Slit Scanning Fundus Imager Enhancements

Abstract

A scanning imaging system has a scanning component that receives light from a light source and generates a scanning beam that is directed by an optical system to a sample to be imaged. A camera captures light returned from the sample to construct an image. Reflections on a target lens within the optical system are prevented by one or more light blocks. A first light block that is imaged onto the target lens is positioned in the optical path from the light source to the scanning component to generate a first moving dark area on the target lens through which the scanning beam from the scanning component to the sample cannot pass. A second light block that is also imaged onto the target lens is positioned in the optical path from the sample to the collector to generate a second moving dark area on the target lens through which the light returned from the sample cannot pass. The moving dark area keeps the scanning beam separated from the return light on the target lens.

Description

Technical Field

[0001] The present invention relates generally to the field of scanning imagers and more particularly to reducing image artifacts caused by reflections from the internal optics of scanning imagers, particularly fundus scanning imagers. Background Art

[0002] Various different types of image capture devices are known for imaging samples under test. Of particular interest are imaging systems that are capable of capturing close-up images of samples with sufficient detail (e.g., sufficient focus, illumination, magnification, and signal-to-noise ratio (SNR)). One example of such an imaging system is a fundus imager, which is typically used to image the fundus of the eye. The fundus is the inner surface of the eye opposite the lens of the eye and can include the retina, optic disc, macula, fovea, and posterior pole. Two types of imaging systems used to image the fundus are flood illumination imaging systems (or flood illumination imagers) and scanning illumination imaging systems (or scanning imagers).

[0003] Flood illumination imagers simultaneously flood the entire field of view (FOV) of a sample (e.g., by using a flash) and capture an image of the sample (e.g., the fundus) with a full-frame camera. Figure 1is a conceptual diagram of a flood-illuminated fundus imager 10. A flash tube 15 is shown as the illumination source, with its illumination light following an optical path along an illumination axis 17, which may include various system lenses 19, before being folded by a reflector 23 onto an optical axis 25. Optical axis 25 includes a system lens 11 to transmit this illumination light to the specimen or sample to be imaged (e.g., the retina 33 of the eye 13 in this example). System lens 11 is the imager lens closest to the eye 13 and may be referred to herein as the eyepiece or ophthalmic lens. Optical axis 25 traverses the optical components of the eye 13 (including the cornea 27, iris 28, pupil 29, and lens (or eye lens) 31) to the retina 33. Thus, illumination light traveling along optical axis 25 can enter the eye 13 through the eye's cornea 27, pass through the eye's pupil 29, and traverse the lens 31 to the retina 33 at the back of the eye (e.g., the fundus region) and be scattered by the retina 33 (and other portions of the fundus). Scattered light returning from the fundus 33 can exit through the lens 31, pupil 29, and cornea 27 and travel along the optical axis 25 to the observation axis 35. The observation axis 35 may include a plurality of system lenses 21 and direct the scattered light returning from the fundus to a full-frame camera 37, which captures a full-frame image 39 of the fundus of the eye 13. Because the observation axis 35 and the illumination axis 17 are coincident along the optical axis 25, the reflector 23 typically has a centrally located aperture 43 for allowing scattered light returning from the eye 13 to pass through the reflector 23 onto the observation axis 35 for capture by the camera 37. The reflector 23 may be flat and annular (e.g., ring-shaped) with a circular aperture 43 at its center. If the reflector 23 is used for pupil segmentation, it may further be imaged onto the pupil 29.

[0004] Pupil segmentation allows illumination light (light entering eye 13) and return light (scattered light exiting the eye) to enter and exit eye 13 along different paths through optimally selected regions of pupil 29. These regions are selected, for example, to avoid pupil shearing, light scattering from cataracts, and specular reflections (e.g., reflections) of illumination light, such as from cornea 27. To facilitate pupil segmentation, a reflector 23 can be imaged at or near pupil 29, reflecting illumination light toward eye 13 while having an aperture 43 therein allowing return light to pass to camera 37. For example, when reflector 23 folds (e.g., reflects) illumination light from illumination axis 17 toward eye 13 onto optical axis 25, an annular illuminated region can be generated at eye 13. That is, the circular aperture 43 of reflector 23 can create a circular, non-illuminated region near cornea 27 at the center of the annular illuminated region. Scattered light returning from retina 33 can exit eye 13 through this non-illuminated region, thereby preventing illumination light from entering eye 13. In addition, specular artifacts from the optical surfaces of the flood-illuminated imager itself can be reduced by using so-called dark spots, which are fixed in the illumination path to prevent illumination of certain surface areas of the system's optics. Flood-illuminated imaging systems can image the fundus rapidly and with high signal levels and dynamic range, but may suffer from low contrast. The need to eliminate reflections can also impose constraints on the system, which may limit its FOV. An example of a flood-illuminated imaging system can be found in U.S. Patent No. 3,915,564, assigned to the same assignee as the present invention, and incorporated herein by reference in its entirety.

[0005] In contrast, scanning imagers illuminate and image only a portion of the sample at a time, collecting multiple image portions as the illumination beam is scanned across the sample. The multiple image portions are then stitched together, or mosaicked, to produce a composite image that constitutes the full-frame image. One advantage of scanning imagers over flood-illuminated imagers is increased parfocality, which enables greater discrimination of unwanted light scattered from surfaces other than the retina, allowing for wider FOV imaging without artifacts. Like flood-illuminated imagers, fundus scanning imagers encounter reflections from the various optical components of the eye and the various system lenses of the scanning imager itself, albeit to a lesser extent. Techniques used to reduce reflections from the optical components of the eye, such as pupil segmentation, can be applied to scanning imagers. Pupil segmentation can reduce reflections to some extent, but it cannot eliminate them. Its advantage is that it aims to minimize unwanted light from the eye, rather than from specific system lenses.

[0006] It is an object of the present invention to provide a scanning imager having a mechanism for directly reducing or preventing reflections from certain system lenses.

[0007] Another object of the present invention is to provide a fundus scanning imager that reduces reflections at a given target optics / lens of the fundus scanning imager. Summary of the Invention

[0008] The above objects can be achieved in systems, devices and / or methods for directly reducing or eliminating reflection artifacts at a given target optical device (e.g., system optical devices such as lenses, prisms, reflectors, etc.) in a scanning imager (or scanning illumination imaging system), particularly in a scanning imager configured as a fundus scanning imager. The scanning imager may include a radiation source (e.g., a light source) and a scanning component. The radiation source may be a coherent light source (e.g., a laser) or an incoherent light source (e.g., a lamp or a light emitting diode (LED)). The scanning component may be one or more galvanometers, microelectromechanical systems (MEMS) scanners, electro-optical deflectors, rotating mirrors and / or rotating polygon scanners or other scanning mechanisms. The scanning component receives a radiation stream (e.g., a laser beam or a light beam) from the radiation source and defines a scanning beam (e.g., by rotating a deflection mirror within the galvanometer). The scanning beam may be scanned across a sample to be imaged, thereby producing a moving illumination area on the sample. In the case of a fundus scanning imager, the sample would be the fundus (or retina) of the eye, and the scanning component could be imaged onto the pupil of the eye to facilitate pupil segmentation, as described above.

[0009] System optics (e.g., a scan lens and an eyepiece or ophthalmic lens) can direct a scanning beam from the scanning component to a sample to be imaged. The system optics can constitute an optics train that defines a radiation path (e.g., a light path) from the scanning component to the imaged sample. Optionally, a target optic from which reflections are to be eliminated can be selected from the optics train. The scanning beam can be scanned across the target optics. A radiation blocking component (e.g., a first light block) can be positioned to partially block the radiation flow output from the radiation source and limit the radiation received by the scanning component. Thus, the radiation blocking component can be positioned along the radiation path from the radiation source to the scanning component. The radiation blocking component can be imaged onto the target optics (e.g., positioned in a conjugate plane of the target optics) and create a moving non-radiating region (e.g., a first dark region) on the target optics through which the scanning beam of the scanning component cannot pass. The scanning beam can define a moving illumination region, and the non-radiating region can move along with the illumination region. Alternatively, the non-radiative region may block (or partially block) the overlap between the illumination region and the collection region through which scattered light returning from the sample may pass, particularly at the objective optics.

[0010] The scanning imager may include a collector (e.g., a photodetector, a photosensor, a charge coupled device (CCD) image sensor, or a complementary metal oxide semiconductor (CMOS) image sensor) for collecting scattered radiation (e.g., scattered light) returned from the sample through a collection region. The scanning imager may further include a collector blocking component (e.g., a second light block) positioned to partially block the collection region so as to block the amount of returned scattered radiation reaching the collector. The collector blocking component may be imaged onto a target optical device (e.g., a target optical device located in a conjugate plane of the target optical device) to produce a moving non-collection area (e.g., a second dark area) on the target optical device (or a second target optical device) through which scattered radiation returning from the moving illumination region cannot pass. The non-collection area may be moved by the scanning component and may overlap with the collection region. For example, the non-collection area may move with the non-irradiation area and the scanning beam and may block (or partially block) the overlap between the illumination region and the collection region, particularly at one or more target optical devices. Overlap between the blocked illumination area and the collection area can be achieved by having the non-collection and non-radiation regions abut or overlap each other, for example, as they move across one or more target optics (eg, merge / coincide with each other).

[0011] Blocking the overlap between the illumination area and the collection area on the target lens limits (or blocks) reflections from the target lens from reaching the collector, thereby helping to avoid reflection artifacts in the captured image. Therefore, for any given scanning position of the scanning component, it is desirable to minimize or eliminate the overlap between the illumination area and the collection area on the target lens. However, system focusing as part of a typical setup routine for an image capture sequence may defocus and / or shift the position of the non-irradiating and / or non-collection areas, resulting in increased overlap between the illumination area and the collection area. Various steps are contemplated to compensate for this defocusing effect.

[0012] Although it is desirable to completely block the overlap between the illumination area and the collection area, adjustments to the system focus can change (e.g., increase) the size of the overlap between the illumination area and the collection area. The size and position of the collector barrier and the radiation barrier can be selected so that the overlap between the mobile non-radiating area and the mobile non-collecting area on the target optics is sufficient to cover a predetermined increase in the overlap between the illumination area and the collection area, such as a defocusing effect caused by axial shifting of the position of the conjugate plane of the target lens relative to the collector barrier and / or the radiation barrier.

