Abstract: A display system for sensing a finger of a user applied to the display system includes a display panel; a sensor for sensing the finger; a sensing light source configured to emit a first light having a first wavelength W1; and a reflective polarizer disposed between the display panel and the sensor. For a substantially normally incident light, an optical transmittance of the reflective polarizer versus wavelength for a first polarization state has a band edge such that for a first wavelength range extending from a smaller wavelength L1 to a greater wavelength L2 and including W1, where 30 nm?L2?L1?50 nm and L1 is greater than and within about 20 nm of a wavelength L3 corresponding to an optical transmittance of about 50% along the band edge, the optical transmittance has an average of greater than about 75%.

Abstract: A mixture of an aluminous ore and a carbon source is dried and calcined in the presence of a sulfur-containing compound. The mixture is then chlorinated to produce crude metal chlorides. Aluminum chloride is condensed and separated from the remaining metal chlorides, combined with sulfur and aluminum powder, and sublimated and desublimated so as to produce substantially pure aluminum chloride.