Wind and snow all night long. Closed dome testing with swing arm to check the TipTiltOffsetLookupTable

LUCI spinning and tt offset LUT check

System is setup to be able to measure star and mask position on LUCI (see HowToSetUpForLUCIOffsetCalibration)

The 2 systems were setup in different configurations: SX has CCD39 running at 200Hz with a modulation of 1.60V ptv, while DX has CCD39 running at 105Hz with modulation of 1.49V ptv

Pointing error measurement

Several rotator full rotations are done with a LUCI scripts (see FlexComp_Calib30.xml) that rotates in steps of 30deg and acquires LUCI images. SR has a program to analyze the data and fit the pointing error (defined as star_position - mask_position). The attached files (L1_X_avg_wobble.fits,L1_Y_avg_wobble.fits,L2_X_avg_wobble.fits, L2_Y_avg_wobble.fits) are the pointing error for LUCI1 and LUCI2 measured between -90 and 450 deg in steps of 30 deg.

Calibration of TT offsets to LUCI delta pointing.

On SX side:

Piezo TT offset star_position mask_position notes
(0,0) (942.68, 1089.60) 924.08, 516.67 Rot=341
(1,0) (941.08, 1090.42) 924.13, 516.66 Rot=341
(2,0) (939.38, 1091.15) 924.06, 516.65 Rot=341
(-2,0) (946.02, 1088.33) 924.04, 516.64 Rot=341
(0,2) (944.23, 1092.64) 924.08, 516.66 Rot=341
(0,-2) (941.17, 1086.57) 924.10, 516.63 Rot=341
(0,0) (942.66, 1089.58) 924.13, 516.68 Rot=341

where the offsets are in Volts, star and mask position are pixels in LUCI 3.75 camera. The mask position is the position of the image of one (always the same!) hole of the N30 field stop mask

From the measurements with offset of 2V we derive the calibration

IM (px/V)
-1.66 0.765
0.705 1.5175

REC (V/px)
-0.496 0.25
0.23 0.543

On DX side we repeat the same procedure:

Piezo TT offset star_position mask_position notes
(0,0) (981.34, 1054.14) 947.23, 526.42 Rot=210
(2,0) (982.88, 1057.16) 947.17, 526.45 Rot=210
(-2,0) (979.68, 1051.10) 947.17, 526.46 Rot=210
(0,2) (984.61, 1052.50) 947.14, 526.39 Rot=210
(0,-2) (977.97, 1055.71) 947.16, 526.40 Rot=210

p00=np.array([981.34, 1054.14])
p20=np.array([982.88, 1057.16])
pn20= np.array([979.68, 1051.1])
p02= np.array([984.61, 1052.5])
p0n2= np.array([977.97, 1055.71])
im=np.zeros((2,2))
im[:,0]= (p20-pn20)/4
im[:,1]= (p02-p0n2)/4
rec= np.linalg.pinv(im)

IM (px/V)
0.8 1.66
1.515 -0.8025

REC (V/px)
0.25420507 0.5258323
0.47990117 -0.25341316

Look up table

We create the LUT for TT offset SX:
rec1= np.array([[-0.49617853,  0.25013283], [ 0.23051457,  0.5427719]])
l1x=pyfits.getdata('/home/argos/Downloads/L1_X_avg_wobble.fits')
l1y=pyfits.getdata('/home/argos/Downloads/L1_Y_avg_wobble.fits')
delta= np.array([l1x, l1y])
angle= np.arange(19)*30 -90
lut1= np.vstack((angle, -1. * np.dot(rec1, delta))).T
np.savetxt('tt_offset.txt.l1.170509', lut1, fmt='%10.3f')

Same for DX:
rec2=np.array([[ 0.25420507,  0.5258323 ],[ 0.47990117, -0.25341316]])
l2x=pyfits.getdata('/home/argos/Downloads/L2_X_avg_wobble.fits')
l2y=pyfits.getdata('/home/argos/Downloads/L2_Y_avg_wobble.fits')
delta= np.array([l2x, l2y])
angle= np.arange(19)*30 -90
lut2= np.vstack((angle, -1. * np.dot(rec2, delta))).T
np.savetxt('tt_offset.txt.l2.170509', lut2, fmt='%10.3f')

Files are attached and committed in the svn

Look up table check

We repeat the same procedure used above to estimate the pointing error, but with the LUT enabled.

