Abstract
Industrial processes involving thermal plasma such as cutting, welding, laser machining with ultra-short laser pulses (nonequilibrium conditions), high temperature melting using electrical discharge or ion-beams, etc., generate non-repeatable fast transient events which can reveal valuable information about the processes. In such industrial environments containing high temperature and radiation, it is often difficult to install conventional lens-based imaging windows and components to observe such events. In this study, we compare imaging requirements and performances with invasive and non-invasive modes when a fast transient event is occluded by a metal window consisting of numerous holes punched through it. Simulation studies were carried out for metal windows with different types of patterns, reconstructed for both invasive and non-invasive modes and compared. Sparks were generated by rapid electrical discharge behind a metal window consisting of thousands of punched through-holes and the time sequence was recorded using a high-speed camera. The time sequence was reconstructed with and without the spatio-spectral point spread functions and compared. Commented MATLAB codes are provided for both invasive and non-invasive modes of reconstruction.
Highlights
Imaging through occlusion such as mist, fog, or a scattering medium is a challenging task [1,2,3]
Techniques which utilize the information of the imaging configuration such as the point spread function (PSF), scattering matrix, and distances are categorized as invasive since additional information related to the scattering media is needed [4]
In many industrial processors, the above is not possible where the occlusion is welded on to the system and the space beyond the occlusion is not accessible. This invasive procedure is especially not safe in biomedical applications where the surface of an organ or tissue is occluded by the skin
Summary
Imaging through occlusion such as mist, fog, or a scattering medium is a challenging task [1,2,3]. There has been numerous research works on non-invasive approaches and the method has been successfully extended to obtain an additional dimension—depth [9,10,11]. Another major difference between invasive and non-invasive approaches is that with invasive methods, it is possible to reconstruct the object information as close as possible to reality, with higher signal to noise ratio (SNR), optimal resolution and field of view. The non-invasive approach relies on an initial guess (random matrix) which controls the degree of convergence, necessitating several initial guess cases in [6], that were tried until an optimal reconstruction was obtained. Supplementary files consisting of original MATLAB code with comments are provided for a freshman in this area of research
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
