Impact of different receiver geometries on a reconfigurable intelligent surface assisted multi-cell VLC system in the presence of light path blockage.

We report the effect of integrating metasurface-aided reconfigurable intelligent surfaces (RISs) on the signal-to-interference-plus-noise ratio (SINR) and data rate of a multi-cell visible light communication (VLC) system. RIS has been deployed in the channel between transmitter and receiver to redirect the reflected light in the desired directions, even in the absence of line-of-sight (LoS) links. Results show that the introduction of RIS has improved average SINR but reduced average illumination level compared to a no-RIS system.

Computational-sampling-moiré-based on-machine alignment for freeform optics.

The manufacturing and characterization of freeform optical surfaces are influenced by their high sensitivity to misalignments. In this work, the computational sampling moiré technique combined with phase extraction is developed for the precise alignment of freeform optics during fabrication and in metrology applications. This novel, to the best of our knowledge, technique achieves near-interferometry-level precision in a simple and compact configuration.

Polishing performance of a magnetic nanoparticle-based nanoabrasive for superfinish optical surfaces.

Superfine optical components are necessary for advanced engineering applications such as x-ray optics, high-power lasers, lithography, synchrotron optics, laser-based sensors, etc. Fabrication of such superfine surfaces is one of the major challenges for optical and semiconductor industries. This research focuses on the development of a magnetic nanoparticle-based nanoabrasive for superfine optical polishing.

Design and development of volume phase holographic grating based digital holographic interferometer for label-free quantitative cell imaging.

In this paper, a volume phase holographic optical element based digital holographic interferometer is designed and used for quantitative phase imaging of biological cells [white blood cells, red blood cells, platelets, and Staphylococcus aureus (S. aureus) bacteria cells]. The experimental results reveal that sharp images of the S.

Weighted spline based integration for reconstruction of freeform wavefront.

In the present work, a spline-based integration technique for the reconstruction of a freeform wavefront from the slope data has been implemented. The slope data of a freeform surface contain noise due to their machining process and that introduces reconstruction error. We have proposed a weighted cubic spline based least square integration method (WCSLI) for the faithful reconstruction of a wavefront from noisy slope data.

Subaperture stitching for measurement of freeform wavefront.

A method based on subaperture stitching for measurement of a freeform wavefront is proposed and applied to wavefronts calculated from the slope data acquired using a scanning Shack Hartmann sensor (SHS). The entire wavefront is divided into a number of subapertures with overlapping zones. Each subaperture is measured using the SHS, which is scanned over the entire wavefront.

Experimental investigation on butane diffusion flames under the influence of magnetic field by using digital speckle pattern interferometry.

In this paper, the effect of magnetic fields on the temperature and temperature profile of a diffusion flame obtained from a butane torch burner are investigated experimentally by using digital speckle pattern interferometry (DSPI). Experiments were conducted on a diffusion flame generated by a butane torch burner in the absence of a magnetic field and in the presence of uniform and nonuniform magnetic fields. A single DSPI fringe pattern was used to extract phase by using a Riesz transform and monogenic signal.

99mTc-Nannocolloid Localization of Lymphorenal Fistula Causing Chyluria.

Chyluria is an abnormal condition in which chyle appears in the urine because of a fistulous communication between the lymphatics and the urinary tract. It is not life-threatening and spontaneous regression is reported in 50% of cases. Lymphangiography has been the main imaging modality for localization of the site of fistula, but it is invasive and requires expertise.

Design considerations for the absolute testing approach of aspherics using combined diffractive optical elements.

Aspheric optical surfaces are often tested using diffractive optics as null elements. For precise measurements, the errors caused by the diffractive optical element must be calibrated. Recently, we reported first experimental results of a three position quasi-absolute test for rotationally invariant aspherics by using combined-diffractive optical elements (combo-DOEs).

Quasi-absolute measurement of aspheres with a combined diffractive optical element as reference.

We have already reported a method for the quasi-absolute test of rotationally symmetric aspheres by means of combined diffractive optical elements (combo-DOEs). The combo-DOEs carry the information for the ideal shape of an aspheric surface under test as well as a spherical wave for the measurement at the cat's eye position. An experimental demonstration of the procedure is given.