Apparatus for coating (1; 1'; 1") manufactured articles, such as panels made of wood, fiberglass, ceramic and the like, on which a photosensitive paint is applied beforehand, wherein said manufactured article has an upper surface (Ps), a head surface (Pt), a tail surface (Pc), two side surfaces and a lower surface (Pi), comprising at least one radiation source (41, 61) for the treatment of said photosensitive paint, and a conveying system, wherein said manufactured article is movable on said conveying system in a forward direction, wherein said conveying system comprises at least one optic group (33, 34) having a housing cavity (335, 345), arranged in correspondence of said at least one radiation source (41, 61), wherein said at least one optic group (33, 34) comprises a reflecting member (334, 344) arranged in said housing cavity (335, 345), in correspondence of said radiation source (41, 61), so as to spread its emitted radiation, wherein said reflecting member (334, 344) has a superficial shape so as to spread the incident radiation on said head surface (Pt) and on said tail surface (Pc) when respectively said panel moves towards, and moves away from said housing cavity (335, 345) while it is moved by said conveying system, and wherein said reflecting member (334, 344) has a longitudinal extension that exceeds the width of said manufactured article, and it is arranged transversely with respect to said forward direction of said manufactured article, for spreading the incident radiation on said lateral surfaces of said manufactured article while it passes over said housing cavity (335, 345), characterized in that said reflecting member (334, 344) has one of the following shapes: convex, shaped by two planes arranged to shape an inverted V; concave, shaped by two planes arranged to shape a V; shaped by two curved surfaces joined along a line, so that it has a cusp section. at least one radiation source (41, 61) for the treatment of said photosensitive paint, and a conveying system, wherein said manufactured article is movable on said conveying system in a forward direction, wherein said conveying system comprises at least one optic group (33, 34) having a housing cavity (335, 345), arranged in correspondence of said at least one radiation source (41, 61), wherein said at least one optic group (33, 34) comprises a reflecting member (334, 344) arranged in said housing cavity (335, 345), in correspondence of said radiation source (41, 61), so as to spread its emitted radiation, wherein said reflecting member (334, 344) has a superficial shape so as to spread the incident radiation on said head surface (Pt) and on said tail surface (Pc) when respectively said panel moves towards, and moves away from said housing cavity (335, 345) while it is moved by said conveying system, and wherein said reflecting member (334, 344) has a longitudinal extension that exceeds the width of said manufactured article, and it is arranged transversely with respect to said forward direction of said manufactured article, for spreading the incident radiation on said lateral surfaces of said manufactured article while it passes over said housing cavity (335, 345), characterized in that said reflecting member (334, 344) has one of the following shapes: convex, shaped by two planes arranged to shape an inverted V; concave, shaped by two planes arranged to shape a V; shaped by two curved surfaces joined along a line, so that it has a cusp section.