--14--

Note to fig.6 SCHEME OF THE CONE OF LIGHT BETWEEN SECONDARY AND FOCUS in the coma free device

y2s > y2m

It is Page 14 Equation 1 and Page 14 Equation 2
It must be a) Page 14 Equation 3
therefore b) Page 14 Equation 4

Being Page 14 Equation 5 the convergence Um of the meridional rays in F′m and Page 14 Equation 6 the convergence Us of the saggital rays in F′s, we get c) Page 14 Equation 7 since Page 14 Equation 8 and Page 14 Equation 9 we can write formula c) d) Page 14 Equation 10 Formula d) soluted for a1m will then give our formula 18) Equation 18 version 2 q.e.d.

In fig.6 is shown that, if the corrector is placed in the plane X, ( y3m = y3s ), the final convergence of the meridional rays U1m equals the final convergance Us of the saggital rays, i.e., Fm and Fs are equalized and the astigmatical difference of focal- lengths is eliminated.