Patent Description:
There is an ever increasing demand for low cost, high volume solutions for optical (micro-)elements, such as lens assemblies, with adjustable focal length and the highest possible imaging quality and which are impact resistant. Modern mobile phones, for example, are now equipped with miniature digital camera modules and the quality and cost demands for optical elements, such as lenses and lens assemblies, are increasing and they are required to be impact resistant. More and more miniature cameras used in mobile phones and laptop computers have auto focus functionality. The design of, e.g., lens systems for such applications requires fulfilment of a large number of requirements, from production standards to ease of operation when fitting the lens on top of a camera module. These challenges are even greater when the lens arrangement comprises tuneable parameters, such as encountered in auto focus lenses, wherein the focal length must be adjusted, for example, to fit the distance from the lens to the object to be photographed. Such optical elements are usually complex designs comprising movable parts that can make it difficult to assemble the optical element in a simple manner. A further challenge with such designs is the ever-increasing requirements to provide suitable optical elements, such as lens assemblies, for such use. It is particularly challenging to make these optical elements impact resistant and in particular when the optical and mechanical properties must be kept at a high level.

There exist a number of solutions for making compact auto focus optical elements. One of the problems of current solutions is how to provide good impact resistance, such as good impact resistance while maintaining good optical and mechanical properties.

For example, <CIT> relates to varifocal lens solutions for camera module comprising a membrane, a frame, a transparent substrate, one or more actuators and a restriction lessening member which is adapted to lessen a restrictive force of an edge of the fluid lens part.

Other current solutions describing optical element having adjustable focal length are <CIT> and <CIT>.

Hence, an optical element with improved impact resistance would be advantageous, and in particular an optical element, such as a tuneable optical micro lens with improved impact resistance, where the means for enabling good impact resistance entails only little or no degradation in optical and mechanical properties, would be advantageous.

It may be seen as an object of the present invention to provide an optical element, such as a tuneable optical element, that solves the above mentioned problems of the prior art, such as to provide an optical element (such as a tuneable optical element) with improved impact resistance. It may be seen as a further object of the present invention to provide an alternative to the prior art.

Thus, the above described object and several other objects are intended to be obtained in a first aspect of the invention by providing an optical element, such as an optical lens, such as a tuneable optical lens, defining an optical axis and comprising:.

characterized in that the Young's modulus of the supporting structure is less than the Young's modulus of the bendable cover member.

The invention is particularly, but not exclusively, advantageous for obtaining an optical element, such as optical (refractive) lens, such as a tuneable micro lens, which may have improved impact resistance and/or improved ability to endure an impact ensuing a drop. Another possible advantage may be that the proposed solution does not significantly impair optical properties (such as wavefront error and/or transmittance and/or tuneability, e.g., range of dioptres, which may be spanned) and/or mechanical properties (such as flexural rigidity of the bendable cover member).

It may be seen as an insight of the present inventors that an abrupt change, such as a single abrupt change, in mechanical properties at, e.g., an inner edge of a supporting structure may lead to excessively large stresses, such as excessively large stresses in the bendable cover member. The features of the present invention may enable avoiding such excessively large stresses. It may be seen as an insight of the present invention, that stresses at such abrupt changes (singularities) may advantageously be redistributed, such as via structures which change thickness and/or Young's modulus gradually or in a plurality of steps.

According to the invention, the supporting structure increases thickness and/or Young's modulus (such as "spring constant") gradually and/or in a plurality of steps (such as not in a - single - step function) and/or the bendable cover member may be thicker (i.e., have a larger dimension in a direction being parallel with the optical axis) at the contact point with the supporting structure - such as at a sidewall of the supporting structure - than inside the supporting structure (such as closer to the optical axis). By 'thickness' may be understood 'thickness of coherent material', such as if there is a gap in the material then only the material until the gap contributes to the thickness, whereas material below the gap does not.

It is understood that the supporting structure on the one side of the interface plane may comprise a combination of gradual and stepwise increases of the thickness, i.e. a portion of the supporting structure may be formed with a gradual increase of the thickness and another portion of the supporting structure may be formed with stepwise increase of the thickness.

The stepwise increase of the thickness and/or Young's modulus with a plurality of steps may be in a form which approximates the gradual increase of the thickness/Young's modulus. Accordingly, the plurality of steps may comprise at least <NUM> or <NUM> steps, such as at least <NUM> or at least <NUM> steps in order to approximate a continuous gradual increase. As noted elsewhere, the gradual or approximated gradual increase of thickness may improve mechanical properties with respect to improved impact resistance. Equivalently, the gradual or approximated gradual increase of the Young's modulus similarly improves the mechanical properties. The stepped increase of the thickness/Young's modulus is an approximation to a continuous increase of the thickness/Young's modulus. However, whether the increase is in the form of multiple steps or a continuous variation, both examples exhibits a gradual increase of the thickness/Young's modulus. Accordingly, the stepped increase of the thickness or Young's modulus is an example of the gradual increase of the thickness (i.e. dimension in a direction being parallel with the optical axis) or Young's modulus.

For example, the supporting structure may comprise a combination of different layers deposited and patterned separately from the front side of a wafer. They could be of different materials, such that the selectivity of the back side etching would lead to the desired stepped shape.

The extension of the line where at least a portion of the increasing thickness is formed extends a point at an inner edge of the interface to the point more distantly placed with respect to the optical axis. Accordingly, the point at the inner edge of the interface is located closer to the optical axis than the more distantly placed point - and the line extends between these points.

The shaping of the bendable cover member into a desired shape by means of the one or more actuators may be achieved by the stress generated by the actuators on the cover member which thereby responds with a deformation dependent on the stress and location of the actuators.

A possible advantage of the present invention may be that it enables providing the supporting structure and placing the cover member thereon and then - without necessitating further steps and/or additional reinforcing elements on the opposite site of the cover member (with respect to the supporting structure) - features of the present invention may be integrated. The invention may thus be seen as enabling a simple and/or efficient method of manufacturing (regardless of whether the supporting structure and/or the cover member is arranged to mitigate the stress singularity issue described above). It may be an advantage, that other elements, such as actuators, can be placed on the opposite side of the cover member (with respect to the supporting structure), such as without interfering with features arranged to mitigate the stress singularity issues described above.

By 'optical element' may be understood an element which acts upon (such as manipulates) light passing through the element (such as the element being an optical lens, such as an optical refractive lens) or which acts upon light being reflected from the optical element (such as the optical element being a reflective element or a reflective mirror).

The optical element may in general be a tuneable optical element. By 'tuneable' may be understood that a focal length of the optical element may be tuned, such as by actuation of the actuators, e.g., (where the actuators are piezoelectric actuators) by changing an applied voltage of the one or more piezoelectric actuators arranged for shaping said bendable cover member into a desired shape.

The deformable transparent lens body such as a transparent, deformable, non-fluid body. The deformable, non-fluid lens body is preferably made from an elastic material such as an elastic polymer-material. Since the lens body is non-fluid, no tight enclosure is needed to hold the lens body, and there are no risk of leakage. The lens body may be made from a soft polymer, which may include a number of different materials, such as silicone, polymer gels, a polymer network of cross-linked or partly cross-linked polymers, and a miscible oil or combination of oils. The elastic modulus of the non-fluid lens body may be larger than <NUM> Pa, thereby avoiding deformation due to gravitational forces in normal operation. The refractive index of the non-fluid lens body may be larger than <NUM>.

Using a soft polymer makes it possible to produce lenses where the polymer is in contact with air, thus requiring much less force when adjusting the focal length of the lens, e.g. as compared to case when the polymer fills the entire cavity. It also eases the production, as the polymer will keep in place even if the different production steps are localized in different positions or facilities.

'Optical axis' is commonly understood in the art, and is understood to intersect the cover member (and, in case of the optical element being an optical lens, the optical axis is also understood to intersect the lens body), such as pass through the lens body and the cover member.

It may in general be understood when referring to optical properties within this application, that the optical property (such as transmittance or opacity or transparency or reflectivity) applies for light travelling within an angle of incidence (AOI) with respect to the optical axis, such as through the optical aperture (for an optical lens) or being reflected of the optically active area (for a reflective element), wherein the angle of incidence is within an angle of <NUM>-<NUM>°, such as <NUM>-<NUM>° (such as <NUM>°) with respect to the optical axis. An optical property may be understood to be an optical property at a specific wavelength, such as any wavelength within the visible region, such as <NUM>, and/or at a specific angle of incidence, such as <NUM>°, such as at a wavelength of <NUM> and at an angle of incidence of <NUM>°.

When referring to 'average' of an optical property, it is understood as a double average of said property within a wavelength range and an angle of incidence (AOI) with respect to the optical axis, wherein the wavelength range may be within <NUM> to <NUM>, such as wherein the wavelength range may correspond to one or more or all of:.

and wherein AOI is <NUM>-<NUM>°, such as <NUM>-<NUM>°, such as <NUM>°.

'Optical' is to be understood as relating to 'light', and 'light' is understood to be electromagnetic radiation within one or more or all regions corresponding to UV, visible, nIR, mIR and fIR, such as within the visible region.

Reference to 'transparent' is generally understood with reference to light, i.e., light may pass through a transparent object, with little or no intensity loss, such as losing on average <NUM> % or less, such as on average <NUM> % or less, when passing through the material (corresponding to an average transmittance of, respectively <NUM> % and <NUM> %).

By 'transmittance', such as the specular transmittance or regular transmittance, may in the present context of transmittance with respect to the optical element, such as the optical lens, be understood the average (within a wavelength range and within the angle of incidence range) ratio between.

