PROJECTION OPTICAL SYSTEM AND METHOD FOR MANUFACTURING OPTICAL STRUCTURE - Patent application

Abstract

An embodiment according to the present invention includes a method for manufacturing an optical structure, the method including forming a first layer of the optical structure, the forming the first layer including forming and curing a first curable material on a first molding structure to form the first layer, thereby forming a first optical lens surface on a first side where the first layer bonds to the first molding structure, the method further including providing a second layer of the optical structure on a second side opposite the first side of the first layer, the first layer bonding to the first molding structure on the first side of the first layer. A further embodiment according to the present invention includes a projection optical system.

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments according to the present invention relate to projection optical systems and methods for manufacturing optical structures. [Background technology]

[0002] Modern camera systems are increasingly required to be small, powerful, and low-cost. As an example, in medical applications, camera systems may have to meet strict constraints regarding their dimensions so that they can be inserted into the human body to assist in surgery or to meet medical objectives such as determining the next steps in a respective treatment. Despite these constraints, it may be important for a miniature camera system to be able to provide high-quality images in order to provide the best possible assistance to the treating physician. At the same time, there is a need to provide low-complexity manufacturing methods for such systems in order to keep costs low. Summary of the Invention

[0003] It is therefore desirable to have a concept for optical structures and their manufacture as well as projection optics that provides a better compromise between the size, performance, complexity and thus cost of the optical structure or projection optics respectively and their manufacture.

[0004] This is achieved by the subject matter of the independent claims of the present application. Further embodiments according to the invention are defined by the subject matter of the dependent claims of the present application.

[0005] An embodiment according to the present invention includes a method for manufacturing an optical structure, the method including forming a first layer of the optical structure, the forming the first layer including forming and curing a first curable material on a first molding structure to form the first layer, thereby forming a first optical lens surface on a first side of the first layer adjacent the first molding structure, the method further including providing a second layer of the optical structure on a second side opposite the first side of the first layer, the first layer adjacent the first molding structure on the first side of the first layer.

[0006] The step of providing the second layer may be or may include forming said second layer, for example based on a molding procedure. In other words, the second layer may therefore be created or established on the opposite side of the first side of the first layer. In other words, the step of providing the second layer may include active formation or active creation (e.g., putting in place, e.g., arranging, e.g., installing, e.g., manufacturing, e.g., constructing, e.g., molding) of said layer while the first layer is adjacent to the first forming structure on the first side of the first layer, or more precisely while it is still adjacent to the first forming structure.

[0007] The inventors have recognized that a stack of layers of an optical structure produced by a molding process can also be processed during manufacturing on the back side, opposite the side subjected to the first molding step, i.e., by using the molding structure used for the first molding step when processing the back side, thereby avoiding the need for an additional substrate on the back side. That is, the molding structure may include a textured, e.g., non-planar, surface for forming or replicating the first optical lens surface of the first layer of the optical structure on the first side of the first layer. At least one processing step may be performed on the second side, opposite the first layer, while the first molding structure has not yet been removed to serve as a kind of handle, so to speak. For example, this processing may include replicating another layer. For example, a second layer may be provided on this second side without a substrate between the first and second layers. Thus, by way of example, the second layer may be provided directly on the first layer, or the two layers may be optionally separated only by one or more coating layers. At this manufacturing step, the first layer is still adjacent to the first shaped structure, which can provide a stable base for precise application of the second layer and / or one or more coating layers.

[0008] The inventors have recognized that in this way, less complex manufacturing of optical structures can be achieved without the need for intermediate substrates. For example, for mechanical reasons, substrates used in conventional approaches are limited to a minimum thickness, which hinders the desired miniaturization of optical structures. In short, the inventors have recognized that a molding structure, which may be needed anyway to form a lens surface in conventional approaches, for example, can be used dually not only to form lenses but also as a substitute substrate. This further reduces the need for elements in the manufacturing process, which may reduce costs.

[0009] According to an embodiment of the present invention, the step of providing the second layer includes the step of forming and curing a second curable material on a second side of the first layer using a second molding structure to form the second layer, whereby a second optical lens surface is formed on a second side of the second layer facing away from the second side of the first layer, where the second layer is adjacent the second molding structure, and the second optical lens surface is aligned with the first optical lens surface and the optical axis of the optical structure.

[0010] Briefly, as an example, the inventors have recognized that the approach for forming a first optical lens surface can be mirrored in forming a second optical lens surface by "sandwiching" a layer stack including first and second layers between a first molding structure and a second molding structure. Thus, optical lens surfaces can be formed on opposite sides of the layer stack, i.e., a first side of the first layer and a second side of the second layer, without the need for an intermediate substrate. Again, the first molding structure can provide stability to the cured first layer as the second curable material is formed and cured.

[0011] As mentioned above, the first and second layers may be directly adjacent to each other. However, it should be noted that, again, one or more coating layers may be provided on the second surface of the first layer, for example, before providing the second layer, and may optionally be structured. Optionally, such coating layers may form a filter or aperture, or a filter combined with an aperture, of the projection optical system or optical structure of the present invention.

[0012] Thus, an embodiment includes a projection optical system including a first layer of a first curable material, the first layer including a first optical lens surface on a first side of the first layer along an optical axis of the projection optical system and a planar portion on a second side of the first layer opposite the first side of the first layer along the optical axis, and the projection optical system further includes a second layer of a second curable material, the second layer including a planar portion on the first side of the second layer along the optical axis and a second optical lens surface on a second side of the second layer opposite the first side of the second layer along the optical axis.

[0013] Furthermore, the planar portion of the first layer is adjacent to the planar portion of the second layer at the optical axis, or the planar portion of the first layer is separated from the planar portion of the second layer at (or at) the optical axis only by one or more coating layers.

[0014] Thus, the method of the present invention may include removing the first and / or second shaping structures after curing of the first and second layers to provide the projection optics previously described.

[0015] Furthermore, by sandwiching or encapsulating the first and second curable materials between the first and second molding structures to produce the first and second layers, it is possible to provide precise alignment of the first and second optical lens surfaces with the optical axis of the projection optical system.

[0016] Further, according to embodiments, the projection optical system can include multiple layer stacks. As previously described, the layer stacks can include first and second double-sided replicated layers having optical lens surfaces on both sides. Therefore, the projection optical system can include a first additional layer and a second additional layer, which can be manufactured similarly to the first and second layers, and such additional layer stacks can be bonded to the second layer on the second side of the second layer, for example, so that the first additional layer is adjacent to the second layer. In this way, a projection optical system can be provided having at least two double-sided replicated layer stacks, each including at least four optical elements in the form of optical lens surfaces. Therefore, the projection optical system of the present invention can be formed from multiple modules including the first and second layers, and these modules can be manufactured using a similar manufacturing process, which can reduce the cost and complexity of each manufacturing method.

[0017] It should be noted that further coating layers may be provided between such further layers. With respect to any of the coating layers, the inventors have recognised that such coating layers may provide apertures and / or filters to further increase the feature density of the projection optics or optical structure, respectively.

[0018] According to a further embodiment, the projection optical system can include a third layer of a third curable material, the third layer adjacent to the second layer on a second side of the second layer and a first side of the third layer, or the third layer adjacent to the second further layer on a second side of the second further layer and a first side of the third layer. Furthermore, the third layer may comprise a third optical lens surface on a second side opposite the first side of the third layer in an optical axis of the projection optical system.

[0019] Thus, to provide such a third layer, the method of the present invention can include the steps of removing the second molding structure from the second layer, and forming and curing a third curable material on a second side of the second layer between the second layer and the third molding structure to form the third layer, whereby a third optical lens surface is formed on a first side of the third layer, adjacent the second layer and facing away from the first side of the third layer, on a second side of the third layer where the third layer is adjacent the third molding structure, and the first optical lens surface is aligned with the third optical lens surface at the optical axis of the optical structure.

[0020] Thus, a third layer may be provided on the second further layer of the projection optical system or optical structure of the present invention.

[0021] Thus, in the manufacturing process of the present invention, additional layers can be stacked on top of the first and second layers. Thus, simply put, one of the molding structures can be removed so that the next curable material can be applied to the layer and formed using the next molding structure. Simply put, to form the next layer, such as a third layer, the layer stack can again be sandwiched between the first molding structure and a next, for example, third, molding structure.

[0022] In general, embodiments according to the present invention may enable the use of a precisely clamped or fixed first molding structure for the alignment of multiple layers, or even all additional layers, replicated and / or bonded onto the first molding structure. This may simplify the manufacturing process and enable highly accurate alignment of the layers. Accordingly, in addition, alignment structures may be positioned outside the optical axis of the projection optics or optical structure to further improve the alignment of optical elements, such as lens surfaces. Alternatively, optical alignment methods may be used.

[0023] Additionally, embodiments may include compensation structures configured to compensate for manufacturing tolerances and / or to set or provide focus for the inventive structures or inventive optical systems. First, it should be noted that, to reduce costs, fabrication of the inventive optical elements or structures may be performed in parallel for multiple such devices, e.g., at wafer level and / or in an array configuration.

[0024] The inventors recognized that, based on the collection of data for each optical system or structure, individual or generic compensation structures can be used for compensation. For example, a set of parameters characterizing each structure or optical system can be obtained through testing, and if these parameters are similar, simply put, for multiple optical systems or structures fabricated in parallel, a generic compensation structure can be used for each structure or optical system. On the other hand, if such an approach results in too many rejects, an individual compensation structure can be fabricated for each optical element or structure and bonded to each optical element or structure. Alternatively, a compensation structure that best matches each of the projection optical systems or structures of the present invention can be selected from among multiple different compensation structures.

[0025] According to embodiments, each batch can choose between using a generic compensation structure or an individual compensation structure, potentially providing a highly optimized manufacturing process.

[0026] The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the invention are described with reference to the following drawings: [Brief explanation of the drawings]

[0027] [Figure 1a] FIG. 1 is a schematic diagram of a projection optical system having additional optional features according to an embodiment of the present invention. [Figure 1b] FIG. 1 is a schematic diagram of a projection optical system having additional optional features according to an embodiment of the present invention. [Figure 1c] FIG. 1 is a schematic diagram of a projection optical system having additional optional features according to an embodiment of the present invention. [Figure 2a] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2b]1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2c] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2d] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2e] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2f] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2g] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2h] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2i] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2j] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2k] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2l] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2m] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2n]1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2o] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2p] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2q] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2r] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2s] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 2t] 1 is a schematic side view of an optical structure and its components, visualizing a method for manufacturing the optical structure according to an embodiment of the present invention. [Figure 3] FIG. 2 is a schematic diagram of another projection optical system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] Equivalent or equivalent elements, or elements having equivalent or equivalent functions, are designated in the following description with the same or equivalent reference numerals, even if they appear in different figures.

