Long-term effects of pattern scan laser pan-retinal photocoagulation on diabetic retinopathy in Chinese patients: a retrospective study

●AIM:To evaluate the long-term effects of pattern scan laser(PASCAL)pan-retinal photocoagulation(PRP)on diabetic retinopathy(DR)in Chinese patients.●METHODS:In this retrospective study,we evaluated clinical data of 29 patients(53 eyes)with severe non-proliferative DR(SNPDR)or proliferative DR(PDR)who received PRP and follow-up at our hospital from 2008 to 2013.Sixteen patients(29 eyes)received PASCAL PRP and 13 patients(24 eyes)received 100-ms conventional laser PRP.●RESULTS:After long-term follow-up(mean,min-max days:719.8,290-1666 for PASCAL PRP vs 743.5,240-1348 for conventional PRP,P=0.569),patients receiving PASCAL PRP required fewer photocoagulation sessions than the conventional PRP group(2.6±1.0 vs 3.9±0.9,P<0.01).Best corrected visual acuity(BCVA)was reduced slightly in PASCAL PRP group while reduced significantly in conventional PRP group.At last visit,24 eyes in the PASCAL group(88.9%)and 21 eyes in the conventional group(91.7%)were improved or stable.Two eyes in PASCAL PRP group(7.4%)and 3 eyes in the conventional PRP group(12.5%)developed vitreous hemorrhage or vitreous fibrovascular proliferation.●CONCLUSION:PASCAL PRP is as effective and may be more conducive to maintaining visual acuity with less treatment sessions for DR treatment compared to conventional laser PRP.

Pattern Scan Laser Photocoagulator on Retinopathy: an annual clinical application summary

Purpose:To evaluate the clinical efficacy of Pattern Scan Laser Photocoagulator (PASCAL) by observing the efficacy of PASCAL on retinopathy.Methods:A total of 92 patients with retinopathy (121 eyes) who underwent PASCAL between December 2008 and February 2009 in our center were retrospectively analyzed to evaluate the visual acuity changes and recovery conditions of the patients from baseline to posterior to the treatment.The retinopathy included:diabetic retinopathy,ischemic retinal vein occlusion.(IRVO),central serous chorioretinopathy (CSC),retinal periphlebitis (Eales disease) and retinal degeneration /holes.Results:The patients were subject to a 12-month follow up after PASCAL.The visual acuity findings were stated as below:for diabetic retinopathy.(73 eyes),10 eyes had improved visual acuity;55 eyes were stabilized and 8 eyes progressed;for IRVO (13 eyes),4 eyes showed improvement,6 eyes were stabilized and 3 eyes progressed;for CSC (9 eyes),6 eyes were alleviated and 3 eyes progressed;for retinal periphlebitis (5 eyes),2 eyes had enhanced visual acuity and 3 eyes showed stable visual acuity;for retinal degeneration /holes (21 eyes),5 eyes presented improved visu-al acuity,16 eyes were stabilized and no eye progressed.Indirect ophthalmoscopic reexamination confirmed secured blockage by laser spots and favorable absorption of the retinal edema and newborn capillaries.No obvious leakage was observed during fundus fluorescein angiography and no laser-related ocular adverse effect was reported.Conclusion:PASCAL is accurate,effective and well-tolerated.The duration of short laser pulse falls within the safety range,ensuring the stabilization and improvement in the pa-tient's visual acuity.The parameters,long-term efficacy and complications of PASCAL should be further demonstrated by performing long-term clinical trials with larger sample size.

