um of Z motion could result in about a 1 um increase in FWHM
        • 15 um of Z motion would result in 1 pixel of blur
      • Alignment stability
        • Must maintain signal strength in the EAMT contrast meas. of > 5% over the operational range of elevations and temperatures
      • Shutters
        • They gotta work, no compromise
        • Apart from measurements, no LBT instruments should be able to detect Etalon laser light when shutter closed
      • Stray light detection system
        • System to detect light whenever TMS emits into the enclosure
    • Software:
      • Etalon EAMT Software
      • LBTO TMS TCP/IP Software (mono/bino)
        • Commands measurements, receives and processes data from Etalon and LBTO Data Dict., and produces pose vectors of M1 6 DOF's
      • LBTO Software Interface w/ Telescope (TCS)
        • Takes M1 pose vector and modifies according to various offsets deterministically introduced by telescope operations
        • Residual applied to telescope
    • Operational
    • RAMS
  • This level of complexity should help to assure astronomers that this system will mitigate risk of lost science data
  • At the top of the doc., it is most important to convince astronomers that TMS will improve their observations and that it won't negatively affect their data
Telescope Time
  • There has not yet been a proposal for a TMS engineering night
  • Andrew proposes that we make an anticipatory request right now, or at least by early next week when the commissioning document is more mature
  • Olga thinks that there is 1.5 engineering nights, and 1.5 director's time (which Christian may be willing to give us)
  • Block of LBTI commissioning that goes through Sunday, and they've asked for backup partner subscriptions in case conditions are poor for LBTI
  • First to LBTI, then to backup programs, then to engineering (a backup to the backup, requiring a configuration change)
  • If some opportunistic slots open up, what test would we like to run
    • Would be great to test the stability over a transit, continuously getting pupils
    • System stability; collimate with FPIA, run TMS for an hour, and run FPIA again
    • Set up a nice, stable observation somewhere in the North, start continuously taking defocus pupils while driving thermal into the mirror (could be nice in poor seeing)
  • Keep in mind, this could be very bad seeing conditions, greater than 1.6 arcsec seeing with over 2 magnitude cloud extinction
  • Goal has to have a commissioned system ready to go
  • No LBC observation tonight, due to weather (clouds, wind, blah)

-- TrentonBrendel - 20 May 2021
Topic revision: r1 - 21 May 2021, TrentonBrendel
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