Abstract: In a laser surgical unit having a contact laser probe (1), a hydroxyl group (13) is included in the contact laser probe so that a laser beam is partially absorbed by the hydroxyl group (13) to heat the contact laser probe (1) for transmission to living tissue. Consequently, a coagulation layer is formed in the living tissue along with vaporization and incision. At least a part of the contact laser probe (1) is made of a material which contains the hydroxyl group (13) generally in an amount of between 0.5 and 10 ppm. Alternatively, the hydroxyl group (13) may be included only in a portion adjacent to a surface of a tip portion of the probe (1). As a further alternative, a coating film containing the hydroxyl group (13) may be attached to the tip of the contact laser probe (1). The laser beam preferably has a wavelength between 1.5 and 15 .mu.m. For example, use is made of an Er:YAG laser beam a Ho:YAG laser beam, or a CO.sub.2 laser beam.

Abstract: In a laser surgical unit having a contact laser probe (1), a hydroxyl group (13) is included in the contact laser probe so that a laser beam is partially absorbed by the hydroxyl group (13) to heat the contact laser probe (1) for transmission to living tissue. Consequently, a coagulation layer is formed in the living tissue along with vaporization and incision. At least a part of the contact laser probe (1) is made of a material which contains the hydroxyl group (13) generally in an amount of between 0.5 and 10 ppm. Alternatively, the hydroxyl group (13) may be included only in a portion adjacent to a surface of a tip portion of the probe (1). As a further alternative, a coating film containing the hydroxyl group (13) may be attached to the tip of the contact laser probe (1). The laser beam preferably has a wavelength between 1.5 and 15 .mu.m. For example, use is made of an Er:YAG laser beam, a Ho:YAG laser beam, or a CO.sub.2 laser beam.

Abstract: A laser treatment device provided with a laser light source, a laser-light transmitting optical fiber for transmitting laser light output from the laser light source and a probe for guiding the laser light transmitted by the laser-light transmitting optical fiber to an object to be irradiated. Further, the probe is constituted by a laser-light guiding optical fiber separated from the laser-light transmitting optical fiber. Moreover, a cooling chamber for cooling the optical fibers is provided in the neighborhood of an output end of the laser-light transmitting optical fiber, from which the transmitted laser light is output, and an input end of the laser-light guiding optical fiber, from which the laser light output by the laser-light transmitting optical fiber is input to the laser-light guiding optical fiber. Thereby, a medical treatment of a deep part of an affected or diseased region can be achieved without worsening the state of the exit of the laser-light transmitting optical-fiber.