Multi-modality rotating optical system and method of use thereof

Abstract

Disclosed herein is a characterization system. The characterization system may include a stationary unit. The characterization system may include a rotation unit, if present, optically connected (e.g., via a FORJ) to the stationary unit. The rotation unit may include a first optical channel, a second optical channel, and a photodetector for detecting light for the first characterization modality. The photodetector may be a camera, an interferometer, or a spectrometer. The first optical channel and / or the second optical channel may include a single mode optical fiber, a multimode optical fiber, or multiple waveguides. The first optical channel may be optically connected to the photodetector. The stationary unit, if present, may be optically connected to the rotation unit, at least in part, by the second optical channel.

Description

[Technical field]

[0001] Priority Application This application claims the benefit of U.S. Provisional Patent Application No. 63 / 233,639, filed August 16, 2021, the disclosure of which is incorporated by reference in its entirety herein.

[0002] The present disclosure relates generally to methods and apparatus for detecting electromagnetic radiation for multimodal characterization of body lumens. [Background technology]

[0003] In many applications, multiple sample characterization modalities are used to characterize a sample. Multimodal characterization can be performed with different forms of optical radiation from a single fiber or multiple fibers. For rotational characterization systems, it can be difficult to transport the light beam from two or more optical fibers onto an optical rotary junction at high speed. Therefore, the use of an optical rotary junction in a multimodal system can result in degradation of image quality. Summary of the Invention [Means for solving the problem]

[0004] Sample characterization (e.g., of a material) can be performed in a rotational fashion with electromagnetic radiation (e.g., optical radiation) provided through a rotating probe. In a rotational characterization system, the electromagnetic radiation is often provided using a stationary electromagnetic radiation source (e.g., a light source) and transmitted to the rotating probe via an electromagnetic rotary junction (e.g., a fiber optic rotary joint (FORJ)). Transmitting signals for two or more modalities of optical characterization (e.g., interference imaging and diffuse spectroscopy) onto a single FORJ can be complex and some solutions (e.g., multi-channel FORJ) can degrade the performance of the characterization results (e.g., images, indications, or diagnostics), especially at high rotational speeds.

[0005] Indeed, there are biomedical applications where high fidelity, rapid data and image collection is important, such as intravascular characterization (e.g., imaging), where characterization of cardiovascular vessels over 100 millimeters may be desired in just a few seconds between flushes of the vessels (e.g., contrast or saline). Current technology for rotational characterization only approaches these rates when using a single characterization modality. Thus, additional means of transmitting signals for the characterization modalities between the stationary and rotating units of the sample characterization system are important for high-speed multimodal characterization. This disclosure recognizes that by using light beams generated or detected on the rotating unit, or both, and transmitting detected information (e.g., via other forms of energy) to the stationary unit, high fidelity and high-speed multimodal characterization is possible, thereby overcoming challenges in conventional optical systems.

[0006] Indeed, detecting electromagnetic radiation signals directly on the rotating device and transmitting the information by other means (e.g., wirelessly) is a solution to the shortcomings of multi-channel FORJ. Separating modalities before splicing of optical fibers can reduce FORJ complexity, reduce device size, increase signal-to-noise ratio (SNR), improve manufacturability, and reduce system cost. These improvements can improve characterization results (e.g., images, indications, diagnostics) from multiple signals (different signals can be, for example, electromagnetic radiation of different wavelengths). The present disclosure provides, among other things, a multi-modal characterization system that can be used to detect rotationally transmitted electromagnetic radiation interacted with tissue (e.g., coronary arteries) with high characterization sensitivity (e.g., OCT systems with sensitivity of greater than 90 dB, greater than 95 dB, greater than 100 dB, or greater than 110 dB) and at high rotational speeds (e.g., greater than 3,500 rpm, greater than 5,000 rpm, greater than 6,000 rpm, or greater than 10,000 rpm).

[0007] The rotating optical system may include a stationary unit housing a stationary portion of the device (e.g., an interferometer) and a rotating unit housing a rotating portion of the device (e.g., a probe). The stationary unit may include a means for applying a rotational torque to the rotating unit, which may include a rotatable probe (e.g., an inner portion of an imaging catheter) for the purpose of transmitting light circumferentially to a portion of a sample (e.g., the lumen of an artery) for imaging or characterizing an internal body structure. Typically, light is transmitted from a light source to the rotating unit via a FORJ. The rotating probe typically includes at least one optical channel (e.g., at least two optical channels) to carry light from the FORJ to the tissue and back through the FORJ to be detected by the stationary portion. The FORJ may have a maximum rotational speed up to the rated for operation. Commercially available prior art single channel FORJs may be rated up to 20,000 rpm for high fidelity operation with measured insertion loss of less than 0.5 dB and insertion loss variation with rotation of less than 0.5 dB. In the event of the desire for multimodal characterization where multiple signals are being transmitted to and from the sample, two or more optical channels (e.g., non-coaxial waveguides) may be desirable. FORJs with two or more optical channels are currently rated to have much lower rotational speeds than their single channel counterparts, limiting the speed of high fidelity multimodal characterization. For example, prior art FORJs for multichannel operation are rated at up to 3000 rpm for high fidelity operation and include higher insertion loss and insertion loss variation (e.g., with rotation). There are also manufacturing advantages to using a single channel FORJ, such as robustness (e.g., lifetime), reduced vibration, reduced size, and reduced cost. Multichannel FORJs may also be limited in the number of unique optical channels that can be multiplexed.

[0008] Certain characterization scenarios require high-fidelity and rapid characterization, for example, in the case of endoluminal characterization during blood flushing. During such endoluminal characterization, the probe rotates and translates at high speeds (sometimes exceeding 10,000 rpm) to perform the characterization pullback. The speed of pullback is crucial, since optical characterization is often only possible while blood is being flushed out of the artery, for example through a radiopaque contrast agent or saline. The pullback timescale is on the order of seconds (e.g., about 2 seconds). Currently, multichannel FORJ does not support high-fidelity characterization at these speeds. The present disclosure aims to overcome these limitations and provide a means to enable high-fidelity multimodal sample characterization at high speeds.

[0009] In view of these challenges, one objective of the present disclosure is to provide exemplary embodiments of systems, devices, and methods for rapid multimodal characterization. For example, multimodal characterization may include diffuse spectroscopy in conjunction with optical coherence tomography (OCT) / optical frequency domain imaging (OFDI - interchangeably referred to herein as OCT). Diffuse spectroscopy may include any form of spectral measurement in which diffuse light (e.g., multiply scattered light) is measured. Diffuse spectroscopy may include, without limitation, reflectance intensity measurements, fluorescence spectroscopy, Raman spectroscopy, UV spectroscopy, visible spectroscopy, near infrared spectroscopy (NIRS), short wave infrared spectroscopy (SWIRS), and infrared spectroscopy.

[0010] An exemplary method for performing OCT in combination with spectroscopy (e.g., NIRS) to perform multi-modal analysis of luminal tissue can be provided within the catheter, which can use an exemplary apparatus / device / arrangement according to an exemplary embodiment of the present disclosure to illuminate the tissue and collect scattered light from the tissue.

[0011] In some embodiments, multimodal characterization is performed by direct detection of the characterization modalities in the rotating unit of the device prior to FORJ, and the high fidelity use of a single optical channel FORJ can be used for other characterization modalities. In some embodiments, detection of a portion of the optical signal returned after interacting with the sample is performed in the rotating unit, converting the optical signal to another form of energy (e.g., electricity). The detected signal may be transmitted to the stationary unit in the converted energy form, or may be further converted before transmission (e.g., radio frequency (RF)). Coupling the rotating detector with the collection optical channel may or may not include a lens in the optical path (e.g., waveguide / detector direct coupling). In some embodiments, the detected signal in the rotating unit is transmitted continuously to the stationary unit during the characterization session. In some embodiments, the information carried by the detected signal may be temporarily stored on a computing storage device in the rotating unit until the characterization session is completed, and then transmitted (e.g., via an electrical docking contact) to the stationary unit. In some embodiments, the detected signal is transmitted continuously during the characterization session using an electrical rotary junction (e.g., an electrical slip ring). In some embodiments, the detection signal may be transmitted wirelessly using a wireless transmission protocol (e.g., RF-based) during characterization or at the end of the characterization session. In some embodiments, electrical energy may be transferred from the stationary unit to the rotating unit to generate light (e.g., LEDs) from within the rotating unit as a source emitter. In some embodiments, any combination of multiple rotating optical illuminators and rotating photodetectors may be deployed to perform any combination of multi-modal characterization scenarios.

