Wide-angle pupil relay for cell phone-based fundus cameras

Abstract

An optical imaging system includes: a first lens system housed in a body of a mobile communication device, the first lens system having a first optical axis, a first entrance pupil spatially fixed in a reference plane associated with the body, and a first focal length; and an optical telescope providing diffraction-limited imaging in a spectral range of at least 486 nm to at least 656 nm. The optical imaging system is configured to: when the optical telescope is inserted between the first lens system and the entrance pupil (EPE) of the eye's visual system, image the EPE onto the first entrance pupil at a basic unit magnification, and vice versa.

Description

[0001] This invention application is a divisional application of the invention application with an international filing date of August 31, 2017, international application number PCT / JP2017 / 031412, national application number 201780053096.X which entered the Chinese national phase, and invention title "Wide-angle pupil repeater based on mobile phone fundus camera". Technical Field

[0002] This invention relates technically to U.S. Provisional Patent Application No. 62 / 381,768, filed August 31, 2016, and U.S. Provisional Patent Application No. 62 / 539,733, filed August 1, 2017. The disclosures of these provisional applications are incorporated herein by reference.

[0003] This invention generally relates to ocular diagnostic imaging devices, and more specifically to a retinal camera based on a portable handheld smartphone for capturing high-quality, wide-field-of-view fundus images. The use of a mobile phone platform creates a fully embedded system capable of acquiring, storing, and analyzing fundus images that can be transmitted directly from a telephone via a wireless communication system for remote evaluation. Background Technology

[0004] Fundus imaging is widely used for the diagnosis, monitoring, and management of many retinal diseases. One limitation found in current imaging systems is the large size and stationary nature of the imaging equipment. Traditional fundus cameras are bulky desktop devices, difficult to move due to their fragility, large size, and weight. In practice, such fundus cameras also force patients to sit upright, which can be difficult for sick and hospitalized patients. In addition to size limitations, fundus cameras require power to power illumination, the imaging screen, and the data processing unit. Typically, this power is provided by a central in-wall power outlet and requires continuous power to operate the fundus camera properly.

[0005] While digital fundus cameras have been envisioned (some of which are based on mobile phones or similar devices, such as iPhones; typically mobile devices), these cameras have substantial operational limitations caused by any of the following: (i) lack of optical conjugation between the optical system of the mobile device used and the visual system being imaged; (ii) insufficient field of view (FOV) associated with the imaging of the selected surface of the visual system, which results in the need for multiple computational “stitching” of the acquired images; (iii) severely residual aberrations that impair the resulting images; and (iv) a combination of the above.

[0006] Therefore, there is still a need for a low-cost handheld device configured as an alternative to high-cost medical devices that can record digital images of the surfaces of the visual system during ophthalmic examinations, without exhibiting the operational drawbacks of currently known imaging system solutions. Summary of the Invention

[0007] A first aspect of this disclosure includes: a first lens system housed in a body of a mobile communication device, the first lens system having a first optical axis, a first entrance pupil spatially fixed in a reference plane associated with the body, and a first focal length; and an optical telescope providing diffraction-limited imaging in a spectral range of at least 486 nm to at least 656 nm, wherein the optical imaging system is configured to: image the EPE onto the first entrance pupil at a basic unit magnification when the optical telescope is inserted between the first lens system and the entrance pupil, i.e., the EPE, of the eye's visual system, and vice versa. Attached Figure Description

[0008] The invention will be more fully understood by referring to the following detailed description of specific embodiments and the accompanying drawings which are not drawn to scale.

[0009] Figure 1 The diagram shows a mobile phone 20 equipped with an image capture unit (camera sensor) 214, which captures an image of the fundus of the subject's eye via a window 214W and via an optical system (image capture lens system (camera lens)) not shown, and shows an accessory 22 attached to the mobile phone 20.

[0010] Figure 2 This is a schematic diagram of the optical component of the first embodiment, which supplements the exit pupil of the portable device and relays the image of the mobile phone camera pupil to the eye pupil.

[0011] Figure 3 Includes characterization for different field heights Figure 2 A dot plot of the diffraction-limited imaging quality of the first embodiment.

[0012] Figure 4 A second embodiment of the optical component 500 is shown, which represents a focal-free relay system configured as conceived in this invention, and is illustrated in combination with a Navarro model of the human eye.

[0013] Figure 5 It shows the results for different field heights Figure 4 A dot diagram of the second embodiment.

[0014] Figure 6A This is a diagram showing the dimensional relationship between the image capture field of view of the fundus and the image sensor in the first embodiment.

[0015] Figure 6B This is a diagram showing the dimensional relationship between the image capture field of view of the fundus and the image sensor in the second embodiment.

[0016] Figure 7This is a schematic diagram showing the configuration of Annex 22 according to the third embodiment.

[0017] Figure 8 This is a schematic diagram showing the configuration of Annex 22 according to the fourth embodiment.

[0018] Figure 9 This is a schematic diagram showing the configuration of Annex 22 according to the fifth embodiment.

[0019] Figure 10 This is a diagram showing the electrical configuration of mobile phone 20.

