Liquid lens having a fixed lens shaping element and a movable transparent window

The invention relates to a liquid lens (1) with an adjustable optical power comprising at least the following components:

CROSS-REFERENCE TO RELATED APPLICATIONS

This is the U.S. National Stage of International Patent Application No. PCT/EP2020/072933 filed on Aug. 14, 2020, 2021, which claims priority to European Patent application Ser. No. 19/219,052.8 filed on Dec. 20, 2019, and European Patent Application No. 20183997.4 filed on Jul. 3, 2020.

The invention relates to a liquid lens, an optical system and a method for controlling the lens or the system.

In the art membrane-based liquid lenses are known. The lenses operate on a mechanical force applied to an incompressible liquid in a lens volume, wherein in response to the applied force a membrane covering the lens volume adjusts its curvature and thus the optical power of the lens.

For this purpose, the liquid lens has a first membrane and opposite the first membrane a rigid transparent cover element, wherein the liquid is arranged between the membrane and the cover element.

The lens further comprises a wall portion enclosing the liquid circumferentially. The first membrane may be connected to the wall portion.

The actuation force is provided to the liquid lens by means of a movable lens shaping element. The lens shaping element is outside of the lens volume arranged on the first membrane and comprises an aperture that defines an adjustable lens area of the first membrane within which the first membrane can adjust its curvature along the optical axis upon actuation. Around the aperture of the lens shaping element there is a free membrane portion of the first membrane allowing the membrane to bend and provide the necessary elasticity for actuation.

By moving the lens shaping element towards or away from the lens volume the curvature of the first membrane is adjusted.

This design has several disadvantages.

For example during assembly of the lens, an optical axis of the lens is defined by the lateral wall. The lens shaping element with its aperture therefore needs to be arranged perfectly centered on the optical axis in order to omit aberrations and beam displacements relative to the optical axis.

Moreover, when actuating the lens shaping element along the optical axis of the lens, residual lateral movement of the lens shaping element cannot be prevented. These lateral movements however lead to movement of the optical axis of the adjustable lens area of the membrane and also a potentially asymmetric membrane curvature with respect to the optical axis of the lens. This leads to undesired lateral image shifts when the optical power of the lens is adjusted.

Furthermore, the lens does not provide means for compensating or controlling a beam displacement.

Also, the first membrane has to provide a specific stiffness such that the desired optical properties of the lens can be achieved. For actuation however, it is more desirable to have a low stiffness which allows for low actuation forces and thus energy conserving control of the lens. This leads to a conflict of objectives in the lens design that cannot be solved without compromise.

In general the lenses known in the art require a certain predefined building space, which for many applications should be reduced.

An object of the present invention is to provide a lens that solves the problems of the lenses known in the art. The object is achieved by the liquid lens having the features of claim1.

Advantageous embodiments are described in the subclaims.

According to claim1the liquid lens has an adjustable optical power and comprises at least the following components:a lens volume with a first transparent liquid arranged between a first transparent, particularly elastically deformable, membrane and a second transparent, particularly elastically deformable, membrane opposite the first membrane,wherein the first membrane has a first side facing outwards the lens volume and a second side facing in the opposite direction toward the lens volume,wherein the second membrane has a first side facing toward the lens volume and a second side facing in the opposite direction outward the lens volume,a lens shaping element arranged on, particularly connected to, more particularly fixedly connected to the first membrane, the lens shaping element having a circumferential aperture defining a lens area of the first membrane having an adjustable curvature,a transparent, particularly rigid and/or massive window element connected to the second membrane, particularly wherein the window element is particularly fixedly connected to the second side of the second membrane, covering a window portion of the second membrane, wherein the window element is circumferentially surrounded by a free, particularly non-window covered portion of the second membrane, such that the window element can move relatively to the lens shaping element thereby bending the free portion of the second membrane and adjusting a liquid pressure in the lens volume, such that a curvature of the first membrane in the lens area and therefore the optical power of the lens is adjusted.

According to an embodiment of the invention, an optical path extends through the window element and the lens area of the first membrane along the optical axis.

The term “optical path” particularly defines the portion of the lens, particularly the portion of the lens volume through which light propagates for being affected by the lens, i.e. the optical path does particularly not include residual stray light that might propagate through the lens in a manner that is not contributing to the intended alteration of the wave front of the light propagating through the lens.

The clear aperture of the lens shaping element defines the lens area of the first membrane by means of the circumferential enclosure of said lens area. When a pressure in the lens volume is adjusted, the lens area of the first membrane may alter its curvature in response to the pressure in the lens volume by either adopting a convex shape, i.e. in an outward protruding fashion, or by adopting a concave shape, i.e. in an inward protruding fashion. The change of curvature of the lens area of the first membrane allows the lens to adjust its optical power in a well-defined manner. Depending on the embodiment, the first membrane may also alter its curvature at other portions outside the lens area, however, these portion are outside the optical path of the lens and do not contribute to the optical properties of the lens.

According to another embodiment of the invention, in response to a change of pressure in the lens volume, the curvature of the first membrane causing the lens to change its optical power takes place only in the lens area of the first membrane.

Such change in pressure may be evoked by a relative movement or tilt of the window element toward or away from the lens shaping element.

The window element may be a plate-like window with no holes having at least one planar surface that is connected to the second side of the second membrane.

According to another embodiment of the invention, the lens comprises a lens body, wherein the lens body comprises at least the lens shaping element, the first membrane, the second membrane as well as the lens volume.

According to another embodiment of the invention, the lens shaping element is a fixed component of the lens body. Therefore, adjustment of the optical power or prism of the lens may be facilitated by moving the window element relatively to the lens body.

In a first embodiment, adjustment of the optical power and/or prism of the lens can be facilitated by means of an actuation force, for example provided by an actuator, configured to move the window element towards or away from the lens shaping element and thus the lens body, particularly while the lens body and the lens shaping element remain at a fixed position. In a second embodiment, adjustment of the optical power and/or prism of the lens may be facilitated by means of an actuation force, for example provided by an actuator, configured to move the lens body and/or the lens shaping element towards or away from the window element, particularly while the window element remains at a fixed position. Both embodiments provide a relative movement of the window element with respect to the lens shaping element and/or the lens body.

In other words, particularly, the optical power and/or prism of the lens may be adjusted by applying an actuation force to the lens shaping element, the window element or the lens body. The actuation force results in a relative motion of the window element and the lens shaping element. Said motion results in a displacement of the liquid in the lens volume, whereby the curvature of the first membrane in the lens area and/or the tilt of the first membrane in the lens area with respect to the window element is altered.

According to another embodiment of the invention, the lens comprises a housing, wherein the lens shaping element is rigidly, i.e. non-movable connected to the housing, wherein the window element is not connected to the housing or movably connected to the housing.

According to another embodiment of the invention, upon actuation, the housing is moved relatively to the window element, either by actuating the window element with respect to the fixed housing and/or by actuating the housing with respect to the fixed window element. The window element may be fixed to a holding device of the lens.

Even if the window element exhibits residual lateral movement relative to the lens body or housing upon actuation, the optical quality of the lens remains unaffected as the optical axis and the shape of curvature in the lens area is unaltered.

Moreover, actuation is not moving the lens shaping element relative to the lens body or housing which provides greater robustness and freedom of choice regarding the first and the second membrane.

Furthermore, impact of assembly tolerances on the position of the optical axis is reduced, because the position of the optical axis is essentially defined by the positon of the aperture of the lens shaping element.

Positioning tolerances of the window element on the second membrane do not affect the optical quality of the lens.

According to one embodiment, the lens comprises a prism function for deflecting a light beam relative to the optical axis of the lens. The prism function can be addressed by tilting the window element relative to the aperture of the lens shaping element.

According to an embodiment of the invention, the window element is formed as a planar plate.

According to an embodiment of the invention, the window element has a first planar surface that is fixedly connected, i.e. attached to the second membrane and a second surface that is facing in the opposite direction of the first planar surface.

According to an embodiment of the invention, the second surface of the window element is planar. In this case the window may introduce a prism capability but no optical power to the lens.

According to another embodiment of the invention, the first or the second surface of the window element is curved. In this case, the window element provides some additional optical power to the lens. In particular, the window element is a rigid lens, having a predefined optical power.

According to an embodiment of the invention, a z-axis of a Cartesian or cylindrical coordinate system extends orthogonally through the aperture of the lens shaping element.

According to an embodiment of the invention, an x-axis and a y-axis of a Cartesian coordinate system extend parallel to the aperture of the lens shaping element.

According to an embodiment of the invention, an optical axis of the lens extends orthogonally through the center of the aperture of the lens shaping element.

Depending on the physical requirement of the lens the relative sizes of the aperture and the second opening can be chosen.

The size of second opening essentially defines a stroke or force necessary for actuation of the window element, more precisely the actuation force and stroke depends on the size of the window element and the free portion of the second membrane as well as the stiffness of the second membrane.

It is noted that the actuation element is also referred to as piston shaper in the context of the specification.

It is further noted that the lens shaping element is also referred to as lens shaper in the context of the specification.

It is noted that the lens area does not need to be circular, but can have various shapes, such as oval, rectangular or polygonal.

It is further noted that the term deflection unit particularly refers to the lens area of the first membrane and to the lens shaping element in the context of the specification.

It is further noted that the term “container” particularly refers to the wall portion (see further below for details on the wall portion) with or without the lens shaping element in the context of the specification.

The lens shaping element may be also referred to as lens shaper in the context of the current specification.

With the lens according to the invention, either the window element might be actively moved with respect to a fixedly arranged lens shaping element or the fixedly arranged lens body. Movement of the window element might be facilitated with an actuator in order to adjust the optical power or the prism of the lens.

Alternatively, the lens body comprising the lens shaping element as well as the first and second membrane might be actively moved with respect to a fixedly arranged window element. Movement of the lens body, or the lens shaping element might be facilitated with an actuator in order to adjust the optical power or the prism of the lens.

