Method and system for estimating distance between end of optical fiber and target

Abstract

The present disclosure relates to the technical field of fiber feedback (FFB), and provides a method and system for estimating a distance between an end of an optical fiber and a target. The method includes irradiating a target with laser light of different wavelengths having a low water absorption coefficient and a high water absorption coefficient using different laser light sources through a light emission, transmission and detection (LETD) system, and receiving a return signal corresponding to the incident laser light of the different wavelengths and detecting the return signal to measure an intensity value of the return signal of a particular wavelength. Using the measured intensity values, the processing unit may estimate the distance between the fiber end and the target. The distance between the tail end of the optical fiber and the target can be accurately estimated. The disclosure also provides a robust distance estimation technique compatible with different types of targets.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of and priority to U.S. Provisional Application No. 63 / 341,654, filed on May 13, 2022, entitled “Method and System for Estimating Distance Between a Fiber End and a Target,” and is a continuation-in-part of U.S. Patent Application No. 17 / 535,172, filed on November 24, 2021, entitled “Method and System for Estimating Distance Between a Fiber End and a Target,” which claims the benefit of and priority to U.S. Provisional Application No. 63 / 118,857, filed on November 27, 2020, entitled “Method and System for Estimating Distance Between aFiber End and a Target,” and U.S. Provisional Patent Application No. 63 / 118,117, filed on November 25, 2020, entitled “Apparatus and Method for Enhancing Laser Beam Efficacy in a Liquid Medium" and U.S. Provisional Patent Application No. 63 / 252,830, filed on October 6, 2021, entitled "Method and System for Estimating Distance Between a Fiber End and a Target," the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to optical systems and optical fibers for medical or therapeutic laser treatment. In particular, but not exclusively, the present disclosure relates to methods and systems for estimating the distance between an optical fiber end and a target. Background Art

[0004] The introduction of lasers into the medical field and the development of fiber optic technology using lasers have opened up many applications in treatment, diagnosis, therapy, etc. Such applications range from invasive and non-invasive treatments to endoscopic surgery and image diagnosis. For example, in the treatment of urinary stones, the stones need to be broken into smaller fragments. A technique called laser lithotripsy can be used for this fragmentation process, in which, for small and medium-sized urinary stones, a rigid or flexible ureteroscope is placed through the urinary tract for illumination and imaging. At the same time, an optical fiber is inserted into the target location (e.g., the location where the stone exists in the bladder, ureter, or kidney) through the working channel of the ureteroscope. The laser is then activated to break the stone into smaller fragments or to remove dust from it. In another case, laser and fiber optic technology are used for coagulation or ablation therapy. During ablation therapy, the laser is delivered to the tissue to vaporize the tissue. During coagulation therapy, the laser is used to cause thermal damage in the tissue. This ablation therapy can be used to treat various clinical conditions, such as benign prostatic hyperplasia (BPH), cancers (such as prostate cancer, liver cancer, lung cancer, etc.), and for treating cardiac conditions by ablating and / or coagulating portions of tissue in the heart.

[0005] These treatments using laser and fiber optic technologies require high precision to ensure that the laser is aimed at the correct target (stone, tissue, tumor, etc.) to achieve clinical goals such as tissue ablation, coagulation, stone fragmentation, dust removal, etc. Therefore, it is important to know the distance between the target and the end (distal end) of the optical fiber from which the laser is emitted, because laser treatment parameters such as energy, pulse width, laser power modulation and / or repetition rate are usually determined based on the distance from the fiber tip to the target.

[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 which is transmitted through the optical fiber by modulating the numerical aperture of the light beam. However, it is not always convenient to vary the numerical aperture of the light beam. Furthermore, the separation of the reflections of light beams of different numerical apertures required by these techniques is difficult. Summary of the invention

[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 to aid in determining the scope of the claimed subject matter.

[0008] One embodiment includes a system comprising: a first laser source for generating laser light of a first wavelength; a second laser source for generating laser light of a second wavelength; an optical fiber having a distal end and a proximal end, the optical fiber being 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, transmit a portion of the laser light out of the distal end, and receive the reflected laser light into the distal end; a first light detector for measuring the intensity of reflected light; a second light detector; a reflector for directing the portion of the laser light reflected from the proximal end to the second light detector, the second light detector measuring the intensity of the portion of the laser light reflected from the proximal end; and a processor and a memory comprising 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 light detector and the intensity of the portion of the laser light reflected from the proximal end measured by the second light detector.

[0009] The system may include where a first water absorption coefficient at a first wavelength is higher than a second water absorption coefficient at a second wavelength.

[0010] The system can include where a ratio of the first coefficient of water absorption to the second coefficient of water absorption is at least 2 to 1.

[0011] The system can include where the first wavelength is from about 1330 nm to about 1380 nm.

[0012] The system may include where the second wavelength is between approximately 1260 nm and approximately 1320 nm.

[0013] The system may include a third laser source including a laser generating a third wavelength used to characterize a condition of the optical fiber, wherein the third wavelength has a third water absorption coefficient higher than the first water absorption coefficient and the second water absorption coefficient.

[0014] The system can include where the third wavelength comprises a wavelength of approximately 1435 nm, approximately 2100 nm, or between approximately 1870 nm and approximately 2050 nm.

[0015] The system may include where the light detector measures a first intensity value of reflected light corresponding to laser light of a first wavelength and a second intensity value of reflected light corresponding to laser light of a second wavelength.

[0016] The system may include where the instructions, when executed by the processor, further cause the processor to: calculate a ratio of 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.

[0017] The system can include where one or more of the first laser source and the second laser source comprises a polarization maintaining pigtailed fiber laser, a single mode pigtailed fiber laser, or a free space laser.

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

[0019] One embodiment includes a method, the method comprising: illuminating a target with multiple lasers of different wavelengths; receiving a first reflected light beam from the target via an optical fiber; receiving a second reflected light beam from a proximal end of the optical fiber; measuring the intensity of the first reflected light beam and the second reflected light beam with multiple light detectors; and estimating the distance between the distal end of the optical fiber and the target based on the intensity of the reflected light beams measured with one or more light detectors.

[0020] The method may include emitting a plurality of lasers of different wavelengths via an optical fiber to illuminate a target.

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

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

[0023] One embodiment includes at least one non-transitory computer-readable medium including a set of instructions that, in response to being executed by a processor circuit, cause the processor circuit to: determine a first intensity value based on a first reflected laser light corresponding to a laser source, wherein the first reflected laser light enters a proximal end of an optical fiber, exits a distal end of the optical fiber, is reflected by a target, and enters the distal end of the optical fiber; determine a second intensity value based on a second reflected laser light corresponding to the laser source, wherein the second reflected laser light is reflected by the proximal end of the optical fiber; calculate a ratio of 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] At least one non-transitory computer-readable medium may include, wherein the set of instructions, in response to being executed by the processor circuit, further causes the processor circuit to: subtract the first internal reflection value from the first measured intensity value to determine a first intensity value, and subtract the second internal reflection value from the second measured intensity value to determine a second intensity value.

[0025] At least one non-transitory computer-readable medium may include, wherein the set of instructions, in response to being executed by a processor circuit, further causes the processor circuit to determine an internal reflection value based on third reflected laser light corresponding to laser light at a third wavelength, wherein the laser light at the third wavelength leaves the laser source and at least a portion of the third reflected laser light is reflected by a distal end of the optical fiber.

[0026] At least one non-transitory computer-readable medium may include, wherein the set of instructions, in response to being executed by a processor circuit, further causes the processor circuit to: compare the internal reflection value to a baseline internal reflection value; and adjust an operating parameter of the therapy beam based on the comparison of the internal reflection value to the baseline internal reflection value.

[0027] At least one non-transitory computer-readable medium may include, wherein the set of instructions, in response to being executed by a processor circuit, further causes the processor circuit to: compare the internal reflectance value to a baseline internal reflectance value; characterize a state of the optical fiber based on the comparison of the internal reflectance value to the baseline internal reflectance value; and communicate an indication of the state of the optical fiber via a user interface.

[0028] At least one non-transitory computer-readable medium may include where the set of instructions, in response to being executed by the processor circuit, further cause the processor circuit to communicate, via a user interface, an indication of an estimated distance between a distal end of the optical fiber and a target. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Figure 1 A system according to one embodiment is shown.

[0031] Figure 2 A fiber optic cable is shown according to one embodiment.

[0032] Figure 3 A LETD system according to one embodiment is shown.

[0033] Figure 4 Another LETD system according to one embodiment is shown.

[0034] Figure 5 Another LETD system according to one embodiment is shown.

[0035] Figure 6 Another LETD system according to one embodiment is shown.

[0036] Figure 7Another LETD system according to one embodiment is shown.

[0037] Figure 8 Another LETD system according to one embodiment is shown.

[0038] Fig. 9 Another LETD system according to one embodiment is shown.

[0039] Fig.10 Another LETD system according to one embodiment is shown.

[0040] Fig.11 Another LETD system according to one embodiment is shown.

[0041] Fig.12 A method according to one embodiment is shown.

[0042] Fig.13 Another method according to one embodiment is shown.

[0043] Fig.14 Another method according to one embodiment is shown.

[0044] Fig.15 Another LETD system according to one embodiment is shown.

[0045] Fig.16 Another method according to one embodiment is shown.

[0046] Fig.17 Another LETD system according to one embodiment is shown.

[0047] Fig.18 A computer-readable storage medium according to one embodiment is shown.

[0048] Fig.19 Another system according to an embodiment is shown. DETAILED DESCRIPTION

[0049] The present disclosure provides methods and systems for estimating the distance between the end of an optical fiber and a target. It should be understood that the efficiency of treatment using a laser generally depends on the relative position and orientation of the optical fiber tip relative to the target. However, due to various factors, such as movement of the optical fiber relative to the position and orientation in the body of a subject (e.g., a patient), tissue environment, movement of tissue, the surface of the target, the color of the target, the pigment of the target, degradation of the optical fiber tip during treatment, water flushing and turbid environments (e.g., due to dust removal), etc., it is extremely difficult to determine or estimate the distance between the optical fiber tip and the target. Determining the distance between the optical fiber tip and the target is further complicated by the fact that the optical fiber tip is typically inserted into the body of the subject.

[0050] Incorrect estimates of the distance between the fiber tip and the target, as well as incorrect estimates of the orientation of the fiber tip, may result in aiming the laser at an area of ​​interest that is not the target. This may result in unnecessary complications, and in some cases may also result in permanent damage to certain portions of the subject's tissues, organs, etc., which may render the subject's body part dysfunctional. In some other cases, incorrect distance measurements and orientations may result in an increase in treatment duration, or may result in poor quality ablation / fragmentation results. In some cases, such as BPH or cancer, if the tumor is not properly ablated, it may result in regrowth of the tumor (or other unwanted tissue), leading to further complications. Therefore, it is important to determine the precise (or maintain the desired) distance between the fiber tip and the target while performing certain treatments using the laser and fiber techniques discussed above.

[0051] The method includes: using different laser light sources through a light emitting, transmitting and detecting (LETD) system, and irradiating the target with lasers of different wavelengths with low water absorption coefficients and high water absorption coefficients. The wavelengths can be selected in such a way that they are close to each other and belong to the same "nm scale". In addition, the LETD system receives return signals corresponding to incident lasers of different wavelengths. The return signal includes a light beam reflected from the back irradiation of the target. One or more light detectors configured in the LETD system can detect the return signal to measure the intensity value of the return signal of a specific wavelength. Using the measured intensity value, the processing unit can then estimate the distance between the end of the optical fiber and the target.

[0052] The present disclosure uses the described LETD system in different configurations, which include different arrangements of various optical components (such as beam combiners, beam splitters, polarizers, collimators, wavelength division multiplexers (WDM), photodetectors, etc.). The present disclosure enables accurate estimation of the distance between the end of the optical fiber and the target. In addition, the present disclosure provides a robust distance estimation technique compatible with different types of targets. In addition, the present disclosure can be used for the purpose of controlling and / or adjusting one or more operating parameters. For example, during treatment, the target may move around, move forward and backward, or move in other ways, or may change one or more of its shape, size, composition, pigment, and color. Therefore, the laser source parameters preset before starting to emit laser light to the target may become less effective. Traditionally, these preset parameters are manually changed, which may be error-prone and time-consuming, or in some cases, the preset parameters may remain unchanged, which may result in the situation where the optical fiber is too close or too far from the target. Therefore, the present disclosure allows automatic and real-time monitoring of the distance between the end of the optical fiber and the target, and further enables automatic change of preset laser emission parameters to adjust the laser according to the target shape, position, etc., and provide a higher possibility of achieving the desired results or achievements from the treatment.

