Phase-only spatial light modulators are now ubiquitous tools in modern optics laboratories, and are often used to
generate so-called structured light. In this work we outline the use of a phase-only spatial light modulator to achieve full complex amplitude modulation of the light, i.e., in amplitude and phase. We outline the theoretical concept, and then illustrate its use with the example of the laser beam shaping of Gaussian beams into flat-top beams. We quantify the performance of this approach for the creation of such fields, and compare the results to conventional lossless approaches to flat-top beam generation.

The generation of flat-top beams by complex amplitude modulation with a phase-only spatial light modulator

In this paper, we theoretically demonstrate that lenses with negative spherical aberration can be used to reshape a Gaussian Schell-model (GSM) beam to uniform profiles. The numerical calculation results show that, when the coherence of the GSM beam is low, we can achieve uniform GSM beams with smooth top. As the coherence increases, some intensity modulation occurs at the top of the uniform GSM beam. This intensity modulation is caused by the interference of highly coherent light.

Reshaping Gaussian Schell-model beams to uniform profiles by lenses with spherical aberration

This paper describes a technique aimed at measuring particle size by light scattering from gaussian laser beams. The uncertainties in illumination due to the beam shape are avoided by determination of the direction and velocity. The method, which we arbitrarily called the Two Beam System (TBS), uses a simple birefringent prism to separate the incident laser beam into two orthogonally polarised overlapping parallel beams. The relative delay and amplitudes of the intensities scattered out of the orthogonal polarisations are indicative of the particle direction and velocity. Having obtained the direction of travel of the particle, its size is then obtained from the scattered intensity using Mie theory.

A Double Gaussian Beam Method for the Determination of Particle Size, Direction and Velocity

.......................................... . ......................................................................... 21 2.

Three-dimensional mapping of electrical propagation in the heart: experimental and mathematical model based analysis

Dynamic flat-topped laser beam shaping method using mixed region amplitude freedom algorithm

Expressions for describing Gaussian beams focused by a lens with spherical aberration have been derived. Numerical results show that, when the coefficient of the spherical aberration is negative, one can obtain flattened laser irradiance at two positions along the focused field. The larger the coefficient of negative spherical aberration, the larger the flatness is. The effect of the Fresnel number of the focusing lens on the flattened laser irradiance is also investigated.

Huihua Zhang

Papers

Aberrated lenses for generating flattened laser irradiance