It is noted that a movement of the lens shaping element alone, e.g. with respect to the first and the second membrane is not possible according to the invention, as the relation of the lens shaping element fixed with respect to the first membrane and the second membrane, particularly with respect to the lens body. This allows for the provision of a more robust lens with improved actuation properties as compared to liquid lenses where the lens shaping element is moved separately and relative to the lens body, e.g. the first membrane and the second membrane, and where the window element is in a fixed relation with respect to the lens body.

It is further noted, the relative movement of the window element with respect to the lens shaping element might be alternatively or additionally defined, if the lens comprises a wall portion, which disclosed for some embodiments of the invention. The relative movement in embodiments that have the wall portion may be defined by the window element being movable relative to the wall portion, wherein the lens shaping element remains at a fixed location and orientation with respect to the wall portion. The wall portion can be considered as being part of the lens body.

In the art, the lens shaping element is always moving relative to the wall portion.

In some embodiments the lens has an extension along the optical axis between 100 μm and 2 mm.

In some embodiments, the lens shaping element has an extension along the optical axis between 25 μm and 200 μm, particularly 100 μm.

In some embodiments, the window element has an extension along the optical axis between 50 μm and 200 μm, particularly 150 μm.

According to another embodiment of the invention, the lens volume is enclosed particularly exclusively, by the first and the second membrane only, wherein the first and the second membrane are connected in a sealing fashion to each other such as to form the lens volume, particularly wherein the first membrane and the second membrane are connected circumferentially at a lateral portion of the lens volume, particularly wherein the lateral portion extends circumferentially around the lens area of the first membrane and circumferentially around the free portion of the second membrane.

This embodiment provides a cushion-like lens, with no wall portion or rigid elements that might provide additional stability to the lens volume. This embodiment is therefore particularly light-weight and less-complex to manufacture.

Particularly, the lens shaping element is arranged between the lens area of the first membrane and the lateral portion.

This embodiment might also include a housing for rigid attachment of the lens shaping element, such that a motion of the window element relative to the lens shaping element does not cause the lens shaping element to move as well, such that actuation is not taking place efficiently.

According to another embodiment of the invention, the first membrane and the second membrane are integrally formed in form of a membrane sleeve that is sealingly connected at the openings of the membrane sleeve, particularly at the circumferential portion of the lens.

This embodiment allows for an even more facile manufacturing and provides a shorter seam length which in turn results in a more stable and robust lens.

The term sleeve in the context of the current specification particularly refers to a cylindrical or morphologically equivalent or similar geometry of a cylinder, wherein a cylinder wall is formed by the membrane that integrally comprises the first membrane and the second membrane. In other words, the membrane sleeve is a tube shaped membrane.

At the openings of the sleeve, the membrane is sealed in comprises the liquid of the lens.

According to another embodiment of the invention, the lens volume forms or comprises a first volume comprising the first liquid.

This embodiment allows for various types of lenses. According to a first alternative, the lens comprises only one liquid, namely the first liquid and the lens volume is the first volume. According to a second alternative, the lens comprises a plurality, for example two liquids that are both comprised in the lens volume, wherein the first liquid is comprised in the first volume and the other liquids are comprised in other (sub)-volumes of the lens volume. That is the lens volume might comprise a plurality of sub-volumes, when the lens comprises more than one liquid, wherein the first volume may be considered as a sub-volume of the lens volume as well.

According to another embodiment of the invention, the lens comprises a second liquid in a second volume, wherein the second volume is arranged at least partially on and/or completely centered around the optical axis of the lens, particularly along the z-axis of the lens, wherein the first liquid and the second liquid as well as the first volume and the second volume are separated from each other by a separating membrane portion.

The embodiment allows for acceleration-induced optical aberration compensation that for example occurs due to gravity.

By appropriately choosing the physical properties of the first and the second liquid acceleration-induced optical aberration compensation can be achieved.

Acceleration-induced optical aberrations may also be introduced by any force that attacks the lens obliquely to the optical axis.

According to this embodiment, the first and the second volume are essentially stacked on each other along the optical axis of the lens and are extending circumferentially around the optical axis of the lens.

The separating membrane portion may be a third membrane or it may be a particularly integral portion of the second membrane that is arranged such that it separates the first from the second volume. The latter is for example possible in case the second volume is arranged between a portion of the second membrane and the window element, wherein the second volume is sealed between said portion of the second membrane and the window element.

The first and the second volume are separated by each other in a liquid tight fashion, such that the liquids in the first and the second volume cannot exchange. It is noted that the membrane portion is not a liquid interface of the first and the second liquid but is made from a different material than the liquids.

According to another embodiment of the invention, the second liquid is arranged and sealed between the window element and the second membrane. In particular, the second membrane is connected with its second side only at a circumferential portion of the window element with the window element, thereby enclosing the second liquid between an integral portion of the second membrane and the window element, particularly wherein said integral portion forms the separating membrane portion, particularly wherein the separating membrane portion is in contact with the second liquid with a second side that corresponds to the second side of the second membrane and with the first liquid with a first side that corresponds to the first side of the second membrane.

Advantageously, this embodiment requires no third membrane and is thus less complex and more robust.

Moreover, upon actuation the second volume remains essentially at the same size and the integral portion of the second membrane (i.e. the separating membrane portion) does not change size which allows for low actuation forces, particularly as only the free portion of the second membrane and the lens area of the first membrane have to be changed in shape by a pressure change in the lens volume.

Particularly, the circumferential portion of the window element has a larger size than the clear aperture of the lens, particularly the clear aperture of the lens shaping element. Advantageously, the acceleration-dependent aberration compensation happens over the entirety of the clear aperture of the lens. In case the lens has a circular aperture, the circumferential portion of the second membrane surrounding the window element has a larger diameter than the clear aperture of the lens shaping element. In an analogue manner, this can be applied for different shapes of the clear aperture of the lens, particularly the clear aperture of the lens shaping element.

According to another embodiment of the invention, the separating membrane portion is comprised, particularly formed, more particularly integrally formed by a third membrane, wherein the third membrane has a first side and a second side, wherein the second side of the third membrane faces in the opposite direction than the first side of the third membrane.

This embodiment allows for a more differentiated structure of the lens volume in terms of separating the first from the second volume. For example, the third membrane may be attached to components of the lens, such as a wall portion, the first and/or the second membrane.

According to another embodiment of the invention, the first liquid is arranged between the first membrane and the third membrane. According to this embodiment, the first and the third membrane completely or partially limit the first volume. The third membrane may be attached to the first membrane such that the first volume is delimited by the first and third membrane only. For the perspective of manufacturing such a lens, there are several methods of producing such membrane-only first volume in conjunction with the second volume that might be formed as well from membranes only, e.g. by the first and the second membrane.

It is noted that all membranes are not solely liquid interfaces of the first and the second liquid but are made of a different materials than the liquids.

According to another embodiment of the invention, the second liquid, and thus the second volume is arranged between the third membrane and the second membrane. This embodiment complements for example the previous embodiment, where the first volume is arranged between the first and the third membrane.

Particularly, the lens volume is comprised between the first and the second membrane, wherein the third membrane is ranged inside the lens volume.

According to another embodiment of the invention, the second volume is comprised by the lens volume.

This embodiment is a clarification of the terms used in the specification.

According to another embodiment of the invention, the second volume is enclosed, particularly completely formed and enclosed by the third membrane and the second membrane. This embodiment might be used in combination with other embodiments to form a cushion-like lens which lens volume is essentially formed by membranes only.

According to another embodiment of the invention, the third membrane is circumferentially connected with its second side to the first side of the second membrane, particularly wherein the second volume with the second liquid is formed between a portion, particularly the window portion of the second membrane and a portion of the third membrane.

According to this embodiment, for example the second membrane is attached with its second side over an entire side of the window element to the window element and with the first side the second membrane faces the second volume. The third membrane in turn faces the second volume with its second side and with its first side the third membrane might face the first volume. Particularly, at some rim portions of the second and the third membrane, the membranes might be attached and sealingly connected to each other so as to form the second volume.

According to another embodiment of the invention, the third membrane is connected to the lens shaping element.

According to another embodiment of the invention, the first membrane is connected to the first side of the lens shaping element and wherein the third membrane is connected to the second side of the lens shaping element, such that the first volume is enclosed in the aperture of the lens shaping element.

This embodiment provides lateral structural stability to the first volume and the physical properties of the lens may be defined more precisely. Moreover, according to this embodiment, upon actuation both, the first and the third membrane (as well as the free portion of the second membrane) will be forced to change their curvature. This allows for additional optical power adjustment by the third membrane by exploiting changes in refractive index between the first and the second liquid. According to this embodiment, the curvature of the first and the third membrane will be either both convex or both concave. As both membranes are attached to the lens shaping element they exhibit the same clear aperture such that the clear aperture is perfectly overlapping and identical for both membranes, which allows for a high optical performance lens. The curvature of the first and the third membrane are moreover independent of a potential tilt of the window element and thus completely defined by the pressure change in the lens upon actuation and the clear aperture of the lens shaping element, which, to contributes to a high-quality lens. The actuation forces required for this embodiment are comparably higher, as according to this embodiment, three membranes have to be bent upon actuation (as compared to embodiments, where only two membranes, namely the first and the second membrane are bent).

According to another embodiment of the invention, the third membrane is circumferentially connected to the first membrane and the first volume is formed between the first membrane and the third membrane, particularly wherein the first side of the third membrane is in contact with the first liquid and the second side of the third membrane is in contact with the second liquid. Particularly, the first volume is formed by the first and the third membrane only.

According to this embodiment, actuation forces may be comparably low, as the third membrane is exposed only to very minor bending forces.

According to another embodiment of the invention, the third membrane is connected with its first side to the second side of the first membrane.

According to another embodiment of the invention, the first liquid has a first refractive index n1and the second liquid has a second refractive index n2, wherein the first and the second refractive index are different from each other.

This allows for various problems of the lens to be overcome.

One problem that may be solved with the two liquids having different refractive indices is temperature compensation of the optical power of the liquid lens.

