An optical tuneable lens assembly

Abstract

The invention relates to an optical tuneable lens assembly for a compact optical device, the optical tuneable lens assembly (1) comprising at least one transparent membrane (10), a transparent deformable non-fluid lens-body (30), the deformable non-fluid lens body abuts with the transparent membrane(s) (10), the deformable non-fluid lens body conforms to the shape of the transparent membrane(s), and a ring-formed actuator (40). The ring-formed actuator (40) and the transparent membrane(s) (10) are co-axial. The ring-formed actuator, when activated, is arranged to apply a radial force to the transparent membrane(s), causing deformation of the transparent membrane(s).

Description

[0001] 84881PC01

[0002] 1

[0003] AN OPTICAL TUNEABLE LENS ASSEMBLY

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to an optical tuneable lens assembly comprising a transparent deformable non-fluid lens body and at least one transparent membrane and a method for deforming the membrane and hereby deforming the lens body.

[0006] BACKGROUND OF THE INVENTION

[0007] Optical lenses are widely used in various applications, including cameras, microscopes, and other imaging systems. Traditional optical lenses are typically made from rigid materials, which limits their ability to adapt to different focal lengths and other optical properties. This limitation necessitates the use of multiple lenses or complex mechanical systems to achieve the desired optical performance.

[0008] Recent advancements have introduced deformable lenses that can change shape in response to external stimuli, such as electrical or mechanical forces. These deformable lenses offer greater flexibility and adaptability compared to traditional rigid lenses. However, existing deformable lens systems often suffer from non- uniform force distribution, limited range of motion, and increased stress concentrations, which can affect their performance and durability.

[0009] There is a need in the art for an improved optical tuneable lens assembly that can provide uniform force distribution, enhanced control and precision, reduced stress concentration, and a greater range of motion. Such an assembly would offer better optical performance, faster response times, and a more compact and lightweight design, making it suitable for a wide range of advanced optical applications. 84881PC01

[0010] 2

[0011] Hence, an improved optical tuneable lens assembly would be advantageous, and in particular a more efficient and / or reliable optical tuneable lens assembly would be advantageous.

[0012] OBJECT OF THE INVENTION

[0013] The object of the invention is to provide an optical tuneable lens assembly wherein the actuator extends beyond the edge of the transparent membrane, ensuring a uniform radial force distribution across the membrane for consistent deformation and optimal optical performance.

[0014] It is a further object of the present invention to enable precise control over the deformation of the transparent membrane, allowing for accurate adjustments in the lens shape and improved optical properties.

[0015] It is a further object of the present invention to provide an alternative to the prior art.

[0016] In particular, it may be seen as an object of the present invention to provide an optical tuneable lens assembly that solves the above-mentioned problems of the prior art.

[0017] SUMMARY OF THE INVENTION

[0018] Thus, the above described object and several other objects are intended to be obtained in a first aspect of the invention by providing an optical tuneable lens assembly for a compact optical device, the optical tuneable lens assembly comprising: o at least one transparent membrane, the transparent membrane(s) being substantially circular and comprises a circumferential radius, an upper surface, a lower surface, an upper edge at the boundary of the upper surface, a lower edge at the boundary of the lower surface, and a boundary surface between the upper edge and the lower edge, 84881PC01

[0019] 3 o a transparent deformable non-fluid lens-body, the deformable nonfluid lens body abuts with the transparent membrane(s), the deformable non-fluid lens body conforms to the shape of the transparent membrane(s), and o a ring-formed actuator, the ring-formed actuator is, at least partly, ring-formed and comprises an inner actuator radius and an outer actuator radius, wherein the ring-formed actuator (40) and the transparent membrane(s) are coaxial, the circumferential radius of the transparent membrane(s) is less than the outer actuator radius, and the ring-formed actuator, when activated, is arranged to apply a variable radial force to the transparent membrane(s), causing deformation of the transparent membrane(s).

[0020] The present invention relates to optical lens assemblies, and more particularly to an optical tuneable lens assembly that comprises a transparent deformable non- fluid lens body in contact with a transparent membrane, and an actuator for generating controllable bending of the transparent membrane. The present invention pertains to an advanced optical tuneable lens assembly that enables precise and controllable deformation of a transparent membrane, and thereby deforming the non-fluid lens body, and thereby allowing for dynamic adjustment of the tuneable lens's optical properties with tuneable focal length capabilities.

[0021] The lens assembly features at least one substantially circular transparent membrane. The transparent membrane comprises upper and lower surfaces, with corresponding upper and lower edges, and a boundary surface connecting these edges. The transparent membrane comprises a circumferential radius. The transparent membrane is deformable by the ring-formed actuator affecting the transparent membrane(s). The boundary surface, which follows the circumferential radius, is the outer peripheral surface situated between the upper and lower edges of the transparent membrane.

[0022] In contact with the transparent membrane(s) is a transparent, deformable non- fluid lens body. This lens body is designed to conform to the shape of the 84881PC01

[0023] 4 transparent membrane(s), ensuring a seamless interface that maintains optical clarity and integrity.

[0024] In the tuneable lens assembly, the transparent, deformable, non-fluid lens body is sandwiched between one transparent membrane and either another transparent membrane or a transparent back window, so that the tuneable lens assembly constitutes a lens having an optical axis intersecting one transparent membrane and either the other transparent membrane or the transparent back window.

[0025] The non-fluid lens body abuts the inwardly facing surfaces of one transparent membrane and either the other transparent membrane or the transparent back window, such that the non-fluid lens body is deformed when any of the membranes are deformed.

[0026] A critical component of the assembly is the ring-formed actuator, which is arranged to generate controllable bending of the transparent membrane(s). The ring-formed actuator when activated may be contracting, or it may be expanding, and thereby applying a variable radial force to the transparent membrane(s) to change the overall shape of the lens assembly.

[0027] When the ring-formed actuator is not activated, no force is applied to the transparent membrane.

