W Unit Opto-Mechanical Acceptance Test Specifications

A.Tozzi, E.Pinna, S.Esposito

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

FLAO_03 (CAN: 687f002e)

FLAO system external review, Florence, 30/31 March 2009 2

Contents

1. Cooling Line test2. Electronic boxes test:

• Box39, box47, Motor box functional test• Auto Power Off• Thermal test

3. WFS board internal reference source & Pupil images optical configuration

4. W unit hardware performance test:• Main optics (Tip Tilt mirror, Pyramid, Camera Lens)• Secondary optics (Filter Wheel #1 and #2, pupil re-rotator, ADC)

5. Translation stages test:• Stage limit switches • Stage positioning accuracy• WFS avaible FoV

6. Flexure unit test7. W unit sensor/acquisition CCDs test8. Reference star acquisition sequence

Slide#

Acceptance test report docs are

W#1: 687s001, W#2: 687s002

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1 – cooling line

Preliminary test with air *.Test condition: compressed air at 10 Atm: Test result: value stable for 12 hours.

Operative glycol cooling system.Test condition: off-axis system not attached. On axis cooling

plates attached.Test result: flow rate of 3 liter/minute

Ref: p.9 FLAO 03 doc

* Test realized before acceptance test

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2 – Electronic box test

Box39, box47, Motor box functional step/test:• main 110Vacis powered on by telescope control • System rele operation: ADC, Filter Wheels, Pupil ReRotator, Fans, CCDs, XYZ stages,• Filter Wheels correct filter selection and homing• ADC motor moves properly and homing,• TT signal generator working,• WFS CCD is responding and configurable,• Technical CCD is responding and configurable,• BCU39 computation working for different binning modes,• Internal Reference Source is working,• Power on/off of the three translation stages, limit switches work.

Auto Power Off:Test condition: cooling line is stopped, W unit working. Test result: W unit automatically switches off when temp. threshold is reached

Thermal test:Test condition: W unit is working for 4 hours, cooling line ΔT=-2.5°CTest result: 1) W unit external surfaces uniformity <1°C.

2) Internal box temperature less then 50°C

Ref: p.9-11 FLAO 03 doc

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3 – WFS light source & Pupil images optical configuration

f/number test *: Test condition: W unit working, internal ref. source on, auxiliary CCD is used Test result: f/# = 14.5 +/- 0.15

Pupil geometry test: Test condition: W unit working, internal ref. source on Test result: 1) pupil diameter: 31.0 +/- 0.1 pixel 2) pupil center distance: 36.0 +/- 0.1 pixel

Ref: p.11-12 FLAO 03 doc* Test realized before acceptance test

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4 – W Unit hardware performance test

Tip Tilt test *:Test condition: W unit working, auxiliary CCD on PSF f/45

Test result: amplitude vs freq. (50-1000 Hz) is measuredPyramid test *:

Scratch vertex Pyr1 <10µm, scratch edges <5µm, angles error <15”Camera lens test:

Test result: pupil shift of 4 pix in X,Y directions. Accuracy of 0.1 pix

Filter wheel #1 test *: Test result: PSF displacement < 47masFilter wheel #2 test *: Test result: Non critical (PSF position repeatability < 47mas)Pupil Rerotator test: Test result: 1) PSF displ. <9µm (5mas), PUP displ. <0.1pix @ 1.25° RR (10minutes)

2) PSF displ. <900µm (500mas), PUP displ. <+/-2 pix @ 0-360° RR ADC test *:

Test condition: W unit working, ADC works for Z=(0°,70°), CCD47 used Test result: 1) PSF FWHM matches the DL configuration

2) PSF baricenter displ. < 5 mas

Main optics

Secondary optics

Ref: p.12-15 FLAO 03 doc* Test realized before acceptance test

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5 – Translation stage test

Stage positioning:Test condition: W unit working, TT loss = ±1/15 full range, ext. gaugeTest result: 1) after homing the X,Y accuracy has to be < ±23.4µm (39mas)

2) after homing Z accuracy has to be <100µm

Stages range (FoV):Test condition: W unit workingTest result: 1) FoV center measured with respect the AGW within 1 mm 2) FoV >= [3.2, 2.3 arcmin]3) FoV center coord. = [0.55, 0.15 arcmin]

Ref: p.15-16 FLAO 03 doc

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6 – Flexure unit test

PSF, PUP displacement *: Test condition: AGW on telescope simulator (AIP) / Solar tower, external

reference source working. Test result: 1) PSF displ. <9µm (5mas), PUP displ. <0.1pix @ 1.25° RR (10min)

2) PSF displ. <2”, PUP displ. <+/-2 pix @ 0-360°

Ref: p.17-19 FLAO 03 doc* Test realized before acceptance test

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7 – W unit sensor CCDs test

W sensor CCD test:Test condition: W unit working, CCD39 coveredTest result:

