# Patent

## Title
Total internal reflection laser tools and methods

## Abstract

There is provided high power laser tools and laser heads that utilize total internal reflection (“TIR”) structures to direct the laser beam along a laser beam path within the TIR structure. The TIR structures may be a TIR prism having its hypotenuse as a TIR surface.

## Background
This application claims, under 35 U.S.C. §119(e)(1) the benefit of the filing date of Mar. 1, 2012 of U.S. provisional application Ser. No. 61/605,434 filed Mar. 1, 2012 and the benefit of the filing date of Jan. 23, 2013 of U.S. provisional application Ser. No. 61/755,745, the entire contents of each of the above mentioned provisional applications is incorporated herein by reference.


This invention was made with Government support under Award DE-AR0000044 awarded by the Office of ARPA-E U.S. Department of Energy. The Government has certain rights in this invention.


BACKGROUND OF THE INVENTION
Field of the Invention
The present inventions relate to methods, apparatus and systems for the delivery of high power laser beams to a work surface, and in particular, a work surface that may on a factory floor, may be in remote, hazardous, optically occluded and difficult to access locations, such as: oil wells, boreholes in the earth, pipelines, underground mines, natural gas wells, geothermal wells, surface mines, subsea, nuclear reactors, or in other environments.
SUMMARY
There is a need to perform operations such as cutting, removing, milling, drilling, perforating and cleaning in many settings, including on the factory floor and in the exploration, production, and development of natural resources, such as minerals, ores, gems, oil, gas and geothermal. The present inventions, among other things, meet these needs by providing the articles of manufacture, devices and processes taught herein.
Thus, there is provided a TIR high power laser tool having: a beam tube, and the beam tube having a laser beam path for transmitting a laser beam within the beam tube and for delivering a fluid; a housing in fluid communication with the beam tube, and the housing having a TIR polyhedron structure made from a material that is transmissive to the laser beam; and, a passage defined in part by a TIR surface of the TIR polyhedron structure, and having the passage in fluid communication with the beam tube and having the passage removed from the laser beam path; and the laser beam path extending through a first surface of the TIR polyhedron structure and into the material; the laser beam path extending to and from the TIR surface and forming an angle of incidence θi on the TIR surface that is greater than a critical angle θc for the TIR surface, whereby the laser beam traveling along the laser beam path is reflected within the TIR structure by total internal reflection from the TIR surface.
Further there is provided TIR high power laser tools having one or more of the following features: wherein the fluid has an index of refraction of n2 and the material has an index of refraction of n1, and wherein n1 is greater than n2; wherein the beam tube defines a beam tube passage and wherein the fluid and laser beam path are within the beam tube passage, whereby the laser beam is transmitted through the fluid in the beam tube passage; wherein the housing comprises a nozzle and the laser beam path from the TIR surface extends through the nozzle; wherein the TIR structure has a 1-degree tilt and the nozzle has a 2-degree tilt; and, wherein the TIR structure is a right angle prism having a hypotenuse that includes the TIR surface; wherein the TIR structure is a right angle prism having a hypotenuse and the TIR surface is the hypotenuse.
Moreover, there is provided a TIR high power laser head for use with a high power laser tool, the laser head having: a TIR structure having a first face, a second face and a third face and having an index of refraction n1 for a laser beam having predetermined beam parameters; a laser beam path along which the laser beam travels, the laser beam path extending through the first face, to the second face and through the third face; and, the second face having a TIR surface.
Still further there is provided a TIR high power laser head having one or more of the following features: wherein the laser beam has a wavelength of from about 400 nm to about 1,600 nm and a power of at least about 10 kW; wherein the laser beam has a spot size on the first face of the TIR structure of less than about 4 cm2; wherein the laser beam has a spot size on the first face of the TIR structure of less than about 2 cm2; wherein the laser beam has a power of at least about 20 kW and wherein the laser beam has a spot size on the first face of the TIR structure of at least about 0.08 cm2; wherein the laser beam has a power of at least about 20 kW and the spot size on the first face of the TIR structure is from about 0.5 cm2 to about 0.08 cm2; wherein the TIR structure is a right angle prism having a hypotenuse and the TIR surface is at least a portion of the hypotenuse; having a mount, the mount having a top window and a side window; a first wall and a second wall defining a channel; the channel containing a material having an index of refraction of n2 for the laser beam; the material in optical contact with the TIR surface, wherein in n1 is greater than n2; wherein the material having the index of refraction n2 is a fluid; wherein this material is a gas; wherein this material is air; having a prism mount, the prism mount comprising a top window and a side window; a first channel wall and a second channel wall defining a channel; wherein the second channel wall comprises the second face; the channel containing a material having an index of refraction of n2 for the laser beam; the material in optical contact with the TIR surface; wherein n1 is greater than n2 and the n2 material is a gas; and, wherein the TIR surface has a critical angle θc and the laser beam path forms an angle of incidence θi with the TIR surface; and wherein θi is greater than θc.
Additionally, there is provided a method of directing a high power laser beam within a laser tool, the method including: directing a laser beam along a beam path to a first surface of a TIR structure in a laser tool; the laser beam traveling along the laser beam path entering the TIR structure through the first surface and traveling along the laser beam path within the TIR structure to a second surface of the TIR structure; the laser beam being reflected by total internal reflection from the second surface and traveling along the laser beam path within the TIR structure to a third surface of the TIR structure; and, directing the laser beam along the laser beam path from the laser tool.
Still additionally, the TIR methods of directing a laser beam within a high power laser tool may have one or more or the following features: wherein the TIR structure has an index of refraction for the laser beam of n1; and providing a fluid having an index of refraction of n2 adjacent to the second surface of the TIR structure, wherein n1 is greater than n2; wherein the laser beam is transmitted through this fluid as the laser beam is directed from the laser tool; wherein the laser beam is transmitted through this fluid as the laser beam is delivered to the TIR structure.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross sectional view of an embodiment of a TIR structure in accordance with the present invention.
FIG. 2 is a cross sectional view of an embodiment of a TIR laser tool head in accordance with the present invention.
FIG. 3 is a cross sectional perspective view of an embodiment of a TIR laser tool head in accordance with the present invention.
FIG. 4A is a cross sectional view of an embodiment of a TIR laser tool in accordance with the present invention.
FIG. 4B is a cross sectional view of the TIR laser head of the TIR laser tool of FIG. 4A.
FIGS. 4C and 4D are prospective views of the TIR prism holder of the TIR laser tool of FIG. 4A.
FIG. 5A is a cross sectional view of an embodiment of a TIR laser tool in accordance with the present invention.
FIG. 5B is a cross sectional view of the TIR laser head of the TIR laser tool of FIG. 5A.
FIG. 5C is a prospective view of the TIR prism holder of the TIR laser tool of FIG. 5A.
FIG. 6 is a cross sectional perspective view of an embodiment of a TIR laser head in accordance with the present invention.



