Anisotropic Subsurface Scattering Acquisition Through a Light Field Based Apparatus

Subsurface scattering gives a distinct look to many everyday objects. However, until now, systems to acquire subsurface scattering have assumed that the subsurface displacement and angle of scattering are completely independent of the angle of incident. While this independence substantially simplifies the acquisition and rendering of materials where it holds true, it makes the acquisition of other materials impossible. In this paper, we demonstrate a system that can quickly acquire the full anisotropic subsurface scattering at a given point. Unlike many existing commercial acquisition systems, our system can be assembled from off-the-shelf optical component and 3D printed/cut parts, making it accessible at a low price. We validate our device by measuring and fitting a dipole model for material exhibiting isotropic subsurface scattering as well as comparing real-world appearance with rendering of anisotropic material under incident laser beam illumination.

Higher harmonic generation by self-focused q-Gaussian laser beam in preformed collisionless plasma channel

This paper presents an investigation of self-focusing of a q-Gaussian laser beam and its effect on harmonic generation in a preformed collisionless parabolic plasma channel. In the presence of a q-Gaussian laser beam, the carriers get redistributed from high field region to low field region on account of ponderomotive force as a result of which a transverse density gradient is produced in the channel which in turn generates plasma wave at pump frequency. Generated plasma wave interacts with the incident laser beam and generate higher harmonics of the incident laser beam. Moment theory has been used to derive differential equation for the spot size of laser beam propagating through the channel. The differential equation so obtained has been solved numerically. The effect of the intensity of laser beam, deviation of intensity distribution of laser beam along its wave front from Gaussian distribution, plasma density and depth of channel on beam width of laser beam and harmonic yield has been investigated. The effect of order of higher harmonic on harmonic yield has been also investigated.

Electric, magnetic Wakefields, and electron acceleration in quantum plasma

A detailed study of Wakefield excitation in very dense quantum plasma is presented. Electric and magnetic Wakefields have been obtained for a particular profile of the laser pulse, using perturbative technique involving orders of the incident laser beam. The Wakefields can trap electrons and accelerate them to extremely high energies. It is observed that the quantum effects significantly change the classical nature of the Wakefield. The axial and radial forces acting on a test electron due to the Wakefields have been evaluated.