Name: subsurface defect localization by structured heating using laser projected photothermal thermography
Uploaded: 2017-05-15T14:00:00.000+00:00
Duration: 11 min 34 s
Description: Watch this Scientific Journal Video about Subsurface Defect Localization by Structured Heating Using Laser Projected Photothermal Thermography at JoVE.com

我们要感谢Taarna Studemund和Hagen Wendler拍摄实验设备的照片，并为他们的图形出版做准备。此外，我们要感谢Anne Hildebrandt的样品准备工作，Sreedhar Unnikrishnakurup，Alexander Battig和Felix Fritzsche进行验证。

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作者没有什么可以披露的。

所提出的协议描述了如何定位垂直于表面定向的人造地下缺陷。该方法的主要思想是产生与地下缺陷相互作用的干扰热波场。最重要的步骤是（i）将SLM与二极管激光器组合，以便在样品表面产生两个交替的高功率照明图案;这些图案被光热转换成相干热波场，（ii）让它们在与地下缺陷相互作用的同时被破坏性地干扰，以及（iii）使用热成像从样品表面的动态温度的表面扫描中定位这些缺陷红外摄像机由于只需要相对的温度周围温度变化平均值而不是绝对温度值，这种方法对隐藏的缺陷非常敏感1 。 最关键的步骤之一在协议中是为了在使用SLM耦合的激光源进行结构化加热时建立足够的照明光束分布均匀性（参见步骤1.10）。二极管激光器提供高辐照度，但必须以正确的光束直径和方向性将其馈送到包含SLM的投影机中。由于投影机内专有光路的轻微不可避免的几何和频谱不匹配，样品上产生的图像失真。因此，通过参考光束轮廓测量来执行控制投影图像的图像强度值的数值校正。成功实验的第二个关键步骤是实现IR图像的高空间分辨率（参见3.3.7- 3.3.8）。耗尽区必须足够空间解决，否则不会耗尽，因此无法测量缺陷位置。 所施加的热波的性质是类似扩散的过程导致其振幅在几毫米以上的强烈衰减。我们通过使用大功率二极管激光器作为光源来满足这种固有的物理限制。当前实验装置的瓶颈是SLM 21的热应力极限，这意味着只能使用一部分可用的激光功率。我们目前的解决方案是用黑色石墨涂层涂覆样品表面。将来，我们期望使用优化的光引擎或甚至可切换的直接激光阵列（如高功率垂直腔表面发射激光器（VCSEL）阵列22 ）具有更高灵敏度的设置。 这种方法与非破坏性测试中现有热成像的主要区别在于我们使用完全相干热波场的破坏性干扰;这只有在控制一组个体li的幅度和相位之后才可能确定性的方式。在现有的热成像方法中，使用在时域中控制的平面光源或在空间域中控制的单个聚焦激光光斑。我们的方法的主要优点是对垂直于样品表面的缺陷具有高灵敏度。 到目前为止，只有两个单独的光源已经被创造出来。通过激光耦合SLM，我们原则上可以在样品表面上生成和控制高达一百万个单独的光源 - 一百万个热源。显然，这种方法开创了长期的任意热波整形的可能性，并将物理极限内的超声波或雷达传输技术转移到主动热成像领域。一旦如上所述的辐照度挑战（ 即每个投影像素的光功率）被令人满意地解决，位于更深的表面下方的更小的缺陷将变得可检测。至今，钢已被测试，但是由于施加的低热应力，该方法特别适用于塑料，复合材料和其他敏感材料。