DESCRIPTION OF THE PREFERRED EMBODIMENTS
In general, the present inventions relate to high power laser tools that may be used with, as a part of, or in conjunction with, systems, methods and tools for applying laser energy for performing laser applications and 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.
Generally, a total internal reflectance (“TIR”) prism directs a laser beam along a portion of a laser beam path within, into, and out of a laser tool. High power laser tools with a TIR prism may direct the high power laser beam to a work surface for performing a laser or laser assisted operation.
The TIR prism is configured such that a high power laser beam, i.e., 1 kW or greater, is directed toward a first face or surface of the prism, which can be referred to as the incoming, or receiving, face. Preferably, this face has an antireflective coating. The plane of first face is essentially normal, i.e., about 90 degrees, to the laser beam path and the laser beam traveling along that path. This angle, which can be referred to as the incoming beam path-face angle, may vary from 90 degrees, preferably by no more than about 5 degrees. Larger and smaller angles of variation are contemplated, but less preferred. Custom and more specialized antireflective coatings and other means to address reflections may be needed when the incoming beam path-face angle is greater or less than about 85-95 degrees.
Upon entering the prism the laser beam travels along the laser beam path through the prism material and strikes a second surface or face within the prism, e.g., the hypotenuse, of the prism. The material on the outside of this second face has an index of refraction, which in view of the angle at which the laser beam is striking the second face, results in the total internal reflection of the laser beam within the prism. Total internal reflection occurs when the index of refraction n1 of the prism material is greater than the index of refraction n2 of the material adjacent the second prism face. Further, for total internal reflection to occur the angle at which the laser beam path and laser beam strike the second prism face (the angle of incidence, θi) must be greater than the critical angle θc as measured from the surface normal. The critical angle θc is defined by the equation




  
    θ
    ⁢
    
      
    
    ⁢
    c
  
  =
  
    
      
        sin
        
          -
          1
        
      
      ⁡
      
        (
        
          
            n
            2
          
          
            n
            1
          
        
        )
      
    
    .
  




