Pressure estimation via measurement of reduced light scattering coefficient by oblique laser incident reflectometry

David Abookasis*, Daniel Malchi, Dror Robinson, Mustafa Yassin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Continuous measurement of pressure is vital in many fields of industry, medicine, and science. Of particular interest is the ability to measure pressure in a noninvasive and contact-free manner. This work presents the potential of oblique incident reflectometry (OIR) to monitor variation in pressure via the reduced scattering parameter ( μ s ′ ) . Pressure deforms the geometry of the medium and causes distortion of its internal structure and the spatial distribution of optical properties. Light scattering is related to the morphology (size, density, distribution, etc.) and refractive index distributions of the medium, and applied pressure will influence directly these parameters. Therefore, we assume that pressure can be quantitatively assessed through monitoring the reduced scattering coefficient. For this purpose, the technique of OIR to evaluate the scattering parameter during pressure variations was utilized. OIR is a simple noninvasive and contact-free imaging technique able to quantify both absorption and scattering properties of a sample. In our setup, the medium is illuminated obliquely by a narrow laser beam, and the diffuse reflectance light is captured by a CCD camera. In offline processing, the shift (δ) of the diffuse light center from the incident point is mathematically analyzed and μ s ′ coefficient ( μ s ′ ∼ δ − 1 ) is extracted. We present here confirmation of the validity of this assumption through results of a series of experiments performed on turbid liquid and artery occlusion of a human subject under different pressure levels. Thus, μ s ′ has the potential to serve as a good indicator for the monitoring of pressure.

Original languageEnglish
Article number012028
JournalJournal of Laser Applications
Volume36
Issue number1
DOIs
StatePublished - 1 Feb 2024

Keywords

  • diffuse light reflectance
  • image analysis
  • oblique incident reflectometry
  • pressure measurement
  • scattering coefficient

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