Home | Methods | Compensator | Lambda Plate | Fringes |

First polariser at 45 degrees with the main stress axis | Sample which gives difference in phase | Quarter-wave plate | Rotating Analyser at angle set to f / 2 radians relative to -45 degree |

The inserted quarter-wave plate adds a phase shift of 90 degrees to the parallel direction. As a result, the light becomes linear polarised at angle of f / 2 radians relative to the original position of the Analyser. So a crossed linear polariser should give a resulting intensity of zero. When the Analyser is rotated till the intensity in a certain point is zero, the phase-shift in that point is equal to 2 times the rotation angle.

The light vectors at the different stages are:

After polariser at +45: EyA = sin( w t) ExA = sin( w t) |
After Sample EyB = sin( w t) ExB = sin( w t + f ) |
After Quarter-wave plate: |
After Analyser at -45+f/2: EyD = 0 ExD = 0 |