全息光伏打聚光器的设计

本文描述了一种采用全息反射元件的分段谱光伏打聚光器,系统的转换效率可高于26%。分析了聚光器的特性并给出了全息元件的设计参数和制作方法。     

Design of an off-axis HOE light concentrator to focus light from multiple directions in a plane

The attractive and multifunctional properties of holographic optical elements (HOEs) offer an opportunity to create compact optical systems for a wide range of applications. In this paper, we propose a novel method of focusing light onto a small region of space by an off-axis HOE that is illuminated from multiple directions in a plane. An off-axis spherical wave generated from a microscopic objective (0.65 NA) is combined with sequentially illuminated five reference waves at the recording plane. A multi-exposure technique is adopted for recording. A comparison between single-exposure and multi-exposure technique is also presented. The design parameters, performance and possible applications of these optical devices are described.     

A luminescent solar concentrator with 7.1% power conversion efficiency

The Luminescent Solar Concentrator (LSC) consists of a transparent polymer plate, containing luminescent particles. Solar cells are connected to one or more edges of the polymer plate. Incident light is absorbed by the luminescent particles and re‐emitted. Part of the light emitted by the luminescent particles is guided towards the solar cells by total internal reflection. Since the edge area is smaller than the receiving one, this allows for concentration of sunlight without the need for solar tracking. External Quantum Efficiency (EQE) and current–voltage (I –V) measurements were performed on LSC devices with multicrystalline silicon (mc‐Si) or GaAs cells attached to the sides. The best result was obtained for an LSC with four GaAs cells. The power conversion efficiency of this device, as measured at European Solar Test Installation laboratories, was 7.1% (geometrical concentration of a factor 2.5). With one GaAs cell attached to one edge only, the power efficiency was still as high as 4.6% (geometrical concentration of a factor 10). To our knowledge these efficiencies are among the highest reported for the LSC. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

聚光光伏系统的发展及未来趋势

介绍了聚光光伏系统的发展历史和研究现状。对聚光光伏系统中的主件一聚光器和光伏电池进行了详细分类，给出了它们的特点和主要参数。描述了国外一些厂家为提高光伏系统效率并降低成本而研制的太阳跟踪系统。总结出聚光光伏系统的发展趋势，主要是指高倍聚光器＋跟踪系统和低倍大角度聚光器＋分光元件＋多节电池等。最后就目前状况提出了聚光光伏系统商业化还需要解决的问题。     

Modeling and design of an optimized patterned electrode liquid crystal microlens array with dielectric slab

To eliminate the occurrence of disclination lines in the hole patterned electrode liquid crystal microlens array (LC MLA), inserting an ultrathin dielectric slab was proved to be an effective method. The thickness of the dielectric slab played an important role in effecting the optical performance of the liquid crystal microlens array device, including the dynamic focal range, focus diameter and symmetry of phase profile. In this paper, we studied the effect of dielectric slab thickness on the optical performance of the liquid crystal microlens array by numerical simulation. It is indicated that the optical performance of the device could be improved by reducing the dielectric slab thickness, assuming that the dielectric slab thickness was larger than the threshold thickness. The dependence of the threshold thickness on some key parameters was investigated and the associated effect on the optical performance by changing these key parameters was also studied. In the end, the approaches to enhance the optical performance, namely the dynamic focal range of the liquid crystal microlens array was proposed and proved to be in effect by numerical simulation results.     

Monocrystalline silicon photovoltaic luminescent solar concentrator with 4.2% power conversion efficiency

We report conversion efficiencies of experimental single and dual light guide luminescent solar concentrators. We have built several 5 cm×5 cm and 10? cm×10 cm luminescent solar concentrator (LSC) demonstrators consisting of c-Si photovoltaic cells attached to luminescent light guides of Lumogen F Red 305 dye and perylene perinone dye. The highest overall efficiency obtained was 4.2% on a 5 cm×5 cm stacked dual light guide using both luminescent materials. To our knowledge, this is the highest reported experimentally determined efficiency for c-Si photovoltaic-based LSCs. Furthermore, we also produced a 5 cm×5 cm LSC specimen based on an inorganic phosphor layer with an overall efficiency of 2.5%.     

