NAOMI
WFS Acceptance Tests at the University of Durham wht-naomi-45
DRAFT (Version date: 2nd June 2000)
The ID numbers are
those used in Dr. Andy Longmore’s Microsoft Access database (see AJL file:
integration_tests.mdb) which summarises the WPD requirements.
Most of the acceptance
tests listed in the database have been included in this document; some
selection of tests has been performed. The pressures of the schedule may lead
to significant reductions. In later versions of this document the author plans
to attach priorities to the tests and indicate test sequences for more
efficient operation, i.e. tests with similar configurations and requirements
should be grouped together. Notes in this draft have partially addressed the
need for grouping but a scheme that readily identifies similar tests is needed.
|
ID |
Objective |
Requirements |
Description of Test |
Date &Examiner |
Pass/ Fail |
Comments |
|
4 |
Verify that the WFS
will operate with atmospheric coherence lengths > 8 cm at 0.55 mm. |
·
WFS ·
OMC ·
Engineering
level GUI ·
Liquid crystal
turbulence simulator |
1.
Set up WFS to
view point source through turbulence simulator with DM flattened and FSM at
midrange. 2.
Demonstrate
that satisfactory Hartmann spot data can be obtained over required range of
turbulence conditions, changing between lenslets 1 and 2 in accordance with
turbulence strength. |
|
|
|
|
7 |
Verify that the DM
segments map onto the WFS subapertures. |
·
WFS ·
OMC ·
NCU ·
Engineering
level GUI |
1.
Flatten DM and
set the FSM to midrange. Align WFS to on-axis NCU DL point source. 2.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 3.
Adjust x-y position of the DM as required
for the best overall registration of the DM image with the lenslet array. 4.
Verify that in
near-pupil viewing mode that light does not spill over into other
subapertures except as allowed by test ID number 120. Note: Tests ID 7 and 20 should be combined. |
|
|
|
|
10 |
Verify that CCDs
operate with 8 x8 (6 x 6) and 4 x 4 pixels (unbinned) |
·
WFS ·
OMC ·
NCU ·
Engineering
level GUI |
1.
Flatten DM or
install dummy DM. Set FSM to midrange. Align WFS to on-axis NCU DL point
source. 2.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 3.
Adjust WFS
pickoff to centre Hartmann spots in array. 3.
Adjust NCU
brightness and WFS integration time to give high photon rate without
saturation. 4.
Operate in
required readout modes and show that the data streams can be reconstructed
into the appropriate images. |
|
|
|
|
11 |
Verify that the CCDs
operate in a quad cell mode (2 x 2 binned pixels). |
·
WFS ·
OMC ·
NCU ·
Engineering
level GUI |
1.
Flatten DM or
install dummy DM. Set FSM to midrange. Align WFS to on-axis NCU DL point
source. 2.
Set up WFS in
quad cell mode with lenslet array 1 and ADC set to zero dispersion. 3.
Adjust WFS
pickoff to centre Hartmann spots in array. 4.
Adjust NCU
brightness and WFS integration time to give high photon rate without
saturation. 5.
Verify that the
data stream can be reconstructed into the appropriate image. |
|
|
|
|
12 |
Verify that the CCD
configuration is changeable without loosing lock. |
·
WFS ·
OMC ·
Engineering
level GUI ·
Liquid crystal
turbulence simulator |
1.
This test
should be performed on completion of test ID 4. 2.
With lenslet 1
and 4 x 4 pixels close the DM and FSM loops for simulated ro TBD
(>15 cm suggested). 3.
Demonstrate
that one can change to quad cell mode and 6 x 6 pixels without loosing lock. |
|
|
|
|
20 |
Pickoff must allow
acquisition of WFS source |
·
WFS ·
Engineering
level GUI |
1.
Acquire WFS
calibration source by moving pickoff. 2.
Verify that
images of source can be centred in CCDs field of view. |
|
|
|
|
22 |
Verify that the
acquisition accuracy is < 3.4 mm. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
1.
Flatten DM or
install dummy DM. Set FSM to midrange. Install NCU FP mask. 2.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 3.
Acquire and
centre in CCD FOV a selection of pinholes from over the field presented by
the FP mask. 4.
Verfify that
acquisition accuracy meets requirements from WFS pickoff readouts and
calibration data for FP mask. |
|
|
|
|
23 |
Dithering range of
1.7 mm (5 arcsecond) with + 3.4 mm
repeatability is required. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
1.
Flatten DM or
install dummy DM. Set FSM to midrange. Install NCU FP mask. 2.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 3.
Select pair of
pinholes in FP mask with separation closest to 1.7 mm. 4.
