Biomedical subjects

Vidal F Canales

Publications and source records attributed to Vidal F Canales.

3 recordsLinked to original sources

PubMed2004

Superresolution in compensated telescopes.

We present a procedure for attaining resolution beyond the diffraction limit in ground-based telescopes. This procedure is based on the use of rotationally symmetric pupil plane filters that can be easily implemented in dynamic optical devices such as a deformable mirror of an adaptive-optics system. We show that a successful application of the technique requires partial compensation for atmospheric distortion by adaptive optics. Consequently, we derive the required level of compensation as a function of the atmospheric conditions. Finally, our results are checked using simulated data.

Journal Article↗

PubMed2003

Design of superresolving continuous phase filters.

We present a procedure for designing to control the three-dimensional light-intensity distribution near focus. Our method is based on the use of a series of figures of merit that are properly defined to describe the effect of general complex pupil functions. As a practical implementation, we have applied our method to obtain super resolving continuous smoothly varying phase-only filters. The advantages of these kinds of filters are that they do not produce energy absorption and they are easy to build with a phase-controlling device such as a deformable mirror. Results of comparisons between the performance of our method and that of other phase-filter designs are provided.

Journal Article↗

PubMedDate not supplied

Monte Carlo simulation of irradiance distribution on the retina after refractive surgery.

PURPOSE: Generation of random wavefronts for ocular wave aberration statistics across the population has been used for various analyses. We propose a more accurate simulation procedure. This simulation technique is not intended to be a perfect representation of an eye, but instead is a tool for those applications where a correct distribution of aberrations across a population is necessary. METHODS: Our technique consists of the generation of coefficients of the wavefront expansion into Zernike modes. The simulation makes use of the variance of every mode measured on a large population by using compact and reliable wavefront sensors. RESULTS: The simulation procedure was verified by reproducing two statistical functions that characterize eye behavior. This tool can be used to predict the performance of sensing techniques and to evaluate the consequences of customized ophthalmic elements and refractive surgery. It may also be useful for deriving both first and second order photon statistics of the point-spread function on the human retina (a key parameter in certain visual perception models). CONCLUSIONS: A new tool for analysis of customized refractive surgery is presented and the evolution of the light intensity probability density function on the retina with compensation attained after customized correction of the eye's aberrations is analyzed.

Humans↗