IEC 60825-4 Safety of Laser Products - Part 4: Laser Protectors

The standard “IEC 60825-4 Safety of laser products - Part 4: Laser guards” developed by the International Electrotechnical Commission (IEC) describes laser guards surrounding the process zone of a laser processing machine, requirements for permanent and temporary (e.g. for service), and specifications for registered laser guards.

This standard applies to all component parts of an enclosure, including transparent (visibly transmitting) screens and viewing windows, panels, laser curtains and walls. Requirements for beam path components, beam stops and other parts of the protective enclosure of a laser product that do not enclose the process zone are contained in “IEC 60825-1 Safety of laser products - Part 1: Equipment classification and requirements”.

In addition, this standard specifies:

How to evaluate and determine the protective properties of a laser guard
How to choose a laser protector

For the purposes of this standard, the following definitions apply in addition to those given in IEC 60825-1:

The active guarding protection time is the minimum time, measured from the issuance of the active guard termination signal, during which the front surface of an active laser guard can safely prevent laser radiation accessible from the rear surface of the active laser guard from exceeding the class 1 accessible emission limit for a given laser exposure.
The active guard termination signal is the signal that an active guard gives in response to excessive exposure of its front surface to laser radiation and is intended to result in automatic termination of the laser radiation. The action of a safety interlock becoming open circuit is considered a signal in this context.
Active laser guarding is a laser guard that is part of a safety-related control system. The control system generates an active guard termination signal in response to the impact of laser radiation on the front surface of the laser guard.
The foreseeable exposure limit is the maximum laser exposure at the front surface of the laser guard within the maintenance inspection interval, evaluated under normal and reasonably foreseeable failure conditions.
The faceplate is the face of the laser shield designed to be exposed to laser radiation.
A laser guard is a physical barrier that limits the extent of the hazard zone by preventing laser radiation accessible from its rear surface from exceeding the class 1 accessible emission limit.
A laser processing machine is a machine that uses a laser to process materials and is covered by the ISO 11553-1 standard.
The laser termination time is the maximum time from the generation of an active guard termination signal to the termination of laser radiation. The laser termination time refers to the response of the laser processing machine, specifically the laser safety shutter, and not to the response of an active laser guard.
A passive laser protector is a laser protector that works based solely on its physical properties.

A laser guard must meet the ISO 12100-2 standard with regard to the general requirements for guards as well as the more specific requirements regarding its location and method of fastening. Furthermore, a laser guard must not give rise to any associated hazards on or beyond its rear surface when exposed to laser radiation up to the foreseeable exposure limit in its intended location. Examples of associated hazards are: high temperature, release of toxic substances, fire, explosion, electricity. The evaluation of the foreseeable exposure limit is included in the standard annex (Annex B).

When the front surface of a laser guard is exposed to laser radiation within the foreseeable exposure limit, the laser guard shall prevent the laser radiation accessible from its rear surface from exceeding the accessible emission limit of class 1 at any time during the maintenance inspection interval. The minimum value of the maintenance inspection interval for automatic laser processing machines is 8 hours. This requirement shall be met for the intended life of the laser guard under expected operating conditions. This requirement implies both low transmission of laser radiation and resistance to laser-induced damage.

Some materials may lose their protective properties due to aging, exposure to ultraviolet radiation, certain gases, temperature, humidity, and other environmental conditions. In addition, some materials transmit laser radiation under high-intensity laser exposure even when there is no visible damage.

Active laser guards The active guard protection time exceeds the laser termination time by the foreseeable exposure limits. Generation of the active guard termination signal results in a visible or audible warning. Manual reset is required before laser emission can resume.

Among the numerous testing, measurement, analysis and evaluation studies that our organization has carried out for businesses in various sectors, it also provides testing services defined in the “IEC 60825-4 Safety of laser products - Part 4: Laser protectors” standard with its trained and expert staff and advanced technological equipment.