Method and system for estimating distance between fiber end and target - Patents.com

Abstract

The present disclosure relates to the field of fiber feedback (FFB) technology and provides a method and system for estimating the distance between a fiber end and a target. The method includes illuminating a target with laser light of different wavelengths having low and high water absorption coefficients using different laser light sources and receiving return signals corresponding to the incident laser light of different wavelengths by a light emission, transmission, and detection (LETD) system, and detecting the return signals and measuring the intensity values ​​of the return signals of the specific wavelengths. Using the measured intensity values, a processing unit can estimate the distance between the fiber end and the target. The present disclosure allows for accurate estimation of the distance between the fiber end and the target. The invention disclosure also provides a robust distance estimation technique that is compatible with different types of targets.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 341,654, filed May 13, 2022, and entitled "Method and System for Estimating Distance Between a Fiber End and a Target," and U.S. Provisional Patent Application No. 63 / 118,857, filed November 27, 2020, and entitled "Method and System for Estimating Distance Between a Fiber End and a Target," U.S. Provisional Patent Application No. 63 / 118,117, filed November 25, 2020, and entitled "Apparatus and Method for Enhancing Laser Beam Efficacy in a Liquid Medium," and U.S. Provisional Patent Application No. 63 / 118,117, filed October 6, 2021, and entitled "Method and System for Estimating Distance Between a Fiber End and a Target." This application is a continuation-in-part of U.S. patent application Ser. No. 17 / 535,172, entitled "Method and System for Estimating Distance Between a Fiber End and a Target," filed on November 24, 2021, which claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 252,830, entitled "Method and System for Estimating Distance Between a Fiber End and a Target," the entireties of which are incorporated by reference herein.

[0002] The present disclosure relates generally to optical systems and optical fibers used in medical or therapeutic laser procedures. More specifically, but not exclusively, the present disclosure relates to a method and system for estimating the distance between a fiber end and a target. [Background technology]

[0003] The introduction of lasers in the medical field and the development of fiber optic technology using lasers has opened up numerous applications in treatment, diagnosis, and therapy. Such applications range from invasive and non-invasive treatments to endoscopic surgery and imaging. For example, in urinary stone treatment, stones are required to be fragmented into smaller fragments. For such fragmentation processes, a technique known as laser lithotripsy may be used where a rigid or flexible ureteroscope is placed through the urinary tract for illumination and imaging for small to medium sized urinary stones. At the same time, an optical fiber is inserted through the working channel of the ureteroscope to the target location (e.g., in the bladder, ureter, or kidney where the stone is located). The laser is then activated to fragment the stone into smaller fragments or pulverize it. In another case, laser and fiber optic technology is used for coagulation and ablation procedures. During ablation procedures, laser light is delivered to tissue to vaporize the tissue. During coagulation procedures, laser light is used to induce thermal damage in the tissue. Such ablation procedures may be used to treat a variety of clinical diseases, such as cancers, such as benign prostatic hyperplasia (BPH), prostate cancer, liver cancer, and lung cancer, and to treat cardiac diseases by ablating and / or coagulating portions of tissue within the heart.

[0004] These procedures using laser and fiber optic technology require high precision to ensure that the laser is aimed at the correct target (stone, tissue, tumor, etc.) to achieve clinical objectives such as tissue ablation, coagulation, stone fragmentation, and pulverization. Therefore, it is important to know the distance between the target and the end (distal tip) of the optical fiber from which the laser light is emitted, since laser procedure parameters such as energy, pulse width, laser power adjustment, and / or repetition rate are often determined based on the distance between the tip of the optical fiber and the target. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Provisional Patent Application No. 63 / 118,117 Summary of the Invention [Problem to be solved by the invention]

[0006] One of the existing techniques for estimating the distance between the distal end of an optical fiber and a target provides for measuring and comparing the reflected intensity values ​​of a light beam, where the light beam is transmitted through the optical fiber by adjusting the numerical aperture of the light beam. However, it is not always convenient to shift the numerical aperture of the light beam. Moreover, it is difficult to separate the reflections of light beams of different numerical apertures, which is required for these techniques. [Means for solving the problem]

[0007] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to necessarily identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter.

[0008] An embodiment includes a system including a first laser source generating laser light at a first wavelength, a second laser source generating laser light at a second wavelength, an optical fiber having a distal end and a proximal end, the optical fiber configured to receive laser light from the first and second laser sources at the proximal end, reflect a portion of the laser light from the proximal end, emit a portion of the laser light from the distal end, and receive the reflected laser light into the distal end, a first photodetector measuring an intensity of the reflected light, a second photodetector, and a mirror directing the portion of the laser light reflected from the proximal end to the second photodetector, where the second photodetector measures an intensity of the portion of the laser light reflected from the proximal end, and a processor and memory including instructions that, when executed by the processor, cause the processor to estimate a distance between the distal end of the optical fiber and a target based on the intensity of the reflected light measured by the first photodetector and the intensity of the portion of the laser light reflected from the proximal end measured by the second photodetector.

[0009] The system can include a feature in which the first wavelength has a first water extinction coefficient that is higher than a second water extinction coefficient of the second wavelength.

[0010] The system may include a feature where the ratio of the first water extinction coefficient to the second water extinction coefficient is at least two to one.

[0011] The system may include the feature that the first wavelength is from about 1330 nm to about 1380 nm.

[0012] The system may include the feature that the second wavelength is from about 1260 nm to about 1320 nm.

[0013] The system may include a third laser source generating laser light at a third wavelength utilized to characterize the condition of the optical fiber, the third wavelength being characterized by a third water extinction coefficient that is higher than the first and second water extinction coefficients.

[0014] The system can include the feature that the third wavelength includes a wavelength between about 1435 nm, about 2100 nm, or between about 1870 nm and about 2050 nm.

[0015] The system can include the feature that the photodetector measures a first intensity value of the reflected light corresponding to the laser light of the first wavelength and a second intensity value of the reflected light corresponding to the laser light of the second wavelength.

[0016] The system can include the feature that when the instruction is executed by the processor, the processor further calculates the ratio of the first intensity value to the second intensity value, and estimates the distance between the distal end of the optical fiber and the target based on the ratio of the first intensity value to the second intensity value.

[0017] The system can include the feature that one or more of the first and second laser sources include a polarization-maintaining pigtail fiber laser, a single-mode pigtail fiber laser, or a free-space laser.

[0018] The system includes a wavelength division multiplexer (WDM) coupled to the proximal end of the optical fiber, and the WDM can include the feature of arranging the laser light of the first wavelength and the laser light of the second wavelength to be incident on the proximal end of the optical fiber at one or more of the same point and the same angle.

[0019] An embodiment includes a method comprising illuminating a target with laser light of a plurality of different wavelengths, receiving a first reflected light beam from the target through an optical fiber, receiving a second reflected light beam from the proximal end of the optical fiber, measuring the intensities of the first and second reflected light beams using a plurality of photodetectors, and estimating the distance between the distal end of the optical fiber and the target based on the intensities of the reflected light beams measured using one or more photodetectors.

[0020] The method can include the feature of emitting laser light of a plurality of different wavelengths through an optical fiber to illuminate the target.

[0021] The method may include a feature including measuring a first intensity value of a reflected light beam corresponding to the laser light at a first wavelength and a second intensity value of a reflected light beam corresponding to the laser light at a second wavelength.

[0022] The method may include features including calculating a ratio between the first intensity value and the second intensity value, and estimating a distance between the distal end of the optical fiber and the target based on the ratio between the first intensity value and the second intensity value.

[0023] An embodiment includes at least one non-transitory computer-readable medium including a set of instructions that, in response to being executed by the processor circuit, cause the processor circuit to determine a first intensity value based on a first reflected laser light corresponding to the laser source and incident on the proximal end of the optical fiber, exit the distal end of the optical fiber, reflect off the target, and incident on the distal end of the optical fiber, determine a second intensity value based on a second reflected laser light corresponding to the laser source and reflecting off the proximal end of the optical fiber, calculate a ratio between the first intensity value and the second intensity value, and estimate a distance between the distal end of the optical fiber and the target based on the ratio of the first intensity value and the second intensity value.

[0024] The at least one non-transitory computer readable medium can include a feature where the set of instructions, responsive to execution by the processor circuit, further causes the processor circuit to subtract the first internal reflectance value from the first measured intensity value to determine a first intensity value, and to subtract the second internal reflectance value from the second measured intensity value to determine a second intensity value.

[0025] The at least one non-transitory computer readable medium can include a feature where the set of instructions, in response to execution by the processor circuit, further causes the processor circuit to determine an internal reflectance value based on a third reflected laser light corresponding to the laser light at a third wavelength, the laser light at the third wavelength emitting from the laser source, and at least a portion of the third reflected laser light being reflected by the distal end of the optical fiber.

[0026] The at least one non-transitory computer-readable medium can include a feature where the set of instructions, in response to execution by the processor circuit, further causes the processor circuit to compare the internal reflectance value to a baseline internal reflectance value, and adjust an operating parameter of the treatment beam based on the comparison of the internal reflectance value to the baseline internal reflectance value.

[0027] The at least one non-transitory computer-readable medium may include a feature where the set of instructions, in response to execution by the processor circuit, further causes the processor circuit to compare the internal reflectance value with a baseline internal reflectance value, characterize a condition of the optical fiber based on a comparison of the internal reflectance value with the baseline internal reflectance value, and communicate an indication of the condition of the optical fiber through a user interface.

[0028] The at least one non-transitory computer-readable medium can include a feature where the set of instructions, in response to execution by the processor circuit, further causes the processor circuit to communicate an indication of the estimated distance between the distal end of the optical fiber and the target through a user interface.

[0029] To easily identify the discussion of any particular element or act, the most significant digit(s) of a reference number refers to the number of the figure in which that element is first introduced. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 illustrates a system according to one embodiment. [Diagram 2] FIG. 1 illustrates an example fiber optic cable according to one embodiment. [Diagram 3] FIG. 1 illustrates an LETD system according to one embodiment. [Figure 4] FIG. 1 illustrates another LETD system according to one embodiment. [Diagram 5] FIG. 1 illustrates another LETD system according to one embodiment. [Figure 6]A diagram illustrating another LETD system according to an embodiment. [Figure 7] A diagram illustrating another LETD system according to an embodiment. [Figure 8] A diagram illustrating another LETD system according to an embodiment. [Figure 9] A diagram illustrating another LETD system according to an embodiment. [Figure 10] A diagram illustrating another LETD system according to an embodiment. [Figure 11] A diagram illustrating another LETD system according to an embodiment. [Figure 12] A diagram illustrating a method according to an embodiment. [Figure 13] A diagram illustrating another method according to an embodiment. [Figure 14] A diagram illustrating another method according to an embodiment. [Figure 15] A diagram illustrating another LETD system according to an embodiment. [Figure 16] A diagram illustrating another method according to an embodiment. [Figure 17] A diagram illustrating another LETD system according to an embodiment. [Figure 18] A diagram illustrating a computer-readable storage medium according to an embodiment. [Figure 19] A diagram illustrating another system according to an embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The present disclosure provides a method and system for estimating the distance between an optical fiber tip and a target. It is recognized that the efficiency of a laser-based procedure often depends on the relative position and orientation of the optical fiber tip with respect to the target. However, due to various factors such as optical fiber movement relative to the position and orientation within the subject's (e.g., patient's) body, tissue environment, tissue movement, target surface, target color, target pigment, degradation of the optical fiber tip during the procedure, water washing, and a turbid environment (e.g., due to powdering), determining the distance between the optical fiber tip and the target is extremely difficult. The step of determining the distance between the optical fiber tip and the target is generally further complicated by the insertion of the optical fiber tip into the subject's body.

[0032] Inaccurate estimation of the distance between the fiber end and the target and inaccurate estimation of the orientation of the fiber end may lead to aiming the laser at an area that is not of interest on the target, which may lead to unnecessary complications and in some cases may cause permanent damage to certain parts of the subject's tissues, organs, etc., and may even cause parts of the subject's body to fail. In some other scenarios, inaccurate measurement of the distance and orientation may lead to longer procedure times or poor ablation / disruption results. In some cases, such as BPH or cancer, if the tumor is not properly ablated, this may lead to regrowth of the tumor (or other undesirable tissue), leading to further complications. Therefore, it is important to determine the exact distance (or maintain the desired distance) between the fiber tip and the target while performing certain procedures using laser and fiber optic techniques as discussed above.

[0033] The method includes illuminating a target with different wavelengths having high and low water extinction coefficients using different laser light sources by an optical emission, transmission, and detection (LETD) system. These wavelengths can be selected to be close to each other and belong to the same "nm scale". Additionally, the LETD system receives return signals corresponding to the incident lasers of different wavelengths. The return signals include light beams reflected from the illumination of the target posts. One or more photodetectors configured in the LETD system can detect the return signals and measure intensity values ​​of the return signals of specific wavelengths. Using the measured intensity values, a processing unit can then estimate the distance between the fiber end and the target.

[0034] The present disclosure uses the above-mentioned LETD system in various configurations including various arrangements of beam combiners, beam splitters, polarizers, collimators, wavelength division multiplexers (WDMs), and photodetectors. The present disclosure allows for accurate estimation of the distance between the fiber end and the target. Furthermore, the present disclosure provides a robust distance estimation technique that is compatible with different types of targets. Furthermore, the present disclosure can be used to control and / or adjust one or more operating parameters. For example, during a procedure, the target may move around, retreat, advance, or otherwise shift, or may change one or more of its shape, size, composition, pigment, and color. Thus, parameters associated with the laser source that are preset before starting lasing on the target may become less effective. Conventionally, such preset parameters are changed manually, which may be error-prone and time-consuming, or in some cases the preset parameters may be left unchanged, leading to scenarios where the optical fiber may be too close or too far from the target. Thus, the present disclosure allows for automatic real-time monitoring of the distance between the end of the optical fiber and the target, and further allows for adjusting the lasing according to the target's shape, location, etc., and automatically altering pre-set lasing parameters to provide a greater likelihood of obtaining a desired result or outcome from the procedure.

