Automatic laser welding and milling with in situ inline coherent imaging

Abstract

Received Month X, XXXX; revised Month X, XXXX; accepted Month X, XXXX; posted Month X, XXXX (Doc. ID XXXXX); published Month X, XXXX Though new affordable high power laser technologies make possible many processing applications in science and industry, depth control remains a serious technical challenge. Here we show that inline coherent imaging, with line rates up to 312 kHz and microsecond-duration capture times, is capable of directly measuring laser penetration depth in a process as violent as kWclass keyhole welding. We exploit ICI's high speed, high dynamic range and robustness to interference from other optical sources to achieve fully automatic, adaptive control of laser welding as well as ablation, achieving micron-scale sculpting in vastly different heterogeneous biological materials.

Real time monitoring of laser beam welding keyhole depth by laser interferometry

“…A Nikon DS-Fi2 camera attached to a Nikon Epiphot microscope and Nikon NIS Elements software captured micrographs of the welds. Detailed descriptions of ICI are available in the literature, [18][19][20] so only a brief discussion of the important features is given here. ICI utilises a Michelson interferometer construction with a reference and probe beam, using a superluminescent diode with a wavelength of 843 nm and FWHM of 20 nm as the light source.…”

“…For example, ICI has been used to measure the drill hole depth in ferrous alloys during laser machining, 18,19 and its application in laser welding is just beginning. 20 In this paper, the utility of ICI to provide real time measurements of keyhole depth is demonstrated in DH36 steel, 304 stainless steel, InconelH Alloy 690, Ti-6Al-4V, and 2219 aluminium alloys. A wide range of industries, including construction, energy, aerospace, and automotive, utilise and join the alloys used in this study or compositionally similar alloys.…”

Automated 3D bone ablation with 1,070 nm ytterbium‐doped fiber laser enabled by inline coherent imaging

“…A 50:50 fiber coupler connects the four sections of the system as illustrated in Figure (adapted from ref. ). The imaging light source is a superluminescent diode (SLD) with a center wavelength of 840 nm and spectral bandwidth of 25 nm (Superlum BLM‐S‐840‐G‐I‐30).…”

In situ morphology-based defect detection of selective laser melting through inline coherent imaging

“…Work by Blecher et al (2014) demonstrated the ability of ICI to measure laser keyhole depths in a range of metals, including DH36 steel, 304 stainless steel, Inconel 690, Ti-6Al-4V, and 2219 aluminum alloy. Webster et al (2014) exploited the utility of ICI for feedback control in high-power laser welding applications. Ji et al (2015) demonstrated ICI deployment through a high-speed galvanometer scanner.…”