  The robust method for obtaining the helical interference pattern due to the
phase-conjugation of an isolated optical vortex by means of the non-holographic
technique is proposed. It is shown that a perfect wavefront-reversal of the
vortex in a linear polarization state via even number of reflections is
achievable due to the turn of the photon's momentum $\vec p \approx \hbar \vec
k$ with respect to the photon's orbital angular momentum projection $L_z$. The
possible experimental realization is based upon $catseye-prism$ like
reflections inside the confocal optical $loop$ cavity. The alternative scheme
contains the Dove prism embedded in the optical $loop$ with the odd number of
reflections from mirrors. This $confocal$ interferometric technique is
applicable to the optical tweezers, atomic traps, Sagnac laser loops and
metamaterials fabrication.