[0035] The foregoing has outlined the features and technical advantages of the present disclosure in order that the detailed description of the present disclosure that follows may be more clearly understood. It will be appreciated by those skilled in the art that the disclosed embodiments may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. The novel features of the present disclosure, both as to its organization and method of operation, together with further objects and advantages, will be more clearly understood from the following description when considered in connection with the accompanying drawings. It is to be expressly understood, however, that each of these figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

[0036] 1 illustrates an exemplary system 100 for estimating a distance between a fiber end and a target according to some embodiments of the present disclosure. In some embodiments, the exemplary system 100 includes a target 102, an optical fiber 104, a light emission, transmission, and detection (LETD) system 106, a processing unit 108, and an indicator 110. The target 102 may be tissue, a stone, a tumor, a cyst, etc., within a subject's body to be treated, cauterized, or destroyed. In some embodiments, the subject may be a human or an animal.

[0037] 2, the optical fiber 104 includes a proximal end 202 and a distal end 204. The proximal end 202 is the end of the optical fiber 104 through which the light beam 112 enters, whereas the distal end 204 is the end of the optical fiber 104 that allows the light beam 112 to be emitted and directed onto the target 102. For example, this figure depicts the light beam 112 entering the optical fiber 104 at the proximal end 202, propagating longitudinally through the optical fiber 104, exiting the optical fiber 104 at the distal end 204, and entering the target 102 from the distal end 204 of the optical fiber 104.

[0038] Returning to Figure 1, the light beam can be a beam directed from a light source (such as included in the LETD system 106). The light source can be a laser light source. By way of example, such laser light sources can include, but are not limited to, solid-state lasers, gas lasers, diode lasers, and fiber lasers. The light beam 112 can include one or more of an aiming beam, a treatment beam, and any other beam transmitted through the optical fiber 104.

[0039] In various embodiments, the aiming beam can include a low-intensity light beam transmitted through the optical fiber 104 to estimate the distance between the optical fiber end (e.g., the distal end 204) and the target 102. In some embodiments, the treatment beam can include a high-intensity light beam transmitted through the optical fiber 104 to treat the target 102. In some embodiments, the different light beams can be generated by one or more laser light sources. As a specific example, the aiming beam can be generated by one laser source and the treatment beam can be generated by another laser source. In another example, both the aiming beam and the treatment beam can be generated by a single laser source. In yet another example, different laser light sources can be used to generate light beams of different wavelengths, characteristics, etc. This is described in more detail below, for example, with respect to FIG. 3 through FIG.

[0040] 1, the optical fiber 104 may be in optical communication with the LETD system 106 and is arranged to receive a light beam to be aimed at the target 102 and to transmit a reflected light beam reflected from the surface and surrounding area of ​​the target 102. In some embodiments, the optical fiber 104 may be optically, mechanically, and / or electrically coupled to the LETD system 106 through a port (shown in other figures described herein).

[0041] In some embodiments, the LETD system 106 includes optical components that may include, but are not limited to, one or more of the following: laser sources, polarizers, beam splitters, beam combiners, photodetectors, wavelength division multiplexers, collimators, and circulators configured in various combinations as described in detail further elsewhere in this disclosure.

[0042] In many embodiments, the laser sources are configured to generate laser light beams, such as a low intensity aiming beam for aiming the light beam 112 at the target 102, a high intensity treatment beam for treating the target 102, and / or light beams with characteristics (e.g., intensity, wavelength, etc.) that vary based on the application. Each laser source can be configured to generate laser light having a different wavelength, each of the different wavelengths can have a different water extinction coefficient. Furthermore, each laser source can have the same aperture or a different aperture. In some embodiments, each laser source can be configured for a different purpose, for example, one laser source can be configured to generate an aiming beam of a particular intensity, one laser source can be configured to generate a treatment beam of a particular intensity, and one or more laser sources can be configured to generate a light beam of a particular wavelength with a particular water extinction coefficient. In addition, each laser source can be configured to generate polarized laser light or unpolarized / depolarized light.

[0043] A polarizer can include optical components that perform the role of an optical filter. For example, a polarizer can be configured to allow a light beam of a particular polarization to pass and block a light beam of a different polarization. Thus, when light of any given polarization (or a light beam of mixed polarization states) is provided as input to a polarizer, the polarizer provides a well-defined single polarized light beam as output.

[0044] A beam splitter may include optical components used to split the incoming light into two separate beams at a specified ratio. Additionally, the beam splitter may be arranged to manipulate the light to be incident at a desired angle of incidence (AOI). Thus, in many embodiments, the beam splitter may be configured with two main parameters: split ratio and AOI. Split ratio includes the ratio of reflection to transmission (reflection / transmission (R / T) ratio) of the beam splitter. Thus, as used herein, when a split ratio is indicated for a beam splitter as 50:50, it means that the beam splitter splits the incoming light beam with a 50:50 R / T ratio. In other words, the beam splitter splits the incoming light beam by modifying the incoming light by reflecting 50 percent and transmitting the remaining 50 percent. Further, as an example, when an AOI is indicated for a beam splitter as 45 degrees, it means that the beam splitter ensures that the light beam will be incident at an angle of 45 degrees. Beam splitters can include, but are not limited to, polarizing beam splitters and non-polarizing beam splitters. Polarizing beam splitters can split incident light based on S and P polarization components, such as by reflecting the S polarization component of the light and transmitting the P polarization component of the light (or vice versa). In some embodiments, non-polarizing beam splitters can split an incident light beam based on a particular R / T ratio while maintaining the original polarization state of the incident light beam.

[0045] The beam combiner may include a partial reflector that combines two or more wavelengths of light, such as by using the principles of transmission and reflection described above. In many embodiments, the beam combiner may be a combination of beam splitters and mirrors that perform the function of combining two or more wavelengths of light.

[0046] A photodetector may include a device that detects and / or measures a characteristic of a light beam and encodes the detected and / or measured characteristic into an electrical signal. For example, a photodetector may detect a particular type of light beam (preconfigured) and convert the optical energy associated with the detected light beam into an electrical signal. In some embodiments, wavelength division multiplexing may include a technique for combining several optical carrier signals onto a single optical fiber using laser light of different wavelengths.

[0047] A collimator can include a device that narrows a light beam. To narrow a light beam, the collimator can be configured to make the direction of motion more aligned in a particular direction (e.g., parallel light rays) or to make the spatial cross section of the beam smaller. In many embodiments, a collimator can be used to change diverging light from a point source into a parallel beam.

[0048] A circulator can include a multi-port optical device configured to receive and emit light through multiple ports in a predetermined order. For example, a circulator can include a three (or four or five, etc.) port optical device designed such that light entering any one port exits the next port. In one such example, light entering a first port can exit a second port, light entering the second port can exit a third port, and light entering the third port can exit the first port. In many cases, circulators can be utilized to allow a light beam to travel in only one direction.

[0049] It should be noted that when listing specific parameters for the optical components described herein, such as a beam splitter having a 50:50 R / T ratio and 45 degrees, these parameters are presented for the purpose of a general understanding of the disclosed concepts and are not intended to be limiting. As a specific example, it is contemplated that various embodiments described herein may provide beam splitters having R / T ratios and / or AOIs different from those explicitly stated herein without departing from the scope of the present disclosure and claims. In one such example, an AOI of 40 degrees may be utilized. In another such example, an R / T ratio of 47:53 may be utilized.

[0050] The LETD system 106 is further associated with a processing unit 108 and / or a communication network (not shown). In some embodiments, the communication network can be a wired or wireless communication network. The processing unit 108 can be configured to receive measurements from the LETD system 106 and estimate the distance between the distal end 204 of the optical fiber 104 and the target 102 based on the measurements. In some embodiments, the processing unit 108 can be a stand-alone device having the processing capabilities required for distance estimation. For example, the processing unit 108 can include circuitry arranged to determine the distance based on electrical signals received from the LETD system 106. As another example, the processing unit 108 can include circuitry and a memory including instructions that, when executed by the processing unit 108, cause the circuitry to determine the distance based on electrical signals received from the LETD system 106. In yet some other embodiments, the processing unit 108 can be a computing device, such as a laptop, desktop, mobile phone, tablet phone, etc., configured to perform distance estimation using processing capabilities.

[0051] The processing unit 108 may be coupled with an indicator 110 for indicating an estimated distance between the distal end of the optical fiber 104 and the target 102. The indicator 110 may include, but is not limited to, a visual indicator that displays the estimated distance, an audio indicator that announces the estimated distance, or a tactile indicator that indicates the estimated distance through a vibration pattern. In various embodiments, the indicator may be presented through a graphical user interface and / or overlaid on a graphical representation such as a video feed. In some embodiments, a computing device configured as the processing unit 108 may be configured to perform the functionality of the indicator 110. In some other embodiments, the indicator 110 may be a standalone device configured to indicate an estimated distance between the distal end of the optical fiber 104 and the target 102.

[0052] Various illustrative configurations for estimating the distance between a fiber end and a target are described in detail below, however, the values ​​and parameters associated with the various optical components used in each of the configurations described below are purely illustrative and should not be construed as limiting the present disclosure.

[0053] 3 illustrates an example LETD system 300 that may be implemented as the LETD system 106 of the system 100. The LETD system 300 may be configured to estimate a distance between a fiber end and a target according to some embodiments of the present disclosure. As depicted, the LETD system 300 includes several laser sources. In particular, laser sources 302a and 302b are shown. In some embodiments, the laser sources 302a and 302b may be polarized laser sources. Additionally, the LETD system 300 includes a beam splitter 304, a power detector 306, and a polarizer 308. The laser sources 302a and 302b are arranged to generate light beams 320a and 320b, respectively. In some embodiments, laser source 302a is arranged to generate a light beam 320a having a first wavelength, whereas laser source 302b is arranged to generate a light beam 320b having a second wavelength different from the first wavelength, the first wavelength having a higher extinction coefficient (e.g., in water) than the extinction coefficient of the second wavelength.

[0054] As used herein, the light beam 320a generated by the laser source 302a may be referred to as high water absorption coefficient light (HI), and the light beam 320b generated by the laser source 302b may be referred to as low water absorption coefficient light (LO). Although the terms "high" and "low" are used, it is to be appreciated that these terms are intended to be interpreted relative to each other or alternatively relative to a threshold characteristic that represents water absorbance at a particular wavelength. For example, a high water absorption characteristic may be greater than or equal to 50%, whereas a low water absorption characteristic may be less than or equal to 50%.

[0055] In various embodiments, the ratio of high water absorption coefficient to low water absorption coefficient can be about 1:2. For example, laser light 225a can utilize a wavelength of about 1310 nm and have a water absorption coefficient of about 0.1651, while laser light 225b can utilize a wavelength of about 1340 nm and have a water absorption coefficient of about 0.333. A larger ratio between high and low absorption coefficients can result in lower susceptibility to system noise (e.g., electrical noise or opto-mechanical noise), but the resulting system may not be effective at distances greater than 3 mm. A smaller ratio between high and low absorption coefficients can result in higher susceptibility to system noise, but the resulting system may remain effective up to distances of up to 5 mm or 6 mm. In some examples, laser sources 302a and 302b can be polarization-maintaining (PM) pigtailed fiber lasers.

[0056] The laser sources 302a and 302b are associated with and in optical communication with the beam splitter 304. In other words, the light beams 320a and 320b generated by the laser sources 302a and 302b, respectively, are provided as inputs to the beam splitter 304, which is configured to split the incident light beams 320a and 320b in a ratio of about 50:50 (e.g., 47:53 or 49:51) such that the incident light beams 320a and 320b are aligned along a single optical path as the light beam 322. However, it is to be appreciated that any ratio between 99:1 and 1:99 may be utilized without departing from the scope of the present disclosure. Similarly, although an embodiment may describe an AOI of 45 degrees, it is to be appreciated that any AOI between 1 and 89 degrees, such as 43-47 degrees, 40 degrees, or 20 degrees, may be utilized without departing from the scope of the present disclosure.

[0057] Power detector 306 is associated with and in optical communication with beam splitter 304. Power detector 306 is arranged to measure the optical power in the optical signal (e.g., the portions of optical beams 320a and 320b that are transmitted to power detector 306) corresponding to each wavelength of light in optical beam 322. In some embodiments, the term "optical power" may refer to the energy transmitted per unit time by a given laser beam.

[0058] The beam splitter 304 is further associated with and in optical communication with a polarizer 308. The beam splitter 304 is further arranged to provide portions of the light beams 320a and 320b, labeled light beam 322, aligned along a single optical path as inputs to the polarizer 308. In some embodiments, the polarization state of the polarizer 308 can be preconfigured and arranged to output a polarized light beam 324. The LETD system 300 further includes a beam combiner 310 in optical communication with the polarizer 308. In such a manner, the polarized light beam 324 obtained as an output from the polarizer 308 is provided as an input to the beam combiner 310.

[0059] The beam combiner 310 can combine the polarized light beam 324 with the treatment beam 326 and the aiming beam 328. In some other embodiments, the treatment beam 326 can be generated by one or more laser sources (not shown) other than the laser sources 302a and 302b. By way of example, the treatment beam 326 can be generated by a solid-state laser or fiber laser, such as a Holmium (HO) laser or a Thulium Fiber Laser (TFL). However, the treatment beam 326 can be generated by lasers other than HO or TLF, such as neodymium and erbium. In some other embodiments, the treatment beam 326 and the aiming beam 328 can be generated by the laser sources 302a and / or 302b.