[0028] When the ring-shaped actuator is activated and therefore contracts or expands, it applies a variable radial force to the transparent membrane(s). This force causes the membrane(s) to deform, which in turn changes the shape of a non-fluid lens body that is in contact with the membrane(s). As the shape of the non-fluid lens body follows the deformation of the membrane(s), its optical properties are altered. This mechanism allows for precise control over the tuneable lens assembly's optical characteristics, enabling applications in various fields requiring adjustable optics.

[0029] The ring-shaped actuator comprises an inner actuator radius and an outer actuator radius. The actuator may be co-axial with the transparent membrane(s) and the actuator comprises an outer actuator radius greater than the circumferential radius of the membrane(s). When activated, the actuator applies a 84881PC01

[0030] 5 variable radial force to the transparent membrane(s), causing them to deform in a controlled manner.

[0031] In the context of this invention, variable radial force refers to the force exerted by the ring-formed actuator on the circular membrane, directed either towards the centre or away from the centre of the membrane, depending on whether the ring- formed actuator contracts of expands. This force is responsible for deforming the membrane and subsequently altering the shape and optical properties of the nonfluid lens body. That the radial force is variable is to be understood that the magnitude and direction of this radial force can change dynamically. For instance, if the ring-formed actuator comprises piezo-electric material, the contraction or expansion of the ring-formed actuator depends on the magnitude of the electric field applied to it.

[0032] The membrane(s) may be pre-shaped to control the direction the membrane(s) will bend when subjected to a radial force. This may be achieved by coating design, plastic moulding, or glass thermal forming. The membrane(s) may for instance comprises a groove locally weakening the membrane(s), such that the membrane(s) will bend in a specific direction.

[0033] In the context of the invention, the non-fluid lens body changes its optical properties by deforming in response to the radial force applied by the actuator on the membrane(s), which alters the non-fluid lens body's shape indirectly through the deformation of the transparent membrane.

[0034] Preferably the ring-formed actuator is a complete ring. This means the actuator forms a continuous, unbroken circle. This design likely ensures uniform distribution of force or motion around the entire circumference, which can be beneficial for applications requiring consistent performance.

[0035] In an alternative design possible the ring-formed actuator may not be a complete ring. Instead, the ring-formed actuator may be made up of several segments, each forming a part of the ring. In this alternative design, the actuator is divided into multiple segments. Each segment is a portion of the ring, and together, these segments can form a shape similar to a full ring. This approach can allow for 84881PC01

[0036] 6 easier replacement of individual segments, customization of the actuator's shape, or adaptation to space constraints in the application.

[0037] The innovative aspect of this invention lies in the actuator's ability to apply a radial force that results in the deformation of the transparent membrane(s) and thereby the non-fluid lens body. This deformation allows for precise control over the optical characteristics of the lens assembly, such as focus, curvature, and other parameters. That the outer actuator radius is greater than the circumferential radius of the membrane ensures a uniform force distribution, which leads to consistent and predictable deformation patterns, as the actuator affects the diaphragm at the boundary surface, or at the edges and the upper and / or lower surface adjacent to the edges. This optical tuneable lens assembly is particularly suitable for applications requiring high precision and adaptability, such as advanced imaging systems, adaptive optics, and other optical devices where dynamic control of lens properties is important.

[0038] According to an embodiment, the circumferential radius of the transparent membrane(s) is less than or equal to the inner actuator radius, at least when the ring-formed actuator is not activated.

[0039] The optical tuneable lens assembly may be designed such that the circumferential radius of the transparent membrane(s) is less than or equal to the inner actuator radius when the ring-formed actuator is not activated. This makes it possible when the actuator is activated to directly apply a radial force to the boundary surface of the transparent membrane that results in the deformation of the transparent membrane(s).

[0040] If the ring-formed actuator is fixed to the boundary surface of the membrane(s), then if the ring-formed actuator expands, the inner actuator radius increases, and the ring-formed actuator may pull at the boundary surface of the transparent membrane(s) and hereby deform the transparent membrane(s).

[0041] According to an embodiment, the ring-formed actuator, when activated, applies a radial force, either directly or via one, or more, intermediate part(s), to the boundary surface of the transparent membrane. 84881PC01

[0042] 7

[0043] The optical tuneable lens assembly comprises a ring-formed actuator that, when activated, applies a radial force to the boundary surface of the transparent membrane. This force may be applied either directly or through the intermediate part(s). This design allows for precise and controlled deformation of the transparent membrane, enhancing the tunability of the lens assembly.

[0044] By applying the radial force to the boundary surface, either pushing or pulling, the actuator ensures a uniform and predictable deformation pattern, which is maintaining the optical integrity and performance of the lens. The use of intermediate parts, if employed, provides additional flexibility in the design and operation of the actuator, allowing for fine-tuned adjustments to the deformation process.

[0045] The intermediate part(s) may be circular following the ring-formed actuator all the way round in a circle, but there may be a plurality of intermediate parts distributed evenly around the transparent membrane(s).

[0046] According to an embodiment, the ring-formed actuator, when activated, applies a radial force, either directly or via the one, or more, intermediate part(s), to the upper edge and / or the lower edge and to a portion of the upper surface and / or the lower surface adjacent to the upper or lower edge of the transparent membrane.

[0047] The optical tuneable lens assembly may be designed such that the ring-formed actuator, when activated, applies a radial force either directly or via the intermediate part(s) to the upper edge and / or the lower edge of the transparent membrane. Additionally, this force can be applied to a portion of the upper surface and / or the lower surface adjacent to these edges.

[0048] This configuration allows for a comprehensive and controlled deformation of the transparent membrane, enhancing the precision and tunability of the lens assembly. By targeting the edges and adjacent surfaces, the actuator ensures that the deformation is evenly distributed, maintaining the optical clarity and performance of the lens. 84881PC01

[0049] 8

[0050] According to an embodiment, the transparent membrane(s) comprises a circular groove.

[0051] The transparent membrane(s) of the optical tuneable lens assembly includes a circular groove. This groove is strategically designed to locally weaken the membrane, facilitating controlled bending such that the membrane(s) will bend in a specific direction.

[0052] The introduction of the circular groove helps to control the deformation of the membrane(s), ensuring that the bending occurs as desired. This targeted weakening enhances the spherical quality of the lens at the aperture area, resulting in improved optical performance and precision.

