CN116457627A - Method and system for estimating the distance between the end of an optical fiber and a target - Google Patents

Abstract

The present disclosure relates to the field of fiber optic feedback (FFB) technology and provides a method and system for estimating the distance between an end of an optical fiber and a target. The method includes illuminating a target with laser light of different wavelengths having low and high absorption coefficients by a light emission, transmission and detection (LETD) system using different laser light sources, and receiving return signals corresponding to the incident laser light of the different wavelengths and detecting the return signals 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 end of the optical fiber and the target. The present disclosure enables accurate estimation of the distance between the fiber tip and the target. The present disclosure also provides a robust distance estimation technique compatible with different types of targets.

Description

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

Cross References to Related Applications

This application claims the benefit of priority under 35 U.S.C. §119 to U.S. Provisional Application No. 63/118,857, filed November 27, 2020, entitled "Method and System for Estimating Distance Between a Fiber End and a Target," in its entirety Incorporated herein by reference.

This application claims priority benefit under 35 U.S.C. §119 to U.S. Provisional Patent Application No. 63/118,117, filed November 25, 2020, entitled "Apparatus and Method for Enhancing Laser Beam Efficacy in a Liquid Medium," in its entirety Incorporated herein by reference.

This application claims priority benefit under 35 U.S.C. §119 to U.S. Provisional Patent Application No. 63/252,830, filed October 6, 2021, entitled "Method and System for Estimating Distance Between a Fiber End and a Target," the entirety of which The contents are incorporated herein by reference.

technical field

The present disclosure relates generally to the field of optical fibers for medical or therapeutic laser delivery. In particular, but not exclusively, the present disclosure relates to methods and systems for estimating the distance between the end of an optical fiber and a target.

Background technique

The introduction of lasers into medicine and the development of fiber optic technology using lasers has opened up many applications in therapy, diagnosis, therapy, and more. Such applications range from invasive and non-invasive treatments to endoscopic surgery and image diagnostics. For example, in urolithiasis treatment, the stone needs to be broken into smaller pieces. A technique called laser lithotripsy may be used for this fragmentation procedure, in which, for small to medium uroliths, a rigid or flexible ureteroscope is placed through the urinary tract for illumination and imaging. At the same time, an optical fiber is inserted through the working channel of the ureteroscope to the target site (for example, where a stone is present in the bladder, ureter, or kidney). The laser is then activated, breaking the stone into smaller pieces or dusting it. In another instance, laser and fiber optic technologies are used for coagulation or ablation therapy. During ablation therapy, laser light is delivered to tissue to vaporize the tissue. During coagulation therapy, a laser is used to cause thermal damage within the tissue. Such 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 heart disease.

These treatments using laser and fiber optic technology require high precision to ensure that the laser is aimed at the correct target (stone, tissue, tumor, etc.) to achieve clinical 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 of the fiber (distal end) where the laser is emitted, since laser treatment parameters such as energy, pulse width, laser power modulation and/or repetition rate are often based on the distance from the fiber tip to The distance between the targets is determined.

One of the existing techniques for estimating the distance between the far end of an optical fiber and a target provides for measuring and comparing reflected intensity values of a beam transmitted through the optical fiber by modulating the numerical aperture of the beam. However, changing the numerical aperture of the beam is not always convenient. Furthermore, the separation of beam reflections of different numerical apertures required by these techniques is difficult.

Contents of the invention

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 be an aid in determining the scope of the claimed subject matter.

In one aspect, the present disclosure relates to a system comprising: a first laser source and a second laser source, an optical fiber, a photodetector, a processor, and a memory. The first laser source may generate laser light at a first wavelength, and the second laser source may generate laser light at a second wavelength. The optical fiber may have a distal end and be configured to transmit laser light from the first laser source and the second laser source out of the distal end and receive reflected laser light into the distal end. A photodetector measures the intensity of the reflected light. The processor and memory may include instructions that, when executed by the processor, cause the processor to estimate the distance between the distal end of the optical fiber and the target based on the intensity of reflected light measured by the light detector.

In some embodiments, the first coefficient of water absorption at the first wavelength is higher than the second coefficient of water absorption at the second wavelength. In some such embodiments, the ratio of the first coefficient of water absorption to the second coefficient of water absorption is at least 2 to 1. In a further such embodiment, the first wavelength is from about 1330 nm to about 1380 nm, and the second wavelength is from about 1260 nm to about 1320 nm. Still further embodiments include a third laser source generating laser light at a third wavelength for characterizing the 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. In yet another embodiment, the third wavelength includes a wavelength of about 1435 nm, about 2100 nm, or between about 1870 nm and about 2050 nm.

In some embodiments, the photodetector 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. In some such embodiments, the instructions, when executed by the processor, further cause the processor to: calculate the ratio of the first intensity value to the second intensity value; and estimate the fiber optic fiber based on the ratio of the first intensity value to the second intensity value The distance between the far end and the target.

In various embodiments, one or more of the first laser source and the second laser source includes a polarization maintaining pigtailed fiber laser, a single mode pigtailed fiber laser Or free-space lasers.

Several embodiments include a wavelength division multiplexer (WDM) coupled to the proximal end of the fiber, the WDM arranging the laser light at the first wavelength and the laser light at the second wavelength to enter the fiber at one or more of the same point and at the same angle near end.

In another aspect, the present disclosure relates to at least one non-transitory computer-readable medium comprising a set of instructions that, in response to being executed by a processor circuit, cause the processor circuit to perform one or more of the following: based on A first intensity value is determined for a first reflected laser light corresponding to a first wavelength of laser light, wherein the first wavelength of laser light exits the distal end of the optical fiber, and the first reflected laser light is reflected by the target and enters the distal end of the optical fiber; The second reflected laser corresponding to the laser to determine the second intensity value, wherein the second wavelength laser leaves the far end of the fiber, and the second reflected laser is reflected by the target and enters the far end of the fiber; calculate the first intensity value and the second intensity values; and estimating the 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.

In some embodiments, 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 the first intensity value, and determine the first intensity value from the second measured intensity value value to determine the second intensity value by subtracting the second internal reflection value.

In various embodiments, the set of instructions, in response to being executed by the processor circuit, further causes the processor circuit to determine an internal reflection value based on a third reflected laser light corresponding to a third wavelength of laser light that exits the laser light source, and at least a portion of the third reflected laser light is reflected by the distal end of the optical fiber. In various such embodiments, the set of instructions, in response to being executed by the processor circuit, further causes the processor circuit to compare the internal reflection value to a baseline internal reflection value; and to determine based on the comparison of the internal reflection value to the baseline internal reflection value Adjust the operating parameters of the treatment beam. In a further such embodiment, the set of instructions, in response to being executed by the processor circuit, further causes the processor circuit to compare the internal reflection value to a baseline internal reflection value; characterize based on the comparison of the internal reflection value to the baseline internal reflection value the status of the fiber; and communicating an indication of the status of the fiber via the user interface.

In some embodiments, the set of instructions is responsive to execution by the processor circuit, further causing the processor circuit to communicate an indication of the estimated distance between the distal end of the optical fiber and the target via the user interface.

In yet another aspect, the present disclosure may include a method comprising one or more of: illuminating a target with a plurality of laser light of different wavelengths; receiving a reflected beam from the target via an optical fiber; measuring the reflection with one or more photodetectors the intensity of the beam; and estimating the distance between the distal end of the optical fiber and the target based on the intensity of the reflected beam measured with the one or more photodetectors.

In some embodiments, the method includes emitting a plurality of laser light of different wavelengths through the optical fiber to illuminate the target.

In various embodiments, the method includes measuring a first intensity value of the reflected beam corresponding to the laser light of the first wavelength and a second intensity value of the reflected beam corresponding to the laser light of the second wavelength. In various such embodiments, the method includes: calculating a ratio of the first intensity value to the second intensity value; and estimating the distance between the distal end of the optical fiber and the target based on the ratio of the first intensity value to the second intensity value. distance.

Description of drawings

Non-limiting embodiments of the present disclosure are described by way of example with reference to the accompanying drawings, which are schematic and not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is shown is typically represented by a single numeral. It will be understood that the various figures included in this disclosure may omit some components, show parts of some components, and/or present some components as transparent to facilitate illustration and presentation of components that may otherwise appear hidden. describe. For purposes of clarity, not every component is labeled in every figure, nor is every component of every embodiment shown, where illustration is not necessary to allow one of ordinary skill in the art to understand the disclosure . In the picture:

FIG. 1A illustrates an exemplary architecture for estimating the distance between a fiber end and a target, according to some embodiments of the present disclosure.

Figure IB illustrates an exemplary optical fiber according to some embodiments of the present disclosure.

2A-2G illustrate exemplary configurations for estimating the distance between a fiber end and a target, according to some embodiments of the present disclosure.

2H and 2I illustrate exemplary views of a proximal end of an optical fiber cut at a particular angle, according to some embodiments of the present disclosure.

3A-3C show a flowchart illustrating a method of estimating a distance between an optical fiber end and a target according to some embodiments of the present disclosure.

4 shows a block diagram of an exemplary computer system for implementing embodiments consistent with the present disclosure.

Detailed ways

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 laser light generally depends on the relative position and orientation of the fiber tip with respect to the target. However, due to various factors, such as movement of the optical fiber relative to the position and orientation of the subject (e.g., patient), tissue environment, movement of tissue, surface of the target, color of the target, pigment of the target, optical fiber during treatment Determining or estimating the distance between the fiber tip and the target is extremely difficult due to tip degradation, water washout, and turbid environments (eg, due to dust removal). Determining the distance between the fiber tip and the target is further complicated by the fact that the fiber tip is typically inserted into the subject.

Incorrect estimation of the distance between the fiber end and the target as well as incorrect estimation of the orientation of the fiber end may result in aiming the laser at an area that is not the target's region of interest. This may lead to unnecessary complications and, in some cases, permanent damage to some parts of the subject's tissues, organs, etc., which may render the subject's body part dysfunctional. In some other cases, incorrect distance measurement and orientation may lead to increased treatment duration, or may lead to low-quality ablation/fragmentation results. In some cases, such as BPH or cancer, if the tumor is not properly ablated, it may lead to the regrowth of the tumor (or other undesired tissue), leading to further complications. Therefore, while performing certain treatments using laser and fiber optic technologies as discussed above, it is important to determine the precise (or maintain desired) distance between the fiber tip and the 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 by using a light emitting, transmitting and detecting (LETD) system using different laser light sources. The wavelengths can be chosen 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 laser light of different wavelengths. The return signal consists of a beam of light reflected from behind the target. One or more photodetectors configured in the LETD system can detect the return signal to measure the intensity value of the return signal at a specific wavelength. Using the measured intensity values, the processing unit can then estimate the distance between the fiber end and the target.

This disclosure uses the described LETD system in different configurations including various optical components such as beam combiners, beam splitters, polarizers, collimators, wavelength division multiplexers (WDM), photodetectors, etc. ) of different arrangements. The present disclosure enables accurate estimation of the distance between the fiber end and the target. Additionally, the present disclosure provides a robust distance estimation technique that is compatible with different types of targets. Additionally, the present disclosure may be used for the purpose of controlling and/or adjusting one or more operating parameters. For example, during treatment, the target may move around, back and forth, or otherwise, or may change one or more of its shape, size, composition, pigment, and color. Therefore, the laser source parameters preset before starting to laser on the target may become less effective. Traditionally, these preset parameters are changed manually, which can be error-prone and time-consuming, or in some cases, the preset parameters can be left unchanged, which can lead to situations where the fiber is too close or too far from the target. Thus, the present disclosure allows automatic and real-time monitoring of the distance between the fiber end and the target, and further enables automatic changes to preset laser emission parameters to adjust the laser light according to target shape, position, etc., and provide the desired outcome from the treatment. or a higher likelihood of outcome.

The foregoing has broadly outlined the features and technical advantages of the present disclosure so that the following detailed description of the disclosure may be better understood. It should be appreciated by those skilled in the art that the disclosed embodiment may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. The novel features of the disclosure, both as to its organization and method of operation, together with further objects and advantages, will be better understood from the following description when considered in conjunction with the accompanying drawings. It should be expressly understood, however, that each drawing is presented for purposes of illustration and description only, and is not intended as a definition of the limits of the present disclosure.

