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2016

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2020-07-22T09:59:33Z

Acceptance in OA@INAF

The ERIS adaptive optics system

Title

RICCARDI, Armando; ESPOSITO, Simone; AGAPITO, GUIDO; Antichi, J.; BILIOTTI, Valdemaro; et al.

Authors 10.1117/12.2234001 DOI http://hdl.handle.net/20.500.12386/26568 Handle PROCEEDINGS OF SPIE Series 9909 Number

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PROCEEDINGS OF SPIE

SPIEDigitalLibrary.org/conference-proceedings-of-spie

The ERIS adaptive optics system

Riccardi, A., Esposito, S., Agapito, G., Antichi, J., Biliotti,

V., et al.

A. Riccardi, S. Esposito, G. Agapito, J. Antichi, V. Biliotti, C. Blain, R.

Briguglio, L. Busoni, L. Carbonaro, G. Di Rico, C. Giordano, E. Pinna, A.

Puglisi, P. Spanò, M. Xompero, A. Baruffolo, M. Kasper, S. Egner, M. Suàrez

Valles, C. Soenke, M. Downing, J. Reyes, "The ERIS adaptive optics system,"

Proc. SPIE 9909, Adaptive Optics Systems V, 99091B (26 July 2016); doi:

10.1117/12.2234001

Event: SPIE Astronomical Telescopes + Instrumentation, 2016, Edinburgh,

United Kingdom

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The ERIS Adaptive Optics System

A. Riccardi*

a,c

, S. Esposito

a,c

, G. Agapito

a,c

, J. Antichi

a

, V. Biliotti

a,c

, C. Blain

a

, R. Briguglio

a,c

,

L. Busoni

a,c

, L. Carbonaro

a,c

, G. Di Rico

a,c

, C. Giordano

a,c

, E. Pinna

a,c

, A. Puglisi

a,c

, P. Spanò

a

,

M. Xompero

a,c

, A. Baruffolo

b

, M. Kasper

d

, S. Egner

d

, M. Suàrez Valles

d

, C. Soenke

d

, M. Downing

d

,

J. Reyes

d

a

INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy

b

INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio, 5, 35141 Padova PD, Italy

c

ADONI – Laboratorio Nazionale di Ottica Adattiva, Italy

d

European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany

ABSTRACT

ERIS is the new AO instrument for VLT-UT4 led by a Consortium of Max-Planck Institut fuer Extraterrestrische Physik, UK-ATC, ETH-Zurich, ESO and INAF. The ERIS AO system provides NGS mode to deliver high contrast correction and LGS mode to extend high Strehl performance to large sky coverage. The AO module includes NGS and LGS wavefront sensors and, with VLT-AOF Deformable Secondary Mirror and Laser Facility, will provide AO correction to the high resolution imager NIX (1-5um) and the IFU spectrograph SPIFFIER (1-2.5um). In this paper we present the preliminary design of the ERIS AO system and the estimated correction performance.

Keywords: ERIS, VLT, Wavefront Sensing, Deformable Secondary Mirror, Adaptive Optics System, SPARTA,

CCD220, Laser Guide Star

1. INTRODUCTION

ERIS, the Enhanced Resolution Imager and Spectrograph, is a new 1-5 μm instrument for the Cassegrain focus of the UT4/VLT telescope that is equipped with the Adaptive Optics Facility (AOF)[1]. The instrument is led by a Consortium of Max-Planck Institut für Extraterrestrische Physik (MPE, leading institute), UK Astronomy Technology Centre (UK-ATC), Swiss Federal Institute of Technology (ETH-Zurich), European Southern Observatory (ESO) and Istituto Nazionale di Astrofisica (INAF-Arcetri, Teramo and Padova). The ERIS Consortium have taken the lead of the project in early 2015 and successfully passed the Preliminary Design Review (PDR) in February 2016. The project is currently in Final Design phase and the related review is foreseen in March 2017. The present paper reports the design of the ERIS AO system as result of the PDR.

The instrument is made of the following sub-systems (see Figure 1):

• two science instruments, which receive their light via a IR/VIS dichroic beam-splitter located in the AO module.

o NIX[4] provides diffraction limited imaging, sparse aperture masking (SAM) and pupil plane coronagraphy capabilities from 1-5 μm (i.e. J-M’), either in “standard” observing mode or with “pupil tracking” and “burst” (or “cube”) readout mode. NIX is a cryogenic instrument and it is equipped with a 2048 × 2048 detector providing a field of view of 53” x 53”

o SPIFFIER[5] is an upgraded version of SPIFFI, the 1-2.5 μm integral field unit used on-board SINFONI, that will be modified to be integrated into ERIS. Its observing modes are identical to those of SINFONI, possibly adding a high-resolution mode as a goal.

o The two science instruments do not operate simultaneously, an insertable mirror behind the IR/VIS dichroic allows to select the instrument.

