Current Research Topics in Optical Sensors and Laser Diagnostics Prof. Robert P. Lucht,Purdue University, W. Lafayette, IN February 16, 2006 Patterned Border Template 1
Survey of Spectroscopic Laser Diagnostic Techniques 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. Patterned Border Template 2
Rayleigh Scattering Filtered Rayleigh Scattering Flame or Nonreacting Flow Single-Frequency Laser Beam Dump Excited Electronic Level Iodine Cell Virtual Level CCD Array Ground Electronic Level Patterned Border Template 3 Strong signal, spatially resolved, not species-specific
Tunable Laser Absorption Flame or Plasma Tunable Laser System Excited Electronic Or Vibrational Level Trans Laser Intensity Photomultiplier or Photodiode Ground Electronic Or Vibrational Level Laser Frequency Patterned Border Template 4 Species-specific, quantitative, path-averaged
Spontaneous Raman Scattering Flame or Plasma Fixed Frequency Laser Beam Dump Excited Electronic Level Photomultiplier or CCD Array Virtual Level Spectrometer v+1, J v, J Species-specific, spatially resolved, quantitative, weak signal Patterned Border Template 5
Laser-Induced Fluorescence (LIF) Excited Electronic Level Nonradiative Decay Nd:YAG Laser Q-switched, 10-nsec pulse, 500 mj 532 nm Dye Laser Frequency-Doubling Crystal 545 nm to 800 nm 272 nm to 400 nm Ground Electronic Level Lens Flame Focusing Lens Beam Dump or Power Meter Collecting Lens Photomultiplier or Digital Camera Spectrometer or Filter Computer Species-selective, spatially Patterned resolved, Border Template strong 6signals, complicated by nonradiative decay, not all species fluoresce
Laser-Induced Polarization Spectroscopy (LIPS) Flame or Plasma Beam Dump Tunable Laser System M=-1 M=0 M=+1 λ/4 Excited Zeeman States Trans Laser Intensity Beam Dump Photomultiplier or Photodiode M=-1 M=0 M=+1 Pump RCP Probe RCP Probe LCP Ground Zeeman States Laser Frequency Species-selective, spatially Patterned Border resolved, Template wide 7range of species, coherent signal, complicated physics
Coherent Anti-Stokes Raman Scattering (CARS) Conventional Single-Pump CARS Noninvasive Coherent Laser-Like Signal Spatially and Temporally Resolved Excellent Gas Temperature Data (especially at higher temperatures) ω pump ω Stokes ω Stokes ω V ω pump Patterned Border Template 8 ω Pump1 ω Pump1 ω CARS ω CARS
Current 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 Patterned Border Template 9 Mixing in Model Rocket Chambers
Laser-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. Low-pressure diamond-film CVD flame. LIPS measurements of atomic hydrogen Patterned Border Template 10
Diode-Lased-Based Sensors in 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. OH Sensor in Operation NO Sensor in Gas Turbine Test Cell Patterned Border Template 11
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. High-Resolution NO Spectra from OPG. OPG in Operation. Patterned Border Template 12
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 C 2 H 2 in high-pressure flames, and for detection of anthrax spores. Patterned Border Template 13
Femtosecond 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. Probe Beam - ω 3 660 nm, 70 fsec Stokes Beam - ω 2 780 nm, 70 fsec Fsec CARS Pulse Diagram. Dispersive Rod 60 cm SF11 Chirped Probe Pulse 2-3 psec Delay Line for Probe Fsec CARS Optical System. Pump Beam - ω 1 660 nm, 70 fsec Raman Coherence CARS Signal Beam - ω 4 Turbulent Flame or Gas Cell To Spectrometer and EMCCD Patterned Border Template 14 t
Hypersonic 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. High-Res NO LIF imaging will be used to measure p, T, V. LIF Signal / UV Intensity (arb. units) 0.70 0.60 0.50 0.40 0.30 0.20 Patterned Border Template 15 0.10 (b) Theory Experiment 0.00 0.0 5.0 10.0 15.0 20.0 25.0 2 X OPO Signal Frequency - 1,326,922.5 (GHz)
Mixing in 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 Simulator PLIF Image of Mixing of Nitrogen from Central Oxidizer Slot with Helium from Side Fuel Slots Patterned Border Template 16
Questions? Comments? Interest in RA Position? Please contact Prof. Lucht at 765-494-5623 (office), 765-586-5823 (cell), or at Lucht@purdue.edu. Patterned Border Template 17