Holographic shift multiplexing by using rod lens array referencing

We demonstrate both theoretically and experimentally a shift multiplexing method for holographic data storage by using a rod lens and rod lens array (RLA). RLA referencing provides a simple and effective way to increasing the holographic storage density. The sidelobe intensity is reduced to 0.3% and multiple holograms are proven to be stored with a spatial separation of 1.2 μm without crosstalk.     

Shift multiplexing by planar waveguide referencing

We present a new method with which to implement shift multiplexing by planar waveguide referencing. In this method, a planar waveguide is used to steer the reference beam, and we implement shift multiplexing by shifting the recording medium. A spatial selectivity as high as 1.1 microm is obtained. By using waveguide referencing we can make a compact and simple holographic system.     

Autostereoscopic display with bicylindrical lens based on temporal-spatial multiplexing

An autostereoscopic display system with a bicylindrical lens based on temporal-spatial multiplexing technique is introduced in this paper. The system comprises a directional scanning backlight, a liquid crystal display panel with high refreshing rate,and an eye tracking device. The directional scanning backlight consists of an LED board, two lenticular lens arrays with matching periods, a parallax barrier film, and other optical films. One of the lenticular lenses is a bicylindrical lens designe...     

Secure orthogonal time-frequency multiplexing with two-dimensional encryption for optical-wireless communications

This paper firstly, to the best of our knowledge, proposed two-dimensional(2D) encryption based on the Arnold transformation for implementing a secure DC-biased optical orthogonal time-frequency multiplexing(DCO-OTFM) in optical-wireless communications(OWCs). The encrypted data is transformed to the particular 2D matrix and decrypted by the only key to get the correct information. Meanwhile, the number of keys in 2D encryption is enormous, which prevents eavesdroppers from exhaustively searching secret keys rapidly to find the right decryption. Numerical results demonstrate that the secure DCO-OTFM based on 2D encryption can effectively prevent signal decryption from the eavesdropper, which has good secure performance for applying in OWC.     

Transmission of two-dimensional images by wavelength multiplexing

Wavelength multiplexing is a method for encoding spatial information into spectral information. Previously, each point of a one-dimensional image corresponds to a specific wavelength. All wavelengths together can be transmitted in scrambled fashion through a single light fiber. Decoding into the original image is achieved by sending the transmitted light through a spectroscope. This process again displays the various wavelengths at various positions along a line. In this project, two-dimensional spatial information or grey tone images are encoded into a spectral distribution. After transmission through a light fiber this spectrum can be decoded into the original two-dimensional image. Four different encoding versions are presented, which use serial transmission parallel transmission, shifted light coupling or spatial pulse modulation.     

二维空间紫外LED阵列实现单光斑辐照固化系统的设计

新型大功率紫外LED具有电光转化效率高、光谱纯度高和体积小等优点,但单管LED功率仍很难满足光固化的要求,针对单光斑辐照要求,提出采用空间阵列UV-LED排布实现能量累加的方案。该方案通过单管LED聚光系统与集成阵列系统综合设计实现了各单元单光斑辐照度在辐照面上的合成,最终得到的光斑辐照度分布均匀、尺寸合理,阵列系统后工作距离长,完全满足现场应用的具体指标要求。通过外围电子线路控制阵列LED的电流强度及通断状态可实现光斑辐照度在(1000～1800) mW/cm²可调,光斑尺寸为1cm²,后工作距离为10cm。     

Invariant-focusing two-dimensional lens for a finite-emittance beam

A two-dimensional lens consisting of three pairs of plates is investigated. Expressions are given for the magnification of the lens in crossover-to-crossover conversion. Invariant-focusing regimes that preserve a constant crossover position against variation of the beam energy are determined for this lens. The influence of the angular and linear beam dimensions on the crossover position is analyzed in detail in the example of a particular lens configuration. Zh. Tekh. Fiz. 68, 126–128 (October 1998)     

Beam smoothing by lens array with spectral dispersion

A scheme of combining technology of lens array (LA) and smoothing by spectral dispersion (SSD) is introduced to improve the irradiation uniformity in laser fusion based on the earlier works on LA. The feasibility of the scheme is also analyzed by numerical simulation. It shows that a focal pattern with flat-top and sharp-edge profile could be obtained, and the irradiation nonuniformity can fall down from 14% with only LA to 3% with both SSD and LA. And this smoothing scheme is depended less on the incidence comparing to other smoothing methods. The preliminary experiment has demonstrated its effectiveness.     

Coercivity reduction in a two-dimensional array of nano-particles

We report on theoretical investigation of the magnetization reversal in two-dimensional arrays of ferromagnetic nano-particles with parameters of cobalt. The system was optimized for achieving the lowest coercivity in an array of particles located in the nodes of triangular, hexagonal and square grids. Based on the numerical solution of the non-stochastic Landau-Lifshitz-Gilbert equation we show that each particle distribution type is characterized with a proper optimal distance, allowing to lower the coercivity values for approximately 30% compared with the reference value obtained for a single nano-particle. It was shown that the reduction of coercivity occurs even if the particle position in the array is not very precise. In particular, the triangular particle arrangement maintained the same optimal distance between the particles under up to 20% random displacements of their position within the array.     

