Methods and apparatus for pressing glass or glass-ceramic preforms to form shaped plates, methods for manufacturing liquid lenses, and liquid lenses

A method includes pressing a preform with a mold including a mold body and a plurality of mold protrusions extending from the mold body at a pressing temperature and a pressing pressure sufficient to transform the preform into a shaped article including a plurality of cavities corresponding to the plurality of mold protrusions. The preform is formed from a glass material, a glass-ceramic material, or a combination thereof. The mold body is formed from a porous material. The plurality of mold protrusions is formed from a non-porous material.

BACKGROUND

Field

This disclosure relates to methods and apparatus for pressing glass or glass-ceramic preforms to form shaped articles, which can be used to manufacture liquid lenses.

Technical Background

Isothermal glass pressing generally includes pressing a glass plate at a relatively low temperature (e.g., a temperature at which the glass has a relatively high viscosity of 1010poise to 1012poise) using a polished ceramic or metallic mold. Such high viscosity of the glass helps to prevent the glass from sticking to the mold and to maintain the surface quality of the finished article. The mold complexity and relatively high pressing force generally limits isothermal glass pressing to small glass articles with simple geometries (e.g., ophthalmic lenses).

SUMMARY

Disclosed herein are methods and apparatus for pressing glass or glass-ceramic preforms to form shaped articles, which can be used to manufacture liquid lenses and to liquid lenses incorporating such shaped articles.

Disclosed herein is a method comprising pressing a preform with a mold comprising a mold body and a plurality of mold protrusions extending from the mold body at a pressing temperature and a pressing pressure sufficient to transform the preform into a shaped article comprising a plurality of cavities corresponding to the plurality of mold protrusions. The preform comprises a glass material, a glass-ceramic material, or a combination thereof. The mold body comprises a porous material. The plurality of mold protrusions comprise a non-porous material.

Disclosed herein is an apparatus for pressing a plurality of cavities in a preform, the apparatus comprising a mold body comprising a porous material and a plurality of mold protrusions extending from the mold body and comprising a non-porous material.

Disclosed herein is a shaped article comprising a plate comprising a glass material, a glass-ceramic material, or a combination thereof and a plurality of cavities formed in the plate. An unpolished sidewall of each of the plurality of cavities has a surface roughness of less than or equal to 120 nm.

Disclosed herein is a liquid lens comprising a lens body comprising a first window, a second window, and a cavity disposed between the first window and the second window. A first liquid and a second liquid are disposed within the cavity of the lens body. The first liquid and the second liquid are substantially immiscible with each other and have different refractive indices such that an interface between the first liquid and the second liquid forms a lens. A sidewall of the cavity has a surface roughness of less than or equal to 120 nm.

Disclosed herein is a method of manufacturing a liquid lens, the method comprising pressing a preform with a mold comprising a mold body and a plurality of mold protrusions extending from the mold body at a pressing temperature and a pressing pressure sufficient to transform the preform into a shaped plate comprising a plurality of cavities corresponding to the plurality of mold protrusions. The preform comprises a glass material, a glass-ceramic material, or a combination thereof. The mold body comprises a porous material. The plurality of mold protrusions comprises a non-porous material. A first liquid and a second liquid are deposited in each of the plurality of cavities of the shaped plate. The first liquid and the second liquid are substantially immiscible with each other and have different refractive indices such that an interface between the first liquid and the second liquid forms a lens. A cap is bonded to a surface of the shaped plate to seal the first liquid and the second liquid within the plurality of cavities of the shaped plate and form a liquid lens array.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. The components in the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the exemplary embodiments.

Numerical values, including endpoints of ranges, can be expressed herein as approximations preceded by the term “about,” “approximately,” or the like. In such cases, other embodiments include the particular numerical values. Regardless of whether a numerical value is expressed as an approximation, two embodiments are included in this disclosure: one expressed as an approximation, and another not expressed as an approximation. It will be further understood that an endpoint of each range is significant both in relation to another endpoint, and independently of another endpoint.

As used herein, the term “surface roughness” means Ra surface roughness determined as described in ISO 25178, Geometric Product Specifications (GPS)—Surface texture: areal, filtered at 25 μm.