[0013] In the case where the scanning imager is a fundus scanning imager that images an eye with high myopia, the conjugate plane of the target lens may be moved (e.g., axially moved) relative to one or more blocking components as a result of compensating for the myopia of the eye. In some instances of severe myopia, due to the movement of the position of one or more blocking components relative to the illumination area and / or collection area, the non-collection area and / or non-illuminated area may restrict too much light (to or from the eye), resulting in a darkened image or a slower image capture cycle. In these extreme cases, it is desirable to accept a certain degree of reflection in exchange for a brighter image. That is, the collector blocking component and / or the radiation blocking component may be constructed to be movable (or removable) so as to limit its obstruction of the radiation path (e.g., the optical path). For example, the radiation blocking component may be positioned to partially block radiation output from the radiation source, the collector blocking component may be positioned to partially block scattered radiation returned from the moving collection area, or the radiation blocking component may be positioned to not block radiation output from the radiation source, and / or the collector blocking component may be positioned to not block scattered radiation returned from the moving collection area.

[0014] Alternatively, if the scanning imager has a focusing mechanism that causes the conjugate plane of the target optics to move (e.g., axially) when the sample is focused on the collector, the collector blocking member and / or the radiation blocking member can move with the conjugate plane of the target optics to remain substantially in the conjugate plane of the target optics. This can be due to, for example, movement of the optics between the blocking member and the target lens (including the target lens) when the focus is adjusted for myopia of the eye. In other words, one or more blocking members can be moved when the focus is adjusted to remain in the conjugate plane of the target lens. Alternatively, the position of the radiation blocking member can remain stationary regardless of the movement of the conjugate plane of the target optics.

[0015] As a further alternative, the relative positions of the collector barrier, the scanning component, and the target optics can be independent of the focusing mechanism. For example, the focusing optics can be positioned between the collector barrier and the collector such that even as the focusing optics focus the sample on the collector, the relative positions of the optics along the optical path of the return scattered radiation from the target optics to the collector barrier (including the scanning component) remain fixed.

[0016] In addition, changes in the position of the blocking component relative to the illumination plane and / or the collection plane may affect the amount of light captured. Such changes in position may be due to movement in the optical chain (e.g., movement between the radiation source and the radiation blocking component and / or movement between the collector and the collector blocking component), or may be due to movement of the blocking component to maintain the blocking component in a conjugate plane of the target lens, as described above. Such changes in position may result in increased blockage of light when adjusting the camera focus for greater myopia. Therefore, for more myopia, the amount of blocking provided by either blocking component may be adjusted to allow more light to pass, even if this results in some increased reflection back to the collector.

[0017] In certain embodiments, the radiation blocking component may be coplanar with the collector blocking component. This may simplify the design and alignment of the scanning imager. Additionally, an illumination aperture on a conjugate plane of the surface of the sample to be imaged (e.g., the retina of the eye in the case of a fundus imager) may be placed in front of the radiation source to construct (e.g., shape) its output radiation beam. In this case, the illumination aperture may be between the illumination source and the radiation blocking component. Similarly, the scanning imager may have a collection aperture on a conjugate plane of the surface (optionally, the same surface) of the sample to be imaged (e.g., the retina of the eye). In this case, the collection aperture may be positioned between the collector and the collector blocking component, and the illumination aperture may be coplanar with the collection aperture. The illumination aperture may match the collection aperture and may be on a conjugate plane of the collection aperture on the light sensor (e.g., the collector).

[0018] Optionally, the scanning imager may further include a pupil-splitting aperture defining a segmentation region that separates a scanned beam of radiation in front of a sample (e.g., the retina or fundus) from scattered radiation returning from the sample. For example, in the case of pupil segmentation in a fundus imager, the pupil-splitting aperture may be positioned substantially immediately before the scanning component in the radiation path from the radiation source to the scanning component. The segmentation region may define a first sample opening through which the radiation beam from the radiation source reaches the scanning component, and may define a second sample opening through which scattered radiation returning from the sample passes. The first sample opening and the second sample opening may be coplanar. In this configuration, the scanning imager may further include a dual lens, embodied as two coplanar lenses molded into a single optical component, and including a first sub-lens aligned with the first sample opening and a second sub-lens aligned with the second sample opening. A structure (e.g., a wall) may maintain alignment between the first sample opening, the first sub-lens, the radiation blocking component, and the illumination aperture, and maintain alignment between the second sample opening, the second sub-lens, the collector blocking component, and the collector aperture. This structure can also be used to prevent light from leaking from the first sample well side to the second sample well side.

[0019] In the case where the scanning imager is a fundus imager, the target lens may be a transmissive lens. For example, the target lens may be the lens closest to the sample (e.g., the fundus) along the radiation path from the scanning component to the sample. Alternatively, the target optical device may be, for example, a scanning lens between the scanning component and the sample, whose function is generally to receive the scanning beam from the scanning component at an incident angle and output the scanning beam along a predetermined, generally collimated path.

[0020] The scanning imager may be a confocal point scanning imager or a line scanning imager. As will be appreciated, a line scanning imager (or line scanning ophthalmoscope) may include both a line scanning laser scanner / ophthalmoscope (LSLO) and a wide line scanning (fundus) imager / ophthalmoscope (BLFI). In the case where the scanning imager is a line scanning imager, the radiation beam may be a substantially rectangular radiation beam. The rectangular radiation beam may have a (optionally fixed) length dimension and may have a variable width dimension that is substantially perpendicular to the length dimension.

[0021] The present scanning imager can be implemented in different types of scanning configurations. For example, the scanning imager can be a scan-non-descan system, a scan-descan system, or a scan-descan-rescan system.

[0022] Other objects and purposes and a more complete understanding of the present invention will become apparent and readily appreciated by referring to the following detailed description and claims in conjunction with the accompanying drawings.

[0023] The embodiments disclosed herein are merely examples, and the scope of the invention is not limited to these embodiments. Any embodiment feature mentioned in one claim category (e.g., method) may also be claimed in another claim category (e.g., system). Dependencies or references in the appended claims are selected for formal reasons only. However, any subject matter derived by careful reference to any previous claim may also be claimed, so that any combination of claims and their features may be disclosed and claimed, regardless of the dependencies selected in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In the drawings, wherein like reference symbols / numerals refer to like parts:

[0025] Figure 1 This is a conceptual diagram of a flood-illuminated fundus imager.

[0026] Figure 2 A generalized confocal point-scanning fundus imager is shown.

[0027] Figure 3 A simplified exemplary scanning pattern of a confocal point scanning fundus imager (or more generally, a point confocal scanning system) is shown.

[0028] Figure 4 A simplified exemplary scanning pattern for a line (confocal) scanning system is shown.

[0029] Figure 5A 、 Figure 5B and Figure 5C Each shows exemplary illuminated broad lines (or slits) of different sizes and widths, such as may be used with a line scan fundus imager.

[0030] Figure 6A shows an idealized scanning configuration for a so-called "scan-not-descan" system, where, when scanning a sample, a traversing line beam will cross a line of the sample (e.g., see Figure 4 、 Figure 5A 、 Figure 5B and Figure 5C ) illumination, and allowing the returning reflected / scattered light to be similarly scanned across a collector (e.g., a light detector or camera), which may optionally be coupled to a CPU for further processing and a monitor for display, such as Figure 2 shown.

[0031] Figure 6B An idealized scanning configuration for a so-called "scan-descan" system is shown, in which a line beam is scanned across the sample, but the line of returning scattered light is maintained at a single predetermined position on the collector rather than being scanned across the collector.

[0032] Figure 6C An example of a so-called "scan-descan-rescan" system is shown, in which a secondary scanning mechanism is incorporated into the scan-descan system to rescan (e.g., rescan) the returned scattered light generated by the scan-descan system before it reaches the collector, but is otherwise unscanned, thereby rescanning the returned scattered light across the collector. Optionally, this rescanning functionality can be provided by a second scanning component, or by a different portion of the scanning component that scans the scanning beam across the sample. For example, rescanning can be accomplished by using the back side of a single scanning component, or a different location on a single scanning component, that also scans the scanning beam across the sample.

[0033] Figure 6D shows the integration of a spherical mirror into a Figure 6C Scan - Descan - Rescan the system.

[0034] Figure 7 An example of an alternative scan-descan configuration for a line-scan fundus imager incorporating the present invention is shown.

[0035] Figure 8 Provided Figure 7A simplified, not-to-scale, close-up view of an ophthalmic lens, showing an illumination block after imaging (e.g., a non-illumination area), a collection block after imaging (e.g., a non-collection area), an illumination window through which the scanning light beam from the scanning component can pass to the eye, and a collection window through which the return light from the eye can pass to the collector.

[0036] Figure 9 An example of an alternative scan-descan-rescan configuration for a line scan fundus imager incorporating the present invention is shown.

[0037] Figure 10 The conceptual design of a compound double lens is shown.

[0038] Figure 11 An alternative configuration of a beam stop for adding imaging to an ophthalmic lens / eyepiece in a scan-descan-rescan line scanning system using a compound dual lens is shown.

[0039] Figure 12 An example computer device (or CPU or computer system) is shown. DETAILED DESCRIPTION

[0040] Two types of scanning imagers are confocal point scanning imagers (which use a laser spot beam to scan a sample one point at a time) and line scanning imagers (which use a narrow line beam or a wide line of light (e.g., a linear slit of a predetermined width) to scan a sample one line at a time). In the field of fundus imaging, line scanning imagers may be referred to as line scanning ophthalmoscopes and include line scanning laser imagers / ophthalmoscopes (LSLOs), which typically use a laser to generate a very narrow transverse line across the sample as it scans, and wide line scanning (fundus) imagers / ophthalmoscopes (BLFIs), which may use an incoherent light source to generate a wide transverse line (or slit) of a predetermined width across the sample as it scans. Hereinafter, the term line scanning imager may be understood to refer to both laser line (or very narrow line) scanning imagers (e.g., LSLOs) and wide line scanning imagers (e.g., BLFIs).