FIG. 1A illustrates an exemplary architecture 100 for estimating the distance between a fiber end and a target, according to some embodiments of the present disclosure. In some embodiments, exemplary architecture 100 includes target 101 , optical fiber 103 , light emission, transmission, and detection (LETD) system 105 , processing unit 107 , and indicator 109 . In some embodiments, the target 101 may be a tissue, stone, tumor, cyst, etc. to be treated, ablated or destroyed in a subject. In some embodiments, a subject can be a human or an animal. Furthermore, the optical fiber 103 includes a proximal end and a distal end. The proximal end is the end of the optical fiber 103 through which the light beam enters the optical fiber 103 and the distal end is the end of the optical fiber 103 through which the light beam is emitted and can be directed onto the target 101 . Thus, light beam 115 enters at proximal end 111 of optical fiber 103, propagates through the length of optical fiber 103, exits distal end 113, and is directed from distal end 113 of optical fiber 103 to (or toward) target 101, as shown in FIG. 1B .

In some embodiments, the beam of light may be a beam of light directed from a light source. For example, the light source may be a laser light source. As examples, laser light sources may include, but are not limited to, solid-state lasers, gas lasers, diode lasers, and fiber lasers. The beams may include one or more of: an aiming beam, a treatment beam, and any other beam transmitted through the optical fiber 103 . In various embodiments, the aiming beam may comprise a low intensity beam that is transmitted through the fiber optic 103 to estimate the distance between the end of the fiber optic (eg, distal end 113 ) and the target 101 . In several embodiments, the treatment beam may comprise a high intensity beam delivered through the optical fiber 103 to treat the target 101 . In some embodiments, different beams may be generated by one or more laser light sources. As a specific example, the aiming beam may be generated by one laser source and the treatment beam may be generated by another laser source. In another example, both the aiming beam and the treatment beam may be generated by a single laser source. In yet another example, different laser light sources may be used to generate beams of different wavelengths, characteristics, etc.

Additionally, an optical fiber 103 may be associated with a LETD system 105, as shown in FIG. 1A, to receive the beam, aim it at the target 101, and deliver a reflected beam that reflects off the surface and surrounding area of the target 101. In some embodiments, optical fiber 103 may be optically, mechanically and/or electrically coupled to LETD system 105 via a port (not shown in FIG. 1A ).

In some embodiments, the LETD system 105 includes optical components, which may include, but are not limited to, laser sources, polarizers, beam splitters, beam combiners, photodetectors, wavelength division multiplexers, collimators, circulators, etc. one or more of , which are configured in various combinations, as explained in detail in further sections of this disclosure.

In many embodiments, the laser light source is configured to generate a laser beam, such as a low-intensity aiming beam for aiming the beam 115 at the target 101 and a high-intensity therapy beam for treating the target 101, and/or have varying characteristics based on the application ( For example, intensity, wavelength, etc.) of the beam. Each laser light source can be configured to generate laser light having a different wavelength, where each of the different wavelengths can have a different coefficient of water absorption. Furthermore, each laser light source can have the same aperture or a different aperture. In some embodiments, each laser source may be assigned a different purpose, for example, one laser source may be configured to generate an aiming beam of a particular intensity, and one laser source may be configured to generate a treatment beam of a particular intensity, and One or more laser light sources may be configured to generate a beam of a particular wavelength with a particular water absorption coefficient. Additionally, each laser light source can be configured to generate polarized laser light or unpolarized/depolarized light.

Polarizers may include optical components that act as optical filters. For example, a polarizer can be configured to allow light beams of a particular polarization to pass, and block light beams of a different polarization. Thus, when undefined light (or a beam of mixed polarity) is provided as an input to a polarizer, the polarizer provides a well-defined, single-polarized beam as output.

A beam splitter may include optical components for splitting incident light into two separate beams in specified proportions. Furthermore, the beam splitter may be arranged to steer light incident at a desired angle of incidence (AOI). Thus, in many embodiments, a beam splitter can be configured primarily with two parameters, split ratio and AOI. The split ratio includes the ratio of reflection to transmission of the beam splitter (reflection/transmission (R/T) ratio). Thus, as used herein, if the splitting ratio of a beam splitter is indicated as 50:50, this means that the beam splitter splits the incident beam with an R/T ratio of 50:50. In other words, the beam splitter splits the incident light beam by changing it by reflecting 50% and transmitting another 50%. Also, as an example, if the AOI of a beam splitter indicates 45 degrees, this means that the beam splitter ensures that the beam will be incident at an angle of 45 degrees. Beam splitters may include, but are not limited to, polarizing beam splitters and non-polarizing beam splitters. A polarizing beam splitter may split incident light based on the S-polarization component and the P-polarization component, such as, for example, by reflecting the S-polarization component of light and transmitting the P-polarization component of light (or vice versa). In some embodiments, a non-polarizing beam splitter can split an incident beam based on a specific R/T ratio while maintaining the original polarization state of the incident beam.

A beam combiner may comprise a partial reflector which combines light of two or more wavelengths, such as by using the principles of transmission and reflection as explained above. In many embodiments, a beam combiner may be a combination of beam splitters and mirrors that perform the function of combining two or more wavelengths of light.

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

A collimator may include a device that narrows the beam. To narrow the beam, the collimator can be configured to make the direction of motion more consistent in a particular direction (eg, parallel rays), or to make the spatial cross-section of the beam smaller. In many embodiments, a collimator can be used to change the diverging light from a point source to a parallel beam.

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

Note that where specific parameters are listed for the optics described herein, such as a beam splitter with 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 is not a restriction. As a specific example, beam splitters having different R/T ratios and/or AOIs than specified herein may be provided in various embodiments described herein without departing from the scope of the disclosure and claims. In one such example, a 40 degree AOI may be used. In another such example, an R/T ratio of 47:53 may be used.

The LETD system 105 is also associated with a processing unit 107 via a communication network. In some embodiments, the communication network may be a wired communication network or a wireless communication network. The processing unit 107 may be configured to receive measurements from the LETD system 105 and estimate the distance between the distal end of the optical fiber 103 and the target 101 . In some embodiments, the processing unit 107 may be an independent device with the processing capabilities required for distance estimation. For example, the processing device 107 may comprise circuitry arranged to determine the distance based on electrical signals received from the LETD system 105 . As another example, the processing device 107 may include circuitry and memory including instructions that, when executed by the circuitry, cause the circuitry to determine a distance based on electrical signals received from the LETD system 105 . Still, in some other embodiments, the processing unit 107 may be a computing device, such as a laptop, desktop, mobile phone, tablet, etc., configured to perform distance estimation using its processing capabilities.

The processing unit 107 may be associated with an indicator 109 to indicate the estimated distance between the distal end of the optical fiber 103 and the target 101 . Indicator 109 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, indicators 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 processing unit 107 may be configured to perform the functions of indicator 109 . In some other embodiments, the indicator 109 may be a stand-alone device configured to indicate the estimated distance between the distal end of the optical fiber 103 and the target 101 .

Various exemplary configurations for estimating the distance between the fiber end and the 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 limitations on the present disclosure.

2A-2G illustrate example configurations of portions of architecture 100 including many configurations of LETD system 105 . It is important to note that the description of a previous figure (eg, Figure 2A) is often relied upon to adequately describe another figure (eg, Figure 2E). However, examples are not limited in this respect.

FIG. 2A illustrates an exemplary configuration 200A for estimating the distance between a fiber end and a target, according to some embodiments of the present disclosure. In configuration 200A, LETD system 105 may include one or more polarized (or unpolarized) lasers, one or more beam splitters, polarizers, beam combiners, and one or more photodetectors. The one or more beam splitters may be polarizing beam splitters, non-polarizing beam splitters, or a combination of both polarizing and non-polarizing beam splitters. As shown in Figure 2A, the LETD system 105 includes a first polarized laser source 201a, a second polarized laser source 201b, a first beam splitter 203, a power detector 205, a polarizer 207, a first beam combiner 209, a second splitter beam splitter 211 , polarizing beam splitter 213 , first photodetector 215 and second photodetector 217 .

In configuration 200A, the first polarized laser source 201a is arranged to generate laser light 225a (or light beam 225a) having a wavelength with a high water absorption coefficient relative to the wavelength of laser light 225b generated by the second polarized laser source 201b. As used herein, the laser light 225a generated by the first polarized laser source 201a may be referred to as high water absorption light (HI), while the laser light 225b generated by the second polarized laser source 201b may be referred to as low water absorption light (HI). 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 the threshold characteristic describing water absorption at a particular wavelength. For example, the high water absorption characteristic can be greater than or equal to 50%, and the low water absorption characteristic can be less than or equal to 50%.

In various embodiments, the ratio of high coefficient of water absorption to low coefficient of water absorption may be about 1:2. For example, laser 225a may utilize a wavelength of about 1310 nm and have a water absorption coefficient of about 0.1651, while laser 225b may utilize a wavelength of about 1340 nm and have a water absorption coefficient of about 0.333. A higher ratio between high and low absorption coefficients may result in less sensitivity to system noise (eg, electrical or optomechanical noise), but the resulting system may not be effective at distances beyond 3 mm. A lower ratio between high and low absorption coefficients may result in greater sensitivity to system noise, but the resulting system may remain effective at distances of up to 5 or 6mm. In some examples, the first and second polarized laser sources 201a and 201b may be polarization maintaining (PM) pigtailed fiber lasers.

Laser sources 201a and 201b are associated with and in optical communication with first beam splitter 203 . Stated differently, the laser beams 225a and 225b generated by the laser sources 201a and 201b, respectively, are provided as input to the first beam splitter 203, which is configured to divide the beams at approximately 50:50 (e.g., 47:53 or 49:51) to split incident beams 225a and 225b such that incident beams 225a and 225b are aligned as beam 227 along a single optical path. However, it will be understood 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 understood that any AOI between 1 and 89 degrees (such as 43-47 degrees, 40 degrees, or 20 degrees) may be utilized without departing from the scope of the present disclosure. scope.

A power detector 205 is associated with and in optical communication with the first beam splitter 203 . The power detector 205 is arranged to measure the optical power of light in the optical signal corresponding to each optical wavelength in the light beam 227 (eg, the portions of the light beams 225 a and 225 b routed to the power detector 205 ). In some embodiments, the term "optical power" may refer to the energy delivered by a certain laser beam per unit time.

The first beam splitter 203 is also associated with and in optical communication with a polarizer 207 . The first beam splitter is also arranged to provide a portion of the beams 225a and 225b , indicated as beam 227 , aligned along a single optical path, as input to the polarizer 207 . In some embodiments, the polarity of polarizer 207 may be preconfigured. Polarizer 207 is associated with and is in optical communication with first beam combiner 209 . In this manner, polarized light 229 obtained as an output from the polarizer 207 is supplied to the first beam combiner 209 as an input.

As shown in FIG. 2A , first beam combiner 209 may combine polarized beam 229 with aiming beam 231 and treatment beam 233 into combined beam 235 . In some other embodiments, aiming beam 231 and treatment beam 233 may be generated by one or more laser sources (not shown) in addition to laser sources 201a and 201b. As an example, the treatment beam 233 may be generated by a solid state laser or a fiber laser such as a holmium (HO) laser. However, this should not be considered a limitation of the present disclosure, as the therapeutic beams may be generated by lasers other than HO lasers, such as neodymium, erbium, thulium, etc. In some other embodiments, aiming beam 231 and treatment beam 233 may be generated by laser sources 201a and 201b. The combined beam 235 comprising the aiming beam 231, the treatment beam 233 and the polarized beam 229 from the laser sources 201a and 201b may be subjected to a second beam splitter 211 having a configuration of 50:50 R/T ratio and 45 degree AOI. That is, the first beam combiner 209 may be associated with and be in optical communication with the second beam splitter 211 such that the combined beam 235 is provided to the second beam splitter 211 as an input.

