lasersafetyatfermilab-文庫吧在線文庫
【正文】 ? VIS Visible radiation – to mm ? IR Infrared radiation – Greater than mm ? Retinal hazard region to mm ? Far IR to 103 mm Eye damage = f(l) ? UV Cornea + lens ? VIS Retina ? IR Cornea Effect of l on damage threshold 1101001000290 310 330 350 370 390Radiant exposure (J/cm2) Wavelength (nm) Corneal injury (Zuclich andKurtin)Temporary lens opacities(Pitts, et al)Permanent lens opacities(Pitts, et al)Photokeratitis (Pitts, et al)Damage mechanisms ? Thermal – Increased temperature destroys tissue – VIS + IR ? Photochemical – Photon promotes chemical reaction – UV + far blue VIS ? Photoacoustic – Thermal expansion creates shock wave – 109 to 105 sec – VIS high intensity ? Plasmagenic – High Efield destroys tissue – Below 109 sec – VIS Damage threshold (approximate) EFFECT IR VIS UV WARMTH N/A PAIN 2 3 N/A ERYTHEMA (1st DEGREE BURN) 5 6 BLISTER (2nd DEGREE BURN) 10 12 1 LENS EFFECT 10,000 N/A RETINAL DAMAGE 3 Units of J/cm2 in exposures of ~ 1 sec Making things easier ? Classification scheme to simplify controls – Class 1 (safe) to Class 4 (dangerous) – Likelihood of inadvertent injury ? Low Class 1, 2 amp。 approval by LSO amp。 exposure duration ? NHZ Nominal Hazard Zone – The space within which the MPE is exceeded – Includes direct, reflected amp。 3a = few requirements ? High Class 3b amp。 D/S/C ? Qualify laser operators ? Isolate people from the beam ? Post signs during unenclosed operation ? Consider laser eye protection (optional) ? Other Qualify laser operators ? Laser operator ? Qualification – Laser safety training – Laser eye exam – Laser system manager authorization Training ? General Fermilab laser safety tr
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