[0053] By incorporating a circular groove, the lens assembly may achieve better control over the shape and curvature of the transparent membrane(s) during deformation. This leads to more accurate and consistent adjustments of the lens's optical properties, making it highly suitable for applications that demand high precision and adaptability.

[0054] According to an embodiment, the optical lens assembly further comprising one, or more, intermediate part(s) connecting at least one of the transparent membranes and the ring-formed actuator.

[0055] The optical lens assembly may comprise one, or more, intermediate part(s) that connects at least one of the transparent membranes to the ring-formed actuator. This intermediate part may play a role in transmitting the radial force from the actuator to the membrane.

[0056] When the optical lens assembly comprises two membranes, the optical lens assembly may comprise two intermediate parts, one for each membrane, or a plurality of intermediate parts distributed evenly between the two membranes.

[0057] The inclusion of the intermediate parts may allow for more precise control over the deformation of the transparent membrane. By providing a direct connection between the actuator and the membrane, the intermediate parts ensure that the 84881PC01

[0058] 9 force is evenly distributed, leading to consistent and predictable deformation patterns.

[0059] The intermediate parts help to maintain the optical clarity and integrity of the lens by ensuring that the deformation occurs in a controlled manner. The use of the intermediate parts also adds flexibility to the design of the actuator mechanism, allowing for fine-tuned adjustments to the deformation process. This may further improve the tunability and functionality of the optical lens assembly.

[0060] According to an embodiment, the optical lens assembly is adapted to transfer force from the ring-formed actuator to the transparent membrane(s).

[0061] The optical lens assembly is specifically adapted to transfer force from the ring- formed actuator to the transparent membrane(s). The design ensures that the force applied by the ring-formed actuator is effectively transmitted to the transparent membrane(s), causing the transparent membrane(s) to deform in a controlled manner. This deformation transforms the flat membrane into a lens with the desired optical properties, such as curvature and focal length or may transform a lens with a curvature into a different curvature or even to become flat.

[0062] By enabling the precise transfer of force, the tunability and performance of the optical lens assembly is enhanced. The controlled deformation allows for accurate adjustments to lens assembly's optical characteristics, making it highly suitable for applications that require dynamic control of lens properties.

[0063] According to an embodiment, the ring-formed actuator is made of a material comprising a piezoelectric material.

[0064] The ring-formed actuator may be made of a material comprising a piezoelectric material. This choice of material allows the ring-formed actuator to generate precise and controllable variable radial forces when activated. The ring-formed actuator is activated by being subjected to an electric field. When subjected to an electric field the ring-formed actuator contract or expand. The size of the 84881PC01

[0065] 10 contraction or expansion of the ring-formed actuator depends on the magnitude of the electric field applied to it.

[0066] The use of piezoelectric material for the actuator enhances the responsiveness and accuracy of the optical lens assembly. When activated, the piezoelectric actuator can apply a radial force to the transparent membrane(s) with high precision, enabling fine-tuned adjustments to the lens's optical properties.

[0067] According to an embodiment, the ring-formed actuator is made of a material comprising shape memory alloys, electroactive polymers, magnetostrictive materials and / or hydrogels.

[0068] The ring-formed actuator may alternatively be made of materials that include shape memory alloys, electroactive polymers, magnetostrictive materials, and / or hydrogels. These materials offer alternative options to piezoelectric materials, each providing unique properties that can be leveraged to achieve precise and controllable deformation of the transparent membrane.

[0069] Shape memory alloys can change shape in response to temperature changes, allowing for controlled deformation when heated or cooled. Electroactive polymers can deform in response to an electric field, similar to piezoelectric materials, but with different mechanical properties. Magnetostrictive materials change shape in response to a magnetic field, providing another method for applying force to the membrane. Hydrogels can swell or contract in response to environmental changes, such as pH or temperature, enabling dynamic control of the membrane's shape.

[0070] These alternative materials enhance the versatility and adaptability of the optical lens assembly. By selecting the appropriate material for the actuator, the lens assembly can be tailored to specific applications and requirements, ensuring optimal performance and precision.

[0071] According to an embodiment, the ring-formed actuator and the transparent membrane are connected by glue, adhesive tape, anodic bonding, or laser welding. 84881PC01

[0072] 11

[0073] The ring-formed actuator and the transparent membrane(s) may be connected using methods such as glue, adhesive tape, anodic bonding, or laser welding. These connection techniques ensure a secure and stable attachment between the actuator and the membrane.

[0074] Using glue or adhesive tape provides a straightforward and flexible method for attaching the actuator to the membrane, allowing for easy assembly and potential reconfiguration. Anodic bonding offers a strong and durable connection by creating a bond at the atomic level, which is particularly useful for applications requiring high mechanical strength and stability. Laser welding provides a precise and robust connection by using focused laser energy to fuse the materials together, ensuring minimal disruption to the optical properties of the membrane.

[0075] These connection methods enhance the overall performance and reliability of the optical lens assembly. By ensuring a secure attachment, the assembly can maintain consistent and predictable deformation patterns.

[0076] According to an embodiment, the ring-formed actuator, one, or more, intermediate part(s), and the transparent membrane are connected by glue, adhesive tape, anodic bonding, or laser welding.

[0077] The ring-formed actuator, one or more intermediate part(s), and the transparent membrane are connected using methods such as glue, adhesive tape, anodic bonding, or laser welding. These connection techniques ensure a secure and stable attachment between these components.

[0078] Using glue or adhesive tape provides a straightforward and flexible method for attaching the actuator, intermediate parts, and membrane, allowing for easy assembly and potential reconfiguration. Anodic bonding offers a strong and durable connection by creating a bond at the atomic level, which is particularly useful for applications requiring high mechanical strength and stability. Laser welding provides a precise and robust connection by using focused laser energy to fuse the materials together, ensuring minimal disruption to the optical properties of the membrane. By ensuring a secure attachment, the assembly can maintain consistent and predictable deformation patterns. 84881PC01

[0079] 12

[0080] According to an embodiment, at least one intermediate part(s) comprises a groove.

