Intraoral OCT Devices

Abstract

A handheld optical device for imaging a sample includes an interferometer having at least an output waveguide and a collection waveguide formed on an integrated optical circuit substrate. A light source generates light at a wavelength above a threshold wavelength. A first signal detector acquires an interference signal from the interferometer between a first portion of the light scattered from the sample and a reference portion of the light. A processor is programmed with instructions to perform optical coherence tomography on the acquired interference signal.

Description

[Technical field]

[0001] The present disclosure relates generally to devices for optical coherence tomography (OCT) imaging, and more specifically to a handheld device that provides OCT functionality in a highly compact OCT scanner. [Background technology]

[0002] Optical coherence tomography (OCT) is a non-invasive imaging technique that uses interference principles to obtain high-resolution cross-sectional images that characterize the depth structure of a sample. Particularly suited for in vivo imaging of human tissue, OCT has demonstrated its utility in a range of biomedical research and medical imaging applications, such as ophthalmology, dermatology, oncology, and other fields, as well as ear, nose and throat (ENT) and dental imaging.

[0003] OCT has been described as a type of "photo-ultrasound" that images reflected energy from within biological tissue to obtain cross-sectional data. In an OCT imaging system, light from a broadband source, such as a superluminescent diode (SLD) or other light source, is directed along two distinct optical paths: a reference arm of known length, and a sample arm that illuminates the tissue or other object under study. The reflected and backscattered light from the reference and sample arms are then recombined in the OCT device, which uses interference effects to characterize the surface and subsurface structures of the sample. Interference data can be acquired by rapidly scanning the illumination across the sample. At each of thousands of points, the OCT device acquires an interference profile. The interference profile can be used to reconstruct an A-scan for the axial depth into the material, which accounts for the source coherence. In most tissue imaging applications, OCT can provide image content at a depth of several millimeters (mm) using a broadband illumination source.

[0004] Early OCT devices employed a time-domain (TD-OCT) architecture that achieved depth scanning by rapidly changing the length of a reference arm using some type of mechanical mechanism, such as a piezoelectric actuator. TD-OCT methods require the illumination probe to be moved or scanned from one position to the next during an imaging session using point-by-point scanning. More recent OCT devices use a Fourier-domain architecture (FD-OCT) that distinguishes between reflections from various depths depending on the optical frequency of the signal produced. FD-OCT methods simplify or eliminate the axial scanning requirement by collecting information from multiple depths simultaneously, improving acquisition speed and signal-to-noise ratio (SNR). There are two implementations of Fourier-domain OCT: spectral-domain OCT (SD-OCT) and swept-source OCT (SS-OCT).

[0005] SD-OCT imaging can be achieved by illuminating the sample with a broadband light source and dispersing the reflected and scattered light onto an array detector, such as a CCD (charge-coupled device) detector, using, for example, a spectrometer. SS-OCT imaging illuminates the sample with a fast wavelength-tuning laser and collects the reflected light during a wavelength sweep using only a single photodetector or a balanced photodetector. With both SD-OCT and SS-OCT, a profile of the scattered light reflected from different depths is obtained by manipulating the recorded interference signal using a Fourier transform, such as a fast Fourier transform (FFT), which is well known to those skilled in the art of signal analysis techniques.

[0006] The potential for achieving high performance in low-cost FD-OCT systems based on swept-frequency laser sources has attracted considerable attention for medical applications requiring subsurface imaging of highly scattering tissues.

[0007] One of the challenges for SS-OCT is providing a suitable light source capable of generating the required series of wavelengths in rapid succession. To meet this need, swept-source OCT systems traditionally employ fast wavelength-swept lasers with intracavity monochromators or use some type of external cavity narrowband wavelength scanning filter to adjust the laser power. Examples of external devices that have been used for this purpose include tunable Fabry-Perot filters, whose cavity length is adjusted to provide linear variation of the longitudinal mode, and polygon scanner filters, which selectively reflect dispersed wavelength light. Fourier domain mode-locking is a recently reported technique that has been used to generate swept frequencies that are most useful for OCT imaging, which generally uses broadband near-infrared (BNIR) wavelengths.

[0008] The challenges in adapting OCT for use in intraoral imaging include integrating various modules within an OCT scanner system and managing and coordinating the generation, delivery, sensing, and decoding of the optical signals acquired in an OCT scan. For OCT to become more widely accepted and used, there is a need for more compact component packaging and easily configurable OCT configurations without complex setup considerations, cumbersome signal cabling, and no restrictions on the operation and movement of the intraoral scanning camera. Summary of the Invention

[0009] An aspect of the present application is to advance dental diagnostic imaging or address the need for a more compact OCT instrument for intra-oral use.

[0010] Another aspect of the present application is to address, in whole or in part, at least the above-mentioned and other deficiencies in the related art.

[0011] Another aspect of the present application is to provide, in whole or in part, at least the advantages described herein.

[0012] These objects are given merely as illustrative examples, and such objects may be exemplary of one or more embodiments of the invention. Other desirable objects and advantages inherently achieved by the disclosed method may occur or become apparent to those skilled in the art. The invention is defined by the appended claims.

