CN116457627A - Method and system for estimating distance between end of optical fiber and 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 distance between end of optical fiber and target

Cross Reference to Related Applications

The present application claims priority from U.S. patent application Ser. No. 63/118,857 entitled "Method and System for Estimating Distance Between aFiber End and a Target," filed on even date 27 at 11/2020, 35U.S. C. ≡119, the entire contents of which are incorporated herein by reference.

The present application claims the benefit of priority entitled "Apparatus and Method for Enhancing Laser BeamEfficacy in a Liquid Medium" from U.S. c. ≡119, U.S. provisional patent application No. 63/118,117, filed on 25/11/2020, the entire contents of which are incorporated herein by reference.

The present application claims the benefit of priority entitled "Method and System for Estimating Distance Between aFiber End and a Target" from U.S. patent application Ser. No. 63/252,830, filed on 6/10/2021, 35U.S. C. ≡119, the entire contents of which 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 a method and system for estimating the distance between an end of an optical fiber and a target.

Background

The introduction of lasers into the medical field and the development of fiber optic technology using lasers has opened up many applications in therapy, diagnosis, therapy, etc. Such applications range from invasive and non-invasive treatments to endoscopic surgery and image diagnostics. For example, in urinary calculus treatment, it is desirable to break up the calculus into smaller pieces. One technique, known as laser lithotripsy, may be used for such fragmentation procedures, wherein for small and medium sized uroliths, a rigid or flexible ureteroscope is placed through the urinary tract for illumination and imaging. At the same time, the optical fiber is inserted through the working channel of the ureteroscope to a target location (e.g., where stones are present in the bladder, ureter, or kidney). The laser is then activated to fracture the stone into smaller pieces or to dust it. In another case, laser and fiber techniques are used for coagulation or ablation treatment. During ablation therapy, laser light is delivered to the tissue to vaporize the tissue. During coagulation treatment, lasers are used to cause thermal damage within the tissue. Such ablative treatment may be used to treat a variety of clinical conditions, such as Benign Prostatic Hyperplasia (BPH), cancer (such as prostate cancer, liver cancer, lung cancer, etc.), and to treat cardiac conditions by ablating and/or coagulating portions of tissue in the heart.

These treatments using laser and fiber optics techniques require high precision to ensure that the laser is aimed at the correct target (stone, tissue, tumor, etc.), thus achieving clinical goals of tissue ablation, coagulation, stone fragmentation, dust removal, etc. It is therefore important to know the distance between the target and the end (distal end) of the fiber at which the laser is being launched, since laser treatment parameters such as energy, pulse width, laser power modulation and/or repetition rate are typically determined based on the distance between the fiber tip and the target.

One of the prior art techniques for estimating the distance between the distal end of an optical fiber and a target provides for measuring and comparing the reflected intensity values of the light beam, wherein the light beam is transmitted through the optical fiber by modulating the numerical aperture of the light beam. However, it is not always convenient to change the numerical aperture of the beam. Furthermore, the separation of the beam reflections of the different numerical apertures required for these techniques is difficult.

Disclosure of 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 used as an aid in determining the scope of the claimed subject matter.

In one aspect, the present disclosure relates to a system comprising: the device comprises a first laser source, a second laser source, an optical fiber, a light detector, a processor and a memory. The first laser source may generate laser light of a first wavelength and the second laser source may generate laser light of a second wavelength. The optical fiber may have a distal end and be 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. The light detector may measure the intensity of the reflected light. The processor and the memory may include instructions that, when executed by the processor, cause the processor to estimate a 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.

In some embodiments, the first water absorption coefficient of the first wavelength is higher than the second water absorption coefficient of the second wavelength. In some such embodiments, the ratio of the first water absorption coefficient to the second water absorption coefficient is at least 2 to 1. In further such embodiments, the first wavelength is about 1330nm to about 1380nm and the second wavelength is about 1260nm to about 1320nm. A still further embodiment includes a third laser source that generates laser light at a third wavelength that is used to characterize the state of the optical fiber, wherein the third wavelength has a third water absorption coefficient that is higher than the first water absorption coefficient and the second water absorption coefficient. In yet another embodiment, the third wavelength comprises a wavelength of about 1435nm, about 2100nm, or between about 1870nm and about 2050 nm.

In some embodiments, the photodetector measures a first intensity value of the reflected light corresponding to the laser light of the first wavelength and a second intensity value of the reflected light corresponding to the laser light of the second wavelength. In some such embodiments, 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 estimating a distance between the distal end of the optical fiber and the target based on a ratio of the first intensity value and the second intensity value.

In various embodiments, one or more of the first and second laser sources comprise a polarization maintaining pigtail fiber laser (polarization maintaining pigtailed fiber laser), a single mode pigtail fiber laser (single mode pigtailed fiber laser), or a free space laser.

Several embodiments include a Wavelength Division Multiplexer (WDM) coupled to the proximal end of the optical fiber that arranges the laser light of the first wavelength and the laser light of the second wavelength to enter the proximal end of the optical fiber at one or more of the same point and the same angle.

In another aspect, the present disclosure is directed to at least one non-transitory computer-readable medium comprising a set of instructions that, in response to execution by a processor circuit, cause the processor circuit to perform one or more of: determining a first intensity value based on a first reflected laser light corresponding to the laser light at a first wavelength, wherein the laser light at the first wavelength 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; determining a second intensity value based on a second reflected laser light corresponding to the laser light of a second wavelength, wherein the second wavelength laser light exits the distal end of the optical fiber and the second reflected laser light is reflected by the target and enters the distal end of the optical fiber; calculating a ratio of the first intensity value and the second intensity value; and estimating a distance between the distal end of the optical fiber and the target based on a ratio of the first intensity value and the second intensity value.

In some embodiments, the set of instructions, in response to execution by the processor circuit, further cause the processor circuit to: the first internal reflection value is subtracted from the first measured intensity value to determine a first intensity value and the second internal reflection value is subtracted from the second measured intensity value to determine a second intensity value.

In various embodiments, the set of instructions, in response to execution by the processor circuit, further cause the processor circuit to determine the internal reflection value based on a third reflected laser light corresponding to the laser light of a third wavelength, wherein the laser light of the third wavelength exits the laser 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 execution by the processor circuit, further cause the processor circuit to compare the internal reflection value to a baseline internal reflection value; and adjusting an operating parameter of the therapeutic beam based on a comparison of the internal reflection value to the baseline internal reflection value. In a further such embodiment, the set of instructions, in response to execution by the processor circuit, further cause the processor circuit to compare the internal reflection value to a baseline internal reflection value; characterizing a state of the optical fiber based on a comparison of the internal reflection value to the baseline internal reflection value; and communicating an indication of the status of the optical fiber via the user interface.

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

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

In some embodiments, the method comprises: a plurality of laser light of different wavelengths are emitted via an optical fiber to illuminate a target.

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

Drawings

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

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

Fig. 1B illustrates an exemplary optical fiber according to some embodiments of the present disclosure.

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

Fig. 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.

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

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

Detailed Description

The present disclosure provides methods and systems for estimating a distance between an end of an optical fiber and a target. It should be appreciated that the efficiency of treatment with lasers generally depends on the relative position and orientation of the fiber tip with respect to the target. However, determining or estimating the distance between the fiber tip and the target is extremely difficult due to various factors, such as movement of the fiber relative to the position and orientation within the subject (e.g., patient), tissue environment, movement of tissue, surface of the target, color of the target, pigment of the target, degradation of the fiber tip during treatment, water rinsing and cloudy environment (e.g., due to dust removal), etc. 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 targeting the laser at a region that is not the region of interest of the target. This may lead to unnecessary complications and in some cases also to permanent damage of certain parts of the subject's tissues, organs etc., which may cause dysfunction of the body parts of the subject. In some other cases, incorrect distance measurements and orientations may result in increased treatment duration or may result in poor quality ablation/fragmentation results. In some cases, such as BPH or cancer, if the tumor is not ablated properly, it may lead to regeneration of the tumor (or other undesirable tissue), leading to further complications. Thus, while performing certain treatments using laser and fiber techniques as discussed above, it is important to determine the precise (or maintain a desired) distance between the fiber tip and the target.

The method comprises the following steps: by a light emission, transmission and detection (LETD) system, different laser light sources are used, while the target is irradiated with laser light of different wavelengths having a low water absorption coefficient and a high water absorption coefficient. The wavelengths may be selected in such a way that they are close to each other and belong to the same "scale". In addition, the LETD system receives return signals corresponding to incident lasers of different wavelengths. The return signal includes a reflected beam of light from the target back illumination. One or more photodetectors configured in the LETD system may detect the return signal to measure the intensity value of the return signal at a particular wavelength. Using the measured intensity values, the processing unit may then estimate the distance between the end of the optical fiber and the target.