激光投射光热法（LPPT）方法用于定位埋在试样体积中并且主要垂直于其表面定向的地下缺陷。 该方法使用了相同延伸率和频率的两个反相热波场的破坏性干扰， 如图1b所示 。在各向同性无缺陷材料中，热波通过相干叠加在对称平面上中和破坏性（ 即零温度振荡）。在具有地下缺陷的材料的情况下，该方法利用瞬态热流与该缺陷之间的横向（ 即面内）分量的相互作用。这种相互作用可以在样品表面上的对称线上以重现的振荡温度伸长率来测量。现在，通过叠加的热波场扫描含有缺陷的样品相对于样品位置测量温度伸长的水平。由于对称性，当缺陷穿过对称平面时，再次满足破坏性干扰条件;这使我们能够非常敏感地定位缺陷。此外，由于破坏性干扰的最大扰动水平与缺陷的深度相关，因此可以通过分析温度扫描1来确定其深度。 LPPT可以分配到有源热成像方法，一种已建立的非破坏性方法，其中主动产生瞬态加热，并且通过热红外相机测量所得到的瞬态温度分布。通常，该方法的灵敏度限于基本上垂直于瞬态热流定向的缺陷。此外，由于控制瞬态热传导方程是抛物线部分不同的中性方程式，进入体积的热流强烈衰减。因此，有源热成像方法的探测深度被限制在近表面区域，通常在毫米范围内。两种最常见的有源热成像技术是脉冲和锁定热成像技术。它们由于平面光学表面照明2而快速，但是导致垂直于表面的瞬时热流。因此，这些技术的灵敏度仅限于主要与加热的样品表面平行（ 例如脱层或空隙）取向的缺陷。脉冲热成像的经验规则表明，"最小可检测缺陷的半径应该比其在表面下方的深度大至少1到2倍" 3 。为了增加垂直取向的缺陷（ 如裂纹）与热流之间的有效相互作用面积，热流的方向需要改变。例如，通过使用具有线性或圆形斑点的聚焦激光器的局部激发产生具有能够有效地与垂直缺陷4,5,6,7相互作用的面内部件的热流。 在所提出的方法中，我们还使用横向热流分量来检测地下缺陷，但是我们使用热浪可以叠加的事实，而缺陷，特别是垂直取向的，可以扰乱这种叠加。以这种方式，所提出的方法类似于无参考，对称和非常敏感的方法，因为可以在远低于8,9的宽/深比下检测人造地下缺陷。到目前为止，很难建立两个提供足够能量的反相热波场。我们实现了这个b将空间光调制器（SLM）耦合到大功率二极管激光器，这使得我们能够将激光系统的高光功率与SLM的空间和时间分辨率（ 见图2 ）合并成大功率投影仪。热波场现在通过经投影图像的像素亮度的两个反相正弦调制线图案的光热转换来产生（ 见图2 ， 图1a ）。这导致样品表面的结构化加热并导致明确的破坏性干扰热波场。为了找到地下缺陷，使用红外相机测量破坏推理的干扰作为表面的温度振荡。 术语热波是有争议的，因为热波不能由于热传播的扩散特性而传输能量。不过，当hea有波浪般的行为<html>定期使用，使我们能够在实际波和扩散过程10,11,12之间使用相似之处。因此，热波可以被理解为在传播方向上高度衰减但是随时间周期性（ 图1b ）。特征热扩散长度<img alt="公式1" src="/files/ftp_upload/55733/55733eq1.jpg" />通过其材料特性（热导率k ，热容c p和密度ρ ）以及激发频率ƒ来描述。尽管热波强烈衰减，但它的波浪性质可以应用于获得样品性质的洞察力。首先应用热波干涉来确定层的厚度。与我们的方法相比，干涉效应用于深度尺寸（ 即垂直于表面）<html>参考"13。通过分割激光束将干扰思想扩展到第二维度，使用热波干涉来对地下缺陷进行调整14 ，仍然以传输方式应用该方法，这意味着它受到渗透的限制此外，由于仅使用一个激光源，该方法施加了建设性的干扰，这意味着无需参考，除了使用热波干扰的想法外，第一种技术方法是空间和Holtmann 等人使用具有内置光源的未经修改的液晶显示器（LCD）投影仪进行时间控制的加热，其光输出功率受到严格限制15.Pribe和Ravichandran的进一步接近旨在增加光学通过将激光器耦合到SLM 16来输出功率，<html> s ="xref"&gt; 17。 本文介绍的方案描述了如何应用LPPT方法来定位垂直于钢样品表面定向的地下缺陷。该方法处于早期阶段，但足够强大以验证拟议的方法;然而，在实验装置的可实现的光输出功率方面仍然受到限制。由于光输出功率的增加仍然是一个挑战，所提出的方法适用于含有人造放电加工缺口的涂层钢。然而，协议的最重要和最关键的步骤，产生均匀的结构化照明，满足破坏性热波干扰的先决条件，以及定位缺陷，仍然适用于更严格的缺陷。由于控制量是热扩散长度μ，LPPT方法也可应用于许多不同的材料。 NT"&gt; <img alt="图1" src="/files/ftp_upload/55733/55733fig1.jpg" /> 图1:破坏性干扰效应原理。 （ a ）实验中使用的照明图案的示意图。样品在空间和时间上加热了相位移π的两个周期性照明图案。虚线表示两个图案之间的对称线。这条线将用作"耗尽线"的评估。 （ b ）从热传导方程的分析解算出的空间和时间分辨的交替热结果图。它显示了对于（a）具有P opt 1 = 1.5W sin（2π0.125Hz t ）+ 1.5W和P opt 2 = 1.5W sin（2π0.125Hz t ）的两种图案的照度的响应热波+π）+ 1.5 W用于结构钢ρ 3 ， c p = 461J /（kg·K）， k = 54W /（m·K）。虚线处的温度曲线显示均匀的各向同性材料的热振荡。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55733/55733fig1large.jpg" target="_blank">请点击此处查看此图的较大版本。</a> <img alt="图2" src="/files/ftp_upload/55733/55733fig2.jpg" /> 图2:主动热成像中使用的结构化加热的测量原理示意图。将均匀化为顶帽型材的高斯光束施加到空间光调制器（SLM）。 SLM通过其可切换元件在空间上解决光束，并通过其切换速度暂时解决光束。每个元素表示SLM像素。在本实验中，SLM是数字微镜装置（DMD）。通过用时间确定性控制软件调制像素亮度A ，样品表面以结构化的方式加热。在所提出的实验的情况下，我们调制两个反相线（相位:φ= 0，π），它们是角频率ω处的相干干扰热波场的起源。波场与样品的内部结构相互作用，也影响表面的温度场。这是通过中波红外摄像机的热辐射来测量的。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55733/55733fig2large.jpg" target="_blank">请点击此处查看此图的较大版本。</a>