[0013] According to an aspect of the present application, there is provided a handheld optical device for imaging a sample, the handheld optical device may include an interferometer having at least an output waveguide and a collection waveguide formed on an optical integrated circuit substrate, a light source generating light at a wavelength above a threshold wavelength, a first signal detector acquiring an interference signal from the interferometer between a first portion of the light scattered from the sample and a reference portion of the light, and a processor programmed with instructions to perform optical coherence tomography processing on the acquired interference signal.

[0014] According to an aspect of the present application, there is provided a handheld intra-oral optical imaging device including a probe, the probe being an interferometer formed on an optical integrated circuit substrate, the interferometer comprising a light source generating light at a wavelength above a threshold wavelength, an output waveguide, and a collection waveguide; a signal detector that acquires an interference signal from the interferometer between a first portion of the light scattered from the intra-oral feature and a reference portion of the light; and a processor programmed with instructions to perform optical coherence tomography processing on the acquired interference signal.

[0015] The foregoing and other objects, features and advantages of the present invention will become apparent from the following more particular description of embodiments of the invention, as illustrated in the accompanying drawings.

[0016] Elements in the drawings are not necessarily to scale relative to each other. Some exaggeration may be necessary to emphasize basic structural relationships or principles of operation. Some conventional components that would be required for the implementation of the described embodiments, such as, for example, support components used to provide electrical power, package, and mount and protect the system optics, are not shown in the drawings for simplicity of illustration. [Brief description of the drawings]

[0017] [Figure 1A] FIG. 1 is a schematic diagram showing a related art swept-source OCT (SS-OCT) device using a programmable filter that uses a Mach-Zehnder interferometer.

[0018] [Figure 1B] FIG. 1 is a schematic diagram showing a related art swept-source OCT (SS-OCT) apparatus using a programmable filter that uses a Michelson interferometer.

[0019] [Figure 1C] FIG. 1 is a schematic diagram illustrating a related art OCT device that uses a spectrometer in a spectral-domain (SD) OCT device.

[0020] [Figure 1D] FIG. 1 is a schematic diagram showing components of a related art OCT device for FMCW interferometry.

[0021] [Figure 1E] FIG. 1 is a schematic diagram showing a related art interferometer of an FMCW image acquisition device with a Mach-Zehnder configuration.

[0022] [Figure 1F] FIG. 1 is a schematic diagram showing a related art FMCW interferometer with a Michelson configuration.

[0023] [Diagram 2] FIG. 1 is a schematic diagram showing components of a related art intra-oral OCT imaging system.

[0024] [Diagram 3] 1 shows a galvo mirror used to provide 2D scanning as part of a related art OCT imaging system probe.

[0025] [Figure 4A] FIG. 2 shows a schematic diagram of the scanning motion for acquiring a B-scan.

[0026] [Figure 4B] FIG. 1 shows the OCT scanning pattern for C-scan acquisition.

[0027] [Diagram 5] 5A-5E illustrate the different types of imaging content acquired and generated as part of an OCT processing sequence using the example image of a tooth with severe cavities.

[0028] [Figure 6] FIG. 1 is a schematic diagram illustrating a probe configured for OCT imaging, according to an exemplary embodiment of the present disclosure.

[0029] [Figure 7] FIG. 1 is a schematic diagram illustrating a probe configured for OCT imaging and employing a fiber array unit, according to an exemplary embodiment of the present disclosure.

[0030] [Figure 8] FIG. 1 is a schematic diagram illustrating a probe configured for OCT imaging and having a swept source integrated on a silicon substrate, according to an exemplary embodiment of the present disclosure.

[0031] [Figure 9] FIG. 1 is a schematic diagram illustrating a probe configured for spectral-domain OCT imaging using an external light source, according to an exemplary embodiment of the present disclosure.

[0032] [Figure 10]FIG. 1 is a schematic diagram illustrating a probe configured for spectral-domain OCT imaging with an on-board spectrometer, according to an exemplary embodiment of the present disclosure.

[0033] [Figure 11] FIG. 1 is a schematic diagram illustrating a probe configuration combining OCT scanning and reflectance image acquisition functions according to an exemplary embodiment of the present disclosure.

[0034] [Figure 12] FIG. 1 is a schematic diagram illustrating a probe configuration for battery-powered OCT imaging and a wireless transmitter for untethered operation, according to an exemplary embodiment of the present disclosure.

[0035] [Figure 13] FIG. 1 is a schematic diagram illustrating an intra-oral OCT imaging device according to a tethered embodiment, in accordance with an exemplary embodiment of the present disclosure.

[0036] [Figure 14] FIG. 1 is a schematic diagram illustrating an intra-oral OCT imaging device according to a wireless embodiment, in accordance with an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Following is a detailed description of exemplary embodiments, reference is made to the drawings in which like reference numerals identify like elements of structure in each of the several views.

[0038] When used in the context of this disclosure, the terms "first," "second," etc. do not necessarily imply any ordering, sequential, or priority relationship, but are simply used to more clearly distinguish one step, element, or set of elements from another, unless otherwise specified.

