A system for real-time laser power monitoring

Abstract

[0001] The present disclosure relates generally to systems and methods for laser power measurement, and more particularly, to systems and methods for laser power measurement in a sterile working environment. In certain embodiments described herein, power measurements are made utilizing two laser sources: 1) a first laser source configured to generate a first laser beam (a treatment laser), and 2) a second laser source configured to generate a second laser beam (a test laser). The first laser beam generates gas bubbles in a test material (e.g., water, saline, balanced salt solution, gel, etc.), and the second laser beam is reflected back, and the reflected portion of the second laser beam is measured to determine the bubble lifetime, and the lifetime measurements are correlated with power measurements based on a correlation curve.

Description

[Background technology]

[0001] To prepare a surgical laser system for surgery, all of the components of the surgical laser system (e.g., surgical console with laser source, handpiece, consumables, optical fiber) must be assembled together. Proper assembly allows for efficient transmission of laser light from the laser source to the distal tip of the optical fiber. Incomplete and / or incorrect assembly or misalignment of components during use can lead to a lack of sufficient radiation at the tip of the optical fiber, and therefore a lack of efficiency. Furthermore, while the power at the laser source may be known, the power level at the tip of the optical fiber may be unknown due to inevitable variations in the optical connections of the various components of the surgical laser system during assembly or use.

[0002] Conventional systems require the use of a power meter coupled to a surgical laser system to measure the power level of the transmitted laser light. Typically, the power level of the laser light transmitted by a surgical laser system is measured prior to the surgical procedure. However, because the power meter is a non-sterile piece of equipment, using the power meter in an operating room environment is cumbersome and time-consuming, as the non-sterile power meter must be carefully handled, isolated, and kept sterile for patient safety. Furthermore, conventional testing systems cannot be used to verify laser power delivery during surgery because they are non-sterile. Summary of the Invention [Means for solving the problem]

[0003] The present disclosure relates to systems and methods for laser power measurement in a sterile working environment.

[0004] In certain embodiments, the laser power measurement is performed by a system including first and second laser sources, an optical fiber, and an optical detector. The first and second laser sources generate first and second laser beams, respectively. The optical fiber is configured to receive and direct the first and second laser beams toward the test material. The first laser beam forms a gas bubble in the test material. A portion of the second laser beam reflects from the interface between the optical fiber and the test material and back into the optical fiber. The optical detector receives the reflected portion and determines the power level of the first laser beam based on the reflected portion of the second laser beam. This system allows the power level to be determined in a sterile condition.

[0005] In certain embodiments, a method is provided. The method includes generating a first laser beam with a first laser source. The method also includes generating a second laser beam with a second laser source. The method also includes receiving the first laser beam from the first laser source with an optical fiber. The method also includes directing the first laser beam toward the test material through the optical fiber to form a bubble in the test material. The method also includes receiving a second laser beam from the second laser source at the optical fiber. The method also includes directing the second laser beam toward the test material through the optical fiber. The method also includes receiving, at the optical fiber, a reflected portion of the second laser beam from a distal end of the fiber and from the bubble. The method also includes directing, at the optical fiber, the reflected portion of the second laser beam to an optical detector. The method also includes receiving, at the optical detector, the reflected portion of the second laser beam from the optical fiber. The method also includes identifying, at the optical detector, a power level of the first laser beam based on a duration of the change in the reflected portion of the second laser beam received at the optical detector.

[0006] So that the above-mentioned features of the present disclosure can be understood in detail, a more particular description of the present disclosure briefly summarized above may be rendered with reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only exemplary embodiments and therefore should not be considered limiting of its scope, which is open to other equally effective embodiments. [Brief explanation of the drawings]

[0007] [Figure 1A] 1 illustrates an exemplary system for performing laser power measurements, in accordance with certain embodiments of the present disclosure. [Figure 1B] 1B illustrates another configuration of the exemplary system of FIG. 1A, in accordance with certain embodiments of the present disclosure. [Figure 2] 1 illustrates an exemplary method for performing laser power measurements, according to certain embodiments of the present disclosure. [Figures 3A-3F] 10 illustrates the evolution of a bubble while performing laser power measurements, according to certain embodiments of the present disclosure. [Figure 4A-4B] 10 shows a graph of reflected portions of laser light in accordance with certain embodiments of the present disclosure. [Figure 5] 10 shows a correlation curve of the back-reflected pulse width of the second laser with the laser power of the first laser, in accordance with certain embodiments of the present disclosure. [Figure 6] 1 shows a schematic diagram of a surgical console and its components in accordance with certain embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] For ease of understanding, the same reference numerals have been used, where possible, to refer to the same elements common to the figures. It is contemplated that elements and features of one embodiment may be incorporated into other embodiments as appropriate without further recitation.

[0009] The present disclosure relates generally to systems and methods for laser power measurement, and more particularly to systems and methods for laser power measurement in a work environment (e.g., a sterile surgical work environment).

[0010] Conventional systems require the use of a power meter to measure the power of a laser beam delivered from the working tip of an optical fiber. However, because the power meter is typically a non-sterile piece of equipment, using a power meter in an operating room environment is cumbersome and time-consuming when attempting to maintain sterility for patient safety. Furthermore, due to the non-sterile nature of the power meter, the power level of a laser beam transmitted by a surgical laser system is typically measured only before a surgical procedure is performed. However, it is important to monitor the power of the laser beam delivered from the working tip of the optical fiber throughout the performance of a surgical procedure. Accordingly, embodiments of the present disclosure provide systems and methods that enable efficient laser power measurement before, during, and after a surgical procedure in a sterile operating environment.