<table><tbody><tr><td>500 W diode laser system, 940 nm</td><td>Laserline</td><td>LDM 500 - 20</td><td>Pilot laser class 2 @ 650&amp;nbsp;nm, diode laser is a class 4 laser system --&gt; special laboratory needed</td></tr><tr><td>Laser control box</td><td>Laserline</td><td>Laser control box LDM</td><td>Add on to the laser system, used to switch electronically, laser threshold, shutter, laser on 0 V..5 V TTL</td></tr><tr><td>Control box scanner</td><td>Laserline</td><td></td><td>Add on to the laser system, used to adjust the optical output power via analog signal from 0&amp;nbsp;V..10 V</td></tr><tr><td>Fiber Laser Mount 2&quot;, f = 80 mm</td><td>Laserline</td><td></td><td>Add on to the laser system</td></tr><tr><td>Multifunction Data Aquisition (DAQ) Device + BNC Terminal</td><td>National Instruments</td><td>NI-USB 6251</td><td>The DAQ card is used to trigger the IR camera,&amp;nbsp; the DLP Light Commander 5500, control Laser and diode PDA 36A</td></tr><tr><td>Standard - PC&amp;nbsp;</td><td></td><td></td><td>Control PC - graphic card for two screens, at least 4 x USB, Windows based</td></tr><tr><td>BNC cabel</td><td></td><td></td><td>Standard cable</td></tr><tr><td>HDMI cable</td><td></td><td></td><td>Standard cable</td></tr><tr><td>Micro USB to USB cable</td><td></td><td></td><td>Standard cable</td></tr><tr><td>LabVIEW 2013 SP1 Development System</td><td>National Instruments</td><td></td><td>Development environment for device control</td></tr><tr><td>LPPT control software</td><td>BAM</td><td></td><td>part of the LPPT software package by LabVIEW 2013 SP1</td></tr><tr><td>LPPT intensity&amp;nbsp; software</td><td>BAM</td><td></td><td>part of the LPPT software package by LabVIEW 2013 SP1</td></tr><tr><td>LPPT laser control software</td><td>BAM</td><td></td><td>part of the LPPT software package by LabVIEW 2013 SP1</td></tr><tr><td>Matlab 2016b</td><td>MathWorks</td><td></td><td>Postprocessing of the measurement data</td></tr><tr><td>LPPT postprocessing software</td><td>BAM</td><td></td><td>Postprocessing of the measurement data</td></tr><tr><td>IR camera control PC</td><td>InfraTec</td><td></td><td>Control PC is supplied by camera distributor</td></tr><tr><td>IR camera control software</td><td>InfraTec</td><td>Irbis 3 Professional</td><td></td></tr><tr><td>InfraTec SDK</td><td>InfraTec</td><td></td><td>Dynamic Link Library as interface between the native data aquisition format of Infratec and Matlab</td></tr><tr><td>IR camera</td><td>InfraTec</td><td>Image IR 8300</td><td>640 x 512, cooled InSb detector, wavelength 2&amp;nbsp;&amp;micro;m..5.7 &amp;micro;m, noise = 20&amp;nbsp;mK + accessories (LAN cable, Digital in/out cable, space ring, power supply, case)</td></tr><tr><td>Tripod</td><td>Manfrotto</td><td>161MK2B</td><td></td></tr><tr><td>IR camera mount</td><td>Manfrotto</td><td>405</td><td></td></tr><tr><td>Projector development kit (PDK) for digital light processing (DLP) technology (DLP Light Commander 5500)</td><td>Logic PD</td><td>DLP-LC-DLP5500-10R</td><td>DLP5500 Digital Micromirror Device from Texas Instruments included , light engine and case need to be disassembed</td></tr><tr><td>PDK control software</td><td>Logic PD</td><td></td><td>Included when delivered, DLP Light Commander control software</td></tr><tr><td>Mechanical platform for the PDK</td><td>BAM</td><td></td><td>Self made (140 x 230 x 420) mm&lt;sup&gt;3&lt;/sup&gt;</td></tr><tr><td>Power meter control unit</td><td>Ophir</td><td>Vega</td><td>USB Interface</td></tr><tr><td>30 W power meter head&amp;nbsp;</td><td>Ophir</td><td>30(150)A-LP1-18</td><td>Power meter head to determine Transmission of the projector system</td></tr><tr><td>500 W power meter head</td><td>Ophir</td><td>FL500A</td><td>Power meter for process supervision</td></tr><tr><td>Motion controller</td><td>Newport</td><td>ESP301</td><td>with USB Interface</td></tr><tr><td>Translation stage</td><td>Newport</td><td>M-ILS200CC</td><td>Connected to ESP301</td></tr><tr><td>Photodiode with amplifier</td><td>Thorlabs</td><td>PDA 36A-EC</td><td>1&quot; mount</td></tr><tr><td>Reflective filter ND1</td><td>Thorlabs</td><td>ND10A</td><td>to be mounted to the PDA 36A</td></tr><tr><td>Pinhole 1&quot;</td><td>Thorlabs</td><td>P1000S</td><td>to be mounted to the PDA 36A</td></tr><tr><td>Optical aluminium breadboard&amp;nbsp;</td><td>Thorlabs</td><td>MB60120/M</td><td>(1,200 mm x 900 mm) base</td></tr><tr><td>Plano Convex Lens f = 200 mm</td><td>Thorlabs</td><td>LA1979-B</td><td>Coated for IR, first telescope lens</td></tr><tr><td>Plano Convex Lens f = 75 mm</td><td>Thorlabs</td><td>LA1145-B</td><td>Coated for IR, second telescope lens</td></tr><tr><td>xy-translation stage</td><td>Newport</td><td>M401</td><td>Used for adjusting the telecope</td></tr><tr><td>Beamsampler</td><td>Thorlabs</td><td>BSF20-B&amp;nbsp;</td><td>Splits the optical output, used to reduce the optical input for the projector system</td></tr><tr><td>Mirror</td><td>Thorlabs</td><td>BB2-E03</td><td>Mirror for coupling the beam to the DLP Light Commander</td></tr><tr><td>Heavy duty lab jack</td><td>Thorlabs</td><td>L490</td><td>Used for the fiber mount and on top of the linear stage to position the sample (2x)</td></tr><tr><td>PDK-objective&amp;nbsp;</td><td>Nikon</td><td>Nikon AF Nikkor 50 mm 1:1:8:D&amp;nbsp;</td><td>Objective for DLP Light Commander, 50 mm</td></tr><tr><td>Plano Convex Lens f = 100 mm</td><td>Thorlabs</td><td>LA1050 -B</td><td>Lens is attached to the Nikon Objective</td></tr><tr><td>Bi-Convex Lens f = 60&amp;nbsp;mm</td><td>Thorlabs</td><td>LB1723 -B</td><td>Lens to be attached to the Nikon objective in order to determine the optical transmission with the 30 W measurement head</td></tr><tr><td>Square protected gold mirror</td><td>Thorlabs</td><td>PFSQ20-03-M01</td><td></td></tr><tr><td>High power IR sensor card</td><td>Newport</td><td>F-IRC-HP-M</td><td>Sensor card to check the optical pathway</td></tr><tr><td>2&quot; crosshairs</td><td>BAM</td><td></td><td>Self-made</td></tr><tr><td>1&quot; crosshairs</td><td>BAM</td><td></td><td>Self-made</td></tr><tr><td>Bullseye level</td><td>Thorlabs</td><td>LCL01</td><td></td></tr><tr><td>Translation Stage</td><td>Newport</td><td>M-UMR8.25</td><td>Used for measuring the beam profile</td></tr><tr><td>Micrometer screw</td><td>Newport</td><td>DM17-25</td><td>Used with translation stage M-UMR8.25</td></tr><tr><td>Mounted Zero Aperture Iris</td><td>Thorlabs</td><td>ID75Z/M</td><td>used to check the optical pathway</td></tr><tr><td>Bases and Post Holders Essentials Kit, Metric and Universal Components</td><td>Thorlabs</td><td>ESK01/M</td><td>Basis</td></tr><tr><td>Posts &amp;amp; Accessories Essentials Kit, Metric and Universal Components</td><td>Thorlabs</td><td>ESK03/M</td><td></td></tr><tr><td>M6 Cap Screw and Hardware Kit</td><td>Thorlabs</td><td>HW-KIT2/M</td><td></td></tr><tr><td>Construction Rails</td><td>Thorlabs</td><td>XE25L700/M</td><td></td></tr><tr><td>1&quot; Construction Cube</td><td>Thorlabs</td><td>RM1G</td><td>Used to mount construction rails</td></tr><tr><td>Electrical discharge machining</td><td>Sodick</td><td>AG60L</td><td>www.sodick.de</td></tr><tr><td>St37 block of steel&lt;br /&gt;(100 x 100 x 40) mm&lt;sup&gt;3&lt;/sup&gt;</td><td>BAM</td><td></td><td>self-made, hidden defect with remaining wall thicknesses of 0.25&amp;nbsp;mm, 0.5 mm, 0.70 mm, 1.25&amp;nbsp;mm (shown in &lt;strong&gt;Figure 5&lt;/strong&gt;)</td></tr><tr><td>St37 block of steel&lt;br /&gt;(100 x 100 x 40) mm</td><td>BAM</td><td></td><td>self-made, hidden defect with remaining wall thicknesses of 1&amp;nbsp;mm, 1.5&amp;nbsp;mm, 1.75 mm, 2 mm (shown in &lt;strong&gt;Figure 5&lt;/strong&gt;)</td></tr><tr><td>Graphite spray</td><td>CRC Industries Europe NV</td><td>GRAPHIT 33</td><td>Ref. 20760, 200 mL aerosol (Kontakt-Chemie)</td></tr><tr><td>Protective tape</td><td>Tesa</td><td>tesakrepp 4348</td><td>used to protect the hidden defects while coating</td></tr></tbody></table>

