The introduction of high-brightness (HB) LEDs in everything from automobiles to signage to hand-held torches, and a need for end-to-end design, illumination, and propagation packages, is helping to drive optical engineering environments to new levels of integration.
"We sell into cyclical markets, but there's a tremendous amount of work going into anything to do with LEDs," explains Michael Thomas, president of optical engineering firm Optical Product Development Inc. (OPD; Lexington, MA). "It's everywhere: headlight designs, projection systems, and backlight design - anything with a light source, people are putting LEDs into it. Everything that was designed before is being designed again with LEDs."
Valued at just under $2 billion in 2002, the HB-LED market was estimated at just under $4 billion worldwide in 2004, growing at nearly 50% per year, according to market analyst firm Strategies Unlimited (Mountain View, CA). By comparison, the U.S. medical imaging market, of which optical systems are only one part, was estimated at $6.7 billion in 2004, according to market research firm Business Communications Company Inc. (Norwalk, CT), and is expected to grow only 5.7%.
The benefits of solid-state lighting - low electrical consumption, long lifetime, reduced heat generation - make this source extremely attractive to illumination and imaging system designers; however, the "newness" of these components, with their higher acquisition price, has slowed their deployment in some application areas. While today's high-volume production is driving prices down, LED suppliers are easing this illumination revolution by making source designs and characterization data directly available to optical engineers. "In the near future, an optical engineer is going to be able to contact any major LED supplier and get a free catalogue of ray data to make it easier to incorporate light sources into optical designs," predicts OPD's Thomas. "Right now, you have to make approximations or have someone else characterize the source at your own expense. The ability to download source characteristics will be a huge time saver." End-to-End Design Solutions
Design software is also changing for the better, following larger software trends based on data interfacing and standardization. "One of the main developments I see in optical engineering is that the integration of illumination software with lens design packages has gotten a lot closer to reality," says Robert Fischer, president of Optics 1 (Westlake Village, CA). "ZEMAX [Bellevue, WA] is one design program that's moving in that direction, starting several years ago, but it's an evolutionary process. This level of integration isn't trivial."
The combination of optical engineering's three main tool sets - lens design, illumination/propagation, and physical optics simulation - has come a long way from when designers used to cover multifaceted automotive headlights with paper, leaving only one facet open to make physical measurements of the light's direction. The additions of Monte Carlo simulations in optical design software, non-sequential surface algorithms in illumination design software, and beam propagation in physical optics simulation software have made these design environments more powerful, yet connecting the packages into an end-to-end optical engineering package has yet to reach its full potential.
According to OPD's Thomas, "Right now, we're still using multiple programs. Lens optimization is done in Code V [Optical Research Associates; Pasadena, CA] ... illumination in ASAP or FRED [Photon Engineering LLC; Tucson, AZ], physical optics in Code V, FRED, or ASAP. Integration is improving in that Zemax has added some basic illumination functionality and also has add-ed physical optics propagation. Also, programs like FRED have taken an integrated optical-mechanical approach and have given the user advanced optical analysis options in a 3-D Cad-like environment. However, current design problems are so complex that it's often beneficial to use the program that is best-suited to the task at hand."
One innovation that may assist the development of "open" optical engineering design programs is scripting languages. Within each design environment, Thomas says that different vendors use proprietary scripting languages, forcing programmers to learn multiple syntax to perform similar calculations. "Each of the optical CAD programs has its own proprietary script, but FRED is the first to adopt visual basic as its scripting language, and OSLO bases its macro languages on C," he says. "Usually, if you're an optical engineer that can write code, you spend your entire day programming to automate the design and analysis, but with this type of structure, you can outsource some basic code development such as graphics and some numerical analysis, and focus on designing the optical system." Similarly, the development of open-source codes such as extensible markup language is helping designers combine powerful image processing programs such as MatLAB (The MathWorks Inc; Natick, MA) with optical design programs. "It used to be voodoo to do a com interface, but it's getting a lot easier," Thomas says. oe