WO2022067638A1

WO2022067638A1 - Optical device and apparatus comprising said optical device

Info

Publication number: WO2022067638A1
Application number: PCT/CN2020/119309
Authority: WO
Inventors: Jukka-Tapani Makinen
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2020-09-30
Filing date: 2020-09-30
Publication date: 2022-04-07
Also published as: CN116261858A

Abstract

An optical device (1) for enabling magnification and comprising a primary lens arrangement (2) and a secondary lens arrangement (3) defining an optical axis (O). The primary lens arrangement (2) is ball-shaped, i.e. may be at least partially spherical or spheroid, and has a plane of symmetry (P) dividing the primary lens arrangement (2) into two halves. The primary lens arrangement (2) comprises at least one primary lens element (5, 5a, 5b), the primary lens element (s) (5, 5a, 5b) forming one or both of said halves, and an optical aperture element (7). The optical aperture element (7) is adapted to spatially limit propagation of electromagnetic radiation and extends along the plane of symmetry (P). The secondary lens arrangement (3) comprises at least one secondary lens element (8, 8a, 8b), and is either adapted to direct electromagnetic radiation towards the primary lens arrangement (2), or is adapted to receive limited electromagnetic radiation from the primary lens arrangement (2). The optical magnification ratio of the optical device may be between 1: 3 and 3: 1, providing magnification which is sufficient for the average consumer.

Description

OPTICAL DEVICE AND APPARATUS COMPRISING SAID OPTICAL DEVICE

TECHNICAL FIELD

The disclosure relates to an optical device for enabling magnification, the optical device comprising a primary lens arrangement and a secondary lens arrangement defining an optical axis.

BACKGROUND

Traditional microscopes for medical use, such as diagnostics, or research are designed to be used with the naked eye, but may also be provided with additional interfaces for, e.g., imaging using a camera. Such microscopes are usually large and expensive devices intended for experts. Furthermore, stand-alone microscopes have limited use for tasks that require the microscope to be portable, such as inspection work.

Current portable and/or low-cost options include USB-microscopes to be used together with a computer, and add-on lenses to be applied externally onto a standard smartphone or tablet in front of the camera objective of the device. A USB-microscope together with a computer is portable, however, not easily so. Add-on lenses have low resolution and are oftentimes difficult to use.

Currently, there are no consumer devices such as smartphones or tablets having a built-in microscope camera module available. The technical problems associated with fitting a full microscope camera module into a mobile electronic device has not been solved by prior art.

SUMMARY

It is an object to provide an improved optical device for enabling magnification. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

According to a first aspect, there is provided an optical device for enabling magnification, the optical device comprising a primary lens arrangement and a secondary lens arrangement defining an optical axis, the primary lens arrangement being ball-shaped and having a plane of symmetry dividing the primary lens arrangement into two halves. The primary lens arrangement comprises at least one primary lens element, the primary lens element (s) forming one or both of the halves, and an optical aperture element adapted to spatially limit propagation of electromagnetic radiation. The optical aperture element extends along the plane of symmetry. The secondary lens arrangement comprises at least one secondary lens element, and the secondary lens arrangement is adapted to direct electromagnetic radiation towards the primary lens arrangement, or to receive limited electromagnetic radiation from the primary lens arrangement.

Such a solution has low complexity, relatively low manufacturing costs, and requires relatively little space within the apparatus while still providing good image quality due to the inherent symmetry. The ball-shaped lens arrangement can be arranged at the center of the optical device, which makes the design of the device smaller in size, enabling better portability. By allowing the centered ball-shaped arrangement to provide most of the optical power, and using the other arrangement (s) merely to flatten the image surface into a plane, the present solution also provides a larger usable image area.

In a possible implementation form of the first aspect, the optical device further comprises an image sensor, the image sensor sharing the optical axis. This allows images to be taken of a magnified object.

In a further possible implementation form of the first aspect, the optical aperture element is an electromagnetic radiation stop, the optical aperture element being partially electromagnetically transparent and partially opaque. This allows the electromagnetic radiation passing through the primary lens arrangement to be limited, either to the radiation passing directly through the aperture of the optical aperture element or to the radiation passing through the aperture in combination with electromagnetic radiation passing through additional, non-opaque parts of the optical aperture element.

In a further possible implementation form of the first aspect, an optical magnification ratio of the optical device is between 1: 3 and 3: 1, providing magnification which is sufficient for the average consumer.

