NAOMI
WFS and OMC/NCU Acceptance Tests at the University of Durham wht-naomi-34
DRAFT (Version date: 4th July 2000)
This document combines
two earlier draft documents that addressed the WFS and OMC/NCU separately. It
also covers the system level acceptance tests that will be repeated at GHRIL to
verify performance.
The ID numbers in the
first column are those used in Dr. Andy Longmore’s Microsoft Access database
(see AJL file: integration_tests.mdb) which summarises the WPD requirements.
The prefixes “WFS” and “OMC” before the ID number refer to the wavefront sensor
and opto-mechanical chassis/Nasmyth calibration unit respectively.
Most of the acceptance tests listed in the database have been included in this document; some selection of tests has been performed. Section 1 contains a grouping of tests with similar procedures. Elsewhere numbers in parentheses in the ID column identify tests that may be grouped together for efficient operation: note that there is no back referencing in the ID column. There is no requirement to perform the tests in the order given in this document.
Three levels of priority are shown, namely high, medium and low. These levels are indicated by the letters H , M and L in the ID column. In some instances a lower priority has been assigned where sufficient testing has been performed at the ATC or there is high confidence in the design.
A pre-requisite for the tests is the
ability to observe a near diffraction-limited visible image with the SBIG
camera at the IR science port. At least the first Airy ring should be
observable in the image and the FWHM of the central peak should be consistent
with diffraction theory after allowing for camera pixellation effects.
1.
Grouped Tests
|
ID |
Objective |
Requirements |
Description of Test |
Date &Examiner |
Pass/ Fail |
Comments |
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|
OMC 15 M |
Verify that the
optics maintain the registration of the DM with the WFS lenslets independent
of the guide star position. |
·
OMC ·
WFS ·
NCU ·
Engineering
level GUI |
1.
The integrated
system is required for this test with the
Nasmyth focal plane mask installed. 2.
Flatten the DM
and set the FSM to mid range. 3.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 4.
Move the WFS pickoff
to acquire the on-axis DL pinhole and
centre the Hartmann spots. 5.
Select the WFS
fiducial mask and position the relay-lens/CCD carriage for the pupil-viewing
mode. 6.
Verify the DM
registration with the fiducial mask. If not aligned adjust the DM x-y stage
accordingly. (Note that the offset segment approach described in the next
procedure may be used to obtain optimum alignment.) 7.
Move the WFS
pickoff to at least 4 other field points and measure the DM/fiducial-mask
registration. 8.
0.115
subaperture misregistration is predicted due to non telecentricity. |
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WFS 7 H |
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 in the pupil viewing mode. Return to Hartmann
spot viewing. 4.
Select a DM
segment close to the DM centre and offset all adjacent segments so that their
respective Hartmann spots move out of each subaperture’s field of view. 5.
Determine the
light spillover into adjacent subapertures. Readjust DM in x and y if
required to balance spillover. Spillover should not exceed 3.3% (2% is
allowed for lenslet scattering and 1.3 % for misregistration. Note that in
the next test 0.7% is allowed for angular misregistration.) 6.
Repeat steps 4
and 5 for another segment close to the DM centre. |
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WFS120 H |
Lenslets shall be
aligned in angle to better than 10 arcminutes relative to mapping of the DM
segments. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
This test is a
continuation of the preceding procedure. 1.
Select a DM
segment at edge of WFS subapertures and offset all adjacent segments so that
their respective Hartmann spots move out of each subaperture’s field of view. 2.
Determine the
light spillover into adjacent subapertures as a result of misregistration
(angular or otherwise). 3.
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. Note allowance of 3.3% for other sources of
error. |
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Requirement is
achieved by shimming DM as required. |
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|
WFS 51 H |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
Note: Although there is no off-axis
specification the Hartmann spot offsets should be determined for other field
positions as part of the system characterisation. 1.
The integrated
system is required for this test with the
Nasmyth focal plane mask installed. 2.
Flatten the DM
and set the FSM to mid range. 3.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 4.
Move pickoff to
acquire on-axis source. 5.
