Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!pasteur!ucbvax!decwrl!spar!snjsn1!bilbo!greg
From: greg@bilbo (Greg Wageman)
Newsgroups: sci.electronics
Subject: Re: Seeing UV
Message-ID: <230@snjsn1.SJ.ATE.SLB.COM>
Date: 11 May 88 23:33:53 GMT
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Reply-To: greg%sentry@spar.slb.com (Greg Wageman)
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In article <685@eos.UUCP> jbm@eos.UUCP (Jeffrey Mulligan) writes:
>+ But what makes me curious is that every "black light" I've ever seen
>+ has a peculiar quality to it that I never see in any other kind of
>+ illumination. Hard to describe but it looks very specular, somewhat
>+ like laser illumination of normal surfaces, and it always looks a little
>+ fuzzy, possibly as if it were out of focus. When I ask other people if
>+ they perceive anything like this, they look at me funny.
>
>Ultraviolet radiation causes the lens of the eye to flouresce.
>This would produce a diffuse illumination of the entire retinal image,
>but the effect would probably be more of a soft-focus effect,
>(sharp edges with a fuzzy overlay) rather than out and out blurring.

The above may very well be true, but...

Different wavelengths of light also refract to different degrees
through the same material (e. g. a prism, or the lens of your eye.)
Your eye does what it normally does to bring an image into focus under
wide-spectrum lighting conditions.  But since "UV" is at the extreme end
of the visible spectrum (actually what you are seeing is the extreme
deep violet visible portion), its refraction will be far enough from
the correct focal point that it will indeed be out of focus.


Greg Wageman             	ARPA: greg%sentry@spar.slb.com
Schlumberger Technologies	BIX:  gwage
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