Compact MEMS two-dimensional MEMS scanning mirror assembly design and related aspects

Abstract

A micro-electro-mechanical system (MEMS) two-dimensional scanning mirror assembly (310), the scanning mirror assembly having an optical design, the optical design includes a movable MEMS scanning mirror having a reflective surface (334), a point light source (308a) of a light beam, a collimating lens assembly (516) configured to receive light from the light source and output a collimated light beam having an outgoing beam diameter above a threshold toward the reflective surface (334), and an objective lens assembly (510, 512), the collimated light beam reflected from the reflective surface being coupled to the lens assembly (510, 512) via the objective lens assembly (510, 512). 512) from the scanning mirror assembly. The reflective surface (334) is configured to reflect the incident collimated beam to form a probe beam (312) that exits from the mirror assembly as a telecentric beam (312) towards a telecentric image plane having a resolution superior to a threshold of the telecentric beam resolution. The optics of the scanning mirror assembly are configured to provide a total trajectory length L of less than 40 mm from the point light source to the telecentric imaging plane (700).

Description

Technical Field

[0001] The present disclosure relates to a compact MEMS-based two-dimensional mirror assembly and related aspects, and more particularly, but not limited to, a scanning mirror design suitable for compact optical coherence tomography (OCT) and related aspects. Background Art

[0002] Optical coherence tomography (OCT) is an optical device that generates cross-sectional images of biological tissues. Using monochromatic light with a constant phase difference, an axial (depth) resolution of much less than 8 microns can be achieved. Although OCT scans cannot penetrate deep layers, they can provide deep scans of tissues for use in medical fields such as ophthalmology, dermatology, and surgical applications. Therefore, it would be desirable if such an OCT system could detect living tissue in real time (in vivo) and generate images with depth information in other applications. In order to generate images with depth information, multiple one-dimensional scans (called A scans) are performed along the scan line, and these A scans are stacked together to create a two-dimensional image, called a B scan. By acquiring B scans closely and quickly enough, volumetric images of sample tissue detected by OCT can also be obtained.

[0003] To generate a three-dimensional image, an OCT scanner scans a sample at a two-dimensional spatial position through a beam path. Such scanning systems known in the art typically use orthogonal galvanometers to locate the desired two-dimensional spatial position of the sample. In order to avoid the Petzval curvature of the interfering image plane caused by the spatial separation of the galvanometers, relay optics are required to merge the pupils of each scanning mirror into a common pupil, which can then be focused to an imaging plane where each galvanometer has the same optical path length. Alternatively, electromechanical 2D scanning mirror systems are also known in the art that use a single pupil per scanning axis, but due to the physical size limitations of the technology, these systems operate at significantly reduced scanning speeds, making them less attractive than systems that can scan at higher speeds.

[0004] OCT scanners can be used for a variety of surgical procedures where depth information is advantageous. For surgical procedures involving small areas, or where tissue is difficult to reach, such as when using an OCT scanner in eye surgery, the OCT scanner's design needs to differ significantly from that of an OCT scanner that does not require access to or contact with the area being scanned by the OCT scanner.

[0005] Using an OCT scanner while performing surgical procedures places additional design constraints on the form factor of the OCT device. One such constraint is the physical limitations of the size of the combined microscope and OCT adapter. For example, the overall height of the OCT device and any attached microscope used by the surgeon performing the surgery is limited by the design so that the surgeon can view the area being scanned through the microscope while still being able to use surgical tools to access the area under the OCT / microscope to perform the surgical procedure.

[0006] One factor that affects the overall size of an OCT scanner is the size of the scanning mirror assembly. Optical reflective devices based on micro-electromechanical systems (MEMS) can be used to reduce the physical size limitations of the scanning mirror assembly and support higher scanning rates, but the mirrors of these optical reflective devices have a small effective clear aperture. Optical designs with small effective clear apertures in OCT applications result in lower lateral resolution at the image plane or require complex optical designs due to the use of a converging beam incident on a small-aperture MEMS mirror.

[0007] In applications such as metrology or intraoperative OCT, where a flat tomographic image plane is required, the spatial separation of the galvanometer mirrors requires relay optics to merge the pupils of each scanning mirror into a common pupil and then focus it onto the image plane. This results in large, multi-optical scanner designs, which are not ideal for intraoperative systems that require minimal sterile operating space. Optical designs based on small-aperture reflective scanners can result in low numerical aperture designs, resulting in lower lateral resolution, or complex optical designs due to the high incidence angle of the converging beam acting on the small-aperture MEMS mirrors.

[0008] Therefore, the design of OCT scanning systems for surgical procedures is subject to various design constraints, particularly for OCT scanning systems for ocular surgery, where OCT light must enter the interior of the eye via the pupil. The use of an OCT scanner during ocular surgery may impose various design constraints, which may conflict with each other. In order to minimize the distance between the microscope height or other equipment dimensions (depending on the size specifications of the microscope) and the direction of the surgeon and the tissue being operated on, it is known in the prior art to replace the microscope objective lens with the objective lens in the OCT scanning system. The OCT scanner system objective lens is aligned with the optical channel of the microscope optics, which enables the OCT scanner to use the same focal plane as the microscope. However, the structure of known OCT microscope adapter systems currently increases the stack height of the microscope by up to approximately 50 mm when connected to the microscope. Therefore, there is a need to improve the optical design of the OCT adapter to better minimize the stack height (or other dimensions between the surgeon and the operating area) when the microscope and OCT adapter assembly are fixed together. By reducing the stack height, the accessibility of the OCT scanning detection area during surgery can be improved. Summary of the Invention

[0009] The disclosed technology aims to alleviate or eliminate at least some design limitations by providing an improved MEMS-based scanning mirror assembly optical design suitable for OCT scanner applications. In particular, but not exclusively, some embodiments of the disclosed technology provide an ultra-compact, high-numerical-aperture, MEMS-based 2D point-source optical design that utilizes high angles of incidence at the scanning mirror to reduce compound angular coupling when performing two-dimensional (2D) scanning. Some embodiments of the disclosed technology are capable of generating OCT images with high lateral optical resolution from an optical path length equivalent to the image plane. Given the size and dimensions of the optical components in an OCT scanner adapter, achieving the smallest possible footprint (and volume) is limited. However, by modifying at least the internal optical geometry (including the design of the scanning mirror assembly, the beam direction through the objective lens (also used for the microscope), and the deflection angle), a more compact OCT scanner adapter can be achieved that fits within the footprint of a surgical microscope and has a reduced vertical stack height. However, achieving this reduction is not trivial due to the size constraints of the optical components and the need to fit the optical structure into such a confined space.

[0010] The following summary sets forth features of the disclosed technology that may be preferred in some embodiments. The present invention is defined by the appended claims.

[0011] The disclosed technology relates to scanner designs and related aspects suitable for, but not limited to, optical coherence tomography (OCT) scanning applications. Some embodiments of the disclosed technology provide an OCT scanner having an optical configuration that enables a particularly compact housing design. This design is advantageous for use in surgical applications, where the OCT scanner is provided as an adapter for a microscope.

[0012] According to a first aspect of the disclosed technology, there is provided a micro-electromechanical system (MEMS) two-dimensional scanning mirror assembly, the scanning mirror assembly comprising a scanning mirror optical device having an optical design, the optical design comprising at least: a movable reflective surface of the MEMS scanning mirror, the reflective surface being movable in two dimensions; a collimating lens assembly configured to receive a scanning light beam from a scanning light source and output a collimated scanning light beam toward the reflective surface, wherein the collimated scanning light beam has an exit beam diameter of the collimating lens assembly; an objective lens assembly, the collimated scanning light beam reflected from the reflective surface exits the scanning mirror assembly via the objective lens assembly, wherein the configuration of the optical device of the scanning mirror assembly comprises a reflective surface, the reflective surface being configured to reflect the incident collimated scanning beam toward the objective lens assembly to form a telecentric scanning light beam that exits the mirror assembly and is telecentrically directed toward a telecentric imaging plane, wherein the point at which the telecentric scanning light beam is focused in the telecentric imaging plane changes as the reflective surface moves during scanning; and wherein at least the position and size of the scanning mirror optical device within the scanning mirror assembly are configured to minimize a trajectory length L from the light source to the telecentric imaging plane.

[0013] By configuring the scanning mirror assembly to have a track length of 40 mm (millimeters) or less, the lateral footprint of the scanning mirror assembly is kept small, which allows the scanning mirror assembly to be accommodated in a scanner housing that also has a small lateral footprint.

[0014] In some embodiments, the scanning mirror assembly includes an optical block.

[0015] In some embodiments, the optical block is connected to a light source that scans the light beam. In some embodiments, the scanning light source can be mounted on another device, and the scanning light can be injected from the device along the optical fiber.

[0016] In some embodiments, the light source of the scanning beam in the optical assembly is a point light source, for example, an optical fiber end connected to the light source of the scanning beam. The light in the optical fiber can enter the scanning mirror assembly via an optical fiber connector.

[0017] In some embodiments, the position and size of the scanning mirror optics within the mirror assembly defines a track length L from the light source to the telecentric imaging plane, and the track length L is less than or equal to 40 mm.

[0018] In some embodiments, the scanning light is received by the scanning mirror assembly through the end face of an optical fiber used as a point light source. In some embodiments, the numerical aperture of the optical fiber used as the point light source and the focal length of the collimating lens assembly are configured so that the scanning light beam exiting the collimating lens has a beam diameter of at least 3.1 mm.

[0019] In some embodiments, the scanning light source (e.g., the source of scanning light at a scanning mirror assembly) includes an optical fiber end face providing a point light source, and the numerical aperture of the point light source and the focal length of the collimating lens assembly are configured so that the exit beam diameter of the scanning light beam from the collimating lens is configured to be at least 3.1 mm.

[0020] In some embodiments, the design threshold of the telecentric beam resolution at the telecentric imaging plane is better than 6 microns, that is, the image can be resolved to a level less than 6 microns.

[0021] In some embodiments, the numerical aperture of the optical fiber and the focal length of the collimating lens assembly set the collimating lens exit beam design threshold to at least 3.1 mm.

[0022] In some embodiments, the combination of the focal lengths of the scanning mirror objective and the scanning mirror field lens through which the scanning or probe beam emerges from the mirror assembly determines the total track length L.

[0023] In some embodiments, the mirror assembly scans + / - 5 degrees, for example, the reflective surface (334) can be configured to move within + / - 5 degrees of each of two orthogonal axes x, y, which in some embodiments intersect at the optical center of the reflective surface of the scanning mirror.

[0024] In some embodiments, the optical fiber has a numerical aperture of 0.14.

[0025] In some embodiments, the objective assembly optics include an objective lens and a field lens, wherein the total track length L depends on the combined focal length of the objective assembly optics.

[0026] In some embodiments, the objective lens comprises an F2.7 biconvex doublet lens, and the field lens comprises an F19 positive / negative meniscus doublet field lens.

[0027] In some embodiments, the optical path difference (OPD) of the telecentric scanning or probe beam output by the scanning mirror assembly has a curvature radius greater than 100 mm.

[0028] In some embodiments, the telecentricity of the telecentric beam is better than an incident angle of 0.03 degrees at the telecentric imaging plane.

[0029] In some embodiments of the MEMS scanning mirror assembly, the reflective surface of the MEMS scanning mirror comprises a large aperture gold-coated silicon mirror bonded to an underlying mechanical structure.

[0030] In some embodiments, the reflective surface comprises a large aperture gold-coated silicon mirror bonded to the underlying mirror movement mechanism of the MEMS scanning mirror assembly.

[0031] In some embodiments, the mirror assembly is a scanning mirror in an OCT scanner device, and the optical fiber provides a point light source for the OCT beam.

[0032] In some embodiments, the scanning mirror assembly is provided in the housing of the OCT scanner adapter.

[0033] In some embodiments, the OCT scanner device is an OCT adapter scanner for a microscope, preferably a surgical microscope.

[0034] In some embodiments, a MEMS scanning mirror assembly is provided as an optical block in an optical coherence tomography scanner, wherein the scanning beam comprises an OCT probe beam and the light source comprises an optical fiber having an end face serving as a point light source for the OCT probe beam.

[0035] In some embodiments, by using an optical design such that the internal track length within the scanning mirror assembly is 40 mm or less, the housing of the OCT scanner adapter can be mounted to the base of the surgical microscope and fit within at least the lateral footprint of the surgical microscope to which the OCT scanner housing is mounted.

[0036] In some embodiments, the OCT probe beam provides depth scanning of the sample, and the OCT light returned from the sample has a lateral optical resolution equal to or better than 6 μm (micrometers).

[0037] In some embodiments, the OCT light returning from the sample along the OCT detection arm has a lateral optical resolution equal to or better than 6 μm, in other words, a resolution better than 166 line pairs per millimeter.

[0038] In some embodiments, the OCT scanner is provided as an OCT scanner adapter, for example as an attachment to a surgical microscope.