[0012] According to one exemplary embodiment, the first characterization modality subsystem may be a spectroscopy subsystem, e.g., a near-infrared spectroscopy (NIRS) subsystem. The second characterization modality subsystem may be an imaging subsystem, e.g., an optical coherence tomography (OCT) subsystem. Each system may use its own light source or may use the same light source. The systems may be arranged such that light transmitted to the sample travels through a first illumination optical channel (e.g., a single mode fiber) and light received after interaction with the sample (e.g., a coronary artery) travels through two or more optical channels (e.g., a single mode fiber and a multimode fiber). In some embodiments, light for both modalities may be transmitted through a single waveguide through a single channel FORJ and detected through both the first waveguide (e.g., terminating in a stationary unit) and the second waveguide (e.g., terminating on a rotating unit) to provide separate optical characterization signals (e.g., interferometry and reflectance intensity). In some embodiments, the sample characterization system is a catheter system, for example a cardiac catheter, that can be used to rapidly characterize a patient's lumen (eg, an artery) in a multi-modal manner.

[0013] In some embodiments, the characterization system includes a rotation unit and, optionally, a stationary unit. If present, the stationary unit may optionally be optically connected to the rotation unit (e.g., via a FORJ). The rotation unit includes a first optical channel, a second optical channel, and a photodetector for detecting light for the first characterization modality. The photodetector may be a camera, an interferometer, or a spectrometer. The stationary unit may be optically connected to the rotation unit at least in part by the second optical channel. The first optical channel and / or the second optical channel may each independently include a single mode fiber, a multimode fiber, or multiple wave guides (e.g., multi-clad fiber). In some embodiments, the first optical channel is optically connected to the photodetector. In some embodiments, the second optical channel is used to detect light for a second characterization modality, for example, different from the first characterization modality.

[0014] In some embodiments, a method for rotational sample characterization is used. The method may include providing illumination light to the sample through a second optical channel. The second optical channel, the first optical channel, and the first photodetector may be rotated (e.g., by a motor). A signal may be collected from the sample through the first optical channel by the first photodetector during rotation. In some embodiments, a second signal may be collected from the sample through the second optical channel by a second (e.g., stationary) photodetector during rotation. In some embodiments, the sample may be characterized by a first modality (e.g., NIRS) using the signal collected by the first photodetector, and the sample may be characterized by a second modality (e.g., OCT) using the second signal collected by the second photodetector.

[0015] In some embodiments, the characterization system includes a rotation unit and, optionally, a stationary unit. If present, the stationary unit may optionally be optically connected to the rotation unit (e.g., via a FORJ). The rotation unit may include a first optical channel, a second optical channel, and a light source for providing illumination light. The first optical channel may be optically connected to the light source. The stationary unit may be optically connected to the rotation unit at least in part by the second optical channel. The first optical channel and / or the second optical channel may each independently include a single mode fiber, a multimode fiber, or multiple wave guides (e.g., multi-clad fiber).

[0016] In some embodiments, a rotation unit for a sample characterization system includes a rotatable housing. The rotation unit may further include a circuit board and a light detector or a light source or both disposed on the circuit board. The circuit board may be attached to the housing, for example, inside or outside the housing. The rotation unit may further include a first optical channel optically connected to the light detector or the light source. The rotation unit may further include a second optical channel disposed through the housing along an axis. The circuit board may be disposed at least partially around the axis. When both the light source and the light detector are disposed on the circuit board, the first optical channel may be optically connected to both the light source and the detector (e.g., using different waveguides in the channel), or there may be additional optical channels, such that the light source is connected to one channel and the detector is connected to a different channel.

[0017] In some embodiments, the multi-modality optical device has a proximal face and a distal face, a proximal optical port on the proximal face, and a distal optical port on the distal face. The optical device may include a first optical waveguide configured to transmit and receive a first characterization modality. In some embodiments, the first optical waveguide forms an optical connection between the proximal optical port and the distal optical port. The optical device may further include a second optical waveguide configured to transmit and receive a second characterization modality. The second optical waveguide may be optically connected to the distal optical port. The second optical waveguide may be optically connected to a detector, which may be housed within a rotation unit of the device.

[0018] Any two or more of the features described in this specification, including this summary section, may be combined to form an embodiment not specifically and explicitly described herein.

[0019] The drawings are presented herein for purposes of illustration and not for limitation. The foregoing and other objects, aspects, features, and advantages of the present disclosure will become more apparent and may be better understood by referring to the following description in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 illustrates a conventional OCT imaging system having a stationary unit and a rotating unit that is useful in understanding embodiments of the present disclosure.

[0021] [Diagram 2] FIG. 1 illustrates a multi-modal OCT and spectroscopic imaging system having a stationary unit and a rotating unit housing a non-light transmitting device, according to an exemplary embodiment of the present disclosure.

[0022] [Diagram 3] FIG. 1 is a detailed diagram of a conventional proximal rotation unit for an OCT system that is useful in understanding embodiments of the present disclosure.

[0023] [Figure 4] FIG. 13 is a detailed view of a proximal rotation unit with rotation detection and wireless transmission, according to an exemplary embodiment of the present disclosure.

[0024] [Diagram 5] FIG. 13 is a detailed view of a proximal rotation unit having rotation sensing and an electrical rotary junction according to an exemplary embodiment of the present disclosure.

[0025] [Figure 6] FIG. 13 is a detailed view of a proximal rotation unit with rotational detection and a docking station, according to an exemplary embodiment of the present disclosure.

[0026] [Figure 7] FIG. 13 is a detailed view of a proximal rotation unit having rotating illumination and detection and an electrical rotary junction according to an exemplary embodiment of the present disclosure.

[0027] [Figure 8] 1 is a cross-sectional view of a rotating circuit board having multiple detectors and light sources according to an exemplary embodiment of the present disclosure.

[0028] [Figure 9-1] 9A-D are diagrams of an optical channel / rotating detector coupling method according to an exemplary embodiment of the present disclosure. [Figure 9-2] 9A-D are diagrams of an optical channel / rotating detector coupling method according to an exemplary embodiment of the present disclosure.

[0029] [Figure 10A] FIG. 1 is a detailed view of a multi-channel catheter interconnection, according to an exemplary embodiment of the present disclosure.

[0030] [Figure 10B] FIG. 1 is a detailed view of a multi-channel distal catheter tip according to an exemplary embodiment of the present disclosure.

[0031] [Figure 11A]1A-1C are images of high-fidelity OCT and spectroscopy data acquired simultaneously during rapid rotation of a rotating optical system constructed in accordance with an exemplary embodiment of the present disclosure.

[0032] [Figure 11B] 13A-13C are images of high-fidelity OCT and spectroscopy data acquired simultaneously during fast pullback of a rapidly rotating rotating optical system constructed in accordance with an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] definition In order to make the present disclosure easier to understand, certain terms used herein are defined below. Further definitions for the following terms and other terms may be set forth throughout the specification. In this application, unless otherwise clear from the context or otherwise specified, (i) the term "a" may be understood to mean "at least one", (ii) the term "or" may be understood to mean "and / or", (iii) the terms "comprising" and "including" may be understood to include the listed components or steps, whether presented alone or with one or more additional components or steps, (iv) the terms "about" and "approximately" may be understood to allow for standard deviations that would be understood by one of ordinary skill in the art, and (v) when ranges are given, the endpoints are included. Any numbers used in this application, with or without about / approximately, are intended to cover any normal variations that would be understood by one of ordinary skill in the art. In certain embodiments, the terms "approximately" or "about" refer to a range of values ​​that is within 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less in either direction (greater or less than) the stated reference value, unless otherwise specified or apparent from the context (except when such number would exceed 100% of possible values).