By 'sidewall' may be understood a support element or a part (such as a surface) of the support element, which at least partially supports the bendable cover member, such as supports the bendable cover member in a region immediately outside or close to the optically active area, such as the optical aperture.

By 'supporting structure' may be understood the structure, such as frame, which mechanically holds the bendable cover member in place, such as fixates the bendable cover member. In, e.g., a camera, the supporting structure fixates the cover member with respect to the remainder of the camera. The supporting structure can be monolithic, for example a silicon element with a protruding element inwards towards the optical axis, or non-monolithic (such as composed of two or more monolithic materials), for example a silicon element and an epoxy element protruding inwards towards the optical axis.

'Epoxy' is understood as is common in the art, and may in particular refer to the cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups.

In possibly advantageous embodiments, an epoxy may be applied which comprises or consists of liquid, flowable thermoset or UV-curable (or a combination) adhesives with or without inorganic or organic filler materials, which has a low viscosity achievable before curing sets in (such as a viscosity equal to or less than <NUM> mPas (milli Pascal second), such as from room temperature (such as <NUM> or <NUM>) to a temperature/time upon heating before viscosity increases due to cross-linking reactions in the adhesive), with Young's modulus after curing equal to or larger than <NUM> GPa. Additional possibly advantageous features of an applied epoxy may include one or more of: Low shrinkage, good thermal stability and good moisture resistance.

The bendable cover member may be relatively thin, such as thin with respect to the supporting structure (and/or the lens body when present), where "thin" refers to a (small) dimension in a direction along the optical axis, e.g., less than <NUM>, such as less than <NUM>, such as less than <NUM>, such as [<NUM>; <NUM>] micrometer (i.e., within <NUM>-<NUM> micrometer). It may be made of any type of glass (such as glass with a Young's modulus within <NUM>-<NUM> GPa, such as within <NUM>-<NUM> GPa, such as within <NUM>-<NUM> GPa or within <NUM>-<NUM> GPa), such as borophosphosilicate glass (BPSG), such as any standard type of glass, or other material such as ceramic-glass, polymer, polymer-inorganic hybrid, such as being a so-called cover glass or being similar to a cover glass. These materials may in particular be relevant in embodiments where the bendable cover member should be transparent. By 'bendable' may be understood that an element, such as the bendable cover member, may be bent by the one or more actuators, i.e., actuation of the one or more actuators may bend the element. The 'bendable cover member' may be referred to interchangeably with "cover member".

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein the bendable cover member comprises, such as consists of, a material having a Young's modulus of at least <NUM> GPa, such as within <NUM>-<NUM> GPa, such as within <NUM>-<NUM> GPa, such as within <NUM>-<NUM> GPa or within <NUM>-<NUM> GPa. An advantage of this (such as a relatively rigid cover member) may be that it enables or facilitates that the one or more piezoelectric actuators are defining the optically active area, such as the aperture, while it is still possible to shape the cover member in the optically active area, such as the aperture (although no piezoelectric actuators are there) with the one or more piezoelectric actuators.

The bendable cover member may (in case of the optical element being an optical lens) be a bendable transparent cover member, and may more particularly.

This may for example be realized if the bendable transparent cover member is made of glass.

In an embodiment not covered by the subject matter of the claims, there is presented an optical element, wherein the bendable cover member extends beyond the inner edges of the sidewall. It is to be understood that the inner edges of the sidewall correspond to the surface of the sidewall, such as the surface of the sidewall facing the deformable lens body in the case of the optical element being an optical lens. In other words, the bendable cover member extends further away from the optical axis than the surface of the sidewall facing, such as the surface of the sidewall facing the optical axis (and optionally the deformable lens body).

'Actuators' are known in the art, and may for example be any one of thermal actuators, electrostatic actuators, magnetic actuators or piezoelectric actuators.

By 'arranged for shaping said bendable cover member into a desired shape', is understood that the shape, size and position of the actuators relative to the cover member enables them upon actuation, such as (in case of piezoelectric actuators) upon an applied voltage across their electrodes, to deform and thereby shape said bendable cover member into a desired shape. It is understood that at least a portion of the cover member is in the optically active area, such as the optical aperture, such as the portion of the cover member being intersected by the optical axis is being shaped into a desired shape.

By 'desired shape' may be understood that when going from a shape to a desired shape (such as from one desired shape to another desired shape), then the focal length of the optical element may change.

It may be possible to mitigate the stress singularity issue by arranging the supporting structure so that one or more of.

of the supporting structure on one side of the interface plane increases gradually and/or in a plurality of steps along at least a portion of a line being orthogonal to the optical axis and intersecting the optical axis and in a direction away from the optical axis, wherein said line spans a range from a point at an inner edge of the interface and a point more distantly placed with respect to the optical axis. By this arrangement, the "spring constant" (where "spring constant" is understood to be a constant k relating force F and displacement x, such as in Hooke's law, F = kx) of the supporting structure as seen by the bendable cover member, may vary from zero at the optical axis (where there may be no supporting structure) and increase gradually or in a plurality of steps in a direction away from the optical axis, such as at least from an inner edge of the interface between the cover member and the supporting structure. Thus, the variation in maximum reaction force between supporting structure and cover member may also increase gradually or in a plurality of steps in a direction away from the optical axis.

It is noted that the position of the line segment along which the thickness is measured is a line segment oriented outwards in a radial direction with respect to the optical axis and starting from a first point of contact between the supporting structure and the cover member, covering at least a portion of the supporting structure radially outside said first point of contact, and ending at a point more distantly placed with respect to the optical axis than said first point of contact. Said line segment may have a length being equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>. A thickness, such as a dimension in a direction parallel with the optical axis, of the supporting structure across said line segment may be equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>. In particular embodiments, both of a length of said line segment and a dimension of the supporting structure across said line segment may be equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>, such as equal to or less than <NUM>.

By 'a Young's modulus of the supporting structure' is understood a Young's modulus of the material of the supporting structure. By 'increases gradually and/or in a plurality of steps' may in terms of Young's modulus be understood an increase in relative terms, such as <NUM> % or more, <NUM> % or more, <NUM> % or more or <NUM> % or more larger.

By 'increases gradually and/or in a plurality of steps' may in terms of dimensions be understood an increase in absolute terms. Said increase may be <NUM> micrometer or more, such as <NUM> micrometer or more, such as <NUM> micrometer or more, such as <NUM> micrometer or more, such as <NUM> micrometer or more, such as <NUM> micrometer or more, such as <NUM> micrometer or more. Said increase may be <NUM> micrometer or less, such as <NUM> micrometer or less, such as <NUM> micrometer or less, such as <NUM> micrometer or less, such as <NUM> micrometer or less, such as <NUM> micrometer or less. In a specific embodiment, said increase is within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer.

A distance between the point at an inner edge of the interface and the point more distantly placed with respect to the optical axis may be <NUM> micrometer or more, such as <NUM> micrometer or more, such as <NUM> micrometer or more, such as <NUM> micrometer or more, such as <NUM> micrometer or more, such as <NUM> micrometer or more, such as <NUM> micrometer or more. A distance between the point at an inner edge of the interface and the point more distantly placed with respect to the optical axis may be <NUM> micrometer or less, such as <NUM> micrometer or less, such as <NUM> micrometer or less, such as <NUM> micrometer or less, such as <NUM> micrometer or less, such as <NUM> micrometer or less. In a specific embodiment, said distance is within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer.

In a still more specific embodiment, said increase in dimension in a direction being parallel with the optical axis is within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, and said distance is within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer. In a still more specific embodiment, said increase is within <NUM> micrometer to <NUM> micrometer and said distance is within <NUM> micrometer to <NUM> micrometer. In a still more specific embodiment, said increase is within <NUM> micrometer to <NUM> micrometer and said distance is within <NUM> micrometer to <NUM> micrometer.

It may be possible to mitigate the stress singularity issue by arranging the bendable cover member so that a dimension (such as thickness) of the bendable cover member in a direction being parallel with the optical axis is larger.

By this arrangement, the bendable cover member may experience an abrupt change in "spring constant" of the supporting structure, but it may be sufficiently thick at that abrupt change that it can handle it, but may simultaneously be thin enough at an area within the supporting structure that it can exhibit good optical and/or mechanical properties. The interface referred to above is the interface between the supporting structure and the bendable cover member as observed in the direction being parallel with the optical axis.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein the optical element does not comprise liquid. In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein the optical element is solid or gaseous, such as consists of solid or gaseous elements. In an embodiment not covered by the subject-matter of the claims there is presented an optical element,
wherein the optical element is solid, such as consists of solid elements.