[0039] Another aspect of the disclosed technology provides a spectral domain optical coherence tomography scanner system, the scanner system including an optical interferometer device, the scanner system comprising: a coupler connected to an illumination arm, the illumination arm including a light source, a scanning depth reference arm, a scanning arm and a detection arm, wherein an illumination beam from the light source enters the coupler along the illumination arm, wherein the illumination beam is divided by the coupler into a scanning depth reference beam along the scanning depth reference arm toward a reflective surface and a scanning beam along the scanning arm toward a scanned sample, wherein the scanning arm includes a scanning mirror assembly according to the first aspect or any one of its preferred embodiments, configured to move the scanning beam on the sample so that light returned from the sample returns to the coupler along the scanning arm, wherein the return light from the scanning arm and the return light from the scanning depth reference arm are guided by the coupler to an interference detector located in the detector arm, the interference detector being configured to detect interference between the return light from the scanning arm and the return light from the scanning depth reference arm, and wherein the interference detector is configured to output data including an OCT interference signal of the return light for image processing to generate a tomographic image of the scanned sample.

[0040] In some embodiments, the scanner system includes an image processor configured to process the received OCT interference signal and output an OCT image for display.

[0041] In some embodiments, the scanner system includes at least one display and an image processor configured to process the received OCT interference signals and output the OCT image to the at least one display.

[0042] In some embodiments, a MEMS2D scanning mirror assembly includes a MEMS2D OCT scanning mirror, which includes at least: a movable MEMS scanning mirror having a reflective surface; a fiber optic connector configured to receive an optical fiber, the optical fiber being used as a point light source of an OCT beam that illuminates the reflective surface; a collimating lens assembly configured to output OCT light having an output beam diameter of at least 3.1 mm from the point light source toward the reflective surface, wherein the reflective surface is configured to reflect the incident collimated OCT beam to form an OCT scanning or detection beam, which is emitted from the mirror assembly as a telecentric beam toward a telecentric image plane with a maximum resolution of 6 microns, and wherein the optical device of the scanning mirror assembly is configured to provide a total track length L from a) the fiber optic connector end face of the point light source inserted into the fiber optic connector (as a point light source) to b) the telecentric imaging plane that is less than 40 mm.

[0043] In some embodiments of the scanner system, an objective lens assembly is provided in a detection arm of the scanning mirror assembly to configure a telecentric OCT beam.

[0044] Another aspect of the disclosed technology includes an optical coherence tomography (OCT) scanner system comprising a micro-electromechanical system (MEMS) two-dimensional scanning mirror assembly according to the first aspect disclosed herein or any embodiment thereof.

[0045] Advantageously, some embodiments of the disclosed technology relate to an OCT scanner system comprising an OCT scanner adapter for a surgical microscope, the OCT scanner adapter including an example embodiment of a MEMS scanning mirror assembly disclosed herein. The OCT scanner adapter configuration according to the disclosed technology is compact because the optical design of the MEMS scanning mirror enables an optimal short housing stack height for the optical channel formed by the microscope optics and the attached OCT scanner objective. The optical design also enables a laterally compact housing for the OCT scanner adapter because the path length of the OCT probe light within the scanning mirror assembly block is less than 40 mm. Some embodiments of this design also enable the generation of OCT images with a resolution of 6 microns or less.

[0046] This is particularly useful in eye surgery, where surgeons use a microscope or similar device to magnify the image of the surgical field through the microscope's optics. By providing a magnified view of the surgical field, the surgeon can more clearly see the tissue being operated on while keeping the patient within arm's reach.

[0047] Some embodiments of the OCT scanner system design disclosed herein enable the combined stack height of the microscope and attached OCT scanner adapter 206 to be much lower than previously possible. This design better balances design constraints, enabling the surgeon to view the area being scanned by the OCT scanner through one or more eyepieces of the microscope while keeping the area being scanned within the focal plane of the microscope's optics and still allowing the surgeon to physically access the scanned area to perform the surgical procedure.

[0048] Other aspects of the compact design provide additional benefits. For example, the design of the scanning mirror assembly reflects the beam used to feedback the scanning mirror position onto a different optical plane than that used by the OCT probe beam, and the optical path of the reference beam used to determine the scanning mirror position is advantageously configured to reduce the likelihood that light returned from the feedback arm will contaminate the scanning mirror position reference beam or its light source, or contaminate the OCT probe beam.

[0049] It will be apparent to one of ordinary skill in the art that the above aspects, the appended claims and / or the examples disclosed herein above and later below may be appropriately combined with each other.

[0050] Other features and advantages are disclosed in the subsequent description, claims and drawings of this specification. It is obvious to a person skilled in the art to combine the features disclosed in the context of one aspect or embodiment above with the features disclosed in the specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Some embodiments of the disclosed technology will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0052] Figure 1 The basic principle of the spectral domain OCT system is schematically shown;

[0053] Figure 2A and 2B schematically illustrates front and rear perspective views of an OCT scanner adapter 206 for a microscope according to some embodiments of the disclosed technology;

[0054] Figure 3A and 3B schematically illustrates various views of components of an example of an OCT scanner adapter 206 according to some embodiments of the disclosed technology;

[0055] Figure 4 Shown Figure 3A and 3B An enlarged view of the OCT scanner adapter 206 is shown in FIG;

[0056] Figure 5A schematically illustrates an example of a MEMS scanning mirror assembly optical design according to some embodiments of the disclosed technology;

[0057] Figure 5B Schematically shows Figure 5A More details of the input arm 518;

[0058] Figure 6 Schematically shows Figure 5A An example of a collimating lens assembly for an input arm;

[0059] Figure 7 An example of an objective lens assembly of a MEMS scanning mirror assembly according to some embodiments of the disclosed technology is schematically shown. DETAILED DESCRIPTION

[0060] The following detailed description provides examples of embodiments of the disclosed technology that are explained in sufficient detail to enable those skilled in the art to put the disclosed technology into practice.

[0061] There are two types of OCT scans: time-domain OCT (TD-OCT) and spectral-domain OCT (SD-OCT). SD-OCT uses spectral demodulation technology on the spectrum output by the OCT interferometer.

[0062] Figure 1 The operating principles of an example spectral domain optical coherence tomography (SD-OCT) interferometer scanning system 100 are schematically shown, which includes some embodiments of the disclosed technology.

[0063] exist Figure 1 In the example SD-OCT system 100 shown, the SD-OCT system 100 can be used to generate optical coherence tomography images of an in vivo tissue sample 116 (eg, a human eye) by probing within the tissue sample 116 using a scanned beam of OCT light.

[0064] Obviously, Figure 1 The system 100 is shown schematically in FIG. 1 , and is not drawn to scale. Figure 1 The positions of the components of the SD-OCT system 100 and their relative sizes shown in FIG. 1 do not necessarily reflect their actual or relative positions or sizes in example embodiments of the disclosed technology.

[0065] Hereinafter, reference to an OCT scan image or image data may refer to a one-dimensional A-scan, a two-dimensional B-scan comprising multiple A-scans, or a volumetric scan image comprising multiple B-scans, as appropriate, which will be apparent to a person of ordinary skill in the art.

[0066] like Figure 1 As shown, the SD-OCT system 100 includes a low-coherence broadband optical scanning light source 102. The scanning light source 102 is suitably connected to a coupler 104, which is configured to split the light from the light source 102 into a reference beam of OCT light that follows an optical path 103a along a reference arm 103, and a detection or scanning beam of OCT light that follows an optical path 105a along an OCT detection arm 105. The OCT light returning along the reference arm 103 and the detection arm 105 will have different phase shifts, which will cause interference when the returning light is recombined at the coupler 104. The combined light signal is output from the coupler along a detection or output arm 107, and the light interference pattern is detected using a spectrometer 136. The light signal 146 output by the spectrometer 136 is then processed by an image processor 148, for example by applying a Fourier transform to the output light signal 146, to generate OCT scan data, which can then be displayed on a suitable display 152.

[0067] The different phase shifts between the OCT light returned by the reference arm and the OCT light returned from the detection arm, which results in the detected interference pattern, occur because the OCT light returns from one or more different structures at different depths on or within the scanned tissue sample 116. In some embodiments, the scanned tissue sample may include an object of interest 112 that is a different type of object than an in vivo tissue sample located in a region of the human body.

[0068] The phase shift that creates interference is affected by the different depths of the OCT light returning from structures within the sample being scanned. The interference caused by the phase shift allows the signal output 146 of the spectrometer 136 to be used to generate images called tomographic images that can visually display the depth and location of one or more such structures in the scanned or probed area.

[0069] exist Figure 1 In some embodiments of the SD-OCT system 100 shown, the broadband OCT light source 102 has a central wavelength of 860 nm (nanometers) and a bandwidth of 100 nm. In some embodiments, more than one light source 102 is used to provide broadband low-coherence OCT scanning light over a desired bandwidth.

[0070] The probe OCT beam is received after being backscattered or reflected or otherwise returned by any structure at a particular depth in region 116 (including the tissue sample being scanned). In some embodiments, one or more or all of the optical paths 101a, 103a, 105a, 107a can be implemented with a suitable single-mode optical fiber and can include one or more portions where the beam propagating along the optical fiber travels in free space.

[0071] Figure 1 In an embodiment of the SD-OCT system 100 schematically shown in FIG, a reference beam is emitted from a coupler 104 and propagates along a reference arm 103 via a collimating lens 106, is then reflected by a moving reference mirror 108, and is returned along the reference arm 103 toward the coupler 104. An optical path 103a along the reference arm 103 and an optical path 105a along the detection arm 105 toward the focal plane 154 (for illuminating the sample or other object of interest being scanned) are configured to have equal optical path lengths. Based on the interference detected between the returned reference beam and the returned OCT probe beam when recombined at the coupler 104, the depth (or depths) of any structures within the sample that have backscattered, reflected, or otherwise returned the probe beam can be determined by outputting a detected interference signal 146 to an image processor 148.

[0072] In some embodiments, a suitable spectrometer 136 (e.g. Figure 1The OCT system 100 measures the interference between the returned reference beam and the returned OCT probe beam along the output arm 107 to determine the depth of the scanned cross-sectional image. Other embodiments of the OCT system 100 may use other techniques to measure interference and generate the output signal 146.

[0073] In some embodiments of the OCT system 100, one or more or all of the optical paths 101a, 103a, 105a, 107a include suitable single-mode optical fibers and / or include one or more portions in which an OCT beam propagating along the optical fiber propagates in free space as it propagates outwardly or inwardly relative to a coupler.

[0074] In some embodiments of the disclosed technology, although the optical path lengths followed by the reference beam and the probe beam are matched, the dispersion characteristics of the optical fiber along which each beam propagates are configured to be different to improve the removal of the complex conjugate image from the OCT image output, thereby improving the image quality of the OCT scan image and the speed of obtaining complex conjugate resolved OCT scan images.

[0075] In some embodiments, the term OCT scan is used herein to refer to B-scan and volume scan images of a tissue region (also referred to herein as a tissue sample) 116 generated using the spectral-domain SD-OCT scanner system 100 .

[0076] exist Figure 1 In the spectral domain OCT example schematically shown in FIG, a broadband light source 102 generates an OCT probe beam that illuminates a tissue region 116 that is scanned by the OCT probe beam in the near-infrared wavelength range.

[0077] Figure 1 The spectrometer 136 shown includes a collimating lens 138, through which the light returned passes through a grating 140 to generate a spectrally dependent interference pattern. The interference pattern is focused onto a line array camera 144 via an objective lens 142, and an image signal representing the interference pattern is transmitted from an output 146 to a suitable image processing system 148. However, in alternative embodiments, another type of suitable interference detector may be used in the output arm 107.

[0078] Figure 1 In the embodiment of the SD-OCT system 100 shown, the spectrometer 136 measures the spectral interference in the returning OCT beam by measuring the intensity modulation of the returning OCT beam as it varies with frequency. The rate of change of intensity at different frequencies indicates the location of different reflective layers in the sample.

[0079] The OCT detection beam propagates from the OCT detection branch 105 of the coupler 104 along the optical path 105 a of the coupler 104 and then enters the OCT scanner 164 . Figure 1 The example OCT scanner 164 shown includes a collimating lens 110, a scanning mirror assembly 310 (e.g., Figure 3A 5, such as described later below), the scanning mirror assembly 310 includes a reflective surface 334 (see, for example, FIG. Figure 3A 5 ), the reflective surface 334 deflects the OCT scanning beam out of the scanner 164 via the objective lens 114 and toward the focal plane 154 in the scanning area 116. The scanning mirror assembly 310 includes a mirror positioning system that includes a secondary light source 158 that is also reflected by the scanning mirror 112 of the scanning mirror assembly toward the scanned sample area 116. The scanning mirror assembly includes a mirror positioning system 156 that includes a light source 158 and a mirror position detector PSD 160 for detecting the mirror position. The OCT scanner 164 also includes the objective lens 114 that focuses the OCT scanning beam on the focal plane 154 within the tissue or sample area 116 being scanned.

