Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 exptools 1/6/84; site ihuxq.UUCP Path: utzoo!watmath!clyde!burl!ulysses!harpo!ihnp4!ihuxq!ken From: ken@ihuxq.UUCP (ken perlow) Newsgroups: net.physics Subject: Re: Haloes on fogged-up glass... Message-ID: <720@ihuxq.UUCP> Date: Wed, 29-Feb-84 11:20:33 EST Article-I.D.: ihuxq.720 Posted: Wed Feb 29 11:20:33 1984 Date-Received: Fri, 2-Mar-84 07:28:40 EST References: <1201@ucf-cs.UUCP> Organization: AT&T Bell Labs, Naperville, IL Lines: 24 -- >>> Partly in consequence of seeing the haloes around the sun last week, I >>> noticed that street lights seen through a fogged-up car windshield have >>> a colored halo. The strange thing was that there were areas of color, >>> with no apparent order to where a particular color occured. >>> My question, should anyone decide to accept it, is: >>> What causes the light to be broken up into colors? A foggy (pun intended) recollection from a 1960's vintage optics class: Babinet's Principle. I can't even remember what it is, although it involves diffraction through multiple holes, and an equivalence between such a situation and its logical inverse (multiple points). I do remember that haloes through foggy glasses was the demonstration of Babinet's Principle. (If I still had the text, I'd restate the thing.) -- *** *** JE MAINTIENDRAI ***** ***** ****** ****** 29 Feb 84 [10 Ventose An CXCII] ken perlow ***** ***** (312)979-7261 ** ** ** ** ..ihnp4!ihuxq!ken *** ***