[0029] In the following description, numerous details are set forth to provide a more thorough explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring embodiments of the present invention. Furthermore, features of different embodiments described herein below can be combined with each other unless specifically stated otherwise.

[0030] Furthermore, for purposes of describing the embodiments, the first side of an element may be opposite the second side of the element, and the sides of consecutive elements may be oriented such that the first side of one element is adjacent to the second side of another element. Thus, the first sides of the elements may be oriented in the same direction, and the second sides of the elements may be oriented in another, same direction opposite the orientation of the first sides. Simply put, the first side may be the top surface of the element, and the second side may be the bottom surface of the element.

[0031] First, it should be noted that embodiments according to the present invention include optical systems, for example in the form of projection optics and / or optical structures. While some embodiments are described with respect to methods for manufacturing projection optics or optical structures, it should be noted that any features, details, and functions of the respective projection optics and / or methods for manufacturing the same may be used in a similar, identical, or equivalent manner for optical structures and / or methods for manufacturing the same, and vice versa. Furthermore, the inventive arrangement of first and second layers may be referred to as a layer stack or a double-sided replication layer.

[0032] Furthermore, it should be noted that, in general, as used herein, the placement of an element on or at the optical axis may be understood to mean that the element is positioned laterally on the optical axis, e.g., laterally in-plane relative to the respective layer, e.g., laterally adjacent to the axis, e.g., within a laterally adjacent volume perpendicular to the axis.

[0033] 1a-1c show schematic diagrams of projection optical systems with additional optional features according to embodiments of the present invention. Projection optical systems 100a-c each include a first layer 110 of a first curable material and a second layer 120 of a second curable material. The first layer 110 includes a first optical lens surface 112 on a first side of the first layer relative to an optical axis 130 of the projection optical system. Furthermore, the first layer 110 includes a planar portion 114 on a second side of the first layer opposite the first side relative to the optical axis 130. Conversely, the second layer 120 includes a planar portion 122 on the first side of the second layer relative to the optical axis 130 and a second optical lens surface 124 on a second side of the second layer opposite the first side relative to the optical axis 130. As shown in FIGS. 1a-1c, the planar portion 114 of the first layer is optionally adjacent to the planar portion 122 of the second layer at the optical axis 130.

[0034] However, as an optional feature, each of the projection optical systems 100a-100c includes a coating layer 140. Note that multiple coating layers 130 (or 140) may be disposed between the first layer 110 and the second layer 120. As shown in Figures 1a-1c, the coating layer 140 may be a structured coating layer. In the illustrated embodiment, each coating layer 140 may form an aperture in each of the projection optical systems 100a-100c.

[0035] As another optional feature, the coating layer or one or more coating layers may form a filter of the respective projection optical system and / or an aperture and a filter of the respective projection optical system. Thus, in the optical axis, for example, in the case of a filter, one or more coating layers may be arranged between the first layer 110 and the second layer 120 such that the planar portion 114 of the first layer 110 is separated from the planar portion 122 of the second layer 120 at the optical axis 130 only by one or more coating layers (not shown). In such a case, it should be emphasized that the coating layer does not have to be a filter as described above by way of example, but may be, for example, any thin layer suitable for providing any desired functionality to the projection optical system.

[0036] As explained above, in contrast to conventional approaches, the absence of a substrate between the first and second layers allows the layer stack including layers 110 and 120 to be manufactured with small dimensions, resulting in a miniaturized layer stack. Furthermore, the inventors have recognized that an additional coating layer can even be disposed between the first and second layers, thus eliminating the substrate that would simply enlarge the overall structure, as well as further including another functional layer, e.g., providing the functionality of an aperture or a filter or even both, without significantly affecting the dimensions of the projection optics.

[0037] As an optional feature, the projection optical system 100c includes a second layer stack, in other words, a second double-sided replication layer. The projection optical system 100c includes a first further layer 110c of a first further curable material and a second further layer 120c of a second further curable material. The first further layer 110c includes a first further optical lens surface 112c on a first side of the first further layer along an optical axis 130 of the projection optical system and a planar portion 114c on a second side of the first further layer opposite the first side of the first further layer along the optical axis 130. The second further layer 120c includes a planar portion 122c on the first side of the second further layer along the optical axis 130 and a second further optical lens surface 124c on a second side of the second further layer opposite the first side of the second further layer along the optical axis 130.

[0038] Furthermore, the planar portion 114c of the first further layer 110c is adjacent to the planar portion 122c of the second further layer 120c at the optical axis 130. Again, it should be noted that this direct adjacency is merely optional, as already explained in the context of the first and second layers. Another optical feature is shown in the form of a further coating layer 140c disposed between the first further layer 110c and the second further layer 120c. Again, this further coating layer 140c may be, for example, a structured layer, but may also or alternatively optionally form a filter.

[0039] In general, a coating layer according to an embodiment of the present invention may be, for example, any thin layer including any suitable functionality. Thus, again, as described in the context of the first and second layers, the first further layer 100c may be, for example, separated from the second further layer 120c at the optical axis only by the coating layer 114c (or 140c). Thus, instead of the planar portions 114c and 122c being directly adjacent at the optical axis 130, the further coating layer 140c may be disposed at the optical axis 130 between these planar portions.

[0040] Furthermore, as shown for projection optical system 100c, first additional layer 110c is adjacent to second layer 120 on the second side of the second layer and on the first side of the first additional layer.

[0041] It should be noted that the first and second layers and the first and second further layers may be, for example, similar, identical, or entirely different layer stacks. Furthermore, it should be noted that such a configuration allows for providing multiple optical lens surfaces without the need to include a conventional substrate. Thus, even complex light projection paths through the projection optical system 110c can be provided without significantly increasing the size of the projection optical system.

[0042] For the sake of completeness, it is noted that multiple additional coating layers 140c may be disposed between the first and second additional layers, and that such additional layer stacks may also be bonded to any additional, e.g., third, layer that may be disposed on the second layer 120.

[0043] As shown, as another optional feature, projection optical system 100c includes a cavity 150c at optical axis 130 between second optical lens surface 124 and first further optical lens surface 112c.

[0044] As another optional feature, each of projection optical systems 100a-100c includes an additional layer 160 of additional curable material adjacent first layer 110 on a first side of the first layer and on a second side of the additional layer. Further, the additional layer includes an additional optical lens surface 162 on the second side of the additional layer at optical axis 130 of the projection optical system. Optionally, a cavity 150 may be present, as shown, between first optical lens surface 112 and additional optical lens surface 162 at optical axis 130.

[0045] For example, to bond the additional layer 160 to the first layer 110, the projection optical system of the present invention may optionally include an alignment structure. As an example, an alignment structure 170 is shown in FIG. 1c. To further emphasize that this feature is merely optional, the alignment structure 170 is only shown in FIG. 1c, but may also be present in the projection optical systems 100a and 100b. As shown in FIG. 1c, as an example, the alignment structure 170 may be disposed on a first side of the first layer 110 and a second side of the additional layer 160. The alignment structure 170 is configured to align the first layer 110 and the additional layer 160 such that the first optical lens surface 112 is aligned with the additional optical lens surface 162 at the optical axis 130. As an example, the alignment structure 170 is shown as a small pyramid structure, but any shape suitable for aligning two layers (or any other two layers to be bonded) may be used. As an example, one of the two layers, either the first layer or the additional layer, may include the alignment structure 170, and the respective other layer may include a female mold, or simply a hole, in the shape of the alignment structure so that the optical lens surfaces are aligned after bonding the two layers.

[0046] It should be emphasized that embodiments are not limited to such alignment structures. In the manufacturing method of the present invention, layers may be aligned using, for example, optical alignment methods. Furthermore, alignment clamps may also be disposed on the outer edges of each layer stack to provide alignment. Furthermore, it should be noted that alignment can be performed at the wafer level or array level, for example, for the manufacture of projection optics, thereby allowing multiple manufactured devices of the present invention to be aligned simultaneously. Therefore, in summary, optical alignment can be performed using alignment structures and / or mechanical structures, for example, clamp structures.

[0047] As shown in FIGS. 1a and 1c, the projection optical system may optionally include a support structure 180 adjacent to the additional layer 160 on a first side opposite the second side of the additional layer. The support structure 180 may be, for example, a substrate or a forming structure and / or a forming structure with a planar topology. Thus, the additional layer may be fabricated, for example, on a substrate, e.g., a glass substrate, using a conventional manufacturing process, and then the entire structure including the additional layer 160 and the substrate may be bonded onto the first layer 110. However, instead of using a substrate, a forming structure may be used to fabricate the additional layer 160. Thus, the first side of the additional layer 160 may optionally be provided with another lens surface formed by a respective forming structure. As another optional feature, the support structure 180 may be a forming structure with a planar topology that, in short, acts as a substrate.

[0048] As another optional feature, as shown in Figure 1b, the projection optical system 100b includes a third layer 190 of a third curable material. The third layer is adjacent to the second layer 120 on a first side of the third layer and on a second side of the second layer. Furthermore, the third layer 190 comprises a third optical lens surface 192 on a second side opposite the first side of the third layer with respect to the optical axis 130 of the projection optical system. For example, in the projection optical system as shown in Figure 1c, the third layer may optionally be adjacent to a second further layer 120c (not shown) on a second side of the second further layer and on a first side of the third layer.

[0049] The projection optical system 100b shown in FIG. 1b can provide an achromatic function. Therefore, optionally, two consecutive layers of the projection optical system can have different optical properties, i.e., in the example shown in FIG. 1b, the second layer 120 and the third layer 190. Thus, to form an achromat, the optical lens surface of the first of the two consecutive layers can have a high refractive index and low dispersion, and the optical lens surface of the second of the two consecutive layers facing the optical lens surface of the first of the two consecutive layers can have a low refractive index and high dispersion. Therefore, embodiments according to the present invention can limit the effects of chromatic and spherical aberrations. Therefore, adjacent lens surfaces can provide the functions of flint glass and crown glass.