[0080] The scanning mirror 112 may include a micro-electromechanical system (MEMS) scanning mirror that is driven by a mirror mover ( Figure 1 Movement of the scanning mirror 112 causes the OCT probe beam to be scanned across the sample or other object of interest being scanned, and the resulting interference pattern is used to generate an OCT B-scan image from the system output 156.

[0081] The movement of the mirror mover is performed under the control of the controller 162. The controller 162 may be located in a scanning mirror assembly including the scanning mirror 112 or may be located remote from the scanning mirror 112.

[0082] Figure 1 The mirror positioning system 156 shown includes an optical angular displacement mirror position measurement system 156. This system provides feedback to the controller regarding the mirror position and, in some embodiments, enables closed loop control of the position of the MEMS-based scanning mirror in some embodiments.

[0083] When the OCT scanner 164 is in use, the scanning mirror 112 guides the OCT beam along a scanning path via a mirror movement mechanism under the control of the controller 162. After being reflected by the mirror 112, the OCT detection beam passes through the telecentric objective lens 114, which focuses the OCT detection beam at different positions in the focal plane 154 of the sample tissue 116 being scanned. Figure 1 Schematically illustrated, the focal plane 154 is shown as lying in an imaginary xy plane, with depth information provided vertically along the z-axis.

[0084] Figure 1The telecentric objective lens 114 is shown, through which the probe beam reaches the sample 116, and the return probe beam also passes through the telecentric objective lens 114, wherein three exemplary outgoing telecentric beams are shown, which are focused at different positions in the focal plane 154, which is located at Figure 1 The outgoing telecentric beam in each example comes from a different position of the scanning mirror assembly 112. In other words, Figure 1 Three sequential telecentric beam positions are schematically shown by way of example only. This is to schematically illustrate how the telecentric OCT scanning or detection beam moves to illuminate different areas as a B-scan or volume scan is performed.

[0085] The area being scanned includes a sample of tissue 116. Figure 1 In this example, this includes tissue of the eye 116, which may be an in vivo or in vitro tissue sample. In other uses of the OCT scanning system, other types of human or animal tissue may be scanned in vivo or in vitro, where the OCT scan images may be used to visualize internal structures at different depths within the tissue.

[0086] For example, Figure 1 As shown, an eye 116 is schematically illustrated including a pupil 118 surrounded by an iris 120 posteriorly followed by a posterior chamber 122 and zonular fibers 124 , and anteriorly followed by the lens 126 and cornea 128 of the eye. Figure 1 Also shown are the anterior chamber 130 of the eye, as well as the ciliary muscle 132 and the zonules 134 , which can all be scanned using an OCT system, such as OCT system 100 , and shown as internal structures in the tomographic image presented on display 152 .

[0087] When performing surgery on tissue such as the human eye or other biological eyes, the use of OCT can increase the likelihood of successful surgery due to the extremely low accessibility of the surgical site. In some embodiments, the OCT system 100 can be used to perform a two-dimensional or three-dimensional scan of an area of ​​the eye 116 during surgery and create images that can be presented in real time to the person performing the surgery. This can allow for a better understanding of the depth of any procedure being performed while the surgery is ongoing. Providing real-time depth information of the surgical area during surgery can help the surgeon avoid making incisions that are too deep (which may unnecessarily damage deep tissue) or too shallow (in which case the surgery may not be successful and / or the surgical site healing time is prolonged).

[0088] like Figure 1As schematically shown, the interferometric signal output 146 of the spectrometer 136 of the OCT system 100 is post-processed by an image processor 148. For example, the signal output 136 may be subjected to image processing of the OCT scan using a Fourier transform or other suitable signal transform. This may initially generate a distorted OCT scan image, which may then be subjected to additional image processing to remove the distortion before outputting the OCT scan image 150 to a suitable display 152. Some embodiments of the OCT scanner system 100 may also use image processing to remove complex conjugate artifacts to enhance the depth range of the acquired image.

[0089] Display 152 can be part of the device that contains SD-OCT system 100 and performs image processing, or it can be a separate device. Some example embodiments of the disclosed technology use the OCT probe beam to generate a series of OCT scan images 148 quickly enough to provide a real-time video stream including OCT scan images 150 on display 152. In some embodiments, display 152 can be a near-eye display. In some embodiments, display 152 can be a large display system including multiple displays to present information to the surgeon and / or others in the operating room. Display 152 can be integrated into SD-OCT system 100 or located externally thereto.

[0090] Figure 1 Of the components forming the OCT scanning system 100 shown in FIG, one or more components can be separated from the optics forming the OCT scanning device 164. By separating the OCT scanner optics, the OCT scanner 164 can have a more compact structure. A more compact OCT scanner 164 can be better positioned near the sample area being scanned.

[0091] In some embodiments, the OCT scanner system 100 includes an OCT scanner 164 provided as a microscope adapter, e.g., for Figure 2A and 2B 200 . In some embodiments, the microscope 200 comprises a surgical microscope suitable for use in surgical procedures. The housing 202 of the microscope 200 has a base that, in some embodiments, is configured to accommodate one or more microscope accessories, thereby allowing the OCT scanner adapter 206 to be attached to the base of the microscope housing. The OCT scanner adapter optics objective 114 can also be used as the microscope objective 210 (see also Figure 3A 、 3B and 4).

[0092] Example of a microscope system with an OCT scanner adapter

[0093] Figure 2Aand 2B Schematic diagram illustrating front and back perspective views of an OCT scanner adapter 206 for a microscope, i.e., an OCT scanner microscope attachment 206 according to some embodiments of the disclosed technology. The term OCT scanner adapter is used herein to refer to an OCT scanner adapter microscope attachment. In some embodiments of the disclosed technology, reference to an OCT scanner adapter may also refer to a device that includes an integrated OCT scanner adapter.

[0094] Figure 2A and 2B Shown Figure 3A 、 3B 4 and 5. The OCT scanner adapter 206 can be mounted to the base of the microscope 200. The OCT scanner adapter 206 microscope accessory can be retrofitted to the microscope 200 by, for example, removing any existing microscope accessories from the microscope base and attaching the OCT adapter 206 to the base of the microscope 200 using its original microscope attachment points. Once properly secured in place, the OCT scanner adapter is configured to align the objective lens 210 with at least one optical channel of the microscope optics, such as a rear channel or a channel for a microscope camera. In some embodiments, the base of the OCT adapter can also provide attachment points for adding accessories.

[0095] In some embodiments, the OCT scanner adapter 206 has a vertically compact configuration so that, when in use, it does not add significant height h2 to the height h1 of the microscope to which it is attached. By reducing the additional vertical height h1 of the OCT scanner adapter 206, accessibility to the scanned area can be improved when using the microscope while simultaneously using the scanner to generate cross-sectional images of the scan area 116. The OCT scanner adapter 206 is also laterally compact. This means that, when attached to the microscope 200, it does not unduly obstruct surgical access to the tissue area being scanned, thereby allowing simultaneous surgical procedures to be performed.

[0096] In the following description, when reference is made to a height, it is intended that tissue sample 116 will be scanned using OCT scanner adapter 206 from a position above the tissue sample, such as may occur when OCT scanner adapter 106 is mounted to the base of surgical microscope 200 .

[0097] Some embodiments of the OCT scanner 206 described herein can maintain a similar compact form factor and be used in other situations. In addition, in some embodiments, the OCT scanner 206 can be provided for integration into other devices (such as the microscope 200). In some embodiments, the OCT scanner 206 can be distributed as an optional accessory to such a device, allowing it to be distributed and sold independently of the microscope to which it is later attached. Therefore, unless the context clearly prohibits otherwise, references to height also apply to other dimensional directions of the OCT scanner that are substantially or approximately orthogonal to the OCT objective lens plane and any device to which the OCT scanner is attached. In addition, the orientation of the OCT scanner and microscope stack may also vary depending on one or more of the patient orientation, the configuration of the microscope optics, and the position of the eyepiece.

[0098] In other words, references to height in the context of an overall "height" are based solely on the assumed orientation of the OCT scanner and microscope relative to a supine patient, i.e., the orientation in which the surgical procedure is being performed on the patient. While the patient is supine, the surgeon can, in accordance with the following embodiments of the OCT scanner adapter 206 implemented by the disclosed technology, access the area being operated on while still having physical access to the eyepieces of the microscope 200 to which the OCT scanner 206 is attached. In some embodiments, this geometric configuration can vary depending on the configuration of the microscope optics and / or the orientation of the patient and / or the location of the surgical field. Therefore, in the following description, references to the height and / or combined stack height of the microscope and OCT scanner adapter 206 may also refer to other dimensions of the microscope and OCT scanner adapter 206 that serve as constraints on the size specifications of the OCT scanner, as will be apparent to one of ordinary skill in the art.

[0099] Now back Figure 2A and 2B The microscope optical device is installed in the microscope housing 202 to form an optical channel, which can observe the area below the objective lens 210 of the OCT scanner adapter 206. In some embodiments, the objective lens 210 provided by the OCT scanner adapter 206 to the microscope 200 includes Figure 1 1 and 2. Thus, references to the objective lens 210 in the description may refer to the objective lens 114 of an OCT system 100 that includes a different type of OCT scanner 164, unless the context clearly limits the reference to using the OCT scanner only as an adapter or accessory for a microscope.

[0100] exist Figure 2AIn the illustrated example embodiment of the OCT scanner adapter 206 , the OCT scanning optics are designed to have a compact form factor, minimizing the additional height h2 added to the height h1 of the microscope optics housing 202 .

[0101] Figure 2A and 2B Also shown are microscope handles 204a, 204b for positioning the microscope 200 over the area to be scanned (and observed). The OCT scanner adapter 206 includes a housing 208, which is secured to the base of the microscope 200 as shown. However, as described above, in some embodiments, the OCT scanner adapter 206 can have different configurations and / or orientations during use. Such different configurations and / or orientations of the OCT scanner adapter 206 during use can also achieve the compact design principles of the OCT scanner disclosed herein.

[0102] Figure 2B Shown Figure 2A Different rear views of the OCT scanner adapter 206 are shown. The rear view shows a data and / or power port 212, such as an RSJ45 Ethernet port or a USB port, and an optical port 214. Port 212 provides power to the OCT scanner adapter 206 and, in some embodiments, may include a Power over Ethernet port.

[0103] In some embodiments, the OCT scanning light is returned from the OCT scanner adapter 206 to the OCT scanning system 100 (eg, Figure 1 Interferometry components shown).

[0104] For example, in Figure 1 In the embodiment of the present invention, the return OCT light from the sample 116 is returned through the objective lenses 210 and 114 and output through the optical port 214 along the optical fiber 308a. The optical fiber 308a, along with the mirror lens assembly and other optical components of the OCT scanner adapter 306 along the optical path of the OCT scanning beam toward the scanned sample, together form part of the detection arm 105 of the FD-OCT system 100.

[0105] After emitting and illuminating the scanned sample tissue 116, the OCT light is reflected, backscattered, or otherwise returned. The returned OCT light then passes back through the coupler 104, where it interferes with the light returning from the reference arm 103. The returned OCT beam and the reference beam then propagate along the output arm 107 to the spectrometer 136, which outputs an optical interference signal 136 of the OCT and reference beams for image processing to generate OCT imaging data 146, which is presented on a display 152.

[0106] In some embodiments of the disclosed technology, for example Figure 1 、 2A As shown in FIG. 2B , the returned OCT light is output from the OCT scanner adapter 206 to the coupler 104 through the optical port 214 , and is transferred to the spectrometer 136 of the spectral OCT system 100 via the coupler 104 .

[0107] exist Figure 2A and 2B In the illustrated embodiment, the OCT scanner housing 208, including the objective lens 210, adds a height h2 to the height h1 of the microscope 200. By utilizing the optical design of the OCT scanner optical components within the OCT scanner adapter 206 according to embodiments of the disclosed technology, the additional stack height introduced by attaching the OCT scanner adapter 206 to the microscope housing 202H2 is minimized.

[0108] For example, some embodiments of the optical assembly design of the OCT scanner adapter 206 may have Figure 3A 、 3B , 4 and 5A and 5B. This optical design lifts the OCT beam emerging from the scanning mirror assembly 310 upward from the plane of the objective lenses 114, 210 by a minimal amount before the OCT beam emerges through the objective lenses 114, 120. This allows the additional stack height h2 of the OCT scanner adapter to be less than 40 mm, and in some embodiments, the additional stack height h2 is 36 mm or less.