Second beam splitter 211 may split combined beam 235 in a 50:50 ratio such that aiming beam 231 , treatment beam 233 and polarized beam 229 from laser sources 201a and 201b are aligned along a single optical path. Second beam splitter 211 is optically coupled to optical fiber 103 (e.g., via port 219, etc.) such that, as shown in FIG. via port 219), and is indicated as beam 221. Light beam 221 is delivered to proximal end 111 of optical fiber 103 and then propagates through the length of optical fiber 103 to be delivered from distal end 113 of optical fiber 103 to target 101 . As an example, target 101 may be a tissue, stone, tumor, cyst, etc. within a subject to be treated, ablated, destroyed, etc.

When the light beam 221 is delivered to the target 101 via the optical fiber 103, the target 101 can reflect a portion of the incident light beam 221 away from the optical fiber 103 and reflect a portion of the light towards the optical fiber 103, wherein the portion of the light reflected towards the optical fiber 103 can be redistributed at the distal end of the optical fiber 103. Enter fiber 103 . The portion of reflected light that re-enters at the distal end may be referred to as reflected light 223a. Reflected light 223a may be transmitted "backwards" in optical fiber 103 from the distal end of optical fiber 103 to the proximal end of optical fiber 103 . When the reflected light 223a reaches the proximal end of the optical fiber 103 , the reflected light 223a may pass through the second beam splitter 211 . The reflected light 223a may include numerous reflections, such as from the proximal end of the optical fiber 103, from the distal end of the optical fiber 103, from the port 219, etc., so that the reflected light 223a is no longer polarized.

In order to polarize the reflected light 223a, the reflected light may first undergo the second beam splitter 211 to align the optical path of the reflected light 223a, and then undergo the polarization beam splitter 213. The reflected light 223a will be incident on the second beam splitter 211 at an angle of 45 degrees and split in a 50:50 ratio (or another ratio as outlined herein). The reflected light 223b coming out of the second beam splitter 211 is then subjected to the polarizing beam splitter 213, as shown in FIG. 2A. The polarization beam splitter 213 may split the reflected light 223b into a reflected P-polarized beam and a transmitted S-polarized beam. In some embodiments, first photodetector 215 may be configured to detect the P-polarized beam of light 223 b reflected by polarizing beam splitter 213 , while second photodetector 217 may be configured to detect P-polarized beam transmitted by polarizing beam splitter 213 The S-polarized beam of light 223b. The first light detector 215 and the second light detector 217 may respectively measure the intensity of the detected beam of light 223 b and transmit the intensity to the processing unit 107 . In some embodiments, the processing unit 107 can estimate the distance between the distal end of the optical fiber 103 and the target 101 based on the measured intensity. The method of estimating the distance between the distal end of the optical fiber 103 and the target 101 based on the measured intensity is explained in more detail below with respect to FIGS. 3A-3C .

FIG. 2B illustrates an exemplary configuration 200B for estimating the distance between a fiber end and a target, according to some embodiments of the present disclosure. Configuration 200B differs from configuration 200A in two configurations. One of the different construction aspects in configuration 200B when compared to configuration 200A is the arrangement of the first beam splitter 203 . In configuration 200B, the first beam splitter 203 is replaced by a second beam combiner 237 . Since the first beam splitter 203 is replaced by a second beam combiner 237, the power detector 205 associated with the first beam splitter 203 in configuration 200A is arranged in conjunction with the second beam splitter 211 in configuration 200B. Associated. The embodiments are not limited in this context.

In configuration 200B, LETD system 105 may include one or more polarizing lasers, one or more beam splitters, polarizers, 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 and non-polarizing beam splitters. As shown in Figure 2B, the LETD system 105 includes a polarized laser source 201a, a polarized laser source 201b, a power detector 205, a polarizer 207, a first beam combiner 209, a second beam combiner 237, a second beam splitter 211, Polarizing beam splitter 213 , first photodetector 215 and second photodetector 217 . In this configuration, as shown in FIG. 2B , the polarized laser light source 201a has a wavelength with a high water absorption coefficient (HI), and the polarized laser light source 201b has a wavelength with a low water absorption coefficient (LO).

The incident beams from laser sources 201a and 201b are provided as input to a second beam combiner 237 configured to combine incident beams 225a and 225b generated by laser sources 201a and 201b into beam 227 . Furthermore, the output of the second beam combiner 237 (eg, beam 227 ) may be provided as input to polarizer 207 for providing polarized beam 229 as output. In some embodiments, the polarization of polarizer 207 may be preconfigured. Thereafter, polarized light 229 obtained as an output from the polarizer 207 may be provided as an input to the first beam combiner 209 . First beam combiner 209 may combine polarized beam 229 with aiming beam 231 and treatment beam 233 into combined beam 235, as shown in FIG. 2B.

The combined beam 235 comprising the aiming beam 231, the treatment beam 233 and the polarized beam 229 from the laser sources 201a and 201b may be subjected to a second beam splitter 211 having an R/T ratio of 50:50 and a 45 AOI (or any other R/T ratio and AOI as outlined herein) configuration. The second beam splitter can split the combined beam 235 at a ratio of 50:50 so that the aiming beam 231, the treatment beam 233 and the polarized beam 229 from the laser sources 201a and 201b can be aligned along a single optical path.

The power detector 205 associated with the second beam splitter 211 can measure the power in the optical signal (beam 235, beam 229, etc.) corresponding to each wavelength. In various embodiments, the power detector 205 may detect the accumulated energy of the optical signal received at the second beam splitter 211 . In some embodiments, the term "optical power" may refer to the energy delivered by a certain laser beam per unit time. As outlined above with respect to FIG. 2A , beam 221 , which is the output of second beam splitter 211 , is then transmitted to optical fiber 103 (eg, via port 219 ). Additionally, reflected light 223a is received and processed as outlined above with respect to Figure 2A.

FIG. 2C illustrates an exemplary configuration 200C for estimating the distance between a fiber end and a target, according to some embodiments of the present disclosure. The present disclosure can work with polarized and non-polarized laser sources. Therefore, in the configuration 200C, the laser sources 201a' and 201b' for providing the incident light beam (source light) are non-polarized laser sources. As an example, the laser sources 201a' and 201b' may be single mode (Single Mode, SM) fiber pigtailed lasers. When the laser sources 201a' and 201b' are non-polarized laser sources, the polarizer 207, the polarizing beam splitter 213, the first photodetector 215 for detecting the P-polarized beam and the second photodetector for detecting the S-polarized beam are not required. Light detector 217, as depicted in configurations 200A and 200B above.

In configuration 200C, LETD system 105 may include one or more unpolarized lasers, one or more beam splitters, beam combiners, and photodetectors. One or more beam splitters may be non-polarizing beam splitters. As shown in Figure 2C, the LETD system 105 includes a first unpolarized laser source 201a', a second unpolarized laser source 201b', a first beam splitter 203, a power detector 205, a first beam combiner 209, a second splitter Beamer 211 and a third photodetector 239.

As with existing configurations, in configuration 200C, the unpolarized laser source 201a' may have a high water absorption coefficient (HI) wavelength, and the unpolarized laser light source 201b' may have a low water absorption coefficient (LO) wavelength. The incident beams 225a' and 225b' from the laser sources 201a' and 201b' are provided as input to the first beam splitter 203, which is configured to split the incident beams at a ratio of 50:50 such that the incident beams 225a' and 225b' are aligned along a single optical path as light beam 227'.

The power detector 205 associated with the first beam splitter 203 can measure the power in the optical signal (beam 227') corresponding to each wavelength. Since configuration 200C is implemented in a non-polarizing environment, no polarization-based optical components such as polarizers and polarizing beam splitters are required in this configuration. Thus, the output of the first beam splitter 203, namely the incident light beams 225a' and 225b' aligned along a single optical path as light 227', can be provided as input to the first beam combiner 209. The first beam combiner 209 may combine the beam 227' from the first beam splitter 203 with the aiming beam 231 and the treatment beam 233, as shown in Figure 2C.

In some embodiments, aiming beam 231 and treatment beam 233 may be generated by one or more laser sources other than laser sources 201a' and 201b'. In some other embodiments, aiming beam 231 and treatment beam 233 may be generated by laser sources 201a' and 201b'. The combined beam 235' comprising the aiming beam 231, the treatment beam 233 and the unpolarized beams 201a' and 201b' from the laser sources 201a' and 201b' may be subjected to a second beam splitter 211 having a ratio of 50:50 and a 45 degree Configuration of AOI (or any other R/T ratio and AOI as outlined herein). The second beam splitter 211 may split the combined beam 235' in a 50:50 ratio such that the aiming beam 231, the treatment beam 233 and the unpolarized beams 225a' and 225b' are aligned along a single optical path. Beam 221 , which is the output of second beam splitter 211 , is then transmitted to optical fiber 103 (eg, via port 219 ), while reflected light 223a is transmitted back, as shown in FIG. 2C and described above.

Since configuration 200C is implemented in a non-polarized environment, reflected light 223a is only subjected to second beam splitter 211 to align the light path of reflected light 223a without the need for a polarizing beam splitter as depicted in configurations 200A and 200B. The reflected light 223a will be incident on the second beam splitter 211 at an angle of 45 degrees and split at a ratio of 50:50. The reflected light 223b from the second beam splitter 211 can be directly detected by a single detector. As such, configuration 200C provides a third light detector 239 .

The third light detector 239 may respectively measure the intensity of the detection beam of the reflected light 223 b and transmit the intensity to the processing unit 107 . In some embodiments, the processing unit 107 can estimate the distance between the distal end of the optical fiber 103 and the target 101 based on the measured intensity. The method of estimating the distance between the distal end of the optical fiber 103 and the target 101 based on the measured intensity is explained in more detail below with respect to FIGS. 3A-3C .

Figure 2D illustrates an exemplary configuration 200D for estimating the distance between a fiber end and a target, according to some embodiments of the present disclosure. Configuration 200D includes a third polarized laser source 201c introduced for the purpose of real-time calibration of fiber conditions. As an example, the state of the optical fiber 103 may include, but is not limited to, any changes or degradations at the distal or proximal end of the optical fiber 103 , the effect of fiber bending on polarization scrambling, or any other degradation and changes occurring in the optical fiber 103 . Changes in the state of the fiber 103, especially the tip/end of the fiber 103 (eg, input and output facets) can adversely affect the transmitted and reflected beams, resulting in numerous reflections, energy loss, and inaccurate measurements. This may affect the accuracy of the distance estimate, resulting in incorrect positioning of the optical fiber 103 during treatment.

In configuration 200D, LETD system 105 may include one or more polarized lasers, one or more beam splitters, polarizers, 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 and non-polarizing beam splitters. As shown in Figure 2D, the LETD system 105 includes a polarized laser source 201a, a polarized laser source 201b and a polarized laser source 201c, a first beam splitter 203, a power detector 205, a polarizer 207, a first beam combiner 209, a second A beam splitter 211 , a polarizing beam splitter 213 , a first photodetector 215 , a second photodetector 217 and a third beam splitter 241 . In configuration 200D, as shown in Figure 2D, incident beams 225a and 225b from laser sources 201a and 201b are provided as input to a first beam splitter 203, which is configured to split The incident light beams 225a and 225b are split such that the incident light beams 225a and 225b are aligned along a single optical path, forming the light beam 227 . In addition, the output of first beam splitter 203 (e.g., beam 227) as incident beams 225a and 225b aligned along a single optical path may be provided as input to a third beam splitter 241, which is also configured To split the incident beam at a ratio of 50:50, beam 243 comprising light 225a, 225b and 225c is formed.

At a third beam splitter 241, an incident beam 225c (eg, light for calibration) from a polarized laser source 201c is provided as input together with the output of the first beam splitter 203 (eg, beam 227). Power detector 205 associated with third beam splitter 241 may measure the power in the optical signal (eg, beam 243 ) corresponding to each wavelength reaching third beam splitter 241 . Along with the output of the first beam splitter 203, the third beam splitter 241 receives the incident beam from the polarized laser source 201c.