离轴光纤旋转连接器的设计与实验

利用光纤准直器的特殊分布,设计出了一种新型的离轴双向传输旋转结构。该光纤旋转连接器具有两个可绕一共轴相互独立旋转的部件,在一个旋转部件上离旋转轴等距处安装四个光纤准直器,在另一个旋转部件上安装两个光纤准直器,两部件上的光纤准直器在旋转过程中始终保持光耦合,从而实现了光信号能在旋转过程中不间断的双向传输。通过分析从光纤准直器出射的光斑功率分布和系统旋转的损耗值,在进一步提升机械性能和光耦合效率的基础上,实现了高质量的图像和视频信号传输。实验结果表明,在旋转部件间距小于500mm和转速小于120r/min的条件下,系统满足1.25Gbit/s的高速率光信号的稳定传输。     

Experimental generation of high-contrast Talbot images with an ultrashort laser pulse

A femtosecond Ti:sapphire laser oscillator emitting pulses with 800 nm central wavelength, 10.9 fs pulse width, and 75 MHz repetition rate, combined with a dispersion-compensated diffractive system, was used to implement a large-area, high-contrast, broadband optical interference technique based on the Talbot effect. Chromatic artifacts associated with the huge spectrum of the optical source (approximately 150 nm) are compensated for with an air-separated hybrid diffractive-refractive lens doublet. The spatial resolution of the chromatically compensated Talbot images under femtosecond illumination is nearly identical to that achieved under continuous wave monochromatic illumination. Furthermore, the temporal width of the signal at the Talbot planes is limited by the group-delay-dispersion coefficient which is shown to be small. High-contrast one-dimensional periodic structures of 96.1 μm spacing generated by Talbot diffractometry are experimentally demonstrated.     

叠层荧光集光太阳能光伏器件的性能模拟和优化

荧光集光太阳能光伏器件可以减少太阳能电池的用量,有效降低光伏发电的成本.相对于单层荧光 集光太阳能光伏器件,叠层荧光集光太阳能光伏器件能分波段充分利用太阳光谱,提高荧光集光太阳能光伏 器件的效率,进一步降低光伏发电的成本.但是,叠层荧光集光太阳能光伏器件涉及较多的参量,难以通过实验 优化.本文分析了从单层到叠层荧光集光太阳能光伏器件的全部物理过程,建立了数学模型,并相应编制了 计算机模拟软件.运用上述软件,系统研究了器件尺寸、太阳能电池的带隙对光电转换效率的影响.     

Self-deflection of partially spatially incoherent beams and solitons in photovoltaic photorefractive crystals

By considering the effect of background light and diffusion, the self-deflection process of partially spatially incoherent (PSIC) beams and photovoltaic (PV) solitons in open-circuit PV photorefractive crystals has been investigated by employing numerical method and the perturbation technique, respectively. The results from the two approaches are in good agreement: the center of PSIC PV solitons moves on a parabolic trajectory, which is similar to those of coherent solitons. In addition, we also discuss that the dependence of self-deflection effect on the coherent parameter θ₀ and find it is slight relative to θ₀ for quasi-soliton but decreases monotonously with θ₀ for PSIC beam.     

