Doors providing access to spaces containing open-beam Class-4 lasers shall be fitted with interlocks to prevent emission from the lasers if the doors are opened, and to deny outside-to-inside entry during laser emission. Design of interlocks should favor the use of shutters or laser beam dumps to limit emission. Laser power supply shutoffs should not be used except where no other alternative exists.
Laser operations in which personnel entering rooms can immediately encounter a potentially harmful level of laser radiation are not permitted.
A lab containing a number of lasers and/or interlocked optical benches or beam paths may require a programmable logic controller to coordinate interlock functions and warning annunciations at the entrances.
ANSI Z136.1 188.8.131.52.2
All doors to Class-3b and Class-4 laser areas shall have ANSI Z136.1 (2000) specification laser warning signs. Signs should be mounted such that they are visible near the doorway and at some distance from it. Signs should not be mounted above doorways, as these can be overlooked. Lighted laser warning signs (or status panels that indicate the room access status) shall be used for Class-3b and Class-4 lasers.
Electronic displays may be preferable for conspicuousness and/or to relate instructions for labs with complex laser setups. Electronic displays may be simple, with features ranging from on-off switch controls, to enunciators for systems interfacing laser, room access, and beam enclosure interlocks. Modern light-emitting diode (LED) displays and programmable logic controllers (PLCs) can display access status and specify laser eyewear or personal protective equipment (PPE) requirements. Electronic displays may also be used in addition to conventional warning signs.
ANSI Z136.1 184.108.40.206.2
Partitions, dogleg entrances, or other provisions shall be made to allow persons to don laser protective eyewear and other required PPE before entering spaces where beam hazards exist or could exist. Preferably, this provision should be made before they enter the lab.
Laser eyewear is vulnerable to physical damage and is expensive, so provisions need to be made for proper storage to prevent scratching or other damage.
Appropriate barriers shall be provided to prevent Class-3b or Class-4 laser beams from leaving the confines of a laser lab through doorways, windows, etc.
NOTE: ANSI Z136.1 recommends barriers for Class-3b lasers and mandates barriers for Class-4 lasers. Laser labs could be set up in rooms with windows, but should not be set up in a space with operable windows. Windows need to be covered with appropriate materials (opaque at the laser wavelength and compatible with the beam energy) to prevent beams from escaping. A simple metal plate with a diffusely reflective finish at the laser wavelength is adequate.
ANSI Z136.1 220.127.116.11.2