Holographic Multiple Input Output (HMIMO), which integrates massive antenna elements into a compact space to achieve spatially continuous aperture, plays an important role in future wireless networks. With numerous elements, it is hard implement the HMIMO via phased arrays due unacceptable power consumption. To address this issue, reconfigurable refractive surface (RRS) energy-efficient enabler...

Intelligent reflecting surfaces (IRSs), which are capable of adjusting radio propagation conditions by controlling the phase shifts waves that impinge on surface, have been widely analyzed for enhancing performance wireless systems. However, reflective properties studied IRSs restrict service coverage to only one side surface. In this paper, extend communication systems, we introduce concept in...

Gradient-index (GRIN) microlenses (Fig. 1 inset) are important components for example in highresolution optical sensors, optical communication and in technical as well as in medical endoscopy [1, 2]. The ability of GRIN lenses to have plane optical surfaces offers great qualitative advantages in the mounting and miniaturisation of microoptical systems. Instead of the conventional spherical lens...

We present an optically isotropic switchable microlens array (MLA) based on liquid crystals (LCs) using the Joule heating electrode structure. The LC molecules were initially aligned vertically on the lens and electrode surfaces. By applying voltage to the transparent electrodes, the temperature of the LC layer could be changed. Above the clearing point temperature of LCs, the LC layer shows an...

Results. For the spherical surface, both curvature-based paraxial power approximations were uniform over the entire surface because curvature is constant. However, the corneal refractive power increased from center to periphery, demonstrating the known phenomenon of spherical aberration. For the ellipsoids, which have been shown to model the human cornea, curvature-based power approximations de...

Because of the complexity of tracing rays through a gradient refractive index medium, the human eye's lens is sometimes approximated by a shell structure with constant refractive index within shells. In the shell model, power arises from a combination of an axial variation in index and the curvatures of the shell surfaces. We develop an equation which gives the power due to the gradient index o...

For more than 100 years, eye scientists and clinicians have recognized that there is a difference between the refractive and anterior corneal astigmatism of the human eye. Javal postulated an approximately linear relationship between corneal astigmatism and refractive astigmatism, which became known as Javal’s rule: refractive astigmatism 1⁄4 1.25 (keratometric astigmatism) 0.50 90. For most ey...

We introduce a novel optofuidic biochemical sensor in which detection is based on the contrast between the refractive index of a target biomaterial and ambient carrier fluid. The sensor consists of parallel vertical micochannels embedded in a planar substrate. The central microchannel is illuminated by a focused beam of light and the periodic spacing of the channels combined with the contrast i...