The present disclosure uses the described LETD system in different configurations, including different arrangements of various optical components, such as beam combiners, beam splitters, polarizers, collimators, wavelength Division Multiplexers (WDM), photodetectors, and the like. The present disclosure enables accurate estimation of the distance between the end of the optical fiber and the target. In addition, the present disclosure provides a robust distance estimation technique that is compatible with different types of targets. Further, 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. Thus, the laser source parameters preset before starting lasing of the target may become less effective. Traditionally, these preset parameters are manually altered, which can be error-prone and time-consuming, or in some cases, the preset parameters may remain unchanged, which can lead to situations where the fiber is too close or too far from the target. Thus, the present disclosure allows for automatic and real-time monitoring of the distance between the fiber tip and the target, and further enables automatic changing of preset laser emission parameters to adjust the laser according to the target shape, position, etc., and provides a higher likelihood of achieving a desired result or outcome from the treatment.

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

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

In some embodiments, the light beam may be a light beam directed from a light source. For example, the light source may be a laser light source. As examples, the laser light source may include, but is not limited to, a solid state laser, a gas laser, a diode laser, and a fiber laser. The light beam may include: one or more of the aiming beam, the 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 optical fiber 103 to estimate the distance between the fiber tip (e.g., distal end 113) and the target 101. In several embodiments, the treatment beam may comprise a high intensity light beam that is transmitted through the optical fiber 103 to treat the target 101. In some embodiments, the different light 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 sources may be used to generate light beams of different wavelengths, characteristics, etc.

Further, the optical fiber 103 may be associated with the LETD system 105, as shown in FIG. 1A, to receive a light beam, aim at the target 101, and deliver a reflected light beam reflected from the surface and surrounding areas of the target 101. In some embodiments, the optical fiber 103 may be optically, mechanically, and/or electrically coupled to the 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, one or more of a laser light source, a polarizer, a beam splitter, a beam combiner, a photodetector, a wavelength division multiplexer, a collimator, a circulator, configured in various combinations, as explained in detail in further portions 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 treatment beam for treating the target 101, and/or a beam having varying characteristics (e.g., intensity, wavelength, etc.) based on the application. Each laser source may be configured to generate laser light having a different wavelength, where each of the different wavelengths may have a different water absorption coefficient. Furthermore, each laser light source may have the same aperture or different apertures. In some embodiments, each laser source may be designated for a different purpose, e.g., 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 therapeutic beam of a particular intensity, and one or more laser sources may be configured to generate a beam of a particular wavelength having a particular water absorption coefficient. In addition, each laser light source may be configured to generate polarized laser light or unpolarized/depolarized light.

The polarizer may include an optical component that functions as an optical filter. For example, a polarizer may be configured to allow light beams of a particular polarization to pass through and to 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 an output.

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

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

The light detector may comprise a device that detects and/or measures a characteristic of the light beam and encodes the detected and/or measured characteristic in an electrical signal. For example, the light detector may detect a particular type of light beam (e.g., preconfigured) and convert the light energy associated with the detected light beam into an electrical signal. In some embodiments, wavelength division multiplexing may include techniques that combine multiple optical carrier signals onto a single optical fiber while using lasers of different wavelengths.

The collimator may comprise a device for narrowing the light beam. To narrow the beam, the collimator may be configured to make the direction of motion more uniform in a particular direction (e.g., parallel rays), or to make the spatial cross section of the beam smaller. In many embodiments, a collimator may be used to change the divergent light from a point source to a parallel beam.

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

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

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 the measurement values 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 a stand-alone 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 an electrical signal received from the LETD system 105. As another example, the processing device 107 may include circuitry and memory that includes instructions that, when executed by the circuitry, cause the circuitry to determine the distance based on an electrical signal received from the LETD system 105. Still, in some other embodiments, the processing unit 107 may be a computing device, such as a notebook computer, desktop computer, mobile phone, tablet phone, or the like, configured to perform distance estimation using its processing capabilities.

The processing unit 107 may be associated with an indicator 109 to indicate an estimated distance between the distal end of the optical fiber 103 and the target 101. The indicators 109 may include, but are not limited to, visual indicators that display the estimated distance, audio indicators that announce the estimated distance, or tactile indicators that indicate the estimated distance via vibration modes. In various embodiments, the pointer may be presented and/or overlaid on a graphical representation, such as a video feed, via a graphical user interface. In some embodiments, a computing device configured as the processing unit 107 may be configured to perform the functions of the indicator 109. In some other embodiments, the indicator 109 may be a stand alone device configured to indicate an estimated distance between the distal end of the optical fiber 103 and the target 101.

Various exemplary configurations for estimating the distance between the end of the optical fiber 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 limiting the present disclosure.

Fig. 2A-2G illustrate example configurations of portions of architecture 100 that include many configurations of the LETD system 105. It should be noted that the description of the previous diagram (e.g., fig. 2A) is often relied upon to fully describe another diagram (e.g., fig. 2E). However, examples are not limited in this respect.

Fig. 2A illustrates an exemplary configuration 200A for estimating a distance between an end of an optical fiber and a target in accordance with some embodiments of the present disclosure. In configuration 200A, the 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 fig. 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 beam splitter 211, a polarizing beam splitter 213, a first light detector 215, and a second light detector 217.

In configuration 200A, a first polarized laser source 201a is arranged to generate laser light 225a (or beam 225 a) having a wavelength with a high water absorption coefficient relative to the wavelength of laser light 225b generated by a second polarized laser source 201 b. As used herein, the laser light 225a generated by the first polarized laser source 201a may be referred to as high water absorption coefficient light (HI), while the laser light 225b generated by the second polarized laser source 201b may be referred to as low water absorption coefficient Light (LO). It should be understood that even though the terms "high" and "low" are used, they are intended to be interpreted relative to each other, or in the alternative, relative to a threshold characteristic describing the absorption of water at a particular wavelength. For example, the high water absorption characteristic may be greater than or equal to 50%, while the low water absorption characteristic may be less than or equal to 50%.

In various embodiments, the ratio of the high water absorption coefficient to the low water absorption coefficient may be about 1:2. For example, laser 225a may utilize a wavelength of about 1310nm and have a water absorption coefficient of about 0.1651, while laser 225b may utilize a wavelength of about 1340nm and have a water absorption coefficient of about 0.333. The higher the ratio between the high and low absorption coefficients, the lower the sensitivity to system noise (e.g., electrical or opto-mechanical noise) may result, but the resulting system may be ineffective at distances exceeding 3 mm. The lower the ratio between high and low absorption coefficients may result in higher sensitivity to system noise, but the resulting system may remain effective at distances up to 5 or 6 mm. In some examples, the first and second polarized laser sources 201a and 201b may be polarization maintaining (polarization maintaining, PM) pigtail fiber lasers.

The laser sources 201a and 201b are associated with and in optical communication with a first beam splitter 203. Stated differently, the laser beams 225a and 225b generated by the laser sources 201a and 201b, respectively, are provided as inputs to the first beam splitter 203, and the first beam splitter 203 is configured to split the incident beams 225a and 225b in a ratio of approximately 50:50 (e.g., 47:53 or 49:51) such that the incident beams 225a and 225b are aligned along a single optical path as beam 227. However, it will be appreciated that any ratio between 99:1 and 1:99 may be utilized without departing from the scope of the present disclosure. Similarly, while a 45 degree AOI may be described in the embodiments, it will be appreciated that any AOI between 1 and 89 may be utilized (such as 43-47 degrees, 40 degrees, or 20 degrees) without departing from the scope of the present disclosure.

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 an optical signal (e.g., the portion of the optical beams 225a and 225b routed to the power detector 205) corresponding to each optical wavelength in the optical beam 227. In some embodiments, the term "optical power" may refer to the energy transmitted 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 further arranged to provide a portion of beams 225a and 225b, denoted as beam 227, which is aligned along a single optical path as input to polarizer 207. In some embodiments, the polarity of polarizer 207 may be preconfigured. A polarizer 207 is associated with and in optical communication with the first beam combiner 209. In this way, polarized light 229 as output obtained from the polarizer 207 is provided as input to the first beam combiner 209.