[0050] 1a-1c, the projection optical systems 100a-100c may include a back structure 200 and a cavity 210. As shown in FIG. 1a, the first surface of the back structure 200 may be adjacent to the second layer 120 on the second side of the second layer, and the cavity 210 may be disposed between the back structure 200 and the second optical lens surface 124 along the optical axis 130. Alternatively, as shown in FIG. 1b, the first surface of the back structure 200 may be adjacent to the third layer 190 on the second side of the third layer, and the cavity 210 may be disposed between the back structure 200 and the third optical lens surface 192 along the optical axis 130. As another optional alternative, as shown in FIG. 1c, the first surface of the back structure 200 may be adjacent to the second further layer 120c on a second side of the second further layer, and the cavity 210 may be located between the back structure 200 and the second further optical lens surface 124c at the optical axis 130.

[0051] The back structure can provide mechanical stability to the projection optical system. Optionally, as shown in FIGS. 1a-1c, the back structure can include a back substrate 202, a filter 204, and a compensation structure 206. The compensation structure 202 (or 206) can be configured to compensate for manufacturing tolerances and set or improve the focus of the optical structure. As a result of manufacturing the layers of the projection optical system, for example, their thicknesses can vary within certain tolerances. However, this can degrade the desired beam path through the projection optical system and thus, for example, deteriorate the desired alignment of light rays through the projection optical system with a predetermined focus at the location where a sensor is bonded to the projection optical system. To compensate for such tolerances, the compensation structure 202 (or 206) can be included in the projection optical system.

[0052] As shown, filter 204 optionally includes a first filter structure 2041 disposed on a first surface of back substrate 202 and a second filter structure 2042 disposed on a second surface opposite the first surface of back substrate 202. Double-sided application of the filter structure allows for compensation for the effects of warping during manufacturing, thereby forming a planar structure that can accurately bond back substrate 202 and filter 204 to other layers and / or elements of the projection optics.

[0053] For reference, the compensation structure 206 may include a first surface and a second surface, the second surface being opposite the first surface, and the first surface of the compensation structure may be adjacent to the second filter structure 2042, such that the first filter structure 2041 forms the first surface of the back structure 200, as shown in Figures 1a to 1c.

[0054] However, it should be noted that, according to an embodiment, the order of the compensation structure and the back substrate can be interchanged along with the filter. Thus, optionally (not shown), the first filter structure 2041 may be adjacent to the second surface of the compensation structure 202 (or 206) such that the first surface of the compensation structure forms the first surface of the back structure 200. In short, the back substrate and the filter including the filter structure may be disposed, for example, at the bottom of the back structure 200, and the compensation structure 202 (or 206) may be disposed at the top of the back structure 200.

[0055] Additionally, it should be noted that, according to an embodiment, the rear structure 200 may optionally include only the compensation structure 206 or only the rear substrate 202 along with the filter 204 .

[0056] Furthermore, it should be noted that the filter may optionally include only a first filter structure and not a second filter structure. The first filter structure may be disposed on the first surface of the rear substrate at least along the optical axis. Thus, the first filter structure and the first surface of the rear substrate may form the first surface of the rear structure. In other words, the filter material may be disposed and structured on the rear substrate only in a region around the optical axis, for example, in a lateral region around the optical axis. Thus, the first filter structure may only partially form the first surface of the rear structure.

[0057] Furthermore, it should be noted that, in general, the cavity 210 may be at least partially formed by at least one of a recess in the second layer, a recess in the second further layer, a recess in the third layer, a recess in the rear structure, a through-hole in the rear structure, and / or a through-hole in the compensation structure of the rear structure. The recess and / or through-hole may be manufactured by at least one of etching, powder blasting, and / or laser-induced deep etching (LIDE). Thus, the cavity may be provided based on forming a spacer structure using the respective molding structure to provide a cavity for the respective lens structure, and / or based on a recess or through-hole in the rear structure. It should be noted that the cavity may be provided by one or both of the aforementioned techniques. Thus, the respective lens structure can fit into the recess or through-hole in the rear structure, for example, if the respective layer does not include a recess in which the lens structure is to be disposed.

[0058] It should be further noted that the through-holes in the back structure may also be through-holes that penetrate a component of the back structure, such as a compensation structure. Thus, by a subsequent filter, the through-holes can be "closed" on one side and form a cavity or part of a cavity. Furthermore, a cavity can be understood not only as a "closed" cavity, in which the internal volume of the cavity is completely sealed from the environment, but also as an "open" cavity, such as a natural cavity with an inlet, or in other words, a cavity that is not completely closed from the environment.

[0059] Optionally, the compensation structure 206 may be a generic compensation structure configured to compensate for manufacturing tolerances and / or to set or improve the focus of multiple projection optical systems on average. To obtain appropriate dimensions for the compensation structure 206, measurements of multiple projection optical systems can be obtained in a batch manufacturing process for the multiple projection optical systems. For example, if different projection optical systems are similar, e.g., with respect to their tolerances, a generic compensation structure may be formed and used equally for all projection optical systems. The compensation structure used may therefore be configured to (at least partially or substantially) compensate for manufacturing tolerances and / or to set or improve the focus of multiple projection optical systems, at least on average. In other words, the compensation structure may be formed, simply put, as a compromise to best improve the multiple projection optical systems.

[0060] Thus, compensation structures 206 may be individual compensation structures configured to compensate for manufacturing tolerances and / or to set or improve the focus of the projection optical system. Thus, for example, based on individual measurements of the respective projection optical system, individual compensation structures can be formed for each projection optical system to best improve the properties of the respective optical system.

[0061] Optionally, the projection optical systems 100a, 100b, and 100c can have a lateral dimension in the plane of the first layer 110 of at least 100 μm, at least 200 μm, at least 300 μm, or at least 0.5 mm, and at most 2 mm, at most 3 mm, or at most 5 mm. Alternatively or additionally, the projection optical systems can have a height perpendicular to the first and second layers of at least 0.5 mm, at least 1 mm, or at least 2 mm, at most 2 mm, at most 3 mm, or at most 5 mm. Thus, as previously mentioned, a projection optical system with small dimensions can be provided, allowing it to be used in challenging applications, such as providing visual assistance for surgery inside the human body.

[0062] 1a-1c show sensor structure 220 bonded to compensation structure 206. Thus, compensation structure 206 can be used to precisely focus light rays traveling through the projection optics onto the sensor chip of sensor structure 220.

[0063] Reference is now made to Figures 2a to 2t. Figure 2 shows a schematic side view of an optical structure and its components, visualising a method for manufacturing an optical structure according to an embodiment of the invention. The optical structure to be manufactured may for example be a projection optical system as shown in Figure 1.

[0064] 2a-2d illustrate forming a first layer of an optical structure and providing a second layer of an optical structure. As shown in FIG. 1a, a first layer 310 can be formed, where forming the first layer includes forming and curing a first curable material on a first molding structure 320 to form the first layer, thereby forming a first optical lens surface 312 on a first side of the first layer adjacent the first molding structure.

[0065] Optionally, as shown in FIG. 2b, methods according to embodiments may include providing one or more coating layers between the first layer 310 and the second layer. Thus, as shown in FIG. 2b, a coating layer 330 may be disposed on the second side of the first layer 310 and on the plane of the first layer 310. As another optional feature, one or more coating layers 330 may be structured. As an example, as shown in FIG. 2b, one coating layer 330 forms an aperture. However, it should be noted that, in addition to the aperture, one or more coating layers may optionally form a filter and / or a filter and an aperture.

[0066] It should be noted that the coating layer is provided on a second side opposite the first side of the first layer 310, and the first layer 310 is adjacent to the first forming structure 320 on the first side of the first layer.

[0067] As shown in Figure 2c, a second layer of the optical structure may again be provided on a second side opposite the first side of the first layer 310, while the first layer 310 is adjacent on the first side of the first layer to a first forming structure 320. It should be noted that, as shown in Figure 2c, a second forming structure 350 may be used in forming the second layer, although this feature is merely optional.

[0068] 2c, providing the second layer 340 can include forming and curing a second curable material on the second side of the first layer 310 using a second molding structure 350 to form the second layer, whereby the second layer is adjacent to the second molding structure 350 and a second optical lens surface 344 is formed on the second side of the second layer 340 facing away from the second side of the first layer 310, the second optical lens surface 344 being aligned with the first optical lens surface 312 at the optical axis 360 of the optical structure. As shown in FIG. 2c, the second optical lens surface 344 can be a convex lens, but as shown in FIG. 2d, it can also be concave. Thus, the molding structure 350 as shown in FIG. 2d can include different configurations.

[0069] As optionally shown, each molding structure may include a master support 322 and 354, respectively, and a master (PDMS) 324 and 352, respectively. The master support may, for example, include or be made of glass, and the master may include polydimethylsiloxane. In the embodiment shown in Figures 2a-2t, the first layer 310 may be the first replication layer, and the second layer 330 may be the second replication layer. Thus, replication layer 2 and replication layer 2a may be different instances of second layer 330, with different shapes of their respective optical lens surfaces 344.

[0070] 2a, according to an embodiment, the first process step may be to replicate a lens layer 1, e.g., replication layer 1, using a master 324 (e.g., a typical PDMS-type material) comprising a master support 322 (e.g., typical glass). The replication layer may be applied by a puddling process and then UV-cured. By way of example, such a puddling process may comprise applying an epoxy material, e.g., replication layer 1, onto a substrate or wafer, or, according to a preferred embodiment, onto a molding structure, e.g., by means of a mechanical "puddle," to reach a final thickness of the material. Furthermore, the puddling process may comprise removing excess material with a puddle.

[0071] As another example, spin coating may be performed for the above process steps.

[0072] 2b, by way of example, in other words, in this process step the replicated layer may still be kept in the master 324 and a coating layer 330 in the form of apertures may be applied, for example by coating, for example by spin-coating, a thin layer of an opaque black material (e.g., that can be structured lithographically) that can be structured by a lithographic process, in order to generate a coating layer in the form of apertures. It should be noted that, in contrast to conventional approaches in which apertures are structured on a glass substrate comprising a typical black chrome, according to embodiments the apertures may be structured directly on the replication layer.

[0073] Referring to Figure 2c, as an example, in other words, in this process step, the replication layer (including the structured aperture) may still be retained within the master, and then replication layer 2 (lens 2, e.g., layer 340 including second optical lens surface 344) is replicated using second master 352 (including master support 354).

