Laser Safety Classification

Class 1: A Class 1 laser is considered safe based upon current medical knowledge. This class includes all lasers or laser systems which cannot emit levels of optical radiation above the exposure limits for the eye under any conditions inherent in the design of the laser product. There may be a more hazardous laser embedded in the enclosure of a Class 1 product, but no harmful radiation can escape the enclosure.Class 2: A Class 2 laser or laser system must emit a visible laser beam. Class 2 laser light is too dazzling to stare into for extended periods. Momentary viewing is not considered hazardous since the upper radiant power limit on this type of device is less than the Maximum Permissible Exposure for momentary exposure of 0.25 seconds or less. Intention extended viewing, however, is considered hazardous. Class 3: A Class 3 laser or laser system can emit any wavelength, but it cannot produce a diffuse (not mirror-like) reflection hazard unless focused or viewed for extended periods at close range. It is also not considered a fire hazard or serious skin hazard. Any continuous wave (CW) laser that is not Class 1 or Class 2 is a Class 3 device if its output power is 0.5 W or less. Since the output beam of such a laser is definitely hazardous for intra-beam viewing, control measures center on eliminating this possibility.Class 4: A Class 4 laser or laser system is any that exceed the output limits (Accessible Emissions Limits, AELs) of a Class 3 device. As would be expected, these laser may be either a fire or skin hazard or a diffuse reflection hazard. Very stringent control measures are required for a Class 4 laser or laser system. Ultrafast lasers fall into this classification.
Ultrafast lasers possess safety hazards not associated with light from conventional sources. Among potential injuries, eyes are the most vulnerable. Damage to the retina cannot be repaired and does not heal by itself.Why is eye safety so critical? Compare the output of femtosecond lasers with the radiation that the human eye can receive from the sun on a clear day. The sun’s image on the retina is approximately 160 microns. This yields a radiation density of around 30 W/cm2. A typical Ti:Sapphire femtosecond oscillator is capable of producing intensity in excess of 50 GW/cm2, while an amplifier will easily exceed 1014 W/cm2. Obviously, very weak laser reflections, or even scattering from rough surfaces, can be extremely bright - dangerously bright - to the eyes.You are urged to read carefully the safety section found in the user manual of any laser product you use and to strictly adhere to those instructions.

iClad: A Wonderful Laser Cladding Head

In the race against time, the specialists at Stork Gears & Services BV, Rotterdam, have a global reputation in sectors like the shipbuilding, petrochemical, wind power, and steel industries where the maximum uptime of efficient gearboxes and associated drive systems is of crucial importance. As quickly as possible, the experts at Stork repair damaged or failed gearbox-related components, rebuilding them or replacing them with new parts. In this line of work, laser cladding is used as a tried-and-tested technology to prevent wear-out and unwanted material changes. The team led by Jelmer Brugman, head of Stork's laser cladding department, successfully applies this technique on more than 20 gear repair or modification jobs per month. However, in about 10% of the cases, inaccessible internal surfaces could not be treated with conventional laser processing heads. Until about a year ago, there was no alternative but to replace the damaged parts with new ones. The solution to this problem is iClad, a laser processing head developed by Pallas GmbH the treatment of internal contours from a diameter of 26 mm and to a depth of 600 mm. By using this innovative processing head, the Dutch company has opened up new possibilities for the repair of critical components. Compared with the previously unavoidable effort involved in such cases, several weeks of repair time can be saved. In the maritime industry, in power stations, or wind power plants, gearboxes and gearwheels have to operate reliably over long periods of time under the hardest of conditions. In many different sectors, corrosion, abrasion, and erosion put such drive systems under extreme pressure. This results in broken or damaged gearwheels, leading to unplanned downtimes or, in the worst case, complete failure. Since last year, however, Stork Gears & Services has been successfully using the new iClad processing head for the preventative maintenance, modification, and repair of such heavily stressed drive systems. Now, both damaged and new components can be optimally coated with low distortion using a 2-kilowatt diode laser. The surface of the component and the powder jetsprayed onto it are melted by the laser and joined together metallurgically with minimal dilution. The previously available processing heads were only deployable for internal contours with an access aperture of at least 100 mm diameter or were limited to the treatment of freely accessible surfaces. The iClad processing head, developed by the company Pallas in collaboration with the Fraunhofer Institute for Laser Technology (ILT), can be used from a diameter of 26 mm and to a depth of 600 mm for the complete range of laser cladding tasks. Whether hardening, alloying, or coating, even in the tightest of internal spaces, iClad renders the most demanding internal surface treatments possible. For Brugman, laser cladding with iClad has significant advantages. Using the new processing head, highly strained critical components that were previously inaccessible can now be optimized or repaired with a coating specifically designed to meet their respective stress loads. As one of the first industrial-scale users, Stork Gears & Services deployed the newly developed processing head, a prototype of iClad with integrated collimation as a special feature. This was a fixed head with a working depth of 500 mm for the internal coating of 50 mm bores. In addition to gearwheels and clutches, gearbox casings are also treated using the new technology. On average, Stork deals with three gearbox repairs per month. One-piece gearbox casing models used to pose a real problem, as laser cladding by means of the standard processing heads was not an option. Before iClad was deployed, the alternative, the production of a completely new casing, used to take several weeks. Now, the filigree processing head for laser cladding of internal contours makes it possible to save time on the repair of a damaged gearbox and thus to reduce the duration of downtimes, a factor of great market relevance. So far, Stork has successfully used iClad on about 20 jobs – most of them demanding single-piece projects, i.e. not serial production. The new technology has proven itself both for repairs and for the production of new components. After just one year of deployment, the slender optical processing head for the laser treatment of hard-to-access inner contours has already significantly enlarged Stork's scope of service. Previously inaccessible surfaces and structures of critical components are now being successfully equipped in record time with specific coatings to meet the challenges of their wear-intensive daily lives.