The optical lens may in general be a micro lens, such as a tuneable micro lens. By 'micro lens' may in general be understood a lens wherein a dimensions of at least one structural component, such as the thickness (dimension in a direction parallel with the optical axis), is within the range <NUM> micrometer to <NUM> millimeter. In the present application, reference to thickness is a reference to geometrical thickness (as opposed to optical thickness). In an embodiment, the thickness may be the sum of the support structure (e.g., silicon), which may be <NUM>-<NUM> micrometer, the cover member and the one or more piezoelectric actuators including electrical contacts, which may be about <NUM> micrometer. The optical lens may be similar albeit not identical to (due to the claimed features) a tuneable micro lens known as a TLens® obtainable from the company poLight, Norway. The optical lens may in particular be a tuneable micro lens corresponding (albeit not identical) to the tuneable micro lens disclosed in the patent application <CIT>) with the title "Flexible lens assembly with variable focal length. It is additionally noted regarding the reference <CIT>) that certain dimensions may be converted from micrometers into millimeters, and in particular the dimensions referred to as d1PZT, d2PZT and wpol. (see for example figure 1c, subfigure I) on figure page <NUM>/<NUM>) may in realizations have the numerically same values albeit given in units in mm (millimeter) instead of µm (micrometer), more particularly: d1PZT = <NUM>, d2PZT = <NUM>, and wpol.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein a thickness of the optical element is equal to or less than <NUM>, such as equal to or less than <NUM> micrometer, such as equal to or less than <NUM> micrometer, such as equal to or less than <NUM> micrometer, such as equal to or less than <NUM> micrometer, such as equal to or less than <NUM> micrometer. A possible advantage of having a small thickness is that it enables an optical lens with a very small vertical footprint. This small vertical footprint may in turn optionally allow thinner optical devices, such as cameras, with smaller vertical footprint that can then be integrated into thinner devices, such as mobile phones, than presently allowed today. By 'thickness of the optical lens' may be understood the dimension of the optical length in a direction parallel with the optical axis (such as the distance between two planes being orthogonal with respect to the optical axis and being placed on either side of the optical lens).

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein the supporting structure comprises:.

A possible advantage of having a structural element adjoining the support element, and the bendable cover member may be that it renders it superfluous to provide a monolithic supporting structure, with the claimed features (which may be challenging). For example, it may be possible to provide a monolithic supporting structure in silicon with the claimed features, but it is challenging and may result in low yield. Introduction of a structural element as described may render it possible to provide in a simple and efficient manner a supporting structure with, e.g., an epoxy based structural element, wherein a dimension in a direction being parallel with the optical axis of the structural element (of the supporting structure) on one side of the interface plane increases gradually along at least a portion of a line being orthogonal to the optical axis and intersecting the optical axis and in a direction away from the optical axis. In an embodiment, said structural element has a first dimension in a direction being parallel with the optical axis within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer. In an embodiment said structural element has a second dimension in a radial direction with respect to the optical axis within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer. In an embodiment, a Young's modulus of said structural element is within <NUM>-<NUM> GPa, such as within <NUM>-<NUM> GPa, such as within <NUM>-<NUM> GPa, such as <NUM> GPa. In a still more specific embodiment, each of said first and second directions are within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, such as within <NUM> micrometer to <NUM> micrometer, and a Young's modulus is within <NUM>-<NUM> GPa, such as within <NUM>-<NUM> GPa, such as within <NUM>-<NUM> GPa, such as <NUM> GPa. In a still more specific embodiment each of said first and second directions are within <NUM> micrometer to <NUM> micrometer, and a Young's modulus of said structural element is within <NUM>-<NUM> GPa.

The structural element merely connects the support element with the bendable cover member and the structural element has an outer surface facing the optical axis. The outer surface extends from the support element to the bendable cover member and may be a plane surface or a curved surface such as an inwardly shaped or concave surface.

The material of the structural element may be selected among a plurality of materials. In embodiments the structural element material may be a polymer. In embodiments the structural element material may be an epoxy.

In embodiments the structural element may be organic reactive adhesives. For example, liquid structural element material, such as liquid organic/hybrid inorganic/organic adhesives that sets to a rigid cross-linked structure after curing, such as acrylics, polyurethanes, epoxies, polyimides, cyanoacrylates may be placed at the support element and/or the bendable cover member and the (solid) liquid structural element can then be formed via curing, such as wherein curing can be a thermally activated chemical crosslinking reaction, moisture activated curing, UV activated curing or a combination.

In embodiments filler material is added to the structural element material. Filler materials may be added to adhesives to obtain desirable properties, such as: Higher modulus, increased fracture resistance, better thermal stability, better mechanical strength or stability, or to modify flow properties in the uncured state. Filler materials can be in the form of particles, fibers, platelets and might be any kind of inorganic (or in some cases organic) minerals (oxides, nitrides, metals, glass, carbon). The filler materials may be anisotropic or isotropic (such as fibers vs spherical particles).

In embodiments the structural element comprises inorganic materials, such as sol-gels. There exists a number of materials that can have liquid-like properties before setting, and which through chemical/thermal processes becomes rigid, high modulus materials, such as materials which are typically denoted "sol-gel" systems. Some examples are: Nanoparticle ceramics dispersed in water or other liquid, which by a multi-step process of gelation, drying (to remove solvent) and sintering and maybe even a third crystallization step. Sol-gel techniques may be applied for producing thin films of ceramic materials (oxides, nitrides, carbides). In embodiment the structural element comprises, such as consists of, metals and/or ceramics. Metals and/or ceramics may be applied via sputtering (such as via physical vapour deposition (PVD)) with proper masking.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein a dimension (such as thickness) of the supporting structure, such as of the structural element, in a direction being parallel with an optical axis of the optical element increases gradually and/or in a plurality of steps along a line orthogonal to the optical axis from the optical axis and away from the optical axis. A possible advantage of this may be that it enables that the Young's modulus of the supporting structure can be kept constant, because the increase in thickness may be utilized to increase gradually and/or in a plurality of steps the spring constant of the supporting structure, so that the stress singularity issue is reduced or eliminated.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein the optical element endures an acceleration and/or deceleration of at least <NUM> (five thousand) g, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, in a direction parallel with the optical axis, such as an acceleration in a negative direction (i.e., in a direction parallel to the optical axis from the cover member to the supporting structure, which would correspond to an impact on a drop where the cover member is facing in a direction of gravity) and/or a positive direction. By 'endures' may in this context be understood that any one or more or all of the parameters given by.

shall after the acceleration and/or deceleration remain within an interval given by [<NUM>; <NUM>] % (such as ± <NUM> %) with respect to the value of said parameter before the acceleration and/or deceleration.

The endurable acceleration is achieved at least partially by means of the support structure, particularly due to the gradually or stepwise increasing thickness and/or Young's modulus. The acceleration specification may be achieved by various designs of the support structure which can be designed with different dimensions of the part with increasing thickness and/or Young's modulus, different Young's modulus values and different shapes.

In an embodiment not covered by the subject-matter of the claims (such as an embodiment with a support element and a structural element) there is presented an optical element, wherein the structural element is placed adjacent, such as adjoining, a sub-interface between the support element and the bendable cover member, such as at a side of said sub-interface facing the optical axis. A possible advantage of this (such as having the structural element in the corner where a supporting structure with a sidewall parallel or substantially parallel with the optical axis and facing the optical axis meets the cover member being orthogonal to the optical axis or being placed between the support element and the cover member and extending further towards the optical axis than the support element) may be that this is a position where the structural element may aid in mitigating the stress singularity issue. The prefix 'sub' (in 'sub-interface) may be understood to denote that since the supporting structure has an interface with the cover member, the structural element (being a part of the supporting structure) can only have a sub-interface of this interface.

In an embodiment not covered by the subject-matter of the claims (such as an embodiment with a support element and a structural element) there is presented an optical element, wherein some or all of the structural element is placed and/or extends further towards the optical axis than the support element, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM>, such as at least <NUM> further towards the optical axis than then support element. A possible advantage of this may be that this is a position where the structural element may aid in mitigating the stress singularity issue.

In an embodiment not covered by the subject-matter of the claims (such as an embodiment with a support element and a structural element) there is presented an optical element, wherein the structural element is encircling, such as completely (<NUM> degrees) encircling, an optical axis of the optical element. A possible advantage of this may be that it enables that the stress singularity issue is mitigated or overcome all around the optical axis.

In an embodiment not covered by the subject-matter of the claims (such as an embodiment with a support element and a structural element) there is presented an optical element, wherein a material of the structural element is different from.

In a particular embodiment, the material of the structural element (such as epoxy) is different from both the material of the support element (such as silicon) and the material of the bendable cover member (such as glass). In an alternative embodiment, a material of the structural element is different from a material of the support element or a material of the bendable cover member.

In an embodiment not covered by the subject-matter of the claims (such as an embodiment with a support element and a structural element) there is presented an optical element, wherein the structural element comprises, such as consists of, a polymer.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein the structural element comprises, such as consists of, epoxy.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein a surface of the structural element as observed from an optical axis of the optical element is concave. Thus, the concavity is seen when observed from the optical axis and towards the concave surface, either along a direction perpendicular to the optical axis or a direction which makes an acute angle with the optical axis. A possible advantage of this may be that it can be realized by wetting and/or capillary forces. Another possible advantage may be that it facilitates good mechanical properties, such as low stress concentration factors in the bendable cover member during impact at the inner sidewall of the supporting structure and at the inner edge of the structural element.

In general the improved mechanical properties which improves impact resistance are not only obtained with a concave surface of the structural element, but may be achieved with any curved surface or plane surface (according to the first aspect) as long as the thickness of the support structure in the direction of the optical axis changes gradually or stepwise from a low thickness where this part of the support structure is closest to the optical axis to a larger highest thickness at the sidewall of the supporting structure. The gradually increasing thickness could affect light transmitted through the gradually varying thickness to generate imaging distorting of the lens embodied by the optical element. However, as long as the lens does not receive light transmitted through the gradually increasing thickness, the effect of the supporting structure with the gradually increasing thickness is irrelevant.