[0081] At least one of the intermediate parts comprises a groove. This groove may be designed to enhance the functionality of the intermediate part by providing a specific area for controlled deformation or flexibility. Preferably each of the intermediate part(s) comprises a groove.

[0082] The inclusion of a groove in the intermediate parts allows for more precise control over the transmission of force from the ring-formed actuator to the transparent membrane(s).

[0083] By incorporating a groove, the intermediate parts may better accommodate the deformation of the transparent membrane, leading to more accurate and consistent adjustments of the lens's optical properties.

[0084] According to an embodiment, the inner surface of the ring-formed actuator is not perpendicular to the upper surface and / or the lower surface of the ring-formed actuator.

[0085] The inner surface of the ring-formed actuator may not be perpendicular to the upper and / or lower surface of the actuator. Instead, this inner surface may be slightly tilted. This design feature is intended to help control the bending of the transparent membrane(s).

[0086] The slight tilt of the inner surface may allow for more precise application of radial force, ensuring that the deformation of the transparent membrane(s) is controlled and predictable. This enhances the tunability and performance of the optical lens assembly by providing better control over the shape and curvature of the membrane(s) during deformation.

[0087] According to an embodiment, the optical lens assembly further comprising a pressure ring mounted around the ring-formed actuator, wherein the pressure ring is arranged to apply a pre-load on the ring-formed actuator. 84881PC01

[0088] 13

[0089] The pressure ring, which may be made of a metal with a high coefficient of thermal expansion (CTE), is heated prior to mounting to enlarge its inner diameter. Alternatively, the pressure ring may be made of plastic, ceramic, glass or composite material. Upon heating, the pressure ring expands and is then mounted around the ring-formed actuator. As the pressure ring cools, it contracts, thereby applying a pre-load on the ring-formed actuator. When the ring-formed actuator is activated, it contracts, and the pre-load from the pressure ring, combined with the radial force from the actuator, results in a higher total radial force.

[0090] In some embodiments, a first flexural rigidity of the one or more intermediate part(s) or of at least part of the transparent membrane(s) outside an aperture in a direction parallel to an optical axis is smaller than a second flexural rigidity of the one or more intermediate part(s) or of at least part of the transparent membrane(s) outside the aperture in a direction perpendicular to the optical axis.

[0091] Here, the first flexural rigidity refers to the resistance to bending or flexing of the intermediate part(s) or membrane(s) when a force is applied in a direction parallel to the optical axis of the lens assembly. This lower rigidity enables easier deformation along the optical axis, allowing the membrane or intermediate part to bend more readily in this direction. In contrast, the second flexural rigidity denotes the resistance to bending in a direction perpendicular to the optical axis (i.e., radially outward from the center of the lens). By designing the groove or structural features such that the first flexural rigidity is smaller than the second, the assembly achieves controlled and preferential bending along the optical axis, which is essential for precise adjustment of the lens shape and its optical properties.

[0092] This anisotropic rigidity is typically achieved by introducing a groove of sufficient depth, such as at least 10% of the thickness of the part, thereby locally weakening the structure and facilitating targeted deformation when the actuator applies a radial force.

[0093] Aperture in the context of this patent application refers to the opening or region within the optical tuneable lens assembly through which light passes, thus may be referred to as clear aperture, denoting the unobstructed portion of the lens or 84881PC01

[0094] 14 membrane that is available for light transmission, thus where optical performance is critical.

[0095] The direction perpendicular to the optical axis may also be referred as radial direction extending outward from the centrer of the lens toward the edge

[0096] The direction parallel to the optical axis refers to the direction aligned with the central axis of the lens assembly.

[0097] Flexural rigidity may also be referred to as to stiffness.

[0098] In some other embodiments, the optical tuneable lens assembly comprises the groove on a top or bottom surface of said at least one intermediate part(s), thereby the first flexural rigidity of the one or more intermediate part(s) outside the aperture in the direction parallel to the optical axis is smaller than the second flexural rigidity of the one or more intermediate part(s) in a direction perpendicular to the optical axis.

[0099] In certain embodiments of the optical tuneable lens assembly, a groove is formed on the top or bottom surface of at least one intermediate part positioned outside the aperture region. This structural feature is specifically designed to locally weaken the intermediate part, thereby reducing its flexural rigidity in the direction parallel to the optical axis compared to the direction perpendicular to the optical axis. As a result, the intermediate part bends more readily along the optical axis, facilitating precise and controlled deformation of the transparent membrane and, consequently, the lens body. At the same time, the intermediate part maintains greater stiffness in the radial direction, which helps preserve the overall structural integrity of the assembly. This anisotropic rigidity, achieved by the groove, enables dynamic adjustment of the lens's optical properties while ensuring consistent optical performance within the clear aperture.

[0100] In some further embodiments, the optical tuneable lens assembly comprises the groove on a top or bottom surface of said at least one intermediate part(s), thereby the first flexural rigidity of the one or more intermediate part(s) outside the aperture in the direction parallel to the optical axis is smaller than the second 84881PC01

[0101] 15 flexural rigidity of the one or more intermediate part(s) in a direction perpendicular to the optical axis.

[0102] In further embodiments of the optical tuneable lens assembly, a groove is provided on the top or bottom surface of at least one intermediate part located outside the aperture region. This groove is specifically engineered to locally reduce the flexural rigidity of the intermediate part in the direction parallel to the optical axis, while maintaining a higher flexural rigidity in the direction perpendicular to the optical axis. Such a configuration enables the intermediate part to bend more easily along the optical axis, thereby allowing for precise and controlled deformation of the transparent membrane and the lens body. At the same time, the intermediate part retains greater stiffness in the radial direction, which is essential for preserving the structural integrity of the assembly. By introducing this anisotropic rigidity through the groove, the lens assembly achieves dynamic adjustment of its optical properties, ensuring reliable and consistent optical performance within the clear aperture.

[0103] The groove depth should be at least 10% of its thickness, such as the thickness of the part, the intermediate part or the membrane, on which it is formed.

