Accurate calculations of electrostatic potentials for cylindrically symmetric lenses

Improved methods are described for determining electrostatic potentials within cylindrically symmetric lenses. At fixed number of mesh points, increases in the obtainable precision of approximately a factor of 100 are found by using the present relaxation method. This type of improvement in the precision implies decreases in computational times of a factor of approx. 104 when compared with previous relaxation techniques for equivalent precisions