An apparatus and method to apply photo-stimulation, photo-dynamic therapy and/or ablation laser treatment to biological tissue. The apparatus includes a plurality of radiation energy sources, preferably laser beams. Additionally, the apparatus allows either a single wavelength or a combination of various wavelengths, either coincidentally or adjacently, to be utilized to achieve a desired treatment effect. Laser beams are transmitted to the treatment area by one or more fiber optic cables which terminate at an assembly structured to collimate the emitted radiation prior to application to the tissue. In addition, the apparatus includes a focal length setting mechanism which assures that a constant, fixed distance exists between the point of discharge of the laser beam and the biological tissue, thus assuring a constant energy density at the point of application. A method is presented for applying photo-stimulation, photocollagen stimulation and/or ablation laser treatment utilizing the above apparatus.