Showlasers

Different laser classes and their restrictions

They are absolute eye-catchers and always cause amazement: laser shows. Whether in a large-scale discotheque, on a cruise ship or as an environmentally friendly alternative to fireworks. Today, laser shows are often part of the entertainment program. However, since show lasers are by no means always harmless, certain devices may only be operated by certified professionals. We introduce the different device classes and give an overview of their use.

Class 2 and 2M

Class 2 and 2M lasers are approved without restriction in many countries. They can therefore be used easily and only a small minimum distance and no technical protective measures have to be observed or proof provided. These classes include lasers with a wavelength between 400 and 700 nanometers, i.e. lasers that are in the visible light range and have an output power of 1 mW or less per individual beam. In show applications, these are usually simple star lasers or cluster lasers that generate a large number of laser points. In combination with fog, these dots then become visible beams. Of course, this also applies to class 2 and 2M effect lasers that are integrated into other lighting effects.

A special laser projector from this class is offered by the company LASERWORLD: the EL-300RGB . While almost all projectors of this class work with red and/or green laser colors, this device adds a blue laser. As a real special feature, the colors here are not next to each other as usual, but can be mixed to up to 7 additional colors by a special optic.

Control

But how is a larger laser controlled? In the professional environment, show lasers are almost invariably controlled by means of a computer and special software via their ILDA interface or, nowadays, very often via a network. For the control via ILDA an external interface on the PC is necessary, for the control via network all common software manufacturers offer their interfaces as built-in version directly in the laser projectors. The manufacturer LASERWORLD , for example, labels these devices with “Shownet inside”. On these network interfaces built into the laser projectors, graphics and patterns can be stored, which can be called up via DMX including all safety measures. This way, even more complex shows can be easily realized with DMX control.

Class 3 and 4

If you want to address a larger audience with a laser show or if you want to create your own, more complex shapes and graphics, you can’t avoid projectors of laser classes 3 or 4. This is where the more powerful show lasers are found, which work with very small deflection mirrors that move at high speed and can thus create a wide variety of patterns up to complex images. This deflection unit, consisting of 2 mirrors, one for the horizontal and one for the vertical deflection of the laser beam, is also called “scanner”. How fast and precise the scanner unit in a laser projector can display the patterns, can be found out from the indication “kpps”. “kpps” is the abbreviation for kilo points per second, i.e. how many points the laser can scan per second. The higher the value, the cleaner and more precise the laser can display complex graphics. When comparing several devices, however, it must be taken into account that the beam angle to which the specification refers must also be comparable.

An industry-standard comparative value is recorded here with the so-called ILDA test image with a fixed beam angle of 8°. Thus, a projector with “25 kpps at 8° ILDA” can already display beautiful shapes and simple graphics. From “40 kpps at 8° ILDA”, complex shapes and graphics are already possible. A second statement about the light quality of the laser can be found in the so-called divergence value. The divergence is given in mrad [pronounced: “millirad” or “milliradiant”] and determines how cleanly the laser light runs, i.e. how little it diverges. The value 1 mrad corresponds to a beam widening of 1 cm over a distance of 10 m. Ideally, this value is the same for all laser beams and the same for all colors, so that the basic colors of the projector remain congruent over longer distances and a nice color mixture is maintained.

The disadvantage of class 3 and class 4 lasers is the health hazard they pose. Anyone who wants to operate a show laser of these classes must fulfill a number of requirements. Among other things, a certificate of competence must be provided. In clear terms, this means having attended a course to become a laser safety officer and also renewing this qualification at regular intervals. In the past, every change of location, i.e. every new installation of such a laser, had to be registered with the regulatory authority and possibly even approved by a test center. Fortunately, this regulation has changed somewhat: By now, only the proof of a comprehensive safety concept is required, which has to be prepared before the event. Such a safety concept is no small matter, because it must take into account all the requirements and explain how they have been implemented in the respective location. In addition, class 3 and 4 lasers must always be connected to an emergency stop switch, which can be used to immediately shut down the system at any time in the event of problems.

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