[0011] In certain embodiments described herein, power measurements of a surgical laser system are performed utilizing two laser sources: 1) a first laser source configured to generate a first laser beam (a “treatment” laser beam, such as an infrared (IR) laser beam) and 2) a second laser source configured to generate a second laser beam (a “test” laser beam, such as a visible laser beam). Before or during a surgical procedure, the first and second laser beams may be propagated through a test substance (e.g., water, saline, balanced salt solution, gel, etc.) to measure or monitor the power level of the first laser beam generated by the first laser source. As the first laser beam propagates through the test substance, it may generate transient vapor bubbles in the test substance, which may alter the portion of the second laser beam that reflects back into the surgical laser system. Thus, the duration of the change in the reflected portion of the second laser beam may be optically measured to determine the lifetime of the vapor bubble, which may be correlated to a laser power value based on one or more correlation curves.

[0012] Laser power measurement using the return reflection of the second laser beam allows for efficient inspection in a sterile environment and even during surgery without the use of non-sterile equipment such as power meters. Inspection of laser power levels can help identify equipment issues including improper assembly, component failure, misalignment due to movement or use before or during surgery, etc. Thus, the methods and systems described herein not only allow for real-time inspection during surgery, but also improve the overall safety of the surgical procedure by reducing the risk of introducing contaminants.

[0013] 1A illustrates a system 100 for performing laser power measurements in accordance with certain embodiments of the present disclosure. System 100 includes a surgical laser system 101, which may be operably coupled to and / or in communication with a surgical console, such as a surgical console for ophthalmic surgery. Surgical laser system 101 includes a first laser source 102 configured to generate a first laser beam 104 and, in certain embodiments, a second laser source 106 configured to generate a second laser beam 108. Generally, system 100 can measure the power of first laser beam 104 in real time as it is generated by first laser source 102 of surgical laser system 101.

[0014] In some embodiments, the first laser source 102 is a therapeutic laser source configured to generate a first laser beam 104 for treatment of a patient. The first laser beam 104 may be used to cut and / or emulsify material during a surgical procedure. For example, the first laser beam 104 may be used as a therapeutic beam to perform various functions during ophthalmic surgery (e.g., vitreoretinal procedures, glaucoma surgery, cataract surgery, etc.).

[0015] In some embodiments, the first laser beam 104 generated by the first laser source 102 is ultraviolet (“UV”) (less than 350 nm) (nanometer) laser light. In some embodiments, the first laser beam 104 is infrared (“IR”) (780-4000 nm) laser light, such as mid-infrared laser light. In some embodiments, the first laser beam 104 is argon blue-green laser light (488 nm), Nd-YAG (neodymium-doped yttrium aluminum garnet) laser light (532 nm), such as a frequency-doubled Nd-YAG laser light, krypton red laser light (647 nm), or any other suitable type of laser light for ophthalmic surgery. In some embodiments, the first laser beam 104 has a wavelength of approximately 500 nm.

[0016] In some embodiments, the first laser source 102 may generate and propagate a first laser beam 104 having a pulse rate within a range of about 100 Hertz (Hz) to 10 Kilohertz (kHz). In some embodiments, the first laser source 102 may generate and propagate a first laser beam 104 having a pulse rate within a range of about 10 Kilohertz (kHz) to about 500 kHz or about 1 kHz to about 1500 Hz. Other pulse rate ranges are contemplated. In some examples, the first laser source 102 generates a nanosecond, picosecond, or femtosecond first laser beam 104. In some embodiments, the first laser source 102 is a continuous wave (CW) laser source that can be switched to a pulsed mode during a calibration procedure.

[0017] 1A, in certain embodiments, the surgical laser system 101 also includes a second laser source 106 configured to generate a second laser beam 108. The second laser beam 108 may, in certain embodiments, function as a test laser beam for measuring the power level of the system 100. In some embodiments, the second laser beam 108 may be further configured to operate as a source of illumination for the surgical site or for targeting, or otherwise.

[0018] In some embodiments, the second laser beam 108 generated by the second laser source 106 is visible (380-780 nm) or IR (780-1000 nm) laser light. For example, in certain embodiments, the second laser beam 108 comprises 640 nm laser light. However, other spectra / ranges (e.g., 400 nm-4 μm) are also contemplated for the second laser beam 108.

[0019] In some embodiments, the second laser source 106 may generate and transmit the second laser beam 108 having a pulse rate within a range of about 100 Hertz (Hz) to 10 kilohertz (kHz). In some embodiments, the second laser source 106 may generate and transmit the second laser beam 108 having a pulse rate within a range of about 10 kilohertz (kHz) to about 5 MHz or about 1 kHz to about 1500 Hz. Other pulse rate ranges are contemplated. In some examples, the second laser source 106 generates a nanosecond, picosecond, or femtosecond laser beam 108. In some embodiments, the second laser source 106 may generate a continuous coherent or semi-continuous second laser beam 108. For example, the second laser source 106 may generate a continuous wave second laser beam 108 at a low power.

