Optical coherence tomography using a self-testing imaging device

Abstract

Aspects of the present disclosure provide automated self-testing by an OCT imaging engine or device to identify and resolve faults or inefficiencies in the system or device hardware and / or software during imaging. The OCT imaging engine may include a catheter connection check system to check the quality of the physical connection points between the catheter and other components of the OCT imaging device or system. In some examples, the OCT imaging engine includes a self-testing engine implemented to perform routine self-testing by using an internal reference reflector of the OCT imaging engine to generate system performance data. The OCT imaging engine may use the system performance data to periodically look for and resolve faults or inefficiencies in the system. The OCT imaging engine may perform a self-calibration process to perform k-linearization and / or correct for chromatic dispersion using mirror measurements collected from an internal reference reflector.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 63 / 316,017, filed March 3, 2022, the disclosure of which is incorporated herein by reference. [Background technology]

[0002] Optical coherence tomography (OCT) is an imaging technique that uses light to capture cross-sectional images of tissues on a micron scale. OCT can be used in situ or in systems external to a sample, such as an organism or tissue.

[0003] A common problem with OCT imaging devices is poor image quality of the images produced by the device. Exemplary causes of poor image quality include hardware issues with either the probe or catheter used to image the object, or the hardware connection between the probe or catheter and other components of the OCT imaging device. Poor image quality may also be due to problems in the software used to receive the optical signal from the hardware sensor and convert the signal into a tomogram or other image. In some cases, OCT imaging devices may have multiple points of failure. Addressing these points of failure may require the device to be serviced by a trained field service technician, resulting in increased downtime and costs. Summary of the Invention [Problem to be solved by the invention]

[0004] Aspects of the present disclosure provide automated self-inspection by an OCT imaging engine or device to identify and resolve faults or inefficiencies in the hardware and / or software (i.e., hardware or software or both) of the system or device during imaging. [Means for solving the problem]

[0005] The OCT imaging engine may include a catheter connection check system for checking the quality of the physical connection between the catheter and the OCT imaging device or other components of the system. In some examples, the OCT imaging engine may include a self-test engine implemented to perform routine self-tests by using a reference reflector internal to the OCT imaging engine to generate system performance data. The OCT imaging engine may use the system performance data to periodically look for and resolve faults or inefficiencies in the system without user input or the use of devices external to the system, such as external tools. Trends in performance data collected by the system may also be monitored to discover system degradation before a fault occurs. In some examples, the OCT imaging engine may perform a self-calibration process to perform k-linearization or correct chromatic dispersion, which may automatically improve the performance of the OCT imaging engine through improved image quality. In yet another aspect, the OCT imaging engine may implement both the catheter connection check system and the self-test engine as described herein.

[0006] An aspect of the present disclosure provides an imaging system comprising: a light source adapted to be coupled to a first optical connector; a catheter adapted to be coupled to a second optical connector, the catheter adapted to be coupled to the light source using the first optical connector and the second optical connector; an interferometer comprising a plurality of optical switches, at least two of the plurality of optical switches connected to each other by a length of optical fiber, when in a first position, the plurality of optical switches form a first optical path for an optical signal to and from the light source and the catheter, and when in a second position, the plurality of optical switches form a second optical path for an optical signal to and from the light source along the length of optical fiber; and one or more processors configured to perform operations including receiving a back reflection of an optical signal at a connection point between the first optical connector and the second optical connector; and determining whether the catheter is fully connected to the light source or not based on the back reflection.

[0007] An aspect of the disclosure provides a method executed by one or more processors of an imaging system, the system comprising: a light source adapted to be coupled to a first optical connector; a catheter adapted to be coupled to a second optical connector, the catheter adapted to be coupled to the light source using the first optical connector and the second optical connector; and an interferometer comprising a plurality of optical switches, at least two of the plurality of optical switches connected to each other by a length of optical fiber, the plurality of optical switches forming a first optical path for an optical signal to and from the light source and the catheter when in a first position, and the plurality of optical switches forming a second optical path for an optical signal along the length of optical fiber to and from the light source when in a second position, the method including receiving a back reflection of an optical signal at a connection point between the first optical connector and the second optical connector, and determining whether the catheter is fully connected to the light source or not based on the back reflection.

[0008] An aspect of the disclosure provides one or more computer-readable storage media storing instructions that, when executed by one or more processors of an imaging system comprising: a light source adapted to be coupled to a first optical connector; a catheter adapted to be coupled to a second optical connector, the catheter adapted to be coupled to the light source using the first optical connector and the second optical connector; and an interferometer comprising a plurality of optical switches, at least two of the plurality of optical switches connected to each other by a length of optical fiber, when in a first position, the plurality of optical switches form a first optical path for an optical signal to and from the light source and the catheter, and when in a second position, the plurality of optical switches form a second optical path for an optical signal to and from the light source along the length of optical fiber, the interferometer causing the one or more processors to perform operations including receiving a back reflection of an optical signal at a connection point between the first optical connector and the second optical connector; and determining whether the catheter is fully connected to the light source or not based on the back reflection.

[0009] An aspect of the present disclosure provides an imaging system comprising: a light source adapted to be coupled to a first optical connector; a catheter adapted to be coupled to a second optical connector, the catheter adapted to be coupled to the light source using the first optical connector and the second optical connector; an interferometer comprising one or more optical switches and a reference reflector coupled to a first optical switch of the one or more optical switches; and one or more processors configured to perform operations including receiving an optical signal reflected by the reference reflector and calculating system performance data, the system performance data including one or more of a point spread function, a noise level, a signal-to-noise ratio, or a dynamic range.

[0010] An aspect of the present disclosure provides an imaging system comprising: a light source adapted to be coupled to a first optical connector; a catheter adapted to be coupled to a second optical connector, the first optical connector adapted to be coupled to the light source using the first optical connector and the second optical connector; an interferometer comprising one or more optical switches and a reference reflector coupled to a first optical switch of the one or more optical switches; and one or more processors configured to perform operations including receiving one or more mirror measurements using the reference reflector and the reference mirror; using the one or more mirror measurements to perform one or more of: calculating a dispersion-free k-spectrum, calculating a polynomial fit to the dispersion-free k-spectrum, calculating a dispersion spectrum, or calculating a spectrally flattened spectrum; and storing one or more of the calculated spectrum and the polynomial fit in a memory as a calibration spectrum.

[0011] Aspects of the present disclosure may include one or more of the features, including the features described below. In some examples, aspects of the present disclosure provide all of the features in combination.

[0012] In determining whether the catheter is fully or not fully connected to the light source based on the back reflection, the one or more processors are further configured to perform operations including calculating a return loss of the back reflection and determining whether the catheter is fully or not fully connected to the light source based on a comparison between the calculated return loss and a predetermined return loss threshold.

[0013] The one or more processors are further configured to perform operations including, in response to determining that the catheter is not fully connected, performing one or more of: outputting a prompt or signal indicating a potential problem with the catheter; and outputting data characterizing a quality of the physical connection between the catheter and the light source.

[0014] The one or more processors are further configured to perform operations including, in response to determining that the catheter is fully connected, one or more of: outputting a prompt or signal indicating that the catheter is fully connected, and outputting data characterizing a quality of a physical connection between the catheter and the light source.

[0015] The sample arm comprises a reference reflector coupled to a third optical switch of the plurality of optical switches, and the one or more processors are further configured to perform operations including receiving an optical signal reflected by the reference reflector and calculating system performance data, the system performance data including one or more of a point spread function, a noise level, a signal-to-noise ratio, or a dynamic range.

[0016] The one or more processors are further configured to perform operations including comparing the system performance data to one or more predetermined thresholds and outputting a result corresponding to the comparison.

[0017] The one or more processors are further configured to perform operations including comparing the system performance data to system performance data generated at an earlier time and outputting a result corresponding to the comparison.

[0018] The one or more processors are configured to perform operations including determining that the system is powered on and calculating the system performance data in response to receiving the optical signal and determining that the system is powered on.

[0019] The sample arm comprises a reference reflector coupled to a third optical switch of the plurality of optical switches, and the one or more processors are further configured to perform operations including receiving one or more mirror measurements using the reference reflector and the reference mirror, using the one or more mirror measurements to perform one or more of: calculating a dispersion-free k spectrum, calculating a polynomial fit to the dispersion-free k spectrum, calculating a dispersion spectrum, or calculating a spectrally flattened spectrum, and storing one or more of the calculated spectrum and the polynomial fit in a memory as a calibration spectrum.

[0020] The one or more mirror measurements include a plurality of mirror measurements taken from the reference reflector located on either side of a zero delay line.

[0021] The one or more processors are further configured to perform operations including loading the calibration spectrum and performing one or more of k-linearization, dispersion correction, or spectral flattening using the loaded calibration spectrum.

[0022] The one or more processors are further configured to perform operations including receiving the back reflection of the optical signal at the connection point when the catheter is not connected to the light source, and determining whether the connection point is degraded based on a return loss for the back reflection of the optical signal at the connection point when the catheter is not connected to the light source.

[0023] The one or more processors are further configured to perform operations including receiving one or more mirror measurements using the reference reflector and the reference mirror; using the one or more mirror measurements to perform one or more of: calculating a dispersion-free k spectrum, calculating a polynomial fit to the dispersion-free k spectrum, calculating a dispersion spectrum, or calculating a spectrally flattened spectrum; and storing one or more of the calculated spectrum and the polynomial fit in a memory as a calibration spectrum.

[0024] The one or more processors are further configured to perform operations including loading the calibration spectrum and performing one or more of k-linearization, dispersion correction, or spectral flattening using the loaded calibration spectrum.

