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 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

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

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

Improvements pimp my 4D… SW: Acquisition steps splitted Capture .raw28 Hz Process .cal 9 Hz Reduce .h5 1.2 Hz Faster capturing Independent sessions: Sampling -- Processing 1

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. 2

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 3

Working at a faster frequency Trigger 28.5Hz clock Resulting frame rate

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

Sampling sessions BCU39 Interface 4D AdSec AOWS WF S Phase Cam Fastlink1 TX Trigger Shapes Sampling Start of Frame

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

! 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

Starting trefoil +mode -mode +mode

Trigger Command

Sampling procedure 0. connect & set-up »Connect HW »Set the shell »Configure BCU & 4D 1.Create a set of shapes (IF, MirModes, KL) 2.Start 4D acquisition (no action on trigger) 3.Enable the shapes sending »Commands to AdSec »Pulses to 4D interface 30 min 2 sec 1

Sampling procedure 0. Commands applied by AdSec »+zeroes+starting trefoil… »Oversampling 1.Modes commands template: [1,-1,1] 2.Images are captured 3.‘Move’ from RamDisk to HD 4.Download of command history from SDRAM 50sec 40sec 5 min Images ‘production’ (process+reduction:.dat .h5) Data analisys w/template: [1,-1,1] Analisys of electrical data 30min 20min 1 min 2