[0020] In some embodiments, first laser beam 104 and second laser beam 108 may be generated by a single laser source of surgical laser system 101 configured to generate more than one type of laser beam or laser beams with different characteristics. For example, in some embodiments, first laser beam 104 and second laser beam 108 may be generated by first laser source 102. In other embodiments, first laser beam 104 and second laser beam 108 may be generated by second laser source 106.

[0021] The system 100 further includes an optical fiber 110 having a proximal end 113 configured to be removably coupled to a port 130 of the surgical laser system 101. The optical fiber 110 may be configured to proximally receive and distally propagate both the first laser beam 104 and the second laser beam 108 generated by the first laser source 102 and the second laser source 106, respectively, which may be disposed adjacent the proximal end 113 of the optical fiber 110. The optical fiber 110 may include any suitable type of optical fiber configured to transmit optical energy along its length. In some embodiments, the optical fiber 110 may be fabricated at least in part from germanium oxide-based glass, sapphire, fluoride, zirconium fluoride, and / or silica. The optical fiber 110 may include a single material, a blend of materials, or may have distinct regions of different materials, etc. However, any suitable material or space for efficiently propagating the laser beams 104 and 108 is contemplated. The optical fiber 110 may be at least partially clad, single-clad, double-clad, multi-clad, or cladless. In embodiments having a clad, the clad may be concentric with one or more cores of the optical fiber 110. In some embodiments, the first laser beam 104 and / or the second laser beam 108 may propagate through the optical fiber 110 via the clad.

[0022] In some embodiments, the optical fiber 110 has a single-core structure. In such embodiments, the first laser beam 104 and the second laser beam 108 may propagate along the same core of the optical fiber 110. In other embodiments, the optical fiber 110 has a multi-core structure. In such embodiments, the first laser beam 104 and the second laser beam 108 may propagate along the same core or different cores of the optical fiber 110.

[0023] In general, optical fiber 110 can be rigid or flexible. In some embodiments, optical fiber 110 can be straight or tapered. In some embodiments, optical fiber 110 has a diameter of about 100 μm (micrometers) to about 400 μm, e.g., about 100 μm to about 300 μm, e.g., about 100 μm to about 200 μm, e.g., about 200 μm to about 400 μm, e.g., about 200 μm to about 300 μm, e.g., about 300 μm to about 400 μm. In some embodiments, optical fiber 110 can have different regions of similar or different shapes. In such embodiments, the different regions can include one or more optical fiber pieces butt-bonded to one another.

[0024] The optical fiber 110 may also be configured to distally receive and proximally propagate a reflected portion 120 of the second laser beam 108 that is reflected by and returned to the distal end 115 of the optical fiber 110 during power level measurements. Because at least one of the first laser beam 104 or the second laser beam 108 propagates in opposite directions within the optical fiber 110, the reflected portion 120 may pass within the optical fiber 110 along the same core or a different core of the optical fiber 110.

[0025] In some embodiments, the optical fiber 110 includes an optical fiber tip 114 disposed at a distal end 115 of the optical fiber 110 opposite the first laser source 102 and / or the second laser source 106. Generally, the first laser beam 104 and the second laser beam 108 may propagate through the optical fiber 110 and then be transmitted (i.e., emitted) distally from the optical fiber tip 114. The optical fiber tip 114 may be fabricated with a similar or different structure to the rest of the optical fiber 110. For example, the optical fiber tip 114 may differ from the rest of the optical fiber 110 in terms of material, material properties, optical properties, geometry, etc. For example, the optical fiber tip 114 may be rigid, while the rest of the optical fiber 110 may include a flexible portion to allow the optical fiber 114 to be positioned relative to the test material 112 or surgical site. In some embodiments, the optical fiber tip 114 includes a lens or window to facilitate distal transmission of the first laser beam 104 and the second laser beam 108 from the optical fiber 110. In some embodiments, the lens or window may comprise sapphire. In some embodiments, the fiber optic tip 114 is configured to be disposed within or integrated into a handpiece of a surgical instrument, such as an ophthalmic surgical laser probe. In some embodiments, the material of the fiber optic tip 114 is selected to be strong enough to withstand the impact of repeated bubble expansion and collapse and / or not chemically interact with the test substance 112. One example of such a material is sapphire.

[0026] In some embodiments, the optical fiber 110 and / or the system 100 may further include one or more optical elements configured to direct, redirect, filter, deflect, focus, collimate, split, or otherwise manipulate the first laser beam 104, the second laser beam 108, and / or the reflected portion 120 of the second laser beam 108. For example, in FIG. 1A , a first dichroic mirror 116 and a second dichroic mirror 118 are shown. Generally, the dichroic mirrors 116 and 118 can facilitate either reflection or transmission of a laser beam depending on its wavelength. In FIG. 1A , the first dichroic mirror 116 is shown to facilitate transmission of the first laser beam 104 and redirection (e.g., reflection) of the second laser beam 108 into the optical fiber 110, while also facilitating redirection of the proximally transmitted reflected portion 120 of the second laser beam 108 to the second dichroic mirror 118. A second dichroic mirror 118 then redirects the reflected portion 120 to an optical detector 122 (or any suitable type of signal detector).

