Prism Glare Shield Reduces Night Driving Hazards (Feb, 1932)
Source: Modern Mechanix ( More articles from this issue )
Issue: Feb, 1932
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Prism Glare Shield Reduces Night Driving Hazards
CONSISTING of two finely polished optical glass prisms set in a metal mounting, this device is designed to serve as a glare eliminator for automobiles. Fastened over the windshield, it is perfectly transparent so that the driver can clearly see the road. Startling as it may seem, however, on the approach of another car with glaring headlights the device immediately lowers an “optical curtain” so that the oncoming car and lights vanish and the driver can see as clearly as ever.
Optically the device consists of two accurately ground and highly polished prisms, which are mounted with a minute air film intermediate of the two prisms. When driving at night the brilliant light of an approaching car strikes the eliminator and the dazzling rays are immediately refracted by the prisms, causing a dense, shadowy curtain to drop and shield the eyes.
Aside from the practicality of this device, can anyone explain how it could work? It almost looks like a beam splitter.
Comment by Slim — May 19, 2008 @ 9:25 am
It’s probably an early polarizer? At the same time Edwin Land was still working with polarizing film he had invented: http://en.wikipedia.org/wiki/Edwin_H._Land
Comment by Tõnu — May 19, 2008 @ 11:27 am
Even if it was a polarizer, the lights of an oncoming car are not polarized — only oblique reflections are polarized. So that’s not how it works.
I don’t think it works. That is, I don’t see any way that it can reflect a different percentage of oncoming-headlights glare than of other kinds of things you want to be able to see.
Comment by mc — May 19, 2008 @ 8:25 pm
Still, it would find use in tanks.
Comment by KHarn — May 21, 2008 @ 6:21 am