[0025] The sample arm comprises a plurality of optical switches, at least two of which are connected to each other by a length of optical fiber, and when in a first position, the plurality of optical switches form a first optical path for an optical signal to and from the light source and the catheter, and when in a second position, the plurality of optical switches form a second optical path for an optical signal to and from the light source and the length of optical fiber, and one or more processors are configured to perform operations including receiving a back reflection of an optical signal at a connection point between the first optical connector and the second optical connector, and determining whether the catheter is fully connected to the light source or not fully connected based on the back reflection. [Brief description of the drawings]

[0026] [Figure 1A] FIG. 1 is a block diagram of an example OCT imaging engine having a catheter connection check system, according to an aspect of the present disclosure. [Figure 1B]FIG. 13 is a flow diagram of an example process for performing a catheter connection check on an OCT imaging engine, according to an aspect of the present disclosure. [Figure 1C] 1 is an example graph showing return loss for a damaged catheter interface optical connector detected by an OCT imaging engine. [Figure 1D] 1 is an exemplary graph showing the return loss from a catheter interface before and after successful catheter connection as measured by an OCT imaging engine. [Figure 1E] FIG. 1 is a block diagram of an example OCT imaging engine having a catheter connection check system, according to an aspect of the present disclosure. [Figure 2A] FIG. 1 is a block diagram of an example OCT imaging engine configured to perform self-assessment and calibration, according to an aspect of the present disclosure. [Figure 2B] FIG. 2 is a schematic diagram of a reference mirror of an OCT engine, according to an embodiment of the present disclosure. [Figure 2C] FIG. 2B is a block diagram of the reference reflector of FIG. 2A according to an embodiment of the present disclosure. [Figure 2D] FIG. 1 is a block diagram of an example OCT imaging engine configured to perform self-assessment and calibration, according to an aspect of the present disclosure. [Diagram 3] FIG. 13 is a flow diagram of an example process for self-assessment by an OCT imaging engine, according to an aspect of the present disclosure. [Figure 4A] 1 is a flowchart of an example process for self-calibration using a reference mirror and a reference reflector within an OCT imaging engine. [Figure 4B] FIG. 13 is a flow diagram for a self-calibration process performed by an OCT imaging engine, according to an aspect of the present disclosure. [Figure 5A] 1 is an example OCT imaging engine for performing both catheter connection checks and self-assessment and calibration, according to an aspect of the present disclosure. [Figure 5B]FIG. 1 is a block diagram of an example OCT imaging engine configured for dual catheter lengths to perform both catheter connection checks and self-assessment and calibration. [Figure 5C] FIG. 1 is a block diagram of an example OCT imaging engine that uses a 1×2 switch and a 2×2 switch to perform both catheter connection checks and self-assessment and calibration, according to an aspect of the present disclosure. [Figure 5D] FIG. 1 is a block diagram of an example OCT imaging engine that uses two 1x2 optical switches and one optical switch to perform both catheter connection checks and self-assessment and calibration, according to an embodiment of the present disclosure. [Figure 6] FIG. 1 is a block diagram of an imaging environment including an OCT imaging engine and a host computing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] [overview] Aspects of the present disclosure provide an OCT imaging engine configured to perform automatic self-tests to identify and address inefficiencies or fault points that affect the quality of images generated by the system. In some aspects of the present disclosure, the OCT imaging engine can automatically check the quality of an optical connector that forms a physical connection between a catheter and another component of the OCT imaging engine, such as a catheter interface configured to connect the catheter to the OCT imaging engine. The OCT imaging engine can use an internal length of optical fiber and an optical switch to measure the return loss of an optical signal reflected at the physical connection point to the optical connector. The internal length of the fiber can be equal to or substantially similar to the length of the attached catheter, for example, plus or minus 2 centimeters. In other examples, the internal length of the fiber can vary according to the maximum distance to which the reference mirror 130 can be adjusted, as described herein.

[0028] Based on the return loss, the OCT imaging engine can determine whether the connection is optimal, for example, by comparing the return loss to a predetermined threshold. As used herein, an "optimal" connection can refer to a connection that experiences little or no degradation (within a predetermined tolerance) in the path of the optical signal across the connection. Degradation can be caused by improper mating between optical connectors (e.g., resulting in voids between the optical connectors), debris (e.g., dirt or dust) at the connection points of the optical connectors, or voids between the optical connectors that disrupt glass-to-glass contact.

[0029] A connection point between two optical connectors may be a failure point if an optical signal cannot be transmitted across the connection point. A connection point between two optical connectors may be considered degraded if an optical signal can be transmitted across the connection point but at a reduced speed or of poor quality compared to a connection point without any source of degradation. A poorly transmitted optical signal may refer to a loss or degradation of the signal during transmission across the connection point during an imaging procedure.

[0030] If the connection points are found to be suboptimal, the OCT imaging engine can take any of a variety of different actions, such as generating a user output indicating a potential cause of failure in the system. For example, the OCT imaging engine can prompt the user to manually inspect the physical connection points, or to take steps to address the problem, such as by reseating the optical connector, prompting the user to replace the optical connector, or prompting the user to clean the optical connector.

[0031] In some embodiments of the present disclosure, the OCT imaging engine includes an internal reference reflector or calibration mirror that automatically receives information corresponding to the quality of the OCT imaging engine. The reference reflector can be inserted into the sample arm of the OCT imaging engine and used to receive optical signals that perform various diagnostic processes to quantify the performance of the OCT imaging engine. For example, the OCT imaging engine can self-assess its performance by calculating system performance data that can include one or more of the system's point-spread function (PSF), full-width half maximum (FWHM), noise level, signal-to-noise ratio, and dynamic range. The reference reflector can be coupled to the rest of the OCT imaging engine through an optical switch to allow the OCT imaging engine to switch between imaging mode and self-test mode.

[0032] The OCT imaging engine can provide system performance data, for example, after performing a self-test. The self-test can be performed, for example, upon startup of the OCT imaging engine or before an imaging procedure is to be performed by the system. The OCT imaging engine can determine whether the system performance data indicates system degradation and output suggestions or prompts to address potential causes of the degradation in system performance. If performance degrades, the system can also be prompted to recalibrate itself.

[0033] The OCT imaging engine can also perform self-calibration using a reference reflector and a reference mirror of its reference arm. The self-calibration can include one or more of k-linearization, dispersion correction, and spectral flattening. Aspects of the present disclosure provide for applying k-linearization, dispersion correction, and spectral flattening using a one-time calibration process and optical signals collected from a reference reflector and a reference mirror aligned to various different positions. The self-calibration described herein can provide improved OCT imaging engine performance, e.g., improved image quality, without the need for a k-clock. Through self-calibration, the OCT imaging engine can correct problems caused by, for example, dispersion introduced by environmental conditions or hardware degradation, such as degradation of optical components of the system.

[0034] In some examples, an OCT imaging engine with self-test described herein can be coupled to a cloud computing platform or other system to upload system performance data and / or calibration data (i.e., system performance data or calibration data or both) collected as part of the self-test. The collected system performance data can be used to monitor the performance of various deployed OCT imaging engines. Through the collected system performance data, one or more processors can implement predictive models, such as machine learning models, to predict when maintenance will be required for the OCT imaging engine before the system is shut down. Additionally, the collected system performance data can be useful in designing new versions of the OCT imaging engine to potentially mitigate or avoid issues causing poor image quality identified through the collected data.

[0035] In some aspects of the present disclosure, the OCT imaging engine can perform one or more of a catheter connection check, a self-test, and a self-calibration. The OCT imaging engine can receive an input that causes one or more optical switches to switch from an imaging mode to one of many different self-test modes. The OCT imaging engine can perform one or more of the self-test processes described herein automatically and without user input. The process can be performed quickly, for example, in less than one second, and the system can perform the self-test at various points during use. Combining the self-test with automated troubleshooting can reduce downtime and improve performance, resulting in increased user satisfaction and reduced costs by reducing the need for on-site field service.

[0036] Aspects of the present disclosure provide many technical advantages. The OCT imaging engine configured for self-testing described herein reduces or eliminates user input to identify and resolve faults or inefficiencies within the OCT imaging engine that may occur periodically, for example, as a result of continued use and wear of the device, or that may appear from time to time as a result of the design of the OCT imaging engine. Because user input can be reduced in resolving these faults, aspects of the present disclosure provide automated troubleshooting, improving the performance of the OCT imaging engine while reducing downtime caused by issues that would otherwise go unaddressed. The OCT imaging engine can use a reference reflector internal to the system to sample the optical signal to generate a calibration spectrum. Because the reference reflector is internal, the OCT imaging engine can automatically perform self-testing and calibration without the need to first connect an external device to the system.

[0037] [Example system] [Catheter connection check] FIG. 1A is a block diagram of an example OCT imaging engine 100A with a catheter connection check system 101A. In some examples, the OCT imaging engine 100A is or incorporates an optical interferometer. As will be appreciated by those skilled in the art, while one configuration of an OCT imaging engine is shown in FIG. 1A, variations of the system and different implementations, such as an in vivo OCT imaging engine, are within the scope of this disclosure. In some examples, the OCT imaging engine 100A can include more, fewer, or different components than those shown in the figure. The direction of optical or electrical signals, including optical signals, is indicated by arrows in FIG. 1A. Although the imaging engine 100A is described as using OCT, other imaging modalities can be used, such as intravascular ultrasound (IVUS), near infrared spectroscopy (NIRS), micro-OCT, or any other modality.

[0038] The light source 110 can be a swept laser source or a low coherence light source capable of capturing sub-micrometer level resolution. In some instances, an ultra-broad output of wavelengths of light is desirable. In some instances, a laser can be used as the light source. In yet other instances, a light emitting diode can be used as the light source. In some instances, the light generated in the light source 110 can be sent through a collimation lens (not shown).

[0039] Light from the light source 110 can be sent to a beam splitter 120. The beam splitter 120 can be an optical device that splits the beam of light from the light source 110 into two or more beams. The light split by the beam splitter 120 can proceed to a reference mirror 130 and a sample 140. An embodiment of the reference mirror 130 is further described with reference to FIG. 2B. The sample 140 can be an organic tissue or other sample on which OCT can be performed. In some examples, the sample 140 can be studied internally, as in an in vivo OCT scan. An optical signal, such as light from the light source 110, can be reflected from both the reference mirror 130 and the sample 140, and can be passed through an optical path that directs the light across the beam splitter 120 to a photodiode 150. The photodiode 150 can be a semiconductor or other device that converts light into an electrical current and allows for detection of the light.

[0040] When photons or light waves are incident on the photodiode, a current or another electrical signal is generated in the photodiode 150. The photodiode 150 may include one or more optical filters, lenses, or other components to focus the light and increase the signal-to-noise ratio. The signal generated in the photodiode 150 may be converted from an analog signal to a digital signal and processed by the digital signal processor 162. The digital signal processor may be a specialized microprocessor or integrated chip with architecture and / or software (i.e., architecture or software or both) optimized for the operational needs of digital signal processing. In some examples, the information generated in the photodiode 150 may be processed and sampled by the k-clock signal and converted into an image for display on the display 171 by the digital signal processor 162. As described further below, the digital signal processor 162 may perform one or more of the steps described below while optimizing the image generated from the study or observation of the sample 140.

[0041] The digital signal processor may include one or more processors or may be one of one or more processors. Aspects of the present disclosure include processes and computer readable instructions that cause one or more processors to perform the processes described herein. The one or more processors may include any of a variety of types of processors, including one or more central processing units (CPUs), graphic processing units (GPUs), field-programmable gate arrays (FPGAs), and / or application-specific integrated circuits (ASICs) (i.e., CPUs, GPUs, FPGAs, and / or ASICs).

[0042] Display 171 can display an image associated with sample 140. By way of non-limiting example, display 171 can be a monitor, an OLED screen, an LCD screen, a television, an electroluminescent display, or a quantum dot display. Other specialized screens or displays for special contrast ratios or to facilitate display of OCT information can also be used as display 171.

[0043] The OCT system may also include a k-clock (not shown). If the arrival time of the signal from the k-clock output to the DSP 162 is not synchronized with the signal from the main interferometer to the DSP 162, the interferogram cannot be sampled correctly. As used in this disclosure, an interferogram or interference pattern may be a pattern formed by wave interference, such as, for example, interference of light waves from the reference arm 125 and sample arm 135 of the OCT imaging engine 100A.

[0044] Synchronization issues can be introduced by mismatches in optical fiber lengths and electronic connections after a photodiode such as photodiode 150 (which can be, for example, bandpass filters or electrical cable lengths). In some examples, only a few percent of the light, for example 2%-3%, can be sent to the k-clock. A k-clock for an OCT imaging engine can include any combination of 90 degree phase shifters, zero crossing detection units, XOR or OR gates, or similar elements.

