development of eye-safe lidar technology for aerosol and ... · development of eye-safe lidar...

Engineered for LifeITT IndustriesITT Industries Advanced Engineering

& Sciences Division

Development of Eye-Safe Lidar Technologyfor Aerosol and Cloud Measurements

Scott HigdonITT Advanced Engineering & Sciences Division

Lasers and Electromagnetics DepartmentAlbuquerque, NM

USEPA ORS WorkshopJuly 30, 2002

Scott HigdonPh: (505)[email protected]


& Sciences Division

Presentation Outline

• Lidar Overview

• Eye-Safe Lidar for Atmospheric Aerosols

• Differential Scattering Lidar for Bio-Agent Detection

• Laser Interrogation of Surface Agents (LISA)

Radar = Radio Detection and Ranging

AmplifierA-D Converter

orPhoton Counter

Computer

Data Storage

Lidar = Light Detection and Ranging

Aerosols

Molecules


& Sciences Division


& Sciences Division

ITT Lidar Measurement Techniques

ElasticBackscatter

LaserRaman

Scattering

DifferentialAbsorption

Lidar(DIAL)

1.0x10 6

0.8

0.6

0.4

0.2

0.030002500200015001000500

Raman shift (cm -1)

DIMP

1-50 km

1-50 m

1-15 kmRange Resolved

orPath IntegratedMeasurements


& Sciences Division

ITT Lidar Technology Program

Chemical and Biological Agent Detection Atmospheric & EnvironmentalLidar Sensors

Ground-BasedDifferentialAbsorption

Lidar

The ITT lidar team develops and fields operational lidarsensors for chem/bio warfare agent detection and for

atmospheric and environmental measurements.

Standoff Detection of SurfaceDeposited Chemical Weapon Agents

Standoff Detection ofBiological Weapon Agents

Airborne Detection of VaporPhase Chemical Weapon Agents

AirborneDifferentialAbsorption

Lidar

Raman Lidar

DifferentialScattering


& Sciences Division

Eye-Safe Lidar forAtmospheric Aerosols


& Sciences Division

AEROSOLPARTICLES

FOSSIL FUEL COMBUSTION

SO2

GROUND BASED LIDARMEASUREMENTSNATURAL SOURCES

TRANSPORTMIXINGREACTION

EFFECT ON EARTH’STEMPERATURE

Natural Sources: windblown dust, sea spray, volcanoes, gas-to-particle conversion; etc.

Anthropogenic Sources: fuel combustion, material processing (eg.crushing, grinding),intentional release of biological agent aerosols

Atmospheric Aerosol Sources


& Sciences Division

0 1000 2000 3000 4000 5000 6000 7000

2000

1000

0Range (meters)

Barcelona

26jul323d; 17:42 hrs, 35 deg

Altitude(meters)

Mix Layer

StableResidualLayers

0 1000 2000 3000 4000 5000 6000 7000 8000Range (meters)

3500

3000

2500

2000

1500

1000

500

0

r2 Corrected Data

8.0 14 20 26 32

Mexico CityAltitude(meters) PBL and

Mix LayerHeight

Entrainment Zone

ConvectionCell

IndustrialPlumes

Highway

Examples of Aerosol Lidar Measurements


& Sciences Division

Hampton University Eye-safe Aerosol System

Center for Lidar and Atmospheric Sciences Students


& Sciences Division

For the same operating parameters, a 1.5 m laser is~105 times safer than 1.064 m laser~200 times safer than 0.355 m laser

0 1 2 3 4 51 10 3

0.01

0.1

1

10

100

1 103

1 104M

axim

um E

yesa

fe E

nerg

y (m

J)

Q1 a( )

Q2 a( )

Q3 a( )

a

cm

Max Eyesafe Energy vs. Beam Diameter, a, at Laser Output

Beam diameter at laser output aperture

1064 nm

355 nm

1500 nm

Eye Safety Considerations


& Sciences Division

Eye-Safe Near-IR Transmitter

Nd:YAG Output(14 Hz)

320 mJ

After Isolator 290 mJ

OPO Output 82 mJ

OPO Energy Stability(/mean)

2%

Nd:YAG Divergence(Full Angle)M2

0.43 x 0.80 mrad

3 x 6OPO Divergence(Full Angle)M2

4.8 x 5.8 mrad

12 x 23

• Operation at 20 Hz yielded unusually high divergence for Nd:YAG and OPO.

