Technical Challenges During the Emergence of the Laser - 1960’s

Q-Switched Ruby Laser with "Rat’s Nest" Calorimeter - 1962
Click here to view the image above in a larger format.

In the late 1950’s and early 1960’s, scientists accomplished the extraordinary feats of predicting, discovering and making the first lasers operational. Throughout the 1960s, scientists continued to lead in discovering new solid, gas and liquid materials that could be used as the active medium in lasers, providing new output wavelengths, higher energy and/or pulsed power outputs and greater efficiencies.

By 1961, electrical and mechanical engineers also joined laser R&D staffs in the development and refinement of laser systems and related equipment. We were faced with technical challenges for which we were not prepared in our education and/or prior experience. Some of the challenges we faced were:

• Engineers and physicists did not usually work together or even speak the same technical language. We learned to work in teams and to develop mutual respect for each other - because we needed each other’s unique experience and expertise.
• There were no textbooks and few journal articles about lasers; we had to learn about them as we worked on them. We were discovering new phenomena and revising existing theories.
• In the 1960’s, most engineers’ knowledge of optics was limited to what they learned in a few weeks of study in sophomore physics. Many of us had to learn more depth in geometrical optics from a book by Jenkins & White; wave (or physical) optics from a book by Strong.
• Light was traditionally measured in photometric units (lumens, foot candles, angstroms etc). We had to transition to radiometric units (joules, watts, nanometers etc).
• Safety aspects of laser beams was neither known nor respected. Laser safety became an R&D field of its own. Laser safety goggles had not been invented.
• There was no instrument used to measure the energy in an optical pulse (i.e. output of a pulsed laser.) Robert M. Baker, a Fellow Electronics Engineer at the Westinghouse Defense Center, devised and tested a “rats nest” calorimeter, composed of tens of meters of coated, fine copper wire, tangled and placed in a small beaker. The pulsed laser beam was directed into the “rats nest”; the change in electrical resistance, due to the heat rise in the copper, was measured; the temperature rise in the wire was calculated and related to the laser pulse energy absorbed by the “rats nest”.
• The physics of “negative absorption” or “optical gain” could only be understood through an understanding of modern physics and quantum mechanics. Some of us had “lightly” learned these fields in graduate studies; others had to struggle through these topics in other ways.
• Operation of solid lasers, like ruby, required fluent knowledge and facility in cryogenics and high voltage power supplies and capacitor banks. Most engineers had to learn these practices “on the job”.
• As new applications of lasers were proposed in fields such as defense, materials processing, medical therapeutics, communications, remote sensing and others, engineers were required to devise, revise and adapt equipment to accommodate laser and optical components, devices and systems.
• We learned, by mistakes, that a high power, pulsed ruby laser cannot be focused with an achromat lens without destroying the cement that joins the components of the lens together. Achromat lenses were not needed for monochromatic laser light.
• We also learned that most anti-reflective coatings, needed on gas laser tubes and the ends of solid laser rods, were also vulnerable to damage by the laser radiation. We solved this problem by positioning the end of the laser rods and the windows at Brewster’s angle to minimize reflections; thereby eliminating the need for AR coatings.

This list is far from comprehensive, but it’s what first came to mind and it’s long enough for this blog posting. Perhaps you were also working on lasers in the 1960’s. I would invite you to comment on other challenges that you faced.

Visit http://www.laserfest.org/ to learn more about the 50th anniversary celebration of the laser!

Celebrating 50 years of the Laser in 2010

A little more than 48 years ago, when I was a fledgling young electrical engineer at the Westinghouse Defense Center in Baltimore, I had a fortunate occasion that transformed my career into one of the most exciting experiences I could expect in my life. I was developing and testing some electronic timing/counting circuits for airborne radar systems; I was bored to death and wondering why I had dragged my young wife up to Baltimore from Texas to live in this “foreign land”, away from friends, relatives and Mexican food.

My engineering manager approached me just before lunch one day in June 1961, and showed me a copy of the latest issue of Scientific American magazine. He said, “Here, read this article about a helium-neon laser that had been created at Bell Labs. We want to build the second one, and I want to know if you would like to have this assignment.” I read the article, struggled through the quantum mechanics, modern physics and optics, and couldn’t imagine any practical applications for this curious device. But I also couldn’t think of anything else that I wanted to do, so I returned from lunch and responded with “why not”?

