Laser-induced incandescence (LII) is a non-intrusive method of measuring soot particle volume fraction and primary particle sizes in flames. Not only restricted to flames, this technique is recently used for characterization of car engine exhaust, atmospheric black carbon and synthetic nanoparticles. These new applications require the same basic signal processing, but at the same time individual databases for material (soot or non-soot) and gas compositions as well as individual heat transfer models for the determination of particle sizes. LIISim is a framework for basic signal processing and analysis of experimental LII data to help researches across the world to compare their experimental data.

LIISim is a project of
University of Duisburg-Essen Institute for Combustion and Gas Dynamics - Reactive Fluids

The old web interface (by Max Hofmann) can be found here.


LIISim is designed to provide transparent and flexible tools, which allow individual setting of processing parameters, visualization of intermediate processing steps, and comparison of multiple experimental data sets.

Main features:

  • Modular choice of user-defined material properties (soot, silicon, germanium,…)
  • Comparison of experimental data with different pre-implemented heat-transfer models
  • Various analysis tools help visualizing dependencies between experimental data sets (plots, parameter comparison, statistical information)
  • Easy-to-use import (TXT/CSV) and export (TXT/CSV/MATLAB) functionalities
  • Copy/paste of signals and analysis results into spreadsheet software (MATLAB, Excel, Origin,…)
  • Software architecture allows processing and comparison of large data sets (> 4 GB)



The modular signal processing toolbox allows processing of raw signals, absolute signals and temperature traces. Processing steps can be individually set and arranged. Intermediate processing results can be visualized and analyzed with various plot tools.

AnalysisTool: Temperature Fit

Visualization of spectral temperature fitting using Planck’s law. Temperature traces that are calculated in the SignalProcessing module can be analyzed and all fitting iterations can be visualized.

AnalysisTool: Parameter Analysis

Experimental data can be systematically compared for various parameters (i.e., laser fluence, LII peak temperature, PMT gain voltage,…).


Select from a variety of heat transfer models and databases for simulation of LII signal traces and comparison with experimental data.


Document Version File
User manual 0.0.1 (19.01.2018) on request
Developer’s guide 0.0.0 not yet available


We are currently in BETA development phase, release is scheduled for Spring 2018. Please feel free to request a BETA release for testing purposes.

Pre-compiled binaries are available for Windows 7/8/10 platforms (32bit and 64bit).

Platform Version File
Windows 7/8/10 (x64) 3.0.5 (BETA) Request BETA version
Windows 7/8/10 (x32) 3.0.5 (BETA) not yet available

Source code

The latest source code can be obtained from GitHub. Please see the developer’s guide for further instructions on compiling the source code and required libraries.


LIISim is a project of
University of Duisburg-Essen Institute for Combustion and Gas Dynamics - Reactive Fluids

LIISim was so far known as console application (LIISim 1.5) and web interface (, developed by Max Hofmann between 2001 and 2007. The console application was written in C and the web interface was based on Perl. Modeling settings and file names for experimental data could be defined in DAT files and after execution of the console application, DAT output files containing the modeling results are created.
Later the console application was extended by a C++ based graphical user interface (GUI) by Tobias Terheiden and Martin Leschowski, which allowed the visualization of the modeling results from the DAT files (LIISim Desktop 1.02 and LIISim Console 2.14). While the console application was distributed among the community, the desktop version was not published and was only internally used.
In 2013 the development of LIISim 3 a new framework with object-oriented structure based on C++ was started by Raphael Mansmann designed for the application on individual material systems (soot and non-soot) with a modular implementation of signal processing steps and choice of heat-transfer models.

The old web interface (by Max Hofmann) can be found here.

Raphael Mansmann
Tobias Terheiden
Philip Schmidt


LIISim is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

LIISim is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.