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IF and KL measurements with 4D interferometer

IF and KL measurements with 4D interferometer. Runa Briguglio, OAA. Rationale. New experimental set-up (4D+BCU39), that permits the reduction of convection and vibration noise. Acquisition of Influence Functions. Determination of KL modes and testing. Table of contents.

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IF and KL measurements with 4D interferometer

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  1. IF and KL measurementswith 4D interferometer Runa Briguglio, OAA

  2. Rationale New experimental set-up (4D+BCU39), that permits the reduction of convection and vibration noise. Acquisition of Influence Functions Determination of KL modes and testing

  3. Table of contents • 4D interferometer • Dinamic interferometry • High sensitivity • High speed external trigger • Improvements and tests • RamDisk • Software modifications • Trigger interface • Measurements • Exp. Set-up and connections • Acquisition procedure • IF: Zonal & Modal • KL

  4. 4D interferometer • Simultaneous phase shifting • No moving parts • No delay between frames • Single CCD for 0°,90°,180°,270° phases • High sensitivity • High density of fringes is detectable • Great help for alignment and first flattening • External trigger

  5. Burst acquisition:few points • Continous images sampling, 0.14Hz<F<28.5Hz • Data flow: • .raw • .cal • .h5 • External triggering • Programmable delay between trigger edge and capturing

  6. 1 Improvementspimp my 4D… • SW: Acquisition steps splitted Capture  .raw 28 Hz Process  .cal 9 Hz Reduce  .h5 1.2 Hz Independent sessions: Sampling -- Processing Faster capturing

  7. 2 Improvements • Data transfer to HD unreliable • RamDisk installed • Storage: 1600 frames, 0% faults …Depending on Frequency and n° of frames… No faults found at f<15Hz Ok for IF acquisition, at max freq.

  8. 3 Improvements • Testing: • GUI  scripting conflict • GUI commands reset the trigger settings • Ext trigger > Fmax is processed • ! Rising edges are detected after 1/28Hz • Internal delay verified • Using a sinchronized PZT • Repeatability better than 0.5ms

  9. 4 Improvements • Trigger interface converter • From BCU39 to 4D Interface BCU39 4D No delay, 200 us pulses 0-5V TTL Optic Fiber, 40MHz bus (25 ns pulses) TTL & Opto-coupled (TTL used)

  10. Sampling sessions Shapes AOWS WFS AdSec PhaseCam Fastlink1 BCU39 Start of Frame Interface TX 4D Trigger Sampling

  11. Timeline Time BCU39 AdSec 4D 0 20 40 ms A! Start of frame 12ms Start of frame Slopes to AdSec Slopes to AdSec Received commands Commands applied Oversampling period (5 ms) B! A! Trigger Trigger 8 ms Image acquisition 8 ms Image acquisition

  12. ! • A!: the image is captured Before the mode application The transient is not seen! We command a trefoil and 4 zero-shapes as starting point reference

  13. Starting trefoil +mode -mode +mode

  14. TriggerCommand TriggerCommand

  15. 1 Sampling procedure 0. connect & set-up • Connect HW • Set the shell • Configure BCU & 4D • Create a set of shapes (IF, MirModes, KL) • Start 4D acquisition (no action on trigger) • Enable the shapes sending • Commands to AdSec • Pulses to 4D interface 30 min 2 sec 2sec noise measurements

  16. 2 Sampling procedure 50sec 40sec 5 min 0. Commands applied by AdSec • +zeroes+starting trefoil… • Oversampling • Modes commands template: [1,-1,1] • Images are captured • ‘Move’ from RamDisk to HD • Download of command history from SDRAM Images ‘production’ (process+reduction:.dat .h5) Data analisys w/template: [1,-1,1] Analisys of electrical data 30min 20min 1 min

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