The present invention relates to devices / systems and methods for the treatment of varicose veins and other vein abnormalities. In one embodiment, the treatment comprises a combination of two wavelengths to effectively occlude the abnormal vein. This wavelength is selected as the effective absorption peak of hemoglobin and water, which is considered to be about 980 nm and 1460 nm, respectively. This vein is targeted at this wavelength to obtain maximal and effective absorption. Near Infra Red Laser radiation is delivered to the blood, collagen and water in the blood vessels, resulting in the closure and contraction of the vein. In this technique, an optical fiber is inserted into the vein and a laser source is used to illuminate the vein. The adjustment mechanism enables delivery of a constant power density based on feedback of the speed of the fiber pullout and local structural vein parameters. This technique is an effective treatment for venous disturbance because the treated vein is targeted to a wavelength with dual wavelength energy or alternatively highly controlled venous-wall damage characteristics. This treatment condition is based on feedback from different control parameters, which are modulated and preferentially predetermined structural parameters of the treatment site. The apparatus includes a side fired optical fiber that can also be irradiated from the distal end of the fiber to a substantially uniform circumference. Alternatively, in another preferred embodiment, 1460 + - 60 nm laser energy is used, which with its high absorption rate in the vein wall results in less damage to the vein wall, less thermal stress outside the vein, Which is very effective. An example is to use a wavelength of 1460 +/- 60 nm, for example. Laser vein therapy administered using 1460 ± 60 nm offers advantages of high vein occlusion rates and extremely favorable postoperative outcomes, that is, almost no postoperative pain / discomfort, bruising or inflammatory response ,
