Colloquium: Esther Baumann - Seeing through flames with Coherent Laser Ranging at meters of distance

Title: Seeing through flames with Coherent Laser Ranging at meters of distance

Abstract(s):
Non-contact surface mapping at a distance is of interest to diverse applications including industrial metrology, manufacturing, determination of structural deformation in the case of fire and forensics. Frequency modulated continuous wave (FMCW) laser detection and ranging (LADAR) is a promising approach since it offers shot-noise limited precision/accuracy, high resolution and high sensitivity.

Here, I will discuss how calibrated 3D images can be obtained at meters of stand-off distances with mm ranging precision as calibrated with a frequency comb, limited only by fundamental speckle noise. Further I will show how such an imaging method might be applied to measure deforming objects in the case of fire. To date, no ranging technology has been demonstrated that excels at both seeing through flames and offering high precision at larger stand-off distances where photon efficiency is crucial. Ideally, such a system should be non-contact and able to measure millimeters to meter size targets behind flames with sub-mm precision and sufficiently high update rates. I will show 3D images obtained with coherent laser ranging of both static and deforming objects behind methane and acetylene flames. A ranging precision of 30 µm through an acetylene flame at a 2-meter stand-off is achieved.

Speaker Bio(s):
Esther Baumann is a senior research scientist at the National Institute of Standards and Technology (NIST) in Boulder, CO. Before joining NIST in 2008, she obtained a PhD in experimental physics at the University of Neuchatel in Switzerland working on intersubband transitions in GaN/AlN semiconductor quantum wells. At NIST, Esther Baumann designs and builds fiber frequency combs and explores novel frequency comb applications. In particular, she has been working on high-precision gas phase molecular dual-comb spectroscopy including green-house gas monitoring and was involved in comb-based time and frequency transfer. Esther Baumann’s work at NIST also includes precision coherent laser ranging based on frequency modulated continuous wave (FMCW) laser detection and ranging. She has been studying fundamental limits of coherent laser ranging when imaging diffusely scattering surfaces and the applicability of FMCW for ranging through turbulent media such as flames.