  A method for calculating the meridian profile of the aspherical surface of a
plane-convex lens excluding spherical aberration, without calculating the
coefficients of the series, by direct solving the compiled differential
equation is proposed. The differential equation of an aspherical lens was
compiled, found its numerical solution, and got the meridian profile of an
aspherical lens. For long-focus lenses found conditions to simplify the
differential equation.