[0074] As shown in FIG. 2, the method of the present invention according to the embodiment can be carried out to provide a plurality of optical structures, for example, at the wafer level or in an array arrangement. Thus, as shown, a plurality of optical lens surfaces 312 and 344 can be provided (see, for example, the subsequent dicing step shown in FIG. 2q). Thus, in a subsequent process, the layer can be diced to provide a plurality of optical structures. In this regard, it should be noted that although wafer-level lenses can be performed, a glass substrate cannot be used between replication layers 1 and 2, and replication layer 2 may be replicated directly on the aperture and replication layer 1.

[0075] 2d, in other words, as an example, Fig. 2d can show an alternative approach, for example an alternative to the approach shown in Fig. 2c, in which the replication layer 2 is no longer a convex lens but includes a concave shape (replication layer 2a) so that an achromat can be constructed. For example, the lens layer 2a (e.g., second layer 340) can include a relatively low Abbe number (e.g., V number or aberration coefficient of the transparent material) and can represent a flint-type material.

[0076] Referring to Figures 2e and 2f, as another optional feature, a third layer 370 of optical structures may be provided. As shown in Figure 2e, providing the third layer 370 can include removing the second forming structure 350 from the second layer 340 to form the third layer; and forming and curing a third curable material on a second side of the second layer 340 between the second layer and the third forming structure 350a (again, optionally including the master 352a and master support 354a), as shown in Figure 2f, thereby forming a third optical lens surface 372, as shown in Figure 2f, on a first side of the third layer 370, where the third layer is adjacent to the second layer 340 and on a second side of the third layer, facing away from the first side of the third layer, where the third layer is adjacent to the third forming structure 350a, and where the first optical lens surface 312 is aligned with the third optical lens surface 372 at the optical axis 360 of the optical structure.

[0077] As shown, optionally, a third layer 370 may be provided between first layer 310 and first forming structure 320 on a first side of the first layer.

[0078] In other words, referring to FIG. 2e, in this step, the master 352 that formed the concave lens, e.g., lens surface 344 as shown in FIG. 2d, is removed, but the entire wafer is still held within master 324 by lens 1.

[0079] It should be noted that the fabrication steps of Figures 2e and 2f are shown based on the approach as shown in Figure 2d, however, providing a third layer may equally be performed for an optical structure as shown in Figure 2c, or any other alternative layer stack according to an embodiment of the present invention.

[0080] Again, in other words, referring to FIG. 2f, for example, an alternative approach, such as that shown in FIG. 2d, may be completed, and another layer (e.g., a replicated layer 2b including a double convex shape) may be overcoated on replicated layer 2a to build an achromat. For example, lens layer 2b (e.g., third layer 370) may include a relatively high Abbe number and represent a crown-type material that may be needed to build an achromat and improve chromatic aberration. Thus, in summary, embodiments include, for example, building an achromat on a wafer-level optical system, particularly compared to conventional approaches.

[0081] As another optional feature, the first and second further layers can be provided and formed using steps such as those visualized in Figures 2a-2d. Thus, further layer stacks can be provided in a similar or identical manner, with forming a first further layer of the optical structure comprising forming and curing a first further curable material on the first further shaping structure to form the first further layer, thereby forming a first further optical lens surface on a first side of the first further layer adjacent the first further shaping structure. Furthermore, the step of providing a second further layer of the optical structure on a second side opposite the first side of the first further layer while the first further layer is adjacent to the first further shaping structure on the first side of the first further layer may include using the second further shaping structure to form and harden a second further curable material on the second side of the first further layer to form the second further layer, whereby the second further layer is adjacent to the second further shaping structure and a second further optical lens surface is formed on the second side of the second further layer facing away from the second side of the first further layer, the second further optical lens surface being aligned with the first further optical lens surface at the optical axis of the optical structure.

[0082] 2a-2d, layer 310 may represent a first further layer, layer 340 may represent a second further layer, first forming structure 320 may represent a first further forming structure, and forming structure 350 may represent a second further forming structure.

[0083] It should be noted that one or more further coating layers may therefore be provided between the first and second further layer, and at least one of the one or more further coating layers may be structured. Furthermore, as described in the context of one or more coating layers, the one or more further coating layers may therefore simultaneously form apertures and / or filters, or both.

[0084] In this regard, it is noted that the thickness of the one or more coating layers and / or one or more further coating layers between the first layer and the second layer and between the first further layer and the second further layer may comprise up to 10% or up to 5% or up to 2% or up to 1% of the thickness of the first layer, or of the thickness of the second layer, and / or of the thickness of the first further layer, and / or of the thickness of the second further layer, respectively.

[0085] Thus, a second layer stack including first and second additional layers may be bonded to the first layer stack including the first and second layers. Thus, for example, as shown in FIG. 2e, the second shaping structure 350 can be removed. Furthermore, (not shown) for bonding, the first additional shaping structure can be removed. Then, (not shown), the first additional layer can be bonded to the second layer 340 such that the first additional layer is adjacent to the second layer on the second side of the second layer and the first side of the first additional layer, and the first additional optical lens surface is aligned with the second optical lens surface 344 at the optical axis 360 of the optical structure. Thus, as described in the context of FIG. 1c, the first additional optical lens surface and the second optical lens surface can be formed such that the optical structure includes a cavity between the first additional optical lens surface and the second optical lens surface at the optical axis 360 of the optical structure. Note that, again, the additional layer stack may be bonded to the third layer of the optical structure.

[0086] 2g illustrates another optical process step according to an embodiment, for example, the next step in the structure shown in FIG. 2c can be to remove the first and second shaping structures 320 and 350. In other words, the next process, for example if the optical structures are not achromatic, can be to remove the master wafers on both sides.

[0087] Figure 2h shows an example of further optical method steps for a structure such as that shown in Figure 2f, including removal of first and third shaping structures 320 and 350a. In other words, the next process step for the alternative approach (achromatic) may be to remove the master wafer on both sides.

[0088] 2i and 2j illustrate an additional optional method step of providing an optical substructure. Optical substructure 380 includes a support structure 382 and an additional layer 384. Providing the optical substructure may include forming and curing an additional curable material between additional forming structure 390 and support structure 382 to form additional layer 384, whereby additional optical lens surface 386 is formed on a second side of additional layer 384 adjacent additional forming structure 390, and the additional layer is adjacent support structure 382 on a first side of the additional layer opposite the second side of the additional layer.

[0089] Again, the additional forming structure 390 may optionally include a master 392 and a master support 394. Additionally, the additional layer may be a replication layer, i.e., replication layer 3, as shown, and similarly, the support structure may be a replication base layer.

[0090] As shown in the example of Figure 2i, the support structure may be a substrate. Alternatively, as shown in Figure 2j, the support structure 382 may be a forming structure and / or may be a forming structure having a planar topology, for example, as specifically shown in Figure 2j. As another optional feature, in Figure 2j, the planar forming structure again comprises a master support 3801 and a master 3822.

[0091] Referring to Figure 2i, as an example, in other words, in this process step, the lens replication layer 3 may be produced by directly replicating it onto a glass substrate using a master 392 (PDMS) and a master support 394, for example in the form of a replication base layer.

[0092] 2j can show an alternative approach of using only a master support 3821 comprising a flat PDMS layer 3822 without using a substrate (front glass) to replicate a lens layer 3, e.g., replication layer 3. As an example, a lens layer, e.g., 384, may be replicated by using a master, e.g., 392, having a layer 3 structure and a master support, e.g., 394.

[0093] As an optional feature, both masters 382 and 390 can then be removed, for example as shown in Figures g) and h) (e.g., Figures 2g) and 2h)). Thus, embodiments can include optical structures that do not include a cover glass in the final product but have a substrate-less design.

[0094] As shown as an optical and / or optional feature in Figures 2k and 2l, for example, after removing first shaping structure 320 from at least first layer 310 as shown in Figures 2g and 2h, and after removing additional shaping structure 390, additional layer 384 can be bonded to first layer 310 such that additional layer 384 is adjacent to first layer 310 on a first side of the first layer and a second side of the additional layer, and additional optical lens surface 386 is aligned with first optical lens surface 312 at the optical axis of the optical structure. As optionally shown in Figure 2l, the method of the present invention can further include removing support structure 382 from additional layer 384. It should be noted that removal of the support structure is independent of the form of the structure, and thus the support structure can be removed in the form of a glass substrate or substrate, or in the form of a shaping structure, or in the form of a planar shaping structure, for example as shown in Figure 2j.

[0095] As another optional feature as shown in Figure 2k, a method according to an embodiment may include bonding a first surface of the rear structure 410 to the second layer 340 on a second side of the second layer such that the second optical lens surface 344 and the first surface of the rear structure form a cavity 450 (as shown in Figure 2m). For bonding the rear structure 410, the method may include, for example, beforehand, removing the second molding structure 350 from the second layer 340, as shown in Figure 2g.

[0096] Thus, for an optical structure including a third layer 370, as shown in FIG. 2l, the third molding structure 380 can be removed, for example as shown in FIG. 2h, and the first surface of the rear structure 410 can be bonded to the third layer 370 on the second side of the third layer such that the third optical lens surface 372 and the first surface of the rear structure form a cavity 450 (as shown in FIG. 2n).

[0097] 2k and 2l, the rear structure 410 may include a substrate 412 and a filter 414. The filter may include a first filter structure 4141 disposed on a first surface of the rear substrate and a second filter structure 4142 disposed on a second surface of the rear substrate opposite the first surface. Thus, the first filter structure 414 may form the first surface of the rear structure 410.

[0098] 2k, in other words, rear substrate 412 may be or act as a filter carrier, layer 4141 may be a filter compensation or filter compensation layer, and layer 4142 may be a filter layer. As mentioned above, double-sided application of the filter layer can reduce the effects of warping and can provide a flat rear structure 410 that can be precisely bonded to the respective layer 340 or 370. Further, as an example, in other words, once lens layers 1, 2, and 3 are completed, they can be laminated and bonded to each other, and then a rear glass, e.g., 410, which may be simply glass, can be bonded, and its thickness may be appropriately specified, e.g., with a low TTV (low total thickness variation).

[0099] Therefore, in general, embodiments in accordance with the present invention can also include a rear structure including only a rear substrate. The rear glass, e.g., 410, can incorporate an optical filter, e.g., 414, such as an NIR cut filter, a notch filter, or a bandpass filter. As previously explained, the filter can be applied to both sides to ensure no, limited, or slight distortion of the filter substrate, thereby providing compensation and allowing the substrate to remain flat. Referring to Figure 2l, the same or similar process as shown in Figure 2k can be illustrated, but now with an alternative approach for lenses 1, 2a / b and lens 3 (achromat).