Design, realisation and analysis of an apodised, film-loaded acousto-optic tunable filter

The design and realisation of a SiO₂ film-loaded Ti:LiNbO₃ integrated acousto-optic tunable filter are presented. An optimised Hamming apodisation is achieved through introducing an angular offset between the acoustic and optical waveguides along with carefully placed acoustic absorbers. The realised device has a 20-mm acoustic interaction length and achieves a 3-dB linewidth of 1.8 nm with 19-dB sidelobe suppression. The realised device is highly efficient, requiring a RF drive power of only 10 mW to achieve complete polarisation conversion. The enhanced drive efficiency of the device is analysed using both acoustic and optical mode analysis. Based on this analysis, possible explanations for the improved behaviour are presented and directions that may lead to further enhancements are discussed. Received: 18 May 2001 / Revised version: 7 August 2001 / Published online: 23 October 2001     

Optimal Design of an Achromatic Angle-Insensitive Phase Retarder Used in MWIR Imaging Polarimetry

Dielectric gratings with period in the range from λ/10 to λ/4 with A being the illumination wavelength not only exclude higher order diffractions but also exhibit strong dispersion of effective indices which are proportional to the wavelength. Moreover, they are insensitive to the incident angle of the illumination wave. With these features, we can design a true zero-order achromatic and angle-insensitive phase retarder which can be used as the polarization state analyzer in middle wave infrared （MWIR） imaging polarimetry. A design method using effective medium theory is described, and the performance of the designed phase retarder is evaluated by rigorous coupled wave analysis theory. The calculation results demonstrate that the retardance deviates from 45° by 〈 ±1.6° within a field of view ：±l0° over the MWIR bandwidth （3-5μm）.     

轻型高稳定性离轴非球面平行光管设计

为了满足高精度相机在外场环境下的检测要求,采用碳化硅光学材料制作反射镜,碳纤/环氧树脂基复合材料制作遮光筒,设计了一套重量轻、自身精度高、温度稳定性好的离轴平行光管。在二者线胀系数保持二倍关系的情况下,在一定温变范围内保持精度的稳定性。经检测,口径为400 mm,焦距为8 m的离轴平行光管的温变为(20±10)℃,系统波像差为1/5λ(P-V值,λ=632.8 nm)和1/27λ(RMS值),达到了设计要求,能够在外场环境下使用。     

多波段共孔径离轴三反光学系统设计北大核心CSCD

针对军用光电系统对视场范围、图像质量和系统小型化的迫切需求,根据指标要求设计了一种大口径离轴三反光学系统。采用离轴多反式结构消除系统遮拦,缩减结构尺寸,通过引入复杂面型实现大孔径设计,在保证足够分辨率的同时,增大光学系统的视场角,以获得更加丰富的目标特征,提高了系统的目标探测和识别能力。与透射式结构与折返式结构相比,大幅度减小了光电产品的体积和质量,有效减轻了伺服设计负荷,具备隐蔽性好、光谱覆盖范围广、透过率高、视场兼容性强的特点。设计结果表明:电视光路在120 lp/mm处全视场MTF>0.2,短波红外光路在60 lp/mm处全视场MTF>0.3,中波红外在30 lp/mm处全视场MTF>0.15,网格畸变小于0.5%,满足设计指标要求。     

大倍率离轴无焦四反光学系统设计

空间引力波探测任务采用的是外差法激光干涉测量技术,其对系统的噪声和精度要求极为苛刻。望远镜是引力波探测天文台的重要组成部分,起到激光信号收发的作用,其光学系统应具备大倍率、高像质、杂光抑制能力强,波前误差一致性好的特点。针对上述要求,对大倍率离轴四反无焦光学系统进行了设计和优化。基于初级像差理论阐述了初始结构的求解方法。系统具有中间像面和可用的实出瞳,便于杂光抑制和与后端科学干涉仪的承接。优化过程中,建立了波前一致性优化函数,通过优化设计,系统入瞳直径为200 mm,放大倍率为40倍,科学视场为±8μrad,波前误差RMS值优于0.005λ,PV值优于0.023λ(λ=1064 nm),波前一致性残差RMS值优于0.0008λ(λ=1064 nm),在捕获视场±200μrad内的成像质量均接近衍射极限,并对系统公差进行了分析,满足引力波探测的应用需求。     