According to another embodiment of the invention, the first liquid and the second liquid have different refractive indices, and the materials of the first liquid and the second liquid, the curvature of the membranes delimiting the first volume and the second volume are selected such that temperature-induced changes of the volume of the first and second liquid and temperature-induced changes of the refractive indices of the first and the second liquid are compensated, whereby the optical power of the lens remains essentially constant over a range of different temperatures.

For example, the first liquid may have a refractive index of 1.3±0.05 and the second liquid may have a refractive index of 1.45±0.05. Both, the first and the second liquid expand, when the temperature increases. Thereby, the curvatures of the membranes delimiting the first volume and the second volume respectively change in a similar fashion, when the temperature increases. Advantageously, a lens comprising two liquids with different refractive indices enables inherent temperature compensation, which results in a particularly reliable performance of the lens.

With differing refractive indices of the two liquids also acceleration-induced aberrations may be compensated or eliminated.

According to another embodiment of the invention, the first liquid has a first mass density and a first refractive index and the second liquid has second mass density and a second refractive index, wherein the first and the second refractive indices of the first and the second liquid as well as the first and the second mass densities are selected such that an acceleration-induced aberration of the lens, such as gravity-induced aberration, such as gravity coma or posture effects induced by orienting the lens along different directions with respect to gravity is compensated.

The person skilled in the art will understand that certain combinations of mass densities and refractive indices will behave just so that the optical path is adjusted by the two liquids such that said aberrations are compensated.

According to another embodiment of the invention, the second mass density of the second liquid is higher than the first mass density of the first liquid, and the second refractive index is smaller than the first refractive index of the first liquid or vice versa.

Such a combination of the physical properties of the liquids allows for acceleration-induced aberration compensation or at least reduction.

According to another embodiment of the invention, the first membrane has a first stiffness and the separating membrane portion, particularly the third membrane has a separating membrane portion stiffness, particularly wherein a thickness of the first membrane and the thickness of the separating membrane portion are essentially equal, wherein the first stiffness and the separating membrane portion stiffness are selected according to the relation

ksk1=n1-n2n1-1⁢ρ2-ρ1ρ1
wherein ρ1is the first mass density of the first liquid, ρ2is the second mass density of the second liquid, n1is the first refractive index of the first liquid and n2is the second refractive index of the second liquid.

According to another embodiment of the invention, the first membrane has a first thickness t1and the separating membrane portion has separating membrane portion thickness ts, particularly wherein a stiffness of the first membrane and a stiffness of the separating membrane portion are essentially equal, wherein the first thickness and the separating membrane thickness are selected according to the relation:

tst1=n1-1n1-n2⁢ρ2-ρ1ρ1,
wherein ρ1is the first mass density of the first liquid, ρ2is the second mass density of the second liquid, n1is the first refractive index of the first liquid and n2is the second refractive index of the second liquid.

According to another embodiment of the invention, the stiffness of the first membrane and/or the stiffness of the separating membrane portion is/are in the range of 0.1 MPa and 10 MPa.

In this range one the one hand actuation forces are manageable and on the other hand membranes are rendered robust enough to last for a long time.

According to another embodiment of the invention, the membrane thickness of the first membrane and/or the thickness of the separating membrane portion is/are in the range of 2 μm and 200 μm.

This thickness range allows for a robust membrane and moderate actuation forces.

According to another embodiment of the invention, the first and/or the second refractive index is/are in the range of 1.26 and 1.6. Particularly, the first refractive index of the first liquid is in the range 1.3±0.05 and the second refractive index of the second liquid is in the range of 1.45±0.05.

According to another embodiment of the invention, the first and/or the second mass density is/are in the range of 1 kg*m−3and 1.8 kg*m−3.

According to another embodiment of the invention, the lens comprises an actuation element connected to the window element. Particularly the actuation element serves as a connection device for an actuation device. As such the actuation element may be integrally formed, glued to, or welded with the window element.

In some embodiments, the actuation element has an extension along the optical axis between 50 μm and 200 μm, particularly 100 μm.

The actuation element may have a clear aperture centered around the optical axis or may be asymmetrically formed with respect to the optical axis.

The actuation element may be formed from a different material than the window element or from the same material. The window element can be formed from glass or a transparent polymer.

According to another embodiment of the invention, the actuation element is connected, particularly in a rigid fashion to the window element at a circumferential portion of the window element, such that the window element can be tilted by the actuation element around at least one axis with respect to the aperture of the lens shaping element and/or translationally moved towards or away from the aperture of the lens shaping element.

Tilting of the window element may be achieved by providing an asymmetric force to the actuation element with respect to the optical axis of the lens. Tilting of the window element may be used in order to provide a prism function to the lens

Translation in turn may be achieved by providing a symmetric force to the actuation element. Translation of the window element along the optical axis may be used to adjust the optical power of the lens, as at least the curvature of the lens area of the first membrane is adjusted by such a translational motion of the window element.

According to another embodiment of the invention, the actuation element has a clear aperture enclosed by the actuation element such that light can pass through the clear aperture of the actuation element and through the window element. The clear aperture may be centered around the optical axis of the lens. Particularly, the clear aperture of the actuation element may be larger than the clear aperture of the lens shaping element.

According to another embodiment of the invention, the actuation element comprises a rigid portion and at least one damping element, wherein the damping element may be arranged at least partially between the window element and the rigid portion of actuation element, and/or wherein the damping element may be arranged at an outer portion of the rigid portion of the actuation element, wherein the damping element is softer than the window element and the rigid portion of the actuation element, pa wherein the damping element is connected to the window element, particularly at the circumferential portion of the window element.

The damping element for example allows for larger strokes for actuating the window element, which in turn allows for the use of a different kind of actuators that might be more cost-effective, due to reduced actuation-accuracy requirements.

Also the damping elements absorb external shocks.

According to another embodiment of the invention, the actuation element comprises a spring element such that an actuation force provided to the window element is transmitted via the spring element, particularly wherein the spring element is formed as an elastic metal sheet that extends essentially parallel to the window element.

The spring element particularly allows for larger strokes of the actuator, which leads to an increased actuation accuracy and tolerance and the manufacturing of the lens with less expensive actuators.

Moreover, the spring element may serve as an absorber for mechanical shocks.

According to another embodiment of the invention, the circumferential portion of the window element at which the actuation element is connected has a larger diameter, particularly a larger clear aperture than the aperture of the lens shaping element, particularly larger than the first opening of the wall portion (see further below), such that an optical path through the lens remains unobstructed by the actuation element, particularly wherein the diameter, particularly the clear aperture of the circumferential portion of the window element is so large that the optical path remains unobstructed by the actuation element, even if the actuation element is tilted with respect to the aperture of the lens shaping element.

When the apertures are circular the term diameter relates directly to the diameter of the circular aperture. If another shape of aperture is chosen for the lens, the aperture of the actuation element has to be so large that the actuation element does not obstruct the optical path through the clear aperture of the lens shaping element.

According to another embodiment of the invention, the lens shaping element is arranged fixed in space, while the window element is movably arrange din space, particularly wherein the lens shaping element is arranged fixedly at an external system or a housing or an optical system with respect to the movable window element, such that adjusting an optical power of the lens is facilitated by moving the window element relative to the lens shaping element that remains fixed in space, e.g. fixed relative to the external system, the housing or the optical system.

This embodiment essentially relates to a window element that is moved by an actuator.

Movement of the window element may comprise a tilting motion and/or a translational motion particularly parallel to or along the optical axis.

According to another embodiment of the invention, the lens body comprising the lens shaping element is configured to be actuated or moved, wherein the window element is fixedly arranged in space, while the lens body is arranged movably in space, wherein the window element may be rigidly connected to a housing of the lens, to an external system or to an optical system, such that adjusting an optical power or prism of the lens is facilitated by moving the lens body relative to the window element that remains fixed in space, e.g. fixed relative to the external system, the housing or the optical system.

According to another embodiment of the invention, the window element is configured to be actuated or moved, wherein the lens body, comprising the lens shaping element is fixedly arranged in space, while the window element is arranged movably in space, wherein the lens body and thus the lens shaping element may be rigidly connected to a housing of the lens, to an external system or to an optical system, such that adjusting an optical power of the lens is facilitated by moving the window element relative to the lens body that remains fixed in space, e.g. fixed relative to the external system, the housing or the optical system.

According to another embodiment of the invention, the lens comprises a lateral wall portion, particularly a rigid lateral wall portion extending circumferentially around the lens volume, particularly enclosing the lens volume at least laterally and/or radially, wherein the wall portion has a first side with a first opening facing toward the first membrane and a second side with a second opening opposite the first opening, wherein the second opening extends circumferentially around the free portion of the second membrane, particularly wherein the second side of the wall portion is connected, particularly bonded, plasma-bonded or glued, to the first side of the second membrane, thereby particularly sealing the first liquid in the lens volume, particularly wherein the lens shaping element is arranged at a fixed orientation and position with respect to the wall portion.

The wall portion is comprised by the lens body and has a fixed orientation relative to the lens body.

Particularly, an extension of the wall portion along the optical axis is in the range of 100 μm to 1.000 μm, particularly 350 μm.

The wall portion is particularly a structural stabilizing component of the lens.

The wall portion might be made of a non-transparent material such that stray light is reduced.

Thee wall portion might have a cylindrical or toroidal shape.

Depending on the lens design, the wall portion might also have polygonal or oval cross-section extending orthogonally to the optical axis.

The first and or second opening of the wall portion might differ from the clear aperture of the lens shaping element.

Particularly, the first and the second opening of the wall portion are centered on the optical axis of the lens, particularly the openings of the wall portion enclose the optical axis of the lens.

Particularly, the first and the second opening of the wall portion are concentrically arranged with respect to each other, centered on the optical axis of the lens.

According to another embodiment of the invention, the wall portion is connected with, particularly attached to the first side to the second side of the first membrane.

Connection may be facilitated by means of glue, bonding or welding techniques.

