Picosecond time scale modification of forward scattered light induced by absorption inside particles

Abstract

Abstract:The aim of this work is to evaluate the influence of absorption processes on the Time Of Flight (TOF) of the light scattered out of a thick medium in the forward direction. We use a Monte-Carlo simulation with temporal phase function and Debye modes. The main result of our study is that absorption inside the particle induces a decrease of the TOF on a picosecond time scale, measurable with a femtosecond laser apparatus. This decrease, which exhibits a neat sensitivity to the absorption coefficient of particles, could provide an efficient way to measure this absorption.

Spatially Resolved Spectral Powder Analysis: Experiments and Modeling

“…If the particles are small compared to the wavelength, the Rayleigh approximation can provide an analytical description of small-particle scattering. 20,21 For describing a larger number of particles, various methods can be applied, depending on the field of interest: (i) exact analytical solutions via the Maxwell equations (i.e., Mie equations); [22][23][24] (ii) stochastic methods (predominantly Monte-Carlo [MC] methods); [25][26][27][28] (iii) geometrical optics (e.g., ray tracing); [29][30][31] (iv) balance equations (known as radiative transfer equation). 16,[32][33][34] As NIR spectroscopy has gained a lot of attention in the pharmaceutical industry, the need for a detailed understanding of the behavior of radiation has increased, especially for products and intermediates like powder blends, granules, ribbons, and tablets.…”

“…For describing a larger number of particles, various methods can be applied, depending on the field of interest: (i) exact analytical solutions via the Maxwell equations (i.e., Mie equations); 22–24 (ii) stochastic methods (predominantly Monte-Carlo [MC] methods); 25–28 (iii) geometrical optics (e.g., ray tracing); 29–31 (iv) balance equations (known as radiative transfer equation). 16,32–34 …”

Latest achievements in generalized Lorenz‐Mie theories: A commented reference database

“…The numerical analysis relied on a temporal Monte‐Carlo simulation scheme, while Kervella et al . dealt with picosecond time scale modification of forward scattered light induced by absorption inside particles, using again a Monte‐Carlo simulation with temporal phase function and Debye modes. Vervelidou and Chrissoulidis dealt with the scattering of a pulsed wave by a sphere with an eccentric spherical inclusion.…”

The influence of turbid medium properties on object visibility in optical Kerr gated imaging

“…The general technique is known as 'time gated imaging' [4,5], and makes use of a very fast shutter to select the ballistic and quasi-ballistic photons from the transmitted imaging photons. Most time gated imaging systems depend on the optical Kerr gate (OKG) technique [6][7][8][9][10][11]. The OKG is based on the optical Kerr effect, and its shutter time can be up to tens of femtoseconds.…”