Abstract: A laser treatment device provides an output operating laser beam having a single wavelength which is highly absorbed by tissue of a patient and which beam is non-diverging. The laser treatment device may be a catheter which is inserted into a patient for performing endovascular myocardial revascularization (i.e., creating new channels for blood flow from within the interior of the patient's heart). The use of the highly absorbed wavelength and the non-diverging character of the beam are possible by having a distal laser at a distal end of the catheter. The distal laser is pumped by a source of laser energy supplied by an array of diode lasers and passed along an optical fiber from a proximal end of the catheter.