Adjust WFS
pickoff to obtain best centration of Hartmann spots in array and record
pick-off x-y position. 6.
Adjust WFS integration time to give high photon rate without saturation. 7.
Record spot
centroid positions and determine displacement from centre of each pixel
array. 8.
Repeat steps
5-7 for lenslets 2 and 3. 9.
Repeat steps
4-7 for other pinholes in grid of NFP mask (subject to time constraints). |
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OMC 20 H |
NCU provide
capability to distortion map of AO optical train. |
·
NCU ·
OMC ·
WFS ·
Engineering
level GUI |
Capability was
demonstrated in preceding test. |
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WFS 22 M |
Verify that the
acquisition accuracy is < 3.4 mm. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
Acquisition accuracy
will be ascertained as part of the astrometric mapping process in test WFS
51. |
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WFS159 H |
Combined motion of
all carriages in response to pickoff motion shall produce no detectable focus
error at WFS. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
Verified by observing WFS focus residuals
during astrometric mapping in test WFS 22. Note that the WFS carriage drives
are programmed to compensate for the OMC field curvature. |
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WFS 29 L |
Pickoff z-axis shall
provide field curvature compensation. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI |
Verified by
observing WFS focus residuals during astrometric mapping in test WFS 22. Note
that the WFS carriage drives are programmed to compensate for the OMC field
curvature. |
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OMC186 H |
Provision must be
made to calibrate non-common path errors between science path and the WFS. |
·
NCU ·
OMC ·
WFS ·
Engineering
level GUI ·
SBIG camera |
Procedure to be
added later to cover methods developed by Durham. |
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2. OMC Tests (not addressed
above)
|
ID |
Objective |
Requirements |
Description of Test |
Date &Examiner |
Pass/ Fail |
Comments |
||
|
OMC 19 M |
The NCU should
provide a WHT pupil simulator (for on-axis use only) |
·
NCU ·
OMC ·
WFS ·
Engineering
level GUI. |
1.
Measure the
f/ratio of the NCU output beam with the pupil mask in place. 2.
If brightness
is sufficient, verify that the pupil mask is imaged at the DM and its size is
correct (56 mm). 3.
If brightness
inadequate for visual observation at DM the pupil viewing mode of the WFS may
be used as follows. 4.
Flatten DM and
set FSM to midrange. 5.
Set WFS ADC to
zero dispersion and select doublet. 6.
Acquire on-axis
point source by moving WFS pickoff and centre in WFS FOV. 7.
Switch to WFS
pupil viewing mode. Verify pupil is in focus and record image for analysis.
Confirm that pupil size is acceptable. |
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Test may be limited
by source brightness. |
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OMC 21 (OMC 41) H |
Average transmission
from Nasmyth focus to WFS input must be >0.58 over 0.5 to 0.8 mm (Mode 1). |
·
NCU ·
OMC ·
Engineering
level GUI. ·
ATC photometer
(or equivalent, e.g. SBIG camera) ·
0.5 -0.8mm filter |
1.
Flatten DM and
set FSM to midrange. 2.
With on-axis
point source, pupil mask and spectral filter measure NCU output flux with
photometer or SBIG camera. (Note that the latter can measure total flux). 3.
Measure flux
passing through centre of dichroic at WFS input and calculate transmission. |
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OMC 51 (WFS 23, 24, 25) H |
Show that loop
closure can be maintained while dithering. |
·
NCU ·
OMC ·
WFS ·
Engineering level
GUI |
1.
Select NCU
on-axis point source, i.e. no FP mask. 2.
Flatten DM and
set FSM to midrange. 3.
Move WFS
pickoff to acquire point source and centre in WFS FOV. 4.
Close DM and
FSM loops. 5.
Setting the
configuration to the dither mode, inject an increasing amplitude, low
frequency tilt signal to the NCU tip/tilt mirror (maximum amplitude and
frequency TBD). 6.
Demonstrate
that the system can maintain loop closure while dithering. |
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OMC 55 (OMC 56, 57, 58, 60) M |
On-axis
common/science path wavefront error shall be <30 nm rms within a
subaperture (note exceptions in WPD). |
·
OMC ·
FISBA
interferometer ·
Concave
spherical mirror and x, y & z mount (for use as retroreflector) |
1.