[0045] A separate beam splitter (not shown) may also split the light to the k-clock and beam splitter 120. In some examples, a small amount of light may be sent through the beam splitter to the k-clock. The k-clock may also be coupled to a separate photodiode (not shown). This may be similar to photodiode 150, which may be connected to the k-clock and may analyze the light incident on photodiode 191. The k-clock photodiode may be connected to a digital signal processor 162. Some of the light passes through the k-clock so that it may be analyzed separately from the light incident on or obtained from sample 140.

[0046] In some examples, optical fibers and related optical components such as optical couplers can be used in place of or in conjunction with the components described herein. For example, as will be appreciated by those skilled in the art, rather than using collimation lenses and beam splitters, optical couplers can be used to achieve the same or equivalent setup as described with reference to FIGS. 1A-2D. Light can follow a path determined by the fiber optic wires or other optical signal carriers. The use of optical fibers and optical couplers can provide a more robust and simpler optical device for use in commercial OCT applications. In some examples, the various components can be linked, controlled, and communicated through a suitable computing system, such as environment 600, further described below with reference to FIG. 6.

[0047] The OCT imaging engine includes a catheter connection check system 101A that can be located in the sample arm 135 as shown in FIG. 1A. The engine 101A can include two 1x2 optical switches: a first optical switch 160 and a second optical switch 165. In a first position, the optical switches 160, 165 shuttle optical signals between the catheter interface 170 and the beam splitter 120, as shown by optical path 180.

[0048] An optical switch is a device for switching optical signals from one or more sources to one or more different destinations. The sources and destinations may be optical fibers or other optical carrying cables for transmitting the optical signals to and from devices connected to the optical switch through the cables. An optical switch may receive inputs for switching the path of the optical signals from one or more sources to one or more destinations. An optical switch may be described at least in part according to the number of sources and destinations supported by the switch. For example, a 1x2 switch refers to a switch in which one source receives an input from a single source and passes it to one or both of two destinations. An optical switch may receive an input that specifies which of the two destinations receives the optical signal from the source. Other configurations are possible, such as a 1x3 switch. The current configuration of an optical switch, e.g., passing an optical signal from a first source to a second destination in the 1x2 case, is referred to as its position.

[0049] When the switches 160, 165 are moved to the second position, the optical switches 160, 165 cause the optical signal to pass through the fiber 184, as shown by light path 182. The fiber 184 is a length of optical fiber or other optical signal carrying cable. The length of the fiber 184 may be substantially equal to the length of the catheter 190, for example, plus or minus 2 centimeters. Differences in cable length may be compensated for by adjusting the position of the reference mirror 130. While the optical switches 160, 165 are in the second position, the OCT imaging engine 100A may be said to be operating in a "catheter connection check" mode.

[0050] When the switches 160, 165 are in a first position, the length of the optical path from the optical signal reflected from the sample 140 matches the length of the reference arm 125. When the switches 160, 165 are in a second position, the length of the optical signal from the beginning of the catheter 190 at the connection point 192 matches the length of the reference arm 125. Although the sample arm 135 is shown with two switches 160, 165, in some examples, the sample arm 135 can be configured to send and receive optical signals through either the first optical path or the second optical path using more or fewer switches. For example, FIG. 5B shows an OCT imaging engine 100D with multiple fiber lengths to handle catheters of different lengths.

[0051] When the switches 160, 165 are switched to the second position and the optical signal travels along the optical path 182, the OCT imaging engine 100A can test the catheter interface connection and determine whether the connection is successful by measuring the return loss in the glass-to-glass connection between the optical connector 188 for the catheter 190 and the optical connector 188 for the catheter interface 170. It has been observed that devices configured for OCT imaging can detect back reflections measured according to return loss (e.g., in decibels). For example, it has been observed that if the optical connector 188 for the catheter interface 170 is an angle-polished connector (APC), the measured return loss of the back reflection of the optical signal can be approximately -65 dB. The catheter interface 170 can include other types of connectors, such as a sacrificial joint and / or a fiber optic rotary joint, among others (i.e., a sacrificial joint and / or a fiber optic rotary joint).

[0052] When the catheter 190 is successfully connected to the catheter interface 170, at the optical connector connection point 192 (shown as the point where the catheter interface 170 is adjacent to the optical connector 188), there is a glass-to-glass connection that reduces reflections from the catheter interface connector by minimizing Fresnel reflections. Any contaminants, gaps, damage, alignment issues, or other potential points of failure or inefficiencies will cause the return loss of the back reflection of the optical signal at the connection point 192 to be higher than the return loss when the connection is successful.

[0053] In addition to checking the optical connector connection point 192, the DSP 162 can also receive a return loss for the optical signal reflected from other components of the catheter interface 170, such as a sacrificial joint or some other optical connector. In these examples, the DSP 162 can determine from the received return loss whether the component of the catheter interface 170 for connecting the catheter is damaged without the need to connect the catheter. In doing so, the DSP 162 can output a more specific prompt about the potential cause of degradation or failure, since it can eliminate at least the catheter 190 as a potential problem. The DSP can receive a back reflection of the optical signal at the connection point when the catheter is not connected to the light source. The DSP can determine whether the connection point is degraded based on the return loss for the back reflection of the optical signal at the connection point when the catheter is not connected to the light source.

[0054] The DSP 162 can calculate a return loss of the back reflection of the optical signal. The DSP 162 is configured to receive an input indicating that the switches 160, 165 are in a second position. Based on the received input, the DSP 162 can receive the input optical signal and determine a return loss of the back reflection of the optical signal. The DSP 162 can compare the measured return loss to a predetermined threshold that indicates a successful connection at the optical connector connection point 192.

[0055] If the DSP 162 determines that the return loss of the back reflection of the optical signal is not within a predetermined threshold, the DSP 162 can take a number of different actions in response. The DSP 162 can send a signal that causes a user output of the OCT imaging engine 100A to visually or audibly indicate that there is a potential problem with the connection point 192. For example, the DSP 162 can cause an LED or other light designated to indicate the status of the connection point 192 to blink or turn a particular color (e.g., red). Additionally or alternatively, the DSP 162 can cause a user display to project a message indicating the status of the connection point 192. In yet another example, the DSP 162 can cause a speaker coupled to the OCT imaging engine 100A to play an alarm sound or some other audible indication of a potential problem with the connection point 192. The DSP 162 can indicate a potential fault in the optical connector connecting the catheter interface 170 to the catheter 190, rather than a potential fault in the catheter interface 170 or the catheter 190. Because optical connectors are generally easier and less expensive to replace than the catheter 190 itself, the DSP 162 can automatically facilitate more efficient troubleshooting and repair of problems in the OCT imaging engine 100A.

[0056] If the DSP 162 determines that the return loss of the optical signal is within a predetermined threshold, the DSP 162 can perform a number of different actions in response. For example, the DSP can play a confirmation sound, cause an LED to blink or turn a certain color (e.g., green), and / or cause a confirmation message to appear on a display. In some examples, the DSP 162 can return the switch to position 1 and not generate any user output at the OCT imaging engine 100A if the DSP determines that the return loss is within a predetermined threshold of a successful connection. As described herein, FIG. 1B is a block diagram of an example process 105B for self-testing the optical signal connection point between the catheter interface and the catheter.

[0057] The predetermined threshold for the return loss can be empirically derived, for example, based on measurements of back reflection of the optical signal at a predetermined successful connection point. In some examples, the return loss for the optical signal at a successful connection point can be 20 dB to 30 dB, although the return loss can vary for different optical connectors, catheters, catheter interfaces, and / or other components of the OCT imaging engine (i.e., different optical connectors, catheters, catheter interfaces, and / or other components of the OCT imaging engine).

[0058] In some examples, the OCT imaging engine 100A is configured to perform a calibration to calculate a predetermined threshold indicative of a successful connection. This may be performed, for example, when a different optical signal carrying component of the OCT imaging engine 100A is replaced, potentially resulting in a different return loss for the optical signal at the point of successful connection. In other examples, the calibration may be performed in response to detecting a variation in the return loss of the component, for example exceeding a predetermined threshold.

[0059] FIG. 1B is a flow diagram of an example process 105B for performing a catheter connection check on an OCT imaging engine.

[0060] In accordance with block 110B, the digital signal processor receives back reflections from the physical connection point of the optical connector. As described herein with reference to FIG. 1A, back reflections may be received while the optical switch is set to the second position, i.e., the “catheter connection check” mode.

[0061] In accordance with block 115B, the digital signal processor calculates the return loss of the received back reflections. In some examples, the OCT imaging engine can send information characterizing the back reflections to another processor, e.g., external to the OCT imaging engine, for processing.

[0062] In accordance with block 120B, the digital signal processor receives a predetermined return loss threshold. The DSP may receive the return loss threshold, for example from an external source, or may calculate the return loss threshold as part of an initialization process each time the OCT imaging engine is powered on or receives a replacement optical component.

[0063] Per decision block 125B, the digital signal processor determines whether the calculated return loss is within a predetermined return loss threshold. If so ("YES"), per block 135B, the DSP may perform one or more actions in response to the return loss being within the predetermined threshold. The one or more actions may include outputting a prompt or signal indicating that the catheter is fully connected and outputting data characterizing the quality of the physical connection between the catheter and the light source.

[0064] If the DSP determines that the calculated return loss is not within a predetermined return loss threshold ("NO"), then, per block 130B, the DSP may perform one or more actions, including outputting a prompt or signal indicating a potential problem with the catheter and outputting data characterizing the quality of the physical connection between the catheter and the light source.

[0065] For example, by performing process 105B, the OCT imaging engine can perform a self-inspection of its own performance while optical imaging is being performed. In contrast to the use of external devices to measure the optical imaging equipment, or manual inspection, for example, by a field technician, the OCT imaging engine can automatically generate information for use in evaluating the performance of the system during operation. This process of automatically generating information related to system performance without external intervention can be referred to as "self-inspection." The calculated and compared return loss is an example of this type of information, at least because it is generated by the OCT imaging engine without the use of external devices or manual inspection, and it provides insight into the quality of the optical connection between the catheter and the rest of the engine. This insight is used to determine the presence of degradation in the connection.

[0066] FIG. 1C shows example graphs 198C and 199C illustrating the return loss for a damaged catheter interface optical connector detected by the OCT imaging engine. The x-axis of graphs 198C and 199C traces the distance in pixels from zero optical path difference, and the y-axis traces the return loss of the optical signal in decibels. Graph 198C shows the return loss at the optical connection point before the catheter is connected, with a peak return loss of approximately 90. Graph 199C shows the return loss of the back reflection at the optical connector connection point after the catheter is connected, with a similar peak return loss. Based on these measurements, the OCT imaging engine can determine a return loss threshold and use this threshold to compare the return loss for damaged and undamaged optical components of the OCT imaging engine.

[0067] FIG. 1D shows exemplary graphs 198D and 199D illustrating the return loss from a catheter interface before and after successful catheter connection as measured by an OCT imaging engine. The x-axis of graphs 198D and 199D tracks the distance in pixels from zero optical path difference, and the y-axis tracks the return loss of the optical signal in decibels. Graph 198D shows the return loss of the optical connection point before the catheter is successfully connected, with a peak loss of about 70 dB. Graph 199D shows the return loss of the optical connection point after the catheter is connected, with a peak loss of about 50 dB, i.e., a difference of about 20 dB to 30 dB.