[0027] 1A , a monofocal lens 121 is also shown. The monofocal lens 121 may be configured to focus at least one of the first laser beam 104 or the second laser beam 108 onto the optical fiber 110 at or through the port 130. For example, the monofocal lens 121 may be configured to focus at least one of the first laser beam 104 or the second laser beam 108 into the core of the optical fiber 110.

[0028] System 100 further includes an optical detector 122, which is configured to receive the reflected portion 120 and generate an optical detector output based on the reflected portion 120. In some embodiments, optical fiber 110 is configured to direct the reflected portion 120 of the second laser beam 108 to the optical detector 122 indirectly (e.g., through an air or other gap). In other embodiments, optical fiber 110 may direct the second laser beam 108 to the optical detector 122 through direct contact transmission. The optical detector 122 may include a sensor 124 (e.g., a photodiode or other energy-sensitive detection element) capable of detecting the reflected portion 120 of the second laser beam 108 incident on the optical detector 122 and further capable of generating an optical detector output.

[0029] In some embodiments, the optical detector output may be electrically amplified, hi other embodiments, the optical detector output may be passed through a high-pass filter to separate the transient back-reflected signal from the DC (direct current) baseline, or a high-pass filter may be used before or after the amplifier or between amplifier stages.

[0030] Optical detector 122 is coupled to a controller 126 configured to receive and analyze optical detector output from optical detector 122 corresponding to detected reflected portion 120 and identify various metrics / characteristics of reflected portion 120. Such metrics / characteristics of reflected portion 120 are utilized to determine the power level of laser light generated by at least first laser source 102 at optical fiber tip 114, as will be described in more detail below. Although optical detector 122 and controller 126 are shown in FIG. 1A as integrated components of surgical laser system 101, optical detector 122 and controller 126 may be separate components operably coupled to surgical laser system 101, such as components of a surgical console operably coupled to surgical laser system 101.

[0031] The system 100 may also include or be used in combination with a test material 112, with the optical fiber 110 configured to direct the first laser beam 104 and the second laser beam 108 therein to perform power level measurements of the first laser beam 104. In some embodiments, the optical fiber 110 may be positioned so that it is at least partially disposed in the test material 112 during use. In other embodiments, the optical fiber 110 may be positioned so that it contacts only the surface of the test material 112 during use. The optical fiber 110 is configured to emit the first laser beam 104 and the second laser beam 108 from the optical fiber 110 into the test material 112. In some embodiments, the test material 112 may include a liquid, such as water, saline, balanced salt solution (BSS), etc. In some embodiments, the test material 112 may include a viscoelastic material. Other examples may include liquid, semi-liquid, and / or semi-solid materials that form transient gas bubbles upon delivery of laser energy to the test material. In some embodiments, the test substance 112 is a disposable, or single-use, substance. In some embodiments, the test substance 112 can be a reusable, or multi-use, substance.

[0032] To measure the power level of the laser light generated by the first laser source 102, the optical fiber tip 114 is positioned in or near the test material 112, and the first laser source 102 is activated to generate a first laser beam 104. The first laser beam 104 is received at a proximal end of the optical fiber 110 and propagates distally within the optical fiber 110 for transmission from the optical fiber tip 114 into the test material 112. When the test material 112 receives the first laser beam 104, the thermal energy of the first laser beam 104 vaporizes or otherwise changes state or form, creating a bubble 113 or cavity in the test material 112 and near the optical fiber tip 114. Continued transmission of the first laser beam 104 through the test material 112 causes the resulting bubble 113 to expand until it collapses. In certain embodiments, thereafter, each time the first laser beam 104 is emitted / fired from the first laser source 102, a corresponding bubble may be generated. In general, different power levels of first laser beam 104 result in different bubble characteristics or bubble formation profiles of bubbles 113 .

[0033] Simultaneously with the first laser beam 104, a second laser beam 108 is generated and propagates distally through the optical fiber 110, exiting the optical fiber tip 114. Thus, the second laser beam 108 is transmitted to the interface between the test material 112 and the optical fiber tip 114 of the optical fiber 110. When the bubble 113 is formed by the thermal energy of the first laser beam 104 and expands, the refractive index for the second laser beam 108 at the interface changes because the interface changes, for example, from a solid-liquid (e.g., sapphire-BSS) interface to a solid-vapor (e.g., sapphire-vaporized BSS) interface. For example, the refractive index before the formation of the bubble 113 may be approximately equal to 1.33 between the optical fiber 110 and the test material 112. Once the bubble 113 is formed, the refractive index at the interface between the optical fiber 110 and the vapor in the bubble 113 may change to approximately 1.0.

[0034] The change in refractive index at the distal end of the optical fiber 110 results in a change in the Fresnel coefficient of the distal end of the optical fiber 110 and therefore in the optical behavior of the second laser beam 108 at the end of the optical fiber 110, causing more of the second laser beam 108 to reflect back through the optical fiber 110. For example, if an air bubble 113 is present, a greater portion of the second laser beam 108 may be temporarily reflected proximally within the optical fiber 110 by the optical fiber tip 114, while a lesser portion of the second laser beam 108 may pass into the test material. A portion of the transmitted portion of the laser beam may be further reflected from the inner surface of the air bubble 113 and return to the fiber.