Thus, the laser beam is reflected from the second face of the prism by total internal reflection and then travels along the laser beam path from the second face to the third face of the prism. The angle at which the laser beam path and laser beam strike the third prism face is smaller than the critical angle, and thus, the laser beam traveling along the laser beam path leaves the prism, e.g., is launched from the third face along the laser beam path. Upon leaving the third face the laser beam continues to travel along the laser beam path toward, e.g., other optics, another TIR prism, a nozzle, a fluid jet, a work surface, and combinations and various of these and other intermediate and end points along the laser beam path.
Thus, by way of illustration, turning to FIG. 1 there is shown a schematic diagram of an embodiment of a TIR prism in a laser tool. The TIR prism 100 has material 113 having an index of refraction n1; and has a first, incoming, face or surface 103, a second, TIR, face or surface 104, and a third, exit, face or surface 105. The prism would be a 90-degree prism, as surfaces 103 and 105 meet at a right (90 degree) angle at point 112. A material 114, is adjacent surface 104 and has an index of refraction n2 that is different from the index of refraction n1 of the prism material 113. Index of refraction n1 is greater than index of refraction n2. It further being understood that index of refraction for a particular material is wavelength dependent.
A laser beam traveling along incoming beam path 101 enters the prism passing through surface 103. The angle 108 (incoming beam path-face angle) between beam path 101 and surface 103 is 89 degrees. The incoming beam path 101 is coaxial with the longitudinal axis 111 of the laser tool. The laser beam traveling along the laser beam path within the prism 100 strikes surface 104. The beam and beam path form an angle 109 (the angle of incidence θi) with surface 104. Angle 109 is measured from a line (dashed line 106), that is normal (90 degrees) to surface 104. In this embodiment angle 109, θi, is 46 degrees. θi is greater than the critical angle, θc, and surface 104 provides total internal reflection directing the laser beam along beam path 102 toward and through surface 105.
Thus, in a TIR prism, it is an internal surface of the prism that the laser beam is reflected from. This is to be contrasted with a convention mirror, in which it is an external surface that the laser beam is reflected from. Especially in harsh environments and as laser powers increase, having an internal reflective surface provides advantages over an external reflective surface, by keeping that surface clean and protected, e.g., from dirt, debris and environmental factors.
Returning to FIG. 1, after being reflected from TIR surface 104, the laser beam traveling along path 102 strikes the surface 105 at an angle 110, which is measured from a line (dashed line 107) that is normal (90 degrees) to the surface 105. Angle 110 is smaller than the critical angle for surface 105, and thus the laser beam is transmitted through surface 105. In this embodiment angle 110 is 2 degrees.
Thus, in the embodiment of FIG. 1 the prism has a 1 degree tilt from the tool axis 111 and incoming beam path 101, and provides a 2 degree tilt from horizontal (i.e., normal to the tool and beam axis) for the exiting laser beam 102 and beam path. Depending upon the position of the prism relative to the incoming laser beam and other factors, the angle of the exiting laser beam from the prism relative to the incoming laser beam into the prism may be 90 degrees, about 90 degrees, and greater than or less than 90 degrees, e.g., about 89 degrees, about 91 degrees, about 92 degrees, about 88 degrees, about 93 degrees, and about 87 degrees.
Although a prism is the preferred geometric shape for use as the TIR structure, that structure may be any polyhedron, as long as the geometry, in conjunction with other factors, provides for total internal reflection on the intended TIR surfaces. The TIR structure, e.g., the prism, may be made of fused silica, sapphire, diamond, calcium chloride, or other such materials capable of handling high power laser beams and transmitting them with little, low or essentially no absorbance of the laser beam. The entrance and exit faces of the TIR structure should have AR (anti-reflective) coatings matched to the medium of transmission. Typically, AR coatings have a much lower absorption than HR (highly-reflective) coatings, which would be used on conventional reflective mirrors, and as a consequence AR coatings cause substantially less heating in the substrate than would be present if HR coatings were used. Thus, an advantage in using TIR structures is the reduce need and reduce usage of HR coatings, and preferably the elimination of the need for such coatings along the high power laser beam path in the tool. The material adjacent the TIR structure's TIR surface can be any material having, or in operation of the tool providing, an index of refraction n2 that is lower than the index of refraction n1 of the material of the TIR structure at the TIR surface. Thus, this material may be a fluid (e.g., liquid or gas), a supercritical fluid, or a solid. For example, this material could be an oil, mineral oil, silicon oil, diesel, water, deuterium oxide, air, nitrogen or oxygen. 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, essentially no loss, in power at each TIR surface or interface.