[0053] The foregoing has broadly summarized the features and technical advantages of the present disclosure so that the following detailed description of the present disclosure can be better understood. It should be appreciated by those skilled in the art that the disclosed embodiments can be easily used as the basis for modifying or designing other structures for achieving the same purpose of the present disclosure. When considered in conjunction with the accompanying drawings, the novel features of the present disclosure, its organization and method of operation, and further objects and advantages will be better understood from the following description. However, it should be clearly understood that each of the accompanying drawings is provided for the purpose of illustration and description only and is not intended to be a definition of the limitations of the present disclosure.

[0054] Figure 1 An exemplary system 100 for estimating the distance between an optical fiber end and a target according to some embodiments of the present disclosure is shown. In some embodiments, the exemplary system 100 includes a target 102, an optical fiber 104, a light emission-transmission-detection (LETD) system 106, a processing unit 108, and an indicator 110. The target 102 may be a tissue, a stone, a tumor, a cyst, etc. to be treated, ablated, or destroyed in a subject. In some embodiments, the subject may be a human or an animal.

[0055] In addition, if Figure 2, optical fiber 104 includes a proximal end 202 and a distal end 204. Proximal end 202 is the end of optical fiber 104 through which light beam 112 enters, and distal end 204 is the end of optical fiber 104 through which light beam 112 is emitted and via which light beam 112 can be directed onto target 102. For example, the figure depicts light beam 112 entering optical fiber 104 at proximal end 202, propagating through the length of optical fiber 104, exiting optical fiber 104 at distal end 204, and being incident on target 102 from distal end 204 of optical fiber 104.

[0056] Back to Figure 1 , the light beam may be a light beam directed from a light source (e.g., included in LETD system 106, etc.). The light source may be a laser light source. As examples, such laser light sources may include, but are not limited to, solid-state lasers, gas lasers, diode lasers, and fiber lasers. The light beam 112 may include one or more of an aiming beam, a treatment beam, and any other beam transmitted through the optical fiber 104.

[0057] In various embodiments, the aiming beam can include a low intensity light beam that is transmitted through the optical fiber 104 to estimate the distance between the end of the optical fiber (e.g., distal end 204) and the target 102. In several embodiments, the treatment beam can include a high intensity light beam that is 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 beams of different wavelengths, characteristics, etc. This is described in more detail below, for example, with respect to Figure 3 .

[0058] Optical fiber 104 can be in optical communication with LETD system 106, such as Figure 1 104 and is arranged to receive a light beam, aim at a target 102, and deliver a reflected light beam reflected from the surface and surrounding area of ​​the target 102. In some embodiments, the optical fiber 104 can be optically, mechanically, and / or electrically coupled to the LETD system 106 via a port (shown in other figures herein).

[0059] In some embodiments, the LETD system 106 includes optical components, which may include, but are not limited to, one or more of a laser light source, a polarizer, a beam splitter, a beam combiner, a photodetector, a wavelength division multiplexer, a collimator, a circulator, which are configured in various combinations as explained in detail in further sections of the present disclosure.

[0060] In many embodiments, the laser light sources are configured to generate laser beams, such as a low-intensity aiming beam for aiming the beam 112 at the target 102 and a high-intensity treatment beam for treating the target 102, and / or beams with varying characteristics (e.g., intensity, wavelength, etc.) based on the application. Each laser light source can be configured to generate laser light having a different wavelength, wherein each of the different wavelengths can have a different water absorption coefficient. In addition, each laser light source can have the same aperture or a different aperture. In some embodiments, each laser light source can be assigned a different purpose, for example, one laser light source can be configured to generate an aiming beam of a specific intensity, and one laser light source can be configured to generate a treatment beam of a specific intensity, and one or more laser light sources can be configured to generate a beam of a specific wavelength with a specific water absorption coefficient. In addition, each laser light source can be configured to generate polarized laser light or non-polarized / depolarized light.

[0061] A polarizer may include an optical component that acts as an optical filter. For example, a polarizer may be configured to allow a light beam of a specific polarization to pass through, and to block a light beam of a different polarization. Thus, when undefined light (or a light beam of mixed polarities) is provided as an input to the polarizer, the polarizer provides a well-defined single polarization light beam as an output.

[0062] The beam splitter may include an optical component for dividing the incident light into two independent beams in a specified ratio. In addition, the beam splitter may be arranged to manipulate the light to be incident at a desired angle of incidence (AOI). Therefore, in many embodiments, the beam splitter may be configured mainly with two parameters, the separation ratio and the AOI. The separation ratio includes the ratio of reflection to transmission (reflection / transmission (R / T) ratio) of the beam splitter. Therefore, as used herein, if the separation ratio of the beam splitter is indicated as 50:50, this means that the beam splitter separates the incident light beam at an R / T ratio of 50:50. In other words, the beam splitter separates the incident light beam by changing the incident light by reflecting 50% and transmitting the other 50%. In addition, as an example, if the AOI of the beam splitter is indicated as 45 degrees, this means that the beam splitter ensures that the light beam will be incident at an angle of 45 degrees. The beam splitter may include, but is not limited to, a polarizing beam splitter and a non-polarizing beam splitter. The polarizing beam splitter can separate the incident light based on the S polarization component and the P polarization component, such as, for example, by reflecting the S polarization component of the light and transmitting the P polarization component of the light (or vice versa). In some embodiments, the non-polarizing beam splitter can separate the incident light beam based on a specific R / T ratio while maintaining the original polarization state of the incident light beam.

[0063] The beam combiner may include a partial reflector that combines two or more wavelengths of light, such as by using the transmission and reflection principles explained above. In many embodiments, the beam combiner may be a combination of a beam splitter and a reflector that performs the function of combining two or more wavelengths of light.

[0064] The optical detector may include a device that detects and / or measures characteristics of an optical beam and encodes the detected and / or measured characteristics in an electrical signal. For example, the optical detector may detect a particular type of optical beam (such as pre-configured) and convert the optical energy associated with the detected optical beam into an electrical signal. In some embodiments, wavelength division multiplexing may include a technique for combining multiple optical carrier signals onto a single optical fiber while using lasers of different wavelengths.

[0065] A collimator can include a device that narrows a light beam. To narrow the light beam, a collimator can be configured to make the direction of motion more consistent 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 divergent light from a point source into a parallel beam.

[0066] A circulator may include a multi-port optical device that is configured to receive and transmit light via a predetermined sequence of multiple ports. For example, a circulator may include a three (or four, or five, etc.) port optical device that is designed so that light entering any one port exits the next port. In one such example, light entering a first port may exit a second port, light entering a second port may exit a third port, and light entering a third port may exit a first port. Typically a circulator may be used to allow a light beam to travel in only one direction.

[0067] Note that where specific parameters are listed for optical components described herein, such as a beam splitter having an R / T ratio of 50:50 and an AOI of 45 degrees, these parameters are provided for a general understanding of the disclosed concepts and are not limiting. As a specific example, beam splitters having different R / T ratios and / or AOIs than those specified herein may be provided in the various embodiments described herein without departing from the scope of the present disclosure and claims. In one such example, an AOI of 40 degrees may be used. In another such example, an R / T ratio of 47:53 may be used.

[0068] The LETD system 106 is also associated with a processing unit 108 and / or a communication network (not shown). In some embodiments, the communication network may be a wired communication network or a wireless communication network. The processing unit 108 may 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 may be an independent device having the processing power required for distance estimation. For example, the processing unit 108 may include a circuit arranged to determine the distance based on the electrical signal received from the LETD system 106. As another example, the processing unit 108 may include a circuit and a memory, which include instructions, which, when executed by the circuit, cause the circuit to determine the distance based on the electrical signal received from the LETD system 106. Still, in some other embodiments, the processing unit 108 may be a computing device, such as a laptop, a desktop computer, a mobile phone, a tablet phone, etc., which is configured to perform distance estimation using its processing power.

[0069] The processing unit 108 may be associated with an indicator 110 to indicate the 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 via a vibration pattern. In various embodiments, the indicator may be presented via 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 functions of the indicator 110. In some other embodiments, the indicator 110 may be a stand-alone device that is configured to indicate the estimated distance between the distal end of the optical fiber 104 and the target 102.

[0070] Various exemplary configurations for estimating the distance between an optical fiber end and a target are explained in detail below. However, the values ​​and parameters associated with the different optical components used in each of the configurations explained below should be considered purely exemplary and should not be construed as limiting the present disclosure.

[0071] Figure 3An LETD system 300 is shown, which can be implemented as the LETD system 106 of the system 100. According to some embodiments of the present disclosure, the LETD system 300 can be configured to estimate the distance between the end of the optical fiber and the target. As depicted, the LETD system 300 includes a plurality of laser sources. In particular, laser sources 302a and 302b are shown. With respect to some embodiments, the laser sources 302a and 302b can be polarized laser sources. In addition, 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. With respect to some embodiments, the laser source 302a is arranged to generate a light beam 320a having a first wavelength, and the laser source 302b is arranged to generate a light beam 320b having a second wavelength different from the first wavelength, wherein the first wavelength has an absorption coefficient higher than the absorption coefficient of the second wavelength (e.g., in water, etc.).

[0072] As used herein, the light beam 320a generated by the laser source 302a may be referred to as high water absorption coefficient light (HI), while the light beam 320b generated by the laser source 302b may be referred to as low water absorption coefficient light (LO). It should be understood that even though the terms "high" and "low" are used, they are intended to be interpreted relative to each other, or in the alternative, relative to a threshold characteristic describing water absorption at a particular wavelength. For example, a high water absorption characteristic may be greater than or equal to 50%, while a low water absorption characteristic may be less than or equal to 50%.

[0073] In various embodiments, the ratio of the high water absorption coefficient to the low water absorption coefficient can be about 1:2. For example, laser 225a can utilize a wavelength of about 1310 nm and have a water absorption coefficient of about 0.1651, while laser 225b can utilize a wavelength of about 1340 nm and have a water absorption coefficient of about 0.333. A higher ratio between the high absorption coefficient and the low absorption coefficient may result in lower sensitivity to system noise (e.g., electrical noise or optomechanical noise), but the resulting system may be ineffective at distances greater than 3 mm. A lower ratio between the high absorption coefficient and the low absorption coefficient may result in higher sensitivity to system noise, but the resulting system may remain effective at distances of up to 5 or 6 mm. In some examples, laser sources 302a and 302b may be polarization maintaining (PM) pigtailed fiber lasers.

[0074] Laser sources 302a and 302b are associated with and in optical communication with a beam splitter 304. Stated differently, light beams 320a and 320b generated by laser sources 302a and 302b, respectively, are provided as inputs to beam splitter 304, which is configured to split incident light beams 320a and 320b in a ratio of approximately 50:50 (e.g., 47:53 or 49:51) such that incident light beams 320a and 320b are aligned along a single optical path as light beam 322. However, it will be appreciated that any ratio between 99:1 and 1:99 may be utilized without departing from the scope of the present disclosure. Similarly, while an AOI of 45 degrees may be described in an embodiment, it will be appreciated that any AOI between 1 and 89 (such as 43-47 degrees, 40 degrees, or 20 degrees) may be utilized without departing from the scope of the present disclosure.

[0075] Power detector 306 is associated with and in optical communication with beam splitter 304. Power detector 306 is arranged to measure the optical power of light in an optical signal corresponding to each wavelength of light in beam 322 (e.g., the portion of beams 320a and 320b routed to power detector 306). In some embodiments, the term "optical power" may refer to the energy transmitted by a laser beam per unit time.

[0076] The beam splitter 304 is also associated with and in optical communication with the polarizer 308. The beam splitter 304 is also arranged to provide a portion of the light beams 320 and 320b, represented as light beam 322, aligned along a single optical path, as an input to the polarizer 308. In some embodiments, the polarity of the polarizer 308 can be pre-configured and arranged to output a polarized light beam 324. The LETD system 300 also includes a beam combiner 310, which is in optical communication with the polarizer 308. In this manner, the polarized light beam 324 obtained as an output from the polarizer 308 is provided as an input to the beam combiner 310.

[0077] The beam combiner 310 can combine the polarized beam 324 with a treatment beam 326 and an 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 320a and 320b. As an example, the treatment beam 326 can be generated by a solid-state laser or a fiber laser, such as a holmium (HO) laser or a thulium fiber laser (TFL). However, this should not be considered a limitation of the present disclosure, as the treatment beam 326 can be generated by a laser other than HO or TLF, such as neodymium, erbium, etc. In some other embodiments, the treatment beam 326 and the aiming beam 328 can be generated by the laser sources 320a and / or 320b.