Numerical Investigation of Laser Surface Hardening of AISI 4340 Using 3D FEM Model for Thermal Analysis of Different Laser Scanning Patterns

Laser surface hardening is becoming one of the most successful heat treatment processes for improving wear and fatigue properties of steel parts. In this process, the heating system parameters and the material properties have important effects on the achieved hardened surface characteristics. The control of these variables using predictive modeling strategies leads to the desired surface properties without following the fastidious trial and error method. However, when the dimensions of the surface to be treated are larger than the cross section of the laser beam, various laser scanning patterns can be used. Due to their effects on the hardened surface properties, the attributes of the selected scanning patterns become significant variables in the process. This paper presents numerical and experimental investigations of four scanning patterns for laser surface hardening of AISI 4340 steel. The investigations are based on exhaustive modelling and simulation efforts carried out using a 3D finite element thermal analysis and structured experimental study according to Taguchi method. The temperature distribution and the hardness profile attributes are used to evaluate the effects of heating parameters and patterns design parameters on the hardened surface characteristics. This is very useful for integrating the scanning patterns’ features in an efficient predictive modeling approach. A structured experimental design combined to improved statistical analysis tools is used to assess the 3D model performance. The experiments are performed on a 3 kW Nd:Yag laser system. The modeling results exhibit a great agreement between the predicted and measured values for the hardened surface characteristics. The model evaluation reveals also its ability to provide not only accurate and robust predictions of the temperature distribution and the hardness profile as well an in-depth analysis of the effects of the process parameters.

Experimental Investigation of Laser Surface Hardening of AISI 4340 Steel Using Different Laser Scanning Patterns

Laser surface transformation hardening becomes one of the most modern processes used to improve fatigue and wear properties of steel surfaces. In this process, the material properties and the heating parameters are the factors that present the most significant effects on the hardened surface attributes. The control of these factors using predictive modeling approaches to achieve desired surface properties leads to conclusive results. However, when the dimensions of the surface to be treated are larger than the cross-section of the laser beam, various laser-scanning patterns are involved. This paper presents an experimental investigation of laser surface hardening of AISI 4340 steel using different laser scanning patterns. This investigation is based on a structured experimental design using the Taguchi method and improved statistical analysis tools. Experiments are carried out using a 3 kW Nd: YAG laser source in order to evaluate the effects of the heating parameters and patterns design parameters on the physical and geometrical characteristics of the hardened surface. Laser power, scanning speed and scanning patterns (linear, sinusoidal, triangular and trochoid) are the factors used to evaluate the hardened depth and the hardened width variations and to identify the possible relationship between these factors and the hardened zone attributes. Various statistical tools such as ANOVA, correlations analysis and response surfaces are applied in order to examine the effects of the experimental factors on the hardened surface characteristics. The results reveal that the scanning patterns do not modify the nature of the laser parameters’ effects on the hardened depth and the hardened width. But they can accentuate or reduce these effects depending on the type of the considered pattern. The results show also that the sinusoidal and the triangular patterns are relevant when a maximum hardened width with an acceptable hardened depth is desired.

基于激光雷达数据的塔里木河下游胡杨种群空间分布格局和种内竞争关系

【目的】分析胡杨种群在干旱区不同地下水埋深梯度下的空间分布格局及种内竞争强度变化,探究种群空间结构对干旱环境的响应特征。【方法】在塔里木河下游3个断面处离河道1 000 m的范围内等距离布设15个50 m×50 m天然胡杨林样地,利用地面激光雷达(TLS)获取树木三维结构数据,并通过聚集指数(R)、丛生指数(I)、点格局函数g(r)等空间分布指标以及竞争指数(CI),分析空间分布格局和种内竞争强度。【结果】1)R和I指数表明,在下游不同地下水埋深梯度下,胡杨种群空间分布格局整体上呈聚集分布。2)各样地内在0~25 m半径r距离获取的g(r)函数值分析表明,大部分样地胡杨在r<5 m距离内基本呈现聚集分布格局,在r>5 m距离呈随机分布格局。随着地下水埋深增加,树木聚集分布的距离r会缩小。3)点格局函数g_(12)(r)结果表明,不同龄级胡杨树分布格局存在差异,中龄树主要呈聚集分布,其他龄级树呈随机分布;中龄树与幼龄树、成熟树之间存在正关联性,表现出相互促进关系,而其他龄级树木之间未呈现显著关联性。4)平均CI指数随离河道距离增大呈递减趋势,单木CI随胸径增大逐渐递减。【结论】塔里木河下游胡杨种群在小尺度上呈聚集分布格局,随着尺度的增加主要呈现随机分布特征。随离河道距离增大和地下水位逐步降低,导致树木密度降低和种内平均竞争强度变弱,树木呈衰退趋势。