As shown in fig. 2A, first beam combiner 209 may combine polarized beam 229 with aiming beam 231 and treatment beam 233 to combine beam 235. In some other embodiments, aiming beam 231 and treatment beam 233 may be generated by one or more laser sources (not shown) other than laser sources 201a and 201 b. 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 as limiting the present disclosure, as the treatment beam may be generated by a laser other than the HO laser, 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 201 b. The combined beam 235, including aiming beam 231, treatment beam 233, and polarized beam 229 from laser sources 201a and 201b, may be subjected to a second beam splitter 211 having a 50:50R/T ratio and 45 degree AOI configuration. That is, first beam combiner 209 may be associated with and in optical communication with second beam splitter 211 such that combined beam 235 is provided as an input to second beam splitter 211.

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 polarized beams 229 from the 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 a portion of beam 235, which is the output of second beam splitter 211, is transmitted through optical fiber 103 (e.g., via port 219), and is represented as beam 221, as shown in FIG. 2A. The optical beam 221 is transmitted to the proximal end 111 of the optical fiber 103 and then propagates through the length of the optical fiber 103 to be delivered from the distal end 113 of the optical fiber 103 to the target 101. As an example, the target 101 may be a tissue, a stone, a tumor, a cyst, etc., to be treated, ablated, destroyed, etc., in the subject.

When the light beam 221 is delivered to the target 101 via the optical fiber 103, the target 101 may reflect a portion of the incident light beam 221 away from the optical fiber 103 and reflect a portion of the light toward the optical fiber 103, wherein the portion of the light reflected toward the optical fiber 103 may re-enter the optical fiber 103 at the distal end of the optical fiber 103. The portion of reflected light that re-enters at the distal end may be referred to as reflected light 223a. The reflected light 223a may be transmitted "back" in the optical fiber 103 from the distal end of the optical fiber 103 to the proximal end of the optical fiber 103. When the reflected light 223a reaches the proximal end of the optical fiber 103, the reflected light 223a may be subjected to a 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.

To polarize reflected light 223a, the reflected light may first be subjected to a second beam splitter 211 to couple the path of Ji Fanshe light 223a and then to polarizing beam splitter 213. The reflected light 223a will be incident on the second beam splitter 211 at a 45 degree angle and split at a 50:50 ratio (or another ratio as outlined herein). The reflected light 223b from the second beam splitter 211 is then subjected to a 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, the first light detector 215 may be configured to detect the P-polarized beam of light 223b reflected by the polarizing beam splitter 213, while the second light detector 217 may be configured to detect the S-polarized beam of light 223b transmitted by the polarizing beam splitter 213. The first light detector 215 and the second light detector 217 may measure the intensity of the detection beam of light 223b, respectively, and transmit the intensities to the processing unit 107. In some embodiments, 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 intensities. The method of estimating the distance between the distal end of the optical fiber 103 and the target 101 based on the measured intensities is explained in more detail below with respect to fig. 3A-3C.

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

In configuration 200B, the LETD system 105 may include one or more polarized lasers, one or more beam splitters, a polarizer, one or more beam combiners, and one or more photodetectors. The one or more beam splitters may be polarizing beam splitters, non-polarizing beam splitters, or a combination of polarizing and non-polarizing beam splitters. As shown in fig. 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, a polarized beam splitter 213, a first light detector 215, and a second light detector 217. In this configuration, as shown in fig. 2B, the polarized laser light source 201a has a wavelength of a high water absorption coefficient (HI), and the polarized laser light source 201B has a wavelength of a low water absorption coefficient (LO).

The incident light beams from the laser sources 201a and 201b are provided as inputs to a second beam combiner 237, the second beam combiner 237 being configured to combine the incident light beams 225a and 225b generated by the laser sources 201a and 201b into a light beam 227. Further, the output of the second beam combiner 237 (e.g., beam 227) may be provided as an input to the polarizer 207, which is used to provide the polarized beam 229 as an output. In some embodiments, the polarization of polarizer 207 may be preconfigured. Thereafter, polarized light 229, obtained as an output from polarizer 207, may be provided as an input to 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, including 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, which second beam splitter 211 has a configuration of an R/T ratio of 50:50 and an AOI of 45 degrees (or any other R/T ratio and AOI as outlined herein). The second beam splitter may split combined beam 235 in a ratio of 50:50 so that aiming beam 231, treatment beam 233, and polarized beam 229 from laser sources 201a and 201b may be aligned along a single optical path.

The power detector 205 associated with the second beam splitter 211 may 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 transmitted by a certain laser beam per unit time. As outlined above with respect to fig. 2A, the optical beam 221, which is the output of the second beam splitter 211, is then transmitted to the optical fiber 103 (e.g., via port 219). In addition, reflected light 223a is received and processed as outlined above with respect to fig. 2A.

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

In configuration 200C, the LETD system 105 may include one or more unpolarized lasers, one or more beam splitters, a beam combiner, and a light detector. One or more of the beam splitters may be a non-polarizing beam splitter. As shown in fig. 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 beam splitter 211, and a third light detector 239.

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

The power detector 205 associated with the first beam splitter 203 may measure the power in the optical signal (beam 227') corresponding to each wavelength. Since configuration 200C is implemented in a non-polarized environment, polarization-based optical components, such as polarizers and polarizing beam splitters, are not required in this configuration. Thus, the output of the first beam splitter 203, i.e., the incident light 225a ' and 225b ' aligned along a single optical path as light 227', may 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 fig. 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 201 b'. In some other embodiments, aiming beam 231 and treatment beam 233 may be generated by laser sources 201a 'and 201 b'. The combined beam 235', including aiming beam 231, treatment beam 233, and unpolarized beams 201a ' and 201b ' from laser sources 201a ' and 201b ', may be subjected to a second beam splitter 211 having a 50:50 and 45 degree AOI (or any other R/T ratio and AOI configuration as outlined herein). Second beam splitter 211 can split combined beam 235' in a 50:50 ratio such that aiming beam 231, treatment beam 233, and unpolarized beams 225a ' and 225b ' are aligned along a single optical path. The optical beam 221, which is the output of the second beam splitter 211, is then transmitted to the optical fiber 103 (e.g., via port 219), while the 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 couple the path of Ji Fanshe 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 a 45 degree angle and split at a 50:50 ratio. The reflected light 223b from the second beam splitter 211 may be directly detected by a single detector. Thus, configuration 200C provides third light detector 239.

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

Fig. 2D illustrates an exemplary configuration 200D for estimating a distance between an end of an optical fiber and a target in accordance with some embodiments of the present disclosure. Configuration 200D includes a third polarized laser source 201c that is introduced for the purpose of calibrating the fiber state in real time. By way of example, the state of the optical fiber 103 may include, but is not limited to, any change or degradation of the distal or proximal end of the optical fiber 103, the effect of fiber bending on polarization scrambling, or any other degradation and change occurring in the optical fiber 103. The state change of the optical fiber 103, particularly the tip/end (e.g., input and output facets) of the optical fiber 103, can adversely affect the transmitted and reflected beams, resulting in substantial reflection, energy loss, and inaccurate measurements. This may affect the accuracy of the distance estimation, resulting in incorrect positioning of the optical fiber 103 during treatment.

In configuration 200D, the 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 fig. 2D, the LETD system 105 includes a polarized laser source 201a, polarized laser source 201b, and polarized laser source 201c, a first beam splitter 203, a power detector 205, a polarizer 207, a first beam combiner 209, a second beam splitter 211, a polarized beam splitter 213, a first light detector 215, a second light detector 217, and a third beam splitter 241. In configuration 200D, as shown in fig. 2D, incident light beams 225a and 225b from laser sources 201a and 201b are provided as input to first beam splitter 203, and first beam splitter 203 is configured to split incident light beams 225a and 225b in a 50:50 ratio such that incident light beams 225a and 225b are aligned along a single optical path, forming light beam 227. In addition, the output of the 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, the third beam splitter 241 further configured to split the incident beams at a ratio of 50:50, forming a beam 243 comprising light 225a, 225b, and 225 c.

At the third beam splitter 241, an incident light beam 225c (e.g., light for collimation) from the polarized laser source 201c is provided as an input along with the output of the first beam splitter 203 (e.g., light beam 227). The power detector 205 associated with the third beam splitter 241 may measure the power in the optical signal (e.g., beam 243) corresponding to each wavelength that reaches the third beam splitter 241. With the output of the first beam splitter 203, the third beam splitter 241 receives the incident light beam from the polarized laser light source 201 c.