• the AO module has wavefront sensing and real-time computing capabilities. It interfaces to the AOF infrastructure and it is required to provide the following observing modes:

Adaptive Optics Systems V, edited by Enrico Marchetti, Laird M. Close, Jean-Pierre Véran, Proc. of SPIE Vol. 9909, 99091B © 2016 SPIE · CCC code: 0277-786X/16/$18 · doi: 10.1117/12.2234001

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a.,-- I

'e.,_,___

In

C

rOCE

y

r ICE

.r--- Light from stars

- IR light - VIS light

Laser light

- NGS path VIS light

- Calibration light Moving in /out of U+ Connections routr Instrument shutte movable CU selec on common meck AO+wa VIS eeamsolitter NIX < I NIX IR entrant SRIFFI path ed via cable.wrao er and Rion Mirror hanism vm oOLÌCs ewindow 1

IIR entrance window

7

SPIFFIE

NIX Selector Mirror

=R From DSM CU 0. 1IR/VIS DichrolcI • The instr The ERIS AO ERIS Top Le Mirror (DSM system[3]. M GRAAL), wavefront detectors (EM modified SPARTA/AO Computer (R

2. LA

Figure 2 conceptual ERIS instrum the Adaptiv sub-system ( set of optic that relays optical beam Cassegrain science instru AO WFSs, Warm Optic considered p sub-system. Figure 1 Left o LGS-mo second W o NGS-mo o Seeing E used whe Calibration rument signatu O concept max evel Requirem M)[1][2] and th Moreover the namely sensor cam MCCD220) an version OF as Real-Ti TC).

AYOUT

shows scheme of ment, includ e Optics (A or module). T cal compone the telesc m out from Flange to uments and to is defined cs (WO) and part of the A ft: the ERIS inst

ode: a Wavefro WFS provides ode: a WFS pr Enhanced mod en no suitable Unit (CU)[6 ure) and perfo ximizes the re ments (TLRs). he artificial so ERIS AO su the mera nd a of ime the the ding AO) The nts, ope the the the as d is AO trument. Right: ont Sensor (W low-order cor rovides high-o de: only the on e NGS is avail 6], which pro orm troublesho e-use of existin In particular, odium Laser G ub-system us the ERIS sub-sy

WFS) provides rrection using order AO corr n-axis LGS W

able for the fa ovides faciliti ooting and per ng AOF sub-s , the AO corre Guide Star (LG ses componen systems (optical Figur s high-order A g a NGS in the ection using a WFS is used fo ast correction ies to calibr riodic mainten systems and c ection is prov GS) is generat nts from the l bench internal re 2 ERIS instru AO correction e patrol field ( a NGS in the p or the high-ord of the tip-tilt. ate the scien nance tests of components as vided by the A ted by one of t AOF GLAO l view). ument scheme n using a LGS (R≤1arcmin). patrol field; der correction ntific instrum f the AO modu s explicitly req AOF Deformab the launchers O systems (G on-axis and a . This mode is ments (remove ules. quested by the ble Secondary of the 4LGSF GALACSI and a s e e y F d

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cera

Sr,i

ipe ance Lens

,rt Board x -filed stag

Dichroic

/

Pupil stabilizat ommirror HO/LO SI ion Tech H lenslet switch ADC Folding mirror 1 Support h Board Plate Support Board focus stage Collimator lens Filter Wheel finical Camera

The ERIS ins IR/VIS dichr The IR/VIS d the AO beam 2 arcmin diam The two instr from the IR/V The AO mod the external D The LGS-mo introduction i the narrow-ba splitter also a functionalitie off-axis capab LGS loop is transmission The AO WF slow) optics (NCPA). Thi powered opti Natural Guid but implemen radius). The s standard appr successfully e The mechani and VIS/VIS regardless the The CU Sele all the sub-sy the WO com space constra with respect t

3. HO/L

Figure 3 sh baseline NGS merges the functionalitie mode, res configuration i.e. the highe SPARTA/AO constraints. implemented trade-off b performance allowing the number low strument is in roic, transmitti dichroic is the m from the scie

meter. ruments (SPIF VIS dichroic. N dule does not n DSM facility, ode requires t in the WO of and Sodium L as WFS Dichr es between the bilities. The L less sensitive through the W Ss opto-mech to relay the te is is an opport ics to integrate de Star (NGS) nting each W same approach roach for the experienced o cal scanning S dichroic to e off-axis. Thi ctor Mirror is ystems. The siz mponents. The

aint to fit the to the nominal

LO NGS W

hows the de S WFS imple HO and LO es for the NG spectively. n implements

est order com OF and CCD The LO con as a 4x4 S between p toward the e sensing o orders modes nstalled at the ing the IR (1-e first compon ence beam. Th FFIER and NI NIX is fed by need to intern part of the AO the implement f a VIS/VIS B LGS light from

roic. The curr e two WFSs in LGS WFS is i e with respec WFS dichroic s hanical design elescope beam tunity, to be e e a DM in the in the AO fie WFS units as h is adopted f AO systems on LBT-FLAO of the WFS b relay the tele is is an extrem s located upstr ze of the CUS e distance bet WO design. l VLT one.