[0104] This minimum groove depth ensures that the local weakening is sufficient to effectively reduce the flexural rigidity in the direction parallel to the optical axis, thereby enabling controlled and precise deformation of the intermediate part or membrane when actuated, while maintaining the necessary structural integrity in the radial direction.

[0105] In some embodiments, the at least one intermediate part(s) is flat and connected to the lower or to the upper surface of the at least part of the transparent membrane(s) outside the aperture, thereby the first flexural rigidity of the one or more intermediate part(s) outside the aperture in the direction parallel to the optical axis is smaller than the second flexural rigidity of the one or more intermediate part(s) in a direction perpendicular to the optical axis.

[0106] In a second aspect, the invention relates to a compact optical device comprising an optical tuneable lens assembly according to the first aspect. 84881PC01

[0107] 16

[0108] The compact optical devicesystem typically comprises a lens stack and the optical tuneable lens assembly may be an additional lens in the optical lens stack, or compact optical devicemay have a lens module comprising the optical tuneable lens assembly.

[0109] The optical device may be a compact imaging camera system, or it may be a projector, or a microscope or other optical devices.

[0110] In a third aspect, the invention relates to a method of causing deformation of at least one transparent membrane within an optical tuneable lens assembly for a compact optical device, the optical tuneable lens assembly is comprising: o at least one transparent membrane, the transparent membrane(s) being substantially circular and comprises a circumferential radius, an upper surface, a lower surface, an upper edge at the boundary of the upper surface, a lower edge at the boundary of the lower surface, and a boundary surface between the upper edge and the lower edge, o a transparent deformable non-fluid lens-body, the deformable nonfluid lens body abuts with the transparent membrane(s), the deformable lens body conforms to the shape of the transparent membrane(s), and o a ring-formed actuator, the ring-formed actuator is, at least partly, ring-formed and comprises an inner actuator radius and an outer actuator radius, wherein the ring-formed actuator and the transparent membrane(s) are co-axial, the circumferential radius of the transparent membrane is less than the outer actuator radius, and the ring-formed actuator, when activated, is applying a variable radial force to the transparent membrane(s), causing deformation of the transparent membrane(s).

[0111] The first, second and third aspect of the present invention may each be combined with any of the other aspects. These and other aspects of the invention will be 84881PC01

[0112] 17 apparent from and elucidated with reference to the embodiments described hereinafter.

[0113] BRIEF DESCRIPTION OF THE FIGURES

[0114] The optical tuneable lens assembly according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

[0115] Fig. la-f illustrates the optical tuneable lens assembly wherein the membranes are positioned inside the ring-formed actuator.

[0116] Fig. 2a-b illustrates the transparent membrane.

[0117] Fig. 3a-c illustrates the ring-formed actuator.

[0118] Fig. 4a-e illustrates another embodiment of an optical tuneable lens assembly, wherein the transparent membranes are placed so that the upper edge and / or the lower edge and a portion of the upper surface and / or the lower surface adjacent to the upper or lower edge of the transparent membrane are attached to the upper surface and / or the lower surface of the ring-formed actuator.

[0119] Fig. 5a and 5b illustrate two embodiments where there is only one transparent membrane.

[0120] Fig. 6 illustrates a compact imaging camara system.

[0121] Fig. 7a and 7b illustrates a transparent membrane comprising a circular groove. Fig. 8 illustrates a transparent membrane attached to an intermediate part.

[0122] Fig. 9 illustrates a transparent membrane attached to a number of intermediate parts, where each intermediate part also is attached to the ring-formed actuator. Fig. 10 illustrates an embodiment with an intermediate part.

[0123] Fig. 11 illustrates an embodiment with two intermediate parts glued together.

[0124] Fig. 12 illustrates an embodiment where the transparent membrane is attached directly to the ring-formed actuator.

[0125] Fig. 13 illustrates an embodiment where an intermediate part is connecting the ring-formed actuator and the transparent membrane.

[0126] Fig. 14 illustrates an embodiment where the transparent membrane is attached to the ring-formed actuator with glue. 84881PC01

[0127] 18

[0128] Fig. 15 shows an embodiment, where a pressure ring is mounted around the ring- formed actuator.

[0129] DETAILED DESCRIPTION OF AN EMBODIMENT

[0130] Fig. la-f illustrates an optical tuneable lens assembly 1. Fig. la illustrates the optical tuneable lens assembly 1 comprising two transparent membranes 10 with a non-fluid lens body 30 sandwiched between the two transparent membranes 10. A ring-formed actuator 40 is surrounding the transparent membranes 10. When the ring-formed actuator is activated, it is in this embodiment contracting and thereby applying a radial force 39, illustrated by arrows, to the transparent membranes by applying the radial force to the boundary surface 20 of the transparent membrane. The transparent membranes 10 comprises an upper surface 12 and a lower surface 14.

[0131] Fig. la-lb illustrated that when the radial force 39 is applied to the transparent membranes 10, the transparent membranes deform. This is illustrated in fig. lb, wherein the transparent membranes are deformed so that the non-fluid lens body 30 also changes form as it abuts the transparent membranes 10 which when deforming exercises a pressure on the non-fluid lens body making the non-fluid lens body deform. Hereby the non-fluid lens body takes the form of a lens making it deflect light beams entering the non-fluid lens body.

[0132] Fig. lc illustrates the optical tuneable lens assembly 1 seen from above with the ring-formed actuator 40 surrounding the transparent membranes 10. Fig. Id illustrates the optical tuneable lens assembly 1 in 3D view with the ring-formed actuator 40 surrounding the transparent membranes 10.

[0133] Fig. le and If illustrates an optical tuneable lens assembly 1 wherein the ring- formed actuator 40 is expanding instead of contracting. In this embodiment when the ring-formed actuator is relaxed, shown in fig. le, the membranes 10 are bended, and when the ring-formed actuator is activated, the ring-formed actuator, which is attached to the membranes, pulls in the membranes changing the form of the membranes towards the flat form illustrated in fig. If. Whether the membranes are deforming to the flat form or to an intermediate form, 84881PC01

[0134] 19 wherein the membranes are less bended than in fig. le depends on variable radial force applied to the membranes.