In some embodiments, polarized laser source 201c has a wavelength with a very high water absorption coefficient (e.g., substantially, completely, or nearly completely absorbed by water) relative to the wavelength of the light emitted by laser sources 201a and 201 b. As an example, the wavelength of polarized laser source 201c may be about 1435nm and have a water absorption coefficient of about 31.55 (or about 100 times that of a "high" water absorption source). At a distance of 0.5mm at wavelength 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 (e.g., 1870-2070 nm) with very high water absorption coefficients may be utilized. However, the further the wavelengths are from the HI and LO wavelengths (e.g., 1310nm and 1340nm, respectively), the more complex the optical design may result. For example, the detector may cover a range of about 1100-1600nm, and if a very high absorption coefficient laser has a wavelength of 2000nm, a unique or additional detector would be required. In some embodiments, the calibration laser may have a wavelength of about 1435nm, about 2100nm, or between about 1870nm and about 2050 nm.

Based on the reading of the polarized laser source 201c (e.g., as measured by the power detector 205), the processing unit 107 may define an optical baseline characteristic of the "quality" of the fiber tip at the distal end 113 of the optical fiber 103. More specifically, since the laser source 201c is highly absorbed in water, the light from the laser source 201c will be less likely to reach the target tissue, and as a result, little or no light from the laser source 201c will be reflected back into the optical fiber 103 as part of the reflected light 223 a. Thus, the component of light reflection 223c having the wavelength of light associated with laser source 201c is primarily due to the optical characteristics of distal end 113 of optical fiber 103. It should be appreciated that the distal end 113 of the optical fiber 103 experiences degradation during laser treatment due to, for example, heat and cavitation. In many embodiments, an increased intensity reading of the 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.) of intensity variation from baseline readings for a particular fiber, the processing unit 107 may indicate that the fiber 103 should be inspected or replaced, such as through a user interface and/or an audible alarm. In addition, fiber tip degradation may result in higher internal reflection of light from polarized laser sources 201a and 201b from the distal end of the fiber. Whether the laser source is polarized or not may have little effect on internal reflection 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 (e.g., 1435nm laser) can be used to determine the change in the distal reflection (as a percentage of the initial reflection of 1435 to the real-time reflection). Further, for LO lasers (e.g., 1310nm lasers) and HI lasers (e.g., 1340nm lasers), the change in far-end reflection may be applied to the initial reflection from the far-end to update the initial reflection.

In addition, fiber tip degradation may change the ratio between polarity P and polarity S in the back-reflected light 223a or 223 c. Thus, creating baseline readings for the particular optical fiber 103 currently in use, and monitoring these baselines on the fly, a more accurate distance estimate may be achieved, even as and during degradation of the fiber tip, and until the degradation reaches a threshold level indicating that the optical fiber 103 should be replaced. In addition, the output or beam 243 of the third beam splitter 241 (which includes 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 an output from polarizer 207 may be provided as an 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 described 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 sources L1 and L2.

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

Fig. 2E illustrates an exemplary configuration 200E for estimating a distance between an end of an optical fiber and a target, according to some embodiments of the present disclosure. As with configuration 200C, configuration 200E is implemented in a non-polarized environment. Furthermore, configuration 200E is a "half fiber based design" in which the two input splitters seen in the previous configuration (e.g., configuration 200D) are replaced with Wavelength Division Multiplexers (WDM). WDM power loss can be about 20% and splitter power loss can 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, the beam splitter and beam combiner are much less accurate in aligning each of the three laser sources as a single beam.

Configuration 200E utilizes a third unpolarized laser 201c ' and first and second unpolarized lasers 201a ' and 201b '. As described above, the third unpolarized laser 201c' is introduced for the purpose of calibrating the state of the optical fiber in real time. It will be appreciated that the calibration laser may be polarized or unpolarized without departing from the scope of the present 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 fig. 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, a second beam splitter 211, a third light detector 239, a WDM 247, a fourth beam splitter 249, and a collimator 251. In configuration 200E, unpolarized laser source 201a 'may emit light having a wavelength with a high water absorption coefficient (HI), while unpolarized laser source 201b' may emit light having a wavelength with a low water absorption coefficient (LO). In addition, unpolarized laser source 201c ' may emit light having a very high water absorption coefficient (e.g., completely or nearly completely absorbed by water) relative to the wavelength of the light emitted by laser sources 201a ' and 201b '. As an example, the wavelength of the unpolarized laser source (L3') may be 1435nm.

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

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

Thereafter, the output of the collimator 251 (e.g., beam 255 ') may be provided to the first beam combiner 209, which first beam combiner 209 combines the beam 255' exiting the collimator 251 with the aiming beam 231 and the treatment beam 233, as shown in fig. 2E. In several embodiments, the aiming beam 231 may be introduced at the WDM 251. In many embodiments, the aiming beam 231 may be introduced at the first beam combiner 209. Still, in some embodiments, the aiming beam 231 may be introduced at both the WDM 251 and the 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 201 c'.

The 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 having a configuration of R/T ratio 50:50 and 45 degree AOI. The second beam splitter 211 may split the combined beam 235' in a ratio of 50:50 such that the aiming beam 231, the treatment beam 233, and the unpolarized beam 255' from the laser sources 201a ', 201b ', and 201c ' may be aligned along a single optical path. The optical beam 221, which is the output of the second beam splitter 211, is then transmitted to the optical fiber 103 (e.g., via port 219), as shown above and described more fully.

Fig. 2F illustrates an exemplary configuration 200F for estimating a distance between an end of an optical fiber and a target, according to some embodiments of the present disclosure. As with configurations 200C and 200E, configuration 200F is implemented with a non-polarized detector. However, the source may be unpolarized or polarized. In this exemplary configuration, the LETD system 105 may include one or more unpolarized lasers (or polarized lasers), one or more beam splitters, a beam combiner, one or more photodetectors, WDM, a circulator, and a collimator. As shown in fig. 2F, the LETD system 105 includes a non-polarized laser light source 201a ', a non-polarized laser light source 201b ', a non-polarized laser light source 201c ', a power detector 205, a first beam combiner 209, a third optical detector 239, a WDM247, a fourth beam splitter 249, a collimator 2251, and a circulator 257. In configuration 200F, unpolarized laser source 201a 'may emit light having a wavelength with a high water absorption coefficient (HI), while polarized laser source 201b' may emit light having a wavelength with a low water absorption coefficient (LO). Furthermore, the unpolarized laser 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 with WDM247 as shown in fig. 2F. Further, in the exemplary configuration 200F, the second beam splitter 211, which is arranged to deliver the beam to port 219 in all of the above exemplary configurations, is also removed. The beam splitter reduces the output power by up to 50% (or more) and reduces the output power by an additional 50% (or more) when receiving the return signal. Thus, removing the beam splitter in configuration 200F significantly increases the signal and output power.

Incident beams 225a ', 225b' and 225c 'from laser sources 201a', 201b 'and 201c' and aiming beam 231 are provided as inputs to WDM 247, WDM 247 being configured to combine the incident beams in such a way that the beams move identically. Further, the output of WDM 231 can be provided as an input to a fourth beam splitter 249, which fourth beam splitter 249 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 the present disclosure. In some embodiments, fourth beam splitter 233 is a fiber-based beam splitter, thereby making configuration 200F an all-fiber-based design. The power detector 205 associated with the fourth beam splitter 249 may measure the power in the optical signal (e.g., beam 253') corresponding to each wavelength. Further, an output (e.g., beam 253') of the fourth beam splitter 249, which is incident light aligned along a single optical path, may be provided as an input to the circulator 257. The circulator 257 is configured to ensure that all beams propagate in one direction. In addition, the circulator 257 supplies the beam 253 'to the collimator 251 from a port other than the port into which the beam 253' enters. The collimator 251 may narrow the beam into a parallel beam 255'. The circulator 257 can provide (1) lower power loss (beam splitter loss is-50% in each direction) and (2) a more flexible optical design (free space optics requires straight lines, while fiber-based designs can be folded as needed) when compared to beam splitters.

The output of collimator 251 (e.g., parallel beam 255 ') may be provided to first beam combiner 209, and first beam combiner 209 combines beam 255' from collimator 251 with aiming beam 231 and treatment beam 233 into 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. 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 ', or 201 c'. The combined beam 221, including 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 optical fiber 103 (e.g., 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, and then it 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 optical 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 off the optical fiber 103 and reflect a portion of the light toward the optical fiber 103, wherein the portion of the light reflected toward the optical fiber 103 may re-enter the optical fiber 103 at the distal end 113. As outlined above, the portion of the reflected light re-entering at the distal end 113 is referred to as reflected light 223a. Reflected light 223a may be transmitted "backward" from distal end 113 to proximal end 111 through optical fiber 103. When reflected light 223a reaches proximal end 111 of optical fiber 103, reflected light 223a may pass through first beam combiner 209 and collimator 251 to undergo circulator 251, where it is routed to third light detector 239 and measured as described above. Fig. 2G illustrates an exemplary configuration 200G for estimating a distance between an end of an optical fiber and a target, according to some embodiments of the present disclosure. As with some existing configurations, configuration 200G may be implemented in a non-polarized environment. In several embodiments, configuration 200G may include an optical design based on a single beam splitter. In configuration 200G, WDM 247 may replace the functions or operations of multiple beam splitters (e.g., those used in configurations 200A-200D, etc.). WDM 247 can receive input beams 225a ', 225b' and 225c 'from unpolarized laser sources 201a', 201b 'and 201 c'.