[0109] It should be understood that Figure 2A and 2B The figures are not drawn to scale, and the xyz axes shown in the figures are schematic and are used only to illustrate the general front and rear perspectives. Figure 2A and 2B As shown, the microscope housing body stack height is h1 and is aligned with the Z axis, while the microscope housing base and OCT scanner adapter 206 are primarily aligned with the XY horizontal plane. The base-mounted OCT scanner system stack height h2 is also aligned with the Z axis. This allows the full stack height h3 of the main body of the microscope containing the microscope optics and the base-mounted OCT scanner to be determined by h1 and h2. Preferably, the combined height h3 of h1 + h2 = h3 is short enough so that the microscope can be positioned to allow the user to operate the microscope while performing surgery on or through an area that includes the focal plane of the microscope objective 210, through which the OCT beam emerging from the microscope can be observed. The OCT optical design allows h2 to be minimized to 36 mm while still maintaining a suitable exit beam diameter, such as 10.6 mm, in some embodiments, and still having a stack height of 36 mm or less.

[0110] Therefore, by using the optical design of the scanning mirror assembly optics according to embodiments of the disclosed technology, the combined stack height h3 = h1 + h2 can be made much shorter than was possible with previous optical design configurations.

[0111] By minimizing the stack height, the microscope can be better positioned for surgical procedures. For example, it can be positioned far enough from the focused tissue sample to allow the user to access the tissue sample being manipulated, yet close enough to accommodate typical human physical form factors. In other words, the OCT adapter height h2 is preferably minimized to ensure that the user can perform routine operations on the microscope while performing a surgical procedure. The microscope, through the microscope objective 210 of the OCT scanner adapter 206, optically focuses the focal plane on the tissue sample while the OCT probe beam is emitted onto the tissue sample via the microscope objective 210.

[0112] Figure 2A and 2B Some embodiments of the illustrated OCT scanner adapter 206 microscope attachment include a scanning mirror assembly 310 (described in more detail below) having a compact optical design that allows h2 to be minimized to 36 mm or less.

[0113] For example, in some embodiments, as shown below with reference to Figure 3A 、 3B As described in and 4, the OCT scanner adapter 206 includes an ultra-compact, large numerical aperture, micro-electromechanical system (MEMS)-based two-dimensional (2D) scanning mirror assembly 310 that uses a point source 158 to determine the position of a mirror surface 334 in its optical design via a position sensitive detector 160.

[0114] Some embodiments of OCT scanner assemblies using PSD 160 can support very high scan rates, such as 36,000 or more A-scans per second, where an A-scan is a depth scan of a point in tissue. Each B-scan is formed from multiple adjacent A-scans and can be used to generate an image with depth information of the scanned area, which is sliced ​​through the scanned sample to show structures at different depths along the slice. In other words, a B-scan provides a single linear path along a tissue sample (e.g., along a line such as a plane). Figure 1The OCT assembly provides information about structures in the z-direction, or depth, traversed by a linear scan (e.g., a line definable in xy coordinates schematically shown in FIG). Some embodiments of the OCT assembly allow for the generation of high-resolution images, such as 400 B-scans per second, in real time across the entire field of view (FoV) being scanned, which can be, for example, an area of ​​20 mm x 20 mm or larger. By performing a series of B-scans across the sample quickly enough and close together, a three-dimensional volumetric or composite scan of the scanned area can be formed and presented on the display 152.

[0115] Figures 3A to 3B , 4 and Figure 5A and 5B An embodiment of the scanning mirror assembly, shown in greater detail in FIG. 3 as optical block 310 , includes various optical elements arranged in an optical design intended to reduce the height h 2 and lateral footprint of the OCT scanner adapter 206 .

[0116] Some embodiments of the optical design of the scanning mirror assembly specify one or both of the minimum and maximum exit beam diameters of one or more optical components. For example, the OCT beam input via optical fiber 308A is directed from the collimating lens assembly 516 (e.g., Figure 6 When the collimating lens 602 shown in FIG. 5 is used, the beam diameter is preferably greater than a threshold diameter of 3.1 mm, and in some embodiments, the beam diameter from the collimating lens can have an exit pupil diameter of 3.3 mm. Other design constraints may depend on the exit pupil diameter of the OCT beam from the collimating lens. For example, in some embodiments, the collimated OCT beam emerges from the collimating lens assembly with an exit pupil diameter of at least 3.1 mm (and possibly up to 3.3 mm) and has a wavefront error of less than (approximately) 1 / 2 wave (rms).

[0117] Another exit beam diameter selected is the beam diameter of the OCT beam 312, which exits the focusing lens assembly 314 of the OCT scanner adapter 206 and is then incident on the deflecting mirror 316. The focusing lens 314 expands the OCT scanning or detection beam diameter to 10.6 mm to set the OCT system numerical aperture and ultimately the resolution of the OCT scanner system based on the focal length of the OCT microscope objective 210. For an objective 210 with a working distance of 175 mm (non-focal length), the lateral resolution is 30 μm, or in other words, a resolution better than 33 line pairs per millimeter. This can be compared to a resolution of 6 microns (166 line pairs per millimeter) at the intermediate imaging plane located at the exit of the OCT objective assemblies 510, 512.

[0118] In some embodiments, a user may access the Figure 1The user interface of the apparatus of the image processing system 148 shown, which includes or is connected to the display 152) sets the maximum FoV of the scan to an area of ​​20 mm x 20 mm. In some embodiments, the user interface is configured so that the user can adjust the position of the OCT scan FoV within the 25 mm box, although the complete FoV of the OCT scan image remains the 20 mm x 20 mm area.

[0119] Embodiments of the disclosed technology for surgical procedures and other use environments requiring real-time image processing may use a high-dispersion configuration of the OCT system 100 with the OCT scan adapter 206 .

[0120] The term real-time, as used herein, refers to processing latency that is imperceptible, for example, 60ms or less, with latency of approximately 30ms or less achievable in some embodiments. The design utilizes a high angle of incidence at the scanning mirror to reduce compound angular coupling when performing 2D scanning of samples with high lateral optical resolution and a telecentric image plane.

[0121] The following Figure 3A 、 3B , 4 and 5A are described, which uses a high angle of incidence at the scanning mirror reflective surface 334 to reduce compound angular coupling when scanning the sample in 2D, thereby enabling OCT scanning to achieve high lateral optical resolution and a telecentric image plane simultaneously. Each OCT scan includes a large number of one-dimensional scans (A scans) that provide depth information for a point in the scanned area (e.g., a sample). Multiple A scans are stacked together to create a two-dimensional image, referred to herein as a B scan. The B scan provides a slice through the scanned area that shows depth information along the path of the A scan. Multiple B scans through the scanned area can provide a three-dimensional volume scan of the scanned area.

[0122] The scanning mirror assembly 310 includes a movable reflective surface 334 that includes a micro-electromechanical system with a suitably large numerical aperture. The term "large numerical aperture" herein refers to the clear aperture of the reflective surface 334, which is preferably greater than about 4 mm in diameter. The term "clear aperture" refers to the range of angles over which the aperture can be imaged without being obstructed by any supports, clamps, or other fixing elements. The larger the diameter of the clear aperture of the scanning mirror reflective surface 334, the slower the scanning rate because the probe beam covers a larger diameter. Although MEMS mirrors with clear apertures of approximately 7 mm are known in the art, even with optical feedback, such known MEMS mirrors with large clear apertures are unable to achieve acceptable scanning rates for real-time imaging applications such as those required for OCT during optical surgery. In some embodiments, the scanning mirror has a clear aperture of 5 mm. In some embodiments, a scanning mirror assembly with a clear aperture of 4.2 mm is used, which is capable of performing scanning at a sufficiently high rate to enable Figure 1 The SD-OCT system shown is used for real-time surgical applications.

[0123] In OCT, axial and lateral characteristics are decoupled. Lateral resolution is defined by the objective lens and focusing medium in front of the sample. The axial characteristics of the interferometry are determined by the coherence properties of the OCT scanning light source and how the returning OCT signal is sampled on the detector after returning from the sample. OCT axial resolution depends on the spectral bandwidth and central wavelength of the OCT scanning light source. Axial imaging depth defines the axial range covered by the B-scan. It is also defined by the maximum detectable fringe frequency, as the maximum frequency of the interferometric spectrum can decode the maximum scan depth.

[0124] An A-scan is an amplitude depth scan of a sample along one dimension (often called the z-axis), and a B-scan is a two-dimensional lateral scan of the sample formed by a series of A-scans. In other words, for each sample point, the spectrally correlated interference fringe pattern generated by the back reflection from the OCT interferometer's reference mirror and the back reflection from the sample is recorded as an A-scan. Performing multiple A-scans to generate other scans, such as B-scans, allows for the generation of a complete depth profile of the sample reflectivity at the beam position.

[0125] In some embodiments, the opening diameter is 4.2 mm or greater.

[0126] In some embodiments, the OCT scanner adapter 206 includes a MEMS-based high-speed OCT mirror scanning assembly 310 that uses the position-sensitive detector system 160 to provide control loop feedback for controlling the positioning of the OCT beam during scanning. This control loop feedback offers technical advantages because it allows the OCT scanner to generate more B-scans per second of the scanned object of interest. In other words, the control feedback loop provided in some embodiments of the disclosed technology can suppress ringing and resonant behavior caused by sudden changes in the drive voltage at the end of the scan line.

[0127] Example of OCT microscope adapter design

[0128] Figure 3A An example embodiment of a MEMS microscope OCT scanner adapter 206 according to the disclosed technology is schematically shown, which is suitable for mounting to a Figure 2A and 2B The base of the microscope 200 is shown as it is configured with optical components to minimize lateral and vertical footprint while maintaining suitable optical quality characteristics for OCT applications.

[0129] exist Figure 3A , the exemplary embodiment of the OCT scanner adapter 206 is shown to include a plurality of components contained within or mounted on an adapter housing 208. The adapter housing 208 includes a data / power port 212, such as a Power over Ethernet port or a high-speed USB port.

[0130] An optical port 214 is also provided for inputting and outputting OCT scanning light to the OCT scanner adapter 206. An optical fiber 308a is connected to the optical port 214 to transmit the OCT light from the Figure 1 The OCT scanning system 100 is shown with the coupler 104 being fed via the fiber optic connector 308 to Figure 3A The returned OCT light propagates back along the original path via the optical fiber 308a to the optical block 310 of the scanning mirror assembly shown in FIG. Figure 1 The coupler 104 is shown in FIG. Thus, the optical fiber 308a is Figure 1 The optical path 105a shown in the OCT scanning system 100 is a part of the optical path 105a, through which the OCT detection light illuminates the sample to be scanned, and the OCT light returned from the sample travels through the optical path to the sample. Figure 1 The coupler 104 output of the OCT scanning system 100 is shown in FIG. The optical fiber 308a has a suitable numerical aperture, preferably 0.14, to allow the OCT light in the near infrared region to propagate along its single mode.

[0131] The OCT light from the OCT light source 102 passes through the illumination arm 101 along the optical path 101a to the coupler 104, and then passes through the optical path 101a to the coupler 104. Figure 1The optical path 105a of the detection arm 105 in the MEMS scanning mirror assembly is propagated, wherein the optical fiber 308a constitutes a part of the optical path 105a. The OCT light along the optical fiber 308a is injected into the scanning mirror assembly optical block 310 through the OCT data connection optical fiber connector 308, and then along the OCT arm 518 (see FIG. Figure 5A )spread.

[0132] In some embodiments, the fiber optic connector 308 used to input OCT light to the MEMS mirror block 310 is a fiber optic connector to an angle polished connector.

[0133] The optical block that houses the MEMS scanning mirror assembly 310 also houses the optical components of the optical angular displacement mirror position measurement system 156 for the scanning mirror assembly, such as Figure 1 Shown is a mirror position measurement system 156. Controller 162 (see Figure 1 , Figure 3A (not shown) for adjusting the mirror movement mechanism (not shown) using the MEMS scanning mirror assembly 310 Figure 1 Controller 164 may be implemented within OCT scanner adapter 206 or provided remotely, in which case control signals may be passed to the mirror mover in MEMS scanning mirror assembly 310 via data port 212 of OCT scanner adapter 206.

[0134] In some embodiments, the same mirror reflective surface 334 in the scanning mirror assembly housed in the optical block 310 reflects both the input OCT beam and the mirror positioning reference beam from different sources (see below for details). Figure 5A However, it will be apparent to one of ordinary skill in the art that separate mirrors mounted on the same tilt axis may be used in other embodiments, as long as such a design does not adversely affect the stack height h2 of the OCT scanner adapter 206.

[0135] The OCT light received via the OCT data connection optical fiber 308 propagates along the optical path 105 a and is reflected in the optical plane at the reflective surface 334 onto an optical plane different from the optical plane where the light source reflected light of the angular displacement mirror measurement system 156 is located.

[0136] The reflected OCT beam then propagates along the optical path through the OCT scanner adapter 206 and exits the adapter 206 via the microscope objective 210 to detect an object of interest, e.g. Figure 1 A tissue sample such as eye tissue in vivo is schematically shown in . Other types of objects of interest may include tissue samples used in ophthalmology and fields such as dermatology, dentistry, angiography, cardiology, and other tissue samples used for disease diagnosis (including cancer).

