A Solution of the Dazzle Problem?
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AN impressive demonstration was recently given in London by Polaroid Products, Ltd., of the application of polarized light in several industrial branches. The glare problem was tackled most convincingly.
In a long room, two pairs of headlamps were arranged, facing each other. Below one pair a number plate
was placed. Above the other, two Polaroid screens were pivoted, so that when the headlamps were switched on the observer could compare the dazzle effects both through the Polaroid screen and without it.
In the latter instance, dazzle was pronounced. When the screen was in use, the dazzle was cut out entirely, no
eye strain was noticeable and the number plate was clearly legible at a distance of 30 ft.
In discussing the commercial possibility of Polaroid, Mr. George Wheelwright, who has worked with the actual inventor, Mr. E. H, Land, of Boston, Mass., U.S.A., pointed out that although polarized light has been known since 1669, it is only as 'a result of the new system that it became an economic possibility. Previously, light could he polarized only by large and expensive crystals.
Now, under the Polaroid method, infinitely small crystals are suspended in a suitable medium (cellulose acetate) in quantities in the region of
1012 to the sq. in. This matrix is
held between thin sheets of plate glass, so that it has certain shatter-proof qualities, resembling safety glass in formation. It is claimed that by using Polaroid, polarization is 99.5 per cent. complete.
Put in the simplest language, polarization is a method of controlling light, particularly in its specular form, which is responsible for most of the dazzle effects. Thus, a fish bowl with a light shining on the surface at such an angle that nothing below it can be seen, owing to surface dazzle, is revealed in its full depth through a Polaroid screen, the fish becoming clearly visible.