Circular polarizer filters...quite different from traditional variable ND filter??

Started Jan 10, 2013 | Discussions thread
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Re: Reverse the front one...
In reply to Joseph S Wisniewski, Jan 12, 2013

Joseph S Wisniewski wrote:

That's linear polarization. There's a second kind of polarization, circular. You can turn linear into circular by altering the phase relationships between the electrical and magnetic parts of the wave.

Joe, with all due respect the last statement is incorrect. To change from linear to circular polarization you change phase relationships between two components of the electric field without paying attention to magnetic field (Maxwell equations allow you to recover H from E or E from H in a EM wave). Here is a simple thought experiment. Consider a plain EM wave propagating along Z-axis in free space. Electric field being perpendicular to Z could have components along X and Y. If those components are at the same phase you get linear polarization. If X and Y components have a relative phase shift then you have circular pol. The magnetic filed in an E-M wave is uniquely determined from electric field by means of Maxwell equations and is at 90 degrees angle to electric field at all times.


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