Photon Density Wave Spectroscopy
Method of Measurement
Detection and analysis of PDWs in terms of amplitude and phase with respect to modulation frequency and source-detector distance allow for the precise determination of fundamental optical properties of the material under investigation, namely the absorption and reduced scatttering coefficients. Whereas the first provides access to chemical concentrations, the latter allows for the determination of concentrations or particle and droplet sizes of the dispersed phase without any dilution or calibration.
The analysis is based on radiation transport theory, Mie theorie and several approaches concerning dependent scattering. Don't worry - we know about the details!
- Intrinsically safe electronics-free, fibre-optics only probe for installations in critical environments (e.g. ATEX)
- Laser power < 15 mW
- Typical probe materials: stainless steel, glass, PTFE. Customer specific development possible
- Probe diameter depends on application. Typical range is 15 - 25 mm
- Time resolution: approx. 2 per minute
- Size range: approx. 50 nm - 500 µm (diameter)
What systems can be analyzed?
See our list of scientific contributions for more theoretical background and examples of investigated materials and processes (Literature).
Calibration Standards: Limitations of turbidity process probes and formazine as their calibration standard by M. Münzberg, R. Hass, N. Duc Khanh, O. Reich (open access available)
PNIPAM transition: Process analytical approaches for the coil-to-globule transition of poly(N-isopropylacrylamide) in a concentrated aqueous suspension by P. Werner, M. Münzberg, R. Hass, O. Reich (open access available)
Biogenic dispersions: Optical monitoring of chemical processes in turbid biogenic liquid dispersions by Photon Density Wave spectroscopy by R. Hass, D. Munzke, S. Vargas Ruiz, J. Tippmann, O. Reich
Particle sizing: Particle sizing in highly turbid dispersions by Photon Density Wave spectroscopy by L. Bressel, R. Hass, O. Reich
In-line particle sizing: Industrial applications of Photon Density Wave spectroscopy for in-line particle sizing by R. Hass, M. Münzberg, L. Bressel, O. Reich
PIT Emulsification:In-line Characterization of Phase Inversion Temperature Emulsification by Photon Density Wave Spectroscopy by M. Münzberg, R. Hass, O. Reich
Monitoring of Milk: Optical monitoring of milk fat phase transition within homogenized fresh milk by Photon Density Wave spectroscopy by S. Vargas Ruiz, R. Hass, O. Reich
Polymerization: Photon Density Wave Spectroscopy for Dilution-Free Sizing of Highly Concentrated Nanoparticles During Starved-Feed Polymerization by R. Hass, O. Reich
Emulsification: Sensing emulsification processes by Photon Density Wave spectroscopy by O. Reich, L. Bressel, R. Hass
Review: Inline-Partikelgrößenmesstechniken für Suspensionen und Emulsionen by R. Hass, D. Munzke, O. Reich
Bidispersity: Photon Density Wave spectroscopy: Bidisperse Systems by L. Bressel, J. Wolter, O. Reich
Monte-Carlo Simulations: Theoretical and experimental study of the diffuse transmission of light through highly concentrated absorbing and scattering materials. Part I: Monte-Carlo Simulations by L. Bressel, O. Reich
Photon Density Wave spectroscopy: Fiber-optical sensing in turbid media by Photon Density Wave Spectroscopy by R. Hass, S. Vargas Ruiz, O. Reich
Photon Density Wave spectroscopy: Optical sensing with photon density waves: Investigation of model media by O. Reich, H.-G. Löhmannsröben, F. Schael