According to another embodiment of the invention, the lens shaping element is arranged inside the lens volume and circumferentially connected with the first side of the lens shaping element to the second side of the first membrane, thereby forming the lens area of the first membrane. In particular, the lens shaping element delimits the lens volume partially. For example, the lens shaping element is in direct contact with the liquid in the lens volume.

According to another embodiment of the invention, the aperture of the lens shaping element, particularly the lens area is smaller than the second opening of the wall portion.

According to another embodiment of the invention, the aperture of the lens shaping element, particularly the lens area is larger or of the same size than the second opening of the wall portion.

According to another embodiment of the invention, the third membrane is circumferentially connected to a wall portion and/or to the lens shaping element. The features of the wall portion are particularly defined in more detail in another embodiment.

According to another embodiment of the invention, the third membrane is connected with its first side to the first side of the wall portion.

According to another embodiment of the invention, the lens shaping element is connected, particularly with a second side of the lens shaping element to the first side of the wall portion.

This embodiment particularly comprises embodiments in which the lens shaping element is arranged inside the lens volume.

According to another embodiment of the invention, the wall portion is integrally formed with the lens shaping element, particularly wherein the first opening of the wall portion is formed by the clear aperture of the lens shaping element. In the same sense, the lens shaping element may be considered to be integrally formed with the wall portion, particularly wherein the aperture of the lens shaping element is formed by the first opening of the lateral wall portion.

This embodiment allows for a less complex lens manufacturing process, as fewer parts are required for lens assembly.

According to another embodiment of the invention, the lens shaping element is arranged on and connected to the first side of the first membrane, particularly wherein the lens shaping element is connected with its second side to the first side of the first membrane.

According to another embodiment of the invention, the first side of the wall portion is connected to the second side of the first membrane in a sealing fashion.

According to another embodiment of the invention, the aperture of the lens shaping element, particularly the lens area is smaller than the first opening of the wall portion. This embodiment allows for the lens to have a larger aperture on the side of the window element than on the side of the lens shaping element. Stray light may be reduced according to this embodiment.

According to another embodiment of the invention, the lens shaping element consists of a wall structure enclosing the aperture circumferentially, particularly wherein the wall structure has a toroidal shape, particularly wherein the wall structure forms a rectangular, square, oval, ellipsoid or circular aperture of the lens shaping element. According to this embodiment, the lens shaping element may be formed as a ring or a morphologically identical to a ring.

Particularly, the lens shaping element has an outer diameter and an inner diameter, wherein the inner diameter corresponds to the clear aperture of the lens shaping element.

The lens shaping element in this form is easy to manufacture, widely available and intrinsically stable.

According to another embodiment of the invention, the lens shaping element is a ring-shaped element, particularly wherein the ring-shaped element has a rectangular, square, oval, elliptical or circular aperture of the lens shaping element.

According to another embodiment of the invention, the lens shaping element is overlappingly arranged with the lateral wall portion, such that a rigid connection is formed between the wall portion and the lens shaping element or wherein the lens shaping element is arranged non-overlappingly with the lateral wall portion, particularly wherein the lens shaping element is connected to a part of the lens or an external member that may be arranged fixedly with respect to the window element.

According to another embodiment of the invention, the wall portion comprises a circumferential recess around the first opening, wherein the lens shaping element is arranged in the circumferential recess and connected to the wall portion, particularly wherein the lens shaping element is formed corresponding to a recess shape, such that a well-defined position with respect to the wall portion is adopted in the assembled state. This embodiment allows for a precise assembly of the lens during manufacturing.

According to another embodiment of the invention, the window element, particularly an area covered by the window element, more particularly the window portion of the second membrane, is larger than the aperture of the lens shaping element, particularly wherein the window element is larger than the aperture of the lens shaping element even if the window element is tilted with respect to the aperture of the lens shaping element.

This embodiment essentially renders the window element invisible at any orientation with respect to the clear aperture of the lens shaping element, as no edges of the window element can interfere with the incident light propagating through the lens.

According to another embodiment of the invention, the second opening of the wall portion is larger, smaller or equal in size than the first opening of the wall portion.

According to another embodiment of the invention, the first and the second opening of the wall portion extend parallel to each other, particularly in an x-y plane, particularly orthogonally to a z-axis of the lens.

According to another embodiment of the invention, the wall portion comprises a step-like contour, e.g. a discontinuity in the contour, between the first and the second opening at which the diameter of the wall portion changes, particularly wherein the step is formed by a protrusion of the wall portion that extends along a plane parallel to the first and the second opening of the wall portion, particularly wherein the protrusion is formed by the lens shaping element.

This embodiment allows for a larger degree of stray light reduction.

According to another embodiment of the invention, the first membrane has a first stiffness k1and/or a first thickness and the second membrane has a second stiffness k2and/or a second thickness, wherein the second stiffness k2and/or the second thickness is smaller than the first stiffness k1and/or the first thickness.

This embodiment allows for comparably low actuation forces, as the bending of the free portion of the second membrane may be facilitated with little force, while the first membrane is rendered comparably robust due to its increased stiffness/thickness as compared to the second membrane.

According to another embodiment of the invention, the first membrane has a first thickness t1and the second membrane has a second thickness t2, wherein the second thickness t2is smaller than the first thickness t1.

This embodiment allows for comparably low actuation forces, as the bending of the free portion of the second membrane may be facilitated with little force, while the first membrane is rendered comparably robust due to its increased stiffness/thickness as compared to the second membrane.

According to another embodiment of the invention, the lens shaping element forms the lateral wall portion for the lens volume, the first volume and/or the second volume.

According to another embodiment of the invention, the lens comprises the components ofthe actuation element that is rigidly connected, particularly attached to the window element, wherein said actuation element extends laterally from the window element with a lateral mover element beyond the wall portion and comprises a coil portion that is that is arranged laterally beyond the wall portion on the lateral mover element, wherein said coil portion comprises one or more coils, wherein said one or more coils are arranged such on the coil portion that the one or more coils extend with a coil axis of the at least one coil along the wall portion, particularly towards a lateral plane of the lens shaping element, particularly essentially parallel to the z-axis of the lens,for each coil a corresponding magnetic portion, wherein said magnetic portion is arranged at the wall portion of the lens, such that a Lorentz force can be induced in the at least one coil that provides a tilting force to the actuation element and thereby to the window portion, such that a refractive power of the lens can be adjusted.

This embodiment of the lens allows for Lorentz force-induced actuation of the lens.

The coils particularly extend circumferentially around the lens volume with their respective coil axes essentially parallel to the optical axis of the lens.

Upon actuation of the lens, it might be that at least some coils will adopt a slightly tilted state with respect the optical axis. This tilt movement and also the lateral movement of the coils along the optical axis might be limited by a hard stop.

Particularly, the magnetic portion comprises at least one magnet, particularly one permanent magnet or a plurality of magnets that are correspondingly arranged to the coils at the wall portion.

This embodiment allows for robust actuation of the lens even in the presence of other, external magnetic fields.

According to another embodiment of the invention, the lens comprises a hard stop portion rigidly connected to the lens with respect to the shaping element, wherein the hard stop portion extends laterally over the coil portion at a distance, such that a movement along at least one direction of the z-axis of the coil portion particularly the mover element is mechanically limited by said distance between the coil portion and the hard stop element.

This embodiment provides a mechanical shock protection as well as an overdrive-protection for the lens, in case a control signal for the coils would cause the lens to be adjusted beyond an adjustment range.

According to another embodiment of the invention, the lens comprises a mechanical stop device that is arranged such at the lens that movement of the window element with regard to a fixedly arranged lens body, particularly the fixedly arranged lens shaping element along the optical axis and/or a movement orthogonally to the optical axis is limited by the mechanical stop device, particularly along a back and forth direction, or wherein the stop device is arranged such at the lens that a movement of the lens body, particularly the lens shaping element with respect to the fixedly arranged window element along the optical axis and/or a movement orthogonally to the optical axis is limited by the mechanical stop device, particularly along a back and forth direction.

For example, the stop device limits the relative motion of the window element and the lens shaping element along the optical axis. In particular, the stop device does not limit a tilt of the window element with respect to the lens shaping element. This embodiment allows for mechanical shock protection and overdrive states of the lens, particularly when the lens is built-in optical systems.

According to another aspect of the invention, the problem is solved by a lens barrel comprising an optical assembly, with at least one solid lens having a fixed focal length, and wherein the lens barrel further comprises the lens according to any of the preceding embodiments.

The lens barrel particularly comprises a rigid barrel wall that circumferentially encloses the optical assembly as well as the lens according to the invention, wherein the optical assembly and the lens are fixedly arranged in the lens barrel, such that the lens barrel may be used in an optical system as a pre-manufactured electro-optical component.

According to another embodiment of the lens barrel, the liquid lens is arranged at a first and/or a second opening of the lens barrel as the first optical component (apart from protective optical elements such as transparent windows), particularly wherein the optical assembly is arranged completely optically behind or in front of the liquid lens in the lens barrel.

The term optical component therefore particularly relates to an optical element that is configured to change the wavefront of incident light.

According to one embodiment, the lens may be altered from a negative to a positive lens by actuation or the lens may be changed from a positive lens to a negative lens by actuation.

For example, in a non-actuated state of the lens, the first membrane is concavely curved, and upon actuation the first membrane becomes convexly curved. Alternatively, the in a non-actuated state of the lens, the first membrane is convexly curved, and upon actuation the first membrane becomes concavely curved. Advantageously, switching between a negative and a positive lens enables a particularly large tuning range and a versatile application of the tunable lens.

According to a second aspect to the invention, the problem is solved by an optical system, comprising the lens according to any of the previous embodiments, wherein the system comprises at least one lens, i.e. a conventional rigid glass or polymer lens having a fixed focal length and an optical sensor, particularly an image sensor, arranged along an optical axis of the system, wherein the liquid lens and the at least one solid lens are fixedly arranged in a lens barrel, particularly the lens barrel, along the optical axis of the system, particularly wherein the first membrane of the liquid lens is closer to the sensor than the second membrane of the liquid lens.