In configuration 200G, the LETD system 105 may include one or more unpolarized lasers (or polarized lasers), beam splitters, beam combiners, one or more photodetectors, WDM, and collimators. As shown in fig. 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 fifth beam splitter 259, a third optical detector 239, and a WDM 248. In configuration 200G, as in the prior configuration, the wavelength of unpolarized laser beam 225a ' may have a high absorption coefficient (HI) relative to unpolarized laser beam 225b ', while the wavelength of unpolarized laser beam 225b ' itself may have a lower absorption coefficient (LO). In addition, unpolarized laser beam 225c' may have a wavelength with a very high water absorption coefficient as described in detail above.

As described above, the processing unit 107 may define an optical baseline characteristic of the quality of the distal end 113 (e.g., output face, etc.) of the optical fiber 103 based on readings associated with the reflection of light generated by the unpolarized laser source 201 c'. More specifically, since light from the laser source 201c' is highly absorbed in water, a small amount of this light will be reflected back into the optical fiber 103 as part of the reflected light 223 a. Thus, the reading associated with reflected light 223c is primarily due to the optical properties of distal end 113 of optical fiber 103, which, as described, undergo degradation during laser treatment due to, for example, heat and cavitation. Thus, an increased intensity reading of the 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.) of intensity variation from a baseline reading for a particular optical fiber 103, the processing unit 107 may indicate that the optical fiber 103 should be inspected or replaced, such as through a user interface and/or an audible alarm. In addition, fiber tip degradation may result in higher internal reflection of light associated with unpolarized laser sources 201a 'and 201b' from distal end 113 of optical fiber 103. In addition, fiber tip degradation may change the ratio between polarity P and polarity S in the back-reflected light 223a or 223 c. Thus, creating baseline readings for the particular optical fiber currently in use, and monitoring these baselines on the fly, a more accurate distance estimate can be achieved, even as and during degradation of the fiber tip, and until the degradation reaches the point where the fiber should be replaced. Thus, greater dynamic control of parameters associated with therapy or treatment may be provided.

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

Incident light beams 225a ', 225b' and 225c 'from laser sources 201a', 201b 'and 201c' and aiming beam 231 may be provided as inputs to WDM 247, and WDM 247 may be configured to combine the incident light beams in such a way that the light beams move identically. In addition, the output of WDM 247 can be provided as an input to a fifth beamsplitter 259, which can 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 (e.g., glass) based beam splitter. In some other embodiments, fifth beam splitter 259 may be a fiber-based beam splitter. In many embodiments, the power detector 205 associated with the fifth beam splitter 259 may measure the power in the optical signal (e.g., beam 253') corresponding to each wavelength.

The output of the fifth beam splitter 259, which is incident light aligned along a single optical path, may be provided as an 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 fig. 2G. In various embodiments, the aiming beam 231 may be introduced into the WDM 247, at the first beam combiner 209, or both the WDM 247 and the 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 may be generated by laser sources 201a', 201b ', and 201 c'. The combined beam 221, including the aiming beam 231, the treatment beam 233, and the beam 253 'from the laser sources 201a', 201b ', and 201c', received from the first beam combiner 209, may be transmitted to the optical fiber 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), but rather a fifth beam splitter 259 (which is initially configured to split the incident beam to split Ji Rushe light along a single optical path) is used to pair Ji Fanshe the optical path of light 223 a. Furthermore, since configuration 200G utilizes a single beam splitter, it may be significantly less sensitive to treatment fiber movement and fiber bend radius, resulting in a more robust configuration. Moreover, 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 example 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 may 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 optical detector may comprise one or more of the following: (a) reflection from a port lens; (b) reflection from blast shield; (c) reflection from the proximal end 111 of the fiber; and/or (d) reflection from the fiber distal end 113.

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

In some embodiments of the above-described exemplary configurations, 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 this figure, cutting at an angle of 8 degrees achieves steering of the reflected beam from the proximal end 111 of the optical fiber 103 (unwanted 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 optical detector may comprise one or more of the following: (a) reflection from a port lens; (b) reflection from an explosion-proof shield; (c) reflection from the proximal end 111 of the fiber; and/or (d) reflection from the fiber distal end 113.

As explained above, the AR coating of the proximal end of the optical fiber 103 may reduce the reflection from the proximal end of the optical fiber 103 from 3.5% to about 0.5%. However, the more subtle angled proximal end of the optical fiber 103 helps to reduce unwanted reflections and improve the dynamic range of the signal reflected from the target 101. In some other embodiments, the SMA connector may be polished or cut at a 4 degree angle instead of 8 degrees, as shown in fig. 2I. In various embodiments, cutting at a tilt of 4 degrees (such as instead of 8 degrees (or higher) may improve signal robustness. In some embodiments, the smaller the 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 is difficult to grasp it from the main signal. However, light will not enter the fiber at a higher angle (e.g., 10+ degrees).

Fig. 3A illustrates a flow chart showing a method 300 of estimating a distance between an end of an optical fiber and a target, according to some embodiments of the present disclosure. The method 300 is described with reference to the architecture 100 and various configurations of the LETD 105 described above. However, it should be appreciated that the method 300 may be implemented using a different LETD than that described herein. The embodiments are not limited in this context.

At block 301, the method 300 includes illuminating a target with a plurality of different wavelengths of laser light. For example, the LETD105 can illuminate the target 101 with a plurality of different wavelengths of laser light via the optical fiber 103 using a plurality of laser sources (e.g., 201a and 201b or 201a 'and 201 b'). In some embodiments, a plurality of different wavelengths of laser light may be provided to the optical fiber 103 for illuminating the 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 225 b'), each wavelength having a different water absorption coefficient to ensure robustness against different types of targets 101, target components, target colors, target surfaces, etc.

In some embodiments, the 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 1310nm and 1340nm. However, this example should not be construed as limiting, as different wavelengths with different water absorption coefficients may be used. For example, 1260-1320nm may be used for LO and 1330-1380nm may be used for HI. More generally, any combination of wavelength absorption coefficient pairs having a 2:1 (or greater) ratio may be used. In some embodiments, one or more of the following pairs may be used for LO and HI lasers, 1310nm and 1340nm lasers, 1260nm and 1310nm and 1550nm lasers, respectively. As outlined above, in some embodiments, two laser sources (e.g., 201a and 201b or 201a 'and 201 b') may be used to emit light of two different wavelengths. In some embodiments, the laser source may be a polarized laser source, an unpolarized laser source, or a combination of polarized and unpolarized laser sources. As an example, to measure the distance between the distal end 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 may be used because it does not include visible light that may interfere with the user.

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

At block 305, the method includes measuring an intensity of the reflected light beam by detecting the reflected light beam using one or more light detectors, and transmitting an indication (e.g., an electrical signal, etc.) of the reflected light beam intensity measured by the one or more light detectors to a processing unit. For example, the LETD system 105 can measure the intensity of the reflected light beam 223 (also referred to herein as a 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 the two different wavelengths. Thus, two measured intensities corresponding to two different wavelengths of laser light sources (e.g., laser light 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 a processing unit, an indication of the intensity of the reflected light beam 223 measured by the one or more light detectors. For example, the processing unit 107 may receive an electrical signal from the LETD system 105 that includes an indication of the measured intensity of the 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 intensity of the return signal. In some embodiments, the processing unit 107 may substitute the measured intensities into equation 1 as follows:

strength of return signal = R e ^(-λ*X) Equation 1

In the above formula 1, "R" means a target reflectance affected by a target component, a target color/pigment, a target angle, a target surface, etc.; "λ" refers to the water absorption coefficient of a particular wavelength; and "X" refers to the distance between the distal end of the optical fiber 103 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, in order to determine the values of "X" and "R", the processing unit 107 may replace the two measured intensity values into the above-described formula 1, thereby obtaining two formulas having the measured intensities and the replaced values of the water absorption coefficients of the corresponding wavelengths. For example, two formulas with substitution values may be as follows.

