{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

EMA 3413 Part III review

EMA 3413 Part III review - EMA 3413 Part III review Ch 10...

This preview shows pages 1–3. Sign up to view the full content.

EMA 3413 Part III review Ch. 10. Optical Constants Light (EM) wave o Wavelength range for visible, UV, IR o Photon energy vs. wavelength or frequency: o Propagation of light in medium Photon energy and frequency are the same as in vacuum Speed of light Wavelength Dispersion, i.e. wavelength dependence of ε , n , etc. Reflection and refraction o Snell’s law for refraction: o Total internal reflection: from high index medium to low index medium () Attenuation of light in absorptive medium o Complex dielectric constant: o Complex refractive index: ( called extinction coefficient) o , o If , then , which means material is transparent (no absorption) o Intensity of EM wave attenuates following , where the absorption coefficient and 1/ α is the characteristic penetration depth of the EM wave (or absorption length) Reflection and absorption losses in medium o Reflectance (or reflectivity): o Transmittance (or transmissivity, or transparency): o Absorptance: o 1= R + T + A if assuming no scattering losses o At normal incidence from air to a medium (or vice versa): o Multiple reflections and absorptions: example transmission of light through a mostly transparent medium Ch. 11. Atomistic Theory of the Optical Properties Atomistic (i.e., classical) theory o Motion of electrons is governed by Newton mechanics: charge particles respond to the electromagnetic field (EM optical wave) o Position of electrons is also related to polarization in the medium, from which the dielectric constant can be determined o Whenever there is absorption (), energy from the EM wave is transferred to the electron kinetic energy (motion) Drude model for free electrons o Understand what this model is

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
o Without damping: Plasma frequency: ( N f is the number of free electrons per unit volume), typically in the UV range for metals (~10 15 Hz) At , , and R = 1 (100% reflection for light incident from air to the medium at normal incidence) At , , and R 0 (no reflection and no absorption, everything goes through, i.e.
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 5

EMA 3413 Part III review - EMA 3413 Part III review Ch 10...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online