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The piezoelectric single crystal PMN-PT has lower acoustic impedance and a higher electromechanical coupling coefficient than conventional piezoelectric materials. For these reasons, single crystal PMN-PT can be a good way to enhance the sensitivity and increase the bandwidth of ultrasonic transducers. However the single crystal has certain limitations in size, manufacturability, and a higher electrical...
Beam scanning performance of planar multifocal transmitarray antennas are investigated in this paper. The advantages of the proposed structure over conventional designs are first delineated, and then a Ku-band transmitarray antenna with quadrufocal phase distribution is designed using the particle swarm optimization technique for 60° scan coverage, which shows a good performance. The results presented...
This paper introduces an improved design method supported by analytical formulas defining the focal curve of a Rotman lens with reduced worst-case phase-aberrations. The benefit of this design approach is illustrated through a specific numerical example and compared to the standard design method.
The paper provides a short overview on recent ESA developments on array antenna architectures for satellite antennas generating a multiple spot beams coverage with a single aperture. In particular, solutions based on direct radiating arrays, discrete lens arrays, and arrays magnified by confocal reflectors will be discussed. ESA is supporting since several years activities in this challenging domain.
This paper reports on the design of broadband lens-integrated differentially driven wire ring on-chip antennas for THz direct detectors in a state-of-the-art SiGe HBT technology. The antenna provides wideband detector operation on a high-permittivity substrate at least within the measured 650–1028 GHz, high radiation efficiency at THz frequencies on a bulk silicon substrate, layout fully compatible...
The design of a 1.2 GHz microstrip antenna utilizing a superstrate layer for gain enhancement is presented. An 4 × 1 antenna array is also studied with the effects of various inter-elemental spacings investigated. The single antenna element achieves 5.74 dB of gain enhancement in simulation through the use of the superstrate lens. The 4 × 1 superstrate array achieves approximately 2.5 dB of gain enhancement...
A circularly polarized slotted substrate integrated waveguide (SIW) array antenna is presented. The objective is to verify the capabilities of a new type of slot to maintain good circular polarization radiation performances for beams scanned over a large angle range. A Rotman lens has been designed to feed a 15 slotted waveguides array generating a set of independent beams covering the ±60° angle...
Face recognition has received a substantial attention from industry and also academics. The improvement in the image sensors has further boosted the performance of the face recognition algorithm in real-world scenarios. In this paper, we evaluate the strength of the light-field camera for for face recognition applications. The main advantage of a light-field camera is that, it can provide different...
Design and fabrication of dielectric lenses for terahertz (THz) focal plane arrays are presented in this paper. Lenses are designed using optical lens and ellipsoid function theory in the terahertz range (centered at f = 300GHz). In order to enhance coupling to planar circuits on wafer, two types of lenses are considered: modified hemispherical, such as extended hemispherical and hypo-hemispherical...
Three dimensional projection-type integral imaging display system using directional projection and elemental image resizing method is reported in this paper. In directional elemental image generation, directional projection geometry is considered for each pixel in order to directional elemental image projection. In this scheme, the elemental image resizing method is used to prevent elemental image...
The effect of variable micropattern for an advanced compound optical film was investigated. This compound optical film was made by using Lithographie galvanoformung abformung (LIGA)-like process. The multi-step electroforming with micro-void embedded Polydimethylsiloxane (PDMS) was developed. This work presents many innovative processes, such as the homemade gray scale mask to fabricate variable size...
The research was to develop a variable focus liquid lens module with a direct current electromagnetic driving. The variable focus lens module consists of a sandwich like structure and an electromagnetic driving device. The module was composed by three acrylic plates by milling machine and coated PDMS film as a fluidic chamber. Three acrylic plates were clipped the PDMS membrane and attached two magnets...
We show a N × M wavelength selective crossconnect (WSX) with flexible passbands that can route any wavelength between any input and output port without spectral gaps.
This study presents a novel and precision process to fabricate microneedle. The process includes microlens array mask with the contact printing in ultraviolet (UV) lithography. The tip of micro tapered cone microneedle utilizes the microlens array mask with geometrical optics. Due to the light pass through a plano convex microlen, a microlen have a focal point. An optical system is set up to characterize...
Most of currently employed laparoscopes use a single and non-tunable solid lens to visualize the surgical environment during minimal invasive interventions. These devices are limited due to the loss of depth perception, fixed view direction and narrow field-of-view (FOV). In this study, a three-dimensional deformable liquid lens array with adaptive focusing and directional view capability is developed...
This study presents an implementation of direction-of-arrival estimation using signals received from a Rotman lens array antenna. The algorithm is based on the magnitude comparison method. The Rotman lens array provides multiple beams toward different directions simultaneously. The beam port outputs, which are converted to the video band using envelope detectors, form an output vector. It is used...
It is experimentally demonstrated that subwavelength holes milled in a metallic film as a set of concentric circular rings can focus linearly polarized light in the visible range.
We report experimental realization of an array of broadband invisibility cloaks, which operates in the visible frequency range. Wavelength and angular dependencies of the cloak array performance have been studied.
We theoretically investigate the temporal-focusing effect generated by a microlens array with patterned height differences among the microlenses, and show how such an effect can be utilized for wide-field optical-sectioning microscopy.
The information of luminance and color at the point where the camera's sight line hits the surface of object. The area is large at which application of range finder is of useful, for example, model generation for computer graphics [1] and robot's eye [2]. In order to realize these requests, range finder needs some functions. Especially, there are 3 functions for range finder used for robot control...
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