[0100] The results of the lamination steps as shown in Figures 2k and 2l are shown in Figures 2m and 2n. As shown, optionally, first optical lens surface 312 and additional optical lens surface 386 may be formed such that the optical structure includes a cavity 420 between the first optical lens surface and the additional optical lens surface at the optical axis 360 of the optical structure.

[0101] As an example, in other words, FIG. 2m can show the final bonded stack still in wafer form, and FIG. 2n can show the final bonded stack still in wafer form (alternative achromatic approach).

[0102] 2o and 2p illustrate further optional features of a method according to an embodiment, in which the optical structure is provided with compensation structures 430, and 4301, 4302, and 4303, respectively. The compensation structures may be configured to compensate for manufacturing tolerances and / or to set or improve the focus of the optical structure. Additionally, the back structure 410 may be provided with compensation structures.

[0103] Thus, each compensation structure may be bonded to the first and / or second filter structure. As explained above, simply put, the order of the compensation structure, substrate 412, and filter 414 may be changed. Therefore, alternatively, the method of the present invention may optionally include bonding a first filter structure to a second surface of the compensation structure such that the first surface of the compensation structure forms the first surface of the back structure 410, such that the compensation structure is bonded to a second or third layer, or, for example, a second further layer. Alternatively, the method of the present invention may optionally include bonding a first surface of the compensation structure to a second filter structure 4142 such that the first filter structure 4141 forms the first surface of the back structure 410, as shown, for example, in FIGS. 2o and 2p.

[0104] However, it should be noted that the back structure 410 may comprise, for example, only the compensation structures 430 or 4301, or only the elements 412 and 414, respectively.

[0105] As shown in FIG. 2o, the compensation structure may be a universal compensation structure used for each optical structure of the set of optical structures. As shown in FIG. 2o, compensation structure 430 may be, for example, a globally matched back glass. Optionally, the method may further include determining a plurality of parameter sets, each parameter set characterizing one optical structure of the plurality of optical structures, and providing the compensation structure as a universal compensation structure. The providing of the compensation structure may further include adjusting the compensation structure based on the determined plurality of parameter sets to compensate for manufacturing tolerances and to set or improve the focus of the optical structures on average.

[0106] As shown in FIG. 2o and as described above, a separation into a plurality of optical structures, here by way of example for simplicity into three different optical structures I, II, and III, can be performed. It should be noted that, in general, according to embodiments, a large number of structures, for example hundreds or thousands or tens of thousands of optical structures or projection optics or lens stacks, can be arranged, for example, in one row on a wafer or array arrangement. In other words, in practice, the drawing may show only a portion of three structures in one row out of what is usually a much larger number of structures (which can easily be 10,000 structures or even 100 structures on an 8-inch wafer).

[0107] Therefore, measurements can be performed on each of these stacks, and as an example, the properties of each of the stacks that can be diced into separate optical structures may be sufficiently similar (e.g., in terms of yield or performance) so that manufacturing tolerances are compensated for on average (e.g., allowing for ``compromise compensation'' of the three optical structures I, II, III) in order to use a generic structure.

[0108] Thus, for example, if the layer stacks that can be diced into individual optical structures I, II, III are not sufficiently similar as shown in FIG. 2p, or if, for example, a globally matched back glass approach may result in too many defective devices based on the respective sets of measurements and / or parameters characterizing each optical structure, individual compensation structures 4301, 4302, and 4303 can be provided, each individual compensation structure being adjusted based on the respective set of parameters to compensate for manufacturing tolerances and / or to set or improve the focus of each optical structure.

[0109] In other words, referring to FIG. 2o as an example, it may be necessary to add additional glass spacer wafers (e.g., compensation structures 430) to compensate for tolerances and build a camera with a well-defined best focus position. All lenses on a stacked wafer or array arrangement can be measured, e.g., using an automated test system, for MTF (Modulation Transfer Function), BFL (Back Focal Length), EFL (Effective Focal Length), etc., to generate a wafer map or array map of multiple optical structures. If the tolerances for a set of parameters within a wafer or array, e.g., BFL, are not too large, a globally matched back glass approach can be used, meaning, for example, that an average value for BFL across all lenses or layer stacks on a wafer or in an array of optical structures can be calculated, and the compensation structure, e.g., the back glass wafer, can be ground to that thickness. Lenses with poor MTF (e.g., layer stacks I, II, and / or III) or lenses with BFLs that are too short, too short, or too long may not be usable, or may result in reduced yield if used.

[0110] Thus, referring to Figure 2p, if using a globally aligned back glass would result in too high tolerances and potentially unacceptable yields, individual spacer alignment can be used as an alternative. Again, all lenses on the stacked wafer can be measured for characteristic parameters, such as MTF, BFL, EFL, etc., using, for example, an automated test system, and a wafer or array map can be generated. A set of pre-diced compensation structures, e.g., glass substrates 4301, 4302, 4303, with predetermined dimensions, can be prepared or will be prepared with different, e.g., appropriately defined, thicknesses (e.g., multiple, e.g., five different thicknesses with specific differences), and then these small glass substrates can be bonded as a single component to form individual lens stacks. As an example, a shorter BFL may require a thinner back glass, etc. For example, typically, only lenses with poor MTF must be skipped at the end.

[0111] However, it should be noted that embodiments are not limited to compensation structures in the form of glass spacers. The compensation structure according to embodiments may also be a separate replication layer, for example, a layer including an epoxy material that can be applied and then UV-cured. In particular, such a compensation layer may be applied at wafer level, thus prior to dicing into separate projection optical systems. As mentioned above, testing of the projection optical systems (e.g., for the full aperture of each optical system) can be performed, for example, for each projection optical system individually or at wafer level to obtain a single result for the projection optical systems of the entire wafer.

[0112] Optionally, according to embodiments of the present invention, the compensation structure can be adapted, for example, according to such testing at wafer level, to set or improve the back focal length of the projection optics of the wafer. This can correspond to a focal length or an overall setting of the focal length of the projection optics of the wafer. Thus, the thickness of the compensation structure can be adjusted, for example, across the entire wafer, for example, so that the compensation structure has the same thickness across the entire wafer. Alternatively, individual adaptations can be performed as well.

[0113] Using the manufacturing technique of the present invention, the focal length of the projection optics of the wafer can be set with good precision, e.g., with low individual tolerances for each projection optic of the wafer, so that, e.g., instead of individually adapted spacers, a global adaptation of compensation structures can be performed to fine-tune the focal length within the set tolerances.

[0114] Thus, in general, according to an embodiment, the compensation layer may be a hardening material (e.g., a first, second, further, and / or another hardening material) and may be configured to compensate for manufacturing tolerances and / or to set or improve the focus of a projection optical system and / or to set or improve the focus of multiple projection optical systems at wafer level.

[0115] Thus, optionally, the rear structure 410 may include a rear substrate 412, a filter 414, and a compensation structure, wherein the compensation structure is configured to compensate for manufacturing tolerances and / or to set and / or improve the focus of the optical structure, and wherein the filter includes a first filter structure 4141 arranged on a first surface of the rear substrate, and wherein the filter includes a second filter structure 4142 arranged on a second surface opposite the first surface of the rear substrate, or wherein the filter includes a first filter structure arranged on the first surface of the rear substrate at least in the optical axis, and wherein the first filter structure and the first surface of the rear substrate form the first surface of the rear structure.

[0116] Further, the method optionally includes a step of bonding the first filter structure 4141 to the second layer on a second side of the second layer so that the second optical lens surface and the first filter structure 4141 form a cavity at the optical axis, or a step of bonding the first filter structure 4141 to the second further layer on a second side of the second further layer so that the second further optical lens surface and the first filter structure 4141 form a cavity at the optical axis, or a step of bonding the first filter structure 4141 to the third layer on a second side of the third layer so that the third optical lens surface and the first filter structure 4141 form a cavity.

[0117] Further, the method may optionally include forming and curing a curable material on the second filter structure 4142 or the rear substrate, for example, to form a compensation structure having a predetermined thickness to compensate for manufacturing tolerances and / or to set the focal length of the respective optical system, as described above.

[0118] As another optional feature, methods according to embodiments may include forming and curing a curable material on the substrate and / or molding structure to form a compensation structure; removing the compensation structure from the substrate and / or molding structure; bonding the compensation structure to the second layer on a second side of the second layer so that the second optical lens surface and the compensation structure form a cavity at the optical axis; or bonding the compensation structure to the second further layer on the second side of the second further layer so that the second further optical lens surface and the compensation structure form a cavity at the optical axis; or bonding the compensation structure to the third layer on the second side of the third layer so that the third optical lens surface and the compensation structure form a cavity.

[0119] Optionally, the method may include forming and curing a curable material on the substrate and / or molding structure to form the compensation structure, removing the compensation structure from the substrate and / or molding structure, and bonding the compensation structure to a second filter structure or a back substrate.

[0120] Thus, as an example, the overall matched back glass may simply be replaced with an overall matched hardened material.

[0121] 2q and 2r, methods according to embodiments can optionally include a step of performing dicing to separate optical structures I, II, and III of the plurality of optical structures. In other words, as an example, the entire wafer or array, for example after completion, can be diced with a wafer saw using, for example, blue tape or UV peel tape. FIG. 2q shows an example using a globally aligned back glass 430, while FIG. 2r shows, as an example, an individually aligned back glass for an alternative approach (achromat).

[0122] As shown in Figures 2s and 2t, the method of the present invention can optionally include bonding the sensor structure 440 to an optical structure. As shown, the sensor may include a cover glass. In other words, as an example, once the optical stack is complete, the CMOS image sensor can be bonded to a lens. Figure 2t can show an alternative approach using an achromat.

[0123] 1a) and 1b) can respectively show the end result of the manufacturing method according to Fig. 2a) to 2s) and 2t). Thus, according to the embodiment described in the context of Fig. 2, in Fig. 1a) and 1b), layer 110 can be replication layer 1, layer 120 can be replication layer 2 (in Fig. 1a) and replication layer 2a (in Fig. 1b), respectively, layer 180 can be replication base layer, layer 160 can be replication layer 3, coating layer 140 can be aperture, layer 190 in Fig. 1b) can be replication layer 2b, element 202 can be filter carrier, element 2041 can be filter compensation, element 2042 can be filter layer, element 206 can be matching spacer, and element 220 can be sensor with cover glass.