[0020] Figure 11 This is a flowchart illustrating how to use Appendix 22 and mobile phone 20.

[0021] Typically, the dimensions and relative proportions of elements in a drawing can be set differently from reality to appropriately simplify, clarify, and facilitate understanding of the drawing. For the same reason, not all elements in one drawing need to be shown in another. Detailed Implementation

[0022] Figure 1 A mobile phone 20 is shown, which is equipped with an image capture unit (camera sensor) 214, which captures an image of the fundus of the subject's eye via a window 214W and via an optical system (image capture lens system (camera lens)) not shown. Figure 1 Attachment 22 is shown, which is attached to mobile phone 20.

[0023] In the description of this invention, "mobile phone" is the same as "mobile communication device," "telephone," or "wireless communication system," and "fundus camera" is the same as "retinal camera based on portable handheld smartphone" or "low-cost handheld device."

[0024] A mobile phone camera lens is an imaging lens on a camera sensor. Of course, these are already provided by mobile phone manufacturers.

[0025] The inventors have utilized a very useful characteristic of mobile phone camera lenses. Specifically, the lens has approximately diffraction-limited properties, and the incident pupil is located in front of the lens, within the window of the mobile phone camera.

[0026] If a phone has both a wide-angle and a telephoto camera, their entrance pupils are essentially at the same position. This means that if the phone is moved laterally, either camera can be used. Therefore, simple zooming is possible between 40dg and 80dg field-of-view retinal cameras without significant pixel loss.

[0027] Another useful feature of mobile phone camera lenses is that the field of view is similar to that required by fundus cameras, so the pupil relay can be close to 1x magnification, which means that lateral chromatic aberration and distortion can be very small, and the optical design is relatively simple.

[0028] Coarse focusing is a separate mechanical adjustment between lens group G1 and the second lens group G2 to accommodate different patients' refractive power settings. Fine focusing is the built-in autofocus system of a mobile phone camera.

[0029] According to the disclosed embodiments of the present invention, a modular device and its method of use are disclosed for a handheld eye imaging device, which is supplemented by an imaging optical detection system (camera) and a programmable processor of a mobile phone (optionally, a tablet or another smart device) operatively coupled to optical and illumination elements, configured to image the structure of the eye (e.g., the retina) in a non-clinical location. This modular device provides multifunctionality (fluorescein imaging, fluorescence, bright field, infrared (IR) imaging, near-infrared (NIR) imaging) and multi-region imaging of the eye (retina, cornea, external, etc.), as well as added features for image processing, storage, and wireless data transmission for remote storage and evaluation. Acquired eye images can also be directly transmitted from the device to the patient's electronic medical record without the need for an intermediate computer system.

[0030] The field of view (FOV) of the retina is a technical specification for fundus imaging and an important consideration in the development of fundus cameras. FOV describes the angle through which the image of the retina passes. Illumination light from the device enters the retina, and reflected light from the retina is used to form an image at the device's sensor. Standard fundus cameras have a field of view of approximately 40-45 degrees.

[0031] For example, in<peekvision.org / what-it-does> In the digital imaging system disclosed in the paper (referred to here as the Peek system), a mobile phone camera is used to take a picture of the user's retina by placing it as close as possible to the user's eye. In this case, the entrance pupil (EP) of the mobile phone's optical system (usually located at the front lens element within its front window) is not optically conjugate with the user's eye EP or iris (i.e., the EP of the visual system being examined).<www.d-eyecare.com> A similarly configured and operationally limited device is disclosed. As a result, as will be readily understood by those skilled in the art, the image of the retina formed by the employed optical system inevitably contains significant aberrations, preventing the user from properly assessing the condition / state of the retina to be imaged under normal, uncorrected / unattended conditions. Specifically, the FOV associated with retinal imaging with the Peek system is therefore essentially limited by the ratio of the pupil diameter to the size of the foveal region surrounding the optic nerve and macula, resulting in poor image quality. While this approach provides useful, low-cost diagnostic information for some retinal lesions, imaging larger areas of the retina at higher resolution would be advantageous, allowing for the observation of other, more subtle retinal lesions.

[0032] <bosch-eyecare.com / en / eyecare / products / fundus_imaging / fundus_imaging.html> The Bosch fundus camera described in [the article] is also limited to imaging within a + / - 40 degree field of view; Jedmed describes a similar system:<jedmed.com / products / portable-fundus-camera> The solution offered by Volk Optical is another example of a system with operational limitations in retinal surface imaging (see [link]).<veatchinstruments.com / Volk-Pictor-Plus-Portable-Retinal-Camera> ).

[0033] Operational problems associated with existing fundus cameras (low field of view, requiring multiple computational "stitching" of optical data acquired from the retina, and significant residual aberrations that harmfully reduce the overall quality of the resulting "stitched" image) are addressed by providing a compact, low-cost fundus camera with a wide 80-degree (full-angle) FOV configured as an achromatic focusless repeater (telescope) operating at near 1x magnification to achieve imaging of a 2 mm diameter (undilated) eye pupil in a spatially fixed EP with diffraction-limited resolution to the optical system of a mobile device.

