Welcome to LIISim3, a modular signal processing toolbox for time-resolved laser-induced incandescence measurements written in C++ with the Qt-Framework.

LIISim is a project of

Institute for Combustion and Gas Dynamics - Reactive Fluids University of Duisburg-Essen


Raphael Mansmann
Tobias Terheiden
Philip Schmidt


The software is described in the following paper:

R. Mansmann, T. Terheiden, P. Schmidt, J. Menser, T. Dreier, T. Endres and C. Schulz: "LIISim: a modular signal processing toolbox for laser-induced incandescence measurements" Appl. Phys. B 124(4), 69 (2018). DOI 10.1007/s00340-018-6934-9


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.


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)


Signal Processing

Signal Processing
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.

Analysis Tool: Temperature Fit

Analysis Tool: 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.

Analysis Tool: Parameter Analysis

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

Fit Creator

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

Download now


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.