Install dummy
DM with pupil stop. 2.
Mount FISBA on
axis at the OMC input (Nasmyth focus). 3.
Install and align
concave sphere so that its centre of curvature is coincident with the focused
FISBA light at the WFS focus. 4.
Measure and
record the wavefront. Analyse for compliance. 5.
Move the
concave sphere to the science path and repeat the wavefront measurement. Analyse
for compliance. |
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OMC 56 M |
Off-axis
uncorrectable wavefront error over 1 arcmin field shall be <50 nm rms
(note exceptions in WPD) |
·
OMC ·
FISBA
interferometer ·
Concave
spherical mirror and x, y & z mount (for use as retroreflector) |
1.
Install dummy
DM with pupil stop. 2.
Mount FISBA at
+0.5 arcmin off axis in x at OMC input (Nasmyth focus). 3.
Install and
align concave sphere so that its centre of curvature is coincident with the
focused FISBA light at the WFS focus. 4.
Measure and
record the wavefront. Analyse for compliance. 5.
Repeat steps
2-5 for –0.5 arcmin in x and + 0.5 arcmin in y. |
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-0.5 arcmin in y may
be omitted due to symmetry of the design. |
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OMC 57 M |
The pupil wavefront
error shall be <200 nm rms (goal < 170 nm) within 2 arcmin field. (Note
exceptions in WPD). |
·
OMC ·
FISBA
interferometer ·
Concave
spherical mirror and x, y & z mount (for use as retroreflector) |
1.
Follow same
procedure as for ID 56 except that FISBA and sphere are located at + 1
arcmin in x and y respectively. 2.
Determine rms
wavefront error over the pupil for each field position. |
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OMC 58 M |
The pupil wavefront
error shall be <300 nm rms (goal < 265 nm) within 2.9 arcmin field.
(Note exceptions in WPD). |
·
OMC ·
FISBA
interferometer ·
Concave
spherical mirror and x, y & z mount (for use as retroreflector) |
1.
Follow same
procedure as for ID 56 except that FISBA and sphere are located at +
1.45 arcmin in x and y respectively. 2.
Determine rms
wavefront error over the pupil for each field position. |
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OMC 60 M |
Non-common path
errors between science path and WFS shall be < 100 nm rms |
·
OMC ·
WFS ·
FISBA
interferometer ·
Concave
spherical mirror and x, y & z mount (for use as retroreflector) |
1.
Calibrate
wavefront quality of concave spherical mirror using the FISBA. Retain
wavefront data for use in other tests that follow. 2.
Set up the
FISBA on axis at the input (Nasmyth focus) to the OMC. WFS should not be in
position. 3.
Flatten the DM
or install the dummy DM. 4.
Install and
align the concave spherical mirror at the IR science port so that the IR
science path can be measured in double pass with the FISBA. Measure and
record the wavefront. 5.
Move the
concave sphere so that its centre of curvature lies at the WFS input focus.
Measure and record the input wavefront to the WFS. Remove sphere. 6.
Install the WFS
and move its pickoff so that the FISBA light passes through to the optical
science port (OSP). Reposition the sphere to allow a double-pass wavefront
measurement to the OSP. Measure and record the wavefront. 7.
Determine the
non-common path errors from the measured wavefronts. |
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OMC 67 M |
General optical
practice to avoid ghosting shall be followed. |
·
OMC ·
NCU ·
Engineering
level GUI ·
WFS ·
SBIG camera |
The objective is to
identify all ghost images within the optical train and quantify them in terms
of relative intensity and location. 1.
Set the NCU to
maximum brightness, select the on-axis point source, flatten the DM and set
the FSM to mid range. 2.
Set up the SBIG
camera at the IR science port to view the point source image. Demagnification
to provide at least a 50 arcsecond field of view is suggested. Identify and
quantify any ghost images. Note that an extended integration time may be
needed to locate any ghosts. 3.