[0060] The beam combiner 310 can combine the polarized light beam 324 with the treatment beam 326 and the aiming beam 328 to form a combined light beam 330. The LETD system 300 further includes a beam splitter 312 and a port 314. The beam splitter 312 is arranged in optical communication with the beam combiner 310. The beam splitter 312 can receive the combined light beam 330 including the polarized light beam 324, the treatment beam 326, and the aiming beam 328. The beam splitter 312 can have a configuration of a 50:50 R / T ratio and a 45 degree AOI.

[0061] In such an arrangement, the beam splitter 312 may split the combined light beam 330 in a 50:50 ratio such that the polarized light beam 324, the treatment beam 326, and the aiming beam 328 are aligned along a single optical path. The beam splitter 312 is optically coupled (e.g., through port 314, etc.) to the optical fiber 104 such that a portion of the combined light beam 330 that is the output of the beam splitter 312 is transmitted through the optical fiber 104 (e.g., through port 314), which portion is designated as light beam 332. The light beam 332 is transmitted to the proximal end 202 of the optical fiber 104, then propagates longitudinally through the optical fiber 104, and is delivered from the distal end 204 of the optical fiber 104 to the target 102. By way of example, the target 102 may be tissue, stones, tumors, cysts, etc. to be treated, cauterized, destroyed, etc. within the subject's body.

[0062] When the light beam 332 is sent through the optical fiber 104 to the target 102, the target 102 may reflect some portion of the incident light beam 332 away from the optical fiber 104 and some portion of the light back towards the optical fiber 104, which may re-enter the optical fiber 104 at the distal end 204 of the optical fiber 104. The portion of the reflected light that re-enters the distal end may be referred to as the reflected light beam 334a. The reflected light beam 334a may travel "backwards" within the optical fiber 104 from the distal end 204 to the proximal end 202 of the optical fiber 104. When the reflected light beam 334a reaches the proximal end 202 of the optical fiber 104, it may pass through the beam splitter 312. The reflected light beam 334a may include numerous reflected lights, such as from the target 102, from the distal end 204 of the optical fiber 104, from the proximal end 202 of the optical fiber 104, and from the port 314. Thus, reflected light beam 334a is no longer polarized.

[0063] The LETD system 300 further includes a polarizing beam splitter 316, a photodetector 318a, and a photodetector 318b. The reflected light beam 334a enters the beam splitter 312 at a 45 degree angle and may be split in a 50:50 ratio (or other ratios detailed herein) such that the reflected light beam 334a is aligned along a single optical path as a reflected light beam 334b. The polarizing beam splitter 316 is arranged in optical communication with the beam splitter 312 and is further arranged to receive and polarize the reflected light beam 334b. In some embodiments, the polarizing beam splitter 316 may split the reflected light beam 334b ​​into a reflected P-polarized beam and a transmitted S-polarized beam. One of the photodetectors 318a or 318b can be configured to detect the P-polarized beam of the reflected light beam 334b, and the other of the photodetectors 318a or 318b can be configured to detect the S-polarized beam of the reflected light beam 334b. The photodetectors 318a and 318b can measure the intensity of the detected light beam of the reflected light beam 334b, respectively, and transmit it to the processing unit 108. In some embodiments, the processing unit 108 can estimate the distance between the distal end 204 of the optical fiber 104 and the target 102 based on the measured intensity. A method for estimating the distance between the distal end 204 of the optical fiber 104 and the target 102 based on the measured intensity is described in more detail below.

[0064] 4 illustrates an example LETD system 400 that may be implemented as the LETD system 106 of the system 100. The LETD system 400 may be configured to estimate the distance between a fiber end and a target according to some embodiments of the present disclosure. For convenience, where components of the LETD system 400 are the same as components of previously described LETD systems (e.g., LETD system 300, etc.), the same reference numbers are used.

[0065] LETD system 400 differs from LETD system 300 in two configuration aspects. One of the configuration aspects that differs between LETD system 400 and LETD system 300 is that beam splitter 304 is replaced with beam combiner 402. With beam splitter 304 replaced with beam combiner 402, power detector 306, which was associated with beam splitter 304 in LETD system 300, is arranged to be associated with beam splitter 312 in LETD system 400. The embodiments are not limited to this situation.

[0066] The LETD system 400 may include one or more polarized lasers, one or more beam splitters, a polarizer, one or more beam combiners, and one or more photodetectors. The one or more beam splitters may be polarizing beam splitters, non-polarizing beam splitters, or a combination of both polarizing and non-polarizing beam splitters. As shown in FIG. 4, the LETD system 400 includes a laser source 302a, a laser source 302b, a beam combiner 402, a polarizer 308, a beam combiner 310, a beam splitter 312, a power detector 306, a polarizing beam splitter 316, a photodetector 318a, and a photodetector 318b. In this configuration, as shown in FIG. 4, laser source 302a outputs a light beam 320a having a wavelength with a high water extinction coefficient (HI), and laser source 302b outputs a light beam 320b having a wavelength with a low water extinction coefficient (LO).

[0067] The incident light beams from the laser sources 302a and 302b are provided as inputs to the beam combiner 402, which is configured to combine the incident light beams 320a and 320b generated by the laser sources 302a and 302b into a light beam 322. Furthermore, the output of the beam combiner 402 (e.g., the light beam 322) can be provided as an input to the polarizer 308 to provide the polarized light beam 324 as an output. In some embodiments, the polarization of the polarizer 308 can be pre-configured. The polarized light beam 324 obtained as an output from the polarizer 308 can then be provided as an input to the beam combiner 310. As shown in FIG. 4, the beam combiner 310 can combine the polarized light beam 324 with the aiming beam 328 and the treatment beam 326 into a combined light beam 330.

[0068] The combined light beam 330, including the aiming beam 328 and the treatment beam 326 and the polarized light beam 324 from the laser sources 302a and 302b, may be passed through a beam splitter 312 having a 50:50 R / T ratio and a 45 degree AOI (or any other R / T ratio and AOI configuration outlined herein). The beam splitter 312 may split the combined light beam 330 in a 50:50 ratio such that the aiming beam 328, the treatment beam 326, and the polarized light beam 324 may be aligned along a single optical path.

[0069] A power detector 306 associated with the beam splitter 312 can measure the power of the optical signal (such as the polarized optical beam 324) corresponding to each wavelength. In various embodiments, the power detector 306 can detect the cumulative energy of the optical signal received at the beam splitter 312. In some embodiments, the term "optical power" may refer to the energy carried by a certain laser beam per unit time. The output of the beam splitter 312, the optical beam 332, is then transmitted to the optical fiber 104 (e.g., through port 314), as outlined above with respect to FIG. 3. In addition, the reflected optical beam 334a is received and processed, as outlined above with respect to FIG. 3.

[0070] FIG. 5 illustrates a LETD system 500 for estimating the distance between a fiber end and a target according to some embodiments of the present disclosure. The present disclosure can function with polarized and non-polarized laser sources. Thus, in the LETD system 500, the laser sources 502a and 502b used to provide the incident light beam (source light) are non-polarized laser sources. As an example, the laser sources 502a and 502b can be single mode (SM) fiber pigtailed lasers. When the laser sources 502a and 502b are non-polarized laser sources, there is no need for the polarizer 308, the polarizing beam splitter 316, the photodetector 318a for detecting the P-polarized light beam, and the photodetector 318b for detecting the S-polarized light beam described in the LETD system 300 and the LETD system 400 described above.

[0071] The LETD system 500 may include one or more unpolarized lasers, one or more beam splitters, a beam combiner, and a photodetector. The one or more beam splitters may be unpolarized beam splitters. As shown in FIG. 5, the LETD system 500 includes an unpolarized laser source 502a, an unpolarized laser source 502b, a beam splitter 304, a power detector 306, a beam combiner 310, a beam splitter 312, and a photodetector 512.

[0072] As with the previous configurations, in the LETD system 500, the unpolarized laser source 502a can have a wavelength with a high water extinction coefficient (HI), whereas the unpolarized laser source 502b can have a wavelength with a low water extinction coefficient (LO). Light beams 504a and 504b emitted from the laser sources 502a and 502b, respectively, are provided as inputs to a beam splitter 304 that is configured to split the incoming light beams in a 50:50 ratio such that the incoming light beams 504a and 504b are aligned along a single optical path as light beam 506.

[0073] A power detector 306 associated with the beam splitter 304 can measure the power of the optical signal (light beam 506) corresponding to each wavelength. Because the LETD system 500 is implemented in a non-polarized environment, polarization-based optical components such as polarizers and polarizing beam splitters are not required in this configuration. Thus, the output of the beam splitter 304, which are the incident light beams 504a and 504b aligned along a single optical path as the light beam 506, can be provided as input to the beam combiner 310. As shown in FIG. 5, the beam combiner 310 can combine the light beam 506 arriving from the beam splitter 304 with the aiming beam 328 and the treatment beam 326.

[0074] In some embodiments, the aiming beam 328 and the treatment beam 326 can be generated by one or more laser sources other than the laser sources 502a and 502b. In some other embodiments, the aiming beam 328 and the treatment beam 326 can be generated by the laser sources 502a and 502b. The combined light beam 508, including the aiming beam 328, the treatment beam 326, and the light beam 506, which is a non-polarized light beam, can be passed through a beam splitter 312 having a configuration of a ratio of 50:50 and 45 degrees (or any other R / T ratio and AOI outlined herein). The beam splitter 312 can split the combined light beam 508 in a 50:50 ratio such that the aiming beam 328, the treatment beam 326, and the light beam 506, which is a non-polarized light beam, are aligned along a single optical path. The output of beam splitter 312, light beam 510, is then transmitted to optical fiber 104 (eg, through port 314), while reflected light beam 514a is transmitted in the reverse direction as shown in FIG. 5 and described above.

[0075] Since the LETD system 500 is implemented in a non-polarized environment, the reflected light beam 334a passes only through the second beam splitter 312 in alignment with the optical path of the reflected light beam 514a, and no polarizing beam splitter is required as depicted in the LETD system 300 and the LETD system 400. The reflected light beam 514a is considered to be incident on the beam splitter 312 at a 45 degree angle and split in a 50:50 ratio. The reflected light beam 334b ​​emerging from the beam splitter 312 can be directly detected by a single detector. Thus, the LETD system 500 provides a photodetector 512.

[0076] The light detector 512 can measure the intensity of each of the detected light beams of the multiple reflected light beams 514b and transmit these intensities to the processing unit 108. In some embodiments, the processing unit 108 can estimate the distance between the distal end 204 of the optical fiber 104 and the target 102 based on the measured intensities. Methods for estimating the distance between the distal end of the optical fiber 104 and the target 102 based on the measured intensities are described in more detail below.

[0077] FIG. 6 illustrates a LETD system 600 for estimating the distance between a fiber end and a target according to some embodiments of the present disclosure. The LETD system 600 includes a third polarized laser source 302c introduced for the purpose of real-time calibration of the optical fiber condition. By way of example, the condition of the optical fiber 104 may include, but is not limited to, changes or degradation of either the distal or proximal end of the optical fiber 104, fiber bending effects on polarization scrambling, or any other degradations and changes occurring within the optical fiber 104. Changes in the condition of the optical fiber 104, especially its tip / end (e.g., input and output facets), can adversely affect the transmitted and reflected light beams, causing multiple reflections, energy losses, and inaccurate measurements. This can affect the accuracy of the distance estimation and further cause inaccurate positioning of the optical fiber 104 during the procedure.

[0078] The LETD system 600 may include one or more polarized lasers, one or more beam splitters, a polarizer, a beam combiner, and one or more photodetectors. The one or more beam splitters may be polarizing beam splitters, non-polarizing beam splitters, or a combination of both polarizing and non-polarizing beam splitters. As shown in FIG. 6, the LETD system 600 includes polarized laser source 302a, polarized laser source 302b, polarized laser source 302c, beam splitter 304, beam splitter 602, power detector 306, polarizer 308, beam combiner 310, beam splitter 312, beam splitter 604, photodetector 318a, and photodetector 318b. 6, light beams 320a and 320b from laser sources 302a and 302b are provided as inputs to beam splitter 304, which is configured to split light beams 320a and 320b in a 50:50 ratio such that light beams 320a and 320b are aligned along a single optical path to form light beam 322. Additionally, the output of beam splitter 304 (e.g., light beam 322), light beams 320a and 320b aligned along a single optical path, can be provided as inputs to beam splitter 602, which is also configured to split the incoming light beam in a 50:50 ratio to form polarized light beam 606 including light beams 320a, 320b, and 320c.

[0079] Beam splitter 602 is provided as an input with an incident light beam 320c (e.g., light for calibration purposes) from polarized laser source 302c along with the output from beam splitter 304 (e.g., light beam 322). A power detector 306 associated with beam splitter 602 can measure the power of the optical signal (light beam 606) corresponding to each wavelength that reaches beam splitter 602. Along with the output of beam splitter 304, beam splitter 602 receives an incident light beam from polarized laser source 302c.

[0080] In some embodiments, the polarized laser source 302c has a wavelength with a very high water extinction coefficient (e.g., substantially, completely, or nearly completely absorbed by water) compared to the wavelengths of light emitted by the laser sources 302a and 302b. By way of example, the wavelength of the polarized laser source 302c may be about 1435 nm and have a water extinction coefficient of about 31.55 (or about 100 times that of a "high" water absorption laser source). At a wavelength of 1435 nm, about 98-99% of the light is absorbed at a distance of 0.5 mm. In some embodiments, the calibration light source may have a wavelength from about 1420 to about 1440 (resulting in a water extinction coefficient of about 30). Alternatively or additionally, wavelengths with very high water extinction coefficients (e.g., 1870-2070 nm) may be utilized. However, wavelengths farther away from the HI and LO wavelengths (e.g., 1310 nm and 1340 nm, respectively) are likely to lead to more complex optical designs. For example, the detector may cover a range of about 1100 nm to 1600 nm, where a unique or additional detector may be required if the very high water extinction coefficient laser has a wavelength of 2000 nm. In some embodiments, the calibration laser may have a wavelength of about 1435 nm, about 2100 nm, or between about 1870 nm and about 2050 nm.

