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γ = 1,1 t 0,5 [mrad] t > 104 γ = 110 [mrad] Table 2.6 Correction for repetitive exposure Each of the following three general rules should be applied to all repetitive exposures as occur from repetitively pulsed or scanning laser systems: 1. The exposure from any single pulse in a train of pulses shall not exceed the exposure limit value for a single pulse of that pulse duration.

2. The exposure from any group of pulses (or sub-group of pulses in a train) delivered in time t shall not exceed the exposure limit value for time t.

3. The exposure from any single pulse within a group of pulses shall not exceed the single-pulse exposure limit value multiplied by a cumulative-thermal correction factor Cp=N-0,25 , where N is the number of pulses. This rule applies only to exposure limits to protect against thermal injury, where all pulses delivered in less than Tmin are treated as a single pulse. Parameter Valid spectral range (nm) Value Tmin 315 < λ ≤ 400 Tmin = 10 -9 s (= 1 ns) 400 < λ ≤ 1 050 Tmin = 18· 10 -6 s (= 18 μs) 1 050 < λ ≤ 1 400 Tmin = 50· 10 -6 s (= 50 μs) 1 400 < λ ≤ 1 500 Tmin = 10 -3 s (= 1 ms) 1 500 < λ ≤ 1 800 Tmin = 10 s 1 800 < λ ≤ 2 600

Laser optical radiation The biophysically relevant exposure values to optical radiation can be determined with the formulae below. The formulae to be used depend on the wavelength and duration of radiation emitted by the source and the results should be compared with the corresponding exposure limit values indicated in the Tables 2.2 to 2.4. More than one exposure value and corresponding exposure limit can be relevant for a given source of laser optical radiation. Coefficients used as calculation tools within the Tables 2.2 to 2.4 are listed in Table 2.5 and corrections for repetitive exposure are listed in Table 2.6. Notes: dP power expressed in watt [W]; dA surface expressed in square metres [m2]; E (t), E irradiance or power density: the radiant power incident per unit area upon a surface, generally expressed in watts per square metre [W m-2]. Values of E(t), E come from measurements or may be provided by the manufacturer of the equipment; H radiant exposure: the time integral of the irradiance, expressed in joules per square metre [J m-2]; t time, duration of the exposure, expressed in seconds [s]; λ wavelength, expressed in nanometres [nm]; γ

limiting cone angle of measurement field-of-view expressed in milliradians [mrad]; γm measurement field of view expressed in milliradians [mrad]; α angular subtense of a source expressed in milliradians [mrad]; limiting aperture: the circular area over which irradiance and radiant exposure are averaged; G integrated radiance: the integral of the radiance over a given exposure time expressed as radiant energy per unit area of a radiating surface per unit solid angle of emission, in joules per square metre per steradian [J m-2 sr -1]. Table 2.1 Radiation hazards Wavelength [nm] λ Radiation range Affected organ Hazard Exposure limit value table 180 to 400 UV eye photochemical damage and thermal damage 2.2, 2.3 180 to 400 UV skin erythema 2.4 400 to 700 visible eye retinal damage 2.2 400 to 600 visible eye photochemical damage 2.3 400 to 700 visible skin thermal damage 2.4 700 to 1 400 IRA eye thermal damage 2.2, 2.3 700 to 1 400 IRA skin thermal damage 2.4 1 400 to 2 600 IRB eye thermal damage 2.2 2 600 to 106 IRC eye thermal damage 2.2 1 400 to 106 IRB, IRC eye thermal damage 2.3 1 400 to 106 IRB, IRC skin thermal damage 2.4 Table 2.2

Exposure limit values for laser exposure to the eye — Short exposure duration < 10 s Table 2.3 Exposure limit values for laser exposure to the eye — Long exposure duration ≥ 10 s Table 2.4 Exposure limit values for laser exposure of skin Table 2.5 Applied correction factors and other calculation parameters Parameter as listed in ICNIRP Valid spectral range (nm) Value CA λ < 700 CA = 1,0 700 — 1 050 CA = 10 0,002 (λ - 700) 1 050 — 1 400 CA = 5,0 CB 400 — 450 CB = 1,0 450 — 700 CB = 10 0,02 (λ - 450) CC 700 — 1 150 CC = 1,0 1 150 — 1 200 CC = 10 0,018 (λ - 1 150 ) 1 200 — 1 400 CC = 8,0 T1 λ < 450 T1 = 10 s 450 — 500 T1 = 10 · [10 0,02 (λ - 450)] s λ > 500 T1 = 100 s Parameter as listed in ICNIRP Valid for biological effect Value αmin all thermal effects αmin = 1,5 mrad Parameter as listed in ICNIRP Valid angular range (mrad) Value CE α < αmin CE = 1,0 αmin < α < 100 CE = α/αmin α > 100 CE = α2/(αmin · αmax) mrad with αmax = 100 mrad T2 α < 1,5 T2 = 10 s 1,5 < α < 100 T2 = 10 · [10 (α - 1,5 ) / 98,5 ] s α > 100 T2 = 100 s Parameter as listed in ICNIRP Valid exposure time range (s) Value γ t ≤ 100 γ = 11 [mrad] 100 < t < 104

Tmin = 10 -3 s (= 1 ms) 2 600 < λ ≤ 10 6 Tmin = 10 -7 s (= 100 ns)