[0034] Embodiments of the present invention utilize the parameters of a typical built-in imaging optics system of a mobile phone (or other mobile device), which has a full-angle FOV of about 75 to 80 degrees and assumes no aberrations or vignetting (a reasonable assumption given the nominal diffraction-limited performance of such optics known in the art) and an EP size of about 2 mm in diameter (the EP of the mobile device is fixed in space) to provide approximately 1x optical relay system for imaging the EP of the eye onto the EP of the mobile device.

[0035] Considering the size matching typically achievable between the EP of a wavy eye and the EP of a typical mobile device's optical system, the focusless repeater of the present invention is configured to provide imaging with approximately 1x magnification, thereby ensuring a full-angle FOV at approximately 80 degrees of eye entry. This is approximately twice that of a typical fundus camera in the prior art and approximately half the full horizontal field of view of the human eye. Therefore, a single imaging exposure using the lens of the present invention covers a significantly larger area of ​​the retina compared to a typical fundus camera. Furthermore, in the case of attempting spatial stitching of several (e.g., four) images of the retina obtained with the lens system of the present invention, not only does the "stitched" image cover the entire retina, but the stitching will also be available while maintaining nearly 50% overlap between the individual fields of the stitched image. Those skilled in the art will readily understand that such spatial overlap of the individual images is impossible using the systems described in the prior art. Because existing systems have a much smaller field of view (40 degrees or less), more individual images (acquired with existing systems) must be overlapped to cover the entire retina (approximately 160 degrees), or alternatively, with even less overlap. However, it is recognized in the art that the greater the overlap between or within the component images, the better the quality of the resulting stitched image, because more features (primarily blood vessels in the case of retinal imaging) are available for alignment. An advantage of this embodiment is that each individual component image covers more of the retinal surface, thus allowing for an increase in the overlapping area between the component images when forming the resulting stitched image.

[0036] Figure 2 A YZ cross-section of an embodiment of the lens system of the first embodiment is shown, where the lens system is configured as a rotationally symmetric refractive afocal repeater (telescope). For convenience, as shown in the figure, light rays from... Figure 2 The phone's camera EP on the right tracked the optical system in Appendix 22. Figure 2 The Navarro model's eye on the left. The lens element closest to the pupil of the phone camera is... Figure 2The first lens element is labeled as element 1; the next lens element is element 2, and so on, with the retinal surface referred to as the image plane. This design includes two cemented doublet lenses (EP 320 for the eye and EP 310 for a mobile phone camera lens), with the single positive biconvex lens 3 having the highest converging capability among the optical elements present in this embodiment. The cemented doublet lens 320 is formed by cementing a positive meniscus lens element 6 recessed towards the eye and a meniscus lens element recessed towards the eye. The first lens group G1 includes the cemented doublet lens 320 and the positive meniscus lens element 4 recessed towards the eye. The cemented doublet lens 310 consists of a biconcave negative lens element 1 cemented with the biconvex positive lens element 2. The second lens group G2 includes the cemented doublet lens 310 and the positive biconvex lens element 3.

[0037] Operating at near 1x magnification is ideal and offers a significant operational advantage over existing systems, as this optical configuration helps correct lateral chromatic aberration and distortion aberrations, in stark contrast to existing systems. Figure 2 The optical design is configured to compensate for the aberrations of the (Navarro model) eye (2mm pupil diameter, the healthy human eye is almost diffraction-limited) and provide near-diffraction-limited resolution across the entire 80-degree FOV range. Figure 3 Evidence of this operational characteristic is provided in the diagram, which shows ray aberrations (dot plot) in planes tangent to a local area of ​​the spherical retina at three identified wavelengths: 643.85 nm, 546.1 nm, and 479.99 nm. Figure 3 As shown, and convincingly demonstrated by the dot plot of each wavelength falling within the Airy disk curve, aberrations are substantially corrected across the entire visible spectrum, but even less at the red end of the spectrum (where backscattered light from the retina is approximately five times stronger than blue light, which is operationally preferred during retinal imaging). This diffraction-limited property across the visible spectrum largely and advantageously distinguishes the proposed invention from prior art inventions. In practice, the proposed optical system is designed to achieve diffraction-limited imaging of the retina by balancing the typical optical aberrations of the ordinary eye with the optical aberrations of the eyepiece portion of the embodiment of the invention.

[0038] Several points are noted regarding the objective lenses used in embodiments of the system of the present invention. Tables 1, 2, and 3 provide representations. Figure 2 Data on the optical components (sequence) of the lens element in the first embodiment are provided in Tables 4, 5, and 6. Figure 4 Data of the optical components (sequence) of the lens element in the second embodiment, Figure 4 The implementation forms a lens system configured according to the concept of the present invention. Design specifications for the implementation are generated using code V, and discussed with reference to the corresponding drawings. In these tables, from the plane closest to the object / target ( Figure 4 As shown in Table 4, the optical elements and, possibly, the media separating some of the elements, are numbered "backwards," starting towards the surface of the retina. As those skilled in the art will understand, this method of numbering optical elements makes it easier to define the NA and parameters characterizing the system's behavior in image space (i.e., in eye space) during the optical design process. Figure 4 In this design, the lens element closest to the object is labeled as element 1, the next lens element is element 2, and so on, while the retinal surface is referred to as the image plane. It is noteworthy that the combination chosen to resemble the Navarro model of the human eye, with its typical optical characteristics and geometry, must be included in the design of the relay system of this invention in order to allow for proper system evaluation.

