WO2017156176A1 - Articulation rotative à fibre optique et son procédé de formation - Google Patents
Articulation rotative à fibre optique et son procédé de formation Download PDFInfo
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- WO2017156176A1 WO2017156176A1 PCT/US2017/021433 US2017021433W WO2017156176A1 WO 2017156176 A1 WO2017156176 A1 WO 2017156176A1 US 2017021433 W US2017021433 W US 2017021433W WO 2017156176 A1 WO2017156176 A1 WO 2017156176A1
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- fiber
- optical fiber
- rotary joint
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- optic rotary
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/36—Mechanical coupling means
- G02B6/3604—Rotary joints allowing relative rotational movement between opposing fibre or fibre bundle ends
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/0209—Low-coherence interferometers
- G01B9/02091—Tomographic interferometers, e.g. based on optical coherence
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/264—Optical coupling means with optical elements between opposed fibre ends which perform a function other than beam splitting
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
- A61B1/00112—Connection or coupling means
- A61B1/00121—Connectors, fasteners and adapters, e.g. on the endoscope handle
- A61B1/00126—Connectors, fasteners and adapters, e.g. on the endoscope handle optical, e.g. for light supply cables
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
- A61B1/00163—Optical arrangements
- A61B1/00165—Optical arrangements with light-conductive means, e.g. fibre optics
Definitions
- the present invention relates to fiber optic rotary joints enabling the transmission of optical signals between fibers that rotate relative to one another.
- Fiber optic rotary joints are widely used for transmitting optical signals where one side of a fiber junction rotates freely. Numerous fields take advantage of these devices such as light communication through robotic joints, radar antennas based on slip-ring housings for satellite communication systems, military and civil radars. For applications in medical imaging and sensing, it is sometimes beneficial to use very broad spectral bandwidths, near ultraviolet (“UV”) to short-wave infrared (“IR”), as well as more specialized optical fibers such as double clad fiber. These conditions are very challenging for the current set of commercially available fiber optic rotary joints that use lenses in their optical design.
- UV near ultraviolet
- IR short-wave infrared
- the present approaches provide an unacceptable level of insertion loss, fiber abrasion, and fluctuating optical signal power at high spinning speeds.
- the fiber optic rotary joint includes a first stationary optical fiber inserted into and bonded to the capillary tube.
- the fiber optic rotary joint also includes a second optical fiber, having an end inserted into the capillary tube and in contact with the index-matching fluid, configured to be rotated by a rotatable fiber chuck.
- FIGURES 1 and 2 illustrate a partial block diagram and a pictorial view of an embodiment of at least a portion of a fiber optic rotary joint
- FIGURES 3, 4, and 5 illustrate graphical images showing exemplary insertion loss between transmitting and receiving fibers due to reflections, axial separation of single- mode fibers ("SMFs") and multi-mode fibers ("MMFs");
- SMFs single- mode fibers
- MMFs multi-mode fibers
- FIGURES 6 through 10 illustrate pictorial views of exemplary results from testing a suitability of an index-matching fluid
- FIGURES 11 through 13 illustrate graphical images of exemplary throughput power variations and power stability during continuous rotation of an optical fiber
- FIGURE 14 illustrates a flow diagram of an embodiment of a method of forming a fiber optic rotary joint.
- Embodiments will be described in a specific context, namely, a fiber optic rotary joint ("FORJ") constructed with optical fibers and methods of forming the same. While the principles of the present invention will be described in the environment of transmitting optical signals through fiber employing a fiber optic rotary joint, any application or related technology that may benefit from a device that can transmit electromagnetic energy through a rotary waveguide joint is well within the broad scope of the present invention.
- FORJ fiber optic rotary joint
- the fiber optic rotary joint may be applied in technologies for intravascular optical imaging in arteries using catheter endoscopes. This is most frequently accomplished by rotating the endoscope at high speed while pulling the endoscope back. This creates a spiral image of the artery. The artery should be flushed with a transparent fluid during imaging to clear the blood. This introduces an additional challenge peculiar to this application, namely, short bursts of rapid rotation of the FORJ at velocities exceeding 6000 revolutions per minute (“rpm”) for time duration of 4 - 6 seconds. The high rotational velocity is necessary due to the maximum volume/time allowed for the flush to ensure patient safety. This is, in fact, how commercial intravascular optical coherence tomography ("OCT”) systems function.