The faces of the TIR structure, such as the first and third non-TIR faces of a TIR prism, may also have beam shaping, affecting or changing optics incorporated into them, and thus, may function as, for example, a lens.
The area, e.g., spot size, of the laser beam striking the first surface of the TIR structure may be selected or is dependent upon factors such as the power/area that this surface can handle without being damage or otherwise adversely affected, the optics of the tool, the relative position of the optics with respect to the TIR structure, the intended spot size of the laser beam at the work surface, the physical size limitation on the tool, and other factors. Thus, for example, the spot size on the first face of the TIR structure may be less than about 4 cm2, less than about 2 cm2, at least about 0.08 cm2 for laser beams having at least about 20 kW of power, and from about 0.5 cm2 to about 0.08 cm2.
There may be one, two, three or more TIR structures, each having one, two, three or more TIR surfaces, in a tool, or combination of tools. The tool may have one, two, three or more laser beams and laser beam paths. The laser beam path may be co-axial with an axis of the tool, may be parallel but not co-axial with an axis of the tool, and may be non-parallel with an axis of the tool. The tool may also have other components, such as controllers, optics, optical assemblies, optical connectors, locking and latching devices, connectors, motors, sensors, fluid jets, optical fibers, umbilicals, control, data and monitoring cables, and mechanical removal elements.
In an embodiment of the TIR laser tool the prism is preferably made from fused silica and the material on the face of the second surface, the hypotenuse, is air. In operation, the air is flowing and flowing in a manner that removes any heat that may build up within or on the prism. Although air and fused silica are use in this embodiment other materials and fluids may be utilized including liquids; provided that the differing indices of refraction and angle of laser beam incidence on the internal prism face result in total internal reflection. Typically sapphire has a high absorption at 1070 nm and in that wavelength and wavelength range fused silica is preferred. Wavelengths and wavelength ranges may vary for applications and systems.
EXAMPLES
The following examples are provide to illustrate various configurations of embodiments of TIR high power laser tools. These examples are for illustrative purposes, and should not be view as, and do not otherwise limit the scope of the present inventions.
Example 1
Turning to the embodiment of FIG. 2, there is shown a cross section of a laser tool head having a TIR structure. The laser tool head 200 has beam tube 201 that is secured to a housing 212 by way of a threaded connection. The beam tube 201 has a cavity through which the laser beam path 202, and the laser beam along that path, travels. The beam tube also conveys the fluid that is used to provide the TIR effect and to form a fluid laser jet. The TIR prism 203 has a first AR coated surface 210, a TIR surface 204, and a third AR coated surface 211. The TIR prism 203 is held in position by prism mount 205 that is secured to housing 212 by setscrew 213. Mount 205 holds windows 207 and 208. Mount 205 has a fluid flow passage 206 that is formed against the TIR surface 204. Thus, a wall, or inner surface, of the fluid flow passage 206 is the TIR surface 204. In this manner a fluid having an index of refraction n2, which is lower than the index of refraction n1 of the prism material is maintained in contact with the TIR surface 204. The prism in this embodiment is made from fused silica. The housing 212 has a nozzle for providing a jet of the fluid, which jet surrounds the laser beam path.
Example 2
Turning to FIG. 3 there is provided a perspective cross-sectional view of an embodiment of a TIR laser head having a 2-degree from horizontal exiting beam path. The laser tool head 300 has a beam tube 301 having a cavity 321 for transmitting the laser beam along a laser beam path and for transmitting the fluid having an index of refraction lower than the index of refraction of the prism material. The beam tube 301 is attached to a housing 312. In this embodiment the fluid is air and the prism is made from sapphire. The flow of air through the laser tool head 300 is shown by arrows, e.g., 315. The TIR prism 303 is a 90-degree prism and is held in a prism clamp 320. The prism clamp 320 has topside (or inlet) window 307 that is held in place by a retainer ring 316 and a wave spring 317. The topside window 307 receives the laser beam from the beam tube 301 and transmits the laser beam to the TIR prism 303. The prism clamp 320 has a side (or outlet) window 308 that is held in place by a retainer ring 319 and a wave spring 318. The prism clamp 320 is attached to the prism holder 305, which is attached to the housing 312. The TIR prism 303 has a TIR surface 304. The prism is held at a 1 degree tilt with respect to the axis of the tool; providing for a 92 degree change in the laser beam path. A nozzle 309 is attached to the housing 312.
