The invention is directed to a laser catheter (1) for bypass surgery, wherein the distal part (2) of the catheter (1) is provided with: a tubular arrangement (3) of optical fibers (4) having distal ends (5) defining a ring-shaped light emergence surface (6) for emitting a tubular bundle of light beams in the distal direction (D) of the catheter (1); and a stop surface (7) extending around the tubular arrangement (3) of optical fibers (4) and facing in the distal direction (D), the stop surface (7) being arranged at a distance (A) proximally from the light emergence surface (6). The light emergence surface (6) slants at a slanting angle (α) in the range of [20°, 60°] with respect to the longitudinal axis (8) of the catheter (1). The invention further relates to an assembly comprising such a catheter.