Solid-State Continuous-Wave Laser Light Sources
One of the foremost design goals of the E&S Laser Projector was to solve the problem of expensive light sources which degrade over time and require constant periodic replacement. CRT tubes, Xenon arc lamps, and other conventional projector light sources all have limited life spans, and all exhibit the undesirable property of gradually diminishing output intensity as the lamp ages.
The light sources for the Laser Projector are solid-state diode-pumped fiber lasers of the same type that is used in fiber-optic telecommunications equipment. These lasers are exptremely reliable and stable. The laser diodes used within have operational lifetimes well in excess of 100,000 hours, and the power output does not gradually decay over time. Also, the color of each light source, because it is a laser, is also extremely stable and therefore the Projector does not exhibit "color drift" over time.
E&S uses a relatively safe type of laser with continuous wave output. Other types of high-power pulsed-mode lasers, such as those designed for industrial cutting purposes, maximize their destructive force by emitting very short bursts of power much higher than the average rating of the device. Notably, other laser-based projectors currently on the market use this type of laser, which brings along a set of safety problems. For example, a pulsed laser projector with 10-Watt output may emit short pulses at a cycling rate of 80 MHz, with each pulse lasting only 7 picoseconds. Amazingly, this common configuration results in an instantaneous peak power output, during the strongest portion of the pulse, of over 10 Kilowatts! Clearly, this class of power density, when concentrated in a single beam, could instantly cripple a human eye.
But not all laser devices are as dangerous. It’s all a matter of power, power density, and the way the laser is employed. For example, the LED-based laser pointers that are found in many conference rooms these days are harmless, in part because of their low power (5 mW typically), and in part because they produce a safer continuous-wave (CW) output, which lacks the concentrated power "spikes" of the pulsed laser.
For a variety of reasons, the Laser Projector employs the much safer CW type of laser light source. Although a significant amount of special R&D was required to produce CW lasers suitable for this application, the benefits are well worth the effort required. We already know that the CW laser has significant safety benefits. But there are reliability benefits as well. The CW laser light is easily guided with lightweight optical fibers, whereas pulsed laser light can have a tendency to "burn up" these fibers due to the high power transients.