Example 3
Turning to FIGS. 4A to 4D there is provided an embodiment of a TIR laser tool. In FIG. 4A there is shown a cross-sectional view of a TIR laser tool 400. The laser beam 401 is focused (by focusing optics not shown in the FIG.) to a focal point 402. The laser tool 400 has a beam tube 408 and a laser tool head 403 having a TIR prism 404. The fluid, e.g., air, flow path is shown by the arrows, e.g., 405. Thus, in this embodiment a focused laser beam is being directed into the TIR prism. Although shown in this embodiment as being after the TIR prism, the focal point may also be before or in the TIR prism. The tool 400 has a fluid inlet 406. The laser tool head 403 has a nozzle 407 for forming a laser-fluid jet. The laser tool head 403 has a prism holder 410 having channels 411, 412. In this manner the laser beam 401 is transmitted through the fluid in the beam tube 408. The fluid is then routed by the channels 411, 412 to a flow channel 413 along the TIR side 450 of the TIR prism 404 and then back around, to be recombined with the laser beam 401 in the nozzle 407.
Example 3A
In the embodiment of FIG. 4, the laser beam has a spot size on the first face of the TIR structure of about 2 cm2, has a wavelength of about 1070 nm, and has a power of 20 kW.
Example 3B
In the embodiment of FIG. 4, the laser beam has a spot size on the first face of the TIR structure of about 0.08 cm2, has a wavelength of about 1070 nm, and has a power of 20 kW.
Example 3C
In the embodiment of FIG. 4, the laser beam has a spot size on the first face of the TIR structure of about 0.5 cm2, has a wavelength of about 1070 nm, and has a power of 15 kW.
Example 4
Turning to FIGS. 5A to 5C there is provided an embodiment of a TIR laser tool. In FIG. 5A there is shown a cross-sectional view of a TIR laser tool 500. In FIG. 5B there is shown a more detailed cross-sectional view of the tool head 503; and in FIG. 5c there is shown a more detailed perspective view of the prism holder 510. The laser tool 500 has an outer beam tube 508 and a laser tool head 503 having a TIR prism 504. The outer beam tube 508 has an inner beam tube 509. Inner beam tube 509 forms a cavity 531, through which the laser beam along a laser beam path is transmitted to the TIR prism 504. Inner beam tube 509 and outer beam tube 508 form an annular cavity 530 through which the fluid, e.g., air, flows along a flow path as shown by the arrows, e.g., 505. The tool 500 has a fluid inlet 506. The inner beam tube 509 has an inlet 532, which may be used for a purge gas, to pressurize the inner beam tube 509 and both. The laser tool head 503 has a nozzle 507 for forming a laser-fluid jet. The laser tool head 503 has a prism holder 510 that is preferably in sealing engagement with the bottom of inner beam tube 509. In this manner the laser beam and the fluid are transmitted to the laser head 503 in separate cavities 530, 531. Thus, the laser beam is not transmitted through the fluid in the laser beam tube. The fluid is then routed by a flow channel 513 along the TIR side 550 of the TIR prism 504 and then back around, to be combined for the first time with the laser beam in the nozzle 507.
Example 5
Turning to FIG. 6 there is provided a perspective cross-sectional view of an embodiment of a TIR laser head having a 0-degree from horizontal exiting beam path. The laser tool head 900 has a beam tube 901 having a cavity 921 for transmitting the laser beam along a laser beam path and for transmitting the fluid having an index of refraction lower than the index of refraction of the prism material. The beam tube 901 is attached to a housing 912, having a removable bottom cap 940. In this embodiment the fluid is air and the prism is made from fused silica. The flow of air through the laser tool head 900 is shown by arrows, e.g., 915. The TIR prism 903 is a 90-degree prism and is held in a prism mount 920, and is retained in mount 920 by clip 941. The prism mount 920 has topside (or inlet) window 907 that is held in place by a retainer ring 916 and a wave spring 917. The topside window 907 receives the laser beam from the beam tube 901 and transmits the laser beam to the TIR prism 903. The prism mount 920 has a side (or outlet) window 908 that is held in place by a retainer ring 919 and a wave spring 918. The prism mount 920 is attached to the housing 912. The TIR prism 903 has a TIR surface 904. The prism is held at a 0 degree tilt with respect to the axis of the tool; providing for a 90 degree change in the laser beam path. A nozzle 909 is attached to the housing 912. The axis of the nozzle is at 90 degrees to the axis of the tool and the laser beam path, and thus the tilt of the nozzle would be 0 degrees. An air block 950 is positioned in the flow channel 951 adjacent the TIR surface 904. The air block is shaped to reduce dead, stagnant or back flow areas of flow next to the TIR surface 904. The air block can have many shapes, that are for example designed to increase the flow rate or velocity of the fluid as it moves past the TIR surface 904.