We have 2 LUT availables:

  • 170501: LBTO LUT. Measured with FLAO in bin1 and LUCI N30 camera. Files are in svn: svn.lbto.org/repos/aosupervisor/confcalib/calib/wfs/W1/tt_offset/tt_offset.txt.l1.170501 and svn.lbto.org/repos/aosupervisor/confcalib/calib/wfs/W2/tt_offset/tt_offset.txt.l2.170501
  • 170509: ARGOS LUT. Measured with FLAO in bin4 using ARGOS SW and LUCI N3.75. Procedure is described above. Files are in svn: svn.lbto.org/repos/aosupervisor/confcalib/calib/wfs/W1/tt_offset/tt_offset.txt.l1.170509 and svn.lbto.org/repos/aosupervisor/confcalib/calib/wfs/W2/tt_offset/tt_offset.txt.l2.170509

The history of this measurements is the following:

Measure LUT Setup Result Notes
Measure 1 170501 ?? SX_ROTANG.pdf doesn't work. Done on 20170506 by MB ans IG. AO configuration ?
Measure 2 170509 200Hz SX_ROTANG_2.pdf, DX_ROTANG_2.pdf both SX and DX
Measure 3 170509 750Hz SX_ROTANG_3.pdf to check the effect of the modulator frequency
Measure 4 170501 750Hz SX_ROTANG_4.pdf Repeation of Measure 1 to re-check LBTO's LUT. It works well

Measure 1 configuration and AO setup is not well known? (see NightTime20170505). We probably did an error during the acquisition (?), but the results were not good with a residual of about 5-6 px on SX (see SX_ROTANG.pdf)

Measure 2 was done to test ARGOS LUT. Results are similar to the ones reached by Doug on LUT 170501: the pointing error is reduced by about a factor 10 on SX leaving a ptv residual of about 0.1" (1px on N3.75) over the entire rotator range. On DX, that has a better alignment, the ptv residual is anyhow of the same order, slightly better than 1px See psf_XY_luci1_plot.png psf_XY_luci2_plot.png

and the following plots SX_ROTANG_2.pdf, DX_ROTANG_2.pdf

Measure 3 was done to check a possible dependency on TT modulator frequency, and it was done on SX only at 750Hz with the LUT 170509 (measured at 200Hz). See SX_ROTANG_3.pdf: the correction is as good as in Measure 2

We then realized that the difference between the 2 LUTs is really minimal. See LUTs_compared.png

So we decided to repeat Measure 1 using LBTO LUT in a more controlled way. The results are good (see SX_ROTANG_4.pdf), consistent with the ones found by Doug in email of 170501

Conclusions so far:
  1. LBTO's LUT and ARGOS LUT are pretty much the same, (the one of ARGOS is rougher, yet!)
  2. Both LUTs work fine in day-time with a residual pointing error of about 0.1"
  3. There is no dependency on modulation frequency.
  4. We are still missing a good test on sky. The LUT 170501 was used on-sky in the past nights without success, but the reason is not clear (?)