Furthermore, the optical aperture <NUM> (<FIG>) is restricted by the inner edge of the piezoelectric actuator (layers <NUM>, <NUM>, <NUM>). Light only goes through the aperture. Therefore, as long as the supporting structure is located beneath the piezoelectric actuator it does not matter if it is transparent or not.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein a diameter of
an optically active area is <NUM> or less, such as <NUM> or less, such as <NUM> or less (such as [<NUM>; <NUM>] mm), such as <NUM> or less (such as [<NUM>-<NUM>] mm), such as <NUM> or less, such as <NUM> or less, such as <NUM> or less. A possible advantage of having a small diameter is that it enables providing an optical lens, which may utilise very little area in a final application device (such as a camera) and/or where the small size facilitates that it can be installed in multiple positions for additional functionality (e.g. 3D imaging). By 'optically active area' may be understood an area upon which light may be incident and may be manipulated. For an optical lens the optically active area may correspond to (such as be identical to) the optical aperture. For a reflective element, such as a mirror, the optically active area may be a reflective area upon which light may be incident and from which manipulated light may be reflected (such as analogously to an aperture for an optical lens).

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein a diameter of
the optically active area is <NUM> or more, such as <NUM> or more, such as <NUM> or more, such as <NUM> or more, such as <NUM> or more. A possible advantage of having a large diameter is that it enables providing a large amount of light.

The optical element may further comprise at least one deformable transparent lens body attached to the bendable cover member. This may in particular be relevant, if the optical element is a refractive optical element, such as a lens, such as a tunable lens. In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein the optical element is a refractive lens comprising:.

and wherein the bendable cover member is a bendable transparent cover member which is attached to.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element being an optical lens,
wherein said at least one deformable transparent lens body comprises polymer, such as solid polymer, such as a deformable transparent lens body consisting of solid polymer. By said at least one deformable transparent lens body comprises polymer, such as solid polymer, may be understood that said at least one deformable transparent lens body comprises at least <NUM> wt% (weight percent), such as at least <NUM> wt%, such as at least <NUM> wt%, such as at least <NUM> wt%, solid polymer. In an embodiment there is presented an optical element being an optical lens, wherein said at least one deformable transparent lens body comprises a polymer network of cross-linked or partly cross-linked polymers and a miscible oil or combination of oils. In an embodiment there is presented an optical element being an optical lens, wherein said at least one deformable transparent lens body may have an elastic modulus larger than <NUM> Pa, a refractive index is above <NUM>, and an absorbance in the visible range less than <NUM> % per millimeter thickness.

'Refractive lens' is known in the art and understood accordingly. An advantage of refractive lenses may be that they require only low maintenance and generally do not require collimation or recoating to the same extent as reflective elements.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein said optical element comprises one or more actuators for deforming (such as directly deforming) or shaping the bendable cover member, wherein the one or more actuators and the bendable cover member are arranged so that the one or more actuators upon actuation are capable of deforming or shaping the bendable cover member throughout a range of <NUM> dioptres or more, such as throughout a range of <NUM> dioptres or more, such as throughout a range of <NUM> dioptres or more, such as throughout a range of <NUM> dioptres or more, such as throughout a range of [-<NUM>; +<NUM>] dioptres or more), such as throughout a range of <NUM> dioptres or more, such as <NUM> dioptres or more, such as <NUM> dioptres or more, such as <NUM> dioptres or more, such as through a range of [-<NUM>; +<NUM>] dioptres or more, such as throughout a range of <NUM> dioptres, such as throughout a range of <NUM> dioptres or more (such as [-<NUM>; +<NUM>] dioptres or more), such as throughout a range of <NUM> dioptres or more, (such as [-<NUM>; +<NUM>] dioptres or more). It may in general be understood, that the range spanned may include a magnification of <NUM> dioptres or more, such as a range spanning <NUM>-<NUM> dioptres or more, such as <NUM>-<NUM> dioptres or more, such as <NUM>-<NUM> dioptres or more, such as <NUM>-<NUM> dioptres or more, such as <NUM>-<NUM> dioptres or more, such as <NUM>-<NUM> dioptres or more, such as <NUM>-<NUM> dioptres or more, such as <NUM>-<NUM> dioptres or more, such as throughout a range of <NUM> dioptres or more, such as throughout a range of <NUM> dioptres or more (such as [-<NUM>; +<NUM>] dioptres or more), such as throughout a range of <NUM> dioptres or more (such as [-<NUM>; +<NUM>] dioptres or more). The range spanned may include a magnification of <NUM> dioptres and a range on both sides of zero, such as a range from/to ±<NUM> dioptres or more( i.e., from - <NUM> dioptres to <NUM> dioptres or more), such as ±<NUM> dioptres or more, such as ±<NUM> dioptres or more, such as ±<NUM> dioptres or more, such as ±<NUM> dioptres or more, such as ±<NUM> dioptres or more, such as ±<NUM> dioptres or more, such as ±<NUM> dioptres or more, such as [-<NUM>; +<NUM>] dioptres or more, such as [-<NUM>; +<NUM>] dioptres or more.

By 'directly' (deforming) may be understood, that the one or more actuators are arranged with respect to the bendable cover member, so that the deformation of the bendable cover member is not dependent on a third element.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein:.

An advantage of a high transmittance may be that it facilitates that less light is lost when travelling through the optical device element. In general embodiments, said optical lens, has an average transmittance of <NUM> % or more, such as <NUM> % or more, such as <NUM> % or more, such as <NUM> % or more.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein the optical element is a reflective element, and wherein the bendable cover member is reflective on the side facing away from the supporting structure and/or on the side facing the supporting structure. By 'reflective element' may be understood an element which reflects incident electromagnetic radiation, such as a mirror. By 'reflective' may be understood that the average (within a wavelength range and within the angle of incidence range) reflectivity is at least <NUM> %, such as at least <NUM> %, such as at least <NUM> %, such as at least <NUM> %. An advantage of reflective elements may be that they may suffer less from chromatic aberration compared to refractive optical elements. Another advantage of reflective elements may be that they can be relatively lighter than refractive optical components.

In an embodiment not covered by the subject-matter of the claims there is presented an optical element, wherein a total wavefront error (WFERMS) is equal to or less than <NUM>, such as <NUM>, such as <NUM>, such as <NUM>, such as <NUM>, throughout a range of <NUM> dioptres or more, such as throughout a range of <NUM> dioptres or more, such as throughout a range of <NUM> dioptres or more, such as throughout a range of <NUM> dioptres or more, such as throughout a range of [-<NUM>; +<NUM>] dioptres or more), such as throughout a range of <NUM> dioptres or more, such as throughout a range of <NUM> dioptres or more. In a particular embodiment there is presented an optical element, wherein a total wavefront error (WFERMS) is equal to or less than <NUM> throughout a range of <NUM> dioptres or more. In a particular embodiment there is presented an optical element, wherein a total wavefront error (WFERMS) is equal to or less than <NUM> throughout a range of <NUM> dioptres. By having total WFERMS being lower than a threshold throughout a range of another parameter, such as dioptres, it may be understood that the total WFERMS is lower than the threshold for any value of the other parameter in the given range. A possible advantage of this embodiment may be that an improved image quality may be achieved throughout a range of dioptres and/or focal lengths. By 'total wavefront error (WFERMS)' is understood the total root-mean-square (RMS) wavefront error (WFERMS), which is commonly known in the art and understood accordingly. The total wavefront error (WFE) is defined for a given conjugation (object and image points). The wavefront error is defined for each point of the light beam. It is the optical path difference (OPD), such as the discrepancy in optical path lengths (OPL), between the actual (aberrated) wavefront and a perfect spherical wavefront. It is a distance usually expressed in nanometer (nm) or micrometer (µm). The total WFERMS is defined for a given conjugation (object and image points). It is the root mean square of the total WFE over a cross section of the light beam on the surface on which it is calculated, such as described in the formula below: <MAT>.

The integral is made across the area A of the cross section of the output pupil of the system. The total WFERMS is a single value. It is a distance, usually expressed in nanometer (nm) or micrometer (µm). Measurement of total WFERMS may be carried out using a wavefront measurement system with the Shack-Hartmann sensor, such as HASO™ from the company Imagine Optic (with headquarter address in Orsay, France). In an embodiment there is presented an optical element, wherein the total wavefront error (WFERMS) is measured at <NUM>, such as at a wavelength of <NUM> and at an angle of incidence of <NUM>°.

According to the invention, the Young's modulus of the supporting structure is less than the Young's modulus of the bendable cover member. For example, the supporting structure may comprise or consists of an adhesive like Epoxy which after being solidified, e.g. with a heating or UV curing process, has a Young's modulus value in the range of <NUM> - <NUM> GPa, such as <NUM> GPa. In comparison the bendable cover member, e.g. made of glass, may have a Young's modulus in the range from <NUM>-<NUM> GPa. For example, Young's modulus for borosilicate glass is <NUM> GPa, <NUM> GPa for fused silica glass and <NUM> GPa for borophosphosilicate glass. Advantageously, a supporting structure with a relative higher elasticity (i.e. lower Young's modulus) may be easier to attach in a reliable way to the cover member and the sidewall of the supporting structure.

In an embodiment, the plurality of steps comprise at least <NUM> steps.

Advantageously, the stepped surface of the support structure approximates a support structure with a continuous structure with respect to it's mechanical properties.

In an embodiment, at least a portion of the supporting structure of which the dimension in the direction being parallel with the optical axis, and/or the Young's modulus increases gradually and/or in a plurality of steps is located separated from the at least one deformable transparent lens body.

