OSHNET SCHOOL OSHNET SCHOOL FOR HIGH CERTIFIED EDUCATION IN THE FIELD OF OCCUPATIONAL AND ENVIRONMENTAL SAFETY AND HEALTH

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1 OSHNET SCHOOL FOR HIGH CERTIFIED EDUCATION IN THE FIELD OF OCCUPATIONAL AND ENVIRONMENTAL SAFETY AND HEALTH Module 1.2 Optical Radiation RICCARDO DI LIBERTO 1

2 Occupational Health & Safety NETworking in EASTern Europe OPTICAL RADIATION Radiometric quantities and measurements Riccardo Di Liberto Medical Physics Dept. Fondazione IRCCS Policlinico San Matteo Pavia- Italy Module 1.2 Optical Radiation RICCARDO DI LIBERTO 2

3 Exposure Limit Values for Artificial Optical Radiation are expressed in terms of RADIOMETRIC QUANTITIES Module 1.2 Optical Radiation RICCARDO DI LIBERTO 3

4 RADIOMETRIC QUANTITIES are physical absolute quantities independent of spectral sensitivity of the detector (eye). PHOTOMETRIC QUANTITIES depend on the spectral sensitivity of the eye. Module 1.2 Optical Radiation RICCARDO DI LIBERTO 4

5 Can be divided in two classes: Those describing the emitting source ( = radiant flux or power, L = radiance) Those describing the irradiated surface (E = irradiance, H = radiant exposure) Module 1.2 Optical Radiation RICCARDO DI LIBERTO 5

6 irradiance (E) or power density: the radiant power incident per unit area upon a surface expressed in watts per square metre (W m -2 ); radiant exposure (H): the time integral of the irradiance, expressed in joules per square metre (J m -2 ); radiance (L): the radiant flux or power output per unit solid angle per unit area, expressed in watts per square metre per steradian (W m -2 sr -1 ); Module 1.2 Optical Radiation RICCARDO DI LIBERTO 6

7 Irradiance of the source surface distance Module 1.2 Optical Radiation RICCARDO DI LIBERTO 7

8 Irradiance reduces with the inverse square law of distance Module 1.2 Optical Radiation RICCARDO DI LIBERTO 8

9 Radiance does not vary with distance! if the surface subtended by the solid angle is only the source! Module 1.2 Optical Radiation RICCARDO DI LIBERTO 9

10 Module 1.2 Optical Radiation RICCARDO DI LIBERTO 10 Dr. R. Di Liberto Fondazione IRCCS Policlinico San Matteo - Pavia Radiance is used to evaluate the exposure level of retina due to the focusing of optical radiation.

11 Module 1.2 Optical Radiation RICCARDO DI LIBERTO 11 Dr. R. Di Liberto Fondazione IRCCS Policlinico San Matteo - Pavia Radiant Exposure may quantify the exposure effect integrated over time giving the risk level.

12 Angular subtense = Module 1.2 Optical Radiation RICCARDO DI LIBERTO 12

13 Ω = A r 2 [sr] Ω Module 1.2 Optical Radiation RICCARDO DI LIBERTO 13

14 fonte: ICNIRP 1997 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. Module 1.2 Optical Radiation RICCARDO DI LIBERTO 14

15 fonte: ICNIRP 1997 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. Module 1.2 Optical Radiation RICCARDO DI LIBERTO 15

16 ELVs Module 1.2 Optical Radiation RICCARDO DI LIBERTO 16

17 I limiti di esposizione Module 1.2 Optical Radiation RICCARDO DI LIBERTO 17

18 I limiti di esposizione Module 1.2 Optical Radiation RICCARDO DI LIBERTO 18

19 I limiti di esposizione Module 1.2 Optical Radiation RICCARDO DI LIBERTO 19

20 I limiti di esposizione Module 1.2 Optical Radiation RICCARDO DI LIBERTO 20

21 I limiti di esposizione Some ELV are expressed as effective quantities. Effective irradiance E eff Effective radiant exposure H eff Effective radiance L B, L R Module 1.2 Optical Radiation RICCARDO DI LIBERTO 21

