Multilayer optical unit

Abstract

We disclose an optical device including an optical stack. The optical stack includes a first substrate layer, a second substrate layer, and an optical medium located between the first substrate layer and the second substrate layer. The optical stack is bent so that the second portion of the optical stack extends behind the first portion of the optical stack.

Description

Technical Field

[0001] The present disclosure relates to optical devices, and in particular, but not exclusively, to multi-layer liquid crystal optical devices manufactured using a single monolithic process. Background Art

[0002] Liquid crystal optics use multiple stacked liquid crystal cells, and the power of these optics can be increased by further stacking a greater number of cells.

[0003] Stacking multiple units on top of each other requires multiple connections, each of which adds cost, complexity, takes up space, and reduces yield.

[0004] Figure 1 A prior art liquid crystal optical device is shown, comprising n liquid crystal cells stacked on top of each other. A plurality of connections are used to connect to each optical cell, and adhesive is used between each optical cell in the liquid crystal cell stack.

[0005] One current solution is to introduce vias through the substrate layer to allow connection to the optical unit; however, this also further increases complexity and cost. Summary of the invention

[0006] An object of the present disclosure is to provide a multilayer optical unit that can be manufactured using a single monolithic process.

[0007] The devices of the present disclosure are advantageous over prior art devices for the following reasons:

[0008] The invention aims to create a longer single unit and fold it back onto itself, rather than creating multiple units and separate connections;

[0009] This allows a single process to create multiple complete units;

[0010] It also allows the creation of very complex stacks in a single monolithic layer.

[0011] Small angles can be added to the fold, which allows multiple optical designs to be created using a single industrial process;

[0012] Different glue patterns can isolate cells for different form factors, shapes and designs. Bond lines can be used to separate individual optical cells, or alternatively seal only at the perimeter (thus reducing the possibility of glue mixing);

[0013] A single connection can be made to a large number of stacked units;

[0014] The method scales to as many layers as needed;

[0015] The optical device can be used for LC displays, optical devices or sensors, and can be used for virtual reality (VR) displays.

[0016] According to a first aspect of the present disclosure, an optical device is provided, the device comprising: an optical stack, wherein the optical stack comprises: a first substrate layer; a second substrate layer; an optical medium located between the first substrate layer and the second substrate layer; wherein the optical stack is bent so that the second portion of the optical stack extends behind the first portion of the optical stack. This provides a multilayer optical unit device using a single process. The optical device can be used for an optical device, a display, or a sensor.

[0017] The optical medium may be a liquid crystal layer.

[0018] The first portion of the optical stack can be substantially parallel to the second portion of the optical stack.

[0019] Each portion of the optical stack may form an optical unit.

[0020] The optical cell may be a liquid crystal cell or an organic photodiode (OPD).

[0021] Each of the first substrate layer and the second substrate layer may comprise a single continuous substrate layer forming both the first and second parts of the optical stack. In other words, each substrate layer may extend through all optical units in the optical device.

[0022] The first substrate layer can be spaced apart from the second substrate layer in a first dimension, and the first portion of the optical stack can be spaced apart from the second portion of the optical stack in the first dimension. In other words, within each optical unit, the first substrate layer is on top of the second substrate layer. When the device is bent, the optical units can then be stacked on top of each other.

[0023] The first substrate layer may include an upper substrate layer of the first portion of the stack and a lower substrate layer of the second portion of the stack; and the second substrate layer may include a lower substrate layer of the first portion of the stack and an upper substrate layer of the second portion of the stack. In other words, the first substrate layer may form a top layer of the first optical unit and a bottom layer of the second optical unit, and the second substrate layer may form a bottom layer of the first optical unit and a top layer of the second optical unit. A single substrate layer may be a substrate layer of two optical units, but may be a top layer of one optical unit and a bottom layer of another optical unit.

[0024] The optical stack can be bent at an angle of about 180°. This allows the optical units to be essentially flat with respect to each other.

