I'm taking an optics lab in which I'm required to construct an interferometer, and measure the wavelength of a laser, and the coherence length of the light emitted from a candle fire.
Now, I've been hinted by my instructor that when working with mirrors (which are present in an interferometer), it is best to make sure that the laser is polarized to either "P" or "S" polarization - otherwise, the mirrors might give an elliptic component to the polarization, which in turn will spoil the measurment, due to interference effects.
So now comes the question: should the light from the candle be polarized as well??
I have a reason to suspect that polarizing it will improve the coherence length, and on the other hand, I'm pretty sure that elliptical polarization will take effect if the light remains untouched.
What is your opinion on this dilemma?? Thanks!!