Polygonal scanning mirror mask in ophthalmic imaging instrument

Abstract

The invention relates to a polygon scanning mirror mask in an ophthalmic imaging instrument. An ophthalmic imaging instrument includes: a light source emitting a light beam; the polygonal scanning mirror comprises a plurality of reflecting facets; a driver that rotates the polygon scanning mirror during operation such that each facet reflects a light beam; an optical system that guides the light beam reflected from the polygon scanning mirror toward the fundus through the cornea and that guides the light returned from the fundus toward the polygon scanning mirror; a mask that blocks a portion of the light beam that has been reflected back from at least one of the cornea and an optical element of the optical system to prevent it from reaching the detector; a detector that detects the return light to generate a detection signal; and a pathway to a computing resource arranged to generate an image of the fundus using the detection signal.

Description

Technical Field

[0001] This invention relates to a polygonal scanning mirror in an ophthalmic imaging instrument. More specifically, but not exclusively, this invention relates to a mask arranged to block a portion of a light beam reflected from the polygonal scanning mirror to prevent it from reaching the detector of the polygonal scanning mirror, the portion of which is a light beam already reflected from the cornea of ​​the eye and at least one of the optical elements of the optical system of the ophthalmic imaging instrument. background

[0002] Ophthalmic imaging instruments are widely used to image a patient's eye in order to assess its health. Such instruments typically include a light source and a controller arranged to control the light source to generate a beam with a target optical power. The beam is deflected by one or more scan relay elements to cover the imaging area by means of a typically parallel arrangement of multiple scan lines. The scan relay elements typically include a polygonal scanning mirror and one or more scanning galvanometer mirrors, referred to herein as "galvanometers". The former, the polygonal scanning mirror, comprises multiple reflecting facets arranged along the outer circumference of a rotating body. A actuator is operable to rotate the body of the polygonal scanning mirror such that each facet continuously reflects the incident beam at a varying angle. Thus, during the passage of a single facet, the beam is deflected by a varying angle. After such a deflection cycle is completed, the next facet essentially repeats the process, and so do all other facets.

[0003] This repeated deflection of the beam by the polygonal scanning mirror forms the basis of at least one scanning direction by providing multiple parallel scan lines. Additional scanning elements, such as the galvanometer already mentioned, can then further deflect the beam in another direction to shift the scan lines relative to each other on the target and ultimately cover the two-dimensional scan area. In at least some imaging modalities, light from the scanning beam is scattered back from the target tissue, which, in the case of ophthalmic imaging, primarily comprises parts of the human eye, such as the fundus or retina. Typically, the light thus returns along the incident light path so that it is eventually detected by a detector in the form of a light sensor, converted into an intensity signal, and processed to form an image. Specifically, this subsequent signal processing is achieved by means of computational resources that compile the individual images from the corresponding set of line scans.

[0004] In cases where the target tissue is the fundus of the eye, light from a scanning beam passes through the cornea of ​​the eye. The cornea (e.g., the outer surface of the cornea) can reflect some of the scanning beam toward the detector mirror, thus creating image artifacts in the image. Other image artifacts can be similarly formed by some of the scanning beam reflected back from the mirrors of the optics within an ophthalmic imaging instrument.

[0005] Therefore, it is necessary to suppress or eliminate image artifacts caused by these back reflections of the scanning beam, while keeping the system complexity at an acceptable level. Overview

[0006] According to one embodiment of the present invention, an ophthalmic imaging instrument is provided. The ophthalmic imaging instrument includes a light source, a polygonal scanning mirror, a driver, an optical system, a mask, a detector, and a pathway to computing resources. The light source is arranged to emit a light beam. The polygonal scanning mirror includes a plurality of reflective facets. The driver is arranged to rotate the polygonal scanning mirror during operation such that each facet reflects the light beam at a varying angle. The optical system is arranged to guide the light beam reflected from the polygonal scanning mirror through the cornea of ​​the eye toward the fundus of a subject's eye, and to guide light returning from the fundus toward the polygonal scanning mirror. The mask is arranged to block a portion of the light beam reflected from the polygonal scanning mirror to prevent it from reaching the detector, a portion of which is a portion of the light beam that has been reflected back from at least one of the cornea of ​​the eye and an optical element of the optical system. The detector is arranged to detect the returned light reflected from the polygonal scanning mirror to generate a detection signal. The pathway is a pathway to computing resources arranged to generate an image of the fundus of the eye using the detection signal.

[0007] According to another embodiment of the present invention, a method for operating the above-described ophthalmic imaging instrument is provided. The method includes the following steps: rotating the polygonal scanning mirror by means of a driver such that each facet reflects a light beam; guiding the light beam reflected from the polygonal scanning mirror toward the fundus of a subject's eye by means of an optical system; guiding light returning from the eye toward the polygonal scanning mirror by means of the optical system; blocking a portion of the light beam reflected from the polygonal scanning mirror by means of a mask to prevent it from reaching a detector; generating a detection signal by means of the detector through detecting the returning light; and generating an image of the fundus of the eye using the detection signal by means of a pathway to computing resources. Brief description of the attached diagram

[0008] Embodiments of the invention will now be described with reference to the accompanying drawings, which are presented to better understand the inventive concept but should not be construed as limiting the invention. In the drawings: Figure 1 A schematic diagram of an ophthalmic imaging instrument according to a general device embodiment of the present invention is shown; Figure 2 A schematic diagram of an ophthalmic imaging instrument according to an embodiment of the present invention is shown; Figure 3 An enlarged schematic diagram of a rotating polygonal mirror and a mask according to an embodiment of the device is shown to illustrate certain other aspects thereof; Figure 4A schematic diagram of an ophthalmic imaging instrument, particularly in the context of an example of an optical system, is shown according to an embodiment of the present invention. Figure 5 A flowchart illustrating a general method embodiment of the present invention is shown.

