Anyone who remembers the Micro Machines line of toys might be surprised to learn that the tiny model vehicles are positively gargantuan compared with actual micromachine manufacturing. While specimens of the miniature toy collection may indeed have been “smaller than a silver dollar,” some industrial micromachined parts compare similarly to the breadth of a human hair, which is around 75 microns.
For example, Potomac Photonics, Baltimore, MD, might use a high-speed laser to drill a grid of 25,000 holes, each less than two microns across, through a steel surface with an accuracy of plus or minus 0.3 microns—and do it cheaply enough that the part can be considered disposable. “That’s pushing the limits in terms of machining capability,” says Mike Adelstein, the company’s president and CEO.
The company’s website is rife with photos in which looming pennies and dimes dwarf the intricate metal gears, microfluidic channels, and 3D-printed plastic parts it has produced.
Since its founding in 1982, the company has worked on a number of Small Business Innovation Research (SBIR) contracts with the Department of Defense, the National Science Foundation, and other agencies to develop technologies such as lasers and ultrasensitive detectors. However, Adelstein says it was a set of SBIR contracts with NASA’s Marshall Space Flight Center in the mid-1990s that was especially influential in putting the company on the cutting edge of micromachining, leading to the work it does today.
There were two objectives to the Phase I and II SBIR contracts awarded to the company. One was to prove the capability of excimer lasers in crafting intricate, diffractive optical elements— lenses etched with thin, micro-structure patterns that manipulate the light passing through them. These are used in a wide variety of applications, from sensors and monitoring equipment to fiber optics, displays, and information storage. At the time, however, making these small-scale elements was time-consuming and hugely expensive.
While near-infrared lasers were commonly used to manufacture metal components, less was known about the use of excimer lasers, which operate in the deep ultraviolet range, to shape polymer and glass elements, such as lenses, Adelstein says. But the work proved the ultraviolet lasers were effective on these materials.
Then, the company wanted to develop an integrated, computerized workstation capable of mass-producing such optical components, using AutoCAD software to digitally control the process and make it faster, more flexible, and cheaper.
“NASA certainly was interested, because they do a lot of work with lasers and light,” Adelstein says.
The work that Potomac Photonics carried out under NASA SBIRs ended up being a major breakthrough for the company, resulting in a workstation that allowed the user to customdesign diffractive optical elements and produce them cheaply and efficiently.
Although its work with NASA was geared toward manufacturing diffractive optics, the company found that the digital fabrication technology it had developed for the workstation was useful in all sorts of micromachining. And micromachining is, in fact, one common application of the very diffractive lenses the workstations could now cheaply produce. These lenses allow optimized, precise laser cutting, drilling, and ablation— whereby a controlled amount of material is vaporized.
“It was that breakthrough that led to everything we do now,” Adelstein says of the work with NASA. “It showed a different way of making these components and pushed the limits of the technology. It really set the tone for our direction in leading this field.”
Over the years, he says, the company grew a contract manufacturing business, making tiny parts to order with quick turn-around times. Around 2008, the workstations were discontinued, and the company now focuses on “rapid contract micromanufacturing,” as Adelstein puts it, as well as continuing to develop new technologies to that end. The work ranges from microhole drilling and precise laser marking to hot embossing and 3D printing, working with metal, plastics, glass, ceramics, and silicon. Popular applications include medical devices, biotechnology manufacturing, and electronics, among others. (See Figure 1)
Software and laser technology have come a long way since the mid-1990s, and Adelstein says, in the company’s production line and in the world of modern technology, “everything’s gotten smaller, and everything’s gotten more precise.”