[0035] The change in the optical behavior of the second laser beam 108 is detected by a sensor 124 of the optical detector 122, which continuously or non-continuously monitors / detects the reflected portion 120 of the second laser beam 108 and sends the optical detector output to a controller 126. The controller 126 coupled thereto can then analyze the detected signal to identify metrics / characteristics of the reflected portion 120, which can be correlated with predefined or predetermined bubble characteristics or bubble formation profiles and therefore the power of the first laser beam 104.

[0036] FIG. 1B illustrates another embodiment of the system 100 of FIG. 1A. As previously mentioned, additional optical components and / or relays are also contemplated for use with the system 100. The exemplary embodiment of FIG. 1B includes wave plates (e.g., half-wave plate 130, quarter-wave plate 132), polarizing elements (polarizer 134, polarizing cube 136), reflectors (e.g., reflectors 138, 140, 142), dichroic elements (e.g., dichroic 144), lenses (e.g., focusing lenses 146, 148, collimators, etc.), and others. In some examples, optical components may be used to facilitate power modulation, laser light separation, transmission of identified wavelengths, etc. One or more components may include coatings (e.g., anti-reflective coatings), materials, diffraction gratings, films, etc., to separate wavelengths, separate the laser from the back-reflected beam, or otherwise. In some embodiments, physical structures may be used to transmit the light. In other embodiments, the light may be transmitted through free space. In some embodiments, light may be transmitted through a combination of physical structures and free space.

[0037] It should be noted that other surgical laser systems are contemplated for use with the present systems and methods for real-time laser power measurement, including those described in U.S. Patent Application No. 17 / 662,148, entitled "Surgical Laser System with Illumination," filed May 5, 2022 (U.S. Patent Application Publication No. 20220354692), which is incorporated herein by reference in its entirety.

[0038] Figure 2 illustrates a method 200 of performing laser power measurements using system 100, according to certain embodiments described herein. Figures 3A-3F illustrate one or more operations of method 200. Thus, Figure 2 and Figures 3A-3F are described together herein, where necessary, for clarity.

[0039] Referring to FIG. 2, in block 202 of the method 200, a first laser beam 104 is generated by a first laser source 102.

[0040] In block 204, the second laser beam 108 is generated by the first laser source 102 or the second laser source 106. In some embodiments, the second laser beam 108 is generated simultaneously with the first laser beam 104. In some embodiments, the second laser beam 108 is generated sequentially with the first laser beam 104. For example, the second laser beam 108 can be generated before generating the first laser beam 104, or vice versa.

[0041] In block 206 of the method 200, the first laser beam 104 is received from the first laser source 102 into the optical fiber 110, which may be an optical fiber having one or more cores and / or claddings for simultaneously or sequentially propagating the first laser beam 104 and the second laser beam 108. In other embodiments, the optical fiber may be an unclad fiber, such as an unclad sapphire rod or fiber.

[0042] In block 208, the optical fiber 110 directs (e.g., propagates) the first laser beam 104 toward the test material 112 to form a gas bubble 113 in the test material 112. As described above, the test material 112 may include a liquid such as water, saline, balanced salt solution (BSS), etc. The formation of the gas bubble 113 briefly changes the refractive index of the test material 112 and, therefore, the reflection coefficient of the interface between the optical fiber tip 114 of the optical fiber 110 and the test material 112.

[0043] 3A-3F illustrate the formation of a bubble 113 in block 208. Specifically, in FIG. 3A, a first laser beam 104 is transmitted from an optical fiber tip 114 into the test material 112. As energy from the first laser beam 104 interacts with the test material 112, a first stage bubble 113A begins to form. The formation of the first stage bubble 113A is represented by the separation of the test material 112 from the optical fiber tip 114.

[0044] 3B, second stage bubble 113B continues to expand, thereby increasing in volume relative to first stage bubble 113A. The expansion of second stage bubble 113B is due to the expansion of vapor within bubble 113B caused by the energy of first laser beam 104.

[0045] In FIG. 3C, the third stage bubble 113C reaches a peak volume when the vapor pressure and dynamic movement of the bubble 113 reaches equilibrium with the pressure of the test substance 112.

[0046] In FIG. 3D, the fourth stage bubble 113D begins to collapse, thus reducing its volume and allowing the test substance 112 to move closer to the optical fiber tip 114 as the energy from the bubble 113 dissipates.

[0047] In FIG. 3E, the volume of the fifth stage bubble 113E continues to decrease, and the fifth stage bubble 113E begins to separate from the optical fiber tip 114 during collapse.

[0048] In FIG. 3F, the sixth stage bubble 113F is sufficiently separated from the optical fiber tip 114, and the test substance 112 is completely interposed between the sixth stage bubble 113F and the optical fiber tip 114.

[0049] Now, referring back to FIG. 2, in block 210 of the method 200, the second laser beam 108 is propagated into the optical fiber 110 by the second laser source 106.

[0050] 1A, the second laser beam 108 is directed through the optical fiber 110 toward the test material 112. In some embodiments, the second laser beam 108 may be carried within the same core of the optical fiber 110 as the first laser beam 104, or within a different core in instances where the optical fiber 110 includes a multi-core configuration. In some embodiments, the optical fiber 110 may be cladding, and the first laser beam 104 and / or the second laser beam 108 propagate within the cladding.