[0025] The optical device may also include an electrical connection coupled to the first substrate layer and the second substrate layer, and the electrical connection may be located on a single side of the optical stack. In other words, when the optical device stack is bent, the electrical connection may be to a single optical unit. This reduces the number of electrical connections required for the optical device.

[0026] Alternatively, the optical device may further include an electrical connection coupled to the first substrate layer and the second substrate layer, and the electrical connection may be provided to each portion of the optical device stack. In other words, an electrical connection may be provided to each optical unit. This may protect the electrical connection from breaking when the optical device stack is bent.

[0027] The electrical connections may include aluminum. Alternatively, the electrical connections may include any metal or alloy suitable for sputtering or similar type deposition, such as molybdenum, nickel, silver, gold and alloys thereof. The electrical connections may include indium titanium oxide (ITO). Aluminum - or other example metals and alloys - may be used because they are more ductile than ITO, thereby protecting the electrical connections from breaking when the optical device stack is bent. Alternatively, screen-printable conductive silver traces may be used for the electrical connections. This may be applied on the outside of the optical unit in a manner similar to conventional touch screen routing. Multiple "touch sensor-like" screen-printable conductive silver traces may be formed on one edge of the folded unit stack.

[0028] Alternatively or additionally, an enhanced, highly conductive trace or route may be formed along the length of the optical device stack when unfolded. Such a trace may comprise metal or may comprise another conductive material. This is advantageous when there are many cells within the optical device stack (strip) and connections are made only on the short edges. Such a trace improves the electrical connection because the conductivity of the ITO alone may not be sufficient to switch all cells - especially cells at the ends of the strip. In this case, preferably the conductive material may be ductile to withstand the folding at the boundaries of each optical cell.

[0029] The optical device may also include one or more intermediate transparent layers located between adjacent portions of the optical stack.

[0030] The intermediate transparent layer may be an adhesive layer. The adhesive layer ensures that the optical components remain properly aligned, any unwanted air gaps are removed from the final optical stack, and that adjacent optical elements are spaced apart at a desired distance. The adhesive may be a liquid adhesive or may be a sheet adhesive.

[0031] The intermediate layer may be located between the first portion of the second substrate layer and the second portion of the second substrate layer. In other words, the intermediate layer may be located between the bottom layer of the first optical unit and the top layer of the second optical unit. The optical device stack may be curved so that the intermediate layer is located between adjacent portions of one substrate layer.

[0032] The optical device stack can be bent around the intermediate layer. The intermediate layer can determine the curvature of the optical device stack. The thickness of the optical device and the distance between adjacent optical units can depend on the thickness of the intermediate layer, and therefore, the thickness of the intermediate layer can be changed to change the properties of the optical device.

[0033] The intermediate transparent layer may have a refractive index substantially the same as that of the optical medium. The intermediate layer may include a non-birefringent material. Thus, the intermediate layer does not change the optical properties of the optical device and minimizes reflections within the device.

[0034] In addition, the optical device stack may include other adhesives that form a glue frame or seal. The glue frame may be configured to isolate the individual optical units in order to enhance mechanical robustness.

[0035] Alternatively, the glue frame can be configured to allow the cell gap to continue over the bend. When unfolded, the glue seal can be formed only around the periphery of the entire optic stack. This reduces complexity for manufacturing and reduces the fragility of the optics. Having a glue frame only around the periphery of the optic stack means that less rigid material is located at the bend, allowing for a narrower bezel.

[0036] The optical device may include at least four optical units, each of which may be parallel to each other, and each of which may extend behind an adjacent optical unit. Alternatively, the optical device may have fewer than four optical units or more than four optical units. The number of optical units may be selected depending on user requirements; however, any number of optical units may be manufactured in a single process. The optical medium within each optical unit may be individually contained, or may be a single layer of continuous optical medium.

[0037] The optical stack can be bent so that it has a corrugated shape. The corrugated shape can also be described as an accordion shape. The corrugated shape can be a series of alternating parallel ridges and grooves, or alternating folds in opposite directions. The accordion shape ensures that the stresses in the cell are reset each time the optical stack is bent in one direction and then in the other direction. The alternating directions of curvature ensure that neither substrate is stretched significantly relative to the other, thus preventing wrinkling.

