A Novel Artificial Superposition Compound Eye

A new artificial superposition compound eye model is presented based on micro-lens array. In all compound eyes,it has the advantages of small volume,light weight,wide FOV,high sensitivity and much higher energy utilization ratio. Nevertheless,its structure is relatively complicated,especially the GRIN medium in the crystalline cone. Therefore,the modeling,analysis and fabrication for it are burdensome. In the established model,the GRIN is replaced by a curved micro-lens array. Thus,the modeling,analysis and optimization process are simple,and the components of artificial superposition compound eye are easy to be fabricated. The system is modeled by ZEMAX software. With the help of raytracing,its principle is analyzed,and the sensitivity comparison between the superposition compound eye and the apposition compound eye is done. The model's validity is proven.

Nonequidistant two-dimensional antenna arrays based on Latin squares

Non-equidistant sparse antenna arrays constructed on the basis of Latin squares are considered. A method for their construction and a synthesis algorithm are proposed,and the properties of two-dimensional antennas based on them,which ensure,at a high degree of rarefaction,a sufficiently small lateral radiation are studied. The features and main characteristics of such antennas are studied.

Integral imaging-based tabletop light field 3D display with large viewing angle

Light field 3D display technology is considered a revolutionary technology to address the critical visual fatigue issues in the existing 3D displays.Tabletop light field 3D display provides a brand-new display form that satisfies multi-user shared viewing and collaborative works,and it is poised to become a potential alternative to the traditional wall and portable display forms.However,a large radial viewing angle and correct radial perspective and parallax are still out of reach for most current tabletop light field 3D displays due to the limited amount of spatial information.To address the viewing angle and perspective issues,a novel integral imaging-based tabletop light field 3D display with a simple flat-panel structure is proposed and developed by applying a compound lens array,two spliced 8K liquid crystal display panels,and a light shaping diffuser screen.The compound lens array is designed to be composed of multiple three-piece compound lens units by employing a reverse design scheme,which greatly extends the radial viewing angle in the case of a limited amount of spatial information and balances other important 3D display parameters.The proposed display has a radial viewing angle of 68.7°in a large display size of 43.5 inches,which is larger than the conventional tabletop light field 3D displays.The radial perspective and parallax are correct,and high-resolution 3D images can be reproduced in large radial viewing positions.We envision that this proposed display opens up possibility for redefining the display forms of consumer electronics.

Simple and High-Efficiency Preparation Method of Biometric 3D Artificial Compound Eyes for Wide-Field Imaging

Three-dimensional(3D)artificial compound eyes(ACEs)are helpful for wide field-o-fview imaging and sensing system applications.However,existing batch preparation methods are technically challenging.A bio-inspired,simple,and high-efficiency batch preparation method is proposed,which involves bonding a sticky microlens array(MLA)polydimethylsiloxane(PDMS)film to an elastic PDMS hemisphere under pressure,followed by abrupt pressure removal.Characterizations from a scanning electron microscope and laser scanning confocal microscope show that 3D ACEs prepared using the proposed method have high numbers of uniformly distributed ommatidia with a high-quality finish.Furthermore,optical imaging investigations demonstrate that the proposed preparation method can achieve clear,distortionfree imaging with a wide field-of-view(up to 140.2°).

Chemical compounds as well as antioxidant and litholytic activities of Arbutus unedo L. leaves against calcium oxalate stones

Objective: The present study aimed to quantify and identify the bioactive compounds of the Arbutus unedo L. leaves in order to evaluate both their antioxidant properties and litholytic activities against calcium oxalate stones.Methods: This survey was carried out using hydroalcoholic extract(E.FA) and infusion(I.FA) of A. unedo leaves. The quantification of phenolic compounds, flavonoids, flavonols and anthocyanins was done by spectrophotometric methods and identification of chemical components was performed by ultraperformance liquid chromatography with photodiode array and electrospray ionization tandem mass spectrometry. Antioxidant activity was measured using the 1,1-diphenyl-2-picrylhydrazyl(DPPH)method and by the ferric reducing/antioxidant power(FRAP) assay. Litholytic activity of E.FA and I.FA was studied using a special model that resembles circuitry of the urinary system.Results: E.FA showed greater antioxidant efficacy than I.FA(P < 0.05). Its higher efficiency was shown via the values of median inhibitory concentration, which was close to(76.14 ± 0.91) mg/mL for E.FA versus(202.64 ± 5.77) lg/mL for I.FA using the DPPH method, and(53.77 ± 0.81) lg/mL for E.FA versus(236.86 ± 31.90) lg/mL for I.FA, using FRAP method. I.FA exhibited significantly higher litholytic activity compared to E.FA(P < 0.05), with dissolution values of 31.03% ± 0.63% versus 14.55% ± 0.65%, respectively.Conclusion: Overall, the results suggest that the A. unedo is rich in bioactive compounds, and possesses antioxidant and litholitic abilities that are worthy of further study.

Multi-aperture optical imaging systems and their mathematical light field acquisition models

Inspired by the compound eyes of insects,many multi-aperture optical imaging systems have been proposed to improve the imaging quality,e.g.,to yield a high-resolution image or an image with a large field-ofview.Previous research has reviewed existing multi-aperture optical imaging systems,but few papers emphasize the light field acquisition model which is essential to bridge the gap between configuration design and application.In this paper,we review typical multi-aperture optical imaging systems(i.e.,artificial compound eye,light field camera,and camera array),and then summarize general mathematical light field acquisition models for different configurations.These mathematical models provide methods for calculating the key indexes of a specific multiaperture optical imaging system,such as the field-of-view and sub-image overlap ratio.The mathematical tools simplify the quantitative design and evaluation of imaging systems for researchers.