[0137] The OCT light reflected, backscattered, or otherwise returned from the structure within the tissue sample then travels back along the return path 105a, through the scanning mirror assembly of the optical block 310, and returns along the optical fiber 308a. The returned OCT light then exits the OCT scanner adapter 206 via the optical port 214 and is fed into the OCT system 100, where it is combined with the light returned from the reference arm 103 at the coupler 104 and interferes. Figure 1 In the OCT system 100 , the resulting interference pattern is detected by the spectrometer 136 , which generates image data, and then a tomographic image is obtained through image processing, indicating the scanned structures in the tissue located within the scanning FoV.

[0138] exist Figure 3A In the illustrated exemplary embodiment of the OCT adapter 206, an OCT probe beam 312 is output from an optical block housing a MEMSOCT scanner mirror assembly 310 and propagates toward a deflecting mirror 316, which lifts the OCT beam minimally from its optical plane toward a beam splitter 318. The beam splitter 318 reflects the incoming OCT beam toward the objective lens assembly 210 of the OCT scanner adapter 206, which also serves as the objective lens for the microscope optics housed in the microscope 200 when the OCT scanner adapter 216 is attached to the microscope 200. The OCT probe beam is focused from the objective lens 210 as a telecentric beam onto the focal plane 154 in the tissue being scanned, as shown in FIG. Figure 1 The focal plane is shown schematically in the xy plane. The resulting returned OCT light can be used to generate an OCTA scan that provides depth information orthogonal to the focal plane 154, i.e., Figure 1 The z-direction is shown. Movement of the mirror surface 334 causes the telecentric beam to move on the focal plane 154 in the scanned area 116, thereby generating an OCTB scan image.

[0139] exist Figure 3A , the OCT scanner adapter 206 is configured so that the objective 210 can be used as the objective of the microscope optics as well as the OCT scanner system 100. A light-tight gasket 320 is provided around an aperture formed in the OCT scanner adapter 206 through which the OCT objective 210 is aligned with and extends through an optical channel formed by the microscope optics of the microscope 200.

[0140] The configuration of the deflecting mirror 316, beam splitter 318, and objective lens assembly 210 of the OCT scanner adapter 206 is cooperatively designed so that the OCT beam deviates from the plane along which it passes through the scanning mirror assembly by only a slight amount of lift so that it can be emitted through the objective lens 210. The required lift is affected by the tilt angles of the beam splitter and deflecting mirror, as well as the beam incidence geometry. By using this optical design, the additional height h2 that the OCT scanner adapter 206 adds to the height of the microscope is also minimized. For example, in some embodiments, the OCT scanner adapter housing 302 adds 40 mm or less to the overall height h1 of the microscope housing 202. In some embodiments, the additional height h2 is 36 mm or less. In some embodiments, by adopting appropriate beam splitter and deflecting mirror tilt angles, a lift of 27 mm or approximately 27 mm can be achieved.

[0141] In some embodiments, as Figure 3A As shown in the example embodiment of the adapter, the OCT probe beam 312 emerges from the optical block housing the scanning mirror assembly and first traverses free space to a focusing lens assembly 314, which allows adjustment of the focal plane of the scanned image. This allows adjustment of the focus at different depths. The focusing lens assembly 314 is driven by a motor 326 and also includes a travel limiter or stop 324. In some embodiments, the focusing mechanism provided by the adapter's focusing lens assembly 314 can be adjusted to control the OCT focal plane within a ±30 mm range, allowing focus to be applied to a range of depths within the sample for scanning. The OCT focal plane can be adjusted within a ±30 mm range and can be optimized during initial image acquisition for optimal signal-to-noise ratio (SNR). This is distinct from, and should not be confused with, the technique of moving the focus at the A-scan rate to extend the depth of focus within the sample. Movement of the focusing lens assembly 314 is slower than that required for A-scan acquisition and is not adjusted without user intervention unless the system detects significant movement in the sample.

[0142] In some embodiments, as Figure 3AAs shown, the OCT scanner adapter 206 is attached to the microscope 200 using fasteners (e.g., screws) provided in recesses in the mounts 328a and 328b and extending from the mounts 328a and 328b into the base of the microscope 200, into corresponding receiving holes or apertures, preferably threaded holes, in the base of the microscope 200, to securely engage the OCT scanner adapter 206 with the microscope. In some embodiments where the OCT scanner adapter 206 is used as a microscope accessory, the base of the OCT scanner adapter 106 may also include receiving holes or apertures at locations corresponding to the receiving holes or apertures in the base of the microscope 200. By having the same or similar fastening locations in the base of the OCT scanner adapter microscope accessory 206 as the microscope base, different types of microscope accessories that would otherwise attach to the base of the microscope 200 can be attached to the base of the OCT adapter. In other words, in some embodiments, the OCT scanner adapter 206 is configured to attach to the base of the microscope as a microscope optical accessory. Some embodiments of the OCT scanner adapter microscope attachment 206 allow the OCT scanner adapter attachment 206 to have another microscope attachment attached to the base of the OCT scanner adapter.

[0143] Figure 3B Shown Figure 3A Another view of the OCT scanner adapter 206. However, in Figure 3B middle, Figure 4 The positions of the light source or emitter 158 for illuminating the mirror positioning beam 400 of the scanning mirror and the position of the position sensitive detector (PSD) 160 of the optical angular displacement measurement system 156 in the optical block 310 are shown more clearly.

[0144] Figure 3B It is also schematically shown in Figure 4 , an example of an incident angle θ of a mirror positioning illumination beam 400 at the reflective surface 334 of the MEMS scanning mirror, which forms a mirror positioning reference beam traveling toward the PSD 160 after reflection.

[0145] It should be understood that the angles of incidence and positions of beam paths shown in the drawings are for illustration purposes only and are not drawn to scale.

[0146] The design of the MEMS scanning mirror assembly is configured so that Figure 4The illumination mirror positioning beam 400 shown in FIG is reflected at a different optical plane by the reflective surface 334 of the scanning mirror to form a reference beam 402, which is transmitted along the optical plane of the positioning reference arm of the OCT scanning mirror assembly 310 to reflect the incident OCT scanning or detection beam 312 from the reflective surface 334, as shown in FIG. Figure 4 and 5A The scanning mirror assembly is further configured so that the returned positioning light is reflected by the mirror to another optical plane that is different from the reflection optical plane of the outgoing and returned OCT beams and the optical plane on which the incident mirror positioning beam is reflected, thereby minimizing interference of the positioning light on the light source of the OCT beam or the incident mirror positioning beam or the mirror positioning beam.

[0147] In the attached figure Figure 4 Schematically shows Figure 3A and 3B An enlarged view of the OCT scanner adapter 206. Figure 4 , the mirror position illumination beam 400 (shown as a dashed line) from the point light source 158 is incident on the reflective surface 334 of the OCT scanning mirror 500 at an angle of incidence (AOI) shown as θ, as shown in FIG. Figure 5A As shown. The mirror position reflects the light beam 402 (as Figure 4 For clarity, the return light of the incident light beam at PSD 160 is not shown in FIG. Figure 4 Shown in.

[0148] Figures 3A to 4 The illustrated OCT scanner optical assembly is arranged so that the OCT light emerging from the optical plane of the scanning mirror assembly is only slightly lifted from the optical plane by the deflecting mirror 316 toward the beam splitter 318. The beam splitter 318 allows the light to be transmitted through and back to the microscope optics while also reflecting the OCT probe beam to the same focal plane 154 as the microscope light. By optimally positioning the beam splitter and deflecting mirror relative to the objective 210, the height to which the OCT probe beam must be lifted by the deflecting mirror before being reflected by the beam splitter 318 and passing through the objective 210 can be reduced.

[0149] In some embodiments, the deflecting mirror elevates the OCT beam by 27 mm from the optical plane of the scanning mirror assembly.

[0150] Example of optical design of a scanning mirror assembly

[0151] In the attached figure Figure 5A An example of an optical design of a two-dimensional (2D) scanning mirror assembly is schematically shown, for example, as Figure 3A 、 3BThe two-dimensional scanning mirror assembly shown in Figures 4 and 5 is housed in the optical block 310.

[0152] The optical design of the 2D scanning mirror assembly is suitable for other types of OCT scanners, such as Figure 1 The OCT scanner 164 and the OCT scanner adapter 206 are included. Figure 5A The illustrated scanning mirror assembly 310 has an optical design that can be used for applications other than OCT that use scanned light that requires mirror positioning.

[0153] in other words, Figure 5A The 2D scanning mirror assembly optical design need not be limited to OCT applications or devices, such as those in the accompanying drawings in all of its embodiments. Figure 1-4 It can be advantageously implemented in any other type of optical scanning device where compact transverse optical planes are beneficial.

[0154] Figure 5A Some example embodiments of the micro-electromechanical system (MEMS) two-dimensional scanning mirror assembly 310 shown have an optical design that includes a movable MEMS scanning mirror having a reflective surface 334, and a connector 308 for connecting to a point light source to generate a scanning light beam. For example, as shown, an optical fiber 308a is connected via the optical fiber connector 308, and its end (see Figure 5b) acts as a point light source of the light beam.

[0155] The scanning mirror assembly optics also includes a collimating lens assembly 516 for introducing light via the connector 308. The collimating lens assembly 516 is configured to direct the exit beam from the point light source to a reflective surface suitable for the desired scanning application at an exit beam diameter greater than a threshold exit beam diameter. After being reflected at the reflective surface 334 of the scanning mirror 112, the scanning beam exits the scanning mirror assembly via the objective lens assemblies 510 and 512.

[0156] The reflective surface 334 is configured to reflect an incident collimated light beam to form a scanning light beam, for example, an OCT probe beam if a point light source provides OCT light, which exits the mirror assembly as a telecentric light beam 312 via the objective lens 510 and the field lens 512 (collectively referred to as the objective lens assembly 510, 512) and heads toward the telecentric image plane 154. The optical design of the components in the scanning mirror assembly is configured to ensure that the scanning light beam can perform scanning at a resolution better than a resolution threshold.

[0157] The optical device of the scanning mirror assembly is configured to provide a scanning mirror from a point light source (such as an optical fiber or an optical fiber connector end face (see also Figure 5B)) to the telecentric image plane (700) is less than about 40 mm to help keep the scanning mirror assembly lateral dimension X small enough to allow the OCT scanner housing 308 to be designed below the required lateral footprint. For example, as shown in FIG5 , the scanning mirror assembly width X is preferably less than 41 mm, for example, in some embodiments it can be 40.6 mm or less. The optical design is also configured to maintain Figure 5A The depth Y shown in FIG is as small as possible, for example, Y can be 35 mm or less, and in some optical designs may be as short as 34.5 mm or less.

[0158] Therefore, in some embodiments, the total track length L is maintained as short as the optical design layout allows to reduce the lateral and depth footprints X and Y to the minimum possible, so that the housing of the scanner including the scanning mirror assembly 310 can also have a similarly small footprint.

[0159] By keeping the lateral footprint X as small as possible, lateral access to the area being scanned is improved, which is particularly beneficial when the scanning mirror assembly 310 is a scanning mirror assembly for an OCT scanner adapter 206 (the OCT scanner adapter 206 is an attachment for a surgical microscope) because it can improve access to the surgical operating area when using the microscope to which it is attached.

[0160] In some embodiments of the scanning mirror assembly, the threshold exit beam diameter from the collimating lens 516 is at least 3 mm, preferably at least 3.1 mm. By having an exit beam diameter of at least 3.1 mm, the scanner benefits from better lateral resolution than a smaller exit beam diameter would allow.

[0161] In some embodiments of the scanning mirror assembly, the threshold of the telecentric beam resolution is better than 6 microns at the telecentric imaging plane 700. In other words, the scanned image can resolve features smaller than 6 microns in the scanned sample.

[0162] In some embodiments, the scanning mirror 112 can be moved, for example, by the controller 162. In some implementations, the scanning mirror assembly can be configured to move about its optical axis and, in some embodiments, have a scanning range of + / - 5 degrees.

[0163] In some embodiments of the scanning mirror assembly, the numerical aperture of the optical fiber and the focal length of the collimating lens together determine a suitable threshold value for the diameter of the collimated light beam exiting the collimating lens of at least 3.1 mm to achieve the designed resolution at the focal plane. The combination of the focal lengths of the scanning mirror objective and the scanning mirror field lens determines the total path length L through which the probe beam exits the mirror assembly, and this path length L is preferably less than or approximately 40 mm.

[0164] In some embodiments, such as when the scanning mirror assembly is used for OCT purposes, the optical fiber has a numerical aperture of 0.14. In other embodiments of the scanning mirror assembly, the optical fiber that acts as a point light source to feed light to the scanning mirror assembly may have another suitable numerical aperture value, as long as the numerical aperture allows sufficient light to be fed to the scanning mirror assembly along the single-mode optical fiber 308a for another use environment.

