Forest ElemPhysics Optics ThinFilms

Prperties of Refection and Refraction

1.) Waves reflect from higher index of refraction materials will have a half wave shift.

2.) Frequency of light stays the same no matter what the medium change

3.) The wavelength of light changes with the index of refraction.

[math]n \equiv \frac{c}{v}[/math]

[math]\frac{\lambda_0} {\lambda} = \frac{v_o/f}{v/f} = \frac{n}{n_0} = n : n_0 =1 if air[/math]

Thin Film Applet

http://physics.bu.edu/~duffy/semester2/c26_thinfilm.html

Thin Film of MgF2 on glass

1.) [math]n_{air} = 1 \lt n_{MgF2} = 1.38 \lt n_{glass} = 1.5[/math]

This means that reflection on all the interfaces will have a half wavelength [math](\pi)[/math] phase shift because wave is reflected from a higher index of refraction both times.

2.) The wavelength shortens each time.

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