[0039] The term "exemplary" does not imply that the illustration is ideal, but rather indicates that it is used as an example.

[0040] As used herein, the term "energizable" refers to a set of devices or components that perform a indicated function upon receiving power and, optionally, upon receiving an enable signal.

[0041] In the context of this disclosure, the term "optical system" is used generally to refer to lenses and other refractive, diffractive, or reflective components or apertures used to shape and direct beams of light. Individual components of this type are called optical components.

[0042] In the context of this disclosure, the term "scattered light" is used generally to include light that is reflected and backscattered from an object.

[0043] In the context of this disclosure, the terms "viewer," "operator," and "user" are considered equivalent and refer to a practitioner, technician, or other person who views and may operate a camera or scanner, and who may view and manipulate images, such as dental images, on a display monitor. "Operator commands" or "viewer commands" are obtained from explicit commands entered by the viewer, such as by clicking a button on a camera or scanner, or by using a computer mouse, or by touch screen or keyboard entry.

[0044] In the context of this disclosure, the phrase "in signal communication" indicates that two or more devices and / or components can communicate with each other via signals traveling across some type of signal path. The signal communication can be wired or wireless. The signals can be communication signals, power signals, data signals, or energy signals. The signal path can include physical, electrical, magnetic, electromagnetic, optical, wired, and / or wireless connections between a first device and / or component and a second device and / or component. The signal path can also include additional devices and / or components between the first device and / or component and the second device and / or component.

[0045] In the context of this disclosure, the term "camera" relates to a device capable of acquiring a 2D digital image including reflectance from reflected visible or NIR light, such as structured light reflected from tooth surfaces and supporting structures.

[0046] The general term "scanner" refers to an optical system that projects a scanned light beam of broadband near infrared (BNIR) light that is directed through a sample arm to the tooth surface and acquired as returned scattered light in the sample arm to detect interference with light from a reference arm used for OCT imaging of the surface. The term "raster scanner" refers to a combination of hardware components that scan the light towards the sample, as will be explained in more detail later.

[0047] The term "object" refers to the patient's teeth or other part being imaged, and in optical terms can be considered equivalent to the "object" of a corresponding imaging system.

[0048] In the context of this disclosure, the phrase "broadband light emitter" refers to a light source that emits a continuous spectral output over a range of wavelengths at any one time. Short or low coherence broadband light sources include, for example, superluminescent diodes, short pulsed lasers, many types of white light sources, and supercontinuum light sources. Most of these types of short coherence length sources have coherence lengths on the order of tens of microns or less.

[0049] In the context of this disclosure, the term "oblique" refers to an angular orientation that is not an integer multiple of 90 degrees. Two lines or optical paths can be considered to be oblique with respect to one another if they diverge from one another or converge toward one another, for example, at an angle that is about 5 degrees or more away from parallel or at an angle that is about 5 degrees or more away from orthogonal.

[0050] In the context of this disclosure, two wavelengths may be considered "close" to each other when they are within + / - 10 nm of each other.

[0051] According to embodiments of the present disclosure, a programmable light source is provided that can provide variable wavelength illumination, which can be used as a swept source for scanned SS-OCT and other applications that benefit from a controllably alterable spectral pattern.

[0052] The simplified schematic diagrams of FIGS. 1A and 1B each show components of a related art swept-source OCT (SS-OCT) device 100 that uses a programmable filter 10 that is part of a tunable laser 50 .

[0053] In the embodiment of FIG. 1A, a related art Mach-Zehnder interferometer system for OCT scanning is shown. FIG. 1B shows components of a related art Michelson interferometer system. In FIGS. 1A-1B, a programmable filter 10 provides part of a laser cavity for generating the output of a tunable laser 50. The output of the tunable laser 50 is directed through a coupler 38 to a sample arm 40 and a reference arm 42. In FIG. 1A, the signal in the sample arm 40 is sent through a circulator 44 to a probe 46 for measuring the sample S. The signal in the reference arm 42 is directed by the reference, which may be a mirror or a light guide, through a coupler 58 to a detector 60. The sampled signal is sent back through the circulator 44 (FIG. 1A) and through the coupler 58 to the detector 60.

[0054] 1B, the signal is sent directly to sample arm 40 and reference arm 42. The sampled signal is returned through coupler 38 to detector 60. Detector 60 may use a pair of balanced photodetectors configured to cancel common mode noise.

[0055] 1A and 1B, a control logic processor (control processing unit CPU) 70 is in signal communication with the tunable laser 50 and its programmable filter 10, and with the detector 60, and acquires and processes the output from the detector 60. The CPU 70 is also in signal communication with a display 72 for command input and display of OCT results.

[0056] 1C is a schematic diagram showing a related art OCT device that uses a spectrometer 230 in a spectral domain (SD) OCT device 240. A broadband light source 224 directs light through a coupler 38 to a probe 46 to obtain a sampled scan of an intraoral feature or other object. A scanning component that is part of the probe 46 directs light from the broadband illumination source 224 to multiple points along the intraoral feature to perform B-scans and C-scans. The low coherence light from the broadband light source 224 is directed through the coupler 38 to the probe 46 on the sample arm 40 and the reference arm 42. The illumination source 224 can be, for example, a superluminescent diode.