[0135] Fig. 2a-b illustrates the transparent membrane 10. Fig. 2a illustrates the transparent membrane in a 3D-view. The transparent membrane comprises an upper surface 12 and a lower surface 14, not visible as it is on the non-visible underside, an upper edge 16 at the boundary of the upper surface, a lower edge 18 at the boundary of the lower surface, and a boundary surface 20 between the upper edge and the lower edge. Fig. 2b illustrates the transparent membrane 10 seen from above, showing the upper surface 12 and the upper edge 16. Also, fig. 2b shows the circumferential radius 15, which it the distance between the centre 21 of the upper surface 12 of the transparent membrane and the upper edge 16.

[0136] Fig. 3a-c illustrates the ring-formed actuator 40. Fig. 3a illustrates the ring- formed actuator in a 3D-view. Fig. 3b illustrates the ring-formed actuator seen from above showing the inner actuator radius 42, which it the distance between the centre 41 of the ring-formed actuator and the inner surface 43 of the ring- formed actuator, and the outer actuator radius 44, which it the distance between the centre 41 of the ring-formed actuator and the outer surface 45 of the ring- formed actuator.

[0137] It is possible that the ring-formed actuator may not be a complete ring, but only is partially ring-formed. This is illustrated in fig. 3c, wherein the ring-formed actuator 40 comprises four segments 40a-40d. These segments, when activated, apply force to the transparent membrane separately but preferably synchronously. The ring-formed actuator may comprise four, six, eight or any suitable number of segments.

[0138] Fig. 4a-f illustrates another embodiment of an optical tuneable lens assembly 1, wherein the transparent membranes 10 are placed so the upper edge 16 and / or the lower edge 18 and a portion of the upper surface and / or the lower surface adjacent to the upper or lower edge of the transparent membrane are attached to the upper surface 47 and / or the lower surface 49 of the ring-formed actuator 40. 84881PC01

[0139] 20

[0140] The transparent membrane, the ring-formed actuator and possible intermediate parts may be attached by glue, adhesive tape, anodic bonding, or laser welding. When the ring-formed actuator is activated, the ring-formed actuator is in the embodiment shown in fig. 4a and 4b contracting and thereby applying a radial force 39, illustrated by arrows, to the transparent membranes.

[0141] Fig. 4b illustrates that when the radial force 39 is applied to the transparent membranes 10, the transparent membranes deform. When the transparent membranes deform then the non-fluid lens body 30 also deform as it abuts the transparent membranes 10, which when deforming exercises a pressure on the non-fluid lens body making the non-fluid lens body deform. Hereby the non-fluid lens body takes the form of a lens making it deflect light beams entering the non- fluid lens body.

[0142] Fig. 4c illustrates a 3D-view of the transparent membrane 10 attached to the ring- formed actuator 40. The lower edge 18 and the lower surface 14 adjacent to the lower edge of the transparent membrane is attached to the upper surface 47 of the ring-formed actuator 40 and is attached to the upper surface 47 of the ring- formed actuator, preferably by glue.

[0143] Figures 4d and 4e shows an alternative design of an optical tuneable lens assembly, where the ring-shaped actuator 40 expands rather than contracts. In this embodiment, when the ring-shaped actuator is in a relaxed state, as shown in Figure 4d, the membranes 10 are bended or curved. Upon activation, the ringshaped actuator, which is connected to the membranes, expands and thereby pulls the membranes, changing their shape towards the flat configuration illustrated in Figure 4e. The degree to which the membranes flatten or assume an intermediate shape, less curved than in Figure 4d, is determined by the varying radial force applied to the membranes."

[0144] Fig. 5a and 5b illustrate two embodiments where there is only one transparent membrane 10. Fig. 5a illustrates an embodiment where the ring-formed actuator 40 applies a force to the boundary surface 20 of the transparent membrane. Only one side of the non-fluid lens body 30 is abutting a transparent membrane. The 84881PC01

[0145] 21 other side of the non-fluid lens body 30 is abutting a transparent back window 90, which is not being deformed by the ring-formed actuator.

[0146] Fig. 5b illustrates an embodiment where the ring-formed actuator 40 applies a force to the lower edge 18 and a portion of the lower surface 14 adjacent to the lower edge of the transparent membrane. Also, in Fig. 5b there is only one transparent membrane abutting one side of the non-fluid lens body 30, while the other side of the non-fluid lens body 30 is abutting a transparent back window 90.

[0147] Fig. 6 illustrates a compact optical device 110, the optical device may be an imaging camera system, a projector, or another optical device, wherein the optical tuneable lens assembly 1 may be implemented. The compact imaging camara system 110 is comprising optical components 110, an image sensor 112, a photo capturing function 114, an image processor 120 and the optical axis 150. There may be different optical components 110 within such an optical device, like a lens stack 115, the optical tuneable lens assembly 1, an optical image stabilization lens 117, a cover glass 116, and / or an IR-filter 119. When the photo capturing function 114 is activated, which may be done by a user pushing a button, or it may be done automatically for instance by a timer preset to activate the photo capturing function, then the image processor may capture an image. The optical components 110 and the optical tuneable lens assembly 1 may be adjusted to optimize the image for instance by adjusting the focus of the image.

[0148] The lens assembly 1 may be attached to lens holder 107 in the optical device by glue, either directly to the ring-formed actuator 40 or via a custom designed mechanical support part (not shown). The glue needs to be soft and flexible to allow the ring-formed actuator 40 to contract.

[0149] Power supply and other electronic and / or mechanical device such as driving circuitry, support and housing for the optical elements needed for utilizing the invention is not described in detail as they are considered to the obvious to a person skilled in the art, depending on the chosen embodiment and the situation in which it is to be used.