[0039] A positive radius value for a given surface indicates that the center of curvature of that surface is located on the left side of the surface, while a negative radius value indicates that the center of curvature is located on the right side of the surface; dimensions are in millimeters; thickness is defined as the axial distance from a given surface to the next surface; and the indicated image diameter is a paraxial value, not a ray-traced value. Additionally, regarding the description of chromatic aberration (if present), a decrease in the Strell ratio between monochromatic and multicolor designs indicates a loss of contrast in the chromatic aberration within a specified spectral band, while the change in the optimal single focal point indicates the residual field curvature.

[0040] For the purposes of this disclosure and the appended claims, descriptors relating to present values, elements, properties, or characteristics use the terms “substantially,” “approximately,” “about,” and similar terms to emphasize that the mentioned values, elements, properties, or characteristics are, in any case, considered for practical purposes as would be understood by those skilled in the art, although not necessarily exactly as claimed. These terms, applied to descriptions of specific features or qualities, mean “mostly,” “mainly,” “quite,” “substantially,” “largely or largely,” “mainly but not necessarily entirely,” and reasonably indicate approximate language and describe the specified feature or descriptor in a way that would enable those skilled in the art to understand its scope. When used with reference numerical values, the term indicates a range relative to the specified value plus or minus 20%, more preferably plus or minus 10%, even more preferably plus or minus 5%, and most preferably plus or minus 2% relative to the specified value.

[0041] The use of these terms in describing selected features or concepts neither implies nor provides a basis for uncertainty nor adds numerical limitations to the specified features or descriptors. As those skilled in the art will understand, the precise value or characteristic of such a value, element, or property deviates from the actual value within a numerical range defined by typical experimental measurement errors when using measurement methods accepted in the art for this purpose, and can vary within that range. In some specific instances within the scope of this invention, the terms "approximately" and "about" when used with reference values ​​indicate a range relative to a specified value plus or minus 20%, more preferably plus or minus 10%, even more preferably plus or minus 5%, and most preferably plus or minus 2%.

[0042] Table 1 (Implementation Method 1)

[0043]

[0044] Note:

[0045] A positive radius indicates that the center of curvature is to the right.

[0046] A negative radius indicates that the center of curvature is to the left.

[0047] Dimensions are in millimeters.

[0048] The thickness is the axial distance to the next surface.

[0049] Navarro's eye model is described in "Accommodation-Dependent Model of the Human Eye Withaspherics", J Opt Soc Am A. 1985 August: 2(8): 1273-81; Navarro R. Santamaria J. Bescos J.

[0050] Table 2: Aspherical constants

[0051]

[0052] Table 3: Infinite Conjugation

[0053]

[0054] Note:

[0055] FFL measured from the first surface

[0056] BFL measured from the final surface

[0057] Table 4 (Implementation Method 2)

[0058]

[0059] Note:

[0060] ------------------------------------------

[0061] A positive radius indicates that the center of curvature is to the right.

[0062] A negative radius indicates that the center of curvature is to the left.

[0063] Dimensions are in millimeters.

[0064] The thickness is the axial distance to the next surface.

[0065] Navarro's eye model is described in "Accommodation-Dependent Model of the Human Eye Withaspherics", J Opt Soc Am A. 1985 August: 2(8): 1273-81; Navarro R. Santamaria J. Bescos J.

[0066] ------------------------------------

[0067] Table 5: Aspherical constants

[0068]

[0069] Table 6: Infinite Conjugation

[0070]

[0071] As described in Tables 4, 5, and 6 above, the second embodiment 500 of the relay system of the present invention is constructed in... Figure 4 The image shown has an effective focal length (modulus) of 30.67 mm, resulting in an image with a (paraxial) height of approximately 10.6 mm, and good correction for lateral chromatic aberration. Embodiments of the lens system conceived according to the invention comprise only a single aspherical surface A(1), which provides practical advantages (e.g., reduced cost). Figure 4As shown, the second embodiment includes a first lens group G1 and a second lens group G2. The first lens group G1 includes lens elements 4 and 5, and the second lens group G2 includes lens elements 1, 2, and 3. A Navarro model of the eye is also shown in combination with a relay system 500. The second lens group G2 includes: a first meniscus lens element 1 having negative refractive power and optically contacting a biconvex positive lens element 2; and an element 3 having positive optical power and an aspherical A(1) and spatially separated from the combination of elements 1 and 2. The second lens group G2 together has positive optical power, thereby exceeding the negative optical power of element 1. The first lens group G1 includes a positive lens element 4 and a second meniscus lens element 5 concave towards the eye side, and together has positive optical power. The first lens group G1 is positioned close to the eye to be examined, such as Figure 4 The Navarro model of the eye is shown.