[0009] It should be understood that, unless otherwise stated, some figures are not necessarily shown to scale. In some cases, details that are not essential for understanding this disclosure or that make other details difficult to perceive may have been omitted. Of course, it should be understood that this disclosure is not necessarily limited to the specific examples or embodiments shown or depicted herein. Detailed description

[0010] The inventors have recognized that specular reflections of scanning beams from the cornea and optical elements of an ophthalmic imaging instrument can follow optical paths different from both the scanning beam and the returning light from the eye. Therefore, the inventors have designed a mask that blocks portions of the scanning beam reflected from at least one of the optical elements of the ophthalmic imaging instrument's optical system, preventing it from reaching the detector of the ophthalmic imaging instrument. Thus, the mask can at least partially suppress image artifacts in fundus images that would otherwise be generated by the detection of these back reflections. Therefore, the quality of images generated by the ophthalmic imaging instrument can be significantly improved.

[0011] Example embodiments described herein will now be described with reference to the accompanying drawings.

[0012] Figure 1A schematic diagram of an ophthalmic imaging instrument 102 according to a general device embodiment of the present invention is shown. Specifically, an ophthalmic imaging system 112 is shown, which includes an ophthalmic imaging instrument 102 that provides at least one imaging modality 121, such as autofluorescence (AF), red-green, red-green-blue, and fluorescein angiography. The ophthalmic imaging instrument 102 may be or include a scanning laser ophthalmoscope (SLO) to provide one or more of at least one imaging modality 121, and may include an optical coherence tomography (OCT) device to provide an OCT imaging modality. In some embodiments, the OCT device may share one or more optical components with the SLO, such as the scanning system therein. The ophthalmic imaging system 112 may include or have (e.g., via a wired or wireless connection) access to a computing resource 106, which in turn includes a processing unit 108 and a memory unit 110. Components of an ophthalmic imaging system 112, including an ophthalmic imaging instrument 102 and computing resources 106, can be housed within a common housing, such that the system 112 thereby forms the ophthalmic imaging instrument 102, such as an ophthalmoscope. In this way, the ophthalmic imaging instrument 102 may have access to the computing resources 106, or may include the computing resources 106 itself. In some embodiments, the computing resources 106 may be located within separate housings outside the instrument 102. In some embodiments, any component may be located in a different housing than the others.

[0013] Computational resource 106 is operable to generate an image of the fundus of the eye using detection signals from detectors in ophthalmic imaging instrument 102, as described later, and is operable to control and provide imaging modality 121. The computational resource has at least one processing unit 108, such as a central processing unit (CPU) and / or a graphics processing unit (GPU), and a memory unit 110 storing instructions that, when executed by at least one processing unit 108, cause the processing unit 108 to perform one or more methods and functions described herein. In embodiments of local computational resources or local physical components of a computing device, the resource may include processors (such as CPUs and / or GPUs), system memory, and a system bus coupling the system memory to the CPU / GPU. The system memory may include random access memory (“RAM”) and read-only memory (“ROM”). A basic input / output (“I / O”) system is stored in the ROM, containing basic routines such as those that facilitate the transfer of information between elements within the computing device during startup. The computational resource may also include a mass storage device capable of storing software instructions and data. Mass storage devices can be connected to the CPU / GPU via a mass storage controller connected to the system bus. Mass storage devices and their associated computer-readable data storage media can provide non-volatile, non-transitory storage for computing resource 106. While the description of computer-readable data storage media herein refers to mass storage devices such as hard disks or CD-ROM drives, those skilled in the art will understand that computer-readable data storage media can be any available non-transitory physical device or article of art from which a device can read data and / or instructions. Mass storage devices are examples of computer-readable storage devices.

[0014] Computer-readable data storage media include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable software instructions, data structures, program modules or other data). Examples of computer-readable data storage media include, but are not limited to, RAM, ROM, EPROM, EEPROM, flash memory or other solid-state storage technologies, CD-ROM, digital versatile optical disc (“DVD”), other optical storage media, magnetic tape, magnetic tape, disk storage devices or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible by a computing device.

[0015] Computing resource 106 can operate in a networked environment using a logical connection to remote network devices via a network, such as a local area network, the Internet, or another type of network. Computing resource 106 can be connected to a network via a network interface unit connected to a system bus. The network interface unit can also be connected to other types of networks and remote computing systems. Computing resource 106 includes an input / output controller for receiving and processing input from multiple other devices, including a touch user interface display or another type of input device. Similarly, the input / output controller can provide output to a touch user interface display, a printer, or other types of output devices. As described above, mass storage devices and RAM can store software instructions and data. The software instructions can include an operating system suitable for controlling the operation of computing resource 106. Mass storage devices and / or RAM can also store software instructions that, when executed by a CPU / GPU, cause computing resource 106 to provide the functionality discussed in this document, including the methods described herein and shown in the accompanying drawings.

[0016] In some embodiments utilizing the aforementioned SLO to achieve imaging modality 121, the SLO can be a confocal laser scanning microscope for diagnostic imaging of the retina of the eye. Imaging can be two-dimensional (2D) imaging, and a laser beam can be used to scan across the retina in a raster pattern to illuminate successive elements of the retina point-by-point. Light reflected from each retinal point can be captured by a photomultiplier tube. The output of the photomultiplier tube can be recorded and displayed in a digital format. In this way, the SLO may be able to produce high-contrast, detailed images of the retina. In some embodiments, images are captured sequentially using one imaging modality of the SLO and at least one additional imaging modality using at least one of the SLO and an OCT device.

[0017] Figure 2 A schematic diagram of an ophthalmic imaging instrument 102 according to an embodiment of the present invention is shown. As shown, the ophthalmic imaging instrument 102 includes a light source 200 arranged to emit a light beam 201 as a scanning beam. A polygonal scanning mirror 202 acts as a first scanning element (or in other words, a first scanning relay device), the polygonal scanning mirror 202 including a plurality of reflective facets 2021, 2022, ... and arranged about a rotation axis a. xThe beam rotates in a plane of rotation (i.e., parallel to the yz plane). The facets may each have the same shape and may each extend a distance in a common direction (i.e., the x-direction) orthogonal to the plane of rotation of the polygonal scanning mirror 202. In some embodiments, the beam 201 may have a cross-sectional area that is a fraction of the area of ​​the facets (e.g., less than 0.1% or 1% of the area of ​​each facet). The polygonal scanning mirror 202 is arranged to reflect the beam 201 toward the optical system 220 and return the light L from the eye E. R Reflected toward detector 205, as described later. As shown, when incident on polygonal scanning mirror 202, beam 201 may have a component in the direction opposite to the positive y-direction during its travel. In this embodiment, the polygonal scanning mirror is a regular convex polygon with 12 rectangular facets, each facet having a length defined by the lengths of two edges of the polygonal scanning mirror 202 parallel to the plane of rotation of the polygonal scanning mirror 202, and a width in a common direction defined by the lengths of two edges of the polygonal scanning mirror 202 orthogonal to that plane. However, other numbers of facets (e.g., 16 facets or at least four or five facets), facet shapes, or polygonal geometry may be used alternatively.

