From: "Richard F.L.R. Snashall" 
To:  atm{at}shore.net
Reply-To: "Richard F.L.R. Snashall" 




Anthony Stillman wrote:

>
>
> THE MATH
>
> The focal length of the first and second element of a dialyte are given by:
>
> f1 = F( 1 - V2/(V1(1-k)) )
>
> f2 = F(1-k)( 1 - V1(1-k)/V2 )
>
> The secondary color of a dialyte is given by:
>
> delta F / F =  (1-k) * (P1 - P2)  /  (V1*(1-k) - V2)
>
>
> where:
>  k = d / f1
>

Thank you for this.  It is interesting too that, if the flint element is
first, the conclusion still holds, as k < 0.

                Rick S.

>  F  the effective focal length of the system
>  V1 the Abbe number of the first element
>  V2 the Abbe number of the second element
>  P1 the partial dispersion of the first element
>  P2 the partial dispersion of the second element
>  d  the separation of the elements
>

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