WFS UNIT

esign of the ementation. I O NGS WFS GS and LGS The HO a 40x40 SH mpliant to the D220 forma nfiguration i SH array as a pushing the faint-end and of a suitable s for the truth

UT4/VLT Ca -5μm) light to nent of the WO

he size of the IX) are simult y inserting a 45 nally integrate OF[1][2]. tation of two Beam-Splitter m the rest of t rent design joi n a purely on-implemented ct to the HO N substrate. n has been co m to the AO W exploited, pro e AO module. eld is not perf a compact bo for tracking th developed by O[7] and Mage board to patro escope exit pu mely slow opti

ream the IR/V SM is driven b tween the Cas That requires e It S S O H, e at s a e d e h Figure 3. assegrain Foc o the science O and has also

dichroic (110 taneously inte 5deg mirror, t e any deforma WFSs, the H in the optical the visible rad ins the HO N axis LGS-ded in the beam tr NGS loop to nstrained by WFSs to max ovided by tele . As a direct c formed by an oard supporte he focus in bo y INAF-OAA ellan-AO (Ma ol the field req

upil (M2) to ics having the VIS Dichroic by the NIX Fo ssegrain Flang to increase t NGS WFS unit al Station. Th instruments a o the practical 0mm) is constr egrated in ERI he NIX Selec able mirror, in HO LGS WF branch reflec diation. Herea GS functiona dicated WFS a ransmitted thr the astigmat the general d ximize the stab

scopes with a consequence o optical field s ed by stages t th NGS and L for telescope agAO)[8]. quires insertin infinity and k focal length e to allow the C oV and contrib ge and the to the Cassegrain

t. The unit cove

he beam from and the visible l function of d rained by the IS. SPIFFIER tor Mirror, sti nterfacing for S and the LO cted by the IR after, we will r lity in the LO and an HO/LO rough the WF ism and chro design choice bility of Non an adaptive se of this design selector (tip-ti to scan the fi LGS WFS cas es with Adapt ng a telecentri

keep the chie equal to the di CU providing butes to constr op of SPIFFIE n Back Focal er is hidden to s the telescope e (<1μm) to th decoupling the reflected AO R receives dire ill part of the W

the wavefront O NGS WFS, R/VIS Dichroi refer to the V O NGS WFS, O NGS-dedica FS dichroic be omaticity intro of using flat Common Pat econdary mirr choice, the se lt mirror on a ield (circular, se. This design

tive Secondar ic lens betwe ef ray of the istance to M2 all the calibr raint the avail ER provides a

Length (BFL

how the conten

e is split by an he AO WFSs e alignment o patrol field o ectly the beam

WO. t correction to requiring the ic. It separates VIS/VIS beam separating the ated WFS with ecause the HO oduced by the (or extremely th Aberrations ror, forcing no election of the a pupil image) , about 32mm n choice is the ry Mirrors and en the IR/VIS beam paralle (14.9 m). ration needs to

lable space for another major L) by 250 mm nt. n s. f f m o e s -e h O e y s o e ), m e d S el o r r m

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sensing. Figu sensor signal mode up to th use of a 4x4 LGS mode. The main com

1. A dual a other (X compen and ther or R=32 respect t of WO a 2. A board from the 3. A rotary patrol th triggere vertical 4. The Ent stabiliza 5. A Pupil of the D 6. A beam for NGS mirror. Figure 4 Mo present in jitter ure 4 shows th l when the so he trefoil, requ configuration mponents and axis stage sup X stage) in th nsate for differ rmal expansio 2mm) and to c to the instrum and WFS unit d, supported by e stage for ma y stage suppor he full NGS F d by the verti (Y) motion w trance Lens p ation purposes Rotator (nam DSM on the SH m splitter dichr S acquisition. odal reconstruc the simulation. r and focus loop

he variation o dium density uiring 4x4 SH n with respect functions of t pporting the W he orthogonal rential focus w on. The X stag compensate fo ment focal plan

ts to the ERIS y the dual axi aintenance; the

rting the Entra oV combining ical space con with a third sta produces a F/2 s (see below). med also K-mi H lenslet array roic transmitti . The wavelen ction error usin

The beacon is ps. The error h f the modal r profile chang H as a suitable t to the minim the LO/HO W WFS board. On direction, pa with respect t ge, together w or all the effec ne. Part of the reference axi is stage, where e alignment is ance Lens and g the periscop nstraints insid age. 20 beam and r irror), implem y when ERIS i ing wavelengt ngths in the g a reference r re-centered and as sensitive com econstruction ges its vertica sampling for mal 2x2 produ WFS unit are: ne (focus) sta arallel to the p to SPIFFIER with the perisco

cts introducing e travel budge is. e all the WFS s reproduced b d a periscope. pe rotation wit de the ERIS c relays the inp mented with an instrument rot ths shorter tha range 600nm reconstructor w d the LGS WFS mponents up to error of an u al distribution the truth sens uces only a 0.