[0038] Alternatively, the optical stack could be curved so that it has a spiral shape, however a constant direction of curvature would mean that the "outer substrate" would be stretched relative to the inside and possibly wrinkled.

[0039] Each section of an optical stack can form an optical lens. Stacking optical lenses can form a more powerful optical lens. The number of optical units or sections can be changed to change the overall power of the optical lens.

[0040] The substrate layer may comprise a plastic material. The substrate may comprise a flexible material. This allows the entire optical device stack to be flexible and bend to form the optical device. Using glass as used in prior art devices would not be feasible. The substrate layer may comprise a TAC film, polyimide (PI) or cycloolefin polymer (COP). The substrate layer may also comprise other plastic materials not listed. TAC has the same birefringence as glass, but is thinner, which means better overall optical performance than glass (as well as being thinner, lighter and shatterproof). TAC is flexible, therefore allowing for a minimum radius of curvature for bends within the optical device. Alternatively, the substrate layer may comprise any flexible substrate material.

[0041] The optical medium may include aligned domains. This alignment of the domains may be changed to change the optical properties of each portion of the optical device stack and the entire optical device. The domains may include liquid crystals. The liquid crystal (LC) alignment direction may be configured to be different for each optical cell. Each optical cell will be differentially exposed by masking all areas except the area currently to be exposed while unfolding the optical device stack. No additional inter-cell seal is required to achieve this.

[0042] Each portion of the optical device stack can be square when folded. Alternatively, each portion of the optical device stack can be rectangular, circular, or elliptical when folded. The optical cells within the optical device can have a square, rectangular, circular, elliptical, or other shape. The optical cells can have a generally circular, elliptical, or other shape that includes at least one flat edge to provide an area for bending the optical stack.

[0043] According to another aspect of the present disclosure, there is provided an eyeglass device comprising two optical devices as described above. The domain of the first optical device can be aligned along a first direction, and the domain of the second optical device can be aligned along a second direction. This allows each eye of the eyeglass device to have different optical properties, which can be used for 3-dimensional glasses.

[0044] According to another aspect of the present disclosure, a method for manufacturing an optical device is provided, the method comprising: forming an optical stack, wherein the optical stack comprises: a first substrate layer, a second substrate layer, an optical medium located between the first substrate layer and the second substrate layer; and bending the optical stack so that the second portion of the optical stack extends behind the first portion of the optical stack. The method allows multiple optical units to be manufactured in a stack using a single manufacturing process. This reduces manufacturing complexity and reduces manufacturing costs.

[0045] Prior to bending the optical stack, the method may further include: aligning the optical medium within the first portion of the optical stack along a first direction using a photolithography mask, and aligning the optical medium within the second portion of the optical stack along a second direction using a photolithography mask. This allows alignment of domains within the optical medium, and all optical units can be aligned in a single step.

[0046] Bending the stack of optical devices may include using rods to bend around them and / or inserting spacers between adjacent layers. A tool similar to a sheet metal bender can perform the first bend. Preferably, this can be done in a vacuum if a sheet adhesive or liquid adhesive is used to adhere the cells on either side of the fold. Once the first fold is performed, the next fold can be performed in the opposite direction. The initial fold can be configured to be "loose" or not too tight, and then a final press can be performed to obtain the final cell stack.

[0047] Alternatively, the optics stack may be rolled into a spiral and then pressed or flattened. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Some preferred embodiments of the present disclosure will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0049] Figure 1 shows a schematic cross section of an optical device stack according to the prior art;

[0050] Figure 2 shows a schematic cross section of an optical device stack according to an embodiment of the present disclosure;

[0051] Figure 3 shows a schematic cross-section of an optical device stack according to an embodiment of the present disclosure, wherein an optical unit is shown;

[0052] Figure 4 shows a plan view of an optical device according to a first embodiment of the present disclosure, wherein the optical device has electrical connections to each portion of the device stack, and wherein the optical device is shown prior to folding;

