Fresnel zone

About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.

Light scattering from binary optics

Abstract: We have calculated the angle-resolved scattering from several phase only Fresnel zone plates (lenses) and Dammann gratings (beam splitters). We simulate manufacturing errors by random perturbations of the surface-relief pattern, and calculate the irradiance in the far-field by evaluating the Fresnel diffraction integral. Scattering from perturbations of the etch depth is found to be proportional to the square of the ratio of the perturbation divided by the wavelength. Random perturbations of the pattern edges in Fresnel zone plates causes more scattering with shorter wavelengths than with longer wavelengths, but in Dammann gratings this scattering is independent of wavelength. Scattering increases for either small apertures or small f-numbers; but does not depend on either the number of levels in a Fresnel zone plate, the pattern in a Dammann grating, or the form of the probability distribution function.

Free-space optical collinear crossover interconnects.

Abstract: Two new optical free-space collinear cross-over interconnect schemes are suggested. The first optical implementation uses mirrors and beam splitters, while the second uses a Fresnel zone plate and lens combination. Some proof-of-principle experimental results are also presented.

New Methods Of Designing Holographic Optical Elements

Abstract: Holographic optical elements (photographically produced Fresnel zone plates) can be easily designed with lens design computer codes using an analogous lens model. From a ray tracing point of view this lens model focuses light exactly the same as a holographic optical element. The analog works for on-axis rays, off-axis rays and any wavelength.© (1977) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Simple and rigorous analytical expression of the propagating field behind an axicon illuminated by an azimuthally polarized beam.

Abstract: A simple and rigorous analytical expression of the propagating field behind an axicon illuminated by an azimuthally polarized beam has been deduced by use of the vector interference theory. This analytical expression can easily be used to calculate accurately the propagation field distribution of azimuthally polarized beams throughout the whole space behind an axicon with any size base angle, not just restricted inside the geometric focal region as does the Fresnel diffraction integral. The numerical results show that the pattern of the beam produced by the azimuthally polarized Gaussian beam that passes through an axicon is a multiring, almost-equal-intensity, and propagation-invariant interference beam in the geometric focal region. The number of bright rings increases with the propagation distance, reaching its maximum at half of the geometric focal length and then decreasing. The intensity of bright rings gradually decreases with the propagation distance in the geometric focal region. However, in the far-field (noninterference) region, only one single-ring pattern is produced and the dark spot size expands rapidly with propagation distance.

Alignment apparatus for X-ray or optical lithography

Abstract: Fine alignment of mask (12) and wafer (13), using Fresnel zone plates is achieved by focussing light on the wafer using a zone plate in the mask. Light diffracted from a zone plate on the wafer is received by a sensor (14). The received light is coded (analog or digital) to indicate alignment. For analog coding the wafer zone plate diffracts light to the sensor from an area of the wafer zone plate which is indicative of alignment. For digital coding the wafer plate is digitally encoded as a function of alignment to similarly code the diffracted light.