[0068] FIG. 1E is a block diagram of an example OCT imaging engine 100A' having a catheter connection check system 101A'. The OCT imaging engine 100A' can include the same components as described herein in connection with the OCT imaging engine 100A of FIG. 1A and can be configured to operate in a similar manner. However, as shown in FIG. 1E, the components for the catheter connection check system 101A' are included in the reference arm 125' rather than in the sample arm 135'. The catheter connection check system 101A' can include two 1x2 optical switches, a first optical switch 160' and a second optical switch 165'. In a first position, the optical switches 160', 165' shuttle an optical signal between the reference mirror 130' and the beam splitter 120, as shown by the optical path 180'.

[0069] When the switches 160', 165' are changed to the second position, the optical switches 160', 165' cause the optical signal to pass through the fiber 184', as shown by the optical path 182'. The fiber 184' is a length of optical fiber or other optical signal carrying cable. The length of the fiber 184' can be configured based on the length of the catheter 190 so that the OCT imaging engine 100A' can check whether the catheter 190 is properly connected to the catheter interface 170. For example, the length of the fiber 184' can be substantially equal to the length of the catheter 190, plus or minus 2 centimeters. The difference in cable length can be compensated for by adjusting the position of the reference mirror 130'. While the optical switches 160', 165' are in the second position, the OCT imaging engine 100A' can be said to be operating in a "catheter connection check" mode.

[0070] When the switches 160', 165' are in a first position, the length of the optical path from the optical signal reflected from the reference mirror 130' matches the length of the sample arm 135' to the connection point 192 to the catheter interface 170. When the switches 160', 165' are in a second position, the length of the optical signal from the end of the catheter 190 at the sample 140 matches the length along the reference arm 125' to the reference mirror 130'. Although the reference arm 125' is shown with two switches 160', 165', in some examples the reference arm 125' can be configured to send and receive optical signals through either the first optical path or the second optical path using more or fewer switches.

[0071] When the switches 160', 165' are switched to a first position and the optical signal travels along the optical path 180', the OCT imaging engine 100A' can inspect the catheter interface connection and determine whether the connection is successful by measuring the return loss at the glass-to-glass connection at the connection point 192 between the optical connector 188 and the catheter interface 170. It has been observed that devices configured for OCT imaging can detect back reflections measured according to return loss (e.g., in decibels). For example, it has been observed that if the optical connector 188 for the catheter interface 170 is an angle-polished connector (APC), the measured return loss of the back reflection of the optical signal can be approximately -65 dB. The catheter interface 170 can include other types of optical components, such as sacrificial joints and / or fiber optic rotary joints, among others. The return loss of these components can also be measured.

[0072] When the catheter 190 is successfully connected to the catheter interface 170, there is a glass-to-glass connection at the optical connector connection point 192 (shown as the point where the catheter interface 170 is adjacent to the optical connector 188) that reduces reflections from the catheter interface connector by minimizing Fresnel reflections. Any contaminants, voids, damage, alignment issues, or other potential points of failure or inefficiencies will cause the return loss of the back reflection of the optical signal at the connection point 192 to be higher than the return loss when the connection is successful.

[0073] In addition to checking the optical connector connection point 192, the DSP 162 can also receive a return loss for the optical signal reflected from other components of the catheter interface 170, such as a sacrificial joint or some other optical connector. In these examples, the DSP 162 can determine from the received return loss whether the component of the catheter interface 170 for connecting the catheter is damaged without the need to connect the catheter. In doing so, the DSP 162 can output a more specific prompt about the potential cause of degradation or failure, since it can eliminate at least the catheter 190 as a potential problem. The DSP can receive a back reflection of the optical signal at the connection point when the catheter is not connected to the light source. The DSP can determine whether the connection point is degraded based on the return loss for the back reflection of the optical signal at the connection point when the catheter is not connected to the light source.

[0074] The DSP 162 can calculate a return loss of the back reflection of the optical signal. The DSP 162 is configured to receive an input indicating that the switches 160', 165' are in a first position. Based on the received input, the DSP 162 can receive the input optical signal and determine a return loss of the back reflection of the optical signal. The DSP 162 can compare the measured return loss to a predetermined threshold that indicates a successful connection at the optical connector connection point 192.

[0075] If the DSP 162 determines that the return loss of the back reflection of the optical signal is not within a predetermined threshold, the DSP 162 can take a number of different actions in response. The DSP 162 can send a signal that causes a user output of the OCT imaging engine 100A to visually or audibly indicate that there is a potential problem with the connection point 192. For example, the DSP 162 can cause an LED or other light designated to indicate the status of the connection point 192 to blink or turn a particular color (e.g., red). Additionally or alternatively, the DSP 162 can cause a user display to project a message indicating the status of the connection point 192. In yet another example, the DSP 162 can cause a speaker coupled to the OCT imaging engine 100A' to play an alarm sound or some other audible indication of a potential problem with the connection point 192. The DSP 162 can indicate a potential problem with the optical connector connecting the catheter interface 170 to the catheter 190, rather than a potential problem with the catheter interface 170 or the catheter 190. Because optical connectors are generally easier and less expensive to replace than the catheter 190 itself, the DSP 162 can automatically facilitate more efficient troubleshooting and repair of problems in the OCT imaging engine 100A'.

[0076] [Self-assessment and self-calibration] FIG. 2A is a block diagram of an example OCT imaging engine 100B configured to perform self-assessment and calibration.

[0077] The OCT imaging engine 100B may include a self-assessment and calibration engine 101B. The self-assessment and calibration engine 101B may include an optical switch 260 and a reference reflector 286. The switch 260 may be 1x2 defining two optical paths 280, 282. In a first position, the switch 260 directs the optical signal along the optical path 280 to and from the catheter interface 170. In a second position, the switch 260 directs the optical signal along the optical path 282 to and from the reference reflector 286. While the switch 260 is in the second position, the OCT imaging engine 100 may be said to be in a "self-assessment and calibration" mode.

[0078] The OCT imaging engine 100B can be further configured to simultaneously correct for nonlinear sampling and chromatic dispersion to automatically calibrate the system by optimizing the spectrum using k-linearization (KL) wavenumber linearization, dispersion correction (DC), and spectral flattening. The system can perform calibration without the use of an external k-clock to compensate for nonlinear sampling in k-space.

[0079] The OCT imaging engine 100B uses the positions of one or more of the reference mirror 130 and the reference reflector to generate information related to the performance of the optical system, which can be used in the methods described herein. In some examples, the information generated from positions P1 and P2 can be used to calculate a spectral wavelength linearization and a spectral flattening spectrum, as further described with reference to Figures 3-4B.

[0080] 2B is a schematic diagram of a reference mirror 130 of an OCT engine 100B according to an embodiment of the present disclosure. The reference mirror 130 can be a mirror or other reflective surface with high reflectivity and optical properties that allow for reflection of photons. The OCT imaging engine 100B can scan the mirror 130 in the reference arm 125 with an optical signal from a reference reflector 286. The OCT imaging engine 100B using a DSP 162 can calculate an interference pattern and use the pattern to generate an interferogram or another type of image from the received signal.

[0081] The OCT imaging engine 100B is configured to adjust the position of the reference mirror 130. With reference to FIG. 2B, the OCT imaging engine 100B can adjust the reference mirror 130 to various positions on either side of the zero delay line. The various positions, for example positions P1, P2, and P3, can move the image of the mirror to pixels at various depths, for example ranging from −1024 pixels to +1024 pixels relative to the zero delay line. In some examples, the pixel depth for the various positions can depend on the total number of pixels used before the fast Fourier transform (FFT) is performed and / or the zero padded data length before the FFT (i.e., the total number of pixels used before the FFT is performed, or the zero padded data length before the FFT, or both) according to the total samples of k clocks or the internal sampling rate of the A / D card. An example imaging depth of pixel depth 0 to pixel depth 1024 can be determined according to the following: (center wavelength) 2 / (2*laser bandwidth)

[0082] The pixel depth can depend on the total samples of k clocks or according to the internal sampling rate of the A / D card, half the total number of pixels used before the FFT, and the zero-padded data length before the FFT.

[0083] The OCT imaging engine modifies the interference pattern generated from the light returning from the reference reflector 286 by adjusting the position of the reference mirror 130. As described herein, the position of the reference mirror 130 can be used to generate information related to the performance of the OCT imaging engine 100B. For example, information generated from the interference pattern of light reflected by the reference mirror 130 while in one or more of the various positions described herein can be used by the OCT imaging engine 100B to calculate a spectral wavelength linearization and a spectral flattening spectrum. In some examples, the position of the reference mirror 130 can change the interference pattern generated from the light returning from the reference reflector 286.

[0084] FIG. 2C is a block diagram of the reference reflector 286 of FIG. 2A according to some examples. The reference reflector 286 can include an optical connector 205C that connects the reference reflector 286 to the switch 260. Alternatively, the reference reflector 286 can be fusion spliced ​​to the switch 260. The reference reflector 286 can include an attenuator 210C. The attenuator 210C can have a predetermined attenuation, for example, attenuating the reflected signal so that the magnitude of the reflection is similar to the reflection from the sample 140, for example, plus or minus 20 dB. The reference reflector 286 can include a flat surface 215C to provide a single point reflection. The length L of the optical fiber can have an optical path length similar to the sample 140, for example, 1.6 meters, so that the light reflected from 215C interferes with the reference arm. The single point reflection can be referred to as a point spread function (PSF), which can be processed by the DSP 160 or other components of the OCT imaging engine to obtain information that quantifies the OCT imaging engine.

[0085] According to some examples, the OCT imaging engine receives mirror measurements using a reference mirror and a calibration mirror. The mirror measurements can include a time-varying amplitude of an interferogram. The received measurements can be used by the system to derive the phase of the optical signal as a function of a sampling index.

[0086] FIG. 2D is a block diagram of an example OCT imaging engine 100B' configured to perform self-assessment and calibration and configured with a catheter connection check system 101A'.

[0087] The OCT imaging engine 100B' can use the positions of one or more of the reference mirror 130' and the reference reflector to generate information related to the performance of the optical system for use in the methods described herein. In some examples, the information generated from positions P1 and P2 can be used to calculate a spectral wavelength linearization and a spectral flattening spectrum, as further described with reference to Figures 3-4B. Additionally, the OCT imaging engine 100B' can use the catheter connection check system 101A' to check the connection of the catheter 190 to the catheter interface 170 in the manner described herein for the OCT imaging engine 100A' shown in Figure 1E.

[0088] FIG. 3 is a flow diagram of an example process 300 for self-assessment by an OCT imaging engine, according to an embodiment of the present disclosure.

[0089] 2A can receive an input indicating that switch 260 is set to a second position to receive the PSF from reference reflector 286. DSP 162 can use the PSF to measure, for example, the full-width half maximum (FWHM), current or average noise level, signal-to-noise ratio (SNR), and / or dynamic range of the OCT imaging engine (i.e., the full-width half maximum, current or average noise level, signal-to-noise ratio, and / or dynamic range, or two or more thereof).

