Laser safety DCU激光安全系统.ppt

Laser safety Paul van Kampen 02/02/11 Almost all you need to know about laser safety Beware of electrical safety Don’t expose your eyes or skin Minimise the number of shiny surfaces Wear goggles Beware of water leaks Use warning signs Use interlocks Types of laser Continuous wave (cw) or pulsed Power Wavelength Visible/invisible Effect on skin, cornea, retina Laser classification What is it based on? Maximum Permissible Exposure (MPE) 10% of dose that has 50% chance of doing damage Depends on wavelength, body part, cw or pulsed Visible-IR range, cornea, cw: 1 mW/cm2 Example: class 1 or class I laser limit Fully dilated pupil: diameter 7 mm, area 0.39 cm2 Maximum permissible power: 0.39 mW Laser classification (old) Class I: safe (UNFOCUSSED!) Class II: safe - your aversion to bright light will protect you Class IIIA: cw: 1-5 mW, safe unless you look at it, or its reflection, directly Class IIIB: cw 5-500 mW, pulsed 10 J/cm2, sometimes diffuse reflection hazard Class IV: cw 500 mW, pulsed 10 J/cm2, diffuse reflection, fire, skin hazard More data become available More data become available Laser classification (new) Class 1(M): safe (UNFOCUSSED!) 0.4 mW Class 2(M): safe - your aversion to bright light will protect you. 1 mW Class 3R: cw: 1-5 mW, safe unless you look at it, or its reflection, directly. Low risk Class 3B: cw 5-500 mW, (300 mW visible), pulsed 10 J/cm2, diffuse reflection OK Class 4: cw 500 mW, pulsed 10 J/cm2, diffuse reflection, fire, skin hazard, interlock required UV lasers Excimer lasers: gas premix typically contains 0.1 percent of fluorine/chlorine ArF, KrCl, KrF: UV-C radiation Eye: snowblindness Skin: sunburn, skin cancer XeCl: UV-B radiation Eye: snowblindness Skin: skin aging, increased pigmentation XeF, Nd:YAG tripled: UV-A radiation Eye: cataracts Skin: skin burn, pigment darkening Germicidal lamps 15 W UV-C lamp 254 nm, cylindrical, 30 cm tall 40% efficient in UV-C so 6 W of UV-C light Model: every ring 1 cm high centred on la