The scientific life of Jyoti started with a fact: The invention of an optical beam of sufficient power to be useful in manufacturing and a question: what to do with it? He became involved in developing laser cutting and welding and saw these processes change from being considered avant-garde, exotic, expensive, or even dangerous to becoming accepted high quality processes. He played a part in pioneering many novel processes using lasers from simple marking to the production of nanoparticles. As this tribute shows he played a major role in transforming manufacturing by developing additive manufacturing with his pioneering scientific studies on laser cladding. This is a fundamental transformation, not a flash in the pan of fashion. Manufacturing will not be the same again. His too early death is a great loss to all working in this subject as well as his many friends.

The subject of laser material processing owes much to Jyoti. He was always searching for the next development and he had the talent to exploit it when he found it. From his 400 or so publications one can see a genius at work. His mathematical models became so sophisticated they could replicate the waves on a weld pool and inside the keyhole. A far cry from where we started in 1980 at the Imperial College in London, England. He was one of the pioneers to recognize that the laser could produce nanoparticles through ablation at a time when no one thought nanoparticles would lead to so much. Then came laser cladding and the realization that cladding repeatedly in one place could build features leading to the subject of additive manufacturing.

He remained a serious scientist to the end. In the recent 2020 ICALEO virtual conference he proposed a new method for monitoring a laser weld from the spectrum of the plasma. In an email to Steen later he stated, “The Mechanical property and plasma relationship concept came from the simple thought that if hardness is proportional to resistance to deformation, then there should be similarity with plasma formation too. If the atom does not want to move sidewise, it will not like to vaporize either. After doing some proof-of-concept experiments, I started getting deeper into it. Plasma behavior is described using Quantum mechanics whereas mechanical properties are described using classical mechanics. I dream and hope that one day, I can develop a simple equation for transition from quantum to classical mechanics.” Email to WMS in Oct 2020.

Professor Mazumder leaves behind an extraordinary history of excellence with numerous awards and achievements. In addition to receiving the prestigious Arthur Schawlow award from LIA, he was the recipient of many other awards. To name just a few, he was an elected member of the USA National Academy of Engineering, Foreign Fellow of the Indian National Academy of Engineering, William T. Ennor Award for manufacturing, Thomas A. Edison Patent Award, and the Distinguished University Innovator Award from the UM. He co-authored two books, Theory and Application of Laser Chemical Vapor Deposition, and Laser Materials Processing. While pursuing academic excellence in the field of Direct Metal Deposition (DMD) technology, he also demonstrated entrepreneurial skill by establishing a company for commercializing the DMD technology.

Professor Mazumder was an excellent teacher. He educated and trained many students who are now well-established faculty members in various universities, accomplished professionals in different industries, or meticulous scientists in Government laboratories. He leaves behind a legacy of bright scientists and engineers throughout the world carrying on his teachings and research principles. He touched the lives of many and will be dearly missed. His spirit and legacy, however, will remain alive. We hope this special edition of JLA will benefit many generations to come.

William M. Steen and Aravinda Kar

His friend and Ph.D. supervisor. His friend and post-doctoral student

The authors have no conflicts to disclose.

William M. Steen: Writing – review & editing (equal). Aravinda Kar: Writing – review & editing (equal).