We had the HeNe lasing @ 1.153 microns (with a flat mirror Fabry-Perot etalon cavity) before the end of the year. Then we set out to build a ruby laser like Ted Maiman had demonstrated at Hughes. When we got it to operate (with a pulse energy output of about two joules), we focused the beam, with a one-inch focal length lens, on a razor blade, and blew a hole in it. Now we knew the potential application; we had the ultimate weapon to “blow ICBM’s out of the sky” and save the USA from nuclear weapon destruction! The Department of Defense also caught the laser fever; within months, R&D $$ for laser development began to flow like a river. We tried to make more powerful lasers by discovering other materials that would lase (someone even reported that they had made jello to lase.) We built ruby laser oscillator/amplifiers to raise the output power and sent them to military labs for more testing.

I not only shot more razor blades, I shot other, more exotic materials; calculated the volume of material removed and measured the impulse generated by the rapid “blow-off” at the material’s surface. In 1963 Soviet Premier Nikita Khrushchev visited the United Nations, beat his shoe on the podium, and showed a hand ruler that had a small hole in it made from a ruby laser. He declared that the USSR had the ultimate weapon that would allow them to control the world. By that time, I had determined that it might be more effective to “throw the laser at the ICBM” than it would be to try to shoot it out of the sky. Laser weapons’ research continued, and some useful devices have no doubt been developed that have made our military more efficient and our country safer.

But many more unique, useful laser applications have been developed in medicine, surgery, telecommunications, manufacturing, homeland security, lighting, displays and nanotechnology, to name a few. Lasers (today, a part of photonics) is an enabling technology that has provided new solutions to difficult problems, made our country a safer place to live and improved our quality of life. I’m so glad that I am a part of this scientific achievement. I’m an engineer and an educator; I didn’t discover the laser, but I am proud to have been part of its development; I’ve contributed to new applications; and I’ve been working for the last 35 years to build the laser (photonics) technician workforce - a critical element in this exciting and useful field.

Next year, the American Physical Society (APS), along with other sponsors, like OP-TEC, is leading a national celebration to commemorate the 50th year of the laser. This celebration is called LaserFest.

Check out the plans, information, history and opportunities to participate in LaserFest by visiting the APS web site at www.laserfest.org.

For the next several weeks I will be writing about LaserFest and some of my early memories of the emergence of the laser, including some early pioneer colleagues, technologies that had to be created/changed to support laser development, the transition from “laser systems development” to “laser applications development”, and the need/response for laser technicians.

The Photonics College Network Was Launched!

The OP-TEC Photonics College Network (OPCN) was initiated last week, at the HI-TEC Conference in Scottsdale, Arizona. Twenty-three faculty members and administrators were present, representing 18 of the nation’s 29 photonics colleges. Two additional faculty members also attended, representing two other colleges that are planning to start new photonics programs in the near future.

The OPCN met for five hours over two evenings, and accomplished the following:

• In a “networking session”, members exchanged contact information, program descriptions and student recruitment brochures.
• Members asked OP-TEC to create and maintain an OPCN community web site, open only to members, for the purpose of sharing successful strategies and engaging in discussions on issues and problems related to photonics technician education.
• Members agreed to participate in conducting Regional Needs Assessments of photonics technician job opportunities.
• Members agreed to participate in quarterly teleconferences, beginning in September 2009.
• Members requested OP-TEC to develop and conduct monthly webinars on photonics education innovations and technical updates. These 1-hour webinars will be led by OPCN members, OP-TEC center staff and technical experts. Topics will be agreed upon in the next six weeks, and the webinars will begin in the fall of 2009.

OP-TEC announced that matching mini grants would be awarded in 2009-2010, on a competitive basis, for selected OPCN members to initiate proven strategies to increase photonics student enrollment/retention at OPCN colleges.

Dr. Fred Seeber, Professor Emeritus at Camden County College, provided a seminar to the OPCN members on Laser Safety, highlighting the recently released ANSI Z136.5 Safe Use of Lasers in Educational Institutions. Copies of the new ANSI Standard were given to each OPCN member in attendance.

The following colleges were represented at the meetings: Bellingham Technical College; Camden County College; Central Carolina Community College; Central New Mexico Community College; College of Lake County; Delaware Technical College; Idaho State University (2-yr program); Indian Hills Community College; Indian River State College; Indiana University of Pennsylvania (2-yr Northpointe Campus); Irvine Valley College/CACT; Ivy Tech Community College; Monroe Community College; Northwest Vista Community College; Pima Community College; Sinclair Community College; Texas State Technical College; TriCounty Technical College; Valencia Community College; and, Wallace State Community College.

Membership in OPCN is available, without charge, to other two-year colleges offering photonics education. If you would like additional information about OPCN, please contact us at op-tec@op-tec.org.