Annex 3: Non-coherent 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 range of radiation emitted by the source and the results should be compared with the corresponding exposure limit values indicated in Table 3.1. More than one exposure value and corresponding exposure limit can be relevant for a given source of optical radiation.

Numbering (a) to (o) refers to corresponding rows of Table 3.1.

a)		(H_eff is only relevant in the range 180 to 400 nm)
b)		(H_UVA is only relevant in the range 315 to 400 nm)
c), d)		(L_B is only relevant in the range 300 to 700 nm)
e), f)		(E_B is only relevant in the range 300 to 700 nm)
g)-l)		(See Table 1.1 for appropriate values of λ₁ and λ₂ )
m), n)		(E_IR is only relevant in the range 780 to 3000 nm)
o)		(H_skin is only relevant in the range 380 to 3000 nm)

For the purposes of these regulations, the formulae above can be replaced by the following expressions and the use of discrete values as set out in the following tables:

a)		and (H_eff = E_eff · Δt)
b)		and (H_UVA = E_UVA · Δt)
c), d)	[formula missing, see Norwegian version]
e), f)
g) - l)		(See Table 1.1 for appropriate values of λ₁ and λ₂ )
m), n)
o)		and (H_skin = E_skin · Δt)

Notes:

Eλ (λ,t), Eλ	spectral irradiance or spectral power density: the radiant power incident per unit area upon a surface, expressed in watts per square metre per nanometre [Wm^-2 nm-1]; [Wm^-2 nm^-1]; values of Eλ (λ, t) and E_λ come from measurements or may be provided by the manufacturer of the equipment;
E_eff	effective irradiance (UV range): calculated irradiance within the UV wavelength range 180 to 400 nm spectrally weighted by S (λ); expressed in watts per square metre [Wm^-2];
H	radiant exposure: the time integral of the irradiance, expressed in joules per square metre (Jm^-2 );
H_eff	effective radiant exposure: radiant exposure spectrally weighted by S (λ), expressed in joules per square metre [Jm^-2];
E_UVA	total irradiance (UVA): calculated irradiance within the UVA wavelength range 315 to 400 nm, expressed in watts per square metre [Wm^-2];
H_UVA	radiant exposure: the time and wavelength integral or sum of the irradiance within the UVA wavelength range 315 to 400 nm, expressed in joules per square metre [Jm^-2];
S (λ)	spectral weighting: taking into account the wavelength dependence of the health effects of UV radiation on eye and skin (Table 1.2) [dimensionless];
t, Δt	time, duration of the exposure, expressed in seconds [s];
λ	wavelength, expressed in nanometres [nm];
Δ λ	bandwidth: expressed in nanometres [nm], of the calculation or measurement intervals;
Lλ (λ), Lλ	spectral radiance of the source expressed in watts per square metre per steradian per nanometre [W m^-2 sr^-1 nm^-1];
R (λ)	spectral weighting: taking into account the wavelength dependence of the thermal injury caused to the eye by visible and IRA radiation (Table 1.3) [dimensionless];
LR	effective radiance (thermal injury): calculated radiance spectrally weighted by R (λ) (λ), expressed in watts per square metre per steradian [Wm^-2 sr^-1];
B (λ)	spectral weighting: taking into account the wavelength dependence of the photochemical injury caused to the eye by blue light radiation (Table 1.3) [dimensionless];
L_R	effective radiance (blue light): calculated radiance spectrally weighted by R (λ) (λ), expressed in watts per square metre per steradian [Wm^-2 sr^-1];
E_B	effective irradiance (blue light): calculated irradiance, spectrally weighted by B (λ), expressed in watts per square metre [Wm^-2];
E_IR	total irradiance (thermal injury): calculated irradiance within the infrared wavelength range 780 nm to 3 000 nm expressed in watts per square metre [Wm^-2];
E_skin	total irradiance (visible, IRA and IRB): calculated irradiance within the visible and infrared wavelength range 380 nm to 3 000 nm, expressed in watts per square metre [Wm^-2];
H_skin	radiant exposure: the time and wavelength integral or sum of the irradiance within the visible and infrared wavelength range 380 to 3 000 nm, expressed in joules per square metre [Jm^-2];
α	angular subtense: the angle subtended by an apparent source, as viewed at a point in space, expressed in milliradians (mrad). Apparent source is the real or virtual object that forms the smallest possible retinal image.