NOVELTY - The tool has a beam tube (201) having a fluid path and a laser beam path (202) for transmitting a laser beam within beam tube. Housing (212) includes a TIR polyhedron structure having a material transmissive to laser beam, and defining a passage (206) in communication with fluid path. The laser beam path extends to and from a TIR surface (204) and forms an angle of incidence on TIR surface, which is greater than a critical angle for TIR surface. The laser beam traveling along laser beam path is reflected within TIR structure by total internal reflection.    USE - Total internal reflection (TIR) high power laser tool for delivering high power laser beams to work surface of oil well, borehole in the earth, pipeline, underground mine, natural gas well, geothermal well, surface mine, subsea and nuclear reactor. Can also be used in laser assisted applications such as cutting, heat treating, thermal processing, annealing, cladding, hard facing, welding, removing material, monitoring, cleaning, controlling, assembling, drilling, machining, powering equipment, milling, flow assurance, decommissioning, plugging, abandonment and perforating, subsea activities, decommissioning structures e.g. oil rigs, oil platforms, offshore platforms, factories, nuclear facilities, nuclear reactors, pipelines and bridges, cutting and removal of structures in refineries, civil engineering projects and construction and demolitions, concrete repair and removal, mining, surface mining, deep mining, rock and earth removal, surface mining, tunneling, making small diameter bores, oil field perforating, oil field fracking, well completion, window cutting, well decommissioning, well work-over, in-place milling and machining, heat treating, drilling and advancing boreholes, work-over and completion and flow assurance.    ADVANTAGE - The TIR structure reduces the need and usage of highly-reflective coatings, and eliminates the need for highly-reflective coatings along the high power laser beam path in the tool. Multiple TIR surfaces and reflections can be used in a single TIR structure to make a total desired beam angle change with virtually no loss in power at each TIR surface or interface. The internal reflective surface of TIR prism is kept clean and protected from dirt, debris and environmental factors.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a TIR high power laser head for use with high power laser tool; and    (2) a method for directing high power laser beam within laser tool.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the TIR laser tool head.    Beam tube (201)    Laser beam path (202)    TIR surface (204)    Passage (206)    Housing (212)