Efficiency of rotating phase masks in the resolution

The redistribution of light energy in the receiving plane of the diffraction pattern by means of concurrent suppression of side-lobes and the amplification of the central disc by applying rotating phase masks at the exit pupil has been investigated. The magnitude of the suppression of side-lobes depends on the degree of the phase mask at the edge zones of the pupil. The mask is applied to achieve the side-lobe suppression on one side of the PSF. By applying a rotated mask, side-lobe suppression will occur on the other side of the PSF. The resolution of the object or signal under the optimum masking conditions is analysed by employing the standard characteristic parameters of the diffraction

Corollaries of Point Spread Function with Asymmetric Apodization

Primary energy based corollaries of point spread function with asymmetric apodization using complex pupil function have been studied in the case of three-zone aperture. Merit function like semicircled energy factor, excluded semicircled energy, and displaced semicircled energy were analyzed with respect to Airy case in terms of phase and amplitude apodization. Analytical results have been presented for the optimum parameters of phase and amplitude asymmetric apodization

Tailoring the point spread function of an aberrated optical imaging system with Hanning aperture

The point spread function of the optical system in the presence of defocusing effect and the third order wave aberration such as primary spherical aberration with the Hanning amplitude mask is investigated. A significant improvement in the profile of the point spread function has been achieved. Employment of the Hanning amplitude pupil function under the higher degree of spherical aberration and defocusing situation renders the optical systems to perform like a super-resolver. The lateral resolution of the central peak is made to be improved by the highest degree of the amplitude apodization β. The presence of first minima with zero intensity suits the optical system for Rayleigh criterion to be applied for two-point resolution studies

Robust Design of Autofocused Airy Beam-Based Multifocal Metalens With Tunable Intensities

Optical metasurfaces with versatile focal properties have great importance and adaptability in photonic systems and potential applications. The unique capability of the ultra-compact device in forming and modulating light fields is triggered to configure multifocal setups. This study introduces a geometric metasurface consisting of dielectric cross-shaped metaatoms with a suitable phase profile operating in the visible regime that can transport the conjugate focal spot of the auto-focused Airy beam (AFAB) into real space by adding the proper convex lens profile and resulting in three foci whose positions and intensities can be adjusted without redesigning metaatoms architecture. The cross-shaped meta-atoms with complete control of the amplitude and phase of the incident light have considered diverse functionalities for the x-and y-components of the incident light, generating six focal spots with high adjustable intensities shown in free space. The proposed hybrid metalens has shown robustness against change in geometrical design while controlling multifocal setups, which can be useful in developing polarization-sensitive devices, photonics, medicine, micromachining and imaging applications to realize beneficial results

Single-Shot 3D Incoherent Imaging Using Deterministic and Random Optical Fields with Lucy–Richardson–Rosen Algorithm

Coded aperture 3D imaging techniques have been rapidly evolving in recent years. The two main directions of evolution are in aperture engineering to generate the optimal optical field and in the development of a computational reconstruction method to reconstruct the object’s image from the intensity distribution with minimal noise. The goal is to find the ideal aperture–reconstruction method pair, and if not that, to optimize one to match the other for designing an imaging system with the required 3D imaging characteristics. The Lucy–Richardson–Rosen algorithm (LR2A), a recently developed computational reconstruction method, was found to perform better than its predecessors, such as matched filter, inverse filter, phase-only filter, Lucy–Richardson algorithm, and non-linear reconstruction (NLR), for certain apertures when the point spread function (PSF) is a real and symmetric function. For other cases of PSF, NLR performed better than the rest of the methods. In this tutorial, LR2A has been presented as a generalized approach for any optical field when the PSF is known along with MATLAB codes for reconstruction. The common problems and pitfalls in using LR2A have been discussed. Simulation and experimental studies for common optical fields such as spherical, Bessel, vortex beams, and exotic optical fields such as Airy, scattered, and self-rotating beams have been presented. From this study, it can be seen that it is possible to transfer the 3D imaging characteristics from non-imaging-type exotic fields to indirect imaging systems faithfully using LR2A. The application of LR2A to medical images such as colonoscopy images and cone beam computed tomography images with synthetic PSF has been demonstrated. We believe that the tutorial will provide a deeper understanding of computational reconstruction using LR2A

Deep Deconvolution of Object Information Modulated by a Refractive Lens Using Lucy-Richardson-Rosen Algorithm

A refractive lens is one of the simplest, most cost-effective and easily available imaging elements. Given a spatially incoherent illumination, a refractive lens can faithfully map every object point to an image point in the sensor plane, when the object and image distances satisfy the imaging conditions. However, static imaging is limited to the depth of focus, beyond which the point-to-point mapping can only be obtained by changing either the location of the lens, object or the imaging sensor. In this study, the depth of focus of a refractive lens in static mode has been expanded using a recently developed computational reconstruction method, Lucy-Richardson-Rosen algorithm (LRRA). The imaging process consists of three steps. In the first step, point spread functions (PSFs) were recorded along different depths and stored in the computer as PSF library. In the next step, the object intensity distribution was recorded. The LRRA was then applied to deconvolve the object information from the recorded intensity distributions during the final step. The results of LRRA were compared with two well-known reconstruction methods, namely the Lucy-Richardson algorithm and non-linear reconstruction

Deep Deconvolution of Object Information Modulated by a Refractive Lens Using Lucy-Richardson-Rosen Algorithm

A refractive lens is one of the simplest, most cost-effective and easily available imaging elements. Given a spatially incoherent illumination, a refractive lens can faithfully map every object point to an image point in the sensor plane, when the object and image distances satisfy the imaging conditions. However, static imaging is limited to the depth of focus, beyond which the point-to-point mapping can only be obtained by changing either the location of the lens, object or the imaging sensor. In this study, the depth of focus of a refractive lens in static mode has been expanded using a recently developed computational reconstruction method, Lucy-Richardson-Rosen algorithm (LRRA). The imaging process consists of three steps. In the first step, point spread functions (PSFs) were recorded along different depths and stored in the computer as PSF library. In the next step, the object intensity distribution was recorded. The LRRA was then applied to deconvolve the object information from the recorded intensity distributions during the final step. The results of LRRA were compared with two well-known reconstruction methods, namely the Lucy-Richardson algorithm and non-linear reconstruction