[0090] The DSP 162 can compare the acquired data to known thresholds that the DSP 162 can use to determine whether the OCT imaging engine is operating within acceptable parameters. For example, the DSP 162 can determine whether the SNF of the OCT imaging engine exceeds a predetermined SNF threshold. As a result of the determination, the DSP 162 can perform a variety of actions, such as any of those described above with reference to FIG. 1B, to send an indication that the OCT imaging engine may potentially not be operating correctly or efficiently.

[0091] Referring to FIG. 3, in accordance with block 310, the DSP receives an optical signal reflected by a reference reflector internal to the OCT imaging engine.

[0092] The DSP calculates system performance data using the received optical signals, according to block 320. The system performance data may include one or more of a point spread function, a noise level, a signal to noise ratio, and a dynamic range.

[0093] According to block 330, the DSP compares the system performance data to one or more predefined thresholds or previous system performance data. The predefined thresholds can correspond to ideal system performance data that the imaging engine should generate under different settings. For example, for a particular calibration intensity, the DSP can compare the calculated system performance data to the predefined thresholds to determine whether the OCT imaging engine is operating within parameters. The DSP can also monitor trends in the performance data. For example, if the SNR is still above the threshold but is consistently degrading over time, e.g., above a predefined rate, the DSP can output a prompt to the user to perform maintenance or repairs before the system fails.

[0094] In accordance with block 340, the DSP outputs a result corresponding to the comparison. For example, as described herein with reference to FIG. 1B, the DSP may send a prompt or information indicating whether the system performance data meets a predetermined threshold. The DSP may output a prompt for maintenance or replacement of certain components of the OCT imaging engine, or may output a prompt for further investigation of a potential cause of failure or degradation, for example.

[0095] In some examples, the DSP may compare the system performance data to previously generated system performance data. For example, at least some of the times the DSP generates system performance data, for example according to aspects of the present disclosure, the DSP may store the data and subsequently retrieve the data and compare it to the currently generated system performance data. Based on the comparison, the DSP may send a prompt or information indicating whether the difference between the previously generated system performance data and the currently generated system performance data changes beyond a predetermined threshold. If there is a significant change, for example, a change of more than 5 percent, according to block 340, the DSP may output a result corresponding to the comparison. As part of the comparison, in some examples, the DSP may compare the currently generated system performance data to previously generated system performance data collected in the most recent time, and in other examples, the DSP may compare the currently generated system performance data to an average metric calculated, for example, from a set of previously generated system performance data over a period of time. The DSP may also monitor the performance data to identify trends and identify system degradation prior to failure to prompt a user to perform preventative maintenance.

[0096] [Self-calibration] In part, the disclosure relates to a calibration process that can calculate k-linearized (KL), variance, and spectral flattening spectra. The calibration process can provide a set of calibration spectra. OCT signals, including raw fringe data, using a mirror in the sample arm can be collected separately from the front and negative faces by adjusting the path distance of the reference arm.

[0097] Calibration spectra can be generated in a calibration stage using a first mirror measurement and a second mirror measurement, the first mirror measurement and the second mirror measurement being taken when the reference mirror is on opposite sides of a zero-delay line, each mirror measurement being an interferogram or a signal or a system impulse response. While the examples use two mirror measurements, other examples can use more mirror measurements. For example, the calibration can be based on three, four, tens, hundreds, or any number of mirror measurements.

[0098] In part, this disclosure relates to utilizing a received calibration spectrum to correct or correct the interferogram prior to performing an FFT. The calibration spectrum can be used to linearize future fringe data collected by the system in the wavenumber domain to improve the interferogram. In some examples, the wavenumber sampling can be linearized by interpolation using the calibration spectrum (k-linearization). Variance can be corrected by applying a Hilbert transform and multiplying with the variance spectrum of the k-linearized interferogram.

[0099] In part, aspects of the present disclosure provide systems and methods that separately correct for the nonlinearity of the k spectrum as well as the dispersion and asymmetric laser sweep intensity by using a spectrum calibrated by a signal processing step. The present disclosure allows an optimized optical resolution to be maintained throughout the imaging depth. Furthermore, the algorithms, methods, and systems described in this disclosure can also operate with or without a k-clock, providing the option to improve the system SNR by using the internal sampling rate of the digitizer. This sampling rate is typically faster than the maximum frequency of the k-clock.

[0100] The system can use the optical signal reflected from the reference reflector 286 in conjunction with interference patterns determined when the optical signal is reflected from the reference mirror at different positions to perform self-calibration of the methods described herein.

[0101] The system can use the optical signal reflected from the optical connector 188 in conjunction with interference patterns determined when the optical signal is reflected from a reference mirror at different positions to perform self-calibration of the methods described herein.

[0102] The self-calibration process 400A described herein can be performed, for example, each time an imaging system that contains an imaging engine described herein is powered on or before starting an imaging procedure. In another example, the OCT imaging engine performs the process 400A upon detecting a new or replaced component, such as a new optical connector or joint in the OCT imaging engine. Although the positions -P1 and P1 are shown on opposite sides of the zero delay line, they may or may not be equidistant from the zero delay line. In some examples, the positions -P1 and P1 may be equidistant or substantially equidistant to the zero delay line and may be in opposite directions to the zero delay line.

[0103] Although positions -P1 and P1 to P3 are shown as examples, the reference mirror 130 in various examples can be adjusted to different positions relative to the zero delay line, including the zero delay line itself. There can be any ordered finite number of positions. For example, there can be an additional position P4 that is at a greater positive pixel depth than position P3. In the example, the pixel depth can range from +1024 pixels to -1024 pixels.

[0104] Aspects of the present disclosure provide for performing a calibration process on the OCT imaging engine to measure the PSF of the OCT imaging engine at several positions. The reference reflector 286 can be adjusted, for example, using a motor, to reflect the optical signal at different positions and angles. Through calibration, the OCT imaging engine can maintain performance quality during imaging while calibrating itself as needed without user input. Through the calibration described herein, the OCT imaging engine can also self-correct issues related to stress-induced dispersion.

[0105] The calibration spectrum can be used to linearize future fringe data by the system. The wavenumber sampling can be linearized by interpolation using the calibration spectrum (k-linearization) and the variance is corrected by the Hilbert transform (DC). The spectral envelope of the laser source is flattened and the digitized laser bandwidth is optimized to suppress sidelobe artifacts arising from non-uniform laser intensity during the spectral sweep. The corrected spectrum is then processed downstream. By correcting the spectrum, the axial resolution can be improved and preserved throughout the depth of the A-scan. No external k-clock is required.

[0106] In part, this disclosure relates to utilizing an acquired calibration spectrum to correct or correct an interferogram prior to Fast Fourier Transform (FFT) processing. The calibration spectrum can be used to linearize future fringe data collected by the system in the wavenumber domain to improve the interferogram. In some examples, the wavenumber sampling can be linearized by interpolation using the calibration spectrum (k-linearization). Variance can be corrected by applying a Hilbert transform and multiplying with the variance spectrum of the k-linearized interferogram.

[0107] In some examples, the OCT imaging engine can use the reference reflector 286 as part of self-calibration without user input. Aspects of the present disclosure provide for performing a calibration process on the OCT imaging engine to measure the PSF of the engine at several positions. The reference reflector 286 can be adjusted, for example, using a motor, to reflect the optical signal at different positions and angles. Alternatively, the position of the reference mirror 130 can be adjusted to measure the PSF at several positions. Through calibration, the OCT imaging engine can maintain performance quality during imaging while calibrating itself as needed without user input. Through the calibration described herein, the OCT imaging engine can also self-correct issues related to stress-induced dispersion.

[0108] FIG. 4A is a flow chart of an example process 400A for self-calibration using a reference mirror and a reference reflector internal to an OCT imaging engine.

[0109] According to block 410A, the OCT imaging engine receives mirror measurements using a reference mirror and a reference reflector. The reference reflector can be an internal reflector as shown in FIG. 2C or some other reflection point in the sample arm 135 of the OCT imaging engine, for example, the connection point 192 at the end of the optical connector in the catheter interface 170. The mirror measurements can include the time-varying amplitude of the interferogram. The system can use the received measurements to derive the phase of the optical signal as a function of the sampling index n. The optical phase of the received signal can be, for example, Φ P1 (n) and Φ -P1 (n), where Φ x (n) corresponds to the optical phase at position x of the reference mirror 130 (e.g., measured at pixel depth relative to a zero delay line). The input parameter n is the sampling index of the OCT imaging engine.

[0110] As part of receiving the mirror measurements, the OCT imaging engine can receive optical signals from the reference reflector and the reference mirror for each different position of the reference mirror. The received optical signals can be referred to as raw fringe data (or "raw fringes"). The OCT imaging engine can receive a plurality of optical signals, for example, an optical signal when the reference mirror is at position P1 and another signal when the reference mirror is at position -P1, as shown and described with reference to FIG. 2B. The P1 and -P1 positions can be any of a variety of pixel depths relative to the zero delay line of the reference mirror 130. For example, the pixel depth can be 250 pixels to 300 pixels relative to the zero delay line, which corresponds to 25% to 30% of the Nyquist depth for a 1024 pixel system. In other examples, any two arbitrary positions can be selected relative to the zero delay line. The OCT imaging engine can receive the mirror measurements for a plurality of pairs of positions of the reference mirror relative to the zero delay line. For example, one location pair may be (P1,-P1) as described herein, but measurement data for multiple location pairs may be received in accordance with block 410A.

[0111] The optical signal can include raw fringe data, which can be received when the optical signal is reflected from a reference mirror or reflector when the reference mirror is at different positions relative to the zero delay line. A high pass filter can filter out low frequency components of the interference signal.

[0112] As part of receiving the mirror measurements, the OCT imaging engine can generate an interferogram from the received optical signals. For each received optical signal, the OCT imaging engine generates a respective interferogram. The interferograms can be referred to as raw fringe data and can be sampled by the OCT imaging engine using a k-clock.

[0113] The engine applies a Hilbert transform from the generated interferogram to obtain the complex signal and phase of the received measurements, e.g., Φ P1 (n) and Φ -P1 (n). The engine calculates the k-linear phase by averaging the fringes of the optical signal in each measurement, and the optical phase Φ P1 (n) and Φ P2 (n) can be obtained.

[0114] For example, the optical phase Φ of the received signal at position P1 P1 Calculating (n), it is observed that the strength of the signal at position P1 is proportional to a function of the wavenumber of the optical signal, the position of the reference mirror 130 when the signal is received, and the optical dispersion phase of the received optical signal when the reference mirror 130 is at position P1. An example formulation can be as follows: I P1 (n) ∝ cos(k(n)Z P1 +Φ disp (n)) (A) I P1 (n) ∝ cos(k(n)Z P2 -Φ disp (n)) (B)

[0115] Here, I P1 (n) corresponds to the intensity of the optical signal received at the sampling index n and the position P1 of the reference mirror, and ∝ corresponds to the left operand (e.g., I P1 (n)) is the right operand (e.g. cos(k(n)Z P1 +Φ disp (n)), where cos(·) is the cosine function, k(n) is the wavenumber of the received optical signal, and Z ±P1 is the mirror distance from the zero delay line.

