why does a glass prism disperse white light
Prism Light changes speed as it moves from one medium to another (for example, from air into the glass of the prism). This speed change causes the light to be refracted and to enter the new medium at a different angle (Huygens principle). The degree of bending of the light's path depends on the angle that the incident beam of light makes with the surface, and on the ratio between the refractive indices of the two media (Snell's law). The refractive index of many materials (such as glass) varies with the wavelength or color of the light used, a phenomenon known as dispersion. This causes light of different colors to be refracted differently and to leave the prism at different angles, creating an effect similar to a rainbow. This can be used to separate a beam of white light into its constituent spectrum of colors. A similar separation happens with iridescent materials, such as a soap bubble. Prisms will generally disperse light over a much larger frequency bandwidth than diffraction gratings, making them useful for broad-spectrum spectroscopy. Furthermore, prisms do not suffer from complications arising from overlapping spectral orders, which all gratings have.
Ray-Ban In 1929, US Army Air Corps Colonel John A. Macready worked with Bausch & Lomb, a Rochester, New York-based medical equipment manufacturer, to create aviation sunglasses that would reduce the distraction for pilots caused by the intense blue and white hues of the sky.[3][4][5] Specifically, MacCready was concerned about how pilots' goggles would fog up, greatly reducing visibility at high altitude.[6] The prototype, created in 1936 and known as ‘Anti-Glare’, had plastic frames and green lenses that could cut out the glare without obscuring vision. They also added impact-resistant lenses in 1938.[7] The sunglasses were redesigned with a metal frame the following year and patented as the Ray-Ban Aviator.[6] According to the BBC, the glasses used “Kalichrome lenses designed to sharpen details and minimise haze by filtering out blue light, making them ideal for misty conditions.”[6]