ge moves in t plane of the and NIX, inc ope (see below g a differentia et of the stage components by a set of mec

The axis offs th the X stage central structu put telecentric n Abbe rotato tator is operat an 600nm to m-1000nm are

ith different sod S is re-focused t

the trefoil Zern

unaberrated w . The error is ing. Numerica 5 mag loss of the direction o WFS board. cluding drifts w), is used to l image drift a es is used for t are mounted. chanical refer et of the peris motion. The re that does n c focal plane t or prism, to de ting in field tra a technical ca

reflected tow dium profiles. N to simulate the c nike mode. Sodi

avefront from s dominated b al simulations f the limit ma

of the input op The focus sta due to differe patrol the NG at the WFS fo the initial opti The board can rences. scope is 32 mm

periscope solu not allow imp to a tip-tilt m e-rotate the ac acking mode. amera that can ward the pupi No atmospheric correction effec ium profiles fro

m the HO LGS by the Zernike s show that the agnitude in the

ptical axis, the age is used to ential flexures GS FoV (R=1 ocal plane with

ical alignmen n be separated m, allowing to ution has been plementing the mirror for pupi

ctuator pattern n be also used il stabilization c turbulence is ct of the LGS om [9] S e e e e o s ’ h nt d o n e il n d n

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7. The pup the F/2 stabilize the pup The mai requirem pupil p alignme instrume wobblin due to flexures possible The mir a 2.5” fi 8. A 4-sto beam st pass-all with bri 9. A collim 10. An ADC elongati 11. A stage Camera 12. The ESO 6x6 pix samplin Figure 5 show 1. A focus changin compen differen 2. A board from the 3. An Ent stabiliza 4. A shutte 5. A Pupil ERIS in 6. A beam This cam system[ 7. The pup SH lens to alignm for a 5.0 8. A collim 9. The ESO size of t with a F pil stabilizati 20 focal pla e the lateral d il on the SH in contributor ment of the m plane lateral ent error betw

ent rotator ng during K-m residual alig s and therma e telescope ex rror implemen ield stop. op filter whe

top for dark filter for norm ght NGSs (1< mator lens rela C to compensa ion in the LO e to switch be

CCD. The HO O’s WFS Cam xel per subap ng is currently ws the design s stage suppo ng its distanc nsating differe ntial flexures a d, supported b e stage for ma trance Lens p ation purposes er to stop the i Rotator (the nstrument rotat m splitter reflec mera will be 3]. pil stabilizatio slet array. The ment error bet 0” field stop to mator lens rela

O’s WFS Cam the CCD (5.76 FoV of 5”. ion mirror on ane used fo decentering o lenslet array rs to the stroke mirror are the drift due to ween WFS and axis, PSF mirror rotation gnment errors al effects, and

xit pupil shift nts a mask fo eel hosting a calibration, a mal operation <mR<2 and 1 aying an imag ate for atmosp

configuration etween HO an O and LO cha mera (CCD22 erture in the 12x12 pixel p of the baselin orting the WF e with elevat ential focus p and thermal ex by the focus s aintenance; the producing a s. incoming beam same as NGS tor is operatin cting 1% of th probably rem on mirror on t e main contrib tween WFS an o accommoda aying an imag mera (CCD22 6 mm). It is th n r f y. e e o d F n s, d t. r a a

ns and two fil <mR<7 in the e of the pupil pheric dispers n.

nd LO SH le annels are imp 20) having 240 HO configur per subapertur

4. L

ne LGS WFS i FS board. The

tion and sod ositions with xpansion. stage, where a e alignment is F/20 beam a m to protect C WFS) to de-r ng in field trac he laser light to moved because the F/20 focal butors to the s nd instrument ate the elongat e of the pupil 20) including he same came Figure 5. lters to reduce e HO and LO on the SH len sion down to z enslet arrays a plemented as t 0x240 pixel fo ration (2.5”/6 re (0.21”/pix).

LGS WFS U

implementatio e stage is use dium profile e respect to SP all the WFS c s reproduced b and relaying CCD220 again rotate the actu cking mode. o feed a techn e of the recen l plane used f stroke requirem t rotator axis, ted image of th on the SH len a 40x40 lens era and SH arr NGS WFS unit

e the light lev configuration nslet array. z=70deg and a and related op two parallel ba format. It is th 6=0.42”/pix). .

UNIT

on. The main c ed for trackin evolution. Th PIFFIER and components ar by a set of mec the input foc nst over-illumi uator pattern o nical camera th ntly proven go for stabilize th ment of the m K-mirror and he sodium bea nslet array.

let array glue ray used for A t. The unit cove

vel and avoid ns) avoiding sensi ptics relaying arrels with a 4 he same camer In the LO c components a ng the best fo he travel of t d NIX, includ re mounted. T chanical refer cal plane to ination and ca of the DSM on

hat can be als ood performan he lateral dece mirror are the p d flexures. The acon. ed on the cam AOF, providin er is hidden to s CCD220 ove itivity reducti g the SH spot 40x40 and 4x4 ra used for A configuration and functions a ocus of laser the stage is ding the focus The board can rences. a tip-tilt mir alibrate dark fr n the SH lensl o used for LG nce of the 4L entering of th pupil plane la e mirror imple mera window w ng 6x6 pixel p how the conten

er-illumination on due to PSF ts to the WFS 4 SH arrays. OF, providing the 2.5” FoV are: beacon when also used for s drifts due to n be separated rror for pupi frames.

let array when GS acquisition LGSF pointing

e pupil on the ateral drift due ements a mask with the same er subaperture nt. n F S g V n r o d il n n. g e e k e e

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.5 locus stage Pupil mirrors K-rnirrors/ADC pos Stage position w IFS LGS slope offset

w- i.

