Re: [ATM] Diffusers

["Bob May" <rmay@nethere.com>]

Back wehn light bulbs were used, the small ones were often of a
clear bulb so the filament showed through the glass.   More
typical of earlier bulbs than today but the flashlight bulbs are
still of clear glass, often including a small lens on the end to
focus the light ot a smaller cone.  As a result, it was noticed
quickly that sometimes the light would be strong and other times,
the light would be weak.  A diffuser at the KE made this problem
go away as the light wass diffused to all angles needed at a very
even level.  What was happening was that the filament would be
seen by the surface and thus the light level would be uneven and
thus distracting to the user of the tester.  LEDs are a fairly
even source across the die of the LED so they really don't have
the same problem as a filament all woulnd up would have.  In
addition, the filament would be some distancee behind the KE so
its light cone would not be that great and fast mirrors would not
be evenly illuminated across their face.  Basically the same
problem as ont getting your eye close enough to the KE to see the
light all across the surface of the mirror.
Bob May

rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net


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