[0053] FIG5( a ) shows a top view of an optical device according to a first embodiment of the present disclosure, wherein the optical device has electrical connections to each portion of the device stack and wherein a folded optical device is shown;

[0054] FIG5( b ) shows a perspective view of an optical device according to a first embodiment of the present disclosure, wherein the optical device has electrical connections to each portion of the device stack, and wherein a folded optical device is shown;

[0055] Figure 6shows a plan view of an optical device according to other embodiments of the present disclosure, wherein electrical connections are provided to a single portion of the device stack, and wherein the optical device is shown prior to folding;

[0056] Figure 7 shows a perspective view of an optical device according to another embodiment of the present disclosure, wherein the optical device has electrical connections to a single portion of a device stack, and wherein a folded optical device is shown;

[0057] Figure 8 (a) to Figure 8 (d) shows perspective views of optical devices according to other embodiments of the present disclosure. These figures show the optical device at four stages of the bending process during manufacturing;

[0058] Fig. 9 Fig.12 A plan view of electrical routing or traces for electrical connections is shown instead of, or in addition to, the electrical connections of previous embodiments. DETAILED DESCRIPTION

[0059] Embodiments will now be described by way of example only.

[0060] Figure 2 A schematic cross-section of an optics stack according to an embodiment of the present disclosure is shown.

[0061] The optical device stack comprises two substrate layers: a first substrate layer 105 and a second substrate layer 110. The second substrate layer 110 is arranged parallel to the first substrate layer 105. A liquid crystal (LC) layer 115 extends between the two substrate layers 105, 110. In this embodiment, a liquid crystal layer is used, but this could be a layer of a different optical medium, such as a layer of an organic photodiode (OPD).

[0062] The optics stack is bent so that it has an accordion shape or a corrugated shape, where a portion of the optics stack on one side of the bend extends behind a portion of the optics stack on the other side of the bend. For example, a single bend would form a C-shape, two bends would be used to form an S-shape, or three or more bends would be used to form a corrugated shape, such as Figure 2 shown.

[0063] The optics stack is a single continuous stack extending around each bend. Thus, a first portion of the optics stack will be adjacent to and on top of a second portion of the optics stack when bent, wherein the first portion of the optics stack is laterally adjacent to the second portion of the optics stack when flat. The first substrate layer 105 will form the top substrate layer for cell 1 and the bottom substrate layer for cell 2. The second substrate layer 110 will form the bottom substrate layer for cell 1 and the top substrate layer for cell 2.

[0064] Each portion of the optical device stack can be defined as a portion of the optical device stack located between two adjacent bends of the optical device stack. Each portion of the optical device stack includes a portion of the first substrate 105, a portion of the second substrate 110, and a portion of the optical medium 115, and thus forms an optical unit. Figure 2 In the embodiment shown, the optical cell is a liquid crystal cell, however this could also be an organic photodiode (OPD).

[0065] A liquid crystal edge seal 135 is located between the first substrate layer 105 and the second substrate layer 110, however it is only required at the end optical cells (cell 1 and cell n).

[0066] In the present embodiment, the first substrate layer 105 and the second substrate layer 110 are triacetyl cellulose (TAC) films. The TAC film can be replaced by any suitable flexible substrate material. For some applications, it is preferred to select a non-birefringent material, such as polyimide (PI) or cycloolefin polymer (COP). TAC has the same birefringence as glass, but is thinner, which means that it has better overall performance than glass optically (as well as being thinner, lighter and shatterproof). TAC is flexible, so it allows for a minimum radius of curvature for bends within an optical device.

[0067] When bent, adjacent portions of the optical device stack (optical cells) are separated by an optically clear adhesive (OCA) 120. The thickness of the substrate layers 105, 110 and the thickness of the OCA 120 determine the curvature of the bend between adjacent portions of the optical device stack and determine the vertical separation between adjacent portions of the optical device stack. The adhesive 120 must be optically clear to allow light to pass between adjacent portions of the optical device stack. Since the adhesive 120 is not used across the entire width of each portion of the optical device stack (i.e., only at the bend), the adhesive 120 is not used over the entire width of each portion of the optical device stack (i.e., only at the bend). Figure 1 This uses less adhesive to form the optical device stack than shown in .