[0072] Figure 5 The diagram includes a dot plot showing the defocusing effect when imaging an object using the second embodiment 500 of the invention, as a function of field position (expressed in degrees). The second embodiment also demonstrates compensation for (Navarro model) eye aberrations (2 mm pupil diameter, nearly diffraction-limited in a healthy human eye) and provides near-diffraction-limited resolution across the entire 80-degree FOV. As the dot plot of each wavelength falling within the Airy disk curve convincingly demonstrates, aberrations are substantially corrected across the entire visible spectrum, but even less at the red end of the spectrum (where backscattered light from the retina is approximately five times stronger than blue light, which is operationally preferred during retinal imaging). This diffraction-limited performance across the visible spectrum largely and advantageously distinguishes the proposed invention from the prior art. In practice, the proposed optical system is designed to achieve diffraction-limited imaging of the retina by balancing the typical optical aberrations of the ordinary eye with the optical aberrations of the eyepiece portion of the embodiment of the invention.

[0073] For each of the first and second embodiments, values ​​related to the focal length of the first lens group G1 and the second lens group G2 are shown below.

[0074] Implementation Method 1

[0075] The focal length of the first group (eyepieces) is f1 = 32.3.

[0076] The focal length of the second group (objective lenses) is f2 = 34.4.

[0077] Paraxial magnification: f2 / f1 = 1.07

[0078] Implementation Method 2

[0079] The focal length of the first group (eyepieces) is f1 = 38.0.

[0080] The focal length of the second group (objective lenses) is f2 = 53.0.

[0081] Paraxial magnification: f2 / f1 = 1.4

[0082] Regarding the relationship between the wide-angle retinal image size and the image sensor size, there are two possible scenarios. In scenario 1, the magnification is chosen such that the 80-degree field of view entering the eye is imaged onto the camera to fill the diagonal of the screen (i.e., the image sensor size), as shown below. Figure 6A As shown. This has the advantage of using all camera pixels, but the disadvantage is that it loses some of the 80-degree field of view at the top, bottom, and sides.

[0083] In case 2, the magnification is chosen such that the 80-degree field of view entering the eye is imaged onto the camera screen (i.e., the size of the image sensor) to fill the shorter dimension of the rectangular screen, such as... Figure 6B As shown. This has the advantage of seeing the entire 80-degree field of view, but the disadvantage is that not all camera pixels are used. This is a more common case with fundus cameras, but both cases demonstrate that by selecting an appropriate magnification close to 1.0 within the range of 1.0 to 2.0, the invention can be applied to either situation.

[0084] Specific embodiments of the invention can also be configured to perform fundus imaging using a dual-lens (or typically multi-lens) mobile phone camera. For example, if the mobile phone has a second camera lens with a different focal length (e.g., twice the focal length of the first lens), then if the mobile phone is moved laterally or horizontally relative to the focusless repeater of the invention to optically (axially) align the second lens with the focusless repeater, the central angular portion of the retina (corresponding to the mobile phone lens with a smaller FOV compared to the other lens's FOV) can be imaged at a higher resolution. This facilitates a closer examination of the foveal region and optic nerve while maintaining the ability to capture the entire retina to a short-focal-length camera through stitching. Alternatively, in this case, image stitching can be used with a longer focal-length lens to cover an 80-degree field of view or larger at a higher resolution.

[0085] The scope of this invention is advantageously suited to situations where a mobile device has multiple lenses (optical systems) arranged adjacent to each other (e.g., as 1D or 2D lens arrays) and different focal lengths (and therefore different FOVs). Here, Figure 1The implementation can be integrated with the rear of the mobile device via a device or locator (mechanically driven or otherwise driven, e.g., using an electric motor) configured to laterally reposition the implementation in a plane perpendicular to the optical axes of the multiple lenses, while maintaining the working (axial) distance between the implementation and the plane in which the multiple lenses are set. When the implementation is thus translated to be coaxially aligned with the first lens of the mobile phone camera, an optical conjugate is established between the EP of the eye and the EP of the first lens, and 1x retinal imaging can be advantageously achieved using the telescope and the first lens of the present invention. When, in a next operation, the implementation is translated to be coaxially aligned with the second lens of the mobile phone camera, an optical conjugate is established between the EP of the eye and the EP of the second lens, and 1x retinal imaging can be advantageously achieved using the telescope and the second lens of the present invention. As a result of multi-step (e.g., N>1) repositioning, an N-position zoom imaging system is effectively realized. It should be understood that during retinal imaging in this configuration, when the mobile phone lens with a smaller FOV cooperates optically and mechanically with the implementation of the focusless repeater, (during image stitching) retinal imaging with higher resolution is achieved.

[0086] Furthermore, since users typically don't wear glasses when taking photos, + / -10 diopter adjustment can be provided by focusing the lens (eyepiece) closest to the eye according to the user's prescription. The camera's focusing system will then be adjusted for fine focusing.