As used herein, the term “non-stick,” when used in reference to a material from which a mold surface is formed, can mean that there is no substantial formation of an oxide layer at the interface between a glass material, a glass-ceramic material, or a combination thereof with the mold surface at a temperature at which the glass material, the glass-ceramic material, or the combination thereof has a viscosity of 108poise. Additionally, or alternatively, the term “non-stick,” when used in reference to a material from which a mold surface is formed, can mean that the diffusion of any component of a glass material, a glass-ceramic material, or a combination thereof from the interface between the glass material, the glass-ceramic material, or the combination thereof with the mold surface into the mold surface at a temperature at which the glass material, the glass-ceramic material, or the combination thereof has a viscosity of 108poise is limited to a depth of 1 nm.

As used herein, the term “formed from” can mean one or more of comprises, consists essentially of, or consists of. For example, a component that is formed from a particular material can comprise the particular material, consist essentially of the particular material, or consist of the particular material.

In various embodiments, a method comprises pressing a preform with a mold comprising a mold body and a plurality of mold protrusions extending from the mold body at a pressing temperature and a pressing pressure sufficient to transform the preform into a shaped article comprising a plurality of cavities corresponding to the plurality of mold protrusions. In some embodiments, the preform comprises a glass material, a glass-ceramic material, or a combination thereof. Additionally, or alternatively, the mold body comprises, consists essentially of, or consists of a non-stick and/or porous material, such as graphite. Additionally, or alternatively, the plurality of mold protrusions comprise, consist essentially of, or consist of a non-stick and/or non-porous material, such as glass-like carbon.

In various embodiments, an apparatus for pressing a plurality of cavities in a preform comprises a mold body comprising a non-stick and/or porous material, such as graphite, and a plurality of mold protrusions extending from the mold body and comprising a non-stick and/or non-porous material, such as glass-like carbon.

The methods and apparatus described herein can enable pressing of relatively large preforms at relatively low pressing pressures to form shaped articles having cavities with reduced sidewall roughness compared to conventional pressing methods and apparatus.

The methods and apparatus described herein can be used to manufacture shaped articles with smooth cavities formed therein. For example, in various embodiments, a shaped article comprises a plate comprising a glass material, a glass-ceramic material, or a combination thereof, and a plurality of cavities formed in the plate. An unpolished sidewall of each of the plurality of cavities has a surface roughness of less than or equal to 120 nm.

The methods and apparatus descried herein can be used to manufacture liquid lenses. For example, in various embodiments, a liquid lens comprises a lens body comprising a first window, a second window, and a cavity disposed between the first window and the second window. A first liquid and a second liquid are disposed within the cavity of the lens body. For example, the first liquid and the second liquid are substantially immiscible with each other and have different refractive indices such that an interface between the first liquid and the second liquid forms a lens. In some embodiments, a sidewall of the cavity has a surface roughness of less than or equal to 120 nm.

In various embodiments, a method of manufacturing a liquid lens comprises pressing a preform with a mold comprising a mold body and a plurality of mold protrusions extending from the mold body at a pressing temperature and a pressing pressure sufficient to transform the preform into a shaped plate comprising a plurality of cavities corresponding to the plurality of mold protrusions. In some embodiments, the preform comprises a glass material, a glass-ceramic material, or a combination thereof. Additionally, or alternatively, the mold body comprises, consists essentially of, or consists of a non-stick and/or porous material, such as graphite. Additionally, or alternatively, the plurality of mold protrusions comprise, consist essentially of, or consist of a non-stick and/or non-porous material, such as glass-like carbon. In some embodiments, a first liquid and a second liquid are deposited in each of the plurality of cavities of the shaped plate. For example, the first liquid and the second liquid are substantially immiscible with each other and have different refractive indices such that an interface between the first liquid and the second liquid forms a lens. In some embodiments, a cap is bonded to a surface of the shaped plate to seal the first liquid and the second liquid within the plurality of cavities of the shaped plate and form a liquid lens array.

FIG.1is a perspective view of some embodiments of an apparatus100that can be used to press a plurality of cavities in a preform as described herein, andFIG.2is a schematic cross-sectional view of apparatus100. In some embodiments, apparatus100comprises a mold102. For example, mold102comprises a mold body104and a plurality of mold protrusions106extending from the mold body as shown inFIGS.1and2. Mold body104and mold protrusions106cooperatively define a mold surface to be engaged with the preform during pressing as described herein.