• Nd:YAG reconfigured for lower PRF operation.

• Present tests underway to fully characterize effects of pump divergence and PRF


& Sciences Division

Receiver Optics

Lightweight Telescope Mirror

Transceiver Housing

Receiver Optical Design

Lens/Filter Subassembly

Lens 1

InGaAsAPD

Filter

Lens 2

Lens 3

10” CatadioptricTelescope


& Sciences Division

CLASS Lidar Team at Hampton University

Center for Lidar and Atmospheric Sciences Students


& Sciences Division

Atmospheric and Hard Target Return Signals

Near Field Return Far Field Return

(Sandia Mountains)


& Sciences Division

(A) (B)

Scanning Lidar Backscatter Signal After Background Subtraction and Range Correction(A) Jan-02-2002, Hampton, USA, azimuthal scanning of a cloud with 70 degrees elevation angle,

(B) Jan-02-2002, Hampton, USA, elevation scanning of a cloud

Cloud Measurements


& Sciences Division

Micro-Pulse Lidar (MPL) Technology

• Pioneered by NASA Goddard Space Flight Center

• Uses high rep rate (1-10 kHz)/low pulse energy (10-50 J)at 532 nm to achieve eye-safe output at the aperture

• Low-cost, reliable, autonomous operation

• Requires long time averages and not conducive to scanning

• NASA GSFC is developing a network of these lidars (MPL-Net)at various locations around the world


& Sciences Division

Remote Detection ofBio-Agent Aerosols

DifferentialScattering

Lidar


& Sciences Division

Transmitter for Bio-Agent Detection Using Differential Scattering Lidar

m OPO

Nd: YAG

3.4-3.7

OC HRType III

KTA

>100 mJ1.5 m

1.5 m OPO

OC HRType III

KTA

>50 mJ3.4 - 3.7

375 mJ 1064 nm20 HZ rep-rate

350 mJ1064 nm

Isolator

PockelsCell

Polarizer350 mJ1064 nm

ITT is developing a DISC lidar system using this transmitter forthe ARMY SBCCOM in collaboration with Physical Sciences, Inc.


& Sciences Division

Dual Transmitter

Receiver Aft Optics

PrimaryMirror

TransmitterSection

Receiver AftOptics Section

14”

42”

26”

Transceiver Module

Bio-Agent Lidar System Transceiver Design


& Sciences Division

Bio-Agent Lidar System


& Sciences Division

Laser Interrogation ofSurface Agents (LISA)

NBCRS - Fox


& Sciences Division

SiliconSampleWheel

SiliconSampleWheel

MassSpectrometer

Probe

• Requires sample collection using a surface-contact mechanical device

• Requires a dedicated device operator• Slow response and very small sampling area• Operational and supply logistics issues

Current Approach for Ground Contamination NBCRS Fox Vehicle Sample Wheel Device


& Sciences Division

Measurement Methodology:Raman Scattering

• Vibrational Raman Scattering occurswhen light interacts with a molecule

• A small amount of wavelength-shiftedlight is scattered

• Amount/intensity depends on the molecule’s size, shape, and strength(vibrational modes of the molecule)

• Creates a distinct “spectral fingerprint”

Selectivity is the hallmark of Raman spectroscopy

Selectivity is the hallmark of Raman spectroscopy

Laser Light

Molecule

RayleighScattering

RamanScattering

VibrationalModes

-0.025

0.075

0.175

0.275

0.375

0.475

0.575

0.675

0.775

3500 3000 2500 2000 1500 1000 500 0

Raman Shift (cm-1)

p-xylene

o-xylene

m-xylene


& Sciences Division

LISA Concept

Dispersive Optics

Telescope

Illumination

Molecules of Chemical Agent

Chemical Fingerprint

Molecules of Chemical Agent

Scattering

Raman Signal

Photo-Detector

DatabaseAlgorithms

Analysis

id

Detection &Identification

Fiber Bundle

Laser Transmitter LISALaser Interrogationof Surface Agents


& Sciences Division

BNL Mini-Raman Lidar System (MRLS) uses laboratory off-the-shelf components

1.0x106

0.8

0.6

0.4

0.2

0.0

Coun

ts

30002500200015001000500Raman shift (cm

-1)

