Interlock systems enable the safe use of lasers when operators aren’t present by ensuring that the area of operation is protected from unauthorised access. To suit varying locations, from university laboratories to wind tunnels, and still provide safe and simple use, they have to be secured with appropriate enclosures. These housings have to ensure the necessary protection and must also offer the installation flexibility that suits the design layout of the host environment.
Lasers are used within commercial and university laboratories across the UK for multiple purposes including research and measurement. As a result of health and safety issues relating to their use, including damage to the eye’s retina, safety precautions have to be deployed. Included within the requirements is a laser interlock system that prevents unauthorised access to a laboratory while a laser is in use. At the same time, the interlock allows the continued and safe operation of the laser without supervision, which may be required, for example, during scientific experiments.
Laser Support Services’ interlock design comprises a main control unit as a master of the laser’s power supply and operation; a door control unit that authorises entry to the laboratory where the laser is in use; and a keypad that allows outside access to the lab. Each unit has to be housed within a safe and durable enclosure with mounting flexibility dependent on the layout and configuration of each laboratory. Laser Support Services has used Spelsberg enclosures from the outset.
“We have to adapt the interlock system for individual laboratory requirements. Spelsberg provides boxes that are flexible and very simple to use, making them adaptable and suitable for every laser interlock project,” says Grahame Rogers, Laser Support Services’ managing director and founder. “Various mounting points enables flexible installation, combined with an in-house CAD service when required.”
The laser interlock’s main control unit comprises a master key switch and an E-stop, as well as energise and de-energise functions for manual system operation. The unit also incorporates an LCD display to show status and faults. Each of these user interaction features is integrated within a Spelsberg enclosure that is configured for the required mounting positions. The enclosure walls are either smooth or feature pre-stamped knock-outs for simple assembly, and Spelsberg’s UK site also features an in-house CAD design service if specific customisation is required.
Typically, Laser Support Services uses Spelsberg’s TK enclosures. This includes the highly durable, glass fibre reinforced polycarbonate TK PC, as well as the very lightweight TK PS that is constructed from polystyrene. Both enclosures enable easy handling for a simple mounting process, while the TK PC is chosen for more rugged installation settings.
While the reinforced polycarbonate TK PC meets the high IK08 impact rating, the polystyrene TK PS box still achieves IK07, meaning impact resistance from 0.5kg dropped from 25cm. Both enclosures also provide ingress protection of up to IP66, giving Laser Support Services installation flexibility for wide-ranging settings, from wind tunnels to labs to clinics.
Even with knock out holes and customisation, the enclosures achieve high environmental protection, crucial for safe laser control. The TK enclosure’s gasket secures internal components from any outside moisture, and can operate in 95% humidity at 25°C.
Enclosures constructed from glass-fibre reinforced polycarbonate are also used, providing even higher impact resistance if required, offering up to IK08 protection, among the highest available levels. If Laser Support Services requires a large enclosure, for example when combining multiple control units, Spelsberg also provides mild steel housings.
As the setting differs between each laser interlock installation, which can also take place within existing buildings as well as integration within new developments, this means that the positioning of the system’s various control units has to be flexible to the locations space constraints. At the same time, the system must remain safe and simple to use for laboratory staff.
The system’s door control unit allows 30 seconds for the user to leave the laboratory, meaning that the closer the device can be positioned to the door, the safer and easier the system is to use. This requires flexibility in mounting and while 350mm x 250mm boxes are usually used, Spelsberg’s wide range of enclosure sizes means that the required dimensions are always available for the required setting.
While the enclosures that Laser Support Services typically requires are standard models, Spelsberg UK’s customisation service is available when required for fast turnaround of bespoke designs.