[0034] "Light Source." As used herein, a "light source" refers to a source that provides (e.g., emits) light. Light is electromagnetic radiation (EMR) (e.g., photons). As used herein, the frequency (wavelength) of the light may or may not be within the visible spectrum. The light source may emit one or more of visible light, near infrared light, infrared light, long wavelength infrared light, ultraviolet light, deep ultraviolet light, and extreme ultraviolet light. In some embodiments, the light source may emit terahertz radiation. The light source may emit x-rays, microwaves, or radio waves. The light source may be, but is not necessarily, a laser. The light source may be, for example, a source including a light source with reduced temporal coherence, for example, a light emitting diode (LED) or a superluminescent diode (SLD). The light source may be a swept source, a tunable source, or a narrowband source. In some embodiments, the light source is a swept source laser. In some embodiments, the light source is a broadband source.

[0035] "Image." As used herein, the term "image" includes any visual representation, e.g., a photograph, a video frame, streaming video, and any electronic, digital, or mathematical analog of a photograph, video frame, or streaming video, as in the case of, for example, a two-dimensional or three-dimensional image of a tissue (or other sample). Any system or device described herein, in some embodiments, includes a display for displaying an image or any other result generated by the processor. Any method described herein, in some embodiments, includes a step of displaying an image or any other result generated by the method. Any system or device described herein, in some embodiments, outputs the image to a remote receiving device (e.g., a cloud server, a remote monitor, or a hospital information system (e.g., a Picture Archiving and Communication System (PACS))). In some embodiments, the image is generated using a fluorescent imaging system, a spectroscopic imaging system, a fluorescent imaging system, and / or a reflectance imaging system. In some embodiments, the tomographic image and the spectroscopic image are co-registered to form a composite image. In some embodiments, the image is a two-dimensional (2D) image. In some embodiments, the image is a three-dimensional (3D) image. In some embodiments, the image is a reconstructed image. An image (e.g., a 3D image) may be a single image or a set of images. One or more images may be formed by an imaging technique (e.g., using light provided by a light source).

[0036] "Probe." As used herein, a "probe" refers to a device or apparatus, or part of a subsystem, that delivers light from one or more light sources toward a sample. A probe may include one or more optical elements (e.g., by way of non-limiting example, one or more lenses, one or more mirrors, and / or one or more waveguides (e.g., optical fibers)). A probe may include any one or combination of one or more single mode fibers and one or more multimode fibers. For example, a probe may include one or more multi-clad fibers (e.g., double clad fibers). A probe may include a housing (e.g., a sheath, e.g., if the probe is part of a catheter).

[0037] "Sample." As used herein, a "sample" refers to a substance to be characterized. Generally, any material, mixture, or substance that can be characterized by light can be used as a sample. A sample may include one or more materials. A sample may be a gas, a fluid, or a solid. A sample may be, for example, a gel (e.g., a hydrogel), an elastomer, or a composite material. A sample may be a biological sample. For example, a sample may be an organ or biological structure (e.g., tissue) or a portion thereof. A sample may be an in vivo organ or an in vivo tissue. For example, a sample may be an in vivo artery or a portion thereof. A sample may include one or more features of interest. For example, a feature of interest may be, for example, arterial plaque (e.g., vulnerable plaque, e.g., having a fibrous cap).

[0038] "Spectroscopy." As used herein, "spectroscopy" refers to any form of characterization of a sample using a light source. The light source may have a narrowband (e.g., less than 2 nm) wavelength range (e.g., 1210.01-1210.02 nm, e.g., 1210 nm-1212 nm), a broadband wavelength range (e.g., 1160 nm-1280 nm), or two or more non-contiguous bands of wavelengths (e.g., 1205 nm-1215 nm and 1260 nm-1360 nm). For example, "visible spectroscopy" may refer to characterizing (e.g., imaging) a sample at visible wavelengths (e.g., 550 nm). As another example, "near-infrared spectroscopy / NIRS" may refer to characterizing (e.g., imaging) a sample at NIRS wavelengths (e.g., 1210 nm). In some embodiments, an image can be generated by scanning any light source over any area of ​​the sample, and this process may still be referred to as spectroscopy. This is because the image relates to the absorption and scattering properties of the sample in a particular wavelength range.

[0039] "Optical" is not limited to referring to visible light. For example, an optical channel may be constructed to transmit light having a frequency (wavelength) outside the visible spectrum, such as infrared or ultraviolet light. Similarly, "light detection," "optical modalities," and other similar terms may utilize light (electromagnetic radiation) outside the visible spectrum, such as infrared or ultraviolet light. Two components that are "optically connected" may be directly optically connected or may have one or more additional optical components (e.g., waveguide(s), lens(es), beam splitter(s), multiplexer(s)) and / or free space disposed between them along the optical path.

[0040] DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS Intraluminal characterization generally involves rapidly rotating a light source to image the inner circumference of an internal object, as is done in a typical catheter-based intravascular characterization system. Such a rotating optical system may include at least one light source for at least one tissue characterization mode. In some cases, the rotating optical system may perform single-modality characterization or multi-modality sample characterization using a single optical channel (e.g., single-mode fiber). In other cases, multi-channel optical systems (e.g., single-mode and multi-mode optical fibers) are required for sample characterization, for example, when performing structural characterization (e.g., by imaging with OCT) and absorption characterization (e.g., by diffuse spectroscopy).

[0041] Tissue characterization may be performed by non-interferometric or interferometric characterization, or both. In the case of interferometric characterization (e.g., OCT imaging), there may be a beam splitter (e.g., a polarizing beam splitter, a half mirror, a cube splitter, or a plate splitter) that splits the light source into a sample and a reference arm. The sample arm light may interact with the sample, and the reference arm light may interact with a reference reflector. After reflection, the sample and reference light are recombined, interfered, and directed to at least one detector (e.g., at least two) via a beam redirector (e.g., a circulator, e.g., a fiber coupler, e.g., a beam splitter, e.g., a polarizing beam splitter, etc.) to form interference fringes, which can then be detected. The detection may be performed using a spectral separation detection unit (e.g., a spectrometer) when a broadband light source (e.g., Spectral Domain OCT (SDOCT)) is deployed, or a time domain detection unit (e.g., at least one photodetector) when a swept source (e.g., Swept Source OCT (SSOCT)) is deployed. The broadband light source may be deployed with a time domain detector (e.g., Time Domain OCT (TDOCT), Light Detection and Ranging (LiDAR)). From the detector, the analog signal may be converted to a digital format and may be stored and processed on a computer storage device to display the characterization results (e.g., spectral measurements, e.g., images) or may be sent to a computer storage device to display the characterization results.

[0042] Non-interferometric characterization (e.g., NIRS) may use a narrowband light source (e.g., single wavelength), a broadband light source, or a variable wavelength light source. The light source may transmit and detect through at least one (e.g., at least two) optical channels. Detection may be performed using a spectral separation detection unit (e.g., a spectrometer), or a time domain detection unit (e.g., at least one photodetector, e.g., a CMOS, e.g., a charge-coupled detector (CCD)), or any combination of two or more of these. Importantly, when light illuminates tissue, reflection is not the only optical phenomenon that can occur. Detectors may be positioned to detect, at least in part, reflected light, refracted light, scattered light, transmitted light (e.g., the unabsorbed portion of the originally incident light), or light generated by the sample in response to light from any light source impinging on the sample (e.g., by photoluminescence (e.g., fluorescence, phosphorescence, or Raman emission), chemiluminescence, or bioluminescence).

