Download TOU BreadBoard

General strategy for the AIV during Phase A
•
2 roadmaps have been identified to prove the AIV
feasibility of the 32 telescopes
1.
INDUSTRY
1.
Paper study concerning the aspherical lenses procurement
feasibility on a ~2 years time schedule
2. Paper study concerning the spherical lenses procurement
feasibility on a ~2 years time schedule
3. Paper study concerning the albemet structure procurement
feasibility on a ~2 years time schedule
2. RESEARCH INSTITUTES
1.
Identify an AIV concept and procedure, defined in agreement
with the industry
2. Test on a TOU BraedBoard of the AIV procedure
3. Test on the prototype of the warm/cold system performance,
defined and performed together with the industry
TOU Alignment Concept
Variable Iris
Beam Expander
B/S
Focussing
CCD
Laser
Back Reflected Light
Transmitted Light
Focussing
CCD
Telescope
By using Airy and Newton rings both of the back reflected and of the transmitted
light (introducing one lens at a time) the alignment will be performed; to
maximize fringe contrast and airy rings visibility:
1. the detectors are conveniently mounted on linear stages which can move along
the optical axis
2. light shields can be inserted between each lens, to isolate the back reflected
light, when needed, coming only from that lens
3. A variable diameter iris is inserted on the collimated beam, to maximize the
transmitted and back-reflected spot visibility
TOU Alignment Set-Up: Vertical
Focussing
CCD
Transmitted Light
To allow lenses insertion
from the top, the final
alignment set-up for the
BB will be vertical
TOU
Variable Iris
Beam Expander
B/S
Laser
Back Reflected Light
Focussing
CCD
Strategy for the prototype alignment
1.
2.
PRE-BreadBoard: Identification of commercial lenses with, as much as
possible, the same curvature of the final design lenses, with the aim
to build a pre-prototype (completely realized with commercial parts)
to: test the alignment procedure and learn from the test setup (Airy
and Newton rings visibility, decenter and tilt misalignment sensitivity,
tuning of the test setup components, like for example the movement
range of the detectors)
BreadBoard: Realization of an “equivalent mechanical structure” (in
term of thermal behaviour) to perform the real final alignment
procedure and eventually test also in cold conditions the optical
performance of the system. This phase will be performed with a set
of lenses as close as possible to the final design lenses, differing only
for the glasses and for the usage of a spherical lens instead of the
aspherical one
TOU Pre-BreadBoard
Variable Iris
Beam Expander
B/S
Focussing
CCD
Laser
Back Reflected Light
Transmitted Light
Focussing
CCD
Pre-BreadBoard, realyzed with
commercial lenses and commercial
XYZ and Tip-Tilt
adjustments for each lens
TOU BreadBoard
Focussing
CCD
Frame connected to the bench,
allowing the “TOU Dummy” rotation
for lenses insertion from the top
and their alignment similarly to what
would happen with the final structure
Transmitted Light
Fixing points
TOU Dummy Structure
Rotating points
Variable Iris
Beam Expander
B/S
Laser
Back Reflected Light
Focussing
CCD
TOU Bradboard test
• Preliminary discussions with the industry have outlined this
possible strategy for the TOU prototype test:
– Warm test (Research institutes): being the alignment
performed in warm conditions, a few test on the
expected TOU “warm performance” are foreseen: 1) a
test of the PSF quality on axis 2) an interferometric test
of the TOU optical quality
– Cold test (Research institutes + Industry): in a climate
chamber operating in vacuum at the required
temperature (-80º), we will perform: 1) a test of the PSF
optical quality on axis 2) an optical quality test
(interferometric or Hartmann test)
1) TOU PSF Test in warm
Performed by the Research Institutes
Tip-Tilting Flat Folding Mirror
Collimated Beam
Test Camera, adjustable
in focus
Off Axis Parabola
Vis Illuminator
Optical Fiber
2) TOU Optical Quality Test in warm
Performed by the Research Institutes
Zygo GPI FP
F/1.5 Transmission Sphere
4" - 1/10 Wave, P-V
DYNAFLECT Coated
TOU Cold Test Critical Items
• Problems due to the low testing T and to the
gradient between inside and outside the Climate
Chamber:
T~+20º
Lens effect
Shrinking effect
“Lens Effect” of the