_

o I Atipn ur

r__t 2f__,,_

nodes

nv/hIt off set

GS TT cmcl 1.1 Laser launch SPIFFIER metrology L. ,-K_,,,ro, 1.0 0.8 0.6 0.4 0.2 I I I NGS WFS rs/AIX position LUT1 K= 10 Defocus/coma omoaa s band: 2145 nm I I I TELES,OF: TGS-.1 20 GS TLR IGS TLR GS IGS SH 25 The LGS WF stabilization acquisition an 5.1 Control Figure 6-left WFSs are ope The real-time system) run w The frames o The DMS co command to WFS. SPAR vector to th vector from t DSM. SPAR successfully the DSM satu The frames o LO 4x4 co SPARTA an DSM tip-tilt v Vibration Can by ESO[10]. also reconstr SPARTA for particular the relocate the L higher order vector of the Among the a brevity, only Figure 6. Sc FS operates o are devoted nd drift trackin

5.

loops in LGS summarizes t erating in this e AO loop bet with a baseline of the LGS W ommand vect stabilize the L RTA sums the

he last availa the LO loop a RTA receive applied com uration check. of the NGS W nfiguration a nd processed vector implem ncellation alg The higher ructed and ti r the truth s e average NGS LGS WFS fo rs to update LGS WFS sig auxiliary loops a subset of t cheme of the rea

nly on-axis, t to the 4LGS ng, and a low

REAL-TI

S-mode the system of mode. The N tween the LG e maximum lo WFS Camera a tor does not LGS image in e DSM comm able DSM tip and send it to es back the mmand to man WFS Camera in are collected to compute menting the Ac gorithm develo orders terms ime averaged sensing loops S focus is use cus stage and the slope o gnals. s we cite here the most relev al-time and aux

therefore it do SF launcher, p stroke fast TT

IME AND

control loops NGS WFS is se GS WFS signa oop frequency are collected b include the t n the mand p-tilt o the last nage n the d by the ctive oped s are d by s. In ed to d the offset e, for vant: xiliary control lo Figur

oes not requir providing an T corrector.

AUXILIAR

s and look-up et in the LO c al, the DSM a y of 1 kHz. by SPARTA a tip-tilt compo oops in LGS mo re 7 Estimated p re stages to pa internal larg

RY CONTR

tables (LUTs onfiguration. and the laser l

and processed onent that is ode(left) and NG

performance in

atrol the field ge stroke field

ROL LOO

s) in LGS mod launcher jitter d to compute used to prod NGS mode (right Ks-band of the . LGS on-axi d steering mi

OPS

de. Both the L r mirror (part

the DSM com duce the laser

t) e ERIS AO syste s location and irror for LGS LGS and NGS of the 4LGSF mmand vector r jitter mirror em d S S F r. r

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a) the pupil position loop to keep pupil registered with the related SH arrays; b) the DSM averaged position loop to offload integrated focus/coma and higher orders to M2 hexapod and M1 active optics respectively; c) the k-mirror and ADC angles following the updating of the telescope elevation and instrument rotation angles; d) the image motion compensation loop updating an offset of the NGS WFS stages and periscope to compensate – with a pre-calibrated LUT as a function of elevation, instrument rotator angle and temperature – for the differential flexure between NGS WFS and the instrument, the NGS WFS k-mirror and periscope PSF induced wobble and the differential atmospheric refraction (NGS vs science target). When SPIFFIER is used, its internal metrology system can be used for computing an additional term in the differential flexure offset.

5.2 Control loops in NGS mode

Figure 6-right summarizes the system of control loops and LUTs in NGS mode. The scheme is similar to the LGS one disabling the loops that are LGS dependent.

6. AO SYSTEM PERFORMANCE

The ERIS AO system performance is computed in terms of Strehl ratio (SR) as a function of the NGS magnitude and it is shown in Figure 7 for the Ks band in comparison with the top-level requirements for both LGS and NGS modes. The curves have been obtained adding to the end-to-end numerical simulation results the wavefront error budget components that have not been directly included in the simulation. The numerical simulations have been provided by the PASSATA code developed at INAF-Arcetri[11]. The parameters of the numerical simulation are

shown in Table 1 and the additional terms of the wavefront error (WFE) budget are the following: • figuring error of DSM and M1 (after removing DSM correctable component)

• correction residual of Non Common Path Aberrations (NCPA) • pupil registration loop residual

• interaction matrix calibration noise • truth sensing residual error • residual vibration compensation

The total contributions of the budget for the NGS and LGS modes are 110 nm and 150 nm rms WFE respectively. They are dominated by an extremely conservative contribution of the residual vibration compensation of 83 nm and 113 nm rms, based on vibration data in a different focal station (VLTI) and without considering the effect of the Active Vibration Cancellation algorithm developed and successfully tested by ESO.