In a further possible implementation form of the first aspect, the image sensor has a pixel size of 0.7-5 μm, and/or the image sensor has a diameter of maximum 10 mm. This allows the apparatus comprising the optical device and the image sensor to be turned into a small microscope with sufficient image resolution.

In a further possible implementation form of the first aspect, the primary lens arrangement is biconvex, preferably equiconvex.

In a further possible implementation form of the first aspect, each primary lens element is at least partially convex. This allows the primary lens element to have a shape which is more easily manufactured and/or configured to fit a specific space available

In a further possible implementation form of the first aspect, the primary lens element is a monolithic, biconvex lens element, the optical aperture element extending within the monolithic, biconvex lens element. This facilitates simple assembly with fewer components in need of alignment.

In a further possible implementation form of the first aspect, the primary lens arrangement is at least partially spherical or spheroid.

In a further possible implementation form of the first aspect, the primary lens arrangement comprises two primary lens element (s) in the form of a first plano-convex lens element and a second planoconvex lens element, a first main planar surface of the first plano-convex lens element and a second main planar surface of the second planoconvex lens element extending in parallel with each other and with the plane of symmetry, the optical aperture element extending between, and in abutment with, the first main planar surface and the second main planar surface. This simplifies the manufacturing process.

In a further possible implementation form of the first aspect, each primary lens element is at least partially spherical or spheroid.

In a further possible implementation form of the first aspect, the first plano-convex lens element has a thickness as seen from the first main planar surface, and the second planoconvex lens element has a second thickness as seen from the second main planar surface, the first thickness and the second thickness being identical for at least one section of the first plano-convex lens element and one section of the second planoconvex lens element. By having at least sections which are identical and arranged at corresponding locations of the two halves, the primary lens arrangement has at least partial symmetry, while the remainder of the primary lens arrangement can have any other suitable shape.

In a further possible implementation form of the first aspect, the first thickness and the second thickness have identical deviation as seen from a common center point and along a radial direction.

In a further possible implementation form of the first aspect, the optical device further comprises a tertiary lens arrangement comprising at least one tertiary lens element, the primary lens arrangement being arranged between the secondary lens arrangement and the tertiary lens arrangement along the optical axis. This allows electromagnetic radiation to both converge and diverge, as suitable.

In a further possible implementation form of the first aspect, at least one of the primary lens element (s) , the secondary lens element (s) , and/or the tertiary lens element (s) is/are aspheric, allowing the image surface to be flattened into a plane.

In a further possible implementation form of the first aspect, incoming electromagnetic radiation is allowed to propagate through the primary lens element (s) by passing through the optical aperture element from a first side of the plane of symmetry to a second side of the plane of symmetry.

In a further possible implementation form of the first aspect, the electromagnetic radiation has a wavelength within one of a visible light wavelength range, an infrared wavelength range, or an ultraviolet wavelength range. This allows the optical device to be used for applications other than microscopy, such as e.g. detection of security markings outside normal human vision range.

In a further possible implementation form of the first aspect, the optical aperture element has a diameter which is smaller than a peripheral diameter of the primary lens arrangement.

In a further possible implementation form of the first aspect, the secondary lens arrangement and the tertiary lens arrangement are identical and symmetrically arranged around the primary lens arrangement.

In a further possible implementation form of the first aspect, the secondary lens arrangement comprises a first secondary lens element and a second secondary lens element, and the tertiary lens arrangement comprises a first tertiary lens element and a second tertiary lens element, increasing the flexibility and power of the optical device. In a further possible implementation form of the first aspect, the first secondary lens element and the first tertiary lens element are identical, and the second secondary lens element and the second tertiary lens element are identical, allowing the optical device to be completely symmetrical.

In a further possible implementation form of the first aspect, the secondary lens arrangement comprises a first secondary lens element and a second secondary lens element, and the tertiary lens arrangement comprises a first tertiary lens element and a second tertiary lens element, the first secondary lens element and the first tertiary lens element being non-identical, the second secondary lens element and the second tertiary lens element being non-identical, allowing the optical device to be configured to fit any desired specification.

In a further possible implementation form of the first aspect, the electromagnetic radiation stop comprises a foil and/or a coating, the foil or coating preferably comprising an electromagnetically non-transparent plastic and/or metal material.

In a further possible implementation form of the first aspect, the electromagnetic radiation stop comprises a plate with a throughgoing opening or is part of an external lens barrel housing.