In some embodiments, polarized laser source 201c has a wavelength with a very high water absorption coefficient (eg, substantially, completely, or nearly completely absorbed by water) relative to the wavelength of light emitted by laser sources 201a and 201b. As an example, polarized laser source 201c may have a wavelength of about 1435 nm and have a water absorption coefficient of about 31.55 (or about 100 times that of a "high" water absorbing 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 may have a wavelength of about 1420 to about 1440 (resulting in a water absorption coefficient of about 30). Alternative or additional wavelengths (eg 1870-2070nm) with very high water absorption coefficients may be utilized. However, wavelengths farther from the HI and LO wavelengths (eg, 1310 nm and 1340 nm, respectively) may result in more complex optical designs. For example, a detector may cover a range of approximately 1100-1600 nm, and if a 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 between about 1870 nm and about 2050 nm.

Based on the readings from polarized laser source 201c (eg, as measured by power detector 205 ), processing unit 107 may define an optical baseline characteristic of the "quality" of the fiber tip at distal end 113 of optical fiber 103 . More specifically, since laser source 201c is highly absorbed in water, light from laser source 201c will be less likely to reach the target tissue, and as a result hardly any light from laser source 201c will be absorbed as part of reflected light 223a reflected back into the fiber 103. Thus, the component of light reflection 223c having the wavelength of light associated with laser source 201c is primarily due to the optical properties of distal end 113 of optical fiber 103 . It should be appreciated that the distal end 113 of the optical fiber 103 undergoes degradation during laser treatment due to, for example, heat and cavitation. In many embodiments, an increased intensity reading of back reflected light 223c may indicate fiber tip degradation. In several embodiments, at some threshold (e.g., 10% to 50%, greater than or equal to 25%, 50%, 75%, 90%, between 10% and 100%, etc.), the processing unit 107 may indicate that the optical fiber 103 should be checked or replaced, such as through a user interface and/or an audible alarm. Additionally, fiber tip degradation may result in higher internal reflection of light from polarized laser sources 201a and 201b from the far end of the fiber. Whether the laser source is polarized or not has little effect on internal reflections because the light is randomly depolarized in the fiber. However, monitoring the reflection from the distal end of the fiber by a very high absorption coefficient laser (eg, a 1435nm laser) can be used to determine the change in reflection at the far end (as a percentage of initial reflection at 1435 to real time reflection). In addition, for LO lasers (eg, 1310 nm lasers) and HI lasers (eg, 1340 nm lasers), changes in the far-end reflections can be applied to the original reflections from the far-end to update the initial reflections.

In addition, fiber tip degradation may change the ratio between polarity P and polarity S in back reflected light 223a or 223c. Thus, creating baseline readings for the particular fiber 103 currently in use, and monitoring these baselines in real time, allows for more accurate distance estimates, even as and during fiber tip degradation and until degradation reaches a threshold indicating that the fiber 103 should be replaced until level. Furthermore, the output or beam 243 of the third beam splitter 241 (which includes the incident beams 225a, 225b and 225c aligned along a single optical path) may be provided as input to the polarizer 207 to obtain a single polarized beam 245 as output. In some embodiments, the polarization of polarizer 207 may be preconfigured.

Polarized light 245 obtained as output from polarizer 207 may be provided as input to first beam combiner 209 . First beam combiner 209 may combine polarized beam 245 with aiming beam 231 and treatment beam 233 to form combined beam 235, as shown in FIG. 2D. As mentioned above, aiming beam 231 and/or treatment beam 233 may be generated by one or more laser sources other than laser sources 201a, 201b or 201c, or aiming beam 231 and/or treatment beam 232 may be generated by laser source L1 and L2 generation.

The combined beam 235 comprising the aiming beam 231 , the treatment beam 233 and the polarized beam 245 may be subjected to a second beam splitter 211 having a ratio 50:50 and a 45 degree AOI configuration. Second beam splitter 211 may split combined beam 235 at a ratio of 50:50 such that aiming beam 231 , treatment beam 233 and polarized beam 245 are aligned along a single optical path. Light beam 221, which is the output of second beam splitter 211, is then transmitted to optical fiber 103 (eg, via port 219).

FIG. 2E illustrates an exemplary configuration 200E for estimating the distance between a fiber end and a target, according to some embodiments of the present disclosure. Like configuration 200C, configuration 200E is implemented in a non-polarizing environment. Furthermore, configuration 200E is a "half fiber based design" where the two input splitters seen in previous configurations (eg, configuration 200D) are replaced by wavelength division multiplexers (WDMs). WDM power loss may be about 20%, while splitter power loss may be about 50%, thus using WDM increases the efficiency of the LETD system 105 . In addition, WDM can perfectly or nearly perfectly align each of the three laser sources into the optical path. However, beam splitters and beam combiners are much less precise at aligning each of the three laser sources into a single beam.

Configuration 200E utilizes a third unpolarized laser 201c' as well as a first unpolarized laser 201a' and a second unpolarized laser 201b'. As mentioned above, the third non-polarized laser 201c' is introduced for the purpose of calibrating the fiber state in real time. It will be appreciated that the collimation lasers may be polarized or non-polarized without departing from the scope of this disclosure. In configuration 200E, the LETD system 105 may include one or more unpolarized lasers, one or more beam splitters, a beam combiner, one or more photodetectors, a WDM, and a collimator. As shown in Figure 2E, the LETD system 105 includes a non-polarized laser source 201a', a non-polarized laser source 201b', a non-polarized laser source 201c', a power detector 205, a first beam combiner 209, and a second beam splitter 211 , a third photodetector 239 , a WDM 247 , a fourth beam splitter 249 and a collimator 251 . In configuration 200E, the unpolarized laser source 201a' may emit light at a wavelength with a high water absorption coefficient (HI), and the unpolarized laser source 201b' may emit light at a wavelength with a low water absorption coefficient (LO). In addition, non-polarized laser source 201c' may emit light having a wavelength that has a very high water absorption coefficient (eg, completely or almost completely absorbed by water) relative to the wavelength of light emitted by laser sources 201a' and 201b'. As an example, the unpolarized laser source (L3') may have a wavelength of 1435nm.

As mentioned above, in configuration 200E the first beam splitter 203 and the third beam splitter 241 shown in FIG. 2D are replaced by WDM 247 . In some embodiments, to ensure proper use of the unpolarized laser source 201c', as a real-time collimator, the incident beams from each of the unpolarized lasers 201a', 201b', and 201c' may be arranged to be at the same point And enter the proximal end of the optical fiber 103 at the same angle. In many embodiments, it may be difficult or impossible to align the incident beams from each of the non-polarized lasers 201a', 201b', and 201c' to enter at the same point and at the same angle using a combiner/beam splitter. possible. To ensure compliance with this same point and same angle condition, configuration 200E uses WDM247. WDM 247 may be configured to ensure that all incident beams from each of unpolarized lasers 201a', 201b', and 201c' enter the proximal end of fiber 103 at the same point and at the same angle. Furthermore, in various embodiments, the use of WDM 247 may reduce power loss, such as when compared to some beam splitters that result in 50%-75% power loss.

The incident beams from 201a', 201b', 201c' and the aiming beam 231 are provided as input to the WDM 247, which is configured to combine the incident beams in such a way that the beams move identically. In addition, the output of WDM 247 can be provided as input to a fiber-based beam splitter (e.g., fourth beam splitter 249), which can be arranged to provide a high transmission-reflection ratio (e.g., 95:5 or 99:1 ) to split the incident beam, as shown in Figure 2E. In some embodiments, the fourth beam splitter 249 is a fiber optic based beam splitter. The power detector 205 associated with the fourth beam splitter 249 can measure the power in the optical signal (e.g. beam 253') corresponding to each wavelength. In addition, the output of fourth beam splitter 233 (e.g., beam 253'), which is incident light aligned along a single optical path, can be provided as input to collimator 251 to narrow beam 253' into a parallel beam.

Thereafter, the output of collimator 251 (e.g., beam 255') may be provided to first beam combiner 209, which combines beam 255' emerging from collimator 251 with aiming beam 231 and treatment beam 233 combinations, as shown in Figure 2E. In several embodiments, aiming beam 231 may be introduced at WDM 251 . In many embodiments, aiming beam 231 may be introduced at first beam combiner 209 . Still, in some embodiments, aiming beam 231 may be introduced at both WDM 251 and first beam combiner 209 . In some embodiments, aiming beam 231 and/or treatment beam 233 may be generated by one or more laser sources other than laser sources 201a', 201b', and 201c', or aiming beam 231 and/or treatment beam 233 may be Generated by laser sources 201a', 201b' and 201c'.

Combined beam 235' (e.g., light from laser sources 201a', 201b', and 201c' received from first beam combiner 209) comprising aiming beam 231, treatment beam 233, and beam 255' may be subjected to a second beam splitter 211 with a configuration of R/T ratio 50:50 and 45 degree AOI. The second beam splitter 211 can split the combined beam 235' at a ratio of 50:50 so that the aiming beam 231, the treatment beam 233 and the unpolarized beam 255' from the laser sources 201a', 201b' and 201c' can follow a single optical path align. Beam 221, which is the output of second beam splitter 211, is then delivered to optical fiber 103 (eg, via port 219), as shown above and described more fully.

FIG. 2F illustrates an exemplary configuration 200F for estimating the distance between a fiber end and a target, according to some embodiments of the present disclosure. Like configurations 200C and 200E, configuration 200F is implemented with an unpolarized detector. However, the source can be unpolarized or polarized. In this exemplary configuration, LETD system 105 may include one or more unpolarized lasers (or polarized lasers), one or more beam splitters, beam combiners, one or more photodetectors, WDMs, circulators, and Collimator. As shown in Figure 2F, the LETD system 105 includes an unpolarized laser source 201a', an unpolarized laser source 201b', an unpolarized laser source 201c', a power detector 205, a first beam combiner 209, and a third photodetector 239 , WDM247, fourth beam splitter 249, collimator 2251 and circulator 257. In configuration 200F, the unpolarized laser source 201a' may emit light at a wavelength with a high water absorption coefficient (HI), while the polarized laser source 201b' may emit light at a wavelength with a low water absorption coefficient (LO). In addition, the unpolarized laser light source 201c' may have a wavelength with a very high water absorption coefficient, which is substantially absorbed in water.

As mentioned above, in configuration 200F, the first beam splitter 203 and the third beam splitter 241 as shown in Fig. 2D are replaced by WDM 247 as shown in Fig. 2F. Furthermore, in the exemplary configuration 200F, the second beam splitter 211 arranged to deliver the beam to the port 219 in all the above exemplary configurations is also removed. Beam splitters reduce the output power by up to 50% (or more), and reduce an additional 50% (or more) of the output power when receiving the return signal. Therefore, removing the beam splitter in configuration 200F increases the signal and output power significantly.

The incident beams 225a', 225b' and 225c' from the laser sources 201a', 201b' and 201c' and the aiming beam 231 are provided as input to the WDM 247, which is configured to combine the incident beams in such a way that the beams move in the same manner. Further, the output of WDM 231 may be provided as input to a fourth beam splitter 249, which splits the incident beam at a ratio of 95:5, as shown in FIG. 2F. As previously mentioned, other ratios such as 99:1 may be used without departing from the scope of this disclosure. In some embodiments, fourth beam splitter 233 is a fiber-based beam splitter, making configuration 200F an all fiber-based design. The power detector 205 associated with the fourth beam splitter 249 can measure the power in the optical signal (e.g. beam 253') corresponding to each wavelength. Additionally, the output of fourth beam splitter 249 (e.g., beam 253'), which is incident light aligned along a single optical path, may be provided as an input to circulator 257. The circulator 257 is configured to ensure that all beams travel in one direction. In addition, the circulator 257 provides the collimator 251 with a port other than the port where the beam 253' enters from the beam 253'. The collimator 251 can narrow the beam into a parallel beam 255'. When compared to a beam splitter, the circulator 257 can provide (1) lower power loss (beam splitter loss is ~50% in each direction) and (2) more flexible optical design (free-space optics Straight lines are required, whereas fiber-based designs can be folded as needed).