- OCT optical coherence tomography
- a multimodal system is introduced that integrates OCT with fluorescence lifetime imaging microscopy ("FLIM”) to characterize atherosclerotic plaques and garner information that has previously only been available in postmortem histopathology. Extending this multimodal approach to intravascular imaging invokes the attributes of the FORJ such as extremely broad bandwidth, high rotational velocity, and maintenance of modal integrity with a double clad fiber.
- FLIM fluorescence lifetime imaging microscopy
- optical coherence tomography OCT
- FLIM fluorescence lifetime imaging microscopy
- the fiber optic rotary joint is achromatic over a wide bandwidth, than it may include a lens, for instance, when changing a numerical aperture ("NA") of the fiber by adding a small segment of gradient index fiber to an end thereof.
- NA numerical aperture
- the terms single-mode and multi-mode as used herein refer to the spatial modes of light propagating down the fiber while the terms double, triple, etc., clad refer to the number of cores (or cladding) in the fiber.
- a double clad fiber as used herein may have a single-mode (inner) core and a multi-mode (outer) core.
- a fiber optic rotary joint can facilitate an intravascular OCT/FLIM system.
- the intravascular OCT/FLIM system is expected to play an increasing role in clinical imaging of heart patients during cardiac catheterization.
- the OCT/FLIM system may find a role in the assessment of the efficacy of therapies. To the extent that these needs come to fruition, the use of a fiber optic rotary joint is advantageous.
- fiber optic rotary joints Because of their various effective capabilities such as wide broadband signal transmittance, small space for building, and low signal loss, fiber optic rotary joints have been widely used for transmitting optical signals in many fields, for example, for robotic joints controlled with light signals in industry, and radar antennas based on slip-ring housings in military. In clinical fields, especially, by rapidly adapting intravascular imaging via a catheter, fiber optic rotary joints have become the chosen devices in clinical processes. Intravascular imaging of coronary and carotid arteries via a catheter is currently employed to obtain detailed information on the progression of atherosclerosis at high resolution. This information is advantageous for diagnosing and monitoring diseases as well as monitoring and guiding treatment.
- IV-OCT intravascular optical coherence tomography
- TCFA thin-cap fibroatheroma
- MVA minimal lumen area
- IVUS intravascular ultrasound
- IV-OCT is able to non-invasively produce morphological information with high resolution
- lipid rich plaque which is based on measuring interferometry and a back- scattered signal.
- multimodal techniques are beneficial to probe both the morphology and biochemistry of plaques.
- An integrated OCT with endogenous FLIM instrument is capable of quantifying biomarkers, which could quantitatively and sensitively classify plaque content as either lipid or collagen.
- Particular medical applications of a fiber optic rotary joint include, without limitation, endoscopy, light therapy, x-ray imaging, and lab, clinical, and surgical diagnostics.
- a catheter-based scanning system should be able to cover a broad wavelength spectrum from ultraviolet (“UV”) to infrared (“IR”), which leads to the need for fiber optic rotary joints that can operate over, without limitation, a 355-1310 nm bandwidth and accommodate double clad optical fibers.
- UV ultraviolet
- IR infrared
- an optical lens for a fiber coupling system is difficult to operate over a 355-1310 nm bandwidth.
- a mode-structure should be well maintained while scanning.
- Embodiments of a design for a connectorized end on the rotating portion of a rotary joint that allow for changing the catheter endoscope employ deionized water or other fluid for lubrication and index matching for the optical path between the ends of the two fibers.
- Attempts to form a lensless rotary joint using two fibers with ends butted together have used oil lubricants to index match and provide lubrication. The oils tend to break down when illuminated with ultraviolet light and damage the optical fibers.
- Prior lensless rotary joints used bare fiber connections that are difficult to work with because of their vulnerability to damage and the difficulty of inserting them into a rotary joint.
- the coupling efficiency, stability of the coupling efficiency, and mode-structure maintenance may be tested with different speeds of rotation.
- a fast photodetector can track an output power and its fluctuations. This measurement verifies system signal-to-noise ratio ("SNR").
