From: Nickhutsl{at}aol.com
To: atm{at}shore.net
Reply-To: Nickhutsl{at}aol.com



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In a message dated 12/28/2002 10:10:50 PM Central Standard Time,
mdholm{at}telerama.com writes:

> Richard F.L.R. Snashall
   Mark Holm
I was taught that the reflection at the interface of the coating and the
lens depends on two conditions.
   First that the amount of light reflected from the coating should equal
that from the lens. IOW The waves should be equally "high"
   Second, that the wave of light reflected from the coating should cancel
the wave reflected from the lens. IOW The "crest" of one wave
should meet the "though" of the other.
  The first condition is met if the index of refraction of the coating is
equal to the square root of the index of the lens. ( When the lens is in
air, which index is nearly unity)
  The second is met if the thickness of the coating is equal to an odd number
of quarter wavelengths i.e.: 1/4 lamda, 3/4 lamda, 5/4 lamda etc. Nick Hutsell

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In a message dated 12/28/2002 10:10:50 PM Central
Standard Time, mdholm{at}telerama.com writes:

Richard F.L.R.
Snashall
   Mark Holm
I was taught that the reflection at the interface of the coating and the
lens depends on two conditions.
   First that the amount of light reflected from the coating should
equal that from the lens. IOW The waves should be equally "high"
   Second, that the wave of light reflected from the coating should
cancel the wave reflected from the lens. IOW The "crest" of one
wave should meet the "though" of the other.
  The first condition is met if the index of refraction of the coating is
equal to the square root of the index of the lens. ( When the lens is in
air, which index is nearly unity) 
  The second is met if the thickness of the coating is equal to an odd
number of quarter wavelengths i.e.: 1/4 lamda, 3/4 lamda, 5/4 lamda
etc. Nick Hutsell  

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