In some embodiments, mold body104is formed from a non-stick and/or porous material. For example, mold body104is formed from a graphite material having an open porosity of at least about 2%, at least about 3%, at least about 4%, at least about 5%, or at least about 10%. One potentially suitable graphite material is graphite grade 2020 commercially available from Mersen SA (Gambetta, France). In some embodiments, mold protrusions106are formed from a non-stick and/or non-porous material. For example, mold protrusions106are formed from a glass-like carbon material. One potentially suitable glass-like carbon material is vitrious carbon commercially available from Mersen SA (Gambetta, France). For example, the International Union of Pure and Applied Chemistry (IUPAC) defines glass-like carbon as “[a]n agranular non-graphitizable carbon with a very high isotropy of its structural and physical properties and with a very low permeability for liquids and gases.” Other suitable non-stick and/or non-porous materials can include, for example, a tungsten carbide material (e.g., a low cobalt tungsten carbide material with a cobalt content of about 4% or less), a zirconia material, a zirconia yttrium material (e.g., yttria-stabilized zirconia or YSP or YTZP), or combinations thereof.

Forming mold body104from the porous material can enable the mold body to have a large mold surface. For example, in some embodiments, the mold surface has an area (e.g., an area defined within a perimeter of the mold surface) of at least about 100 cm2, at least about 200 cm2, at least about 300 cm2, at least about 400 cm2, at least about 500 cm2, at least about 750 cm2, or at least about 1000 cm2. Such a large mold surface can be difficult to manufacture using non-porous materials, which can be difficult to machine using conventional diamond tooling. Forming mold protrusions106from the non-porous material can enable the mold protrusions to have smooth engaging portions as described herein. For example, the engaging portions of mold protrusions106can be formed by micro-grinding and/or finished (e.g., using a tribofinishing or another suitable finishing technique) to achieve the desired smoothness. Such smoothness can be difficult to achieve using porous materials. For example, a surface roughness that can be achieved by machining graphite having a relatively small grain size of 0.5 μm to 1 μm and less than 3% open porosity can be limited to about 0.2 μm to about 0.3 μm.

In some embodiments, the mold protrusions are configured as inserts or pins that are received within the mold body to form the mold. For example, mold body104comprises a plurality of openings108, and each of the plurality of mold protrusions106is received within a corresponding one of the plurality of openings in the mold body as shown inFIGS.1and2. Thus, each mold protrusion106comprises a shank portion106A disposed within the corresponding opening108in mold body104and an extension portion106B disposed outside the corresponding opening in the mold body and extending from the mold body. Extension portion106B can be used to engage a preform to form cavities in the preform corresponding to the size and shape of the extension portion as described herein.

In some embodiments, shank portion106A of mold protrusion106and opening108of mold body104have substantially the same cross-sectional shape to enable the shank portion to be received within the opening as described herein. For example, in the embodiments shown inFIGS.1and2, shank portion106A and opening108have a circular cross-sectional shape. In other embodiments, the shank portion and the opening can have a triangular, rectangular, elliptical, or other polygonal or non-polygonal shape. In some embodiments, a width or diameter of shank portion106A of mold protrusion106is substantially the same as a width or diameter of opening108of mold body104. For example, the width or diameter of shank portion106A is at most about 5 μm larger than the width or diameter of opening108. Such sizing can enable an interference fit between mold protrusion106and mold body104. For example, mold protrusion106and opening108are sized to achieve about 5 μm to about 10 μm of compression upon introducing shank portion106A of the mold protrusion into the opening.

