14 DAY TRIAL // In a study that proved diode lasers can replace their LED-based counterparts in a wide variety of applications, researchers at the US Department of Energy's (DOE) Sandia National Laboratories (SNL) were able to produce a high-quality type of white light using nothing but a four-color laser source.
SNL investigators were very curios to determine whether white light produced from diode lasers influenced the human eye differently than white light generated by light-emitting diode (LED) lasers.
Researchers therefore developed a series of tests to assess this issue, and eventually determined that the human eye perceives no difference between the two types of white light, proving itself to be equally as comfortable with both of them.
The main difference between these two types of lasers is the fact that LED-based devices generate light by spontaneously releasing photons when electrical current is passed through a material, whereas the diode-based devices bounce the photons between internal mirrors before releasing them.
One of the main reasons why this difference is so important is that LED lasers become less efficient when the electrical current feeding them exceeds 0.5 amps. These devices were created to replace light produced by tungsten incandescent bulb technology.
Interestingly enough, the efficiency of diode lasers tends to improve as more amperage is applied to the circuit, producing even more light in situations where their LED-based counterparts falter.
“What we showed is that diode lasers are a worthy path to pursue for lighting. Before these tests, our research in this direction was stopped before it could get started,” SNL research scientist Jeff Tsao explains.
“The typical response was, ‘Are you kidding? The color rendering quality of white light produced by diode lasers would be terrible.’ So finally it seemed like, in order to go further, one really had to answer this very basic question first,” adds the expert, who proposed the new experiment.
The actual white light beam was produced at the University of New Mexico Center for High Technology Materials. A group of 40 volunteers were asked to observe a series of bowls containing identical fruit arrangements. Each set of bowls was illuminated by a different light source.
The experiment revealed a statistically significant preference for the diode-laser-based white light, the team reports. The DOE Office of Science funded the bulk of this investigation, through its Solid-State Lighting Science Energy Frontier Research Center.