Micro Hyperspectral Systems For UAVs If a picture is worth 1000 words, a hyperspectral image is...
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Micro Hyperspectral Systems For UAVs If a picture is worth 1000 words, a hyperspectral image is worth almost 1000 pictures Dr John P Ferguson Photonics & Analytical Marketing Ltd RSPSoc and NERC Cluster UAV Workshop University of Durham, 7-8 June 2011
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Transcript of Micro Hyperspectral Systems For UAVs If a picture is worth 1000 words, a hyperspectral image is...
Micro Hyperspectral Systems
For UAVs
If a picture is worth 1000 words, a hyperspectral image is worth almost 1000
pictures
Dr John P FergusonPhotonics & Analytical Marketing Ltd
RSPSoc and NERC Cluster UAV WorkshopUniversity of Durham, 7-8 June 2011
TOPICS TO BE COVERED
Headwall PhotonicsExplanation of Hyperspectral ImagingSome applicationsThe Headwall Micro HyperspecImaging from UAVs
HEADWALL PHOTONICS INC
1976 - American Holographic, Inc.
2000 - Agilent Technologies acquisition
2003 – Headwall Photonics launched
Currently 40 employees
Factory in Fitchburg, Massachusetts, USA
Producers of imaging spectrometers, OEM spectral engines, original holographic gratings
Applications of Headwall Technology• Hyperspec V10 – Marine Ocean Buoy Project (MOBY)• Hyperspec VS30 – NRL airborne requirement for remote sensing and ocean
color monitoring• Hyperspec VS15 – USAF airborne mine detection in littoral zones • Hyperspec VS15 – USN Predator-based project for Project Warhorse • Hyperspec VS15 – NRL Ocean PHILLS sensor• Hyperspec VS15 – AFRL LWIR sensor for polarimetric sensing for battlefield
surveillance • Hyperspec VS25 – Selected by NASA for International Space Station deployment • Hyperspec VS25 – First UAV deployment• Hyperspec VS – Custom UV/MCP unit deployed for AFRL missile plume tracking • Hyperspec VS50 – Airborne SWIR sensor • Micro-Hyperspec VNIR and NIR – Introduced in 2006 for UAV and SUGV
deployment • Hyperspec-VNIR – NASA deployment for AVIRIS project augmentation• Hyperspec-VNIR, Hyperspec-NIR, Hyperspec-SWIR – integrated instruments for
commercial applications• Micro-Hyperspec – UAV remote sensing
Applications of Headwall Hyperspectral SystemsSpace
Piloted
UAV
Ground-based
Handheld Reconnaissance
Base protection
Multiple Platforms
Small Satellite
WHAT IS HYPERSPECTRAL IMAGING?
• Collection of high resolution spectral detail over a large spatial and broad wavelength region from within each pixels instantaneous field of view
• Also known as imaging spectroscopy, chemical sensing• Chemical/spectral imaging within spatial dimension
• Many definitions– Common requirement = > ~ 100 spectral bands– No definition has explained spatial requirements
Example – Airborne remote sensing
Image Source: BAE Systems
THE VISIBLE LIGHT SPECTRUM
What information can the spectrum tell us?
The type of building material used
The type of vegetation
The rock strata
The type of ground
How does it work?
AN OUTLINE OF HYPERSPECTRAL IMAGING
A TYPICAL SCENE
THE CAMERA’S VIEW
THE VIEW THROUGH A SLIT - PIXELS IN ROW 7
PIXELS IN ROW 11
PIXELS IN ROW 17
THE HYPERSPECTRAL DATA
CLOSER TO REALITY
A HYPERSPECTRAL DATA CUBE
Some technical stuff
25 Proprietary and Confidential
Hyperspectral Design Options
Aberration-Corrected Concentric– All-reflective system– Three reflective surfaces
Prism-Grating-Prism– Transmission-based grating system
Headwall’s imager design optimized for …
Imaging performance – • Aberration-corrected
• Minimal stray light• High signal-to-noise• High dynamic range
• High spectral/spatial resolution• Efficiency across total spectral range
Deployment in harsh environments• Ruggedized & durable• Small, compact size
• Minimal thermal expansion
Attributes- Integrated spectrometer solution - High spectral/spatial resolution- Very tall image slit - Very low image distortion- Low stray light, high signal-to-noise- Small package size- Flight hardened no moving parts
THE HEADWALL PATENTED SPECTROGRAPH DESIGN
EntranceSlit
DetectorPlane
Original holographichigh efficiency convex grating
Hyperspec© Concentric Design
• Advantages - selection of concentric design …– Extremely compact nature– Image quality (spectral/spatial resolution)– Superior aberration-correction characteristics– Lower F number– All reflective design
• Additionally, Headwall sensors offers additional benefits …– Balanced spectral performance across range– Lower stray light– Tall image slits - Spectral & spatial performance off-axis– Performance in lower VIS / blue region
Fore-optics Imaging Spectrograph Detection Electronics
Key Imaging Spectrograph Risks: Keystone (spatial distortion)
Smile (spectral distortion)
VignetteScatter (transmissive materials, poor surface qualities, replicated optics)
Stray Light (overfilled optics, secondary diffracted orders, inadequate baffeling)
Chromatic Aberrations and AstigmatismLow Optical Dynamic Range
THE SALES PITCH
Fore-optics Imaging Spectrograph Detection Electronics
Key Detection Electronics Risks: Base chip dynamic range - pixel full well capacity / (dark current + read noise)
A/D bit depthPixel resolution (spatial and spectral)
Spectral band sensitivityReadout speedReadout methodSecond order detection
CAMERA CONSIDERATIONS
Traditional Hyperspectral Imaging Deployments
Remote SensingSurveillance
Target Identification & Tracking
Spectral Tagging
Search & Rescue
Ocean Monitoring
Geological Mapping
EnvironmentalAnalysis
Photos: Courtesy of NRL, Space Computer, BAE, General Atomics
Military/Defense
Micro-Hyperspec™ for UAVs
Design goals:– Very small size, form factor
• Less than 1 lb pounds– Excellent imaging and S/N
performance• Aberration-corrected optics
– Low-power CCD/CMOS sensor – Modular for variety of input &
detector options
Spectral Ranges• VNIR - 400-1000nm• NIR - 900-1700nm
Micro-Hyperspec for Airborne Turrets & Gimbals
Fully integrated – sensor, GPS/INS, processor board
Designed for integration
into UAV turrets & gimbals
Single attachment
point
Micro-Hyperspec – Small Tier UAVs Mounting Options
Tier 2 UAV Hyperspectral mounting options Micro-Hyperspec within Payload Bay- Payload bay or forward turret
Micro-Hyperspec – Payload Bay Mounting Tier II UAV
Fiber-Optic-Downwelling Irradiance Sensor (FODIS)
• In-flight calibration of Hyperspec© sensor– Fully reflective FODIS module allows frame-by-frame real-time tracking of
the solar Irradiance allowing
High Efficiency Sensors
38 Proprietary and Confidential
• Three spectral ranges – Ext VNIR (600-1700nm), NIR (900-1700nm), & SWIR (900– 2500nm) • Extremely high optical efficiency• Lightweight for airborne missions• Athermal design for measurement accuracy and stability• Tall image slit for wide field of view, swath path efficiency
NIR High Efficiency Modeled and Measured Grating Efficiency
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800
Wavelength (nm)
Eff
icie
ncy
(%
)
Measured
Modeled
High Efficiency sensors offer peak efficiency greater than 90%, minimum 70%
• Custom designed fore-optics
Thank you for listening