[0018] A driver 203 is arranged to rotate the polygonal scanning mirror 202 during operation (in the plane of rotation of the polygonal scanning mirror 202) such that each facet 2021, 2022... reflects the light beam 201 at a varying angle α (as the facets rotate at angular positions within a predetermined range). The driver 203 may be, for example, a motor connected to the polygonal scanning mirror 202 and controlled by a controller (which may be computing resource 106) of the ophthalmic imaging instrument 102. As shown, the path of the scanning light beam 201 is illustrated in a one-dimensional (1D) scan generated during an exemplary counterclockwise rotation of the polygonal scanning mirror 202 (indicated by a curved arrow). Path "A" is an example of the scanning light beam 201 reflected from the corresponding facet 2021 of the polygonal scanning mirror 202 at the starting point during rotation (i.e., when facet 2021 moves into the path of the light beam 201 from the light source 200). Path "B" is an example of a scanning beam 201 reflected from the corresponding facet 2021 of the polygonal scanning mirror 202 at a later time point after further downward rotation, as facet 2021 moves out of the path of the beam 201 from the light source 200.

[0019] In this manner, as the beam 201 moves from one edge of a facet defining its length to another, the polygonal scanning mirror 202 reflects the beam 201 from the active facet (i.e., the facet currently reflecting the beam 201 from the light source 200 to the optical system 220) at a varying angle α. When facet 2021 moves out of the range of the beam 201, the adjacent facet 2022 (i.e., the facet adjacent to / bordering facet 2021 in a rotational direction opposite to the rotational direction of the polygonal scanning mirror 202) substantially repeats the described reflection process, such that each facet sequentially reflects the beam 201 continuously at a varying angle α. This varying angle α varies with the control of the length and rotation of the respective facet, and the corresponding orientation of the facet relative to the incident beam 201 determines the reflection angle of the beam 201.

[0020] The ophthalmic imaging instrument 102 also includes an optical system 220 arranged to guide a light beam 201 reflected from the polygonal scanning mirror 202 (i.e., a light beam 201 reflected at a varying angle α) through the cornea C of the eye E toward the fundus F of the subject's eye E. See later. Figure 4 Examples of components and optical elements within the optical system 220 are described.

[0021] The optical system 220 is also arranged to receive light L returning from the fundus F. R Guided towards polygonal scanning mirror 202. Return light L R This can be, for example, light scattered from the eye E in a red-green or red-green-blue imaging mode, or it can be or include, for example, light emitted from the eye E in an AF imaging mode. The returning light L R It can follow the same optical path as beam 201, and therefore can be guided by optical system 220 at a varying angle α toward polygonal scanning mirror 202 along the optical path corresponding to the reflection of beam 201, as described later. (Return to light L) R Therefore, the light is guided by the optical system 220 to the activation surface, and the activation surface reflects the reflected light L along the optical path of the beam 201 toward the detector 205. R This is to form an image 210 of the eye E, as described later. When the currently active facet moves outside the range of the beam 201, the adjacent facet becomes the active facet and substantially repeats the described return light L. R The reflection process causes each facet to sequentially reflect the returned light L along the optical path of beam 201 toward detector 205. RTherefore, continuous scan lines in image 210 can be formed by using, for example, orthogonal scanning elements. As described later, in some embodiments, these continuous scan lines in image 210 may correspond to a portion β of the varying angle α, which may be different from the varying angle α, and more specifically a subset of the varying angle α (e.g., greater than 50%, 70%, or 90% of the varying angle α and less than 95% or 100% of the varying angle α, or centered within the varying angle α or starting from the beginning of the varying angle α when the faceted just-reflected beam 201 is activated).

[0022] In some embodiments, the reflected light L from the eye E R The beam can be larger than the diameter of beam 201 and can be (substantially) equal to the diameter of the pupil of eye E. The beam can have a size that (substantially) fills the entire area of ​​each facet. However, those skilled in the art will understand that this depends, for example, on the components and optical elements in optical system 220, the characteristics of beam 201, and imaging mode 121.

[0023] As previously described, some of the light beams 201 reflected from the polygonal scanning mirror 202 and guided by the optical system 220 toward the eye E can be reflected back from the cornea C to form image artifacts in the image 210. Similarly, some of the light beams 201 reflected from the polygonal scanning mirror 202 can be reflected back from at least one of the optical elements in the optical system 220 to also form image artifacts in the image 210. These reflected portions of the light beams 201 can follow the same path as the return light L incident on the detector 205. R The optical paths are different from those of the optical paths, therefore, as the inventors have recognized, the return light L used to generate image 210 can be blocked / impeded or blocked / impeded to a minimum without obstruction / impedance. R In this case, these reflected portions are blocked to prevent them from reaching detector 205.

[0024] Therefore, the ophthalmic imaging instrument 102 also includes a mask (or light blocker) 206, which is arranged to block a portion of the light beam 201 reflected from the polygonal scanning mirror 202 to prevent it from reaching the detector 205 (e.g., via the polygonal scanning mirror 202, as described below), which is light that has already been reflected back from at least one of the optical elements of the cornea C of the eye E and / or the optical system 220 (i.e., back-reflected light). The mask 206 can achieve this by at least one of the following: substantially absorbing the portion of the light beam 201 (e.g., absorbing at least 90% or 95% of the portion of the light beam 201); and / or reflecting the portion of the light beam 201 along the optical path that is not incident on the detector 205 (so that it is not detected by the detector 205). Thus, the mask 206 can prevent the portion of the light beam 201 from reaching the detector. This portion of beam 201 is part of the output scanning beam 201, which is reflected back to detector 205 and does not propagate to the fundus F (therefore it is not the return light L). R As shown, mask 206 is arranged between rotating polygonal mirror 202 and optical system 220, although other arrangements as described later are also possible. In cases where mask 206 is arranged to substantially absorb this portion of beam 201, as in this embodiment, mask 206 may be a non-reflective element, such as a metal plate having, for example, an anti-reflective coating (e.g., an absorptive anti-reflective coating or a multilayer anti-reflective coating).