- SNR system signal-to-noise ratio
- a beam profiler can be used.
- Optical coupling efficiency can be over 90 percent ("%").
- the rotary joint can be used and reused over a period of, for instance, at least several days without incident.
- the tested rotational speed was 8800 revolutions per minute ("rpm"), whereas the maximum rotational speed reported in the literature for a lensless rotary joint is 600 rpm.
- a combination of an OCT and FLIM system is employed in conjunction with a fiber optic rotary joint that can operate over, for instance, a 355-1310 nm bandwidth and accommodate double clad fibers.
- the fiber optic rotary joint can operate down to, for instance, 200 nm.
- the resulting ultra- broadband lensless fiber optic rotary joint is able to cover optical wavelengths from ultraviolet to infrared using a double clad fiber.
- the ultra-broadband lensless fiber optic rotary joint can comply with the demands of intravascular scanning device for OCT/FLIM systems.
- the fiber optic rotary joint is designed employing a capillary tube that couples a stationary fiber and a rotating fiber (i.e., an optical fiber functional as a first stationary waveguide and a second rotating waveguide).
- Both fibers may be double clad fibers (e.g., SM-9/105/125-20A, produced by Nufern), enabling the use of single-mode core for OCT and multi-mode core for FLIM.
- the capillary tube is filled with a fluid such as deionized water for matching a refractive index instead of an immersion oil (e.g., Olympus Immersion Oil Type F), which exhibits fluorescence and can damage a fiber from an ultraviolet laser.
- a fluid such as deionized water for matching a refractive index instead of an immersion oil (e.g., Olympus Immersion Oil Type F), which exhibits fluorescence and can damage a fiber from an ultraviolet laser.
- the resulting fiber optic rotary joint is able to achieve very low insertion loss (e.g. , less than 0.2 decibels (“dB”)) and output angular throughput power fluctuation (e.g. , 0.38 dB) with high spinning speed (e.g. , 8800 rpm/146 hertz (“Hz”)).
- high rotational speed the fiber optic rotary joint maintains a transverse electromagnetic ("TEM") mode-structure (e.g. , TEMoo mode-structure) from ultraviolet to infrared wavelengths with throughput efficiency above, for instance, 94 percent, which is less than 0.2 dB of insertion loss and less than 0.38 dB of angular power fluctuation during rotation at 8800 rpm/146 Hz.
- TEM transverse electromagnetic
- a transverse mode- structure of the output beam during high-speed rotation is well maintained with a TEMoo (Gaussian transverse distribution).
- TEMoo Gausian transverse distribution
- the fiber optic rotary joint includes a capillary tube 110 (e.g. , a cylindrical glass ferrule/capillary tube such as a FER- 1.8-126-GL produced by OZoptics), a first stationary optical fiber 160 and a second optical fiber 180 (a rotatable fiber), a rotatable fiber chuck 120 (e.g. , FPH-J produced by Newport), a motor 145 (e.g. , RE50 produced by Maxon Motor), and a pulley and belt arrangement (e.g. , first and second pulleys 165, 167 and a pulley belt 140).
- a capillary tube 110 e.g. , a cylindrical glass ferrule/capillary tube such as a FER- 1.8-126-GL produced by OZoptics
- a first stationary optical fiber 160 and a second optical fiber 180 a rotatable fiber
- a rotatable fiber chuck 120 e.g. , FPH-J produced by
- the shape of both ends of the capillary tube 110 is formed with a conically shaped counter sink to prevent damage of a bare fiber (such as the first stationary optical fiber 160 and the second optical fiber 180) when the bare fiber is passed through the capillary tube 110.
- An inner diameter of the capillary tube 110 is selected to accommodate the diameter of the bare fiber.
- the rotatable fiber chuck 120 within the rotating section is coupled to pillow- mounted bearings 125 and the first pulley 165 (a small diameter pulley).
- the rotatable fiber chuck 120 In order to use an optical fiber without a buffer jacket, the rotatable fiber chuck 120 is used that accommodates use of an optical fiber with less than, for instance, 250 micrometers (" ⁇ ") of outside diameter.
