FLAO system test plan in solar tower

S. Esposito, G. Brusa, L. Busoni

FLAO system external review, Florence, 30/31 March 2009

FLAO system external review, Florence, 30/31 March 20092

LBT672 long focus plane

The test facility

1370

0mm

Lab

F/15 input beam from reference source or interferometer

13700mm

1060mmLBT672 short focus plane

LBT672 thin shellThe optical test of the LBT672 and of the FLAO system is done using a double pass configuration. A retroreflecting optics is used to reflect the light at the secondary mirror short focus. Light source can be the interferometer or the WFS internal reference source.

Retro-reflecting optics

F/1 parabola 30mm diameter

FLAO system external review, Florence, 30/31 March 20093

FLAO test tasks listTask name Days Description Milestone Success criteria

FLAO integration in solar tower

17 Alignment of LBT672 and W unit. FLAO system aligned

Alignment achieved:

a) WF error <= 120nm rms (FLAO_09)

b) W optical axis misalignment <= 2 arcmin (FLAO_09)

FLAO optical alignment

FLAO test: Phase I

50 a) Initial calibration & closed loop test with FLAO.

b) FLAO Control SW debugging

FLAO system operated in closed loop with control SW

a) Closed loop with 200 modes.

b) FLAO system configured via control SW

IRTC installation & alignment

9 Installation and alignment of IRTC with FLAO.

SR optimization of IRTC.

IRTC aligned and

non common path aberration corrected.

SR value for IRTC in H band measured >=70%.

FLAO test; Phase II

48 a) Complete calibration of FLAO. Optimization of system configuration to achieve the best SR.

b) Observing modes test & performance evaluation (ACE mode)

FLAO performance compliance with acceptance test specifications.

SR values >= baseline values defined in FLAO_06

Acceptance test

12 FLAO system acceptance test FLAO performance complaiant with acceptance test

FLAO performance better than baseline performance defined in FLAO_06

Duration of solar tower test is 141 days

FLAO system external review, Florence, 30/31 March 20094

Task #1: system integration & alignment

Alignment phase I (FLAO_09):to position the adaptive secondary so that the axis of the unit is passing from the retro-reflecting optics focal point and the focus of the WFS Unit reference source. This condition ensures that the off-axis aberrations due to the secondary mirror are null. Preliminary alignment of retro-reflector [AD17] is assumed.Alignment phase II(FLAO_09):To position the optical axis of the W unit to be coincident with the optical axis of the secondary mirror. This condition ensures that the pupil images are stable when the pupil rotator is operated. This condition will be reached by tilting the WFS board with respect to the translation stages unit.

1. The two mentioned axes are coincident with an error less than 2 arcminutes. This is to ensure the proper optical configuration of the WFS. 2. The total wf error seen at the WFS location should be not larger then the initial DM best flat figure. In any case it should be less then 120nm RMS.

Task#2: closed loop Phase I

FLAO system external review, Florence, 30/31 March 20095

1. Loop closed with 200 modes.

2. FLAO control SW: startup all the system HW and SW, in particular the adaptive secondary mirror (DM) and the W unit (WFS).

3. FLAO control SW: configuration of the two units (DM and WFS) is done automatically from input parameters: star coordinates & magnitudes, r0, v0. The system configuration will be calculated from look-up tables created using numerical simulations.

Summary: initial test and verifications of main system components and procedures. Complete debug of FLAO control SW including interaction with TCS simulator.

FLAO system external review, Florence, 30/31 March 20096

Task#3: InfraRed Test Camera (IRTC) installation & alignment

After alignment and NCP aberration corrections the SR in H band has to be better than 70%.

Non Common Path (NCP) aberrations correction

We plan to test various techniques to optimize the SR of the IRTC: 1. Curvature sensing (NOAO SW package?)2. Temporal modulation of low order modes.3. Phase diversity

FLAO system external review, Florence, 30/31 March 20097

Task#4: closed loop test Phase II

System performance R0 = 0.8”, v=15m/sClosed loop performance test:

1. Engineering mode (baseline)

2. Observing modes (a,b baseline, c goal)

a. Field Stabilization Mode (FSM). In this mode only tip-tilt is corrected using the W sensor tilt measurements.

b. Automatic Configuration modE (ACE/ICE). In this mode the reference star co-ordinates, the star magnitude and the r0 and v0 parameters will be provided to the system. The AO supervisor will configure the AO system using look-up tables.

c. ACE with on sky optimization of system parameters .

Same as above. FLAO system parameters are optimized after acquisition of some WFS frames on sky. Adjustable parameters are: system gain, number of corrected modes.

Task Summary: Fine calibration of the system. System performance test vs. input parameters: star magnitude, r0, v0. Modification of system look-up tables. Test of performance achieved in engineering mode & automatic configuration mode (ACE).

FLAO system external review, Florence, 30/31 March 20098

Task#5: FLAO acceptance test

Repetition of a specific set of tests already done in phase II (see FLAO_06)

Test list:1. system performance

a. engineeringb. FSMc. ACE

2. full control SW test (including IRTC control GUI). 3. mode offloading to hexapod

FLAO system external review, Florence, 30/31 March 20099

FLAO test activity managment

ASM group involved in the test of the LBT672b. Required manpower to be quantified and considered in the management table (20/03-19/06).

The required manpower is found compatible with the available resources of the group.Two new person have joined the group: a phd student and a post-doc.

Conclusion

-A test plan describing the various activities of the FLAO solar tower test has been done.

-A set of milestones has been defined to track progress of the test phase.

-Criteria for milestone achievement have been set.

-The manpower required for the test campaign has been quantified and found compatible with the overall group resources.