Table 1. Main simulation parameters

Parameter Value Seeing 0.87 arcsec (at z=30°)

Outer scale 22 m

Atmospheric layers 10 (std. Paranal profile)

Wind speed 12 m/s

NGS star type G2 (spectra from Pickles)

Telescope entrance pupil D = 8.12 m, 15.9% obs. H = 90 m below M1

Laser 1.2as WFHM including upward prop. Sodium profile “Single Peak” from Prommer&Hickson

Simulated elongation and downward propagation

DSM 1170 influence functions from FEA

WFS camera (CCD220) RON

Excess noise Dark

EMCCD 240x240 pix

80e- rms/G (G=EM gain, 1≤G≤400) proper avalange statistics

3.6 e-/pixel/s (fs≥900) 1.8 e-/pixel/s (900>fs≥500) 1.4 e-/pixel/s (500>fs≥360) 1.08 e-/pixel/s (360>fs≥180) LGS WFS subap FoV wavelength Pix/subap tranmission SH 40x40 subap 5 arcsec λeff = 589 nm (BW=40nm) 6x6 0.48 (including CCD QE) HO/LO NGS WFS subap FoV wavelength Pix/subap tranmission

SH; HO:4x4 subap; LO:4x4 subap 2.5 arcsec λeff = 768 nm (BW=600-1000nm) HO: 6x6; LO: 12x12 0.34 (including CCD QE) 107 detected ph/arcsec2/m2/s RTC (SPARTA) Max frame frequency Centroid algorithm Control base Total effective delay (in frame units)

HO: 1kHz; LO: 500Hz

Weighted CoG, gaussian weight map Karhunen–Loève modes fitted on the DSM influence functions

1 for f < 334 Hz

2 for 334 Hz < f < 667 Hz 3 for 667 Hz < f < 1000 Hz

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t

%... For each NG frequency, th The performa on-axis obse comparison w (mR=8) and L Considering INAF-Arcetri baseline SH W cited PWFS-b 7.1 Pyramid The PWFS d components a WFS, at leas Figure 9. Py S magnitude, e Gaussian siz ance shows a c rvations, the with the TLR r LGS (mR=12) the performan i AO group WFS with a P based AO sys d WFS upgra design option h are shown in st for the me ramid WFS com both in NGS ze of the WCo conservative S NGS magnit requirements mode, respect

7. THE

nce success o (e.g. FLAO a PWFS has be

tems are coup

ade opto-mech

has the same Figure 9, whe echanical part Figure 8. Com mponents and LGS mod oG weighting SR(Ks)=83% tude for sele show a contin tively.

E PYRAMI

of the Pyram at LBT[7] an een studied as pled with a DS hanics opto-mechani ere the ones h t. As for the mparison betwe

de, the numbe maps and the in the on-axis ecting the bet ngency of 150

ID WFS UP

mid WFS in o nd MagAO at part of the E SM sharing th ical interfaces having labels w baseline SH longitu perisco A diffe longer The re steering the PSF Close t This is Section apex an betwee After t wavele Due to placed match t On the focused

een SH WFS (lef er of correctin e CCD220 gain s bright end in tter performin 0nm and 100nm

PGRADE O

other AO syst t Magellan T ERIS prelimin e same techno s of the baseli with a thick f sensor the p udinal positio ope and an XY erent relay len focal ratio at lay lens creat g mirror that F. The angle to it, a doub based onto a n 4.8.3), but th ngles inside th en the ADC an he derotator, engths for targ o the very lon

after the dich the same conf other arm of d on a double-eft) and Pyrami

ng modes and n have been o n NGS mode a ng mode (LG m rms WFE in

OPTION

tems develope Telescope[8]), nary design. T ology of the V ine SH WFS ( frame share th atrolling of t on is achiev Y stage. ns has been d t the pyramid tes a pupil im produces the of incidence o le counter-rot similar design he larger pupi he prisms. Th nd the focal pl a dichroic be get acquisition ng focal ratio, roic to shorten figuration of th the beam-spli -pyramid[12] d WFS (right). related loop g optimized. and 60% in L GS/NGS) is m n the bright en ed and exper an upgrade To be noted th VLT-UT4. (see Figure 8) he same desig the FoV in tr ved by usin designed to ac d (F/42.5 inst mage of 16mm fast angular m on this mirror tating prism n of the SH N il diameter re he derotator p lane. eam splitter re n to an acqui , a focal redu n the focal rat he SH NGS W itter, the trans

placed togeth

gains, the loop GS mode. For mR=13.7. The nd of the NGS

rienced by the option of the hat both of the

). The interna n with the SH ransversal and ng a rotating ccommodate a tead of F/20) m over a fas modulation o r is 45 degree acts as ADC NGS WFS (see quires smaller rism is placed eflects shorter sition camera ucer doublet is tio to F/20 and WFS. smitted light is her with a field p r e S e e e al H d g a ). st f e. C. e r d r a. s d s d