[0043] A combination of characterizations may be performed. In some embodiments, a single light source may be used for multimodal characterization. In some embodiments, multiple light sources may be used for multimodal characterization. In some embodiments, the light sources may be combined into a single optical channel using an optical combining device (e.g., polarizing beam splitter, wavelength division multiplexer).

[0044] A FORJ may be used to couple light from a stationary waveguide to a rotating waveguide to transmit light to the sample in a rotational fashion. The rotating waveguide may be rotated by a rotational device such as a motor (e.g., via a direct drive, e.g., a drive belt), and the assembly (e.g., stationary waveguide, FORJ, motor, and rotating waveguide) may be displaced longitudinally (e.g., using an actuator) to scan (e.g., image) a portion of the sample. In the case of an intravascular probe (e.g., a catheter), another rotatable waveguide (e.g., a probe) may be connected in series to the rotating waveguide and may be housed within a non-rotating protective tube (e.g., a sheath). A drive shaft may be used to transmit torque from the proximal end of the probe to its distal tip.

[0045] The present disclosure also provides a method for improving the robustness of a rotating optical system by reducing free-space optical communication. In some embodiments, the rotating unit uses a waveguide (e.g., a reduced free-space beam director) to transfer optical energy between the rotating probe and the stationary system. For example, the FORJ may be connected (e.g., permanently connected, e.g., attached, glued, or spliced) to a multi-use optical fiber that is connected in series (e.g., optically coupled) to a waveguide in the single-use multi-channel rotating probe. In some embodiments, a 0 dB connector may be placed at the fiber connection point to improve the maintainability of the system. Furthermore, the rotation detector may have other multi-use waveguides in physical contact with it (e.g., glued or spliced) that connect in series to the waveguide in the single-use multi-channel rotating probe. Such direct contact may improve signal collection efficiency.

[0046] In some embodiments of the present disclosure, at least one light source is provided in the stationary unit and generates light that is transmitted to the rotating unit via a single channel FORJ. The rotating unit may house at least one optical channel having at least one photodetector, as well as a means for transmitting a detection signal to the stationary unit. The optical channel may be extended via a connection (e.g., a fiber interconnect) to the rotating probe to transmit the light to the sample. In some embodiments, the light transmitted to the sample may travel through a first illumination optical channel, and the light received after interaction with the sample may travel through at least one optical channel (e.g., an illumination optical channel and a collection optical channel). In some embodiments, the light sources for both modalities may be transmitted from the stationary unit through the single channel FORJ and may be detected via both the illumination optical channel (e.g., detected in the stationary unit for the first characterization modality) and the collection optical channel (e.g., detected on the rotating unit for the second characterization modality) to provide separate optical characterization signals (e.g., interferometry and reflectance intensity). Such an arrangement may be particularly useful when there is a large difference in strength between the signals detected for the different characterization modalities.

[0047] In some embodiments, the rotation detection signal may be transmitted to a stationary receiver via contacts (e.g., conductive) that are connected while the rotating unit is stationary (e.g., not performing characterization (e.g., imaging)). In some embodiments, the rotation detection signal may be temporarily stored in the rotating unit. In some embodiments, the detection signal may be transmitted wirelessly by wireless means (e.g., RF, Bluetooth). In some embodiments, the detection signal may be retransmitted wirelessly, for example, in free space (e.g., without physical contact), using a rotating optical emitter (e.g., LED) and a stationary detector (e.g., photodetector) to emit a light pulse / flash that conveys information about the detection signal. In some embodiments, the detection signal may be transmitted to a stationary receiver via an electrical rotary junction (e.g., slip ring) while the rotating unit is rotating (e.g., performing characterization) or while the rotating unit is stationary. In some embodiments, the electrical rotary junction may provide power while the rotating unit is rotating, but transmit the detection signal while it is not rotating (e.g., after performing characterization (e.g., after catheter pullback)) to improve signal fidelity. In some embodiments, timing and / or acquisition signals may be transmitted wirelessly from the stationary system back to the rotating unit, for example, through a wireless transmitter in the rotating unit. In some embodiments, the detected signal may be retransmitted optically using an aligned rotating light source and a stationary detector (e.g., optical slip ring). In some embodiments, the detected signal may be retransmitted optically using a misaligned rotating light source and a stationary detector, where a portion (e.g., reflection) of the rotating light source is sufficient to convey information about the detected signal. In some embodiments, the detected signal may be retransmitted optically and detected using a stationary circular (e.g., annular) active area photodiode. In some embodiments, the detected analog signal may be converted to a digital form before any form of rotating / stationary transmission.In some embodiments, further signal processing may occur within the rotating housing using a rotatable processing unit (e.g., a field programmable gate array (FPGA)). In some embodiments, the raw signals, the processed signals, or both may be temporarily stored within the rotating unit using small computer storage devices (e.g., a microcontroller) or other non-transitory memory (e.g., flash memory, read only memory (ROM), erasable programmable ROM, or electrically erasable programmable ROM).

[0048] In some embodiments, components on the rotating unit may require energy (e.g., power) to operate. In some embodiments, the rotating unit may house an energy storage device (e.g., a battery) that is charged (e.g., via electrical contacts) while the rotating unit is not moving. In some embodiments, the rotating unit may house an energy storage device (e.g., a battery) that is charged (e.g., via a wireless charging device) while the rotating unit is moving. In some embodiments, energy may be supplied to the rotating unit through an electrical rotary joint (e.g., a slip ring). In some embodiments, energy may be supplied to the rotating unit by an induction process.

[0049] In some embodiments, two or more light sources may be detected using a single detector housed on the rotating unit. In some embodiments, there may be two or more illumination optical channels and / or two or more collection optical channels. For example, in some embodiments, there may be a single illumination optical channel with two or more collection optical channels (each terminating in a separate detector housed in the rotating unit). In some embodiments, two or more collection optical channels may terminate on the same rotating detector after a combining means (e.g., a fiber coupler). In some embodiments, the illumination optical channel may be split and directed to two or more locations on the sample, for example, the distal end of the probe.

[0050] In some embodiments, multiple collection channels may be positioned to characterize separate locations, for example due to their relative positions at the distal end of the probe. In some embodiments, any single collection optical channel may be split (e.g., using a wavelength division multiplexer (WDM)) and directed to two or more optical detectors in (and / or off) the rotating unit. In some embodiments, a portion of the collection optical channel may be combined with an illumination optical channel (e.g., via a fiber coupler) and optically transmitted back through a FORJ (e.g., a single channel FORJ) for detection in the stationary unit, while the other portion is detected on the rotating unit. In some embodiments, an optical fiber with multiple waveguides (e.g., coaxial waveguides) may serve as the illumination and collection optical channels in a rotating probe. In some embodiments, a multi-waveguide optical fiber may split a portion of the signal from either or both of its waveguides and detect a portion of the optical signal on the rotating unit, allowing for a single optical channel probe.

[0051] Optical noise (e.g., resulting from slight alignment variations during rotation of the FORJ) may affect the SNR of the detection signal. To overcome this, in some embodiments, optical common mode rejection may be performed by splitting the illumination optical channel and performing simultaneous detection with the light returning from the collection optical channel. In some embodiments, a portion of the light from the illumination optical channel may be split off either before (e.g., in the stationary unit) or after (e.g., in the rotating unit) the FORJ to provide a reference measurement for calibration. Even after minimizing the source of noise, electrical noise may also be present. Thus, in some embodiments, before transmitting the rotation detection signal, the electrical waveform may be conditioned, cancelled, and / or amplified by electrical means (e.g., using electrical circuits) to improve the SNR. In some embodiments, the device used for signal improvement may include at least one transimpedance amplifier. In some embodiments, the device used for signal improvement may include a gain circuit or a level offset circuit, or both. In some embodiments, the device used for light detection may include a means of optically isolating optical components to minimize optical interference. In some embodiments, the device used for light detection may include a means of electrically isolating electrical components to minimize electrical interference. The reduced electrical noise ultimately allows for higher fidelity measurements. In some embodiments, the electrical shielding may include a Faraday cage (e.g., an enclosed metal container, e.g., an aluminum block). Furthermore, it may remain difficult to completely isolate electrical components over long distances, and unintended electrical interference may occur. Thus, in some embodiments, devices used for signal quality maintenance (e.g., single / differential circuits) may be used to preserve waveform fidelity during transmission of the detection signal. In some embodiments, the detected analog signal may be converted to a digital signal (e.g., via an analog-to-digital converter (ADC)) before transmission. Although such a processing unit may increase the complexity of the rotation circuit, higher fidelity measurements may be obtained, for example, by processing simultaneously at the point of detection.In some embodiments, the signal is processed after being transmitted (eg, to a remote computing device).