[0051] In block 214 of method 200, a portion of second laser beam 108 (e.g., reflected portion 120) is reflected back from the interface between optical fiber tip 114 and test substance 112 and received by optical fiber 110. When gas bubble 113 is formed, gas bubble 113 changes the reflection coefficient of the interface between optical fiber tip 114 and test substance 112, thereby causing a temporal modulation of back-reflected portion 120. In certain embodiments, a portion of second laser beam 108 may reflect from within gas bubble 113 back into optical fiber 110.

[0052] In block 216, the reflected portion 120 of the second laser beam 108 propagates back through the optical fiber 110 and is directed (such as by using one or more optical components or a relay) to an optical detector 122.

[0053] At block 218, the method 200 includes receiving the reflected portion 120 of the second laser beam 108 at the sensor 124 and generating, by the sensor 124 and / or the optical detector 122, an optical detector output (e.g., a signal) based on the received reflected portion 120. In some embodiments, the optical detector output is a signal profile (e.g., a measured reflected time signal, described below in FIGS. 4A and 4B ).

[0054] In some embodiments, the optical detector output may be electrically amplified, in other embodiments the electrical detector output may be passed through a high pass filter to separate the transient back-reflected signal from the DC baseline, or a high pass filter may be used before or after the amplifier or between amplifier stages.

[0055] At block 220, the method 200 includes determining a power level of the first laser beam 104 in real time based on the optical detector output. For example, in some embodiments, various features and / or characteristics of the signal profile of the reflected portion 120 may be correlated with predetermined or defined signal profile features and / or characteristics corresponding to one or more power levels of the first laser beam 104. Such features and / or characteristics may include the number of peaks, the duration of the peaks, the rise time, the fall time, etc. In some embodiments, the signal profile of the reflected portion 120 corresponds to the lifetime of a single bubble 113 formed as a result of projecting the first laser beam 104 into the test material 112. Thus, in some embodiments, the power level of the first laser beam 104 may be determined based on the duration component of the reflected portion 120 determined from the optical detector output.

[0056] 4A and 4B, there are shown exemplary signal profiles of the reflected portion 120 of the second laser beam 108 during the formation and collapse of a gas bubble 113 in the test material 112 as detected by an optical detector 122, according to certain embodiments described herein. While a particular shape of the signal profile is shown, other shapes are possible and may also provide power measurement capabilities.

[0057] 4A shows a signal profile 400 corresponding to the formation and collapse of a bubble 113 caused by the first laser beam 104 at a particular power level. The signal profile 400 includes a plot of signal voltage values ​​over time for the reflected portion 120 of the second laser beam 108. In the illustrated example, the signal profile 400 for the reflected portion 120 includes a first peak 402 (and a drop) corresponding to the first stage bubble 113A of FIG. 3A. The first peak 402 may exhibit a slightly elevated reflectivity because the interface between the first stage bubble 113A and the test material 112 may still be close to the optical fiber tip 114 but is beginning to separate therefrom, causing a subsequent drop in reflectivity after the first peak 402.

[0058] After the first peak 402, the signal profile 400 steadily rises, corresponding to the formation of a second-stage bubble 113B as the vapor in the bubble 113 expands. During the formation of the second-stage bubble 113B, a greater portion of the second laser beam 108 is reflected by the optical fiber tip 114. In the illustrated example, the signal profile 400 includes a second peak 404, corresponding to the formation of a third-stage bubble 113C. The third-stage bubble 113C may represent the maximum volume of the bubble 113, at which point the vapor pressure within the bubble 113 equilibrates with the resistance of the test substance 112. Because the density of the vapor within the bubble 113 may be lowest at the third-stage bubble 113C, the signal profile 400 may be highest at this second peak 404 based on the refractive index at the optical fiber tip 114. As the bubble 113 transforms into a fourth stage bubble 113D, the signal profile 400 begins to decrease, dropping more sharply as the bubble 113 rapidly collapses into a fifth stage bubble 113E. In this exemplary embodiment, the separation of the bubble 113 from the optical fiber tip 114 at sixth stage bubble 113F may return a steady state value at the optical detector 122, indicating the end of the bubble's 113 life.

[0059] 4B , a graph 406 of 14 different signal profiles 400 is shown, where each of the 14 illustrated signal profiles 400 includes a plot of signal voltage values ​​over time. Each of the different signal profiles 400 may correspond to a different power level output by the first laser source 102 when generating the first laser beam 104. In the illustrated example, it can be seen that increasing the output power (mW) of the first laser source 102 results in a longer time trace of the corresponding signal profile 400. As further shown, increasing the output power also produces a signal profile 400 with a higher intensity peak of the second laser beam 108 (e.g., corresponding to more recovery of back-reflected light from the curved surface of the bubble).

[0060] Once desired characteristics / features of a signal profile 400 have been identified, such as the pulse width or duration of the signal profile 400, such characteristics / features may be mapped to one or more predetermined correlation curves to identify the power level of the first laser beam 104. In some embodiments, the correlation curve may depend, at least in part, on the phase transition enthalpy of the test material 112, the diameter of the optical fiber 110, the pulse wavelength and / or duration of the first laser source 102, etc. An example of a correlation curve 502 is shown in FIG. 5. In the illustrated example, characteristic measurements of the signal profile 400 are shown as test value points 504 located along or substantially along the correlation curve 502, which was previously based on a standardized sample. Using correlation curves similar to correlation curve 502, a user may be able to identify the pulse energy of the first laser beam 104 and the power of the first laser source 102 based on the measured characteristics of the backreflected signal profile 400 of the second laser beam 108.