[0081] Based on the readings of the polarized laser source 302c (e.g., measured by the power detector 306), the processing unit 108 can define an optical baseline characteristic of the "quality" of the fiber tip at the distal end 204 of the optical fiber 104. More specifically, since the laser source 302c is significantly absorbed in water, the light from the laser source 302c is unlikely to reach the target tissue, and as a result, any light from the laser source 302c is unlikely to be reflected back into the optical fiber 104 as part of the reflected light beam 334a. Thus, the component of the reflected light beam 334a (light reflection 610) having the wavelength of light associated with the laser source 302c can be attributed primarily to the optical characteristics of the distal end 204 of the optical fiber 104. It is to be appreciated that the distal end 204 of the optical fiber 104 undergoes degradation during the laser procedure, for example, due to heat and cavitation. In many embodiments, a high intensity reading of the back light reflection 610 can indicate degradation of the optical fiber tip. In some embodiments, the processing unit 108 may indicate, such as via a user interface and / or an audible alarm, that the optical fiber 104 should be inspected or replaced at a certain threshold of intensity change from the baseline reading for a particular fiber (e.g., 10% to 50%, or greater than or equal to 25%, 50%, 75%, 90%, or between 10% and 100%, etc.). In addition, degradation of the optical fiber tip may cause stronger internal reflections of light from the polarized laser sources 302a and 302b from the distal end of the fiber. Because light is randomly depolarized in the fiber, whether the laser source is a polarized laser source or not may have only a small effect on the internal reflections. However, monitoring the reflection from the fiber distal end with a very high extinction coefficient laser (e.g., a 1435 nm laser) may be used to determine the change in distal end reflection (in percentage of initial reflection vs. real-time reflection of 1435). Additionally, changes in the distal tip reflections can be applied to the initial reflections from the distal tips for the LO laser (eg, 1310 nm laser) and the HI laser (eg, 1340 nm laser) to update the initial reflections.

[0082] Additionally, degradation of the fiber tip may change the ratio between P and S polarization states in the reflected light beam 334a or light reflection 610. Thus, generating baseline readings for a particular optical fiber 104 currently in use and monitoring these baselines on the fly may allow for more accurate distance estimations when and even as the fiber tip degrades until the degradation reaches a threshold level at which the optical fiber 104 must be replaced. Additionally, the output of the beam splitter 602 or light beam 606, including light beams 320a, 320b, and 320c aligned along a single optical path, may be provided as an input to a polarizer 308 to obtain a single polarized light beam 608 as an output. In some embodiments, the polarization of the polarizer 308 may be preconfigured.

[0083] The polarized light beam 608 obtained as an output from the polarizer 308 can be provided as an input to the beam combiner 310. As shown in FIG 6, the beam combiner 310 can combine the polarized light beam 608 with the aiming beam 328 and the treatment beam 326 to form a combined light beam 612. As detailed above, the aiming beam 328 and / or the treatment beam 326 can be generated by one or more laser sources other than or including the laser sources 302a, 302b, or 302c.

[0084] The combined light beam 612, including the aiming beam 328, the treatment beam 326, and the polarized light beam 608, may be passed to a beam splitter 312 having a configuration of a 50:50 ratio and a 45 degree AOI. The beam splitter 312 may split the combined light beam 612 in a 50:50 ratio such that the aiming beam 328, the treatment beam 326, and the polarized light beam 608 are aligned along a single optical path. The output of the beam splitter 312, a light beam 614, is then transmitted to the optical fiber 104 (e.g., through port 314).

[0085] FIG. 7 illustrates a LETD system 700 for estimating the distance between a fiber end and a target according to some embodiments of the present disclosure. Similar to the LETD system 500, the LETD system 700 is implemented in a non-polarized environment. Furthermore, the LETD system 700 is a "half fiber-based design" in which the two-input beam splitter found in previous configurations (e.g., the configuration of the LETD system 600) is replaced with a wavelength division multiplexer (WDM). The WDM power loss can be about 20%, whereas the beam splitter power loss can be about 50%, improving the efficiency of the LETD system 700 with the use of the WDM. Furthermore, the WDM can perfectly or nearly perfectly align each of the three laser sources to the optical path. However, the beam splitter and the beam combiner are somewhat less accurate in aligning each of the three laser sources to the optical path.

[0086] The LETD system 700 utilizes a third unpolarized laser source 502c in conjunction with the first unpolarized laser source 502a and the second unpolarized laser source 502b. The third unpolarized laser source 502c is introduced for the purpose of real-time calibration of the optical fiber condition as described above. It is to be appreciated that the calibration laser can be a polarized laser or an unpolarized laser without departing from the scope of the present disclosure. The LETD system 700 can include one or more unpolarized lasers, one or more beam splitters, a beam combiner, one or more photodetectors, a WDM, and a collimator. 7, the LETD system 700 includes an unpolarized laser source 502a, an unpolarized laser source 502b, an unpolarized laser source 502c, a laser source 702, a wavelength division multiplexer (WDM) 704, a beam splitter 706, a power detector 306, a collimator 708, a beam combiner 310, a beam splitter 312, and a photodetector 512. In the configuration of the LETD system 700, the unpolarized laser source 502a can emit light having a wavelength with a high water extinction coefficient (HI), and the unpolarized laser source 502b can emit light having a wavelength with a low water extinction coefficient (LO). Furthermore, the unpolarized laser source 502c can emit light having a very high water extinction coefficient (e.g., completely or nearly completely absorbed by water) compared to the wavelengths of the light emitted by the laser sources 502a and 502b. As an example, the wavelength of the unpolarized laser source 502c may be 1435 nm.

[0087] As mentioned above, in the configuration of LETD system 700, beam splitter 304 and beam splitter 602 shown in FIG. 6 are replaced by WDM 704. In some embodiments, to ensure proper use of unpolarized laser source 502c as a real-time calibrator, the incoming light beams arriving from each of unpolarized laser sources 502a, 502b, and 502c can be arranged to be incident at the same point and at the same angle on the proximal end of optical fiber 104. In many embodiments, it may be difficult or impossible to align the incoming light beams from each of unpolarized laser sources 502a, 502b, and 502c to be incident at the same point and at the same angle using a combiner / splitter. To ensure adherence to this condition of same point and same angle, the configuration shown in LETD system 700 utilizes WDM 704. The WDM 704 can be configured to ensure that all incoming light beams arriving from each of the unpolarized laser sources 502a, 502b, and 502c are incident at the same point and angle on the proximal end 202 of the optical fiber 104. Additionally, in various embodiments, the use of the WDM 704 can reduce power losses, such as when compared to some beam splitters that cause 50%-75% power losses.

[0088] The incident light beams and aiming beam 328 from the laser sources 502a, 502b, and 502c are provided as inputs to a WDM 704, which is configured to combine the incident light beams so that they travel identically. As further shown in FIG. 7, the output of the WDM 704 can be provided as input to a fiber-based beam splitter (e.g., a fourth beam splitter 706), which can be arranged to split the incident light beam with a high transmission-to-reflection ratio (e.g., 95:5 or 99:1). In some embodiments, the beam splitter 706 is a fiber-based beam splitter. A power detector 306 associated with the beam splitter 706 can measure the power of the optical signal (e.g., the optical beam 710) corresponding to each wavelength. Additionally, the output of beam splitter 706 (eg, light beam 710), the incident light aligned into a single optical path, may be provided as an input to collimator 708 to narrow and collimate light beam 710 into a parallel beam.

[0089] 7, the output of the collimator 708 (e.g., light beam 712) can be provided to the beam combiner 310, which combines the light beam 712 arriving from the collimator 708 with the aiming beam 328 and the treatment beam 326. In some embodiments, the aiming beam 328 can be introduced into the WDM 704. In many embodiments, the aiming beam 328 can be introduced into the beam combiner 310. Additionally, in some embodiments, the aiming beam 328 can be introduced into both the WDM 704 and the first beam combiner 310. In some embodiments, the aiming beam 328 and / or the treatment beam 326 can be generated by one or more laser sources other than or among the laser sources 502a, 502b, and 502c.

[0090] The combined light beam 508 including the aiming beam 328, the treatment beam 326, and the light beam 712 (e.g., light emitted from the laser sources 502a, 502b, and 502c and received from the collimator 708) may be passed to a beam splitter 312 having an R / T ratio of 50:50 and a 45 degree AOI configuration. The beam splitter 312 may split the combined light beam 508 in a 50:50 ratio such that the aiming beam 328, the treatment beam 326, and the combined light beam 508 of the unpolarized light beams from the laser sources 502a, 502b, and 502c may be aligned along a single optical path. The light beam 510 output from the beam splitter 312 is then transmitted to the optical fiber 104 (e.g., through port 314) as shown and described more fully above.

[0091] 8 illustrates a LETD system 800 for estimating the distance between a fiber end and a target according to some embodiments of the present disclosure. The LETD system 800 is implemented using a non-polarized detector, similar to the configurations of the LETD system 500 and the LETD system 700. However, the laser source can be a non-polarized or polarized laser source. In this example configuration, the LETD system 800 can include one or more non-polarized lasers (or polarized lasers), one or more beam splitters, a beam combiner, one or more photodetectors, a WDM, a circulator, and a collimator. 8, the LETD system 800 includes an unpolarized laser source 502a, an unpolarized laser source 502b, an unpolarized laser source 502c, a laser source 702, a wavelength division multiplexer (WDM) 704, a beam splitter 706, a power detector 306, a circulator 802, a photodetector 512, a collimator 708, and a beam combiner 310. In the configuration of the LETD system 800, the unpolarized laser source 502a can emit light having a wavelength with a high water extinction coefficient (HI), whereas the polarized laser source 502b can emit light having a wavelength with a low water extinction coefficient (LO). Furthermore, the unpolarized laser source 502c can have a wavelength with a very high water extinction coefficient that is substantially absorbed in water.

[0092] Similar to what has been described above, in LETD system 800, beam splitter 304 and beam splitter 602 shown in FIG. 6 are replaced with WDM 704 shown in FIG. 7 and FIG. 8. Additionally, in LETD system 800, beam splitter 312, which was arranged to send a light beam to port 314 in all previous illustrative configurations, is also eliminated. The beam splitter reduces the output power by 50% (or more), and reduces the output power by an additional 50% (or more) when a return signal is received. Thus, the elimination of beam splitter 312 in LETD system 800 can significantly enhance the output power and the reflected signal.

[0093] The incident light beams 504a, 504b, and 504c emitted from the laser sources 502a, 502b, and 502c, respectively, and the aiming beam 328 are provided as inputs to the WDM 704, which is configured to combine the incident light beams so that they travel identically. For example, the output of the WDM 704 can be provided as input to the beam splitter 706, which splits the incident light beams in a ratio of 95:5. As previously mentioned, other ratios such as 99:1 can be utilized without departing from the scope of the present disclosure. In some embodiments, the beam splitter 706 is a fiber-based beam splitter, which makes the configuration of the LETD system 800 an all-fiber-based design. A power detector 306 associated with the beam splitter 706 can measure the power of the optical signal (e.g., the optical beam 710) corresponding to each wavelength. Additionally, the output of beam splitter 706 (e.g., light beam 710), which is the incident light aligned along a single optical path, can be fed as an input to circulator 802. Circulator 802 is configured to ensure that all light beams travel in one direction. Additionally, circulator 802 feeds light beams 804 from ports other than the port where light beam 710 enters to collimator 708. Collimator 708 can focus these light beams into parallel light beam 804. Circulator 802 provides (1) lower power loss (beam splitter loss is ∼50% in each direction) and (2) a more flexible optical design (free space optics require straight lines whereas fiber-based designs can be folded as needed) when compared to beam splitters.

[0094] 8, the output of the collimator 708 (e.g., collimated light beam 804) can be fed into a beam combiner 310, which combines the light beam 804 arriving from the collimator 708 with the aiming beam 328 and the treatment beam 326 into a combined light beam 806. In some embodiments, the aiming beam 328 can be introduced either at the starting point (e.g., in the WDM 704), into the beam combiner 310, or into both the WDM 704 and the beam combiner 310. In some embodiments, the aiming beam 328 and / or the treatment beam 326 can be generated by one or more laser sources other than the laser sources shown in this figure or by the laser sources shown in this figure. 8, a combined light beam 806 including the aiming beam 328, the treatment beam 326, and the light beams 804 (e.g., light beams 504a, 504b, and 504c) received from the beam combiner 310 can be transmitted (e.g., through port 314) to the optical fiber 104. The combined light beam 806 can be transmitted to the proximal end 202 of the optical fiber 104, then propagates longitudinally through the optical fiber 104, and delivered to the target 102 from the distal end 204 of the optical fiber 104.

[0095] As outlined above, when the light beam 806 is transmitted to the target 102 through the distal end 204 of the optical fiber 104, the target 102 may reflect some of this light away from the optical fiber 104 and some of the light back towards the optical fiber 104, where the portion of the light reflected back towards the optical fiber 104 may re-enter the optical fiber 104 at the distal end 204. As outlined above, the portion of the reflected light that re-enters the distal end 204 is referred to as the reflected light beam 334a. The reflected light beam 334a may travel "backwards" through the optical fiber 104 from the distal end 204 to the proximal end 202. When the reflected light beam 334a reaches the proximal end 202 of the optical fiber 104, it may pass through the beam combiner 310 and the collimator 708 and pass through the circulator 802 where it is sent to the photodetector 512 for measurement as described above with respect to FIG. 7.

[0096] 9 illustrates an LETD system 900 that can be implemented in a non-polarized environment similar to some of the previous configurations. In some embodiments, the LETD system 900 can include an optical design utilizing a single beam splitter. In the configuration of the LETD system 900, the WDM 704 can replace or perform the function or operation of multiple beam splitters (e.g., those utilized in the LETD system 300, the LETD system 400, 500, and / or the LETD system 600, etc.). The WDM 704 can receive the light beams 504a, 504b, and 504c from the non-polarized laser sources 502a, 502b, and 502c, respectively.

