Transcript Schmidt optics design for K-EUSO

Okochi Hall, RIKEN, Wako, Japan,
December 13th, 2016
The 20th JEM-EUSO International meeting
Schmidt optics design for K-EUSO
P. Sandri (a), P. Mazzinghi (b)
(a) CGS Spa, an OHB Company - Italy
(b) National Institute of Optics CNR, Italy
With the collaboration of all the Optical Working Group of K-EUSO
TABLE OF CONTENT
1- Baseline solution of the Schmidt optics design for K-EUSO
2- Company presentation and technology
3- Conclusions
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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THE OPTICAL DESIGN OF THE
SCHMIDT CAMERA FOR K-EUSO
BASELINE SOLUTION
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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INTRODUCTION
•
The baseline optical design here presented is the results of a strong interaction
with the Optical Working Group of K-EUSO, composed by:
-
Sergei Sharakin, SINP MSU
Pavel Klimov, Lomonosov Moscow State University
Vladislav Druzhin, Bauman MSTU
Yoshiyuki Takizawa, RIKEN
Piero Mazzinghi, INO
Paolo Sandri, CGS
•
A further optimization of the baseline design might be necessary according to
the output of the present meeting.
•
Some analyses are preliminary at the moment and need a more detailed phase
after this meeting.
•
Some analyses (e.g. structural, thermal) have not been performed yet due to
lack of time.
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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MAIN OPTICAL REQUIREMENTS
- Entrance Pupil Diameter = 2,5m
- Field of View = 40degrees
- Spectral band = [337; 391]nm
- Ground resolution = between 500m and 1km at height of 450km
- Focal length = 1,75m
- Relative aperture = F/number 0,7
- Level of stray-light: TBD, but LOW!
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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BASELINE OPTICAL DESIGN
LAYOUT
Spherical mirror
Corrector plate
Focal Surface
Entrance aperture
Double Donut Schmidt Camera (named by P. Mazzinghi)
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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BASELINE OPTICAL DESIGN
PERFORMANCES
•
Polychromatic RMS spot radius as a function of the field of view of the NOMINAL design
(Average) required ground resolution
The NOMINAL BASELINE design fully meets the requirement of ground resolution
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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BASELINE OPTICAL DESIGN
PERFORMANCES
•
Vignetting & throughput as a function of
the field of view (FoV)
•
The throughput is calculated with enhanced aluminum coating for the mirror (R≈95%).
•
The throughput can be enhanced with a dielectric coating (R≈99%) for the mirror, depending on the
chosen substrate for the mirror.
•
The throughput will be updated including the envelope of the electronic boxes (correct
recommendation from Takizawa) when available.
• The vignetting and throughput at the edge of the FoV can be optimized at the expenses of the spatial
resolution. An exercise has been performed…
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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BASELINE OPTICAL DESIGN
PERFORMANCES
•
… an exercise has been performed in this early phase of the project (1) by moving the
entrance aperture closer to the corrector and (2) by reducing the longitudinal size.
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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BASELINE OPTICAL DESIGN
PERFORMANCES
•
The result of this exercise is represented by the red curves hereunder:
•
Reduced vignetting ( enhanced
throughput) at the edge of the field of
view
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
•
•
•
Reduced ground resolution on nominal design
Effect of tolerances is not included in this plot
Ground resolution of 750m at 450Km is met for
the nominal design
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BASELINE OPTICAL DESIGN
CORRECTOR
•
•
Material = PMMA000, special Grade UV-transmitting polymetyl methacrylate (Mitsubishi Rayon Co. LTD, Japan)
Weight 53Kg
Left: refractive index for CYTOP and PMMA-000. Right: transmittance for CYTOP and PMMA-000 for 15-mm
thickness [extracted from A. Zuccaro Marchi et al. “The JEM-EUSO optics design”, 32nd Intern. Cosmic Ray
Conference (2011)] .
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BASELINE OPTICAL DESIGN
CORRECTOR
•
Material = PMMA000
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BASELINE OPTICAL DESIGN
CORRECTOR
•
The lens needs to be protected from electron components of radiation.
•
Solutions (courtesy of Takizawa):
1- SiO2 coating on the front surface of the lens
2- CYTOP coating on the front surface of the lens
3- Use CYTOP lens (in this case optimization of the baseline with CYTOP)
(see for example Y. Takizawa et al. “Protection of the plastic front lens of the JEM-EUSO telescope
from atomic-oxygen erosion”)
And…
The external baffle (thanks to the
entrance aperture placed outward)
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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BASELINE OPTICAL DESIGN
WHY A CORRECTOR WITH A HOLE?
