Optics Is Light Work

Trip to Nashville

Tue, 19 Oct 2010 16:49:55 -0400

This past weekend we took a trip to Nashville to see an exhibit, The Beginnings of Impressionism, at the Frist Center for the Arts. The Center is housed in an amazing Art Deco building that was once the main post office for Nashville. More pictures later

Tracing Rays

Mon, 8 Feb 2010 23:43:28 -0500

Now that I have finally retired from editing Optical Engineering, I want to reëstablish this blog as a record of my thoughts and to set up a blog on photography on tour. The link to this other blog, The Touring Photographer, is at the top of the page and here.

After retiring from teaching at Georgia Tech, I returned to do one last course on ray tracing in anticipation of work on a book on optical design. Spring 2007. I circulated a notice about the course that I called Analysis of Optical Systems. It provided a short definition of ray tracing, the manipulation, interpretation, and use of optimization of optical systems, and gave a short description of the advancing technology of simulating optical systems.I was surprised by the response of the students. They thought I was going to teach them how to use powerful computers to generate realistic scenes like those that animation studios like Pixar use to create movies like Finding Nemo or Wall•E. While I realized that ray tracing techniques were used to make computer generated images (CGI), it never occurred to me to think of ray tracing that way.

For me, I became aware of ray tracing as a separate discipline when I instituted an optics track in the School of Physics at Tech in the early 1970’s. After creating a course on lasers, it became clear that an applied optics approach was needed, which included an advanced course in geometrical optics. It might have been called optical engineering, but the College of Engineering might have gotten a bit testy about such a course being taught in the School of Physics, so I called it Optical Design. There was a problem, I had never done any optical design or engineering beyond my thesis work in Raman spectroscopy.

So I signed up for a summer course, Fundamentals of Lens Design, at the Institute of Optics in Rochester. The course was taught by the chief lens designer at Kodak, Rudolph Kingslake. It was clear once the class began that he enjoyed his work in a fascinating field and shared it with anyone who was interested. I took the summer after Texas Instruments and Hewlett-Packard began their battle of programming calculators. Kingslake could not contain himself as he bounced across the front of the auditorium narrating with great glee his calculations for ray tracing through a series of lenses using one of these new marvels. After all, for those who had punched their cards and brought their offerings to the high priests of the IBM computers of that era, the invention of the programmable calculator was like the removal of shackles.

While the handheld calculator could be purchased for initial ray traces, it was difficult to do a thorough analysis with it. When the minicomputers became widely available many of the mainframe programs were converted to run on them. For a teacher in a technological institute, the transition that mattered was when the handheld calculators morphed into programmable desktop calculators with a miniature magnetic tape reader served to store programs and a paper tape printer for output. However, an HP 9815 calculator was costly, so there was only a single machine for the class. To run the ray traces for assignments, students would sign up for hour sessions to use the machine. The day before assignments were due, the students worked around the clock, sleeping under the tables of the optics lab at night.

The desktop calculator was replaced by the personal computer and student could run their own copies of ray trace programs. Around that time, Mike Harrigan, a researcher at Kodak Labs, and I wrote a series of columns with the same title as this editorial for SPIE’s Optical Engineering Reports. They were intended as a series of “five finger exercises” for those beginning in optical design. Sadly, we were not able to sustain the columns.

Now, the mainframes are not needed or wanted for lens design. A personal computer can perform the analyses and optimizations using powerful processors. Even the computational demands of CGI, that “other” ray tracing, do not require mainframes. Instead a large of number of standard personal computers running in massively parallel modes to produce a exquisitely detailed CGI for one of a half a million frames of an animated movie.

Certainly, teaching students to trace rays is easier today. They are given a CD containing the program along with a security key. They can run it on their own computer where ever and when ever they choose. Generating a blizzard of information, they can optimize a system to their heart’s content. Teaching optical design, which uses a software application is a challenge. While exploring the various aspects of design, you cannot let the students get bogged down in the details of operating the program. My approach was to give the students sufficient instruction in a number features of the program so they can use them to understand a range of optical designs. I ended with the course with a new feature in ray tracing programs, image simulation. Instead of an object consisting of line of separated points or a grid of such points, the object is a two-dimensional digital image that is imaged by the optical system. As an example of a single frame rendering, similar to CGI, this type of analysis put strong demands on the processing power of the machine and gave my physics students another appreciation of ray tracing.

How do you drive a stake into a ballet

Thu, 12 Feb 2009 20:50:38 -0500

After many years of picking one or two ballets in a season, we decided to subscribe to the current season of the Atlanta ballet. In the fall we saw Swan Lake with new (non-Petipa) choreography. We were mightily impressed by the ability of the principal dancers and the excellent work of the corps de ballet. It had been a while. What a treat!

Having seen a fantastic new production by the San Francisco ballet on PBS, we skipped the ceremonial Christmas Nutcracker and went to see the next regular production, Dracula. I think they did this once before, around Halloween, but we had never seen the production. So we came without expectations, as we might for a Tschiakovsky ballet.