- the optical fiber at the rotatable fiber chuck 120 is bare double clad fiber that is passed through one side of the capillary tube 110.
- the rotatable fiber chuck 120 can be changeable.
- the motor 145 is coupled to a larger diameter second pulley 167 and rotates the rotatable fiber chuck 120 using the pulley belt 140. Based on the diameter ratio of the first and second pulleys 165, 167, a certain rotating speed of the rotatable fiber chuck 120 is achieved.
- One part of the second optical fiber 180 that is within the rotatable fiber chuck 120 is able to be connectorized with any commercial fiber connector (such as a ferrule connector or fiber channel/physical contact connector), an angled physical contact connector, and/or a subminiature version A connector.
- any commercial fiber connector such as a ferrule connector or fiber channel/physical contact connector
- the fiber optic rotary joint can be extendable to connect with another optic fiber component.
- Another side of the second optical fiber 180 at the rotatable fiber chuck 120 is bared and passes through one side of the capillary tube 110, which has, for instance, a 126 micrometer (" ⁇ ") diameter of an inner channel to fit a bared fiber.
- a side of an inner channel has a conical shaped counter sink, which helps for accessibility and to reduce damage at the cleaved surface of a bared fiber.
- an adapter 130 and connectorized fiber end 135 are coupled to an end of the second optical fiber 180 opposite the capillary tube 110 to connect to a system such as an OCT/FLIM system.
- the adapter 130 combines a rotated fiber with a fiber chuck.
- one end of the first stationary optic fiber 160 is bonded with to the capillary tube 110 and the other end is connected to a light source 170 via, for instance, an optical fiber connector 112 including a mating sleeve 115 and connectorized fiber ends 155.
- the first stationary optic fiber 160 is coupled to the second optical fiber 180.
- the inner channel of the capillary tube 110 is filled with a refractive index-matching fluid 190 such as deionized water, which also helps to provide lubrication between the capillary tube 110 and the first and second optical fibers 160, 180.
- the index-matching fluid 190 is illustrated in a gap 195 between the first and second optical fibers 160, 180.
- the refractive index of the index-matching fluid 190 is greater than or equal to 1.3. It is not necessary for the index-matching fluid to match the refractive index of the optical fibers because other properties thereof such as its absorption spectrum play a role in optically coupling the first and second optical fibers 160, 180. A refractive index greater than that of air (such as that of deionized water) can provide a significant role in optically coupling the first and second optical fibers 160, 180. In addition to being transparent over an operating bandwidth, the index-matching fluid should reduce (e.g., minimize) insertion loss due to reflections from, and separation between, the end faces of the first and second optical fibers 160, 180.
- the index-matching fluid 190 should be appropriate to cover a broadband wavelength from ultraviolet to infrared.
- the index-matching fluid 190 should present minimal optical absorption characteristics in the 355-1310 nm bandwidth, and provide less than about 0.5 dB loss.
- the capillary tube 110 is set on a three-dimensional XYZ translation stage 150.
- the XYZ translation stage 150 is configured to enable mechanical alignment of one or the other optic fiber along three mutually perpendicular axes.
- the first stationary optical fiber 160 is able to adjust lateral misalignment and axial separation to the second rotatable optical fiber 180 in order to improve or otherwise optimize coupling efficiency. From the XYZ translation stage 150, the first stationary optical fiber 160 is able to be aligned coaxially and be close to the second rotatable optical fiber 180 at the rotatable fiber chuck 120.
- a first small segment 197 and a second small segment 198 of gradient index fiber can be spliced to an end of the first stationary optical fiber 160 and the second optical fiber 180, respectively, to improve optical coupling therebetween.
- the end of the first stationary optical fiber 160 and the second optical fiber 180 (and/or the end of the first and second small segments 197, 198 of gradient index fiber(s)) can be shaped with curvature such as shaped with a spherical curvature to provide further improvement in optical coupling therebetween.
- the coupling loss between the fibers is less than 0.1 dB.
- the transmission mode-structure was tested with different rotation speeds of the rotatable optical fiber.
- the suitability of an index-matching solution, fluorescence emission and maintainability were checked of a bared fiber optic condition between an index-matching fluid and a bared fiber, which is connected with a pulsed 355 nm or 488 nm diode laser or a 1310 nm swept source (SL1310V1-10048, produced by Thorlabs).