I _(HI) ＝R*e ^(-λ_HI*X) Equation 1.1

I _(LO) ＝R*e ^(-λ_LO*X) Equation 1.2

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

step 1: the ratio of the measured intensity values obtained for the two return signals of different wavelengths is calculated.

Step 2: the distance value is determined using natural logarithms as follows:

thus, 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 the formulas 1.1 and 1.2 as shown above. In the above formula 2.2, "ln" refers to the natural logarithm. In some embodiments, the distance (X) may be measured in millimeters. In some embodiments, "X" is the same distance for both wavelengths, and R (target reflection) is nearly 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 250nm (e.g., 1310nm and 1340nm or 1310nm and 1550 m). However, in many embodiments, wavelengths may be selected that have values closer to R. Thus, 1310nm and 1340nm may be selected at 1310nm and 1550 nm. By some examples of the present disclosure, two laser sources (e.g., 201a and 201b or 201a 'and 201 b') may be arranged to emit light having wavelengths within 100nm of each other.

The state of the optical 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 optical fiber 103, the effect of fiber bending on polarization scrambling, or any other degradation and change occurring in the optical fiber 103. Variations in the optical conditions of the optical fiber 103, particularly variations in the tip/end of the optical fiber 103, may adversely affect one or more of the quality of the radiation beam, the intensity of the internally reflected beam, the amount of back reflected light from the target entering the optical fiber, the amount of energy reaching the target, and the accuracy of the measurement. This may affect the accuracy of the distance estimation, possibly leading to incorrect positioning of the optical fiber 103 during treatment or miscalculating energy optimization, based on the distance estimation described in U.S. provisional patent application No.63/118,117, which is incorporated herein by reference.

Internal reflections from planes associated with the optical fiber (e.g., proximal or distal of the optical fiber) or other optical elements optically connected to the optical fiber (e.g., lenses or shields) can generate parasitic and unwanted reflections. Furthermore, these internal reflections may change over time due to degradation of the fiber or other element. 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 223 b.

Thus, for some embodiments, at block 309, the method 300 may measure the initial internal reflection of each laser prior to the beginning of the treatment to maintain accurate distance measurements during fiber degradation and internal reflection changes. In many such embodiments, an initial internal reflection value (or base value) may be recorded and used to monitor changes over time. For example, the processing unit 107 may include circuitry (e.g., 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 a laser system. For example, the process may 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 (e.g., stored in circuitry of the processing unit 107, etc.) to dynamically correct distance measurements as provided herein.

In some embodiments, the processing unit 107 is configured to read (e.g., from registers, from memory, etc.) baseline values of such spurious (e.g., unwanted) reflections using a system pre-process calibration procedure. In some embodiments, the system preconditioning calibration process may include setting the therapeutic fiber in water without the target. In this case, a "no target" may 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 off the target and back into the fiber 103 as signal 223 a. For IR sources (e.g., 1310nm and 1340nm sources), such a distance may be, for example, 10mm or greater from the distal end 113 of the optical fiber 103. However, if visible light (e.g., 400-700 nm) is used, lengths greater than 10mm may be used. Thereafter, under these conditions, the system may activate the lasers (e.g., 201a and 201b or 201a 'and 201 b') and measure the reflected signal 223, as described above. Because the reflected light 223a under these conditions (e.g., active laser light in the presence of water but without a target) is very low, the signal to the photodetector is primarily related to the internal reflection associated with the fiber (e.g., from port 219, proximal end 111, distal end 113, etc.).

In this case, the Internally Reflected (IR) beam may be detected using a light detector, and the measured intensity value may be stored as IR by the processing unit 107 _(HI) And IR _(LO) (e.g., in a register, or in a memory circuit, etc.). IR (IR) _(HI) May be of higher water absorption when there is no target near the tip (e.g., distal end 113) of the fiberInternal reflection intensity of incident light of coefficient, while IR _(LO) May be the intensity of the internal reflection of incident light with a low water absorption coefficient when there is no target near the tip (e.g., distal end 113) of the fiber. Thereafter, during therapy or treatment, when the laser is activated while the distal end 113 of the optical fiber is placed at a closer distance from the target 101, the return signal 223a may be reflected back through the optical fiber and detected using the light detector described herein.

In addition to calculating the measured intensity values 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 values 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 a wavelength with a higher water absorption coefficient (HI), and store I _(LO) Which may be an indication of the intensity of the return signal from the target 101 (e.g., tissue, stone, etc.) corresponding to a wavelength having a lower water absorption coefficient (LO). However, to eliminate spurious (or unwanted) reflection values from the readings of the actual return signal 223, the processing unit 107 may separately output the actual return signal I _(HI) Subtracting and/or reducing IR from the reading of (a) _(HI) (as shown in equation 3.1 below) and the signal I returned from the actual _(LO) Subtracting and/or reducing IR from the reading of (a) _(LO) As shown in equations 3.1 and 3.2 below.

I′ _(HI) ＝I _(HI) -IR _(HI) Equation 3.1

I′ _(LO) ＝I _(LO) -IR _(LO) Equation 3.2

In the above formula 3.1, I' _(HI) Refers to the newly calculated intensity (no spurious (or unwanted) reflection) of the return signal corresponding to the wavelength with the higher water absorption coefficient (HI); i _(HI) Refers to the measured intensity (with spurious (or unwanted) reflection) of the return signal corresponding to the wavelength with the higher water absorption coefficient (HI); IR (infrared radiation) _(HI) Refers to the measured intensity of the internal reflection of incident light with a higher water absorption coefficient ("measurement without target").

Similarly, in equation 3.2 above, I' _(LO) Refers to the newly calculated intensity (no spurious (or unwanted) reflection) of the return signal corresponding to the wavelength with the lower absorption coefficient (LO); i _(LO) Refers to the measured intensity (with spurious (or unwanted) reflection) of the return signal corresponding to the wavelength with the lower water absorption coefficient (LO); IR (infrared radiation) _(LO) Refers to the measured intensity of the internal reflection of incident light with a lower water absorption coefficient ("measurement without target").

Thus, a new intensity calculation I 'is used' _(HI) And I' _(LO) The processing unit 107 may be configured to replace the new "calibration" value I 'in equation 2.2' _(HI) And I' _(LO) To determine the distance between the distal end 113 of the optical fiber 103 and the target 101 as follows:

in some embodiments, the above formula for "X" may also be expressed as follows:

as mentioned above, the internal reflection may not be constant over time and may change due to some change in the internal optical parameters of the system (as opposed to dynamic changes due to the therapeutic 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 therapeutic beam 233, cavitation effects occurring at the distal end 113 (or tip) of the optical fiber 103, and the liquid environment in which the optical fiber is disposed during treatment, the optical fiber experiences various amounts of degradation, primarily at the distal end 113 (or tip). Thus, in several embodiments, a "real-time" or "dynamic" calibration may be performed by repeatedly monitoring the reflected signal 223 during treatment and dynamically accounting for or adjusting for such internal reflection variations. 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 201 c') may be utilized to facilitate a more accurate distance estimation that accounts for such degradation of the optical fiber 103.

As explained with respect to configurations 200D-200G, the collimated laser beam (e.g., 225c or 225 c') 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 collimated lasers 201c and 201c' are thus strongly absorbed by the liquid environment, as explained above, little of any back reflection 223a associated with these laser beams is returned to the optical fiber. Thus, while the calibration laser source (e.g., 201c or 201c ') is active, the reflected signal 223 having the wavelength of the calibration laser source 201c or 201' is primarily associated with (or indicative of) internal reflection.

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 architecture 100 associated with the laser source 201c or 201c' prior to the start of the treatment. These one or more base values may represent the "quality" of the optical fiber 103 (e.g., the optical quality of the distal end 113) prior to the beginning of the treatment, and may be stored by the processing unit 107 (e.g., in a register, in a memory circuit, etc.). Furthermore, the processing unit 107 may be configured to continue measuring the internal reflection of the light emitted by the calibration laser source 201c or 201c' in "real time" during the treatment to identify deviations from the base value. Monitoring these deviations provides an indication of degradation of the optical quality of the optical fiber and can be used to correct for any measured back-reflected intensity associated with signal 223 a. In many embodiments, the processing unit 107 may correct the calibration parameters of the main laser sources 201a and 201b or 201a ' and 201b ' based on a reading of the internal reflection of the light emitted by the calibration laser source 201c or 201c '.