[0087] According to the aforementioned embodiments, a low-cost fundus camera with a simple and small-sized configuration can be realized. Furthermore, compared to conventional fundus cameras using attached lenses, superior fundus images can obviously be obtained in a field of view that is approximately twice as wide and spans a broad wavelength range. Moreover, when using a multi-lens mobile phone camera, the degrees of freedom of the field of view and resolution performance are increased.

[0088] The disclosed aspects, or a portion thereof, may be combined in ways not listed above. Therefore, the invention should not be construed as limited to the disclosed embodiments.

[0089] In the following text, see references Figure 7 The third implementation method is described.

[0090] like Figure 7 As shown, Annex 22 is a relay optical system that relays the pupil of the target eye 150 to the pupil position of the optical system of the image capture unit 214 of the mobile phone 20, and is provided with a first positive lens group G1 and a second positive lens group G2. The first positive lens group G1 and the second positive lens group G2 have the same optical axis and essentially form an afocal system. Through the combination of the first positive lens group G1 and the second positive lens group G2, the pupil of the target eye 150 is relayed to the pupil of the optical system of the image capture unit 214 of the mobile phone 20.

[0091] The focusless repeater of the present invention, as a focusless accessory, is located in front of the mobile phone camera lens. In this case, it is used to relay the mobile phone camera's pupil to the patient's iris (pupil).

[0092] When the afocal relay accessory 22, consisting of the first positive lens group G1 and the second positive lens group G2, is positioned between the target eye 150 and the optical system positioned in front of the image capture unit 214 of the mobile phone 20 (e.g.) Figure 7 As shown, this configuration aligns the eye-side focal point of the first positive lens group G1 with the pupil position of the target eye 150, and aligns the focal point of the second positive lens group G2 on the mobile phone 20 side with the pupil position of the image capture optical system of the mobile phone 20. According to this configuration, the combination of the first positive lens group G1 and the second positive lens group G2 forms a conjugate relationship between the pupil of the target eye and the pupil of the external optical system.

[0093] When the afocal attachment 22, which includes the first positive lens group G1 and the second positive lens group G2, is set, as follows: Figure 7 As shown, at a position where its optical axis is aligned with the optical axis of the image capture optical system of the mobile phone 20, an image FI of the fundus of the object eye 150 is formed between the first positive lens group G1 and the second positive lens group G2.

[0094] The first positive lens group G1 includes, starting from the eye side, a positive meniscus lens 320 with a concave surface facing the eye side and a positive lens 340, and the second positive lens group G2 includes, starting from the eye side, a positive lens 330 and a meniscus lens 310 with a convex surface facing the eye side.

[0095] The positive meniscus lens 320 with a concave surface facing the eye side is not limited to... Figure 7 The configuration shown can have Figure 2 The configuration shown is a compound lens comprising a positive meniscus lens 6 having a concave surface facing the eye and a meniscus lens 5 having a concave surface facing the eye.

[0096] like Figure 7 As shown, the meniscus lens 310 of the second positive lens group G2, which has a convex surface facing the eye, can be a composite lens of a biconvex positive lens 310A and a biconcave positive lens 310B cemented together. Furthermore, an aspherical surface can be suitably used as the shape of the lens surface, and in the second example, an aspherical surface is provided at the convex surface of the biconvex lens of the second lens group G2 on the eye side.

[0097] When f1 is the focal length of the first lens group G1, f2 is the focal length of the second lens group G2, and D is the principal plane spacing between the two lens groups G1 and G2, the following conditions are preferably satisfied.

[0098] f1+f2=D.

[0099] When, as described above, the first positive lens group G1 and the second positive lens group G2 substantially form a focalless system, the following conditions are preferably satisfied.

[0100] 0.9 <f2 / f1<2.2

[0101] In addition, for practical use, it is preferable to satisfy the condition 1.0≤f2 / f1<2.0.

[0102] Preferably, the focal length f1 of the first lens group G1 and the focal length f2 of the second lens group G2 satisfy the following conditions.

[0103] 30mm <f1<50mm

[0104] 30mm <f2<60mm

[0105] The viewing angle of the second lens group G2 on the optical system side of the mobile phone 20 includes and preferably matches the viewing angle of the optical system of the mobile phone 20. The image of the field of view (FOV) of the fundus of the target eye corresponding to the viewing angle of the first lens group G1 is transmitted to the optical system of the mobile phone 20 via the second lens group G2.

[0106] The 1x magnification of the relay optics system in Annex 22 of all the foregoing embodiments is ideal for aberration correction; however, as stated above, regarding numerical conditions, a larger field of view than a mobile phone camera is achieved by introducing a small amount of magnification, and the design still achieves favorable aberration correction. The larger field of view is beneficial because many retinal lesions can be seen within an 80-degree field of view, and it is possible to switch to a mobile phone telephoto lens camera to view more detailed information at a central 40-degree angle to the retina.

[0107] In addition, Annex 22 is provided with a power supply 380, a light source 362 powered by the power supply 380, and a beam splitter 372, which reflects the light emitted from the light source 362 toward the second lens group G2 side and transmits the light reflected from the object eye 150 to the mobile phone 20 via the second lens group G2.