Input Optical Window
Enlarging effect
– The input optical window of the Climate Chamber
is affected by aberrations (“lens” effect)
– If the test requires auxiliary optical components
inside the chamber, they will also be affected by
aberrations and particular care shall be given to
Climate Chamber
their mounts
Input optical window
Ambient
T~-80º
Flat ideal shape
TOU Cold Test strategy
• Characterize the Input Optical Window aberrations
• In any case, to minimize the lens effect of the Input
Optical Window, better to use parallel beams setup at
the climate chamber entrance
• Better NOT to use additional optics inside the climate
chamber
• If additional optics inside the chamber is needed,
better to use flat mirrors instead of concave mirrors,
again to minimize the “lens effect”
• 4 test proposed, but we are converging on test 1 and
2c, which require only one crygenic stage and no optical
elements inside the climate chamber
1) TOU PSF Test on axis in cold
Performed by the Research Institutes + Industry
Climate Chamber (T~-80º)
Input optical window
Flat Folding Mirror
Collimated Beam
Test Camera remotely
adjustable in focus
Off Axis Parabola
Advantages:
• Parallel beam in input
• No additional optical
parts inside the chamber
• Only 1 “cold” motoryzed
axis required
Optical Fiber
Vis Illuminator
2a) TOU interferometric cold test I
Performed by the Research Institutes + Industry
F/1.5 transmission sphere
Climate Chamber (T~-80º)
Interferometer
Input optical window
Disadvantages:
• No Parallel beam in input
• Additional optical parts required inside the chamber
• 2 “cold” motoryzed axis required
Advantages:
• The required optical element inside the chamber is a flat mirror
Flat Mirror (TT
remotely adjustable)
2b) TOU interferometric cold test II
Performed by the Research Institutes + Industry
Climate Chamber (T~-80º)
Collimated Beam
Interferometer
Input optical window
Concave Mirror F/1.5 (TT &
Focus remotely adjustable)
Disadvantages:
• Additional optical parts required inside the chamber
• The required optics inside the chamber is a fast concave mirror (“lens effect”)
• Three “cold” motoryzed axis
Advantages:
• Parallel beam in input
2c) TOU Hartmann test in cold
Performed by the Research Institutes + Industry
Hartmann Mask
Climate Chamber
T~-80º
Collimated Beam
P1
Off Axis Parabola
Input optical window
P2
CCD (movable
in focus)
Advantages:
- Parallel beam in input
- No other Optical Parts
Vis Illuminator
inside the chamber
- Only 1 “cold” motoryzed
axis required
Knowing with precision the relative position of P1 and P2 (linear stage with
encoder), we can know very precisely where is the TOU focus and measure the
optical quality in term of Encircled Energy, even without going with the CCD there!
Optical Fiber
Status
• The procurement of all the opto-mechanical
components needed for the Pre-BB, for the BB,
for the lab setup, for the “warm” and “cold”
test has started and all the order have been
placed since mid November 2010
• The industrial studies are about to be placed in
these days, hopefully all before the end of
2010, at latest in January 2011
Time planning
• Pre-Breadboard
– Opto-Mechanical components arriving 15/20 Jan 2011
– Alignment test results by end of Jan/mid Feb 2011
• TOU Breadboard
– Opto-Mechanical and test components arriving by 31 Mar
2011
– “Warm” alignment and test of the TOU prototype by 15
Apr 2011
– “Cold” test in Galileo by 25 Apr 2011
– Test report by 30 Apr 2011
• This planning has no contingency present and it is based
on the best effort delivery date of SESO; a shift
ranging from 1 to 4 weeks could easily happen
Items TBD with Daniele
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Light shields between each lenses (TOU)
Tools for lenses insertion (TOU&Dummy)
Tools (3 screws at 120deg) for lenses alignment (TOU&Dummy)
Reasonable machining precision in Z for the barrel and for the lenses
mounts (TOU&Dummy)
Spacers for focus?
Travel for XY adjustment (1mm?)
How do we hold and rotate the structure (Dummy)
At which minimum height will be the Optical Axis (Dummy)
Detector connection (Linear Stage)
How do we connect the lenses to their mounts? Glue? From
preliminary discussion with the industry, issue with the test in
vacuum for the glue degasing… Who will in case glue the lenses for
the prototype?