According to another aspect of the invention, the problem is also solved by a reluctance motor assembly for adjusting the optical power of the liquid lens according to the invention.

According to another embodiment of the invention, the reluctance motor assembly is comprised by the optical system.

According to another embodiment of the invention, the optical system is a wide-angle, a macro-, a tele-, or a zoom-system.

According to another embodiment of the invention, the optical system comprises a first optical assembly with at least one lens having a fixed focal lens, and a second optical assembly comprising at least one lens having a fixed focal length, wherein the first and the second optical assembly are connected to a rigid lens barrel, particularly the lens barrel, wherein the liquid lens is arranged between the first and the second optical assembly with respect to the optical path of the optical system.

According to another embodiment of the invention, the system comprises a first control circuit that is configured to provide an electronic signal to an actuation assembly of the liquid lens configured to tilt the window element of the lens in response to a movement of the optical system such that an image on the sensor is stabilized, particularly wherein the first control circuit is configured to control a position of the at least one lens having fixed focal length.

This embodiment allows for image stabilization for example in hand-held devices such as mobile phone comprising an image sensor, such as a camera.

According to another embodiment of the invention, the liquid lens is arranged in the system for focusing an image to the sensor.

According to another embodiment of the invention, the liquid lens is arranged in the system for stabilizing an image position on the sensor.

Image stabilization can be achieved by tilting the window element in response to a recorded motion of the system accordingly.

As actuation of the lens is comparably fast, image stabilization is achieved fast as well such that sharper images may be acquired with the optical system.

According to another aspect of the invention, the problem is solved by a method, particularly a computer-implemented method for controlling the optical properties such as the optical power as well as prism of a liquid lens or an optical system according to the invention, wherein the method comprises the steps of:in response to a first control signal provided by a computer or a processor unit causing an actuation assembly particularly comprising the actuation element connected to the window element to tilt the window element relative to the aperture of the lens shaping element such that a light beam is deflected with respect to an optical axis of the liquid lens, and/orin response to a second control signal provided by the computer or the processor unit causing the actuation assembly to move the window element translationally, particularly along the optical axis, with respect to the aperture of the lens shaping element such that an optical power of the liquid lens is adjusted.

According to another aspect of the invention, the problem is solved by a method, particularly a computer-implemented method for controlling the optical properties such as the optical power as well as prism of a liquid lens or an optical system according to the invention, wherein the method comprises the steps of:in response to a first or third control signal provided by a computer or a processor unit causing an actuation assembly connected to the lens body and/or the lens shaping element to tilt the lens body and/or the lens shaping element relative to window element, and/orin response to a second or fourth control signal provided by the computer or the processor unit causing the lens assembly to move the lens body and/or the lens shaping element translationally, particularly along the optical axis, with respect to the window element such that an optical power of the liquid lens is adjusted.

The Figures are appended to the claims and are accompanied by text explaining individual features of the shown embodiments and aspects of the present invention. Each individual feature shown in the Figures and/or mentioned in said text of the Figures may be incorporated (also in an isolated fashion) into a claim relating to the device according to the present invention.

DETAILED DESCRIPTION

InFIG.1Aa schematic cross-section through a lens1according to the invention is shown. The lens1has on optical axis OA that extends along a z-axis of a Cartesian coordinate system (indicated as arrows with x, y and z). Laterally, the lens1extends along the x and y-axis of said coordinate system. While the x axis can point along the picture plane, the y axis might point outward the picture plane or vice versa.

The lens1comprises a lens volume VL that is enclosed by the first membrane21, the second membrane22and a rigid lateral wall portion4as well as the lens shaping element3.

The lateral wall portion4and the lens shaping element3are formed integrally with each other in the embodiment ofFIG.1A.

Nonetheless, for reasons of consistency with other embodiments of the lens1, the lens shaping element3and the wall portion4are treated as different members of the lens1. The wall portion4has a first side4-1(cf.FIG.4) facing toward the first membrane21and a second side4-2facing in the opposite direction. The wall portion4comprises a first opening4aon the first side4-1and a second opening4-2on the second side4-2. The lens shaping element3has a clear aperture3acomprising the optical axis OA of the lens1, such that a clear lens area21afor the first membrane21is formed, wherein in the lens area21aof the first membrane21is deformable and light can propagate through the lens1via the lens area21a.

The lens shaping element3is formed as a ring-shaped member with a clear aperture3athat encircles the lens area, wherein the wall portion4is formed as a ring-shaped member as well.

The wall portion4and the lens shaping element3extend circumferentially around the optical axis OA of the lens1.

The first membrane21is a transparent distensible, i.e. an elastically deformable membrane, and has a first side21-1that faces away from the lens volume VL and a second side21-2that faces towards the lens volume VL.

The first membrane21is sealingly and circumferentially attached with its second side21-2to a first side3-1of the lens shaping element3.

The opening4a,4bof the wall portion4is larger than the aperture3aof the lens shaping element3. The second membrane22is sealingly and circumferentially connected with a first side22-1of the membrane22to the second side4-2of the wall portion4and covers the second opening4bof the wall portion4.

The second membrane22is a transparent and distensible membrane.

The first side22-1of the second membrane22faces toward the lens volume VL and a second side22-2of the second membrane22faces away from the lens volume VL.

The first side22-1of the second membrane22and the second side21-1of the first membrane21are in direct contact with a first liquid L1of the lens1that is enclosed in the lens volume VL by the first and second membrane21,22and the wall portion4as well as the lens shaping element3.

A rigid, transparent window element5is connected to the second membrane22at the second side22-2of the second membrane22.

The window element5extends symmetrically around the optical axis OA over a window portion22aof the second membrane22. The window portion2aof the second membrane22is circumferentially enclosed by a free portion22bof the second membrane22that is not covered by the window element5, such that the window element can be moved along the z-axis and to some extend also laterally along the x- and/or y-axis. Any motion of the window element5will cause the free portion22aof the second membrane22to bend in order to allow the motion of the window element5.

Thus, the window element5is not directly connected (but only via the free portion22aof the second membrane22) to the wall portion4or the lens shaping element3and can therefore move relatively to the wall portion4as well as to the lens shaping element3.

An actuation element6is rigidly connected to the window element5at a connecting portion5band forms a clear aperture5aof the window element5. The clear aperture5acomprises the optical axis OA of the window element5.

The actuation element6extends laterally away from the window element5and allows an actuation force to be provided to the window element5.

FIG.1Ashows the lens1when no actuation force is applied to the actuation element6.

FIG.1Bshows the same lens as depicted inFIG.1A, but with an actuation force (indicated by the arrows A next to the actuation element6) applied to the actuation element6. On one side the actuation force pushes the window element5towards the clear aperture3aof the lens shaping element3and on the other side of the window element5(facing outward the lens volume VL), the window element5is pulled away from the aperture3aof the lens shaping element3.

As can be seen, the free membrane portion22bof the second membrane22bends and stretches accordingly.

In the situation shown inFIG.1Ba net movement of the window element5toward the clear aperture3aof the lens shaping element3is achieved, which eventually produces a bending force also on the first membrane21such that the first membrane21is pushed away at the lens area21afrom the aperture3aof the lens shaping element3forming a symmetric convex membrane surface Therefore, by moving the window element5, the refractive power of the lens1can be adjusted.

Despite the asymmetric tilted state of the window element5with respect to the wall portion4and the lens shaping element3, the bending of the lens area21aof the first membrane21occurs symmetrically around the optical axis OA of the lens1. Particularly, the clear aperture3aof the lens shaping element3defines the optical axis OA of the lens1independently of the actuation state of the window element5. This allows for greater manufacturing and assembly tolerances for the lens1. Also, with respect to the actuation of the window element5, greater tolerance is achieved by having the first and/or the second opening4a,4bof the wall portion4larger than the clear aperture3aof the lens shaping element3. Particularly, the window element5has a larger aperture5athan the clear aperture3aof the lens shaping element3, which allows for even greater manufacturing tolerance without affecting the optical quality of the lens1.

The advantage of window element5moving with respect to the lens shaping element3is that the deformation of the lens area21ais always symmetric with respect to the optical axis OA, independent of any asymmetric motion are lateral shift (e.g. along the x or y axis) of the window element5with respect to the lens shaping element3. This allows for a better optical performance of the lens1according to the invention, particularly any lateral offset of wave front propagating through the lens1due to a non-centered and/or non-symmetric surface shape of the lens area21ais prevented.

In configurations known in the art, where the lens shaping element is moved relative the wall portion (or the window element), any lateral shift or asymmetric motion of the lens shaping element causes a correspondingly asymmetric deformation of the first membrane.

To illustrate this, inFIG.10the same lens1is shown, but this time an actuation force is applied that pushes the window element5toward the aperture3aof the lens shaping element3on both sides to the same extent.

Due to the incompressible first liquid L1in the lens volume VL, the actuation force causes the lens area21ato bend outward of the aperture3aof the lens shaping element3. The shape of the lens area21ais symmetric to the optical axis OA as well.

Thus, by tilting the window element5accordingly, a wave front of light propagating through the lens1can be adjusted such as to compensate for slight offsets with regard to the optical axis of the lens1in a lens assembly or an optical system. In other words, an additional prism function can be integrated in the lens1by asymmetric actuation of the window element5.

With the lens1it is also possible to achieve negative refractive power, by pulling the window element5away from the aperture3aof the lens shaping element3, which causes the lens area21ato deform in a symmetric concave fashion. This is shown inFIG.1D.

The second membrane22might be softer, i.e. less stiff, than the first membrane21, which allows for lower actuation forces of the lens1.

Moreover, a geometric extension along the z-axis of the lens1is reduced by having the lens shaping element3fixed relative to the movable window element5.