[0165] In some embodiments of the scanning mirror assembly, the objective lens 510 comprises an F2.7 bi-convex doublet lens, and the field lens 512 comprises an F19 positive / negative meniscus doublet field lens.

[0166] In some embodiments of the scanning mirror assembly, an optical path difference (OPD) of a telecentric probe beam output by the scanning mirror assembly has a radius of curvature greater than 100 mm.

[0167] In some embodiments of the scanning mirror assembly, the telecentricity of the telecentric beam is better than an angle of incidence of 0.03 degrees relative to the telecentric imaging plane.

[0168] In some embodiments of the MEMS scanning mirror assembly, the reflective surface 334 of the MEMS scanning mirror comprises a large aperture gold-coated silicon mirror bonded to the underlying mechanical structure.

[0169] Figure 5A The embodiment of the scanning mirror assembly 310 design schematically shown in FIG can be implemented as an OCT scanning system (eg, Figure 1 For example, in some embodiments, the scanning mirror assembly is implemented as an optical block having Figure 5A The optical block with the X, Y footprint shown in FIG is used in a compact OCT scanner adapter 206 for a microscope, for example Figure 3A , 3 and 4 show the optical block of the scanning mirror assembly 310.

[0170] However, as mentioned above, Figure 5A and 5B The scanning mirror assembly 310 shown in FIG has an optical design that can be used in a variety of different usage environments in other types of scanner systems. In some embodiments, Figure 5A and 5B The reflector assembly shown in FIG is provided as Figures 3A to 3B The scanning mirror assembly of the OCT device shown in FIG. 3 and receiving the light injected by the optical fiber 308a. In other embodiments, a different point light source can be used instead of the optical fiber 308a serving as the point light source of the OCT beam, such as Figure 3A 、 3B , 4, 5A and 5B.

[0171] In some embodiments, the mirror assembly 310 can be provided in an OCT scanner adapter 206 that functions as an OCT scanning attachment for the microscope 200. In some embodiments, the microscope can include a surgical microscope, and the mirror assembly 310 can be used to generate OCT scans of a sample tissue region undergoing a surgical procedure at a sufficiently high rate to allow real-time OCT tomographic imaging of the sample tissue region to be generated while the surgical procedure is being performed.

[0172] In some embodiments, Figure 1 The SD-OCT scanning system shown in FIG includes an OCT scanner adapter 206 including scanning mirror assemblies 112 and 310, the optical design of which is as follows: Figure 5A and 5B As shown in and described herein.

[0173] In some embodiments, the scanning mirror assembly 310 is configured such that the OCT light returning from the sample along the OCT detection arm 105 has a lateral optical resolution equal to or better than 6 microns, ie, a resolution better than 166 line pairs per millimeter.

[0174] In some embodiments, the scanning mirror assembly 310 comprises a MEMS 2D scanning mirror assembly comprising at least: a movable MEMS scanning mirror having a reflective surface 334; an optical fiber 308a connected via an optical fiber connector 308 and configured as a point light source for illuminating an OCT beam toward the reflective surface 334; and a collimating lens assembly 516 configured to output OCT light having an output beam diameter of at least 3.1 mm from the point light source toward the reflective surface 334. The reflective surface 334 is configured to reflect the incident collimated OCT beam to form an OCT probe beam and a reflector positioning reference beam. The OCT probe beam is emitted from the mirror assembly as a telecentric beam toward a telecentric image plane with a resolution of up to 6 microns. The optical components of the scanning mirror assembly 310 are configured to provide a total path length L from a) the end face of an optical fiber plug inserted into the optical fiber connector providing the point light source to b) the telecentric imaging plane, wherein the total path length L is less than 40 mm, and in some embodiments, preferably less than 36 mm. In some embodiments, objective lens assemblies 510 , 512 are provided in the detection arm of the scanning mirror assembly to focus the telecentric OCT beam via the OCT scanner (microscope) lens 114 , 210 .

[0175] The scanning mirror assembly 310 has an optical design that includes a reflective surface 334 of the MEMS mirror that is configured so that the incident mirror positioning beam is reflected to an optical plane that is different from the optical plane from which the incident OCT scanning beam is reflected. In this way, the scanning mirror assembly can also be used with Figure 1The schematically shown angle tilt mirror positioning system is used in conjunction with other mirror positioning systems.

[0176] As mentioned above, Figure 5A and 5B Some embodiments of the MEMS-based scanning mirror assembly shown in and described herein are implemented as Figure 3A 、 3B and the OCT scanner 206 shown in FIG. Figure 1 Thus, some embodiments of the disclosed technology include an OCT scanner system 100 that includes an OCT scanner 206 that includes a micro-electromechanical system (MEMS) two-dimensional scanning mirror assembly 310 having a compact optical design according to the disclosed technology.

[0177] In some embodiments of the MEMS scanning mirror assembly 310, the scanning mirror 112 is mounted on an underlying mechanical structure or support 500, such as Figure 5A As shown in , this structure provides a mirror movement mechanism to allow the mirror surface 334 to pivot about its optical axis under the control of the controller 162.

[0178] In some embodiments, the reflective surface 334 of the MEMS scanning mirror assembly comprises a large aperture gold-coated silicon mirror bonded to the underlying mechanical structure 500 .

[0179] Figure 1 The angular displacement measurement system 156 shown is Figure 5A In an embodiment of the MEMS mirror assembly, the light source 158 is implemented, and the light source 158 includes a suitable optical point light source, such as a laser diode 502. The optical point light source generates a light beam, referred to herein as the mirror positioning beam 400 (e.g., Figure 5A The light beam passes through the collimating lens 503, so that the collimated mirror positioning light beam 400 is incident on the scanning mirror surface 334 at an incident angle θ.

[0180] Angular displacement measurement system 156 is used to determine the angular position of MEMS scanning mirror assembly 310 relative to the incident mirror positioning beam 400, as this allows the mirror position of the incident beam to be determined while a scan is being performed and adjusted as the scan proceeds. An OCT scan (e.g., a B-scan or volume scan) is performed using controller 164 to move the mirror according to any scan parameters of a particular scan configuration (in some embodiments, these parameters may be user input and / or automatically determined for a particular type of scan).

[0181] In some embodiments, the position of the movable MEMS mirror surface 334 can be controlled in a closed loop based on feedback from the position sensitive detector 160 using a suitable angular position controller ( Figure 5AThe position sensitive detector 160 detects the reflector positioning beam 402.

[0182] In some embodiments, the above reference Figure 3A 、 3B , 4, 5A and 5B include a position sensitive detector 160 that is configured to send feedback mirror position data to a controller 162 when performing a scan, and the controller 162 is configured to control the position of the MEMS scanning mirror surface. However, in some embodiments of the compact OCT scanning mirror assembly 310 shown in the figure, the controller is remotely deployed. For example, in some embodiments, it can be housed elsewhere within the OCT scanner adapter 206. Alternatively, in some embodiments, it can be housed or deployed on a different platform with a user interface along with other system components of the OCT scanner system 100 to allow input of scanning parameters. In some embodiments, the control signal can be sent from the remote control 162 via a suitable data connection (such as the data port 212).

[0183] In some embodiments, the mirror positioning light source illuminates the reflective surface of the mirror assembly at an incident angle θ that is greater than 62 degrees, preferably 67.5 degrees, relative to the plane of the normal to the reflective mirror surface 334 to provide an optical mirror position feedback channel.

[0184] In some embodiments, the OCT light source illuminates the reflective surface of the mirror assembly at an incident angle θ to provide an OCT light channel, and the incident angle θ is less than 28 degrees relative to the normal line of the plane of the reflective mirror surface 334, preferably 22.5 degrees.

[0185] In some embodiments, the minimum available aperture at the mirror surface is at least 4 mm, which is particularly useful when the mirror assembly is incorporated into an OCT scanner device, such as a compact OCT scanner 206 microscope attachment for surgical applications.

[0186] In some embodiments of the disclosed technology, an OCT device may use closed-loop feedback to control the position of a scanning mirror. The use of closed-loop feedback may be useful in embodiments where a high scan rate is required (e.g., where a real-time video or other form of image sequence of an OCT scan is required). The use of closed-loop feedback supports the generation of OCT scans at a high rate and low latency for time-sensitive applications, such as when providing OCT scans to guide surgical procedures, because it allows the mirror to be moved quickly enough and accurately enough to achieve high scan rates and / or high scan resolution (i.e., high OCT image B-scan or volume scan resolution). However, in some embodiments, open-loop control may be provided.

[0187] The disclosed technology is intended to address at least some of the design constraints that exist when designing an OCT system for a surgical microscope. For example, one design constraint is that a smaller diameter scanning mirror surface is better suited to achieve higher scan rates. Numerical aperture is related to resolution. The clear aperture (i.e., mirror diameter) is related to the scan size, because the underlying mechanical structure of the MEMS is the same, so a small diameter mirror (such as a 2mm diameter) can achieve a larger tilt (up to + / - 7 degrees) before hitting the MEMS base, while a large diameter mirror (such as a 7.5mm diameter) can only tilt + / - 1.5 degrees before hitting the base. This means that although a smaller diameter mirror can be used to scan a larger area, it will be at the expense of resolution.

[0188] In some embodiments, the threshold value of the exit beam diameter of the OCT beam is based on the numerical aperture of the optical fiber and the focal length of the collimating lens assembly.

[0189] In some embodiments, the two-dimensional scanning mirror assembly is configured to reflect a mirror positioning beam (400) incident in a first optical plane at a reflective surface (334) to a position sensitive detector (160) configured to generate information about a tilt angle of the scanning mirror reflective surface (344).

[0190] In some embodiments of the optical angular displacement measurement system 156 of the scanning mirror assembly 310 shown in FIG5 , the mirror positioning light from the light source 158 is first collimated by a suitable collimating lens assembly 503 to form a collimated illumination beam 400 that is incident on the mirror surface 334. Figure 3B 、 4 and 5A) is then incident on the reflective MEMS mirror surface 334 with AOI = θ and is reflected to form a mirror position reference beam 402 (at Figure 3B 、 4 5A by the longer dashed line), the reference beam 402 travels along the mirror positioning reference arm 501 of the scanning mirror assembly through the PSD lens assembly 504 and, in some embodiments, through an optional neutral density filter 506 to ultimately reach the PSD 160.

[0191] However, the mirror positioning beam 400 may be reflected by the PSD 160 or otherwise returned to the reflective surface 334 of the MEMS mirror (the reflected beam is not reflected in the mirror). Figure 5A). This is undesirable because this returned light can contaminate the illumination positioning beam and / or the input OCT beam. Other issues associated with stray light reflections in mirror position detector systems include: if any stray light hits the PSD 160, the detected spot position will be in error, and if reflected light enters the diode cavity, the diode's behavior may change, which can cause intensity fluctuations in the position detector beam, which the PSD detects as position changes.

[0192] Some embodiments of the disclosed technology include additional components such as light traps to prevent the returning reflective element of the positioning beam from being reflected by the MEMS mirror assembly 310. The light traps are appropriately configured and positioned to reduce the chance that any reflected mirror positioning reference beam will re-enter the emitter of the mirror positioning beam and / or contaminate the probe beam 312 before it reaches the interferometer.

[0193] As mentioned above, Figure 5A and 5B In some embodiments of the MEMS-based scanning mirror assembly shown in , the reflective surface is designed so that the OCT light input via the OCT optical coupler 308 is reflected from another area of ​​the MEMS mirror surface 334, and so that the mirror positioning reference beam 402 and the OCT scanning or probe beam are reflected in different optical planes.

[0194] The OCT scanning or detection beam reflected by the MEMS mirror surface 334 of the scanning mirror assembly 310 passes through the OCT objective lens 510 and the OCT field lens assembly 512 along the optical path after reflection, is output to the free space in the form of a telecentric beam, and propagates toward the deflecting mirror 316. Figure 3A 、 3B As shown in the embodiment of FIG4 , the beam passes through the focusing lens assembly 314 before being incident on the deflecting mirror 318, which elevates the beam out of the optical plane of the scanning mirror assembly. In some embodiments, this allows the OCT focal plane to be focused within a range of + / - 30 mm, i.e., a range of different depths within the scanning area can be focused. However, in some embodiments of the OCT scanner, the focusing lens optics can be omitted.

[0195] The deflecting mirror 316 elevates the incident OCT scanning (or probe) beam from its optical path plane, which passes through the scanning mirror assembly, by reflecting the incident OCT scanning (or probe) beam toward the beam splitter 318. The beam splitter reflects the OCT scanning or probe beam from the microscope objective 210 of the OCT scanner adapter 206 toward the focal plane 154 for scanning tissue or a similar object of interest, which can be an in vivo tissue sample or an in vitro sample. The beam splitter 318 also allows the scanned area illuminated by the OCT to be observed via the microscope optics housed in the microscope 200.