The dancing was every bit as good as that in Swan Lake...as it should be. Same company. There was a live orchestra...something that had been missing in recent years because of budget shortfalls. So that was all to the good. But the ballet is itself was an underlighted, poorly written, tediously choreographed mess.

We had dinner before the ballet. Some wonderful fish and a bottle of a New Zealand sauvignon blanc. (What else? “See Desperately Seeking Hawkes Bay” Jan 15, 2009) During the first act, wherein the hero makes his way to Castle Dracula, I dozed off, perhaps because of the wine, perhaps because very little was happening on stage. During the second act, wherein a terribly scored tea dance followed by murky scene where Dracula gets a blood donation, i really didn’t care whether I was awake or asleep. By the time the third act rolled around and Vlad was finally was gonna get his comeuppance, it was getting late and I really wanted a snooze. But as a climax, during a really clunky dance of the undead in the crypt of an abbey, an explosion blows the door to the crypt open and Dracula disappears into foggy dew.

All of a sudden it became clear to me. The murky scenes, the story dealing with creatures that no one cares about, music without a single hummable tune, choreography that consists of a lot of writhing with no sense of direction or pace, ...and then the explosion! Let’s see, this production is done by a ballet company, so they don’t have the wherewithal to land a helicopter on stage or plunge a chandelier towards the audience, but they can create a really loud explosion.

The ballet needs a new audience. It must be made attractive to audiences that aren’t impressed by French-titled dance steps. It needs new blood. What is to be done. Aha! The strategy employed by Les Miz, Miss Saigon, and Phantom: the Theme Park Ballet!

My Introduction to the Ballet

Sat, 7 Feb 2009 16:02:24 -0500

I was first drawn to ballet by a review that Bob Zolnerzak, high school friend, showed me one summer Saturday morning in 1961. Earlier in the week Alla Sizova of the Kirov Ballet danced in the Kingdom of the Shades scene from Bayaderka. Bob wanted to see her dance that night. I pointed out that this was a rave review and I didn’t think there would be any tickets. Bob, having moved to New York, had figured out the city and said it would be worth a try.

We took a taxi to the old Metropolitan Opera House on Broadway. I will never forget getting out of that cab and entering the Met. There were tickets with obstructed views in the top tier of seats. We bought two and scaled the stairways to find a LARGE post in front of our seats. Bob, city smarts at work, said let’s go back down. To where? We rappelled down to the lobby and snuck into the Standing Room area behind the orchestra seats. I had a great view of fantastic performances. So much so that I never got over it.

Later, when I married Helen I introduced her to the ballet. She immediately shared my enthusiasm. We braved a strong winter storm to drive from Ohio State in Columbus to Cleveland to see Maya Plitsetskaya in the Bolshoi’s version of Swan Lake. We drove to Detroit to see Nureyev and Fontaine. When we got to Hopkins, we attended the first large performance of a major company at the Baltimore Civic Auditorium. Never having hosted a ballet, they sold peanuts until the first intermission, when they were told to stop.

When we got to Atlanta our ballet experience included both the Atlanta Ballet, supposedly the oldest American ballet company, and touring companies, particularly the American Ballet Theater. That’s where we got to Mikail Baryshnikov just after he defected to the US. The thing that struck us immediately was that not only was he a superb dancer, but he was also an excellent actor with great stage presence.

Over the years we have gone to many performances of touring companies, but our patronage of the Atlanta Ballet has been irregular. We subscribed for many years then got turned off by too much emphasis on modern dance. This year we returned as subscribers and enjoyed the first production, Swan Lake. Since we had seen the company last the performances of dancers and corps were markedly better than previous years. Last week we went to see a performance of Dracula. Oh my...!

Circling the Problem

Mon, 26 Jan 2009 15:30:47 -0500

Sometimes it looks like procrastination. Sometimes it probably is. But when a solution to a problem is not immediately obvious, I don’t dive in and worry about the consequences. Perhaps it comes from some early training in chess. As a high school student I used to walk over to meetings of the Firestone Chess Club in the cafeteria of the main plant about a mile from where I lived in Akron, Ohio. You could see it from our front porch. Everyone I played against was older than me, but I eventually won against every member except a prof from Akron U. known as “C-plus” Roberts, supposedly because that was highest grade he ever gave. Chess taught me to look ahead several moves both to simplify my approach and to the anticipate difficulties that would come my way.

Ever since I retired, I’ve been gathering materials and talking to colleagues in preparation for writing a new textbook on optical design. I considered revising my earlier text, Elements of Modern Optical Design (Wiley, 1985), but the progress in computers and lens design software since the book was published would have made it impossible. Also, with the page layout tools and publishing options now available to me, I can take intermediate steps before producing the entire textbook. For example, I can distribute sample chapters in .pdf format without having to generate the entire text as I would in the past.

So, in anticipation of my trip to Photonics West in San Jose this week, and with all my circling done, I charged through the second chapter of the new text, designing the layout on the fly, learning how to shove lens designs and graphics across our local area network between my desktop computer, where all the heavy lifting is done, and my Mac laptop, which is equipped to run CODE V™, a super nifty optical design program. So after several years of circling the problem, I have finally moved in for the kill. Well...maybe...heavy harassment.