Fig. 1. (a) Coordinate systems for Gaussian beam reflection from a spherical Mirror M; L, incident beam; Lr, reflected beam; (b) simple experiment for comparing TCS and NCS for Gaussian beam reflection; A, incident angles; Li0, arbitrarily chosen incident beam; Lr0, reflected beam of Li0; M0, planar mirror; n, binormals at Point P; P, reflected points; (xi,yi,zi) and (xni,yi,zi), coordinate systems of the incident beam based on the TCS and NCS, respectively; (xr,yr,zr) and (xnr,yr,zr), coordinate systems of the reflected beam based on the TCS and NCS, respectively.