[0078] The beam combiner 310 can combine the polarized beam 324 with the treatment beam 326 and the aiming beam 328 to form a combined beam 330. The LETD system 300 also 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 beam 330, including the polarized 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.

[0079] In such an arrangement, the beam splitter 312 can split the combined light beam 330 in a 50:50 ratio such that the polarized light beam 324, the aiming beam 326, and the treatment beam 328 are aligned along a single optical path. The beam splitter 312 is optically coupled to the optical fiber 104 (e.g., via a port 314, etc.) such that a portion of the combined light beam 330, which is the output of the beam splitter 312, is transmitted through the optical fiber 104 (e.g., via a port 314) and is represented as a light beam 332. The light beam 332 is transmitted to the proximal end 202 of the optical fiber 104 and then propagates through the length of the optical fiber 104 to be delivered to the target 102 from the distal end 204 of the optical fiber 104. As an example, the target 102 can be a tissue, a stone, a tumor, a cyst, etc. in a subject to be treated, ablated, destroyed, etc.

[0080] When the light beam 332 is delivered to the target 102 via the optical fiber 104, the target 102 may reflect a portion of the incident light beam 332 away from the optical fiber 104 and reflect a portion of the light toward the optical fiber 104, wherein the portion of the light reflected toward the optical fiber 104 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 at the distal end may be referred to as a reflected light beam 334a. The reflected light beam 334a may be transmitted "backwards" in the optical fiber 104 from the distal end 204 of the optical fiber 104 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, the reflected light beam 334a may be subjected to the beam splitter 312. The reflected light beam 334a may include numerous reflections, such as from the target 102, the distal end 204 of the optical fiber 104, the proximal end 202 of the optical fiber 104, the port 314, etc. Therefore, the reflected light beam 334a is no longer polarized.

[0081] LETD system 300 also includes polarization beam splitter 316, photodetector 318a and photodetector 318b. Reflected light beam 334a can be incident on beam splitter 312 at an angle of 45 degrees, and separated in a ratio of 50:50 (or other ratios described in detail herein), resulting in reflected light beam 334a being aligned as reflected light beam 334b ​​along a single optical path. Polarization beam splitter 316 is arranged to optically communicate with beam splitter 312, and is arranged to receive reflected light beam 334b ​​and polarize reflected light beam 334b. In some embodiments, polarization beam splitter 316 can divide reflected light beam 334b ​​into a reflected P polarized beam and a transmitted S polarized beam. One of photodetector 318a or 318b can be configured to detect the P polarized beam of reflected light beam 334b, and another of photodetector 318a or 318b can be configured to detect the S polarized beam of reflected light beam 334b. The light detectors 318a and 318b can respectively measure the intensity of the detection beam of the reflected light beam 334b ​​and transmit the intensity 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. The method of estimating the distance between the distal end 204 of the optical fiber 104 and the target 102 based on the measured intensity is explained in more detail below.

[0082] Figure 4 LETD system 400 is shown, which can be implemented as LETD system 106 of system 100. According to some embodiments of the present disclosure, LETD system 400 can be configured to estimate the distance between the end of an optical fiber and a target. For convenience, the same reference numerals are used when the components of LETD system 400 are the same as those of the previously described LETD systems (e.g., LETD system 300, etc.).

[0083] LETD system 400 differs from LETD system 300 in two constructional aspects. One of the constructional aspects that differs between LETD system 400 and LETD system 300 is that beam splitter 304 is replaced by beam combiner 402. Since beam splitter 304 is replaced by beam combiner 402, power detector 306 that was associated with beam splitter 304 in LETD system 300 is arranged to be associated with beam splitter 312 in LETD system 400. In this context, the embodiments are not limited.

[0084] 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 polarizing beam splitters and non-polarizing beam splitters. Figure 4As shown, LETD system 400 includes laser source 302a, laser source 302b, beam combiner 402, polarizer 308, beam combiner 310, beam splitter 312, power detector 306, polarization beam splitter 316, photodetector 318a and photodetector 318b. In this configuration, as shown in FIG. Figure 4 As shown, laser source 302a outputs a light beam 320a having a wavelength with a high water absorption coefficient (HI), and laser source 302b outputs a light beam 320b having a wavelength with a low water absorption coefficient (LO).

[0085] An incident beam from a laser source (laser sources 302a and 302b) is provided as an input to a beam combiner 402, which is configured to combine the incident beams 320a and 320b generated by the laser sources 302a and 302b into a beam 322. In addition, the output of the beam combiner 402 (e.g., beam 322) can be provided as an input to a polarizer 308, which is used to provide a polarized beam 324 as an output. In some embodiments, the polarization of the polarizer 308 can be pre-configured. Thereafter, the polarized beam 324 obtained as an output from the polarizer 308 can be provided as an input to a beam combiner 310. The beam combiner 310 can combine the polarized beam 324 with the aiming beam 328 and the treatment beam 326 into a combined beam 330, as shown in FIG. Figure 4 shown.

[0086] A combined beam 330 including an aiming beam 328, a therapeutic beam 326, and a polarized beam 324 from laser sources 302a and 302b can be subjected to a beam splitter 312 having a configuration of a 50:50 R / T ratio and a 45 degree AOI (or any other R / T ratio and AOI as outlined herein). The beam splitter 312 can split the combined beam 330 in a 50:50 ratio so that the aiming beam 328, the therapeutic beam 326, and the polarized beam 324 can be aligned along a single optical path.

[0087] The power detector 306 associated with the beam splitter 312 can measure the power in the optical signal corresponding to each wavelength (polarized light beam 324, etc.). 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" can refer to the energy transmitted by a laser beam per unit time. Figure 3 As outlined, beam 332, which is the output of beam splitter 312, is then transmitted to optical fiber 104 (eg, via port 314). Additionally, reflected beam 334a is received and processed as described above with respect to Figure 3 As outlined.

[0088] Figure 5An LETD system 500 for estimating the distance between an optical fiber end and a target according to some embodiments of the present disclosure is shown. The present disclosure can work with a polarized laser source and a non-polarized laser source. Therefore, in the LETD system 500, laser sources 502a and 502b for providing an incident light beam (source light) are non-polarized laser sources. As an example, laser sources 502a and 502b can be single-mode (SM) fiber pigtail lasers. When laser sources 502a and 502b are non-polarized laser sources, polarizer 308, polarized polarization beam splitter 316, light detector 318a for detecting a P polarized light beam, and light detector 318b for detecting an S polarized light beam are not required, as described in the above-mentioned LETD system 300 and LETD system 400.

[0089] The LETD system 500 may include one or more non-polarized lasers, one or more beam splitters, a beam combiner, and a photodetector. One or more beam splitters may be non-polarized beam splitters. Figure 5 As shown, the LETD system 500 includes a non-polarized laser source 502a, a non-polarized laser source 502b, a beam splitter 304, a power detector 306, a beam combiner 310, a beam splitter 312, and a light detector 512.

[0090] As with the prior art, in the LETD system 500, the non-polarized laser source 502a may have a wavelength with a high water absorption coefficient (HI), and the non-polarized laser source 502b may have a wavelength with a low water absorption coefficient (LO). Light beams 504a and 504b from the laser sources 502a and 502b, respectively, are provided as inputs to the beam splitter 304, which is configured to split the incident light beams in a 50:50 ratio in the following manner, so that the incident light beams 504a and 504b are aligned along a single optical path as a light beam 506.

[0091] A power detector 306 associated with the beam splitter 304 can measure the power in the optical signal (beam 506) corresponding to each wavelength. Since the LETD system 500 is implemented in a non-polarized environment, polarization-based optical components, such as polarizers and polarization beam splitters, are not required in this configuration. Therefore, the output of the beam splitter 304, i.e., the incident beams 504a and 504b aligned along a single optical path as the beam 506, can be provided as input to the beam combiner 310. The beam combiner 310 can combine the beam 506 from the beam splitter 304 with the aiming beam 328 and the treatment beam 326, as shown in FIG. Figure 5 shown.

[0092] In some embodiments, aiming beam 328 and treatment beam 326 may be generated by one or more laser sources in addition to laser sources 502a and 502b. In some other embodiments, aiming beam 328 and treatment beam 326 may be generated by laser sources 502a and 502b. Combined beam 508 including aiming beam 328, treatment beam 326, and unpolarized beam (beam 506) may be subjected to beam splitter 312 having a configuration of a ratio of 50:50 and an AOI of 45 degrees (or any other R / T ratio and AOI as outlined herein). Beam splitter 312 may split combined beam 508 in a ratio of 50:50 such that aiming beam 328, treatment beam 326, and unpolarized beam (beam 506) are aligned along a single optical path. Beam 510, which is the output of beam splitter 312, is then transmitted to optical fiber 104 (e.g., via port 314), while reflected beam 514a is transmitted backward, as shown. Figure 5 shown and described above.

[0093] Because LETD system 500 is implemented in a non-polarized environment, reflected light beam 334a is only subjected to second beam splitter 312 to align the optical path of reflected light beam 514a, without the need for a polarization beam splitter as described in LETD system 300 and LETD system 400. Reflected light beam 514a will be incident on beam splitter 312 at a 45 degree angle and separated in a 50:50 ratio. Reflected light beam 334b ​​coming out of beam splitter 312 can be directly detected by a single detector. Like this, LETD system 500 provides light detector 512.

[0094] The light detector 512 can measure the intensity of the detection beam of the reflected light beam 514b, respectively, and transmit the intensity 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. The method of estimating the distance between the distal end 204 of the optical fiber 104 and the target 102 based on the measured intensity is explained in more detail below.

[0095] Figure 6An exemplary LETD system 600 for estimating the distance between an optical fiber end and a target according to some embodiments of the present disclosure is shown. The LETD system 600 includes a third polarized laser source 302c, which is introduced for the purpose of real-time calibration of the optical fiber state. As an example, the state of the optical fiber 104 may include, but is not limited to, any changes or degradations at the distal or proximal ends of the optical fiber 104, the effects of optical fiber bending on polarization scrambling, or any other degradation and changes occurring in the optical fiber 104. Changes in the state of the optical fiber 104, particularly the tip / end (e.g., input and output faces) of the optical fiber 104 may adversely affect the transmitted and reflected beams, resulting in a large amount of reflections, energy loss, and inaccurate measurements. This may affect the accuracy of the distance estimate, resulting in incorrect positioning of the optical fiber 104 during treatment.

[0096] 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 polarizing beam splitters and non-polarizing beam splitters. Figure 6 As shown, LETD system 600 includes polarized laser source 302a, polarized laser source 302b and polarized laser source 302c, beam splitter 304, beam splitter 602, power detector 306, polarizer 308, beam combiner 310, beam splitter 312, beam splitter 604, light detector 318a and light detector 318b. Figure 6 As shown, light beams 320a and 320b from laser sources 302a and 302b are provided as input to beam splitter 304, which is configured to split light beams 320a and 320b at a ratio of 50:50, so that light beams 320a and 320b are aligned along a single optical path to form light beam 322. In addition, the output of beam splitter 304 (e.g., light beam (light beam 322)), which is light beams 320a and 320b aligned along a single optical path, can be provided as input to beam splitter 602, which is also configured to split the incident light beam at a ratio of 50:50 to form a polarized light beam 606 including light beams 320a, 320b, and 320c.

[0097] At the beam splitter 602, an incident light beam 320c (e.g., light for calibration) from a polarized laser source 302c is provided as an input along with the output (e.g., light beam (beam 322)) of the beam splitter 304. A power detector 306 associated with the beam splitter 602 can measure the power in the optical signal (e.g., light beam 606) corresponding to each wavelength reaching the beam splitter 602. Along with the output of the beam splitter 304, the beam splitter 602 receives the incident light beam from the polarized laser source 302c.

[0098] In some embodiments, polarized laser light source 302c has a wavelength with a very high water absorption coefficient (e.g., substantially, completely or almost completely absorbed by water) relative to the wavelength of light emitted by laser sources 302a and 302b. As an example, the wavelength of polarized laser light source 302c can be about 1435nm and has a water absorption coefficient of about 31.55 (or about 100 times that of a "high" water absorption source). At a distance of 0.5mm at a wavelength of 1435nm, about 98-99% of the light is absorbed. In some embodiments, the calibration light source can have a wavelength of about 1420 to about 1440 (resulting in a water absorption coefficient of about 30). Alternative or additional wavelengths with very high water absorption coefficients (e.g., 1870-2070nm) can be utilized. However, the farther the wavelength is from the HI and LO wavelengths (e.g., 1310nm and 1340nm, respectively), the more complex the optical design may result. For example, the detector may cover a range of about 1100 nm to 1600 nm, and if the very high water absorption coefficient laser has a wavelength of 2000 nm, a unique or additional detector will be required. In some embodiments, the calibration laser may have a wavelength of about 1435 nm, about 2100 nm, or a wavelength between about 1870 nm and about 2050 nm.