[0052] The collection optical channel may be coupled to the rotating detector in a number of ways that optimize light collection, manufacturing complexity, and device cost. In some embodiments, the active area of ​​the photodetector may be optically coupled directly (e.g., in physical contact or stabilized in close proximity) to the collection optical channel (e.g., multimode optical fiber). Indeed, there may be improved signal collection in a direct coupling scenario (e.g., due to reduced losses on intermediate optics) that can improve the SNR. In some embodiments, the collection optical channel may be aligned with beam shaping optics to optimize collection of light from the optical channel onto the detector. Thus, in some embodiments, focusing, diverging, or collimating lenses may be placed between the collection optical channel and the photodetector. Similarly, in some embodiments (e.g., spectrometers) that may use a spectral detector (e.g., spectrometers), a spectral diverging element(s) (e.g., fiber Bragg grating(s)) may be used between the collection optical channel and the detector.

[0053] In some embodiments, at least one light source is disposed in the rotating unit. In some embodiments, there may be multiple light sources in the stationary unit. In some embodiments, there may be multiple light sources on the rotating unit. It is further understood that in some embodiments, a portion of the return light from any light source may be detected in the stationary unit via the illumination optical channel.

[0054] In some embodiments, the light source may be modulated between lower and higher intensity states (e.g., on and off, e.g., bright and dark) to provide alternating modality characterization, e.g., to enable the use of different wavelengths for different characterization modalities along a single optical channel. The light source may alternate between light and dark phases (e.g., alternate between on and off) during operation at the following rates: at least 10 Hz, at least 100 Hz, at least 1 kHz, at least 2 kHz, at least 5 kHz, at least 10 kHz, at least 15 kHz, at least 20 kHz, at least 50 kHz, at least 75 kHz, at least 200 kHz, at least 1 MHz, or at least 10 MHz (e.g., not more than 10 GHz, not more than 5 GHz, not more than 2 GHz, not more than 1 GHz, not more than 500 MHz, not more than 250 MHz, not more than 100 MHz, not more than 50 MHz, not more than 10 MHz). In some embodiments, the light source may alternate between bright and dark phases with a frequency that corresponds to (e.g., proportional to) the number of rotations of a probe in a catheter, such as a cardiac catheter. If the light source is a swept source, the light source may be scanned across its wavelength range during the bright phase and, optionally, cycled during the dark phase.

[0055] In some embodiments, wavelength selective filters (e.g., high pass, e.g., low pass, e.g., dichroic, etc.) may be used to provide multimodal characterization with simultaneous illumination (e.g., at least two light sources in simultaneous bright phase). In some embodiments, polarizing filtering means (e.g., polarizing beam splitters) may be used to provide multimodal characterization. In some embodiments, a camera (e.g., one or more including a Bayer filter) (e.g., a CMOS camera) may be used as a rotation detector. In some embodiments, a spectrometer may be used as a rotation detector to isolate the wavelength-dependent reflection signal.

[0056] When adding components to a device that rotates at high speeds, balance and airflow are important factors in minimizing vibration. In some embodiments, the circuit board is manufactured such that the optical and electrical components disposed on and / or in optical and / or electrical communication with the circuit board are weight balanced to minimize vibration within the rotating unit. In some embodiments, vibration minimization may be achieved by designing the structural components of the rotating unit (e.g., the rotating device housing) to account for slight imbalances (e.g., in combination with a balanced circuit board). In some embodiments, vibration minimization may be achieved by adding other weight-balancing components. In some embodiments, the circuit board may be circular (e.g., annular). In some embodiments, the circuit board may be centered on the axis of rotation. In some embodiments, there may be more than one circuit board within the rotating unit. For example, there may be two stacked circuit boards (e.g., circular circuit boards with hollow centers) disposed within the rotating unit (e.g., within a rotating cylindrical tube). In some embodiments, the circuit board may be located outside the rotating unit (e.g., attached to the rotating housing).

[0057] For example, it is advantageous to have a modular system to separate devices that are in contact with the patient from those that are not. Thus, in some embodiments, the rotating unit may be attached to a removable component (e.g., a probe, such as in a catheter) to allow for a sterile workflow. In some embodiments, at least a portion of the rotating unit (e.g., a rotating probe) may be housed within such a removable component. In some embodiments, the removable component and its contents are single use, such as a rotating probe (e.g., a cardiac catheter). In some embodiments, the removable component and / or the rotating housing may include an information storage device (e.g., a microchip). This device transmits information wirelessly (e.g., via RF, such as radio frequency identification (RFID)), and / or via mechanical contacts (e.g., levers), and / or via electrical contacts. In some embodiments, this information informs which of the system's multi-modalities should be used in a given characterization session. In some embodiments, this information informs other aspects regarding the modulation of light sources and detectors during a characterization session (e.g., how many light sources or detectors to use, e.g., when to use a given light source or detector, e.g., what duty cycle of light and dark phases should be used for each light source or detector).

[0058] The present disclosure also includes methods to improve the sensitivity of the rotating optical system by reducing free space optics (e.g., reducing optical interfaces that may incur losses) and to improve the lifetime by using sacrificial connectors (e.g., reducing damage to permanent fiber components). In some embodiments, the rotating unit primarily uses waveguides (e.g., reduced free space beam directors) to transfer optical energy between the rotating probe and the stationary system. In some embodiments, each optical channel consists of two or more waveguides in series. For example, the FORJ may connect (e.g., permanently connect) to a multi-use optical fiber, which in turn may connect via an interconnect (e.g., via a single port of a dual interconnect) to a single-use waveguide in the rotating probe. Additionally, the rotating detector housed in the rotating unit may be physically contacted by other multi-use waveguides, which connect via an interconnect (e.g., via a single port of a dual interconnect) to a single-use waveguide in the rotating probe. For multi-channel probes, multi-channel interconnects (e.g., duplex interconnects) may be used to optimize automated connections (e.g., it may be easier to align and connect a single multi-port interconnect in an automated manner rather than multiple single single-port interconnects). In some embodiments, multi-channel probes with two or more optical channels for connecting multiple single-port interconnects may be attached (e.g., glued or bonded) together to mimic the benefits of a multi-port (e.g., duplex) interconnect. In some embodiments, sacrificial low-loss connectors may be used between segments of optical channels (e.g., to improve device lifetime). In some embodiments, a multi-use rotating waveguide may optically connect the FORJ to an eccentric waveguide in the rotating probe. In some embodiments, a multi-use rotating waveguide may optically connect light from the eccentric waveguide in the rotating probe directly to a rotating photodetector. In some embodiments, a multi-use rotating waveguide may optically connect the FORJ to a central waveguide in the rotating probe that is centered around the axis of rotation.In some embodiments, a multi-use rotating waveguide may optically couple light from a central waveguide about the axis of rotation within the rotating probe directly to a rotating photodetector.

[0059] The rotatable probe may include at least one (e.g., at least two) optical channels (e.g., double-clad fiber). In some embodiments, the rotatable probe may include one illumination optical channel (e.g., single mode fiber) and one collection optical channel (e.g., multimode fiber). In some embodiments, the illumination optical channel or the collection optical channel, or both, may have beam-refracting and / or reflective (e.g., mirrors) and / or shaping (e.g., lenses, e.g., non-flat reflective surfaces) components in their optical paths between the carrier waveguide and the sample.