[0041] A scanning imager typically captures scattered light returned from each scanned location of a sample (e.g., by using a collector, such as a light detector or light sensor), and stitches the captured scanned locations together to produce a composite image of the sample, which composite image may define a full-frame (e.g., full field of view, FOV) image. For ease of discussion, embodiments of the present invention describe using a scanning imager to image the fundus of an eye, which is the inner surface of the eye opposite the lens of the eye (e.g., crystalline lens) and may include the retina, optic disc, macula, fovea, and posterior pole. That is, the present scanning imager is presented in the context of a fundus scanning imager, but it will be understood that the present invention is equally applicable to scanning imagers optimized for other uses, such as imaging samples other than the eye.

[0042] Each type of scanning imager has its advantages and disadvantages and can be optimized for various applications. For example, confocal point-scan imagers inherently avoid out-of-focus light, but because each imaged point (e.g., each captured scanned position) corresponds to an image pixel, they must scan across the sample both horizontally and vertically to construct a composite, full-frame image. This can result in relatively long image capture times. Line-scan imagers typically achieve confocal measurements across their width (perpendicular to the length of the scan line or line beam) and can scan across the sample more quickly than point-scan imagers. However, at least in the case of wide-line scan imagers, if the scanned line beam is too narrow, the captured image may not achieve the desired brightness. Nevertheless, wide-line scan imagers avoid the need for a laser source, making them more cost-effective than the other two scanning imagers. Furthermore, wide-line scan imagers can generate scanned line beams of varying widths to increase the amount of light applied to the scanned sample during each capture sequence, resulting in brighter images, albeit at the expense of reduced confocality.

[0043] When imaging the fundus using a scanning imager, it is generally desirable to avoid collecting (e.g., capturing or imaging) extraneous light, as well as reflections from the cornea and light scatter from the lens of the eye (e.g., such as due to cataracts). The sequential illumination and collection of separate, targeted scanned locations of the retina / fundus inherent to the scanning imager reduces the collection of unwanted light from areas outside the fundus (e.g., peripheral), but eliminating / reducing unwanted reflections and light scatter from the eye may require a more direct approach. The scanning beam traversing the cornea and lens of the eye causes reflections from the cornea and light scatter from the lens of the eye as the scanning beam enters the back of the eye. These problems can be addressed by a technique known as pupil segmentation, which blocks reflections from the cornea and light scatter from the lens of the eye by providing different paths in optimally selected areas of the pupil for the scanning beam entering the eye and the return (scattered) light exiting the eye. For example, these regions may be selected to avoid pupil clipping (e.g., blockage of a portion of the light beam by the iris whose center defines the pupil), light scattering by cataracts (e.g., cloudy regions of the lens of the eye), and specular reflections (e.g., reflections) of the illumination light (e.g., such as specular reflections caused by a scanning beam striking the cornea as the illumination light enters the eye). In essence, pupil segmentation defines a pupil illumination region (or window) through which the scanning beam enters the eye to illuminate a particular scanning location on the fundus, and a pupil collection region (or window) that determines which portion of the scattered light leaving the eye is collected (by a collector) to capture an image of the scanned location. Pupil segmentation can be used in line scanning fundus imagers, but is generally not considered necessary in confocal scanning fundus imagers. Another advantage of pupil segmentation is that it can tend to keep the illuminating scanning beam and the returning scattered light separated not only at the pupil, but also in areas close to the pupil (e.g., at the cornea). Due to the defocusing of the pupil illumination area and the pupil collection area, the ability of pupil segmentation to separate the scanning beam from the returning scattered light becomes weaker when leaving the pupil.

[0044] The above-mentioned scanning imagers can use different radiation sources (for example, lasers for coherent point scanning imagers and laser line scanning imagers, and incoherent light sources such as lamps or one or more light-emitting diodes (LEDs) for wide line scanning imagers), but each scanning imager will generally generate a radiation stream or radiation beam that is transmitted (along a radiation path) to a scanning mechanism / component (for example, one or more galvanometers (or galvanometers), a MEMS scanner, an electro-optical deflector, and / or a rotating polygon scanner). The radiation beam (or illumination beam) output from the radiation source can be shaped by placing a slit (for example, a specifically configured hole) in front of the radiation source. The slit hole can be imaged onto the fundus (for example, a conjugate plane of the fundus) or onto any surface to be imaged. The scanning component receives the radiation beam from the radiation source and generates a scanning beam that scans in a specific pattern. From the scanning component, the scanning beam leaves the scanning imager along an optical device system (which defines a scanning path) and scans across a sample (for example, the fundus). The optical system typically includes a scanning lens in front of the scanning element (along the scanning path), followed by one or more optical devices (e.g., lenses or lens structures) that direct the scanning beam to the object to be imaged. In the case of a fundus imager, the lens closest to the eye (along the scanning path) can be called the ophthalmic lens or eyepiece.

[0045] One problem inherent in such scanning imagers is reflections (e.g., light reflections) at system lenses (or other optics) within the scanning imager along the illumination path and / or collection path of the scanning imager. The present invention provides methods, systems, or apparatus for eliminating (or reducing) reflections at one (or more) target optics (e.g., system optics) within a scanning imager. In the case of fundus imagers, reflections at the lens closest to the eye (e.g., the sample being imaged) are typically of concern, and some embodiments are presented herein in the context of eliminating reflections at the lens closest to the eye (e.g., an ophthalmic lens), but it will be understood that the present invention is applicable to another target lens (or other target optic) within a scanning imager.

[0046] In embodiments, a radiation stop (e.g., an illumination stop or radiation blocking component or beam stop) that is imaged onto an ophthalmic lens (or other target optical device of a system where reflections are eliminated / reduced) is placed between the radiation source and the scanning component to partially block the radiation beam received by the scanning component. The radiation stop or beam stop can be constructed using a foil or metal plate with openings, a filter, or other light blocking mechanism that selectively blocks portions of the beam while allowing other portions to pass. The radiation stop can be on a conjugate plane of the ophthalmic lens and creates a non-irradiating zone (non-illuminated zone) that is scanned (e.g., moved) across the ophthalmic lens as the scanning component scans the radiation beam from the radiation source. The non-illuminated zone creates a moving area of ​​no (or reduced) reflection on the ophthalmic lens adjacent to the scanned beam generated by the scanning component. In embodiments, the radiation stop can be placed in front of the radiation source, for example, in front of a slit aperture of the radiation source. If pupil-splitting optics are positioned in front of the radiation source, the pupil-splitting optics can be placed between the illumination stop and the scanning component. As will be appreciated, the illumination block may be imaged substantially to the ophthalmic lens, the pupil splitting optics may be imaged substantially to the eye pupil (or cornea), and the slit aperture may be imaged substantially to the fundus (or retina).

[0047] In embodiments, another radiation block (e.g., a collection block or collector blocking component) may also be imaged onto the ophthalmic lens (or another system's target optics where reflections are eliminated / reduced) and may be placed in the optical path from the scanning component to the collector. The collection block may be located on a conjugate plane of the ophthalmic lens and create a non-collection zone on the ophthalmic lens that is scanned (e.g., moved) across the ophthalmic lens adjacent to (scattered) return light from the eye toward the collector. Thus, a portion of the scattered radiation (e.g., light) returning from the fundus (e.g., sample) may be blocked by the non-collection zone, thereby creating a second, moving region of no (or reduced) reflection on the ophthalmic lens (or other target optics). In some embodiments, reflections on the ophthalmic lens may be further reduced by arranging the non-collection zone to partially overlap the non-illuminated zone as they move in tandem across the ophthalmic lens. The collection block may be placed in front of the collector. If a collection aperture (e.g., a pinhole or slit through which light enters the collector) is placed in front of the collector, the pinhole may be placed between the collector and the collection block. In this case, the collection aperture can be imaged onto the fundus of the eye (or retina) and the collection stop can be imaged onto the ophthalmic lens (or other target optics). The collector can also be imaged onto the fundus, in which case the collection aperture can be slightly out of focus on the retina.

[0048] The present invention can be implemented as part of a confocal point scanning imager or line scanning imager. A point confocal scanning imager, such as a (fundus) confocal scanning laser ophthalmoscope (cSLO), can use a laser (or other bright, confocal light source) to illuminate and image a small point (or spot) of the retina at a time.

[0049] Figure 2A generalized confocal point scanning fundus imager 51 is shown. A laser or other light source, such as a superluminescent diode (SLD) (e.g., a radiation source) 53 emits a spatially coherent point beam that passes through an optional aperture 55 and a collimating lens 57, through a beam splitter 59, and to a scanning component, which in this example includes two galvanometers 61 and 63 (e.g., servo-controlled rotating (or oscillating) mirrors). The first galvanometer 61 can provide vertical scanning (e.g., V scanning) of the point beam (e.g., providing scanning in the Y-axis direction, which can define a column of illumination points on the sample to be imaged), and the second galvanometer 63 can provide horizontal scanning (e.g., H scanning) of the point beam (e.g., providing scanning in the X-axis direction, which can define a row of illumination points on the sample). For example, the H scanning galvanometer 63 can rotate the mirror to horizontally scan the point beam in discrete steps (or continuous, definable steps) to define a row of points. Once a row of dots is complete, the V-scan galvanometer 63 can rotate its mirror vertically to move the scanning beam to a new vertically offset position in preparation for scanning a new row. The function of the scan lens 67, which is in the optical path between the scanning assembly and the eye 75, is generally to receive the scanning beam from the H-scan galvanometer 63 at any one of a plurality of scanning angles (angles of incidence) and generate a scanning beam 69 using a substantially flat surface focusing plane (e.g., a collimated optical path). The scanning beam 69 can then be focused by the ophthalmic lens 71 onto the retina 73 of the eye 75 to image the fundus. Scattered light leaves the eye 75 and returns through the ophthalmic lens 71, the scan lens 67, and the galvanometers 61 and 63 to the beam splitter 59. Because the return path of the scattered light from the eye 75 is similar to that of the scanning beam, the galvanometers 61 and 63 have the effect of "de-scanning" (or not scanning) the returning light so that it is a stable beam (non-scanning) when it reaches the beam splitter 59. At the beam splitter 59, the returning light is directed to another focusing lens 77, which focuses the returning light beam onto a photodetector 79 via a pinhole 81, which can be optically conjugate with the retina 73 and helps eliminate out-of-focus signals (light). Each illuminated point is imaged (e.g., captured or detected) separately by the photodetector 79, and as the point beam from the scanning component is scanned across the sample in a raster pattern, a series of imaged points are collected to construct a composite image of the retina 73. That is, the signals (e.g., light points) detected by the photodetector 79 can be processed by a computer or CPU 83 to form a confocal (full-frame) image 84. The resulting confocal image 84 can be displayed on a video display 85 or stored for further processing. An example of a point confocal scanning system integrated into an optical coherence tomography system is provided in U.S. Patent No. 8,783,868, which is assigned to the same assignee as the present invention and is incorporated herein by reference in its entirety.