In some embodiments, the 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', wherein the system is activated in water. Since the calibration lasers 201c and 201c 'are highly absorbing in water, the sensitivity to distance to the target 101 during a calibration reading of either 201c or 201c' may be much lower relative to the measurement of the reflected signal associated with the light emitted by the lasers 201a and 201b or 201a 'and 201 b'. As will be explained in more detail below, this may provide for continued calibration of the laser measurements during treatment, as the target may also be near the fiber tip.

Thereafter, the target 101 may be irradiated with lasers 201a and 201b or 201a 'and 201b' using one of the example configurations 200D-200G. In this case, the reflected beams 223a and 223b may be detected using a photodetector, and the processing unit 107 may store the measured intensity value as I _(HI) 、I _(LO) And calibrating the additional and related measured value IR of the internal reflection of the laser _(CAL) 。I _(HI) May be the intensity of back reflection from a target of incident light having a higher water absorption coefficient, I _(LO) May be the back reflection intensity from a target of incident light having a lower water absorption coefficient, and IR _(CAL) May be the intensity of the internal reflection of the incident light from the collimated laser 201c or 201 c'.

In some embodiments, the presence or absence of the target 101 may not affect the reflected IR _(CAL) This is because the incident light from the collimated laser source 201c or 201c' is highly absorbed by water. As a result, IR _(CAL) The change in value may be the result of a degradation change of the optical fiber 103, particularly the tip (e.g., distal end 113, etc.) of the optical fiber 103. In some embodiments, based on IR _(CAL) Relative change in value, the processing unit 107 may adjust the previously measured IR _(HI) And IR _(LO) Value or current measured I _(LO) Or I _(HI) 。

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 sufficiently close distance to generate the back-reflected signal 223a, such as when the target is at a distance less than or equal to 10mm from the distal end 113 of the optical fiber 103), the back-reflected beam 223a for the laser source 201a or 201a 'and the laser source 201b or 201b' and from the calibration laser source 20The internal reflection 223c of 1c or 201c' may be detected using a light detector. At block 309, the processing unit 107 may store the measured intensity value as I _(HI) Which may represent the strength of the return signal having a higher water absorption coefficient (HI) corresponding to its wavelength, I _(LO) Which may represent the strength of the return signal with a lower water absorption coefficient (LO) corresponding to its wavelength, and IR _(CAL) Which may represent the intensity of the returned internal reflection signal corresponding to light having a higher static water absorption coefficient at its wavelength (e.g., light emitted by the calibration laser source 201c or 201 c'). Furthermore, to determine the calibration factor, the processing unit 107 may preprocess the IR from the calibration process _(CAL-PRE) IR completed with calibration procedure from during treatment _(CAL-DUR) Divided by one 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 treatment and the optical fiber 103 is unchanged. Furthermore, in order to correct the parameters of the main 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 the following equations 5.1 and 5.2.

I" _(HI) ＝I _(HI) -IR _(HI) X CF equation 5.1

I" _(LO) ＝I _(LO) -IR _(LO) X CF equation 5.2

In the above formula 5.1, I' _(HI) Refers to a new calibrated intensity of the back-reflected signal from the target, corresponding to light having a wavelength with a higher water absorption coefficient (HI); i _(HI) Refers to the measured intensity of the back-reflected signal from the target, corresponding to light having a wavelength with a higher water absorption coefficient (HI); IR (IR) _(HI) Refers to the measured intensity of the internal reflection of an incident laser light having a wavelength with a higher water absorption coefficient ("measurement without target"); and CF refers to the calibration factor determined using equation 4.

In the above formula 5.2, I' _(LO) Refers to a new calibration intensity of the back-reflected signal from the target, corresponding to light having a wavelength with a lower water absorption coefficient (LO); i _(LO) Refers to the measured intensity of the back-reflected signal from the target, corresponding to light having a wavelength with a low water absorption coefficient (LO); IR (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 ("measurement without target"); and CF refers to the calibration factor determined using equation 4.

Thus, a new calibration intensity value I' is used " _(HI) And I' _(LO) The processing unit 107 may at block 309 pass the new calibration value I' _(HI) Or I' _(LO) The distance between the distal end 113 of the optical fiber 103 and the target 101 is determined by substituting into equation 2.2 as follows:

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

At block 311, the method includes indicating, by the processing unit 107 via an indicator, an estimated (e.g., 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 a specific example, the indicator 109 may include one or more of a visual indicator, an audio indicator, and a tactile indicator. Thus, 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 send signal, tactile send signal, 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 affect the treatment beam on the target 101, such as by more accurate targeting.

Fig. 3B illustrates a flow chart showing a method 350 of estimating a distance between an end of an optical fiber and a target, according to some embodiments of the present disclosure. The method 350 is described with reference to the architecture 100 and various configurations of the LETD 105 described above. However, it should be appreciated that the method 300 may be implemented using a different LETD than that described herein. The embodiments are not limited in this context.

At block 351, the method 350 includes determining a first intensity value based on a first reflected laser light corresponding to the laser light of the first wavelength, wherein the laser light of the first wavelength exits the distal end 113 of the optical fiber 103 and the first reflected laser light is reflected by the target 101 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 having a high water absorption coefficient with its wavelength. In some embodiments, as discussed above, a laser corresponding to a wavelength having a high water absorption coefficient may be generated by the laser source 201a or 201 a'.

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

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 a ratio of the first intensity value and the second intensity value using equation 2.1. At block 357, the method 350 includes estimating a 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 a distance between the distal end 113 of the optical fiber 103 and the target 101 based on a ratio of the first intensity value and the second intensity value.

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

At block 381, the method 380 includes illuminating the target with a plurality of different wavelength lasers. For example, one of the configurations 200A-200G may be used to illuminate the target 101 with a plurality of different wavelength lasers 221. In several embodiments, the plurality of 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, via an optical fiber, a reflected light beam from a target. For example, one of the configurations 200A-200G may be used to receive reflected light beam 223 (e.g., corresponding to light reflected from target 101) and transmitted back through optical fiber 103. In several embodiments, reflected light beam 223 may reflect off of target 101 and enter distal end 113 of optical fiber 103, and thus may include reflected light 223a. The reflected light 223a may also include light reflected from optical components within the system (e.g., the proximal end 111, the distal end 113, etc.), and may include reflected light 223c corresponding to reflected light associated with the collimated light beam 225 c.

At block 385, method 380 includes measuring an intensity of reflected beam 223 with one or more photodetectors. In many embodiments, one of the configurations 200A-200G may be used to measure the intensity of the reflected beam 223 with one or more photodetectors. 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, third light detector 227 may be used to measure the intensity of reflected light beam 223.

At block 387, method 380 includes estimating a distance between distal end 113 of optical fiber 103 and target 101 based on an intensity of reflected light beam 223 measured with one or more light detectors. 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, the processing unit 107 may be included in one or more portions of the 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. Alternatively, the processing unit 107 may be implemented by the computer system 400. In some such embodiments, the computer system 400 may be used to estimate the distance between the distal end 113 of the optical fiber 103 and the 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 (e.g., with respect to methods 300, 350, and/or 380). The user may include a person, a person using devices such as those included in the present disclosure (e.g., doctor, nurse, technician, etc.), or the device itself. Processor 402 may include a special purpose processing unit such as an integrated system (bus) controller, memory management control unit, floating point unit, graphics processing unit, digital signal processing unit, application Specific Integrated Circuit (ASICS), field Programmable Gate Array (FPGA), or a commercially available processing unit. The processor 402 may be configured and arranged to communicate with the input device 411 and/or the output device 412 (e.g., via the I/O interface 401, etc.). The 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 Video 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 (e.g., code Division Multiple Access (CDMA), high speed packet Access (HSPA+), global System for Mobile communications (GSM), long Term Evolution (LTE), wiMax, etc.), and the like.

Using I/O interface 401, computer system 400 may communicate with input devices 411 and/or output devices 412. In some embodiments, the processor 402 may be configured and arranged to communicate with a communication network 409 (e.g., via the network interface 403, etc.). The network interface 403 may be used to communicate via a communication network 409. The network interface 403 may employ connection protocols including, but not limited to, direct connection, ethernet (e.g., twisted pair 10/100/1000Base T), transmission control protocol/Internet protocol (TCP/IP), token ring, IEEE 802.11a/b/g/n/x, and the like. Using network interface 403 and communication network 409, computer system 400 may communicate with the LETD system 105 and/or indicator 109. In some embodiments, one or more portions of computer system 400 may be integrated into the LETD system 105. In some such embodiments, one or more components of the LETD system 105 (e.g., power detectors and/or photodetectors) may include an input device 411.