[0057] The resulting interference pattern is measured by a spectrometer 230. The light passes through a light dispersing optic 20, such as a diffraction grating, which causes light dispersion. The lens L2 optics then directs this light to a detector array 232, which may be a CCD (charge-coupled device) array or other sensor within the spectrometer that is sensitive to selected wavelengths or wavenumbers. A processor 236 is in signal communication with the broadband light source 224, the spectrometer 230, and the scanner, and provides logic and control circuitry for image reconstruction and display.

[0058] According to an alternative embodiment of a generalized OCT device, a configuration can be provided that provides frequency modulated continuous wave (FMCW) interferometry, which allows the same probe (e.g., probe 46) to provide information for global surface characterization of teeth, jaws, and facial structures, as well as specific surface characterization of intra- and extra-oral features.

[0059] The schematic diagram of FIG. 1D shows the components of a related art OCT device 10 for acquiring FMCW data from a sample S. A tunable laser diode 320 provides a monochromatic output optical signal of variable frequency to a coupler 14 component that provides a small portion of the light to an interferometer 16 with a fixed path length difference to provide an optical clock for data collection, so that the frequency of the acquired signal can be linearized. A second 1×2 coupler 14′ splits the remaining light along two paths of another interferometer 16, namely, a sample path 24 and a reference local oscillator path 28. The light along the reference path 28 is directed to a 2×2 coupler 34 that provides a local oscillator signal to a balanced detector (BD) 30. The light along the sample path 24 is sent to a circulator 32 and sent from the scanner 22 to the sample S. The return light reflected from the sample S returns to the circulator 32 and the 2×2 coupler 34 and is then sent to the balanced detector 30. A processor 36 obtains distance measurements according to the interference signals from the sample and local oscillator reference paths 24 and 28 , which are combined at a coupler 34 and the interference signals are detected by a detector 30 .

[0060] The tunable laser source 320 can be energized to generate a frequency modulated optical signal. Exemplary tunable laser sources are the external cavity diode lasers from Thorlabs, Newton, NJ, or the tunable pulse fiber from idealphotonics, Vancouver, Canada. The laser source can be based on the Littrow or Littman model configuration. Other examples of tunable laser sources include distributed feedback lasers and tunable vertical cavity surface emitting lasers.

[0061] The frequency of the modulated light from the tunable laser source 320 can be swept linearly and follows a sawtooth profile with respect to time. As the signal propagates through the sample S, scattering and reflection return a portion of the signal to the balanced detector 30, which detects interference between the signal returned from the sample and the local oscillator signal. Alternatively, the modulated frequency may have a triangular profile with respect to time or any other suitable characteristic profile.

[0062] As shown in FIG. 1D, an optional demodulation and low pass filter 98 can be provided to the output signal from the balanced detector 30 in order to selectively capture only a portion of the detection data.

[0063] The simplified schematic of FIG. 1E shows the optical arrangement of a related art Mach-Zehnder interferometer for FMCW imaging of a sample S. Light from a tunable laser source 320 is split into a local oscillator path 28 and a sample path 24. A beam splitter BS1 is shown to direct the light into the two paths 28 and 24. Mirrors M1 and M2 bend the optical path as necessary to make both the sample path 24 and the local oscillator path 28 compact. The light from the sample S and the local oscillator path 28 is combined by a second beam splitter BS2 to form an interference pattern that is sensed by a detector 30, such as a balanced detection photodiode.

[0064] In an embodiment of an intra-oral OCT imaging device 100 using FMCW interferometry, any suitable interferometry model can be used, such as the related art Mach-Zehnder interferometer model shown in Figure IE, or the related art Michelson interferometer as shown in Figure IF. In the embodiment of Figure IF, the sample path uses beam splitter BS1 to route the local oscillator signal and the sample signal back and forth to the sample S. In the Michelson configuration of Figure IF, the signal is routed directly to sample path 24 and local oscillator path 28. The sampled signal is routed back through beam splitter BS1 to detector 30.

[0065] Intra-oral OCT systems are designed using related art interferometry equipment and techniques. In related art designs for OCT embodiments, an intra-oral probe (e.g., probe 46) includes only the minimum components necessary to acquire scan data. Interferometry and related processing is performed using components in signal communication with, but separate from, the probe (e.g., probe 46).

[0066] As shown in FIG. 2, a related art OCT imaging system 200 includes a probe 46 with the minimum components required to acquire scan data for scanning a sample S, and an associated remote imaging engine 56 that includes swept source components, a reference arm and fiber coupling optics, a signal detector, and the acquisition and processing circuitry required to provide intraoral OCT imaging functionality. The imaging engine 56 includes the light source, fiber coupler, reference arm, and OCT detector components described with reference to FIGS. 1A, 1B, 1C, 1D, 1E, and 1F. In one embodiment, the probe 46 includes a raster scanner 90 or partial sample arm. An optional CPU 70 includes the control logic, and an optional display 72 can display the imaging results or dental applications. The requirement to keep the probe 46 itself compact, lightweight, and easy for an operator to handle for scanning a patient's dentition (e.g., to be handheld) has thus far necessitated the use of a separate remote imaging engine 56 to support the required interferometer.