[0116] Using equations (A) and (B), the OCT imaging engine can perform a Hilbert transform on the received signal to receive the optical phase of the signal at different positions of the reference mirror 130. For example, using the Hilbert transform, the OCT imaging engine can calculate Φ P1 (n)=k(n)Z P1 +Φ disp (n) and Φ P2 (n)=k(n)Z P2 -Φ disp (n) may be received. The OCT imaging engine may also remove background from the received signal.

[0117] In accordance with block 420A, the OCT imaging engine generates a dispersion-free k-spectrum (k-spectrum) Φ KL (n)=0.5*{Φ P1 (n)+Φ -P1 (n)}. After interpolating the optical fringes by using the KL spectrum, the OCT imaging engine can calculate the dispersion spectrum. One exemplary formulation of this relationship for measurement data collected from one reference mirror position pair (P1, -P1) is as follows:

number

[0118] For each calibration pair of mirrors, the term X d is used to compensate for the phase difference of the mirror signals from P1 and -P1 due to their unequal positions relative to the zero delay line. p refers to the distance from the zero delay line.

[0119] In accordance with block 430A, the OCT imaging engine generates a k-spectrum Φ KLA polynomial fitting to (n) can be calculated. In some examples, to calculate the polynomial, the OCT imaging engine can perform KL resampling with various polynomial fitting orders using optical signals acquired while the reference mirror is in different positions, such as P2 or P3. In some examples, the polynomial order can vary from zero to 50, with zero representing the raw k spectrum with no fitting.

[0120] The polynomial may be determined based on two or more mirror measurements. A dispersion spectrum or criterion may be calculated for at least one mirror measurement, and compensation may be calculated. A dispersion compensation, dispersion coefficient, or dispersion criterion may be calculated using two mirror positions, one position on either side of a zero delay line. A spectral flattening may be performed for at least one mirror measurement by using an envelope calculated from a particular mirror measurement. The spectral envelope calculated during the spectral flattening may be saved. Each mirror measurement of the multiple mirror measurements may be a system impulse response.

[0121] In some examples, the OCT imaging engine generates additional interferograms from the optical signals received from the reference reflector and the reference mirror while the reference mirror is at positions P1-P3. The OCT imaging engine can use the additional interferograms to better fit with a polynomial, and the OCT imaging engine can be used to optimize the k spectrum based on the optimal polynomial fitting order found from the algorithm. In some examples, the locations of P1, P2, and P3 can be selected based on a desired or estimated depth of the sample to optimize the polynomial fitting over a depth range.

[0122] As part of calculating the polynomial, the OCT imaging engine may perform one or more iterations of fitting candidate polynomials of particular orders as described herein to identify the candidate polynomial order that causes the sharpest intensity peak. The polynomial with the identified candidate order may be stored in memory and used during the real-time imaging phase as described herein in accordance with FIG. 4B. The OCT imaging engine may continue searching for an improved polynomial that fits the k spectrum until one or more convergence criteria, e.g., number of iterations or time elapsed since the search began, are met.

[0123] In some examples, the OCT imaging engine can calculate the full width at half maximum (FWHM) and the sum of the area of ​​the point spread function (PSF) based on the PSF profile after the system performs k-spectral interpolation by each fitting order. The sum of the FWHM and the area of ​​the PSF can be calculated for each depth position P1-P3 for each polynomial order. The system can then average and normalize the sum of the FWHM and the area of ​​the PSF for each position.

[0124] Using the sum of the areas of the averaged FWHM and PSF from multiple, e.g., three, different depths, the system can search for the polynomial order to be applied to the KL spectrum that has the smallest FWHM and PSF across depth.

[0125] According to block 440A, the OCT imaging engine calculates the dispersion spectrum. The OCT imaging engine uses the k spectrum and the polynomial calculated according to blocks 410A-430A to interpolate the raw fringe data. The dispersion phase Φ disp (n) can be calculated according to formula C described herein. The OCT imaging engine can remove noise appearing in the dispersion spectrum by fitting the spectrum with a polynomial function or by applying a low pass filter. The dispersion phase function Φ disp(k) can be stored and used as the anti-dispersion phase to subtract from the analytical form of the KL-corrected fringe.

[0126] According to block 450A, the OCT imaging engine calculates a spectrally flattened spectrum. The OCT imaging engine can calculate the spectrally flattened spectrum using the fringe data corrected using the k spectrum and the dispersion spectrum calculated according to blocks 420A-440A. In some examples, the spectral flattening can further increase the axial resolution of the output image by increasing the available bandwidth. For example, the OCT imaging engine can calculate a spectrally flattened window as a calibration step and apply the window to future data using a window function, e.g., a Kaiser-Bessel window. Using the window function, the OCT imaging engine can calculate a demodulation window, e.g.,

number

[0127] In accordance with block 460A, the OCT imaging engine stores one or more of the k spectrum, the polynomial calculated to fit the k spectrum, the dispersion spectrum, and the spectrally flattened spectrum. Collectively, the stored spectra are referred to as calibration spectra.

[0128] FIG. 4B is a flow diagram for a self-calibration process 400B performed by an OCT imaging engine according to an embodiment of the disclosure.

[0129] In accordance with block 410B, the OCT imaging engine receives one or more calibration spectra, For example, the calibration spectra may be pre-computed and stored by the OCT imaging engine, as described herein with reference to FIG.

[0130] According to block 420B, the OCT imaging engine receives the optical signal and performs k-linearization correction while receiving the optical signal. To perform the k-linearization correction, the OCT imaging engine can interpolate the input optical signal using the stored k-spectrum and polynomial fitting order.

[0131] In some examples, the OCT imaging engine can perform cubic spline interpolation in wavenumber space (k-space) on the received optical data, which can scale the raw fringe data from the nonlinear domain to the linear wavenumber domain before performing the FFT process.

[0132] Spline interpolation is a form of piecewise polynomial interpolation to avoid overfitting, which can cause spike errors. In some examples, accelerators, such as field programmable gate arrays (FPGAs), graphics processing units (GPUs), or application specific integrated circuits (ASICs), can be used to accelerate the cubic spline interpolation in the wavenumber domain and perform the correction in real time, while the OCT imaging engine is running.

[0133] According to block 430B, the OCT imaging engine performs dispersion correction on the fringe data. The OCT imaging engine applies the stored dispersion spectrum, for example, generated according to block 440A of process 400A of FIG. 4A. The OCT imaging engine performs dispersion compensation to cancel the dispersion phase and correct the optical signal it is receiving. In an example of applying a polynomial fitting function or a low pass filter to the optical signal, a more robust correction can be performed compared to the dispersion correction on the uncorrected fringe data.

[0134] For example, the OCT imaging engine can apply a Hilbert transform to the raw fringe data to convert the data into an analytical form. The OCT imaging engine can compensate for the dispersion phase by using an exponential function of the dispersion spectrum. An exemplary formulation of the exponential function is =jΦ disp (n), where j is the imaginary unit.

[0135] The OCT imaging engine can calculate the new fringe function by taking the real part of the corrected fringe data and multiplying it by the complex-valued phase. An exemplary formulation of the fringe function can be as follows: s1(n)=Real{s0(n)×exp[-jΦ disp (n)]Analysis form} (D)

[0136] where s1(n) is the new fringe function and s0(n) is the k-spectral corrected optical signal. The real functions referred to in equation (D) take the real-valued portion of the k-linearized fringe data that has been converted to a complex-valued analytical form.

[0137] According to block 440B, the OCT imaging engine applies spectral flattening to the k-linearized and dispersion corrected signal. The spectral flattening can be performed for at least one mirror measurement by using an envelope calculated from a particular mirror measurement. Each mirror measurement of the plurality of mirror measurements can be a system impulse response. Dispersion compensation can be calculated for at least one mirror measurement. A dispersion spectrum or criterion can be calculated for at least one mirror measurement, and compensation can be calculated. The dispersion compensation, dispersion coefficient, or dispersion criterion can be calculated using two mirror positions that are symmetric across a zero delay line. The spectral envelope calculated during the spectral flattening can be saved.

[0138] In some examples, spectral flattening can further increase axial resolution performance by increasing the available bandwidth. In one example, a spectral flattening window can be calculated as a calibration step and applied to future data using a window function (e.g., a Kaiser-Bessel window) to form the demodulation window. The envelope used can be derived from a signal acquired from any of the reference mirror positions from block 305.

[0139] In one example, the first step of the spectral flattening process is to calculate the fringe envelope by taking the absolute value of the KLDC corrected fringes after the Hilbert transform has been applied. This step can be done when the mirror is placed in the sample arm. When calculating the spectral envelope, the spectral envelope can be fitted by a polynomial function.

[0140] Processes 400A and 440B can be repeated multiple times before, during, or after operation of one of the OCT imaging engines 100A-100F. For example, the OCT imaging engine 100 can perform process 300 to obtain quantification information from the PSF received from the reference reflector when the OCT imaging engine is first powered on. Additionally or alternatively, the OCT imaging engine can perform process 400A periodically or in response to a user input requesting self-assessment and calibration. The input can be, for example, received by the OCT imaging engine to change the position of a switch, which causes the OCT imaging engine to operate in a catheter connection check mode and measure the return loss for back reflection of the optical signal.

[0141] 5A is a block diagram of an example OCT imaging engine 100C for performing both catheter connection checks and self-assessment and calibration, according to an embodiment of the present disclosure. The OCT imaging engine 100C can be configured to operate in either a catheter connection check mode or a self-assessment and calibration mode. The OCT imaging engine 100C can include a combined catheter connection check and self-assessment / calibration engine 101C.

[0142] The OCT imaging engine 100C can include a 1x3 optical switch 510, a 2x1 optical switch 520, a fiber optic cable 530, and a reference reflector 540. The optical switches 510, 520 and the fiber optic cable 530 can be in the sample arm 135 of the OCT imaging engine 100C. The 2x1 optical switch 520 and the fiber optic cable 530 can be implemented, for example, as described with reference to the optical switch 160 and the fiber optic cable 184 of FIG. 1A. Instead of connecting directly to the beam splitter 120, the 2x1 optical switch 520 connects to the 1x3 optical switch 510.

[0143] When the switches 510, 520 are in a first position, the switches 510, 520 allow the optical signal to enter or exit the beam splitter 129 and the catheter interface 170. When the switches 510, 520 are in a first position, the OCT imaging engine 100C can be said to operate to measure the optical signal and to use the measured optical signal to generate a corresponding tomogram or other image.

[0144] When the switches 510, 520 are in the second position, the switches 510, 520 cause the optical signal to pass through the fiber optic cable 530. As described herein with reference to the DSP 162 of Figure 1A, the DSP 162 of Figure 1A can be configured to receive a return loss of a back reflection of the optical signal through the optical connector connection point between the catheter interface 170 and the catheter 190. The DSP 162 can determine whether the connection is successful based on a comparison between the return loss and a predetermined threshold, as described with reference to Figures 1B and 1C.

[0145] When the switch 510 is in the third position, the switch 510 causes the optical signal to pass through the reference reflector 286. The DSP 162 may receive the PSF from the reference reflector 540, as described herein with reference to the DSP 162 and the reference reflector 540. The DSP 162 may process the PSF, as described herein with reference to FIG. 3, and may generate information that quantifies the performance of the OCT imaging engine 100C.