激光后处理实现图案化结构色调控研究

为使人工制备的结构色实现色调的精确调控,本研究以硅片为衬底,采用自组装法制备聚苯乙烯微球(PS微球)的平面六角密堆积结构,通过磁控溅射方法在其上沉积不同厚度的金薄层;再利用532nm脉冲激光后处理,研究不同扫描速度的激光后处理对结构色薄膜呈色性能的影响。结果表明:镀膜时间相同,随激光扫描速度逐渐减小,样品扫描区域颜色的变化为玫红—橙红—橙黄—黄绿—蓝绿—蓝紫,反射光谱中心波长发生蓝移;在此基础上制备了图案化的样品,发现随着观察角度增加,扫描后区域的颜色发生蓝移。

微型光机电二维扫描镜的Lissajous与Linescan扫描对比

在激光扫描显示系统(LSDs)中,MOEMS对激光束的空间调制主要分为Lissajous与Linescan两种模式。为了深入分析各模式的扫描特点,比较各模式之间的优缺,针对每种模式提出了扫描显示分辨率和轨迹均匀性这两个指标进行对比研究。按照仿真分析得出的最小像元划分方法,相同分辨率下,Lissajous模式对MOEMS快轴频率的最低要求要比Linescan模式大约高57%。另外,利用Matlab对不同MOEMS模式进行同一图像的扫描仿真,仿真结果表明,Lissajous扫描轨迹呈现出上下边缘密、中心疏的不均匀特点,而Linescan扫描轨迹则呈现出喇叭状不均匀特点。

Innovations in Retinal Laser Technology

Retinal laser photocoagulation is a proven, effective treatment for various retinal disorders, including diabetic retinopathy, retinal vein occlusions, and sickle cell retinopathy. To minimize iatrogenic retinal damage while maintaining therapeutic effects, retinal laser technology has evolved significantly since its introduction in ophthalmology more than half a century ago. These innovations have included both optimizations of laser parameters in addition to the development of novel laser delivery systems. This review summarizes recent innovations in retinal laser technology, including subthreshold micropulse laser, selective retinal therapy and nanosecond laser, innovative modes of laser delivery including pattern scanning laser, endpoint management, navigated laser, and newly described photo-mediated ultrasound therapy.

基于三维激光扫描的坡沟系统侵蚀产沙过程研究

为了探究野外自然坡沟系统土壤侵蚀过程,研究于黄土丘陵沟壑区典型流域辛店沟内自然坡面开展5场放水冲刷试验,利用地面三维激光扫描技术(Terrestrial laser scanning, TLS)获取高精度地形信息,并采用DEM of difference(DoD)地形变化监测方法计算产沙量,利用实测产沙量评估TLS的监测精度,并探讨了坡沟系统侵蚀/沉积的变化特征。结果表明:(1)累积场次中,DoD不确定性(即level of detection, LoD)平均值(范围)为16.5 mm(16.2~16.8 mm)。单场次中,LoD值平均值为16.4 mm(16.2~16.6 mm);(2)累积场次中,梁峁坡、沟谷坡、坡沟系统TLS扫描所得产沙量相对误差的平均值(范围)为52.63%(26.06%~106.98%),56.68%(30.26%~75.49%)和56.28%(33.37%~73.28%),与实测数据显著相关(R2>0.9,p<0.05)。单场次TLS扫描相对误差波动范围更大且平均值高于累积场次,其值分别为83.70%(4.08%~190.40%),91.41%(0.95%~225.09%)和87.58%(4.09%~215.55%),与实测值非显著相关(R2<0.57,p>0.05),表明TLS更适合于坡沟系统累积场次侵蚀产沙监测,而单场次监测精度较差;(3)随冲刷次数的增加,梁峁坡、沟谷坡和坡沟系统侵蚀产沙均呈增长趋势,但沟谷坡和坡沟系统沉积量快速增长后趋于平稳。(4)梁峁坡侵蚀区域主要位于梁峁坡上中部,沉积主要分布于梁峁坡中下方,沟谷坡大部分区域侵蚀剧烈,沉积主要分布于沟底,梁峁坡和沟谷坡侵蚀区占地形变化区域的比例均高于79%。结果可为黄土高原土壤侵蚀监测与机理研究提供参考。