subsurface defect localization by structured heating using laser projected photothermal thermography

所提出的方法用于定位垂直于表面定向的地下缺陷。为了实现这一点，我们创造了被缺陷所扰乱的破坏性的干扰热波场。测量这种效应并用于定位缺陷。我们通过使用改进的投影仪形成破坏性干扰波场。投影机的原始光引擎被替换为光纤耦合的大功率二极管激光器。其光束被成形并对齐于投影仪的空间光调制器，并通过首先表征光束轮廓而优化用于最佳光学吞吐量和均匀投影，以及第二，其机械和数字校正。根据紧凑的几何情况（包括几何图像失真的校正）和检测样品表面的弱温度振荡的要求，建立了高性能红外（IR）摄像机。数据采集​​可以执行一次同步通过使用专门的实验装置来建立各个热波场源，扫描阶段和红外相机之间的谐波，这需要调整到被调查的具体材料。在数据后处理期间，提取关于在样品表面下存在缺陷的相关信息。从获取的来自样品表面的所谓耗尽线的热辐射的振荡部分中取出。在最终步骤中，从这些振荡的空间 - 时间形状的分析中推导出缺陷的确切位置。该方法无参考，对热波场内的变化非常敏感。迄今为止，该方法已经用钢样品进行了测试，但也适用于不同的材料，特别是温度敏感材料。

