Physics · Ch 6 — Optics
Plane and Partially Polarised Light
Plane and Partially Polarised Light
In plane polarised light, the transmitted intensity through a rotating analyser varies all the way from a maximum down to exactly zero, once every of rotation, because the vibrations are fully allowed along one axis and fully blocked along the perpendicular axis. In partially polarised light, the transmitted intensity instead varies only between a maximum and some non-zero minimum for every of rotation, because the light is not fully restricted to that particular axis -- some intensity still leaks through even at the least-favourable analyser orientation. This difference in how the minimum intensity behaves (reaching exact zero, or …
What this figure shows. Two polar-style intensity plots as an analyser is rotated through a full circle. Panel (a), for genuinely plane polarised incident light, shows the transmitted intensity swelling out to a sharp maximum along one axis and shrinking all the way down to exactly zero along the perpendicular axis, repeating this maximum-to-zero swing every 90 degrees. Panel (b), for partially polarised incident light, shows the same general lobed shape but with the intensity only dipping down to some non-zero minimum value rather than vanishing completely -- because the light is not fully restricted to a single vibration direction, some intensity always leaks through …