Move the camera
to the optical science port and repeat. Move the WFS pickoff to avoid
obscuration of the SBIG camera. 4.
Select the WFS
doublet in the lenslet wheel and move the pickoff to acquire and centre the
point source image. Set the ADC to zero dispersion. Identify and quantify any
ghost images. Insert the lenslet arrays in turn and repeat the operation.
Also insert the WFS filters in turn and rotate the ADC elements. 5.
Similarly check
for ghost images in the acquisition camera’s field. 6.
Install the NFP
mask and search for ghosts at all ports for at least three field postions
(TBD). |
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OMC 77 H |
Measures shall be
taken to protect personnel from hazards. |
·
OMC ·
NCU ·
Engineering
level GUI |
Verify compliance
with documented safety audit. Procedure to be established when document is
made available to Durham. |
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OMC 78 M |
Handling procedures
and lifting aids should be provided for heavy items. |
·
NCU ·
OMC ·
Lifting aids
(e.g. handles) |
Verify availability
and function of lifting aids when demonstrating installation and alignment
(or disassembly on completion of tests). |
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OMC 94 (WFS 4) H |
SciOpReq Clauses 1 –
3 performance achievable for 1 hour integrations without recalibration |
·
Turbulence
simulator ·
OMC ·
WFS ·
Engineering
level GUI ·
SBIG camera |
This test should be
performed as part of test ID WFS 4 which uses the turbulence simulator. The
SBIG camera should be set up at the IR science port to view the compensated
point source image. Observations of the image quality should be made for
fixed test conditions over a 1 hour period. |
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OMC 95 Priority TBD |
The uncorrectable
tip/tilt induced jitter shall be < 30 nrad (0.006 arcsec) in WHT object
space. Note the inclusion of the WFS in the specification. |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI ·
SBIG camera |
Test is subject to
review. 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. Close FSM loop. Measure PSF width again. Determine change in
width. Note: This test is
similar to the WFS test ID 146 which also lacks a satisfactory procedure. |
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Test requires
further thought. Difficult to distinguish uncorrectabl-e tilt from other
sources of PSF degradation. |
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OMC 97 M |
Cleaning procedures
demonstrated on witness samples of all coatings. |
·
Witness samples ·
Cleaning
materials and procedures |
1.
If a suitable
spectrophotometer is available the transmittance or reflectance of all
witness samples should be measured before and after cleaning. 2.
Perform
cleaning in accordance with documentation. Verify that the cleaning does not
leave residue or cause damage. |
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OMC100 (OMC 101) M |
Verify that the DM
and its associated electronics on bench can be removed and re-installed
safely in 1 hour or less. |
·
OMC ·
NCU ·
WFS ·
Engineering
level GUI |
1.
Flatten DM and
set FSM to midrange. Select on-axis point source in NCU. 2.
Select lenslet
1 and 4 x 4 pixel mode. Set ADC dispersion to zero. 3.
Acquire and
centre point source image in WFS by moving its pickoff. 4.
In pupil
viewing mode verify that DM segments are aligned to lenslets. If not adjust
DM x-y position as required. 5.
Turn off all
power to system. 6.
Remove and
re-install DM and bench-mounted electronics, noting time required for
complete operation. |
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OMC101 L |
Verify that only
further minor alignment is needed on re-installation of DM. |
·
OMC ·
NCU ·
WFS ·
Engineering
level GUI |
This test is a
continuation of the procedure for test ID 100. 1.
Power up the
system and check for the image of the point source and pupil alignment in the
WFS. 2.
If re-alignment
is required, verify that it is minor, i.e. within limits of adjustments
provided. |
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OMC103 (OMC 104) L |
Verify that there is
at least + 4mm of travel on the DM motorized stages. |
·
OMC ·
Engineering
level GUI. ·
Travelling
microscope or equivalent |
1.
Set up
travelling microscope to view a reference point on the DM, e.g. segment
boundary. Take care not to touch the DM surface. 2.
Command the DM
x-y stage drive to each limit of travel and measure distance moved with the
travelling microscope. Verify travel is acceptable. |
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OMC104 L |
Verify that DM motorized
stage motions are repeatable to < 0.2 mm. |
·
OMC ·
Engineering
level GUI. ·
Travelling
microscope or equivalent |
This test should be
combined with test ID 103. 1.
