水下连续激光成像的图像退化模型

水下环境中的介质和悬浮颗粒产生了光散射现象,导致水下激光图像存在严重的图像退化问题,大大降低了目标图像的信噪比。本文通过对水下连续激光成像光路图的分析,推导由于前向散射和后向散射而产生的图像退化模型。     

谐振腔长对薄板不锈钢焊接工艺的影响

通过研究YAG激光器谐振腔腔长与光束质量的关系,优化设计谐振腔腔长,得到了良好的激光光束质量。当激光器腔长L=766mm时,激光的光束质量最好,高斯分布均匀,对薄板不锈钢进行穿透焊接工艺试验,此腔长的焊接效果最好。     

脉冲激光导致不锈钢表层温度场演化的模拟

采用焓方法对Nd:YAG脉冲激光导致的不锈钢材料表面熔凝过程的温度场进行了数值模拟。在此基础上,结合材料的结晶动力学和快速凝固理论,对材料微结构演化的几个重要参数,包括凝固速率、冷却速度和界面温度梯度做了估算和讨论。     

振镜式激光加工的轨迹预览及监控

振镜式激光加工的轨迹坐标与屏幕坐标不同,需要进行坐标变换才能使振镜运动轨迹在计算机屏幕中正确显示。在Visual Studio 2008环境中针对LMC-2型激光打标卡,提出了坐标系转换和图形缩放的具体方法,实现了轨迹预览和实时监控。     

基于手持式激光扫描的反求设计实验

提出了基于手持式激光扫描的反求设计实验课程,给出了实施方案.通过研究与实践证明,学生通过Handyscan手持式激光扫描仪以及Geomagic反求建模软件平台,对产品模型进行数据采集、CAD模型重构及反求创新设计,不仅能够了解产品的快速设计开发流程与技术,而且有利于强化学生工程设计与实践能力,引导学生进行创新设计探索.     

多媒体投影伴侣

为改变教师在多媒体教学过程中站在控制台前一边控制计算机,一边讲授课程,与学生之间缺乏交流的现状,设计多媒体投影伴侣,它由图像采集装置、红外激光笔和图像处理软件组成。教师能够利用手中的红外激光笔远距离的控制投影屏幕的显示内容,对屏幕进行单击、双击、右键等类似鼠标的操作。相比于无线鼠标,它无需移动的平面;相比于普通激光笔,它增加了控制投影屏幕显示的功能。     

窄线宽36pm的Er：Yb共掺硅基光纤激光器

实现了一个窄线宽36pm的Er：Yb共掺硅基光纤激光器,输出中心波长是1569．4nm.激光器的谐振腔是由一个高反的Bragg光纤光栅和另一端光纤端面4％的菲涅尔反射组成．用3．8m长的Er：Yb共掺光纤,在975m的LD激光器泵浦下,获得了最大输出功率达到6W,斜率效率达到23．5％,在输出功率范围内有明显的功率饱和现象．     

LISST-100X现场激光粒度分析仪体积转换常数的计算方法

激光粒度仪是施测泥沙颗粒级配分布的设备,在施测过程中以测试水体中悬浮物来确定泥沙颗粒级配的分布,并通过体积转换常数来计算含沙量。本文就LISST-100x现场激光粒度分析仪“泥沙体积转换常数”的计算方法进行分析探讨,以确定最优值的选择方法。     

Correlation between process parameters and primary dendrite arm spacing in laser welding of Cu and Al

A combined numerical model of thermal field and the primary dendrite arm spacing （PDAS） was proposed to correlate the process parameters and PDAS in laser welding of Cu and A1. The solidification parameters simulated by the finite volume method with commercial software ANASYS FLUENT were applied in the PDAS model to predict the dendrite arm spacing of fusion zone. Dendrite was also examined by the metallographic method to validate the model. Results indicate that the calculated PDAS agrees with metallographic measurements reasonably, especially the Hunt model. PDAS increases apparently with increasing laser power while decreases slightly with increasing welding speed. Increasing laser power increases the secondary dendrite and increasing welding speed increases the microporosity in dendrite.     

Flexible Calibration Method for 3D Laser Scanner System简

In this paper, a flexible high-precision calibration method suitable for industrial field was proposed. The complexity of the coordinate transformation was simplified by choosing the camera coordinate system as the unified reference coordinate system. A flexible planar calibration pattern was introduced to the calibration process, which can be arbitrarily placed and from which the known feature points can be extracted to construct other unknown feature points. With the known intrinsic parameters, the laser projector plane equation was fitted by the multi-noncollinear points, which were acquired through the principle of triangulation and the projective invariance of cross ratio. With this method, the strict alignment and multiple times of coordinate transformation can be avoided. Experimental results showed that the arithmetic mean of the root mean square （RMS） error of distance was 0.000 7 mm.