[0097] The LETD system 900 may include one or more unpolarized lasers (or polarized lasers), a beam splitter, a beam combiner, one or more photodetectors, a WDM, and a collimator. As shown in Fig. 9, the LETD system 900 includes an unpolarized laser source 502a, an unpolarized laser source 502b, an unpolarized laser source 502c, a laser source 702, a wavelength division multiplexer (WDM) 704, a beam splitter 902, a power detector 306, a photodetector 512, and a beam combiner 310. In the LETD system 900, as in the previous configuration, the unpolarized light beam 504a may have a wavelength with a higher water absorption coefficient (HI) compared to the unpolarized light beam 504b, which itself may have a wavelength with a lower water absorption coefficient (LO). Additionally, the unpolarized light beam 504c may have a wavelength that has a very high water extinction coefficient, as explained in detail above.

[0098] As explained above, the processing unit 108 can define an optical baseline characteristic of the quality of the distal end 204 (e.g., output facet, etc.) of the optical fiber 104 based on the readings associated with the reflection of the light generated by the unpolarized laser source 502c. More specifically, since the light from the laser source 502c is significantly absorbed in water, only a small amount of this light will be reflected back into the optical fiber 104 as part of the reflected light beam 334a. Thus, the readings associated with the optical reflection 610 can be attributed primarily to the optical characteristics of the distal end 204 of the optical fiber 104, which undergo degradation during the laser procedure, for example, due to heat and cavitation, as explained. Thus, a high intensity reading of the optical reflection 610 can indicate degradation of the optical fiber tip.

[0099] In some embodiments, the processing unit 108 may indicate, such as via a user interface and / or an audible alarm, that the optical fiber 104 should be inspected or replaced at a certain threshold of intensity change (e.g., greater than or equal to 10% to 50%, 25%, 50%, 75%, 90%, or between 10% and 100%) from a baseline reading for a particular fiber 103. Additionally, degradation of the optical fiber tip may cause stronger internal reflections from the distal end 204 of the optical fiber 104 of light associated with the laser sources 502a and 502b, which are unpolarized laser sources. Furthermore, degradation of the fiber tip may change the ratio between P and S polarization states in the reflected light beams 334a or 334b. Thus, generating baseline readings for a particular optical fiber currently in use and monitoring these baselines on the fly may allow for more accurate distance estimations when and even while the tip of the optical fiber degrades until the degradation reaches a point where the optical fiber must be replaced. Thus, more dynamic control of parameters associated with a treatment or procedure may be provided.

[0100] The LETD system 900, like some previous configurations of LETD systems, utilizes a WDM 704 to ensure that all incoming light beams arriving from each of the unpolarized lasers 502a, 502b, and 502c are incident at the same point and angle on the proximal end 202 of the optical fiber 104. Additionally, in various embodiments, the use of a WDM 704 can reduce power losses, such as when compared to some configurations that utilize beam splitters.

[0101] The light beams 504a, 504b, and 504c emitted from the drawing laser source and the aiming beam 328 are provided as inputs to the WDM 704, which is configured to combine the incoming light beams such that they travel identically. Additionally, the output of the WDM 704 can be provided as inputs to the beam splitter 902, which can split the incoming light beams in a 50:50 ratio. In some embodiments, the beam splitter 902 can be a free-space (e.g., glass) based beam splitter. In some other embodiments, the beam splitter 902 can be a fiber-based beam splitter. In many embodiments, the power detector 306 associated with the beam splitter 902 can measure the power of the optical signal (e.g., the light beam 710) corresponding to each wavelength.

[0102] The output of the beam splitter 902, the incident light aligned into a single optical path, can be provided as an input to the beam combiner 310. As shown in FIG. 9, the beam combiner 310 can combine the light beam 710 arriving from the beam splitter 902 with the aiming beam 328 and the treatment beam 326. In various embodiments, the aiming beam 328 can be introduced into the WDM 704, into the beam combiner 310, or into both the WDM 704 and the beam combiner 310. In some embodiments, the aiming beam 328 and / or the treatment beam 326 can be generated by one or more laser sources other than or including the laser sources 502a, 502b, or 502c. A combined light beam 806 including the aiming beam 328, the treatment beam 326, and the light beam 710 received from the beam combiner 310 may be transmitted to the optical fiber 104 (eg, through the port 314).

[0103] As can be seen in this figure, the LETD system 900 eliminates the use of multiple beam splitters. Furthermore, because the LETD system 900 utilizes a single beam splitter, it can be significantly less sensitive to treatment fiber movement and fiber bend radius, resulting in a more robust configuration. Furthermore, because the LETD system 900 has fewer optical components, such as beam splitters, beam combiners, and detectors, it can be smaller, simpler, and less expensive than other configurations.

[0104] In some embodiments of the aforementioned illustrative configurations, the proximal end 202 of the optical fiber 104 may include a Sub-Miniature Version A (SMA) connector that may be polished or cut at an 8 degree angle as shown in FIG. 10. By cutting at an angle of 8 degrees as shown in this figure, a re-routing of the reflected light beam from the proximal end 202 of the optical fiber 104 (unwanted reflections caused by the proximal end 202) may be achieved, thereby reducing a significant amount of noise and increasing the dynamic range. In some embodiments, the optical signal (e.g., reflected light beam 334a) incident on the photodetector may contain one or more of: (a) reflections from a port lens, (b) reflections from a blast shield, (c) reflections from the proximal end 202 of the optical fiber 104, and / or (d) reflections from the distal end 204 of the optical fiber 104.

[0105] The AR coating at the proximal end 202 of the optical fiber 104 can reduce reflections from the proximal end 202 of the optical fiber 104 (e.g., from 3.5% to about 0.5%). However, the tapered narrower proximal end 202 of the optical fiber 104 helps reduce unwanted reflections and improves the dynamic range of the signal reflected from the target 102. In some other embodiments, the SMA connector can be polished or cut at an angle of, for example, 4 degrees as shown in FIG. 11, instead of 8 degrees. In various embodiments, signal robustness can be improved by cutting the SMA connector at a 4 degree angle instead of an 8 degree (or higher) angle, etc. In some embodiments, a smaller cut angle of the SMA connector can provide higher signal robustness of the optical fiber 104. In various embodiments, angles from about 2 degrees to about 8 degrees can be utilized. In general, smaller angles are more difficult to implement in an optical system. In other words, it is difficult to capture the reflected signal from the main signal. However, the light does not end up entering at a larger angle (e.g., more than 10 degrees).

[0106] 12 illustrates a flow diagram showing a method 1200 of estimating a distance between a fiber end and a target according to some embodiments of the present disclosure. The method 1200 is described with reference to the various configurations of system 100 and LETD system 106 described above (e.g., LETD system 300, LETD system 400, LETD system 500, LETD system 600, LETD system 700, LETD system 800, LETD system 900, etc.). However, it is to be appreciated that the method 1200 could be implemented with LETDs different from those described herein. The embodiments are not limited in this context.

[0107] At block 1202, the method 1200 includes illuminating a target with laser light of multiple different wavelengths. For example, the LETD system 106 can utilize multiple laser light sources (e.g., laser sources 302a and 302b, laser sources 502a, 502b, and / or 502c, etc.) to illuminate the target 102 with laser light of multiple different wavelengths through the optical fiber 104. In some embodiments, the laser light of multiple different wavelengths can be delivered to the optical fiber 104 using one of the configurations discussed above to illuminate the target 102. In various embodiments, the present disclosure can use light having two different wavelengths (e.g., light beams 320a and 320b, light beams 504a, 504b, and / or 504c, etc.), each having a different water extinction coefficient to ensure robustness against different types of targets 102, target compositions, target colors, target surfaces, etc.

[0108] In some embodiments, the two (or more) wavelengths can be selected such that one has a low water extinction coefficient (LO) and another has a high water extinction coefficient (HI). By way of example, the two wavelengths can be 1310 nm and 1340 nm. However, this example should not be construed as limiting, as different wavelengths with various water extinction coefficients can be used. For example, 1260-1320 nm can be utilized for LO, and 1330-1380 nm can be utilized for HI. More generally, any combination of pairs having a 2:1 (or greater) ratio of wavelength to water extinction coefficient can be utilized. In some embodiments, one or more of the following pairs can be utilized for the LO and HI lasers: 1310 nm and 1340 nm lasers, 1260 nm and 1340 nm lasers, 1260 nm and 1310 nm lasers, and 1310 nm and 1550 nm lasers. As outlined above, in some embodiments, two laser sources (e.g., 201a and 201b or 201a and 201b) may be used to emit light at two different wavelengths. In some embodiments, the laser source may be a polarized laser source, an unpolarized laser source, or a combination of polarized and unpolarized laser sources. As an example, to measure the distance between the distal end 204 of the optical fiber 104 and the target 102, a laser, such as but not limited to a low power infrared (IR) laser, may be used to illuminate the target 102 through the optical fiber 104. In other embodiments, lasers other than IR lasers may be utilized. However, IR lasers may be utilized due to the lack of visible light that may disturb the user.

[0109] At block 1204, the method 1200 includes receiving a reflected light beam from the target through the optical fiber. For example, the LETD system 106 can receive the reflected light beam 334a or the reflected light beam 514a from the target 102 through the optical fiber 104. In some embodiments, the reflected light beam 334a or the reflected light beam 514a may include a mixture of reflections from the proximal end 202 of the optical fiber 104, reflections from the distal end 204 of the optical fiber 104, reflections from the port 314, reflections from a blast shield (not shown), and other similar reflections. In various embodiments, the LETD system 106 can be configured to identify a reflected light beam suitable for measuring intensity.

[0110] At block 1206, the method 1200 includes measuring an intensity of the reflected light beam by detecting the reflected light beam with one or more photodetectors and transmitting an indication (e.g., an electrical signal, etc.) of the intensity of the reflected light beam measured by the one or more photodetectors to a processing unit. For example, the LETD system 106 can measure the intensity of the reflected light beam 334a or the reflected light beam 514a, also referred to herein as a return signal, by detecting the return signal with one or more photodetectors provided within the LETD system 106. In some embodiments, two different wavelengths are used to illuminate the target 102, so the measured intensity is for two different wavelengths. Thus, two measured intensities corresponding to two different wavelengths of the laser source (e.g., laser sources 302a and 302b, etc.) can be transmitted to a processing unit 108 associated with the LETD system 106. In various embodiments, three or more different wavelengths can be utilized, measured, and / or transmitted.

[0111] At block 1208, the method 1200 includes receiving, by a processing unit, an indication of the intensity of the reflected light beam as measured by the one or more photodetectors. For example, the processing unit 108 may receive an electrical signal from the LETD system 106, including an indication of the measured intensity of the reflected light beam 334a.

[0112] At block 1210, the method 1200 includes estimating, by a processing unit, a distance between the distal end of the optical fiber and the target based on the intensity of the reflected light beam measured by the one or more photodetectors. For example, the processing unit 108 may estimate the distance between the distal end 204 of the optical fiber 104 and the target 102 based on the measured intensity of the return signal. In some embodiments, the processing unit 108 may substitute the measured intensity into Equation 1 as shown below: Equation 1: Return signal strength =

number

[0113] In the above Equation 1, "R" refers to the target reflection coefficient, which is affected by the target composition, target color / dye, target angle, target surface, etc., "λ" refers to the water absorption coefficient at a particular wavelength, and "X" refers to the distance between the distal end 204 of the optical fiber 104 and the target 102.

[0114] In the above Equation 1, "X" and "R" are unknown parameters that need to be determined by the processing unit 108. Therefore, to determine the values ​​of "X" and "R", the processing unit 108 substitutes the two measured intensity values ​​into the above Equation 1, thereby obtaining two equations with substitute values ​​of the measured intensity and the water extinction coefficient of the corresponding wavelength. For example, the two equations with substitute values ​​may be as shown below: Equation 1.1: I (HI) =

number

number

[0115] The processing unit 108 can further simplify the above substituted equations 1.1 and 1.2 to the following equation, calculate the ratio of the intensity values ​​obtained for the return signals of two different wavelengths using equation 2.1, and determine the distance value using the natural logarithm shown in equation 2.2:

number

number

[0116] Thus, the processing unit 108 can estimate the distance X between the distal end 204 of the optical fiber 104 and the target 102 by simplifying equations 1.1 and 1.2 as shown above. In equation 2.2 above, "ln" refers to the natural logarithm. In some embodiments, the distance X can be measured in millimeters. In some embodiments, X is the same distance for both wavelengths, and R (target reflection) is approximately the same for both wavelengths when the selected wavelengths are close to each other on the "nm scale". In some embodiments, these wavelengths can be considered close to each other on the "nm scale" when they are within a range of 250 nm (e.g., 1310 nm and 1340 nm or 1310 nm and 1550 nm). However, in many embodiments, the wavelengths with closer R values ​​can be selected. Thus, 1310 nm and 1340 nm can be selected in preference to 1310 nm and 1550 nm. In some examples of the present disclosure, two laser sources (such as laser sources 302a and 302b) may be arranged to emit light having wavelengths that are within 100 nm of each other.

[0117] The condition of the optical fiber 104 may be affected due to factors such as changes or degradation of the distal end 204 and / or proximal end 202 of the optical fiber 104, fiber bending effects on polarization scrambling, or any other degradations and changes occurring within the optical fiber 104. Changes in the optical condition of the optical fiber 104, particularly its tip / end, may adversely affect one or more of the quality of the illumination beam, the intensity of the internally reflected light beam, the amount of light reflected back from the target into the fiber, the amount of energy reaching the target, and the accuracy of the measurements. These adverse effects may affect the accuracy of the distance estimation, potentially resulting in inaccuracies in the positioning of the optical fiber 104 during a procedure based on the distance estimation, as well as inaccuracies in the energy calculations based on the distance estimation, as described in U.S. Provisional Patent Application No. 63 / 118,117, which is incorporated herein by reference.