Set up
travelling microscope to view a reference point on the DM, e.g. segment
boundary. Take care not to touch the DM surface. 2.
Command the x-y
stage to drive set distances (TBD) repeatedly and measure position after each
command with the travelling microscope. Verify that the repeatability is
acceptable. |
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OMC110 H |
Verify that the FSM
is protected against being driven to limits of its safe operational range. |
·
OMC ·
Engineering
level GUI |
Drive the FSM in incremental steps (TBD)
towards its limits noting the point at which the offload to the TCS occurs.
Verify that FSM does not exceed safe operating limits. Note: A means of
independently monitoring the FSM surface tip/tilt is desirable for this test. |
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OMC111 H |
Verify that FSM
offsets are off-loadable to the TCS. |
·
OMC ·
Engineering
level GUI |
This test should be
combined with test ID 110. |
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OMC112 M |
Characterise the FSM
frequency response to 200 Hz. |
·
OMC ·
Engineering
level GUI ·
Collimator and
position-sensing detector to measure FSM surface tilt. |
1.
Set up
collimator and position-sensing detector (PSD) to measure FSM surface tilt. 2.
Apply small
amplitude (< 50mrad surface tilt)
sinusoidal oscillation to FSM progressing from low to higher frequencies.
Record FSM tip/tilt amplitude as measured with PSD. Exercise caution if
resonance starts to occur. 3.
Determine –3 dB
frequency. |
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Repeat of tests
performed at the ATC. Test subject to equipment availability. |
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OMC113 Priority TBD |
Verify that the FSM
open-loop jitter is < 48 nrad (0.01 arcsec) rms in WHT object space for
either axis. |
·
OMC ·
SBIG camera ·
NCU ·
Engineering
level GUI |
Test is subject to
review. 1.
Install and
align the NCU and OMC. 2.
Flatten the DM
or install the dummy DM. 3.
Install the
SBIG camera at the IR science port to view the NCU on-axis DL point source. 4.
With the FSM
power off, measure the point spread function (PSF) using the SBIG. 5.
Measure the PSF
again with the FSM power on in open loop. 6.
Determine the
increase (if any) in the PSF width in both axes with the power on and convert to angle in WHT object space
using the plate scale. |
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OMC131 (WFS 39) M |
OMC and WFS must
register repeatably to each other with < 50 mm
accuracy in all 3 axes. |
·
OMC ·
NCU ·
WFS ·
Engineering
level GUI. |
This test is
identical to WFS test ID 39 and it should not be repeated. |
|
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OMC147 M |
NCU provides on-axis
point source which is full-aperture diffraction limited (DL) at visible
wavelengths. |
·
NCU ·
SBIG camera |
1.
Set up the SBIG
camera to view the NCU on-axis point source. 2.
Record and
analyse the PSF. |
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OMC150 H |
Verify that the NCU
point source radiant intensity conforms to OMC WPD Table 2. |
·
OMC ·
NCU ·
WFS ·
Engineering
level GUI. |
1.
Flatten DM and
set FSM to midrange. 2.
Select WFS
lenslet 1, 4 x 4 pixel mode and ADC to zero dispersion. 3.
Move WFS
pickoff to acquire and centre NCU on-axis point source image in WFS field of
view. 4.
Determine
photons received per subaparture in 5 msec integration time and convert to
radiant intensity from source. 5.
Extrapolate to
infrared from these test results. |
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More detailed
information to be provided. |
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OMC202 L |
Measure the
open-loop transfer function of the NCU tip/tilt mirror. |
·
OMC ·
NCU ·
SBIG camera ·
Engineering
level GUI. |
The approach assumes that a sufficiently
sensitive, high bandwidth position-sensing detector is not available. 1.
Flatten DM and
set the FSM to midrange. Set up the SBIG on axis at the science port. 2.
Turn on the
on-axis point source with the tip/tilt mirror stationary. Record the image
and determine the PSF width (baseline). 3.