The output of collimator 251 (e.g., parallel beam 255') may be provided to first beam combiner 209, which combines beam 255' emerging from collimator 251 with aiming beam 231 and treatment beam 233 into a combined beam 221, as shown in FIG. 2F. In some embodiments, aiming beam 231 may be introduced initially (e.g., into WDM 247), may be introduced at first beam combiner 209, or may be introduced at both WDM 247 and first beam combiner 209. be introduced. In some embodiments, aiming beam 231 and/or treatment beam 233 may be generated by one or more laser sources other than laser sources 201a', 201b', and 201c', or aiming beam 231 and/or treatment beam 233 may be Generated by laser source 201a', 201b' or 201c'. Combined beam 221 comprising aiming beam 231, treatment beam 233, and beam 255' (e.g., beams 225a', 225b', and 225c' from laser sources 201a', 201b', and 201c') received from first beam combiner 209 may be transmitted to fiber 103 (eg, via port 219), as shown in FIG. 2F. The combined light beam 221 is transmitted to the proximal end 111 of the optical fiber 103 , where it then propagates through the length of the optical fiber 103 and is delivered from the distal end 113 of the optical fiber 103 to the target 101 .

As outlined above, when the light beam 221 is delivered to the target 101 via the distal end 113 of the optical fiber 103, the target 101 may reflect a portion of the light away from the optical fiber 103 and reflect a portion of the light towards the optical fiber 103, wherein the portion of the light reflected towards the optical fiber 103 may be at The distal end 113 re-enters the optical fiber 103 . As outlined above, the portion of reflected light that re-enters at distal end 113 is referred to as reflected light 223a. Reflected light 223a may be transmitted “backwards” from distal end 113 to proximal end 111 through optical fiber 103 . When the reflected light 223a reaches the proximal end 111 of the optical fiber 103, the reflected light 223a may pass through the first beam combiner 209 and the collimator 251 to undergo the circulator 251 where it is routed to the third photodetector 239 and measured as described above. FIG. 2G illustrates an exemplary configuration 200G for estimating the distance between the end of an optical fiber and a target, according to some embodiments of the present disclosure. Like some existing configurations, configuration 200G can be implemented in a non-polarized environment. In several embodiments, configuration 200G may include a single beam splitter based optical design. In configuration 200G, WDM 247 may replace the function or operation of multiple beam splitters (eg, those used in configurations 200A-200D, etc.). WDM 247 may receive input beams 225a', 225b' and 225c' from unpolarized laser sources 201a', 201b' and 201c'.

In configuration 200G, the LETD system 105 may include one or more unpolarized lasers (or polarized lasers), a beam splitter, a beam combiner, one or more photodetectors, a WDM, and a collimator. As shown in Figure 2G, the LETD system 105 includes a first unpolarized laser source 201a', a second unpolarized laser source 201b', a third unpolarized laser source 201c', a power detector 205, a first beam combiner 209, a second Five beam splitter 259 , third photodetector 239 and WDM 248 . In configuration 200G, as in existing configurations, the wavelength of unpolarized laser beam 225a' may have a high water absorption coefficient (HI) relative to unpolarized laser beam 225b', which itself may have a wavelength of Lower water absorption coefficient (LO). In addition, the unpolarized laser beam 225c' may have a wavelength with a very high water absorption coefficient as described in detail above.

As described above, processing unit 107 may define an optical baseline characteristic of the quality of distal end 113 (e.g., output face, etc.) of optical fiber 103 based on readings associated with reflection of light generated by unpolarized laser source 201c'. More specifically, since light from laser source 201c' is highly absorbed in water, a small amount of this light will be reflected back into fiber 103 as part of reflected light 223a. Accordingly, the readings associated with reflected light 223c are primarily attributable to the optical properties of the distal end 113 of the optical fiber 103, which, as described, undergoes degradation during laser treatment due to, for example, heat and cavitation. Thus, an increased intensity reading of back reflected light 223c may indicate fiber tip degradation.

In several embodiments, at some threshold (e.g., 10% to 50%, greater than or equal to 25%, 50%, 75%, 90%, 10% to 100%, etc.), the processing unit 107 may indicate that the optical fiber 103 should be checked or replaced, such as through a user interface and/or an audible alarm. Additionally, fiber tip degradation may result in higher internal reflection of light from the distal end 113 of the fiber 103 associated with the unpolarized laser sources 201a' and 201b'. In addition, fiber tip degradation may change the ratio between polarity P and polarity S in back reflected light 223a or 223c. Therefore, creating baseline readings for the specific fiber currently in use, and monitoring these baselines in real time, allows for more accurate distance estimates, even as and during fiber tip degradation and until degradation reaches the point at which the fiber should be replaced. Thus, greater dynamic control over parameters associated with therapy or therapy may be provided.

As with some existing configurations, configuration 200G utilizes WDM 247 to ensure that all incident beams from each of unpolarized lasers 201a', 201b', and 201c' enter proximal end 111 of fiber 103 at the same point and at the same angle . Furthermore, in various embodiments, the use of WDM 247 may reduce power loss, such as when compared to some configurations utilizing beam splitters.

The incident beams 225a', 225b' and 225c' from the laser sources 201a', 201b' and 201c' and the aiming beam 231 can be provided as input to the WDM 247 which can be configured to combine the incident beams in such a way that the beams move in the same manner . In addition, the output of the WDM 247 may be provided as an input to a fifth beam splitter 259, which may split the incident beam at a ratio of 50:50, as shown in FIG. 2G. In some embodiments, fifth beam splitter 259 may be a free space (eg, glass) based beam splitter. In some other embodiments, the fifth beam splitter 259 may be a fiber optic based beam splitter. In many embodiments, the power detector 205 associated with the fifth beam splitter 259 can measure the power in the optical signal (e.g., beam 253') corresponding to each wavelength.

The output of the fifth beam splitter 259 as incident light aligned along a single optical path may be provided as input to the first beam combiner 209 . The first beam combiner 209 may combine the beam 253' emerging from the fifth beam splitter 259 with the aiming beam 231 and the treatment beam 233, as shown in Figure 2G. In various embodiments, aiming beam 231 may be introduced into WDM 247 , at first beam combiner 209 , or at both WDM 247 and first beam combiner 209 . In several embodiments, aiming beam 231 and/or treatment beam 233 may be generated by one or more laser sources other than laser sources 201a', 201b', and 201c', or aiming beam 231 and/or treatment beam 233 Can be generated by laser sources 201a', 201b' and 201c'. Combined beam 221 received from first beam combiner 209 comprising aiming beam 231, treatment beam 233, and beams 253' from laser sources 201a', 201b', and 201c' may be delivered to fiber optic 103 (e.g., via port 219) .

As can be seen from this figure, configuration 200G eliminates the use of a second beam splitter (e.g., second beam splitter 211) and instead a fifth beam splitter 259 (which is initially configured to split the incident beam to Single optical path alignment (incident light) is used to align the optical path of reflected light 223a. Furthermore, since configuration 200G utilizes a single beam splitter, it may be significantly less sensitive to therapeutic fiber movement and fiber bend radius, resulting in a more robust configuration. Also, because configuration 200G has fewer optical components, such as beam splitters, beam combiners, detectors, etc., configuration 200G may be more compact, simpler, and less expensive than other configurations.

In some embodiments, in each of the exemplary configurations described herein, the proximal end of the optical fiber 103 may be coated with a special coating, such as an anti-reflection (AR) coating. The AR coating can help reduce noise generated at the proximal end 111 of the optical fiber 103 and increase dynamic range. In some embodiments, the optical signal (e.g., reflected beam 223) entering the photodetector may contain one or more of: (a) reflection from the port lens; (b) reflection from the blast shield reflections; (c) reflections from the proximal end 111 of the fiber; and/or (d) reflections from the distal end 113 of the fiber.

In various embodiments, the AR coating for the blast shield can reduce reflection from the port lens to less than 1%, the AR coating for the port lens can reduce reflection from the blast shield to less than 1%, and The AR coating at the proximal end 111 of the optical fiber 103 can reduce the reflection from the proximal end 111 of the optical fiber 103 from 3.5% to about 0.5%. In some embodiments, the reflected signal from a target 101 such as a stone may have very low energy, eg, close to 1% of the fiber output power, where the distance from the fiber tip to the tissue is about 0 mm. By reducing the reflection from the proximal end 111 of the optical fiber 103 to approximately 0.5%, the present disclosure can help improve the dynamic range of the signal reflected from the target 101 .

In some embodiments of the exemplary configurations described above, the proximal end 111 of the optical fiber may include a subminiature A (SMA) connector, which may be polished or cut at an 8 degree angle, as shown in FIG. 2H . As shown in the figure, cutting at an angle of 8 degrees obliquely achieves a diversion of the reflected beam from the proximal end 111 of the optical fiber 103 (undesired reflections caused by the proximal end 111), which in turn can reduce substantial noise and Increase dynamic range. In some embodiments, the optical signal (e.g., reflected beam 223) entering the photodetector may contain one or more of: (a) reflections from the port lens; (b) reflections from the blast shield; (c ) a reflection from the proximal end 111 of the fiber; and/or (d) a reflection from the distal end 113 of the fiber.

As explained above, the AR coating of the proximal end of the optical fiber 103 can reduce the reflection from the proximal end of the optical fiber 103 from 3.5% to about 0.5%. However, the more finely angled proximal end of fiber 103 helps reduce unwanted reflections and improves the dynamic range of the signal reflected from target 101 . In some other embodiments, the SMA connectors may be polished or cut at 4 degrees instead of 8 degrees, as shown in FIG. 21 . In various embodiments, cutting obliquely at a 4 degree angle, such as instead of an 8 degree (or higher) angle, may improve signal robustness. In some embodiments, a smaller cut angle of the SMA connector may result in greater signal robustness of the optical fiber 103 . In various embodiments, an angle of from about 2 degrees to about 8 degrees may be utilized. In general, lower angles are more difficult to implement in optics. In other words, it's hard to grab it from the main signal. However, light will not enter the fiber at higher angles (eg, 10+ degrees).

FIG. 3A shows a flowchart illustrating a method 300 of estimating a distance between an optical fiber end and a target according to some embodiments of the present disclosure. Method 300 is described with reference to architecture 100 and various configurations of LETD 105 described above. However, it should be understood that method 300 may be implemented using LETDs other than those described herein. The embodiments are not limited in this context.

At block 301 , method 300 includes illuminating a target with a plurality of laser light of different wavelengths. For example, LETD 105 may utilize multiple laser sources (eg, 201a and 201b or 201a' and 201b') via optical fiber 103 to irradiate target 101 with multiple lasers of different wavelengths. In some embodiments, multiple different wavelengths of laser light may be provided to optical fiber 103 for illuminating target 101 using one of the configurations 200A-200G discussed above in this disclosure. In various embodiments, the present disclosure may use light having two different wavelengths (e.g., light 225a and 225b or light 225a' and 225b'), each wavelength having a different coefficient of water absorption to ensure that different types of targets are targeted. 101. Robustness of target composition, target color, target surface, etc.

In some embodiments, two wavelengths may be selected such 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 1310 nm and 1340 nm. However, this example should not be construed as limiting, as different wavelengths with different water absorption coefficients can be used. For example, 1260-1320nm can be used for LO, and 1330-1380nm can be used for HI. More generally, any combination of wavelength water absorption coefficient pairs with a 2:1 (or greater) ratio can be used. In some embodiments, one or more of the following pairs may be used for LO and HI lasers, 1310 nm and 1340 nm lasers, 1260 nm and 1340 nm lasers, 1260 nm and 1310 nm and 1310 nm and 1550 nm lasers, respectively. As outlined above, in some embodiments, two laser sources (eg, 201a and 201b or 201a' and 201b') may be used to emit light at two different wavelengths. In some embodiments, the laser source may be a polarized laser source, a non-polarized laser source, or a combination of polarized and non-polarized laser sources. As an example, to measure the distance between the distal end 113 of the optical fiber 103 and the target 101 , the target 101 may be illuminated via the optical fiber 103 using, but not limited to, a low power infrared (IR) laser. In other embodiments, lasers other than IR lasers may be used. However, an IR laser can be used because it does not include visible light that may disturb the user.