[0067] It will be useful to outline the scanning behavior used in OCT acquisition and briefly review how OCT data is acquired. As shown in the schematic diagram of FIG. 3, galvo mirrors 94 and 96 cooperate to provide the raster scanning required for related art OCT imaging. In the configuration shown, galvo mirror 1 (94) scans a wavelength of light to each of points 82 along the sample to generate data along a row in the x-direction, thereby providing a B-scan, which will be described in more detail later. The scanning light for depth data is directed to the sample S in the z-direction. Galvo mirror 2 (96) gradually moves the position of the row in the y-direction to provide 2D raster scanning to additional rows. At each of points 82, the entire spectrum of light provided is rapidly generated in a single sweep, and the resulting signal is measured at detector 60 (e.g., FIGS. 1A, 1B).

[0068] Scan sequence of OCT imaging The schematic diagrams of Figures 4A and 4B show a scan sequence that can be used to form a tomographic image using an exemplary embodiment of an OCT device according to the present disclosure. The sequence shown in Figure 4A shows how a single B-scan image is generated. A raster scanner 90 (Figure 3) scans a selected light sequence point by point on a sample S. A periodic drive signal 92 as shown in Figure 4A is used to drive the galvo mirrors of the raster scanner 90 to control a lateral scan or B-scan extending across each row of the sample, shown as horizontally extending discrete points 82 in Figures 4A and 4B. At each of the multiple points 82 along the line or row of the B-scan, a successive portion of the selected wavelength band is used to generate an A-scan or depth scan that acquires data in the Z-axis direction. Figure 4A shows the drive signal 92 for generating a straight up sequence using the raster scanner 90, which results in a corresponding actuation of a micromirror or other spatial light modulator pixel by pixel through the wavelength band. A retroscan signal 93, which is part of the drive signal 92, simply returns the scan mirror to the start position of the next line. No data is acquired during the occurrence of the retroscan signal 93.

[0069] Note that, as shown in FIG. 3, a B-scan drive signal 92 drives a galvo mirror 94 of a raster scanner 90. At each incremental position, point 82, along the row of the B-scan, an A-scan is acquired. To acquire the A-scan data, a tunable laser 50 or other programmable light source sweeps a spectral sequence controlled by the programmable filter 10. Thus, in an embodiment in which the programmable filter 10 causes the light source to sweep over a 30 nm range of wavelengths, this sequence is performed at each of the points 82 along the B-scan path. As shown in FIG. 4A, a set of A-scan acquisitions is performed at each of the points 82, i.e., at each position of the scanning galvo mirror 94. By way of example, if a MEMs micromirror array device is used as the spatial light modulator, 2048 measurements are possible to generate an A-scan at each position 82.

[0070] FIG. 4A shows diagrammatically the information acquired during each A-scan. An interference signal 88 (shown without DC signal content) is acquired over a time interval for each of the points 82, the signal being a function of the time interval required for the sweep, and the acquired signal shows the spectral interference fringes generated by combining light from the reference and feedback arms of the interferometer (e.g., FIG. 1A, FIG. 1B). A Fourier transform generates a transform T for each A-scan. One transform signal corresponding to an A-scan is shown by way of example in FIG. 4A.

[0071] From the above, it can be seen that a significant amount of data is acquired over a single B-scan sequence. In order to efficiently process this data, a Fast Fourier Transform (FFT) is used to convert the time-based signal data into corresponding frequency-based data from which image content can more easily be generated.

[0072] In Fourier domain OCT, an A-scan corresponds to one line of spectral acquisition that produces a line of depth (Z-axis) resolved OCT signal. The B-scan data produces a 2D OCT image along the corresponding scan line.

[0073] Raster scanning is used to obtain multiple B-scan data by incrementing the acquisition of the raster scanner 90 in the C-scan (y-axis) direction. This is represented diagrammatically in Figure 4B, which shows how 3D volumetric information is generated using the A, B, and C-scan data.

[0074] As previously mentioned, the wavelength or frequency sweep sequence used at each of the A-scan points 82 can be modified from the commonly used ascending or descending wavelength sequence. Any wavelength sequence can be used in an alternating fashion. With any wavelength sequencing, which may be useful for some particular implementations of OCT, only a portion of the available wavelengths are provided as a result of each sweep. With any wavelength sequence, each wavelength can be randomly selected, in any successive order, to be used by the OCT system during a single sweep.

[0075] 5A-5E illustrate different types of imaging content acquired and generated as part of an OCT processing sequence using the example of an image of a tooth with severe cavities. FIG. 5A shows a 2D slice corresponding to a B-scan of OCT imaging. FIG. 5B shows a depth-encoded color projection of the tooth, with an optional color reference bar 180. FIG. 5C shows a corresponding slice of a volume rendering obtained from the OCT imaging content. FIG. 5D shows the result of the segmentation process of FIG. 5A. In FIG. 5A, points along the tooth surface have been extracted. FIG. 5E shows a tooth surface point cloud 64 generated from the OCT volume data. The surface point cloud 64 can be obtained from the OCT volume data after segmentation.