In a further possible implementation form of the first aspect, the primary lens element (s) , the secondary lens element (s) , and/or the tertiary lens element (s) comprise optical glass and/or plastic material.

According to a second aspect, there is provided an apparatus comprising the optical device according to the above. The optical device facilitates a portable apparatus, such as a smartphone, tablet, or laptop, having a built-in microscope camera module.

In a possible implementation form of the second aspect, the optical device is not an add-on to the apparatus.

In a further possible implementation form of the second aspect, the apparatus further comprises an image sensor module, an image sensor of the image sensor module being the image sensor of the optical device. This allows images to be captured of a magnified object using the existing features of the apparatus, such as the camera module of a smartphone.

In a further possible implementation form of the second aspect, the optical device is arranged fully within the apparatus, such that there is no requirement of user-based alignment of the optical device with other features of the apparatus.

In a further possible implementation form of the second aspect, the further comprises at least one illumination source configured to illuminate an object to be magnified using the optical device. This allows not only improved illumination of an object to be magnified, but also allows the optical device to be used for 3D imaging. By controlling the angle of illumination, for example by using two illumination sources providing illumination at two different steep angles, two images can be captured and used for generating a 3D image. By controlling the color of illumination, for example by using two illumination sources providing illumination at two different wavelengths, spectral analysis can be performed on the object.

According to a third aspect, there is provided a method of providing a magnified image of an object emitting electromagnetic radiation, the method comprising a number of steps, including providing a primary lens arrangement defining an optical axis. The primary lens arrangement is ball-shaped and divided into two halves by means of a plane of symmetry, and the primary lens arrangement comprises an optical aperture element adapted to spatially limit propagation of electromagnetic radiation within the primary lens arrangement, the optical aperture element extending along the plane of symmetry. Furthermore, the method comprises the step of providing a secondary lens arrangement along the optical axis, the secondary lens arrangement being adapted to direct the electromagnetic radiation towards the primary lens arrangement, or being adapted to receive limited electromagnetic radiation from the primary lens arrangement. The method additionally comprises either the step of allowing propagation of electromagnetic radiation emitted by the object through the secondary lens arrangement prior to the electromagnetic radiation propagating through the primary lens arrangement, or the step of allowing propagation of the limited electromagnetic radiation through the secondary lens arrangement after the propagation of the electromagnetic radiation has been spatially limited by the optical aperture element.

Such a solution has low complexity, relatively low manufacturing costs, and requires relatively little space within the apparatus while still providing good image quality. The ball-shaped lens arrangement can be arranged at the center of the optical device, which makes the design of the device smaller in size, enabling better portability. Furthermore, the ball-shaped lens arrangement, in combination with further lens arrangement (s) before or after the ball-shaped lens arrangement, provides a larger usable image area.

In a possible implementation form of the third aspect, the method comprises the steps of providing a tertiary lens arrangement along the optical axis, such that the primary lens arrangement is arranged between the secondary lens arrangement and the tertiary lens arrangement along the optical axis, and either allowing propagation of electromagnetic radiation emitted by the object through the tertiary lens arrangement prior to the electromagnetic radiation propagating through the primary lens arrangement, or allowing propagation of the limited electromagnetic radiation through the tertiary lens arrangement after the propagation of the electromagnetic radiation has been spatially limited by the optical aperture element. This allows the electromagnetic radiation to both converge and diverge, as suitable, and the optical device used by the method to be symmetrical.

In a further possible implementation form of the third aspect, the secondary lens arrangement and/or the tertiary lens arrangement comprises at least one aspherical lens, allowing the image surface to be flattened into a plane.

These and other aspects will be apparent from the embodiments described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the aspects, embodiments, and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

Figs. 1a and 1b show a perspective view and a cross-sectional side view of an optical device according to an embodiment of the present invention;

Fig. 2 is a schematic illustration of an apparatus comprising an optical device according to an embodiment of the present invention;

Fig. 3 shows a cross-sectional side view of an optical device according to an embodiment of the present invention;

Fig. 4 shows a cross-sectional side view of an optical device according to an embodiment of the present invention.

DETAILED DESCRIPTION

Fig. 2 illustrates an apparatus 11, such as a smartphone, tablet, or laptop, comprising an optical device 1 enabling magnification of an object. The optical device 1 is arranged fully within the apparatus 11, in other words, the optical device 1 is not an add-on to the apparatus 11.