InFIG.2a similar lens1as inFIG.1Ais shown in equilibrium state by means of a schematic cross-sectional view of the lens1. In contrast toFIG.1, inFIG.2the aperture3aof the lens shaping element3and the openings4aand4bof the wall portion4have the same size. Thus, the lens shaping element3and the wall portion are essentially formed as a cylinder.

It is noted that the aperture5aon the window element5of actuation element6is smaller than the lens area21a.

This allows for an additional aperture function of the lens1provided by the aperture5athat reduces stray light and ghosting effects of the lens1.

InFIG.3an embodiment of the lens is shown, where the openings4a,4bof the wall portion4are smaller than the clear aperture3aof the lens shaping element3and thus the lens area21a. This provides some additional aperture to the lens1that is particularly useful when the lens1is used for large incidence angles of light entering the lens1from the side of the window element5. This design suppresses stray light caused by large incident angles of light due to the smaller opening4a,4bof the wall portion4.

FIG.4shows an embodiment similar to the embodiment ofFIG.1, with the difference that the wall portion4and the lens shaping element3are formed as separate members that are connected to each other, e.g. by means of glue.

This allows for manufacturing the wall portion4and the lens shaping element3from different materials, particularly wherein the lens shaping element3might comprise a metal compound or a magnetic compound that might be essential used for an actuation capability of the actuation element6.

FIG.5shows an embodiment in which the lens shaping element3is arranged outside the lens volume VL. The wall portion4now forms the lateral container walls that enclose the lens volume VL in which the first liquid L1is comprised.

The first side4-1of the wall portion4is circumferentially and sealingly connected with the second side21-2of the first membrane21and the second side4-2of the wall portion4is circumferentially connected with the second side22-2of the second membrane22.

The first opening4aof the wall portion4is smaller than the second opening4bof the wall portion4. The wall portion4is essentially formed from two ring shaped portions having different diameter.

The lens shaping element3is connected with a second side3-2to the first side21-1of the first membrane21. The aperture3aof the lens shaping element3is slightly smaller than the first opening4aof the wall portion4.

The lens shaping element3is connected rigidly via the first membrane21to the wall portion4by having an overlapping portion with the wall portion4.

It is noted that the window element5and the corresponding aperture5ais larger than the aperture3aof the lens shaping element3, such that in a tilted actuation configuration of the window element5, the clear aperture3aof the lens shaping element3is not obstructed or affected by the actuation element6.

InFIG.6a similar embodiment of the lens1ofFIG.5is shown, wherein the lens shaping element3is arranged non-overlappingly with the wall portion4. The lens shaping element3can be fixed relative to the wall portion by a housing member (not shown) of the lens1or another external component (not shown). This embodiment allows for defining the clear aperture of the lens1by an external component (i.e. the lens shaping element3) during assembly of the lens, which increases manufacturing tolerances during assembly and which provides increased flexibility for using differently shaped lens shaping elements3without the necessity of a redesign of the lens1, i.e. the body of the lens1remains the same, while the size and shape of the lens area21acan be defined by choosing the appropriate lens shaping element3with an appropriate shaped clear aperture3a(e.g. circular, rectangular or oval).

InFIG.7another embodiment regarding the lens shaping element3and the wall portion4is shown.

The wall portion4comprises a recess in which the lens shaping element3is comprised inside the lens volume VL. This allows for a larger contact area of the lens shaping element3to the wall portion4, which in turn allows for a more stable connection between the lens shaping element3and the wall portion4. Moreover, the lens shaping element3might be made from a different material than the wall portion4.

FIG.8shows a similar embodiment as shown inFIG.1.

In addition to the embodiment ofFIG.1, the actuation element6comprises a rigid portion6athat extends laterally along a plane of the window element5without obstructing the window aperture5a. The rigid portion6amight be ring-shaped or arm-shaped. The rigid portion6ais connected to the window element5via a damping element6band at its outer portion the rigid portion6ahas another damping element6carranged. The damping elements6b,6care softer than the rigid portion6aof the actuation element6and the window element5and are configured to absorb vibrations and to provide a larger stroke of the actuation element6that is only partially translated to the lens area21a. A larger stroke of the actuation element6in turn increases an actuation sensitivity of the lens1, as the stroke is partially absorbed (e.g. by a deformation/compression/extension) by the damping elements6b,6c, when the window element5is moved from its equilibrium position. This in turn allows to use actuators having a lower stroke resolution and that are more cost efficient.

As similar effect can be achieved with a lens1as shown inFIGS.9A and9B.

Here, the actuation element6comprises a spring element6sextending laterally from the window element5. Here, the spring element6sallows for the larger stroke of the actuation element6. The stroke (i.e. movement of the actuation element6) is not fully translated to the lens area21abut is partially absorbed by a deformation of the spring element6sas can be seen inFIG.9B.

FIG.10shows an embodiment of the lens1devoid of the rigid wall portion4.

The lens volume VL with the first liquid L1is completely enclosed by the first membrane21and the second membrane22only.

In a first variant, the first21and the second membrane22are two separate membranes that are sealingly and circumferentially connected, e.g. glued or plasma-bonded, at a lateral membrane portion21-22of the lens volume VL, wherein the lateral portion21-22extends circumferentially around the lens area21aof the first membrane21and circumferentially around the free portion22bof the second membrane22.

This allows using different membranes for the first21and the second membrane22.

In another variant, the first21and the second membrane22are integrally formed, e.g. by a sleeve-like membrane and sealed at the openings of said sleeve.

The lens shaping element3is arranged outside the lens volume VL (but could also be arranged inside the lens volume VL) as shown in previous embodiments.

Upon actuation of the window element5relative to the lens shaping element3the lens area21abends outwards or inwards. At the same time, it might be that the lateral portion21-22and/or the free portion22balso bend. This provides a damping effect, which in turn allows for larger stroke actuation resulting in a higher actuation resolution of the lens1.

The lens1according to this embodiment can be manufactured comparably cost-efficient as no wall portion is needed.

In the following, several advanced embodiments of the lens1according to the invention are described that can be combined with the embodiment of theFIGS.1to10. The lens1according to some embodiments can be configured to compensate for acceleration-induced aberrations, such as gravity-induced coma.

For this purpose, the lens1comprises a first volume V1comprising the first liquid L1and a separate second volume V2with a second liquid L2. Thus, the lens volume VL is split into the first V1and the second volume V2.

The physical properties of the first and the second liquid L1, L2might be chosen such that the acceleration-induced aberrations are compensated. Such physical properties comprise the refractive index n1, n2as well as the mass density ρ1ρ2of the first and the second liquid L1, L2. Simultaneously, it is possible to adjust some properties of the first and the second membrane21,22as well as a third membrane portion20,23, such properties being for example the stiffness of the membranes or to adjust the thickness of the membranes that in turn might influence the stiffness of the membranes.

An example of one of such lens1that is configured to compensate acceleration in-induced aberrations is shown inFIG.11. As many features of the lens ofFIG.11are identical to the features ofFIG.1only the differing features are elaborated in detail in order to avoid redundancy. It is obvious that also embodiments shown inFIGS.2to10can be modified accordingly in order to provide the acceleration-induced aberration compensation.

The lens1ofFIG.11differs from the lens ofFIG.1in that the lens1additionally comprises a separating membrane portion20,23that essentially divides the lens volume VL in the first volume V1comprising the first liquid L1and the second volume V2comprising the second liquid L2. The first and the second volume V1, V2are arranged such that along the optical axis OA and particularly over the complete lateral extent of the window element aperture5aa layer of the first and second liquid L1, L2is arranged.

The separating membrane portion20has a first side20-1facing the first volume V1and that is in contact with the first liquid L1and a second side20-2that faces in the opposite direction and that is in contact with the second liquid L2.

In the embodiment ofFIG.11the separating membrane portion20is a separate third membrane23, with corresponding sides23-1and23-2. The third membrane23is sealingly and circumferentially connected with its second side23-2to the first side22-1of the second membrane22, such that the second volume V2is formed by the third23and the second membrane22only. The second22and the third membrane23can be connected for example by means of plasma bonding or glue.

The second membrane22and in some embodiments the third membrane23cover the second opening4-2of the wall portion4and thus, seals the first liquid L1together with the wall portion4and the first membrane21that covers the clear aperture3aof the lens shaping element3such that the first volume V1is formed.

The window element5, as inFIG.1, is connected to the second side22-2of the second membrane22on one side of the window element5.

Other features of the lens1ofFIG.11are essentially identical to the features ofFIG.1.

In response to a relative motion that changes the net volume of the lens volume VL of the window element5with respect to the lens shaping element3, the lens area21abends and forms either a concave or convex surface lens surface. The membrane shape of the third membrane23and the second volume V2is hardly affected by such a motion.

Therefore, the robust and accurate adjustment of the curvature of the lens area21athat have been elaborated for the previous embodiments are maintained. In addition, the lens1ofFIG.11is configured to compensate for the acceleration-induced aberrations that might be caused by gravity or another accelerating force.

For this compensating effect to take place in a non-trivial fashion, the force has to have a force component that is not in alignment with the optical axis OA of the lens1.

By adjusting the refractive index n1, n2of the first and the second liquid L1, L2with respect to the first ρ1and the second mass density ρ2of the liquids L1, L2, such acceleration-induced aberrations can be compensated.

For example, the refractive index n1of the first liquid L1might be chosen higher than the refractive index n2of the second liquid L2, while the mass density ρ1of the first liquid L1is chosen to be smaller than the mass density ρ2of the second liquid L1.

This allows adjusting the optical path length through the lens volume VL such that the acceleration-induced aberrations can be compensated to full extend.

In addition, a relation between membrane stiffness ksof third membrane23or the separating membrane portion20and the stiffness k1of the first membrane21can be found according to

Other relations relating thicknesses of the membranes20,23,21to the refractive indices n1, n2are given at another part of the specification and can be applied to this embodiment as well.

A variation of the embodiment ofFIG.11is shown inFIG.12. Here, the separating membrane portion20is integrally formed22cwith the second membrane22. In order to provide the second volume V2the second membrane22is sealingly connected with its second side22-2to the window element5only at a circumferential portion5cof the window element5, such that a volume is formed between an integral portion22cof the second membrane22and the window element5. Thus, the second side22-2of the second membrane22faces the second volume V2over the area of integral portion22c.