轻型高稳定性离轴非球面平行光管设计

为了满足高精度相机在外场环境下的检测要求,采用碳化硅光学材料制作反射镜,碳纤/环氧树脂基复合材料制作遮光筒,设计了一套重量轻、自身精度高、温度稳定性好的离轴平行光管。在二者线胀系数保持二倍关系的情况下,在一定温变范围内保持精度的稳定性。经检测,口径为400 mm,焦距为8 m的离轴平行光管的温变为（20±10）℃,系统波像差为1/5λ（P-V值,λ=632.8 nm）和1/27λ（RMS值）,达到了设计要求,能够在外场环境下使用。     

A new type of small size acousto-optic tunable filter with super narrow optical linewidth

The new concept of the creation of an acousto-optic tunable filter (AOTF) with super-resolution and small size is discussed. The advantage of the device is based on the use of a novel type of multi reflector beam expander that produces a highly collimated optical beam (angular spread about 100 ppm), tilted with a change in optical wavelength. The proposed AOTF, 1 cm in length, can have an optical linewidth about 0.1 nm and up to 400 tunable channels at a wavelength of 1540 nm. It can be utilized as a tunable filter for dense wavelength-division multiplexing (DWDM) in fiber optic networks and as a small-sized tunable optical spectrometer, for example, in sensors of gases, liquids and solids. The acousto-optic tunable filter can be developed by known technology developed for the creation of integrated optics and microelectronics devices. Received: 28 April 2001 / Revised version: 22 August 2001 / Published online: 2 November 2001     

Fabrication of gradient refractive index ball lenses using the method of combination of ion exchanging and sagging

Based on the Fick’s diffusion equations, the distribution function of refractive index of a gradient refractive index ball lens (GRIN ball lens/GBL) is derived. Lithium containing silicate glass is fabricated and GRIN ball lenses (GBLs) which diameters are from 0.3 mm to 3.0 mm are made by the method of combination of Ion exchanging and sagging in sodium nitrate. Refractive index profiles of these GBLs are measured by interferometer, and the performances such as effective focal length (EFL), back focal length (BFL) and numerical aperture (NA) between GBLs and homogeneous ball lenses (HBLs) are compared. Results show that the distribution of the index of refraction is parabolic curve and its Δn is about 0.0002, the performances of the former are super to the latter.     

基于棱镜二次聚光的高倍聚光模组聚光特性与三结电池光谱响应匹配与优化

目前Ⅲ-Ⅴ多结高倍聚光(HCPV)太阳电池实验室效率记录已高达46%,而相对应的模组效率与之相差仍较大,其中由于模组中聚光非理想性引起的损失就高达20%.本文通过建立光学模型和非均匀光照的三维电池电路网络模型,以Ⅲ-Ⅴ族三结电池为例,研究了菲涅耳透镜一次聚光、棱镜二次聚光的HCPV模组的聚光特性和光电特性.结果发现.由于光线非平行入射和-菲涅耳透镜的色散现象,使得沿光轴方向短、中、长波段聚光发散及聚光不均匀,从而造成了三结电池的上、中、下各子电池光谱响应失配损失,模组光电转换性能下降;进一步,通过采用棱镜二次聚光,能较好地改善聚光和温度均匀性;通过对光轴方向上短、中、长波段的聚光特性与三结电池光谱响应匹配优化,使得模组输出功率提高10%以上.模拟结果己得到实验验证.     

一种大口径离轴反射式太阳模拟系统设计

为了完成全谱段成像光谱仪的地面辐射标定,设计了一种大口径离轴反射式太阳模拟系统,用于在实验室环境下模拟空间环境中的太阳辐射。阐述了太阳模拟系统的光学系统参数的计算过程,并运用Lighttools软件完成了光学系统的建模和仿真,根据光学系统的布局和系统的热负荷分布,给出了风冷系统的设计方案,并运用ICEPAK软件完成了散热系统的仿真验证。测试了太阳模拟系统的各项参数,结果表明:在满足系统散热要求的情况下,最大辐照度达到1.17个太阳常数,辐照不均匀度在辐照面200 mm范围内为1.61%,在辐照面400 mm范围内为3.28%。