Thesis Defense Presentation

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Progress on Table-Top Target Tracking
Engagement Demo
Presented by Lane Carlson1 M. Tillack1, T.
Lorentz1, J. Spalding1 N. Alexander2, G. Flint2,
D. Goodin2, R. Petzoldt2 (1UCSD, 2General
Atomics) Presented at HAPL Project Review Oak
Ridge National Laboratory, TN March 21-22, 2006
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Target Engagement Demonstration

• Purpose Table-top demo of key elements of the
  target engagement concept
• Progress Incremental successes ? integration to
  make a proof-of-principle system

• Key Requirements
• 20 µm engagement accuracy in (x,y,z) at 20 m
  (precision of 10-6)
• Few ms position update rate

• Goals of this work
• Demonstrate successful table-top experiments to
  identify and solve any critical issues.
• Final goal is the complete integration of key
  elements of the target engagement concept,
  including hitting target on-the-fly.

• Compliments and improves glint system, backup,
  diagnostics

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Today I will discuss progress on the Doppler
Poisson spot system demos

• Final goal of demo includes integration of
• Poisson spot illumination detection (x,y)
  position
• Doppler fringe counting (z position)
• Active beam steering
• Glint system

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Summary of progress on Doppler fringe counting
Poisson spot detection
Poisson Spot (x,y) Progress 5 µm tracking
precision with 25 ms update rate at 10 m
range Plan Improve update rate
Fringe Counting (z) Progress 5 µm
repeatability over 5 mm travel Plan Longer
travel
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Poisson Spot Tracking Update
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Continuous Poisson spot tracking has previously
been demonstrated

• We have demonstrated continuous (25 ms) PS
  tracking and beam steering with the beam train.
• Update speed is limited by the quality speed of
  the equipment, which is being upgraded.

Poisson spot imaged on CMOS chip 1mm
4mm sphere on translation stage
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Next generation off-the-shelf hardware has been
evaluated (and mostly ordered)
Poisson Spot Detection
FIRST GENERATION HARDWARE NEXT
GENERATION HARDWARE Basler camera 100
fps Mikrotron camera
1000 fps Firewire interface 120 MB/s
Cameralink interface 680
MB/s Multitasking computer 3.0 GHz
Dedicated computer 3.8 GHz Operating
system MS Windows Operating
system dedicated
real-time Speed attained 25 ms
Speed goal lt5
ms Thorlabs
mirror 600 Hz resonant freq.
PI fast steering mirror 2.4 kHz
resonant freq. (0.5 µrad resolution)
12 spokes
Physik Instrumente fast steering mirror
Mikrotron camera
Beam Steering Demo
A careful hardware assessment has been done. We
have reasonable expectations to achieve 5 ms
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Innovative Techniques to Further Increase Speed

• Pixel binning - averages groups of pixels for
  less resolution but faster speed
• Use position sensitive detector (PSD) to
• approximate spot center
• reduce region of interest

3D intensity profile
72 spokes
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Doppler Fringe Counting Update
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Additional fringe counting results confirmed our
short range measurements

• Desire continuous z-axis tracking with 3 in 105
  accuracy.
• Demonstrated 5 µm repeatability at short range
  (0.5 m) travel (5 mm on micron stage.)

Similar intensities
Results show 95 of moved targets are within 5
µm. Meets our goal, but for a very limited range.
Similar results obtained with metal sphere
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A more powerful laser longer-travel delivery
system are needed to extend the useful range
Similar intensities

• Initial setup was a preliminary
  proof-of-principle experiment
• Limited by HeNe laser stability (power,
  polarization, wavelength)
• extraneous fringe counting
• Low power (0.5 mW) limited useful range
• Mechanical vibration backlash in micrometer
  stage
• Doppler counts forward backward fringes

• New telecom laser has
• Greater wavelength stability ( 20 pm)
• Longer wavelength (1.54 µm) higher power (63
  mW)
• slower fringe counting greater return signal
  over 10 m

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Target Transportation Vertical Delivery System
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More prototypic target delivery system was needed

• Beam train allowed open-loop steering demo at
  10 cm/s, but unprototypic motion.
• Desired a more prototypic target to track.

• Drop tower provides continuous target
  acceleration under the influence of gravity.
• Hopper can deliver targets continuously.
• Target achieves 5 m/s final velocity.

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Drop tower - first step in free-flight tracking
Target trajectory

• Operation of the device provides similar
  placement accuracy as a power plant injector.
• Air flow is controlled using an enclosure.

Crossing Sensor 1
C2
1.5 m
C3
3 mm
Carbon paper location
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Real-time, In-flight Target Tracking (1 of 10)
We have demonstrated real time (25 ms) in-flight
tracking centroiding of the Poisson spot with
vertical delivery.
Note target flies into, then out of cameras
field of view

• 10-frame in-flight trajectory sequence taken 25
  ms apart

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Real-time, In-flight Target Tracking (2 of 10)
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Real-time, In-flight Target Tracking (3 of 10)
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Real-time, In-flight Target Tracking (4 of 10)
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Real-time, In-flight Target Tracking (5 of 10)
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Real-time, In-flight Target Tracking (6 of 10)
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Real-time, In-flight Target Tracking (7 of 10)
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Real-time, In-flight Target Tracking (8 of 10)
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Real-time, In-flight Target Tracking (9 of 10)
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Real-time, In-flight Target Tracking (10 of 10)
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A zero-crossing sensor is needed to establish
time zero for fringe counting

• Purpose is two-fold
• To establish a zero-crossing point to start
  counting fringes
• To verify information from Doppler fringe
  counting method

Drop tests indicate 100 µm repeatability
at third crossing sensor
Collimating lens
6x1 mm photodiode
LED
Timing errors due to setup, alignment, air
pressure, ambient light

• Repeatability of time between target crossing
  sensors
• Detector 1 14 µs
• Detector 3 anticipated passing 38 µs

• Standard deviation of time between target
  crossing sensors
• Detector 1-2 12 µs
• Detector 2-3 5 µs

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Progress plans - more prototypic with
continuing integration
Poisson system Progress In-flight tracking 5
µm at 10 m every 25 ms Plans Implement faster
camera real-time OS Doppler
system Progress Reproducibility measurements
5 µm over short range Plans Implement more
stable powerful laser for longer range System
Integration Progress Built drop tower for more
prototypic target flight Plans Integrate
Poisson spot fringe counting techniquesCrossin
g Sensors Progress Zero-crossing repeatability
100 µm Plans Combine verify with fringe
countingBeam Steering System Plans Acquire
better FSM, develop verification techniques for
hitting target on the fly