Purdue University Current Research Topics in Optical ... · Current Research Topics in Optical Sensors and Laser Diagnostics Current Research Topics in Optical Sensors and Laser Diagnostics

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Purdue University

School of Mechanical Engineering

Current Research Topics in Optical Sensors and Laser Diagnostics

Current Research Topics in Optical Sensors and Laser Diagnostics

Prof. Robert P. LuchtSchool of Mechanical Engineering ,Purdue University, W.

Lafayette, IN

February 16, 2006

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• Development of commercialized tunable lasers about 25 years ago has led to routine use of laser techniques for probing flames and plasmas.

• The techniques that we use in our experiments are introduced in the next few slides. After these slides ongoing projects in my laboratory are discussed.

Survey of Spectroscopic Laser Diagnostic Techniques

Survey of Spectroscopic Laser Diagnostic Techniques

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Single-FrequencyLaser

Iodine Cell

CCD Array

ExcitedElectronic Level

Virtual Level

Beam Dump

Flame or NonreactingFlow

GroundElectronic Level

Rayleigh Scattering – Filtered Rayleigh Scattering

Rayleigh Scattering – Filtered Rayleigh Scattering

Strong signal, spatially resolved, not species-specific

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TunableLaser System

Photomultiplieror Photodiode

Excited Electronic Or Vibrational Level

Flame or Plasma

Ground Electronic Or Vibrational Level Laser Frequency

TransLaser

Intensity

Tunable Laser AbsorptionTunable Laser Absorption

Species-specific, quantitative, path-averaged

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Spontaneous Raman ScatteringSpontaneous Raman Scattering

Fixed FrequencyLaser

Spectrometer

Photomultiplieror CCD ArrayExcited

Electronic Level

v+1, J

v, J

Virtual Level

Beam Dump

Flame or Plasma

Species-specific, spatially resolved, quantitative, weak signal

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Laser-Induced Fluorescence (LIF)Laser-Induced Fluorescence (LIF)

Q-switched, 10-nsecpulse, 500 mJ

Nd:YAG Laser Dye Laser

532 nm545 nm

to 800 nm

Frequency-DoublingCrystal

272 nmto 400 nm

Spectrometer orFilter

Photomultiplier orDigital Camera

Computer

Beam Dump orPower Meter

Lens Focusing Lens

Collecting Lens

Flame

Excited Electronic Level

GroundElectronic Level

NonradiativeDecay

Species-selective, spatially resolved, strong signals, complicated by nonradiative decay, not all species fluoresce

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TunableLaser System

Photomultiplieror Photodiode

Excited Zeeman States

Flame or Plasma

Ground Zeeman States

Laser Frequency

TransLaser

Intensity

BeamDump

λ/4 BeamDump

M=-1 M=0 M=+1

M=-1 M=0 M=+1

Pump RCPProbe RCPProbe LCP

Laser-Induced Polarization Spectroscopy (LIPS)

Laser-Induced Polarization Spectroscopy (LIPS)

Species-selective, spatially resolved, wide range of species, coherent signal,complicated physics

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• Conventional “Single-Pump” CARS

• Noninvasive• Coherent Laser-Like

Signal• Spatially and

Temporally Resolved• Excellent Gas

Temperature Data (especially at higher temperatures)

ωpump

ωStokes

ωCARS

ωV

ωpump

ωpump

ωStokes

ωCARS

ωV

ωpump

ωStokes

ωPump1

ωPump1

ωCARS

Coherent Anti-Stokes Raman Scattering (CARS)

Coherent Anti-Stokes Raman Scattering (CARS)

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Current ProjectsCurrent Projects• Laser-Induced Polarization Spectroscopy• Diode-Lased-Based Sensors in the

Ultraviolet • Injection-Seeded Optical Parametric

Generator Systems• Electronic-Resonance-Enhanced Coherent

Anti-Stokes Raman Scattering (ERE CARS)• Femtosecond CARS• Hypersonic Flow Diagnostics• Mixing in Model Rocket Chambers

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Laser-Induced Polarization SpectroscopyLaser-Induced Polarization Spectroscopy• Funding source: US Dept of Energy, Office of

Basic Energy Sciences. One RA position is open.

• This project is a combined experimental and theoretical investigation of the potential of LIPS for concentration measurements for radical species.

LIPS measurements of atomic hydrogen

Low-pressure diamond-film CVD flame.

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Diode-Lased-Based Sensors in the UltravioletDiode-Lased-Based Sensors in the Ultraviolet• Funding source: US Dept of Energy, National

Energy Technology Lab. One RA position is open.

• We have developed advanced diode laser sensors for measuring NO, OH, Hg among other species.

NO Sensor in Gas Turbine Test CellOH Sensor in Operation

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Injection-Seeded Optical Parametric Generator Systems

Injection-Seeded Optical Parametric Generator Systems

• Funding source: US Dept of Energy, Office of Basic Energy Sciences, Air Force Office of Scientific Research.

• We are developing a new pulsed, tunable laser source.OPG in Operation.

High-Resolution NO Spectra from OPG.

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Electronic-Resonance-Enhanced Coherent Anti-Stokes Raman Scattering (ERE CARS)Electronic-Resonance-Enhanced Coherent Anti-Stokes Raman Scattering (ERE CARS)

• Funding source: US Dept of Energy, Office of Basic Energy Sciences, Air Force Office of Scientific Research, DARPA.

• We are developing a ERE CARS techniques for measurement of NO and C2H2 in high-pressure flames, and for detection of anthrax spores.

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Femtosecond CARSFemtosecond CARS

• Funding source: National Science Foundation.

• This project is an investigation of the potential of femtosecond CARS for measurements in turbulent flames at data rates in excess of 1 kHz.

Stokes Beam -ω2780 nm, 70 fsec

Pump Beam - ω1660 nm, 70 fsec

Probe Beam -ω3660 nm, 70 fsec

Delay Linefor Probe

CARS Signal Beam -ω4Turbulent Flame

or Gas Cell

Chirped Probe Pulse2-3 psec

Raman Coherence

t

DispersiveRod

60 cm SF11

To Spectrometerand EMCCD

Fsec CARS Optical System.Fsec CARS Pulse Diagram.

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Hypersonic Flow DiagnosticsHypersonic Flow Diagnostics

• Funding source: Air Force Office of Scientific Research. One RA position is open.

• We are developing new laser diagnostic techniques for probing hypersonic shear layers. A hypersonic tunnel is under construction at Texas A&M Univ.

High-Resolution OPG for NO LIF.

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Theory

Experiment

2 X OPO Signal Frequency - 1,326,922.5 (GHz)

LIF

Sig

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UV

Inte

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(arb

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2 X OPO Signal Frequency - 1,326,922.5 (GHz)

LIF

Sig

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Inte

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(arb

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ts) (b)

High-Res NO LIF imaging will be used to measure p, T, V.

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Mixing in Model Rocket ChambersMixing in Model Rocket Chambers

• Funding source: NASA. One RA position is open.

• We are performing NO PLIF measurements in a simulated rocket injector chamber for comparison with CFD calculations by Prof. Merkle’s group.

Rocket Injector SimulatorPLIF Image of Mixing of Nitrogen from Central “Oxidizer” Slot with Helium from Side “Fuel” Slots

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Questions? Comments? Interest in RA Position?

Questions? Comments? Interest in RA Position?

Please contact Prof. Lucht at 765-494-5623 (office), 765-586-5823 (cell), or at [email protected].