# Presentation: 689289

## Development of Eye-Safe Lidar Technology

**for Aerosol and Cloud Measurements **** **** **
**Scott Higdon**
**ITT Advanced Engineering & Sciences Division**
**Lasers and Electromagnetics Department**
**Albuquerque, NM**
**USEPA ORS Workshop**
**July 30, 2002**

**Scott Higdon**
**Ph:  (505)889-7006**
**scott.higdon@itt.com**

## 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

- filter

- Receiver

- Collected
- Light

- Laser

- detector

- Amplifier

- A-D Converter
- or
- Photon Counter

- Computer

- Data Storage

**Lidar = Light Detection and Ranging**

**Aerosols**

**Molecules**

**Advanced Engineering**
**& Sciences Division**

## ITT Lidar Measurement Techniques

**Elastic**
**Backscatter**

**Laser**
**Raman**
**Scattering**

**Differential**
**Absorption**
**Lidar**
**(DIAL)**

**1-50 km**

**1-50 m**

**1-15 km**

**Range Resolved**
**or**
**Path Integrated**
**Measurements**

## ITT Lidar Technology Program

**Chemical and Biological Agent Detection**

**Atmospheric & Environmental**
**Lidar Sensors**

**Ground-Based**
**Differential**
**Absorption**
**Lidar**

**The ITT lidar team develops and fields operational lidar**
**sensors for chem/bio warfare agent detection and for**
**atmospheric and environmental measurements.    **

## Eye-Safe Lidar for

**Eye-Safe Lidar for**
**Atmospheric Aerosols**

## Atmospheric Aerosol Sources

**AEROSOL**
**PARTICLES**

- FOSSIL FUEL
- COMBUSTION

- SO2

- GROUND BASED LIDARMEASUREMENTS

- NATURAL SOURCES

- TRANSPORTMIXINGREACTION

- EFFECT ON EARTH’S
-  TEMPERATURE

**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**

## Examples of Aerosol Lidar Measurements

**Examples of Aerosol Lidar Measurements**

**Notes:**

Back up only

## Hampton University Eye-safe Aerosol System

*C**enter for** L**idar and *
*A**tmospheric **S**ciences **S**tudents*

## Eye Safety Considerations

** **~105 times safer than 1.064 m  laser
-  ~200 times safer than 0.355 m  laser

- 1064 nm

- 355 nm

- 1500 nm

**Eye Safety Considerations**

## Eye-Safe Near-IR Transmitter

**Eye-Safe Near-IR Transmitter**

** ****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 **

## Receiver Optics

**Lightweight Telescope Mirror**

**Transceiver Housing**

**Receiver Optical Design**

**Lens/Filter Subassembly**

**Lens 1**

**InGaAs**
**APD**

**Filter**

**Lens 2**

**Lens 3**

**10” Catadioptric**
**Telescope**

## CLASS Lidar Team at Hampton University

*C**enter for** L**idar and *
*A**tmospheric **S**ciences **S**tudents*

## Atmospheric and Hard Target Return Signals

- Near Field Return

- Far Field Return
- (Sandia Mountains)

## Cloud Measurements

- 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**

## 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**

## Remote Detection of

**Bio-Agent Aerosols**

**Differential**
**Scattering**
**Lidar**

## Transmitter for Bio-Agent Detection Using Differential Scattering Lidar

**m OPO**

- Nd

- : YAG

**3.4-3.7**

****

**OC**

**HR**

**Type III**

**   ****KTA**

**>100 mJ**
**1.5 ********m**

**1.5**

****

**m OPO**

**OC**

**HR**

**Type III**

**   ****KTA**

**>50 mJ**
**3.4 - 3.7******** **

- 375 mJ 1064 nm
- 20 HZ rep-rate

- 350 mJ
- 1064 nm

- Isolator

- Pockels
- Cell

- Polarizer

- 350 mJ
- 1064 nm

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

## Bio-Agent Lidar System Transceiver Design

**Bio-Agent Lidar System Transceiver Design**

## Bio-Agent Lidar System

**Bio-Agent Lidar System**

## Laser Interrogation of

**Surface Agents (LISA)**

**NBCRS - Fox**

## Current Approach for Ground Contamination 

**Silicon**
**Sample**
**Wheel**

**Silicon**
**Sample**
**Wheel**

**Mass**
**Spectrometer**
**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**

## Measurement Methodology:Raman Scattering

** ****Vibrational Raman Scattering**** occurs**
**  ****when light interacts with a molecule**
** ****A small amount of wavelength-shifted**
**  ****light 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**** **

**Laser Light**

**Molecule**

**Rayleigh**
**Scattering**

- Raman
- Scattering

- Vibrational
- Modes

## LISA Concept

## LISA Proof-of-Concept:  MRLS

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

**MRLS measured spectral signatures**
**& distinguished related compounds**

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

**LISA Proof-of-Concept:  MRLS**

## ITT LISA-Recon System

**ITT LISA-Recon System**

## Preparation for Field Measurements

**HMMWV Test Vehicle**

**Sensor Module & Vibration Mount**

## Single Shot Measurements & Identification 

- 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

## Initial Single Shot Measurements ofa 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.

## ESTCP Project

**Application of (LISA) Technology to DoD Environmental**
**Site 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 ECBC**
**Mr. Scott Higdon – ITT Industries**
**Dr. Arthur Sedlacek – BNL**
**Ms. Tamera Rush - AEC**
**Dr. Daniel Powell – EPA (Advisor)**

## UV Detection of Explosives

**TNT data showing the advantages**
**of UV (< 253 nm) excitation**** **

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

**UV excitation provides:**
**1. Reduced fluorescence**
**2. Potential for simplified spectra and**
**    ****Raman scattering enhancement (10****3**
**    ****to 10****6****) from resonance Raman effect **

***Data from Lacey, et al., Characterization***
***and Identification of Contraband Using***
***UV Resonant Raman Spectroscopy, SPIE***
***Vol. 2937, 100 – 104, 1997.***

## LISA Future Missions

** **

**   **_**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 challenging***
***problem of detecting and identifying surface-deposited chemicals***

**LISA Future Missions**