The portion of the supporting structure of which the dimension in the direction being parallel with the optical axis, and/or the Young's modulus increases, such as the structural element, may be placed with a radial separation between the part of the structural element closest to optical axis and the part of the lens body being most distant from the optical axis. Thus, the structural element may circumscribe the lens body so that at no point along the circumference of the structural element there is direct contact between the structural element or the supporting structure and the lens body.

Advantageously, the placement of the structural element distanced from the lens body ensures that the structural element does not interfere with the light propagation in the lens body. Furthermore, due to the non-contact between the structural element or said portion of the supporting structure and the lens body, the lens body is not exposed to deformations or stresses due to deformations of the structural element.

In an example, the structural element or said portion of the supporting structure may be separated from the at least one deformable transparent lens body at least so that the portion of the structural element being closest to the optical axis does not extend into lens body. Thus, a minimal distance of substantially zero, e.g. a few micro meters may be allowed.

A second aspect relates to a method for providing the optical element according to the first aspect.

In an embodiment of the second aspect, the method is for improving impact resistance of the bendable cover member of the optical element.

In an embodiment of the second aspect, there is presented a method for manufacturing an optical element according to the first aspect and more particularly any embodiment of the first aspect wherein the supporting structure comprises:.

said method comprising placing a liquid structural element material at.

such as said method comprising placing a liquid structural element material at the inner edge of the interface between the support element and the bendable cover membrane, so as to form the structural element.

For obtaining the structural element a solidifying process such as a curing process may be applied to achieve the desired mechanical properties of the liquid structural element material.

An advantage of this method may be that it is relatively simple to place a liquid material at said position(s). Another possible advantage may be that wetting and/or capillary forces may be utilized for redistribution of said liquid, which may be helpful in providing a relatively simple, yet efficient way in obtaining the claimed optical element. For the structural element being epoxy (such as cured epoxy in the optical lens), liquid structural material may be uncured epoxy resins. A possible advantage of placing the liquid structural element material at the inner edge of the interface between the support element and the bendable cover membrane may be that it is then placed (from the start) at the interface from which position wetting and/or capillary forces may (more easily) be utilized for redistribution of said liquid.

In an embodiment not covered by the subject-matter of the claims there is presented a method, wherein the liquid structural element material is redistributed via adhesive forces between the liquid structural element and.

beyond the position where it is placed, such as along an inner edge of the interface between the support element and the bendable cover member, such as the liquid structural element material is redistributed over a distance of at least <NUM> micrometer, such as at least <NUM> micrometer, such as at least <NUM> micrometer, such as at least <NUM> micrometer, via the adhesive forces.

A possible advantage of the redistributed via said adhesive forces may be that it facilitates providing or ensures an even distribution of the liquid structural element. Another possible advantage may be that the redistribution is carried out by itself. Another possible advantage may be that the redistribution can be controlled by controlling the surfaces of the supporting structure and/or the bendable cover member. By 'redistribution via adhesive forces' may be understood wetting and/or capillary forces.

so as to encircle, such as completely (<NUM> degrees) encircle, an optical axis of the optical element.

In an embodiment not covered by the subject-matter of the claims there is presented a method, wherein the method further comprises solidifying the liquid structural element material, such as thereby forming the structural element.

The solidifying of the liquid structural element material may comprise a curing process of the liquid structural element after its redistribution along the bendable cover.

According to a third aspect, there is provided a camera comprising.

It is understood that the optical element is a part of the camera. The optical element may be integrated with the camera, i.e. the camera without the optical element or the remainder of the camera, via the supporting structure so that the supporting structure is attached, e.g. glued, to a part of the camera. In this way, the bendable cover member is attached to the camera.

In a more general embodiment, there is provided an optical device comprising.

wherein the optical device may be any one optical device chosen from the group comprising, such as consisting of: a scanner, a camera, a variable optical tuner or attenuator, an iris, an optical image stabilisation (OIS) unit, a zoom lens, a wide angle lens, bar code reader, endoscope, projector or any device in which light is organised to create a desired effect (e.g. imaging).

According to a fourth aspect not according to the invention, there is provided use of.

The optical element, method and optical device according to the invention will now be described in more detail with regard to the accompanying figures.

In general, when a direction is implied, such as when using the terms 'above' or 'below' or 'top' or 'bottom', it is in general understood that a positive direction is defined in a direction parallel to the optical axis from the supporting structure to the cover member. For example, the cover member is above the supporting structure such as on top of the supporting structure. Furthermore, 'inner' generally refers to a part of an element, such as a side or an end of an element, facing the optical axis, such as the element having an 'inner' side or end facing the optical axis and an 'outer' side or end facing away from the optical axis. Similarly, 'internal' (for example 'internal sidewall') refers to generally refers to a part of an element, such as a side or an end of an element, facing the optical axis, such as the element having an 'internal sidewall' facing the optical axis and an 'external sidewall' facing away from the optical axis.

<FIG> is a perspective drawing of an optical element not covered by the subject-matter of the claims, and more particularly an optical lens, more particularly a supporting structure <NUM> which has a thickness <NUM> in the range <NUM>-<NUM> micrometer. The supporting structure has an internal sidewall <NUM> facing the optical axis <NUM>. The figure furthermore shows a bendable transparent cover member <NUM> (which in the present embodiment is glass), a bottom electrode <NUM> for the one or more actuators (which are piezoelectric actuators), a piezoelectrically active material <NUM>, a top electrode <NUM> (for the one or more piezoelectric actuators). The supporting structure comprises a support element <NUM>, where the support element <NUM> being a silicon element, and a structural element <NUM>, where the structural element <NUM> is an epoxy element. All of the structural element <NUM> is placed closer to the optical axis than the support element <NUM>, and the structural element <NUM> is adjoining both the support element <NUM>, and the bendable cover member <NUM>. The support element <NUM> has a width <NUM> in the range <NUM>-<NUM> micrometer. It may be understood, that the position of the one or more piezoelectric actuators as observed in a top-view (along a direction parallel with the optical axis) is defined as positions wherein there is an overlap between all of the bottom electrode <NUM>, the piezoelectrically active layer <NUM> and the top electrode <NUM> (note that only in these positions can the piezoelectrically active layer be actuated). The figure furthermore shows a transparent deformable lens body <NUM> (which in the present embodiment is a polymer), a transparent back window <NUM> (attached to the lens body <NUM>), a cavity <NUM> inside the supporting structure <NUM> (which cavity <NUM> comprises the optical axis <NUM> and is bounded in a direction away from the optical axis <NUM> by the sidewall <NUM>), an inner edge <NUM> of the supporting structure <NUM> (at the interface between the supporting structure <NUM> and the bendable transparent cover member <NUM>) projected to the surface of the bottom electrode <NUM> or to the surface of the top electrode <NUM>. In the presently shown embodiment, it can be seen that an outer edge of the one or more piezoelectric actuators <NUM>, <NUM>, <NUM> (which in the present embodiment is a single piezolectric actuator which may be defined as the area where all of the bottom electrode <NUM>, piezoelectrically active material <NUM> and top electrode <NUM> are overlapping as observed in a direction being parallel with the optical axis) forms a closed ring completely encircling the optical axis <NUM> and optical aperture <NUM>).

<FIG> is a side-view of an optical element not covered by the subject-matter of the claims similar to the optical element in <FIG> furthermore displays a moulded package <NUM>, a soft object side cap ("blacksheet") <NUM>, and an adhesive <NUM>. The figure furthermore shows an insert <NUM> with a microscopy image (from a scanning electron microscope (SEM)) of cross-sectional view of a structural element <NUM>, which is an epoxy, which has been placed in the corner between cover member <NUM> (glass) and support element <NUM> (silicon) via wetting and/or capillary forces. Both the schematic part of <FIG> and the insert in <FIG> shows the rounded part of the structural element (i.e., the part which is not adjoining neither cover member <NUM> nor support element <NUM>).

<FIG> is a microscope image of a bottom view of an optical element not covered by the subject-matter of the claims during a method of manufacturing, more particularly during providing a structural element. The figure shows a bottom view, i.e., as observed from a point in the optical axis from the bottom (i.e., below the optical element in <FIG>). The figure shows a liquid structural element material <NUM> at the bendable cover member <NUM>. The liquid structural element material is applied so that it touches the inner edge of the interface between cover member <NUM> and support element <NUM>. The liquid structural element material <NUM> may from its presently shown droplet form be redistributed via adhesive forces between on the one side the liquid structural element and on the other side the support element <NUM> and the bendable cover member <NUM>. More particularly, it may be drawn around the inner edge interface between cover member <NUM> and support element <NUM> and thus be redistributed to be positioned around the entire sidewall of the support element <NUM> and fill the corner between the support element <NUM> and the cover member <NUM> so as to completely (<NUM> degrees) encircle the optical axis (being orthogonal to the plane of the paper and centred in the black circle in the middle of the image) of the optical element.

<FIG> shows a microscope (SEM) image of a perspective view from a backside of an optical element not covered by the subject-matter of the claims as schematically shown in <FIG>. The structural element <NUM> can be seen in the corner between cover member <NUM> and (inner sidewall of the) support element <NUM>.

