METR 415/715 Wednesday February 6 2013. Imaginary part of index of refraction When n i is non-zero,...
-
Upload
hector-welch -
Category
Documents
-
view
216 -
download
0
description
Transcript of METR 415/715 Wednesday February 6 2013. Imaginary part of index of refraction When n i is non-zero,...
![Page 1: METR 415/715 Wednesday February 6 2013. Imaginary part of index of refraction When n i is non-zero, absorption of an EM wave occurs as it passes through.](https://reader036.fdocuments.in/reader036/viewer/2022082602/5a4d1b8b7f8b9ab0599bedfa/html5/thumbnails/1.jpg)
METR 415/715
Wednesday February 6 2013
![Page 2: METR 415/715 Wednesday February 6 2013. Imaginary part of index of refraction When n i is non-zero, absorption of an EM wave occurs as it passes through.](https://reader036.fdocuments.in/reader036/viewer/2022082602/5a4d1b8b7f8b9ab0599bedfa/html5/thumbnails/2.jpg)
Imaginary part of index of refraction
• When ni is non-zero, absorption of an EM wave occurs as it passes through a medium.
• ni is sometimes referred to as the absorption index
• ni depends on the wavelength
• Figure 4.1 (page 77) shows values of ni for water and ice – small for visible and higher for UV and IR
![Page 3: METR 415/715 Wednesday February 6 2013. Imaginary part of index of refraction When n i is non-zero, absorption of an EM wave occurs as it passes through.](https://reader036.fdocuments.in/reader036/viewer/2022082602/5a4d1b8b7f8b9ab0599bedfa/html5/thumbnails/3.jpg)
Intensity as a function of travel through a medium
• Eq 4.2, p.77• Βa= absorption coefficient
![Page 4: METR 415/715 Wednesday February 6 2013. Imaginary part of index of refraction When n i is non-zero, absorption of an EM wave occurs as it passes through.](https://reader036.fdocuments.in/reader036/viewer/2022082602/5a4d1b8b7f8b9ab0599bedfa/html5/thumbnails/4.jpg)
Intensity as a function of travel through a medium
• Eq 4.3, p.77
![Page 5: METR 415/715 Wednesday February 6 2013. Imaginary part of index of refraction When n i is non-zero, absorption of an EM wave occurs as it passes through.](https://reader036.fdocuments.in/reader036/viewer/2022082602/5a4d1b8b7f8b9ab0599bedfa/html5/thumbnails/5.jpg)
Transmittance t• The fraction of radiation intensity that survives
the trip over the distance x.• The fraction that was NOT transmitted must
have been absorbed and thereofre converted to another form of energy such as heat
![Page 6: METR 415/715 Wednesday February 6 2013. Imaginary part of index of refraction When n i is non-zero, absorption of an EM wave occurs as it passes through.](https://reader036.fdocuments.in/reader036/viewer/2022082602/5a4d1b8b7f8b9ab0599bedfa/html5/thumbnails/6.jpg)
Beer’s Law
• The intensity of a beam of monochromatic radiation falls off exponentially as it traverses a uniform medium
• The rate at which it falls off is proportional to βa
![Page 7: METR 415/715 Wednesday February 6 2013. Imaginary part of index of refraction When n i is non-zero, absorption of an EM wave occurs as it passes through.](https://reader036.fdocuments.in/reader036/viewer/2022082602/5a4d1b8b7f8b9ab0599bedfa/html5/thumbnails/7.jpg)
Penetration Depth
• Defined as the value of x for which t(x) = e-1 or approximately 37%• Check Figure 4.2 on page 79 for water and ice• How does that influence color of pools water? Light penetration into the ocean?