For this embodiment, no third membrane is required, which reduces manufacturing costs.

The relation for the stiffness and thickness of the membranes might be applied for the first and the second membrane21,22accordingly.

The embodiments shown inFIGS.11and12allow for lower actuation forces and thus lower power consumption, as the third membrane23or the integral membrane portion22cis not bent upon actuation of the window element5, but only the lens area21aof the first membrane21(and the free portion22bof the second membrane22).

InFIG.13another embodiment of the lens1according to the invention is shown having an acceleration-induced aberration compensation.

The lens1comprises a third membrane23as the separating membrane portion20.

In contrast to the embodiments ofFIGS.11and12, inFIG.13the third membrane23is arranged along the optical axis OA between the wall portion4and the lens shaping element3and separates the lens volume into the first V1and the second volume V2, wherein with a first side23-1of the third membrane23, the third membrane23is in contact with the first liquid L1and with a second side23-2of the third membrane23, the third membrane23is in contact with the second liquid L2.

The first membrane21seals the lens volume VL and in particular the first volume V1at the first side3-1of the lens shaping element3, where the lens area21ais formed by the clear aperture3a, wherein the second membrane22seals the lens volume VL and in particular the second volume V2at the second side4-2of the wall portion4.

Therefore, the first liquid L1is enclosed in the first volume V1formed by the first membrane21, the third membrane23and the lens shaping element3, wherein the second liquid L2is enclosed in the second volume V2formed by the second membrane22, the third membrane23and the wall portion4.

For assembly, the third membrane23is connected between the lens shaping element3and the wall portion4, particularly between the second side3-2of the lens shaping element3and the first side4-1of the wall portion4. The lens shaping element3and the wall portion4might be formed from different materials. Particularly, the wall portion4might comprise a permanent electro-magnetic compound and might be shaped in a non-round fashion (when viewed along the z-axis), while the actuating element6might comprise a corresponding metal compound such that a reluctance driving force can be induced by these two elements causing the actuation element6to move relatively to the wall portion4and thus adjustment of the refractive power of the lens1can be achieved. Alternatively, the actuation element6is comprises a permanent electro-magnetic compound and the wall portion4is made of a metal compound, such as steel. For this purpose, one or more coils (not shown) might be arranged next to the wall portion4. The lens shaping element3might be made of glass or a polymer.

The embodiment shown inFIG.13causes the third membrane23to bend as well, when the window element is actuated, and thus depending on the refractive indices n1, n2of the first L1and the second liquid L2, the third membrane23might contribute to the refractive power of the lens1, which might be advantageous in certain instances.

FIG.14shows an embodiment of an acceleration-induced aberration compensating lens1according to the invention. The lens1has an integrally formed lens shaping element3and wall portion4like the lens shown inFIG.1. In addition, the third membrane23forming the membrane portion20is sealingly connected with its first side23-1,20-1to the second side21-2of the first membrane21, such that the first volume V1comprising the first liquid L1is formed between the first21and the third membrane23. The second volume V2comprising the second liquid L2is formed between the third membrane23, the second membrane22, the lens shaping element3and the wall portion4.

The first21and the third membrane23might be connected by plasma-bonding.

FIG.15shows an embodiment of the lens1that comprises an additional second wall portion7that contacts the second side22-2of the second membrane22circumferentially with a first side7-1of the second wall portion7. With a second side7-2, the second wall portion7is connected or integrally formed with the window element5. The opening7aof the second wall portion7defines the window portion22ato be a flexible lens area, within which the second membrane22might change its surface for adjusting the refractive power of the lens1. The first volume V1is enclosed between the first membrane21, the lens shaping element3, the wall portion4and the second membrane22. The second volume V2is enclosed by the second membrane22, the second wall portion7and the window element5.

The wall portion4is connected with its second side4-2to the first side22-1of the second membrane22and faces with its first4-1the second side3-2of the lens shaping element3.

As can be seen inFIG.15, the openings4a,7aof the wall portions4,7and the aperture of the lens shaping element3are all different, which allows a greater flexibility in terms of aperture design in combination with a reluctance motor.

While the lens shaping element3might be made of glass or a polymer, the wall portion4might be made of a metal compound such as steel and the actuation element6is made from a permanent electro-magnetic compound such that by means of a coil assembly (not shown) arranged at the wall portion4, the actuation element6can be moved relative to the lens shaping element, causing a change of refractive power of the lens1. The second wall portion7is made from a neutral material with respect to the electro-magnetic actuation. The second wall portion7can be regarded as a part of the window element5. In fact, the second wall portion7might be made from the same material as the window element5or even be integrally formed with the window element5.

Upon actuation with the actuation element6, the window element5and the second wall portion7exert a force on a contact portion22gof the second membrane22that corresponds to the first side7-1of the second wall portion7.

This causes the first membrane21to alter its shape, i.e. its curvature, in the lens area21aand the second membrane22to alter its shape in the window portion22aaccordingly, depending on the stiffness of the two membranes21,22. This allows for providing a double convex or double concave lens1with acceleration-induced aberration compensation.

In yet another embodiment of the invention, the lens1as shown inFIG.16comprises the first volume V1enclosed between the first membrane21, the cylindrical wall portion4that is integrally formed with the lens shaping element3and the third membrane23, wherein the first membrane21is connected to the first side3-1of the lens shaping element3and the third membrane23is connected to the second side4-2of the wall portion4. The second volume V2is enclosed between the third membrane23and the second membrane22that is circumferentially connected to the third membrane23, such that the second volume V2has a cushion like structure. On the second side22-2of the second membrane22, the window element5is arranged. This embodiment is structurally similar to the embodiment ofFIG.11, with the difference that the third membrane23is attached to the wall portion4rather than to the second membrane22.

The embodiment inFIG.17is a further development of the embodiment ofFIG.11. In addition to the embodiment ofFIG.11, the cross-section of the integrally formed wall portion4and lens shaping element3slightly differs from the embodiment ofFIG.11, as the step-like contour is replaced by a more continuous contour43. The main difference, however, is that on the first side21-1of the first membrane21on the outside of the lens volume VL, an additional member8is connected to the lens1that serves as an aperture of the lens1. The additional member8has a central aperture8athat is placed at a distance D to the first membrane21along the optical axis OA. This allows for manufacturing a lens1with various sizes of apertures that can be modularly applied to the lens1. The distance D allows the first membrane21to bend toward the aperture8aof the additional member8without touching said aperture8a.

Embodiments shown inFIG.18andFIG.19concern a lens design that allows for a particularly light-weight lens1. The lenses1ofFIGS.18and19are similar to the lens ofFIG.10that discloses a pillow-like lens volume VL.

In addition to the lens ofFIG.10, the lenses1ofFIGS.18and19each are modified to compensate acceleration-induced aberrations by having the first and the second volume V1, V2with the first L1and the second liquid L2. The lens volume VL comprises the first volume V1and the second volume V2. The first volume V1is completely enclosed by the first membrane21and the second membrane22that are sealingly connected at a circumferential21-22portion to the second membrane22. The second membrane22is connected at a circumferential portion5cof its second side22-2to the window element5, while the window portion22aof the second membrane22integrally comprises the separating membrane portion20. Between the separating membrane portion20and the window element5, the second liquid L2is comprised in the second volume V2. This structure has been elaborated already forFIG.12in detail, which is applicable toFIG.18as well. The lens shaping element3is connected with a second side3-2to the first side21-1of the first membrane21from an outside of the lens volume VL. Any actuation of the lens1is provided via the window element5, wherein the lens shaping element3remains at a fixed position, which allows for the advantageous effects of a fixed lens shaping element3as elaborated previously. For this purpose, the lens shaping element3protrudes radially away from the optical axis OA, such that it can be rigidly connected to a fixing member (not shown). The window element5can be actuated at least along the z-axis, wherein the first membrane21, particularly the lens area21amight change it curvature in the clear aperture3aof the lens shaping element3in response to an actuation of the window element5.

In contrast ofFIG.8, where the window element5extends laterally beyond the clear aperture3aof the lens shaping element3, which reduces stray light due to edge effects of the window element5, such that the window element5is essentially invisible, the situation is different in the embodiments ofFIG.19AandFIG.19B, where the window element5is smaller and does not extend beyond the clear aperture3aof the lens shaping element3and more light-weight as compared to the window element ofFIG.18.

InFIG.19, the second volume is formed by the second membrane22and the window element alone, wherein inFIG.19Bthe second Volume is enclosed by the third membrane23and the second membrane alone. In both embodiments, upon actuation the second lens volume V2essentially remains at the same size.

As elaborated inFIG.10, the first21and the second membrane22might be two separate membranes or made of a sleeve-like membrane that is connected at the openings of the sleeve21-22for both embodimentsFIG.19AandFIG.19B.

FIG.20shows an embodiment of a pillow-like embodiment of the lens1that arises from a combination of the embodiment ofFIG.14andFIG.10. However, the embodiment ofFIG.20, in contrast to the embodiment ofFIG.14, has a pillow-like lens volume VL formed only by the first21and the second membrane22with no solid components inside the lens volume VL. The lens1comprises a third membrane23that is connected to the first membrane21on an inside of the lens volume VL, i.e. the third membrane23is connected with its first side23-1to the second side21-2of the first membrane21, such that the first volume V1is formed between these membranes21,23. The second volume V2is formed exclusively by the first, the second and the third membrane21,22,23. Outside the lens volume VL, the lens shaping element3is connected to the first membrane21and the window element5is connected to the second membrane22. Actuation is facilitated by either moving the window element5relative to the lens volume VL and the lens shaping element3that remain fixed or by moving the lens volume VL and the lens shaping element3(as a whole) relative to the window element5that remains fixed.