PASCAL激光一次性全视网膜光凝治疗增殖性糖尿病视网膜病变

目的:探讨模式化激光扫描(pattern scan laser,PASCAL)激光一次性完成全视网膜光凝(pan-retinal photocoagulation,PRP)治疗增殖性糖尿病视网膜病变(proliferative diabetic retinopathy,PDR)的疗效及优势。方法:临床检查确诊的PDR患者28例42眼纳入研究。其中,视力≥0.1者36眼,<0.1者6眼;伴黄斑水肿者11眼。所有患眼均经PASCAL激光一次性完成PRP治疗。伴黄斑水肿者联合应用PASCAL单点模式和/或黄斑模式。随访时间1a,观察治疗前后视力、眼底、FFA、OCT、视野的变化情况。结果:选取的42眼患者治疗过程中均无明显疼痛不适。视力提高、稳定、下降者分别为6、28、8眼;视网膜新生血管消退18眼(43%);视网膜新生血管病灶稳定12眼(29%);视网膜新生血管病灶活动12眼(29%)。随访期间5眼(12%)因玻璃体积血行玻璃体切割手术治疗。治疗后黄斑中心凹厚度及视野平均光阈值敏感度与治疗前相比无统计学差异(P>0.05)。结论:应用PASCAL多点模式一次性完成PRP治疗PDR安全、有效、便利。

多点与单点激光治疗增殖性糖尿病视网膜病变的疗效比较（英文）

目的:观察577-nm多点激光用于新近诊断的增殖性糖尿病视网膜病变(proliferative diabetic retinopathy,PDR)行全视网膜光凝(panretinal photocoagulation,PRP)的疗效。方法:该前瞻性对照研究共纳入32例40眼PDR患者,随机分为2组,每组16例患者(20眼)。第1组采用多点激光(pattern scan laser,PSL)行PRP治疗,第2组采用单点激光(single spot laser,SSL)治疗。所有患者在PRP治疗前与最后一次PRP治疗后3mo均行荧光素眼底血管造影检查(fundus fluorescein angiography,FFA),以判断是否存在无灌注区。激光点数、完成PRP的治疗次数、治疗时长以及患者在治疗时的疼痛程度均作为判断指标。结果:PSL组患者需3次治疗以完成PRP,而SSL组需4次完成。第1组每次治疗时间为7.3±2.3min,较第2组的时间(13.2±4.1min)明显缩短(t38=5.596,P<0.01)。第1组的治疗疼痛指数较第2组明显降低(P<0.01)。最后一次PRP治疗3mo后复查FFA,第1组有5眼(25%)出现无灌注区,而第2组有8眼(40%)出现无灌注区,需要进一步治疗。结论:多点激光用于PDR行PRP治疗较单点激光有着明显的优势。它具有效率高,治疗疼痛轻,疗效好的特点。

