262 - Fire Fundamentals pt. 22 - Optical diagnostics in fire with Elizabeth Weckman

In todays episode of fire fundamentals we talk with Professor Elizabeth Weckman from University of Waterloo about advanced optical diagnostics that let fire researchers read temperature, chemistry, soot, and velocity from light without relying only on probes. We break down what cameras, infrared imaging, spectroscopy, lasers, and PIV can reveal, plus the calibration and interpretation pitfalls that can quietly ruin your data.

Things covered in this episode:
• why optical diagnostics are “non-intrusive” in practice and where they still perturb the flow
• limits of probe-based measurements in fire including spatial resolution and radiation errors
• using basic photography and video as a first diagnostic and as a planning tool
• calibration habits for cameras and why cheap, robust cameras are often a better choice for a fire laboratory
• infrared thermography for surface heating plus emissivity problems and practical coatings
• Schlieren imaging for density and temperature gradients and what it can and cannot imply
• point vs planar vs line-of-sight vs tomographic measurements and how “smearing” happens
• FTIR and absorption spectroscopy for pyrolysis gases, emissions, and toxic species
• chemiluminescence and laser-induced fluorescence to mark combustion and flame fronts
• Raman and CARS for temperature and concentration and why they are technically demanding
• soot diagnostics from light extinction to laser-induced incandescence and aging effects
• PIV basics, seeding challenges in fire, and what velocity fields unlock for validation

The episode is best enjoyed along Beth's paper from the IAFSS: Unravelling the mysteries of fire

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