A high power laser diode comprising a plurality of laser light emitters, a plurality of light collimating means, a planar substrate means (10, 30), and a common heatsink, each of said laser light emitters defining, in a direction perpendicular to a direction of propagation of a respective output laser beam, a fast axis (y) and a slow axis (x), and each of said light collimating means being associated with a laser light emitter and configured for collimating said output laser beam at least in a fast axis (y) direction, characterised in that: said planar substrate means comprises a planar alignment substrate and a planar spacer plate disposed on top of and in parallel to said planar alignment substrate, said planar spacer plate having a first surface and a second surface that are parallel to each other, said planar alignment substrate comprises a plurality of cut-outs and a plurality of stops (18, 20, 26), said stops being provided as protrusions on the surface of said planar alignment substrate and/or as a respective edge of said cut-outs; by abutment of a respective laser light emitter or of a respective submount with the plurality of stops said plurality of laser light emitters are aligned to each other such that the optical axis of said laser light emitters are parallel to each other and a predetermined distance in fast axis direction between said laser light emitters is defined; and said first and second surface (300, 301) of said planar spacer plate extends perpendicular to said direction of propagation, said first surface abuts to a planar spacer alignment surface (21, 27) of said planar alignment substrate, which is perpendicular to said direction of propagation, and said second surface abuts to a plane rear side of said collimating means, so that a thickness of said planar spacer plate precisely defines a distance between a respective laser light emitter and an associated light collimating means, wherein each of said laser light emitters is mounted on a submount, said submounts being mounted on said heatsink at predetermined spacings in fast axis direction, and said heatsink further comprising beam deflecting means for deflecting said respective output laser beams toward said collimating means. said planar substrate means comprises a planar alignment substrate and a planar spacer plate disposed on top of and in parallel to said planar alignment substrate, said planar spacer plate having a first surface and a second surface that are parallel to each other, said planar alignment substrate comprises a plurality of cut-outs and a plurality of stops (18, 20, 26), said stops being provided as protrusions on the surface of said planar alignment substrate and/or as a respective edge of said cut-outs; by abutment of a respective laser light emitter or of a respective submount with the plurality of stops said plurality of laser light emitters are aligned to each other such that the optical axis of said laser light emitters are parallel to each other and a predetermined distance in fast axis direction between said laser light emitters is defined; and said first and second surface (300, 301) of said planar spacer plate extends perpendicular to said direction of propagation, said first surface abuts to a planar spacer alignment surface (21, 27) of said planar alignment substrate, which is perpendicular to said direction of propagation, and said second surface abuts to a plane rear side of said collimating means, so that a thickness of said planar spacer plate precisely defines a distance between a respective laser light emitter and an associated light collimating means, wherein each of said laser light emitters is mounted on a submount, said submounts being mounted on said heatsink at predetermined spacings in fast axis direction, and said heatsink further comprising beam deflecting means for deflecting said respective output laser beams toward said collimating means.