[0060] As a comparator, FIG. 1 shows a block diagram of a conventional OCT (e.g., optical frequency domain imaging (OFDI)) imaging system / apparatus. Such an imaging system consists of a stationary optical system 100. The stationary optical system 100 may include an OCT light source 102, an interferometer 104, an OCT detector device 106, and a computer storage device 108. The stationary system 100 can function in connection with a rotating optical system 110 via a FORJ 112. For example, the rotating optical system 110 can include a rotating device housing 114 and an optical channel 116 (e.g., at least one single mode fiber in series). Such a system transmits light from the OCT light source 102 to the sample and receives back-reflected / scattered signals on the OCT detector 106 via the same optical channel to obtain sample characterization results, and processes / stores / displays the results using a computer / storage device / evaluation device 108. Optical transmissions are shown by solid lines and electrical transmissions are shown by dashed lines. An optical channel may include one or more waveguides (eg, single mode fibers, eg, double clad fibers) arranged coaxially (eg, on the same optical path).

[0061] In the figures, optical transmission (along optical path(s)) is shown by solid lines and electrical transmission is shown by dashed lines. An optical channel may include one or more coaxially arranged waveguides (e.g., single mode fibers, e.g., double clad fibers). For example, each coaxial waveguide is used for illumination and / or collection channels for different characterization modalities, or each coaxial waveguide is used as either an illumination channel or a collection channel for a single characterization modality. Signal (e.g., electrical) communication is shown by dashed lines. Dotted boxes represent conceptual sections of the device and are provided for illustrative purposes only.

[0062] As shown in Figure 1, a single channel FORJ may be used to transmit and receive light at high rotational rates that require only a single optical channel as found in a single characterization modality system. This disclosure describes, among other things, how to achieve multi-modal characterization at high rotational rates with systems that require multiple channels (e.g., systems that perform two or more characterization modalities).

[0063] 2 is a block diagram illustrating an exemplary embodiment of the present disclosure. The multimodal system / apparatus includes a stationary optical unit 200. The stationary optical unit 200 may include one or more of an OCT light source 202, a spectroscopic light source 204, a beam splitter 206 forming a reference channel, a beam combiner (e.g., WDM) 208 combining the two light sources, a spectroscopic reference detector 210 for detecting a reference measurement, an interferometer 212, an OCT detector 214, a computing device 216, and a transceiver device 218. The stationary system 200 may function in optical communication with a rotating optical unit 220 via a single channel FORJ 222. The rotating optical unit 220 may include, for example, one or more of a rotating device housing 224, an illumination optical channel (e.g., at least one tandem single mode fiber) 226, a collection optical channel (e.g., at least one tandem multimode fiber) 228, and a collection photodetector 230. The optical channel extending to the sample may be covered by a transparent sheath 232 for protection and safety considerations. The sheath 232 may remain stationary during operation, as in the case of, for example, an intravascular characterization catheter. The collection-detector device 230 may include a spectroscopic detector 234, as well as conditioning circuitry 236 (e.g., to improve the SNR of the detected signal), and a transmitter 244 (e.g., a slip ring, an RF transmitter, or an optical transmitter). The transmitter 244 may be a transceiver.

[0064] The system of FIG. 2 may transmit light from both the OCT light source 202 and the spectroscopic light source 204 to the sample, and may receive light interacted with the sample from both sources on both the OCT detector 214 (e.g., interference detection) through the illumination optical channel, and on the spectroscopic detector 234 (e.g., reflectance detection) through the collection optical channel. The spectroscopic detector 234 may convert the signal to an electrical format and may further undergo signal storage modification within the rotating unit 220. The signal may then be transmitted to a receiver for processing / storing / displaying the results, for example, using the computer / storage device / evaluation device 218 on the stationary unit 200. In some embodiments, the transmission is to a remote computing device (e.g., not part of the stationary unit 200).

[0065] As a comparator, in FIG. 3, an example of a conventional rotation unit for single-modality characterization is shown. Such an exemplary rotation unit 300 consists of a drive belt 306, a FORJ 308, a rotation device housing 310 for accommodating a multi-use waveguide 312, and an interconnect 314 for connecting to a single-use single optical channel probe 316. The entire rotation device may be located on a linear translation stage 318, allowing for back and forth translational motion. The probe housing 320 may be designed to connect to a stationary housing 320 for the rotation unit, thus remaining stationary while the internal optical probe 316 is rotated and translated. A stationary connecting fiber 302 connects the FORJ 308 to the stationary unit. The drive belt 306 connects to a motor 304 (which remains stationary relative to the rotation probe 316).

[0066] 4 is a cross-sectional view illustrating an exemplary embodiment for a rotation unit that enables high fidelity, high speed, multimodal rotational characterization. The rotation unit 400 may include a rotation device housing 410 for housing a FORJ 408 (e.g., a portion thereof), an interconnect 412, a circuit board 414, an illumination optical channel 416, a collection optical channel 418 that terminates on a light detection device 420 (e.g., a photodetector, optionally including optics), and a multi-optical channel probe 422 for transmitting and receiving light from the sample. A stationary unit may be operatively optically connected to the rotation unit 400 via a stationary optical fiber 402 that is operatively connected to the FORJ 408. A motor 404 that remains stationary relative to the rotation unit may be used to drive a drive belt 406 to transmit torque to the rotation unit 400. In some embodiments, a direct drive motor may be arranged without a drive belt. Inside the rotating device housing 410 there may be a wireless transmitter 424 (e.g., a radio transceiver) connected to a circuit board 414 to transmit data and / or receive information from the rotating unit to a wireless RF transceiver 426 on the stationary unit. At least a portion of the rotating unit may be mounted to a linear translation stage 428 to allow for back and forth translational motion. A probe housing 430 may be designed to house the optical probe 422 and function in conjunction with a stationary housing 432 for the rotating device, e.g., to remain rotationally stationary while the internal optical probe 422 is rotated and translated as part of the rotating unit 400. The illustrated housings and devices may be round (e.g., circular) or rectangular, for example.

[0067] FIG. 5 is a cross-sectional view illustrating an exemplary embodiment of a rotation unit that enables high fidelity, high speed, multimodal rotational characterization. The rotation unit 500 may include one or more of the FORJ 508 (e.g., a portion thereof), a rotation device housing 510 for housing interconnects 512, a circuit board 514, an illumination optical channel 516, a collection optical channel 518 terminating on a photodetector 520, and a multi-optical channel probe 522 for transmitting and receiving light from the sample. To transmit torque to the rotation unit 500, a motor 504 that remains stationary relative to the rotation unit may be used to drive a drive belt 506. In some embodiments, a direct drive motor may be disposed without a drive belt. The stationary unit may function in optical connection to the rotation unit 500 via a stationary optical fiber 502 that functions in connection with the FORJ 508. Outside the rotation device housing 510, there may be an electrical rotary joint 524 (e.g., an electrical slip ring) that transmits electrical signals between stationary and rotating contacts. The electrical rotary joint 524 may be disposed on an exterior surface of the rotating device housing 510. At least a portion of the rotating unit may be mounted on a linear translation stage 526 to allow for back and forth translational motion. A probe housing 528 may be designed to house the optical probe 522 and function in conjunction with a stationary housing 530 for the rotating device, e.g., to remain stationary while the internal optical probe 522 is rotated and translated as part of the rotating unit 500. Given the cross-sectional nature of the exemplary illustration, it will be understood that the housing and device may be circular, rectangular, or any other advantageous shape. The illumination optical channel 516 may be used as an optical collection channel for a second characterization modality, e.g., if a second detector is included within the stationary unit.

