Flat polymeric microlens array

A polymer-based flat microlens array is demonstrated. Within each pixel of the array, the polymer presents a circular central-symmetric inhomogeneous orientation. Pixel with such a structure behaves a lens-like character. A suitable amount of liquid crystal mixed in the polymer host can improve not only the lens flexibility but also the lens performance. Moreover, the polymer-based microlens array has the advantages of real planar surface, ultra-thin thickness, and can be designed with any aperture size.     

Optimization of the Hartmann-Shack microlens array

In this work we propose to optimize the microlens-array geometry for a Hartmann-Shack wavefront sensor. The optimization makes possible that regular microlens arrays with a larger number of microlenses are replaced by arrays with fewer microlenses located at optimal sampling positions, with no increase in the reconstruction error. The goal is to propose a straightforward and widely accessible numerical method to calculate an optimized microlens array for a known aberration statistics. The optimization comprises the minimization of the wavefront reconstruction error and/or the number of necessary microlenses in the array. We numerically generate, sample and reconstruct the wavefront, and use a genetic algorithm to discover the optimal array geometry. Within an ophthalmological context, as a case study, we demonstrate that an array with only 10 suitably located microlenses can be used to produce reconstruction errors as small as those of a 36-microlens regular array. The same optimization procedure can be employed for any application where the wavefront statistics is known.     

Tunable microlens arrays using polymer network liquid crystal

A tunable-focus microlens array based on polymer network liquid crystal (PNLC) is demonstrated. The PNLC was prepared using an ultraviolet (UV) light exposure through a patterned photomask. The photocurable monomer in each of the UV exposed spot forms an inhomogeneous centro-symmetrical polymer network which acts as a lens when a homogeneous electric field is applied to the cell. The focal length of the microlens arrays is tunable with the applied voltage.     

Tunable single-mode fiber-VCSEL using an intracavity polymer microlens

We report a tunable, single-mode vertical cavity surface-emitting laser (VCSEL) format suitable for array operation, power scaling, fiber coupling, and operation in isolated environments such as those required by atom optics. The devices are fiber VCSELs, consisting of a semiconductor gain and mirror structure separated from a mirror-coated optical fiber by an air (or vacuum) gap. The gain structure has polymer microlenses fabricated on its surface, of characteristics suitable to focus the oscillating mode on both cavity mirrors, ensuring stable fundamental mode emission and high fiber coupling efficiency. We demonstrate such devices in continuous-wave operation at 1.03 microm at room temperature, with a single-mode tuning range of 13 nm, laser threshold as low as 2.5 mW, and a maximum fiber-coupled output power of 10 mW.     

微透镜阵列光学相控阵扫描技术研究进展

光学相控阵光束扫描技术在激光雷达、空间光通信和光开关等领域拥有巨大的应用潜力。微透镜阵列光学相控阵可以通过微透镜阵列间μm量级的相对位移同时对多个出射光束的二维倾斜相位进行调制,从而实现大角度二维光束扫描,具有出射口径大、结构简单、体积小、微惯性、多功能等优点。首先介绍了微透镜阵列光学相控阵的扫描原理,之后对微透镜阵列光学相控阵国内外的发展现状、应用和现阶段存在的问题进行了阐述,最后对微透镜阵列光学相控阵的发展趋势进行了展望。

     

衍射微透镜列阵的研究与应用

本文研究了衍射微透镜列阵的设计与制作工艺方法，在此基础上研制出一系列衍射微透镜列阵，衍射效率均大于８５％，在深紫外、可见及红外波前传感器中得到了成功应用。     

Analysis of light out-coupling from microlens array

Microlens array has been known to be effective in enhancing the out coupling efficiency of LEDs, OLEDs and other thin film light emitting devices. However, mechanism of efficiency enhancement by use of microlens arrays is still ambiguous, apart from suggestions that it leads to randomization of photons. We have studied the photon dynamics in the presence of microlens arrays and the effect of various parameters e.g. microlens contact angle, absorption and substrate refractive index using ray tracing simulations. Microlens array leads to extraction of a portion of photons outside the escape cone at the cost of reduced extraction from within the escape cone. The reduced extraction from within the escape cone is compensated by multiple reflections from the back surface. Increase in microlens contact angle reduces the number of reflections required for out-coupling hence reducing the absorption in the device.     