The apparatus 11 may furthermore comprise an image sensor module 12, and the image sensor of the image sensor module 12 may also be part of the optical device 1 as the image sensor 4 of the optical device 1. The apparatus may furthermore comprise several additional components, such as autofocus actuators, other related optomechanics, and electronics. Should the apparatus 11 and the optical device 1 not comprise an image sensor 4, the apparatus 11 would instead comprise additional optics such as an eyepiece.

The apparatus 11 may also comprise at least one illumination source 13 configured to illuminate an object to be magnified by means of the optical device 1. This allows not only improved illumination of the object to be magnified, but also allows the optical device 1 to be used for 3D imaging. By controlling the angle of illumination, for example by using two illumination sources providing illumination at two different and steep angles, two images can be captured and used for generating a 3D image. By instead controlling the color of illumination, for example by using two illumination sources providing illumination at two different wavelengths, spectral analysis can be performed on the object.

Figs. 1a, 1b, 3, and 4 show embodiments of the optical device 1. The optical device 1 enables magnification of an object by means of a primary lens arrangement 2 and a secondary lens arrangement 3 which together define an optical axis O along the general direction of which electromagnetic radiation emitted by the object propagates in parallel or at angles, as indicated in Figs. 3 and 4. The optical magnification ratio of the optical device 1 may be between 1: 3 and 3: 1, preferably between 1: 2 and 2: 1.

The electromagnetic radiation may have a wavelength that is within one of a visible light wavelength range, an infrared wavelength range, or an ultraviolet wavelength range. Visible light may be used to generate a 2D (two-dimensional) or 3D (three-dimensional) image, while both infrared light and ultraviolet light can be used for, e.g., detecting security markings outside the normal human vision range.

The primary lens arrangement 2 is ball-shaped and has a plane of symmetry P dividing the primary lens arrangement 2 into two halves, as shown in Figs 1b, 3, and 4. The halves may be either actual, physical halves, as shown in Fig. 4, or imaginary halves, as illustrated in Fig. 3. The halves may be of identical shapes and sizes, or of uneven shapes and sizes. By “ball-shaped” is meant an at least partially spherical shape where at least one section of each half is convex. In other words, the primary lens arrangement 2 is at least partially biconvex. Fig. 3 shows a primary lens arrangement 2 which is completely spherical and equiconvex. Fig. 4 shows a primary lens arrangement 2 which is partially spherical and equiconvex. The primary lens arrangement 2 may be a spheroid and/or comprise cut-off sections such as those shown at the top and the bottom of the primary lens arrangement 2 of Fig. 4.

The primary lens arrangement 2 may have a first thickness T1 and a second thickness T2, as illustrated in Fig. 3. The first thickness T1 and a second thickness T2 may correspond to the radius of the arrangement at the convex sections of the primary lens arrangement 2 as seen from a common center point of the primary lens arrangement 2.

The primary lens arrangement 2 comprises at least one

primary lens element

5, 5a, 5b, the

primary lens elements

5, 5a, 5b forming one or both of the above-mentioned halves. Each

primary lens element

5, 5a, 5b may be at least partially convex.

The primary lens arrangement 2 furthermore comprises an optical aperture element 7, adapted to spatially limit propagation of electromagnetic radiation. The optical aperture element 7 extends within the primary lens arrangement 2 along the plane of symmetry P. The optical aperture element 7 may allow incoming electromagnetic radiation to propagate through the

primary lens elements

5, 5a, 5b by passing through the optical aperture element 7 from a first side of the plane of symmetry P to a second side of the plane of symmetry P. The optical aperture element 7 may have a diameter which is smaller than a peripheral diameter of the primary lens arrangement 2.

The optical aperture element 7 may comprise an electromagnetically transparent aperture, while the remainder of the optical aperture element 7, surrounding the aperture, may form an electromagnetic radiation stop. The area of the optical aperture element 7 which does not form the aperture may be fully or partially opaque. Hence, optical aperture element 7 may allow propagation of electromagnetic radiation through the aperture of the optical aperture element only, or through the aperture as well as through additional, non-opaque parts of the optical aperture element 7. A partially transparent, partially opaque optical aperture element 7 may be useful e.g. for a zone plate when attempting to control diffraction and improve resolution.

