Additional Study Information: The purpose of this study is to gather data about the safety and effectiveness of a new, investigational device (not FDA approved), the Thor laser atherectomy system (Thor system), for the treatment of peripheral artery disease (PAD). When there is a blockage (a deposit on an artery wall, made of fat or calcium, and/or blood clots) in one or more of your leg arteries, you may have little or no blood flow to your leg. The study procedures begin with signing the research consent and collection of your medical records, a physical exam, blood tests, questionnaires about your quality of life, and have an angiography and ultrasound. You will undergo PAD surgery using the Thor laser atherectomy system. The Thor systems laser produces bursts of ultraviolet (UV) light energy which vaporize (remove) blockages in the arteries (atherectomy). The Thor system produces sonic waves like an ultrasound machine (sonic disruption) that can break up the calcified plaque in the artery (calcium modification). Removing calcified plaque can restore elasticity to the artery. Atherectomy and Calcium Modification Procedure: If your doctor decides that your blockage(s) meets the study criteria, you will receive treatment with the Thor system. Your doctor may inflate a small balloon in your artery (balloon angioplasty). Once the Thor system is inserted, it will be placed near the blocked area in your artery, and a laser atherectomy will be performed using the standard method. Then the doctor will perform the calcium modification procedure considered an experimental technique (where the Thor system makes sonic waves like an ultrasound machine). The calcium modification procedure may break up the hardened, calcified plaque in the artery. Your doctor may continue with more balloon angioplasty and/or stenting. If you were treated with the Thor system, your health will be watched until you are ready to go home. You will need to come in for follow-ups at 30 days, 6 months, and 1 year.