Addressable microlens array for parallel laser microfabrication

Parallel processing in femtosecond-laser-based microfabrication is demonstrated using a microlens array in conjunction with a liquid-crystal spatial light modulator (SLM). A portion of the SLM is mapped onto each individual lenslet in the array and can be used to effectively switch foci on and off for fabrication. In addition, the technique allows for homogenizing the intensity of the array of foci and translating spots relative to their natural focus. The technique demonstrates the potential for high efficiency processing of aperiodic structures.     

Second-harmonic-generation microscope with a microlens array scanner

We propose a multifocus scanning technique in second-harmonic-generation (SHG) microscopy in which the SHG detection efficiency and the image acquisition rate are improved by several tens of times compared with typical single-focus scanning techniques. Because of a microlens array scanner, the laser beam of a mode-locked Ti:sapphire laser is split into ~100 beamlets, and the same number of foci are formed in the specimen. Parallel scanning of the foci enables us to observe real-time images of the specimen. The imaging properties and the usefulness of the microscope are demonstrated by SHG images of living HeLa cells and rat cardiac myocytes.     

Snapshot imaging spectrometer based on a microlens array

This Letter proposes a snapshot imaging spectrometer, which obtains the spectral information and spatial information in one shot. The device proposed can achieve the data cube size of 21 × 29 × 40 in the waveband of400–800 nm. The core element of this system is the microlens array, which contains 60 × 60 microlenses in a square arrangement, each microlens has an aperture of 125 μm× 125 μm, and the F number is 15. The microlens array is mounted in a rotation mount, which provides 360° of rotation around the optical axis to maximize the spectral resolution. The final resolution of the system is about 10 nm.     

球形自聚焦平面微透镜阵列研究

本文介绍了制作球形自聚焦平面微透镜阵列的两阶段电场辅助离子交换新工艺,对这种工艺的理论模型作了分析,给出了样品的参数和一组反映样品性能的照片.     

Fabrication and characterization of polydimethylsiloxane concave microlens array

Concave microlens array is fabricated with PDMS (polydimethylsiloxane) material. Resist thermal reflow method and reverse pattern replication method are employed to fabricate the concave microlens array. The optical performance of the PDMS concave microlens array is analyzed with ray-trace method. Profile of the PDMS concave microlens array is observed by metallographic microscope and Talystep. It is indicated by the results that the surface profile of the PDMS concave microlens array is clear and distinct. Optical properties are also tested with Beamprofiler system. The shine spots on the focal plane of the microscope objective are of highly uniformity, and essentially coincide well with the simulation result. The PDMS concave microlens array has potential application in many optoelectronic devices, such as diffusers and scanners.     

Shack-Hartmann sensor based on a cylindrical microlens array

We present a Shack-Hartmann wavefront sensor (SHWS) based on a cylindrical microlens array as a device for measuring highly aberrated wavefronts. Instead of the typical spot pattern created by a conventional SHWS, two orthogonal line patterns are detected on a CCD and are superimposed. A processing algorithm uses the continuity of the focal line to extend the dynamic range of measurement by localizing the line, even if it leaves the CCD area confined by the corresponding microcylinder. The measurement of a wavefront from a progressive addition lens with an 80 lambda peak-to-valley value reveals the capabilities of the sensor.     

