Ido Raveh

New properties of the Radon transform of the cross Wigner/ambiguity distribution function

In this correspondence, we prove that the Radon transform of the cross Wigner distribution function is a separable multiplication of fractional Fourier transforms of these functions. Thus, the 2-D cross ambiguity function is a surface of fractional correlation for 1-D signals, each associated with the angle of observation over the surface.

Intraocular omni-focal lens with increased tolerance to decentration and astigmatism.

PURPOSE To measure the optical performance of an extended depth of focus (EDOF) intraocular lens (IOL), which provides an imaging solution for near, intermediate, and distance ranges, and to compare its optical performance to available bifocal IOLs with various extents of decentration and astigmatism aberrations. METHODS A special profile that performs interference principle-based focal extension is engraved on the top of a monofocal rigid IOL. An optical bench based on the L&B eye model was used to test the performance in comparison with the bifocal AcrySof ReSTOR SA60D3 lens (Alcon Laboratories Inc). RESULTS The imaging performances at near, intermediate, and distance ranges were mapped. Different decentration parameters and amount of astigmatism aberration were tested. In numerical simulations and the experimental bench, the EDOF IOL was demonstrated to have good visual acuity in near, intermediate, and distance ranges as well as reduced sensitivity to decentration of up to 0.75 mm and the capability of correcting astigmatism aberrations of up to 1.00 diopter. CONCLUSIONS Extended depth of focus technology is capable of providing clear and focused vision at near, intermediate, and distance ranges. Its high quality imaging is obtained under large decentration conditions and residual astigmatism. This capability broadens the potential use of the technology beyond its application as a simultaneous multifocal lens.

Digital method for defocus corrections: experimental results

One of the main features of modern cameras is their ability to perform a mechanical autofocus and capture a sharp image. Experimental results for misfocusing corrections by fast and exact numerical postprocessing algorithms are presented. Furthermore, the optical transfer function (OTF) for a defocused circular pupil with an arbitrary diameter is presented. These methods are based on the wave optics and, thus, are more realistic than ray optics based methods.

All-optical axially multi-regional super resolved imaging

In this paper we present a new approach of all-optical extended depth of focus providing two (or more) discrete ranges of focused imaging for close as well as far ranges. The fact that the extended depth of focus is not continuous allows obtaining improved contrast in the two (or more) axial regions of extended depth of focus. The design is aimed for the cell phone camera applications where dual range extended depth of focus can allow simultaneous reading of business cards at very short distance as well as very high contrasted imaging at far range.

Omni-focal refractive focus correction technology as a substitute for bi/multi-focal intraocular lenses, contact lenses, and spectacles

We present novel technology for extension in depth of focus of imaging lenses for use in ophthalmic lenses correcting myopia, hyperopia with regular/irregular astigmatism and presbyopia. This technology produces continuous focus without appreciable loss of energy. It is incorporated as a coating or engraving on the surface for spectacles, contact or intraocular lenses. It was fabricated and tested in simulations and in clinical trials. From the various testing this technology seems to provide a satisfactory single-lens solution. Obtained performance is apparently better than those of existing multi/bifocal lenses and it is modular enough to provide solution to various ophthalmic applications.

Extended depth of focus intra-ocular lens: a solution for presbyopia and astigmatism

Purpose: Subjects after cataract removal and intra-ocular lens (IOL) implantation lose their accommodation capability and are left with a monofocal visual system. The IOL refraction and the precision of the surgery determine the focal distance and amount of astigmatic aberrations. We present a design, simulations and experimental bench testing of a novel, non-diffractive, non-multifocal, extended depth of focus (EDOF) technology incorporated into an IOL that allows the subject to have astigmatic and chromatic aberrations-free continuous focusing ability from 35cm to infinity as well as increased tolerance to IOL decentration. Methods: The EDOF element was engraved on a surface of a monofocal rigid IOL as a series of shallow (less than one micron deep) concentric grooves around the optical axis. These grooves create an interference pattern extending the focus from a point to a length of about one mm providing a depth of focus of 3.00D (D stands for Diopters) with negligible loss of energy at any point of the focus while significantly reducing the astigmatic aberration of the eye and that generated during the IOL implantation. The EDOF IOL was tested on an optical bench simulating the eye model. In the experimental testing we have explored the characteristics of the obtained EDOF capability, the tolerance to astigmatic aberrations and decentration. Results: The performance of the proposed IOL was tested for pupil diameters of 2 to 5mm and for various spectral illuminations. The MTF charts demonstrate uniform performance of the lens for up to 3.00D at various illumination wavelengths and pupil diameters while preserving a continuous contrast of above 25% for spatial frequencies of up to 25 cycles/mm. Capability of correcting astigmatism of up to 1.00D was measured. Conclusions: The proposed EDOF IOL technology was tested by numerical simulations as well as experimentally characterized on an optical bench. The new lens is capable of solving presbyopia and astigmatism simultaneously by providing focus extension of 3.00D under various illumination conditions, wavelengths and pupil diameters of the implanted lens without loss of energy at any of the relevant distances.

Image restoration from vibrating photographic systems.

Many photographic systems are located on moving platforms. Because of mechanical vibrations that exist on those platforms, the photographed image is distorted. To avoid those distortions requires that very complicated mechanical attenuators be used. We suggest an optoelectronic image-processing algorithm to overcome the distortions caused by such vibrations. The algorithm for different types of vibration is reformulated in an exact manner, as opposed to the reformulations of previously known calculations. Furthermore, new types of vibration are explored. The algorithm is fully computerized and thus avoids the need for attenuating devices.

Single-output color pattern recognition using a fractional correlator

A novel method for performing color image pattern recogni- tion using a fractional correlator (FC) is proposed. The input plane is illuminated with three different coherent sources of wavelengths corre- sponding to RGB (red, green, and blue) colors. The output plane pro- vides a single output peak, which is a result of an incoherent addition between the three correlations obtained per each color. By using the fractional correlator, which is a partially space variant correlator, we achieve space-variance-controlled color pattern recognition. The use of the three-color illumination can drastically increase the discrimination ability of the suggested correlator.

Invariant pattern recognition based on 1-D Wavelet functions and the polynomial decomposition

Abstract A new filter, consisting of 1-D Wavelet functions is suggested for achieving optical invariant pattern recognition. The formed filter is actually a real function, hence, it is theoretically possible to be implemented under both spatially coherent and spatially incoherent illuminations. The filter is based on the polynomial expansion, and is constructed out of a scaled bank of filters multiplied by 1-D Wavelet weight functions. The obtained output is shown to be invariant to 2-D scaling even when different scaling factors are applied on the different axes. The computer simulations and the experimental results demonstrate the potential hidden in this technique.

Clinical trials of interference-based extended depth of focus intra ocular lens design

In this paper we present the clinical trials performed with intra ocular lens (IOL) design having interference based extended depth of focus. The purpose of such IOL design is to allow cataract patients avoid using glasses after doing their surgery.