Sources of artificial lighting are widely used in all areas of modern life. The incandescent lamps that have been known for more than a hundred years and the luminescent sources that appeared just before the outbreak of World War II have a number of known disadvantages.
They are reasonably considered:
- low efficiency;
- unsatisfactory weight and size parameters;
- the tendency of fluorescent lamps to ripple;
- the complexity of regulating the luminous flux.
To eliminate them, a number of other solutions were proposed, the most promising among which were demonstrated by semiconductor sources based on LEDs. Laser sources became a further development in this direction.
Visible wavelength lasers were previously used in lighting technology. But due to the monochromatic nature of the generated radiation, their capabilities were limited and did not go beyond the effects on various light shows. An example of laser illumination is shown in Figure 1.
How a laser source works
The principle of operation of a new generation laser source is based on double conversion:
- first, the electric current is converted into blue laser radiation;
- then white light is obtained from it due to luminescence on a phosphor.
In the process of the second transformation, coherence is suppressed and predominantly high directivity of the initial laser radiation: aperture angle (divergence angle) does not exceed 2 degrees. The generated luminous flux reaches 1000 lm / mm2, and the guaranteed MTBF is over 10 thousand hours.
Applications of laser radiation sources
The advantages of a laser diode in the directionality of the generated beam in combination with high brightness crystal and moderate current consumption opens up broad prospects for using these emitters. In automotive luminaires, a range of up to 1 km is provided. In addition, in combination with fiber optics, distributed illumination sources for the instrument panel and interior can be obtained.
Low current consumption is valuable where power is supplied from a built-in source. These are drones and flashlights. Figure 2 gives an idea of the capabilities of a laser flashlight.
Prospects for laser sources in household devices
The high directivity of laser radiation is becoming a disadvantage for conventional household lamps.
The ways to eliminate it are well known:
- the use of assemblies of several emitting crystals of moderate power;
- the use of integrated optical systems.
The available prototypes show good prospects. The Japanese company SLD Laser has started the serial production of the first generation sources under the well-recognized LaserLight trademark. The functionally completed element has a flat housing typical for electronics (see. Figure 3), which is convenient for surface mounting.