- a fast photo detector was placed on the end of the rotating fiber for monitoring throughput power and power fluctuation during rotation of the fiber.
- a beam profiler (BP104-VIS/IR, produced by Thorlabs) was used.
- Equation (1), (2), and (3) describe insertion loss caused by mechanical misalignment from fiber separation and reflection.
- the insertion loss in terms of a refractive index of an index-matching solution with a gap between a transmitting and a receiving fiber can be theoretically estimated employing equations [1] to [3]:
- L is the insertion loss on a decibel (“dB”) scale due to reflection (ref), end-face separation in single-mode fiber (“SMF”), and in multi-mode fiber (“MMF”).
- Z 0 is an axial separation between two fiber end-faces
- NA is a numerical aperture of a fiber
- n t is a refractive index of a fiber
- r 1 is the radius of the Gaussian beam diameter in a multi-mode fiber
- w 0 is the spot size or mode field radius of a transmitting fiber
- n 2 is the refractive index of the medium inside the gap between the fibers.
- FIGURES 3, 4, and 5 Plots of equations (1), (2), and (3) are provided in FIGURES 3, 4, and 5, illustrating performance of an embodiment with the following assumptions.
- a numerical aperture ("NA") of 0.24 is assumed for a double clad fiber.
- the radius n is taken to be the radius of the multi-mode core, 52.5 ⁇ .
- the spot size w 0 is the mode field radius of the SMF core, 10.5 ⁇ .
- the refractive index 3 ⁇ 4 is 1.46 and the refractive index n 2 ranges from 1 to 2.
- FIGURE 3 illustrates insertion loss due to reflections with a line 310.
- FIGURE 4 illustrates with the several lines shown for various refractive indices and identified on the graph insertion loss due to separation of fiber end faces for a single- mode fiber ("SMF").
- FIGURE 5 illustrates insertion loss with the several lines shown and identified on the graph due to separation of fiber end faces for a multi-mode fiber ("MMF').
- the fiber is assumed to have
- equation 2 and FIGURE 4 can be interpreted as the leakage.
- higher index of refraction n 2 values can provide higher tolerances for fiber end-face separation, making alignment easier and reducing the potential for damage caused by bringing the two fiber ends into direct contact. Avoiding fiber damage by maintaining space between the two fiber end faces would be beneficial to achieving longer operational lifetimes for the fiber optic rotary joint. Based on these results, lubricants with refractive index equal to or larger than the fiber core would be desirable.
- Equations 4 and 5 describe the insertion losses L due to the separation of the two fibers Z 0 as function of the numerical aperture ("NA"), wherein V represents the fiber's V-number. If the NA of the light exiting the fiber is reduced, the insertion losses L at greater separation Z 0 are also reduced. In other words, if the NA is reduced, the separation between the two fibers may be larger while maintaining low losses. That will make it easier to align and reduce the risk of damaging the end face of the optical fibers.
- NA numerical aperture
- One method is to shape the end face of the fiber, providing some curvature. A relatively small curvature can positively impact the insertion loss L, while having a negligible impact on the achromatic behavior of the fiber optic rotary joint.
- a second method would be to splice a small segment of gradient index fiber to the end. It would have a similar effect, but have the advantage of having a flat end face and not have dependence on the refractive index of the index-matching fluid. As an example, see FIGURE 1 and the related text above. If it is desirable to use a curved fiber end face of an optical fiber to act as a lens, then the refractive index of the index-matching fluid should not match that of the optical fiber. It is recognized that the greater differences between the refractive indices, the less curvature is necessary to be formed on the end of the fiber to obtain the same change in the numerical aperture.
- the length of gap 195 may be short enough to produce an insertion loss of less than 1 dB.
- Zo/m can be used as a guide with respect to the insertion loss.
- Zo/m is less than 25 ⁇ for the single mode fiber (see, e.g. , equation 4) and Zo/m is less than 163 ⁇ for the multi-mode fiber (see, e.g. , equation 5).
- this is still specific to a particular fiber since losses are also dependent on fiber specific parameters (e.g., NA, mode field radius). It does, however, capture the relationship between refractive index of the fluid (m) and the separation at a target insertion loss.