按照方案，选择具有0.25mm深度的地下缺陷的钢样品的侧面1以产生代表性的结果。该缺陷最初位于照明区域的中心附近。然后将样品通过线性级以0.05mm / s的速度从-5mm移动到5mm。使用这些参数， 图11a显示了从耗尽线提取扫描数据后的扫描数据。在这个阶段，可以估计实验的成功，因为可以从IR摄像机控制软件获得原始数据作为预览（可选:使用线工具预览数据， 参见 图8 ，步骤i.4） 。进一步信号后处理后， 图11b示出了在0.3mm处的希尔伯特曲线（蓝色）的最小值处的缺陷位置。 为了验证实验，曲线应该h具有以下属性:它应该是对称的，在对称平面处具有显着的最小值，并且在其左右两个具有相等的最大值。最大值出现是因为来自一个线源的热流由于在缺陷处的热积累而在另一个之上占主导地位。当缺陷靠近对称平面定位时尤其如此。缺陷形成热流的障碍，因此我们可以观察到主导源的热流及其从缺陷的反射。如果缺陷在中间对称放置，则热流平均分开，最小值为1 。 扫描速度的影响如图11c所示。这里，将扫描速度加倍至0.1mm / s以评估相同的缺陷。之前，样品在舞台上略微移动，以获得不同的相对位置。确定缺陷位置为-2毫米。伸长水平类似于图11a所示的数据，证实了实验的良好重复性，但振荡较少。由于最大伸长率与缺陷的深度相关，所以关于位置和深度的信息也可以保持1 。 图11d显示了次优数据集。缺陷在表面以下1mm，几乎处于该扩散长度的检测极限和可用光功率。虽然仍然可以确定缺陷的位置，但是由于零振荡的位置已经受到噪声的影响，因此测量不确定性较大。从这种行为，我们可以推断，缺陷检测实验失败的最明显的迹象是如果消耗线完全消失或者存在强不对称行为。这可能是由于follo（i）红外摄像机的空间分辨率不够，耗尽线无法正确解析，（ii）相机的噪声与温升相比太高，（iii）照明模式为（iv）与照明图案的调制频率相比，所选择的舞台速度太高，（v）热扩散长度（经由调制频率）不适应于缺陷深度。 <img alt="图11" src="/files/ftp_upload/55733/55733fig11.jpg" /> 图11:实验定位地下缺陷的代表性数据集。 （ a ）来自St37样品，侧面1的代表性实验数据，其深度为0.25mm处具有缺陷。黑线显示随时间的温度信息（上轴）。通过以v = 0.05mm / s的速度平移舞台，位置是检索（底轴）。红色曲线显示用于获得交变温度分量的多项式拟合（7度）。虚线红线表示地下缺陷的位置;（ b ）黑色曲线表示从面板（a）的温度数据中减去多项式拟合得到的交变温度图。通过将黑尔伯特变换应用于黑色曲线并求平均得到蓝色曲线。 （ c ）以0.1mm / s的阶段速度在-7mm至3mm的范围内的相同侧的代表性实验数据。频率减半，但延伸率类似于图（a）。 （ d ）当地下缺陷处于1mm深度时获得的次优实验数据。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55733/55733fig11large.jpg" target="_blank">请点击此处查看此图的较大版本。</a>

Watch this Scientific Journal Video about Subsurface Defect Localization by Structured Heating Using Laser Projected Photothermal Thermography at JoVE.com

Subsurface Defect Localization by Structured Heating Using Laser Projected Photothermal Thermography

该方法旨在定位垂直的地下缺陷。在这里，我们将激光与空间光调制器耦合，并触发其视频输入，以确定性地用两个反相调制线加热样品表面，同时获得高分辨率的热图像。从评估热波干扰最小值来检索缺陷位置。

使用激光投射光热法构造加热的地下缺陷定位

The presented method is used to locate subsurface defects oriented perpendicularly to the surface. To achieve this, we create destructively interfering ...

subsurface-defect-localization-structured-heating-using-laser

Nanyang Technological University

Research

JoVE Journal

Engineering

11.0K 次观看.  Bundesanstalt für Materialforschung und -prüfung (BAM). 该方法旨在定位垂直的地下缺陷。在这里，我们将激光与空间光调制器耦合，并触发其视频输入，以确定性地用两个反相调制线加热样品表面，同时获得高分辨率的热图像。从评估热波干扰最小值来检索缺陷位置。 

视频: Subsurface Defect Localization by Structured Heating Using Laser Projected Photothermal Thermography

A Rapid Laser Probing Method Facilitates the Non-invasive and Contact-free Determination of Leaf Thermal Properties

Plants can produce valuable substances such as secondary metabolites and recombinant proteins. The purification of the latter from plant biomass can be streamlined by heat treatment (blanching). A blanching apparatus can be designed more precisely if the thermal properties of the leaves are known in detail, i.e., the specific heat capacity and thermal conductivity. The measurement of these properties is time consuming and labor intensive, and usually requires invasive methods that contact the sample directly. This can reduce the product yield and may be incompatible with containment requirements, e.g., in the context of good manufacturing practice. To address these issues, a non-invasive, contact-free method was developed that determines the specific heat capacity and thermal conductivity of an intact plant leaf in about one minute. The method involves the application of a short laser pulse of defined length and intensity to a small area of the leaf sample, causing a temperature increase that is measured using a near infrared sensor. The temperature increase is combined with known leaf properties (thickness and density) to determine the specific heat capacity. The thermal conductivity is then calculated based on the profile of the subsequent temperature decline, taking thermal radiation and convective heat transfer into account. The associated calculations and critical aspects of sample handling are discussed.

A method was developed to determine the specific heat capacity and thermal conductivity of leaf tissue by non-invasive, contact-free near infrared laser probing, which requires less than 1 min per sample.