The optical aperture element 7 may comprise a plate with a throughgoing opening, i.e. an aperture, or may be part of an external lens barrel housing. The optical aperture element 7 may comprise a foil and/or a coating, the foil or coating preferably comprising an electromagnetically non-transparent plastic and/or metal material.

The primary lens arrangement 2 may comprise only one primary lens element 5 which is a monolithic, biconvex lens element. The optical aperture element 7 extends within the monolithic, biconvex lens element 5, as illustrated in Fig. 3. Each

primary lens element

5, 5a, 5b may be at least partially spherical or spheroid.

The primary lens arrangement 2 may also comprise two

primary lens elements

5a, 5b in the form of a first plano-convex lens element 5a and a second planoconvex lens element 5b, as illustrated in Fig. 4. A first main planar surface 6a of the first plano-convex lens element 5a and a second main planar surface 6b of the second planoconvex lens element 5b extend in parallel with each other and with the plane of symmetry P. The optical aperture element 7 extends between, and in abutment with, the first main planar surface 6a and the second main planar surface 6b.

The first plano-convex lens element 5a may have a thickness T1 as seen from the first main planar surface 6a, and the second planoconvex lens element 5b may have a second thickness T2 as seen from the second main planar surface 6b. The first thickness T1 and the second thickness T2 may be identical for at least one section of the first plano-convex lens element 5a and one section of the second planoconvex lens element 5b. Nevertheless, the thickness, or in some cases, the radius of curvature for the first plano-convex lens element 5a and the second planoconvex lens element 5b do not have to be defined exactly from the plane of symmetry, i.e. from a common center point. The primary lens element (s) 5, 5a, 5b can be aspheric, such that the ideal radius of curvature can vary slightly between halves and/or elements. If the magnification ration is 1: 1, the parameters for the radius of curvature of the two halves/and or elements may be completely identical.

Furthermore, the sections having the first thickness T1 and the second thickness T2 may have identical deviations rather than identical thicknesses/radiuses of curvature. The range of deviation across the entire surface of the primary lens arrangement depends on the shape of the element (s) and is defined by equations taking a multitude of parameters into account. Hence, it is sufficient if corresponding sections of the two halves and/or elements achieve a generally symmetrical shape adjacent to the area of the aperture of the optical aperture element 7.

The secondary lens arrangement 3 comprises at least one secondary lens element 8, 8a, 8b. The secondary lens arrangement 3 is adapted to direct electromagnetic radiation towards the primary lens arrangement 2, or is adapted to receive limited electromagnetic radiation from the primary lens arrangement 2. In other words, the secondary lens arrangement 3 may be arranged before or after the primary lens arrangement 2, as seen in the direction of propagation of electromagnetic radiation emitted by the object to be magnified.

The optical device 1 may comprise an image sensor 4 arranged such that the image sensor 4 shares the optical axis O with the primary lens arrangement 2 and the secondary lens arrangement 3. As mentioned above, the image sensor 4 may be part of the image sensor module 12 of the apparatus 11. Nevertheless, the image sensor 4 may also be a separate, additional image sensor. The image sensor 4 may have a pixel size of 0.7-5 μm, and/or the image sensor 4 may have a diameter of maximum 10 mm.

The optical device 1 may also comprise a tertiary lens arrangement 9 comprising at least one tertiary lens element 10, 10a, 10b. The primary lens arrangement 2 is arranged between the secondary lens arrangement 3 and the tertiary lens arrangement 9 along the optical axis O, as shown in Figs. 1b, 3, and 4.

The secondary lens arrangement 3 may comprise a first secondary lens element 8a and a second secondary lens element 8b, and the tertiary lens arrangement 9 may comprise a first tertiary lens element 10a, 10b and a second tertiary lens element 10b.

The secondary lens arrangement 3 and the tertiary lens arrangement 9 may be identical and symmetrically arranged around the primary lens arrangement 2 (not shown) , i.e. when the magnification ratio is 1: 1. The first secondary lens element 8a and the first tertiary lens element 10a may be identical, and the second secondary lens element 8b and the second tertiary lens element 10b may be identical.

The secondary lens arrangement 3 may be non-identical, as shown in Figs. 1b, 3, and 4. The first secondary lens element 8a and the first tertiary lens element 10a are non-identical, and/or the second secondary lens element 8b and the second tertiary lens element 10b are non-identical.

At least one of the

primary lens elements

5, 5a, 5b, the secondary lens elements 8, 8a, 8b, and/or the tertiary lens elements 10, 10a, 10b may be aspheric.