In some embodiments, the openings in the mold body are configured as stepped openings. For example, opening108in mold body104comprises a narrow portion108A and a wide portion108B. The terms “narrow” and “wide” are relative terms, meaning that a width or diameter110of narrow portion108A is smaller than a width or diameter112of wide portion108B. Thus, opening108comprises a shoulder at a transition between narrow portion108A and wide portion1086. In some embodiments, mold protrusion106is seated against or engaged with the shoulder of the corresponding opening108. For example, in the embodiments shown inFIGS.1and2, wide portion108B of opening108is sized to receive shank portion106A of mold protrusion106, and narrow portion108A of the opening is smaller than the wide portion and the shank portion, which can prevent the mold protrusion from being introduced into the narrow portion of the opening. Such a configuration can help to ensure that each of the plurality of mold protrusions106is inserted into mold body104to substantially the same depth such that extension portions106B of the mold protrusions extend from the mold body by substantially the same length to engage the preform along a common pressing plane. In some embodiments, openings108in mold body102extend entirely through a thickness of the mold body. Such a configuration can help to enable removal of mold protrusions106from mold body102(e.g., by pressing on the mold protrusions from the back side of the mold body).

Although openings108in mold body104are described with reference toFIGS.1and2as stepped openings, other embodiments are included in this disclosure. For example, in other embodiments, the openings in the mold body are tapered openings (e.g., with progressively smaller width or diameter moving away from the mold surface), straight openings (e.g., with substantially constant diameter), or openings with another suitable configuration. In various embodiments, the mold protrusions can have a size and shape corresponding to the size and shape of the openings in the mold body to enable the mold protrusions to be received within the openings as described herein. Although openings108in mold body104are described with reference toFIGS.1and2as extending entirely through mold body104, other embodiments are included in this disclosure. For example, in other embodiments, the openings in the mold body are blind openings that extend from the mold surface partially through the mold body, but comprise a closed end disposed within the mold body.

In some embodiments, the plurality of mold protrusions is configured to engage a preform to form a plurality of cavities corresponding to the mold protrusions. For example, the mold protrusions, or a portion thereof, are sized and shaped to form cavities in the preform having a desired size and shape. In some embodiments, mold protrusion106comprises an engaging portion106C disposed at a distal end of the mold protrusion extending away from mold body104. For example, engaging portion106C is all or a portion of extension portion106B disposed at the distal end of mold protrusion106to engage the preform as described herein. In some embodiments, a size of engaging portion106C of mold protrusion106corresponds to a desired size of the cavities to be formed in the preform upon pressing. For example, mold protrusion106C can have a diameter or width of at most about 5 mm, at most about 4 mm, at most about 3 mm, at most about 2 mm, or at most about 1 mm. Additionally, or alternatively, mold protrusion106C can have a diameter or width of at least about 0.5 mm or at least about 1 mm. The diameter or width of engaging portion106C can refer to the diameter or width at a proximal end of the engaging portion and/or a distal end of the engaging portion. Such a small engaging portion and the resulting small cavities with smooth and/or straight sidewalls formed in the preform can be enabled by the methods and apparatus described herein. In some embodiments, a shape of engaging portion106C of mold protrusion106has a shape corresponding to a desired shape of the cavities to be formed in the preform upon pressing. For example, in the embodiments shown inFIGS.1and2, engaging portion106C of mold protrusion106has a tapered or truncated conical shape. Thus, mold protrusion106C comprises an elongate rod with a tapered distal end. In other embodiments, the engaging portion of the mold protrusion can have a cylindrical, rounded, or other suitable shape. In various embodiments, engaging portion106C of mold protrusion106has an axisymmetric shape about a longitudinal axis of the mold protrusion.

In some embodiments, a number of mold protrusions in the plurality of mold protrusions corresponds to a desired number of cavities in the plurality of cavities of a shaped article as described herein. For example, the number of mold protrusions106in the plurality of mold protrusions can be at least 100, at least 200, at least 300, at least 400, at least 500, at least 600, at least 700, at least 800, at least 900, at least 1000, at least 1100, at least 1200, at least 1300, at least 1400, or at least 1500. The large number of mold protrusions in the plurality of mold protrusions can be enabled by the low surface roughness of the engaging portions of the mold protrusions. For example, the low surface roughness can enable pressing at a lower pressing force as described herein, which can enable an increased number of mold protrusions.

In some embodiments, engaging portion106C of mold protrusion106has a surface roughness of at most about 50 nm, at most about 40 nm, at most about 30 nm, at most about 20 nm, at most about 10 nm, at most about 5 nm, or at most about 4 nm. Such a smooth engaging surface can be enabled by forming the mold protrusion from the non-porous material as described herein. Additionally, or alternatively, such a smooth engaging portion can enable formation of cavities with smooth sidewalls, which may be beneficial for applications such as liquid lenses as described herein.

