Mass and centroid of rigid lenses

By subdividing a lens design into simpler units it is possible to evaluate its mass and locate its centre of mass (the centroid). The constituent subcomponents form plane sections of the sphere, or, in the case of aspheric lenses, sections of a conicoid. The theory of lens analysis in terms of the conicoidal (and spherical) frustrum is discussed and a BASIC computer program is presented to perform the calculations for spherical multicurve contact lenses.