To evaluate vessel lumen quality (gain) and patient outcomes based on treatment with a predetermined laser treatment protocol in patients presenting with varying lesion types or morphologies: homogenous (plaques with a uniform texture-smooth and regular), heterogeneous (plaques with non-uniform texture-smooth and irregular surface), calcific (consisting of calcium) and restenotic (reoccurring narrowing of the vessel following prior treatment) associated with peripheral arterial disease (PAD).