[0124] Thus, Figure 1a) can show a final product with three aspherical surfaces and one aperture, with no substrate between layers 1 and 2, and with a substrate on replication layer 3 (which can also act as a cover glass). Figure 1b) can show a final product with four aspherical surfaces (e.g., 2a and 2b acting as achromats) and one aperture, with no substrate between layers 1 and 2a / b, and with no substrate on replication layer 3.

[0125] It should be noted that, in general, embodiments according to the present invention can include aspherical and / or spherical optical lens surfaces. In other words, by way of example, all lens surfaces, such as those shown in the drawings, may typically have aspherical shapes, but may also have spherical shapes depending on the specific design. Furthermore, as previously described, processes according to embodiments can be in wafer format, e.g., for 6-inch, 8-inch, or 12-inch circular substrates, although square or rectangular substrates are also possible. By way of example, a typical size of the final product can be approximately 1 mm by 1 mm, with a 2 mm height and a 1.4 mm pitch between lenses.

[0126] 3 is a schematic diagram of another projection optical system according to an embodiment of the present invention. Figure 3 shows a schematic top view 510 of multiple projection optical systems I, II, and III in a wafer-level or array-level arrangement. As an example, each projection optical system may be diced along dashed lines 512, 514.

[0127] 3 further shows a schematic side view 520 along the cross section AA as shown in the schematic top view 510. As explained previously, the projection optical system 500(III) exemplarily comprises a first layer 522 of a first curable material in the form of a replication layer (replication layer 2), with a first optical lens surface 524 on a first side of the first layer relative to the optical axis 526 of the projection optical system, and a planar portion 528 on a second side of the first layer opposite the first side of the first layer relative to the optical axis. The projection optical system 500(III) further comprises a second layer 530 of a second curable material in the form of another replication layer (replication layer 3), with a planar portion 532 on a first side of the second layer relative to the optical axis 526, and a second optical lens surface 534 on a second side of the second layer opposite the first side of the second layer relative to the optical axis 526.

[0128] As an optional feature, the projection optical system 500 includes an additional layer 536 of additional curable material adjacent the first layer 522 on a first side of the first layer and a second side of the additional layer. The additional layer further includes an additional optical lens surface 538 on the second side of the additional layer at the optical axis 526 of the projection optical system, and a cavity 540 between the first optical lens surface 524 and the additional optical lens 538 at the optical axis.

[0129] Furthermore, as another optional feature, the projection optical system includes a support structure 542 adjacent to the additional layer on a first side opposite to the second side of the additional layer, the support structure being a substrate in the form of a front glass.

[0130] Furthermore, the projection optical system 500 includes a lithographically structured coating layer 544 (eg, made of a polymer material) in the form of apertures.

[0131] As another optional feature, the projection optical system 500 includes a rear structure 546 and a cavity 548, wherein a first surface of the rear structure is adjacent to the second layer 530 on a second side of the second layer, and the cavity 548 is positioned between the rear structure 546 and the second optical lens surface 534 at the optical axis 526.

[0132] As an example, rear structure 546 comprises a rear substrate having a filter 550 in the form of a filtered rear glass, and a compensation structure 552 in the form of spacer glass for spacer alignment. As previously mentioned, the compensation structure is configured to compensate for manufacturing tolerances and / or to set or improve the focus of the optical structure.

[0133] The filter includes a first filter structure disposed on a first surface of the rear substrate and a second filter structure disposed on a second surface of the rear substrate opposite the first surface, and the compensation structure includes a first surface and a second surface, the second surface being opposite the first surface.

[0134] In the example shown in FIG. 3, the first filter structure is adjacent to the second surface of the compensation structure such that the first surface of the compensation structure forms the first surface of the back structure.

[0135] Figure 3 further illustrates an enlarged schematic side view 560 of portion B shown in Figure 520, highlighting the layer configuration. Additionally, Figure 3 illustrates an enlarged schematic side view 570 of portion C shown in Figure 560, further highlighting the thin structured coating layer 544 between the first and second layers.

[0136] Additionally, embodiments in accordance with the present invention include a miniaturized wafer-level camera.

[0137] An embodiment according to the present invention comprises a miniature wafer-level camera with a wide field of view, which includes, or is composed of, a first glass substrate (e.g., 180 (FIG. 1), e.g., 540 (FIG. 3)) facing the object, followed by a replicated epoxy layer (e.g., layer 160 (FIG. 1), e.g., layer 382 (FIG. 2), e.g., layer 536 (FIG. 3)) with a first lens (e.g., 162 (FIG. 1), e.g., 386 (FIG. 2), e.g., 538 (FIG. 3)) with a concave aspherical surface facing the sensor side. This epoxy layer may also have posts / spacers integrated around the lens, for example, so that the next layer can be stacked on top. As an example, a corresponding molding structure, e.g., an additional molding structure, may comprise post spacers (e.g., posts / spacers) to form cavities between each lens surface (e.g., 150 (FIG. 1), e.g., 420 (FIG. 2), e.g., 540 (FIG. 3)). The first lens is followed by a replicated second lens (e.g., layer 110 (FIG. 1), e.g., layer 310 (FIG. 2), e.g., layer 522 (FIG. 3)) having a convex aspherical surface (e.g., 112 (FIG. 1), e.g., 312 (FIG. 2), e.g., 524 (FIG. 3)) and comprising or consisting of only epoxy. Optionally, once this second lens wafer (e.g., layer 110 (FIG. 1), e.g., layer 310 (FIG. 2), e.g., layer 522 (FIG. 3)) has been replicated, on the flat side, a black material, generally a coating layer (e.g., 140 (FIG. 1), e.g., 330 (FIG. 2), e.g., 544 (FIG. 3)), which can optionally be structured by a photolithography process and thus form apertures, can be structured or will be structured. As a next step, a third lens (e.g., layer 120 (FIG. 1), e.g., layer 340 (FIG. 2), e.g., layer 530 (FIG. 3)) that includes or is another convex aspherical lens structure (e.g., 124 (FIG. 1), e.g., 344 (FIG. 2), e.g., 534 (FIG. 3)) may be or will be replicated above the aperture.Both replicated convex layers may also have integrated posts, for example, to allow the wafers to be bonded together (e.g., to form respective cavities (150, 210 (Figure 1), 420, 450 (Figure 2), 540, 450 (Figure 3))).

[0138] This may also be one of the fundamental differences with conventional approaches, as shown for example in US Patent Application Publication No. 2017031089, which always use a glass substrate to replicate lenses 2 and 3 (e.g., compare with the example shown in Figure 3), or in most of the claims also use two glass substrates with an aperture structured in the center of both glass substrates.

[0139] Another way to optimize the performance of the lens design (and / or provide an alternative lens design) may be to split the lens 3 in two, which means first replicating a lens 3a with a concave surface (e.g. as shown in replication layer 2a in Figure 2) and a lens material (flint) with a low Abbe number, for example at least 1.5 and at most 2.0, for example 1.6, and for example less than 50, for example 28, and then creating an achromat by overmolding a convex layer, which is lens 3b (e.g. as shown in replication layer 2b in Figure 2) of a lens material (crown) with a refractive index of, for example, 1.52 or less and an Abbe number greater than 50, for example 52.

[0140] If the third lens already has integrated posts / spacers (e.g., to provide a cavity, e.g., 210 in FIG. 1c), another substrate (e.g., 202 in FIG. 1, e.g., 412 in FIG. 2, e.g., a glass substrate (e.g., a second glass substrate)) can be bonded to it. This second glass substrate can also be equipped with or include a wavelength filter, such as an NIR cut filter (e.g., 204 in FIG. 1, e.g., 414 in FIG. 2). One option is to place filter layers on both sides of the second glass substrate, e.g., to compensate for stress and / or thermal mismatch and minimize wafer warpage. Another option is to apply the filter on the second glass wafer only on the object side, structuring and applying it only to the optically required area, rather than across the entire wafer area.

[0141] Another option is for the glass substrate 2 to consist of or include a cavity etched in the direction of the third lens. In that case, the replicated third lens layer may not or need not have integrated posts / spacers, for example, since the lens fits into the cavity in the glass. However, both sides (the third lens layer and the etched cavity in the glass) can optionally be integrated and act as spacers.

[0142] Another method of creating spacers is to use glass spacers with integrated through-holes, which can be produced by, for example, etching, powder blasting and / or LIDE (laser-induced deep etching).

[0143] The spacers can also be fabricated by replicating the spacer structure on a glass substrate.

[0144] Once the entire optical stack is bonded together, the image sensor can be attached. The image sensor may have or include a cover glass that can be bonded directly to the image sensor surface. Because the image sensor may require microlenses per pixel to improve fill factor and minimize crosstalk, the image sensor may or will be coated with a low refractive index transparent material (low-n material) before the cover glass is applied to the wafer-level sensor, so that these microlenses are still optically functional even when completely covered with material. A cover glass may be bonded over the low-n material, which may then be bonded to the optical stack.

[0145] Furthermore, according to embodiments, as an optional feature, the curable material may be, for example, any material suitable for forming a layer, for example a replication layer. By way of example, the material may be curable, for example, by UV light (or by radiation in general) and / or by heat, for example by treatment with a defined temperature profile.

[0146] While some aspects have been described in the context of an apparatus, it will be apparent that these aspects also represent descriptions of corresponding methods, where a block or device corresponds to a method step or feature of a method step, and similarly, aspects described in the context of a method step also represent descriptions of a corresponding block or item or feature of a corresponding apparatus.

[0147] The above-described embodiments are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be apparent to those skilled in the art. It is therefore intended to be limited only by the scope of the appended claims and not by the specific details presented by way of illustration and description of the embodiments herein.

Claims

1. A projection optical system (100a-c, 500), a first layer (110, 310, 522) of a first curable material, a first optical lens surface (112, 312, 524) on a first side of the first layer at an optical axis (130, 360, 526) of the projection optical system; a flat portion (114, 528) on a second side of the first layer opposite the first side of the first layer at the optical axis; a first layer (110, 310, 522) of a first curable material; a second layer (120, 340, 530) of a second curable material, a planar portion (122, 532) on a first side of the second layer at the optical axis (130, 360, 526); a second optical lens surface (124, 344, 534) on a second side of the second layer opposite the first side of the second layer at the optical axis; a second layer (120, 340, 530) of a second curable material; Equipped with the planar portion (114, 528) of the first layer is adjacent to the planar portion (122, 532) of the second layer at the optical axis; or the planar portion (114, 528) of the first layer being separated from the planar portion (122, 532) of the second layer at the optical axis only by one or more coating layers (140, 330, 544); Projection optical system (100a-c, 500).