[0025] Figure 3 An enlarged schematic diagram of the rotating polygonal mirror 202 and mask 206 is shown to illustrate other aspects of this arrangement. These components are shown together with additional optional elements that can form part of the ophthalmic imaging instrument 102, as described below. Only the return light L R The diagram is shown to illustrate some aspects of it more clearly. Part P of beam 201 is shown. 201 An example of an optical path, this part P 201 The light reflected back from at least one of the optical elements of the cornea C of the eye E and / or the optical system 220 may be detected by the detector 205 and will therefore be blocked by the mask 206. This optical path is different from the returning light L. R The optical path. However, it should be understood that other such portions blocked by mask 206 (in the arrangement of mask 206 shown or described later) can travel along the portion P of the beam 201 shown. 201 Different optical paths exist, and these parts, as well as part P of beam 201, are also present. 201 They can have a spatial distribution of optical paths around them (not shown), for example, by these portions and portion P of beam 201. 201The spatial distribution of the optical path determined by the elements performing back reflection. As those skilled in the art will understand, the blocked portion P of beam 201 201 Optical path and return light L R The angle between them can change during the rotation of the polygonal scanning mirror 202.

[0026] For this portion P of the beam 201 that will be incident on the facet 2022 during the rotation of the polygonal scanning mirror 202 201 All optical paths, this part P of beam 201 201 The reflected light L is blocked by mask 206 and does not strike the facet 2022 of the polygonal scanning mirror 202, which is the next facet to reflect the beam 201 at a changing angle α during the rotation of the polygonal scanning mirror 202, thereby detecting the returned light L. R Image 210 is formed. That is, in this part P of beam 201 201 As the light travels along any path that will be incident at any point on facet 2022, it is blocked by mask 206. Thus, each scan line in image 210 is blocked by a light source corresponding to the line extending to... Figure 3 The detected returned light L is a portion of the angle α of the change in the current angular rotation of the polygonal scanning mirror 202 (i.e., where the facet 2022 is parallel to the plane 211, as described below). R In the case of formation, this part P of beam 201 201 The beam 201 is blocked by the mask 206 from being incident on any part of the entire facet 2022, thus preventing any such portion P of the beam 201 from being incident on any part of the facet 2022. 201 The light reaches detector 205, is detected, and thus forms an image artifact in image 210. In this case, the return light L... R Therefore, the reflected light L is blocked by the mask 206 during the rotation of the polygonal scanning mirror 202 and does not incident on the facet 2022, thus detecting the return light L. R Image 210 is formed. This allows mask 206 to block part P of beam 201. 201 and return light L R The optical paths are different and in the return optical L R This can greatly reduce the prevalence of image artifacts in image 210 due to back reflection of beam 201. However, it should be understood that if the polygonal mirror 202 is rotated clockwise, the facet 2022 of the polygonal scanning mirror 202 will be the facet that last reflects beam 201 at a changing angle α during the rotation of the polygonal scanning mirror 202.

[0027] In some embodiments, more generally, during the rotation of the polygonal scanning mirror 202, a portion P of the beam 201... 201The reflected light L is blocked by mask 206 and does not incident on a portion of the facet 2022 of polygonal scanning mirror 202, thus detecting the reflected light L. R Image 210 is formed. That is, in this part P of beam 201 201 As the light travels along the path that will be incident on a portion of the facet 2022, it is blocked by the mask 206. For example, in each scan line of image 210, the mask is blocked by the mask 206. Figure 3 The entire change in angle α is shown, and the detected return light L R During formation, when the polygonal scanning mirror 202 rotates, part P of the beam 201... 201 It is blocked by mask 206 to prevent it from incident on the changing portion of facet 2022, thus blocking that portion P of beam 201. 201 The image reaches detector 205, is detected, and thus forms an image artifact in image 210. Therefore, while utilizing the entire changing angle α of image 210, the image artifact in image 210 caused by back reflection can be reduced at least partially, thereby allowing an extended field of view of ophthalmic imaging instrument 102 to be obtained (via utilizing the entire length of each facet when reflecting the beam 201).

[0028] like Figure 3 As shown, the (e.g., flat) surface 212 of the mask 206 can block a portion P of the beam 201. 201 Thus, at a given angular rotation of the polygonal scanning mirror 202, each facet of the polygonal scanning mirror 202 is parallel to the surface 212 of the mask 206. The inventors have recognized that by reflecting a portion P of the light beam 201 along the optical path not incident on the detector 205... 201 The vertical orientation of the mask surface relative to the facets in the portion P that blocks the beam 201 201 This aspect is particularly advantageous. However, it should be understood that other orientations of the surface 212 of the mask 206 can be used alternatively.

[0029] like Figure 3 As further shown, facet 2022 shares edge E (i.e., the edge along the x-direction) with the active facet 2021 that currently reflects the beam at a varying angle α, forming an obtuse angle θ between the beam 201 and the line from edge E to the point of incidence of the beam 201 on the active facet 2021. In other words, facet 2022 shares edge E of the active facet 2021, which lies along the active facet 2021 in the direction of the projection of the beam 201 onto the edge of the active facet 2021 orthogonal to edge E. In this way, during the rotation of the polygonal scanning mirror 202, the mask 206 will block a portion P of the beam 201. 201 The incident facet 2022 in Figure 3Below the active facet 2022 (i.e., further sharing the edge E of the active facet 2021 in the direction opposite to the y-direction), the returned light L is thus detected. R Image 210 is formed.