Turn on the
tip/tilt mirror (amplitude TBD) at 1 Hz. 4.
Integrate with
SBIG for > 30 sec. Determine width of blurred PSF and subtract baseline
width to arrive at measured amplitude of oscillation. 5.
Repeat at 10 Hz
intervals to 150 Hz. Shorter integration times may be used at the higher
frequencies. 6.
Derive transfer
function from ratio of commanded motion to measured motion as a function of
mirror frequency. |
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|
Test approach is
subject to review. Phase information is not obtained. |
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OMC154 M |
Verify that the NCU
point source tip/tilt injection frequency is controllable from 0.1 to 150 Hz. |
·
OMC ·
NCU ·
WFS ·
Engineering
level GUI. |
This requirement should be verified as part
of the preceding test. |
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OMC153 (OMC 154) H |
Verify that the NCU
point source tip/tilt injection amplitude is variable up to 2.6 arcsec |
·
OMC ·
NCU ·
WFS ·
Engineering
level GUI. |
This procedure may
be performed as part of test OMC 202 provided the SBIG camera is set up with
sufficient FOV to accept the image motion with a 2.6 arcsecond amplitude. An
alternative procedure using the WFS is given below. 1.
Select NCU
on-axis point source, i.e. no FP mask. 2.
Flatten DM and
set FSM to midrange. 3.
Select WFS
doublet and set ADC dispersion to zero. Select lenslet array 2. 4.
Move WFS
pickoff to acquire point source and centre in WFS FOV. 5.
Set NCU tip/tilt mirror to 2.6 arcsec amplitude at
< 10Hz and determine amplitude seen by WFS. |
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OMC157 M |
NCU point source
spectral distribution shall correspond to G0 to K0 spectral type. |
·
NCU ·
ATC photometer
or equivalent calibrated detector. ·
Spectral
filters (ideally 0.1 mm bandwidth over 0.5 to
1.0 mm) |
Measure the spectrum
of the direct output of the NCU using the photometer and filters. If suitable
equipment is not available, calculate spectral type from lamp colour
temperature and data on any colour-balancing filter in the NCU. |
|
|
Test subject to
availability of suitable filters and detector. |
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|
OMC165 M |
Verify that the
extended source radiance conforms to Table 3 of OMC WPD. |
·
NCU ·
Engineering
level GUI ·
ATC photometer |
Note that the solid
angle of the extended source must be determined (or assumed from the optical
design). The photometer measures irradiance and the solid angle is needed to
determine radiance, i.e. W/cm2/ster. As the ATC photometer only
operates over 0.5 to 1.0 mm one may have to use an
IR camera to complete the measurement. |
|
|
Test subject to
equipment availability. |
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|
OMC167 M |
Verify that NCU
extended source uniformity is < 0.5 % over 10 mm diameter. |
·
NCU ·
Engineering level
GUI ·
ATC photometer
with 1mm dia mask or SBIG camera. ·
x-y stage with
>10 mm travel for photometer head |
1.
Install mask on
photometer head (or at SBIG focus) and mount assembly at NCU output. 2.
Set up NCU to
provide extended source. 3.
Measure
uniformity of illumination across at least two diameters moving in <
1 mm increments. Alternative
procedure with SBIG camera. 1.
Install lens on
camera to give 5:1 demagnification. 2.
Set up SBIG to
view extended source. 3.
Analyse
uniformity of image. 4.
Rotate camera
90 degrees about axis and repeat. Analyse data for camera rotational
variations in response. 5.
Displace camera
by +/- half the FOV. Analyse data for lateral variations in camera response.
Separate camera non-uniformities from source non-uniformity. |
|
|
Difficult to make reliable
measuremen-ts to 0.5 %. |
||
|
OMC168 L |
Verify that a NCU
He-Ne laser source is available for on-axis alignment. |
·
NCU ·
OMC ·
Engineering
level GUI |
1.
Install He-Ne
laser in NCU 2.