[0050] As described in further detail below, optionally, an illumination stop 87 that is imaged onto the ophthalmic lens 71 can be positioned in front of the radiation source 53 to create a moving non-illuminated area on the ophthalmic lens 71 adjacent to the scanning beam output from the scanning component (e.g., the scanning beam output from the galvanometer 63). The non-illuminated area prevents (or reduces) reflections due to the scanning beam. Similarly, optionally, a collection stop 89 can be positioned in front of the light detector 79, and the position of the collection stop 89 is selected so that the optics in the system form an image of the collection stop 89 at a surface position of the ophthalmic lens 71 (e.g., the collection stop 89 is located in a conjugate plane of the surface of the ophthalmic lens 71) to create a moving non-collection area on the ophthalmic lens 71 that prevents (or reduces) reflections due to returned scattered light from the eye 75.

[0051] Figure 3 A simplified exemplary scanning pattern of a confocal point scanning fundus imager (or more generally, a point confocal scanning system) is shown. It will be appreciated that other scanning patterns are also possible. In this illustrative example, each point Sp_1 to Sp_n is captured separately and individually in the scanning pattern. Since only one point in the sample is illuminated and captured at a time, imaging typically requires scanning a regular raster (e.g., a rectangular pattern of parallel scan lines) on the sample (e.g., the retina or fundus). For example, the laser scanning beam is scanned across the sample in the XY plane (perpendicular to the main axis direction of the scanning beam (e.g., the Z axis)) using a scanning component (e.g., galvanometer mirrors 61 and 63). Individual rows of points (e.g., R1 to Rm) are captured one by one in corresponding individual horizontal scans (H scans), and the scanning beam is vertically scanned in progressive steps of a single-row-offset (e.g., a vertical step after each horizontal scan) to define a vertical scan (V scan). Generally, slower scanning provides a better signal-to-noise ratio, resulting in better contrast and higher resolution.

[0052] Due to the point confocal arrangement of illumination and detection, confocal scanning imagers can advantageously suppress stray light and out-of-focus light, thereby producing high contrast images without the need for pupil segmentation. However, because they operate using point illumination, they may require high intensity, which can cause safety issues when imaging the retina. Similarly, because most of the light from the sample is blocked at the pinhole 81, the improvement in resolution usually comes at the expense of reduced captured signal intensity, so that exposure time may need to be extended. In addition, confocal point scanning fundus imagers typically require multiple scanning mechanisms to achieve horizontal and vertical scanning (e.g., a galvanometer 63 for horizontal scanning and a galvanometer 61 for vertical scanning), which is expensive and complex and slows down their image generation because many points need to be collected to construct a full-frame composite image. This can also cause problems with eye movement during image construction, which can cause image distortion.

[0053] Line scan imagers differ from confocal scanning imagers in that they use a line beam that spans a specific width of the sample, rather than a point beam. Consequently, line scan imagers can capture an entire row (or column) of image data at once and require a simpler scanning component (e.g., one less galvanometer than the confocal point scanning fundus imager described above). In some embodiments, line scan imagers may also include a second scanner to allow imaging over a field of view wider than the line. Alternatively, the entire optical head of the system is manually rotatable to allow illumination over a wider field of view.

[0054] Figure 4 A simplified exemplary scanning pattern for a line scanning system is shown. In this example, a transverse line beam is generated by a radiation source (not shown) and is scanned vertically (e.g., by using a vertical scanning galvanometer, such as Figure 2 galvanometer 61) to generate a plurality of scan lines L1 to Li in a vertical scan mode (V scan). As mentioned above, the two types of line scan imagers are laser line scan imagers and wide line scan imagers. For ease of discussion, scan lines L1 to Li may represent line scans generated by a laser line scan imager or a wide line scan imager, and it will be understood that the scan lines generated by a laser line scan imager are generally much narrower than the scan lines generated by a wide line scan imager. In general, a line scan imager may maintain a line scan perpendicular to (e.g., along) a line scan line. Figure 4 Some degree of confocal suppression of out-of-focus light along the scan line (L1 to Li) (Y axis in FIG), but lack of confocal suppression along the line (e.g., along Figure 4Line scan systems have been combined with pupil segmentation (e.g., see U.S. Patent No. 8,488,895 to Muller et al., which is incorporated herein by reference in its entirety). Advantageously, line scan imagers can scan across the retina (or fundus) faster than confocal point scan imagers and are therefore less sensitive to motion artifacts, but at the expense of less rejection of defocus. However, variations in line intensity or linear array sensitivity in line scan systems can result in tailings in the captured image.

[0055] Wide line scan imagers strive to combine some of the advantages of laser line scan imagers with those of flood illumination imagers. Wide line scan imagers use a much wider illumination line (or slit) than laser line scan imagers and therefore can have a much larger etendue. This allows the use of incoherent light sources (e.g., non-laser sources), such as one or more lamps or one or more LEDs, which are generally inexpensive and can provide broadband illumination, which can help achieve more natural images.

[0056] Figure 5A 、 Figure 5B and Figure 5CEach of the exemplary wide lines (or illumination slits) 43A, 43B, and 43C of different sizes used to illuminate the corresponding fundus region 41A, 41B, and 41C is shown. In each figure, the illumination slits 43A, 43B, and 43C are schematically shown as different widths. Each illumination slit 43A, 43B, and 43C corresponds to the position of the scanning beam on the fundus at a particular scanning step or time. It is noted that the scanning beam can be scanned smoothly across the retina or moved in steps. Increasing the width of the illumination slit, such as slit 43C compared to strip 43A, increases the amount of light applied and can improve the dynamic range. In the case where the illumination is not significantly moved during detector acquisition (typically when the scanning beam is scanned in steps and is relatively stationary during acquisition), the sharpness of the edges of the illumination strips can be used to find the optimal focus for the line scanning system. Various image processing techniques can be further used to improve the constructed image. For example, unilluminated locations on the retina (e.g., captured images) can be detected to assess background levels, such as stray light levels, from out-of-focus regions of the eye. This background level can then be subtracted from the captured line image, for example, from illumination slits 43A, 43B, or 43C. Furthermore, the size of each vertical scanning step can be smaller than the width of the illumination slit, so that multiple consecutive illumination slits cover the same region of the retina. In this way, multiple image captures will image the same region of the retina. This allows for the use of various image processing techniques (e.g., averaging) to improve the image quality of individual regions. Alternatively, the best image quality of an individual region can be selected for stitching into the final composite image. Furthermore, a variety of pupil segmentation configurations can be used with wide-line imaging systems. For example, pupil segmentation for illumination and detection can be implemented closer to the cornea than with flood-illuminated fundus imagers, and instead of illuminating an annular ring (as described above with reference to flood-illuminated fundus imagers), an illumination slit can be used. Examples of wide line (slit) scanning imagers are provided in U.S. Publication No. 2017 / 0049323 and U.S. Publication No. 2018 / 0014727, both of which are assigned to the same assignee as the present invention, and the entire contents of which are incorporated herein by reference.

[0057] The (fundus) scanning imagers described above can use a variety of scanning configurations. For illustrative purposes, some simplified scanning configurations are presented herein in the context of line scanning imagers (e.g., imagers using a scanning line beam), but these configurations can also be applied to point scanning imagers, as will be understood by those skilled in the art.

[0058] Figure 6A A scanning configuration (a so-called "scan-not-descan" system) is shown, wherein when the line beam 115 is scanned in another dimension (e.g., the Y dimension), such as in Figure 4 、 Figure 5A 、 Figure 5B and Figure 5C As shown in FIG, a transverse line beam 115 illuminates lines L1 to Li across the sample 109 in one dimension (e.g., the X axis). Return (e.g., reflected or scattered) light 116 is similarly allowed to scan across a collector 107 (e.g., a photodetector or camera), which may optionally be coupled to a CPU for further processing and a monitor for displaying a full-frame image, such as a Figure 2 As shown. Figure 6A In this example, the collector 107 can be a full-frame digital camera, and the return light 116 can "paint" a full-frame image as it scans across the camera's two-dimensional (2D) light sensor (e.g., a 2D array of light detectors). That is, each detected line of return light 16 can be captured at a different location on the camera, buffered, and processed to construct a composite full-frame image, either in a single acquisition or through multiple acquisitions that make up the full frame (e.g., by moving a series of line illuminations to additional horizontal positions on the sample). A radiation source 101 (e.g., a light source such as a laser, lamp, or LED) generates an illumination line beam 103 (an incoherent beam or laser beam). A radiation aperture 105, which is imaged onto a sample 109 (e.g., a surface to be imaged), can be placed in front of the radiation source 101 to help shape the illumination line beam 103. In the case of a fundus scanning imager, the radiation aperture 105 can be imaged onto the retina of the eye. The illumination line beam 103 may pass through one or more optical devices (e.g., lenses) 111 before reaching a scanning component (e.g., a galvanometer) 113, which generates a scanned radiation line beam (e.g., a scanned line beam 115) that defines an illumination line L1 to Li across the sample 109. It will be appreciated that in a more practical application, the scanned line beam 115 output from the scanning component 113 may pass through a scan lens 117 and an ophthalmic lens 119 before reaching the sample 109 (e.g., the retina or fundus of the eye), as described above with reference to FIG. Figure 2 In this example, the line beam 115 output from the scanning component 113 is vertically along the sample 109 in steps (for example, Figure 4 The scattered light 116 returned from the sample 109 can pass through an aperture 123 in the scanning element 113 (or otherwise be transmitted from the sample 109) to the collector 107 and can be similarly vertically scanned in corresponding steps on the collector 107. A more practical application may include a focusing lens 121 in front of the collector 107. In the case of a fundus scanning imager, the scanning element 113 can be substantially optically conjugate with the pupil of the eye.