1- Easier manufacturing. Identical sections obtained - for example - with
injection molding and then
assembled together (e.g. optical cement or mechanical support)
1,2m
2- Easier mechanical support. No risks of damaging, holding it from
the robust outer edge.
3- The hole of the corrector can be an access for metrology, LIDAR, or …
4- Weight reduction
1 + 2 + 3 + 4 = Benefits of the holed corrector
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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BASELINE OPTICAL DESIGN
MIRROR
-
Spherical mirror (EASY to manufacture and to test)
-
Diameter 4,0m
-
Central hole with diameter 290mm
-
The mirror is segmented into N smaller elements (dimensions
segment polished to spherical shape
and shape TBD), each
Conceptual view (only!)
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BASELINE OPTICAL DESIGN
FOCAL SURFACE
-
Curved focal surface
-
Convex shape
-
Diameter of focal surface 1,28m
- Radius of curvature ≈ 1,8m
mirror
corrector
Focal surface
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BASELINE OPTICAL DESIGN
TOLERANCES
 We have performed a tolerance analysis including:
-
Manufacturing, assembling and integration tolerances;
 Method: Montecarlo analysis with 10.000 runs and uniform statistics
 The tolerance analysis allowed us to:
1- discuss with engineers the manufacturability of the lens and of the mirror.
=> we received a positive feedback on manufacturability.
2- identify the most critical tolerances.
=> we have a solution for the critical tolerances.
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BASELINE OPTICAL DESIGN
TOLERANCES
Input for the Montecarlo analysis with Zemax
OpticStudio
Value
Radius of curvature of mirror
± 0,1mm
Radius of curvature of focal surface
± 1mm
Central thickness of corrector
± 0,1mm
Distance corrector to mirror
± 0,2mm
Position of the focal surface
± 0,1mm
Decenter of the corrector
± 0,2mm
Tilt of the corrector
± 3arcmin
•
Structural and thermal analyses are
needed to verify if these tolerances can
be maintained on-orbit on the ISS
environment (T, vibrations due to
boosting, …)
•
Each segment of the mirror needs to be
adjusted in tilt-X and tilt-Y with three
actuators every  time interval (to be
calculated)
Critical parameters
Decenter of the mirror
± 0,1mm
Tilt of the mirror
± 2arcmin
RMS surface form of corrector
± 3,16microns (10 fringes at He-Ne)
RMS surface form of mirror
± 0,791microns (2,5 fringes at He-Ne)
Refractive index of corrector
± 0,0003
Abbe number of corrector
± 0,2%
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
•
We can do this job
(with LATT)!
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BASELINE OPTICAL DESIGN
TOLERANCES
•
The effect of the MAIT (= Manufacturing, Assembling, Integration and Testing) tolerances is to slightly
worsen the nominal ground resolution.
•
Montecarlo trials at a level of confidence of 1 (≈68%) satisfy the requirement of ground resolution.
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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BASELINE OPTICAL DESIGN
NON SEQUENTIAL MODEL
Ray trace for the field of view of 20deg
Non-sequential
Sequential
Including:
• surface micro-roughness,
• mechanical items,
• segmentation of corrector,
• Preliminary segmentation of mirror.
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BASELINE OPTICAL DESIGN
STRAY-LIGHT ANALYSIS
•
This stray-light analysis is performed for a Schmidt camera designed for a free flyer (FFEUSO) covering 50° field of view.
•
Stray-light analysis are time consuming and have not been updated due to lack of time.
•
We expect similar results for the baseline solution of K-EUSO.
In field
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
Out of field
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BASELINE OPTICAL DESIGN
STRAY-LIGHT ANALYSIS
•
QUESTION: is a further reduction of stray light necessary?
Possible with a suitable external baffle
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COMPANY PRESENTATION
&
TECHNOLOGY
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COMPANY PRESENTATION
United under one roof
CGS:
•
•
•
Heritage: AGILE, SAR-Lupe, AMS, LARES, …
Earth Observation Programs: PRISMA, OPSIS,
MWI,FLEP, ASIM, ARMES, M-Z, LATT, …
Science and Universe Programs: LISA Pathfinder, Bepi
Colombo, EUCLID, METIS, …
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
http://www.cgspace.it/
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CURRENT PROJECTS IN CGS IN THE OPTICAL FIELD
METIS
 Italian contribution to ESA Solar
Orbiter (ESA M1) mission, aimed to
the exploration of the Sun and the
inner heliosphere.
 Inverted-occultation coronagraph
with two separate channels: in the
visible light (VL) and at 121.6nm.
FLIGHT MIRROR
ASSEMBLY UNDER TEST
NEOSTED
 Ground based optical sensor for Space Surveillance and
Tracking (SST) and Space Situational Awareness Near-Earth
Object Segment (SSA-NEO).