[0030] The inventors have realized that, Figure 3 This arrangement of the facet 2022 below the middle blocking activation facet 2021 is particularly advantageous in suppressing image artifacts in the image 210 that would otherwise be formed by the back reflection portion of the beam 201, which would then reach and be detected by the detector 205. This is because the adjacent facet 2022 is positioned relative to the returning light L. R The angle means that stray back reflections from the corneal C or (one or more) optical elements, if incident on facet 2022, are likely to return to detector 205 more likely than, for example, incident on upper facet 2023. This is especially true when the housing surrounds the polygonal scanning mirror 202, as described below, because back reflections incident on facet 2023 will typically propagate to be contained within the housing. In the case where the rotating polygonal mirror 202 has more facets (e.g., 16 or more facets), the inventors further recognize that, as the number of facets in the rotating polygonal mirror 202 increases, the facet 2022 below the active facet 201 is more likely to return to detector 205 relative to the returned light L. R The angle is close to the active facet 2021 relative to the return light L R The angle of the beam further enhances the aforementioned benefits of blocking the facet 2022. However, in some embodiments, the mask 206 may alternatively be arranged to block the facet 2023 above the active facet 2022, so that a portion of the beam 201 cannot reach the facet 2023, and cannot (e.g., along the path that would be incident on the facet 2023 and could be different from the returning beam L) R The light beam 201 reaches the detector 205, and this part of the light beam 201 has been reflected back (along the light path that will be detected by the detector 205) from at least one of the cornea C of the eye E and the optical elements of the optical system 220.

[0031] As in this embodiment of the device, the mask 206 may extend a distance (not shown) in a direction orthogonal to the plane of rotation of the polygonal scanning mirror 202, the distance being equal to or greater than the distance each facet extends in the direction orthogonal to the plane of rotation of the polygonal scanning mirror 202. In this way, a portion P of the beam 201 201 It is blocked by mask 206 to prevent it from incident on the facet along the distance extending along mask 206 in that direction. For example, mask 206 may be a rectangular element (which includes surface 212) with a width equal to or greater than Figure 3The width of the rectangular facets 2021, 2022... shown. This optional feature results in a portion P of the beam 201. 201 The mask 206 blocks the entire width of each facet, which results in further suppression of image artifacts in the image 210 formed by the back reflection of the beam 201 that reaches and is detected by the detector 205.

[0032] Although the above description describes mask 206 blocking facets 2022 or 2023 adjacent to the active facet 2021, the invention is not limited thereto, and mask 206 may more generally block a portion of a light beam 201 that has been reflected from at least one of the optical elements of the eye E's cornea C and / or the optical system 220 toward the detector 205 from incident on at least one facet of the polygonal scanning mirror 202 that does not reflect the light beam 201 during the rotation of the polygonal scanning mirror 202 (i.e., at least one facet that is not the active facet), thereby detecting the returned light L. R Image 210 is formed. That is, when a portion of the beam 201 travels along the optical path that will be incident on at least one facet of the polygonal scanning mirror 202, it is blocked by the mask 206. As an example, if the housing 208 is removed or the opening 209 of the housing 208 is large enough, the mask 206 may extend in the negative y direction to further block a portion of the beam 201 from being incident in the clockwise direction on the next two facets of the facet 2022 if the back-reflected portion of the beam 201 follows any of these facets and the optical path toward the detector 205.

[0033] return Figure 3 The ophthalmic imaging instrument 102 also includes an optional housing 208 having an opening 209 that surrounds the rotating polygonal mirror 202. As shown, the opening 209 may extend across plane 211 (i.e., parallel to the xy plane). In such an example, the housing 208 can protect the ophthalmic imaging instrument 102 from malfunctions of the rapidly rotating polygonal scanning mirror 202 by containing fragments of the polygonal scanning mirror 202 that may be propelled outward at high speed. With the optional housing 208 provided, a mask 206 is fixed within the housing 208. However, without the housing 208, the mask 206 may be attached to the ophthalmic imaging instrument 102 in other ways, such as by fixing it to the aforementioned housing of the ophthalmic imaging instrument 102. As in this device embodiment, the opening 209 may be larger than the size of each of the plurality of facets in order to unconstrain or negligibly constrain (or limit) the return light L reflected from each (activated) facet and reaching the detector 205. R However, in some embodiments, the mask 206 can be provided through the opening 209, and therefore can be implemented directly by the housing 208, in order to reduce the number of components in the ophthalmic imaging instrument.

[0034] like Figure 3 As shown, the line orthogonal to plane 211 and passing through the center of plane 211 intersects the rotation axis a of the polygonal scanning mirror 202. x The facets intersect and are parallel to the plane of rotation of the polygonal scanning mirror 202. Furthermore, at a given rotation of the polygonal scanning mirror 202, each facet is parallel to plane 211 when reflecting the beam 201. As in this embodiment, when facet 2022 is activated parallel to plane 211, the opening 209 is blocked up to edge E by mask 206, and a portion P of the beam 201 can be blocked by mask 206. 201 This is to prevent it from incident on the facet 2022. That is, the mask 206 extends parallel to the plane 211 of the opening 209 to the edge E, so as to block portion P when the facet 2021 is activated parallel to the plane 211. 201 To prevent it from incident on facet 2022. As shown, surface 212 of mask 206 can be parallel to plane 211 of opening 209. In this way, mask 206 blocks part P of beam 201 during rotation of polygonal mirror 202. 201 All light paths incident on facet 2022 are used to detect the return light L. R Image 210 is formed, as described above.

[0035] The ophthalmic imaging instrument 102 (or more specifically, opening 209) also includes an optional phase mask 210, which can be arranged to cover opening 209. The phase mask 210 can correct for aberrations caused by at least one component and optical element of the optical system 220, such as the scanner surface and ellipsoid as described later.

[0036] Return to Figure 2 Detector 205 is arranged to detect the reflected light L from the polygonal scanning mirror 202. R To generate detection signal S d The detection signal S used d It can be during the rotation of the polygonal scanning mirror 202, which corresponds to a portion β of the angle α corresponding to the change of at least one facet, from the returning light L R The generated signal, although as mentioned above, may not necessarily be so. Detected signal S dThe signal is sent to and received by computing resource 106 via path 207 to computing resource 106. Detector 205 may comprise a one-dimensional or two-dimensional array of photosensitive elements. However, the form of detector 205 is not limited, and detector 205 may, for example, comprise a balanced photodetector arrangement comprising two reverse-biased photodiodes whose output photocurrents are subtracted from each other, and the resulting current signal is converted into a voltage detection signal by a transimpedance amplifier.

