To simulate a Ronchigram of a conic surface an exact ray tracing is done by using the formula

from point source (α, β, γ) to observation Z_ob, and Ronchi ruling, Z_Rr planes.

Then the irradiance on the observation planeis calculated by applying

In the equation we used that the second term of the Fourier series of the Ronchi ruling trasnmittance is positive if transmittance is equal to one and it is negative if the transmittance is equal to cero in Ronchi ruling plane.