The invention relates to a projection lens assembly for directing a beam toward a target. This assembly includes a lens support body (52) that spans a plane (P), and has a connection region (58) and a lateral edge (56). The lens support body is arranged for insertion into a frame (42) of a processing unit along an insertion direction (X) parallel with the plane (P). The projection lens assembly includes conduits (60-64) emanating from the connection region, and a conduit guiding body (70-81) for accommodating the conduits. The guiding body includes a first guiding portion (72) for guiding the conduits from the connection region, along the plane to a lateral region (B) beyond the lateral edge. The guiding body also includes a second guiding portion (78) for guiding the conduits from the lateral region (B) toward a tilted edge (79) of the conduit guiding body.