 Mirror diameter 1m
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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RECENT HERITAGE OF CGS ON ACTIVE OPTICS
•
CGS, as a coordinator of a team composed by INAF (www.inaf.it), CNR-INO (www.ino.it),
ADS International (www.ads-int.com), Microgate (www.microgate.it) and ESA, developed
the LATT = Large Aperture Telescope Technology
•
F/6 spherical mirror
•
40 cm diameter
•
19 actuators
•
shell:
FLIGHT MIRROR
ASSEMBLY UNDER TEST
1mm thick Zerodur
•
Ref Body:
Alum. Honeycomb
+ CFRP
INAF
INO
See for example R. Briguglio et al. Toward Large Diffraction Limited Space Telescopes With The LATT
Lightweight Active Primary, ICSO (2016).
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OPTICAL METROLOGY IN CGS
 Concave ellipsoidal mirrors of METIS tested in ISO5 clean room.
 Innovative technique for the alignment of the uncoated mirrors has been developed (ICSO 2016).
 Wavefront error measurement with Shack Hartmann wavefront sensor.
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TECHNOLOGY
Input:
•
Large size mirror (= 4m in diameter)
•
Coarse requirement on the surface form error (≈2,5fringes RMS)
•
Fine requirement on the alignment
•
Space requirements on power, mass, size, reliability
Mirror topology:
• Segmented to reduce the mass
•
Deployment to fit the launcher
Structural and thermal analysis are
needed to verify if the identified
tolerances can be maintained onorbit on the ISS environment (T,
vibrations due to boosting, …)
Conceptual view (only!)
Example: stowed JWT
Mirror deployment technology ALC: Advanced Lidar Concept
ESA contract (ITT AO/1-4629/NL/CP Ref. 2053, Advanced Lidar Concept, ALC)
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TECHNOLOGY
Input:
•
Large size mirror (= 4m in diameter)
•
Coarse requirement on the surface form error (≈2,5fringes RMS)
•
Fine requirement on the alignment
•
Space requirements on power, mass, size, reliability
Actuation:
3 x segment, set & forget
Solution adopted in
MAGIC & JWT
The LATT derived from the active optics allows for a
control strategy
LATT (Large Aperture Telescope Technology)
(ESTEC Contract No. 22321/09/NL/RA)
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Mirror deployment technology
ALC: Advanced Lidar Concept
ESA contract (ITT AO/1-4629/NL/CP Ref. 2053, Advanced Lidar Concept, ALC)
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ALC: MIRROR DEPLOYMENT TECHNOLOGIES
A 4 m  deployable mirror for LIDAR application has been developed on a ESA
contract (ITT AO/1-4629/NL/CP Ref. 2053, Advanced Lidar Concept, ALC)
Satellite concept after deployment
Diffraction limited 4 m  telescope !
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
Stowed configuration
for launch
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ALC: CAPABILITY OF ANALYSIS
•
THERMAL LOADS DISPLACEMENT ANALYSIS
Optical surface: 6.71 µm; Back-Plate: 7.56 µm;
Back-Plate
Optical surface
•
INERTIAL LOADS DISPLACEMENT ANALYSIS
The maximum primary mirror displacement is 4.73
µm, while the secondary mirror maximum
displacement is 3.44 µm.
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ACTIVE OPTICS
LATT
Large Aperture Telescope Technology
(ESTEC Contract No. 22321/09/NL/RA)
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WHAT IS THE LATT?
INAF
1-LATT is a response to an ESA TRP call
for the:
 Studying
 Prototyping
of an active mirror for space telescopes
Active mirror?
The optical surface is controlled against
thermo-mechanical bendings
INAF
 Requirements
 Large format
 Possibly deployable/segmented
 Light weighted
 Scientific cases
 Astronomical space telescopes
 IR? UV?
 LIDAR
 Earth monitoring
 Telecommunications
Preliminary study:
• ALC project in 2007
LATT prototyping:
• ESTEC/Contract No. 22321/09/NL/RA
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
2- The LATT team:
• has 15 years expertise in ground based
adaptive optics (AO).
• developed the adaptive secondary mirror
concept.