[0059] As described in further detail below, an illumination stop 125 that is imaged onto the target optics (e.g., the ophthalmic lens 119) can be positioned in front of the radiation source 101 to create a moving non-illuminated region on the target optics that can be adjacent to the scanned beam 115 output from the scanning component 113. The non-illuminated region prevents (or reduces) reflections due to the scanned beam 115.

[0060] Figure 6B An idealized scanning configuration for a so-called "scan-descan" system is shown, in which the scan line beam 115 is scanned across the sample 109, but the line of returned scattered light 139 is maintained at a single predetermined position on the collector rather than being scanned across the collector. Figure 6B Zhongyu Figure 6AAll elements that are identical in the present invention have the same reference numerals and are described above. Because the return line of scattered light 139 is not scanned, this scanning configuration allows the use of a line scan camera 131 as a collector. Alternatively, a full-frame digital camera having a line, such as a row of pixels (or a predetermined number of pixel rows to define a broad line) within its 2D array is designated as a region of interest (ROI), and the designated ROI is used to receive and capture the return light 139. In this example, a radiation source 101 generates an illumination line (or broad line / slit) (e.g., a line beam) 103, which passes through a beam splitter (beam splitter) 133 onto an optical path 135 to a scanning component (e.g., a galvanometer) 137. The scanning component 137 converts the received illumination beam into a scanned beam that is scanned across the sample 109. As described above, in a more practical application, the light from the scanning component 137 may pass through a scanning lens 117 and an ophthalmic lens 119 before reaching the sample 109 (e.g., the retina or fundus of the eye). In this example, the scanning component 137 can vertically scan the scanning beam 115 along the sample in discrete scanning steps, but other scanning directions can also be used. At each scanning step, light is reflected / scattered back (in the capture phase) to the scanning component 137. For the purposes of discussion, it can be assumed that the scanning component 137 is substantially stationary during this capture phase and therefore reflects the return light along the same optical path 135 as the incident light from the radiation source 101. Therefore, the optical path 135 can be referred to as a shared path, as shown by the double arrow. The returned, fixed scattered light is guided by the beam splitter 133 onto a collection path 139, which transmits it to a light detector, such as a line scan camera 131. As shown, the position of the returned scattered light on the collection path 139 is substantially fixed, regardless of the vertical scanning position of the line beams L1 to Li on the sample 109, which is referred to herein as a "de-scanning" operation. This allows the use of a line scan camera 131, which may contain a single row of pixels for very rapid data capture (e.g., using a fast CCD sensor or CMOS image sensor). The captured light from each discrete scan step may be captured and mapped to a location in a buffer 141 corresponding to the scan position of the corresponding scan line L1 to Li. The buffered line images may then be reconstructed (e.g., spliced ​​or stitched) into a full-frame image, such as by using a CPU (e.g., a computing system or device), and presented on a computer display, such as Figure 2 shown.

[0061] Optionally, an illumination stop 125 can be used to reduce or eliminate reflections at the target optics. The illumination stop 125 can be positioned in front of the radiation source 101 and can be placed in a conjugate plane with the target optics (e.g., the scan lens 119). Due to the scanning action of the scanning component 137, a moving non-illuminated area is created on the target optics, which can be adjacent to the scanned beam 115 output from the scanning component 137. The non-illuminated area prevents (or reduces) reflections from the target optics due to the scanned beam 115. Optionally, a collection stop 143, which is imaged onto the same target optics, can be positioned in front of the collector (e.g., the line scan camera 131). The use of the collection stop 143 is facilitated because the returned scattered light on the collection path 139 is relatively stationary (e.g., not scanning). Thus, a moving non-collection area can be created on the target optics (e.g., the ophthalmic lens 119) that prevents (or reduces) reflections due to the returned light from the sample 109. The non-collecting region and the non-radiating region may abut or overlap each other when they are moved on a conjugate plane of the target optics or directly on the target optics.

[0062] Further reduction of reflections can be achieved by using crossed polarizers. That is, introducing two polarizers that are orthogonal to each other in a crossed polarizer configuration, for example, polarizers in each of the illumination and detection (collection) paths can further reduce reflections. For example, a first polarizer can be positioned in the illumination path and a second polarizer that is in an orthogonal state (for example, rotated 90 degrees relative to the first polarizer) can be positioned in the detection path. The polarizers can be anywhere in these paths, but preferred embodiments can have them located in stationary portions of the paths, for example, a first polarizer can be positioned in the illumination path from the light source 101 to the sample 109 (for example, the eye) before the scanning mirror 137 and a second polarizer can be positioned in the collection path 139 after the scanner 137 (for example, in the descanned portion of the optical (collection) path from the sample (for example, the eye) to the collector).

[0063] Figure 6A Some advantages of the scan-non-descan system (such as a simplified image capture structure) and Figure 6B Some of the advantages of the scan-descan system (such as helping to collect unscanned, stable return light used by block 143) can be achieved in a third scanning configuration, which is referred to herein as "scan-descan-rescan". Figure 6CA simplified scan-descan-rescan system is shown, wherein an auxiliary scanning mechanism is incorporated into the scan-descan system so that returned, scattered light generated by the scan-descan system is rescanned (e.g., rescanned) before it reaches a collector and is otherwise not scanned (e.g., descanned), thereby rescanning the returned scattered light across the collector. Figure 6C Zhongyu Figure 6A and Figure 6B All elements that are the same in FIG. 1 have the same reference numerals and are described above. As previously described, a radiation source 101 having an optional aperture 105 and a collimating lens 111 generates an illumination line beam 103 that passes through a beam splitter 133 onto an optical path 135 to a scanning component (e.g., a galvanometer) 137. The scanning component 137 converts the received illumination beam into a scanning beam (e.g., a scanning line beam 115) that can pass through a scanning lens 117 and an ophthalmic lens 119 to scan across a sample 109 (e.g., the retina or fundus of an eye). As described in Figure 6B In this case, the light returned from the sample 109 is descanned by the scanning component 137 to generate a substantially stable return line beam on the optical path 135, which is guided by the beam splitter 133 to the collection path 139. At this time, the descanned return light on the collection path 139 is guided to the second scanning mechanism along the optical paths 153a and 153b by using one or more mirrors 151a / 151b. In this example, the back surface of the galvanometer mirror (scanning component 137) is reflective and serves as the second scanning mechanism to rescan the return light and define the rescanned collection beam 116b on the collector 107 via the focusing lens 121. Since the scanning beam 115 and the rescanned collection beam 116b are defined together by the scanning component 137, they correspond to each other.

[0064] As in Figure 6A In the case of , the illumination stop 125 can be used to reduce or eliminate reflections at the target optics (such as the ophthalmic lens 119). That is, the illumination stop 125 can be positioned in front of the aperture 105 and the radiation source 101 and can be imaged onto the target optics (e.g., the back surface or the front surface of the target optics). This creates a moving non-illuminated area on the target optics that can be adjacent to the scanning beam 115 output from the scanning component 137. In addition, the collection stop 143 can be used before rescanning of the return light that defines the rescanned collection beam 116b. That is, the collection stop 143 can be optionally positioned along any of the optical paths 139, 153a, or 153b. As in Figure 6BIn such cases, the collection stop 143 can be imaged onto the same target optic where it is desirable to reduce reflections due to returned scattered light. The use of the collection stop 143 is facilitated because the returned light between the collection stop 143 and the beam splitter 133 is relatively stationary (e.g., not scanning) on ​​the collection path (e.g., 139, 153a, and / or 153b). Thus, a moving non-collection zone can be created on the target optic (e.g., the ophthalmic lens 119) that prevents (or reduces) reflections due to returned light from the sample 109. As previously described, the non-collection zone and the non-radiating zone can abut or overlap each other as they move in a conjugate plane of the target optic or directly on the target optic.

[0065] Additional examples of scanning configurations used in fundus scanning imagers are provided in US Patent No. 9,549,672, assigned to the same assignee as the present application and incorporated herein by reference in its entirety.

[0066] Typically, lenses may introduce aberrations due to their imperfect focusing (e.g., light may be scattered over a region of space rather than focused to a point). For example, light from the outside / edge of a lens may appear blurred or distorted compared to the inside of the lens. This type of aberration may be due to field curvature, or it may be because the lens tends to focus the image at the edges, which appear too close compared to the center where it is best focused. Optionally, one or more spherical mirrors may be used to eliminate / offset / reduce this type of aberration. The field curvature on multiple lenses can be tracked (e.g., combined) using the Petzval sum. Typically, under the uniform radius convention assumed when deriving the Petzval sum, a converging lens (e.g., as used in this exemplary embodiment) has a positive term in the sum. In contrast, a converging mirror has a negative radius and a negative field curvature, and may be used herein to offset the field curvature of a converging lens. Although multiple spherical mirrors can be used (e.g., one in the illumination path from the light source to the eye and another in the return observation path from the eye to the collector (e.g., the collection path)), one spherical mirror (e.g., to offset the combined field curvature of the lenses depending on the size of the Petzval sum) may be sufficient, and that one spherical mirror can be positioned anywhere along the observation path, either in shared, scanned, or unscanned segments.

[0067] The advantage of using a spherical mirror in a shared path (e.g., the portion of the optical path shared by the illumination light and the returning collection light) is that the main challenge in fundus imaging is blocking back reflections from the cornea and optics in the portion of the optical system shared by the illumination path and the collection path (e.g., between the beam splitter and the retina). Unlike a transmissive lens, where light can pass through the interface between air and glass, a reflective mirror does not have significant back reflections, greatly reducing the problem of back reflections. The difficulty in replacing a lens in a shared path with a reflective mirror is that the reflective mirror reflects light, thereby bending the optical path back to the human eye, which creates difficulties in terms of mechanical interference between the optical system and the human face.

