The X-ray Laser Oscillator (XLO) uses LCLS pulses to pump population inversion in  solid copper and lase on the K alpha line, producing fully coherent, transform limit X-ray pulses, opening new avenues for experiments in fields such as inelastic X-ray scattering, parametric down-conversion, quantum science, X-ray interferometry, and coherent imaging. An important component of XLO is a bow-tie cavity to recirculate the X-ray pulses, using Si or diamond crystals as mirrors in a Bragg configuration.  In this proceeding, we report on the XLO optical cavity design and initial measurements, including intracavity focusing, mirrors and lenses alignment. We present and discuss a comparison between the numerical simulations and experimental data.