Re: Refraction and Dispersion-phase contrast

Posted by mmodel on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Refraction-and-Dispersion-phase-contrast-tp7579532p7579533.html

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Hi Claire - the speed of light does change but the eye responds only to frequency, it doesn't know anything about wavelength. And the frequency remains the same throughout all transformations of the wave.

Mike

-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Claire Brown, Dr.
Sent: Monday, January 21, 2013 1:30 PM
To: [hidden email]
Subject: Refraction and Dispersion-phase contrast

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I am teaching a class on light microscopy and have two questions:

1) If higher refractive indices materials slow down the speed of light does the wavelength also change so that frequency and energy are conserved? If this is true does is the wavelength shift so small that the colour does not change a great deal? The other explanation I had is that the speed of light never changes but short wavelengths take longer to travel through high NA materials because they interact with the material and travel along a longer path to reach the other side of the material. So the speed does not change, the wavelength does not change but the light takes longer to get through the material.

2) Does diffracted light shift by exactly 1/4 a wavelength in phase from incident light? If so why is it exactly 1/4 of a wavelength?

Sorry for my basic questions but these sometimes seem harder to explain and understand than more complex concepts.

Sincerely,

Claire