W technical viewer CCD test:Test condition: W unit working, CCD47 coveredTest result:

Ref: p.19-20 FLAO 03 doc

acc.test W#1: 687s001

acc.test W#2: 687s002

Pixel rate [Kpix/s]

Baseline RON [e-]

Goal RON [e-]

2500 10.8 8.4

890 8.0 5.8

400 5.0 4.5

150 3.5 3.5

Pixel rate [Kpix/s]

Baseline RON [e-]

Goal RON [e-]

2500 45 8.4

250 45 5.8

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8 – Ref. star acquisition sequence

Acquisition sequence:Test condition: W unit working, CCD47 operatingTest steps/result: 1) reference star is placed out from the CCD center

2) Automatic procedure is started3) Star is centered with residual error <

±23.4µm (±39 mas)

Ref: p.20 FLAO 03 doc

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conclusions

W Unit Acceptance test specifications:

In FLAO 03 (CAN 687f002e) are resumed specs for:

• Optical setup• Mechanical setup• Electronic setup

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Questions1

Questions by R. Arsenault (26 March 09): .

Q1) Any servicing on the electronics appears cumbersome to carry out.A) The servicing seems not to be simple. But take into account that the electronic boxes (Box39, box47)

can be removed from the AGW structure and you can test them only attaching 110 Vac and RJ45 Ethernet on a desk. For the Box47 you need a spare connection cable, too. Not only: but you can remove the external shell (13 screws) and the electronics component can be checked during operation on a normal desk.

The problem is related to an ancient decision: to have commercial components and to install them into the AGW structure. It may helps telling you that, for example, I have substituted the BCU39 in less one hour having the system completely assembled…

Q2) Is a US 110 V 60 Hz being simulated in Arcetri for tests? A) for the AGWs we have used or a little 220 to 110 transformer (50Hz) or the 110 Vac 60Hz Solar tower

supplies (The same used for the LBT672).

Q3) Differences between W1 and W2 (p10 steps C1 and C2) P10 section 4.1: steps 2, 3,4 ; is anything being measured ? what ? Or do these tests aims simply at testing the rotation/movement of the

devices when commanded by soft.A) Yes. In this phase of the acceptance test we looked at the functionality of the different electronics

devices and nothing else.

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Questions2

Q4) For most tests listed in this section, the actual measured parameter is not always clear, and against what will the measured value be compared. It is not very clear that after conducting all these steps that the validation of the electronics is assured.

A) The tests list you find in section 4.1 is a list of the items present in the W unit. The idea is to check at their functionality. Perhaps a matrix with device/tests would be useful (We’ll prepare it).

Q5) P11 sectoin 4.2; step 1. Can the cooling fluid flow be adjusted on the telescope to insure “optimal value for the operating conditions”

A) Yes, you can. The only thing that is really important is the flow rate in the On axis unit, that it means to have the correct differential pressure value between the cooling Inlet and outlet. We have some spilling valves into the short cooling lines to adjust the single impedence.

Q6) P12 section 7: step 1 second paragraph; this alignment is provided by the tilt stage ? please confirm.A) Yes. The TT is used to refine the PSF position. Not only in this situation.

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Questions3

Q7) p.14: 2 pyramids are used why? To increase deflection angle of the 4 pupils ?Mainly for two reasons:1) with two pyramids you can polish them having bigger angle values (30 deg instead of 2 deg in the single

one). This difference helps us to guarantees a smaller scratched vertex/edge and so to have a less lost light value.

2) with two pyramids you can correct the chromatic behaviour of the single one expecially when the incoming one is 30 deg. (see SPIE article: A. Tozzi, P.Stefanini, E. Pinna, S.Esposito,”The Double Pyramid wavefront sensor for LBT”, Proc. of SPIE Vol. 7015, 701558, (2008)).

Q8) p.16 section 8.1; requirements for stages are clear but test procedure not defined.A) Perhaps it is not clear. At point 1 we say that after the homing command we give to the stages, using the

GUI, a position command. After this we measure, using an external gauge (in case DIGITO12 of Mahr Inc.), the accuracy of the position repeating the procedure many times, five normally. (see 687s001 or 687s002).

Q9) p.21 section 13. I believe the duration quoted in this chapter for individual tests but any problem, issues will delay and they will be numerous. An estimation is 2 wks for these tests appears more reasonable.

A) It may be! For the first acceptance test we scheduled approximately 2 weeks, but there are to points to consider:

1) some of the test presented in this doc have done “offline”, before the acceptance test, writing a report. See ADC, RR, Filter Wheel, Tip Tilt.

2) So doing in the last W#2 acceptance test (march 2009) we have really scheduled only one week (from Monday to Friday) and we have done all the test easily. We have cooled the whole AGW using a fridge truck, too (see 687s002).

Thank you for your questions and comments. We’ll insert your suggestions in the following release of the document