Laser lighting display
The laser show is referred to the use of laser beams as a lighting effect for entertainment. Laser shows are often shown in nightclubs, on concerts or other big events.
A distinction between projection and beam show. When projecting Show ( walls, screens ) are imaged with the laser images and animation on a projection surface, while the beam show laser beams are projected toward the viewer into the room. By haze in the room the viewers see scale patterns or lines that extend from the starting point on the mirror towards the spectator. The use of water screens produces a mixture of the two effects.
Frequently the use of lasers with other media such as pyrotechnics, conventional projections, lighting effects or artist interaction is combined.
For laser shows different laser sources are used, these are mostly cw gas laser, diode laser or DPSS lasers in the power range of a few mW to 100 W. Since lasers are basically monochromatic, polychromatic effects, however, are charming, mixed gas ion lasers are often (argon / krypton to about 40 W ) is used, or different colored DPSS and / or diode laser combined (up to about 15 W). Due to the insufficient performance red Festkörper-/Diodenlasern in high power field (> 15 W), there are preferably used large- frame laser ion. Furthermore, the extremely good -beam data of ion lasers with solid-state lasers are so far out of reach. Thus ion lasers are much more demanding can also be used in large-scale outdoor graphic shows, as their color lines production reasons are always excellent to each other.
Depending on the application and budget, some of the following components can be omitted.
Next, usually a security element that can turn off the laser beam rapidly in case of fault follows ( Beamdump in the beam tilting mirror which directs the beam into an absorber ). Event of an error, for example, the failure of the amplifier or galvanometer.
If a source of multiple projectors are fed, the primary beam is split by beam splitters on the following routes.
In order to display multiple elements or interruptions, the beam may be switched off quickly. For this purpose, either - a tilted mirror in the beam used or used an acousto-optic modulator - as in the safety shutdown. DPSS and diode lasers can be blanked directly via an input to the drive electronics.
A plurality of differently colored laser beams can be guided into a common ray path and is deflected together. By mechanically swiveled Dichrofilter ( color filter ) or acousto-optic modulators ( AOM) will affect the intensities of the individual colors and thus change color and intensity of the total beam. When using diodes and DPSS lasers, the intensity can be adjusted directly at the laser (usually via an analog input to the drive electronics ). A downstream color mixing thus eliminating the need completely.
If multiple projectors are used on different or individual projectors in inaccessible places, the beam is coupled into a fiber link.
Become a lattice or solid beams used, the beam is split on an optical bench by means of swing-in mirror on the individual elements.
Grating ( Grating ) produce diffraction and interference pattern of dots. The grids are sometimes rotated.
About two slightly tilted on motor axes mounted mirrors two circular motions of the beam are superimposed and generates spiral pattern, which can be varied by changing the speed.
Scanners consist of two galvanometers ( galvo ), ie perpendicular mounted mirrors on magnetically driven axles. The one galvo assumes the horizontal, the other vertical deflection of the beam. Depending on the quality and control effort (open loop and closed loop scanner for devices with or without position sensing and control) means that up to 72,000 points per second to be approached.
Due to the complex interaction between blanking, color mixing and scanning an image is repeatedly drawn that appears standing by the inertia of the eye, similar to the movie. This interaction is only accessible by computer or microcontroller. Since the representations are composed of curves and not pixels, is a form of vector graphics.
The software is used to control the scanner and to influence the color and performance of the laser beam. Most software solutions use to output the control signals ILDA protocol.
Safety and Regulatory
The lasers used for laser shows are usually divided into the laser class 3B and 4, so basically very dangerous to the eyes and dangerous for the skin. Therefore, the use of the laser for show purposes is strictly regulated.
For laser class 3R, 3B and 4, an indication of the operation as well as a maintenance inspection is required, it is based on tabulated maximum permissible exposures ( " MPE values " ) defines a laser range within which the laser radiation to the eyes is dangerous. The show laser must be installed such that there are no persons in this area.
This should also be ensured in laser systems, in which is due to the beam movements no danger to the eye in order to avoid hazards in case of failure of the beam deflection.
The use of protective eyewear, such as when adjustments is difficult with multi- color lasers due to the large number of lines in the visible range. Additionally difficult goggles work because the beam to be adjusted is no longer visible to hardly. In practice, therefore, only the output is reduced and worked without protective goggles for such work often.
Relevant provisions are
- EN 207 - Personal eye protection, laser safety goggles
- EN 208 - Personal eye protection, laser adjustment
- EN 60825-1 - Safety of laser products Part 1: Equipment classification and requirements
- DIN 4844-1 - Graphical symbols Safety colors and safety signs Part 1: Design principles for safety signs in workplaces and public areas
- DIN 56912 - show laser show and laser systems; Requirements and testing
- GUV B2/BGV B2
- BG Information 5007 show and laser projection
- Regulation on the protection of workers against risks arising from artificial optical radiation ( work legislation to artificial optical radiation - OStrV )
An application similar technique can be found in the Laser TV. Here, by the deflection of the laser beam, the individual pixels of an image approached and illuminated in the matching color, similar to the electron beam in a cathode ray tube.