一种快速探测激光方法有利于叶热性能的非侵入性和无接触测定

Plants can produce valuable substances such as secondary metabolites and recombinant proteins. The purification of the latter from plant biomass can be ...

科研

生物化学

Quantitative Visualization and Detection of Skin Cancer Using Dynamic Thermal Imaging

In 2010 approximately 68,720 melanomas will be diagnosed in the US alone, with around 8,650 resulting in death 1. To date, the only effective treatment for melanoma remains surgical excision, therefore, the key to extended survival is early detection 2,3. Considering the large numbers of patients diagnosed every year and the limitations in accessing specialized care quickly, the development of objective in vivo diagnostic instruments to aid the diagnosis is essential. New techniques to detect skin cancer, especially non-invasive diagnostic tools, are being explored in numerous laboratories. Along with the surgical methods, techniques such as digital photography, dermoscopy, multispectral imaging systems (MelaFind), laser-based systems (confocal scanning laser microscopy, laser doppler perfusion imaging, optical coherence tomography), ultrasound, magnetic resonance imaging, are being tested. Each technique offers unique advantages and disadvantages, many of which pose a compromise between effectiveness and accuracy versus ease of use and cost considerations. Details about these techniques and comparisons are available in the literature 4.
Infrared (IR) imaging was shown to be a useful method to diagnose the signs of certain diseases by measuring the local skin temperature. There is a large body of evidence showing that disease or deviation from normal functioning are accompanied by changes of the temperature of the body, which again affect the temperature of the skin 5,6. Accurate data about the temperature of the human body and skin can provide a wealth of information on the processes responsible for heat generation and thermoregulation, in particular the deviation from normal conditions, often caused by disease. However, IR imaging has not been widely recognized in medicine due to the premature use of the technology 7,8 several decades ago, when temperature measurement accuracy and the spatial resolution were inadequate and sophisticated image processing tools were unavailable. This situation changed dramatically in the late 1990s-2000s. Advances in IR instrumentation, implementation of digital image processing algorithms and dynamic IR imaging, which enables scientists to analyze not only the spatial, but also the temporal thermal behavior of the skin 9, allowed breakthroughs in the field.
In our research, we explore the feasibility of IR imaging, combined with theoretical and experimental studies, as a cost effective, non-invasive, in vivo optical measurement technique for tumor detection, with emphasis on the screening and early detection of melanoma 10-13. In this study, we show data obtained in a patient study in which patients that possess a pigmented lesion with a clinical indication for biopsy are selected for imaging. We compared the difference in thermal responses between healthy and malignant tissue and compared our data with biopsy results. We concluded that the increased metabolic activity of the melanoma lesion can be detected by dynamic infrared imaging.

We demonstrated that malignant pigmented lesions with increased metabolic activity generate quantifiable amounts of heat and the measurement of the transient thermal response of the skin to a cooling excitation allows quantitative identification of melanoma and other skin cancers (vs. non-proliferative nevi) at an early stage of the disease.

定量可视化和皮肤癌症使用动态热成像检测

In 2010 approximately 68,720 melanomas will be diagnosed in the US alone, with around 8,650 resulting in death 1. To date, the only effective treatment ...

医学

Investigation of Protein Recruitment to DNA Lesions Using 405 Nm Laser Micro-irradiation

The DNA Damage Response (DDR) uses a plethora of proteins to detect, signal, and repair DNA lesions. Delineating this response is critical to understand genome maintenance mechanisms. Since recruitment and exchange of proteins at lesions are highly dynamic, their study requires the ability to generate DNA damage in a rapid and spatially-delimited manner. Here, we describe procedures to locally induce DNA damage in human cells using a commonly available laser-scanning confocal microscope equipped with a 405 nm laser line. Accumulation of genome maintenance factors at laser stripes can be assessed by immunofluorescence (IF) or in real-time using proteins tagged with fluorescent reporters. Using phosphorylated histone H2A.X (&#947;-H2A.X) and Replication Protein A (RPA) as markers, the method provides sufficient resolution to discriminate locally-recruited factors from those that spread on adjacent chromatin. We further provide ImageJ-based scripts to efficiently monitor the kinetics of protein relocalization at DNA damage sites. These refinements greatly simplify the study of the DDR dynamics.

Studying DNA damage repair kinetics requires a system to induce lesions at defined sub-nuclear regions. We describe a method to create localized double-stranded breaks using a laser-scanning confocal microscope equipped with a 405 nm laser and provide automated procedures to quantify the dynamics of repair factors at these lesions.

405 Nm 激光微辐照对 DNA 损伤的蛋白质招募研究

The DNA Damage Response (DDR) uses a plethora of proteins to detect, signal, and repair DNA lesions. Delineating this response is critical to understand ...

遗传学

High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings

Micro-electronic devices often undergo significant self-heating when biased to their typical operating conditions. This paper describes a convenient optical micro-imaging technique which can be used to map and quantify such behavior. Europium thenoyltrifluoroacetonate (EuTFC) has a 612 nm luminescence line whose activation efficiency drops strongly with increasing temperature, due to T-dependent interactions between the Eu3+ ion and the organic chelating compound. This material may be readily coated on to a sample surface by thermal sublimation in vacuum. When the coating is excited with ultraviolet light (337 nm) an optical micro-image of the 612 nm luminescent response can be converted directly into a map of the sample surface temperature. This technique offers spatial resolution limited only by the microscope optics (about 1 micron) and time resolution limited by the speed of the camera employed. It offers the additional advantages of only requiring comparatively simple and non-specialized equipment, and giving a quantitative probe of sample temperature.

