US-12620764-B2 - Method and system for estimating distance between a fiber end and a target

US12620764B2US 12620764 B2US12620764 B2US 12620764B2US-12620764-B2

Abstract

The present disclosure is related to field of Fiber Feedback (FFB) technology, and provides a method and system for estimating the distance between a fiber end and a target. The method includes illuminating, by a Light Emitting, Transmitting and Detecting (LETD) system, the target with laser light of different wavelengths having low and high water absorption coefficients, using different laser light sources, as well as receiving a returned signal corresponding to the incident laser light of different wavelengths, and detecting the returned signal to measure intensity values of the returned signal of a specific wavelength. Using the measured intensity values, a processing unit may estimate distance between the fiber end and the target. The present disclosure enables accurate estimation of distance between a fiber end and the target. The present disclosure also provides a robust distance estimation technique which is compatible with different types of targets.

Inventors

Arkady Khachaturov
Vitaly Rondel

Assignees

LUMENIS LTD

Dates

Publication Date: 20260505
Application Date: 20211124

Claims (14)

1 . A system, comprising: a first laser source to generate laser light of a first wavelength; a second laser source to generate laser light of a second wavelength different from the first wavelength; an optical fiber having a distal end, the optical fiber configured to pass 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 light detector to measure intensity of the reflected light; and a processor and memory comprising instructions that when executed by the processor cause the processor to: receive an indication of a first intensity value of the reflected light corresponding to the laser light of the first wavelength, receive an indication of a second intensity value of the reflected light corresponding to the laser light of the second wavelength, derive an adjusted first intensity value based on subtracting a first internal reflection values from the first intensity value, derive an adjusted second intensity value based on subtracting a second internal reflection values from the second intensity value, and estimate a distance between the distal end of the optical fiber and a target based on a ratio of the adjusted first intensity value of the reflected light and the adjusted second intensity value of the reflected light, wherein the first wavelength has a first water absorption coefficient higher than a second water absorption coefficient of the second wavelength.
2 . The system of claim 1 , wherein the ratio of the first water absorption coefficient to the second water absorption coefficient is at least 2 to 1.
3 . The system of claim 2 , wherein the first wavelength is approximately 1330 nm to approximately 1380 nm and the second wavelength is approximately 1260 nm to approximately 1320 nm.
4 . The system of claim 3 , comprising a third laser source to generate laser light of a third wavelength utilized to characterize a condition of the optical fiber, wherein the third wavelength has a third water absorption coefficient higher than the first and the second water absorption coefficients.
5 . The system of claim 4 , wherein the third wavelength comprises approximately 1435 nm, approximately 2100 nm, or a wavelength between approximately 1870 nm and approximately 2050 nm.
6 . The system of claim 1 , wherein one or more of the first and second laser sources comprise a polarization maintaining pigtailed fiber laser, a single mode pigtailed fiber laser, or a free space laser.
7 . The system of claim 1 , comprising a wave division multiplexer (WDM) coupled to a proximal end of the optical fiber, the WDM to arrange the laser light of the first wavelength and the laser light of the second wavelength to enter a proximal end of the optical fiber at one or more of a same point and a same angle.
8 . At least one non-transitory computer-readable medium comprising a set of instructions that, in response to being executed by a processor circuit, cause the processor circuit to: determine a first intensity value based on first reflected laser light corresponding to laser light of a first wavelength, wherein the laser light of the first wavelength exits a distal end of an optical fiber and the first reflected laser light is reflected by a target and enters the distal end of the optical fiber; determine a second intensity value based on second reflected laser light corresponding to laser light of a second wavelength different from the first wavelength, wherein the laser light of the second wavelength 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; derive an adjusted first intensity value based on subtracting a first internal reflection values from the first intensity value, derive an adjusted second intensity value based on subtracting a second internal reflection values from the second intensity value, and compute a ratio of the adjusted first intensity value and the adjusted second intensity value; and estimate a distance between the distal end of the optical fiber and the target based on the ratio of the adjusted first intensity value and the adjusted second intensity value, wherein the first wavelength has a first water absorption coefficient higher than a second water absorption coefficient of the second wavelength.
9 . The at least one non-transitory computer-readable medium of claim 8 , wherein the set of instructions, in response to execution by the processor circuit, further cause the processor circuit to determine an internal reflection value based on third reflected laser light corresponding to laser light of a third wavelength, wherein the laser light of the third wavelength exits a laser source and the at least a portion of the third reflected laser light is reflected by a distal end of the optical fiber.
10 . The at least one non-transitory computer-readable medium of claim 9 , wherein 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 adjust an operating parameter of a treatment beam based on comparison of the internal reflection value to the baseline internal reflection value.
11 . The at least one non-transitory computer-readable medium of claim 10 , wherein 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; characterize a condition of the optical fiber based on comparison of the internal reflection value to the baseline internal reflection value; and communicate an indication of the condition of the optical fiber via a user interface.
12 . The at least one non-transitory computer-readable medium of claim 8 , wherein the set of instructions, in response to execution by the processor circuit, further cause the processor circuit to communicate an indication of the distance estimated between the distal end of the optical fiber and the target via a user interface.
13 . A method, comprising: illuminating a target with laser light of a plurality of different wavelengths; receiving reflected light beams from the target via an optical fiber; measuring intensity of the reflected light beams with one or more light detectors, comprising at least: measuring a first intensity value of the reflected light beams corresponding to laser light of a first wavelength, and measuring a second intensity value of the reflected light beams corresponding to laser light of a second wavelength different from the first wavelength; deriving an adjusted first intensity value based on subtracting a first internal reflection values from the first intensity value; deriving an adjusted second intensity value based on subtracting a second internal reflection values from the second intensity value; computing a ratio of the adjusted first intensity value and the adjusted second intensity value; and estimating a distance between a distal end of the optical fiber and the target based on the ratio, wherein the first wavelength has a first water absorption coefficient higher than a second water absorption coefficient of the second wavelength.
14 . The method of claim 13 , comprising emitting the laser light of the plurality of different wavelengths via the optical fiber to illuminate the target.