[0118] Internal reflections from surfaces associated with the fiber (e.g., the fiber proximal end or the fiber distal end) or from surfaces associated with other optical elements optically connected to the fiber (e.g., lenses or shields) can generate parasitic and undesirable reflections. Furthermore, these internal reflections can change over time due to degradation of the fiber or other elements. Fiber degradation can also change the quality of the laser beam projected toward the target and / or the intensity of light reflected back from the target tissue, e.g., the reflected light beams 334a and 334b ​​that enter and pass through the optical fiber.

[0119] Thus, in some embodiments, at block 1210, the method 1200 can measure an initial internal reflection before treatment begins to maintain accurate distance measurements even during fiber degradation and changes in internal reflection. In many such embodiments, the initial internal reflection value (or a baseline value) can be recorded and utilized to monitor changes over time. For example, the processing unit 108 can include circuitry (e.g., a register, memory, etc.) for storing a representation of the initial internal reflection value. In some embodiments, this processing can be performed for one or more optical fibers 104 used in the laser system. For example, this processing can be performed for each optical fiber 104 used in the laser system. Various embodiments described herein can monitor changes from the initial internal reflection value (e.g., stored in circuitry such as the processing unit 108) as provided herein to dynamically calibrate distance measurements.

[0120] In some embodiments, the processing unit 108 is configured to read (e.g., from a register or memory, etc.) a baseline value of such parasitic (e.g., undesired) reflections using a system pre-calibration process. In some embodiments, the system pre-calibration process can include setting up the treatment fiber in water without a target. In this context, "no target" can be interpreted to mean that the nearest target (e.g., a stone or tumor, etc.) can be positioned far enough away from the tip of the fiber such that no or substantially no light reflects from the target and enters the optical fiber 104 as the signal reflected light beam 334a. Such a distance can be, for example, 10 mm or more from the distal end 204 of the optical fiber 104 for an IR light source (e.g., 1310 nm light source and 1340 nm light source). However, lengths longer than 10 mm can be used when visible light (e.g., 400 nm to 700 nm) is used. Under these conditions, the system can then activate the laser (e.g., laser sources 302a and 302b, etc.) and measure the reflected signal, reflected light beam 334a, as described above. Because the reflected light beam 334a is very weak under these conditions (e.g., laser operation in the presence of water but without a target), the signal that reaches the photodetector is primarily related to internal reflections associated with the optical fiber 104 (e.g., from port 314, the proximal end 202, or the distal end 204, etc.).

[0121] The internally reflected (IR) light beam in such a scenario can be detected using a photodetector, and the measured intensity values ​​can be processed by the processing unit 108 as IR (HI) and IR (LO) (e.g., in a register or memory circuit). (HI) may be the internal reflection intensity of incident light with a high water absorption coefficient when there is no target near the tip (e.g., distal end 204) of the optical fiber 104, whereas IR (LO)may be the internal reflection intensity of the incident light having a lower water absorption coefficient when there is no target near the optical fiber 104 (e.g., the distal end 204). Then, during a treatment or procedure, when the laser is activated while the distal end 204 of the optical fiber 104 is positioned at a close distance to the target 102, the reflected light beam 334a is reflected back through the optical fiber 104 and may be detected using a photodetector as described herein.

[0122] In addition to calculating the measured intensity values ​​as described above, the processing unit 108 may also calculate, in block 1210, measured intensity values ​​I, which may be indicative of the intensity of the return signal from the target 102 (e.g., tissue, stones, etc.) corresponding to wavelengths having a higher water extinction coefficient (HI). (HI) The measured intensity value, which may be stored (e.g., in a register or memory circuit) as I and may be an indication of the intensity of the return signal from the target 102 (e.g., tissue, stone, etc.) corresponding to the wavelength having the lower water extinction coefficient (LO), (LO) However, to estimate the value of the parasitic (or unwanted) reflections from the readings of the actual reflected light beam 334a, the processing unit 108 calculates the actual return signal I as shown in Equations 3.1 and 3.2 below, respectively: (HI) Reading from IR (HI) and / or reduce the actual return signal reading I (LO) From IR (LO) Subtract and / or reduce. Equation 3.1: I' (HI) =I (HI) -IR (HI) Equation 3.2: I' (LO) =I (LO) -IR (LO)

[0123] In the above formula 3.1, I' (HI) refers to the new calculated intensity of the return signal (without parasitic (or unwanted) reflections) corresponding to the wavelength with the higher water extinction coefficient (HI), and I (HI)refers to the measured intensity of the return signal (with parasitic (or unwanted) reflections) corresponding to wavelengths with a higher water extinction coefficient (HI), and IR (HI) refers to the measured intensity of the internal reflection of incident light with a higher water extinction coefficient (measured "no target").

[0124] Similarly, in the above formula 3.2, I' (LO) refers to the new calculated intensity of the return signal (without parasitic (or unwanted) reflections) corresponding to the wavelength with the lower water extinction coefficient (LO), and I (LO) refers to the measured intensity of the return signal (with parasitic (or unwanted) reflections) corresponding to the wavelength with the lower water extinction coefficient (LO), and IR (LO) refers to the measured intensity of the internal reflection of the incident light (measured "without target") that has the lower water extinction coefficient.

[0125] Therefore, the processing unit 107 calculates a new intensity estimate I' (HI) and I' (LO) Using these new "calibration" values ​​I' (HI) and I' (LO) The distance between the distal end 113 of the optical fiber 103 and the target 101 can be determined by substituting into equation 2.2 as shown below:

number

[0126] In some embodiments, the above formula for "X" may be represented as shown below:

number

[0127] As mentioned above, the internal reflections may not be constant over time and may change due to some changes in the system's internal optical parameters, such as the optical quality of the distal end 204 of the optical fiber 104 (as opposed to changes due to the dynamics of the treatment environment external to the system). Due to one or more of the power level of the treatment beam 326, cavitation effects occurring at the distal end 204 (or tip) of the optical fiber 104, and the liquid environment in which the fiber is placed during treatment, the optical fiber undergoes different amounts of degradation, primarily at the distal end 204 (or tip). Thus, in some embodiments, a "real-time" or "dynamic" calibration may be performed by monitoring the reflected light beam 334a repeatedly during treatment and dynamically accounting for or adjusting for such changes in internal reflections. For example, as shown in the configurations using a calibration laser (e.g., laser source 302c, etc.) described herein, performing such a real-time calibration may be utilized to facilitate more accurate distance estimation that accounts for such degradation of the optical fiber.

[0128] As described with respect to the above configuration, the calibration laser beam (e.g., laser beam 320c) has a wavelength with a very high water extinction coefficient. By way of example, the wavelength of the polarized laser source 302c or the unpolarized laser source 502c may be 1435 nm. Since the laser beams generated by these "calibration" laser sources are significantly absorbed by the liquid environment as described above, any reflected light beams 334a associated with these laser beams are unlikely to return into the fiber. Thus, while the calibration laser source is in operation, the reflected light beams 334a having the wavelength of the calibration laser source are associated with (or exhibit) mainly internal reflections.

[0129] In some embodiments, the processing unit 108 may be configured to read and store one or more baseline values ​​for the internal reflections of the system 100 associated with the laser source 302c (and the like) at block 1210 before treatment begins. These one or more baseline values ​​may represent the “quality” of the optical fiber 104 (e.g., the optical quality of the distal end 204) before treatment begins and may be stored by the processing unit 108 (e.g., in a register or memory circuit, and the like). Additionally, the processing unit 108 may be configured to continue to measure in “real time” (e.g., periodically, repeatedly, and the like) the internal reflections of the light emitted by the calibration laser source (e.g., the laser source 302c, and the like) to identify deviations from these baseline values ​​during treatment. Monitoring these deviations provides an indication of degradation of the optical quality of the optical fiber 104, which may be used to correct any measured back reflection intensity associated with the reflected light beam 334a. In many embodiments, based on the readings of the internal reflections of the light emitted by the calibration laser sources, the processing unit 108 can modify the calibration parameters for the primary laser sources (eg, laser sources 302a and 302b).

[0130] In some embodiments, the method 1200 may include a block for a calibration process. For example, the processing unit 108 may read and store one or more internal reflection values ​​associated with light emitted by the calibration laser source when the system 100 is activated in water. Because the calibration laser source is significantly absorbed in water, the calibration laser source may be significantly less sensitive to the distance to the target 102 during the calibration read of the calibration laser source compared to measurements of reflection signals associated with light emitted by other laser sources. This may allow the calibration laser measurement to continue even when the target may approach the tip of the fiber during the procedure, as described in more detail below.

[0131] The target 102 can then be illuminated using one of the illustrative configurations with an uncalibrated laser source. In such a scenario, a photodetector can be used to detect the reflected light beam 334a and the reflected light beam 334b, and the processing unit 108 can calculate the measured intensity values ​​as I (HI) , I (LO) Additional measurements associated with the internal reflection of the calibrated laser as IR (CAL) It can be stored together with I (HI) may be the intensity of back reflection from a target of incident light with a higher water absorption coefficient, and I (LO) can be the intensity of the back reflection from the target of the incident light with a low water absorption coefficient, IR (CAL) may be the intensity of the internal reflection of the incident light from the calibration laser source.

[0132] In some embodiments, the incident light from the calibration laser source is significantly absorbed by water, so that the presence or absence of the target 102 is not reflected IR (CAL) As a result, IR (CAL) The change in value may be the result of a change in degradation of the optical fiber 104, particularly its tip (e.g., distal end 204, etc.). (CAL) Based on the relative change in value, the processing unit 108 calculates the current measured IR (HI) and IR (LO) or I currently being measured (LO) and I (HI) can be adjusted.

[0133] Thereafter, during treatment (e.g., when the laser is activated to treat the target 102), when the target 102 is present (e.g., when the target 102 is close enough to generate a reflected light beam 334a, such as when the target 102 is at a distance less than or equal to 10 mm from the distal end 204 of the optical fiber 104), the reflected light beam 334a for the laser source 302a or 302b and the laser source 502a or 502b and the light reflection 610 from the calibration laser source 302c or 502c can be detected using a photodetector. The processing unit 108, in block 1210, calculates the measured intensity value as I, which can represent the intensity of a return signal corresponding to light having a wavelength with a higher water extinction coefficient (HI). (HI) The measured intensity value can be stored as I and represent the intensity of the return signal corresponding to light having a wavelength with a lower water extinction coefficient (LO). (LO) and may represent the intensity of the back internal reflection signal corresponding to light having a wavelength with a higher water extinction coefficient (e.g., light emitted by the calibration laser source 302c or 502c). (CAL) Further, to determine the calibration coefficients, the processing unit 108 may store the IR from the pre-processing calibration process as shown in Equation 4 below. (CAL-PRE) IR from the calibration process performed during the treatment (CAL-DUR) can be divided by Equation 4: Calibration Factor (CF) =

number

[0134] When the internal reflection of the calibration laser source before treatment and the internal reflection of the calibration laser source during treatment are the same, there is no change in the optical fiber 104, and the calibration factor can be "1". Furthermore, the processing unit 108 can use this calibration factor to modify the parameters associated with the main laser sources 302a and 302b or the laser sources 502a and 502b based on the calibration factor, as shown in Equations 5.1 and 5.2 below. Equation 5.1: I” (HI) =I (HI) -IR(HI) ×CF Equation 5.2: I” (LO) =I (LO) -IR (LO) ×CF

[0135] In the above formula 5.1, I” (HI) refers to the new calibrated intensity of the back reflected signal from the target 102 corresponding to light having a wavelength with a higher water extinction coefficient (HI), and I (HI) refers to the measured intensity of the back reflected signal from the target 102 corresponding to light having a wavelength with a higher water extinction coefficient (HI), and IR (HI) refers to the measured intensity of the internal reflection of incident laser light having a wavelength with a higher water extinction coefficient (measured "without target"), and C refers to the calibration factor determined using Equation 4.

[0136] In the above formula 5.2, I” (LO) refers to the new calibrated intensity of the back reflected signal from the target corresponding to light having a wavelength with a lower water extinction coefficient (LO), and I (LO) refers to the measured intensity of the back reflected signal from the target corresponding to light having a wavelength with a lower water extinction coefficient (LO), and IR (LO) refers to the measured intensity of the internal reflection of incident laser light having a wavelength with a lower water extinction coefficient (measured "without target"), and CF refers to the calibration factor determined using Equation 4.

[0137] Therefore, the new calibrated intensity value I” (HI) And I” (LO) Using this, the processing unit 108 calculates a new calibration value I" in block 1210. (HI) And I” (LO) The distance between the distal end 204 of the optical fiber 104 and the target 102 can be determined by substituting into Equation 2.2 as shown below:

number

[0138] Thus, in this manner, system pre- and real-time calibrations can be performed and utilized to update calibration coefficients in real-time (e.g., via the processing unit 108) to dynamically account for changes (e.g., degradation, etc.) in the optical fiber 104 during operation. In some embodiments, pre- and real-time calibrations can be performed to ensure accuracy of the estimated distance between the distal end 204 of the optical fiber 104 and the target 102 as the optical fiber 104 undergoes degradation.

[0139] At block 1212, the method 1200 includes the processing unit 108 indicating, via an indicator, the distance estimated (e.g., at block 1210) between the distal end 204 of the optical fiber 104 and the target 102. For example, the processing unit 108 causes an indicator 110 associated with the processing unit 108 to indicate the estimated distance between the distal end 204 of the optical fiber 104 and the target 102. As a particular example, the indicator 110 may include one or more of a visual indicator, an auditory indicator, and a tactile indicator. Thus, at block 1210, the processing unit 108 may send a control signal to the indicator 110 to cause the indicator 110 to indicate (e.g., display, audibly communicate, tactilely communicate, etc.) an indication of the estimated distance.