[0076] Exemplary method and / or apparatus implementations according to the present disclosure provide embodiments of handheld OCT scanner devices (e.g., 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400) that are very compact, and by using optical integrated circuits, reduce or eliminate the need for at least some of the external equipment (e.g., provided in remote imaging engine 56) required in the related art intraoral OCT device configurations previously described.

[0077] 6 shows an exemplary embodiment of a handheld OCT scanner device using integrated optical circuits, according to some implementations. Referring to the schematic diagram of FIG. 6, the probe 46' of the handheld OCT scanner device 600 is shown connected to an external laser source 74 that provides a swept-source laser signal that sweeps across a range of wavelengths for OCT data collection.

[0078] In the embodiment of FIG. 6, the fiber coupler FC couples the laser light into the source arm of an interferometer 130, which is formed as an optical integrated circuit on a substrate 138 (e.g., a silicon substrate) and integrated into the housing (e.g., a handle) of the probe 46′. An internal output waveguide 132 and a collection waveguide 134 are etched on the same silicon substrate 138. The light in the waveguide structure from the swept source SS is split into a sample arm and a reference arm. The sample light is coupled to the output and collimated by a micro-collimation lens 136. The collimated light is focused onto the sample S by an objective lens 140, which is optimized for imaging. The focused beam is directed from the folding mirror 124 onto the sample S by a MEMS mirror 128, which is coupled to the interferometer 130. The lens 136, the mirror 124, and the MEMS mirror 128 are components that can also be integrated onto the silicon substrate 138 as shown in FIG. 6.

[0079] The collection waveguide 134 is placed near the output waveguide 132 (e.g., a few microns, e.g., 100 microns, from the output waveguide 132) to collect the backscattered light from the sample. The output waveguide 132 also collects some amount of the backscattered light. The path length of the reference arm matches the path length of the sample arm. The reference light is split into two reference light portions and interferes with the first sample light and the second sample light. The interference fringes are detected by two sets of on-chip balanced photodetectors 142. Each of the two sets of balanced photodetection provides a complete interference signal for OCT reconstruction. Therefore, having both sets of balanced photodetectors is optional. However, having both sets increases the signal-to-noise ratio.

[0080] A data bus 120 is connected to the probes 46' and may include power connections, which may alternatively be provided separately.

[0081] For example, for intraoral OCT, the laser 50 may be tunable over a range of frequencies (wavenumbers k) corresponding to wavelengths of about 400 nm to 1600 nm. According to an exemplary embodiment of the present disclosure, a tuning range of about 60 nm bandwidth centered at about 1300 nm is used for intraoral OCT.

[0082] FIG. 7 illustrates an exemplary embodiment of a handheld OCT scanner device using an integrated optical circuit, according to some implementations. The embodiment of FIG. 7 is similar to that of FIG. 6, but a fiber array unit (FAU) is employed in the handheld OCT scanner device 700. Additionally, a balanced photodetector 142 is positioned separately from the silicon substrate 138 used for the interferometer. The balanced photodetector 142 is within the housing of the device 700. The fiber array unit FAU is used to couple laser light into the interferometer 130, which is formed as an integrated optical circuit.

[0083] FIG. 8 illustrates an exemplary embodiment of a handheld OCT scanner device using integrated optical circuits, according to some implementations. The embodiment of FIG. 8 is similar to the embodiment of FIG. 6, but with a swept source integrated on the silicon substrate 138 used in the interferometer 130 of the handheld OCT scanner device 800. The integrated swept source can be a tunable vertical cavity surface emitting laser (VCSEL) with a micromechanically movable mirror. The VCSEL can be optically or electrically pumped. Alternatively, the integrated swept source can be a monolithic semiconductor swept source laser.

[0084] 9 shows an exemplary embodiment of a handheld OCT scanner device using integrated optical circuits, according to some implementations. The embodiment of FIG. 9 shows a spectral domain (SD) OCT configuration using an external SLD (superluminescent diode) as the light source 74 of the handheld OCT scanner device 900. A separate spectrometer 150 is also provided external to the probe 46' to detect the interferometric signal.

[0085] 10 shows an exemplary embodiment of a handheld OCT scanner device using integrated optical circuits, according to some implementations. The embodiment of FIG. 10 employs an integrated spectrometer 160 formed on the silicon substrate 138 of the interferometer 130 in the handheld OCT scanner device 1000. This may be, for example, a spectrometer 160 using an arrayed waveguide grating.

[0086] FIG. 11 illustrates an exemplary embodiment of a handheld OCT scanner device using integrated optical circuits, according to some implementations. The embodiment of FIG. 11 illustrates a probe 46' for OCT scanning with additional components for reflectance imaging in a handheld OCT scanner device 1100. A beam combiner 172, such as a dichroic mirror, can be used to provide an image capture device 170 configured to use a portion of the same optical path for reflectance and OCT scanning. The image capture device 170 can include optics, light sources, and image sensing components necessary for monochrome or color imaging, such as to provide a preview image to an operator. Optionally, the image sensing device 170 can also include components to provide structured light projection and capture for surface contour imaging. Reflectance imaging can use light in the visible or near-visible range, such as near-infrared light.