2. a first further layer (110c) of a first further hardening material, a first further optical lens surface (112c) on a first side of the first further layer at the optical axis (130, 360, 526) of the projection optical system; a flat portion (114c) on a second side of the first further layer opposite the first side of the first further layer at the optical axis; a first further layer (110c); and a second further layer (120c) of a second further hardenable material, a planar portion (122c) on a first side of the second further layer at the optical axis; a second further optical lens surface (124c) on a second side of the second further layer opposite the first side of the second further layer at the optical axis (130, 360, 526); a second further layer (120c); and Furthermore, the planar portion (114c) of the first further layer is adjacent to the planar portion (122c) of the second further layer at the optical axis, or the planar portion of the first further layer is separated from the planar portion of the second further layer at the optical axis only by one or more further coating layers (140c), the first further layer is adjacent to the second layer (120, 340, 530) on the second side of the second layer and on the first side of the first further layer; The projection optical system (100a-c, 500) according to claim 1.

3. the one or more coating layers (140, 330, 544) comprise a structured coating layer; and / or the one or more further coating layers (140c) comprise a structured coating layer; A projection optical system (100a-c, 500) according to claim 1 or 2.

4. at least one of the one or more coating layers (140, 330, 544) and / or the one or more further coating layers (140c) forms an aperture of the projection optical system; and / or at least one of the one or more coating layers and / or the one or more further coating layers forms a filter of the projection optical system; and / or at least one of the one or more coating layers and / or the one or more further coating layers form apertures and filters of the projection optical system; A projection optical system (100a-c, 500) according to any one of claims 1 to 3.

5. a cavity (150c) between the second optical lens surface (124, 344, 534) and the first further optical lens surface at the optical axis (130, 360, 526); The projection optical system according to claim 2 , further comprising:

6. an additional layer (160, 384, 536) of additional hardening material adjacent to the first layer (110, 310, 522) on the first side of the first layer and on a second side of the additional layer; the additional layer includes an additional optical lens surface (162, 386, 538) on the second side of the additional layer at the optical axis (130, 360, 526) of the projection optical system. A projection optical system (100a-c, 500) according to any one of claims 1 to 5.

7. a cavity (150, 420, 540) between the first optical lens surface (112, 312, 524) and the additional optical lens surface (162, 386, 538) at the optical axis (130, 360, 526); The projection optical system (100a-c, 500) of claim 6, further comprising:

8. an alignment structure (170) disposed on the first side of the first layer (110, 310, 522) and on the second side of the additional layer (160, 384, 536), the alignment structure (170) being configured to align the first layer and the additional layer such that the first optical lens surface (112, 312, 524) is aligned with the additional optical lens surface (162, 386, 538) at the optical axis (130, 360, 526); The projection optical system (100a-c, 500) according to claim 6 or 7, further comprising:

9. a support structure (180, 382, ​​382) adjacent to the additional layer (160, 384, 536) on a first side thereof opposite the second side thereof; １ , 382 ２ ) A projection optical system (100a-c, 500) according to any one of claims 6 to 8.

10. the support structure (180, 382) is a substrate; or the support structure (180, 382) is a forming structure; and / or The support structure (180, 382) is a forming structure (382) having a planar topology. １ , 382 ２ ) The projection optical system (100a-c, 500) according to claim 9.

11. a third layer (190, 370) of a third curable material, adjacent to said second layer (120, 340, 530) on said second side of said second layer and on a first side of said third layer; or adjacent to the second further layer on the second side of the second further layer and on the first side of the third layer; further comprising a third layer (190, 370); the third layer includes a third optical lens surface (192, 372) on a second side of the third layer opposite the first side along the optical axis (130, 360, 526) of the projection optical system; A projection optical system (100a-c, 500) according to any one of claims 1 to 10.

12. a back structure (200, 410, 546) and a cavity (210, 540, 548); Furthermore, a first surface of the back structure adjacent to the second layer (120, 340, 530) on the second side of the second layer, and the cavity (210, 540, 548) is disposed between the back structure and the second optical lens surface (124, 344, 534) at the optical axis (130, 360, 526); or a first surface of the back structure adjacent to the second further layer (120c) on the second side of the second further layer, and the cavity (210, 540, 548) being located between the back structure and the second further optical lens surface (124c) at the optical axis; or a first surface of the back structure adjacent to the third layer (190, 370) on the second side of the third layer, and the cavity (210, 540, 548) disposed between the back structure and the third optical lens surface (192, 372) at the optical axis; A projection optical system (100a-c, 500) according to any one of claims 1 to 11.

13. the rear structure (200, 410, 546) comprises a rear substrate (202, 412) and a filter (204, 414); The filter comprises a first filter structure (204) disposed on a first surface of the rear substrate. １ , 414 １ a second filter structure (204) comprising: the first filter structure forming the first surface of the rear structure; and the filter disposed on a second surface of the rear substrate opposite the first surface. ２ , 414 ２ ) or The filter comprises a first filter structure (204) disposed on a first surface of the rear substrate at least in the optical axis. １ , 414 １ ) wherein the first filter structure and the first surface of the rear substrate form the first surface of the rear structure. A projection optical system (100a-c, 500) according to claim 12.

14. The back structure (200, 410, 546) includes a compensation structure (206, 430, 430) configured to compensate for manufacturing tolerances and / or to set or improve the focus of the projection optical system. １ , 430 ２ , 430 ３ ) A projection optical system (100a-c, 500) according to claim 12.

15. The rear structure (200, 410, 546) includes a rear substrate (202, 412), a filter (204, 414), and a compensation structure (206, 430, 430). １ , 430 ２ , 430 ３ ) and the compensation structure is configured to compensate for manufacturing tolerances and / or to set or improve focus of the projection optical system; The filter comprises a first filter structure (204) disposed on a first surface of the rear substrate. １ , 414 １ ), wherein the filter comprises a second filter structure (204) disposed on a second surface of the rear substrate opposite to the first surface. ２ , 414 ２ ) or the filter comprises a first filter structure disposed on a first surface of the rear substrate at least at the optical axis, the first filter structure and the first surface of the rear substrate forming the first surface of the rear structure; the compensation structure comprises a first surface and a second surface, the second surface being opposite the first surface; the first surface of the first filter structure and / or the back structure is adjacent to the second surface of the compensation structure such that the first surface of the compensation structure forms the first surface of the back structure; or the first surface of the compensation structure abuts the second side of the second filter structure or the rear substrate such that the first surface of the first filter structure and / or the rear substrate forms the first surface of the rear structure. A projection optical system (100a-c, 500) according to claim 12.

16. the compensation structure is a universal compensation structure (206, 430) configured to compensate for manufacturing tolerances and / or to set or improve the focus of multiple projection optical systems on average; Projection optical system (100a-c, 500) according to any one of claims 14 or 15.

17. The compensation structures may include individual compensation structures (430) configured to compensate for manufacturing tolerances and / or to set or improve the focus of the projection optical system. １ , 430 ２ , 430 ３ ) Projection optical system (100a-c, 500) according to any one of claims 14 or 15.

18. the projection optics comprises a lateral size in the plane of the first layer (110, 310, 522) of at least 100 μm, or at least 200 μm, or at least 300 μm, or at least 0.5 mm, and / or at most 2 mm, or at most 3 mm, or at most 5 mm; and / or the projection optics comprises a height perpendicular to the first and second layers (120, 340, 530) of at least 0.5 mm, or at least 1 mm, or at least 2 mm, or at most 2 mm, or at most 3 mm, or at most 5 mm; A projection optical system (100a-c, 500) according to any one of claims 1 to 17.

19. at least two successive layers of the projection optical system include different optical properties; an optical lens surface of a first layer of the two consecutive layers includes a high refractive index and low dispersion, and an optical lens surface of a second layer of the two consecutive layers facing the optical lens surface of the first layer of the two consecutive layers includes a low refractive index and low dispersion to form an achromat; A projection optical system (100a-c, 500) according to any one of claims 1 to 18.

20. A method for manufacturing an optical structure (100a-c, 500), comprising the steps of: forming a first layer (110, 310, 522) of the optical structure, the forming the first layer comprising forming and curing a first curable material on a first molding structure (320) to form the first layer, thereby forming a first optical lens surface (112, 312, 524) on a first side of the first layer adjacent the first molding structure; forming a first layer (110, 310, 522); while the first layer is adjacent the first forming structure on the first side of the first layer; providing a second layer (120, 340, 530) of the optical structure on a second side of the first layer opposite the first side; Including, method.

21. providing the second layer (120, 340, 530); forming and curing a second curable material on the second side (110, 310, 522) of the first layer using a second forming structure (350) to form the second layer; whereby the second layer is adjacent the second shaped structure and a second optical lens surface (124, 344, 534) is formed on a second side of the second layer opposite the second side of the first layer; aligning the second optical lens surface with the first optical lens surface at an optical axis of the optical structure; 21. The method of claim 20.

22. forming a first further layer of the optical structure (100a-c, 500), the step of forming the first further layer comprising: forming and curing a first further curable material on a first further shaping structure to form the first further layer, whereby a first further optical lens surface is formed on a first side of the first further layer where the first further layer is adjacent the first further shaping structure; forming a first further layer; while the first further layer is adjacent the first further forming structure on the first side of the first further layer; providing a second further layer of the optical structure (100a-c, 500) on a second side of the first further layer opposite to the first side, providing the second further layer; forming and curing a second additional curable material on the second side of the first additional layer using a second additional forming structure to form the second additional layer; whereby the second further layer is adjacent the second further shaped structure and a second further optical lens surface is formed on a second side of the second further layer facing away from the second side of the first further layer; the second further optical lens surface being aligned with the first further optical lens surface at the optical axis (130, 360, 526) of the optical structure. providing a second further layer; removing the first further shaping structure; removing the second forming structure (350); bonding said first further layer to said second layer (120, 340, 530); whereby the first further layer is adjacent to the second layer on the second side of the second layer and on the first side of the first further layer; aligning the first further optical lens surface with the second optical lens surface (124, 344, 534) at the optical axis of the optical structure (100a-c, 500); 22. The method of claim 21 further comprising:

23. the first further optical lens surface and the second optical lens surface (124, 344, 534) are formed such that the optical structure (100a-c, 500) comprises a cavity (150c) between the first further optical lens surface and the second optical lens surface at the optical axis (130, 360, 526) of the optical structure; 22. The method of claim 21.