In the specific embodiment of <FIG>, a two-component epoxy with a viscosity around <NUM> cPs (centipoise) and a storage modulus after curing of <NUM> GPa was used (these data being according to information from the producer datasheet, where the specific Epoxy used is "EPO-TEK® 353ND from the company Epoxy Technology, Inc. , Billerica, US). Approximately <NUM>µl (<NUM>/<NUM> microliter) of the liquid structural element material <NUM> (such as the structural element <NUM> Epoxy material pre-curing) was dispensed using standard dispensing equipment with a small syringe tip. The droplet of liquid structural element material <NUM> was placed onto the bendable membrane <NUM> (being a glass membrane) inside the cavity, such as encircled by the support element <NUM>. After a short time, the liquid droplet spreads and touches the internal sidewall of the support element <NUM> (cf. , internal sidewall <NUM> in <FIG>) facing the optical axis <NUM>, which in the present embodiment is a silicon wall, and quickly starts to flow around the inner edge of the the internal sidewall of the support element <NUM>, such as around the optical axis at the inner edge of the interface between the bendable cover member <NUM> and the support element <NUM>, by capillary forces. The liquid structural element material <NUM> is thus redistributed via adhesive forces between the liquid structural element and.

The optical element with the liquid structural element material <NUM>, such as the liquid epoxy, was then placed in an oven for curing at <NUM> for <NUM> hours.

After curing, a uniformly shaped ring of the hardened epoxy had been formed. The width (i.e., dimension in a direction being orthogonal to the optical axis) of the structural element, such as the epoxy ring, was measured to be approximately <NUM>-<NUM> (micrometer).

Several samples were prepared following the same procedure, and were further used for assembly as optical elements, such as tunable optical lenses. The optical performance of the lenses was subsequently characterized, all showed excellent performance. Further, the lenses were mounted in jigs and drop tests carried out according to normal practice for mobile phone camera modules. <NUM> % of these optical lenses were found to pass drop from <NUM>.

<FIG> illustrates a simulation model of the optical element. The illustration in the upper portion of the figure shows half of the optical element upside down (with respect to, e.g., <FIG>), but otherwise the reference signs corresponds to corresponding elements, more particularly optical axis <NUM>, cover member <NUM>, support element <NUM>, the structural element <NUM>, transparent deformable lens body <NUM>, transparent back window <NUM> and moulded package <NUM>. There is also shown a package glue <NUM>. The simulation corresponds to a drop test for a simplified axisymmetric model. The drop height was h=<NUM>. The bendable cover member <NUM> comprises, such as consists of, borophosphosilicate glass (BPSG) with a thickness (dimension parallel with the optical axis) of <NUM>, covered with the PZT film (<NUM> thick) and Si3N4 film (<NUM> thick). Both PZT and Si3N4 films had a round hole in the centre of <NUM> diameter (the aperture). Stress in the Si<NUM>N<NUM> film was adjusted to -<NUM> MPa to obtain the offset -<NUM> dpt (where 'dpt' is an abbreviation of dioptres). The double arrow indicating half the diameter R = ½*<NUM> (i.e., the radius R=<NUM>*<NUM>) of the optical aperture covers the distance from the optical axis in the left side to the opaque piezo-film in the right side. Arrow <NUM> indicates velocity (i.e., direction) at the impact. Velocity at the boundary <NUM> indicated with a thick dashed line was changed from Vmax=<NUM>/s to <NUM>/s during impact time. The zoom in the lower part of the figure shows some of the same elements as in the upper part of the figure and additionally indicates dimensions in micrometers. It is in particular noted, that simulations are carried out for three different dimensions of the structural element <NUM>, where the edges <NUM> are shown. More particularly, the following dimensions of the epoxy cross-section were simulated: <NUM> x <NUM>, <NUM> x <NUM>, <NUM> x <NUM>. The piezoelectric material is lead zirconate titanate (PZT). The structural element <NUM> is epoxy. The dotted line <NUM> indicates a line for which the stress is calculated in the cover member (see <FIG>), which line is <NUM> from the side facing the polymer lens body, the epoxy structural element and the support element.

<FIG> shows a figure illustrating the stress singularity issue, i.e., that the abrupt change in mechanical properties at the interface between the support element <NUM> and structural element <NUM> results in a peak stress value (with maximum σmax) in the bendable cover member upon impact (which is substantially above a reference value σref. The graph shows Von Mises Stress (in units of MPa) on the y-axis (which spans <NUM>-<NUM> MPa) and the spatial coordinate from the optical axis and spans <NUM> to <NUM> from left to right. The stress is shown for a line in the cover member <NUM> from the side facing the polymer lens body, the epoxy structural element and the support element (see line <NUM> in <FIG>).

<FIG> show simulation results corresponding to the simulation model described in <FIG>. The x-axis shows Young's modulus of the epoxy structural element <NUM> at the cavity inner edge (in gigapascal (GPa)) on a logarithmic scale from <NUM> to <NUM> GPa (in <FIG>) or from <NUM> to <NUM> GPa (in <FIG>). In all curves in <FIG>, the Young's modulus value of <NUM> GPa (which is a realistic value for, e.g., epoxy) is indicated with a vertical dotted line.

<FIG> shows the peak stress σmax at the cavity edge, i.e., the stress in the bendable cover member <NUM> above the lower surface of the bendable cover member (i.e., above the surface facing the support element) at the position of the edge of the support element facing the optical axis (σmax in <FIG>). The y-axis shows peak stress (in megapascal (MPa)). The figure shows that the peak stress can be reduced and the amount of reduction increases with increasing dimensions of the epoxy structural element and with the Young's modulus of the epoxy structural element (for the values shown). The graph shows that peak stress in the cover member (glass) at the cavity edge (sidewall) can be substantially or completely suppressed for the Young's modulus of glue E=<NUM> GPa. The stress concentration factor can also be reduced by several times.

In each of <FIG>, there are three curves which correspond to, respectively, dimensions of the structural element of <NUM> x <NUM> (dotted curve with open circle markers), <NUM> x <NUM> (dashed curve with filled circle markers), <NUM> x <NUM> (full drawn curve with closed circle markers).

<FIG> have a y-axis showing optical power (OP) in units of dioptres (dpt).

<FIG> shows the optical power (OP) as a function of Young's modulus (Ym) for an applied (realistic) voltage across piezoelectric actuators of <NUM> volts.

<FIG> shows the optical power difference corresponding to the voltage difference <NUM>-<NUM> V as a function of Young's modulus. It can be seen that optical power span of <NUM> dioptres or more are achieved for all the shown configurations.

<FIG> have an y-axis showing root-mean-square wavefront error (RMSWFE) in nanometers (nm). <FIG> shows root-mean-square wavefront error as a function of Young's modulus of the structural element. It can be seen that said root-mean-square wavefront error is kept at or below <NUM> for all configurations shown and may even be kept below <NUM> for all dimensions for sufficiently low Young's modulus values and for the smallest shown dimension throughout the shown Young's modulus range.

<FIG> show alternative embodiments not covered by the subject-matter of the claims where the supporting structure is made of silicon. It may be seen that whereas <FIG> related to an optical element with a supporting structure comprising a support element <NUM> of silicon (Si) and a structural element <NUM> of another material (such as epoxy), each of the embodiments of <FIG> comprises a supporting structure where a first (main) portion <NUM>, <NUM>, <NUM> corresponds to the support element of the embodiments of <FIG> and a second (protruding) portion <NUM>, <NUM>, <NUM> corresponds to the structural elements of the embodiments of <FIG> and where each of the first portion and the second portion are made of the same material (silicon), optionally in a monolithic structure. Each of <FIG> discloses a supporting structure with a main portion <NUM>, <NUM>, <NUM> on the right hand side of silicon (Si) and a protruding portion <NUM>, <NUM>, <NUM> on the left hand side of silicon (Si). The protruding portion in each of <FIG> have widths w (dimension in radial direction, i.e., orthogonal to optical axis) of <NUM> (which in other embodiments is <NUM>) and thicknesses d (dimension in parallel to optical axis) of <NUM>, <NUM>, <NUM>, <NUM> or <NUM>. The figures also show a cover member of borophosphosilicate glass (BPSG) which is <NUM> thick. On top of the cover member there is placed a <NUM> thick layer of the piezoelectric material is lead zirconate titanate (PZT) and on top of that there is placed <NUM> Si<NUM>N<NUM> with hole of <NUM> diameter in both.

In <FIG> the second (protruding) portion <NUM> has in a cross-sectional plane comprising the optical axis a substantially rectangular shape, such as a shape corresponding to a rectangle with a rounded corner (where the rounded corner is the corner facing away from both the first (main) portion <NUM> and the cover member <NUM>). In alternative embodiments, the material of the second (protruding) portion <NUM> could be other materials than silicon, it could for example be SiO<NUM>. In alternative embodiments, the material of the second (protruding) portion <NUM> could be similar to a material placed between the first (main) portion <NUM> and the cover member <NUM>.

In <FIG> the second (protruding) portion <NUM> has in a cross-sectional plane comprising the optical axis a substantially triangular shape, such as a triangular shape, such as a shape with straight sides parallel with a side of the first (main) portion <NUM> and a side of the cover member <NUM> and a (last) straight side.

In <FIG> the second (protruding) portion <NUM> has in a cross-sectional plane comprising the optical axis a substantially triangular shape albeit with one curved side, such as a shape with straight sides parallel with a side of the first (main) portion <NUM> and a side of the cover member <NUM> and a (last) side being curved, such as being concave as observed from outside the triangle.

An embodiment according to <FIG> which is not covered by the subject-matter of the claims can be manufactured by standard bulk micromachining techniques with two-step deep dry silicon etching from the back side of the wafer.