[0037] Path 207 is a path to computing resource 106, wherein computing resource 106 is arranged to use detection signal S d An image 210 of the fundus F of eye E is generated. As in this embodiment of the device, the reflected light L, which is reflected by at least one facet (e.g., all facets) during rotation of the polygonal scanning mirror 202, can be used. R The generated detection signal S d To generate image 210. Thus, image 210 of eye E is generated from each corresponding to the detection signal S. d The continuous scan lines are formed, and the detection signal S d The returned light L is detected during the rotation of the polygonal scanning mirror 202, which corresponds to at least the portion β of the angle α corresponding to the change of each facet. R Generated.

[0038] Part P of blocking beam 201 201 To prevent it from reaching detector 205, mask 206 is therefore arranged to block part P of beam 201. 201 To at least partially suppress (or remove) image artifacts in the image 210 of the fundus F, which will be detected by detector 205 (e.g., by polygonal scanning mirror 202, as described above) on a portion of beam 201 P 201 This is generated through detection. As mentioned earlier, this can therefore greatly improve the quality of images generated by ophthalmic imaging instruments.

[0039] Although the above description describes the mask 206 being positioned between the rotating polygonal mirror 202 and the optical system 220 and blocking a portion of the light beam 201 to prevent it from reaching the detector 205 via the polygonal scanning mirror 202, the invention is not limited thereto, and the mask 206 can be placed at alternative locations within the ophthalmic imaging instrument 102. The placement of the mask 206 within the ophthalmic imaging instrument 102 can be selected in such a way as to at least partially suppress the aforementioned image artifacts: acquiring an image of the fundus F; identifying image artifacts in the image suspected to be caused by back reflections from at least one of the cornea C of the eye E and / or the optical elements of the optical system 220; and placing the mask 206 at a first location within the ophthalmic imaging instrument 102 (which may not block or negligibly block the return light L). R The process involves acquiring another image of the fundus F and identifying whether image artifacts have been at least partially suppressed. If not suppressed, mask 206 can be moved to a second position, and so on, until image artifacts have been at least partially suppressed. Therefore, mask 206 can be placed at a position where image artifacts are at least partially suppressed, although mask 206 can be further moved to improve the degree to which image artifacts in the image are suppressed. Those skilled in the art will understand that by identifying a different image than the returned light L… R The iterative process can be accelerated by starting the iterative process with potential optical paths (e.g., by using ray tracing software) and by placing a mask 206 at a location that blocks these optical paths (since these locations are most likely to suppress image artifacts), wherein these potential optical paths are the optical paths that a portion of the beam 201 may follow when back-reflected by at least one of the optical elements of the cornea C of the eye E and the optical system 220 to reach the detector 205.

[0040] Figure 4 A schematic diagram of an ophthalmic imaging instrument 120, in the context of an example of an optical system 220, is shown according to an embodiment of the invention, and is again shown as in conjunction with... Figure 2 The elements explained above (the same reference numerals therefore denote the same elements and functions). As mentioned above, it may also include... Figure 3The optional components shown are described. An ophthalmic imaging instrument 120 is described in the context of an imaging modality in which a beam 201 is generated by a light source 200 and directed toward a patient's eye E, reflected at the tissue of the eye E, and directed back to the detector 205. As part of an SLO module, the instrument 120 includes an example of a light source 200 emitting the beam (i.e., the scanning beam 201), a polygonal scanning mirror 202 (in other words, a first scanning element 202), and an optical system 220 including a plurality of additional scanning relay elements. The scanning relay elements include a second scanning element 206 and optical elements positioned and configured to guide the scanning beam 201. In some embodiments, the optical elements may include an optical element 204 and a second optical element 208, where the optical element 204 may be a scan compensation element, such as a curved mirror or a slit mirror, and the second optical element 208 may be a scan transfer element, such as a primary mirror.

[0041] Optical elements 204 and 208 are positioned and configured to guide the scanning beam 201. The second scanning element 206 may be or include an oscillating plane mirror or a plane mirror coupled to a galvanometer motor. Optical element 204 may be a curved mirror, such as an ellipsoidal mirror. The second optical element 208 may be an aspherical mirror. It should be understood that the first and second optical elements may have alternative forms. Scanning elements 202 and 206 may be referred to as a scanning device or multiple separate scanning devices. It should be understood that the functions shown are merely examples of configurations that can be used with the embodiments described herein. In some examples, one or more of the scanning elements may include, for example, one or more of an oscillating plane mirror, a galvanometer mirror, a MEMS mirror, a rotating mirror, a prism, or a polygonal scanner and / or a resonant mirror.

[0042] A mask 206 is provided, which is arranged to block part P of the beam 201 reflected from the polygonal scanning mirror 202. 201 To prevent it from reaching detector 205, this part P 201 It is a beam of light that has been reflected back from at least one of the optical elements of the cornea C of the eye E and / or the optical system 220, as explained above. The portion P that can be reflected back to beam 201 towards detector 205. 201 The optical elements of the example optical system 222 include, but are not limited to, those of other optical systems. Figure 4 Several additional scanning relay elements are shown.

[0043] In some examples, detector 205 may be a separate component or device operatively coupled to light source 200, such that detector 205 and light source 200 may be positioned in the same location or adjacent to each other. In some examples, light source 200 may be implemented together with detector 205 as a single device or a device within a common housing, such that, in addition to emitting scanning beam 201, the device may also be able to detect or receive light, such as light reflected from first scanning element 202 or from optical element 204. In some further examples, ophthalmic imaging instrument 120 may include a focusing lens positioned in front of detector 205, the focusing lens being arranged to focus all or substantially all of the reflected light L from rotating polygonal mirror 202 onto detector 205. R .

[0044] In the exemplary SLO imaging mode, the scanning beam 201 can be a laser of a suitable wavelength used in SLO applications. If other imaging modes are included, the scanning beam 201 can be a collimated beam, comprising, for example, a laser for SLO applications and a superluminescent diode (SLD) for other applications. It should be understood that any suitable collimated light source can be used, such as a single-frequency laser diode, a vertical-cavity surface-emitting laser, a wavelength-scanning laser source, a pulsed laser source, or other light sources with sufficient intensity and good collimation to produce sufficient retinal illumination. In such applications, an SLD can be used due to the short coherence length required to distinguish the retinal layer from the resulting interferometric data. The SLD can be free-space coupled to the scanning system or fiber-coupled to the scanning system via standard or polarization-maintaining fibers. A frequency-scanning laser source can also be used in other applications, thereby tuning the wavelength of the source within a given range.

