Re: First-surface mirrors don't polarize, do they?

Paul Ciszek wrote:
So, I was discussing possible sources of polarization in the spectrometer
with the guy who runs the lab, and he thought that mirrors might also
have a polarizing influence. Now, I know that an interface between two
transparent media can act as a polarizer (i.e., Brewster's angle) but I
thought the whole point of a first-surface mirror was that it reflected
almost everything that fell on it, at almost any angle.

(Perhaps I am using the wrong term; I am refering to mirrors that are
metalized on the outside, unlike household mirrors.)

Many commercial first surface mirrors are overcoated with SiO2 (quartz) to protect the surface. Those will have some weak polarization if the reflection isn't perpendicular to the surface. Likewise "uncoated" aluminized mirrors will form a layer of aluminum oxide just by being in air. You may be able to design your instruments so the effects are equal in both polarization axis and effectively neutral. For example, in a Cassegrain telescope the net polarization close to zero as the angles are small and symmetrical about the optical axis. That assumes the mirror surfaces are uniformly reflective.

Certainly most spectroscope designs aren't polarization neutral. That's difficult to archive in either a grating or prism spectroscope unless the light source is actively rotated and integrated.
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Relevant Pages

  • Re: Wang / Sagnac Devices
    ... Reflection with SRT and that has to do with moving mirrors. ... incidence and the angle of reflection to be different for a moving ... the speed of light can occur with the emission theory. ...
    (sci.physics.relativity)
  • Re: Wang / Sagnac Devices
    ... Reflection with SRT and that has to do with moving mirrors. ... incidence and the angle of reflection to be different for a moving ... Sagnac mirrors, there is no change in light speed. ...
    (sci.physics.relativity)
  • Re: Wang / Sagnac Devices
    ... Reflection with SRT and that has to do with moving mirrors. ... incidence and the angle of reflection to be different for a moving ... Sagnac mirrors, there is no change in light speed. ...
    (sci.physics.relativity)
  • First-surface mirrors dont polarize, do they?
    ... I was discussing possible sources of polarization in the spectrometer ... with the guy who runs the lab, and he thought that mirrors might also ... almost everything that fell on it, at almost any angle. ...
    (sci.optics)
  • Re: Polarization and Brewster Angle
    ... confused by my current E/M homework. ... It talks about the Brewster angle ... reflection, yet wikipedia seems to disagree, as does most of the internet: ... So, they say that it is a "polarization" angle, which leads me to another ...
    (sci.optics)