[0108] In the image capture mode described below, light emitted from light source 362 is reflected at beam splitter 372 toward the second lens group G2 and reaches the fundus of the target eye 150 via the first lens group G1. The light reaching the fundus of the target eye 150 is reflected at the fundus, and the reflected light reaches the beam splitter 372 via the first lens group G1 and the second lens group G2, passes through the beam splitter 372, and reaches the mobile phone 20. The pupil of the target eye 150 is relayed to the pupil of the optical system of the image capture unit 214 of the mobile phone 20 via the first positive lens group G1 and the second positive lens group G2.

[0109] Next, the fourth embodiment will be described. Because... Figure 8 The fourth embodiment shown has parts similar to the third embodiment, so the same reference numerals denote the same parts, and their descriptions are omitted while different parts are described.

[0110] like Figure 8 As shown, in addition to the first lens group G1 and the second lens group G2, the focalless accessory 22 also includes a light source 362 and a power supply 380 for the light source 362. The diverging light from the light source 362 is calibrated by the condenser lens 364. The calibrated light then enters the diffuser 366 and becomes diverging light, illuminating an annular aperture 368 with an annular hole. The light passing through this annular hole is reflected at the beam splitter 372 and guided to the target eye 150 by the second lens group G2 and the first lens group G1. Furthermore, due to the action of the second lens group G2 and the first lens group G1, the image of the annular hole of the annular aperture 368 is formed on the pupil of the target eye and illuminates the fundus of the target eye.

[0111] Next, the fifth embodiment will be described. Because... Figure 9 The fifth embodiment shown has parts similar to the third embodiment, so the same reference numerals denote the same parts, and their descriptions are omitted while different parts are described. For example... Figure 9 As shown, the focusless accessory 22 includes a contact 382 connected to a light source 362. The mobile phone 20 includes a contact 20C connected to the battery (not shown) of the mobile phone 20. When the focusless accessory 22 is attached to the mobile phone 20, the contact 382 of the accessory 22 and the contact 20C of the mobile phone 20 are connected. As described above, since the contact 382 is connected to the light source 362 and the contact 20C of the mobile phone 20 is connected to the battery (not shown) of the mobile phone 20, power from the battery (not shown) of the mobile phone 20 is supplied to the light source 362 via the contacts 20C and 382.

[0112] In the fourth embodiment (see Figure 8 Acceptably, power supply 380 is omitted, and contact 382 is provided at accessory 22 and contact 20C is provided at mobile phone 20, such that when accessory 22 is attached to mobile phone 20, contact 382 of accessory 22 and contact 20C of mobile phone 20 are connected, and power from battery (not shown) of mobile phone 20 is supplied to light source 362 via contact 20C and contact 382.

[0113] While all the examples above use beam splitter 372, to effectively utilize the light from light source 362, it is acceptable to provide a polarizing beam splitter instead of beam splitter 372, with a polarizer positioned between light source 362 and the polarizing beam splitter, and an analyzer provided between the polarizing beam splitter and mobile phone 20. Furthermore, a quarter-wave plate can be inserted between the second lens group G2 and the polarizing beam splitter, and a configuration can be used to provide circularly polarized light to the target eye.

[0114] Next, refer to Figure 10 This describes the electrical configuration of all the examples of the aforementioned mobile phone 20. For example... Figure 10 As shown, the mobile phone 20 is equipped with a computer 200. The computer 200 has a CPU 202, a ROM 204, a RAM 206, and an input / output (I / O) port 208. The CPU 202, ROM 204, RAM 206, and I / O port 208 are interconnected via a bus 210. The I / O port 208 is connected to an auxiliary storage device 212, an image capture unit 214, a speaker 216, a display unit 218, a communication unit 220, a home button 222, an image capture button 224, and an autofocus mechanism 226.

[0115] Next, refer to Figure 11 This section explains how to use Appendix 22 and mobile phone 20.

[0116] In step 402, the user installs accessory 22 on the mobile phone 20. When the power switch of the mobile phone 20 is turned on, the fundus image capture application starts in step 404. In step 406, the user holds their eye in the image capture position of the image capture unit 214.

[0117] In step 408, by turning on the home button 222 of the mobile phone 20, the CPU 202 starts the image capture mode. When the image capture mode is started, the image capture unit 214 captures a fundus image via the accessory 22.

[0118] In step 410, the CPU 202 adjusts the autofocus mechanism 226 to automatically adjust the focus, and while automatically adjusting the focus, determines whether the fundus image capture range of the image capture unit 214 is appropriate. Specifically, based on the pixel values ​​of the fundus image data and the threshold used to distinguish between the pupil portion and the peripheral portion, the position of the pupil of the target eye 150 is detected within the fundus image capture range of the image capture unit 214. By determining whether the detected pupil position is within the image capture range, it is determined whether the image capture range is appropriate.

[0119] If it is determined in step 410 that the fundus image capture range is inappropriate, the CPU 202 issues an audio command via speaker 216 in step 412 to change the holding position of the phone 20. For example, when the pupil position is higher than the image capture range of the image capture unit 214, the audio "Please raise the phone" is output via speaker 216. Instead of or together with the audio output "Please raise the phone", "Please raise the phone" can be displayed on the display unit 218.

