Feasibility of Extending Rainbow Refractometry to Small Particles Using Femtosecond Laser Pulses

Abstract

Rainbow refractometry has been investigated numerically for small droplets under ultrashort pulse illumination. Using Fourier Lorenz-Mie Theory, local maxima of the scattering function were investigated as a function of the scattering angle, particle size and refractive index. The primary rainbow was shown to be detectable for pulse lengths as short as 10 fs and free of interferences with other scattering orders for droplet diameters down to 5 lm. An extension of the Generalized Lorenz-Mie Theory was used to obtain an estimation of the influence of nonsphericity on refractive index detection. Overall, the possibility of improved in situ temperature measurements with Rainbow refractometry for small particles was shown to be feasible.

On the electromagnetic scattering of arbitrary shaped beams by arbitrary shaped particles: A review

“…Both FLMT and EGO were then used to study the imaging properties of scattering particles in laser beams, including a discussion of the "trajectory effect" in the phase-Doppler method [63], which was previously studied in a GLMT framework [64], [65]. FLMT was also used to study optical particle sizing in backscattering with an emphasis on phase-Doppler instruments [66], particle sizing by a time-resolved approach in which microspheres are illuminated by short laser pulses [67], the time integrated detection of femtosecond laser pulses scattered by small droplets [68], and the feasibility of extending rainbow refractometry to small particles using femtosecond laser pulses [69].…”

List of problems for future research in generalized Lorenz–Mie theories and related topics, review and prospectus [Invited]

“…The basic idea for such a GLMT is very simple: (i) a Fourier transform decomposes the illuminating pulse into elementary continuous waves of differing wavelengths, (ii) a GLMT (or more generally any kind of light-scattering theory) is used to compute the response for each elementary wave, (iii) elementary responses are summed up, and (iv) the total response to the illuminating pulse is obtained by an inverse Fourier transform. Numerical implementations of pulsed GLMTs have been published in [109,[209][210][211][212][213][214][215][216][217].…”

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

“…Bakic et al . examined the feasibility of extending rainbow refractometry to small particles using femtosecond laser pulses. Bech and Leder dealt with the simultaneous determination of particle size and refractive index by time‐resolved Mie scattering, and also with two‐particle characterization by pulse‐induced and time‐resolved scattering.…”