女性黄褐斑主要中医证型与CLSM组织分型及病程的关系

目的:总结分析女性黄褐斑主要中医证型与共聚焦激光扫描显微镜(CLSM)组织分型及病程的关系,为中医辨证与治疗提供一种客观参考依据。方法:从不同病程的女性黄褐斑初诊患者中,筛选出符合黄褐斑主要中医证型辨证分型标准的患者187例,采用非创伤性CLSM技术对其进行组织分型,分析女性黄褐斑主要中医证型与CLSM组织分型及病程的关系。结果:187例女性黄褐斑患者中,CLSM组织分型分别包括表皮型122例(65.24%)和混合型65例(34.76%),无真皮型。表皮型患者以脾虚湿阻型最多(56.56%),显著高于混合型;混合型患者以肾阴不足型为主(38.46%),显著高于表皮型。所有患者平均病程为6.5年,<5年70例(37.43%),以肝气郁结型为主(68.57%);5～10年94例(50.27%),脾虚湿阻型最多(74.47%);>10年23例(12.30%),肾阴不足型最多(86.96%)。结论:女性黄褐斑主要中医证型与CLSM组织分型及病程密切相关,呈一定的规律性分布。

基于微扫描镜的激光投影(英文)

利用微机械加工技术制造出一种新型微扫描镜,结合半导体激光器,可用于投影显示.激光器发出的光束被两个分别沿着X轴、Y轴扭转的镜面相继反射,扫描出二维图形.实验测得扫描镜在15V电压,频率为扫描镜谐振频率2倍的方波信号驱动下,镜子的光学扫描角度达±12°.由于每个镜子都沿各自轴以简谐规律扭转,扫描所得投影为李萨如图形.通过分析图形的形成原理并用Matlab仿真,选出了适用用于任意图案显示的扫描镜谐振频率组合(X轴2 400Hz,Y轴2 425Hz).该组合可以形成194×192个像素点,刷新频率为25Hz.在此基础上提出了一种通过调制激光开关来进行投影显示的方法.

扫描方式对中空环形激光熔覆层残余应力及基板变形的影响研究

目的揭示激光熔覆过程基材变形演变机理,同时研究不同扫描方式对中空环形激光熔覆层残余应力分布及基材变形的影响规律,以期减小熔覆层残余应力,控制基材形变量。方法利用有限元分析软件ANSYS APDL编程语言,首先建立单道模型,探究了熔覆过程基板变形演变机理;其次建立单层多道有限元模型,模拟了6种不同扫描方式对激光熔覆层残余应力分布及基材翘曲变形的影响。基于“光束中空、光内送粉”熔覆工艺,开展了基板翘曲变形量实验研究。结果数值模拟结果表明,基板在激光熔覆起始阶段产生了背向光源的弯曲变形,随着冷却的进行,开始转变为面向光源的翘曲变形。以减小熔覆层残余应力为评价指标,获得不同扫描方式的优越性排序为:沿长边往复扫描方式>沿短边往复扫描,外螺旋式扫描>分块式扫描>内螺旋式扫描>往复扫描。从降低基板翘曲变形程度来看,不同扫描方式的优越性排列为:沿长边往复扫描方式>沿短边往复扫描,分块式扫描>内螺旋式扫描>外螺旋式扫描>往复扫描。实验测量结果表明,基板变形程度的趋势与数值模拟结果一致,验证了数值模拟的正确性。不同扫描方式下,熔覆层残余应力水平与基材翘曲变形程度基本呈正相关趋势。结论采用分块扫描方式可以显著降低熔覆层残余应力分布,改善基材翘曲变形程度,为提高中空环形激光熔覆成形质量路径规划选择提供参考。

激光刻蚀2μm铝/聚酰亚胺(PI)材料体系技术研究

目的研究对激光刻蚀图形形貌可能产生影响的几个参数,如激光功率、填充比等,优化激光束刻蚀制备2μm铝膜/PI的工作参数,提高刻蚀质量。方法利用ANSYS软件对激光刻蚀2μm铝膜/PI过程中薄膜铝表面的能量传输及转化过程进行模拟,了解刻蚀形貌与单个脉冲的激光工艺参数的关系。根据模拟结果,使用LSP2000激光器,采用不同的激光输出功率和扫描方式、填充比等参数对样品进行刻蚀。利用扫描电镜等对激光刻蚀制备后的样品表面形貌进行研究,从而获得优化工艺参数。结果采用波长为1064 nm的Nd:YAG激光器,利用蛇形扫描方式及45°方向填充,填充密度为0.03 mm,在激光功率5 W、激光频率20 kHz、脉宽100 ns、光斑直径40μm、激光扫描速度为565.7 mm/s的工艺参数下,刻蚀边界整齐。结论纳秒刻蚀过程既有光热去除,也有应力去除,激光刻蚀工艺参数的优化在一定程度上改善了刻蚀边界质量,有利于提高激光刻蚀精度。