22 I limiti di esposizione Effective because they take into account biophysical effects depending on wavelenght of optical radiation, through 3 dimensionless spectral weighting factors: S(λ) for UV nm B(λ) for blue-light nm (photochemical effect on eye) R (λ) for visible and IR nm (thermal effect on eye) Module 1.2 Optical Radiation RICCARDO DI LIBERTO 22

23 S(λ) Module 1.2 Optical Radiation RICCARDO DI LIBERTO 23

24 Module 1.2 Optical Radiation RICCARDO DI LIBERTO 24

25 Module 1.2 Optical Radiation RICCARDO DI LIBERTO 25

26 Basic geometric factors for evaluation of radiometric quantities are the following: Z = mean dimension of source = angular subtense of the source = solid angle subtended by the source = angle between perpendicular to source surface and line of sight used for measurement = acceptance angle or FOV (ICNIRP) for the measurement Module 1.2 Optical Radiation RICCARDO DI LIBERTO 26

27 The apparent source must be calculated in the direction of view (cos ) Module 1.2 Optical Radiation RICCARDO DI LIBERTO 27

28 If the line of sight is perpendicular to the source real and apparent dimensions will be identical. Module 1.2 Optical Radiation RICCARDO DI LIBERTO 28

29 Angular subtense ( ) Module courtesy 1.2 Optical of Radiation E. Galbiati RICCARDO DI LIBERTO 29

30 Fattori geometrici ( ) Dimension of Retinal image 1,7 mrad 30 µm 11 mrad 200 µm 100 mrad 1,7 mm Module 1.2 Optical Radiation RICCARDO DI LIBERTO 30

31 Fattori geometrici ( ) For thermal retinal damage, VLE are calulated taking into account of retinal image and exposure time Dimension of Retinal image 1,7 mrad 30 µm: t exp < 10 s 11 mrad 200 µm: t exp s 100 mrad 1,7 mm: t exp > 100 s Module 1.2 Optical Radiation RICCARDO DI LIBERTO 31

32 Fattori geometrici ( ) Sources > 11 mrad are considered extended or not point sources for non-coherent optical radiation. Module 1.2 Optical Radiation RICCARDO DI LIBERTO 32

33 Fattori geometrici ( ) Module 1.2 Optical Radiation RICCARDO DI LIBERTO 33

34 Fattori geometrici ( ) Circular sources = d/d d D Module 1.2 Optical Radiation RICCARDO DI LIBERTO 34

35 Fattori geometrici ( ) Non circular sources: mean of max linear dimensions. X = (X + Y)/2 D Y D Module 1.2 Optical Radiation RICCARDO DI LIBERTO 35

36 TRANSILLUMINATORE A LED Module 1.2 Optical Radiation RICCARDO DI LIBERTO 36

37 LAMPADA A SCARICA PER FOTOTERAPIA Module 1.2 Optical Radiation RICCARDO DI LIBERTO 37

38 LAMPADA A SCARICA LAMPADA A SCARICA A PER FOTOTERAPIA BASSA PRESSIONE UV Module 1.2 Optical Radiation RICCARDO DI LIBERTO 38

39 courtesy of F. Frigerio courtesy of F. Frigerio- Maugeri Foundation - Pavia Module 1.2 Optical Radiation RICCARDO DI LIBERTO 39

40 courtesy of F. Frigerio- Maugeri Foundation - Pavia Module courtesy 1.2 Optical of Radiation F. Frigerio RICCARDO DI LIBERTO 40

41 courtesy of F. Frigerio- Maugeri Foundation - Pavia Module courtesy 1.2 Optical of Radiation F. Frigerio RICCARDO DI LIBERTO 41

42 courtesy of F. Frigerio- Maugeri Foundation - Pavia Module courtesy 1.2 Optical of Radiation F. Frigerio RICCARDO DI LIBERTO 42

43 courtesy of F. Frigerio courtesy of F. Frigerio- Maugeri Foundation - Pavia Module 1.2 Optical Radiation RICCARDO DI LIBERTO 43

44 Module courtesy 1.2 Optical of Radiation F. Frigerio RICCARDO DI LIBERTO 44

45 Occupational Health & Safety NETworking in EASTern Europe Thank You for your kind attenion!. Module 1.2 Optical Radiation RICCARDO DI LIBERTO 45