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. Communication network 409 may be a private network or a shared network that represents an association of different types of networks that communicate with each other using a variety of protocols (e.g., hypertext transfer protocol (HTTP), CAN protocol, transmission control protocol/internet protocol (TCP/IP), wireless Application Protocol (WAP), etc.). Further, communications network 409 may include a variety of 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 (e.g., RAM, ROM, etc., not shown in fig. 4) via a storage interface 404. The storage interface 404 may be connected to the memory 405 using a connection protocol such as Serial Advanced Technology Attachment (SATA), integrated Drive Electronics (IDE), IEEE-1394, universal Serial Bus (USB), fibre channel, small Computer System Interface (SCSI), etc., including but not limited to a memory drive, removable disk drive, etc. The memory drives may also include magnetic drums, magnetic disk drives, magneto-optical drives, redundant Arrays of Independent Disks (RAID), solid state storage devices, solid state drives, and the like.

Memory 405 may store a collection of programs or database components including, but not limited to, a user interface 406, an operating system 407, a 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 of the techniques, steps, processes, and/or methods described herein, such as estimating a distance or performing a 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, the memory 405 may be a memory device including memory circuitry arranged to non-temporarily store instructions 415. In some embodiments, computer system 400 may store user/application data, such as data, variables, records, and the like, as described in this disclosure. Such a database may be implemented as a fault tolerant, relational, scalable, secure database, such as Oracle or Sybase.

The operating system 407 may facilitate resource management and operation of the computer system 400. Examples of operating systems include, but are not limited toOS/> UNIX-like System release (e.g., BERKELEY SOFTWARE +. >(BSD)、/> OPENBSD, et al), -a method of treating cancer>DISTRIBUTIONS (e.g. RED-> Etc.), a,(/> 7/8, 10, etc.),GOOGLE ^TM ANDROID ^TM 、/>OS, etc. The user interface 406 may facilitate display, execution, interaction, manipulation, or operation of the program component by a text or graphical tool. For example, the user interface may provide computer interactive interface elements, such as cursors, icons, check boxes, menus, scroll bars, windows, widgets, and the like, on a display system operatively connected to computer system 400. A Graphical User Interface (GUI) may be employed including, but not limited toOperating System->(e.g., aero, metro, etc.), web interface library (e.g., +.>AJAX、HTML、Etc.), etc.

In some embodiments, computer system 400 may implement a program component stored by web browser 408. Web browser 408 may be a hypertext viewing application, such asINTERNET/>GOOGLE ^TM CHROME ^TM 、/> Etc. Secure web browsing may be provided using secure hypertext transfer protocol (HTTPS), secure Sockets Layer (SSL), transport Layer Security (TLS), and the like. Web browser 408 may utilize, for example, AJAX, DHTML,Application Programming Interfaces (APIs), and the like. In some embodiments, computer system 400 may implement a program component stored by a mail server. The mail server may be an internet mail server such as Microsoft Exchange. Mail servers can utilize, for example, dynamic server pages (ASPs), -, etc >C++/C#、/>.NET、CGI SCRIPTS、PHP、/>And the like. The mail server may utilize a communication protocol such as the Internet Message Access Protocol (IMAP), the Message Application Programming Interface (MAPI), the like,Exchange, post Office Protocol (POP), simple Mail Transfer Protocol (SMTP), etc. In some embodiments, computer system 400 may implement a mail client storage program component. The mail client may be a mail viewing application, such asMAIL、/> Etc.

Furthermore, one or more computer-readable storage media may be used to implement embodiments consistent with the present disclosure. Computer-readable storage media refers to any type of physical memory that can store information or data that is readable by a processor. Thus, a computer-readable storage medium may store instructions for execution by one or more processors, including instructions for causing the processors to perform steps or stages consistent with embodiments described herein. The term "computer-readable medium" shall be taken to include tangible articles and not include carrier waves and transient signals, i.e., non-transient. Examples include Random Access Memory (RAM), read Only Memory (ROM), volatile memory, nonvolatile memory, hard disk drives, compact Disk (CD) ROMs, digital Video Disks (DVDs), flash memory drives, magnetic disks, and any other known physical storage medium.

In various embodiments, the present disclosure may provide various technical effects and improvements. For example, the present disclosure may enable the distance between the distal end of the optical fiber and the target to be estimated by using two different wavelengths of laser light (e.g., one having a low water absorption coefficient and the other having a high water absorption coefficient). Distance estimation based on such wavelength selection may provide robustness with respect to different types of targets, target components, target colors, target surfaces, etc. The wavelength modulation-based techniques and systems disclosed in this disclosure may be provided to estimate the distance between the distal end of the optical fiber and the target, and may facilitate accurate distance estimation. Further, 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 may provide more and more varied distance estimation of the target than conventionally possible. Accordingly, the present disclosure provides systems and methods that aim at a target more accurately than conventionally possible. A more accurate targeting may eliminate or reduce incorrect portions of the ablation and/or disruption target, which may itself lead to adverse consequences and/or permanent damage. In addition, more accurate targeting consumes less time in ablating and/or fragmenting the target.

In several embodiments, the present disclosure may be used to precisely position and/or aim a treatment beam, such as in a low visibility environment (e.g., an environment that includes dust or target debris). For example, during a treatment objective (e.g., kidney stones), water may become cloudy due to the presence of stone fragments or dust. This may reduce (or prevent) the ability to see the target (e.g., kidney stones). In this case, the present disclosure provides a system to accurately identify and inform the treating physician of the placement of the optical fiber (e.g., whether the optical fiber is placed in front of the target or whether the target is not detected).

Further, in many embodiments, the present disclosure may be used for distance measurement. For example, a target (e.g., kidney stones) may move around during treatment, which may result in laser light associated with the treatment beam being incident on unwanted areas (e.g., healthy tissue, etc.) rather than on the target. Accordingly, the present disclosure may enable automatic and real-time monitoring of the distance between the optical 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, the target may move back and forth during treatment, or may change its shape and size. Thus, parameters preset for the laser source before starting lasing of the target may become less effective. Traditionally, such preset parameters are manually changed, which can be error-prone and time-consuming, or in some cases, the preset parameters may remain unchanged, which can lead to a situation where the fiber is too close or too far from the target. Thus, as disclosed in this disclosure, automatic and real-time monitoring of the distance between the fiber and the target may enable automatic variation of laser preset parameters to adjust the laser emission according to the target shape, position, etc. for optimal results.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. For purposes of clarity and not limitation, various singular and/or plural permutations are explicitly set forth herein.

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

In accordance with the present disclosure, all of the devices and/or methods disclosed and claimed herein can be made and executed without undue experimentation. Although the apparatus and methods of this disclosure have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the apparatus and/or methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit and scope of the 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 of a first wavelength;

a second laser source for generating laser light of a second wavelength;

an optical fiber having a distal end, the optical fiber configured to transmit laser light from the first and second laser sources out of the distal end and to receive reflected laser light into the distal end;

a photodetector for measuring the intensity of the reflected light; and

a processor and a memory comprising instructions that, when executed by the processor, cause the processor to estimate a distance between a distal end of the optical fiber and a target based on an intensity of the reflected light measured by the light detector.

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

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

4. The system of any of claims 1-3, wherein the first wavelength is about 1330nm to about 1380nm and the second wavelength is about 1260nm to about 1320nm.

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 has a third water absorption coefficient that is higher than the first and second water absorption coefficients.

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

7. The system of 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 second intensity value of reflected light corresponding to the laser light of the second wavelength.

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 is also provided with

A distance between the distal end of the optical fiber and the target is estimated based on a ratio of the first intensity value and the second intensity value.

9. The system of any one of claims 1 to 8, wherein one or more of the first and second laser sources comprises a polarization maintaining pigtail fiber laser, a single mode pigtail fiber laser, or a free space laser.

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 arranging the first wavelength laser and the second wavelength laser 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:

irradiating the target with a plurality of lasers of different wavelengths;

receiving a reflected light beam from the target via an optical fiber;

measuring the intensity of the reflected beam with one or more photodetectors; and is also provided with

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 light detectors.

12. The method of claim 17, comprising: a plurality of different wavelengths of laser light are emitted via the optical fiber to illuminate the target.

13. The method according to any one of claims 17 to 18, comprising: a first intensity value of the reflected light beam corresponding to the laser light of the first wavelength and a second intensity value of the reflected light beam corresponding to the laser light of the second wavelength are measured.

14. The method of claim 13, wherein the first wavelength is about 1330nm to about 1380nm and the second wavelength is about 1260nm to about 1320nm.

15. The 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 is also provided with

A distance between the distal end of the optical fiber and the target is estimated based on a ratio of the first intensity value and the second intensity value.