Europium thenoyltrifluoroacetonate (EuTFC) has an optical luminescence line at 612 nm, whose activation efficiency decreases strongly with temperature. If a sample coated with a thin film of this material is micro-imaged, the 612 nm luminescent response intensity may be converted into a direct map of sample surface temperature.

高分辨率热显微成像采用铕螯合物的荧光涂料

Micro-electronic devices often undergo significant self-heating when biased to their typical operating conditions. This paper describes a convenient ...

工程学

Custom-designed Laser-based Heating Apparatus for Triggered Release of Cisplatin from Thermosensitive Liposomes with Magnetic Resonance Image Guidance

Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect resulting in significant reductions in systemic toxicity. Nonetheless, insufficient release of encapsulated drug from liposomes has limited their clinical efficacy. Temperature-sensitive liposomes have been engineered to provide site-specific release of drug in order to overcome the problem of limited tumor drug bioavailability. Our lab has designed and developed a heat-activated thermosensitive liposome formulation of cisplatin (CDDP), known as HTLC, to provide triggered release of CDDP at solid tumors. Heat-activated delivery in vivo was achieved in murine models using a custom-built laser-based heating apparatus that provides a conformal heating pattern at the tumor site as confirmed by MR thermometry (MRT). A fiber optic temperature monitoring device was used to measure the temperature in real-time during the entire heating period with online adjustment of heat delivery by alternating the laser power. Drug delivery was optimized under magnetic resonance (MR) image guidance by co-encapsulation of an MR contrast agent (i.e.,&#160;gadoteridol) along with CDDP into the thermosensitive liposomes as a means to validate the heating protocol and to assess tumor accumulation. The heating protocol consisted of a preheating period of 5 min prior to administration of HTLC and 20 min heating post-injection. This heating protocol resulted in effective release of the encapsulated agents with the highest MR signal change observed in the heated tumor in comparison to the unheated tumor and muscle. This study demonstrated the successful application of the laser-based heating apparatus for preclinical thermosensitive liposome development and the importance of MR-guided validation of the heating protocol for optimization of drug delivery.

AN MRI-compatible&#160;custom-designed laser-based heating apparatus has been developed to provide local heating of subcutaneous tumors in order to activate release of agents from thermosensitive liposomes specifically at the tumor region.

定制设计的基于激光的加热装置顺铂触发释放的热敏脂质体与磁共振成像制导

Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect ...

生物工程

In Situ Surface Temperature Measurement in a Conveyor Belt Furnace via Inline Infrared Thermography

Measuring the surface temperature of objects that are processed in conveyor belt furnaces is an important tool in process control and quality assurance. Currently, the surface temperature of objects processed in conveyor belt furnaces is typically measured via thermocouples. However, infrared (IR) thermography presents multiple advantages compared to thermocouple measurements, as it is a contactless, real-time, and spatially resolved method. Here, as a representative proof-of-concept example, an inline thermography system is successfully installed into an IR lamp powered solar firing furnace, which is used for the contact firing process of industrial Si solar cells. This protocol describes how to install an IR camera into a conveyor belt furnace, conduct a customer correction of a factory calibrated IR camera, and perform the evaluation of spatial surface temperature distribution on a target object.

This protocol describes how to install an infrared camera into a conveyor belt furnace, conduct a customer correction of a factory calibrated IR camera, and evaluate the spatial surface temperature distribution of an object of interest. The example objects are industrial silicon solar cells.

通过内联红外热成像在输送带炉中的原点表面温度测量

Measuring the surface temperature of objects that are processed in conveyor belt furnaces is an important tool in process control and quality assurance. ...

Control of Cell Geometry through Infrared Laser Assisted Micropatterning

Micropatterning is an established technique in the cell biology community used to study connections between the morphology and function of cellular compartments while circumventing complications arising from natural cell-to-cell variations. To standardize cell shape, cells are either confined in 3D molds or controlled for adhesive geometry through adhesive islands. However, traditional micropatterning techniques based on photolithography and deep UV etching heavily depend on clean rooms or specialized equipment. Here we present an infrared laser assisted micropatterning technique (microphotopatterning) modified from Doyle et al. that can be conveniently set up with commercially available imaging systems. In this protocol, we use a Nikon A1R MP+ imaging system to generate micropatterns with micron precision through an infrared (IR) laser that ablates preset regions on poly-vinyl alcohol coated coverslips. We employ a custom script to enable automated pattern fabrication with high efficiency and accuracy in systems not equipped with a hardware autofocus. We show that this IR laser assisted micropatterning (microphotopatterning) protocol results in defined patterns to which cells attach exclusively and take on the desired shape. Furthermore, data from a large number of cells can be averaged due to the standardization of cell shape. Patterns generated with this protocol, combined with high resolution imaging and quantitative analysis, can be used for relatively high throughput screens to identify molecular players mediating the link between form and function.

The protocol presented here enables automated fabrication of micropatterns that standardizes cell shape to study cytoskeletal structures within mammalian cells. This user-friendly technique can be set up with commercially available imaging systems and does not require specialized equipment inaccessible to standard cell biology laboratories.

通过红外激光辅助微模式控制细胞几何

Micropatterning is an established technique in the cell biology community used to study connections between the morphology and function of cellular ...