Turn on the
laser and verify that beam properly illuminates the DM. |
|
|
|
||
|
OMC199 M |
Verify fit and
function of spare components, if any. |
·
Spare
components |
Any components to be
identified by the ATC. |
|
|
|
||
|
200 H |
Verify the
mechanical fit of the OMC/NCU
components in their shipping containers. |
·
OMC ·
NCU ·
Shipping
containers |
Pack and inspect. |
|
|
|
||
3.
WFS
Tests (not addressed above)
|
ID |
Objective |
Requirements |
Description of Test |
Date &Examiner |
Pass/ Fail |
Comments |
|
WFS 4 H |
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. |
|
|
|
|
WFS 10 (WFS 11, 12) H |
Verify that CCDs
operate with 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. |
|
|
|
|
WFS 11 H |
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. |
|
|
|
|
WFS 12 H |
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. |
|
|
|
|
WFS 20 M |
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. |
|
|
|
|
WFS 23 (WFS 24, 25) H |
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 with
doublet 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. |
|
|
|
|
WFS 24 H |
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. |
|
|
|
|
WFS 25 H |
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. |
|
|
|
|
WFS 30 L |
Maximum z-axis speed
shall be > 1.9 mm/sec. |
·
WFS ·
Engineering
level GUI |
Measure time for
z-axis motion of 19 mm. |
|
|
|
|
WFS 39 (WFS 163) M |
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. |
|
|
|
|
WFS 40 M |
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. |
|
|
|
|
WFS 41 (WFS 42) H |
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.) |
|
|
|
|
WFS 42 H |
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. |
|
|
|
|
WFS 43 H |
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. |
|
|
|
|
WFS 54 H |
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. |
|
WFS 67 H |
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. |
|
WFS 80 M |
ADC 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. |
|
WFS 85 H |
Remotely-controlled
shutter with EPICS interface is required. |
·
WFS ·
Engineering
level GUI |
Verify remote
operation of shutter. |
|
|
|
|
WFS 88 H |
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. |
|
|
|
|
WFS 90 H |
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. |
|
|
|
|
WFS 91 H |
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. |
|
|
|
|
WFS103 M |
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. |
|
|
|
|
WFS105 H |
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. |
|
|
|
|
WFS107 M |
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. |
|
|
|
|
WFS108 M |
WFS calibration
source must simulate G0-K0 star. |
·
WFS |
Determine by
analysis from lamp colour temperature and the spectral characteristics of any
filters installed in the calibration source. |
|
|
Difficult to devise
and perform suitable test. |
|
WFS111 L |
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. |
|
|
|
|
WFS121 M |
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. |
|
|
|
|
WFS132 M |
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. |
|
|
|
|
WFS146 Priority TBD |
WFS vibration
sources must contribute < 0.0035 arcsec rms uncorrectable tip/tilt jitter |
·
WFS ·
NCU ·
OMC ·
Engineering
level GUI ·
SBIG camera |
This test is subject
to review. 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. Close FSM loop. Measure PSF width again. Determine change in
width. |
|
|
Extremely difficult
to detect. |
|
WFS147 H |
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. |
|
|
|
|
WFS162 M |
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. |
|
|
|
|
WFS163 M |
Lifting frame and
attachments must be provided for the WFS. |
·
WFS ·
Lifting
equipment |
Demonstrated as part
of ID 39. |
|
|
|
|
WFS164 H |
Verify fit of
components in shipping containers and adequacy of protection. |
·
WFS ·
Shipping
containers |
Pack and inspect. |
|
|
|
|
WFS165 H |
Verify fit and
functionality of any spares. |
·
WFS ·
Engineering
level GUI ·
WFS spares |
Verify fit and
functionality of any spares (to be provided by the ATC). |
|
|
|
|
WFS168 L |
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. |
|
|
|
4. System Level Acceptance Tests
|
ID |
Objective |
Requirements |
Description of Test |
Date &Examiner |
Pass/ Fail |
Comments |
|
N/A |
Verify that a Strehl of >0.48 is obtained using NCU tilt
injector with FSM-only correction.
·
Measured at IR
science port with SBIG ST-5 camera.
