The leading supplier of cutting edge technology

LII: Laser Induced Incandescence

Description: A diagnostic technique used to study exhuasts, whereby the soot particles act as a blackbody emission source

Recommended Product: Big Sky Ultra

Principle

Study of the blackbody emission

LII: Basics

  • Requires high intensity laser (>50-100 MW/cm²)
  • Applicable on soot or metallic particles
  • After a calibration (typ. by CRDS or extinction method), LII makes possible the characterization of :
    1. the volume fraction of particles in a 3D sample
    2. The size of the particles (analysis of the temporal profile of the LII signal)

LII: Limitations of the method

  • High soot loadings/long optical path lengths can lead to attenuation of laser across flow field or attenuation of incandescence between measurement volume and detector
  • Requires detector with short temporal gating capability (<50 ns for lasers with 5-10 ns pulse durations)
  • Detection wavelength must be chosen to minimize broadband fluorescence interferences (for example from hydrocarbon molecules)
    1. Typ. 1064nm (or 532nm)

Fields of applications

  • « cold particles »
    1. Automotive, aeronautics, industrial exhausts…
  • « hot particles »
    1. Flames, combustion chambers…