FIG.3is a close-up view of a portion of mold102and a separate mold protrusion106that is not received within mold body104. In some embodiments, mold body104comprises an annular recess114surrounding each of the plurality of openings108in the mold body. For example, annular recess114is an indentation or depression in a surface of mold body104that partially or entirely encircles opening108as shown inFIG.3. In some embodiments, annular recess114has a shape that is substantially the same as the shape of opening108. For example, in the embodiments shown inFIGS.1-3, annular recess114has a circular shape corresponding to the circular shape of opening108. In other embodiments, the annular recess and the opening can have different shapes. Annular recess114can serve as a void into which preform material can flow during pressing as described herein, which can reduce the force required to press the preform.

Although mold body104and mold protrusions106are described with reference toFIGS.1and2as being formed from different materials, other embodiments are included in this disclosure. For example, in other embodiments, the mold body and the mold protrusions can be formed from the same or different materials. Additionally, or alternatively, the mold body and the mold protrusions can be formed as a single, integral unit or as one or more separate, distinct units coupled together.

In some embodiments, apparatus100comprises a backing plate120. During pressing, the preform can be pressed between the mold and the backing plate as described herein. In some embodiments, backing plate120comprises a plurality of depressions122corresponding to the plurality of mold protrusions106of mold102. For example, depression122is an indentation or recess in a surface of backing plate120that is at least partially aligned with a corresponding mold protrusion106. In some embodiments, depression122has a shape that is substantially the same as the cross-sectional shape of mold protrusion106. For example, in the embodiments shown inFIGS.1and2, depression122has a circular shape corresponding to the circular cross-sectional shape of mold protrusion106. In other embodiments, the depression and the mold protrusion can have different shapes. Depressions122can serve as voids into which preform material can flow during pressing as described herein, which can reduce the degree to which the preform sticks to mold102and/or reduce the force required to press the preform.

In some embodiments, backing plate120is formed from a porous material as described herein with reference to mold body104. Backing plate120and mold body104can be formed from the same or different materials.

In some embodiments, apparatus100comprises one or more alignment pins and corresponding alignment holes, which can help to maintain alignment between mold102and backing plate120during pressing. For example, in the embodiments shown inFIGS.1and2, backing plate120comprises a plurality of alignment pins124, and mold102comprises a corresponding plurality of alignment holes126. During pressing, alignment pins124can be introduced into alignment holes126, thereby facilitating proper alignment between mold102and backing plate120.

Although apparatus100is described with reference toFIGS.1and2as comprising alignment pins124on backing plate120and corresponding alignment holes126on mold102, other embodiments are included in this disclosure. In other embodiments, the mold comprises one or more alignment pins, and the backing plate comprises one or more corresponding alignment holes. In various embodiments, alignment pins and corresponding alignment holes can be placed on one or both of the mold and the backing plate.

In some embodiments, apparatus100comprises one or more ribs130disposed on the engaging surface of mold body104and/or backing plate120. For example, in the embodiments shown inFIGS.1and2, mold body104comprises one or more ribs130disposed on the engaging surface of the mold body, and backing plate120comprises one or more corresponding ribs130disposed on the engaging surface of the backing plate. The ribs can form thinned segments in the preform during pressing as described herein to enable separation of the shaped article following the pressing. For example, the thinned segments can be configured as breaking lines along which the shaped article can be mechanically broken (e.g., by bending).

FIG.4is a flowchart representing some embodiments of a method200for forming a shaped article. In some embodiments, method200comprises contacting a preform with a mold at step202.