[0140] In some embodiments, based on an estimated distance between the distal end 204 of the optical fiber 104 and the target 102, one or more of the position of the optical fiber 104, the orientation of the optical fiber 104, and the characteristics of the treatment beam, etc., can be varied in real time to accurately and efficiently affect the treatment beam on the target 102, such as through more precise targeting.

[0141] 13 illustrates a flow diagram showing a method 1300 for estimating a distance between a fiber end and a target according to some embodiments of the present disclosure. The method 1300 is described with reference to the various configurations of the system 100 and LETD system 106 described above. However, it is to be appreciated that the method 1300 could be implemented with LETDs different from those described herein. The embodiments are not limited in this context.

[0142] At block 1302, the method 1300 includes determining a first intensity value based on a first reflected laser light corresponding to a first wavelength of laser light emitted from the distal end 204 of the optical fiber 104, where the first reflected laser light is reflected by the target 102 and incident on the distal end 204 of the optical fiber 104. For example, the processing unit 108 may determine the first intensity value based on the reflected light beam 334a corresponding to light having a wavelength with a high water extinction coefficient. In some embodiments, the laser light corresponding to a wavelength with a high water extinction coefficient may be generated by the laser source 302a or 502a discussed above.

[0143] At block 1304, the method 1300 includes determining a second intensity value based on a second reflected laser light corresponding to the laser light of a second wavelength emitted from the distal end 204 of the optical fiber 104, where the second reflected laser light is reflected by the target 102 and incident on the distal end 204 of the optical fiber 104. For example, the processing unit 108 may determine the second intensity value at block 1304 based on the reflected light beam 334a corresponding to light having a wavelength having a low water extinction coefficient. In some embodiments, the laser light corresponding to a wavelength having a low water extinction coefficient may be generated by the laser source 302b or 502b discussed above.

[0144] At block 1306, the method 1300 includes calculating a ratio between the first intensity value and the second intensity value. For example, the processing unit 108 may calculate the ratio between the first intensity value and the second intensity value using Equation 2.1 at block 1306. At block 1308, the method 1300 includes estimating a distance between the distal end 204 of the optical fiber 104 and the target 102 based on the ratio between the first intensity value and the second intensity value derived at block 1306. For example, the processing unit 108 may utilize Equation 2.2 at block 1308 to estimate a distance between the distal end 204 of the optical fiber 104 and the target 102 based on the ratio between the first intensity value and the second intensity value.

[0145] 14 illustrates a flow diagram showing a method 1400 for estimating a distance between a fiber end and a target according to some embodiments of the present disclosure. The method 1400 is described with reference to the various configurations of the system 100 and LETD system 106 described above. However, it is to be appreciated that the method 1400 could be implemented with LETDs different from those described herein. The embodiments are not limited in this context.

[0146] At block 1402, the method 1400 includes illuminating a target with laser light of multiple different wavelengths. For example, one of the configurations described above can be utilized in illuminating the target 102 with light beams 332 having multiple different wavelengths. For example, light beams 332 can include light beams 320a, 320b, 320c, treatment beams 326, and / or 328 (etc.).

[0147] At block 1404, the method 1400 includes receiving a reflected light beam from the target through the optical fiber. For example, one of the configurations described herein may be utilized to receive and transmit the reflected light beam 334a (corresponding to the light reflected from the target 102) back through the optical fiber 104. In some embodiments, the reflected light beam 334a may reflect from the target 102 and enter the distal end 204 of the optical fiber 104, and thus may include the reflected light beam 334a. The reflected light beam 334a may also include light reflected from an optical component within the system (e.g., the proximal end 202 or the distal end 204, etc.), and may include a light reflection 610 corresponding to the reflected light associated with the calibration light beam 320c.

[0148] At block 1406, the method 1400 includes measuring the intensity of the reflected light beam 334a with one or more photodetectors. In many embodiments, the one or more photodetectors may use one of the configurations described herein to measure the intensity of the reflected light beam 334a. For example, photodetectors 318a and 318b may be used to measure the intensity of the reflected light beam 334b. In another example, another photodetector (such as photodetector 512) may be used to measure the intensity of the reflected light beam 334a.

[0149] At block 1408, the method 1400 includes estimating a distance between the distal end 204 of the optical fiber 104 and the target 102 based on an intensity of the reflected light beam 334a measured using one or more optical detectors. For example, the processing unit 108 can be utilized in estimating the distance between the distal end 204 of the optical fiber 104 and the target 102 based on an intensity of the reflected light beam 334a measured using one or more optical detectors.

[0150] It is to be appreciated that the optical elements (e.g., beam splitters, polarizers, beam combiners, collimators, circulators, WDMs, etc.) of the LETD system described herein are not constant over time. That is, the optical properties of these optical elements may change during a procedure due to, for example, thermal and environmental changes, mechanical vibrations, exposure to a treatment light beam (e.g., a high power laser beam), or other reasons. Because the optical components change, the system (e.g., processing unit 108, etc.) cannot properly distinguish between a change in the distance between the distal end 204 of the optical fiber 104 and the target 102 and a change in the optical components. Thus, the present disclosure provides for capturing or "capturing" light reflected from the proximal end 202 of the optical fiber 104 and using it as a reference or calibration light for the optical components such that the distance between the distal end 204 of the optical fiber 104 and the target 102 can be accurately determined even when the optical components change over time.

[0151] It is to be appreciated that the reflected light beam 334a has an angle of incidence other than zero, such that the light reflected from the proximal end 202 of the optical fiber 104 has an optical path different from the main treatment laser path. In general, the present disclosure provides a LETD system configuration that uses a mirror to direct light from the optical path into a polarizing beam splitter with two detectors. Analysis of the signals of these detectors provides a measure of the system changes compared to the initial state.

[0152] In some embodiments, in each of the example configurations described herein, the proximal end of the optical fiber 104 can be coated with a specialty coating, such as an anti-reflective (AR) coating. The AR coating can help reduce noise generated at the proximal end 202 of the optical fiber 104 and can increase the dynamic range. In some embodiments, the optical signal incident on the photodetector can include one or more of: (a) reflections from a port lens; (b) reflections from a blast shield; (c) reflections from the proximal end 202 of the optical fiber 104; and / or (d) reflections from the distal end 204 of the optical fiber 104.

[0153] In various embodiments, an AR coating on the blast shield can reduce reflections from the port lens to less than 1%, an AR coating on the port lens can reduce reflections from the blast shield to less than 1%, and an AR coating on the proximal end 202 of the optical fiber 104 can reduce reflections from the proximal end 202 of the optical fiber 104 from 3.5% to about 0.5%. In some embodiments, the reflected signal from a target 102, such as a stone, can be of very low energy, e.g., approximately 1% of the output power, when the distance from the optical fiber tip to the tissue is about 0 mm. By reducing reflections from the proximal end 202 of the optical fiber 104 by approximately 0.5%, the present disclosure can help improve the dynamic range of the signal reflected from the target 102.

[0154] 15 illustrates a LETD system 1500 similar to the LETD system 900, but with additional "light trapping" components as described herein. For example, the LETD system 1500 includes the laser sources 502a, 502b, 502c, and the laser source 702, and the WDM 704, the beam splitter 902, the photodetector 512, the power detector 306, and the beam combiner 310. The LETD system 1500 further includes a mirror 1502, a polarizing beam splitter 1504, and a photodetector 1506a. In operation, the mirror 1502 can direct the reflected light from the optical path of the reflected light beam 334a toward the polarizing beam splitter 1504. In other words, the mirror 1502 is provided to reroute the light reflection 1510 from the optical path of the reflected light beam 334a so that the light reflection 1510 does not reach the original optical detector (e.g., the photodetector 512). It should be noted that this diagram does not depict the angles of incidence of the different light beams. However, it should be appreciated that the angles of the light beams incident on the various optical components are often not 90 degrees as shown. For example, the light reflection 1510 may have an angle of incidence of 4 degrees (or the like). Additionally, while the mirror 1502 is depicted in the optical path of the light reflection 1510 between the beam combiner 310 and the beam splitter 902, it is contemplated that the mirror 1502 may instead be located in the optical path between the ports 314 and 310. Additionally, in some examples, the mirror 1502 may be positioned and arranged to not block the light beam 806, but simply redirect the light reflection 1510 as depicted and described above.

[0155] As can be seen, the light reflection 1510 is linearly polarized light and maintains this polarization after being reflected from the proximal end 202 of the optical fiber 104. The light reflection 1510 is directed through mirror 1502 to a polarizing beam splitter 1504 where it is split into two components: a light beam having a polarization parallel to the light incident on the proximal end 202 of the optical fiber 104, and a light beam having a polarization perpendicular to the light incident on the proximal end 202 of the optical fiber 104.

[0156] The LETD system 1500 further includes photodetectors 1506a and 1506b arranged to measure the intensity of the light reflection 1510 split by the polarizing beam splitter 1504. In particular, the photodetectors 1506a and 1506b are arranged to measure the intensity of the light based on the polarization as outlined herein. However, it should be noted that the parallel component of the light reflection 1510 will include both the light reflection 1510 and some portion of the light reflection 610, whereas the perpendicular component of the light reflection 1510 will only include some portion of the light reflection 610.

[0157] In some embodiments, the distance between the distal end 204 of the optical fiber 104 and the target 102 can be expressed by Equation 6.1 shown below. Equation 6.1:

number

[0158] Taking into account that each laser source fires a laser with a different illumination pulse and illumination energy, I refHI is the intensity of the reference power detector 306 for a light source with a high water extinction coefficient, and I refLO is the intensity of the reference power detector 306 for a light source with a low water extinction coefficient, and I normHI and I normLo The intensities can be normalized using Equation 6.2, where is the normalized intensity. Equation 6.2:

number

[0159] I DETλ is the reading from the detector for wavelength λ, and I distλ is the reflection reading from the distal end 204 of the optical fiber 104 for wavelength λ, and I lensλ is the reflection reading from the focusing lens 1514 of the optical fiber 104 for wavelength λ, and I sigλWhen is an isolated signal for wavelength λ (e.g., a “captured” optical signal as described herein), the “pure” reflected signal can be expressed by Equation 6.3. Note that Equation 6.3 assumes that reflections from the proximal end of the fiber are eliminated (e.g., reduced to zero) in the optical path, and that reflections from the blast shield 1512 are also eliminated. Equation 6.3: I DETλ =I sigλ +I distλ +I lensλ

[0160] The LETD system 1500 is calibrated for reflectance at wavelength λ from the focusing lens 1514, I lens-0λ , the detector reading at wavelength λ of ∞, and I dist-∞λ or the reflection from the distal end 204 of the optical fiber 104 at ∞ of wavelength λ and the I lens-0λ The sum of I DET-∞λ It can be arranged to calibrate the optical system by deriving: It is to be appreciated that the calibration is not a function of time (or rather is constant over the procedure).

[0161] By separating the signal from the detector using Equation 6.3 above, I sigλ =I DETλ -(I distλ +I lensλ ) I distλ As a function of time, this value can be calculated using a specific wavelength. Using 1435 nm as a specific example, this yields Equation 6.4 below, which is corrected for distal tip reflection. Equation 6.4:

number

[0162] During operation, a signal is acquired from the detector, which results in Equation 6.5 corrected for the distal tip reflection from the actual detector. Equation 6.5:

number

[0163] Substituting the above equation into Equation 6.5 yields Equation 6.6, which is the signal value extracted from the signal detector (eg, constant static reflectance). Equation 6.6:

number

[0164] As will be appreciated, the addition of transmittance will change the optical path. In particular, some optical components may undergo changes in transmittance and / or reflectance values. For example, focusing lenses (with transmittance of Tr lensλ ) and blast shield (transmittance is denoted as Tr blastλ ) and an optical fiber 104 (transmittance is denoted as Tr fiberλ In other words, these transmittance-sensitive signals are sigλ and I sigλ Therefore, the final equation for a signal with non-static reflection can be defined using equation 6.7. Equation 6.7:

number

[0165] I DETcal * Tr 2 lens cal * Tr 2 blast cal * Tr 2 fiber calNote that the detector value of is measured as a whole without the option of distinguishing these different factors from the detector, but Equation 6.8 below details and can take into account the transmission when the lens, blast shield, and fiber are constant, and this equation can be similar to the normalized signal discussed above. The above equation is equivalent to the following equation:

number

number

[0166] However, by applying the correction across the lens with the distal end 204 without a separate lens reflection, Equation 6.6 can be simplified as shown below in Equation 6.9. Equation 6.9:

number

[0167] In Equation 6.9, the components of lens reflectivity (e.g.,

number

number

[0168] Combining the above equations, distance can be defined as a function of luminance and reflectance as shown in Equation 6.11. Equation 6.11:

number

[0169] As outlined above, the configuration shown in FIG. 15, in other words the LETD system 1500, is arranged to “capture” light reflected off the proximal end 202 of the optical fiber 104 to calibrate the optical components of the system (e.g., focusing lens 1514, blast shield 1512, etc.). In general, the light reflection 1510 is λ is the coefficient of the signal going out in the light capture direction, and I sigλ When is a defined signal, it can be expressed by equation 6.12. Equation 6.12: I snatchedλ =f λ * (I sigλ +I distλ )+I proxλ

[0170] Equation 6.12 is

number

number

number

number

[0171] At a distance of infinity, this equation simplifies to equation 6.14. Equation 6.14:

number

[0172] From the above equation, I dist-∞λ Using the value of f λ * Tr2 fiberλ Thus, the reflection of the proximal end 202 in the “captured” optical signal (e.g., optical reflection 1510) can be extracted as I proxλ =r snatchedλ * Tr 2 lensλ * Tr 2 blastλ * I DET-refλ Therefore, r snatchedλ * Tr 2 lensλ * Tr 2 blastλ is also calibrated. As a result, r snatchedλ * Tr 2 lensλ * Tr 2 blastλ Any change in value of can be converted into equation 6.7 for each wavelength. lensλ The value of I lensλ =I DET-refλ * (1-Tr lensλ ) and therefore the square root of r snatchedλ * Tr 2 lensλ * Tr 2 blastλ A change in will compensate for these movements as well.