1.2x106

1.0

0.8

0.6

0.4

0.2

0.0

Coun

ts

30002500200015001000500Raman shift (cm

-1)1.0x10

6

0.8

0.6

0.4

0.2

0.0

Coun

ts

30002500200015001000500Raman shift (cm

-1)

TMP

DMMP

DIMP

MRLS measured spectral signatures& distinguished related compounds

MRLS Sensitivity 2 g/m2 (single shot at 1 m)Military requirement 0.5 g/m2

LISA Proof-of-Concept: MRLS


& Sciences Division

ITT LISA-Recon System


& Sciences Division

Preparation for Field Measurements

HMMWV Test Vehicle Sensor Module & Vibration Mount


& Sciences Division

Single Shot Measurements & Identification

10002000300040005000Raman shift cm-1

1

2

3

4

5

6x104

Cou

nts

(Bg

Cor

rect

ed)

10002000300040005000Raman shift cm-1

3.1

3.3

3.5

x104

Cou

nts

01000200030004000Raman shift cm-1

2

4

6

x104

Co

un

ts (

Bg

Co

rrec

ted

)

Teflon sheet

(single shot)

Atmospheric O2 and N2

Superimposed on featureless sand

(100 shot average)

Cyclohexane

(single shot)

•Cyclohexane and Teflon are materials used by BNL to characterize their system.

•We can use them to compare our system performance to the baseline BNL system

•The O2 & N2 signature forms the kernel of an instrument confidence check


& Sciences Division

Initial Single Shot Measurements ofa Chemical Agent Simulant

•Red curve: single shot measurement of MeS at 0.25 g/m2 with 9.1 mJ laser pulse.

•Spectra for the atmosphere, water and the quartz vial (2 mm path length) are removed.

•SNR of the MeS peak near 1610 cm-1 is approximately 15.

•Blue curve: same but 100 shot average, 15 mJ pulse.

0 500 1000 1500 2000 2500 30000

2000

4000

6000

8000

Raman shift (cm-1)

Ram

an re

turn

(dig

itize

r cou

nts)


& Sciences Division

ESTCP Project

Application of (LISA) Technology to DoD EnvironmentalSite Characterization Requirements

Develop innovative, rapid screening technologies to detect and delineate land areas with soils containing contaminants associated with live fire training activities including energetic compounds (RDX, HMX, TNT, DNT), propellants, and their byproducts.

Dr. Steve Christesen – Army ECBCMr. Scott Higdon – ITT IndustriesDr. Arthur Sedlacek – BNLMs. Tamera Rush - AECDr. Daniel Powell – EPA (Advisor)


& Sciences Division

UV Detection of Explosives

TNT data showing the advantagesof UV (< 253 nm) excitation

TNT data showing the advantagesof UV (< 253 nm) excitation

Raman spectra of TNT and 4NT can bedistinguished by the strong peak at 860 cm-1

Raman spectra of TNT and 4NT can bedistinguished by the strong peak at 860 cm-1

UV excitation provides:1. Reduced fluorescence2. Potential for simplified spectra and

Raman scattering enhancement (103

to 106) from resonance Raman effect

Data from Lacey, et al., Characterizationand Identification of Contraband UsingUV Resonant Raman Spectroscopy, SPIEVol. 2937, 100 – 104, 1997.


& Sciences Division

Mission Applications• Reconnaissance vehicles• Cargo inspection• Shipboard sensor• Homeland Defense• Environmental cleanup• Planetary exploration

Potential Users• Army SBCCOM• FAA/TSA• Navy• Civil Support Teams• EPA• NASA

LISA technology provides a unique solution to the very challengingproblem of detecting and identifying surface-deposited chemicals

LISA Future Missions

LISALaser Interrogation ofSurface Agents

Advanced Engineering& Sciences

development of eye-safe lidar technology for aerosol and ... · development of eye-safe lidar...

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