- insertion losses in general, are provided as a maximum value (e.g. , less than 2 dB) and operational values (e.g. , less than 0.5 or 1 dB).
- the immersion oil had relatively low fluorescence emission as reported by the manufacturer. However, emission from the index matching fluid was much stronger. Based on these results, the immersion oil was used in further work since strong fluorescence from an index matching fluid introduces a strong background level for fluorescence imaging.
- the fiber optic rotary joint included a multi-mode fiber designed to be used with high power lasers (e.g. , FG050UGA, Thorlabs).
- the fiber had a core radius of 25 ⁇ and a NA of 0.22.
- the laser source was a 355 nm, nanosecond pulsed laser with a 10 kilohertz ("kHz") repetition rate. After initially achieving high power throughput, the power decreased dramatically within a few minutes. After disassembling the fiber optic rotary joint, there was physical damage to the fiber end faces.
- FIGURE 6 illustrates an end view and side view of a multi-mode fiber after a few minutes of submerging into an immersion oil (bar size about 50 um).
- FIGURE 7 illustrates an end view and side view of a double clad fiber after a few minutes of submerging into the immersion oil.
- FIGURE 8 illustrates an end view and side view of a double clad fiber after 20 minutes of submerging into the immersion oil.
- FIGURE 9 illustrates an end view and side view of a multi-mode fiber after 20 minutes of submerging in deionized water.
- FIGURE 10 illustrates an end view and side view of a double clad fiber after 20 minutes of submerging into the deionized water. In each case, the end view is shown in the image on the left, and the side view is shown in the image on the right.
- ultraviolet light was shined directly onto an index-matching fluid.
- a cleaved surface condition of a fiber was checked. Fluorescence emission from an index matching fluid and immersion oil was tested using an ultraviolet lamp (Mos-Cure Mini 365, U-VIX).
- a commercial index matching fluid has fluorescence emissions, which is not appropriate for interrupting a sample signal for the FLIM analysis.
- immersion oil and deionized water were tested, which does have substantially less auto-fluorescence emission in the ultraviolet range.
- the immersion oil and deionized water did not exhibit auto-fluorescence emission from exposure of the same ultraviolet lamp or a coupled ultraviolet laser.
- a cleaved fiber end face was substantially degraded when illuminated with a pulsed 355 nm laser.
- the smooth, cleaved fiber end face is essentially completely removed with deep pitting across the entire surface of the fiber core. While the fluorescence of the immersion oil is low, the absorption is sufficient to cause localized heating and thermal damage to the fiber.
- the double clad fiber a similar test was performed thereon (e.g. , SM-9/105/125-20A fiber). It has a multi-mode core approximately twice as big as the MMF, which should help mitigate the heating issue by lowering the laser intensity by a factor of about four.
- the core of the multi-mode fiber was pitted, and a damaged area of the fiber is visible on the cladding area.
- drops of oil remaining on the fiber are visible.
- substantial area of the fiber was substantially pitted and damaged.
- FIGURES 11 through 13 illustrated are graphical images of exemplary throughput power variations and power stability during continuous rotation of an optical fiber.
- FIGURE 11 illustrated is measured normalized angular output power variation (overlying lines 1120) from coupled optical signals either at 488 and 1310 nm with rotation of a fiber optic rotary joint with step- wise rotation through one cycle.
- normalized power 1110 with lasers turned off.
- the lines 1120 substantially lie on top of each other.
- illustrated is throughput power stability 1210 both fixed or rotated, the lines lying essentially on top of each other) from a 488 nm laser coupled to a multi-mode fiber core with a continuous rotation rate of 8800 rpm (146 Hz) over 20 seconds.
- FIGURE 11 shows the results for both wavelengths where the 1310 nm (single-mode core) and 488 nm (multi-mode core) light was coupled into the double clad fiber and the fiber optic rotary joint rotated through 360 degrees while measuring the output with a power meter.
- the peak-to-valley variation of the throughput power was 0.07 dB at 488 nm and 0.15 dB at 1310 nm.
- the mean and standard deviation of the output power are essentially identical for both the rotating and non-rotation case, i.e., within the accuracy of the measurements there is no variation in the insertion loss upon rotation.