Description

This application claims the benefit of priority under 35 U.S.C. § 119 to U.S. Provisional Application No. 63/118,857, titled “Method and System for Estimating Distance Between a Fiber End and a Target”, filed on Nov. 27, 2020, the entirety of which is incorporated herein by reference. This application claims the benefit of priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 63/118,117, titled “Apparatus and Method for Enhancing Laser Beam Efficacy in a Liquid Medium”, filed on Nov. 25, 2020, the entirety of which is incorporated herein by reference. This application claims the benefit of priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 63/252,830, titled “Method and System for Estimating Distance Between a Fiber End and a Target”, filed on Oct. 6, 2021, the entirety of which is incorporated herein by reference. TECHNICAL FIELD The present disclosure generally relates to the field of optical fibers used in medical or therapeutic laser deliver. Particularly, but not exclusively, the present disclosure relates to a method and system for estimating distance between a fiber end and a target. BACKGROUND Introduction of lasers into the medical field and the development of fiber optic technologies that use lasers has opened numerous applications in treatments, diagnostics, therapies, and the like. Such applications range from invasive and non-invasive treatments to endoscopic surgeries and image diagnostics. For instance, in urinary stone treatment, the stones are required to be fragmented into smaller pieces. A technology known as laser lithotripsy may be used for such fragmenting processes, wherein for small to medium sized urinary stones, a rigid or flexible ureteroscope is placed through the urinary tract for illumination and imaging. Simultaneously, an optical fiber is inserted through a working channel of the ureteroscope, to a target location (e.g., to the location where the stone is present in the bladder, ureter, or kidney). The laser is then activated to fragment the stone into smaller pieces or to dust it. In another instance, a laser and optic fiber technology is used in coagulation or ablation treatments. During an ablation treatment, laser light is delivered to the tissue to vaporize the tissue. During a coagulation treatment, laser light is used to induce thermal damage within the tissue. Such ablation treatments may be used for treating various clinical conditions, such as Benign Prostate Hyperplasia (BPH), cancers such as prostate cancer, liver cancer, lung cancer and the like, and for treating cardiac conditions by ablating and/or coagulating a part of the tissue in the heart. These treatments which use laser and optic fiber technology require high amounts of accuracy to ensure that the laser is aimed at the right target (stone, tissue, tumor etc.), to achieve the clinical objective of tissue ablation, coagulation, stone fragmentation, dusting and the like. Accordingly, it is important to know the distance between the target and end of the optical fiber (distal end) where the laser light is emitted, since the laser treatment parameters, such as energy, pulse width, laser power modulation, and/or repetition rate, are often determined based on the distance between the tip of the optical fiber to the target. One of the existing techniques to estimate the distance between the distal end of an optical fiber and a target provides for measuring and comparing intensity values of reflections of the light beams, where the light beams are transmitted through the optical fiber by modulating the numerical apertures of the light beams. However, it is not always convenient to shift the numerical apertures of the light beams. Moreover, separation of the reflection of light beams of different numerical apertures, required for these techniques is difficult. BRIEF SUMMARY This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to necessarily identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter. In one aspect, the present disclosure relates to a system comprising first and second laser sources, an optical fiber, a light detector, and a processor and 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 pass laser light from the first and second laser sources out of the distal end and to receive reflected laser light into the distal end. The light detector may measure intensity of the reflected light. The processor and 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 a target based on