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Optical Design & Engineering

Imagining the infrared

Max Riedl's passion for his work keeps him active in IR systems.

From oemagazine December 2001
30 December 2001, SPIE Newsroom. DOI: 10.1117/2.5200112.0011

Max Riedl with his grandchildren, Stephanie and Bryan, in San Francisco.

First impressions of Max Riedl are that he is passionate about his work, always looks to the next project, and constantly uses his imagination. Riedl is an SPIE Fellow, author, and teacher. "I do have a very vivid imagination and like to work with people, not as a manager, but as a leader," Riedl says. "I think you lead people and manage inventory." A longer look at his career shows these first impressions to be true.

As passionate about infrared (IR) systems and lens design as Riedl is, it is surprising that he originally planned on a career in precision mechanics. "I never had any idea that I would wind up in optics," says Riedl.

In 1940, Riedl began an apprenticeship in Precision Mechanics (Feinmechanik) at the Mathematical-Mechanical Institute in Kempten, Germany, where he was born. There he helped build planimeters, integrimeters, harmonic analyzers, and other high-precision mathematical apparatus. "Remember that was before even the transistor was invented," says Riedl.

After World War II, Riedl studied in Munich at the Oskar von Miller Polytechnikum, the Akademie für angewandte Technik (Academy for Applied Science). Although Riedl intended to study precision mechanics, the academy only offered a combined precision mechanics and optics program. Riedl graduated four years later in June 1951.

Two years later Riedl was married, and he and his wife, Hermine, moved to the United States. "Our plan was to stay a year or two," says Riedl. "It became a rewarding 45 years, and we are very proud having had that experience. The United States became our homeland. We became U.S. citizens at the first opportunity on Christmas Eve 1958 in Chicago, where we resided and earned our first dollar."

During the 1960s Riedl worked with Werner von Braun's team and then joined Infrared Industries in Santa Barbara, CA, where his experience with IR optics and systems began. "I started my real optical life when I moved to Santa Barbara," says Riedl. His first projects included optical pyrometers, radiometers, and a medical scanner using an indium antimonide (InSb) detector.

Riedl says the highlight of his career as an engineer was working with a team from MIT/Lincoln Laboratories (Cambridge, MA). He developed, built, and field-tested several airborne IR systems for the Pacific Range Electromagnetic Signature Study (PRESS) project. During this time he worked with Warren Smith and Lowell Baskins. "I was the opto-mechanical systems designer and integrator and soaked up all I could from those two very gifted individuals," says Riedl.

In the early 1970s, Riedl received patents for an automotive IR analyzer and other non-dispersive IR devices. "With the development and refinements of diamond turning, a new door was opened," he says. He recognized the possibility of generating not only aspheric surfaces with this technology but also diffractive phase profiles. Following that line of thinking, he designed and built an IR imaging system using hybrid optics, which led to Riedl being awarded the prestigious Photonics Circle of Excellence Award in 1991.

Along with holding many business and technical leadership positions, Riedl also has played the role of teacher. For many years, he had held company-sponsored seminars in basic optics and predesign of IR systems. In the 1980s, he began teaching short courses and eventually formed his notes into a tutorial text titled Optical Design Fundamentals for Infrared Systems, now in its second edition from SPIE Press. "I don't learn things easily, but I am stubborn, and when I see the light, I am happy and want to share my findings with simple explanations and examples with others in the hope to make life easier for them and to show them how beautiful the world is."

He says that before analyzing, you must create something first. "So, I just say: 'At the beginning there is the centerline.' Start wrapping the optics around, beginning with the simplest element and expand until you have found the 'acceptable approximation.'" Riedl stresses the fundamentals when teaching. "I have so much fun. I always tell my students you can't have fundamental without having mental fun."

Riedl maintains "there is no end to IR applications." He would like to see more done with reflective optics, especially injection-molded aspheric systems. Possibilities he sees for applications are automobile braking systems and parking aids. "An interesting one would be to trigger a ventilation system in restrooms when the methane level exceeds a set level," says Riedl. "You see my imagination is still working!"

Now living in Bavaria, Riedl enjoys daily walks through nearby forests and trips to the Alps with Hermine. They visit their daughter, Renee Van Fleet, her husband, Jim, and their two grandchildren, Bryan, 13, and Stephanie, 9, in Los Angeles, CA, as often as they can. "Our grandchildren are very special to us," says Riedl. "Of course, as the saying goes, 'Grandchildren and ideas are the same: Your own are the greatest.'"

Although he's retired, Riedl keeps very busy. He is currently working on a German translation of his tutorial text, and if the book is well received, he has visions of a video to accompany the book. In addition, he gives tutorials and continues to write manuscripts, among other projects.

Riedl shows no signs of slowing down soon. "I live to work and don't work to live," he says. "Luckily, my work is my hobby. So why give up a hobby?"

Erin M. Schadt

Erin M. Schadt is an SPIE staff editor.