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0.9 0 n7-Vl " 0.6 0.5 0.4 6 8 Ks band: 2145 nm i i l i i i l i i i i i l i i il i i i 10 12 NGS mR co

Integration time reduction factor

I iiiI iiiI ii

iii LGS TLR NGS TLR LGS NGS SH A AANGS PYR and and and r r r 0 11 11 NGS magF 0.8 0.6 Ñ 0.4 0.2 1 I I 13 14 H band: 1859 nm i I i i I 1 I 15 NGS mR LGS TLR NGSTLR o oLGS o oNGSSH nANGS PYR PWFS seeing tc 0.8 as 0.2 0.0 Dhave SR(PYR(seeing))= li iiiiiiil 11 11111111 1 10 11 NGS mR J band: 1285 nm 15 NGS mR =SR(SH(0.37)) 2 13 D LGS TLR D INGSTLR 3 oLGS , oNGS SH D ANGS PYR 25 stop at the F images have t increase the n error contribu The NGS LO diameter to av in the final de 7.2 Pyramid Figure 10-lef simulation pa ranges betwe PWFS, comp The PWFS in the LGS curv The increase reduction of exposure time The same inc larger value o which the PW Figure 10 Co bands Figure 11 L seeing used F/42.5 focal p the correct sam number of sub ution in the rec O configuratio void summing esign phase. d WFS upgra ft compares th arameters are en 2 and 3 λ/ pressing the SR ncreases the S ve of about 1 m of PWFS SR exposure tim e reduction fa crease of SR c of seeing and, WFS produces omparison betw Left: exposure ti d by PWFS (soli lane. Finally, mpling of 40x b-apertures up construction p on can be ach g up dark curr ade performa he numerical the same of t /D. The same R performance SR(Ks) at the magnitude. Fig with respect t me to obtain t actor, reaching can be used w , consequently s the same SR ween performan ime reduction f id curve) provid a pupil relay x40 pixels. Th p to the limit o process. hieved by swit

rent and RON

ance simulations o the Table 1 w conservative e in the bright crossing mag gure 10-cente to SH WFS pr the same SN g a value more with the PWFS y, for a larger R of the SH W nce of SH and P

factor for backg ding the same S

y lens (a tripl he compactnes of the SPART tching to a di N contributions of the PWFS with the additi

contribution o t-end. gnitude from

r and right sho roduces a larg NR in backgro e than 2 in J ba S to have the s fraction of ni WFS when the Pyramid WFS in ground limited o SR of the SH WF let) reimages ss of the PWF TA RTC capa ifferent camer s. Optical desi with respect ional paramete of the WFE b 60% to 70% ow the corresp ger fraction of ound limited and. same SR resul ights. Figure e latter is perf n the NGS-mod observations of FS case with 0.8

the four pup FS signal on th abilities to eve

ra lens set-up ign for such c

to the SH W er of the PSF udget reporte with a corres ponding resul f energy in the observations. lts of the SH W 11-right show forming with de for Ks (left), H f PWFS with res 87as seeing (da

ils onto the d he CCD area c en better reduc p reducing the onfiguration w WFS in the NG modulation a d in Sec. 6 is ponding faint lts in J and H b e central peak Figure 11-le WFS at a give ws the seeing ( a median see H (center) and spect to SH WF ashed curve). detector. Pupi could allow to ce the aliasing e pupil images will be studied GS-mode. The amplitude tha applied to the ter crossing o band. that turns in a eft reports the en seeing for a (solid line) for eing of 0.87as J (right) FS. Right: il o g s d e at e f a e a r s.

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The PWFS can produce the same results with seeing above 1as.

The high contrast applications show even more interesting results, because of the well-known ability of the PWFS in a better rejection of the aliasing error. Figure 12-left shows the radial profile of the speckle noise computed from rms of difference of uncorrelated pairs of L’-band PSFs with 1.6s exposure time each, during AO bright-end on-axis correction. No coronagraphy is used in the simulation and the PSF binning has been set to 0.1x0.1as2. The PWFS speckle noise is about 3 times less than SH in the TLR requirement area between 3 to 7 λ/D. The curves, of course, superimpose beyond the AO control radius. The speckle noise is the dominant term below 3 λ/D in the SNR of detection of a faint companion for a simulated ADI observation, while the background noise dominates for larger radial distance. We assumed a background brightness mL’=3.9 mag/arcsec2[13] in the simulation. Figure 12-right reports the detection SNR in 1h of a ΔmL’=10 (TLR requirement) and ΔmL’=12 companion for both Pyramid and SH WFS without coronagrafy. The SNR threshold required by TLR is SNR=5 in 1h showing that the PWFS pushes the performance in a closer region (around 2 λ/D) with fainter companion (ΔmL’=12) with respect to the minimal TLR requirements.