[0045] In some embodiments, each of the first scanning element 202 or the second scanning element 206 may be a single element or an arrangement of two or more elements, as long as it is suitable for providing a scan at a corresponding focal point F1 or F2 (as shown) where the scanning elements are positioned. Focal points F1 and F2 are the focal points of optical element 204, and focal points F2 and F3 are the focal points of optical element 208. The first scanning element 202 is located at focal point F1, the second scanning element 206 is located at focal point F2, and the eye E (e.g., the pupil of eye E) is located at focal point F3 (also referred to as the virtual scan point). When light sweeps across the virtual scan point (e.g., through F3) onto the fundus F of eye E, thereby passing through the cornea C of eye E, the resulting scan may be a 2D scan or a scan pattern of the scanning beam 201.

[0046] In some embodiments, the first scanning element 202 provides a vertical, horizontal, or patterned scan incident on the optical element 204 to a point on the second scanning element 206 via the optical element 204. For example, the scan can be a 1D or 2D optical scan. The axes of the first scanning element 202 and the second scanning element 206 can be arranged to create a 2D optical scan, such as in the form of a raster scan pattern of a scan beam 201. The alignment of the first scanning element 202 and the second scanning element 206 can be orthogonal, substantially orthogonal, or arranged to produce any scan geometry around the optical elements 204 and 208.

[0047] In some embodiments, the second scanning element 206 provides various scans, such as 1D or 2D optical scans, which may include horizontal scans, vertical scans, or any pattern of the scanning beam 201. The scans provided by the first scanning element 202 and the scans provided by the second scanning element 206 differ from each other, for example, with respect to the orientation of the scans. In some examples, one of the scanning elements may provide a vertical scan of the retina, and the other scanning element may provide a horizontal scan of the retina. The scanning beam 201 is guided toward the eye E via the scanning elements 202 and 206 and the optical elements 204 and 208, such that a wide or ultra-wide field of view scanning angle is achieved, for example, at the pupillary plane of the eye E.

[0048] A "wide field of view" scan refers to a scanning angle exceeding 50 degrees in one or two dimensions. An "ultra-wide field of view" scan refers to a scan that essentially covers the entire retina of the eye E. In some examples, multiple line scans can be generated by scanning the retina along a first direction using a first scanning element 202, and by changing the position of the multiple line scans along a second direction using a second scanning element 206, wherein the second direction is orthogonal to the first direction. Figure 4 As shown, the path of the scanning beam 201 is illustrated in a 1D scan generated by a single oscillation or rotation (indicated by the curved arrow) of the first scanning element 202. Path "A" is an example of the scanning beam 201 reflected from the polygonal scanning mirror at one orientation of the reflective facet during rotation, while paths "B" and "C" are examples of the scanning beam 201 reflected at other orientations of the facet during rotation.

[0049] The components of the ophthalmic imaging instrument 120 can be arranged such that the axis of rotation of the first scanning element 202 is substantially parallel to the line connecting the two focal points (i.e., F2 and F3) of the optical element 208, such that the scanning beam 201 scans across the secondary axis of the optical element 204. Furthermore, the first scanning element 202 can produce a 1D or 2D scan incident on the optical element 204. Therefore, the optical element 204 can also produce a 1D or 2D scan. The components of the ophthalmic imaging instrument 102 can be arranged such that the line connecting the two focal points (i.e., F2 and F3) of the optical element 208 lies substantially on the plane defined by the scan produced by the optical element 204 (e.g., a 1D vertical scan).

[0050] Therefore, the first scanning element 202 and the second scanning element 206 can work together to create an optical scan in the form of a raster scan pattern, such as a 2D scan, from a single point in space at or near the focal point F3 in the patient's eye E. The first and second scanning elements can have operating parameters including the amplitude and rotational offset of the oscillation. The operating parameters also include the oscillation speed. Both operating parameters can be selected to control the direction and pattern of the optical scan from the surface point light source. In some examples, the first and second scanning elements can be housed in a rotatable mount (not shown) that can adjust the centering (or eccentricity) of the scanning beam 201 on the fundus F of the eye E, providing the ability to “move” the imaging field across the fundus F.

[0051] Figure 5A flowchart illustrating a general method embodiment of the present invention is shown. Specifically, the method embodiments relate to operating an ophthalmic imaging instrument including pathways for a light source, a polygonal scanning mirror, an optical system, a mask, a detector, and computing resources. For example, the method may be adapted to operate ophthalmic imaging instruments 102 or 120 as disclosed and described in connection with embodiments of this disclosure. The method includes: step S101, rotating the polygonal scanning mirror by means of a driver such that each facet reflects a light beam; step S102, guiding the light beam reflected from the polygonal scanning mirror through the cornea of ​​the subject's eye toward the fundus of the eye by means of an optical system; step S103, guiding light returning from the fundus toward the polygonal scanning mirror by means of an optical system; step S104, blocking a portion of the light beam reflected from the polygonal scanning mirror by means of a mask to prevent it from reaching the detector (in order to at least partially suppress or remove image artifacts in the fundus image caused by detecting this portion of the light beam when generating a detection signal), wherein this portion of the light beam is (along the light path to be detected by the detector) a light beam that has been reflected back from at least one of the optical elements of the eye's cornea and / or the optical system; step S105, generating a detection signal by means of a detector by detecting the returned light (reflected from the polygonal scanning mirror); and step S106, generating an image of the fundus of the eye using the detection signal by means of computational resources (e.g., via a pathway). It should be noted that, if the chosen implementation is most suitable, steps S101 to S106 may be performed simultaneously and / or at least partially sequentially.

[0052] The foregoing has presented embodiments and details thereof as part of the present invention, which can provide one or more advantages by improving the power control mechanism in ophthalmic imaging instruments that allow for flexibility in providing multiple imaging modalities while maintaining safety without increasing the system and / or implementation. While various embodiments of this disclosure have been described above, it should be understood that they are presented by way of example and not limitation. It will be apparent to those skilled in the art that various changes in form and detail can be made. Therefore, the exemplary embodiments described above are not limiting.

