Here you will find explanations of the vocabulary of the website.

Portion of electromagnetic radiation incident on a body that is absorbed by the body.

Optical filter whose effect is based on damping by the filter material.

More or less conscious reaction of avoidance in case of danger exposure (moment of shock).

An incidence of light in the pupil of the human eye can trigger a reflex, which leads to eyelid closure within approx. 0.25 s. However, this reflex does not work for a significant portion of individuals.

Filter made of a glass type, which due to its composition has special spectral characteristics. Since the filter effect is a material property, the optical density increases with thickness.

From the physical point of view the continuous emission of laser radiation during a pulse duration larger than defined by standard EN 207 for pulsed operation.

Declaration by the manufacturer that his product complies with the requirements of mentioned European directives and regulations.

Alternating vapor deposition of very thin layers of high and low refractive, non-electrically conductive, optical materials on substrates lead to mirror surfaces for almost any spectral characteristics.

Incident energy of electromagnetic radiation divided by the irradiated area.

From a physical point of view, any finite emission of a laser in which the light amplification goes beyond the minimum gain required to start oscillation before the laser starts to oscillate. As defined by standard EN 207 emission with a pulse duration below the pulse mode limit and above the ultrashort pulse limit.

Type of laser safety or alignment glasses which can be worn over prescription glasses, without loss of protection against laser radiation. This type is usually held by an elastic headband, similar to a diving mask.

Incident power of electromagnetic radiation divided by the irradiated area.

From a physical point of view a laser is an overdriving electromagnetic radiation amplifier that becomes an oscillator. The gain is achieved by multiple reflections through a medium in which the upper laser level is more populated than the lower one.

Standard EN 208 glasses which protect against laser radiation. When correctly selected, such glasses attenuate the radiation to the limits of laser class 2 and the laser beam is still visible on a target. However, this requires a normal working blink reflex of the eye. This makes that laser alignment glasses are defined only for the wavelength range 400-700 nm. If the blink reflex does not work properly, the slower aversion reaction can be assumed at best.

Rough classification of the danger of laser devices in classes 1 to 4 according to standard EN 60825-1. For classes 1 and 2, personal protective equipment is not mandatory.

Durability of a material to laser irradiation. Various damage mechanisms are possible:

• damage due to UV radiation (dissolution of chemical bonds)
• melting due to absorption and concomitant thermal overload
• cracking due to thermal stress (glass)

Eye protectors according to standard EN 207, which protect against laser radiation. If the scale numbers are selected correctly, they attenuate the radiation to the limits of laser class 1.

Large-area shielding according to EN 12254 against laser radiation. When correctly selected, it attenuates the radiation to the limits of laser class 1.

Electromagnetic radiation perceived by the human eye. This applies to the wavelength range of approximately 400-800 nm.

Portion of light transmitted through a given material, taking into account the spectral sensitivity of the human eye.

Resident in an EC country who has the right to translate the results of a type examination into a type-examination certificate.

Standard EN 207 for laser safety glasses and EN 12254 for laser screens distinguish four laser modes for which different scale numbers each can be specified:

• D for continuous wave operation
• I for pulse operation
• R for giant pulse operation
• M for ultra-short-pulse operation (mode-locked)

The distinction between the three pulse modes occurs depending on the pulse duration. In contrast, standard EN 208 for laser alignment glasses only prescribes maximum permissible values for the power and the pulse energy for each scale number.

Measure for the attenuation of optical radiation. Mathematically, it is the negative, decadic logarithm of the transmittance.

All equipment that is worn on the body and serve the security. In the EU, they may only be placed on the market, if a valid type-examination certificate is available.

Transparent plastics can be colored by special dyes or dye mixtures, so that they have special spectral characteristics. The suitability as a laser protective filter then depends not only on the optical density and the laser resistance of the plastic, but also on the stability of the dyes.

From a physical point of view any laser emission of finite duration, as defined by standard EN 207 emission with a pulse duration below the limit of continuous wave operation and above the limit for giant pulse operation.

Portion of electromagnetic radiation falling on a body, which is reflected by the surface.

An optical filter whose effect is based on reflection of the radiation at an interface of the filter (e.g., dielectric mirror).

Laser safety goggles in accordance with EN 207 must protect at least for 5 s or, for pulsed operation, for 50 pulses before the permissible irradiation is exceeded. The scale numbers are fictitious optical densities. They can be different for the individual laser operating modes, but must not exceed the actual optical density. They can be between 1 and 10. For shields according to EN 12254, the same applies but up to 100,000 pulses over a period of 100 s, depending on the operating mode. The same criteria apply to laser eye protectors according to EN 208 as to laser eye protectors according to EN 207. In addition, there is also an upper limit for the optical density and the scale numbers can only be between 1 and 5.

Type of laser safety or alignment glasses with sides. It usually cannot be worn over prescription glasses without losing some of the protection.