[0087] Figure 12 shows an exemplary embodiment of a handheld OCT scanner device using integrated optical circuits, according to some implementations. According to an alternative embodiment, as shown in the schematic diagram of Figure 12, the probe 46' of the handheld OCT scanner device 1200 may include a battery 144 or other replaceable or rechargeable power source. As shown in Figure 12, the probe 46' may also have a transmitter 146 for wireless communication and data transfer with a host processor.

[0088] FIG. 13 illustrates an exemplary embodiment of a handheld OCT scanner device using integrated optical circuits, according to some implementations. The schematic diagram of FIG. 13 illustrates an intra-oral OCT imaging device 1300 using a probe 46' in a tethered configuration. The control logic processor 70 and display 72 can be integrated into a single unit, such as a laptop computer. In FIG. 13, the control logic processor 70 can alternatively be provided as embedded electronics formed within the probe 46'.

[0089] 14 illustrates an exemplary embodiment of a handheld OCT scanner device using integrated optical circuits, according to some implementations. The schematic diagram of FIG. 14 illustrates an intra-oral OCT imaging device 1400 using a probe 46' in a non-tethered configuration employing wireless communication.

[0090] Consistent with the exemplary embodiment of the present invention, the computer program utilizes stored instructions that are performed on image data accessed from electronic memory. As can be understood by those skilled in the art of image processing, the computer program for operating the imaging system in the exemplary embodiment of the present disclosure can be utilized by a suitable general-purpose computer system that operates as a CPU as described herein, such as a personal computer or a workstation. However, many other types of computer systems, including network processor arrangements, can be used to execute the computer program of the present invention. The computer program for performing the exemplary method of the present invention can be stored on a computer-readable storage medium. This medium can include, for example, a magnetic storage medium, such as a magnetic disk, such as a hard drive, or a removable device, or a magnetic tape; an optical storage medium, such as an optical disk, optical tape, or a machine-readable optical encoding; a solid-state electronic storage device, such as a random access memory (RAM), or a read-only memory (ROM); or any other physical device or medium employed to store a computer program. The computer program for performing the method of the present disclosure can also be stored on a computer-readable storage medium that is connected to the image processor by means of the Internet or other network or other communication medium. Those skilled in the art will further readily recognize that the equivalent of such a computer program product can also be constructed in hardware.

[0091] It should be noted that the term "memory" (which is equivalent to "computer-accessible memory" in the context of this disclosure) may refer to any type of temporary or even permanent data storage workspace (including, for example, a database) that is used to store and operate on image data and is accessible to a computer system. Memory may be non-volatile, for example, using long-term storage media such as magnetic or optical storage. Alternatively, memory may be more volatile in nature, using electronic circuitry such as random access memory (RAM) used by a microprocessor or other control logic processor device as a temporary buffer or workspace. For example, display data is typically stored in a temporary storage buffer directly associated with the display device and is periodically refreshed as needed to provide the displayed data. This temporary storage buffer may also be considered a memory as this term is used in this disclosure. Memory may also be used as a data workspace for performing and storing intermediate and final results of calculations and other processing. Computer-accessible memory may be volatile, non-volatile, or a hybrid combination of volatile and non-volatile.

[0092] It will be understood that the exemplary computer program products of the present disclosure may utilize a variety of well-known image manipulation algorithms and processes. Furthermore, it will be understood that the exemplary computer program products of the present disclosure may embody algorithms and processes not specifically shown or described herein that are useful for implementation. Such algorithms and processes may include conventional utilities that are within the ordinary skill of the image processing art. Such algorithms and systems, as well as additional aspects of hardware and / or software for producing and otherwise processing images or for cooperating with the exemplary computer program products of the present disclosure, may be selected from such algorithms, systems, hardware, components, and elements not specifically shown or described herein but known in the art.

[0093] According to some embodiments, the device includes one or more processors, a non-transitory memory, and one or more programs. The one or more programs are stored in the non-transitory memory and configured to be executed by the one or more processors, and the one or more programs include instructions for performing or causing any of the methods described herein. According to some embodiments, a non-transitory computer-readable storage medium stores instructions that, when executed by one or more processors of the device, cause the device to perform or cause any of the methods described herein. According to some embodiments, the device includes one or more processors, a non-transitory memory, and means for performing or causing any of the methods described herein.

[0094] In various implementations, an exemplary embodiment of an intra-oral handheld optical device includes a housing, an interferometer with at least an output waveguide and a collection waveguide formed on an optical integrated circuit substrate, the optical integrated circuit substrate being within the housing, an interferometer, a light source configured to generate light at a wavelength above a threshold wavelength, a first signal detector configured to acquire an interference signal from the interferometer between a first portion of the light scattered from the sample and a reference portion of the light, and a processor that performs optical coherence tomography processing on the acquired interference signal.

[0095] In some exemplary embodiments, the light source is within the housing or the light source is formed on the integrated optical circuit substrate. In some exemplary embodiments, the first signal detector is within the housing or the first signal detector is formed on the integrated optical circuit substrate.