[0053] While this specification contains numerous details of specific embodiments, these should not be construed as limiting the scope of any invention or potentially claimed content, but rather as descriptions of features specific to the particular embodiments described herein. Certain features described in this specification within the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, although features may be described above as acting in a particular combination and even initially claimed in this way, one or more features from a claimed combination may be removed from the combination in some cases, and the claimed combination may be for a sub-combination or a variation thereof.

Claims

1. An ophthalmic imaging instrument (102, 120), comprising: A light source (200) is arranged to emit a beam (201); A polygonal scanning mirror (202) includes multiple reflective facets (2021, 2022, ...). A driver (203) is arranged to rotate the polygonal scanning mirror (202) during operation such that each facet reflects the light beam (201). An optical system (220) is arranged to guide the light beam (201) reflected from the polygonal scanning mirror (202) through the cornea (C) of the subject's eye (E) toward the fundus (F) of the eye (E), and to direct the light (L) returning from the fundus (F) R ) is guided toward the polygonal scanning mirror (202); A mask (206) is arranged to block a portion (P) of the light beam (201) reflected from the polygonal scanning mirror (202) that has already been reflected from the cornea (C) of the eye (E) and at least one of the optical elements (204, 206, 208) of the optical system (220). 201 ), to prevent it from reaching the detector (205); The detector (205) is arranged to detect the reflected light (L) from the polygonal scanning mirror (202). R ) to generate a detection signal (S) d );and The path (207) to the computing resource (106) is arranged to use the detection signal (S) d Generate an image of the fundus (F) of the eye (E) (210).

2. The ophthalmic imaging instrument (102, 120) according to claim 1, wherein, The portion (P) of the beam (201) 201 The light beam (201) is blocked by the mask (206) to prevent it from incident on a portion of at least one facet of the polygonal scanning mirror (202) that is currently not reflecting the light beam (201) during the rotation of the polygonal scanning mirror (202), thereby detecting the returned light (L). R The image (210) is formed.

3. The ophthalmic imaging instrument (102, 120) according to claim 2, wherein, The portion (P) of the beam (201) 201 The light beam (L) is blocked by the mask (206) to prevent it from incident on a portion of the first facet (2022, 2023) of the polygonal scanning mirror (202) during the rotation of the polygonal scanning mirror (202), thereby detecting the returned light (L). R The image (210) is formed.

4. The ophthalmic imaging instrument (102, 120) according to claim 3, wherein, For the portion (P) of the light beam (201) that will be incident on the first facets (2022, 2023) during the rotation of the polygonal scanning mirror (202), 201 All optical paths of the beam (201), the portion (P) of the beam (201) 201 The light is blocked by the mask (206) to prevent it from incident on the first facet (2022, 2023), thereby the returned light (L) R The image (201) is formed.

5. The ophthalmic imaging instrument (102, 120) according to claim 3 or 4, wherein, The first facet (2022) of the polygonal scanning mirror (202) shares an edge (E) with the active facet (2021) that currently reflects the light beam (201), and wherein an obtuse angle (θ) is formed between the light beam (201) and the line from the edge (E) to the point of incidence of the light beam (201) on the active facet (2021).

6. The ophthalmic imaging instrument (102, 120) according to any one of the preceding claims, wherein, The polygonal scanning mirror (202) is surrounded by a housing (208) having an opening (209) that extends across a plane (211).

7. The ophthalmic imaging instrument (102, 120) according to claim 6, wherein, The opening (209) includes a phase mask (210).

8. The ophthalmic imaging device (102, 120) according to claim 6 or 7, wherein, The mask (206) is fixed inside the outer shell (208).

9. The ophthalmic imaging apparatus (102, 120) according to any one of claims 6 to 8 when dependent on claim 5, wherein, When the activated facet (2021) is parallel to the plane (211), the mask (206) blocks the portion (P) of the beam (201) by blocking the opening (209) of the housing (208) up to the edge (E). 201 ), to prevent it from being incident on the first facet (2022).

10. The ophthalmic imaging apparatus (102, 120) according to any one of the preceding claims, wherein, Each of the plurality of facets (2021, 2022, ...) extends a first distance in a direction orthogonal to the rotation plane of the polygonal scanning mirror (202), and the mask (206) extends a second distance equal to or greater than the first distance in a direction orthogonal to the rotation plane of the polygonal scanning mirror (202).

11. The ophthalmic imaging instrument (102, 120) according to any one of the preceding claims, wherein, The surface (212) of the mask (206) blocks the portion (P) of the light beam (201). 201 ), and wherein, at a given angle of rotation of the polygonal scanning mirror (202), each facet of the polygonal scanning mirror (202) is parallel to the surface (212) of the mask (206).

12. The ophthalmic imaging instrument (102, 120) according to any one of the preceding claims, wherein, The image (210) of the fundus (F) of the eye (E) is obtained using the reflected light (L) from all facets (2021, 2022, ...) during the rotation of the polygonal scanning mirror (202). R The detection signal (S) generated by the signal is d Generated by ).

13. The ophthalmic imaging instrument (102, 120) according to any one of the preceding claims, wherein, The polygonal scanning mirror (202) is a regular convex polygon with 16 facets.

14. The ophthalmic imaging instrument (102, 120) according to any one of the preceding claims, wherein, The ophthalmic imaging instruments (102, 120) are scanning laser ophthalmoscopes.

15. A method for operating an ophthalmic imaging instrument (102, 120) according to any one of the preceding claims, the method comprising: - The polygonal scanning mirror (202) is rotated (S101) by means of the driver (203) such that each facet (2021, 2022, ...) reflects the light beam (201). - By means of the optical system (220), the light beam (201) reflected from the polygonal scanning mirror (202) is guided toward the fundus (F) of the subject's eye (E) (S102). -The light (L) returned from the eye (E) is transmitted by means of the optical system (220). R (S103) guides the polygonal scanning mirror (202) toward the polygonal scanning mirror. -The portion (P) of the beam (201) reflected from the polygonal scanning mirror (202) by means of the mask (206) (S104) is blocked (P). 201 ), to prevent it from reaching the detector (205); - By means of the detector (205), the returned light (L) is detected R (S105) to generate the detection signal (S) d );as well as - Using the detection signal (S) with the aid of the computing resources (106) d (S106) Generate (210) the image of the fundus (F) of the eye (E).

Images