Silicon photonic MZI sensor array employing on-chip wavelength multiplexing

In this work, we present a novel wavelength multiplexing concept for an integrated label-free biosensor array employing silicon photonic Mach-Zehnder interferometers as sensors. Microring resonators act as wavelength selective elements in order to address the individual interferometers. Wire Bragg gratings terminate the interferometer arms and reflect the light back, which eliminates the risk of a wavelength mismatch between drop and add port. The characteristics of the device are discussed and the design based on FEM and 3D-FDTD simulations as well as measurements of the nanophotonic key components—micro ring resonators, Mach-Zehnder interferometers and photonic wire Bragg gratings—are presented. Measurements of combinations of the wire Bragg gratings with ring resonators and Mach-Zehnder interferometer sensors demonstrate the applicability of the reflectors in photonic circuits.     

Design alternatives for a thin lens spatial integrator array

In this paper we analyze different alternatives in the design of optimized optical arrays having spatial integration feature in a plane arrangement. More specifically, we focus our attention in the evaluation of the number of useful individual units, and its contribution to the synthetic image characteristics. The analysis has been made by using matrix optics relations. Two examples of planar thin lens spatial integrator arrays are designed and compared.     

Collective behaviour of a two-dimensional array of interacting lines

A statistical two-dimensional interacting line model is defined in terms of three parameters describing the line stiffness, the line-line interaction and an external restoring force. It describes the collective properties of various physical systems like reconstructing surfaces, disordering stepped surfaces and adsorbed interacting polymers. The statistical properties are calculated by a Monte-Carlo method. The resulting phase diagram is presented for various parameters and an Ising critical behaviour at the phase boundaries is established. For the case of competing interactions a disorder line is found.     

LED阵列光源的舞台灯变焦透镜系统

 针对国内大功率LED阵列光源舞台灯具在光束角度不可变和光能利用效率低等问题,提出利用透镜组变焦原理来设计阵列光源变焦透镜系统。基于透镜组变焦原理设计了单颗LED光源的变焦透镜组,高级光学系统分析模拟软件ASAP的计算结果显示：调焦范围为0~10 mm时,出光角度（1/10峰值角）的变化范围为18.5°~38.7°,光能利用效率在调焦距离为10 mm时达到78%以上。在此基础上,将单颗LED光源的变焦透镜组扩展为Red、Green、Blue各12颗共36颗LED的变焦透镜系统,进一步分析36颗LED阵列光源在不同排布方式下的出光角度及混色效果。ASAP计算结果显示：在调焦范围与单颗LED相同的情况下,LED阵列光源变焦透镜系统的出光角度（1/10峰值角）的变化范围为21°~38.6°,且3种颜色LED交叉排列的混色效果较好。由LED阵列的计算结果可知,与国内现有的大功率LED舞台灯具相比,在出光角度的变化范围和光能利用效率方面都得到了提高。     

用线阵CCD测量透镜焦距

根据透镜成像原理,利用ＣＣＤ和单片微型计算机测量像的大小,再由单片微机计算待测透镜的焦距,由于该方法采用光电技术,测量透镜焦距的精度较高。     

Schemes of a fiber-optic multiplexing sensor array based on a 3 X 3 star coupler

A Michelson-based fiber-optic low-coherence interferometric quasi-distributed sensing system permitting absolute length measurement in a sensor array is proposed. The main part of the sensing system is a fiberoptic 3 x 3 star coupler. The architecture of fiber-optic sensors can be easily realized as a linear sensor array, twin sensor arrays, or a loop sensor array. The proposed sensing scheme will be useful for the measurement of strain distribution. An important application could be deformation sensing in smart structures. A six-sensor array is demonstrated experimentally.     

Optimum holographic optical element lens recorded by visible laser beams for an infrared two-dimensional vertical-cavity surface-emitting laser array

We have designed an optimum holographic optical element (HOE) lens recorded by visible laser beams for an infrared two-dimensional vertical-cavity surface-emitting laser (VCSEL) array. The hologram computer-aided design tool that we have developed is used for the optimum design. The optimum HOE has both high light efficiency and a small amount of aberration. An Nd:YAG laser operated at 532 nm and an 8 x 8 VCSEL array operated at 850 nm are used for HOE recording and reconstruction, respectively. The designed lens is experimentally demonstrated, and the experimental results of the lens almost agree with the numerical results.     

Time-delayed spatial patterns in a two-dimensional array of coupled oscillators

We investigated the effect of time delays on phase configurations in a set of two-dimensional coupled phase oscillators. Each oscillator is allowed to interact with its neighbors located within a finite radius, which serves as a control parameter in this study. It is found that distance-dependent time delays induce various patterns including traveling rolls, squarelike and rhombuslike patterns, spirals, and targets. We analyzed the stability boundaries of the emerging patterns and briefly pointed out the possible empirical implications of such time-delayed patterns.