The

primary lens elements

5, 5a, 5b, the secondary lens elements 8, 8a, 8b, and/or the tertiary lens elements 10, 10a, 10b may comprise optical glass and/or plastic material.

The present invention further relates to a method of providing a magnified image of an object emitting electromagnetic radiation. The method comprises providing a primary lens arrangement 2 defining an optical axis O. The primary lens arrangement 2 is ball-shaped and divided into two halves by means of a plane of symmetry P. The primary lens arrangement 2 comprises an optical aperture element 7 which is adapted to spatially limit propagation of electromagnetic radiation within the primary lens arrangement 2. The optical aperture element 7 extends along the plane of symmetry P. The method furthermore comprises providing a secondary lens arrangement 3 along the optical axis O. The secondary lens arrangement 3 is adapted to direct the electromagnetic radiation towards the primary lens arrangement 2, or is adapted to receive limited electromagnetic radiation from the primary lens arrangement 2. In other words, the secondary lens arrangement 3 can be arranged before or after the primary lens arrangement 2, as seen in the direction of propagation of electromagnetic radiation emitted by the object to be magnified.

Propagation of electromagnetic radiation emitted by the object may be allowed through the secondary lens arrangement 3 prior to the electromagnetic radiation propagating through the primary lens arrangement 2, when the secondary lens arrangement 3 is arranged before the primary lens arrangement 2. Correspondingly, propagation of the limited electromagnetic radiation may be allowed through the secondary lens arrangement 3 after the propagation of the electromagnetic radiation has been spatially limited by the optical aperture element 7, when the secondary lens arrangement 3 is arranged after the primary lens arrangement 2.

The method may further comprise the step of providing a tertiary lens arrangement 9 along the optical axis O, such that the primary lens arrangement 2 is arranged between the secondary lens arrangement 3 and the tertiary lens arrangement 9 along the optical axis O.

Propagation of electromagnetic radiation emitted by the object may be allowed through the tertiary lens arrangement 9 prior to the electromagnetic radiation propagating through the primary lens arrangement 2, when the tertiary lens arrangement 9 is arranged before the primary lens arrangement 2. Correspondingly, propagation of the limited electromagnetic radiation may be allowed through the tertiary lens arrangement 9 after the propagation of the electromagnetic radiation has been spatially limited by the optical aperture element 7, when the tertiary lens arrangement 9 is arranged after the primary lens arrangement 2.

In one embodiment, the secondary lens arrangement 3 is arranged before the primary lens arrangement 2 and the tertiary lens arrangement 9 is arranged after the primary lens arrangement 2, as seen in the direction of propagation of electromagnetic radiation emitted by the object to be magnified. In other words, the secondary lens arrangement 3 is arranged closest to the object to be magnified, and the tertiary lens arrangement 9 is arranged closest to e.g. the image sensor 4.

The secondary lens arrangement 3 and/or the tertiary lens arrangement 9 may comprise at least one aspherical lens. As indicated in Figs. 3 and 4, the secondary lens arrangement may comprise two different aspherical lenses, and the tertiary lens arrangement 9 may comprise two other aspherical lenses. Any suitable number of aspherical lenses may be utilized in each lens arrangement, and the aspherical lenses may be identical or different within each lens arrangement and/or between lens arrangements.

The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc. ) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal” , “vertical” , “left” , “right” , “up” and “down” , as well as adjectival and adverbial derivatives thereof (e.g., “horizontally” , “rightwardly” , “upwardly” , etc. ) , simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.

Claims

An optical device (1) for enabling magnification, said optical device (1) comprising a primary lens arrangement (2) and a secondary lens arrangement (3) defining an optical axis (O) ,

-said primary lens arrangement (2) is ball-shaped and has a plane of symmetry (P) dividing said primary lens arrangement (2) into two halves,

the primary lens arrangement (2) comprising

--at least one primary lens element (5, 5a, 5b) , said primary lens element (s) (5, 5a, 5b) forming one or both of said halves,

--an optical aperture element (7) adapted to spatially limit propagation of electromagnetic radiation,

said optical aperture element (7) extending along said plane of symmetry (P) ;

