Off-axis detection and characterization of laser beams in the maritime atmosphere

Abstract

Remote detection and characterization of laser beams propagating in maritime atmospheres is discussed. A model for off-axis scattered laser light based on Mie scattering from maritime aerosols is presented and compared with angle and time-resolved measurements from a pulsed laser source. We demonstrate that the direction of the source can be determined from the angle-resolved intensity and that the beam direction can be determined from arrival times of the scattered signals if the position of the laser source is known.

Pencil-Beam Approximation of Stationary Fokker--Planck

“…It intents to model a diffusive transport at a scale where the initial directionality of particles is not completely lost, but frequent enough to produce some mixing effect. It is suitable for the study of electron and photon transport [10,25,27], optical imaging and microscopy [13,24], and laser propagation on turbulent media [18,29]. More details on its derivation and application to inverse problem can be found in [4,5], and we refer the reader to [14] for a mathematical introduction to the theory of the transport equation.…”

Off-axis laser beam imaging and characterization with two cameras

“…2. The one-dimensional radiance L W∕m 2 ∕radian of scattered light from an unresolved laser beam is given by [5] Lθ P 0 Tz; r βψ θ R sinψ ;…”

“…Aerosols are generally present in the lower atmosphere although the concentration and specific composition can vary widely and change with time [4]. In previous work, we presented a single-scattering model for the off-axis radiance from a laser beam based on Mie scattering from maritime aerosols and made comparisons with angle and time-resolved measurements using a pulsed laser source [5]. That work demonstrated that the beam orientation relative to the line of sight can be determined from arrival times of the scattered signals if the range to the laser source is known.…”

Pencil-beam approximation of fractional Fokker-Planck

“…It intents to model a diffusive transport at a scale where the initial directionality of particles is not completely lost, but frequent enough to produce some mixing effect. It is suitable for the study of electron and photon transport [10,26,28], optical imaging and microscopy [13,25], and laser propagation on turbulent media [19,30]. More details on its derivation and application to inverse problem can be found in [4,6], and we refer the reader to [14] for a mathematical introduction to the theory of the transport equation.…”