• implemented it into AO facilities at 8m class
telescopes (LBT, Magellan, VLT)
• Currently involved in Extremely Large
Telescope projects (E-ELT, GMT) for the
development of large format deformable
mirrors
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LATT: ENVIRONMENTAL TESTS
Thermal test
INAF
Thermo-vacuum test
Optical test
Temp: -25°C55°C
Tested @ 1e-5mbar
Electrostatic lock test
Vibration test
Lock pressure: 600 N/m2
plus vacuum funct. test
Max acceleration: 11g
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
WFE comparable with AO
after removing the
membranes deformation
(λ/6 @UV)
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LATT ON THE WEB
•
ESA 2016: D. Gallieni et al. TOWARD LARGE ACTIVE PRIMARY MIRRORS FOR
SPACE TEELSCOPES, presented at the Coordinated Final Presentation Days
•
ICSO 2016: R. Briguglio et al. TOWARD LARGE DIFFRACTION LIMITED SPACE
TELESCOPES WITH THE LATT LIGHTWEIGHT ACTIVE PRIMARY
•
ICSO 2014: Development of Large Aperture Telescope Technology (LATT): test results
on a demonstrator bread-board
•
…
INAF
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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CONCLUSIONS
1- The optical working group (OWG) of K-EUSO together with the LATT team has
the experience to design and to manufacture the Schmidt camera for K-EUSO.
2- The OWG has a BASELINE optical solution for the telescope of K-EUSO
satisfying all the optical requirements.
3- A preliminary assessment of tolerances is provided.
4- Some analyses (thermal, structural) need to be performed, others (tolerances,
stray-light) need to be performed at a deeper detail.
5- The optical items (corrector, mirror, focal plane) can be manufactured and
tested.
6- Some modifications on the baseline optical design are possible according to
the output of the present meeting: design can be tuned in accordance to
hierarchy of the requirements.
7- CGS has metrology labs in ISO5 clean rooms, thermal vacuum chambers,
precision measurements machines, qualified processes (e.g. on bonding, …).
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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THANK YOU … AND … ANY QUESTION?
A special thank to:
- all members of the K-EUSO Optical Working Group for the good work performed
together in a very short time
- Prof. P. Picozza for having invited us to the meeting, giving us the possibility to
present the work on optics
- RIKEN for the kind hospitality
- all the audience for the attention and interest
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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BACK-UP SLIDES
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ADVANCED OPTICAL DESIGN
Schmidt camera designed for a free-flyer with field of view = 50°
Slightly aspheric mirror
OR
(Multi-zone mirror,
proposed by S. Sharakin
and colleagues)
DDSC in
sequential modality of Zemax
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
Spider arms
The Non-sequential modality of Zemax
includes the mechanical structure, vanes, …
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ADVANCED OPTICAL DESIGN
(Average) required ground resolution
Baseline
“Advanced” optimized for 50°
“Advanced” optimized for 40°
Baseline = spherical mirror
Advanced = slightly aspheric mirror
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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ADVANCED OPTICAL DESIGN
• The holed corrector presents the same advantages already presented for the
baseline solution (easier manufacturing and mechanical assembling, possibility to
introduce metrology or lidar, weight reduction)
• In the advanced solution the diameter of the central hole can be enlarged to 1m,
against the 20cm of the baseline solution.
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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EXPOSURE COMPARISON
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OPTICAL INVARIANT
• The dimension of the image is calculated with the optical invariant
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ANGLE OF INCIDENCE
• The dimension of the image is calculated with the optical invariant
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TEST
• The spherical mirror can be tested (interferometrically) with a classic set-up.
• Testing the aspheric corrector (with the tested mirror): many set-ups are possible, e.g.:
Collimated beams parallel to optical axis
Collimated beams tilted
Or a Shack Hartmann test
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
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TRANSMISSION OF A FRESNEL LENS
• The transmission of a Fresnel lens is calculated in some papers.
•
•
At relative aperture
F/0,7
For 3 lenses
We have:
(0,67)^3=0,30
A. Davis, ”Raytrace assisted analytical formulation of Fresnel lens transmission efficiency” in Novel Optical
Systems Design and Optimization XII, edited by R. John Koshel, G. Groot Gregory, Proc. of SPIE Vol. 7429,
74290D (2009).
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TRANSMISSION OF A FRESNEL LENS
• Non sequential ray-trace for camera with Fresnel lenses:
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LATT: HOW DOES IT WORK?
Thin glass shell
Magnet
+
Reference Body
(mirror structure)
Actuator
C ~ dist
Capacitive
position
sensor
Actuators:
Internal metrology:
Contactless, voice coil motors + magnet
glued on the back of the shell:
• low print-through (nm)
• no hard point in case of failure (fail
safe)
• very large range (hundreds of µm)
Actuators are commanded in
local close loop, fed by the
capacitive position sensors.
CGS/Schmidt optics design for K-EUSO/December 13th, 2016
Contactless sensing: the TS
is detached from the RB
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LATT: A BRICK FOR MORE COMPLEX SYSTEMS
1m, 7 segments
3-5m, segmented
Addressing segmentation
and co-phasing
1m, monolithic
LATT OBB:
40 cm, 19 actuators
Addressing larger apertures
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