[0099] Based on the readings of the polarized laser source 302c (e.g., as 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, because the laser source 302c is highly absorbed in water, it is unlikely that light from the laser source 302c will reach the target tissue, and as a result, almost no light from the laser source 302c will be reflected back into the optical fiber 104 as part of the reflected light beam 334a. Therefore, the components of the reflected light beam 334a having the wavelength of the light associated with the laser source 302c (e.g., the light reflection 610) are primarily due to the optical properties of the distal end 204 of the optical fiber 104. It should be understood that the distal end 204 of the optical fiber 104 undergoes degradation during laser treatment due to, for example, heat and cavitation. In many embodiments, an increased intensity reading of the backlight reflection 610 can indicate fiber tip degradation. In several embodiments, at a certain threshold (e.g., 10% to 50%, greater than or equal to 25%, 50%, 75%, 90%, between 10% and 100%, etc.) of intensity change from a baseline reading for a particular fiber, the processing unit 108 can indicate that the optical fiber 104 should be inspected or replaced, such as through a user interface and / or an audible alarm. In addition, fiber tip degradation may result in higher internal reflections of light from polarized laser sources 302a and 302b from the distal end of the optical fiber. Whether the laser source is polarized may have little effect on the internal reflections because the light is randomly depolarized in the optical fiber. However, monitoring the reflection from the distal end of the optical fiber by a very high absorption coefficient laser (e.g., a 1435 nm laser) can be used to determine the change in the distal end reflection (as a percentage of the initial reflection of 1435 to the real-time reflection). In addition, for LO lasers (e.g., 1310 nm lasers) and HI lasers (e.g., 1340 nm lasers), the change in the distal end reflection can be applied to the initial reflection from the distal end to update the initial reflection.

[0100] Additionally, fiber tip degradation may change the ratio between polarity P and polarity S in the reflected beam 334a or light reflection 610. Thus, creating baseline readings for the particular optical fiber 104 currently in use, and monitoring these baselines in real time, may allow for more accurate distance estimates, even as and during fiber tip degradation and until degradation reaches a threshold level indicating that the optical fiber 104 should be replaced. Additionally, the output of the beam splitter 602 or beam 606 (which includes beams 320a, 320b, and 320c aligned along a single optical path) may be provided as an input to the polarizer 308 to obtain a single polarized beam 608 as an output. In some embodiments, the polarization of the polarizer 308 may be preconfigured.

[0101] The polarized beam 608 obtained as an output from the polarizer 308 can be provided as an input to the beam combiner 310. The beam combiner 310 can combine the polarized beam 608 with the aiming beam 328 and the treatment beam 326 to form a combined beam 612, as shown in FIG. Figure 6 As described above, aiming beam 328 and / or therapy beam 326 may be generated by one or more laser sources other than laser sources 320a, 320b, or 320c, or may be generated by these laser sources.

[0102] The combined beam 612 including the aiming beam 328, the treatment beam 326, and the polarized beam 608 may be subjected to the beam splitter 312, which has a configuration of a ratio of 50:50 and a 45 degree AOI. The beam splitter 312 may split the combined beam 612 at a ratio of 50:50, so that the aiming beam 328, the treatment beam 326, and the polarized beam 608 are aligned along a single optical path. The beam 614, which is the output of the beam splitter 312, is then transmitted to the optical fiber 104 (e.g., via the port 314).

[0103] Figure 7 An exemplary LETD system 700 for estimating the distance between an optical fiber end and a target according to some embodiments of the present disclosure is shown. Like LETD system 500, LETD system 700 is implemented in a non-polarization environment. In addition, LETD system 700 is a "half-fiber-based design" in which the two input beam splitters seen in the previous configuration (e.g., the configuration of LETD system 600) are replaced by a wavelength division multiplexer (WDM). The WDM power loss can be about 20%, while the beam splitter power loss can be about 50%, thereby improving the efficiency of LETD system 700 using WDM. In addition, WDM can perfectly or almost perfectly align each of the three laser sources into the optical path. However, the beam splitter and beam combiner are much less accurate in aligning each of the three laser sources into a single beam.

[0104] The LETD system 700 utilizes a third non-polarized laser source 502c as well as a first non-polarized laser source 502a and a second non-polarized laser source 502b. As described above, the third non-polarized laser source 502c is introduced for the purpose of real-time calibration of the fiber state. It will be understood that the calibration laser can be polarized or non-polarized without departing from the scope of the present disclosure. The LETD system 700 may include one or more non-polarized lasers, one or more beam splitters, a beam combiner, one or more photodetectors, a WDM, and a collimator. Figure 7As shown, the LETD system 700 includes a non-polarized laser source 502a, a non-polarized laser source 502b, a non-polarized 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 light detector 512. In the configuration of the LETD system 700, the non-polarized laser source 502a can emit light having a high water absorption coefficient (HI) at a wavelength, and the non-polarized laser source 502b can emit light having a low water absorption coefficient (LO) at a wavelength. In addition, the non-polarized laser source 502c can emit light having a very high water absorption coefficient (e.g., completely or almost completely absorbed by water) at a wavelength relative to the wavelength of the light emitted by the laser sources 502a and 502b. As an example, the wavelength of the non-polarized laser source 502c can be 1435nm.

[0105] As mentioned above, in the configuration of LETD system 700, Figure 6 The beam splitter 304 and the beam splitter 602 shown in the LETD system 700 are replaced by WDM 704. In some embodiments, to ensure the correct use of the non-polarized laser source 502c, as a real-time calibrator, the incident beam from each of the non-polarized lasers (laser sources 502a, 502b, and 502c) can be arranged to enter the near end of the optical fiber 104 at the same point and at the same angle. In many embodiments, it may be difficult or impossible to align the incident beam from each of the non-polarized lasers (laser sources 502a, 502b, and 502c) using a combiner / beam splitter to enter at the same point and at the same angle. In order to ensure compliance with the same point and the same angle conditions, the configuration shown in the LETD system 700 uses WDM 704. WDM 704 can be configured to ensure that all incident beams from each of the non-polarized lasers (laser sources 502a, 502b, and 502c) enter the near end 202 of the optical fiber 104 at the same point and at the same angle. Furthermore, in various embodiments, the use of WDM 704 may reduce power losses, such as when compared to some beam splitters that result in 50%-75% power losses.

[0106] The incident beams from the laser sources 502a, 502b, and 502c and the aiming beam 328 are provided as inputs to the WDM 704, which is configured to combine the incident beams in a manner that the beams move in the same manner. In addition, the output of the WDM 704 can be provided as inputs to a fiber-based beam splitter (e.g., a fourth beam splitter 706), which can be arranged to separate the incident beams at a high transmission-reflection ratio (e.g., 95:5 or 99:1), such as Figure 7As shown. In some embodiments, the beam splitter 706 is a fiber-based beam splitter. The power detector 306 associated with the beam splitter 706 can measure the power in the optical signal (e.g., beam 710) corresponding to each wavelength. In addition, the output of the beam splitter 706 (e.g., beam 710), which is the incident light aligned along a single optical path, can be provided as an input to the collimator 708 to narrow the beam 710 into a parallel beam.

[0107] Thereafter, the output of collimator 708 (e.g., beam 712) may be provided to beam combiner 310, which combines beam 712 from collimator 708 with aiming beam 328 and treatment beam 326, as shown in FIG. Figure 7 In several embodiments, aiming beam 328 may be introduced at WDM 704. In many embodiments, aiming beam 328 may be introduced at beam combiner 310. Still, in some embodiments, aiming beam 328 may be introduced at both WDM 704 and first beam combiner 310. In some embodiments, aiming beam 328 and / or therapy beam 326 may be generated by one or more laser sources in addition to laser sources 502a, 502b, and 502c, or aiming beam 328 and / or therapy beam 326 may be generated by laser sources 502a, 502b, and 502c.

[0108] The combined light beam 508 including the aiming beam 328, the treatment beam 326, and the light beam 712 (e.g., such as light from the laser sources 502a', 502b, and 502c received from the collimator 708) can be subjected to the beam splitter 312, which has a configuration of an R / T ratio of 50:50 and a 45 degree AOI. The beam splitter 312 can split the combined light beam 508 in a 50:50 ratio so that the aiming beam 328, the treatment beam 326, and the unpolarized light beams from the laser sources 502a, 502b, and 502c can be aligned along a single optical path. The light beam 510, which is the output of the beam splitter 312, is then transmitted to the optical fiber 104 (e.g., via the port 314), as shown above and described more fully.

[0109] Figure 8 An exemplary LETD system 800 for estimating the distance between an optical fiber end and a target according to some embodiments of the present disclosure is shown. As with the configurations of LETD system 500 and LETD system 700, LETD system 800 is implemented with a non-polarized detector. However, the source can be non-polarized or polarized. In this exemplary configuration, 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. Figure 8As shown, LETD system 800 includes non-polarized laser source 502a, non-polarized laser source 502b, non-polarized laser source 502c, laser source 702, wavelength division multiplexer (WDM) 704, beam splitter 706, power detector 306, circulator 802, photodetector 512, collimator 708 and beam combiner 310. In the configuration of LETD system 800, non-polarized laser source 502a can emit light having a high water absorption coefficient (HI) at its wavelength, while polarized laser source 502b can emit light having a low water absorption coefficient (LO) at its wavelength. In addition, non-polarized laser source 502c can have a wavelength with a very high water absorption coefficient, which is substantially absorbed in water.

[0110] As described above, in the LETD system 800, Figure 6 The beam splitter 304 and the beam splitter 602 shown in FIG. Figure 7 and Figure 8 314. In addition, in the LETD system 800, the beam splitter 312, which is arranged to deliver the light beam to the port 314 in all the above exemplary configurations, is also removed. The beam splitter reduces the output power by up to 50% (or more) and reduces the output power by an additional 50% (or more) when receiving the return signal. Therefore, removing the beam splitter 312 in the LETD system 800 can significantly increase the output power and the reflected signal.

[0111] Incident light beams 504a, 504b and 504c from laser sources 502a, 502b and 502c, respectively, and aiming beam 328 are provided as input to WDM 704, which is configured to combine incident light beams in a manner that the light beams move in the same manner. Further, the output of WDM 704 can be provided as input to beam splitter 706, which separates the incident light beams in a ratio of 95:5. As previously mentioned, other ratios (such as 99:1) can be used without departing from the scope of the present disclosure. In some embodiments, beam splitter 706 is a beam splitter based on optical fiber, thereby making the configuration of LETD system 800 a design based on all-fiber. The power detector 306 associated with beam splitter 706 can measure the power in the optical signal (e.g., light beam 710) corresponding to each wavelength. In addition, the output (e.g., light beam 710) of beam splitter 706 as incident light aligned along a single optical path can be provided as input to circulator 802. Circulator 802 is configured to ensure that all beams propagate in one direction. In addition, circulator 802 provides beam 804 to collimator 708 from a port other than the port where beam 710 enters. Collimator 708 can narrow the beam to a parallel beam 804. When compared to a beam splitter, circulator 802 can provide (1) lower power loss (beam splitter loss is ~50% in each direction) and (2) more flexible optical design (free space optics requires straight lines, while fiber-based designs can be folded as needed).

[0112] The output of the collimator 708 (e.g., the parallel beam 804) can be provided to the beam combiner 310, which combines the beam 804 from the collimator 708 with the aiming beam 328 and the treatment beam 326 into a combined beam 806, such as Figure 8 310 . In some embodiments, aiming beam 328 may be introduced at the beginning (e.g., into WDM 704), may be introduced at beam combiner 310, or may be introduced at both WDM 704 and beam combiner 310. In some embodiments, aiming beam 328 and / or treatment beam 326 may be generated by one or more laser sources other than the laser sources shown in this figure, or aiming beam 328 and / or treatment beam 326 may be generated by the laser sources shown in this figure. A combined beam (beam 806) including aiming beam 328, treatment beam 326, and beam 804 (e.g., beams 504a, 504b, and 504c) received from beam combiner 310 may be transmitted to optical fiber 104 (e.g., via port 314), as shown. Figure 8 The combined light beam 806 is transmitted to the proximal end 202 of the optical fiber 104 , and then propagates through the length of the optical fiber 104 , and can be delivered to the target 102 from the distal end 204 of the optical fiber 104 .

