Keck Interferometer Auto-alignment SystemKECK INTERFEROMETER Keck Interferometer Auto-Alignment...

KECKINTERFEROMETER

Keck InterferometerAuto-Alignment System

Leonard J. Reder

[email protected]

Jet Propulsion LaboratoryPasadena, California

20 Nov. 2002 Keck Interferometer Autoaligner 2

Contributors

• At JPL: A. Booth, M. Colavita, E. Deems, E. Hovland, R. Johnson, R. Ligon, J. Moore, D. Palmer, R. Smythe, A. Tumminello, G. van Belle

• At Keck Observatory: A. Rudeen, T. Saloga, K. Tsubota


Keck Interferometer Update

• 2 Keck 10m telescopes with full adaptive optics (AO).• Wavelengths 1.2 um to 10 um (AO operates in visible).• Science: nulling, differential phase, astrometry, imaging.• First fringes with Keck Telescopes March, 2001.


First Fringes• Initial fringes using siderostats were obtained on Feb. 22,

2001.– Checked out hardware to be used with Kecks on next run.– Two 50-cm siderostats feeding fixed 40 cm telescopes (essentially

the same as the Palomar Testbed Interferometer front-end optics).• EPICS 3.14 alpha SNL sequencer used for sidereal delay

line target generation through 2001.

Enclosures

• First fringes using two large Kecks March 12-14, 2001 (3 1/2-nights)


What I will talk about• Interferometer Major Components

• Automatic Alignment Process- Sequencers - EPICS State Notation Language (SNL)

-- Beam Train Alignment Sequencer (btSeq)-- Internal Instrument Alignment Sequencer (iiSeq)

- Optical alignment control user interface (aligner.tcl)-- Manual and automatic

• Sensors/Actuators/Targets and EPICS- Device Support and Drivers- Use of existing EPICS components (Records, Device

Support and Drivers)


Fastdelaylines

Long delay lines

BeamInjection

andSwitching

Switch-yard

Imaging and nullingcombiners

Fringe trackers

Angle trackers

Auto-aligner

Keck 1

CCD

Optical Path Through the Basement

Keck 2


Optics and Control Layout for First Fringesk5,m10

k6,m10 k6,m11

k5,m11

k1,m11 k2,m11

k1,m14p

k2,m14p

k1,m20p

k2,m20p

k1,m24p

k2,m24p

k1,m21p

k2,m21pk2,ccdp

k1,ccdp

FDL0

FDL1

KATp

k0,dcrp k2,dcrp

k1,dcrp

bc1,m23f

bc1,m23b

bc1,bfw

bc1,ffw

bc1,m25

bc1,stim,wlm

bc1,stim,bslm

Bore Sight

White Light

bc1,stim,wfw

bc1,stim,wlint

bc1,stim,bslint

k1,m10

k2,m10

Sid 2

Keck 1

Keck 2

Sid 1

Optics Layout for motion control for first fringesv1.7, 6/26/01, A.J.Booth

LDL1LDL0

k1,m9

k2,m9

FATCAT1

ft1,fwft1,prsm

ft1,tt1

ft1,tt2

k1,shpk2,shp

bc1,stim, bslsh

kat,sh

ftf

bs

bc1,sh1

bc1,sh2bc1, m2

bc1,m1

bc1,stim,wlsh

ft1,focus

sy,ccaln

sy,ccfts

bc1,stim,inp

CT met

k1,shctk2,shct

k2,stop

k1,stop

k2,shkatk1,shkat

• AA Sequencers:- 6 Beam Train- 4 Internal• Sensors:- 2 C.T.- 4 Cameras

• Stimuli Targets:- White Light- Laser Boresite- 12 LEDs

• Actuators:- 20 Newport 850G- 26 Pico Motors- 16 Shutters- Other Misc.


Interferometer Major Components

Beam Transport Optics(Coude Train)

Keck 1 FM

Fringe Tracker (FATCAT)

Fast Delay Lines (FDL)

Angle Tracker (KAT) Long Delay Lines (LDL)


Keck Interferometer Software

CORBA

JPL RTC Toolkit“Fast Servo Control”-Fringe Tracking-Delay Lines-Tip Tilt

JPL/Keck EPICS“Auto-Alignment”-Motion Control-Sensors/Targets

Keck EPICS“Telescope S/W”- Sequencer

User Interface Scripts

Optical Alignment Tool

(aligner.tcl)Misc. dm and dm2k

panels.

