they are “modulatable,” meaning their power levels can quickly be turned up, down, or off, which is obviously important for projecting a moving image on a screen.
The next key component of the Prysm light engine is a spinning, multifaceted mirror. (To learn just how many facets the mirror has, or how many lasers are in the Prysm array, you’ll just have to buy a Maui unit and tear it down. Those are the sorts of details I agreed not to specify.) The function of the spinning mirror is to direct a bundle of laser beams to a specific group of targets on the phosphor stripes, then quickly redirect the beams to the adjacent set of targets, and so forth, many, many times each second.
Of course, there’s a whole obstacle course of other mirrors and lenses in between the spinning mirror and the phosphor panel—including a Fresnel lens bonded to the panel itself that intercepts the laser beams and straightens them out so that they hit the phosphor stripes at right angles. There’s also a control layer bonded to the panel, etched with lines that resemble a bar code; the system uses the reflections from this so-called “servo layer” as a form of feedback, constantly adjusting the aim and timing of the laser beams to stabilize the picture and make sure that the laser beams are hitting the correct phosphor stripes.
Remarkably, Prysm’s engineers have figured out how to squeeze the entire optical mechanism into a box only about 18 inches deep. One trick for providing the laser beams with all the focal length they need was to use a periscope-like set of mirrors to add height to the units rather than depth; these give the Maui a zig-zag shape that make the units not only shallower but more stackable.
As innovative as its overall concept may be, however, Tan says Prysm uses as much off-the-shelf technology as it can, starting with the laser diodes. “As you dream of how to design something, you’ve got to be sure you can make it,” he says. “We try to avoid the NIH [Not Invented Here] syndrome—if it’s already been solved elsewhere, we use it.”
Tan is also proud of Prysm’s green credentials. In fact, the company has coined a word, “ecovative,” to underscore its commitment to building devices that don’t use much energy compared to traditional displays, and that don’t contain any heavy metals or toxic gases. “We’re trying to come up with something that addresses the limitations [of traditional large-format displays] but at the same time make it as eco-friendly as possible,” Tan says.
Under the Spudnik name, Prysm raised an unspecified amount of Series A venture funding in late 2005, and then a larger Series B round in the spring of 2007, according to Tan. Its investors have included Partech International, Artiman Ventures, CSK Group, and the now-defunct Galleon Group.
The next big milestone for the startup, before it can win some big commercial installation projects, will be showing that the 25-inch Maui screens can be
