The threat potential of the laser classes is the following: * Laser class one – Safe on account of low radiation level or safe enclosure * Laser class 2 – Safe in the event of accidental, unintended exposure due to defence reactions. This applies only to visible laser rays. * Laser class 1M, 2M – The threat potential corresponds to that of laser classes 1 and 2, if the laser beam is not looked at through optical instruments (magnifying glass, telescope, etc.). Conventional spectacles are not regarded as optical instruments for this purpose. * Laser class 3R – potentially dangerous to eyes, less stringent protection required. * Laser class 3B – dangerous to eyes, protection required. * Laser class 4 – dangerous to eyes and skin, a direct and diffusely scattered ray is dangerous, risk of burning (the laser acts as a source of ignition). * If class 3B and 4 laser equipment is used, or encased laser sources of class 3B and 4 exist, a laser protection engineer should be appointed in accordance with international recommendations.