[0146] In some examples, the OCT imaging engine 100C may be connected to one or more storage devices configured to store information measured and generated by the OCT imaging engine 100C while operating in either the catheter connection check mode, the self-assessment and calibration mode, or both the catheter connection check mode and the self-assessment and calibration mode.

[0147] 5B is a block diagram of an example OCT imaging engine 100D configured for dual catheter lengths to perform both catheter connection checks and self-assessment and calibration. The OCT imaging engine 100D can include a combined catheter connection check and self-assessment / calibration engine 101D.

[0148] As shown in FIG. 5B, the OCT imaging engine 100D can include variable length fibers 530A and 530B. In one example, the lengths of the fibers 530A and 530B can be 1.6 meters and 3.2 meters, respectively, but in other examples, the lengths can be longer or shorter. With multiple fiber lengths available, the OCT imaging engine 100D can perform catheter checks on catheters of different lengths. To accommodate the different potential fiber lengths, the OCT imaging engine 100D can implement a 1×4 optical switch 580 and a 1×3 optical switch 590. The size of the optical switch can vary depending on the number of fibers available in the OCT imaging engine 101D.

[0149] FIG. 5C is a block diagram of an example OCT imaging engine 100E that uses a 1×2 switch and a 2×2 switch to perform both catheter connection checks and self-assessment and calibration, according to an embodiment of the disclosure. The OCT imaging engine 100E can include a combined catheter connection check and self-assessment / calibration engine 101E. As shown in FIG. 5C, the OCT imaging engine 100E can include a 1×2 optical switch 599E and a 2×2 optical switch 598E. As described herein with reference to FIGs. 5A-5D, the quantity and type of optical switches can vary from example to example.

[0150] 5D is a block diagram of an example OCT imaging engine 100F that uses two 1x2 optical switches 597E, 598E and one 2x1 optical switch 599E to perform both catheter connection checks and self-assessment and calibration, according to an embodiment of the present disclosure. The OCT imaging engine 100F can include a combined catheter connection check and self-assessment / calibration engine 101F. As shown in FIG. 5D, the OCT imaging engine 100F can include two 1x2 optical switches 597F, 598E connected through a 2x2 optical switch 599E.

[0151] 6 is a block diagram of an imaging environment 600 including one or more of the OCT imaging engines 100A-100F and a host computing device 601. The host computing device ("host device") 601 can include one or more processors configured to receive signals from various types of imaging devices and process the signals to generate one or more image frames or other visual data corresponding to the received signals.

[0152] The host device 601 may include a user input 670. The user input 670 may include any suitable mechanism or technology for receiving input from a user, such as a keyboard, a mouse, a mechanical actuator, a soft actuator, a touch screen, a microphone, and a sensor.

[0153] The host device 601 can be configured to receive images from an imaging device 605 having an imaging probe 604. The imaging probe 604 can be, by way of example, an OCT probe and / or an IVUS catheter (i.e., an OCT probe or an IVUS catheter or both). Using a guidewire (not shown), the probe 604 can be introduced into a blood vessel 602, such as the blood vessel of a target 607. The probe 604 can be introduced and pulled back along the length of the lumen of the blood vessel 602 while collecting data, for example as a series of image frames. According to some examples, the probe 604 can be held stationary during pullback so that multiple scans of a data set can be collected.

[0154] The probe 604 can be connected to a user computing device 601 through an optical fiber 606. The host device 601 can include a light source such as a laser, an interferometer with a sample arm and a reference arm, various optical paths, a clock generator, photodiodes, and other OCT components. In some examples, the host device 601 is connected to one or more other devices and / or instruments (not shown) (i.e., one or more other devices and / or instruments) configured to perform medical imaging using one of the OCT imaging engines 100A-100F. As an example, the host device 601 and one of the imaging engines 100A-100F can be part of a catheterization laboratory.

[0155] The probe 604 can be connected to a light receiver 665. According to some examples, the light receiver 665 can be a balanced photodiode-based system. The light receiver 665 can be configured to receive light collected by the probe 604.

[0156] The host device 601 can be communicatively coupled to one or more storage devices 690 or computing device(s) 619 via a network 695. The storage device(s) 699 or computing device(s) 619 can be a combination of volatile and non-volatile memory and can be in the same or a different physical location as the host device 601 and / or the OCT imaging engines 100A-100D (i.e., the host device 601 and / or the OCT imaging engines 100A-100D). For example, the storage device(s) 690 can include any type of non-transitory computer-readable medium capable of storing information, such as a hard drive, a solid state drive, a tape drive, an optical storage device, a memory card, a ROM, a RAM, a DVD, a CD-ROM, a writeable memory, and a read-only memory.

[0157] The host device 601 may include one or more processors 613 and memory 614. The memory 614 may store information accessible by the processor(s) 613, including instructions 615 executable by the processor(s) 613. The memory 614 may also include data 616 that may be retrieved, manipulated, or stored by the processor(s) 613. The memory 614 may be any type of non-transitory computer-readable medium that may store information accessible by the processor(s) 613, such as volatile and non-volatile memory. The processor(s) 613 may include one or more central processing units (CPUs), graphics processing units (GPUs), field programmable gate arrays (FPGAs), and / or application specific integrated circuits (ASICs).

[0158] Instructions 615 may include one or more instructions that, when executed by processor(s) 613, cause the one or more processors to perform an operation specified by the instructions. Instructions 615 may be stored in object code format for direct processing by processor(s) 613, or in other formats, such as a collection of interpretable scripts or independent source code engines that are interpreted on demand or pre-compiled.

[0159] Data 616 may be obtained, stored, or modified by processor(s) 613 according to instructions 615. Data 616 may be stored in a computer register, a relational or non-relational database, as a table with multiple different fields and records, or as a JSON, YAML, Proto, or XML document. Data 616 may also be formatted in a computer readable form, such as, but not limited to, binary values, ASCII, or Unicode. Additionally, data 616 may include sufficient information to identify related information, such as numbers, descriptive text, unique codes, pointers, references to data stored in other memory, including other network locations, or information used by a function to calculate the related data.

[0160] The host device 601 may be configured to display at least a portion of the received data on a display implemented as part of the user output 680. The user output 680 may also be used to interface the host device 601 on the display 618. The user output 680 may alternatively or additionally include one or more speakers, transducers or other audio outputs, a haptic interface or other haptic feedback that provides non-visual and non-acoustic information to a user of the host device 601.

[0161] 6 illustrates the processor(s) 613 and memory 614 as being within the host device 601, the components described herein, including the processor(s) 613 and memory 614, may include multiple processors and memories that may operate in different physical locations rather than within the same computing device. For example, some of the instructions 615 and data 616 may be stored on a removable SD card and others may be stored in a read-only computer chip. Some or all of the instructions and data may be stored in a location that is physically separate from the processor(s) 613 but still accessible by the processor(s) 613. Similarly, the processor(s) 613 may include a collection of processors that may perform concurrent and / or sequential operations (i.e., simultaneous and / or sequential operations). Each of the host devices 601 may include one or more internal clocks that provide timing information. The timing information may be used to time operations and programs executed by the host device 601. In some examples, the host device 601 is physically separate from the imaging equipment from which the image data or image frames are received. The host device 601 can be configured to receive time data, image frames, and / or other data (i.e., time data, image frames, and / or other data) via the network 695.

[0162] The host device 601 may be capable of direct and indirect communication with one or more other devices via the network 695. The host device 601 may set up a listening socket capable of accepting an initiating connection to send and receive information. The network 695 itself may comprise a variety of configurations and protocols, such as the Internet, the World Wide Web, an intranet, a virtual private network, a wide area network, a local network, and a private network using a communication protocol proprietary to one or more companies. The network 695 may support a variety of short-range and long-range connections. The short-range and long-range connections may be made over different bandwidths, such as 2.402 GHz to 2.480 GHz (typically associated with the Bluetooth® standard), 2.4 GHz and 5 GHz (typically associated with the Wi-Fi® communication protocol), or using a variety of communication standards, such as the LTE® standard for wireless broadband communication. Network 695 may additionally or alternatively support wired connections (including via various types of Ethernet connections) between host device 601, OCT imaging engines 100A-100F, and / or other computing devices (i.e., host device 601, OCT imaging engines 100A-100F, and / or other computing devices).

[0163] Although a single host device 601 and OCT imaging engines 100A-100F are shown in FIG. 6B, it is understood that aspects of the disclosure can be implemented according to a variety of different configurations and quantities of devices, including paradigms for serial or parallel processing, or via a distributed network of multiple devices. In some implementations, aspects of the disclosure can be performed on a single device, and any combination thereof.

[0164] Computer program logic implementing all or part of the functionality described herein above may be embodied in a variety of forms, including but in no way limited to source code form, computer executable form, and various intermediate forms (e.g., forms generated by an assembler, compiler, linker, or locator). Source code may include a series of computer program instructions implemented in any of a variety of programming languages ​​(e.g., object code, assembly language, or high-level languages ​​such as Fortran, C, C++, JAVA, or HTML) for use with a variety of operating systems or operating environments. Source code may define and use various data structures and communication messages. Source code may be in a computer executable form (e.g., via an interpreter) or source code may be converted into a computer executable form (e.g., via a translator, assembler, or compiler).

[0165] The computer program may be fixed in any form (e.g., source code form, computer executable form, or intermediate form) permanently or temporarily on a tangible storage medium such as a semiconductor memory device (e.g., RAM, ROM, PROM, EEPROM, or flash programmable RAM), a magnetic memory device (e.g., diskette or fixed disk), an optical memory device (e.g., CD-ROM), a PC card (e.g., PCMCIA card), or other memory device. The computer program may be fixed in any form on a signal that is transmittable to a computer using any of a variety of communication technologies, including, but in no way limited to, analog, digital, optical, wireless (e.g., Bluetooth), networking, and internetworking technologies. The computer program may be distributed in any form on a removable storage medium (e.g., shrink-wrapped software) with accompanying printed or electronic documentation, may be preloaded on a computer system (e.g., system ROM or fixed disk), or may be distributed from a server or electronic bulletin board over a communication system (e.g., the Internet or World Wide Web).

[0166] Hardware logic (including programmable logic used in conjunction with a programmable logic device) implementing all or a portion of the functionality described herein above may be designed using conventional manual methods, or may be electronically designed, captured, simulated, or documented using a variety of tools, such as computer-aided design (CAD), hardware description languages ​​(e.g., VHDL or AHDL), or PLD programming languages ​​(e.g., PALASM, ABEL, or CUPL).

[0167] The programmable logic may be fixed, either permanently or temporarily, in a tangible storage medium, such as a semiconductor memory device (e.g., RAM, ROM, PROM, EEPROM, or flash programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM), or other memory device. The programmable logic may be fixed in signals transmittable to a computer using any of a variety of communication technologies, including, but in no way limited to, analog, digital, optical, wireless (e.g., Bluetooth), networking, and internetworking technologies. The programmable logic may be distributed as a removable storage medium (e.g., off-the-shelf software) with accompanying printed or electronic documentation (e.g., shrink-wrap software), may be preloaded into a computer system (e.g., a system ROM or fixed disk), or may be distributed over a communication system (e.g., the Internet or World Wide Web) from a server or electronic bulletin board.