[0061] In some embodiments, the correlation curve 502 may be tailored to correspond to a particular test material 112 or group of test materials. As an example, if the test material 112 is a BSS, a corresponding correlation curve may be selected to identify the power level of the first laser beam 104. Similarly, a specific correlation curve may be established for at least one of the first laser source 102, the optical fiber 110, the optical fiber tip 114, etc.

[0062] In some embodiments, the lifetime of a laser-generated bubble 113 in the liquid test material 112 is determined by the formula T=C(E−Ethreshold) 1 / 3 where T is the bubble lifetime (μsec) (microseconds), E is the energy of the laser pulse that generates the bubble (μJ) (microjoules), and C and Ethreshold are constants that depend on the properties of the liquid test material 112, the laser source 102, and the light delivery mechanism (e.g., the optical fiber 110 and associated optics). For example, for a test material 113 consisting of water, the constant C may be equal to or substantially equal to 13.3.

[0063] In some embodiments, a particular surgical laser system 101 or surgical console may include one or more laser sources (e.g., laser sources 102 and / or 108), a fiber optic delivery system (e.g., the optical fiber 110 and other optical elements of the surgical laser system or console), and a test substance 112, for which a correlation curve 502 may be measured in a non-sterile environment prior to performing a surgical procedure. For example, the power output of the first laser source 102 at the optical fiber tip 114 may be measured using a power meter, and the dependence of the temporal backreflection pulse width versus the first laser pulse energy may be recorded as a correlation curve for future use.

[0064] The correlation curve 502 is obtained by measuring the temporal signal pulse width of the reflected portion 120 at several pulse energy levels (e.g., 40%, 50%, 60%, 70%, 80%, 90%, and 100% of the maximum pulse energy) of the first laser source 102 that generates the bubbles, and plotting the pulse width versus energy data points using the aforementioned T=C(E-Ethreshold) 1 / 3 By fitting the function and obtaining values ​​for C and Ethreshold, it can also be established in a sterile environment.

[0065] FIG. 6 shows a schematic diagram of a controller 602 according to embodiments disclosed herein. The controller 602 generally represents the aforementioned controller 126 and may be integral with or operably coupled to a surgical console. In some embodiments, the controller 602 includes a user interface 606, interconnections 608, and at least one I / O (input / output) device interface 610 that may allow various I / O devices (e.g., keyboard, display, mouse device, pen input, etc.) to be connected to the controller 602. The controller 602 may communicate wired or wirelessly via the interconnections 608 with one or more laser sources 612 (e.g., first laser source 102 and / or second laser source 106 of FIG. 1A) and one or more optical detectors 614 (e.g., see optical detector 122 of FIG. 1A with sensor 124). In some embodiments, in addition to or alternatively to the controller 126, one or more laser sources 612 and / or one or more optical detectors 614 may be integral with or operably coupled to the surgical console.

[0066] The controller 602 further includes a CPU 604 (central processing unit), a memory 616, and storage 618. The CPU 604 is configured to retrieve and execute programming instructions stored in the memory 616. Similarly, the CPU 604 may retrieve and store application data in the memory 616. The interconnects 608 transmit the programming instructions and application data between the CPU 604, the I / O device interface 610, the user interface 606, the memory 616, the storage 618, the laser source 612, the optical detector 614, etc. The CPU 604 may include a single CPU, multiple CPUs, a single CPU with multiple processing cores, etc. The memory 616 may be random access memory, and the storage 618 may be a disk drive. Furthermore, the memory 616 and / or the storage 618 may be any type of readily available memory, such as random access memory (RAM), read-only memory (ROM), a floppy disk, a hard disk, a solid-state drive, flash memory, magnetic memory, or any other form of digital storage, local or remote. In certain embodiments, memory 616 and / or storage 618 include instructions that, when executed by CPU 604, may affect the identification / measurement of the power level of laser source 612 based on data received from optical detector 614. In certain embodiments, CPU 604, memory 616, and storage 618 may be the main processor and memory of controller 602.

[0067] 6, the CPU 604 of the controller 602 may include an integrated circuit capable of performing logic functions. As such, the CPU 604 is in the form of a standard integrated circuit package with power, input, and output pins. In other embodiments, the CPU 604 is a microprocessor. In other cases, the CPU 604 is not a programmable microprocessor, but instead is a dedicated controller.

[0068] 6, the controller 602 receives signals from one or more optical detectors 614. These signals may include, for example, optical detector outputs corresponding to reflected light received at sensors of the one or more optical detectors 614.

[0069] As shown, storage 618 includes material profiles 620 representing various types of test materials. For example, material profiles 620 may include information corresponding to different test materials (e.g., saline, water, BSS, etc.), which may be utilized to generate correlation curves or identify power levels for laser source 612 based on generated correlation curves. In some embodiments, material profiles 620 may include bubble formation characteristics of the corresponding test materials. In some embodiments, each material profile 620 stored in storage 618 may include one or more generated correlation curves 622 corresponding to the material in material profile 620. Correlation curves 622 may be retrieved by power level module 624 in memory 616 to identify power for laser source 612 based on optical detector outputs received from one or more optical detectors 614.

