A calcite rhomb rests on a page over the single printed letter O
PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Polarisation and anisotropic media · Polarisation and anisotropic media
Optics and Photonics, Ch Birefringence and crystal optics
Problem
A calcite rhomb rests on a page over the single printed letter O. Looking down through the rhomb, two images of the letter are seen: image P directly below the original letter, and image Q displaced to the right of P. A polaroid sheet is placed above the rhomb and rotated: with the polaroid's transmission axis vertical, image Q disappears and only P remains; with the transmission axis horizontal, image P disappears and only Q remains. The rhomb is then tilted (the page kept still): image P stays exactly where it was, exactly as a plate of ordinary glass would behave, while image Q slides further to the right as the tilt increases.
((a)) Which image, P or Q, is the ordinary image? Justify your answer from the tilt test.
((b)) State the polarisation direction (vertical or horizontal) of the field in the ordinary image.
((c)) The two images are displaced from one another along the horizontal (left-right) direction. State the direction in which the optic axis is projected onto the top face of the rhomb, and explain the reasoning that connects this to the displacement of Q.