Lecture 52 | 3rd Semester | Dichroism | Wire Grid Polarizer | Polarization by Absorption

This lecture, part of a series for undergraduate physics students, focuses on polarization by absorption, also known as dichroism. The instructor explains that certain materials, like tourmaline crystals, exhibit selective absorption of light based on its polarization state. The lecture details how unpolarized light can be decomposed into two orthogonal components, and how a dichroic material absorbs one component while transmitting the other, resulting in linearly polarized light. The concept is illustrated with the example of a tourmaline crystal. The lecture then introduces the wire grid polarizer as an artificial dichroic device, explaining its construction and principle of operation. The spacing between the wires must be smaller than the wavelength of light for effective polarization. The limitations of wire grid polarizers for visible light are discussed, leading to the development of the H-sheet polaroid, which uses aligned polymer chains doped with iodine to achieve polarization. The lecture concludes by highlighting the effectiveness of polaroid sheets in producing polarized light.