SequencerObserving Tool

(seq.tcl)Channel

Access

JPL RTC JAVAEngineering GUI

ChannelAccess


Automatic Alignment Approach1. Align “backwards” from detector to telescope.2. Threading optical axis from instrument internal combiner

out through beam train to optical telescope.

Front view:Mirror surface and LED targetin front.

• Use camera at back end of system.

• Use LEDs mounted on swing armand positioned in front of mirror as alignment targets.

• Illuminate LEDs, and align prior mirror in beam train.

• Repeat from inside instrument up to telescope to thread beam along optical axis.


EPICS Alignment Control of Major Components

Long Delay Lines Sled

Beam Transport Optic As Seen from CoudeTunnel

Beam Transport Optic

• Beam Transport Optics (Coude Train) and Long Delay Lines (LDL) auto-alignment via SNL sequencer implementation (btSeq).


EPICS Alignment Control of Major Components

Opened Fringe Camera Fiber-fed laser metrology

Dichroic Optic

• Fringe Tracker (FATCAT)– PZTs driven by JPL custom device support for alignment.– Focus and filter wheel control, white light stimulus adjustment, etc.

• Angle Tracker (KAT) and Constant Term Metrology SNL seq. alignment


EPICS Automatic Alignment Sequencers

• Implemented in VxWorks using SNL.

• One instance of sequencer per mirror to align.

• Internal Instrument Alignment Sequencer (iiSeq)— Alignment of back end sensor components

(KAT, FATCAT, CCD).— Auto-align constant term metrology.

• Beam Train Alignment Sequencer (btSeq)— Large transport optic mirrors.— LDLs and Coude Train.


Autoaligner Camera System


Frame Grabber/Centroiding

genSub

Image

Grab/Centroid forward link triggered from sequencer or periodic ratescan.

Framecount

INP link toSelect Snapper 24

XCEN, YCEN coordinate of alignment target.

• DataCell Snapper 24 PLC frame grabber used with modified version of driver written by Miroslaw Dach ([email protected]) at the Paul Schere Institure.• Device support links driver and Image Record written by Ned Arnold ([email protected]) LANL. Image Record is glue between EPICS IOC and genSub record.• genSub record used to wrap alignment target centroid estimation algorithm.


Actuated Optics

Transport Optic w/850G Dichroic Optic w/Picomotors• Common actuators used: two kinds throughout system.• Beam Train Transport Optic driven by Newport 850G DC servo long travel actuators.• Piezoelectric New Focus Picomotors used on smaller optic.


Actuated LED Targets

Retracted In position and illuminated• AA Targets position and illuminate with a high degree of

repeatable motion: 0.25mm• Limit switch feedback state of target to EPICS device support.


EPICS Device Support and Drivers

• Datacell Snapper 24 Frame Grabber image record support.• Delta Tau Turbo PMAC device support and motioncontrol sequencing used on Keck AO bench is used forbeam train transport optic positioning.

– Originally written by Thomas Coleman, ANL– Updated by Kevin Tsubota and Paul Stomski, Keck

• Industry Pack device drivers support utilizing Andrew Johnson’s Industry Pack Driver Software (drvIpac).

– Acromag IP480, IP230, IP330 modules– Greenspring IP-Digital24, IP-Driver40 modules– Generic device support for bi, bo, ao, ai, longin, longout

• JPL specific device support implemented.– Picomotors, cryo focus motor, laser attenuator, etc.


Automatic and Manual Optical Alignment User Interface TCL Application (aligner.tcl)

Alignment Position Status

Actuator Status

AA SequencerMonitors &Controls

AA MirrorSelect

Text Status SensorSelect

Alignment Vector& AA Camera Image


Summary• KI is taking “shared risk” science data (since June).• Automatically aligning parts of interferometer.

– Angle Tracker (KAT).– CT Metrology.– Fringe Tracker (FATCAT).– Beam Train Mirrors.

• Refinement of Frame Grabbing Technology andCentroiding for better beam train auto-alignment is needed (presently ~ 1.5 pixels, requirement 0.1 pixels).

• A top level sequencer to orchestrate all alignment is next major development effort.

• More info about Keck Interferometer go to web site: http://planetquest.jpl.nasa.gov.

• Device support codes available from [email protected].


W. M. Keck Observatory: Feb. 2002

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