[0113] As outlined above, when the light beam 806 is delivered to the target 102 via the distal end 204 of the optical fiber 104, the target 102 may reflect a portion of the light away from the optical fiber 104 and reflect a portion of the light toward the optical fiber 104, wherein the portion of the light reflected toward 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 at the distal end 204 is referred to as the reflected light (the reflected light beam 334a). The reflected light beam 334a may be transmitted "backwards" from the distal end 204 to the proximal end 202 through the optical fiber 104. When the reflected light beam 334a reaches the proximal end 202 of the optical fiber 104, the reflected light beam 334a may pass through the beam combiner 310 and the collimator 708 to undergo the circulator 802, where it is routed to the optical detector 512 and as described above with respect to Figure 7 The measured quantity.

[0114] Fig. 9 Shown is a LETD system 900, which, like some existing configurations, can be implemented in a non-polarized environment. In several embodiments, the LETD system 900 can include an optical design based on a single beam splitter. In the configuration of the LETD system 900, the WDM 704 can replace the function or operation of multiple beam splitters (e.g., those used in the LETD system 300, LETD system 400, 500 and / or LETD system 600, etc.). The WDM 704 can receive light beams 504a, 504b and 504c from non-polarized laser sources 502a, 502b and 502c, respectively.

[0115] The LETD system 900 may include one or more non-polarized lasers (or polarized lasers), a beam splitter, a beam combiner, one or more photodetectors, a WDM, and a collimator. Fig. 9 As shown, LETD system 900 includes non-polarized laser source 502a, non-polarized laser source 502b, non-polarized laser source 502c, laser source 702, wavelength division multiplexer (WDM) 704, beam splitter 902, power detector 306, photodetector 512 and beam combiner 310. In LETD system 900, as in the existing configuration, the wavelength of non-polarized light beam 504a can have a high water absorption coefficient (HI) relative to non-polarized light beam 504b, while the wavelength of non-polarized light beam 504b itself can have a lower water absorption coefficient (LO). In addition, non-polarized light beam 504c can have a wavelength with a very high water absorption coefficient as described in detail above.

[0116] As described above, the processing unit 108 can define optical baseline characteristics of the quality of the distal end 204 (e.g., output face, etc.) of the optical fiber 104 based on the readings associated with the reflection of the light generated by the non-polarized laser source 502c. More specifically, because the light from the laser source 502c is highly absorbed in water, a small amount of this light will be reflected back into the optical fiber 104 as part of the reflected beam 334a. Therefore, the readings associated with the light reflection 610 are primarily due to the optical properties of the distal end 204 of the optical fiber 104, which, as described, undergo degradation during laser treatment due to, for example, heat and cavitation. Therefore, the increased intensity readings of the light reflection 610 can indicate fiber tip degradation.

[0117] In several embodiments, at a certain threshold (e.g., 10% to 50%, greater than or equal to 25%, 50%, 75%, 90%, between 10% and 100%, etc.) of intensity variation from a baseline reading for a particular optical fiber 103, the processing unit 108 may indicate that the optical fiber 104 should be inspected or replaced, such as through a user interface and / or an audible alarm. Additionally, fiber tip degradation may result in higher internal reflections of light associated with an unpolarized laser source (laser sources 502a and 502b) from the distal end 204 of the optical fiber 104. Furthermore, fiber tip degradation may change the ratio between polarity P and polarity S in the reflected light beam 334a or 334b. Thus, creating baseline readings for a particular optical fiber currently in use, and monitoring these baselines in real time, may allow for more accurate distance estimates, even when and during fiber tip degradation and until degradation reaches a point where the optical fiber should be replaced. Thus, greater dynamic control of parameters associated with a therapy or treatment may be provided.

[0118] As with some existing LETD system configurations, the LETD system 900 utilizes a WDM 704 to ensure that all incident beams from each of the unpolarized lasers 502a, 502b, and 502c enter the proximal end 202 of the optical fiber 104 at the same point and at the same angle. In addition, in various embodiments, the use of the WDM 704 can reduce power losses, such as when compared to some configurations utilizing a beam splitter.

[0119] The light beams 504a, 504b, and 504c from the depicted laser sources and the aiming beam 328 can be provided as inputs to the WDM 704, which can be configured to combine the incident light beams in a manner that the light beams move in the same manner. In addition, the output of the WDM 704 can be provided as inputs to a beam splitter 902, which can split the incident 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, a power detector 306 associated with the beam splitter 902 can measure the power in the optical signal (e.g., light beam 710) corresponding to each wavelength.

[0120] The output of the beam splitter 902, which is the incident light aligned along a single optical path, can be provided as an input to the beam combiner 310. The beam combiner 310 can combine the light beam 710 from the beam splitter 902 with the aiming beam 328 and the treatment beam 326, as shown in FIG. Fig. 9 310 . In various embodiments, aiming beam 328 may be introduced into WDM 704, introduced at beam combiner 310, or introduced at both WDM 704 and beam combiner 310. In several embodiments, aiming beam 328 and / or therapy beam 326 may be generated by one or more laser sources other than laser sources 502a, 502b, and 502c, or aiming beam 328 and / or therapy beam 326 may be generated by these laser sources. Combined beam 806 including aiming beam 328, therapy beam 326, and beam 710 received from beam combiner 310 may be transmitted to optical fiber 104 (e.g., via port 314).

[0121] As can be seen from this figure, the LETD system 900 eliminates the use of multiple beam splitters. In addition, since the LETD system 900 utilizes a single beam splitter, it may be significantly less sensitive to treatment fiber movement and fiber bending radius, resulting in a more robust configuration. Moreover, since the LETD system 900 has fewer optical components, such as beam splitters, beam combiners, detectors, etc., the LETD system 900 can be more compact, simpler, and cheaper than other configurations.

[0122] In some embodiments of the above exemplary configurations, the proximal end 202 of the optical fiber 104 may include a subminiature male (SMA) connector, which may be polished or cleaved at an 8 degree angle, such as Fig.10As shown in the figure, the cut at an angle of 8 degrees achieves the steering of the reflected light beam (unwanted reflection caused by the proximal end 202) from the proximal end 202 of the optical fiber 104, which in turn can reduce substantial noise and increase dynamic range. In some embodiments, the optical signal entering the optical detector (e.g., the reflected light beam (reflected light beam 334a)) may include one or more of the following: (a) reflection from the port lens; (b) reflection from the blast shield; (c) reflection from the proximal end 202 of the optical fiber 104; and / or (d) reflection from the distal end 204 of the optical fiber 104.

[0123] 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 more finely angled proximal end 202 of the optical fiber 104 helps reduce unwanted reflections and improve the dynamic range of the signal reflected from the target 102. In some other embodiments, the SMA connector can be polished or cut at a 4 degree angle instead of an 8 degree angle, for example, Fig.11 As shown. In various embodiments, cutting at an angle of 4 degrees (such as instead of 8 degrees (or higher) angle) can improve signal robustness. In some embodiments, the smaller the cutting angle of the SMA connector, the greater signal robustness of the optical fiber 104 can result. In various embodiments, angles from about 2 degrees to about 8 degrees can be utilized. Generally, lower angles are more difficult to implement in optics. In other words, it is difficult to grab it from the main signal. However, light will not enter the optical fiber at higher angles (e.g., 10+ degrees).

[0124] Fig.12 A flow chart showing a method 1200 for estimating the distance between an optical fiber end and a target according to some embodiments of the present disclosure is shown. Method 1200 is described with reference to various configurations of system 100 and the above-mentioned LETD system 106 (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 should be understood that method 1200 can be implemented using a LETD different from that described herein. Embodiments are not limited in this context.

[0125] At block 1202, method 1200 includes irradiating a target with a plurality of lasers of different wavelengths. For example, LETD system 106 may utilize a plurality of laser sources (e.g., laser sources 302a and 302b, laser sources 502a, 502b, and / or 502c, etc.) to irradiate target 102 with a plurality of lasers of different wavelengths via optical fiber 104. In some embodiments, a plurality of lasers of different wavelengths may be provided to optical fiber 104 for irradiating target 102 using one of the configurations discussed above. In various embodiments, the present disclosure may use light having two different wavelengths (e.g., light beams 320a and 320b, light beams 504a, 504b, and / or 504c, etc.), each wavelength having a different water absorption coefficient to ensure robustness for different types of targets 102, target compositions, target colors, target surfaces, etc.

[0126] In some embodiments, two (or more) wavelengths may be selected so that one is a wavelength with a low water absorption coefficient (LO) and the other is a wavelength with a high water absorption coefficient (HI). As an example, the two wavelengths may be 1310nm and 1340nm. However, this example should not be construed as limiting, as different wavelengths with different water absorption coefficients may be used. For example, 1260-1320nm may be used for LO, and 1330-1380nm may be used for HI. More generally, any combination of wavelength water absorption coefficient pairs having a 2:1 (or greater) ratio may be used. In some embodiments, one or more of the following pairs may be used for LO and HI lasers, 1310nm and 1340nm lasers, 1260nm and 1340nm lasers, 1260nm and 1310nm, and 1310nm and 1550nm lasers, respectively. As outlined above, in some embodiments, two laser sources (e.g., 201a and 201b or 201a' and 201b') may be used to emit light of two different wavelengths. In some embodiments, the laser source may be a polarized laser source, a non-polarized laser source, or a combination of a polarized laser source and a non-polarized laser source. As an example, to measure the distance between the distal end 204 of the optical fiber 104 and the target 102, a low-power infrared (IR) laser may be used (but not limited to) to illuminate the target 102 via the optical fiber 104. In other embodiments, lasers other than IR lasers may be used. However, an IR laser may be used because it does not include visible light that may interfere with the user.

[0127] At block 1204, the method 1200 includes receiving a reflected light beam from a target via an optical fiber. For example, the LETD system 106 may receive a reflected light beam 334a or a reflected light beam 514a from the target 102 via the optical fiber 104. In some embodiments, the reflected light beam 334a or the reflected light beam 514a may include a mixture of reflections such as from the proximal end 202 of the optical fiber 104, from the distal end 204 of the optical fiber 104, from the port 314, from a burst shield (not shown), etc. In various embodiments, the LETD system 106 may be configured to identify a reflected light beam suitable for measuring intensity.

[0128] At block 1206, the method 1200 includes measuring the intensity of the reflected beam by detecting the reflected beam using one or more photodetectors, and transmitting an indication (e.g., an electrical signal, etc.) of the reflected beam intensity measured by the one or more photodetectors to a processing unit. For example, the LETD system 106 can measure the intensity of the reflected beam 334a or the reflected beam 514a (also referred to herein as a return signal) by detecting the return signal using one or more photodetectors provided in the LETD 106 system. In some embodiments, since two different wavelengths are used to illuminate the target 102, the measured intensity is about two different wavelengths. Therefore, two measured intensities corresponding to laser sources of two different wavelengths (e.g., laser sources 302a and 302b, etc.) can be transmitted to the processing unit 108 associated with the LETD system 106. In various embodiments, three or more different wavelengths can be utilized, measured and / or transmitted.

[0129] At block 1208, the method 1200 includes receiving, by the processing unit, an indication of the intensity of the reflected light beam measured by the one or more light detectors. For example, the processing unit 108 may receive an electrical signal from the LETD system 106 that includes an indication of the measured intensity of the reflected light beam 334a, etc.

[0130] At block 1210, the method 1200 includes estimating, by the processing unit, the 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 light detectors. For example, 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 of the return signal. In some embodiments, the processing unit 108 can substitute the measured intensity into Formula 1 as follows:

[0131] The strength of the return signal = R*e (-λ*X) :Formula 1

[0132] In the above formula 1, "R" refers to the target reflectance which is affected by target composition, target color / pigment, target angle and target surface, etc.; "λ" refers to the water absorption coefficient at a specific wavelength; and "X" refers to the distance between the distal end 204 of the optical fiber 104 and the target 102.

[0133] In the above formula 1, "X" and "R" are unknown parameters that need to be determined by the processing unit 108. Therefore, in order to determine the values ​​of "X" and "R", the processing unit 108 can substitute the two measured intensity values ​​into the above formula 1, thereby obtaining two formulas with substituted values ​​of the measured intensity and the water absorption coefficient of the corresponding wavelength. For example, the two formulas with substituted values ​​may be as follows.

[0134] I (HI) =R*e (-λ_HI*X) : Formula 1.1

[0135] I (LO) =R*e (-λ_LO*X) : Formula 1.2

[0136] The processing unit 108 can further simplify the above substitution formulas 1.1 and 1.2 as follows: use formula 2.1 to calculate the ratio of the measured intensity values ​​obtained for the return signals of two different wavelengths; and use the natural logarithm to determine the distance value, as shown in formula 2.2.