[0068] Spherical mirrors can be used with any of the scanning configurations discussed herein, but for illustration purposes, Figure 6D shows the integration of a spherical mirror into a Figure 6C Scan - Descan - Rescan the system. Figure 6D Zhongyu Figure 2 、 Figure 6A 、 Figure 6B and Figure 6C All elements that are the same in FIG. 1 have the same reference numerals and are described above. Figure 6C In the example of FIG. 1 , a radiation source 101 with an optional aperture 105 and a collimating lens 111 generates an illuminating line beam 103, but with Figure 6C Unlike the example of FIG. 1 , the beam splitter 133 is not required. Instead, the illumination beam 103 can be directed directly to a scanning component, which in this example is embodied as a set of mirrors (e.g., a polygon scanner) 138 that rotates back and forth to scan across the sample (e.g., the eye 75). Thus, the polygon scanner 138 converts the received illumination beam 103 into a scanning beam (e.g., path 115a), which can pass through a scanning lens 117 and an ophthalmic lens 119 to scan across the retina 73 of the eye 75. The scattered light returning from the eye 75 (e.g., optical path 115b) is scanned by different surfaces of the polygon scanner 138 to produce a substantially stable return line beam on optical path 139a, which is directed to the spherical mirror 151c.

[0069] The difficulty with using a spherical mirror is that in order to prevent the light beam directed at the spherical mirror from reflecting directly back on itself, the light beam needs to be irradiated onto the reflector off-axis (e.g., not perpendicular to the surface of the reflector), but irradiating the reflector off-axis may produce unwanted astigmatism. There are several ways to solve this problem. In order to minimize astigmatism, it is desirable to illuminate the reflector (e.g., spherical mirror 151c) as coaxially as possible. Astigmatism can be eliminated by adjusting the radius of curvature of the reflector along the reflection plane of the incident light beam. Astigmatism associated with the difference in curvature of the reflector between the reflection plane and the orthogonal plane can offset the astigmatism associated with off-axis illumination. Another method for eliminating the astigmatism of a first spherical mirror (e.g., spherical mirror 151c) is to reflect the light beam back from a second spherical mirror (not shown), the reflection plane of the second spherical mirror being orthogonal to the reflection plane of the first spherical mirror. The astigmatism of the two reflectors is then orthogonal and can therefore be eliminated. To avoid other aberrations, a reflector with a parabola or other higher-order shape can also be used.

[0070] The advantage of using a spherical mirror in the descanned path is that it can be used to help redirect the descanned path back to the scanner 138. Figure 6C As shown by the mirrors 151a and 151b, the descanned path is typically folded by multiple mirrors so that it can be returned to the scanner 137 and rescanned. Because spherical mirror 151c essentially folds the optical path (e.g., the reflected light), its position in the descanned path allows it to serve two purposes. First, it compensates for aberrations caused by the field curvature of the lenses in the system (e.g., according to the Petzval sum). Second, spherical mirror 151c performs a folding function, returning the descanned line beam along optical path 153c to the other surface of the polygon scanner 138, where it is rescanned to define a rescanned collected beam 116c on the collector 107 via the focusing lens 121. Optionally, adding a second spherical mirror to the illumination path (e.g., the path from the light source 101 to the polygon scanner 138) introduces a second folded path. This folding of the optical path can make the design more compact, thereby enabling a reduction in the size of the fundus camera.

[0071] As previously described, the illumination stop 125 can be used to reduce or eliminate reflections at the target optic (e.g., the ophthalmic lens 119). That is, the illumination stop 125 can be positioned in front of the aperture 105 and the radiation source 101 and can be imaged onto the target optic (on a conjugate plane to a surface of the target optic) (e.g., a curved surface of the target optic) to create a moving non-illuminated zone on the target optic. The collection stop 143 can be positioned on a descanned segment of the path back from the eye 75. In this example, the collection stop 143 is positioned before the spherical mirror 151c in the descanned path from the polygon scanner 138 to the spherical mirror 151c. Alternatively, the collection stop 143 can be imaged onto the same target optic (on a conjugate plane to a surface of the same target optic) (e.g., the ophthalmic lens 119), or onto another target optic where it is desirable to reduce reflections due to returned scattered light. Thus, a moving non-collecting zone can be created on the target optics that prevents / reduces reflections due to light returning from the retina of the eye 75. The non-collecting zone and the non-radiating zone can abut or overlap each other as they move on the target optics, or as they move on a conjugate plane of the target optics.

[0072] As described above, the present invention is directed to reducing image artifacts, such as artifacts caused by reflections from system optics in a scanning imager (such as a line scan imager or a point scan imager). This can be achieved by minimizing or eliminating overlap between the illumination light path and the collection light path on a given optical component (e.g., a target optical component) by placing light blocks (e.g., radiation blocks, illumination blocks, or collector blocks) in the illumination path and / or collection path on a conjugate plane of the target optical component (e.g., the plane onto which the target optical component is imaged). As described above, the present technology can be applied to different scanning configurations of a scanning imager. For illustrative purposes, some specific examples of scan-descan scanning imagers are provided below, it being understood that unless otherwise stated, the discussion can be applied to other scanning configurations. As described above, in a scan-descan configuration, scattered light returned from a sample is descanned, causing the return light to be stationary (e.g., not scanned) in at least a portion of the collection path. An illumination block can be inserted into the illumination path, a collection block can be inserted into a fixed portion of the collection path, and images of these two optical blocks (e.g., darkened areas) can be produced on one or more target optics (e.g., ophthalmic lenses or scan lenses). This can eliminate overlap between the illumination path and the collection path at the target optics, thereby eliminating the collection of reflections from the target lens. The following examples illustrate various design concepts to make this reflection blocking effect more robust to changes in alignment, focus, etc.

[0073] As described above, line scan imagers minimize unwanted light returning to a detector (e.g., a camera) by illuminating a limited area of ​​the sample to be imaged (e.g., the retina of the eye) at a time and collecting light only from that limited area, thereby blocking light that has been reflected or scattered back to the camera from other illuminated areas of the sample. In line scan imagers used for ophthalmic imaging, the separation between illumination and collection at a plane near the pupil of the eye (pupil segmentation) eliminates reflections from the cornea of ​​the eye and reduces reflections from the ophthalmic lens (the imager lens closest to the cornea), but does not eliminate ophthalmic lens reflections.

[0074] In a scanning imager, such as a line scan imager, the scanning component can be imaged onto the pupil plane. Therefore, by splitting the illumination and collection light at the scanning component (e.g., by imaging separate illumination and collection windows onto the scanning component), or even just before the scanning component (possibly near the corneal plane), splitting illumination and collection light at the pupil (or near the pupil, such as at the cornea) can be relatively easily achieved. That is, if the scanning component is essentially imaged onto the pupil, splitting the illumination and collection windows before the scanning component will result in pupil segmentation closer to the cornea.

[0075] However, at the ophthalmic lens (or other target optics in a scanning imager), the separation between illumination and collection light is more difficult. Typical approaches to reducing reflections at ophthalmic lenses rely on a combination of pupil segmentation at the pupil plane and an (illumination) slit with a highly restricted etendue (e.g., very narrow slit requirement), but even this has limited success. In addition to not being able to completely eliminate ophthalmic lens reflections, relying solely on the narrowness of the slit illumination results in very narrow slits (e.g., 0.25 degree width in practical applications), and / or small scanning steps with overlapping slit illumination on the retina, which increases the number of scans required to complete a complete scan across the retina (e.g., the object / sample being imaged). This very narrow slit width requirement also limits the amount of light reaching the retina and results in long acquisition times or noisy images.

[0076] It is noted that because eye lengths (and pupil sizes) vary, as understood by those skilled in the art, it is customary to define the linear distance along the retinal span (e.g., the width of the illumination slit) in terms of diopters, i.e., the width of the visual field on the retina that spans a particular diopter, assuming the focal length is essentially from the pupil to the retina.

[0077] In the present invention, rather than minimizing the narrowness of the slit illumination (e.g., the width of the illumination slit / line beam) to reduce reflections at the ophthalmic lens, the reflections caused by the overlap between the illumination path and the collection path at the ophthalmic lens (or another target optical component within a scanning imager) are directly addressed, independent of pupil segmentation. This can be achieved by placing a light block in the illumination path and / or collection path on a plane conjugate to the ophthalmic lens (e.g., the image plane onto which the target optical device is imaged), such that the light block is imaged (focused) onto the target optical device.

[0078] Figure 7 An example of an alternative scan-descan configuration for a slit (or line) fundus scanning imager incorporating the present invention is shown. Figure 7 Zhongyu Figure 2 6 , and are discussed above. Illumination (e.g., a slit beam or line beam) from a radiation (or illumination) source 101 passes along an illumination beam path (103a to 115a) through an illumination slit 105, which may help shape the slit beam (or slit illumination), through a first beam stop (e.g., illumination stop) 125, through a lens 111, and to a scanning component 137, where it is scanned to generate a scanned beam on path 115a. The scanned beam may traverse a scan lens 117 and an ophthalmic lens 119 to enter the eye 75 and scan light incident on the retina 73. Light scattered from the retina 73 follows the collection beam path (e.g., 115b to 103b to 161) back through the ophthalmic lens 119 and the scan lens 117, is scanned by the rotating scan mirror 137, deflected by the pickup mirror 163 onto the optical path 161, passes through the lens 121, and passes through the second beam stop (e.g., the collection stop) 143 to the camera 131, such as a detector or collector. In this example, the scanning component 137 can be imaged to the pupil plane of the eye 75, and the pickup mirror 163 can be positioned close to the scanning component 137 (e.g., just in front of the scanning component 137) to separate the illumination path and the collection path closer to the cornea (e.g., to provide pupil segmentation). In this example, the camera 131 can be a line scan camera and can use time delay integration (TDI) to generate the vertical dimension of the image (e.g., a full-frame image). As described above, the line images captured by the camera 131 may be buffered, processed by the CPU, and stored for future processing and / or display on a display (e.g., see Figure 2). In this example, the ophthalmic lens 119 is the target optic on which the reflection artifacts are removed or reduced. Therefore, both the beam stops 125 and 143 can be imaged onto the ophthalmic lens 119. In particular, the beam stops 125 and 143 can be imaged onto the back surface 119a of the ophthalmic lens 119. Alternatively, the beam stops 125 and 143 can be imaged onto the front surface 119b of the ophthalmic lens 119, or one beam stop (e.g., the illumination stop 125) can be imaged onto the back surface (e.g., surface 119b) of the ophthalmic lens 119, while the other beam stop (e.g., the collection stop 143) can be imaged onto the opposite side surface (e.g., the front surface 119a) of the ophthalmic lens 119.