[0070] As shown, memory 616 includes a correlation curve generator 624 and a power level module 626. When operated, correlation curve generator 624 utilizes signals received from one or more optical detectors 614 to generate a correlation curve for a test material, which may be stored in a corresponding material profile 620. Meanwhile, when executed, power level module 626 utilizes signals received from one or more optical detectors 614 in combination with one or more correlation curves 622 stored in storage 618 to determine the power of laser source 612. In certain embodiments, after the power of laser source 612 is determined by power level module 626, controller 602 may output the determined power to a user graphical display or other I / O device in communication with controller 602 via I / O device interface 610.

[0071] In summary, embodiments of the present disclosure include systems and methods for laser power measurement, and more specifically, for laser power measurement in a sterile work environment. In certain embodiments described herein, power measurements are made utilizing two laser sources: 1) a first laser source configured to generate a first laser beam (a treatment laser) and 2) a second laser source configured to generate a second laser beam (a test laser). The first laser beam generates gas bubbles in a test material (e.g., water, saline, balanced salt solution, gel, etc.), the second laser beam is reflected back, and the reflected portion of the second laser beam is measured to determine the bubble's lifetime, and the lifetime measurement is correlated with a power value based on a correlation curve. Laser power measurements using the returned reflection of the second laser beam enable testing in a sterile environment, and embodiments may enable testing during surgery. Inspection of laser power levels can identify equipment problems, including improper assembly, component malfunctions, movement before or during surgery, or misalignment through use. Thus, the methods and systems described herein not only improve the safety of testing in a sterile environment, but also improve the ability to test laser power levels before and during operation without introducing contaminants.

[0072] The subject matter disclosed above is to be considered illustrative, not limiting, and the appended claims are intended to cover all modifications, improvements, and other embodiments within the true spirit and scope of the present disclosure. Accordingly, to the maximum extent permitted by law, the scope of the present disclosure shall be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be limited or constrained by the foregoing detailed description.

Claims

1. 1. A system for laser power and pulse energy measurement, comprising: a first laser source configured to generate a first laser beam in pulsed form; a second laser source configured to generate a second laser beam; An optical fiber, receiving the first laser beam from the first laser source; directing the first laser beam at a test material to form a gas bubble in the test material; receiving the second laser beam from the second laser source; directing the second laser beam at the test material; receiving a reflected portion of the second laser beam from an interface between the test material and the optical fiber; directing the reflected portion of the second laser beam to an optical detector; and the optical detector is configured to: receiving the reflected portion of the second laser beam from the optical fiber; generating an optical detector output based on the reflected portion of the second laser beam; an optical fiber configured to perform the above operation, wherein a waveform shape of the optical detector output depends on a pulse energy of the first laser beam; a controller configured to determine the power and the pulse energy of the first laser beam based on the optical detector output; A system including:

2. The system of claim 1 , wherein the optical detector comprises a photodiode light sensor configured to generate the optical detector output.

3. 10. The system of claim 1, wherein the optical detector is further configured to measure the lifetime of the bubble by identifying a change in reflectivity of the second laser beam caused by a change in refractive index at an interface of the optical fiber.

4. The system of claim 1 , wherein at least a portion of the optical fiber comprises sapphire.

5. The system of claim 1 , further comprising a dichroic element positioned to direct the second laser beam from the second laser source into the optical fiber.

6. The system of claim 1 , wherein the first laser beam comprises infrared laser light.

7. 10. The system of claim 1, wherein the optical detector output is filtered by a high pass filter before the controller determines the power and the pulse energy of the first laser beam.

8. generating a first laser beam in pulsed form with a first laser source; generating a second laser beam with a second laser source; receiving the first laser beam from the first laser source via an optical fiber; directing the first laser beam through the optical fiber toward a test material to form a gas bubble in the test material; receiving the second laser beam from the second laser source at the optical fiber; directing the second laser beam toward the test material through the optical fiber; receiving, at the optical fiber, a reflected portion of the second laser beam from an interface between the test material and the optical fiber; directing the reflected portion of the second laser beam to an optical detector via the optical fiber; receiving the reflected portion of the second laser beam from the optical fiber at the optical detector; determining, by a controller in communication with the optical detector, a power and pulse energy of the first laser beam based on the change in the reflected portion of the second laser beam received at the optical detector; A method comprising:

9. The method of claim 8 , wherein the optical detector comprises a photodiode light sensor.

10. 9. The method of claim 8, wherein the optical detector and controller are further configured to measure the lifetime of the bubble by identifying a change in reflectivity of the second laser beam due to a change in refractive index at the interface between the optical fiber and the test material.

11. The method of claim 8 , wherein at least a portion of the optical fiber comprises sapphire.

12. The method of claim 8 , wherein the first laser beam comprises an infrared laser.

13. 9. The method of claim 8, wherein the optical detector output is filtered by a high pass filter before determining the power and pulse energy of the first laser beam.

14. 10. The method of claim 8, wherein the identifying the power and the pulse energy of the first laser beam is further based on a correlation curve correlating a pulse energy level of the first laser beam with a pulse width of the reflected portion of the second laser.

15. The correlation curve is calculated by measuring the pulse width of the reflected portion of the second laser beam at several partial pulse energy levels of the first laser beam and applying the measurements to the equation T=C(E−Ethreshold) １／３ The method of claim 14 wherein the distance is determined by fitting

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