[0137]

[0138] Therefore, 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 the formulas 1.1 and 1.2 shown above. In the above formula 2.2, "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 two wavelengths, and when the selected wavelengths are close to each other on the "nm scale", R (target reflection) is almost the same for the two wavelengths. In some embodiments, the wavelengths can be considered to be close to each other on the "nm scale" when they are within 250nm (e.g., 1310nm and 1340nm or 1310nm and 1550nm). However, in many embodiments, a wavelength with a closer R value can be selected. Therefore, 1310nm and 1340nm can be selected over 1310nm and 1550nm. Through some examples of the present disclosure, two laser sources (e.g., laser sources 302a and 302b, etc.) can be arranged to emit light with wavelengths within 100nm of each other.

[0139] The condition of the optical fiber 104 may be affected by factors such as changes or degradation of the distal end 204 and / or the proximal end 202 of the optical fiber 104, the effect of fiber bending on polarization scrambling, or any other degradation and changes occurring in the optical fiber 104. Changes in the optical condition of the optical fiber 104, particularly the tip / end of the optical fiber 104, may adversely affect one or more of the quality of the radiation beam, the intensity of the internally reflected beam, the amount of back-reflected light from the target entering the optical fiber, the amount of energy reaching the target, and the accuracy of the measurement. This may affect the accuracy of the distance estimate, possibly resulting in incorrect positioning of the optical fiber 104 during treatment or miscalculation of energy optimization, which is based on distance estimates as described in U.S. Provisional Patent Application No. 63 / 118,117, which is incorporated herein by reference.

[0140] Internal reflections from planes associated with the optical fiber (e.g., the fiber proximal end or the fiber distal end) or from planes associated with other optical elements (e.g., lenses or shields) optically connected to the optical fiber can generate parasitic and unwanted reflections. In addition, these internal reflections may change over time due to degradation of the optical fiber or other elements. In addition, fiber degradation may change the quality of the laser beam radiated toward the target and / or the intensity of back-reflected light from the target tissue, such as reflected light entering and passing through the optical fiber as reflected beams 334a and 334b.

[0141] Therefore, for some embodiments, at block 1210, method 1200 can measure the initial internal reflection of each laser before treatment begins to maintain accurate distance measurement during fiber degradation and internal reflection changes. In many such embodiments, the initial internal reflection value (or base value) can be recorded and used to monitor changes over time. For example, the processing unit 108 can include a circuit (e.g., a register, a memory, etc.) that stores an indication of the initial internal reflection value. In several embodiments, the process can be performed for one or more optical fibers 104 to be used with the laser system. For example, the process can be performed for each optical fiber 104 to be used with the laser system. Various embodiments described herein can monitor changes in the initial internal reflection value (e.g., stored in a circuit of the processing unit 108, etc.) to dynamically correct the distance measurement value as provided herein.

[0142] In some embodiments, the processing unit 108 is configured to read (e.g., from a register, from a memory, etc.) a baseline value of such parasitic (e.g., unwanted) reflections using a system pre-processing calibration process. In some embodiments, the system pre-processing calibration process may include setting up the treatment fiber in water without a target. In this case, "no target" may be interpreted to mean that the nearest target (e.g., a stone, a tumor, etc.) may be located far enough from the tip of the fiber that no light or substantially no light is reflected off the target and reflected back into the fiber 104 as the signal reflection beam 334a. For IR sources (e.g., 1310nm and 1340nm sources), such a distance may be, for example, 20410mm from the distal end of the fiber 104, or greater. However, if visible light (e.g., 400nm-700nm) is used, a length greater than 10mm may be used. Thereafter, under these conditions, the system may activate the laser (e.g., laser sources 302a and 302b, etc.) and measure the reflected signal reflection beam 334a, as described above. Because the reflected light reflected beam 334a under these conditions (e.g., active laser in the presence of water but no target) is very low, the signal reaching the optical detector is primarily related to internal reflections associated with the optical fiber 104 (e.g., from port 314, proximal end 202, distal end 204, etc.).

[0143] In this case, the internally reflected (IR) beam may be detected using a light detector and the measured intensity value may be stored by the processing unit 108 as an IR (HI) and IR (LO) (e.g., in a register, or in a memory circuit, etc.) IR (HI) It can be the internal reflection intensity of the incident light with a higher water absorption coefficient when there is no target near the tip (e.g., distal end 204) of the optical fiber 104, while the IR (LO) The internal reflection intensity of incident light with a low water absorption coefficient may be when there is no target near the optical fiber 104 (e.g., distal end 204). Thereafter, during therapy or treatment, when the laser is activated and the distal end 204 of the optical fiber 104 is placed at a closer distance to the target 102, the reflected light beam 334a may be reflected back through the optical fiber 104 and detected using the light detector described herein.

[0144] In addition to calculating the measured intensity value as described above, the processing unit 108, at block 1210, may store (e.g., in a register, in a memory circuit, etc.) the measured intensity value as an I (HI) , which may be an indication of the strength of the return signal from the target 102 (e.g., tissue, stone, etc.) corresponding to the wavelength with a higher water absorption coefficient (HI), and stores I (LO), which may be an indication of the strength of the return signal corresponding to the wavelength with the lower water absorption coefficient (LO) from the target 102 (e.g., tissue, stone, etc.). However, in order to eliminate the parasitic (or unwanted) reflection value from the reading of the actual reflected light beam 334a, the processing unit 108 may respectively extract the actual return signal I (HI) Subtract and / or reduce IR from the reading (HI) (as shown in the following formula 3.1) and the actual returned signal I (LO) Subtract and / or reduce IR from the reading (LO) , as shown in Formula 3.1 and Formula 3.2 below.

[0145] I' (HI) =I (HI) –IR (HI) : Formula 3.1

[0146] I' (LO) =I (LO) –IR (LO) : Formula 3.2

[0147] In the above formula 3.1, I' (HI) I is the newly calculated intensity of the return signal corresponding to the wavelength with higher water absorption coefficient (HI) (without parasitic (or unwanted) reflections); (HI) refers to the measured intensity of the return signal corresponding to wavelengths with higher water absorption coefficient (HI) (with parasitic (or unwanted) reflections); and IR (HI) Refers to the measured intensity of the internal reflection of incident light with a higher water absorption coefficient (measurement under "no target").

[0148] Similarly, in the above formula 3.2, I' (LO) I is the newly calculated intensity of the return signal corresponding to the wavelength with lower water absorption coefficient (LO) (without parasitic (or unwanted) reflections); (LO) refers to the measured intensity of the return signal corresponding to the wavelength with lower water absorption coefficient (LO) (with parasitic (or unwanted) reflections); and IR (LO) Refers to the measured intensity of the internal reflection of incident light with a lower water absorption coefficient (measurement under "no target").

[0149] Therefore, the new intensity calculation value I' is used (HI) and I' (LO) , the processing unit 107 can be by the new "calibration" value I' (HI) and I' (LO) Substituting into equation 2.2 to determine the distance between the distal end 113 of the optical fiber 103 and the target 101 is as follows:

[0150]

[0151] In some embodiments, the formula of "X" can also be expressed as follows:

[0152]

[0153] As mentioned above, internal reflections may not be constant over time and may vary due to some changes in the internal optical parameters of the system (as opposed to due to dynamic changes in the treatment environment external to the system), such as the optical quality of the distal end 204 of the optical fiber 104. Due to one or more of the power level of the treatment beam 326, the cavitation effect occurring at the distal end 204 (or tip) of the optical fiber 104, and the liquid environment in which the optical fiber is disposed during treatment, the optical fiber experiences various amounts of degradation, primarily at the distal end 204 (or tip). Therefore, in several embodiments, a "real-time" or "dynamic" calibration can be performed by repeatedly monitoring the reflected beam 334a during treatment and dynamically accounting for or adjusting for changes in such internal reflections. For example, to perform such real-time calibration, as shown in the configurations described herein, the use of a calibration laser (e.g., laser source 302c, etc.) can be used to facilitate a more accurate distance estimate that accounts for such degradation of the optical fiber 104.

[0154] As explained with respect to these configurations, the calibration laser beam (e.g., beam 320c, etc.) has a wavelength that has a very high absorption coefficient in water. As an example, the wavelength of the polarized laser source 302c or the non-polarized laser source 502c can be 1435nm. Since the laser beams generated by these "calibration" laser sources are so strongly absorbed by the liquid environment, as explained above, there is almost no reflected light beam 334a associated with these laser beams returned to the optical fiber. Therefore, when the calibration laser source is activated, the reflected signal 334a having the wavelength of the calibration laser source is mainly associated with (or indicates) internal reflections.

[0155] In several embodiments, the processing unit 108 at block 1210 may be configured to read and store one or more base values ​​of internal reflections of the system 100 associated with a laser source (laser source 302c) (or the like) before treatment begins. These one or more base 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, in a memory circuit, etc.). In addition, the processing unit 108 may be configured to continue to measure the internal reflections of the light emitted by the calibration laser source (e.g., laser source 302c) in "real time" (e.g., periodically, repeatedly, etc.) during treatment to identify deviations from the base values. Monitoring these deviations provides an indication of degradation of the optical quality of the optical fiber 104, and may be used to correct any measured back reflection intensity associated with the reflected beam 334a. In many embodiments, based on the readings of the internal reflections of the light emitted by the calibration laser source, the processing unit 108 may correct the calibration parameters of the primary laser sources (e.g., laser sources 302a and 302b, etc.).

[0156] In some embodiments, the method 1200 may include blocks 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 a calibration laser source, wherein the system 100 is activated in water. Because the calibration laser source is highly absorbed in water, the sensitivity to the distance to the target 102 during the calibration reading of the calibration laser source may be much lower relative to the measured values ​​of the reflection signal associated with light emitted by other laser sources. As will be explained in more detail below, this may provide for continued calibration laser measurements during treatment when the target may also be close to the fiber tip.

[0157] Thereafter, the target 102 may be illuminated with a non-calibrated laser source using one of the exemplary configurations. In this case, the reflected light beam 334a and the reflected light beam 334b ​​may be detected using a light detector, and the processing unit 108 may store the measured intensity values ​​as I (HI) ,I (LO) and additional and related measurements of the internal reflection of the calibration laser IR (CAL) I (HI) It can be the back reflection intensity from the target with higher water absorption coefficient of the incident light, I (LO) can be the back reflection intensity from the target with lower water absorption coefficient of the incident light, and IR (CAL) It can be the internal reflection intensity of the incident light from the calibration laser source.

[0158] In some embodiments, the presence or absence of target 102 may not affect the reflected IR (CAL), because the incident light from the collimated laser source is highly absorbed by water. As a result, the IR (CAL) The change in value may be the result of degradation of the optical fiber 104, particularly the tip (e.g., distal end 204, etc.) of the optical fiber 104. In some embodiments, based on IR (CAL) The processing unit 108 may adjust the previously measured IR (HI) and IR (LO) value or the currently measured I (LO) or I (HI) .

[0159] 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 at a close enough distance to generate the 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 502a and the laser source 502a or 502b and the light reflection 610 from the calibration laser source 302c or 502c can be detected using the light detector. At block 1210, the processing unit 108 can store the measured intensity value as I (HI) , which can represent the intensity of the return signal corresponding to its wavelength with a higher water absorption coefficient (HI), I (LO) , which may represent the intensity of the return signal corresponding to its wavelength having a lower water absorption coefficient (LO), and IR (CAL) , which may represent the intensity of the returned internal reflection signal corresponding to light having a higher static water absorption coefficient at its wavelength (e.g., light emitted by calibration laser source 302c or 502c). In addition, to determine the calibration factor, processing unit 108 may include the IR signal from the calibration process preprocessing (CAL-PRE) The IR (CAL-DUR) Divide, as shown in Formula 4 below.

[0160]

[0161] When the internal reflection of the calibration laser source is the same before and during treatment, and there is no change in the optical fiber 104, the calibration factor may be "1". In addition, in order to correct the parameters of the main laser sources 302a and 302b or the laser sources 502a and 502b based on the calibration factor, the processing unit 108 may use the calibration factor as shown in the following formulas 5.1 and 5.2.

[0162] I” (HI) =I (HI) –IR (HI) x CF: Formula 5.1

[0163] I”(LO) =I (LO) –IR (LO) x CF: Formula 5.2

[0164] In the above formula 5.1, I” (HI) I refers to the new calibration intensity of the back reflection signal from the target 102, corresponding to the light with a wavelength having a higher water absorption coefficient (HI); (HI) IR refers to the measured intensity of the back-reflected signal from the target 102, corresponding to light having a wavelength with a higher water absorption coefficient (HI); (HI) refers to the measured intensity of the internal reflection of the incident laser light having a wavelength with a higher water absorption coefficient (measurement “without target”); and CF refers to the calibration factor determined using Equation 4.