Attachments

Topic attachments
I Attachment Action Size Date Who Comment
DX_ROTANG_2.pdfpdf DX_ROTANG_2.pdf manage 21 K 09 May 2017 - 07:23 LorenzoBusoni Wobble on LUCI
DX_ROTANG_TT_OFF_2.txttxt DX_ROTANG_TT_OFF_2.txt manage 13 K 09 May 2017 - 07:23 LorenzoBusoni Wobble on LUCI
DX_ROTANG_TT_ON_2.txttxt DX_ROTANG_TT_ON_2.txt manage 12 K 09 May 2017 - 07:23 LorenzoBusoni Wobble on LUCI
FlexComp_Calib30.xmlxml FlexComp_Calib30.xml manage 43 K 09 May 2017 - 11:24 LorenzoBusoni LUCI scripts to rotate in steps of 30deg and acquire. from Dave Thompson
L1_X_avg_wobble.fitsfits L1_X_avg_wobble.fits manage 5 K 09 May 2017 - 06:12 LorenzoBusoni Wobble on LUCI and TT offset LUT
L1_Y_avg_wobble.fitsfits L1_Y_avg_wobble.fits manage 5 K 09 May 2017 - 06:12 LorenzoBusoni Wobble on LUCI and TT offset LUT
L2_X_avg_wobble.fitsfits L2_X_avg_wobble.fits manage 5 K 09 May 2017 - 06:12 LorenzoBusoni Wobble on LUCI and TT offset LUT
L2_Y_avg_wobble.fitsfits L2_Y_avg_wobble.fits manage 5 K 09 May 2017 - 06:12 LorenzoBusoni Wobble on LUCI and TT offset LUT
LUTs_compared.pngpng LUTs_compared.png manage 59 K 09 May 2017 - 11:49 LorenzoBusoni Comparison of the 2 LUTs
SX_ROTANG.pdfpdf SX_ROTANG.pdf manage 13 K 09 May 2017 - 07:23 LorenzoBusoni Wobble on LUCI
SX_ROTANG_2.pdfpdf SX_ROTANG_2.pdf manage 19 K 09 May 2017 - 07:23 LorenzoBusoni Wobble on LUCI
SX_ROTANG_3.pdfpdf SX_ROTANG_3.pdf manage 20 K 09 May 2017 - 10:55 LorenzoBusoni 3rd measurement at 750Hz
SX_ROTANG_4.pdfpdf SX_ROTANG_4.pdf manage 19 K 09 May 2017 - 11:22 LorenzoBusoni Measurement 4 with LBTO's LUT
SX_ROTANG_TT_OFF.txttxt SX_ROTANG_TT_OFF.txt manage 2 K 09 May 2017 - 07:23 LorenzoBusoni Wobble on LUCI
SX_ROTANG_TT_OFF_2.txttxt SX_ROTANG_TT_OFF_2.txt manage 11 K 09 May 2017 - 07:23 LorenzoBusoni Wobble on LUCI
SX_ROTANG_TT_ON.txttxt SX_ROTANG_TT_ON.txt manage 4 K 09 May 2017 - 07:23 LorenzoBusoni Wobble on LUCI
SX_ROTANG_TT_ON_2.txttxt SX_ROTANG_TT_ON_2.txt manage 12 K 09 May 2017 - 07:23 LorenzoBusoni Wobble on LUCI
SX_ROTANG_TT_ON_3.txttxt SX_ROTANG_TT_ON_3.txt manage 13 K 09 May 2017 - 10:55 LorenzoBusoni 3rd measurement at 750Hz
SX_ROTANG_TT_ON_4.txttxt SX_ROTANG_TT_ON_4.txt manage 12 K 09 May 2017 - 11:22 LorenzoBusoni Measurement 4 with LBTO's LUT
psf_XY_luci1_plot.pngpng psf_XY_luci1_plot.png manage 141 K 09 May 2017 - 10:59 LorenzoBusoni pointing accuracy with and without LUT. Measurement 2
psf_XY_luci2_plot.pngpng psf_XY_luci2_plot.png manage 173 K 09 May 2017 - 10:59 LorenzoBusoni pointing accuracy with and without LUT. Measurement 2
tt_offset.txt.l1.170509170509 tt_offset.txt.l1.170509 manage 627 bytes 09 May 2017 - 06:12 LorenzoBusoni Wobble on LUCI and TT offset LUT
tt_offset.txt.l2.170509170509 tt_offset.txt.l2.170509 manage 627 bytes 09 May 2017 - 06:12 LorenzoBusoni Wobble on LUCI and TT offset LUT
Topic revision: r6 - 09 May 2017, LorenzoBusoni
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding Foswiki? Send feedback