Example 8
The embodiment of FIG. 6 is adjusted to have the prism at a 1 degree tilt. Providing for a change in beam direction of 92 degrees. The 90 degree nozzle is replaced with a 92 degree nozzle, and thus providing a downward tilt of 2 degrees.
TIR structures and TIR tools, i.e., a laser tool utilizing a TIR structure, may find applications in activities such as: off-shore activities; subsea activities; decommissioning structures such as, oil rigs, oil platforms, offshore platforms, factories, nuclear facilities, nuclear reactors, pipelines, bridges, etc.; 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 workover; precise and from a distance in-place milling and machining; heat treating; drilling and advancing boreholes; workover and completion; flow assurance; and, combinations and variations of these and other activities and operations. A preferred application for TIR laser tools is generally in internal bore processing applications, such as perforating or window cutting, by providing benefits for, among other things, making about right angle bends in the laser beam path within the restricted space of a borehole.
A single high power laser may be utilized in the system, tools and operations, or there may be two or three high power lasers, or more. High power solid-state lasers, specifically semiconductor lasers and fiber lasers are preferred, because of their short start up time and essentially instant-on capabilities. The high power lasers for example may be fiber lasers, disk lasers or semiconductor lasers having 5 kW, 10 kW, 20 kW, 50 kW, 80 kW or more power and, which emit laser beams with wavelengths in the range from about 455 nm (nanometers) to about 2100 nm, preferably in the range about 400 nm to about 1600 nm, about 400 nm to about 800 nm, 800 nm to about 1600 nm, about 1060 nm to 1080 nm, 1530 nm to 1600 nm, 1800 nm to 2100 nm, and more preferably about 1064 nm, about 1070-1080 nm, about 1360 nm, about 1455 nm, 1490 nm, or about 1550 nm, or about 1900 nm (wavelengths in the range of 1900 nm may be provided by Thulium lasers). An example of this general type of fiber laser is the IPG YLS-20000. The detailed properties of which are disclosed in US patent application Publication Number 2010/0044106. Thus, by way of example, there is contemplated the use of four, five, or six, 20 kW lasers to provide a laser beam having a power greater than about 60 kW, greater than about 70 kW, greater than about 80 kW, greater than about 90 kW and greater than about 100 kW. One laser may also be envisioned to provide these higher laser powers.
The various embodiments of TIR structures and tools set forth in this specification may be used with various high power laser systems and conveyance structures and systems, in addition to those embodiments of the Figures and Examples in this specification. For example, embodiments of TIR structures may be used for, in, or with, the systems, lasers, tools and methods disclosed and taught in the following US patent applications and patent application publications: Publication No. 2010/0044106; Publication No. 2010/0215326; Publication No. 2012/0275159; Publication No. 2010/0044103; Publication No. 2012/0267168; Publication No. 2012/0020631; Publication No. 2013/0011102; Publication No. 2012/0217018; Publication No. 2012/0217015; Publication No. 2012/0255933; Publication No. 2012/0074110; Publication No. 2012/0068086; Publication No. 2012/0273470; Publication No. 2012/0067643; Publication No. 2012/0266803; Ser. No. 61/745,661; and Ser. No. 61/727,096, the entire disclosure of each of which are incorporated herein by reference.
Embodiments of TIR structures may also be used with: other high power laser systems that may be developed in the future; and with existing non-high power laser systems, which may be modified, in-part, based on the teachings of this specification, to create a high power laser system. Further, the various embodiments of devices systems, tools, activities and operations set forth in this specification may be used with each other in different and various combinations. Thus, for example, the configurations provided in the various embodiments of this specification may be used with each other; and the scope of protection afforded the present inventions should not be limited to a particular embodiment, configuration or arrangement that is set forth in a particular embodiment, example, or in an embodiment in a particular Figure.
The invention may be embodied in other forms than those specifically disclosed herein without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive.