[0168] Various examples of suitable processing engines are described in more detail below. As used herein, an engine or system may refer to software, hardware, and / or firmware (i.e., software, hardware, or firmware, or two or more thereof) suitable for performing a particular data processing or data transmission task. In some examples, an engine or system may refer to instructions, or software routines, programs, or other memory resident applications suitable for receiving, converting, routing, and processing various types of data (e.g., OCT scan data and other information of interest).

[0169] The phrase "configured to" is used herein in various contexts relating to a computer system, hardware, or part of a computer program, engine, or module. When a system is said to be configured to perform one or more operations, this means that the system has appropriate software, firmware, and / or hardware installed that causes the system to perform one or more operations during operation. When a piece of hardware is said to be configured to perform one or more operations, this means that the hardware comprises one or more circuits that, during operation, receive inputs and generate outputs corresponding to the one or more operations according to the inputs. When a computer program, engine, or module is said to be configured to perform one or more operations, this means that the computer program includes one or more program instructions that, when executed by one or more computers, cause the one or more computers to perform one or more operations.

[0170] The computers and computer systems described herein may include operatively associated computer-readable media, such as memory for storing software applications used in acquiring, processing, storing, and / or communicating (i.e., storing and / or communicating) data. It may be appreciated that such memory may be internal, external, remote, or local with respect to the computer or computer system to which it is operatively associated.

[0171] Generally, computer-readable memory media applied in connection with the embodiments of the present disclosure described herein may include any memory medium capable of storing instructions executed by a programmable device. Where applicable, the method steps described herein may be embodied or executed as instructions stored on one or more computer-readable memory media. These instructions may be software embodied in various programming languages ​​such as C++, C, Java, etc., and / or various other types of software programming languages ​​that may be applied to create instructions according to the embodiments of the present disclosure (i.e., various programming languages ​​such as C++, C, Java, etc., and / or various other types of software programming languages ​​that may be applied to create instructions according to the embodiments of the present disclosure).

[0172] A storage medium can be non-transitory or can include a non-transitory device. Thus, a non-transitory storage medium or a non-transitory device can include a device that is tangible, meaning that the device has a concrete physical form, although it may change its physical state. Thus, for example, non-transitory refers to the device remaining tangible even with this change in state.

[0173] The aspects, embodiments, features, and examples of the present disclosure are considered in all respects to be illustrative and are not intended to be limiting of the disclosure, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the disclosure as claimed.

[0174] The use of headings and paragraphs in this application is not meant to limit the disclosure; each paragraph may apply to any aspect, embodiment, or feature of the disclosure.

[0175] Throughout this application, when a composition is described as having, including, or comprising particular components, or a process is described as having or including particular process steps, it is intended that the composition of the present teachings consists essentially of or consists of the recited components, and that the process of the present teachings consists essentially of or consists of the recited process steps.

[0176] When an element or component is referred to in this application as being included and / or selected from a list of enumerated elements or components (i.e., included in and / or selected from a list of enumerated elements or components), it is to be understood that the element or component can be any one of the enumerated elements or components, or can be selected from a group consisting of two or more of the enumerated elements or components. Furthermore, it is to be understood that the elements and / or features (i.e., elements and / or features) of the compositions, devices, or methods described herein can be combined in various ways, whether expressly or implicitly stated herein, without departing from the spirit and scope of the present teachings.

[0177] Use of the terms "include," "includes," "including," "have," "has," or "having" should generally be understood to be open-ended and non-limiting, unless otherwise specified.

[0178] The use of the singular herein includes the plural (and vice versa) unless otherwise specified. Additionally, the singular forms "a," "an," and "the" include the plural unless the context clearly dictates otherwise. Additionally, when the term "about" or "substantially" is used before a quantitative value, the present teachings also include the specific quantitative value itself unless otherwise specified. The term "about" or "substantially" as used herein refers to variations in quantity that may occur, for example, through real-world measuring or handling procedures, through accidental errors in these procedures, through differences / faults in the manufacture of materials such as composite tapes, through defects, as well as variations that would be recognized as equivalents by those skilled in the art, unless such variations encompass known values ​​implemented by the prior art. Typically, the term "about" or "substantially" means greater or smaller than the stated value or range of values ​​by 1 / 10, e.g., ±10%, of the stated value.

[0179] It should be understood that the order of steps or order for performing certain actions is immaterial so long as the present teachings remain operable. Moreover, two or more steps or actions may be conducted simultaneously.

[0180] It is understood that the figures and descriptions of the present disclosure have been simplified to show elements that are relevant for a clear understanding of the present disclosure, while omitting other elements for clarity. Those skilled in the art will recognize, however, that these and other elements may be desirable. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present disclosure, descriptions of such elements are not provided herein. It should be understood that the figures are presented for illustrative purposes, and not as structural diagrams. The omitted details and modifications or alternative implementations are within the knowledge of those skilled in the art.

[0181] It can be recognized that in certain aspects of the present disclosure, multiple components can be substituted for single components, and multiple components can be substituted for single components, to provide an element or structure or to perform a given function or functions. Except to the extent that such substitutions are not usable to practice a particular embodiment of the present disclosure, such substitutions are deemed to be within the scope of the present disclosure.

[0182] The examples presented herein are intended to illustrate possible and specific embodiments of the present disclosure. It can be appreciated that the examples are intended primarily to illustrate the present disclosure for those skilled in the art. There may be variations to these diagrams or the operations described herein without departing from the spirit of the present disclosure. For example, in certain cases, method steps or operations may be performed or executed in a different order, or operations may be added, deleted, or modified.

[0183] While the present disclosure relates to various aspects and embodiments and other features described and illustrated herein, it is understood that each of the foregoing disclosed herein may be integrated together in whole or in part, as appropriate. Thus, each embodiment disclosed herein may be incorporated into each aspect to varying degrees, depending on the given embodiment. Furthermore, the various methods and techniques described herein may be used with a variety of imaging modalities.

Claims

1. a light source adapted to be coupled to a first optical connector; a catheter adapted to be coupled to a second optical connector, the catheter adapted to be coupled to the light source using the first optical connector and the second optical connector; an interferometer comprising a plurality of optical switches, at least two of the plurality of optical switches connected to one another by a length of optical fiber, wherein when in a first position, the plurality of optical switches form a first optical path for optical signals to and from the light source and the catheter, and when in a second position, the plurality of optical switches form a second optical path for optical signals to and from the light source along the length of optical fiber; one or more processors configured to perform operations including receiving back reflections of an optical signal at a connection point between the first optical connector and the second optical connector, and determining, based on the back reflections, whether the catheter is fully connected or not fully connected to the light source; An imaging system comprising:

2. In determining whether the catheter is fully connected or not fully connected to the light source based on the back reflections, the one or more processors: calculating the return loss of the back reflection; determining whether the catheter is fully connected or not fully connected to the light source based on a comparison between the calculated return loss and a predetermined return loss threshold; The system of claim 1 , further configured to perform operations including:

3. The one or more processors, in response to determining that the catheter is not fully connected, outputting a prompt or signal indicating a potential problem with the catheter; outputting data characterizing the quality of the physical connection between the catheter and the light source; The system of claim 2 , further configured to perform actions including performing one or more of:

4. The one or more processors, in response to determining that the catheter is fully connected, outputting a prompt or signal indicating that the catheter is fully connected; outputting data characterizing the quality of the physical connection between the catheter and the light source; The system of claim 2 , further configured to perform actions including performing one or more of:

5. the interferometer comprising a reference reflector coupled to a third optical switch of the plurality of optical switches; The one or more processors: receiving an optical signal reflected by the reference reflector; calculating system performance data including one or more of a point spread function, a noise level, a signal-to-noise ratio, and a dynamic range; The system of claim 1 , further configured to perform operations including:

6. The one or more processors: comparing the system performance data to one or more predetermined thresholds; outputting a result corresponding to said comparison; The system of claim 5 , further configured to perform operations including:

7. The one or more processors: comparing the system performance data with system performance data generated at an earlier time; outputting a result corresponding to said comparison; The system of claim 5 , further configured to perform operations including:

8. The one or more processors: determining that the system is powered on; calculating the system performance data in response to receiving the optical signal and determining that the system is powered on; The system of claim 5 configured to:

9. the interferometer comprising a reference reflector coupled to a third optical switch of the plurality of optical switches; The one or more processors: receiving one or more mirror measurements using the reference reflector and the reference mirror; using the one or more mirror measurements to perform one or more of: calculating a dispersion-free k spectrum; calculating a polynomial fit to the dispersion-free k spectrum; calculating a dispersion spectrum; and calculating a spectrally flattened spectrum; storing one or more of the calculated spectrum and the polynomial fit in memory as a calibration spectrum; The system of claim 1 , further configured to perform operations including:

10. The system of claim 9 , wherein the one or more mirror measurements include a plurality of mirror measurements taken from the reference reflector located on either side of a zero delay line.

11. The one or more processors: loading the calibration spectrum; performing one or more of k-linearization, dispersion correction, and spectral flattening using the loaded calibration spectrum; The system of claim 9 , further configured to perform operations including:

12. The one or more processors: receiving the back reflection of the optical signal at the connection point when the catheter is not connected to the light source; determining whether the connection point is degraded based on a return loss for the back reflection of the optical signal at the connection point when the catheter is not connected to the light source; The system of claim 1 , further configured to perform operations including:

13. a light source adapted to be coupled to a first optical connector; a catheter adapted to be coupled to a second optical connector, the catheter adapted to be coupled to the light source using the first optical connector and the second optical connector; an interferometer comprising one or more optical switches and a reference reflector coupled to a first optical switch of the one or more optical switches; receiving an optical signal reflected by the reference reflector; one or more processors configured to perform operations including calculating system performance data including one or more of a point spread function, a noise level, a signal-to-noise ratio, and a dynamic range; An imaging system comprising:

14. The one or more processors: receiving one or more mirror measurements using the reference reflector and the reference mirror; using the one or more mirror measurements to perform one or more of: calculating a dispersion-free k spectrum; calculating a polynomial fit to the dispersion-free k spectrum; calculating a dispersion spectrum; and calculating a spectrally flattened spectrum; storing one or more of the calculated spectrum and the polynomial fit in memory as a calibration spectrum; The system of claim 13 , further configured to perform operations including:

15. The one or more processors: loading the calibration spectrum; performing one or more of k-linearization, dispersion correction, and spectral flattening using the loaded calibration spectrum; The system of claim 14 , further configured to perform operations including:

16. the interferometer comprises a plurality of optical switches, at least two of the plurality of optical switches connected to one another by a length of optical fiber, the plurality of optical switches in a first position forming a first optical path for optical signals to and from the light source and the catheter, and the plurality of optical switches in a second position forming a second optical path for optical signals to and from the light source and the length of optical fiber; The one or more processors are configured to perform operations including receiving a back reflection of an optical signal at a connection point between the first optical connector and the second optical connector, and determining, based on the back reflection, whether the catheter is fully connected or not fully connected to the light source. The system of claim 13.

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