Embodiments according to <FIG> which are not covered by the subject-matter of the claims can be manufactured by standard bulk micromachining techniques with two-step back side silicon etching. A first deep dry silicon etching step is used to remove the main part of the bulk silicon. In case of the embodiment shown in <FIG>, this first deep dry silicon etching step is followed by anisotropic wet etching, which removes silicon preferentially in the <<NUM>> plane and produces the characteristic sloped sidewalls shown in <FIG>. In case of the embodiment shown in <FIG>, the first deep dry silicon etching step is followed by isotropic etching, either wet or dry, which produces the rounded profile shown in <FIG>.

<FIG> shows simulation results for three simulation models corresponding to <FIG>. The x-axis shows thickness d of the second (protruding) portions <NUM>, <NUM>, <NUM> in micrometer (µm). The y-axis shows stress in megapascal (MPa). The three curves <NUM>, <NUM>, <NUM> which on the right hand side are on the top represent (from the top) peak stress in the cover member <NUM> (cf. , σmax in <FIG>) at a position above the interface between first (main) portion <NUM> and second (protruding) portion <NUM> (curve <NUM>), peak stress in the cover member <NUM> (cf. , σmax in <FIG>) at a position above the interface between first (main) portion <NUM> and second (protruding) portion <NUM> (curve <NUM>) and peak stress in the cover member <NUM> (cf. , σmax in <FIG>) at a position above the interface between first (main) portion <NUM> and second (protruding) portion <NUM> (curve <NUM>). The three curves <NUM>, <NUM>, <NUM> which on the left hand side are on the top represent peak stress in the cover member <NUM>, <NUM>, <NUM> at a position above a point of the second (protruding) portion <NUM>, <NUM>, <NUM>, which is closest to the optical axis (i.e., the most left hand point of the second (protruding) portion <NUM>, <NUM>, <NUM> in <FIG>). These curves <NUM>, <NUM>, <NUM> go towards <NUM> MPa for thickness d going towards zero (µm). The little inserted figures with shapes corresponding to the shape of the structural element, which the curves represent, have a little star indicating the position of the peak stress.

<FIG> comprises a legend of the curves of <FIG>, <FIG>. The legend of <FIG> also applies to <FIG> when the Si residues is replaced with Epoxy material for the structural element <NUM>.

<FIG> shows simulation results similar to <FIG> for three simulation models corresponding to <FIG> albeit where widths d of the second (protruding) portions <NUM>, <NUM>, <NUM> are <NUM>. The three curves <NUM>, <NUM>, <NUM> which on the right hand side are on the top represent (from the top) peak stress in the cover member <NUM> (cf. , <FIG>) at a position above the interface between first (main) portion <NUM> and second (protruding) portion <NUM> (curve <NUM>), peak stress in the cover member <NUM> (cf. , <FIG>) at a position above the interface between first (main) portion <NUM> and second (protruding) portion <NUM> (curve <NUM>) and peak stress in the cover member <NUM> (cf. , <FIG>) at a position above the interface between first (main) portion <NUM> and second (protruding) portion <NUM> (curve <NUM>). The three curves <NUM>, <NUM>, <NUM> which on the left hand side are on the top represent peak stress in the cover member <NUM>, <NUM>, <NUM> at a position above a point of the second (protruding) portion <NUM>, <NUM>, <NUM>, which is closest to the optical axis (i.e., the most left hand point of the second (protruding) portion <NUM>, <NUM>, <NUM> in <FIG>). These curves <NUM>, <NUM>, <NUM> go towards <NUM> MPa for thickness d going towards zero (µm). The little inserted figures with shapes corresponding to the shape of the structural element, which the curves represent, have a little star indicating the position of the peak stress.

<FIG> shows simulation results similar to <FIG> and <FIG> for three simulation models corresponding to <FIG> albeit where widths d of the second (protruding) portions <NUM>, <NUM>, <NUM> are <NUM>, and where the structural element <NUM>, i.e. the (protruding) portions <NUM>, <NUM>, <NUM> are made from cured Epoxy. The three curves <NUM>, <NUM>, <NUM> which on the right hand side have the maximum stress values represent (from the top) peak stress in the cover member <NUM> (cf. , σmax in <FIG>) at a position above the interface between first (main) portion <NUM> and second (protruding) portion <NUM> (curve <NUM>), peak stress in the cover member <NUM> (cf. , σmax in <FIG>) at a position above the interface between first (main) portion <NUM> and second (protruding) portion <NUM> (curve <NUM>) and peak stress in the cover member <NUM> (cf. , σmax in <FIG>) at a position above the interface between first (main) portion <NUM> and second (protruding) portion <NUM> (curve <NUM>). The three curves <NUM>, <NUM>, <NUM> which on the left hand side are on the top represent peak stress in the cover member <NUM>, <NUM>, <NUM> at a position above a point of the second (protruding) portion <NUM>, <NUM>, <NUM>, which is closest to the optical axis (i.e., the most left hand point of the second (protruding) portion <NUM>, <NUM>, <NUM> in <FIG>). These curves <NUM>, <NUM>, <NUM> go towards <NUM> MPa for thickness d going towards zero (µm). The little inserted figures with shapes corresponding to the shape of the structural element, which the curves represent, have a little star indicating the position of the peak stress.

From <FIG> it can be seen that stress concentration factors (a ratio between peak stress σmax and reference stress σref. in <FIG>) in the cover member (of BPSG) at the cavity edge (i.e., at the at position above the interface between first (main) portion <NUM>, <NUM>, <NUM> and second (protruding) portion <NUM>, <NUM>, <NUM> (curves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>)) and at the inner edge of the second (protruding) portions <NUM>, <NUM>, <NUM> (i.e., at a position above a point of the second (protruding) portion <NUM>, <NUM>, <NUM>, which is closest to the optical axis, i.e., the most left hand point of the second (protruding) portion <NUM>, <NUM>, <NUM> (curves <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>)) are minimal (such as approximately <NUM>) when the second (protruding) portions have a rounded shape, cf. , the embodiment of <FIG>, with approximately <NUM>:<NUM> ratio of thickness to width, for example:.

It is furthermore noted that influence of the presence of the second (protruding) portions of embodiments of <FIG> on the optical power and root-mean square wavefront error (WFERMS) is negligible (quantitatively, respectively, less than <NUM> diopters and less than <NUM>).

<FIG> shows when the second (protruding) portions have a rounded shape, e.g. concave or inwardly curved shape, as shown in <FIG>, the optimal thickness d is approximately <NUM>, or values above <NUM>. The optimal thickness may be defined as the thickness where the stress levels at the cavity edge (star position to the right, red curves) and the stress levels at the edge of the structural element (star position to the left, blue curves) are approximate equal. Thus, <FIG> shows that a significant reduction of stress levels, particularly at the cavity edge (red curves) is possible with use of Epoxy for the structural element <NUM>.

<FIG> also shows that the optical thickness for rectangular element is about <NUM>-<NUM>, and the optimal thickness for the triangular element is about <NUM>.

It is noted that the concave shape of the surface of the structural element <NUM> made from Epoxy or other liquid structural element material is obtained as a result of the fluid properties of the material.

<FIG> shows is a schematic illustrating positions in an optical element. The figure shows an optical axis <NUM>, a supporting structure comprising a support element <NUM> and a structural element <NUM>, a bendable cover member <NUM> attached to the supporting structure, wherein an interface <NUM> (as indicated by the horizontal dotted line) between the bendable cover member <NUM> and the supporting structure defines an interface plane. The figure furthermore shows a point <NUM> at an inner edge of the interface <NUM> and a point <NUM> more distantly placed with respect to the optical axis (it is noted that this point <NUM> could be anywhere in the range indicated by curly bracket <NUM>). Still further, the figure shows a point <NUM> on a line from the point <NUM> at an inner edge of the interface to the optical axis <NUM> (it is noted that this point <NUM> could be anywhere in the range indicated by curly bracket <NUM>).

<FIG> shows an embodiment which is not covered by the subject-matter of the claims and is similar to the embodiment of <FIG>, except that it does not have the (protruding) structural elements (which it could have in another embodiment) but instead a dimension of the bendable cover member in a direction being parallel with the optical axis <NUM> is larger at at least one first point at an inner edge of the interface between the bendable cover member <NUM> and the supporting structure <NUM> than at at least one second point on a line from said first point to the optical axis <NUM>.

It is noted, that in all shown embodiments, the thickness of the structural element, the second (protruding) portion or the cover member, is increasing or constant at any point in a direction outwards from the optical axis, but it is also conceivable and encompassed by the present invention that for at least some (radial) range, the thickness could be decreasing.

Examples of alternative optical lenses are presented below and in <FIG>.

A first alternative optical lens not covered by the subject-matter of the claims comprises.

wherein each of the first element <NUM> and the second element <NUM> are extending further towards the optical axis than the supporting structure <NUM>. By 'more rigid' may be understood higher flexural rigidity. This may be achieved with a higher Young's modulus and/or larger thickness (i.e., dimension in a direction parallel with the optical axis).