Establish
pickoff positions that centre each pinhole in CCDs’ FOV. 5.
Dither between
these pinholes and determine repeatability from Hartmann spot positions at
ends of each dither cycle. |
|
|
|
|
24 |
Dithering range of 6
mm (18 arcsecond) with + 8.5 mm
repeatability is required. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
This test is similar
to the previous test (ID 23) except that the dither range is increased
accordingly. |
|
|
|
|
25 |
Dithering amplitude
accuracy shall be + 17 mm (+
0.05 arcsecond) or better. |
·
|
This test should be
combined with tests ID 23 and 24. These tests establish repeatability. To
establish accuracy one compares the commanded pickoff positions with the
actual as determined by the spot positions as seen by the CCDs. |
|
|
|
|
29 |
Pickoff z-axis shall
provide field curvature compensation. |
·
WFS ·
Engineering
level GUI |
Verified as part of
any test involving z-axis motion, e.g. ID 159. |
|
|
|
|
30 |
Maximum z-axis speed
shall be > 1.9 mm/sec. |
·
WFS ·
Engineering
level GUI |
Measure time for
z-axis motion of 19 mm. |
|
|
|
|
39 |
WFS must register
with OMC with a 3-axis repeatability < 50 mm. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
1.
Install dummy
DM with fiducial. Set FSM to midrange. Align WFS to on-axis NCU DL point
source. Set NCU to high brightness. 2.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 3.
Adjust WFS
pickoff to centre Hartmann spots in array. Adjust integration time to give go
best signal to noise ratio without saturation. 4.
Measure spot
positions, mean separation, pupil image of fiducial in front of dummy DM. 5.
After taking
all precautions, lift the WFS using the handling gear provided and carefully
replace. 6.
Repeat step 4
and calculate replacement accuracy from spot position and pupil changes. |
|
|
|
|
40 |
WFS must pivot about
f/16.8 focus in both axes. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
This capability is
verified as part of the OMC/WFS initial installation and alignment. |
|
|
|
|
41 |
Phase-gradient
measurement accuracy of 0.018 wave (l=2.2 mm) rms required with 1500 photons/subaperture
. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
1.
Flatten DM or
install dummy DM. Set FSM to midrange. Align WFS to on-axis NCU DL point
source. 2.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 3.
Adjust WFS
pickoff to centre Hartmann spots in array. 4.
Adjust NCU
brightness and WFS integration time to give photon rate. Record spot centroid
positions. 5.
Tilt FSM angle*
20.8 mrad (4.3 arcsec) and measure spot centroid
positions. Repeat several times and determine the dispersion. (* Mirror
surface tilt corresponding to required phase gradient accuracy.) |
|
|
|
|
42 |
Phase-gradient
measurement accuracy of 0.14 wave (l=2.2 mm) rms required with 40 photons/subaperture. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
1.
Flatten DM or
use dummy DM. Set FSM to midrange. Align WFS to on-axis NCU DL point source. 1.
Set up WFS in quad cell mode with lenslet
array 1 and ADC set to zero dispersion. 2.
Adjust WFS
pickoff to centre Hartmann spots in array. 3.
Adjust NCU
brightness and WFS integration time to give photon rate. Record spot centroid
positions. 4.
Tilt FSM angle
TBD and measure spot centroid positions. Repeat several times and determine
the dispersion. |
|
|
|
|
43 |
Verify phase
gradient range is at least + 1.5 waves/subaperture (l=2.2 mm)
with 4 x 4 pixels for ro=8 cm and 8 x 8 pixels for ro
>13 cm. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
1.
Flatten DM or
use dummy DM. Set FSM to midrange. Align WFS to large NCU source which
simulates time-averaged source degraded by strong turbulence. 2.
Set up WFS in 4
x 4 pixel mode with lenslet array _ and ADC set to zero dispersion. 3.
Move WFS
pickoff along x-axis until edge of pixel array is reached in each direction.
Note that + 1.5 waves/subaperture corresponds to a pickoff motion of + 0.41 mm. Record pickoff positions
at array edges. 4.
Repeat for
y-axis. 5.
Align WFS
pickoff to NCU DL point source and select lenslet 1 and 8 x 8 pixel mode. 6.
Repeat steps 3
and 4 for this configuration. |
|
|
|
|
51 |
Spot displacements
due to aberrations on-axis must be < 20% of pixel size. |
·
WFS ·
Engineering
level GUI |
1.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 2.
Move pickoff to
acquire WFS calibration source. 3.
Adjust WFS
pickoff to obtain best centration of Hartmann spots in array. 4.
Adjust WFS integration time to give high photon rate without saturation. 5.