[0120] When it is determined that the user's fundus position is appropriately positioned within the image capture range of the image capture unit 214, the CPU 202 displays an image capture command on the display unit 218 in step 414. The user, seeing the image capture command displayed on the display unit 218, activates the image capture button 224. The image capture command is not limited to being displayed on the display unit 218, and may not be displayed there, or may be output via audio from the speaker 216 based on that display. When the image capture button 224 is activated, the CPU 202 detects that the image capture button 224 has been activated in step 416. When the activation of the image capture button 224 is detected, the fundus image captured by the image capture unit 214 is stored in the auxiliary storage device 212 in step 418, and the image signal of the fundus image is transmitted to the fundus image server 250 via the communication unit 220 in step 420.

[0121] The processes in steps 414 and 416 are omitted. When it has been determined that the position of the user's fundus is properly positioned within the image capture range of the image capture unit 214, in step 418, the CPU 202 stores the fundus image captured by the image capture unit 214 in the auxiliary storage device 212, and in step 420, the image signal of the fundus image is sent to the fundus image server 250 via the communication unit 220.

[0122] In all the examples described above, the mobile phone 20 is equipped with a single optical system (image capture lens system (camera lens)); however, the technology disclosed herein is not limited to this, and multiple optical systems corresponding to multiple viewing angles can be provided. For example, in order to handle the case where the peripheral portion surrounding the central portion of the fundus needs to be captured in addition to the central portion, the mobile phone 20 may be equipped with a first optical system for wide-angle applications and a second optical system for standard applications with a smaller viewing angle than wide-angle. In a first mode of capturing images of both the central and peripheral portions of the fundus, the images of both the central and peripheral portions of the fundus are formed at the image capture unit 214 via the first optical system. In a second mode of capturing only the central portion, only the image of the central portion of the fundus is formed at the image capture unit 214 via the second optical system.

[0123] List of reference numerals

[0124] 20 mobile phones

[0125] 22 Attachments

[0126] G1 First Lens Group

[0127] G2 Second Lens Group

[0128] 320 meniscus lens

[0129] 320A Meniscus Lens

[0130] 320B meniscus lens

[0131] 340 Positive Lens

[0132] 33 Positive Lens

[0133] 310 Meniscus Lens

[0134] 310A Biconvex Lens

[0135] 310B Biconcave Lens

[0136] 320 positive meniscus lens

[0137] 320A Positive Meniscus Lens

[0138] 320B meniscus lens.

Claims

1. An optical imaging system, comprising: A first lens system, housed within the main body of a mobile communication device, the first lens system having a first optical axis, a first entrance pupil spatially fixed in a reference plane associated with the main body, and a first focal length; and An optical telescope that provides diffraction-limited imaging in a spectral range of at least 486 nm to at least 656 nm. The optical imaging system is configured such that when the optical telescope is inserted between the first lens system and the entrance pupil (EPE) of the eye's visual system, it images the EPE onto the first entrance pupil at a basic unit magnification, and vice versa.

2. The optical imaging system according to claim 1, further comprising: A second lens system is housed in the body of the communication device. The second lens system has a second optical axis, a second entrance pupil that is spatially fixed in the reference plane, and a second focal length. The second entrance pupil is laterally offset from the first entrance pupil in the reference plane. as well as A means for connecting the optical telescope to the body, the means being configured to provide movement of the optical telescope from a first position to a second position along a line located in the reference plane, wherein: The first position is defined when the optical axis of the optical telescope and the first optical axis are substantially coincident. The second position is defined when the optical axis of the optical telescope and the second optical axis at least partially coincide.

3. The optical imaging system according to claim 2, wherein, The first optical axis and the second optical axis are substantially parallel to each other.

4. The optical imaging system according to claim 2, wherein, The optical imaging system is configured to image the EPE onto the first entrance pupil at a basic unit magnification when the optical telescope is inserted between the second lens system and the EPE, and vice versa.

5. The optical imaging system according to claim 1, wherein, The first lens system includes: a meniscus lens element having negative optical power, which is cemented with a positive lens element to form an optical doublet; and a positive optical power lens element spatially separated from the optical doublet.

6. A method for imaging the retina, the method comprising: An optical telescope is positioned between a first lens system integrated into a communication device and the eye to image the eye's entrance pupil (EPE) onto the first entrance pupil (EP) of the first lens system under imaging conditions, including: (i) unity magnification and (ii) diffraction-limited imaging in the spectral range of 486 nm to 656 nm; and The first image of the retina of the eye is recorded by the first sensor of the communication device through the optical telescope.

7. The method according to claim 6, further comprising: The optical telescope and the communication device are repositioned relative to each other in a direction transverse to the optical axis of the first lens system until the optical axis of the second lens system built into the communication device substantially coincides with the optical system of the optical telescope. as well as A second image of the retinal surface is recorded via the optical telescope using the second sensor of the communication device.

Images