At block 303, the method 300 includes receiving a reflected beam from the target via the optical fiber. For example, LETD system 105 may receive reflected beam 223 from target 101 via optical fiber 103 . In some embodiments, reflected light beam 223 may include a mix of reflections such as from proximal end 111 of optical fiber 103 , from distal end 113 of optical fiber 103 , from port 219 , from a blast shield (not shown), and the like. In various embodiments, the LETD system 105 can be configured to identify reflected beams suitable for measuring intensity.

At block 305, the method includes measuring the intensity of the reflected beam by detecting the reflected beam using one or more photodetectors, and an indication (e.g., an electrical signal, etc.) of the reflected beam intensity measured by the one or more photodetectors sent to the processing unit. For example, the LETD system 105 may measure the intensity of the reflected light beam 223 (also referred to herein as the return signal) by detecting the return signal 223 using one or more photodetectors provided in the LETD 105 system. In some embodiments, since two different wavelengths are used to illuminate the target 101, the measured intensities are for two different wavelengths. Accordingly, two measured intensities corresponding to two laser sources of different wavelengths (e.g., laser sources 201a and 201b or 201a' and 201b', etc.) may be communicated to the processing unit 107 associated with the LETD system 105. In various embodiments, three or more different wavelengths may be utilized, measured and/or transmitted.

At block 307, the method includes receiving, by the processing unit, an indication of the intensity of the reflected light beam 223 measured by the one or more light detectors. For example, processing unit 107 may receive an electrical signal from LETD system 105 that includes an indication of the measured strength of return signal 223 .

At block 309, the method includes estimating, by the processing unit, a distance between the distal end of the optical fiber and the target based on the intensity of the reflected light beam measured by the one or more light detectors. For example, the processing unit 107 may estimate the distance between the distal end of the optical fiber 103 and the target 101 based on the measured strength of the return signal. In some embodiments, the processing unit 107 may substitute the measured intensity into Equation 1 as follows:

The strength of the returned signal = R*e ^(-λ*X) Formula 1

In the above formula 1, "R" refers to the target reflection coefficient influenced by the target composition, target color/pigment, target angle, target surface, etc.; "λ" refers to the water absorption coefficient of a specific wavelength; The distance between the end and the target 101.

In the above formula 1, “X” and “R” are unknown parameters that need to be determined by the processing unit 107 . Therefore, to determine the values of "X" and "R", the processing unit 107 may substitute the two measured intensity values into Equation 1 above, thereby obtaining a substitution with the measured intensity and the water absorption coefficient for the corresponding wavelength Two formulas for the value. For example, two formulas with substituted values might look like this.

I _(HI) = R*e ^(-λ_HI*X) Formula 1.1

I _(LO) = R*e ^(-λ_LO*X) Formula 1.2

The processing unit 107 can further simplify the above substitution formulas 1.1 and 1.2, as shown in the following two steps:

Step 1: Calculate the ratio of the measured intensity values obtained for the return signals of two different wavelengths.

Step 2: Determine the distance value using natural logarithm as follows:

Therefore, the processing unit 107 can estimate the distance (X) between the distal end 113 of the optical fiber 103 and the target 101 by simplifying Equations 1.1 and 1.2 as shown above. In Equation 2.2 above, "ln" refers to the natural logarithm. In some embodiments, distance (X) may be measured in millimeters. In some embodiments, "X" is the same distance for both wavelengths, and R (target reflection) is almost the same for both wavelengths when the selected wavelengths are close to each other on the "nm scale". In some embodiments, wavelengths may be considered to be close to each other on the "nm scale" when they are within 250 nm (eg, 1310 nm and 1340 nm or 1310 nm and 1550 nm). However, in many embodiments, wavelengths with closer R values can be selected. Therefore, 1310nm and 1340nm can be chosen over 1310nm and 1550nm. By way of some examples of the present disclosure, two laser sources (eg, 201a and 201b or 201a' and 201b') may be arranged to emit light having wavelengths within 100 nm of each other.

The condition of the fiber 103 may be affected by factors such as changes or degradation of the distal end 113 and/or the proximal end 111 of the fiber 103 , the effect of fiber bending on polarization scrambling, or any other degradation and change occurring in the fiber 103 . Variations in the optical condition of the fiber 103, particularly at the tip/end of the fiber 103, may have an effect on the quality of the radiation beam, the intensity of the internally reflected beam, the amount of back-reflected light from the target entering the fiber, the amount of energy reaching the target one or more of the quantity and accuracy of measurement. This may affect the accuracy of the distance estimate, possibly leading to incorrect positioning of the optical fiber 103 or miscalculation of energy optimization during treatment, which is based on the distance estimate described in U.S. Provisional Patent Application No. 63/118,117, incorporated by reference. into this article.

Internal reflections from planes associated with the optical fiber (eg, the proximal or distal end of the fiber) or other optical elements (eg, lenses or shields) optically connected to the fiber can generate parasitic and unwanted reflections. Additionally, these internal reflections may change over time due to degradation of the fiber optic or other components. In addition, fiber degradation may alter 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 fiber as beams 223a and 223b.

Thus, for some embodiments, at block 309, method 300 may measure the initial internal reflection of each laser prior to initiation of treatment to maintain accurate distance measurements during fiber degradation and internal reflection changes. In many such embodiments, initial internal reflectance values (or base values) can be recorded and used to monitor changes over time. For example, the processing unit 107 may include circuitry (eg, registers, memory, etc.) that stores an indication of the initial internal reflection value. In several embodiments, this process may be performed for one or more optical fibers 103 to be used with the laser system. For example, this process can be performed for each optical fiber 103 to be used with a laser system. Various embodiments described herein may monitor changes in initial internal reflection values (eg, stored in circuitry of processing unit 107, etc.) to dynamically correct distance measurements as provided herein.

In some embodiments, the processing unit 107 is configured to read (eg, from a register, from memory, etc.) the baseline value of such parasitic (eg, unwanted) reflections using a system preprocessing calibration procedure. In some embodiments, the system pretreatment calibration process may include setting the treatment fiber in water without a target. In this context, "no target" can be interpreted to mean that the nearest target (e.g., stone, tumor, etc.) may be located far enough from the fiber tip that no or substantially no light is reflected away target and is reflected back into fiber 103 as signal 223a. For IR sources (eg, 1310nm and 1340nm sources), such a distance may be, for example, 10mm from the distal end 113 of the optical fiber 103, or greater. However, if visible light (eg, 400-700nm) is used, lengths greater than 10mm may be used. Thereafter, under these conditions, the system can activate the lasers (e.g., 201a and 201b or 201a' and 201b') and measure the reflected signal 223, as described above. Since reflected light 223a is very low under these conditions (e.g., active laser light in the presence of water but no target), the signal reaching the photodetector is primarily related to internal reflections associated with the fiber (e.g., from port 219, proximal end 111, distal end 113, etc.).

In this case, an internally reflected (IR) beam may be detected using a photodetector, and the measured intensity values may be stored by the processing unit 107 as IR _(HI) and IR _(LO) (e.g., in registers, or in memory circuits, etc.). IR _(HI) may be the internal reflection intensity of incident light with a higher water absorption coefficient when there is no target near the fiber tip (e.g., distal end 113), while IR _(LO) may be the ) is the internal reflection intensity of incident light with a low water absorption coefficient when there is no target nearby. Thereafter, during therapy or treatment, when the laser is activated while the distal end 113 of the fiber is placed at a closer distance from the target 101, the return signal 223a can be reflected back through the fiber and detected using light as described herein device to detect.

In addition to calculating the measured intensity value as described above, the processing unit 107, at block 309, may store (e.g., in a register, in a memory circuit, etc.) the measured intensity value as I _(HI) , which may be An indication of the intensity of the return signal from the target 101 (e.g., tissue, stone, etc.) corresponding to the wavelength with the higher water absorption coefficient (HI), and store I _(LO) , which may be from the target 101 (e.g., tissue, stones, etc.) is an indication of the intensity of the return signal corresponding to the wavelength with the lower water absorption coefficient (LO). However, in order to remove spurious (or unwanted) reflection values from the reading of the actual return signal 223, the processing unit 107 may subtract and/or subtract IR _(HI) from the reading of the actual return signal I _(HI) , respectively (as follows shown in Equation 3.1 above) and subtract and/or subtract IR( _LO) from the actual returned reading of the signal I _(LO) as shown in Equation 3.1 and Equation 3.2 below.

I' _(HI) = I _(HI) -IR _(HI) Formula 3.1

I' _(LO) = I _(LO) -IR _(LO) Formula 3.2

In Equation 3.1 above, I' _(HI) refers to the newly calculated intensity of the return signal corresponding to the wavelength with the higher water absorption coefficient (HI) (without spurious (or unwanted) reflections); I _(HI) is refers to the measured intensity of the return signal (with spurious (or unwanted) reflections) corresponding to wavelengths with a higher coefficient of absorption (HI); and IR _(HI) refers to the interior of the incident light with a higher coefficient of absorption The measured intensity of the reflection (measurement under "no target").

Similarly, in Equation 3.2 above, I' _(LO) refers to the newly calculated intensity of the return signal (without spurious (or unwanted) reflections) corresponding to the wavelength with the lower water absorption coefficient (LO); I _{( LO)} refers to the measured intensity of the return signal (with spurious (or unwanted) reflections) corresponding to a wavelength with a lower coefficient of absorption (LO); and IR _(LO) refers to the incident signal with a lower coefficient of absorption (LO). The measured intensity of the internal reflection of light (measurement under "no target").

Therefore, using the new calculated values of intensity I' _{( HI)} and I' _{( LO)} , the processing unit 107 can determine the fiber The distance between the far end 113 of 103 and the target 101 is as follows:

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

As mentioned above, the internal reflection may not be constant over time and may vary due to some variation in the system's internal optical parameters (as opposed to due to dynamic changes in the treatment environment external to the system), such as the optical quality of the distal end 113 of the optical fiber 103 . Due to one or more of the power level of the treatment beam 233, cavitation effects occurring at the distal end 113 (or tip) of the fiber 103, and the liquid environment in which the fiber is placed during treatment, the fiber experiences various amounts of Degeneration, mainly at the distal end 113 (or tip). Thus, in several embodiments, "real-time" or "dynamic" calibration may be performed by repeatedly monitoring the reflex signal 223 during therapy and dynamically accounting for or adjusting for changes in such internal reflexes. For example, to perform such real-time calibration, as shown in configurations 200D-200G, a calibration laser (e.g., laser source 201c or laser source 201c') may be utilized to facilitate more accurate distance estimates that account for such degradation of fiber 103 .

As explained with respect to configurations 200D-200G, the collimating laser beam (eg 225c or 225c') has a wavelength that has a very high absorption coefficient in water. As an example, the wavelength of the polarized laser source 201c or the unpolarized laser source 201' may be 1435nm. Since the laser beams generated by the collimation lasers 201c and 201c' are so strongly absorbed by the liquid environment, as explained above, there is hardly any back reflection 223a associated with these laser beams back into the fiber. Thus, while the calibration laser source (e.g., 201c or 201c') is active, the reflection signal 223 having the wavelength of the calibration laser source 201c or 201' is primarily associated with (or indicative of) internal reflections.

In several embodiments, the processing unit 107, at block 309, may be configured to read and store one or more base values of the internal reflection of the framework 100 associated with the laser source 201c or 201c' prior to initiation of therapy. These one or more base values may represent the "quality" of the optical fiber 103 (eg, the optical quality of the distal end 113) before treatment begins, and may be stored by the processing unit 107 (eg, in a register, in a memory circuit, etc.). Furthermore, the processing unit 107 may be configured to continue to measure in "real time" the internal reflection of the light emitted by the calibration laser source 201c or 201c' during the treatment to identify deviations from the base value. Monitoring these deviations provides an indication as to the degradation of the optical quality of the fiber and can be used to correct any measured back reflection intensity associated with signal 223a. In many embodiments, the processing unit 107 may correct the calibration parameters of the master laser sources 201a and 201b or 201a' and 201b' based on readings of the internal reflection of light emitted by the calibration laser sources 201c or 201c'.