紫外衍射微透镜阵列的设计与制备

为了提高紫外焦平面阵列的填充因子,可以通过微透镜阵列与紫外焦平面阵列的集成,以改善紫外焦平面阵列的探测性能。根据标量衍射理论设计了用于日盲型紫外焦平面阵列的128×128衍射微透镜阵列,其工作中心波长为350nm,单元透镜F数为F/3.56。采用组合多层镀膜与剥离的工艺方法制备了128×128衍射微透镜阵列,对具体的工艺流程和制备误差进行了分析,测量了衍射微透镜阵列的光学性能。实验结果表明:衍射微透镜阵列的衍射效率为88%,与理论值95%有偏差,制备误差主要来自对准误差和线宽误差。紫外衍射微透镜阵列具有均匀的焦斑分布,与紫外焦平面阵列单片集成能较好地改善器件的整体性能。     

Design and fabrication of a negative microlens array

An operation model of a negative microlens array is demonstrated. The array consists of two kinds of materials with different refractive indices. First of all, a positive microlens array with 256×256 elements serving as a pattern is fabricated by argon ion beam etching on the quartz. The diameter and average corona height of the element are 28 and 0.638 μm, respectively. The spacing between two neighboring elements is 2 μm. In the second phase, after being coated by epoxy, the positive microlens array pattern is spun and baked, leading to a complex negative microlens array. Surface stylus measurement shows that the surface of the positive quartz microlens array is smooth and uniform. Focal length measurement of the negative microlens array indicates that the focal length region with −731±3 μm is in good agreement with the theoretical calculation value of −729 μm.     

基于微透镜阵列匀束的激光二极管面阵抽运耦合系统分析

为了提升高功率固体激光器中激光二极管(LD)面阵抽运场性能,采用几何光学和数理统计分析的方法,建立了基于微透镜阵列匀束的LD面阵抽运耦合系统的数学与物理模型,对微透镜阵列参数与最终耦合输出抽运场参数之间的关系进行分析,明确了微透镜单元F数、微透镜通光单元数以及微透镜阵列空间周期参数的设计原则.经实验测试,优化设计完成的LD面阵抽运耦合系统光场不均匀度为7.9%,耦合效率为90.7%.     

光学微透镜阵列模压成形研究进展与展望

光学微透镜阵列在光学系统中的应用广泛,需求量大,而玻璃模压成形技术是最高效的微透镜阵列量产加工方法,具有精度高,一致性好,生产成本低等特点,有重要的应用研究价值。本文介绍了光学微透镜阵列的设计原理,模具制造技术,模压成形技术及相应检测技术;重点介绍了微透镜阵列模压成形试验与有限元仿真研究的最新进展;最后对微透镜模压成形发展前景进行了展望,包括微透镜阵列模压材料,模具表面镀层技术及超声复合加工技术在微透镜阵列模压成形中的应用等。     

Femtosecond laser microfabrication of periodic structures using a microlens array

A microlens array (MLA) was applied for femtosecond laser microfabrication. Two-dimensional periodic patterns that corresponded to the arrangement of lenses in the MLA were recorded by ablation on a glass surface. The two-dimensional periodic patterns were recorded by a single exposure without scanning of the laser beam or the sample, and worked as a grating. Optical resizing of the patterns and high efficiency of fabrication are demonstrated and discussed. PACS 42.82.Cr; 07.60.Pb; 42.62.Cf     

微透镜阵列误差对半导体激光匀化性能的影响

为了减小微透镜阵列误差对匀化光斑的影响,深入研究微透镜阵列光束匀化系统中微透镜阵列相对位置误差对光束匀化性能的影响,设计了一种微透镜阵列光束匀化系统。依据相对位置误差类型的不同,将双列微透镜阵列间六个自由度变化导致的误差分为距离误差、偏移误差以及转动误差进行分析,并对每种误差对光束匀化性能的影响进行了研究。采用6板条半导体激光器堆栈对上述匀化系统进行实验验证,实现了均匀性为90.75%的光斑,并对系统影响光斑性能的原因进行了分析。     

One-dimensional reflective diffuser for line beam shaper with microlens array homogenizer

A laser beam shaping architecture based on a microlens array homogenizer has been exploited, in which the interference effect due to the coherency of the laser source deteriorates the uniformity. Moving diffusers have been considered as an effective way of averaging out the interference pattern. Because the uniformity is required in the line direction only, a one-dimensional reflective-type diffuser with a well-controlled diffusion angle has been proposed and prototyped. The diffuser is attached onto a rotating cylinder for movement in operation. The experiment demonstrates the effectiveness of the scheme, and a line beam with a uniformity of up to 92% has been achieved.