- the fiber optic rotary joint was also tested during high-speed rotation using fast photodetectors .
- FIGURES 12 and 13 show the results of measurements with continuous rotation at 8800 rpm (146 Hz) over 20 seconds.
- the averaged output power was 24 mW from 488 nm and 9.95 mW from 1310 nm with continuous rotation.
- the intensity of the noise induced by rotation in the multi-mode core is therefore less than 1 percent.
- a spot size of one focused beam at a sample determines spatial resolution.
- a laser source that has good beam shape such as TEMoo (Gaussian) spatial mode
- good spatial resolution can be achieved.
- the mode-structure of a light source should be TEMoo. Since multimodal intravascular imaging with fluorescence lifetime imaging employs a short pulsed UV laser source, pursuit of a suitable lubricant continued.
- a solution is to simply lubricate the fiber optic rotary joint with deionized water. It has the requisite lack of absorption and emission over the desired spectral range.
- FIGURE 14 illustrated is a flow diagram of an embodiment of a method of forming a fiber optic rotary joint.
- the process flow begins in start step or module 1400.
- an index-matching fluid is provided in a capillary tube, an end of which may be conically shaped.
- the index-matching fluid may include deionized water and an alcohol or fluid that is optically transparent at a bandwidth of 355-1310 nm.
- a refractive index of the index-matching fluid matches a refractive index of a first stationary optical fiber and a second optical fiber, and the first stationary optical fiber and the second optical fiber may include double clad fibers.
- a first stationary optical fiber is inserted into the capillary tube.
- the first stationary optical fiber is then bonded to the capillary tube in a step or module 1415.
- an end of the first stationary optical fiber is coupled to a light source via, for instance, an optical fiber connector.
- the optical fiber connector may include connectorized fiber ends and a mating sleeve.
- an end of a second optical fiber is inserted into the capillary tube and in contact with the index-matching fluid.
- the second optical fiber is coupled to and held by a rotatable fiber chuck, in a step or module 1430, which is supported by a pillow-mounted bearing(s) via a step or module 1435.
- a step or module 1440 the pillow-mounted bearing(s) are coupled to a pulley and belt arrangement, which is coupled to a motor via a step or module 1445.
- a step or module 1450 an XYZ translation stage is coupled to the pillow-mounted bearing(s), and the second optical fiber is aligned within the capillary tube with the XYZ translation stage via a step or module 1455.
- the second optical fiber is rotated with respect to the first stationary optical fiber within the capillary tube by the rotatable fiber chuck via a motor. The method ends at a step or module 1465.
- a fiber optic rotary joint has thus been described herein for OCT/FLIM and other applications.
- the fiber optic rotary joint is capable of covering ultra-broadband wavelengths from ultraviolet to infrared (e.g. , 355- 1310 nm).
- the fiber optic rotary joint With a high rotational speed (such as 8800 rpm), the fiber optic rotary joint exhibits low insertion loss (e.g. , less than 0.2 dB) and low angular power variations.
- the resulting fiber optic rotary joint can be readily adopted in clinical applications.
- the integrity of the spatial mode can also be examined to ensure that light propagating down a single-mode core does not bleed into a multi-mode core at the interface of the two fibers.
- Some imaging technologies such as OCT, suffer from artifacts when executed with a multi-mode fiber.
- OCT optical coherence tomography
- the profile of the fiber output can be measured after the fiber optic rotary joint from light launches in both the single-mode and multi-mode cores. The measurements were taken while rotating the fiber optic rotary joint at 8800 rpm. The single-mode and multi-mode cores were illuminated with the 1310 and 488 nm light, respectively.
- the beam profiler either VIS (visible) or IR (infrared), was placed at a fixed distance from the output of the fiber with no optics between. Only the relative size and shape of the two profiles have meaning. It was expected that any significant coupling between the single-mode and multi-mode core would appear as broadening at the base of an otherwise Gaussian looking profile from the single-mode core. It is first noted that there is no apparent change in the spatial mode, comparing the fixed and rotating measurements from the single-mode core. It is also apparent that there is no significant shoulder on the profiles from the single-mode core that could be attributed to 1310 nm light propagating in the multi-mode core. While there may be some leakage into the multi-mode core, this evidence suggests that it is small and beyond our current measurement techniques.
