[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-503563-105":59,"doc-detail-503563-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","contact-free-detection-and-visualization-of-guided-waves-in-composites-using-an-optical-microphone","Contact-free detection and visualization of guided waves in composites using an optical microphone","","With the increasing use of carbon fiber reinforced polymers in modern aircraft, internal damage such as delaminations creates a growing need for advanced nondestructive ultrasonic inspection. Guided ultrasound waves offer long-range propagation and strong sensitivity to internal defects, but common contactless laser-doppler vibrometry depends on surface reflectivity. This work applies a laser-based optical microphone to detect and visualize guided waves contact-free, supported by robot-based sampling, signal processing, defect validation, and scalability toward curved structures.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/contact-free-detection-and-visualization-of-guided-waves-in-composites-using-an-optical-microphone/503563/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/contact-free-detection-and-visualization-of-guided-waves-in-composites-using-an-optical-microphone/503563.png","ImageObject",300,407,{"name":92,"@type":93},"Muffet","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-07","2026-10-03",true,{"@type":102,"interactionType":103,"userInteractionCount":14},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"Why are guided ultrasound waves suitable for aircraft composite maintenance?","Question",{"text":112,"@type":113},"They propagate over long distances and remain highly sensitive to internal defects, making them useful for inspecting large thin-walled structures and detecting subsurface damage.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"What limitation affects laser-based contactless detection methods?",{"text":117,"@type":113},"Their signal quality depends strongly on surface reflective properties, which can fail under maintenance conditions with dirty or low-reflectivity surfaces.",{"name":119,"@type":110,"acceptedAnswer":120},"How does the optical microphone approach improve contact-free detection?",{"text":121,"@type":113},"It detects and visualizes guided waves with very high bandwidth while remaining independent from surface reflectivity, enabling robust measurements on composite plates.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},503563,1791345640,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":14,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":139,"language":140,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":67,"update_tm":144,"read_time":145},962090768927,"https://ap-avatar.wpscdn.com/davatar_085a072bc5b1113ac321206ff7593b45","Contact-free detection and visualization of guided waves in composites  \nusing an optical microphone  \nCaspar Wasle*, Florian Heilemann**, Björn Wohltmann, Rebecca Rodeck, Gerko Wende German Aerospace Center (DLR), Hein-Saß-Weg 22, 21129 Hamburg  \nABSTRACT  \nWith increasing adoption of carbon fiber reinforced polymers in modern aircraft, new challenges in the maintenance of these structures arise. These materials are prone to internal damages such as delaminations, necessitating advanced nondestructive testing methods like ultrasonic testing. Guided ultrasound waves are a promising solution for testing large thinwalled structures like aircraft fuselages due to their long propagation range and high sensitivity to internal damage. However, traditional methods like laser-doppler vibrometry, while effective, are limited by their reliance on surface reflective properties, restricting their applicability in real-world maintenance scenarios. In this paper, a laser-based optical microphone is used to detect and visualize guided waves in carbon fiber reinforced polymer materials, featuring a very high bandwidth and independence from surface reflectivity. A robot test setup is developed to sample areas on the plate through repeated experiments. Signal processing enables the analysis of the wavefield and the visualization as twodimensional wavefield images. By introducing defects into the plate, it is shown that these can be detected by changes in wave propagation patterns. With the flexible test setup using a robotic arm, the scalability of this approach to more complex structures with curvatures is demonstrated, highlighting its relevance for future use in aircraft maintenance.  \nKeywords: Contactless ultrasound, Optical microphone, Guided waves, Lamb waves, Maintenance, Robotics  \n1. INTRODUCTION  \nThe use of Carbon Fiber Reinforced Polymers (CFRPs) in the aerospace industry has seen a remarkable increase over the past few decades. For instance, the usage ofCFRPs in airframe and primary structures of commercial aircraft from Airbus and Boeing has increased from about 10% in 1990 to about 50% in 2015 in long-range models [1] . These composite materials are used due to their good performance in strength-to-weight ratio and design flexibility, making aircraft lighter and enabling higher fuel efficiency. Studies show that the usage of CFRPs in commercial aircraft has a technical CO2 emission reduction potential of 20-25%[2] . For this reason, it is anticipated that future, more sustainable, aircraft generations will consist in large parts of composite materials. However, in contrast to traditional metal materials like aluminium, CFRPs have different damage mechanisms and therefore produce different damage patterns. In metal materials, a predominant failure mechanism is crack propagation due to stress concentration, where cracks initiate from the material surface. Composite materials, in contrast, are prone to delamination and matrix cracking, which are usually internal and harder to detect using traditional methods. The widespread use of composite materials therefore necessitates more advanced inspection methods capable of detecting internal defects [3] .  \nWith its ability to image the internal structure of carbon fiber composites at a reasonable cost, ultrasonic testing has become the procedure of primary choice for nondestructive testing in many applications [4] . Various techniques of ultrasonic testing exist, utilizing different ultrasound wave types and physical properties of these waves. Typically, an ultrasonic test setup consists of an excitation source for generating ultrasound waves in the structure and a receiver for detecting the resulting waves. A coupling medium such as water or gel is normally required to facilitate efficient and predictable transmission of ultrasound into the test material and to the receiver [5] . This approach, however, comes with its downsidesas it is very hard to automate without submerging the test m","cbCaikOeRau8n6sG","https://ap.wps.com/l/cbCaikOeRau8n6sG","pdf",936473,11,"English","# Abstract\n# Introduction\n## Motivation: CFRP damage and inspection needs\n## Ultrasonic testing and coupling limitations\n## Contactless ultrasonics and guided-wave detection","[{\"question\":\"Why are guided ultrasound waves suitable for aircraft composite maintenance?\",\"answer\":\"They propagate over long distances and remain highly sensitive to internal defects, making them useful for inspecting large thin-walled structures and detecting subsurface damage.\"},{\"question\":\"What limitation affects laser-based contactless detection methods?\",\"answer\":\"Their signal quality depends strongly on surface reflective properties, which can fail under maintenance conditions with dirty or low-reflectivity surfaces.\"},{\"question\":\"How does the optical microphone approach improve contact-free detection?\",\"answer\":\"It detects and visualizes guided waves with very high bandwidth while remaining independent from surface reflectivity, enabling robust measurements on composite plates.\"}]","Contact-free detection and visualization of guided waves in composites using an optical microphone | PDF",1791058318,28]