24. providing one or more coating layers (140, 330, 544) between said first layer and said second layer (120, 340, 530); and / or providing one or more further coating layers (140c) between said first further layer and said second further layer; 24. The method of any one of claims 20 to 23, further comprising:

25. structuring at least one of said one or more coating layers (140, 330, 544) and / or said one or more further coating layers (140c), 25. The method of claim 24, further comprising:

26. the coating layer thickness of the one or more coating layers (140, 330, 544) and / or of the one or more further coating layers (140c) between the first layer and the second layer and / or between the first further layer and the second further layer is at most 10%, or at most 5%, or at most 2%, or at most 1% of the thickness of the first layer (110, 310, 522), or the thickness of the second layer (120, 340, 530), and / or the thickness of the first further layer, or the thickness of the second further layer, respectively; 26. The method of any one of claims 24 or 25.

27. at least one of the one or more coating layers (140, 330, 544) and / or the one or more further coating layers (140c) forms an aperture of the projection optical system; and / or at least one of the one or more coating layers and / or the one or more further coating layers forms a filter of the projection optical system; and / or at least one of the one or more coating layers and / or the one or more further coating layers form apertures and filters of the projection optical system; 27. The method of any one of claims 24 to 26.

28. removing the first forming structure (320) from the first layer (110, 310, 522); Providing an optical substructure (380), The optical substructures are supported by a support structure (180, 382, ​​382 １ , 382 ２ ) and an additional layer (160, 384, 536) of said optical structure (100a-c, 500), providing the optical substructure, To form the additional layers of the optical substructure, an additional forming structure (390) and the support structure (180, 382, ​​382) are １ , 382 ２ ) and hardening additional hardenable material therebetween; whereby an additional optical lens surface (162, 386, 538) is formed on a second side of the additional layer where the additional layer is adjacent the additional shaped structure; the additional layer including a step adjacent the support structure on a first side of the additional layer opposite the second side of the additional layer; Providing an optical substructure (380); removing the additional shaping structure; bonding said additional layer (160, 384, 536) to said first layer (110, 310, 522); whereby the additional layer is adjacent to the first layer on the first side of the first layer and on the second side of the additional layer; aligning the additional optical lens surface (162, 386, 538) with the first optical lens surface (112, 312, 524) at the optical axis (130, 360, 526) of the optical structure (100a-c, 500); 28. The method of any one of claims 20 to 27, further comprising:

29. The additional layer (160, 384, 536) is then removed from the support structure (180, 382, ​​382). １ , 382 ２ ), 29. The method of claim 28.

30. the support structure (180, 382) is a substrate; or the support structure (180, 382) is a forming structure; and / or The support structure (180, 382) is a forming structure (382) having a planar topology. １ , 382 ２ ) 30. The method of any one of claims 28 or 29.

31. the first optical lens surface (112, 312, 524) and the additional optical lens surface (162, 386, 538) are formed such that the optical structure (100a-c, 500) comprises a cavity (150, 420, 540) between the first optical lens surface and the additional optical lens surface at the optical axis (130, 360, 526) of the optical structure; 31. The method of any one of claims 28 to 30.

32. removing the second shaping structure (350) from the second layer (120, 340, 530) and bonding a first surface of the back structure (200, 410, 546) to the second layer on the second side of the second layer such that the second optical lens surface (124, 344, 534) and the first surface of the back structure form a cavity (210, 540, 548) at the optical axis; or removing the second further shaped structure from the second further layer and bonding a first surface of the back structure (200, 410, 546) to the second further layer on the second side of the second further layer such that the second further optical lens surface (124, 344, 534) and the first surface of the back structure form a cavity (210, 540, 548) at the optical axis; 32. The method of any one of claims 20 to 31, further comprising:

33. providing a third layer (190, 370) of the optical structure (100a-c, 500) on the second side of the second layer (120, 340, 530), the step of providing the third layer comprising: removing the second forming structure (350) from the second layer; and forming and curing a third curable material on the second side of the second layer between the second layer and a third forming structure (350a) to form the third layer; whereby a third optical lens surface (192, 372) is formed on a first side of the third layer where the third layer is adjacent to the second layer and on a second side of the third layer facing away from the first side of the third layer where the third layer is adjacent to the third molding structure; aligning the first optical lens surface (112, 312, 524) with the third optical lens surface at the optical axis (130, 360, 526) of the optical structure; providing a third layer (190, 370); or providing a third layer (190, 370) of the optical structure (100a-c, 500) on the second side of the second further layer, the step of providing the third layer comprising: removing the second further shaped structure from the second layer; and forming and curing a third curable material on the second side of the second further layer between the second further layer and a third forming structure (350a) to form the third layer; whereby a third optical lens surface (192, 372) is formed on a first side of the third layer where the third layer is adjacent to the second further layer and on a second side of the third layer facing away from the first side of the third layer where the third layer is adjacent to the third shaping structure; aligning the first optical lens surface (112, 312, 524) with the third optical lens surface at the optical axis (130, 360, 526) of the optical structure; providing a third layer (190, 370); 33. The method of any one of claims 20 to 32, further comprising:

34. the third layer (190, 370) is disposed between the first layer (110, 310, 522) and adjacent the first forming structure (320) on the first side of the first layer; 34. The method of claim 33.

35. removing the third forming structure (350a) from the third layer (190, 370); bonding a first surface of a back structure (200, 410, 546) to the third layer on the second side of the third layer, whereby the third optical lens surface (192, 372) and the first surface of the back structure form a cavity (210, 540, 548); 35. The method of claim 33 or 34, further comprising:

36. The cavity is a recess in the second layer; a recess in said second further layer, a recess in the third layer; a recess in the rear structure; a through hole in the rear structure, and / or a through hole in the compensation structure of the rear structure; formed at least in part by at least one of 36. The method of claim 32 or 35.

37. The recesses and / or through holes are produced by at least one of etching, powder blasting and / or laser-induced deep etching (LIDE); 37. The method of claim 36.

38. the rear structure (200, 410, 546) comprises a rear substrate (202, 412) and a filter (204, 414); The filter comprises a first filter structure (204) disposed on a first surface of the rear substrate. １ , 414 １ a second filter structure (204) comprising: the first filter structure forming the first surface of the rear structure; and the filter disposed on a second surface of the rear substrate opposite the first surface. ２ , 414 ２ ) or The filter comprises a first filter structure (204) disposed on a first surface of the rear substrate at least in the optical axis. １ , 414 １ ) wherein the first filter structure and the first surface of the rear substrate form the first surface of the rear structure.

38. The method of any one of claims 32 or 35 to 37.

39. said back structure (200, 410, 546) having a compensation structure (206, 430, 430) configured to compensate for manufacturing tolerances and / or to set or improve the focus of said optical structure (100a-c, 500); １ , 430 ２ , 430 ３ ) 38. The method of any one of claims 32 or 35 to 37.

40. 38. The method of any one of claims 32 or 35 to 37, comprising: The rear structure (200, 410, 546) includes a rear substrate (202, 412), a filter (204, 414), and a compensation structure (206, 430, 430). １ , 430 ２ , 430 ３ ) and the compensation structure is configured to compensate for manufacturing tolerances and / or to set or improve the focus of the optical structure (100a-c, 500), The filter comprises a first filter structure (204) disposed on a first surface of the rear substrate. １ , 414 １ ), wherein the filter comprises a second filter structure (204) disposed on a second surface of the rear substrate opposite to the first surface. ２ , 414 ２ ) or the filter comprises a first filter structure disposed on a first surface of the rear substrate at least at the optical axis, the first filter structure and the first surface of the rear substrate forming the first surface of the rear structure; the compensation structure comprises a first surface and a second surface, the second surface being opposite the first surface; The method comprises: bonding the first surface of the first filter structure and / or the back substrate to the second surface of the compensation structure such that the first surface of the compensation structure forms the first surface of the back structure; or bonding the first surface of the compensation structure to the second side of the second filter structure or the back substrate such that the first surface of the first filter structure and / or the back substrate forms the first surface of the back structure; further comprising: method.

41. 41. The method of any one of claims 20 to 40, the method is performed at wafer level to provide a plurality of optical structures (100a-c, 500); and / or The method is carried out to obtain a plurality of optical structures (100a-c, 500) in an array arrangement, method.

42. 41. The method of any one of claims 29 or 40, comprising: the method is performed at wafer level to provide a plurality of optical structures (100a-c, 500); and / or the method is carried out to obtain a plurality of optical structures (100a-c, 500) in an array arrangement, The method includes determining a plurality of sets of parameters, each set characterizing an optical structure of the plurality of optical structures; providing the compensation structure as a generic compensation structure (206, 430) for use with each of the optical structures of the set of optical structures; further comprising providing the compensation structure includes adjusting the compensation structure based on the determined plurality of parameter sets to compensate for manufacturing tolerances and / or to set or improve, on average, the focus of the set of optical structures; method.

43. 41. The method of any one of claims 39 or 40, comprising: the method is performed at wafer level to provide a plurality of optical structures (100a-c, 500); and / or the method is carried out to obtain a plurality of optical structures (100a-c, 500) in an array arrangement, The method comprises: determining a plurality of sets of parameters, each set characterizing one optical structure of the plurality of optical structures; a compensation structure (430) for each of the optical structures of the set of optical structures; １ , 430 ２ , 430 ３ ) providing a adjusting each individual compensation structure based on a respective set of parameters to compensate for manufacturing tolerances and / or to set or improve the focus of each optical structure; further comprising: method.

44. 44. The method of any one of claims 20 to 43, comprising: the method is performed at wafer level to provide a plurality of optical structures (100a-c, 500); and / or the method is carried out to obtain a plurality of optical structures (100a-c, 500) in an array arrangement, The method comprises: further comprising the step of dicing to separate optical structures of the plurality of optical structures. method.

45. bonding a sensor structure (220, 440) to the optical structure (100a-c, 500); 45. The method of any one of claims 20 to 44, further comprising:

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