·
Wavelength: 850 nm
·
Inject frequency: 10
Hz; Amplitude: +/- 0.1 arcsec.
|
·
NCU
· WFS · OMC · Engineering level GUI |
1.
Flatten DM and
set the FSM to midrange. Align WFS pick-off to on-axis NCU DL point source. 2.
Install and align SBIG camera with
850 nm filter at IR science port. 3.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 4.
Adjust x-y position
of the DM as required for the best overall registration of the DM image with
the lenslet array.
5. Adjust NCU point source intensity to obtain maximum signal with saturation at maximum (TBD) WFS frame rate. 6. Optimise the SBIG camera image using the “Nathanising” procedure. Fix the DM. 7. Set the NCU tilt injector to 10Hz and an amplitude of +/- 0.1 arcsecond. 8. Close the tilt loop. 9. Record the PSF seen by the SBIG camera. 10. Set the NCU tilt injector to 20Hz and an amplitude of +/- 0.05 arcsecond. 11. Close the tilt loop. 12. Record the PSF seen by the SBIG camera. 13. Determine the Strehl ratio for the two measurement conditions. |
|
|
Test subject to availability of software
to allow closure of tilt loop only.
|
As above using reconstructed DM-only
correction.
|
·
NCU
· WFS · OMC · Engineering level GUI |
1.
Flatten DM and set
the FSM to midrange. Align WFS pick-off to on-axis NCU DL point source. 2.
Install and align SBIG camera with
850 nm filter at IR science port (if not already in place). 3.
Set up WFS in 4
x 4 pixel mode with lenslet array 1 and ADC set to zero dispersion. 4.
Adjust x-y position
of the DM as required for the best overall registration of the DM image with
the lenslet array.
5. Adjust NCU point source intensity to obtain maximum signal with saturation at maximum (TBD) WFS frame rate. 6. Set the NCU tilt injector to 10Hz and an amplitude of +/- 0.1 arcsecond. 7. Close the DM loop. 8. Record the PSF seen by the SBIG camera. 9. Set the NCU tilt injector to 20Hz and an amplitude of +/- 0.05 arcsecond. 10. Close the tilt loop. 11. Record the PSF seen by the SBIG camera. 12.
Determine the Strehl
ratio for the two measurement conditions.
|
|
|
|
|
|
N/A |
Verify maximum WFS offsets below with
hill-climbed on-axis DL spot at 850 nm on SBIG and DM fixed.
· <30” off axis: no spot >0.1” from box centre · <90” off axis: no spot >0.2” from box centre |
·
NCU
· WFS · OMC · Engineering level GUI |
1.
Install the NFP
mask. 2.
Flatten DM and
set the FSM to midrange. Align WFS pick-off to on-axis NCU DL point source. 3.
Install and align SBIG camera with
850 nm filter at IR science port (if not already in place). 4. Set up WFS in 4 x 4 pixel mode with lenslet array 1 and ADC set to
zero dispersion. 5. Adjust x-y position of the DM as required for the best overall
registration of the DM image with the lenslet array. 6.
Adjust NCU point
source intensity to obtain maximum signal with saturation at maximum (TBD)
WFS frame rate.
7. Close the DM loop and follow the “Nathanising” procedure to obtain the optimum image at the SBIG camera. Fix the DM. 8. Move the WFS pick-off to acquire and centre the closest (6.5 mm in NCU grid space) point source image in the +x direction. 9. Measure and record the Hartmann spot positions relative to each “box” centre. 10. Repeat steps 8 and 9 for the –x and +/- y positions. 11. Repeat steps 8 to 10 but for NFP point sources that are 19.5 mm (NCU grid space) off axis. 12. Verify that the test objectives have been satisfied. |
|
|
|
|
N/A |
Low light level specification:
With 100 detected photons/ms/subaperture and inject/measurement conditions as for first test, verify Strehl > 0.23. |
·
NCU
· WFS · OMC · Engineering level GUI |
Follow
the procedure for the first test but with the following exceptions:
Before setting the tilt injector (step 7) switch the WFS to quad cell operation and adjust the NCU source brightness to give the specified photon rate in the objectives column. Continue with step 7. |
|
|
|