Laser show

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A laser show is the use of laser beams as a lighting effect for entertainment. Laser shows are often shown in discos , concerts or other large events.

Beamshow in Rostock during the light week 2009
Laser show in a nightclub
Projection on a water screen
Projection show on waterscreen, projected Snoopy

Laser show waiting

A distinction is made between projection and beam shows. In the projection show, images and animations are shown on a projection surface (walls, screens) with the laser, while in the beam show the laser beams are projected into the room in the direction of the viewer . The projection with a laser is also possible on uneven surfaces, as the laser always remains sharp. When using waterscreens , the laser projection creates a slight 3D effect.

In the beam show, the mist / fog in the free space is the projection surface , so the viewers see two-dimensional patterns or lines that expand spatially from the starting point at the scanner mirror to the viewer. The viewer is transported into a virtual 3D world. A beam show is only possible in the dark, otherwise the effect of being in a different world is lost. The laser beam is only visible through the fog, because it or other contaminants in the air scatter the light of the beam. The viewer thus sees the scattered radiation. Rain, snow or soap bubbles enrich a beam show, as every object in the air becomes a sparkling flash of light when it is hit by a laser beam.

The use of lasers is often combined with other media such as pyrotechnics, conventional projections, light effects or artist interactions.

Technical implementation

laser

For laser shows various laser sources are used, these are mostly cw - gas lasers , diode lasers or DPSS lasers in the power range of some mW to 100 W . Since lasers are basically monochrome , but polychromatic effects are more attractive, mixed gas ion lasers (argon / krypton up to about 40 W) or different colored DPSS and / or diode lasers combined (up to about 15 W) are often used. Due to the insufficient power of red solid-state / diode lasers in the high-power range (> 15 W), large-frame ion lasers are preferably used there. Furthermore, the extremely good beam data of ion lasers with solid-state lasers have so far been unattainable. This means that ion lasers can also be used in large-scale outdoor graphic shows, since their color lines always lie perfectly on top of one another due to the manufacturing process.

Depending on the application and budget, some of the following components can be omitted.

Safety shutdown

The next step is usually a safety element that can quickly switch off the laser beam in the event of a fault ( beam dump , a mirror that can be swiveled into the beam and directs the beam into an absorber). An example of a fault is the failure of the amplifier or galvanometer .

Beam splitting

If several projectors are to be fed from one source, the primary beam is divided into the following paths by means of beam splitters .

Blanking

In order to be able to display several elements or interruptions, the beam must be able to be switched off quickly. For this, either - as with the safety shutdown - a mirror swiveled into the beam is used or an acousto-optical modulator is used. DPSS and diode lasers can be blanked directly via an input on the driver electronics.

Color mixing

Several different colored laser beams can be guided into a common beam path and deflected together. The intensities of the individual colors are influenced by mechanically pivoted dichroic filters (color filters) or acousto-optical modulators (AOM) and thus the color and intensity of the overall beam change. When using diode and DPSS lasers, the intensity can be set directly on the laser (usually via an analog input on the driver electronics). A downstream color mixing is therefore completely unnecessary.

Fiber link

If several projectors are to be used on different or individual projectors in inaccessible places, the beam is coupled into a fiber link.

Optical bench

If grids or fixed beams are used, the beam is split between the individual elements on an optical bench using pivoting mirrors.

Grid

Grating ( Grating ) generated by diffraction and interference point pattern. The grids are sometimes rotatable.

Spiraloscope

Two circular movements of the beam are superimposed over two mirrors mounted slightly tilted on motor axes and spiral patterns are generated, which can be varied by changing the speed.

scanner

Scanners consist of two galvanometers ( galvos ), i.e. mirrors mounted at right angles on magnetically driven axes. One galvo takes on the horizontal, the other the vertical deflection of the beam. Depending on the quality and control effort ( open loop and closed loop scanner for devices with or without position detection and control), up to 72,000 points per second can be approached.

Due to the complex interplay between blanking, color mixing and scanning, an image is repeatedly drawn that, due to the inertia of the eye, appears to be standing, comparable to a film . This interaction can only be achieved with a computer or microcontroller . Since the representations are composed of curves and not of pixels, it is a form of vector graphics .

software

The software is used to control the scanner and to influence the colors and powers of the laser beam. Most software solutions use the ILDA protocol to output the control signals .

Security and Regulations

The lasers used for laser shows are mostly divided into laser classes 3B and 4, so they are basically very dangerous for the eyes and dangerous for the skin. Therefore, the use of the laser for show purposes is strictly regulated.

For lasers of classes 3R, 3B and 4, a notification of the operation is required, as well as a TÜV approval, but this is not required. Using tabulated maximum permissible irradiations ("MZB values"), a laser area is defined within which the laser radiation is dangerous for the eyes. The show lasers must be installed in such a way that nobody is in this area.

This should also be ensured in laser systems in which there is no danger to the eye due to the beam movements, in order to avoid dangers in the event of failure of the beam deflection.

The use of protective goggles, e.g. B. Adjustment work is difficult especially with multi-color lasers due to the large number of lines in the visible area. In addition, protective goggles make work more difficult, as the beam to be adjusted is barely visible, if at all. In practical use, therefore, often only the power is reduced for such work and work is carried out without protective goggles.

Relevant regulations are

  • EN 207 - Personal eye protection, laser safety glasses
  • EN 208 - Personal eye protection, laser alignment glasses
  • EN 60825-1 - Safety of laser equipment, Part 1: Classification of systems and requirements
  • DIN 4844-1 - Graphic symbols, safety colors and safety signs, Part 1: Design principles for safety signs for use in workplaces and in public areas
  • DIN 56912 - show lasers and show laser systems; Requirements and testing
  • GUV B2 / BGV B2
  • BG information 5007 show and projection laser
  • Ordinance on the protection of employees from the dangers of artificial optical radiation (Occupational Health and Safety Ordinance on Artificial Optical Radiation - OStrV)

Laser television

A similar technique is used in laser televisions . By deflecting the laser beam, the individual pixels of an image are approached and illuminated in the appropriate color, similar to the electron beam in a picture tube .

See also

literature

Web links

Commons : Laser Shows  - Collection of pictures, videos and audio files