[0096] In some exemplary embodiments, the integrated optical circuit substrate includes a microelectromechanical system scanning mirror. In some exemplary embodiments, the second signal detector is configured to obtain an interference signal from the interferometer between the second portion of the light scattered from the sample and a reference portion of the light. In some exemplary embodiments, the first portion of the light scattered from the sample passes through a collection waveguide and the second portion of the light scattered from the sample passes through an output waveguide. In some exemplary embodiments, the second signal detector is formed on the integrated optical circuit substrate.

[0097] In some exemplary embodiments, the wireless transmitter or battery is in the housing. In some exemplary embodiments, the processor can perform frequency modulated continuous wave (FMCW) processing on the acquired interference signal. In some exemplary embodiments, the processor is in the housing. In some exemplary embodiments, the housing includes a second light source emitting light in the visible range, a beam combiner in the path of light to and from the sample and an image capture device to acquire reflectance image data from the sample. In some exemplary embodiments, the sample is an intra-oral feature of a patient.

[0098] Exemplary implementations according to the present application may include various features described herein (individually or in any combination).

[0099] Although the present invention has been illustrated with respect to one or more embodiments, changes and / or modifications can be made to the illustrated examples without departing from the spirit and scope of the appended claims. The disclosed embodiments of the present invention are therefore considered in all respects to be illustrative and not restrictive. In addition, a particular feature of the present invention may be disclosed with respect to one of several embodiments, but such feature can be combined with one or more other features of the other embodiments as may be desirable or advantageous for any given or specific function. The use of the term "at least one" means that one or more of the described items can be selected. The term "about" indicates that the described value can be somewhat modified unless such modification results in incompatibility of the process or structure of the embodiment shown. Other embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims, and all changes that come within the meaning and range of equivalents of the present invention are intended to be embraced therein.

Claims

1. 1. A handheld optical device for imaging a sample, the device comprising: Housing and an interferometer having at least an output waveguide and a collection waveguide formed on an integrated optical circuit substrate, the integrated optical circuit substrate being within the housing; a light source configured to generate light at a wavelength above a threshold wavelength; a first signal detector configured to obtain an interference signal from the interferometer between a first portion of the light scattered from the sample and a reference portion of the light; a processor programmed with instructions to perform optical coherence tomography processing on the acquired interference signals; The handheld optical device comprises:

2. 10. The handheld optical device of claim 1, wherein the light source is a superluminescent diode, the light source is a tunable laser, the light source is a tunable vertical cavity surface emitting laser, the light source is an external cavity diode laser, or the light source has a tuning range centered at about 1300 nm with a bandwidth of about 60 nm.

3. 3. The handheld optical device of claim 1, wherein the light source is within the housing.

4. 3. The handheld optical device of claim 1, wherein the light source is formed on the integrated optical circuit substrate.

5. 3. The handheld optical device of claim 1, wherein the first signal detector is a spectrometer.

6. 3. The handheld optical device of claim 1, wherein the first signal detector is a balanced detector.

7. 3. The handheld optical device of claim 1, wherein the first signal detector is located within the housing.

8. 3. The handheld optical device of claim 1, wherein the first signal detector is formed on the integrated optical circuit substrate.

9. 3. The handheld optical device of claim 1 or 2, wherein the integrated optical circuit substrate further comprises a micro-electro-mechanical system scanning mirror.

10. 3. The handheld optical device of claim 1, wherein the output waveguide and the collection waveguide are formed in close proximity to each other for collecting the light scattered from the sample.

11. 3. The handheld optical device of claim 1, further comprising a second signal detector configured to obtain an interference signal from the interferometer between a second portion of the light scattered from the sample and a reference portion of the light.

12. 12. The handheld optical device of claim 11, wherein the first portion of the light scattered from the sample passes through the collection waveguide and the second portion of the light scattered from the sample passes through the output waveguide.

13. The handheld optical device of claim 11 , wherein the second signal detector is formed on the integrated optical circuit substrate.

14. 3. The handheld optical device of claim 1 or 2, further comprising a wireless transmitter configured to provide optical coherence tomography or frequency modulated continuous wave (FMCW) data, the wireless transmitter located within the housing.

15. 3. The handheld optical device of claim 1, further comprising a battery, the battery being located within the housing.

16. 3. The handheld optical device of claim 1 or 2, wherein the processor is programmed with instructions to perform frequency modulated continuous wave (FMCW) processing on the acquired interference signal.

17. 3. A handheld optical device according to claim 1 or 2, wherein the processor is formed from embedded electronics, the processor being within the housing.

18. The handheld optical device of claim 1 or 2, further comprising a beam combiner and a reflectance image detector within the housing.

19. the light source is a first light source, and the handheld optical device further comprises: a second light source within the housing that emits light in the visible range, the beam combiner is in the path of the light to and from the sample and in the path of the light from the second light source; an image capture device for acquiring reflectance image data from the sample; 3. A handheld optical device according to claim 1 or 2, comprising:

20. The handheld optical device of claim 1 or 2, wherein the sample is an intra-oral feature of a patient.

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