[0165] In the above formula 5.2, I” (LO) I is the new calibrated intensity of the back-reflected signal from the target, corresponding to light with a wavelength having a lower water absorption coefficient (LO); (LO) Refers to the measured intensity of the back-reflected signal from the target, corresponding to the light with the wavelength with the lower water absorption coefficient (LO); IR (LO) refers to the measured intensity of the internal reflection of the incident laser light having a wavelength with a lower water absorption coefficient (measurement “without target”); and CF refers to the calibration factor determined using Equation 4.

[0166] Therefore, a new calibration intensity value I" is used (HI) and I" (LO) , the processing unit 108 at block 1210 may be configured to obtain a new calibration value I" (HI) or I” (LO) Substituting into equation 2.2 to determine the distance between the distal end 204 of the optical fiber 104 and the target 102 is as follows:

[0167]

[0168] Thus, in this manner, system pre-processing calibration and real-time calibration may be performed and utilized to update calibration factors in real-time (e.g., via processing unit 108) to dynamically account for changes (e.g., degradation, etc.) to the optical fiber 104 during operation. In several embodiments, pre-processing and real-time calibration may be performed to ensure the accuracy of the estimated distance between the distal end 204 of the optical fiber 104 and the target 102 when the optical fiber 104 experiences degradation.

[0169] At block 1212, the method 1200 includes indicating, by the processing unit 108, via an indicator, an estimated (e.g., at block 1210) distance between the distal end 204 of the optical fiber 104 and the target 102. For example, the processing unit 108 causes the estimated distance between the distal end 204 of the optical fiber 104 and the target 102 to be indicated via an indicator 110 associated with the processing unit 108. As a specific example, the indicator 110 may include one or more of a visual indicator, an audio 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 to indicate (e.g., display, audibly signal, tactilely signal, etc.) an indication of the estimated distance.

[0170] In some embodiments, based on the 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, the characteristics of the therapeutic beam, etc. can be changed in real time to accurately and efficiently affect the therapeutic beam on the target 102, such as through more precise aiming.

[0171] Fig.13 A flow chart showing a method 1300 for estimating the distance between an optical fiber end and a target according to some embodiments of the present disclosure is shown. The method 1300 is described with reference to the various configurations of the system 100 and the LETD system 106 described above. However, it should be understood that the method 1300 can be implemented using a different LETD system than described herein. The embodiments are not limited in this context.

[0172] At block 1302, the method 1300 includes determining a first intensity value based on first reflected laser light corresponding to laser light at a first wavelength, wherein the laser light at the first wavelength exits the distal end 204 of the optical fiber 104, and the first reflected laser light is reflected by the target 102 and enters 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 high water absorption coefficient at its wavelength. In some embodiments, as discussed above, the laser light corresponding to the wavelength having a high water absorption coefficient may be generated by the laser source 302a or 502a.

[0173] At block 1304, the method 1300 includes determining a second intensity value based on second reflected laser light corresponding to laser light of a second wavelength, wherein the laser light of the second wavelength exits the distal end 204 of the optical fiber 104, and the second reflected laser light is reflected by the target 102 and enters the distal end 204 of the optical fiber 104. For example, at block 1304, the processing unit 108 may determine the second intensity value based on the reflected light beam 334a corresponding to light having a low water absorption coefficient at its wavelength. In some embodiments, as discussed above, the laser light corresponding to the wavelength having a low water absorption coefficient may be generated by the laser source 302b or 502b.

[0174] At block 1306, the method 1300 includes calculating a ratio of the first intensity value and the second intensity value. For example, at block 1306, the processing unit 108 may calculate the ratio of the first intensity value and the second intensity value using Formula 2.1. 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 of the first intensity value and the second intensity value derived at block 1306. For example, at block 1308, 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 ratio of the first intensity value and the second intensity value using Formula 2.2.

[0175] Fig.14 A flow chart showing a method 1400 for estimating the distance between an optical fiber end and a target according to some embodiments of the present disclosure is shown. The method 1400 is described with reference to various configurations of the system 100 and the LETD system 106 described above. However, it should be understood that the method 1400 can be implemented using a LETD system different from that described herein. The embodiments are not limited in this context.

[0176] At block 1402, method 1400 includes irradiating a target with a plurality of laser beams of different wavelengths. For example, one of the configurations described above may be used to irradiate target 102 with beams 332 having a plurality of different wavelengths. For example, beams 332 may include beams 320a, 320b, 320c, therapy beams 326, and / or 328 (etc.).

[0177] At block 1404, method 1400 includes receiving a reflected light beam from the target via the optical fiber. For example, one of the configurations discussed herein may be used to receive a reflected light beam 334a (e.g., corresponding to light reflected from target 102) and transmitted back via optical fiber 104. In several embodiments, reflected light beam 334a may be reflected from target 102 and enter distal end 204 of optical fiber 104, and thus may include reflected light beam 334a. Reflected light beam 334a may also include light reflected from optical components within the system (e.g., proximal end 202, distal end 204, etc.), and may include light reflection 610 corresponding to reflected light associated with calibration beam 320c.

[0178] At block 1406, method 1400 includes measuring the intensity of reflected light beam 334a with one or more light detectors. In many embodiments, the intensity of reflected light beam 334a can be measured with one or more light detectors using one of the configurations discussed herein. For example, light detectors (light detectors 318a and 318b) can be used to measure the intensity of reflected light beam 334b. In another example, other light detectors (e.g., light detector 512, etc.) can be used to measure the intensity of reflected light beam 334a.

[0179] At block 1408, the method 1400 includes estimating the distance between the distal end 204 of the optical fiber 104 and the target 102 based on the intensity of the reflected light beam 334a measured with the one or more light detectors. For example, the processing unit 108 can be used to estimate the distance between the distal end 204 of the optical fiber 104 and the target 102 based on the intensity of the reflected light beam 334a measured with the one or more light detectors.

[0180] It should be understood 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, their optical properties may change during surgery, for example, due to thermal and environmental changes, mechanical vibrations, exposure to therapeutic laser beams (e.g., high-power laser beams), or other reasons. When the optical components change, the system (e.g., processing unit 108, etc.) cannot correctly distinguish between changes in the distance between the distal end 204 of the optical fiber 104 and the target 102 or changes in the optical components. Therefore, the present disclosure provides for capturing or "snatching" light reflected from the proximal end 202 of the optical fiber 104 to be used as a reference or calibration light for the optical components, so that even when the optical components change over time, the distance between the distal end 204 of the optical fiber 104 and the target 102 can be accurately determined.

[0181] It should be understood that the reflected beam 334a has an angle of incidence different from zero, so that the light reflected by 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 an LETD system configuration with a mirror to direct light out of the optical path and into a polarizing beam splitter with two detectors. Analysis of the signals of these detectors gives a measure of the change in the system compared to the initial state.

[0182] In some embodiments, in each of the exemplary configurations described herein, the proximal end of the optical fiber 104 may be coated with a special coating, such as an anti-reflection (AR) coating. The AR coating may help reduce the noise generated at the proximal end 202 of the optical fiber 104 and increase the dynamic range. In some embodiments, the optical signal entering the optical detector may include one or more of the following: (a) reflection from the port lens; (b) reflection from the explosion-proof shield; (c) reflection from the proximal end 202 of the optical fiber 104; and / or (d) reflection from the distal end 204 of the optical fiber 104.

[0183] In various embodiments, the AR coating for the explosion-proof shield can reduce the reflection from the port lens to less than 1%, the AR coating for the port lens can reduce the reflection from the explosion-proof shield to less than 1%, and the AR coating at the proximal end 202 of the optical fiber 104 can reduce the reflection from the proximal end 202 of the optical fiber 104 from 3.5% to about 0.5%. In some embodiments, the reflected signal from the target 102 such as a stone can have very low energy, for example, close to 1% of the optical fiber output power, where the distance from the optical fiber tip to the tissue is about 0 mm. By reducing the reflection from the proximal end 202 of the optical fiber 104 to close to 0.5%, the present disclosure can help improve the dynamic range of the signal reflected from the target 102.

[0184] Fig.15LETD system 1500 is shown, which is similar to LETD system 900, but has additional "light grabbing" components described herein. For example, LETD system 1500 includes laser sources 502a, 502b, 502c and laser source 702, as well as WDM 704, beam splitter 902, photodetector 512, power detector 306 and beam combiner 310. LETD system 1500 also includes reflector 1502, polarization beam splitter 1504 and photodetector 1506a. During operation, reflector 1502 can guide light reflection from the light path of reflected light beam 334a toward polarization beam splitter 1504. In other words, reflector 1502 is arranged to redirect light reflection 1510 away from the light path of reflected light beam 334a so that 1510 does not reach the original optical detector (e.g., photodetector 512). Note that this figure does not depict the incident angles of the various light beams. However, it should be understood that the angle of the light beam is not always incident on the various optical components at 90 degrees as shown. For example, light reflection 1510 can have an incident angle of 4 degrees (etc.). In addition, although reflector 1502 is depicted in the light path of light reflection 1510 between beam combiner 310 and beam splitter 902, reflector 1502 can instead be disposed in the light path between ports 314 and 310. In addition, for some examples, reflector 1502 can be disposed and arranged so as not to block light beam 806, but rather to redirect light reflection 1510 as depicted and described.

[0185] As will be appreciated, because light reflection 1510 is linearly polarized, it maintains its polarization after reflecting off the proximal end 202 of optical fiber 104. Light reflection 1510 is directed via mirror 1502 to polarizing beam splitter 1504, where it is split into two component beams having polarizations parallel to the light incident on the proximal end 202 of optical fiber 104 and perpendicular to the polarization of the light incident on the proximal end 202 of optical fiber 104.

[0186] LETD system 1500 also includes light detectors 1506a and 1506b, which are arranged to measure the intensity of light reflection 1510 separated by polarization beam splitter 1504. In particular, light detectors 1506a and 1506b are arranged to measure the intensity of light based on polarization as outlined herein. However, it is worth noting that the parallel component of light reflection 1510 will include some parts of light reflection 1510 and light reflection 610, while the perpendicular component in light reflection 1510 will only include some parts on light reflection 610.

[0187] For some embodiments, the distance between distal end 204 of optical fiber 104 and target 102 may be represented by Equation 6.1 shown below.

[0188]

[0189] Taking into account the fact that each laser source fires with different illumination pulses and energies, the intensity can be normalized using Equation 6.2, where I refHI is the reference power intensity of the high water absorption coefficient light source detector 306, I refLO is the reference power intensity of the low water absorption coefficient light source detector 306, and I normHI and I normLo is the normalized intensity.

[0190]

[0191] The “pure” reflection signal can be expressed by Equation 6.3, where I DETλ is the reading from the detector for wavelength λ, I distλ is the reading of the reflection from the distal end 204 of the optical fiber 104 for the wavelength λ, I lensλ is the reading of the reflection from the focusing lens 1514 of the optical fiber 104 for the wavelength λ, and I sigλ is the isolated signal for wavelength λ (eg, a "grabbed" optical signal as described herein). Note that equation 6.3 assumes that reflections from the near end of the fiber are eliminated (eg, reduced to zero) in the optical path and that reflections from explosion proof shield 1512 are also eliminated.

[0192] I DETλ =I sigλ +I distλ +I lensλ : Formula 6.3

[0193] The LETD system 1500 can be arranged to calibrate the optical system by deriving: It is the reflectivity calibration of wavelength λ from focusing lens 1514; which is the detector reading at ∞ in wavelength λ, and is or the reflection from the far end 204 of the optical fiber 104 at ∞ in wavelength λ and the above defined It should be understood that calibration is not a function or time (or more precisely, constant over the process).

[0194] Isolating the signal from the detector in equation 6.3 above results in Pick This value can be calculated using a specific wavelength as a function of time. Using 1435 nm as a specific example yields the following equation 6.4, which is a correction for distal tip reflection.

[0195]

[0196] During operation, a signal is acquired from the detector, which yields Equation 6.5, which is a correction for the distal tip reflection from the actual detector.

[0197]

[0198] Substituting the above into Equation 6.5 yields Equation 6.6, which is the signal value extracted from the signal detector (eg, a constant static reflection).

[0199]

[0200] As will be appreciated, the addition of transmittance will change the optical path. In particular, several optical components may experience changes in their transmittance and / or reflectance values. For example, a focusing lens (transmittance referenced as ), explosion-proof shielding (transmittance ratio is quoted as ) and optical fiber 104 (transmittance is quoted as ) may undergo changes over time. That is, the signals susceptible to these transmittances are and Therefore, the final formula for a signal with non-stationary reflections can be defined using Equation 6.7.

