SCIENCE AND A SYMPHONY - Artistic Laser Light Show With an Orchestral Performance of “Oscillate”

Over 200 central Texas science teachers and other educators were invited guests at a March 20 multimedia concert by the Waco Symphony Orchestra. The event was one of many LaserFest celebrations being held this year throughout the country to commemorate the 50th year of the laser, which was invented in 1960. The purpose of the LaserFest celebrations is to call attention to the many ways that lasers have enhanced our daily lives—from laser printers and copiers to digital sound reproduction and fiber optics, to mention only a few of the applications that are now commonplace.
The WSO concert featured a new composition by Jon Barrett, a Baylor University graduate student. The composition, titled “Oscillate,” was performed in conjunction with a specially designed laser light show.
Barrett’s piece was a natural match for a laser light show. Barrett composed it as a musical reflection of what he called the “never-ending ballet of patterns, interconnected and interdependent with one another, large and small.” “Our cells are born from our parents’ cells,” he noted, “and through division give rise to more cells until finally dying. Our lungs respire through a pattern of inhalation and exhalation. Our heart pumps blood through our bodies, circulating oxygen to our cells. Electrical charges constantly course throughout our nervous systems, giving us control of our bodies and a sense of the world and, ultimately, the Cosmos.” “Oscillate,” which won Baylor’s 2009 Symphony Overture Competition, is also a study in the juxtaposition of opposites—loud and soft, high and low, light and dark, fast and slow, transparent and opaque textures, serious and comical tones, and art and popular musical styles.

The laser light show, which was custom-designed as a visual interpretation of Barrett’s music, was provided by Prismatic Magic, a nationally known laser light show company. Prismatic Magic’s president, Dr. Chris Volpe, is a physicist with a specialization in optics and lasers.

Prior to the concert, OP-TEC, Texas State Technical College, Baylor University, and the City of Waco jointly hosted the guest teachers at a reception in Baylor’s new science building.


Over 100 pictures of the laser light show, as well as a 10-minute audio-video recording of the performance, can be seen on the OP-TEC website, www.op-tec.org/lasershow.

What if there were no lasers today?

When you hear the word, “laser” what are you reminded of? Luke Skywalker? Star Wars? High-tech wars between spacecraft?

Well, those concepts make good movies and TV shows, but they don’t make very good sense - in a practical way. In the last 40+ years, we have created a wide range of lasers (some whose output you can’t even see) and we’ve learned how to control them and use them to make our life better and to do things we’ve never been able to do with any other device - incredible breakthroughs in medicine, communications, manufacturing, entertainment and lots more. Unless we happen to be involved in the development of some application of the laser we probably don’t even know they are being used - right before our eyes!

Lasers now come in a variety of configurations and output wavelengths (colors), in continuous and pulsed beams, and at high and low power levels. We can often find a “laser solution” to a particular problem by selecting a laser with an output that suits our needs best. The unique properties of lasers that make them useful are:

• Monochromatic - Most lasers emit a beam of light at a very pure color (or wavelength). This means that the beam will be selectively transmitted, absorbed or reflected when other beams of light are not affected the same way.


• Collimated - A laser ray can be made to remain a very narrow beam that will travel long distances without spreading out much. A laser beam can be sent all the way to the moon and spread so little that it still makes a powerful spot when it hits something.


• A powerful Source of Heat that can be directed and pin pointed to an exact spot where it may melt or vaporize the target material, and yet leave the surrounding material unaffected.
  
• Coherent - Because laser light is much better organized than ordinary light, lasers have the same “information-carrying” properties that radio waves have, except the laser is working at much, much higher frequencies. This allows huge amounts of information, and many, many channels to be sent over a laser beam. Sometimes the laser beam is sent in the air; and sometimes it is “piped” in tiny plastic or glass strands called “fiber optics”.

So what are some common uses of lasers that we use every day? Here are a few:

Supermarket Checkout Systems
A low-power laser beam is scanned across the “bar codes” that are attached to products we buy. When we check out at a superstore, we just place the product with its bar code face down on the window of the scanner, the laser beam sweeps across the bar code and the reflected laser beam is read as a code that identifies the product. This uses the collimated and monochromatic characteristics of the laser.

LASIK Eye Surgery
LASIK (laser-assisted in situ keratomileusis) is a surgical procedure that uses a laser to correct nearsightedness, farsightedness, and/or astigmatism. In LASIK, a thin flap in the cornea is created using a femtosecond laser. The surgeon folds back the flap, and then removes some corneal tissue underneath using an excimer laser. The flap is then laid back in place, covering the area where the corneal tissue was removed. With nearsighted people, the goal of LASIK is to flatten the too-steep cornea; with farsighted people, a steeper cornea is desired. LASIK can also correct astigmatism by smoothing an irregular cornea into a more normal shape. This application uses the collimated, monochromatic and heat properties of the laser. (Unfortunately, laser pioneers are too old to be considered good candidates for LASIK.)

Laser Printers & Copiers
The physical phenomenon at work in a laser printer is static electricity, the same energy that makes clothes in the dryer stick together. A laser printer uses this phenomenon as a sort of "temporary glue" to hold toner on a photoconductive drum. The laser "writes" the print information on a photoconductive revolving drum, which then transfers it to a sheet of paper. This uses the collimated and heat properties of the laser. The information is then sealed to the paper with heat from a fuser, producing a very high-resolution copy.
(From www.howstuffworks.com/laserprinter.htm )

There are more laser applications to talk about (internet, displays, entertainment, pointers, and defense/homeland security equipment); but, those will have to wait until there’s another blog posting.

Questions or comments? Post your comments here or e-mail me!

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.