[0068] FIG. 6 is a cross-section showing an exemplary embodiment of a rotation unit that enables high fidelity and high speed multimodal rotational characterization. The rotation unit 600 may include one or more of the following: a FORJ 608 (e.g., a portion thereof), a rotation device housing 610 for housing an interconnect 612, a circuit board 614, an illumination optical channel 616, a collection optical channel 618 terminating on a light detection device 620 (e.g., a detector with optics), and a multi-optical channel probe 622 for transmitting and receiving light from the sample. The stationary unit may be operatively optically connected to the rotation unit 600 via a stationary optical fiber 602 operatively connected to the FORJ 608. A motor 604 that remains stationary relative to the rotation unit may be used to drive the drive belt 606 to transmit torque to the rotation unit 600. In some embodiments, a direct drive motor may be disposed without a drive belt. There may be a storage component on the rotation device housing 610 that is connected to the circuit board 616 and connected to electrical contacts 624. The electrical contacts 624 may physically contact stationary electrical contacts 626 (indicated by black arrows) to transmit data and / or receive information to / from the stationary unit at specific translational positions while the rotating unit is stationary. At least a portion of the rotating unit may be mounted to a linear translation stage 628 to allow for back and forth translational motion. A probe housing 630 (e.g., a sheath) may be designed to house the optical probe 622 and function in conjunction with a stationary housing 632 for the rotating device, e.g., to remain rotationally stationary while the internal optical probe 622 is rotated and translated as part of the rotating unit 600. 7 is a cross-sectional view illustrating an exemplary embodiment for a rotation unit that enables high fidelity, high speed, multimodal rotational characterization. The rotation unit 700 may include a drive belt 706, a rotation device housing 710 for housing a FORJ 708 (e.g., a portion thereof), an interconnect 712, a circuit board 714, an illumination optical channel 716, a light source 718, a second illumination optical channel 720, a collection optical channel 722 that terminates directly on a light detection device 724, and a multi-optical channel probe 726 for transmitting and receiving light from the sample. The stationary unit may be operatively optically connected to the rotation unit 700 via a stationary optical fiber 702 that is operatively connected to the FORJ 708. A motor 704 that remains stationary relative to the rotation unit may be used to drive the drive belt 706 to transmit torque to the rotation unit 700. In some embodiments, a direct drive motor may be arranged without a drive belt. On the rotation device housing, there may be an electrical rotary joint (e.g., a rotary transformer, e.g., an inductive coupling device) 724 connected to the circuit board 614 to transmit electrical signals from (e.g., and to) the rotation unit and, optionally, to provide power to the rotation unit. At least a portion of the rotation unit may be mounted to a longitudinal translation stage 730 to allow for back and forth translational motion. A probe housing 732 may be designed to house the optical probe 726 and function in conjunction with a stationary housing 732 for the rotation device, e.g., to remain rotationally stationary while the internal optical probe 726 is rotated and translated as part of the rotation unit 700.

[0069] FIG. 8 is a cross-sectional view illustrating an exemplary embodiment for a rotation unit that enables high fidelity, high speed, multi-modal rotational characterization. The rotation unit 800 may include a rotation device housing 802 for housing an annular circuit board 804, a first detector 806, a second detector 808, an illumination source 810, a wireless transceiver 812, and a processing unit 814. Due to the annular structure of the circuit board, the FORJ 816 and the optical channel interconnect 818 are visible when looking through the hollow center. A motor 820 is connected to the rotation device housing to provide rotational torque. In some embodiments, only one detector, only an illumination source, or only one detector and an illumination source are disposed on the circuit board. Although the circuit board 804 is illustrated as annular (e.g., to provide weight balance), it is not necessarily annular. Additionally, in some embodiments, a second circuit board may be included, e.g., another annular circuit board disposed in a different plane than the circuit board 804, or multiple circuit boards disposed in a common cross-sectional plane (e.g., each forming an arc of a wheel).

[0070] FIG. 9A illustrates an exemplary embodiment for coupling an optical channel to a rotating photodetector. On the left, an optical channel 902 is optically coupled to an active area 904 of a photodetector device 906 without any beam-changing optics in the optical path between the optical channel and the detector. In the arrangement on the left, the optical channel is in physical contact with the detector, but may simply be placed near the photodetector. On the right, the optical channel 902 is optically coupled to an active area 904 of the photodetector device 906 using a lens 908 placed between the optical channel 902 and the detector 906. In some embodiments, a fiber may be optically coupled to the detector without being in-line with it (e.g., a right-angle mirror placed therebetween). The optical system of FIG. 9B includes a beam splitter 910 (or mirror) that facilitates positioning the detector 906 at a right angle to the optical channel 902. Other angles may be used depending on the preferred arrangement of the components. The optical system of Figure 9C includes a dichroic / filter 912, which may be useful, for example, for fluorescence characterization modalities. The optical system of Figure 9D includes a fiber Bragg grating 914 for spectral separation and a camera 916 as a detector, which may be useful, for example, for broadband spectroscopy or Raman spectroscopy characterization modalities.

[0071] FIG. 10A shows the proximal end of a catheter used for characterization according to an exemplary embodiment of the present disclosure. On the proximal end of the catheter is a stationary portion 1000 that can be connected to a stationary housing for a rotation unit via an interlock mechanism 1002. In this illustration, an RFID 1004 for storing information is also on the stationary portion of the catheter. The proximal end of the catheter also has a rotatable portion 1006 that can be connected to the rotation unit via another interlock mechanism 1001. Also shown on the rotatable portion of the proximal end of the catheter is a multi-channel interconnect 1010 that allows for the extension of optical channels from within the rotation unit to the distal end of the catheter. The rotation unit may provide a rotational torque to the rotating portion of the catheter to rotate the optical channels and perform rotational characterization of the sample. It is understood that in some embodiments, once connected, the rotating portion of the catheter is considered to be part of the rotation unit.

[0072] 10B shows the distal end of a catheter used for characterization according to an exemplary embodiment of the present disclosure. Shown is a rotationally stationary sheath 1012, a rotatable drive shaft 1014, a first optical channel 1016, and a second optical channel 1018. At the tips of the optical channels may be beam redirecting and / or focusing optics for circumferential imaging during rotation. Such optics are illustrated here in the form of tilted ball lenses 1020 at the tips of each optical channel.

[0073] 11A shows an example of a multimodal image of a sample simultaneously characterized by multiple modalities during rotation of a rotating optical system used for characterization according to an exemplary embodiment of the present disclosure. The modalities used to form the image are OCT and NIRS spectroscopy. In this example, OCT is used to obtain a structural image of the sample based on its depth-dependent scattering properties, while NIRS is used to localize structures of interest (e.g., lipids) within the sample based on its bulk scattering and absorption properties. In this example, NIRS lipid detection is overlaid on the OCT image with both angled Lighthouse-style contrast as well as contrast shown with angles at the tip of each OCT line where lipids are detected.

[0074] FIG. 11B shows an example of a three-dimensional multimodal data set of a sample simultaneously characterized by multiple modalities during rotation and pullback of the rotating optical system used for characterization, according to an exemplary embodiment of the present disclosure. The top image shows a single slice of the OCT image volume along the pullback. The slice is located near the center of the imaging probe. The bottom image shows a flattened two-dimensional representation of the output of an algorithm for analyzing the NIRS data. Light areas indicate higher lipid signal and dark areas indicate lower lipid signal. The OCT data acquires three-dimensional data, with each dimension including a structure / location dimension. The NIRS data is also three-dimensional, but only two dimensions include structure / location information, while the other dimension includes the NIRS spectrum or rather the spectral dimension. In this example, the NIRS data shows the result of an algorithm designed to convert the spectral dimensions into lipid indices based on the spectral dimension information.

[0075] The multimodal data shown in Figures 11A-B was acquired at rotational speeds of over 10,000 rpm and pullback speeds of over 30 mm / s. This is consistent with state-of-the-art single-modality OCT systems and was achievable using a rotation unit according to embodiments of the present disclosure. As shown, the OCT modality maintains its theoretical high sensitivity (>100 dB) as well as high axial (10 μm) and lateral (40 μm) resolutions without being affected by the addition of the NIRS modality. The ability to perform high-speed multimodal characterization without sacrificing the performance of the OCT modality is a major strength of embodiments of the disclosed technology.