[0079] In this scan configuration ( Figure 7 ), in which light returned from a sample (e.g., the eye 75) is descanned, portions of the illumination path and the collection path may be substantially fixed, e.g., the illumination beam output from the light source 105 may be fixed on the optical path 103 a before being scanned by the scanning component 137, and the return light (e.g., the collection beam) on the collection optical paths 103 b and 161 may be fixed after being descanned by the scanning component 137. Although the illumination block 125 may be inserted anywhere in the illumination path (e.g., from 103 a to 115 a), and the collection block 143 may be inserted anywhere in the collection path (e.g., 115 b to 103 b to 161), for convenience of embodiment, the illumination block 125 may be positioned on the fixed portion of the illumination path (e.g., 103 a) before being scanned by the scanning component 137, and the collection block 143 may be positioned on the fixed portion of the collection path (103 b and / or 161) after being descanned by the scanning component 137.

[0080] Figure 8 Provided Figure 77 , and a simplified, not-to-scale, close-up view of the ophthalmic lens 119, along with an imaged illumination stop 125′ (e.g., a non-illuminated zone created by the illumination stop 125), an imaged collection stop 143′ (e.g., a non-collection zone created by the collection stop 143), an illumination window 165 through which a scanned beam from the scanning component 137 can pass to reach the eye 75, and a collection window 167 through which return light from the eye 75 can pass to the scanning component 137 and to the collector 131. That is, the illumination stop 125 can create an imaged illumination stop 125′ that defines a non-illuminated zone through which the scanned beam from the scanning component 137 cannot pass, and the collection stop 143 can create an imaged collection stop 143′ that defines a non-collection zone through which return light from the eye 75 cannot pass. As shown, optionally, the imaged illumination block 125' can overlap (e.g., define an overlap region 169) with the imaged collection block 143' on the target optic (e.g., the lens near the eye 75 or the ophthalmic lens 119). This eliminates any overlap of the illumination path 115a (e.g., illumination window 165) and the collection path 115b (e.g., collection window 167) at the optic, and thus eliminates reflections from the optic. As the scanning component 137 sweeps (e.g., rotates), the two imaged blocks 125' and 143' move together across the ophthalmic lens (e.g., as shown by arrows 171a / 171b), maintaining their overlap 169, thereby blocking reflections. Alternatively, the illumination block 125' and the collection block 143' can be imaged to abut each other but not overlap.

[0081] Figure 9 An example of an alternative scan-descan-rescan configuration for a slit (or line) fundus scanning imager incorporating the present invention is shown. Figure 9 Zhongyu Figures 2 to 8 Like elements in FIG have like reference numerals and are discussed above. The scan-to-scan portion of this configuration is similar to Figure 7 Scan-to-scan section, but this configuration is different from Figure 7The difference is that a rescanning mechanism is incorporated between its collector (e.g., camera 189) and collection block 143. That is, the slit illumination from the light source 101 passes through the illumination slit 105 along the illumination beam path (103a to 115a), passes through the first beam block (e.g., illumination block) 125, and reaches the scanning component (e.g., galvanometer mirror) 137 through the lens 111. The scanning component 137 generates a scanned beam on the optical path 115a. The scanned beam on the illumination path 115a passes through the scanning lens 117 and the ophthalmic lens 119 and enters the eye 75, where it is scanned and incident on the retina 73. Light scattered from the retina 73 follows the collection beam path (115b to 103b to 161 to 191) back through the ophthalmic lens 119 and the scan lens 117, is scanned by the rotating scan mirror 137, is deflected by the pickup mirror 163 onto the optical path 161, passes through the lens 121, passes through the second beam stop (e.g., collection stop) 143, and passes through the collection slit (or hole) 181, which may be located at a position corresponding to Figure 7 131. Optionally, the collection (slit) aperture 181 may be in a conjugate plane of the retina 73. Return light passing through the collection aperture 181 passes through a (focusing) lens 183 and is rescanned by a second scanning component (second galvanometer) 185, which may be synchronized with the scanning component 137. The rescanned return light from the second galvanometer 185 passes through an optical device 187 (which may be one or more lenses, such as a second scanning lens and a focusing lens) to be scanned across a camera 189, which may be a full-frame camera, to define a composite image.

[0082] In the scan-not-to-scan configuration (e.g. Figure 6A In the configuration shown in FIG, 1 , the illumination light is scanned but the collected light is not descanned. An illumination stop can still be placed in the illumination path that is imaged to the ophthalmic lens (or other target optics) to reduce unwanted reflections, but there may not be a practical corresponding location in the collection path to place such a collection stop. Placing a stop only in the illumination path will reduce reflections, but may not be as effective as placing stops in both the illumination and collection paths to ensure that there is no overlap between the illumination and collection paths at the ophthalmic lens.

[0083] The problem may also be complicated by differences in refractive error of eyes across the population. To effectively image patients with different degrees of refraction (nearsightedness or hyperopia), fundus imagers typically have a focus adjustment to focus the image of the retina on the camera sensor (e.g., collector or detector). If this focus adjustment changes the position of the image (conjugate) plane of the ophthalmic lens (or other target optics) where the illumination stop and / or collection stop are placed, it is desirable to move the stop position with the focus adjustment so as to remain on the ophthalmic lens image plane. Alternatively, because the reflection problem is more severe for more myopic patients, the stop can be placed (e.g., fixed) at a position corresponding to the ophthalmic lens image plane for relatively myopic patients (e.g., -10 diopters).

[0084] Another way to keep the position of the illumination stop / collection stop substantially constant relative to the image plane of the ophthalmic lens is to keep the optics between the illumination stop / collection stop and the ophthalmic lens fixed and to separately correct the camera focus between the illumination stop / collection stop and the illumination source / camera. Figure 9 In an embodiment, the position of the collection block 143 is maintained fixed on a conjugate plane of the ophthalmic lens 119 while adjusting one or more lenses (e.g., lens 183 and / or lens 187) between the camera 189 and the collection block 143 to focus the image of the retina 73 on the light sensor of the camera 189. It has been found that maintaining the focus of the illumination beam (e.g., Figure 9 103a in the optical path 103a) may not be critical, so the illumination focus can also be adjusted between the illumination block (e.g., 125) and the illumination source (e.g., 101 / 105), or the illumination block 125 can remain stationary while the camera focus is adjusted.

[0085] While there is an optimal location for the illumination and collection stops (e.g., in conjugate planes of the objective optics), some flexibility in their locations has been identified. A blind zone (e.g., between the blocked areas after imaging (e.g., 125' and 143') is provided. Figure 8 169) or overlap can reduce the sensitivity of the positioning of the illumination block and the collection block relative to the image plane corresponding to the ophthalmic lens (or other target optical device). This overlap or blind area is also desirable to eliminate overlap between illumination and collection at the ophthalmic lens in the presence of optical aberrations in the system. Because line scan systems (such as wide line scan imagers) have low optical etendue in the segmentation direction (such as the direction perpendicular to the length of the slit), the relatively small amount of overlap can result in significant flexibility in the placement of the illumination block and the collection block.

[0086] It has also been found that for patients with high myopia (e.g., -6 diopters), the cornea may image the retinal plane to a plane close to the ophthalmic lens. Therefore, for patients with high myopia, blocking the overlap between the illumination path and the collection path at the ophthalmic lens may affect the overlap between the illumination path and the collection path at the retina, resulting in the possibility of reduced optical efficiency and lower image brightness. Therefore, it is desirable to have an imaging mode for some myopic patients (e.g., patients with high myopia) in which the illumination block and the collection block are removed or pulled back a little to allow some overlap between the illumination path and the collection path at the ophthalmic lens, accepting some reflections in the image so as to maintain acceptable overall brightness and image quality.

[0087] Although the illumination path and the collection path are divided by using a reflector 163 just before the scanning element 137, e.g. Figure 7 and Figure 9 As shown, this provides a relatively flexible design, but it creates an extra alignment step when the deflection angle of the mirror becomes a free parameter. Conceptually, an optical wedge (e.g., see Figure 6B ) in place of mirror 163 to deflect the collection path by a fixed angle, eliminating this free parameter. One problem with inserting a wedge optic or prism into the system is that reflections from the front and back surfaces of the wedge can create artifacts in the image. However, if the focusing optics are modified to add a wedge to one side, this creates what is referred to herein as a "doublet." Combining a doublet into a single composite structure is referred to herein as a "compound doublet."

[0088] Figure 10 A conceptual design of a compound doublet 209 is shown. As shown, it is desirable to combine lens 201 with wedge 203. This can be achieved by combining lens 201 with prism 205, resulting in a conceptual doublet 207, which can be constructed (e.g., molded) as a single component, resulting in a compound doublet 209 with a fixed spacing between the two centroids C1 and C2.

[0089] Figure 11 An alternative configuration of the beam stop (125 / 143) for adding imaging to the ophthalmic lens / eyepiece 119 in a scan-descan-rescan line scanning system using a compound doublet 209 is shown. Using the compound doublet 209 to separate the illumination and collection paths can reduce both alignment steps and component count. Figure 11 Zhongyu Figures 2 to 10All identical elements in FIG. 1 have the same reference numerals and are described above. In this example, the pupil segmentation aperture 211 (or segmentation region) can be positioned immediately before the scanning element 137 (e.g., in the path between the light source 101 and the scanning element 137) and imaged close to the cornea, e.g., assuming that the scanning element 137 is imaged onto the pupil, as described above. Furthermore, the ophthalmic lens 119 can be adjusted for myopia, and the illumination block 125 and the collection block 143 can be located on conjugate planes of the ophthalmic lens 119 (e.g., corresponding to a myopic eye) to block reflections. Furthermore, the radiation slit (aperture) 105 and the collection slit (or aperture) 181 can be imaged onto the retina 73 and further constructed on a common (same) film, thereby eliminating the need to align one with the other (e.g., the displacement is determined by the separation between the dual lenses 209). In addition, the beam stop 125 / 143 and the slit 105 / 181 can be moved together, for example, by means of a common (same) support wall W1, so as to maintain alignment. The support wall W1 can further provide a light barrier to separate the illumination light on the side of the light source 101 from the collected light on the side of the second scanning component 185 and the collector 189.