[0150] Fig. 7-14 illustrates a number of different embodiments of the invention. 84881PC01

[0151] 22

[0152] Fig. 7a and 7b illustrates a transparent membrane 10 comprising a circular groove 60, which locally weakens the membrane. When the ring-formed actuator 40 applies a radial force to the transparent membrane 10, the transparent membrane 10 deforms and the circular grove causes the transparent membrane to bend at the circular grove to obtain a better spherical quality of the optical lens assembly at the aperture area. Fig. 7b is a close up of the groove section in fig. 7a. The thickness of the circular groove may be half the thickness t of the membrane. The membrane thickness t may be from 30 um to 1000 um. The membrane diameter may be from 3 mm to 30 mm. The circular groove 60 may be 500-2000 pm wide.

[0153] Fig. 8 illustrates a transparent membrane 10 attached to an intermediate part 50 with glue 62, or alternatively by adhesive tape, anodic bonding, or laser welding. The intermediate part is also attached to the ring-formed actuator 40. The intermediate part in this case is circular following the ring-formed actuator all the way round in a circle. The intermediate part may be made of bendable metal to allow the membrane to form a lens shape. The glue 62 attaches the intermediate part to both the ring-formed actuator and the transparent membrane, ensuring that the force is transferred radially into the transparent membrane, which may be made of glass, without causing shear deformation within the glue.

[0154] Fig. 9 illustrates a transparent membrane 10 attached to a plurality of intermediate parts 50, where each intermediate part also is attached to the ring- formed actuator 40. When the ring-formed actuator is activated the intermediate parts transfer force to the transparent membrane deforming the transparent membrane to a lens shape.

[0155] Fig. 10 is showing a cross-section of an embodiment with an intermediate part 50, which may be deep drawn sheet metal, transferring force from the ring-formed actuator 40, when the ring-formed actuator 40 is activated, to the boundary surface 20 of the transparent membrane 10. The intermediate part 50 may be attached with glue 62, adhesive tape, anodic bonding, or laser welding. The optical axis 150 illustrates the centre of the transparent membrane. The intermediate part may be bend in different forms, even so that the circumferential radius of the transparent membrane is larger than the inner actuator radius, but still the intermediate part 50 is formed such that the force is transferred to the 84881PC01

[0156] 23 boundary surface 20 of the transparent membrane 10. The optical axis 150 indicates the centre of the transparent membrane.

[0157] Fig. 11 shows a cross-section of an embodiment with two intermediate parts 50 attached together with glue 62. Also, one of the intermediate parts 50 is attached to the ring-formed actuator 40 with glue 62 and the other intermediate part is attached to the transparent membrane 10 with glue 62. When the ring-formed actuator 40 is activated, it applies a force to the intermediate parts and the force is transferred to be applied on the boundary surface 20 of the transparent membrane 10. Different kinds of glue may be used to attach the different parts together, the glue may be selected so that together with the form of the intermediate parts, will direct the transparent membrane 10 to deform in a controlled way to form a lens. The optical axis 150 indicates the centre of the transparent membrane. The idea of the embodiment shown in Fig 11. is to compensate the diameter tolerances of the transparent membrane and the ring- formed actuator. Intermediate parts 50 with drafted walls can be used to remove gap variation.

[0158] Fig. 12 shows a cross-section of an embodiment where the transparent membrane 10 is attached directly to the ring-formed actuator 40. The ring-formed actuator 40 comprises an inner surface 43 which is not perpendicular to the upper surface 47 and / or the lower surface 49 of the ring-formed actuator 40. When the ring- formed actuator 40 is activated the tilted inner surface 43 engages the boundary surface 20 or the lower edge 18 of the transparent membrane 10, the tilt of the inner surface 43 makes the transparent membrane 10 deform in a controlled way to form a lens. The optical axis 150 indicates the centre of the transparent membrane.

[0159] Fig. 13 shows a cross-section of an embodiment where an intermediate part 50 is connecting the ring-formed actuator 40 and the transparent membrane 10. The intermediate part 50 may be connected to the ring-formed actuator 40 and the transparent membrane 10 with glue 62 or alternatively with adhesive tape, anodic bonding, or laser welding. The intermediate part 50 comprises a groove 64, when the ring-formed actuator 40 is activated the groove 64 may bend and thereby transfer the force applied by the ring-formed actuator 40 to the transparent 84881PC01

[0160] 24 membrane 10 in a way that makes the transparent membrane 10 deform in a controlled way to form a lens. The optical axis 150 indicates the centre of the transparent membrane.

[0161] Fig. 14 shows a cross-section of an embodiment where the transparent membrane 10 is attached to the ring-formed actuator 40 with glue 62 or alternatively with adhesive tape, anodic bonding, or laser welding. The transparent membranes 10 are positioned so that the lower edge 18 and an adjacent portion of the lower surface 14 are attached to the upper surface 47 of the ring-formed actuator 40. When the ring-formed actuator is activated, it contracts, applying a radial force to the transparent membranes. The optical axis 150 indicates the centre of the transparent membrane. The idea with this embodiment is that with such glue geometry we can allow lost adhesion and still have radial force from the glue. Actually, lost adhesion at interface 14 is preferred, to achieve controlled deformation of the membrane.

[0162] Fig. 15 shows an embodiment, where a pressure ring 95 is mounted around the ring-formed actuator 40. The pressure ring may be made of metal with high CTE. Before assembly, the pressure ring is heated up to enlarge the diameter, illustrated by the arrow 96. When heated up the pressure ring is mounted around the ring-formed actuator 40, illustrated by the arrow 97. After mounting the pressure ring is cooling down and the diameter shrinks and therefore applies a pressure, a pre-load on the ring-formed actuator. When activated the ring-formed actuator 40 contracts and the pre-load from the pressure ring 95 combined with the radial force from the ring-formed actuator 40 results in a higher total radial force.

[0163] Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements 84881PC01

[0164] 25 indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.