Flapping Soft Fin Deformation Modeling using Planar Laser-Induced Fluorescence Imaging

Propulsive mechanisms inspired by the fins of various fish species have been increasingly researched, given their potential for improved maneuvering and stealth capabilities in unmanned vehicle systems. Soft materials used in the membranes of these fin mechanisms have proven effective at increasing thrust and efficiency compared with more rigid structures, but it is essential to measure and model the deformations in these soft membranes accurately. This study presents a workflow for characterizing the time-dependent shape deformation of flexible underwater flapping fins using planar laser-induced fluorescence (PLIF). Pigmented polydimethylsiloxane fin membranes with varying stiffnesses (0.38 MPa and 0.82 MPa) are fabricated and mounted to an assembly for actuation in two degrees of freedom: pitch and roll. PLIF images are acquired across a range of spanwise planes, processed to obtain fin deformation profiles, and combined to reconstruct time-varying 3D deformed fin shapes. The data are then used to provide high-fidelity validation for fluid-structure interaction simulations and improve the understanding of the performance of these complex propulsion systems.

The present protocol involves the measurement and characterization of 3D shape deformation in underwater flapping fins built with polydimethylsiloxane (PDMS) materials. Accurate reconstruction of these deformations is essential for understanding the propulsive performance of compliant flapping fins.

基于平面激光诱导荧光成像的拍打软鳍变形建模

Propulsive mechanisms inspired by the fins of various fish species have been increasingly researched, given their potential for improved maneuvering and ...

Continuous-wave Thulium Laser for Heating Cultured Cells to Investigate Cellular Thermal Effects

An original method to heat cultured cells using a 1.94 &#181;m continuous-wave thulium laser for biological assessment is introduced here. Thulium laser radiation is strongly absorbed by water, and the cells at the bottom of the culture dish are heated through thermal diffusion. A laser fiber with a diameter of 365 &#181;m is set about 12 cm above the culture dish, without any optics, such that the laser beam diameter is almost equivalent to the inner diameter of the culture dish (30 mm). By keeping a consistent amount of culture medium in each experiment, it is possible to irradiate the cells with a highly reproducible temperature increase.
To calibrate the temperature increase and its distribution in one cell culture dish for each power setting, the temperature was measured during 10 s of irradiation at different positions and at the cellular level. The temperature distribution was represented using a mathematical graphics software program, and its pattern across the culture dish was in Gaussian form. After laser irradiation, different biological experiments could be performed to assess temperature-dependent cell responses. In this manuscript, viability staining (i.e., distinguishing live, apoptotic, and dead cells) is introduced to help determine the threshold temperatures for cell apoptosis and death after different points in time.
The advantages of this method are the preciseness of the temperature and the time of heating, as well as its high efficiency in heating cells in a whole cell culture dish. Furthermore, it allows for study with a wide variety of temperatures and time durations, which can be well-controlled by a computerized operating system.

An original experimental setup for heating cells in a culture dish using 1.94 &#181;m continuous-wave laser radiation is introduced here. Using this method, the biological responses of retinal pigment epithelial (RPE) cells after different thermal exposures can be investigated.

连续波ium激光加热培养细胞以研究细胞热效应

An original method to heat cultured cells using a 1.94 &#181;m continuous-wave thulium laser for biological assessment is introduced here. Thulium laser ...

生物学

激光诱导的热塑性等离子体穿刺用于质膜修复研究

A Thermoplasmonic Approach for Investigating Plasma Membrane Repair in Living Cells and Model Membranes

The cell membrane is crucial for cell survival, and ensuring its integrity is essential as the cell experiences injuries throughout its entire life cycle. To prevent damage to the membrane, cells have developed efficient plasma membrane repair mechanisms. These&#160;repair mechanisms can be studied by combining confocal microscopy and nanoscale thermoplasmonics to identify and investigate the role of key proteins, such as annexins, involved in surface repair in living cells and membrane model systems.
The puncturing method employs a laser to induce highly localized heating upon nanoparticle irradiation. The use of near-infrared light minimizes phototoxicity in the biological sample, while the majority of the absorption takes place in the near-infrared resonant plasmonic nanoparticle. This thermoplasmonic method has been exploited for potential photothermal and biophysical research to enhance the understanding of intracellular mechanisms and cellular responses through vesicle and cell fusion studies. The approach has shown to be complementary to existing methods for membrane disruption, such as mechanically, chemically, or optically induced injuries, and provides a high level of control by inflicting extremely localized injuries. The extent of the injury is limited to the vicinity of the spherical nanoparticle, and no detrimental damage occurs along the beam path as opposed to pulsed lasers using different wavelengths. Despite certain limitations, such as the formation of nanobubbles, the thermoplasmonic method offers a unique tool for investigating cellular responses in plasma membrane repair in an almost native environment without compromising cell viability.
When integrated with confocal microscopy, the puncturing method can provide a mechanistic understanding of membrane dynamics in model membrane systems as well as quantitative information on protein responses to membrane damage, including protein recruitment and their biophysical function. Overall, the application of this method to reduced model systems can enhance our understanding of the intricate plasma membrane repair machinery in living cells.

作者聚焦：用创新的热等离子体穿刺探索质膜修复机制 

The thermoplasmonic puncture method integrates confocal microscopy, optical tweezers, and gold nanoparticles to study protein responses during plasma membrane repair in cells and giant unilamellar vesicles. The technique enables rapid and localized membrane puncture, allowing the identification of key proteins and their functional roles in the intricate plasma membrane repair machinery.

一种用于研究活细胞和模型膜中质膜修复的热等离子体方法

The cell membrane is crucial for cell survival, and ensuring its integrity is essential as the cell experiences injuries throughout its entire life cycle. ...