Record spot
centroid positions and determine displacement from centre of each pixel
array. |
|
|
|
|
54 |
Transmission shall
be >90% over 0.5 to 1.0 mm spectral range. |
·
WFS ·
OMC ·
NCU or suitable
bright source at Nasmyth focus ·
ATC photometer |
1.
A “point”
source of sufficient brightness is required at the input to the OMC, i.e. the
Nasmyth focus. “Sufficient brightness” is defined as a good signal to noise
level with the ATC photometer when its head is placed at the f/16.8 focus,
i.e. the WFS input. 2.
Measure the
signal at the f/16.8 focus with the photometer head. 3.
Move the CCD
carriage to the rear limit of its travel. 4.
Select the WFS
doublet in the lenslet wheel. 5.
Mount the
photometer head to collect all light from the doublet. 6.
The ratio of
the second reading to the first is a measure of the transmission (excluding
relay optics). 7.
Perform this
operation with different filters (subject to availability) to assess
transmission variation with 0.5 to 1.0 mm
spectral region. |
|
|
Measurement excludes
relay optics. |
|
67 |
Lenslets shall not
scatter >2% into adjacent subapertures. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
1.
Flatten DM and
set FSM to midrange. 2.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 3.
Align WFS to
on-axis NCU point source. 4.
In
pupil-viewing mode verify correct registration of DM segments to lenslets. 5.
Select a
subaperture and tilt segments around this subaperture to limit away from
subaperture. 6.
Measure flux in
adjacent subapertures and compare with flux in selected subaperture. |
|
|
Difficult to
distinguish between lenslet scattering and DM mis-registration. |
|
80 |
Pupil shift and
residual dispersion shall be <5% subap. and <0.04 arcsec at 45deg
zenith: <8% subap, 0.06 arcsec at 60 deg zenith. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
Satisfactory
procedure not yet defined. |
|
|
Difficult to perform
a credible test. |
|
85 |
Remotely-controlled
shutter with EPICS interface is required. |
·
WFS ·
Engineering
level GUI |
Verify remote
operation of shutter. |
|
|
|
|
88 |
Verify that two
electronically switchable readout modes have been provided. |
·
WFS ·
Engineering
level GUI |
Demonstrate
synchronized mode switch (by inspection of output data stream?) while
observing WFS calibration source. |
|
|
|
|
90 |
At 100 kilopixel/sec
the readout noise shall be 3 e-/pixel or less. |
·
WFS ·
Engineering
level GUI |
With the WFS shutter
closed, set the readout rate, determine the dark field and readout noise
level. |
|
|
|
|
91 |
At maximum rate, the
readout noise shall be 7 e-/pixel or less. |
·
WFS ·
Engineering
level GUI |
Similar to previous
test (ID90) but at maximum readout rate. |
|
|
|
|
103 |
Reference wavefront
tilt accuracy must be a factor of two better than WFS can detect. |
·
WFS ·
Engineering level
GUI |
Confirm by
calculation. Compare pickoff resolution to Hartmann spot centroid accuracy as
determined in ID 41. |
|
|
|
|
105 |
WFS calibration
source intensity must be > 3 x 10^-8 W/steradian. |
·
WFS ·
Engineering
level GUI |
1.
With lenslet 1
and 4 x 4 pixel mode, acquire the calibration source and centre Hartmann
spots in CCD FOV. 2.
Measure number
of photons /subaperture in 5 msec through broadest spectral filter with no
ND. Number of photons should exceed 2500. |
|
|
|
|
107 |
WFS calibration
source intensity must be uniform. |
·
WFS ·
Engineering
level GUI |
1.
With lenslet 1
and 4 x 4 pixel mode, acquire the calibration source and centre Hartmann
spots in CCD FOV. 2.
Switch to the
pupil-viewing mode, increasing the integration time if required to obtain
sufficient signal. 3.
Record the
pupil image and assess the uniformity. |
|
|
|
|
108 |
WFS calibration
source must simulate G0-K0 star. |
·
WFS ·
Engineering
level GUI |
Test required to
analyse spectral characteristics. |
|
|
Difficult to devise
and perform suitable test. |
|
111 |
Verify that WFS
transfer curve linearity is <15% (except in quad cell mode). |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
1.
Flatten DM or
use dummy DM. Align WFS to on-axis NCU DL point source. 2.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 3.
Move WFS
pickoff along x-axis in 5 mm increments until edge
of pixel array is reached in each direction. 4.
Record WFS mean
centroid position for each increment. 5.
Plot mean
centroid position against pickoff position. 6.
Repeat steps
3-5 for y-axis. 7.
Determine
linearity of transfer curves. |
|
|
|
|
115 |
CCD pixel gain
calibration shall be accurate to1% rms or better. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
1.
