1. Micro Hyperspectral Systems For UAVs
If a picture is worth 1000 words, a hyperspectral image is worth almost 1000 pictures
RSPSoc and NERC Cluster UAV Workshop
University of Durham, 7-8 June 2011
Dr John P Ferguson
Photonics & Analytical Marketing Ltd

2. TOPICS TO BE COVERED
Headwall Photonics Explanation of Hyperspectral Imaging Some applications The Headwall Micro Hyperspec Imaging from UAVs

3. HEADWALL PHOTONICS INC
American Holographic, Inc.
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

4. 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

5. Applications of Headwall Hyperspectral Systems
Space Piloted UAV Ground-based Handheld
Small Satellite
Multiple
Platforms
Base protection
Reconnaissance

6. 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

7. Example – Airborne remote sensing
Image Source: BAE Systems

8. THE VISIBLE LIGHT SPECTRUM

9. What information can the spectrum tell us?

10. The type of building material used

11. The type of vegetation

12. The rock strata

13. The type of ground

14. How does it work?

15. AN OUTLINE OF HYPERSPECTRAL IMAGING

16. A TYPICAL SCENE

17. THE CAMERA’S VIEW

18. THE VIEW THROUGH A SLIT - PIXELS IN ROW 7

19. PIXELS IN ROW 11

20. PIXELS IN ROW 17

21. THE HYPERSPECTRAL DATA

22. CLOSER TO REALITY

23. A HYPERSPECTRAL DATA CUBE

24. Some technical stuff

25. Hyperspectral Design Options
Prism-Grating-Prism
Transmission-based
grating system
Aberration-Corrected Concentric
All-reflective system
Three reflective surfaces
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

26. THE HEADWALL PATENTED SPECTROGRAPH DESIGN
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
Entrance
Slit
Original holographic
high efficiency
convex grating
Detector
Plane

27. 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

28. THE SALES PITCH Key Imaging Spectrograph Risks:
Fore-optics  Imaging Spectrograph  Detection Electronics
Key Imaging Spectrograph Risks:
Keystone (spatial distortion)
Smile (spectral distortion)
Vignette
Scatter (transmissive materials, poor surface qualities, replicated optics)
Stray Light (overfilled optics, secondary diffracted orders, inadequate baffeling)
Chromatic Aberrations and Astigmatism
Low Optical Dynamic Range

29. CAMERA CONSIDERATIONS
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 depth
Pixel resolution (spatial and spectral)
Spectral band sensitivity
Readout speed
Readout method
Second order detection

30. Traditional Hyperspectral Imaging Deployments
Remote Sensing
Military/Defense
Ocean
Monitoring
Surveillance
Search & Rescue
Geological
Mapping
Target Identification
& Tracking
Spectral
Tagging
Environmental
Analysis
Photos: Courtesy of NRL, Space Computer, BAE, General Atomics

31. 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 nm
NIR nm

32. Micro-Hyperspec in Agriculture

34. Micro-Hyperspec for Airborne Turrets & Gimbals
Fully integrated –
sensor, GPS/INS,
processor board
Designed for
integration
into UAV turrets
& gimbals
Single
attachment
point

35. Micro-Hyperspec – Small Tier UAVs Mounting Options
Tier 2 UAV Hyperspectral mounting options Micro-Hyperspec within Payload Bay
Payload bay or forward turret

36. Micro-Hyperspec – Payload Bay Mounting Tier II UAV

37. 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

38. High Efficiency Sensors
Three spectral ranges –
Ext VNIR ( nm), NIR ( nm), & 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
Custom designed fore-optics
High Efficiency sensors offer
peak efficiency greater than 90%,
minimum 70%

39. Thank you for listening