[0196] In some embodiments, as Figure 3A and 3B As shown, the OCT probe beam 312 is input to the optics block by traveling along the optical path 105a within the optical fiber 308a and enters the scanning mirror optics block 310 via the OCT data connection optical fiber input 308. The OCT scanning or probe beam 520 is then passed through the collimating lens 516 toward the scanning mirror reflective surface 334. The mirror surface 334 reflects the OCT beam out of the optics block containing the scanning mirror assembly 310 via the probe arm 508, at which point the OCT beam travels in free space toward the deflecting mirror 316.

[0197] like Figure 3A 、 3B As shown in the embodiment of the OCT adapter shown in Figures 4 and 5, the OCT scanning or probe beam 312 is focused by a focusing lens assembly 314 before reaching a deflecting mirror 316. The focusing lens assembly is driven by a motor 336, which adjusts the position of the focusing optics to allow a range of depths of focus to be achieved when performing a scan. In some embodiments, the focus range can be varied by + / - 30 mm.

[0198] The returned OCT light is reflected back along the OCT arm 518 of the scanning mirror assembly 310 via the MEMS scanning mirror surface 334. Figure 1 The coupler of the OCT system 100 is shown.

[0199] In the scanning mirror assembly 310, the input OCT beam is input from the end face 532 of the optical fiber 308a via the optical fiber connector 308, passes through the optical fiber connector 530 (see also Figure 5B ), through the OCT collimating lens 516 toward the scanning mirror assembly. The track length, i.e., the measurable physical distance of the path from the end face 532 to the surface of the scanning mirror, is Figure 5A and 5B L1 shown.

[0200] Figure 5A Also shown is the track length L2 from the scanning mirror surface to the telecentric imaging plane 700. The total track length L = L1 and L2, preferably less than or equal to the track length design threshold of 40 mm.

[0201] Figure 5B yes Figure 5A The enlarged view of FIG3 more clearly shows the position of the fiber connector 532 and the fiber end face 530, at which the optical fiber 308a, acting as a point light source, injects OCT light into the mirror scanning system 310. The OCT light enters the collimating lens 516 from the fiber end face 532, and the collimated illumination OCT beam is then incident on the reflective surface 334 of the MEMS scanning mirror and reflected to the OCT detection arm 105 (as shown in FIG3). Figure 1 as shown) or 508 (as shown) Figure 5A shown).

[0202] In the return direction (for clarity, Figure 5A or not shown in 5B), the returned OCT light travels along the OCT arm 518 (see also Figure 6 ) and propagates in the other direction through the collimating lens 516, then propagates along the optical fiber 308a via the OCT data connection optical fiber 308, and finally leaves the OCT scanner adapter 206 via the optical port 214.

[0203] In some embodiments, the OCT scanner is implemented using an off-the-shelf (OTS) MEMS (micro-electro-mechanical system), where the MEMS scanning mirror reflective surface 334 is provided by a large-aperture protected gold-coated silicon mirror bonded to the underlying mechanical structure 500 of the optical block 310. The OCT scanner 206 formed by this design provides a simplified and miniaturized optical system with optical performance comparable to larger galvanometer-type systems known in the art for intraoperative OCT systems.

[0204] In some embodiments, the optical block design of the OCT MEMS mirror assembly 310 includes a 2D scanning mirror assembly and a complementary optical angular displacement measurement system 156 for measuring the position of the MEMS mirror system.

[0205] The mirror positioning system for measuring the angular displacement of the scanning mirror reflective surface 334 includes a mirror positioning light source 158 and a position sensitive detector (PSD) 160. The PSD may include a PSD lens assembly 504 and a neutral density filter 506 as well as the PSD 160. An example of a suitable PSD detector is the Hamamastu S599 14 mm x 4 mm active area position sensitive detector.

[0206] In some embodiments, the angular optical displacement measurement system 156 is provided in the same optical block as the MEMS scanning mirror assembly 310. In some embodiments, the optical angular displacement measurement system 156 is used to provide closed-loop control of the position of the MEMS scanning mirror. The closed-loop control can be achieved by using the PSD 160 to measure the incident angle θ and providing the resulting mirror position information to the controller, thereby enabling the controller to more accurately control the tilt angle of the scanning mirror reflective surface 334 during scanning.

[0207] This closed-loop feedback can achieve extremely high B-scan rates. For example, for a 4.2 mm diameter clear aperture mirror 112, closed-loop control can achieve a maximum scan rate of at least 400 B-scans per second at full angular deflection within the maximum field of view (FoV).

[0208] In embodiments without closed-loop control (i.e., open-loop scanning), a low-pass filter can be used to prevent the MEMS scanning mirror movement device from reaching its natural frequency excitation state, in which the MEMS scanning mirror movement device may resonate due to uncontrolled oscillations (which in turn may damage the MEMS scanning mirror movement device). In embodiments implementing open-loop scanning, the maximum scan rate can be approximately 50 B-scans per second, which can be compared to the rate achievable with closed-loop control. In some embodiments, with closed-loop control, the scan rate achievable using an example embodiment of the MEMS scanning mirror assembly 310 according to the disclosed technology is approximately 400 Hz or higher.

[0209] In some embodiments, the optical components of the MEMS scanning mirror assembly 310 are cooperatively configured to provide a predetermined system numerical aperture through the microscope objective 210 to achieve a desired system optical resolution. That is, in some embodiments, the MEMS scanning mirror system components are appropriately configured so that the diameter of the collimated OCT beam 312 output along the OCT data connection optical fiber 308 after passing through the microscope objective 210 matches the desired minimum system optical resolution.

[0210] In some embodiments, all air-glass interfaces within the OCT scanner adapter 206 are designed to be convex to minimize any back reflections of the OCT beam as it propagates through the optical system.

[0211] Figure 6 An example embodiment of an OCT collimating lens, also referred to herein as an OCT collimating lens assembly 516, is shown, such as the collimating lens 516 shown in the OCT arm 518 of the optical block (including the scanning mirror assembly 310) shown in Figure 5. The OCT collimating lens 516 is provided along the OCT arm 518 of the scanning mirror assembly optical block 310. Figure 6 In FIG, the OCT light fed into the collimating lens assembly 602 through the fiber connector end 532 is emitted as a collimated OCT output beam 604 having a collimated beam diameter of at least 3.1 mm. The collimated OCT beam then travels toward and is reflected from the scanning mirror reflective surface 334. The returned OCT light travels along the opposite path through the scanning mirror assembly and is focused by the collimated beam to the end of the optical fiber 308a, which collects the returned light. The returned OCT light can then be propagated back to the interferometer system (e.g., Figure 1 The coupler 104 of the OCT system 100 is shown.

[0212] A suitable example of an OCT collimating lens 516 suitable for use in some embodiments of the disclosed technology is an F3.2 biconvex doublet lens. This lens has a thick crown glass portion, which reduces the radius of curvature of the lens surface, thereby improving color performance. In some example embodiments, the collimating lens has a focal length of 10 mm and a depth of focus of 100 microns, which ensures good mechanical focus stability. In some embodiments, the OCT collimating lens provides an exit beam having a collimated beam diameter of 3.1 mm (exit pupil diameter) with a wavefront error of less than 1 / 4 wave (root mean square, rms).

[0213] Figure 7 Examples of OCT objective lens assemblies 510, 512 are shown where the OCT beam 312 includes light 312a within a wavelength range, such as a wavelength range in the near infrared portion of the spectrum.

[0214] After being reflected from the reflective surface 334 of the scanning mirror assembly, the OCT light is first focused by the OCT objective lens 510 and then by the field lens 512 , and finally emerges as a telecentric beam 312 b . Figure 7 FIG. 3 shows multiple angularly related telecentric beams 312b focused on a telecentric imaging plane 700. 1,2,3 , where each beam 312b 1,2,3 It indicates the position where the OCT beam 312b is emitted at a specific scanning angle. In other words, the telecentric emitted beams 312b1, 312b2, and 312b3 are continuous beams generated as the B scan proceeds.

[0215] After being deflected from the mirror surface (in other words), the OCT beam 312 passes through the OCT objective lens assembly 510 (which in some embodiments also includes a field lens 512), which is designed so that all scanning angles (in the range of Figure 7 The OCT output light beams 312b1, 312b2, 312b3) schematically shown in the figure are all emitted perpendicular to the intermediate imaging plane and are therefore telecentric.

[0216] In some embodiments, all air-to-glass interface surfaces (e.g., 514) are convex to eliminate back reflection artifacts in OCT images. Figure 7 The OCT objective lens assembly shown converts the reflected angular input OCT scanning or probe beam 312a from the MEMS scanning mirror surface 334 into a telecentric OCT scanning or probe beam 312b (or more precisely, beam 312b). 1,2,3In some embodiments, the telecentric OCT scanning or detection beam 312b is first focused by a focusing lens assembly 314 before being raised by a deflecting mirror 316 toward a beam splitter 318, such as Figure 3A and 3B Alternatively, for example, the telecentric OCT scanning or probe beam 312b can be passed directly in free space to a deflecting mirror 316 and then reflected to a beam splitter 318.

[0217] The focusing lens assembly 314 serves as an optical interface for the telecentric OCT beam 312b to the microscope objective 210. In some embodiments, the scanning mirror assembly can be used without the focusing lens assembly 314, but this would require that the sample be placed on the intermediate imaging plane 700, where the telecentric OCT beam 312b is focused when it exits the scanning mirror assembly. Therefore, in order to use the OCT scanner 206 without the focusing lens assembly, the sample would need to be placed on the intermediate imaging plane 700 in some manner. For example, Figure 3A 、 3B 4, a lens is required to achieve optical coupling with the microscope objective 210. Alternatively, the objective 210 may require a shorter focal length. Such a short focal length is not suitable for surgical applications. However, in some embodiments of the disclosed technology, if the OCT scanner is used for another type of application, the focusing lens assembly 314 may be omitted. For example, an OCT scanner 206 used for eye imaging (particularly animal eye imaging) may not require the focusing lens 314.

[0218] In some exemplary embodiments of the OCT scanner adapter 206 for a surgical microscope, the focusing lens assembly 314 is fixed and positioned at an appropriate back focal length to collimate and expand the incoming telecentric OCT beam 312b to a collimated beam diameter of 10.6 mm upon exiting the focusing lens assembly. When the OCT beam 312 is collimated upon exiting the focusing lens assembly, it is focused at the focal plane of the microscope objective 210, which is identical to the microscope optics.

[0219] Alternatively, the object distance is effectively adjusted by adjusting the position of the focusing lens assembly 314 relative to the intermediate imaging plane. This causes the focus position of the microscope objective 210 to change accordingly to accommodate the OCT scan, while the focus position of the microscope optics remains unchanged.

[0220] In some embodiments of an OCT scanner, such as Figure 3A 、 3B4, a benefit of having a focusing lens assembly 314 is that if the surgeon moves the eye during surgery, the OCT scanning system can use appropriate autofocus techniques known in the art to focus the OCT on the designated anatomical feature.

[0221] Another benefit of an embodiment of the OCT scanner 206 that includes a focusing lens assembly 314 is that the scanner can be used in certain situations even if the user of the microscope 200 (e.g., a surgeon or assistant) has incorrectly set up the microscope optics. For example, if the microscope is non-parfocal, in other words, if the eyepiece of the microscope is set to infinity for a user whose vision is corrected with contact lenses or glasses, the microscope optics will focus on the focal plane of the microscope objective. If the microscope eyepiece is not set to accommodate the refractive error of the microscope user's vision, some users may move the entire microscope (e.g., using Figure 2A 、 2B The microscope optics may be moved to adjust or accommodate for refractive errors in their vision using handles 204a, b as shown. However, such movement of the microscope optics may result in the tissue sample or other object of interest being scanned (e.g., an eye undergoing surgery) no longer being located in the actual focal plane of the microscope objective 210 provided by the OCT scanning system 206. In other words, if the microscope is used improperly, the focus of the OCT beam 312 may need to be adjusted accordingly by a focusing lens assembly (e.g., focusing lens assembly 314) to compensate.

[0222] In some embodiments, Figure 7 The OCT objective lens 510 shown is a F2.7 biconvex doublet lens. The objective lens 510 is coupled to a F19 positive / negative meniscus doublet field lens 512 to convert the scanned collimated OCT beam 312 reflected from the surface 334 of the MEMS scanning mirror into Figure 7 The OCT return beam passes through the OCT field lens, then through the OCT objective lens, and then again through the reflective surface 334 of the MEMS mirror along the OCT output arm 518 and through the OCT collimating lens 516 (see also Figure 5A ) into the interferometer assembly ( Figure 5A Not shown, see Figure 1 SD-OCT system 100).

[0223] In some embodiments, as Figure 5A and 7 As shown in the example embodiment, all air-to-glass interface surfaces, such as surface 514 of the objective lens assembly 510 and the collimating lens 516 for the outgoing OCT beam 312 and the returning OCT beam (not shown), are convex to eliminate back reflection artifacts in the OCT image.