[0076] It is contemplated that the systems, devices, methods, and processes of the present disclosure encompass variations and adaptations developed using information from the embodiments described herein. Adaptations and / or modifications of the systems, devices, methods, and processes described herein may be made by those skilled in the art.

[0077] Throughout the description, when articles, devices, and systems are described as having, including, or comprising particular components, or processes and methods are described as having, including, or comprising particular steps, it is further understood that there are articles, devices, and systems according to particular embodiments of the disclosure that consist essentially of or consist of the recited components, and that there are processes and methods according to particular embodiments of the disclosure that consist essentially of or consist of the recited processing steps.

[0078] It should be understood that the order of steps or order for performing certain actions is immaterial, unless operability is lost. Moreover, two or more steps or actions may be conducted simultaneously.

[0079] It will be understood that the example procedures described herein can be stored on any computer accessible medium, including a hard drive, RAM, ROM (e.g., EPROM or EEPROM), removable disk, CD-ROM, memory stick, etc., and can be executed by a processing device and / or computing device that can be and / or include a processor, microprocessor, mini-, macro-, mainframe, etc. (including a plurality and / or combination thereof).

[0080] The foregoing merely illustrates the principles of the present disclosure.Various modifications and variations to the described embodiments will be apparent to those skilled in the art in light of the teachings herein.

[0081] Arrangements, systems, and methods according to exemplary embodiments of the present disclosure may be used with and / or implemented in and / or within any OCT system, OFDI system, SD-OCT system, TD-OCT system, or other imaging system, such as those described in the following documents: No. PCT / US2004 / 029148 (filed Sep. 8, 2004), published May 26, 2005 as International Patent Publication No. WO2005 / 047813, U.S. Patent Application No. 11 / 266,779 (filed Nov. 2, 2005), published May 4, 2006 as U.S. Patent Application Publication No. 2006 / 0093276, and U.S. Patent Application No. 10 / 501,276 (filed July 9, 2004), published January 27, 2005 as U.S. Patent Application Publication No. 2005 / 0018201, and U.S. Patent Application Publication No. 2002 / 0122246 (published May 9, 2002), the disclosures of which are incorporated herein by reference in their entireties. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements, and procedures which, although not explicitly shown or described herein, embody the principles of the present disclosure and which are therefore within the scope and spirit of the present disclosure. Additionally, all publications and references cited above are incorporated herein by reference in their entireties.

Claims

1. 1. A characterization system comprising: a stationary unit optically connected to a rotating unit; the rotation unit includes a first optical channel, a second optical channel, and a first detector; the stationary unit includes a second detector; a characterization system, wherein the first optical channel is optically connected to the first detector for detecting light for a first characterization modality, and the second optical channel is optically connected to the second detector for detecting light for a second characterization modality.

2. The system of claim 1 including two light sources.

3. The system of claim 2 , wherein the two light sources are optically connected to the second optical channel to provide illumination from the two light sources through the second optical channel.

4. The system of claim 2 , wherein only one of the two light sources is optically connected to the second optical channel to provide illumination from only one of the two light sources.

5. The system of claim 4 , wherein the rotating unit includes a third optical channel, and only one of the two light sources is optically connected to the third optical channel.

6. The system of claim 2 , wherein at least one of the two light sources is a swept source.

7. The system of claim 1 , wherein the first optical channel is also optically connected to the second detector.

8. 10. The system of claim 1, wherein the first optical channel comprises a single-mode waveguide and the second optical channel comprises a multimode waveguide, or the first optical channel comprises a multimode waveguide and the second optical channel comprises a single-mode waveguide.

9. The system of claim 1 , wherein at least one of the first optical channel and the second optical channel comprises two or more optical waveguides connected in series within the rotating unit.

10. 2. The system of claim 1, wherein the rotating unit includes a circuit board, the first detector is disposed on the circuit board, and (i) the circuit board and the first detector together are rotationally weight balanced about an axis, (ii) the rotating unit is rotationally weight balanced about an axis, or (iii) both (i) and (ii).

11. 2. The system of claim 1, wherein (i) the first characterization modality is optical coherence tomography, reflectance imaging, visible spectroscopy, NIRS, or Raman spectroscopy; and (ii) the second optical channel is an illumination channel for the second characterization modality that is different from the first characterization modality, and the second characterization modality is optical coherence tomography, reflectance imaging, visible spectroscopy, NIRS, or Raman spectroscopy.

12. 2. The system of claim 1, wherein the first optical channel is included within a first characterization modality subsystem for the first characterization modality, and the second optical channel is included within a second characterization modality subsystem for the second characterization modality, different from the first characterization modality.

13. The system of claim 12 , wherein at least one of the first modality subsystem and the second modality subsystem includes a photodetector.

14. The system of claim 12 , wherein at least one of the first modality subsystem and the second modality subsystem includes a camera.

15. The system of claim 12 , wherein at least one of the first modality subsystem and the second modality subsystem includes an interferometer.

16. The system of claim 12 , wherein the second optical channel is an illumination channel for the first characterization modality and the second characterization modality.

17. The system of claim 16 , wherein the second optical channel is a collection channel for the second characterization modality.

18. The system of claim 1 , wherein the first optical channel is an acquisition channel for the first characterization modality and the second optical channel is an illumination channel for at least the first characterization modality.

19. The system described in claim 1, wherein the rotating unit includes a light source and a third optical channel optically connected to the light source.

20. The system of claim 1 , wherein the rotation unit is operable to obtain measurements for the first characterization modality at a spatial sampling rate greater than 10 kHz.

21. The system of claim 1 , wherein the rotating unit includes an interconnect, and the first optical channel and the second optical channel are optically connected to the interconnect.

22. 22. The system of claim 21, wherein the rotating unit includes at least a portion of a FORJ, and wherein at least a portion of the second optical channel is disposed between the interconnect and the FORJ.

23. 23. The system of claim 22, wherein the first detector is disposed within the rotary unit between the FORJ and the interconnect.

24. The system of claim 1 , wherein the characterization system comprises a cardiac catheter.

25. 10. The system of claim 1, further comprising a light source constructed and arranged to emit light in a wavelength band that includes a characterization peak for characterizing arterial plaque.

26. The system of claim 1 , wherein the second characterization modality is different from the first characterization modality, and the second characterization modality is optical coherence tomography.

27. 27. The system of claim 26, wherein the first characterization modality is reflectance imaging, fluorescence spectroscopy, visible spectroscopy, NIRS, or Raman spectroscopy.

28. The system of claim 1 , wherein the rotating unit rotates at greater than 3,500 rpm during operation.

29. The system of claim 1 , wherein the rotating unit rotates at greater than 10,000 rpm during operation.

30. The system of claim 1 , wherein the characterization sensitivity of the system is greater than 100 dB for at least one of the first characterization modality and the second characterization modality.

31. 1. A system for rotating sample characterization, comprising: a first optical channel, a second optical channel, and a first photodetector; illumination light is provided to the sample through the second optical channel; the second optical channel, the first optical channel, and the first photodetector are rotatable; The system, wherein the first optical detector is configured to collect a first signal from the sample through the first optical channel during the rotation.

32. The system described in claim 31, including a second optical detector configured to collect a second signal from the sample through the second optical channel.

33. 33. The system of claim 32, comprising a first modality configured to characterize the sample using the signal collected by the first photodetector, and a second modality configured to characterize the sample using the second signal collected by the second photodetector.

34. 32. The system of claim 31 , comprising a first modality configured to characterize the sample using at least a portion of the signal collected by the first photodetector and at least a portion of the signal collected by the second photodetector.

35. The system described in claim 31, wherein the first optical detector is rotatable around the second optical channel.

36. A system as described in claim 31, comprising a light source and a third optical channel that is rotatable, and illumination light is provided from the light source through the third optical channel during said rotation.

37. The system described in claim 31, wherein light received from the sample is split so that a portion of the light travels through the first optical channel.

38. The system described in claim 31, wherein measurements from the signal are obtained at a spatial sampling rate greater than 10 kHz.

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