-said secondary lens arrangement (3) comprising at least one secondary lens element (8, 8a, 8b) , and

said secondary lens arrangement (3) being adapted to direct electromagnetic radiation towards said primary lens arrangement (2) , or being adapted to receive limited electromagnetic radiation from the primary lens arrangement (2) .
The optical device (1) according to claim 1, further comprising an image sensor (4) , said image sensor (4) sharing said optical axis (O) .
The optical device (1) according to claim 2, wherein said image sensor (4) has a pixel size of 0.7-5 μm, and/or said image sensor (4) has a diameter of maximum 10 mm.
The optical device (1) according to any one of the previous claims, wherein said primary lens arrangement (2) is biconvex, preferably equiconvex.
The optical device (1) according to any one of the previous claims, wherein each primary lens element (5, 5a, 5b) is at least partially convex.
The optical device (1) according to any one of the previous claims, wherein said primary lens element (5) is a monolithic, biconvex lens element,

said optical aperture element (7) extending within said monolithic, biconvex lens element (5) .
The optical device (1) according to any one of claims 1 to 5, wherein said primary lens arrangement (2) comprises two primary lens element (s) (5a, 5b) in the form of a first plano-convex lens element (5a) and a second planoconvex lens element (5b) ,

a first main planar surface (6a) of said first plano-convex lens element (5a) and a second main planar surface (6b) of said second plano-convex lens element (5b) extending in parallel with each other and with said plane of symmetry (P) ,

said optical aperture element (7) extending between, and in abutment with, said first main planar surface (6a) and said second main planar surface (6b) .
The optical device (1) according to claim 7, wherein said first plano-convex lens element (5a) has a first thickness (T1) as seen from said first main planar surface (6a) , and said second plano-convex lens element (5b) has a second thickness (T2) as seen from said second main planar surface (6b) ,

said first thickness (T1) and said second thickness (T2) being identical for at least one section of said first plano-convex lens element (5a) and one section of said second plano-convex lens element (5b) .
The optical device (1) according to any one of the previous claims, further comprising a tertiary lens arrangement (9) comprising at least one tertiary lens element (10, 10a, 10b) ,

said primary lens arrangement (2) being arranged between said secondary lens arrangement (3) and said tertiary lens arrangement (9) along said optical axis (O) .
The optical device (1) according to any one of the previous claims, wherein at least one of said primary lens element (s) (5, 5a, 5b) , said secondary lens element (s) (8, 8a, 8b) , and/or said tertiary lens element (s) (10, 10a, 10b) is/are aspheric.
An apparatus (11) comprising the optical device (1) according to any one of claims 1 to 10.
The apparatus (11) according to claim 11, further comprising an image sensor module (12) , an image sensor of said image sensor module (12) being the image sensor (4) of said optical device (1) .
A method of providing a magnified image of an object emitting electromagnetic radiation, said method comprising the steps of:

-providing a primary lens arrangement (2) defining an optical axis (O) ,

said primary lens arrangement (2) being ball-shaped and divided into two halves by means of a plane of symmetry (P) ,

said primary lens arrangement (2) comprising an optical aperture element (7) adapted to spatially limit propagation of electromagnetic radiation within said primary lens arrangement (2) , said optical aperture element (7) extending along said plane of symmetry (P) ,

-providing a secondary lens arrangement (3) along said optical axis (O) , said secondary lens arrangement (3) being adapted to direct said electromagnetic radiation towards said primary lens arrangement (2) , or being adapted to receive limited electromagnetic radiation from said primary lens arrangement (2) ,

-allowing propagation of electromagnetic radiation emitted by said object through said secondary lens arrangement (3) prior to said electromagnetic radiation propagating through said primary lens arrangement (2) , or

-allowing propagation of said limited electromagnetic radiation through said secondary lens arrangement (3) after said propagation of said electromagnetic radiation has been spatially limited by said optical aperture element (7) .
The method according to claim 13, further comprising the steps of:

-providing a tertiary lens arrangement (9) along said optical axis (O) , such that said primary lens arrangement (2) is arranged between said secondary lens arrangement (3) and said tertiary lens arrangement (9) along said optical axis (O) ,

-allowing propagation of electromagnetic radiation emitted by said object through said tertiary lens arrangement (9) prior to said electromagnetic radiation propagating through said primary lens arrangement (2) , or

-allowing propagation of said limited electromagnetic radiation through said tertiary lens arrangement (9) after said propagation of said electromagnetic radiation has been spatially limited by said optical aperture element (7) .
The method according to claim 13 or 14, wherein said secondary lens arrangement (3) and/or said tertiary lens arrangement (9) comprises at least one aspherical lens.