“…In the first column of figure 4, we present other example of H(t, s) of equation (10), but now with a virtual image. At the left side: (top) we show the ray tracing; (centre) the wavefronts; (bottom) both rays and wavefronts [20][21][22]. To plot the eikonals when the object is virtual, we still apply equations (2)-( 5) but we slight modify H(t, s) as follows where = + R Ta nT and the conditions become…”