12 th Engelberg Lectures on Optics 2007 “Photonics in Space: a Challenge for Modern Technologies” Advanced Optics by Aspherical Elements III Driving Force: Applications Bernhard Braunecker Leica Research Fellow (retired) Braunecker Engineering GmbH Rebstein / Switzerland 7 th March 2007
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12th Engelberg Lectures on Optics 2007
“Photonics in Space: a Challenge for Modern Technologies”
Advanced Optics by Aspherical Elements IIIDriving Force: Applications
1. Airborne Imaging: Wide Field Lenses2. Spaceborne Communication: Small Field Telescopes3. Spaceborne Ranging: Small Field Telescopes4. Air/Spaceborne Imaging: Hyperspectral Systems
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1 Airborne Imaging
ImagingRanging Communication
Airborne
Terrestrial
Spaceborne
Photogrammetry, Remote Sensing
SSO
Berne, 1: 8‘500 (h = 1‘300 m)(15/4 UAG-S)
3 cm ground pixel resolution
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St. Gallen / Switzerland 1: 34‘000 (h = 2‘200 m) (ADS40)
10 cm ground pixel resolution
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Lens Cone 15/4 UAG-S (UltraAviogon)
The lens is for the film camera RC30; the film format is 9“ square. Note the ‚large‘ round exit pupil (the lens looks like a ‚cat‘) at large viewing angles to achieve homogenous illumination across field
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Long Tradition at Wild Heerbrugg, later Leica Geosystems
Honeycomb structure• No need for large external baffle byhexagonal tube array
Emitter
Fiber
Honeycomb Tube Baffle
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Pump LASER
Range Accuracy / Sensitivity Improvement
Lenslet Array
Fiber Laser Array Sensor Array
• Lidar strategy
• Pre-pulse 1 monitors ‚time of arrival‘
• Main-pulse 2 probes target
• Post-pulse 3 optically amplifies return pulse 2
• ‚Clock‘ or timebase of central importance
Leica Patent (Brn)
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Cassegrain Telescope
Lenslet Array
New Terminal Conceptsfor space applications
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4 Air / Spaceborne Hyperspectral Imaging
ImagingRanging Communication
Spaceborne
Airborne
Terrestrial
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APEX / K. Itten, J.Nieke
Pupils
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Principle of HS Imager, a pupil manipulator
Source Object Pupil 2 Slit Pupil 1 CCD
SpectrometerGround Imager
•Chromatic spectrum of a ground pixel is spread along track, Swath line of all ground pixels across track
Scrambler
The ‚scrambler‘ makes the recorded intensity independant to polarisation fluctuations by theatmosphere. It eliminates depolarisation effects of the Optics and allows a better radiometricresolution.
Leica Prototype6 Modules (FoV= ± 7°), each with GroundImager & Spectrometer, to cover a wideangle FoV of 84°.
Priority levels:
•P1: Noise Equivalent Albedo < 10-4
•P2: 400 –1100 nm; 1.2 nm resolution
•P3: 250 m ground pixel at 650 km orbit
Integration Sphere
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New Applications: Multiplex Processor
White Source
Object Pupil Image Pupil CCD
A B C
B C A
C A B
A B C
B C A
C A B
¤
¤
¤Matched filter
A
B
C¤ ¤ ¤
¤ ¤ ¤
¤ ¤ ¤
The different pattern A,B,C,.. in the object plane are simultaneously detected as colour coded autocorrelation peaks. Using SF10 and 400-700 nm, one canprocess about 30 holograms of different objects of spatial bandwidth of 6 lp/mm
See B. Braunecker, O. Bryngdahl, Optics Communications, Vol 40,Number 5, p.332 (1982)
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Hyperspectral Imaging
– Future Trends• Seamless adaption HS Imager as next generation of Digital Sensors• Better Balance of system performance between radiometric, spectral and
spatial range/resolution– Improve Ground imager (wide angular viewing)– Look for alternative spectroscopic concepts
• New Technologies:– Use Glass ceramics with n>1.9, transparent to 5 mue for unifying
visual and IR channels– Use Aspheres in GI and Spectrometer– Use monolithic concepts to improve pointing stability
• Look for new applications besides remote sensing
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Conclusions & Outlook
• APPLICATIONS– Imaging
• Film Digital / Color Hyperspectral– Ranging / Communication
• Miniaturisation, but keeping the large collecting aperture Integration
• OPTICS– Wide Angle Lens Systems : Spheres Rotational symmetric Aspheres– Small Angle Mirror Systems: Conical Aspheres Free Form Aspheres
• SYSTEMS– Sensorfusion of Imaging & Ranging & Tracking &…– „Time Base / Clock“ of central relevance of remote sensing systems