[0201]

[0202] Note that the detector value is measured as a whole, without the option to distinguish different factors from the detector. However, Equation 6.8 shown below details the transmittance as a function where the lens, explosion shield and fiber are constants and can be taken into account, which can be done just like the normalized signal above.

[0203]

[0204] It is equal to

[0205]

[0206] However, by applying the correction to the lens together with the distal end 204 without separate lens reflection, Equation 6.6 can be reduced as shown in Equation 6.9 below.

[0207]

[0208] It will be appreciated that the component for the lens reflectivity is missing from Equation 6.9 (e.g., ). We can further reduce the formula by completely neglecting the presence of the lens, yielding Equation 6.10.

[0209]

[0210] Combining the above formulas, we can define distance as a function of brightness and reflectivity, as shown in Formula 6.11.

[0211]

[0212] As outlined above, Fig.15 The configuration shown, or more specifically the LETD system 1500, is arranged to "grab" light reflected from the proximal end 202 of the optical fiber 104 to calibrate the optical components of the system (e.g., focusing lens 1514, explosion-proof shield 1512, etc.). In general, the light reflection 1510 can be expressed by the equation 6.12 shown below, where f λ Isig is the factor of the signal going out in the light grabbing direction. λ is the signal defined in the following formula:

[0213]

[0214] Equation 6.12 can be rewritten in polarized form as shown in Equation 6.13, where - is the mixed polarization value, is the forward source polarization value, and Perpendicular to the source polarization value.

[0215]

[0216] For a distance at ∞, this formula is reduced to Equation 6.14.

[0217]

[0218] According to the above formula, use The value of can be extracted from the calibration signal. Thus, in the "captured" optical signal (e.g., optical reflection 1510), the near end 202 reflection is therefore is also calibrated. As a result, Any change in the value of per wavelength can be converted into Equation 6.7. The value of will be accordingly, So the square root The changes in will also compensate for these movements.

[0219] Will understand, calibrate from the process and at ∞ it will be favorable.

[0220] Furthermore, in the case of using polarized light, the noise in the polarization switch (eg, WDM 704, etc.) can be described using equation 6.15.

[0221]

[0222] Fig.16 A flow chart illustrating a method 1600 of estimating the distance between an optical fiber end and a target according to some embodiments of the present disclosure is shown. Fig.15 The method 1600 is described with reference to the configuration of the LETD system 106 or more specifically, the LETD system 1500. However, it should be understood that the method 1600 may be implemented using a different LETD system than that described herein. The embodiments are not limited in this context.

[0223] At block 1602, the reflector 1502 directs a portion of the light reflected from the proximal end 202 of the optical fiber 104 to the polarization beam splitter 1504 and the optical detectors 1506a and 1506b. That is, the reflector 1502 is arranged to direct a portion of the light reflection 1510 to the polarization beam splitter 1504. Continuing to block 1604, the method 1600 can detect the intensity of the polarization component of the portion of the light directed to the detector. In particular, the light reflection 1510 is split into polarization components by the polarization beam splitter 1504, and the optical detectors 1506a and 1506b can detect the intensity of the components of the light reflection 1510.

[0224] At block 1606, method 1600 may determine a transmission function of the optical system based at least in part on the intensity detected at block 1604. For example, processing unit 108 may execute instructions to determine the transmission of the optical system as outlined above with equations 6.1 through 6.17.

[0225] Fig.17 1700 is shown, which is similar to LETD system 1500, but has a single 1706 and polarizer 1708 instead of polarizing beam splitter 1504 and photodetectors 1506a and 1506b. In addition, it is noted that LETD system 1700 can be implemented in which laser sources 1702a, 1702b and 1702c are arranged to emit unpolarized light beams 1704a, 1704b and 1704c, respectively. Processing unit 108 can be arranged to take into account changes in optical components over time, as described above with respect to Fig.15 and Fig.16 As mentioned, note that the formula for the transmission function will not depend on the polarization as outlined above.

[0226] Fig.18A computer-readable storage medium 1800 is shown. The computer-readable storage medium 1800 may include any non-transitory computer-readable storage medium 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 a circuit (e.g., a processing unit 108, etc.) may use to execute. For example, the computer-executable instructions 1802 may include instructions for implementing the operations described with respect to the method 1200, the method 1300, the method 1400, and / or the method 1600. Examples of computer-readable storage medium 1800 or machine-readable storage medium 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, writable or rewritable memory, and the like. 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.

[0227] Fig.19 1 is a block diagram of a computing environment 1900 including a computer system 1902 for implementing embodiments consistent with the present disclosure. In some embodiments, the computing environment 1900 or a portion thereof (e.g., the computer system 1902) may include or be included in a laser system (e.g., the system 100, the LETD system 106, etc.). Thus, in various embodiments, the computer system 1902 may be used to determine the distance between the distal end 204 of the optical fiber 104 and the target 102, and account for changes in the optical system over time, as outlined above.

[0228] 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 or system generated processes. The user may include a person, a person using a device such as those included in the present disclosure, or another device. The processor 1904 may include a special processing unit such as 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, etc. The processor 1904 may be configured to communicate with an input device 1914 and an output device 1916 via an I / O interface 1912. The I / O interface 1912 may employ 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 video 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), WiMAX, etc.), etc.

[0229] 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 configured to communicate with a communication network 1920 via a network interface 1910. In various embodiments, the communication network 1920 can be used to communicate with a remote memory storage device 1906, such as for accessing a lookup table, performing updates, or utilizing external resources. The network interface 1910 can communicate with the communication network 1920. The network interface 1910 can employ a connection protocol 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, etc.

[0230] The communication network 1920 may be implemented as one of different types of networks, such as an intranet or local area network (LAN), a closed area network (CAN), etc. The communication network 826 may be a dedicated network or a shared network, which represents an association of different types of networks that communicate with each other using a variety of protocols (e.g., Hypertext Transfer Protocol (HTTP), CAN protocol, Transmission Control Protocol / Internet Protocol (TCP / IP), Wireless Application Protocol (WAP), etc.). In addition, the communication network 1920 may include various network devices, including routers, bridges, servers, computing devices, storage devices, etc. In some embodiments, the processor 1904 may be configured to communicate with the memory storage device 1906 via a storage interface 1908. The storage interface 1908 may be connected to the memory storage device 1906, including but not limited to a memory drive, a removable disk drive, etc., using a connection protocol such as Serial Advanced Technology Attachment (SATA), Integrated Drive Electronics (IDE), IEEE-1394, Universal Serial Bus (USB), Fiber Channel, Small Computer System Interface (SCSI), etc. The memory drives may also include magnetic drums, magnetic disk drives, magneto-optical drives, optical drives, redundant arrays of independent disks (RAID), solid-state storage devices, solid-state drives, and the like.

[0231] In addition, the memory storage device 1906 may include one or more computer-readable storage media used in implementing embodiments consistent with the present disclosure. Generally, a computer-readable storage medium refers to any type of physical memory that can store information or data that is readable by a processor. Therefore, a computer-readable storage medium can 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 does not include carrier waves and transient signals, i.e., non-transient. Examples include random access memory (RAM), read-only memory (ROM), volatile memory, non-volatile memory, hard disk drive, compact disk (CD) ROM, digital video disk (DVD), flash drive, disk, and any other known physical storage medium.

[0232] 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, UNIX-like distributions (for example, BERKELEYSOFTWARE (BSD), OPENBSD, etc.), DISTRIBUTIONS (e.g., RED wait), ( / 7 / 8, 10, etc.), GOOGLE TM ANDROID TM , OS, etc.

[0233] Application instructions 1924 may include instructions that, when executed by processor 1904, cause processor 1904 to perform one or more techniques, steps, processes, and / or methods described herein, such that the site is irrigated and the site is irradiated as outlined herein. For example, application instructions 1924, when executed by processor 1904, may cause processor 1904 to perform method 1200, method 1300, method 1400, and / or method 1600.

[0234] User interface elements 1926 may facilitate the display, execution, interaction, manipulation, or operation of program components through textual or graphical facilities. For example, a user interface may provide computer interaction interface elements such as cursors, icons, check boxes, menus, scroll bars, windows, widgets, etc. on a display system operably connected to computer system 1902. User interface elements 1926 may be used by application instructions 1924 and / or operating system 1922 to provide, for example, a user interface through which a user may interact with computer system 1902. In some embodiments, user interface elements 1926 may be integrated with a display (not shown).

[0235] Terms used herein should be given their ordinary meaning in the relevant art or the meaning indicated by their usage in context, but if an explicit definition is provided, that meaning controls.

[0236] In this document, references to "one embodiment" or "an embodiment" do not necessarily refer to the same embodiment, although they may. Unless the context clearly requires otherwise, throughout the description and claims, the words "comprise", "comprising", etc. should be interpreted in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to". Words using the singular or plural also include the plural or singular, respectively, unless expressly limited to a single one or more. In addition, the words "herein", "above", "below" and words of similar meaning, when used in this application, refer to this application as a whole, and not to any particular part of this application. When the claims use the word "or" when referring to a list of two or more items, the word covers all the following interpretations of the word: any item in the list, all items in the list, and any combination of items in the list, unless expressly limited to one or the other. Any terms not expressly defined herein have their conventional meaning as commonly understood by those skilled in the relevant art.

Claims

1. A system comprising: a first laser source for generating laser light of a first wavelength; a second laser source for generating laser light of a second wavelength; an optical fiber having a distal end and a proximal end, the optical fiber being configured to receive laser light from a first laser source and a 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 out of the distal end, and receive reflected laser light into the distal end; a first light detector for measuring the intensity of the reflected light; a second light detector; a reflector for directing the portion of the laser light reflected from the proximal end to the second light detector, the second light detector measuring the intensity of the portion of the laser light reflected from the proximal end; as well as a processor and a memory including instructions that, when executed by the processor, cause the processor to estimate a distance between a distal end of the optical fiber and a target based on an intensity of reflected light measured by the first light detector and an intensity of the portion of laser light reflected from the proximal end measured by the second light detector.

2. The system according to claim 1, wherein: A first water absorption coefficient of the first wavelength is higher than a second water absorption coefficient of the second wavelength.

3. The system according to claim 2, wherein: A ratio of the first water absorption coefficient to the second water absorption coefficient is at least 2 to 1.

4. The system according to claim 3, wherein: The first wavelength is about 1330 nm to about 1380 nm.

5. A system according to claim 3 or claim 4, wherein: The second wavelength is about 1260 nm to about 1320 nm.

6. The system according to claim 4, comprising: A third laser source for generating laser light of a third wavelength is used to characterize the state of the optical fiber, wherein the third wavelength has a third water absorption coefficient higher than the first and second water absorption coefficients.

7. The system according to claim 5, wherein: The third wavelength includes a wavelength of approximately 1435 nm, approximately 2100 nm, or between approximately 1870 nm and approximately 2050 nm.

8. The system according to any one of claims 1 to 6, wherein: The photodetector measures a first intensity value of reflected light corresponding to the laser light of the first wavelength and a second intensity value of reflected light corresponding to the laser light of the second wavelength.

9. The system according to claim 7, wherein: When the instructions are executed by the processor, the processor further causes: calculating a ratio of the first intensity value to the second intensity value; and A distance between a distal end of the optical fiber and the target is estimated based on a ratio of the first intensity value and the second intensity value.

10. The system according to any one of claims 1 to 8, wherein: One or more of the first laser source and the second laser source include a polarization-maintaining pigtailed fiber laser, a single-mode pigtailed fiber laser, or a free-space laser.

11. The system according to any one of claims 1 to 9, comprising: A wavelength division multiplexer (WDM) coupled to the proximal end of the optical fiber arranges the laser light of the first wavelength and the laser light of the second wavelength to enter the proximal end of the optical fiber at one or more of a same point and a same angle.

12. A method comprising: Illuminating a target with multiple lasers of different wavelengths; receiving a first reflected light beam from the target via an optical fiber; receiving a second reflected light beam from the proximal end of the optical fiber; measuring the intensity of the first reflected light beam and the second reflected light beam with a plurality of light detectors; and The distance between the distal end of the optical fiber and the target is estimated based on the intensity of the reflected light beam measured by one or more light detectors.

13. The method according to claim 12, comprising: A plurality of lasers of different wavelengths are emitted through the optical fiber to illuminate the target.

14. The method according to any one of claims 12 to 13, comprising: A first intensity value of a reflected light beam corresponding to the laser light of the first wavelength and a second intensity value of a reflected light beam corresponding to the laser light of the second wavelength are measured.

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

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