[0173] Similarly, from the start of the procedure to ∞, I lens-0λ It will be appreciated that it may be advantageous to calibrate

[0174] Furthermore, when polarized light is used, the noise in a polarization switch (such as WDM 704) can be described above using Equation 6.15.

number

[0175] 16 illustrates a flow diagram showing a method 1600 for estimating a distance between a fiber end and a target according to some embodiments of the present disclosure. The method 1600 is described with reference to the configuration of the system 100 and the LETD system 106 described above, and with reference to FIG. 15, in turn with reference to the LETD system 1500. However, it is to be appreciated that the method 1600 could be implemented with LETDs different from those described herein. The embodiments are not limited in this context.

[0176] At block 1602, the mirror 1502 directs a portion of the light reflected from the proximal end 202 of the optical fiber 104 to the polarizing beam splitter 1504 and the photodetectors 1506a and 1506b. That is, the mirror 1502 is arranged to direct a portion of the light reflection 1510 to the polarizing beam splitter 1504. Continuing to block 1604, the method 1600 can detect the intensity of the polarized components of the portion of the light directed to the detectors. In particular, the light reflection 1510 is split into polarized components by the polarizing beam splitter 1504, and the photodetectors 1506a and 1506b can detect the intensity of the components of the light reflection 1510.

[0177] At block 1606, the method 1600 may determine a transfer function of the optical system based at least in part on the intensities detected at block 1604. For example, the processing unit 108 may execute instructions to determine the transfer of the optical system as outlined above with respect to Equations 6.1 through 6.17.

[0178] 17 illustrates a LETD system 1700 similar to the LETD system 1500, but with a single photodetector 1706 and polarizer 1708 rather than the polarizing beam splitter 1504 and photodetectors 1506a and 1506b. It is further noted that the LETD system 1700 can be implemented in which the optical laser sources 1702a, 1702b, and 1702c are arranged to emit unpolarized optical beams 1704a, 1704b, and 1704c, respectively. It is noted that the processing unit 108 can be arranged to account for the aging of the optical components as described above with respect to FIGS. 15 and 16, in which case the equations for the transfer functions would not be polarization dependent as outlined above.

[0179] FIG. 18 illustrates a computer-readable storage medium 1800. The computer-readable storage medium 1800 may include any non-transitory computer-readable or machine-readable storage medium, such as an optical, magnetic, or semiconductor storage medium. In various embodiments, the computer-readable storage medium 1800 may include an article of manufacture. In some embodiments, the computer-readable storage medium 1800 may store computer-executable instructions 1802 that may be executed by a circuit (e.g., processing unit 108, etc.). For example, the computer-executable instructions 1802 may include instructions for performing the operations described with respect to method 1200, method 1300, method 1400, and / or method 1600. Examples of the computer-readable or machine-readable storage medium 1800 may include any tangible medium capable of storing electronic data, including volatile or non-volatile memory, removable or non-removable memory, erasable or non-erasable memory, and writeable or rewriteable memory, etc. Examples of computer-executable instructions 1802 may include any suitable type of code, such as source code, compiled code, interpreted code, executable code, static code, dynamic code, object-oriented code, visual code, and the like.

[0180] FIG. 19 is a block diagram of a computer environment 1900 that includes a computer system 1902 for implementing an embodiment consistent with the disclosure of the present invention. In some embodiments, the computer environment 1900 or a portion thereof (e.g., the computer system 1902) may include or be included in a laser system (e.g., system 100, LETD system 106, etc.). Thus, in various embodiments, the computer system 1902 can be used to determine the distance between the distal end 204 of the optical fiber 104 and the target 102 as outlined above and to account for changes in the optical system.

[0181] The computer system 1902 may include a central processing unit ("CPU" or "processor") 1904. The processor 1904 may include at least one data processor for executing instructions and / or program components for performing user-generated or system-generated processes. A user may include an individual using a device such as that included in the disclosure of this invention or another device. The processor 1904 may include dedicated processing units such as, for example, an integrated system (bus) controller, a memory management control unit, a floating point unit, a graphics processing unit, a neural processing unit, a digital signal processing unit, and the like. The processor 1904 may be arranged to communicate with input devices 1914 and output devices 1916 through an I / O interface 1912. The I / O interface 1912 can use communication protocols / methods such as, but not limited to, audio, analog, digital, stereo, IEEE-1394, serial bus, universal serial bus (USB), infrared, PS / 2, BNC, coaxial, component, composite, digital visual interface (DVI), high definition multimedia interface (HDMI), radio frequency (RF) antenna, S-video, video graphics array (VGA), IEEE 802.n / b / g / n / x, Bluetooth, cellular (e.g., code division multiple access (CDMA), high speed packet access (HSPA+), global system for mobile communications (GSM), long term evolution (LTE), or WiMAX, etc.).

[0182] Using the I / O interface 1912, the computer system 1902 can communicate with input devices 1914 and output devices 1916. In some embodiments, the processor 1904 can be arranged to communicate with a communication network 1920 through the network interface 1910. In various embodiments, the communication network 1920 can be utilized to communicate with a remote memory storage device 1906 for purposes such as accessing lookup tables, performing updates, or utilizing external resources. The network interface 1910 can communicate with the communication network 1920. The network interface 1910 can use connection protocols including, but not limited to, direct connection, Ethernet (e.g., twisted pair 10 / 100 / 1000Base T), Transmission Control Protocol / Internet Protocol (TCP / IP), Token Ring, IEEE 802.11a / b / g / n / x, and the like.

[0183] The communication network 1920 may be implemented as one of different types of networks, such as an intranet or local area network (LAN), or a closed area network (CAN). The communication network 826 may be either a dedicated network or a shared network representing the relationship of different types of networks using various protocols to communicate with each other, such as Hypertext Transfer Protocol (HTTP), CAN protocol, Transmission Control Protocol / Internet Protocol (TCP / IP), Wireless Application Protocol (WAP), and the like. Furthermore, the communication network 1920 may include various network devices, including routers, bridges, servers, computing devices, storage devices, and the like. In some embodiments, the processor 1904 may be arranged to communicate with the memory storage device 1906 through a storage interface 1908. The storage interface 1908 may be connected to the memory storage device 1906, including, but not limited to, memory drives, removable disk drives, and the like, using a connection protocol, such as, for example, Serial Advanced Technology Attachment (SATA), Integrated Drive Electronics (IDE), IEEE-1394, Universal Serial Bus (USB), Fibre Channel, Small Computer System Interface (SCSI), and the like. The memory drive may further include a drum, a magnetic disk drive, a magneto-optical drive, an optical drive, a redundant array of independent disks (RAID), a solid state memory device, a solid state drive, and the like.

[0184] Further, the memory storage device 1906 may include one or more computer-readable storage media utilized in implementing embodiments consistent with the disclosure of the present invention. Generally, a computer-readable storage medium refers to any type of physical memory capable of storing information or data readable by a processor. Thus, a computer-readable storage medium may store instructions for execution by one or more processors, including instructions for causing a processor to execute steps or stages consistent with the embodiments described herein. The term "computer-readable medium" should be understood to include tangible items and to exclude carrier waves and transient signals, i.e., non-transitory. Examples include random access memory (RAM), read-only memory (ROM), volatile memory, non-volatile memory, hard drives, compact disc (CD) ROM, digital video disc (DVD), flash drive, disk, and any other known physical storage medium.

[0185] The memory storage device 1906 may store a collection of program or database components, including, but not limited to, an operating system 1922, application instructions 1924, and user interface elements 1926. In various embodiments, the operating system 1922 may facilitate resource management and operation of the computer system 1902. Examples of operating systems include, but are not limited to, APPLE® MACINTOSH® OS X®, UNIX®, UNIX-like systems available (e.g., BERKELEY SOFTWARE DISTRIBUTION® (BSD), FREEBSD®, NETBSD®, OPENBSD, etc.), LINUX® DISTRIBUTIONS (e.g., RED HAT®, UBUNTU®, KUBUNTU®, etc.), IBM® OS / 2®, MICROSOFT® WINDOWS® (XP®, VISTA® / 7 / 8, 10, etc.), APPLE® IOS®, GOOGLE® ANDROID®, or BLACKBERRY® OS, etc.

[0186] The application instructions 1924 may include instructions that, when executed by the processor 1904, cause the processor 1904 to perform one or more techniques, steps, procedures, and / or methods described herein, such as cleaning the site and irradiating the site, as outlined herein. For example, the application instructions 1924, when executed by the processor 1904, may cause the processor 1904 to perform method 1200, method 1300, method 1400, and / or method 1600.

[0187] The user interface elements 1926 may facilitate the display, execution, interaction, manipulation, or actuation of program components through textual or graphical mechanisms. For example, the user interface may provide computer interaction interface elements, such as cursors, icons, inspection boxes, menus, scrollers, windows, widgets, and the like, on a display system operatively connected to the computer system 1902. The user interface elements 1926 may be used, for example, by the application instructions 1924 and / or the operating system 1922 to provide a user interface that allows a user to interact with the computer system 1902. In some embodiments, the user interface elements 1926 may be integrated with a display (not shown).

[0188] Terms used in this specification are to be accorded the meaning dictated by ordinary meaning in the art or usage in context, except where an explicit definition is provided, in which case that meaning takes precedence.

[0189] In this specification, references to "one embodiment" or "embodiment" may, but do not necessarily, refer to the same embodiment. Unless the context clearly requires otherwise, words such as "comprise" and "comprising" throughout this specification and claims shall be construed in an inclusive sense, i.e., "including but not limited to," as opposed to an exclusive or exhaustive sense. The use of the singular or plural also includes the plural or singular, respectively, unless expressly limited to the singular or plural. In addition, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portion of this application. When the word "or" is used in the claims in connection with a list of two or more items, the word covers all interpretations of the word to any of the items in the list, all of the items in the list, and any combination of the items in the list, unless expressly limited to one or the other. Any term not expressly defined herein has its conventional meaning as commonly understood by one of ordinary skill in the art. [Explanation of symbols]

[0190] 300 LETD System 324 Polarized Light Beam 326 Treatment Beam 328 Aiming Beam 330 Combined Light Beam 334a, 334b ​​reflected light beam

Claims

1. a first laser source generating laser light at a first wavelength; a second laser source generating laser light at a second wavelength; an optical fiber having a distal end and a proximal end, the optical fiber configured to receive laser light from the first laser source and the second laser source at the proximal end, reflect a portion of the laser light from the proximal end, emit a portion of the laser light from the distal end, and receive the reflected laser light into the distal end; a first photodetector for measuring the intensity of the reflected laser light; A second photodetector; and a mirror that directs a portion of the laser light reflected from the proximal end to the second photodetector that measures an intensity of the portion of the laser light reflected from the proximal end; a processor and a memory including instructions that, when executed by the processor, cause the processor to estimate a distance between the distal end of the optical fiber and a target based on an intensity of the reflected laser light measured by the first optical detector and an intensity of a portion of the laser light reflected from the proximal end and measured by the second optical detector; Including system.

2. 2. The system of claim 1, wherein the first wavelength has a first water extinction coefficient that is higher than a second water extinction coefficient of the second wavelength.

3. The system of claim 2 , wherein a ratio of the first water extinction coefficient to the second water extinction coefficient is at least two to one.

4. The system of claim 3 , wherein the first wavelength is from about 1330 nm to about 1380 nm.

5. 5. The system of claim 3 or 4, wherein the second wavelength is from about 1260 nm to about 1320 nm.

6. a third laser source generating laser light at a third wavelength utilized to characterize a condition of the optical fiber; The system of claim 4 , wherein the third wavelength has a third water extinction coefficient that is higher than the first water extinction coefficient and the second water extinction coefficient.

7. 6. The system of claim 5, wherein the third wavelength comprises about 1435 nm, about 2100 nm, or a wavelength between about 1870 nm and about 2050 nm.

8. 7. The system of claim 1, wherein the photodetector measures a first intensity value of the reflected laser light corresponding to the laser light of the first wavelength and a second intensity value of the reflected laser light corresponding to the laser light of the second wavelength.

9. The instructions, when executed by the processor, further cause the processor to: calculating a ratio between the first intensity value and the second intensity value; and estimating the distance between the distal end of the optical fiber and the target based on the ratio of the first intensity value to the second intensity value. The system of claim 7.

10. 9. The system of claim 1, wherein one or more of the first laser source and the second laser source comprise a polarization-maintaining pigtailed fiber laser, a single-mode pigtailed fiber laser, or a free-space laser.

11. The system of any one of claims 1 to 9, further comprising a wavelength division multiplexer (WDM) coupled to a proximal end of the optical fiber and arranging the first wavelength laser light and the second wavelength laser light to be incident on the proximal end of the optical fiber at one or more of the same point and the same angle.

12. Illuminating a target with laser light of a plurality of different wavelengths; receiving a first reflected light beam from the target through an optical fiber; receiving a second reflected light beam from the proximal end of the optical fiber; measuring the intensities of the first reflected light beam and the second reflected light beam with a plurality of photodetectors; estimating a distance between the distal end of the optical fiber and the target based on an intensity of the reflected light beam measured using the one or more optical detectors; The method includes:

13. The method of claim 12 , comprising emitting the plurality of different wavelengths of laser light through the optical fiber to illuminate the target.

14. 14. The method of claim 12 or 13, comprising measuring a first intensity value of the reflected light beam corresponding to laser light of a first wavelength and a second intensity value of the reflected light beam corresponding to laser light of a second wavelength.

15. calculating a ratio between the first intensity value and the second intensity value; estimating the distance between the distal end of the optical fiber and the target based on the ratio of the first intensity value to the second intensity value; 15. The method of claim 14, comprising:

Images