8. CONCLUSIONS

The ERIS Consortium has taken the lead of the 1-5μm ERIS instrument development beginning 2015. The Preliminary Design Review has been successfully met in February 2016 and now the project is in the Final Design Phase.

The ERIS AO system design makes a large re-use of AOF technology to save development and implementation time: the Deformable Secondary Mirror, the 4LGS Facility, the WFS Cameras (EMCCD) and the SPARTA RTC.

The pre-optics design, based on flat or almost-flat optics, has driven by providing high stability of NCPA and alignment decoupling with respect to the science instruments NIX and SPIFFIER.

The required observing modes (LGS, NGS and Seeing Enhanced) are implemented with the use of two SH WFSs units. The on-axis LGS-only WFS board implements the 40x40 SH with 5as FoV and is located on a linear stage for Na layer tracking. The NGS-only WFS is able to switch between a HO (40x40 SH, 2.5as FoV) and a LO (4x4 SH, 2.5as FoV) configuration for the NGS and the LGS mode respectively. The LO configuration provides also the truth sensing function for the LGS WFS focus and slope offset tuning. The NGS WFS board is located on a dual-axis stage to patrol the R=1arcmin acquisition field (together with the on-board periscope) and the compensation of the differential focus with respect to the science instruments.

The numerical simulations and analysis show that the SR requirements required by the TLRs are met with a contingency of 150nm and 100nm rms WFE in the bright end of the NGS (mR=8) and LGS (mR=12) mode, respectively.

In order to push the performance of the ERIS AO, especially in the high-contrast regime, an upgrade of the NGS WFS to the Pyramid WFS has been proposed. The PWFS unit has been designed to have the same opto-mechanical interfaces as the SH WFS with sensitive better SR performance of SH WFS, especially at short wavelengths (J and H bands). In the

Figure 12 Left: Radial profile of the speckle noise (see text). Right: detection SNR vs distance from central star (see text).

high contrast applications allows to push the faint companion detection performance for inner angles (2 λ/D) with fainter companions (ΔmL’=12).

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REFERENCES

[1] Madec, P.-Y., et al. “Adaptive Optics Facility: control strategy and first on-sky results of the acquisition sequence,” Proc. SPIE 9909, in this proceedings (2016).

[2] Briguglio, R., Biasi, R., Xompero, M., Riccardi, A., Andrighettoni, M., Pescoller, D., Angerer, G., Gallieni, D., Vernet, E., Kolb, J., Arsenault, R., Madec, P.-Y., “The deformable secondary mirror of VLT: final electro-mechanical and optical acceptance test results,” Proc. SPIE 9148, p. 914845 (2014).

[3] Hackenberg, W. K., et al. “ESO 4LGSF: Integration in the VLT, Commissioning and on-sky results,” Proc SPIE 9909, in this proceedings (2016)

[4] Taylor, W. D., et al. “NIX, the imager for ERIS: the AO instrument for the VLT,” Proc. SPIE 9909, in this proceedings (2016).

[5] George, E. M., et al. “Making SPIFFI SPIFFIER: upgrade of the SPIFFI instrument for use in ERIS and performance analysis from re-commissioning,” Proc SPIE 9909, in this proceedings (2016).

[6] Dolci, M., et al. “Deign of the ERIS calibration unit,” Proc. SPIE 9909, in this proceedings (2016)

[7] Esposito, S., Riccardi, A., Pinna, E., Puglisi, A., Quiros-Pacheco, F., Arcidiacono, C., Xompero, M, Briguglio, R., Agapito, G., Busoni, L, Fini, L., Argomedo, J, Gherardi, A, Brusa, G., Miller, D., Guerra, J. C., Stefanini, P., Salinari, P., “Large Binocular Telescope adaptive optics system: new achievements and perspectives in adaptive optics,” Proc. SPIE 8149, p. 814902 (2011).

[8] Morzinski, K., et al. “MagAO: status and science,” Proc. SPIE 9909, in this proceedings (2016)

[9] Pfrommer, T., Hickson, P., “High resolution mesospheric sodium properties for adaptive optics applications,” A&A 565, p. A102 (2014)

[10] Muradore, R., Pettazzi, L., Fedrigo, E., Clare, R., “On the rejection of vibrations in Adaptive Optics Systems,” Proc. SPIE 8447, p. 844712 (2012)

[11] Agapito, G., Puglisi, A. and Esposito, S., “PASSATA: object oriented numerical simulation software for adaptive optics,” Proc. SPIE 9909, in these proceedings (2016).

[12] Tozzi, A., Stefanini, P., Pinna, E., and Esposito, S., “The double pyramid wavefront sensor for LBT,” Proc. SPIE 7015, 701558, (2008).

[13] https://www.eso.org/gen-fac/pubs/astclim/paranal/skybackground/

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