- a lensless fiber optic rotary joint can be constructed by butting the ends of a fixed and rotating bare fiber, and can be made to operate over a broad spectral range with low insertion loss.
- Using deionized water as the lubricant and index matching fluid enabled operation down into the ultraviolet, at least to 355 nm, limited, for instance, only by the absorption spectrum of water and chromatic losses in the chosen fiber.
- the rotary joint can be operated at high rotational velocities, and was tested up to 8800 rpm. At this rotational velocity, there is very little added intensity noise due to rotational misalignment and little or no discernable change in the observed spatial mode of the 1310 nm light.
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- Optical Couplings Of Light Guides (AREA)
Abstract
L'invention concerne une articulation rotative à fibre optique formée avec un tube capillaire contenant un fluide d'adaptation d'indice et son procédé de formation. Dans un mode de réalisation, l'articulation rotative à fibre optique comprend une première fibre optique stationnaire insérée dans le tube capillaire et liée au tube capillaire. L'articulation rotative à fibre optique comprend également une seconde fibre optique, ayant une extrémité insérée dans le tube capillaire et en contact avec le fluide d'adaptation d'indice, conçue pour être mise en rotation par un mandrin de fibre rotatif.
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US201662305006P | 2016-03-08 | 2016-03-08 | |
US62/305,006 | 2016-03-08 |
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WO2017156176A1 true WO2017156176A1 (fr) | 2017-09-14 |
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PCT/US2017/021433 WO2017156176A1 (fr) | 2016-03-08 | 2017-03-08 | Articulation rotative à fibre optique et son procédé de formation |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CZ309936B6 (cs) * | 2022-03-21 | 2024-02-14 | České vysoké učení technické v Praze | Systém pro optickou datovou komunikaci a přenos optické energie určené pro přeměnu na elektrickou energii |
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US20020039472A1 (en) * | 2000-07-31 | 2002-04-04 | Hirokazu Takeuti | Preliminary member of optical device component with optical fiber |
US20060093276A1 (en) * | 2004-11-02 | 2006-05-04 | The General Hospital Corporation | Fiber-optic rotational device, optical system and method for imaging a sample |
US20110164255A1 (en) * | 2008-09-12 | 2011-07-07 | Kenji Konno | Rotation Optical Fiber Unit and Optical Coherence Tomography Image Forming Apparatus |
EP2437088A1 (fr) * | 2009-05-28 | 2012-04-04 | Konica Minolta Opto, Inc. | Connecteur optique et tomographe optique |
JP2012228510A (ja) * | 2011-04-11 | 2012-11-22 | Toyohashi Univ Of Technology | 医療用ドリルユニットおよびドリルならびに医療用加工装置 |
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- 2017-03-08 WO PCT/US2017/021433 patent/WO2017156176A1/fr active Application Filing
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
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US5307438A (en) * | 1992-08-13 | 1994-04-26 | Minnesota Mining And Manufacturing Company | Index matching compositions with improved DNG/DT |
US20020039472A1 (en) * | 2000-07-31 | 2002-04-04 | Hirokazu Takeuti | Preliminary member of optical device component with optical fiber |
US20060093276A1 (en) * | 2004-11-02 | 2006-05-04 | The General Hospital Corporation | Fiber-optic rotational device, optical system and method for imaging a sample |
US20110164255A1 (en) * | 2008-09-12 | 2011-07-07 | Kenji Konno | Rotation Optical Fiber Unit and Optical Coherence Tomography Image Forming Apparatus |
EP2437088A1 (fr) * | 2009-05-28 | 2012-04-04 | Konica Minolta Opto, Inc. | Connecteur optique et tomographe optique |
JP2012228510A (ja) * | 2011-04-11 | 2012-11-22 | Toyohashi Univ Of Technology | 医療用ドリルユニットおよびドリルならびに医療用加工装置 |
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CZ309936B6 (cs) * | 2022-03-21 | 2024-02-14 | České vysoké učení technické v Praze | Systém pro optickou datovou komunikaci a přenos optické energie určené pro přeměnu na elektrickou energii |
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