[0090] In this example, the illumination stop 125 and the collection stop 143 can be substantially coplanar in the image plane of the ophthalmic lens (eyepiece) 119 and can be manufactured from a single foil, thereby providing high alignment accuracy between them. Similarly, the illumination slit 105 and the collection slit 181 can also be coplanar and therefore also manufactured from a single foil. The alignment tolerance between the beam stop 125 / 143 and the slit 105 / 181 can also be less stringent than the relative alignment between the slits or between the beam stops, so that such alignment can rely on a precise mounting of the two components without the need for further alignment adjustments. The two centroids C1 and C2 (see Figure 10 ) is critical to alignment, so it is desirable to mold the composite doublet 209 as a single component.

[0091] In the above description, the beam stop (e.g., 143 / 125) has been imaged onto the ophthalmic lens, as the lens can be an important component that generates reflections in an ophthalmic scanning imager. However, a similar approach of placing a light block (e.g., an additional or identical beam stop) on a conjugate plane of a given target optical component other than the ophthalmic lens can be used to block reflections from that other target optical component in the system.

[0092] Figure 12An example computer device (or CPU or computer system) 83 is shown. Computer device 83 can take any suitable physical form. For example, computer system 83 can be an embedded computer system, a system on a chip (SOC), a single-board computer system (SBC) (such as, for example, a computer on a module (COM) or a system on a module (SOM)), a desktop computer system, a laptop or notebook computer system, a computer system grid, a mobile phone, a personal digital assistant (PDA), a server, a tablet computer system, or a combination of two or more of these systems. Where appropriate, computer device (or computer system) 83 can reside in the cloud, which can include one or more cloud components in one or more networks.

[0093] In some embodiments, the computer system 83 includes one or more processors 102, memory 104, storage 106, input / output (I / O) interface 108, communication interface 110, and bus 112. Optionally, the computer system 83 may also include a display 114, such as a computer monitor or screen (e.g., Figure 2 Display 85 is shown. Processor 102 includes hardware for executing instructions, such as instructions that constitute a computer program. For example, processor 102 may be a general-purpose computing on a central processing unit (CPU) or a graphics processing unit (GPGPU). Memory 104 may include main memory for storing instructions that processor 102 executes or saves temporary data during processing. For example, memory 104 may include random access memory (RAM), such as dynamic RAM (DRAM) or static RAM (SRAM). In some embodiments, memory 106 may include long-term or large-capacity storage for data or instructions. For example, memory 106 may include a hard disk drive (HDD or SSD), flash memory, ROM, EPROM, or other types of non-volatile memory. I / O interface 108 may include one or more interfaces for communicating with I / O devices, which enables communication with people (users). Communication interface 110 may provide a network interface for communicating with other systems or networks. For example, communication interface 110 may include a network interface controller (NIC) and / or a wireless NIC for communicating with another computer system on a network. Communication interface 110 may also include a Bluetooth interface or other types of packet-based communication. Bus 112 may provide a communication link between the aforementioned components of computing system 83 .

[0094] Although the present invention has been described in conjunction with several specific embodiments, it is apparent to those skilled in the art that many further substitutions, modifications, and variations will be apparent based on the foregoing description. Therefore, the invention described herein is intended to encompass all such substitutions, modifications, applications, and variations that fall within the spirit and scope of the appended claims.

Claims

1. A scanning imaging system, comprising: Radiation sources; a scanning component that receives radiation from the radiation source and defines a scanned beam of radiation; an optical device to direct the scanned beam of radiation to a sample to be imaged, the optical device comprising a target optical element over which the scanned beam of radiation is scanned; a radiation blocking member positioned to partially block radiation output from the radiation source and to limit radiation received by the scanning member, the radiation blocking member being on a conjugate plane of the target optical element and producing a moving non-radiating region on the target optical element, the scanning beam of radiation being unable to pass through the moving non-radiating region, a portion of the scanning beam outside the moving non-radiating region being scanned across the sample, thereby producing a moving illumination area on the sample; a collector for collecting radiation returned from the mobile illumination area; as well as a collector blocking member positioned to partially block radiation returning from the movable illumination area, the collector blocking member being in a conjugate plane of the target optical element and creating a movable non-collection region on the target optical element through which radiation returning from the movable illumination area cannot pass, wherein the scanning imaging system has a first operating mode in which the radiation blocking component is positioned to partially block radiation output from the radiation source and the collector blocking component is positioned to partially block radiation returned from the movable illumination area; as well as The scanning imaging system has a second operating mode in which the radiation blocking component is positioned to not block radiation output from the radiation source and the collector blocking component is positioned to not block radiation returning from the moving illumination area.

2. The scanning imaging system according to claim 1, wherein: The radiation blocking component is positioned along a radiation path from the radiation source to the scanning component.

3. The scanning imaging system according to claim 1, wherein: The moving non-radiating area moves together with and at least partially overlaps the moving non-collecting area on the target optical element.

4. The scanning imaging system according to claim 1, wherein: The moving non-radiating area moves together with and abuts the moving non-collecting area on the target optical element.

5. The scanning imaging system according to claim 1, wherein: The sample to be imaged is an eye; The first operating mode corresponds to a non-myopic eye; and The second operating mode corresponds to a myopic eye greater than a predefined diopter value.

6. The scanning imaging system according to claim 1, further comprising: A focusing mechanism for focusing the sample on the collector; in: Focusing the sample onto the collector moves the conjugate plane of the objective optical element; and The collector blocking member moves together with the conjugate plane of the target optical element to remain on the conjugate plane of the target optical element.

7. The scanning imaging system according to claim 6, wherein: The position of the radiation blocking member remains stationary regardless of movement of the conjugate plane of the objective optical element due to focusing the sample onto the collector.

8. The scanning imaging system according to claim 1, further comprising: focusing optics for focusing the sample onto the collector, the focusing optics being between the collector barrier and the collector; in: the relative positions of all optical components along the radiation return path from the target optical element to the collector barrier are fixed; and The collector barrier remains stationary and in the conjugate plane of the objective optical element while the focusing optics focus the sample onto the collector.

9. The scanning imaging system according to claim 1, wherein: The radiation blocking member is coplanar with the collector blocking member; an illumination aperture in a conjugate plane of the surface of the sample to be imaged, the illumination aperture being between an illumination source and the radiation blocking member; a collection aperture in a conjugate plane of the surface of the sample to be imaged, the collection aperture being between the collector and the collector blocking member; Wherein, the lighting hole and the collecting hole are coplanar.

10. The scanning imaging system according to claim 9, further comprising: a partitioning region imaged substantially immediately before the scanning component in a radiation path from the radiation source to the scanning component, the partitioning region separating the scanned beam of radiation at the sample from radiation returned from the sample, the partitioning region having a first sample opening through which the scanned beam of radiation passes and a second sample opening through which radiation returned from the sample passes, the first sample opening and the second sample opening being coplanar; a doublet lens molded from two coplanar lenses into a single optical component, the doublet lens including a first sub-lens aligned with the first sample opening and a second sub-lens aligned with the second sample opening; A structural support maintains alignment between the first sample opening, the first sub-lens, the radiation blocking component and the illumination aperture, and maintains alignment between the second sample opening, the second sub-lens, the collector blocking component and the collection aperture.

11. The scanning imaging system according to claim 1 , wherein: The sample to be imaged is an eye having a pupil and a fundus; The scanning beam of radiation enters the eye through the pupil and produces the moving illumination area at the fundus; as well as Radiation returning from said moving illumination area exits the eye through the pupil; The system further comprises: a radiation aperture positioned in front of the radiation source, the radiation aperture being imaged substantially onto the fundus; pupil-splitting optics imaged substantially to a pupil of the eye, said pupil-splitting optics separating said scanned beam of radiation entering the eye from said returning radiation exiting the eye, said pupil-splitting optics comprising a pupil aperture imaged substantially to the pupil; Wherein, the radiation blocking component is positioned between the pupil aperture and the radiation aperture.

12. The scanning imaging system according to any one of claims 1, 9 and 11, wherein: The target optical element is a system lens positioned in the radiation path from the scanning component to the sample to be imaged.

13. The scanning imaging system according to claim 12, wherein: The system lens is closest to the sample in a radiation path from the scanning component to the sample.

14. The scanning imaging system according to any one of claims 1, 9 and 11, wherein: The radiation source is one of a laser source and an incoherent radiation source.

15. The scanning imaging system according to any one of claims 1, 9 and 11, wherein: The radiation output from the radiation source is a substantially rectangular radiation beam.

16. The scanning imaging system according to claim 15, wherein: The rectangular radiation beam has a length dimension and a variable width dimension substantially perpendicular to the length dimension.

17. The scanning imaging system according to any one of claims 1, 9 and 11, wherein: The scanning imaging system is one of a point scanning imager and a line scanning imager.

18. The scanning imaging system according to any one of claims 1, 9 and 11, wherein: The scanning imaging system is one of a scan-non-descan system, a scan-descan system, and a scan-descan-rescan system.

19. The scanning imaging system according to any one of claims 1, 9 and 11, further comprising a spherical mirror to offset field curvature aberration of one or more lenses of the scanning imaging system.

20. The scanning imaging system according to claim 19, wherein: The curvature radius of the spherical mirror is adjusted along the reflection plane of the incident light beam to reduce or eliminate the astigmatism of the spherical mirror.

21. The scanning imaging system according to any one of claims 1, 9 and 11, further comprising: First spherical mirror; as well as The second spherical mirror is positioned to receive the reflected signal from the first spherical mirror and has a reflection plane orthogonal to the reflection plane of the first spherical mirror to offset the astigmatism of the first spherical mirror.

22. The scanning imaging system of any one of claims 1, 9, and 11, further comprising a crossed polarizer comprising a first polarizer positioned in an optical path from the radiation source to the sample, and a second polarizer that is in an orthogonal state relative to the first polarizer and positioned in an optical path from the sample to the collector.

Images