[0068] A first electrode 125 is formed on a first end of the first substrate layer 105, and a second electrode 130 is formed on a second end of the second substrate layer 110. In the present embodiment, the electrodes 125, 130 are indium tin oxide (ITO) electrodes patterned on the substrate layers 105, 110. In other embodiments, aluminum (or other metals and alloys - as previously described) may be used to reinforce the electrodes 105, 110 as this is more ductile and resistant to bending.

[0069] Both electrodes 125, 130 can be formed on a single side of the optical device stack, which allows the optical devices to be connected more easily. In addition, only one pair of electrodes is required for all optical units within the optical device stack, thus reducing the number of contacts required. Alternatively, individual electrode contacts for each optical unit can be formed on a single side and edge of the optical stack, such as Figure 4 As shown, or when unfolded an enhanced, highly conductive trace or routing (not shown) can be formed along the length of the optical device stack.

[0070] Figure 3 A schematic cross section of an optics stack according to an embodiment of the present disclosure is shown, wherein an optical cell is shown. The area of ​​the optical stack between lines A and A' corresponds to the area of ​​the optical cell. In this optical cell area, the optics stack is flat, and each optical cell is parallel to each optical cell above and below. The bend of the optics is outside the optical cell. Electrical connections 125, 130 and liquid crystal edge seal 135 are outside the area of ​​the optical cell.

[0071] Figure 2 and Figure 3 The optics are not shown to scale, but rather schematically a cross section of the device. In a physical device, the area of ​​the optical cells will be much larger than the area used for bending and connecting. In a manufactured device, the folds between the optical cells will have an angle of 180 degrees. After bending the optical stack, the device will be flattened, which can be done in a vacuum press. This ensures that the optical cells are all parallel to each other.

[0072] Figure 4 A plan view of an optical device according to one embodiment of the present disclosure is shown, wherein the optical device has electrical connections to each portion of the device stack. The figure shows a flat pattern of the optical device before folding, wherein portions of the optical device stack are laterally spaced apart from each other.

[0073] In this embodiment, each optical unit has electrical connections 140, 145 on both sides of each optical unit. The electrodes 140 on one side of the optical device stack are connected to the first substrate layer, while the electrodes 145 on the opposite side of the optical device stack are connected to the second substrate layer. Figure 2 and Figure 3 Compared to the embodiment shown, electrical connections 140, 145 are formed on both sides of each optical unit perpendicular to the fold of the optical device stack. These electrodes 140, 145 can be used when there is a risk of patterned ITO electrodes or metal routing cracking when bending. Since each optical unit has a discrete electrical connection, the electrical connection does not need to extend around the fold and does not have to bend itself, and is therefore protected when the optical device stack is bent.

[0074] The electrical connections 140, 145 are staggered along the edge of each optical unit so that they do not overlap and are laterally spaced apart from each other when the optical device stack is bent. This allows for easier connections. Contact can be made to the top and bottom substrate layers of each optical unit without the electrodes 140, 145 being broken by bending.

[0075] FIG5(a) shows a top view of an optical device according to a first embodiment of the present disclosure, wherein the optical device has electrical connections to each portion of the device stack. Figure 4 An optical device, wherein the optical device is shown as folded. Figure 4 As shown, the electrical connections along each side are staggered such that when the optical device stack is bent, the electrical connections along each side are laterally spaced apart from each other.

[0076] Alternatively, along the top (or bottom) edge of the optical device stack, the electrical connections can also alternate between top and bottom contacts, or at alternating ends of that edge. This means that all contacts on one edge of the folded device will face the same direction, rather than being grouped as shown in Figure 5(a).

[0077] Figure 5(b) shows a perspective view of an optical device according to a first embodiment of the present disclosure, wherein the optical device has electrical connections to each portion of the device stack and wherein a folded optical device is shown. This figure shows the optical device of Figure 5(a).