Claims

84881PC0126CLAIMS1. An optical tuneable lens assembly for a compact optical device, the optical tuneable lens assembly (1) comprising: o at least one transparent membrane (10), the transparent membrane(s) being substantially circular and comprises a circumferential radius (15), an upper surface (12), a lower surface (14), an upper edge (16) at the boundary of the upper surface, a lower edge (18) at the boundary of the lower surface, and a boundary surface (20) between the upper edge and the lower edge, o a transparent deformable non-fluid lens-body (30), the deformable non-fluid lens body abuts with the transparent membrane(s) (10), the deformable non-fluid lens body conforms to the shape of the transparent membrane(s), and o a ring-formed actuator (40), the ring-formed actuator is, at least partly, ring-formed and comprises an inner actuator radius (42) and an outer actuator radius (44), wherein the ring-formed actuator (40) and the transparent membrane(s) (10) are co-axial, the circumferential radius (15) of the transparent membrane(s) (10) is less than the outer actuator radius (44), and the ring-formed actuator, when activated, is arranged to apply a variable radial force to the transparent membrane(s), causing deformation of the transparent membrane(s) and wherein the ring-formed actuator (40), when activated, applies a radial force, either directly or via one, or more, intermediate part(s) (50), to the boundary surface (20) of the transparent membrane (10).

2. The optical tuneable lens assembly of claim 1, wherein the circumferential radius (15) of the transparent membrane(s) (10) is less than or equal to the inner actuator radius (42), at least when the ring-formed actuator (40) is not activated.

3. The optical tuneable lens assembly according to any of the claims 1-2, wherein the ring-formed actuator (40), when activated, applies a radial force, either84881PC0127 directly or via one, or more, intermediate part(s) (50), to the upper edge (16) and / or the lower edge (18) and to a portion of the upper surface (12) and / or the lower surface (14) adjacent to the upper or lower edge (16, 18) of the transparent membrane (10).

4. The optical tuneable lens assembly according to any of the preceding claims, wherein the transparent membrane(s) (10) comprises a circular groove (60).

5. The optical tuneable lens assembly according to any of the preceding claims, wherein the optical lens assembly (1) further comprising one, or more, intermediate part(s) (50) connecting at least one of the transparent membranes (10) and the ring-formed actuator (40).

6. The optical tuneable lens assembly according to any of the preceding claims, wherein the optical lens assembly (1) is adapted to transfer force from the ring- formed actuator (40) to the transparent membrane(s) (10).

7. The optical tuneable lens assembly according to any of the preceding claims, wherein the ring-formed actuator (40) is made of a material comprising a piezoelectric material.

8. The optical tuneable lens assembly according to any of the preceding claims, wherein the ring-formed actuator (40) is made of a material comprising shape memory alloys, electroactive polymers, magnetostrictive materials and / or hydrogels.

9. The optical tuneable lens assembly according to any of the claims 1-8, wherein the ring-formed actuator (40) and the transparent membrane (10) are connected by glue (62), adhesive tape, anodic bonding, or laser welding.

10. The optical tuneable lens assembly according to any of the claims 1-8, wherein the ring-formed actuator (40), one, or more, intermediate part(s) (50), and the transparent membrane (10) are connected by glue (62), adhesive tape, anodic bonding, or laser welding.84881PC012811. The optical tuneable lens assembly according to any of the claims 1-10, wherein at least one intermediate part(s) (50) comprises a groove (64).

12. The optical tuneable lens assembly according to any of the preceding claims, wherein the inner surface (43) of the ring-formed actuator (40) is not perpendicular to the upper surface (47) and / or the lower surface (49) of the ring- formed actuator (40).

13. The optical tuneable lens assembly according to any of the claims 1-8, wherein the optical lens assembly (1) further comprising a pressure ring (95) mounted around the ring-formed actuator, wherein the pressure ring (95) is arranged to apply a pre-load on the ring-formed actuator (40).

14. A compact optical device comprising an optical tuneable lens assembly according to any of the claims 1-13.

15. A method of causing deformation of at least one transparent membrane (10) within an optical tuneable lens assembly (1) for a a compact optical device, the optical tuneable lens assembly (1) is comprising: o at least one transparent membrane (10), the transparent membrane(s) being substantially circular and comprises a circumferential radius (15), an upper surface (12), a lower surface (14), an upper edge (16) at the boundary of the upper surface, a lower edge (18) at the boundary of the lower surface, and a boundary surface (20) between the upper edge and the lower edge, o a transparent deformable non-fluid lens-body (30), the deformable non-fluid lens body abuts with the transparent membrane(s) (10), the deformable lens body conforms to the shape of the transparent membrane(s), and o a ring-formed actuator (40), the ring-formed actuator is, at least partly, ring-formed and comprises an inner actuator radius (42) and an outer actuator radius (44), wherein the ring-formed actuator (40) and the transparent membrane(s)(10) are co-axial,84881PC0129 the circumferential radius (15) of the transparent membrane is less than the outer actuator radius (44), and the ring-formed actuator (40), when activated, is applying a variable radial force to the transparent membrane(s) (10), causing deformation of the transparent membrane(s).

16. The optical tuneable lens assembly of claim 1, wherein a first flexural rigidity of the one or more intermediate part(s) or of at least part of the transparent membrane(s) outside an aperture in a direction parallel to an optical axis is smaller than a second flexural rigidity of the one or more intermediate part(s) or of at least part of the transparent membrane(s) outside the aperture in a direction perpendicular to the optical axis.

17. The optical tuneable lens assembly of claim 16, comprising the groove (64) on a top or bottom surface of said at least one intermediate part(s) (50), thereby the first flexural rigidity of the one or more intermediate part(s) outside the aperture in the direction parallel to the optical axis is smaller than the second flexural rigidity of the one or more intermediate part(s) in a direction perpendicular to the optical axis.

18. The optical tuneable lens assembly of claim 16, comprising the groove (64) on a top or bottom surface of said at least one intermediate part(s) (50), thereby the first flexural rigidity of the one or more intermediate part(s) outside the aperture in the direction parallel to the optical axis is smaller than the second flexural rigidity of the one or more intermediate part(s) in a direction perpendicular to the optical axis.

19. The optical tuneable lens assembly of claim 16, wherein said at least one intermediate part(s) is flat and connected to the lower or to the upper surface of the at least part of the transparent membrane(s) outside the aperture, thereby the first flexural rigidity of the one or more intermediate part(s) outside the aperture in the direction parallel to the optical axis is smaller than the second flexural rigidity of the one or more intermediate part(s) in a direction perpendicular to the optical axis.

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