<FIG> shows an embodiment of the first alternative optical element not covered by the subject-matter of the claims which is similar to the embodiment of <FIG> (cf. , e.g., 'polymer' lens body and back window) except that it does not have the (protruding) structural elements <NUM> (which it could have in another embodiment) and it does not have neither the soft object side cap ("blacksheet") <NUM> nor the adhesive <NUM>. Furthermore, in contrast with the embodiment of <FIG> the embodiment of <FIG> has a first element <NUM> ('hard cap') encircling the optical axis and attached to the cover member with a second element <NUM> ('hard cap adhesive'). An advantage of the first and second elements are may be that they inhibit excessive movement of the cover member, and thus avoid excessive stress in the cover member at the point of the inner edge of the supporting structure. It is noted that due to the adhesive second element, this effect is achieved in both directions (up/down, i.e., for impacts in both directions along the optical axis). Furthermore, the adhesive second element ensures that the rigid first element is some distance away from the cover member, so as to ensure that a stress singularity issue does not arise at the inner edge of the first element. The second element <NUM> can be made of steel (or copper or aluminium) with a thickness in the range <NUM>-<NUM> micrometer, such as <NUM>-<NUM> micrometer. The second element (which may be a glue) <NUM> can be epoxy (or an acrylic or silicone adhesive) with a thickness in the range <NUM>-<NUM> micrometer with Young's modulus E within <NUM>-<NUM> MPa. The Youngs' modulus of the second element <NUM> should preferably not be too stiff to avoid too much influence of the steel plate on optical parameters of the optical lens.

A second alternative optical lens not covered by the subject-matter of the claims, wherein the optical element is a refractive lens, comprises.

<FIG> shows an embodiment of the second alternative optical element not covered by the subject-matter of the claims which is similar to the embodiment of <FIG> (cf. , e.g., 'polymer' lens body and back window) except that it does not have the (protruding) structural element <NUM> (which it could have in another embodiment) and it does not have neither the soft object side cap ("blacksheet") <NUM> nor the adhesive <NUM>. Furthermore, in contrast with the embodiment of <FIG> the embodiment of <FIG> has the first element <NUM> ('soft cap') and the second element <NUM> ('soft cap adhesive'). An advantage of the first and second elements are may be that they inhibit excessive movement of the cover member, and thus avoid excessive stress in the cover member at the point of the inner edge of the supporting structure. It is noted that due to the adhesive second element, this effect is achieved in both directions (up/down, i.e., for impacts in both directions along the optical axis). The first element <NUM> can be made of polyimide of thickness <NUM>-<NUM> micrometer, such as <NUM>-<NUM> micrometer, or any other material with sufficiently low Young's modulus, such as the Young's modulus less than <NUM> MPa. The second element (which may be a glue) <NUM> can be epoxy (or an acrylic or silicone adhesive) with a thickness in the range <NUM>-<NUM> micrometer with Young's modulus E within <NUM>-<NUM> MPa. The Youngs' modulus of each of the first element <NUM> and the second element <NUM> should preferably not be too stiff to avoid too much influence on optical parameters of the optical lens. Both second element <NUM> and first element <NUM> should not be too stiff to avoid too much influence on optical parameters of the TLens.

In a third alternative embodiment not covered by the subject-matter of the claims (which is somewhat similar to the second alternative embodiment), the back window is attached to a rigid frame (such as the supporting structure) by dispensed glue.

In fourth, fifth and sixth alternative optical lenses there may be provided mechanical structure(s) located at a controlled distance from the moving cover member and/or back window. The mechanical structure(s) are provided in a ring-shape so as to enable encircling the optical axis without inhibiting the light path.

A fourth alternative optical lens not covered by the subject-matter of the claims comprises.

<FIG> shows an embodiment of the fourth alternative optical element not covered by the subject-matter of the claims which is similar to the embodiment of <FIG> (cf. , e.g., 'polymer' lens body and back window) except that it does not have the (protruding) structural element <NUM> (which it could have in another embodiment) and it does not have neither the soft object side cap ("blacksheet") <NUM> nor the adhesive <NUM>. Furthermore, in contrast with the embodiment of <FIG> the embodiment of <FIG> has the first element <NUM> ('hard cap'), the second element <NUM> ('hard cap adhesive'), the third element <NUM> ('hard cap') and the fourth element <NUM> ('hard cap adhesive'). An advantage of the fourth alternative optical element may be that the cover member is free to move during normal use, but has its movement inhibited to avoid excessive stress during impacts. Another advantage is that it may be easier technologically to glue cap <NUM> only to the package <NUM> (<FIG>) than to glue it both to the package and to the optical lens (<FIG>), which may in embodiments be referred to as TLens. The first element <NUM> and the third element <NUM> can be made of steel of thickness <NUM>-<NUM> micrometer. The second element <NUM> and the fourth element <NUM> can be epoxy (or an acrylic or silicone adhesive) of thickness <NUM>-<NUM> micrometer and can have Young's modules E within <NUM>-<NUM> MPa. It may be an advantage that the second element <NUM> and/or the fourth element <NUM> are as stiff as possible.

A fifth alternative optical lens not covered by the subject-matter of the claims comprises.

such as wherein the first, second, third, fourth and fifth elements (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) are being placed so as to inhibit motion of the back window in at least one direction along the optical axis. The flexural rigidity of the first, second, third, fourth and fifth elements (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) is sufficiently large to block large motion of the back window in the drop test and at the same time sufficiently small so as to not disturb small motion of the back window, for example when the piezo-film is actuated in normal operation mode.

<FIG> shows an embodiment of the fifth alternative optical element not covered by the subject-matter of the claims which is similar to the embodiment of <FIG> (cf. , e.g., 'polymer' lens body and back window) except that it does not have the (protruding) structural elements <NUM> (which it could have in another embodiment) and it does not have neither the soft object side cap ("blacksheet") <NUM> nor the adhesive <NUM>. Furthermore, in contrast with the embodiment of <FIG> the embodiment of <FIG> has the first, second, third, fourth and fifth elements <NUM>-<NUM>.

<FIG> shows a view from a point on the optical axis of the first element <NUM> and the fourth element <NUM> and both of the above combined <NUM>.

The first element <NUM> can be made of polyimide of thickness <NUM>-<NUM> micrometer or any other material with the Young's modulus less than <NUM> MPa. It should not be too stiff to avoid too much influence on optical parameters of the optical lens. The second element <NUM>, the third element <NUM> and the fifth element <NUM> (which may be adhesive layers) may be epoxy (or an acrylic or silicone adhesive) of thickness <NUM>-<NUM> micrometer and may have a Young's modulus E within <NUM>-<NUM> MPa. The first element <NUM> might not be essential for impact resistance, but may be relevant for blocking unnecessary light from being transmitted through the optical element. The first element and/or the fourth element <NUM> can be made of any standard black material (such as SOMABLACK film made of "polyester film in which carbon black is mixed", cf. , e.g., http://www. jp/english/products/<NUM> somablack. html as retrieved on April <NUM><NUM>). It may be an advantage that the fourth element <NUM> and/or one or more of the second element <NUM>, the third element <NUM> and the fifth element <NUM> (which may be adhesive layers) are as stiff as possible.

A sixth alternative optical lens not covered by the subject-matter of the claims comprises.

wherein the first, second and third elements are arranged so as to allow the back window to move freely below a threshold displacement (optionally a first and second threshold displacement for, respectively an up or down direction along the optical axis) and to inhibit movement beyond said threshold displacement. By 'more rigid' may be understood higher flexural rigidity. This may be achieved with a higher Young's modulus and/or larger thickness (i.e., dimension in a direction parallel with the optical axis).

<FIG> shows an embodiment of the sixth alternative optical element not covered by the subject-matter of the claims which is similar to the embodiment of <FIG> (cf. , e.g., 'polymer' lens body and back window) except that it does not have the (protruding) structural elements <NUM> (which it could have in another embodiment) and it does not have neither the soft object side cap ("blacksheet") <NUM> nor the adhesive <NUM>. Furthermore, in contrast with the embodiment of <FIG> the embodiment of <FIG> has the first, second and third elements <NUM>-<NUM>. The figure shows in the upper half arrangement of the optical lens along a first diagonal and in the lower half arrangement along the other diagonal. Arrow <NUM> indicates movement of back window in impact in one direction (the lower arrow indicates movement of impact in the opposite direction). The circle <NUM> indicates the gap defined by the second element <NUM>. The star <NUM> indicates the stop inhibiting further movement. The circle <NUM> indicates the gap defined by the third element <NUM>. The first element <NUM> can be made of polyimide with a thickness of <NUM>-<NUM> micrometer or any other material with the Young's modulus less than <NUM> MPa. The second element <NUM> and the third element <NUM> (which may each be a glue may be epoxy (or an acrylic or silicone adhesive) of thickness within <NUM>-<NUM> micrometer and may have a Young's modulus E within <NUM>-<NUM> MPa. The first element <NUM> should not be too stiff to avoid too much influence of on optical parameters of the optical element.

Claim 1:
An optical element (<NUM>) defining an optical axis and comprising:
- a supporting structure (<NUM>),
- a bendable cover member (<NUM>) attached to the supporting structure (<NUM>), wherein an interface between the bendable cover member (<NUM>) and the supporting structure (<NUM>) defines an interface plane,
- one or more actuators (<NUM>) arranged for shaping said bendable cover member (<NUM>) into a desired shape,
- at least one deformable transparent lens body (<NUM>, <NUM>) attached to the bendable cover member,
wherein
- one or more of
o a dimension in a direction being parallel with the optical axis, and/or
o a Young's modulus
of the supporting structure on one side of the interface plane increases gradually and/or in a plurality of steps along at least a portion of a line being orthogonal to the optical axis and intersecting the optical axis and in a direction away from the optical axis, wherein said line spans a range from a point at an inner edge of the interface and a point more distantly placed with respect to the optical axis,
and/or wherein
- a dimension of the bendable cover member in a direction being parallel with the optical axis (<NUM>) is larger
∘ at at least one first point at an inner edge of the interface, than
∘ at at least one second point on a line from said first point to the optical axis;
characterized in that the Young's modulus of the supporting structure is less than the Young's modulus of the bendable cover member (<NUM>).