[0078] Figure 6 A plan view of an optical device according to other embodiments of the present disclosure is shown, wherein electrical connections are provided to a single portion of the device stack, and wherein the optical device is shown prior to folding. In this embodiment, electrical connections 125, 130 are provided to only one optical unit, which is an end optical unit. This would be unit 1 or unit n, as shown in FIG. Figure 2 Each electrical connection 125, 130 extends through all cells, through each fold of the device. This forms an "all-at-once switching" device.

[0079] There may be other numbers of connections (eg, one connection per cell or any other number of connections), and the top contact may be lowered to a bottom position to facilitate flex tail bonding using a z-axis conductive adhesive.

[0080] Figure 7 A perspective view of an optical device according to another embodiment of the present disclosure is shown, wherein the optical device has electrical connections to a single portion of a device stack and wherein a folded optical device is shown. Figure 6 Optical devices.

[0081] Figure 8(a) to Figure 8 (d) shows a perspective view of an optical device according to other embodiments of the present disclosure. Figure 6 and Figure 7 An optic at four stages of the bending process during manufacturing.

[0082] Fig. 9 FIG. 1 shows a plan view of an optical device according to an embodiment of the present disclosure, wherein electrical connections are provided at both ends of the electronic device stack. Figure 2 and Figure 3 The optics before folding.

[0083] Fig.10 A plan view of an optical device according to an embodiment of the present disclosure is shown, showing the adhesive and folding points of the device before folding. At points 805, 815 and 825, the optical device stack is folded downward to form a valley fold. At points 810 and 820, the optical device stack is folded upward to form a mountain fold. In this way, the optical device stack is folded to form an accordion or corrugated shape. It is then flattened so that each fold is 180°. Adhesive is applied to the top surfaces of alternating optical cells and the bottom surfaces of other alternating optical cells (where adhesive has not yet been applied to the top surfaces) so that when the optical device is folded, the adhesive is disposed between the entire optical device. Edge seals prevent LC from detaching from the cells. In this embodiment, there is a rectangular edge seal 850 around the perimeter of the entire optical device stack containing all optical cells. Other edge seals 855 between adjacent optical cells are also shown, although some embodiments may only include peripheral edge seals 850.

[0084] Fig.11 A plan view of an optical device according to an embodiment of the present disclosure is shown, showing a mask used to align the optical medium before folding. For each cell, the polarization angle of the UV exposure is changed, and only one optical cell is exposed at a time using a mask. This allows each cell to have a different arbitrary liquid crystal alignment direction. This shows Figure 6 or Fig. 9 although the method may be equally applied to any of the other embodiments shown.

[0085] Fig.12A plan view of electrical routing or traces for electrical connections is shown, rather than electrical connections, or in addition to the electrical connections of the previous embodiments. This includes flexible connectors 1260 that electrically engage the substrate of the device stack, and electrical routing 1265 to the top and bottom of each optical unit. The electrical routing material 1265 can be reinforced or replaced with a more ductile material near the bends / folds of the optical device. The ITO / transparent conductor 1265 can also be patterned so that it will not break especially at the folds, thereby retaining a ductile connector only in the area of ​​the fold.

[0086] The skilled artisan will appreciate that in the foregoing description and the appended claims, positional terms such as "above," "overlapping," "below," "lateral," "vertical," and the like are made with reference to conceptual illustrations of the optical device, such as those showing standard cross-sectional perspective views and those shown in the accompanying drawings. These terms are used for ease of reference but are not intended to be limiting in nature. Therefore, these terms should be understood to refer to the optical device when in the orientation shown in the drawings.

[0087] Although the present invention has been described in terms of preferred embodiments as set forth above, it should be understood that these embodiments are illustrative only and the claims are not limited to these embodiments. In view of this disclosure, those skilled in the art will be able to make modifications and substitutions, which are considered to fall within the scope of the appended claims. Each feature disclosed or shown in this specification, whether alone or in any suitable combination with any other feature disclosed or shown herein, may be included in the present invention.

