{"id":498,"date":"2021-09-06T22:00:00","date_gmt":"2021-09-06T20:00:00","guid":{"rendered":"https:\/\/www.extende.com\/blog\/ut-inspection-limits-of-acoustic-focusing\/"},"modified":"2025-06-24T18:52:17","modified_gmt":"2025-06-24T16:52:17","slug":"ut-inspection-limits-of-acoustic-focusing","status":"publish","type":"post","link":"https:\/\/www.extende.com\/fr\/blog\/ut-inspection-limits-of-acoustic-focusing\/","title":{"rendered":"UT inspection &#8211; Limits of acoustic focusing"},"content":{"rendered":"<p>Phased-Arrays sensors and systems provide a great flexibility to UT inspectors, as the ultrasonic beam can be adjusted thanks to electronic set-up to increase performances (for detection or sizing) in different situations while using the same probe. For instance, the delay laws enable to steer the beam at different angles (sector scan technique) and\/or focus the beam at different depths.<\/p>\n<\/p>\n<p><span class=\"g-color2\">However, ultrasounds remain ultrasounds!<\/span><\/p>\n<\/p>\n<p>One key rule of acoustics is that <span class=\"g-color2\">you cannot focus beyond the near field distance<\/span> (governed by the wavelength, frequency and crystal aperture)\u2026 And this remains absolutely true with phased-array sensors!<\/p>\n<\/p>\n<p>Rather than long explanations and mathematical formulas, <span class=\"g-color2\">let\u2019s use<\/span> <span class=\"g-color1\">CIVA<\/span> <span class=\"g-color2\">simulations to illustrate this!<\/span><\/p>\n<\/p>\n<p>Above, you can see the sound field sector scan coverage generated in a carbon steel block by a linear PA UT probe of 2MHz and 26 mm aperture. The first beam chart on the top left illustrates a sector scan (30\u00b0 to 60\u00b0) without any depth focusing, the max is around 50mm depth corresponding to the natural focal spot, which corresponds to the limit of the near field. Several focal laws are then successively applied to change the focal depth from 30 mm to 120 mm while keeping the same angular scanning. These focal laws lead to a geometrical focusing of the beam illustrated by the white cross, but as you can observe on the 3rd case, and above all the last case, the actual focus cannot be deeper compared to the geometrical \u201cspecification\u201d.<\/p>\n<\/p>\n<p>It just takes a few minutes to illustrate this with <span class=\"g-color1\">CIVA<\/span>,\u00a0and can avoid many misunderstandings and misuse of PA UT probes and systems!<\/p>\n<\/p>\n<p>Feel free to <a class=\"lien\" href=\"https:\/\/www.extende.com\/contact\" target=\"_self\">contact us<\/a> if you need more information about <a class=\"lien\" href=\"https:\/\/www.extende.com\/civa-ndt-simulation-software\/modules-available-in-civa\/ultrasonic-testing-with-civa\/\" target=\"_blank\" title=\"(Nouvelle fen\u00eatre)\">ultrasonic testing with CIVA<\/a>.<\/p>\n<\/p>\n<p>The <span class=\"g-color1\">EXTENDE<\/span> team.<\/p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Phased-Arrays sensors and systems provide a great flexibility to UT inspectors, as the ultrasonic beam can be adjusted thanks to electronic set-up to increase performances (for detection or sizing) in different situations while using the same probe. For instance, the delay laws enable to steer the beam at different angles (sector scan technique) and\/or focus [&hellip;]<\/p>\n","protected":false},"author":0,"featured_media":497,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[378],"tags":[],"class_list":["post-498","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-civa-software"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.extende.com\/fr\/wp-json\/wp\/v2\/posts\/498","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.extende.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.extende.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/www.extende.com\/fr\/wp-json\/wp\/v2\/comments?post=498"}],"version-history":[{"count":1,"href":"https:\/\/www.extende.com\/fr\/wp-json\/wp\/v2\/posts\/498\/revisions"}],"predecessor-version":[{"id":5771,"href":"https:\/\/www.extende.com\/fr\/wp-json\/wp\/v2\/posts\/498\/revisions\/5771"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.extende.com\/fr\/wp-json\/wp\/v2\/media\/497"}],"wp:attachment":[{"href":"https:\/\/www.extende.com\/fr\/wp-json\/wp\/v2\/media?parent=498"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.extende.com\/fr\/wp-json\/wp\/v2\/categories?post=498"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.extende.com\/fr\/wp-json\/wp\/v2\/tags?post=498"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}