## Claims

1. A total internal reflection high power laser tool, for use in hydrocarbon exploration, hydrocarbon production or the decommissioning of hydrocarbon wells, the tool comprising:
a. a beam tube, defining a tool axis, the beam tube comprising a laser beam path for transmitting a laser beam within the beam tube and a fluid path for transmitting a fluid;
b. a housing in fluid communication with the beam tube, the housing comprising a single and unitary total internal reflection polyhedron structure comprised of a material transmissive to the laser beam; and, a passage defined in part by a total internal reflection surface of the total internal reflection polyhedron structure, the passage in fluid communication with the beam tube fluid path and removed from the laser beam path;
c. the laser beam path extending through a first surface of the total internal reflection polyhedron structure and into the material;
d. the laser beam path extending to and from the total internal reflection surface and forming an angle of incidence θi on the total internal reflection surface that is greater than a critical angle θc for the total internal reflection surface; whereby the laser beam traveling along the laser beam path is reflected within the total internal reflection structure by total internal reflection from the total internal reflection surface; and
e. the laser beam path extending from the total internal reflection material and exiting the housing along a straight path; the exiting laser beam path forming an angle of about 90° or less with the beam tube axis.

2. The high power laser tool of claim 1, wherein the beam tube defines a beam tube passage and wherein the fluid and laser beam path are within the beam tube passage, whereby the laser beam is transmitted through the fluid in the beam tube passage.

3. The high power laser tool of claim 1, wherein the total internal reflection structure is a right angle prism having a hypotenuse comprising the total internal reflection surface.

4. The high power laser tool of claim 1, wherein the fluid has an index of refraction of n2 and the material has an index of refraction of n1, and wherein n1 is greater than n2.

5. The high power laser tool of claim 4, wherein the total internal reflection structure is a right angle prism having a hypotenuse and the total internal reflection surface is the hypotenuse.

6. The high power laser tool of claim 4, wherein the housing comprises a nozzle and the laser beam path from the total internal reflection surface extends through the nozzle.

7. The high power laser tool of claim 6, wherein the total internal reflection structure has a tilt of x degrees and the nozzle has tilt of two times 2x degrees.

8. The high power laser tool of claim 7, wherein x is 1.

9. The high power laser tool of claim 7, wherein the total internal reflection structure is a right angle prism having a hypotenuse comprising the total internal reflection surface.

10. A total internal reflection high power laser head for use with a high power laser tool, in hydrocarbon exploration, hydrocarbon production or the decommissioning of hydrocarbon wells, the laser head comprising:
a. the laser head defining a laser head axis; a total internal reflection structure comprising a first face, a second face and a third face and having an index of refraction n1 for a laser beam having predetermined beam parameters, the total internal reflection structure defining a total internal reflection structure axis;
b. a laser beam path along which the laser beam travels, the laser beam path parallel with the laser head axis extending through the first face, to the second face and through the third face; wherein the total internal reflection structure axis is at least 1° different than the laser head axis, and wherein the laser beam path through the third face forms an angle with the laser beam path through the first face of from about 87° to about 93°;
c. the second face comprising a total internal reflection surface; and,
d. a fluid flow passage adjacent to the second face.

11. The total internal reflection high power laser head of claim 10, wherein the laser beam has a spot size on the first face of less than about 4 cm2.

12. The total internal reflection high power laser head of claim 10, comprising a mount, the mount comprising a top window and a side window; a first wall and a second wall defining a channel; the channel containing a material having an index of refraction of n2 for the laser beam; the material in optical contact with the total internal reflection surface, wherein in n1 is greater than n2.