Claims

1. An optical stack comprising: a first substrate layer; a second substrate layer; An optical medium is located between the first substrate layer and the second substrate layer; as well as one or more intermediate transparent layers; wherein the first substrate layer and the second substrate layer are bent around the one or more intermediate transparent layers so that the second portion of the optical stack extends behind the first portion of the optical stack; as well as The one or more intermediate transparent layers are disposed between the first portion and the second portion of the optical stack.

2. The optical stack of claim 1, wherein: The optical medium is a liquid crystal layer.

3. The optical stack of claim 1 , wherein: The first portion of the optical stack is substantially parallel to the second portion of the optical stack.

4. The optical stack of claim 1, wherein: Each portion of the optical stack forms an optical unit.

5. The optical stack of claim 4, wherein: The optical cell is a liquid crystal cell or an organic photodiode.

6. The optical stack according to any one of claims 1 to 3, wherein: Each of the first substrate layer and the second substrate layer comprises a single continuous substrate layer that forms both the first portion and the second portion of the optical stack.

7. An optical stack according to any one of claims 1 to 3, wherein: The first substrate layer is spaced apart from the second substrate layer in a first dimension, and wherein a first portion of the optical stack is spaced apart from a second portion of the optical stack in the first dimension.

8. The optical stack according to any one of claims 1 to 3, wherein: The first substrate layer comprises an upper substrate layer of the first portion of the optical stack and a lower substrate layer of the second portion of the optical stack; as well as Wherein, the second substrate layer includes a lower substrate layer of the first part of the optical stack and an upper substrate layer of the second part of the optical stack.

9. The optical stack according to any one of claims 1 to 3, wherein: The first substrate layer and the second substrate layer are bent at an angle of about 180°.

10. The optical stack according to any one of claims 1 to 3, further comprising: An electrical connection coupled to the first substrate layer and the second substrate layer, and wherein the electrical connection is located on a single side of the optical stack.

11. The optical stack of claim 10, wherein: The electrical connection comprises aluminum.

12. The optical stack of claim 1, wherein: The intermediate transparent layer is an adhesive layer.

13. The optical stack of claim 1, wherein: The intermediate transparent layer is located between the first portion of the second substrate layer and the second portion of the second substrate layer.

14. The optical stack of claim 1, wherein: The intermediate transparent layer has a refractive index substantially the same as a refractive index of the optical medium.

15. An optical stack according to any one of claims 1 to 3, wherein the optical stack comprises at least four optical units, and wherein each optical unit is parallel to each other, and wherein each optical unit extends behind an adjacent optical unit.

16. An optical stack according to any one of claims 1 to 3, wherein: The first substrate layer and the second substrate layer are bent such that the optical stack has a corrugated shape.

17. An optical stack according to any one of claims 1 to 3, wherein: Each portion of the optical stack forms an optical lens.

18. An optical stack according to any one of claims 1 to 3, wherein: The substrate comprises a plastic material.

19. An optical stack according to any one of claims 1 to 3, wherein: The optical medium includes aligned domains.

20. An eyewear device comprising two optical devices, the two optical devices comprising the optical stack according to claim 19, wherein the domains of the first optical stack are aligned along a first direction and the domains of the second optical stack are aligned along a second direction.

21. A method of manufacturing an optical stack, the method comprising: forming a first substrate layer, forming a second substrate layer, forming an optical medium disposed between the first substrate layer and the second substrate layer; bending the first substrate layer and the second substrate layer so that the second portion of the optical stack extends behind the first portion of the optical stack; as well as One or more intermediate transparent layers are formed between adjacent portions of the optical stack, wherein the first substrate layer and the second substrate layer are bent around the one or more intermediate transparent layers.

22. The method according to claim 21, wherein: Prior to bending the optical stack, the method further comprises: aligning optical media within a first portion of the optical stack along a first direction using a photolithographic mask, and The optical medium within the second portion of the optical stack is aligned along a second direction using a photolithographic mask.

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