Pascal模式扫描光凝治疗糖尿病视网膜病变的疗效观察

目的: 探讨Pattern Scan Laser(Pascal)模式扫描光凝治疗糖尿病视网膜病变的疗效观察。方法: 临床对93例186眼重度非增殖期糖尿病视网膜病变患者,治疗前后均做视力、FFA、OCT视野等相关检查。随机分治疗组48例96眼,采用Pascal模式扫描光凝一次完成全视网膜光凝治疗,同时设对照组45例90眼采用多波长氪离子常规全视网膜光凝,分4～5次治疗。结果: 治疗组视力提高总有效率为85.4%,对照组总有效率为82.2%,两组总有效率比较无统计学意义;但治疗组激光术后视野光敏感度无明显下降,而对照则显著降低,术后视功能恢复较对照组好。结论: Pascal模式扫描光凝治疗治疗糖尿病视网膜病变临床疗效优于单纯的全视网膜光凝,具有治疗后视野无明显下降、治疗时间明显缩短和疼痛感小的优点。

扫描方式对激光选区熔化成形316不锈钢性能的影响

为了揭示激光选区熔化成形过程中熔池行为,以316不锈钢粉末为对象展开激光选区熔化试验,研究了激光选区熔化成形时不同的扫描方式对成形件内部缺陷、微观组织以及室温拉伸性能的影响。结果表明:将层片分区短线扫描成形可以有效地控制成形零件内部的气孔缺陷;与无分区长线扫描相比,采用分区短线扫描后零件内部组织呈现明显的柱状且晶粒尺寸较大。

崩岗崩积体坡面糙度及其与侵蚀方式的耦合影响研究

崩岗崩积体是崩岗的主要沙源地。基于人工模拟降雨试验及三维激光扫描技术,研究崩岗崩积体坡面侵蚀过程。研究表明:利用三维激光扫描的点云数据能定量分析降雨前后坡面水蚀特征。全坡面及各坡位均为片蚀总量大于细沟侵蚀总量,但各坡位的侵蚀强度有所差异,其细沟侵蚀强度由大到小表现为下坡、中坡、上坡,片蚀强度由大到小表现为上坡、中坡、下坡。坡面空间糙度由大到小大致呈现下坡位、中坡位、上坡位,坡面侵蚀方式可影响坡面糙度值及变化趋势,而坡面糙度亦能影响各侵蚀方式的侵蚀强度。整个降雨时段内全坡面侵蚀量最大、产沙量次之,沉积量最小,受坡面糙度变化影响,全坡面侵蚀、产沙量均呈现递减趋势。而上坡位的侵蚀、产沙量无明显变化,中、下坡位的侵蚀、产沙量呈对数减小趋势。此外,除上、下坡位沉积量间存在显著差异外,各坡位间侵蚀量、产沙量均无显著差异。

MEMS摆镜在小型化激光成像雷达中的应用

研究了MEMS摆镜在未来小型化激光成像雷达的系统中的应用。首先介绍了MEMS摆镜自身的器件特性,结合脉冲成像激光雷达的应用背景,分析了系统设计时要注意的问题。进一步设计了MEMS摆镜的驱动模块,通过仿真和成像验证了李萨如扫描图形的应用。

激光图案自动变幻仪的成像分析

介绍了激光图案自动变幻仪，对旋转平面镜的反射进行了理论分析，并以此理论为基础对仪器产生的扫描轨迹成像进行了数学近似处理，并编制了图案的计算机仿真程序。