Set up NCU to
provide uniform extended source. 2.
Flatten DM or
use dummy DM. Set FSM to midrange. Align WFS to source. 3.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 4.
Perform pixel
gain calibration. 5.
Tilt FSM by
random amounts to shift position of extended source and repeat pixel gain
calibration at each position. (Intent is to smooth out variations in extended
source brightness.) 6.
Repeat for
various integration times, if possible. |
|
|
Feasibilty depends
on sufficient NCU brightness. Difficult to establish 15% accuracy. |
|
116 |
CCD pixel background
offsets shall be determined to within 1 e- per sensor integration
period. |
·
WFS ·
Engineering
level GUI |
1.
Close WFS
shutter. 2.
Measure
stability of dark frame counts for various integration times, e.g. 3 – 30 ms,
and confirm that the objective is satisfied. |
|
|
|
|
120 |
Lenslets shall be
aligned in angle to better than 10 arcminutes relative to mapping of the DM
segments. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
1.
Flatten DM.
Align WFS to on-axis NCU DL point source. 2.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 3.
Adjust x-y
position of the DM as required for the best overall registration of the DM
image with the lenslet array. 4.
Select DM
segment at edge of WFS subapertures and offset all adjacent segments so that
their respective Hartmann spots move out of the WFS field. 5.
Determine the
light spillover into adjacent subapertures as a result of misregistration
(angular or otherwise). 6.
Repeat the
measurement for three other subapertures so that all four lie at the extremes
of a cross. Light spillover into an adjacent subaperture should not exceed
0.7 % due to rotation alone. |
|
|
Requirement is
achieved by shimming DM as required. |
|
121 |
Lenslet accuracy
shall be maintained when lenslets are changed. |
·
WFS ·
Engineering
level GUI |
1.
With lenslet 1
and 4 x 4 pixel mode acquire the WFS calibration source. Centre the source
image by adjusting the pickoff position as required. 2.
Record spot
positions. 3.
Rotate lenslet
wheel and reselect lenslet 1. 4.
Re-measure spot
positions. 5.
Repeat for
other lenslets. |
|
|
|
|
132 |
WFS shall perform to
specification with a temperature change of 1 deg C/hour. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
This test could be a
continuation of ID 121 by monitoring the spot position, deviation and size
with temperature. |
|
|
|
|
146 |
WFS vibration
sources must contribute < 0.0035 arcsec rms uncorrectable tip/tilt jitter |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI ·
SBIG camera |
1.
Flatten DM and
set FSM to midrange. 2.
Install SBIG
camera at the optical science port to view DL pinhole in FP mask. 3.
Align WFS to
suitable pinhole in FP mask without obscuring image of the SBIG camera. 4.
Measure PSF
width at science port with WFS power sources off. 5.
Turn on WFS
power sources. Measure PSF width again. Determine change in width. |
|
|
Extremely difficult
to detect. |
|
147 |
Cleaning procedures
for all optical components must be developed and demonstrated. |
·
WFS |
Cleaning procedures
should first be demonstrated on witness samples wherever possible to reduce
the risk of damage. An area of particular concern is the WFS pickoff mirror
as no spare is available. Advise waiting until cleaning is required. |
|
|
|
|
159 |
Combined motion of
all carriages in response to pickoff motion shall produce no detectable focus
error at WFS. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
This test could be
performed in conjunction with ID 22 by using the reconstructor to determine
the focus change at each pinhole position. |
|
|
|
|
162 |
Verify proper
function of encoder readout and use in any feedback. |
·
WFS ·
Engineering
level GUI |
A separate test is
not essential in that other tests should adequately demonstrate the encoder
functions. Tests already performed at the ATC indicate satisfactory operation. |
|
|
|
|
163 |
Lifting frame and
attachments must be provided for the WFS. |
·
WFS ·
Lifting
equipment |
Demonstrated as part
of ID 39. |
|
|
|
|
164 |
Verify fit of
components in shipping containers and adequacy of protection. |
·
WFS ·
Shipping
containers |
Pack and inspect. |
|
|
|
|
165 |
Verify fit and
functionality of any spares. |
·
WFS ·
Engineering
level GUI ·
WFS spares |
Using full check
list of spares, install each and show normal operation of WFS, e.g. using WFs
calibration source. |
|
|
|
|
168 |
Temperature sensors
will be provided to allow correction to unavoidable alignment changes caused
by contraction or expansion. |
·
WFS ·
Engineering
level GUI |
Test and monitor
temperature sensors over a couple of 24 –hour periods. Confirm that readings
are consistent with those from an independent thermometer. |
|
|
|