Third-order aberrations in GRIN crystalline lens: a new method based on axial and field rays.

This paper presents a new procedure for calculating the third-order aberration of gradient-index (GRIN) lenses that combines an iterative numerical method with the Hamiltonian theory of aberrations in terms of two paraxial rays with boundary conditions on general curved end surfaces and, as a second algebraic step has been presented. Application of this new method to a GRIN human is analyzed in the framework of the bi-elliptical model. The different third-order aberrations are determined, except those that need for their calculation skew rays, because the study is made only for meridional rays.

Laser direct-write technique for fabricating microlens arrays on soda-lime glass with a Nd:YVO4 laser.

A one-step direct-write technique for fabricating spherical microlenses on soda-lime glass substrates is described. Using a Q switched Nd:YVO(4) laser combined with a galvanometer system, square and triangular microlens arrays were fabricated. The focal length of microlenses is measured using direct and nondirect methods.

Temporal zone plate.

This paper extends the investigation of zone plates to the temporal case. By exploiting the space-time duality between the paraxial diffraction of beams in space and the linear dispersion of optical pulses, we present the time-domain analog of a multiple imaging system. The temporal system is created by using a digital chirp signal generator together with two dispersive delay lines.

Hybrid refractive-diffractive-gradient-index superresolving focusing device.

The focusing properties and resolving power of a device consisting of a tapered gradient-index (GRIN) lens with spherical input and output faces are investigated through the use of the ABCD formalism to achieve minimization of the Airy radius for the device. Diffractive elements, such as zone plates, can, with an appropriate choice of their parameters, increase the resolution of an imaging system compared with a conventional lens. We demonstrate that by combining both elements a hybrid refractive-diffractive-GRIN device can be designed that exhibits improved superresolution characteristics.

Radio-frequency spectrum analysis of a jittery train after a second-order dispersive Talbot line.

The power spectral density of the intensity of coherent Gaussian pulse trains suffering timing jitter after a dispersive line with arbitrary first- (beta(2)) and second-order (beta(3)) dispersion is computed in the small-signal approximation. Due to timing jitter noise, the initial radio-frequency spectrum shows noise bands whose bandwidth and position depend, respectively, on the jitter's standard deviation and on the jitter's pulse-to-pulse correlation. After setting the accumulated first-order dispersion to Talbot conditions, it is shown that the influence on the noise spectrum is a multiplicative factor with a multiple-bandpass structure.

Walsh-Hadamard analysis applied to the study of light propagation in a tapered gradient-index medium.

The analysis of light propagation in a tapered gradient-index (GRIN) medium when the input signal is a binary function is considered with the Walsh-Hadamard analysis. The study of the evolution of the sequency spectrum through the GRIN medium by the Walsh-Hadamard transform confirms the self-imaging effect.

Focusing of light by zone plates in Selfoc gradient-index lenses.

We study the diffraction fields in a hybrid diffractive-gradient-index element composed of an amplitude zone plate and a quarter-pitch Selfoc gradient-index lens under uniform illumination. Focal positions of the diffractive orders and zone-plate diffraction efficiencies are measured, thereby validating the existing theoretical results.

Talbot conditions, Talbot resonators, and first-order systems.

A study of first-order Talbot resonators is presented. The general conditions for Talbot effect in ABCD systems are determined. These conditions are applied to the computation of the diffraction overlapping coefficients between array Gaussian emitters in a general first-order Talbot resonator.

Zone-plate diffraction patterns in gradient-index media.

Diffraction patterns inside gradient-index media in which a complex zone plate is placed at a Fourier transform plane are studied by making use of the optical propagator. The results are illustrated with an example corresponding to a selfoc medium and a Fresnel zone plate of the amplitude and of the phase.

Fresnel zones in tapered gradient-index media.

The free propagation of a wave front in an inhomogeneous medium with parabolic refractive-index profile and the division of the wave front into Fresnel zones are studied. We determine the radius and the area of each zone as well as the zone contribution to the total wave at an observation point inside the medium. We find the condition that the optical path must fulfill from each zone to that point so that the disturbance due to successive zones will be in phase opposition.