[0224] In some embodiments, the total track length L within the optical block of the scanning mirror assembly is the sum of the length L1 from the end face 530 of the optical fiber 308a at the optical fiber connector 532 to the reflective surface 334 of the scanning mirror and the track length L2 from the surface 334 to the telecentric imaging plane 700, as shown in FIG. Figure 5A The total track length L = L1 + L2 is preferably less than 40 mm.

[0225] In some embodiments, the optical path difference OPD at the scanned sample has an OPD curvature greater than 100 mm.

[0226] In some embodiments, the telecentricity of the OCT scanning or detection beam is better than 0.03 degrees of incident angle.

[0227] In some embodiments, the focusing system 314 provides a mechanism for adjusting the OCT beam 312 so that the OCT focal plane can be controlled within a range of ±30 mm to align with the microscope optical channel focal plane.

[0228] In some embodiments, the MEMSOCT scanner has a transverse XY profile, where X is less than 42 mm and Y is less than 35 mm, such as Figure 5A As schematically shown, this allows the OCT scanner system housing to be laterally adapted to the lateral dimensions of the microscope optics carrier housing profile. This advantageously reduces sterile field obstructions in surgical applications. In some embodiments implementing the optical block of the scanning mirror assembly 310, the optical block has dimensions of: a lateral width X of approximately or equal to 40.6 mm, a depth Y of approximately or equal to 34.5 mm, and a track length L of approximately 40 mm or less.

[0229] In some embodiments, the scanning mirror assembly further includes an optical angular displacement measurement system 156 for determining the tilt angle of the reflective surface relative to the incident light, the system comprising at least: a point light source, a collimating lens assembly for collimating light from the point light source to form a collimating mirror position measurement beam incident on the reflective surface; and a position-sensitive detector, wherein the reflective surface is configured to reflect the incident collimated light beam in a first optical plane to form a reflected position measurement beam traveling toward the position-sensitive detector.

[0230] In some embodiments of the scanning mirror assembly 310 described above, reference is made to the accompanying drawings. Figure 5A and 5B Closed-loop control of the position of the reflective surface of the MEMS mirror is provided by a position-sensitive detector configured to provide angular displacement measurement information to a controller configured to control the tilt angle of the mirror surface relative to the illumination beam. In some embodiments, the closed-loop control uses a PID feedback loop to adjust the drive voltage of the MEMS based on position and also suppresses ringing artifacts caused by rapid changes in orientation.

[0231] Advantageously, in some embodiments, where the scanning mirror assembly includes a scanning mirror assembly 310 in the OCT scanning device 206, the input light beam includes an OCT probe beam 312, which is reflected by the optical assembly along an OCT probe beam arm of the scanning mirror assembly to the sample or similar object of interest 116. The scanning mirror assembly 310 is configured to output the OCT probe beam 312 as a telecentric OCT probe beam to the focal plane 154 at the sample, and the optical path length of the OCT probe beam from the light source 102 to the sample focal plane 154 is configured to be equal to the optical path length of a reference OCT beam from the same OCT light source 112 along the reference arm 103 of the interferometer OCT system 100 connected for performing 2D scanning of the sample area 116.

[0232] In some embodiments, the MEMS scanning mirror assembly 310 disclosed herein is provided as an optical block 310 in an OCT scanner adapter 206 for use with a surgical microscope 200, which forms part of an attached OCT system 100. The lateral footprint X of such an OCT scanner adapter 206 is preferably within or equal to the footprint of the surgical microscope housing, and its length or depth footprint is preferably also within the footprint of the microscope. The OCT system 100 outputs an interferometric signal comprising OCT scan data 146 to an image processor 148 of the OCT system 100. The image processor 148 then processes the interferometric signal 146, for example, by performing a signal transformation such as a Fourier transform, to display an OCT image on a display 152 showing internal scanned structures within the scanned region. In some embodiments, this image can be generated in real time to guide a surgeon and / or other personnel on one or more suitable displays 152.

[0233] In some embodiments of the OCT scanner adapter 206, the OCT scanner adapter 106 is configured to be secured to a base of a housing of a microscope optics of a surgical microscope, wherein the OCT scanner adapter 216 increases the stack height of the surgical microscope by less than 40 mm, preferably less than 36 mm.

[0234] In some embodiments of the OCT scanner adapter 206, the OCT scanner adapter 106 is configured to be secured to the base of the microscope optics housing and to align the objectives 114, 210 of the OCT scanner adapter 206 with the optical pathway of the microscope optics when the lateral footprint of the housing 208 of the OCT scanner adapter 206 is positioned within the lateral footprint of the housing 202 of the surgical microscope 200.

[0235] In this way, a surgical microscope according to the disclosed technology can be provided, e.g. Figure 2A and 2B The surgical microscope 200 shown includes microscope optics, a housing 202 containing the microscope optics, and an OCT scanner adapter 206, wherein the OCT scanner adapter 206 includes a scanning mirror assembly according to the disclosed technology, for example, Figure 5A and 3B The OCT scanner adapter 206 may be configured to output image data that is later input to an OCT system (e.g., Figure 1 in the image processor of the OCT system shown in FIG.

[0236] Therefore, some embodiments of the disclosed micro-electromechanical system (MEMS) two-dimensional scanning mirror assembly (310) include a scanning mirror assembly having an optical design, the optical design including a movable MEMS scanning mirror having a reflective surface 334, a point light source 308a for generating a light beam, a collimating lens assembly 516 configured to receive light from the light source and output a collimated light beam having an output beam diameter greater than a threshold toward the reflective surface 334, and objective lens assemblies 510, 512, wherein the collimated light beam reflected from the reflective surface is emitted from the scanning mirror assembly via the objective lens assemblies 510, 512. The reflective surface 334 is configured to reflect the incident collimated light beam to form a telecentric light beam (312) that is emitted from the mirror assembly and toward a telecentric image plane, and the resolution of the detection light beam 312 is better than the threshold of the telecentric light beam resolution. The optics of the scanning mirror assembly are configured to provide a total track length L from the point source of light to the telecentric imaging plane (700) of less than 40 mm, and the scanning mirror assembly can be provided in an optical block having a width less than or equal to 41 mm, preferably 40.6 mm, and a length less than or equal to 35 mm, preferably 34.5 mm, excluding the fiber optic connector 308 and the MEMS support 500 (see Figure 5A Block dimensions X and Y are shown).

[0237] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the present disclosure. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0238] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items and may be abbreviated as " / ."

[0239] It will also be understood that the terms “comprises,” “including,” “includes,” and / or “comprising,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0240] It should be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of this disclosure.

[0241] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe the relationship of one element to another element as shown in the figures. It should be understood that these terms and those described above are intended to encompass different orientations of the device in addition to the orientation shown in the figures. It should be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements.

[0242] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that the terms used herein should be interpreted as having the same meaning as they have in this specification and the relevant art, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0243] Although some aspects are described in the context of an apparatus, it is clear that these aspects also represent a description of the corresponding method, where the blocks or devices correspond to method steps or features of method steps. Similarly, aspects described in the context of method steps also represent a description of the corresponding blocks or items or features of the corresponding apparatus.

[0244] It should be understood that the present disclosure is not limited to the aspects described above and shown in the accompanying drawings; on the contrary, those skilled in the art will recognize that many changes and modifications are possible within the scope of the present disclosure and the appended claims. In the drawings and the specification, aspects are disclosed for illustrative purposes only and not for limiting purposes, and the scope of the inventive concept is set forth in the appended claims.

Claims

1. A micro-electromechanical system (MEMS) two-dimensional scanning mirror assembly (310), the scanning mirror assembly comprising a scanning mirror optical device having an optical design, the optical design comprising at least: A movable reflective surface (334) of a MEMS scanning mirror, wherein the reflective surface is movable in a two-dimensional plane; a collimating lens assembly (516) configured to receive a scanning beam from a scanning light source (308a) and output a collimated scanning beam toward a reflective surface (334), wherein the collimated scanning beam has an exit beam diameter of the collimating lens assembly (516); an objective lens assembly (510, 512), wherein the collimated scanning light beam reflected from the reflective surface (334) is emitted from the scanning mirror assembly (310) via the objective lens assembly (510, 512), wherein the configuration of the scanning mirror assembly optical device includes a reflective surface (334), the reflective surface (334) being configured to reflect an incident collimated scanning light beam toward the objective lens assembly (510, 512) to form a telecentric scanning light beam (312) that emerges from the mirror assembly and is telecentrically directed toward a telecentric imaging plane (700), wherein the point at which the telecentric scanning light beam is focused in the telecentric imaging plane changes as the reflective surface (334) moves during scanning; and wherein at least the position and size of the scanning mirror optical device within the scanning mirror assembly are configured to minimize a trajectory length L from the light source (308a) to the telecentric imaging plane (700).

2. The MEMS scanning mirror assembly according to claim 1, wherein: The position and dimensions of the scanning mirror optics within the mirror assembly define a track length L from the light source (308a) to the telecentric imaging plane (700), the track length L being less than or equal to 40 mm.

3. The MEMS scanning mirror assembly of claim 1 , wherein the scanning light source ( 308 a ) comprises an optical fiber end face ( 532 ) providing a point light source, and wherein the numerical aperture of the point light source and the focal length of the collimating lens assembly ( 516 ) are configured such that an exit beam diameter of the scanning light beam from the collimating lens is at least 3.1 mm.

4. A MEMS scanning mirror assembly according to any one of the preceding claims, wherein: The telecentric scanning beam resolution at the telecentric imaging plane is better than 6 microns.

5. The MEMS scanning mirror assembly of any preceding claim, wherein the reflective surface (334) is configured to move within + / - 5 degrees of each of two orthogonal axes x, y, which intersect at the optical center of the reflective surface.

6. A MEMS scanning mirror assembly according to any one of the preceding claims, wherein the objective assembly optics comprises an objective lens (510) and a field lens (512), and wherein the total track length L depends on the combined focal length of the objective assembly optics.

7. The MEMS scanning mirror assembly according to claim 6, wherein the objective lens (510) comprises an F2.7 biconvex doublet lens, and the field lens (512) comprises an F19 positive / negative meniscus doublet field lens.

8. The MEMS scanning mirror system according to any one of the preceding claims, wherein an optical path difference (OPD) of each scanning sequence beam output by the scanning mirror assembly (310) to form a telecentric scanning beam has a curvature radius greater than 100 mm.

9. The MEMS scanning mirror system of any one of the preceding claims, wherein the telecentricity of each telecentric scanning beam is better than an angle of incidence of 0.03 degrees relative to the normal to the telecentric imaging plane.

10. The MEMS scanning mirror assembly of any preceding claim, wherein the reflective surface (334) comprises a large aperture gold-coated silicon mirror bonded to an underlying mirror movement mechanism of the MEMS scanning mirror assembly (310).

11. A MEMS scanning mirror assembly according to any one of the preceding claims, wherein the MEMS scanning mirror assembly (310) is provided as an optical block in an optical coherence tomography (OCT) scanner (206), wherein the scanning beam comprises an OCT probe beam (312), and wherein the light source (308a) comprises an optical fiber (308a) having an end face (532) that acts as a point light source for the OCT probe beam (312).

12. The MEMS scanning mirror assembly (310) of any one of claims 10 or 11, wherein the OCT probe beam provides a depth scan of the sample and the OCT light returned from the sample has a lateral optical resolution equal to or higher than 6 microns.

13. The MEMS scanning mirror assembly according to any one of claims 11 to 12, wherein the OCT scanner (206) is provided as an OCT scanner adapter (206) for a surgical microscope (200).

14. A spectral domain optical coherence tomography scanner system (100), comprising an optical interferometer device, the scanner system (00) comprising: A coupler (104) connected to an illumination arm (101) including a light source (102), a scanning depth reference arm (103), a scanning arm (105) and a detection arm (107), The illumination light beam from the light source 102 enters the coupler (104) along the illumination arm (101). The illumination beam is divided into a scanning depth reference beam propagating along a scanning depth reference arm (103) toward a reflective surface (108) and a scanning beam propagating along a scanning arm (105) toward a scanned sample through a coupler (104). wherein the scanning arm (105) comprises a scanning mirror assembly (310) according to any one of claims 1 to 14, and is configured to move a scanning light beam over the sample so that light returned from the sample returns along the scanning arm (105) to the coupler (104), wherein the return light from the scanning arm and the return light from the scanning depth reference arm (103) are guided by the coupler (104) to an interference detector (136) located in the detector arm (107), and the interference detector (136) is configured to detect interference between the return light from the scanning arm and the return light from the scanning depth reference arm (103); and The interference detector (136) is configured to output data including a return light interference signal for image processing to generate a tomographic image of the scanned sample.

15. The SD-OCT scanner system (100) according to claim 14, further comprising an image processor configured to process the received OCT interference signal and output an OCT image for display.

Images