In some embodiments, method 300 may include a block for a calibration process. For example, the processing unit 107 may read and store one or more internal reflection values associated with the light emitted by the calibration laser 201c or 201c' where the system is activated in water. Since the calibration lasers 201c and 201c' are highly absorbed in water, relative to the measurement of the reflected signal associated with the light emitted by the lasers 201a and 201b or 201a' and 201b', during the calibration reading of 201c or 201c', the The sensitivity to the distance of the target 101 may be much lower. As will be explained in more detail below, this may provide for continued calibration of the laser measurements during treatment, when the target may also be close to the fiber tip.

Thereafter, target 101 may be irradiated with lasers 201a and 201b or 201a' and 201b' using one of exemplary configurations 200D-200G. In this case, the reflected beams 223a and 223b can be detected using photodetectors, and the processing unit 107 can store the measured intensity values as I _(HI) , I _(LO) and the addition and correlation of the internal reflection of the calibration laser The measured value of IR _(CAL) . I _(HI) can be the backreflection intensity from a target with incident light having a higher water absorption coefficient, I _(LO) can be the backreflection intensity from a target with incident light having a lower water absorption coefficient, and IR _(CAL) can be is the internal reflection intensity of the incident light from the collimation laser 201c or 201c'.

In some embodiments, the presence or absence of the target 101 may not affect the reflected IR _(CAL) because incident light from the calibration laser source 201c or 201c' is highly absorbed by water. As a result, changes in the IR _(CAL) value may be the result of degraded changes in the optical fiber 103, particularly the tip (eg, distal end 113, etc.) of the optical fiber 103. In some embodiments, processing unit 107 may adjust previously measured IR _(HI) and IR _(LO) values or currently measured I _(LO) or I _(HI) based on the relative change in IR _(CAL) values.

Thereafter, during treatment (e.g., when the laser is activated to treat the target 101), when the target 101 is present (e.g., when the target 101 is at a close enough distance to generate the back-reflected signal 223a, such as when the target is at a distance from the optical fiber 103 distal end 113 is less than or equal to the distance of 10 mm), the back reflection beam 223a for the laser source 201a or 201a' and the laser source 201b or 201b' and the internal reflection 223c from the calibration laser source 201c or 201c' can use light The detector is detected. At block 309, the processing unit 107 may store the measured intensity value as I _(HI) , which may represent the intensity of the return signal corresponding to its wavelength having a higher water absorption coefficient (HI), and I _(LO) , which may Represents the intensity of the return signal corresponding to its wavelength with a lower coefficient of absorption (LO), and IR _(CAL) , which may represent light corresponding to its wavelength with a higher static coefficient of absorption (for example, generated by the calibration laser source 201c or 201c 'Emitted light) returns the intensity of the internally reflected signal. Furthermore, to determine the calibration factor, the processing unit 107 may divide the IR from the calibration process preprocessed _(CAL-PRE) by the IR from the calibration process done during treatment _(CAL-DUR) , as shown in Equation 4 below.

The calibration factor may be "1" when the internal reflection of the calibration laser source 201c or 201c' is the same before and during the treatment, and the optical fiber 103 is not changed. Furthermore, in order to correct the parameters of the master lasers 201a and 201b or 201a' and 201b' based on the calibration factors, the processing unit 107 may use the calibration factors as shown in Equations 5.1 and 5.2 below.

I" _(HI) = I _(HI) -IR _(HI) × CF Formula 5.1

I" _(LO) = I _(LO) -IR _(LO) × CF Formula 5.2

In Equation 5.1 above, I” _(HI) refers to the new calibrated intensity of the backreflected signal from the target, corresponding to light with a wavelength with a higher water absorption coefficient (HI); I _(HI) refers to the backreflected signal from the target The measured intensity of the reflected signal, corresponding to light having a wavelength with a higher water absorption coefficient (HI); IR _(HI) refers to the measured intensity of the internal reflection of the incident laser light having a wavelength with a higher water absorption coefficient ( Measurements under "no target"); and CF refers to the calibration factor determined using Equation 4.

In Equation 5.2 above, I” _(LO) refers to the new calibrated intensity of the backreflected signal from the target, corresponding to light having a wavelength with a lower water absorption coefficient (LO); I _”(LO) refers to the backreflected signal from the target The measured intensity of the reflected signal, corresponding to light having a wavelength with a lower water absorption coefficient (LO); IR _(LO) refers to the measured intensity of the internal reflection of an incident laser light having a wavelength with a lower water absorption coefficient ("without Target"); and CF refers to the calibration factor determined using Equation 4.

Therefore, using the new calibrated intensity values I" _(HI) and I" _(LO) , the processing unit 107 at block 309 may substitute the new calibrated values I" _(HI) or I" _(LO) into Equation 2.2 To determine the distance between the far end 113 of the optical fiber 103 and the target 101, as follows:

Thus, in this manner, system preprocessing calibrations and real-time calibrations can be performed and utilized to update calibration factors in real-time (eg, via processing unit 107) to dynamically account for changes in fiber during operation (eg, degradation, etc.). In several embodiments, pre-processing and real-time calibration may be performed to ensure the accuracy of the estimated distance between the distal end 113 of the fiber 103 and the target 101 as the fiber undergoes degradation.

At block 311 , the method includes indicating, by the processing unit 107 via the indicator, the estimated (eg at block 309 ) distance between the distal end 113 of the optical fiber 103 and the target 101 . For example, the processing unit 107 causes the estimated distance between the distal end of the optical fiber 103 and the target 101 to be indicated via an indicator 109 associated with the processing unit 107 . As specific examples, the indicators 109 may include one or more of visual indicators, audio indicators, and tactile indicators. Accordingly, at block 311, the processing unit 107 may send a control signal to the indicator 109 to cause the indicator to indicate (e.g., display, audible transmission, tactile transmission, etc.) an indication of the estimated distance,

In some embodiments, based on the estimated distance between the distal end of the optical fiber 103 and the target 101, one or more of the position of the optical fiber 103, the orientation of the optical fiber 103, the characteristics of the treatment beam, etc. may be changed in real time to accurately and efficiently The treatment beam on the target 101 can be more effectively influenced, such as by more precise aiming.

FIG. 3B shows a flowchart illustrating a method 350 of estimating a distance between an optical fiber end and a target according to some embodiments of the present disclosure. Method 350 is described with reference to architecture 100 and various configurations of LETD 105 described above. However, it should be understood that method 300 may be implemented using LETDs other than those described herein. The embodiments are not limited in this context.

At block 351, the method 350 includes determining a first intensity value based on first reflected laser light corresponding to a first wavelength of laser light that exits the distal end 113 of the optical fiber 103 and that is captured by the target 101 reflects and enters the distal end 113 of the optical fiber 103 . For example, the processing unit 107 may determine the first intensity value based on the reflected laser light 223a corresponding to light whose wavelength has a high water absorption coefficient. In some embodiments, laser light corresponding to wavelengths with high water absorption coefficients may be generated by laser light source 201a or 201a', as discussed above.

At block 353, the method 350 includes determining a second intensity value based on second reflected laser light corresponding to a second wavelength of laser light that exits the distal end 113 of the optical fiber 103 and that is captured by the target 101 Reflects and enters the distal end 113 of the fiber. For example, at block 350 the processing unit 107 may determine a second intensity value based on the reflected laser light 223 corresponding to light whose wavelength has a low water absorption coefficient. In some embodiments, laser light corresponding to wavelengths with low water absorption coefficients may be generated by 201b or 201b', as discussed above.

At block 355, the method 350 includes calculating a ratio of the first intensity value and the second intensity value. For example, at block 355, the processor 107 may calculate the ratio of the first intensity value and the second intensity value using Equation 2.1. At block 357 , the method 350 includes estimating the distance between the distal end 113 of the optical fiber 103 and the target 101 based on the ratio of the first intensity value and the second intensity value derived at block 355 . For example, at block 357, the processor 107 may utilize Equation 2.2 to estimate the distance between the distal end 113 of the optical fiber 103 and the target 101 based on the ratio of the first intensity value and the second intensity value.

FIG. 3C shows a flowchart illustrating a method 380 of estimating a distance between an optical fiber end and a target according to some embodiments of the present disclosure. Method 380 is described with reference to architecture 100 and various configurations of LETD 105 described above. However, it should be understood that method 300 may be implemented using LETDs other than those described herein. The embodiments are not limited in this context.

At block 381 , method 380 includes illuminating the target with a plurality of laser light of different wavelengths. For example, one of configurations 200A-200G may be used to illuminate target 101 with multiple different wavelengths of laser light 221 . In several embodiments, multiple different wavelengths of laser light 221 may include one or more of beams 225a, 225b, 225c, 231, and/or 233.

At block 383, the method 380 includes receiving the reflected beam from the target via the optical fiber. For example, one of configurations 200A- 200G may be used to receive reflected light beam 223 (eg, corresponding to light reflected from target 101 ) and transmit back via optical fiber 103 . In several embodiments, reflected light beam 223 may reflect from target 101 and enter distal end 113 of optical fiber 103, and thus may include reflected light 223a. Reflected light 223a may also include light reflected from optical components within the system (eg, proximal end 111, distal end 113, etc.), and may include reflected light 223c corresponding to the reflected light associated with collimated beam 225c.

At block 385 , method 380 includes measuring the intensity of reflected light beam 223 with one or more photodetectors. In many embodiments, one or more photodetectors may be used to measure the intensity of reflected light beam 223 using one of configurations 200A-200G. For example, first light detector 215 and second light detector 217 may be used to measure the intensity of reflected light beam 223 . In another example, a third light detector 227 may be used to measure the intensity of the reflected light beam 223 .

At block 387 , the method 380 includes estimating the distance between the distal end 113 of the optical fiber 103 and the target 101 based on the intensity of the reflected light beam 223 measured with the one or more photodetectors. For example, the processing unit 107 may be used to estimate the distance between the distal end 113 of the optical fiber 103 and the target 101 based on the intensity of the reflected light beam 223 measured with one or more light detectors. In some embodiments, processing unit 107 may be included in one or more portions of computer system 400 .

FIG. 4 is a block diagram of an exemplary computer system 400 for implementing embodiments consistent with the present disclosure. Computer system 400 , or one or more portions thereof, may include processing unit 107 . Stated differently, the processing unit 107 may be implemented by the computer system 400 . In some such embodiments, computer system 400 may be used to estimate the distance between distal end 113 of optical fiber 103 and target 101 . The embodiments are not limited in this context.

Computer system 400 may include a central processing unit (“CPU” or “processor”) 402 . Processor 402 may include at least one data processor arranged to execute instructions or program components to perform the operations described above (eg, with respect to methods 300, 350, and/or 380). Users can include humans, people using devices such as those included in this disclosure (eg, doctors, nurses, technicians, etc.), or the devices themselves. The processor 402 may include a special-purpose processing unit, such as an integrated system (bus) controller, a memory management control unit, a floating-point unit, a graphics processing unit, a digital signal processing unit, an application-specific integrated circuit (ASICS), a field-programmable gate array (FPGA) ) or a commercial processing unit. Processor 402 may be configured and arranged to communicate with input device 411 and/or output device 412 (eg, via I/O interface 401 , etc.). I/O interface 401 may employ communication protocols or methods such as, but not limited to, audio, analog, digital, stereo, IEEE-1394, serial bus, universal serial bus (USB), infrared, PS/2, BNC, coaxial , Component, Composite, Digital Visual Interface (DVI), High Definition Multimedia Interface (HDMI), Radio Frequency (RF) Antenna, S-Video, Video Graphics Array (VGA), IEEE 802.xx/b/g/n/x, Bluetooth , cellular (eg, Code Division Multiple Access (CDMA), High Speed Packet Access (HSPA+), Global System for Mobile Communications (GSM), Long Term Evolution (LTE), WiMax, etc.), etc.