As can be seen inFIG.20, the first membrane21adopts a convex shape in its equilibrium position (i.e. while no actuation of the window element is performed), such that the lens1has a refractive power in its equilibrium state. This obviously, can be applied to all embodiments of the invention. Similarly, the lens1could be adjusted such, that in its equilibrium position, the first membrane21adopts a concave shape. Both equilibrium states can be achieved by adjusting a pressure of the first liquid L1inside the lens volume VL.

FIG.21discloses a lens1that is configured to compensate acceleration-induced aberrations as the lenses of previous figures.

Here, the lens volume VL is formed by a pillow-like second lens volume V2that is exclusively formed by the second22and the third membrane23with no rigid components on its inside. At its rim portions22-23the third23and the second membrane22are sealingly connected to seal the second liquid L2in the second volume V2.

The first lens volume V1is enclosed by the third membrane23, the lens shaping element3and the first membrane21.

The lens shaping element3is connected with the first side3-1to the first membrane21and with its second side3-2to the third membrane23.

The lens shaping element3protrudes radially away from the clear aperture3a, such that a fixing member (not shown) may be connected to the lens shaping element3.

The window element5is connected to the second side22-2of the second membrane22via the window portion22aof the second membrane22to the second membrane22.

FIGS.22to25focus on actuation assemblies for the lenses according to the invention. While the embodiments only show lenses without acceleration-induced aberration compensation, it is noted that also embodiments having the lens volume VL separated in the first V1and the second volume V2for acceleration-compensation can be equipped with the actuation assemblies in the same manner.

The common design of the actuation assemblies shown inFIG.22toFIG.25is that the actuation coils9are arranged movable relative to the lens shaping element3.

InFIGS.22to25, at the window element5, the actuation element6extends laterally away from the window element5such that it protrudes beyond the wall portion4of the lens1. In terms of a three-dimensional view, this might be by means of separate protruding arm members6aor by means of a ring- or disc-like structure6a. This lateral protruding member is also referred to as the lateral mover element portion6ain the context of the current specification. As elaborated for previous embodiments the actuation element6might comprise damping elements (not shown). The actuation element6can also serve as an aperture for the lens1as shown inFIG.22toFIG.25, limiting the aperture of the lens1on the side of the window element5.

At an outer portion6dof the protruding member6athat lies laterally beyond the wall portion4, a coil portion6eis arranged, wherein said coil portion6ecomprises one or more coils9. Typically, four or more coils9are arranged on the protruding member6acircumferentially around the wall portion4. InFIGS.22to25only two coils9can be seen. The coils9extend with their coil axes essentially parallel to the optical axis OA of the lens1, when in equilibrium state. Correspondingly to the coils9, the lens1comprises magnetic portions10, particularly comprising a permanent magnet10, particularly in form of a permanent ring magnet or a plurality of separate magnets. The magnetic portions10are rigidly connected to the wall portion4on an outside of the lens volume VL that faces the coils9. As such the coils9are arranged opposite the corresponding magnetic portions10on the outside of the lens volume. Between the coils9and the magnetic portions10a predefined lateral distance or air gap50is provided, such that the coils9are free to move and tilt to some extent relative to the magnetic portions10. The magnetic poles N, S of the magnetic portions10are arranged in a radial or lateral fashion with respect to the optical axis OA, such that the magnetic dipole vector is oriented essentially orthogonal to the coil axes. The coils9overlap along the optical axis OA at least partially with the magnetic portions10. With the coil axes and the magnetic poles oriented and positioned as described, actuation of the window element5relative to the wall portion4and thus the lens shaping element3becomes possible by means of a Lorentz force. Therefore, by providing appropriate electrical currents to the coils9virtually any movement of the window element5relative to the lens shaping element3can be achieved.

The coils9can be wound around a solid axis of the coil portion (not shown).

The advantage of this actuation assembly is that is less susceptible to external magnetic fields as compared to reluctance-based actuation assemblies.

The embodiment ofFIG.22further comprises a silicon lens shaping element3that extends laterally beyond the wall portion4and the lens volume VL, such that it provides a hard stop for the coil motion along the optical axis. Further, a hard stop portion11is connected to the lens shaping element3at an outer portion3eof the lens shaping element3, wherein said hard stop portion11extends in a housing-like fashion around the coil portion and the protruding member6dof the actuation element6, such that a hard stop is provided also to the actuation element6from the other side of the lens1.

The two hard stops limit the range of the coil motion along the optical axis OA in both directions such that accidental overdrives or shock-induced motions will do no harm to the actuation assembly.

InFIG.23the lens shaping element3is floatingly arranged on the first membrane21, i.e. it is not in rigid contact with the wall portion4.

In the embodiment ofFIG.23, the wall portion4consists of the magnetic portions10, which reduces the assembly complexity of the lens1.

The lens1comprises a separate hard stop portion11that is configured to limit the movement of the coils9toward the side of the lens1, where the lens shaping element3is located.

InFIG.24a very similar embodiment as inFIG.22is shown, however without any hard stop portions or housing-like features.

In contrast toFIG.22, the coils9are attached to a rigid coil portion6eand not wound around an axis of the coil portion6e.

InFIG.25, an example is shown that illustrates an electric contacting of the coils9. For this purpose, for each coil9a contacting member12is arranged on the first side (i.e. the side of the lens1on which the first membrane21is arranged) of the lens1. The contacting members12comprise a spring-like member12athat physically connects the coils9with the wall portion4and the magnetic portions10on a side of the coils9that faces away from the protruding member6a. The spring-like members12aprovide a restoring force, while at the same time said members12aare configured to provide electricity to the coils9for controlling orientation and position of the window element5and thus, the refractive power of the lens1.

The spring like members12amight be formed as leaf springs.

InFIGS.26and27a different actuation assembly is shown. The actuation is based on a reluctance drive.

For this purpose, the coils9are arranged fixedly at the wall portion of the lens1, with an orientation of the coil axes pointing along the lateral plane (in the angular direction of the lens into the drawing plane or outwards the pane of drawing) extending orthogonal to the optical axis9aof the lens1. The wall portion4is made of a metal compound, such as iron. Similarly, the actuation element6, particularly the protruding portion of the actuation element6comprises or consists of a metal compound such as iron.

An electrically conducting material may be used instead of the metal compound.

When an electrical current is applied to the coils9a reluctance force is induced in the protruding member6aof the actuation element6, such that the position and orientation of the window element5can be controlled. The wall portion4amplifies said force up to a factor1000. As elaborated previously, the design of the lens1with regard to the arrangement of the lens shaping element3, the membranes21,22(and particularly20,23) etc. can be adapted to previous embodiments in a similar fashion.

An example for the adaption of the embodiment ofFIG.26to a lens configured to compensate acceleration-induced aberrations is given inFIG.27.

The lens ofFIG.27essentially corresponds to the lens1ofFIGS.11and/or12. In addition the lens ofFIG.27comprises the actuation assembly laid out inFIG.26.

The reluctance-based actuation provides a very compact lens design.

InFIG.28an example is shown in which the lens shaping element3in combination with the lens volume VL might be moved relative to the window element5as part of an optical system100.

The lens1ofFIG.28comprises an additional optics assembly13comprising a further lens13athat might be glued to the window element5. The lens volume VL is enclosed by the first and the second membrane21,22and the wall portion4that is integrally formed with the lens shaping element3(similar toFIG.2).

The window element5together with the optics assembly13is rigidly attached to some fixing member (not shown) that does not move, and might be connected to a housing of the lens. In order to adjust the refractive power of the lens1, an actuator14, e.g. a piezo actuator, is connected to the lens body comprising the lens volume VL, the first and the second membrane21,22and the lens shaping element3. The actuator14might be rigidly connected with an end portion14eto a fixing member (not shown) and with a connecting portion14cto the lens body.

The lens body can be displaced relative to the window element5, by providing an actuation force generated by the actuator14, such that lens body is displaced relative to the window element5. This way, a relative movement of the window element5with respect to the lens shaping element3is achieved, while the lens shaping element3does not move relative to the wall portion4, the first and the second membrane21,22, i.e. relative to the lens body.

InFIGS.29to30, various embodiment of an optical system100comprising an optical sensor in form of an array detector102, such as a camera that is arranged on an optical axis of the system100that corresponds to the optical axis OA of the lens1. The system further comprises an optical assembly101comprising at least one hard lens101L.

InFIG.29, the lens1and the optical assembly101are arranged at a fixed distance to each other while the lens1is located on an side of the system where the light is enters the system, i.e. the lens1that has the largest distance to the array detector102.

The lens1might provide focusing of an image to the array detector102.

InFIG.30A, the system100comprises two lens assemblies110,120, wherein between the lens assemblies110,120the lens1according to the invention is located. This way, the lens1might be used for a zoom function of the optical system100. InFIG.30Athe lens1faces with its first membrane21toward the array detector102, wherein inFIG.30Bthe lens1faces with its first membrane away from the detector102.

The lens1might provide optical image stabilization, e.g. by means of tilting the window element5accordingly, or superresolution imaging, also by way of tilting the window assembly, such that the induced prism of the lens1projects the image onto different portion on the array detector102in the latter case.

InFIG.31AandFIG.31Ba two three-dimensional views of the lens1according to the invention are shown. InFIG.31A, the lens shaping element3has a circular, disc-like shape, wherein inFIG.31Bthe lens shaping element3has additional protrusions that can be used for attaching and orienting the lens shaping element to external fixing elements (not shown).

In both FiguresFIG.31AandFIG.31B, the window element5is connected to the actuation element6that comprises a plurality of protruding members6ato which an actuator might be connected.

InFIG.32an example of the lens is shown that demonstrates that a relative movement of the window element5relative to the lens body or the lens shaping element3may be achieved by either by actuating the window element5actively and having the lens shaping element with the lens body fixed relative to the window element or by actuating the lens shaping element or the lens body actively and having the window element5fixed relative to the lens shaping element or the lens body. Both actuation methods provide the desired advantages of the lens novel lens design according to the invention.

The double arrow200indicates exemplary actuation directions.