A therapeutic laser apparatus comprising: an encasement adapted to be hand-held; a base assembly (21, 31) in the encasement, the base assembly comprising a laser diode (20, 30, 40, 61) configured to generate a monochromatic laser beam and the base assembly being configured to emit a diverging laser beam; and at least two head assemblies removably enagageable with the base assembly, each head assembly comprising: a lens mount (22, 38) having an axial dimension; and a collimating lens (23, 37, 64) on the lens mount configured to create an approximately coherent, collimated final beam; the axial dimension of the lens mount of a first one of the head assemblies being different from the axial dimension of the lens mount of a second one of the head assemblies, and a size of the collimating lens of the first one of the head assemblies being different from a size of the collimating lens of the second one of the head assemblies; when the first one of the at least two head assemblies is engaged with the base assembly, the collimating lens of the first head assembly intercepting, at a first distance from the base assembly, the diverging beam emitted from the base assembly, and when the second one of the at least two head assemblies is engaged with the base assembly, the collimating lens of the second head assembly intercepting, at a second distance from the base assembly different from the first distance, the diverging beam emitted from the base assembly; when in use with the base assembly, the first head assembly creating a first collimated final beam having a lateral beam dimension different from a corresponding lateral beam dimension of a second collimated final beam created by the second head assembly when in use with the base assembly. an encasement adapted to be hand-held; a base assembly (21, 31) in the encasement, the base assembly comprising a laser diode (20, 30, 40, 61) configured to generate a monochromatic laser beam and the base assembly being configured to emit a diverging laser beam; and at least two head assemblies removably enagageable with the base assembly, each head assembly comprising: a lens mount (22, 38) having an axial dimension; and a collimating lens (23, 37, 64) on the lens mount configured to create an approximately coherent, collimated final beam; a lens mount (22, 38) having an axial dimension; and a collimating lens (23, 37, 64) on the lens mount configured to create an approximately coherent, collimated final beam; the axial dimension of the lens mount of a first one of the head assemblies being different from the axial dimension of the lens mount of a second one of the head assemblies, and a size of the collimating lens of the first one of the head assemblies being different from a size of the collimating lens of the second one of the head assemblies; when the first one of the at least two head assemblies is engaged with the base assembly, the collimating lens of the first head assembly intercepting, at a first distance from the base assembly, the diverging beam emitted from the base assembly, and when the second one of the at least two head assemblies is engaged with the base assembly, the collimating lens of the second head assembly intercepting, at a second distance from the base assembly different from the first distance, the diverging beam emitted from the base assembly; when in use with the base assembly, the first head assembly creating a first collimated final beam having a lateral beam dimension different from a corresponding lateral beam dimension of a second collimated final beam created by the second head assembly when in use with the base assembly.