Using I/O interface 401 , computer system 400 can communicate with input devices 411 and/or output devices 412 . In some embodiments, processor 402 may be configured and arranged to communicate with communication network 409 (eg, via network interface 403 , etc.). The network interface 403 may be used to communicate via a communication network 409 . Network interface 403 may employ connection protocols including, but not limited to, direct connect, 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. Using network interface 403 and communication network 409 , computer system 400 may communicate with LETD system 105 and/or indicator 109 . In some embodiments, one or more portions of computer system 400 may be integrated into LETD system 105 . In some such embodiments, one or more components of the LETD system 105 (eg, power detectors and/or light detectors) may include an input device 411 .

The communication network 409 may be implemented as one of different types of networks, such as an intranet or a local area network (LAN), a closed area network (CAN), or the like. Communications network 409 can be a dedicated network or a shared network that represents a network 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. ) to associate different types of networks communicating with each other. Additionally, communication network 409 may include various network devices including routers, bridges, servers, computing devices, storage devices, and the like. In some embodiments, the processor 402 may be configured to communicate with a memory 405 (eg, RAM, ROM, etc. not shown in FIG. 4 ) via a storage interface 404 . The storage interface 404 may connect to the computer using connection protocols 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. Storage 405, including but not limited to storage drives, removable disk drives, and the like. Memory drives may also include magnetic drums, magnetic disk drives, magneto-optical drives, optical drives, redundant array of independent disks (RAID), solid-state storage devices, solid-state drives, and the like.

Memory 405 may store a collection of program or database components, including but not limited to user interface 406, operating system 407, web browser 408, instructions 415, and the like. In various embodiments, instructions 415 may include instructions that when executed by processor 402 cause processor 402 to perform one or more techniques, steps, procedures and/or methods described herein, such as estimating distance or performing calibration. For example, instructions to perform methods 300 , 350 and/or 380 may be stored in memory 405 . In many embodiments, memory 405 includes at least one non-transitory computer-readable medium. For example, memory 405 may be a memory device including memory circuitry arranged to store instructions 415 non-transitory. In some embodiments, computer system 400 may store user/application data, such as data, variables, records, etc. as described in this disclosure. Such a database may be implemented as a fault-tolerant, relational, scalable, secure database, such as Oracle or Sybase.

Operating system 407 can facilitate resource management and operation of computer system 400 . Examples of operating systems include, but are not limited to OS/> UNIX-like distributions (for example, BERKELEYSOFTWARE/> (BSD), /> OPENBSD, etc.), /> DISTRIBUTIONS (for example, RED/> wait), (/> /7/8, 10, etc.), GOOGLE ^™ ANDROID ^™ , /> OS etc. User interface 406 may facilitate the display, execution, interaction, manipulation, or operation of program components through textual or graphical tools. For example, the user interface may provide computer-interactive interface elements such as cursors, icons, check boxes, menus, scroll bars, windows, widgets, etc. on a display system operatively connected to computer system 400 . A graphical user interface (GUI) may be employed, including but not limited to operating system's /> (e.g. Aero, Metro, etc.), web interface libraries (e.g. /> AJAX, HTML, etc.

In some embodiments, computer system 400 may implement program components stored by web browser 408 . Web browser 408 may be a hypertext viewing application such as INTERNET/> GOOGLE ^™ CHROME ^™ , /> wait. Secure web browsing may be provided using Hypertext Transfer Protocol Secure (HTTPS), Secure Sockets Layer (SSL), Transport Layer Security (TLS), and the like. The web browser 408 can utilize information such as AJAX, DHTML, Tools such as application programming interfaces (APIs). In some embodiments, computer system 400 may implement program components stored by a mail server. The mail server may be an Internet mail server such as Microsoft Exchange. Mail servers can utilize features such as Active Server Pages (ASP), /> C++/C#, /> .NET, CGI SCRIPTS, PHP, /> and other tools. Mail servers may utilize communications protocols such as Internet Message Access Protocol (IMAP), Messaging Application Programming Interface (MAPI), Exchange, Post Office Protocol (POP), Simple Mail Transfer Protocol (SMTP), etc. In some embodiments, computer system 400 may implement a mail client stored program component. A mail client can be a mail viewing application such as MAIL, /> wait.

Additionally, one or more computer-readable storage media may be used to implement embodiments consistent with the present disclosure. A computer-readable storage medium refers to any type of physical memory that can store information or data readable by a processor. Accordingly, a computer-readable storage medium may store instructions for execution by one or more processors, including instructions for causing a processor to perform steps or stages consistent with embodiments described herein. The term "computer-readable medium" should be understood to include tangible items and exclude carrier waves and transient signals, ie non-transitory. Examples include random access memory (RAM), read only memory (ROM), volatile memory, nonvolatile memory, hard drives, compact disc (CD) ROMs, digital video discs (DVD), flash drives, magnetic disks, and any other known physical storage media.

In various embodiments, the present disclosure can provide various technical effects and improvements. For example, the present disclosure may enable the estimation of the distance between the distal end of an optical fiber and a target by using two different wavelengths of laser light (eg, one with a low coefficient of water absorption and another with a high coefficient of water absorption). Distance estimation based on such wavelength selection can provide robustness with respect to different types of targets, target components, target colors, target surfaces, and the like. The wavelength modulation based techniques and systems disclosed in this disclosure can be provided to estimate the distance between the far end of an optical fiber and a target, and can facilitate accurate distance estimation. Furthermore, the present disclosure provides an estimation process of the distance between the distal end of the optical fiber and the target for various types of targets, and can provide distance estimates for more and more varied targets than conventionally possible. Accordingly, the present disclosure provides systems and methods for targeting targets more precisely than conventionally possible. More precise aiming can eliminate or reduce ablation and/or fragmentation of incorrect portions of the target, which itself can lead to adverse outcomes and/or permanent damage. Additionally, more precise aiming consumes less time in ablating and/or fragmenting the target.

In several embodiments, the present disclosure may be used to pinpoint and/or aim a treatment beam, such as in low visibility environments (eg, environments that include dust or target debris). For example, during treatment of a target such as a kidney stone, the water may become cloudy due to the presence of stone fragments or dust. This may reduce (or prevent) the ability to see targets such as kidney stones. In this case, the present disclosure provides a system to accurately identify and inform the treating physician of the placement of the fiber (eg, whether the fiber was placed in front of the target or if the target was not detected).

Furthermore, in many embodiments, the present disclosure can be used for distance measurements. For example, a target (eg, a kidney stone) may move around during treatment, which may cause laser light associated with the treatment beam to impinge on unwanted areas (eg, healthy tissue, etc.) instead of the target. Thus, the present disclosure may enable automatic and real-time monitoring of the distance between the fiber and the target, which in turn may reduce or eliminate the possibility of lasing unwanted areas.

Still further, in various embodiments, the present disclosure may be used for the purpose of controlling and/or adjusting one or more operating parameters. For example, during treatment, the target may move back and forth, or may change its shape and size. Therefore, the parameters preset for the laser source before starting to lase on the target may become less effective. Traditionally, such preset parameters are changed manually, which can be error-prone and time-consuming, or in some cases, the preset parameters may remain constant, which can lead to situations where the fiber is too close or too far from the target . Therefore, automatic and real-time monitoring of the distance between the optical fiber and the target, as disclosed in this disclosure, can enable automatic changes in laser preset parameters to adjust laser emission according to target shape, position, etc., to obtain the best effect.

With respect to the use of substantially any plural and/or singular term herein, those skilled in the art can translate from the plural to the singular and/or from the singular to the plural as appropriate depending on the context and/or application. Various singular and/or plural permutations are expressly set forth herein for purposes of clarity and not limitation.

Those skilled in the art will understand that terms used herein are generally and generally intended to be "open" terms (for example, the term "comprising" should be interpreted as "including but not limited to", the term "having" should be interpreted as should be interpreted as "having at least", the term "comprising" should be interpreted as "including but not limited to", etc.). Those skilled in the art will further understand if a specific number of claim recitations are intended to be introduced. For example, as an aid to understanding, the detailed description may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, use of such phrases should not be construed to imply that a claim statement introduced by the indefinite article "a" or "an" limits any particular claim containing such introduced claim statement to containing only one such stated disclosure even when the same claim includes the introductory phrase "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and/or "an" usually should be construed to mean "at least one" or "one or more"); so is the use of the definite article to introduce claim recitations. Furthermore, even if a specific number of an introduced claim recitation is expressly recited, those skilled in the art will recognize that such a recitation should generally be construed to mean at least that recited number (e.g., "two recitations without other modifiers") ", usually means at least two statements, or two or more statements).

All of the devices and/or methods disclosed and claimed herein can be fabricated and performed without undue experimentation in light of the present disclosure. Although the apparatus and methods of the present disclosure have been described in terms of preferred embodiments, it will be apparent to those skilled in the art that variations may be applied to the apparatus and/or methods and steps or sequence of steps of the methods described herein. , without departing from the concept, spirit and scope of the present disclosure. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the disclosure as defined by the appended claims.

Claims (15)

1. A system comprising: a first laser source for generating laser light at a first wavelength; a second laser source for generating laser light at a second wavelength; an optical fiber having a distal end configured to transmit laser light from the first and second laser sources out of the distal end and receive reflected laser light into the distal end; a light detector for measuring the intensity of the reflected light; and a processor and a memory comprising instructions which, when executed by the processor, cause the processor to estimate the distance between the distal end of the optical fiber and the target based on the intensity of the reflected light measured by the light detector the distance between. 2. The system of claim 1, wherein a first coefficient of water absorption at the first wavelength is higher than a second coefficient of water absorption at the second wavelength. 3. The system of claim 2, wherein a ratio of the first coefficient of water absorption to the second coefficient of water absorption is at least 2 to 1. 4. The system of any one of claims 1 to 3, wherein the first wavelength is from about 1330 nm to about 1380 nm and the second wavelength is from about 1260 nm to about 1320 nm. 5. The system according to any one of claims 2 to 4, comprising: a third laser source for generating laser light of a third wavelength, which is used to characterize the state of the optical fiber, wherein the third wavelength It has a third water absorption coefficient higher than the first water absorption coefficient and the second water absorption coefficient. 6. The system of claim 5, wherein the third wavelength comprises a wavelength of about 1435 nm, about 2100 nm, or between about 1870 nm and about 2050 nm. 7. The system according to any one of claims 1 to 6, wherein the light detector measures a first intensity value of reflected light corresponding to the laser light of the first wavelength and a value of the reflected light corresponding to the second wavelength. The second intensity value of the reflected light corresponding to the laser. 8. The system of claim 7, wherein the instructions, when executed by the processor, further cause the processor to: calculating a ratio of the first intensity value and the second intensity value; and A distance between the distal end of the optical fiber and the target is estimated based on the ratio of the first intensity value and the second intensity value. 9. The system of any one of claims 1 to 8, wherein 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 lasers or free space lasers. 10. 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, the WDM combining the laser light at the first wavelength with the The laser light of the second wavelength is arranged to enter the proximal end of the optical fiber at one or more of the same point and the same angle. 11. A method comprising: Irradiate the target with multiple lasers of different wavelengths; receiving a reflected beam from the target via an optical fiber; measuring the intensity of said reflected beam with one or more photodetectors; and A distance between the distal end of the optical fiber and the target is estimated based on the intensity of the reflected light beam measured with the one or more photodetectors. 12. The method of claim 17, comprising emitting a plurality of different wavelengths of laser light through the optical fiber to illuminate the target. 13. A method according to any one of claims 17 to 18, comprising measuring a first intensity value of the reflected beam corresponding to the laser light of the first wavelength and a second intensity value of the reflected beam corresponding to the laser light of the second wavelength value. 14. The method of claim 13, wherein the first wavelength is from about 1330 nm to about 1380 nm and the second wavelength is from about 1260 nm to about 1320 nm. 15. A method according to any one of claims 13 to 14, comprising: calculating a ratio of the first intensity value and the second intensity value; and A distance between the distal end of the optical fiber and the target is estimated based on the ratio of the first intensity value and the second intensity value.