13. The total internal reflection high power laser head of claim 10, wherein the total internal reflection surface has a critical angle θc and the laser beam path forms an angle of incidence θi with the total internal reflection surface; and wherein θi is greater than θc.

14. The high power laser tool of claim 10, wherein the total internal reflection structure is a right angle prism having a hypotenuse comprising the total internal reflection surface.

15. The total internal reflection high power laser head of claim 14, wherein the material is a air.

16. The total internal reflection high power laser head of claim 10, comprising a prism mount, the prism mount comprising a top window and a side window; a first wall and a second wall defining a channel; wherein the second wall comprises the second face; the channel containing a material having an index of refraction of n2 for the laser beam; and the material in optical contact with the total internal reflection surface.

17. The total internal reflection high power laser head of claim 16, wherein n1 is greater than n2 and the material is a gas.

18. The total internal reflection high power laser head of claim 10, wherein the laser beam parameters comprise a wavelength of from about 400 nm to about 1,600 nm and a power of at least about 10 kW.

19. The total internal reflection high power laser head of claim 18, wherein the laser beam has a spot size on the first face of less than about 2 cm2.

20. The total internal reflection high power laser head of claim 18, wherein the laser beam has a power of at least about 20 kW and the spot size on the first face is from about 0.5 cm2 to about 0.08 cm2.

21. The total internal reflection high power laser head of claim 20, wherein the material is a gas.

22. The total internal reflection high power laser head of claim 18, wherein the laser beam has a power of at least about 20 kW and wherein the laser beam has a spot size on the first face of at least about 0.08 cm2.

23. The total internal reflection high power laser head of claim 22, wherein the material is a fluid.

24. The total internal reflection high power laser head of claim 22, wherein the total internal reflection surface has a critical angle θc and the laser beam path forms an angle of incidence θi with the total internal reflection surface; and wherein θi is greater than θc.

25. A method of directing a high power laser beam within a laser tool, for use in hydrocarbon exploration, hydrocarbon production or the decommissioning of hydrocarbon wells, the method comprising:
a. directing a laser beam along a beam path to a first surface of a unitary total internal reflection structure in a laser tool;
b. the laser beam traveling along the laser beam path entering the unitary total internal reflection structure through the first surface and traveling along the laser beam path within the total internal reflection structure to a second surface of the total internal reflection structure;
c. the laser beam being reflected by total internal reflection from the second surface and traveling along the laser beam path within the total internal reflection structure to a third surface of the total internal reflection structure;
d. directing the laser beam along the laser beam path from the laser tool; and,
e. wherein the laser travels along a beam tube, the beam tube comprising a laser beam path for transmitting a laser beam within the beam tube and a fluid path for transmitting a fluid.

26. The method of claim 25, wherein the total internal reflection structure has an index of refraction for the laser beam of n1; and comprising providing a fluid having an index of refraction of n2 adjacent to the second surface, wherein n1 is greater than n2.

27. The method of claim 25, wherein the laser beam is transmitted through the fluid as the laser beam is directed from the laser tool.

28. The method of claim 27, wherein the laser beam is transmitted through the fluid as the laser beam is directed to the total internal reflection structure.

29. A total internal reflection high power laser tool, for use in hydrocarbon exploration, hydrocarbon production or the decommissioning of hydrocarbon wells, the tool comprising:
a. a beam tube, defining a tool axis, the beam tube comprising a laser beam path for transmitting a laser beam within the beam tube and a fluid path for transmitting a fluid;
b. a housing in fluid communication with the beam tube, the housing comprising a single and unitary total internal reflection polyhedron structure comprised of a material transmissive to the laser beam; and, a passage defined in part by a total internal reflection surface of the total internal reflection polyhedron structure, the passage in fluid communication with the beam tube fluid path and removed from the laser beam path;
c. the laser beam path extending through a first surface of the total internal reflection polyhedron structure and into the material;
d. the laser beam path extending to and from the total internal reflection surface and forming an angle of incidence θi on the total internal reflection surface that is greater than a critical angle θc for the total internal reflection surface; whereby the laser beam traveling along the laser beam path is reflected within the total internal reflection structure by total internal reflection from the total internal reflection surface; and,
e. the laser beam path extending from the total internal reflection material and exiting the housing along a straight path; the exiting laser beam path forming an angle of about 90° or greater with the beam tube axis.