FIG.5is a perspective view of some embodiments of a preform300, andFIG.6is a cross-sectional view of preform300. In some embodiments, preform300is configured as a sheet or plate. For example, preform300comprises a first surface302and a second surface304substantially parallel to the first surface. A thickness of preform300is a distance between first surface302and second surface304. In some embodiments, preform300has a rectangular circumferential or perimetrical shape as shown inFIG.5. In other embodiments, the preform can have a triangular, circular, elliptical, or other polygonal or non-polygonal circumferential or perimetrical shape. For example, the preform300can be a wafer having a substantially circular circumferential shape and with or without a reference flat disposed on an outer circumference or perimeter of the preform. In some embodiments, first surface302of preform300(e.g., the surface of the preform engaged by mold102as described herein) has a surface area of at least about 100 cm2, at least about 200 cm2, at least about 300 cm2, at least about 400 cm2, at least about 500 cm2, at least about 600 cm2, at least about 700 cm2, at least about 800 cm2, at least about 900 cm2, at least about 1000 cm2, at least about 1100 cm2, at least about 1200 cm2, at least about 1300 cm2, at least about 1400 cm2, or at least about 1500 cm2. For example, preform can be a 6 inch wafer with a surface area of about 121.55 cm2, an A6 plate with a surface area of about 155.4 cm2, an 8 inch wafer with a surface area of about 162.15 cm2, an A5 plate with a surface area of about 310.8 cm2, an A4 plate with a surface area of about 623.7 cm2, an A3 plate with a surface area of about 1247.4 cm2, or another suitably sized preform with a suitable surface area. Such a large surface area can be enabled by the mold100described herein (e.g., by enabling increased pressing temperature and/or reduced pressing pressure). In some embodiments, preform300is formed from a glass material, a glass-ceramic material, or a combination thereof. For example, preform300is a glass sheet or plate.

In some embodiments, the contacting comprises contacting preform300with mold102described herein. For example, the contacting comprises bringing at least a portion of the mold surface (e.g., engaging portions106C of mold protrusions106) into contact with first surface302of preform300.

In some embodiments, method200comprises heating the preform at step204as shown inFIG.4. For example, heating preform300comprises heating the preform in a heating device such as an oven or a lehr. Thus, the heating can be performed as a batch process (e.g., in a static oven) or a continuous process (e.g., in a dynamic lehr). In some embodiments, the heating comprises heating preform300to a pressing temperature. The pressing temperature can be a temperature sufficient to cause preform300to soften to a desired viscosity for pressing as described herein. For example, the pressing temperature is a temperature at which preform300has a viscosity of at least about 105poise, at least about 106poise, or at least about 107poise. Additionally, or alternatively, the pressing temperature is a temperature at which preform300has a viscosity of at most about 1012poise, at most about 1011poise, at most about 1010poise, at most about 109poise, or at most about 1085poise. In some embodiments, the heating comprises ramping the temperature of preform300to the pressing temperature (e.g., from room temperature (e.g., about 20° C.) to the pressing temperature) over a ramp period. For example, the ramp period is at least about 0.5 hours, at least about 1 hour, or at least about 1.5 hours. Additionally, or alternatively, the ramp period is at most about 5 hours, at most about 4 hours, at most about 3 hours, or at most about 2.5 hours. Gradually heating the preform over the ramp period can help to avoid thermally shocking the preform.

The heating can be performed before and/or after the contacting. For example, in some embodiments, preform300is contacted with mold102, and then the preform and the mold are heated together to bring the preform to the pressing temperature. In other embodiments, preform300is heated to an intermediate temperature (e.g., a temperature between room temperature and the pressing temperature) prior to being contacted with mold102, and then the preform and the mold are further heated to bring the preform to the pressing temperature.

In some embodiments, method200comprises pressing the preform with the mold at a pressing temperature and a pressing pressure sufficient to transform the preform into a shaped article comprising a plurality of cavities corresponding to the plurality of mold protrusions. For example, the pressing comprises applying a sufficient force on mold102to press mold protrusions106into first surface302of preform300, thereby forming the cavities in the preform and transforming the preform into the shaped article. For example, the pressing pressure can be about 0.1 N/cm2to about 1 N/cm2. The pressing pressure can depend on the pressing temperature. For example, a higher pressing pressure may be used in combination with a lower pressing temperature (e.g., to compensate for the higher viscosity of the preform). Conversely, a lower pressing pressure may be used in combination with a higher pressing temperature (e.g., to compensate for the lower viscosity of the preform).

In some embodiments, mold102comprises mold body104formed from the porous material and mold protrusions106formed from the non-porous material as described herein. Such a configuration of mold102can enable an isothermal pressing process for producing shaped articles with high precision and/or high registration. For example, the porous material of mold body104can help to prevent gas entrapment during pressing and/or enable venting during mold release, or demolding.

In some embodiments, pressing the preform comprises pressing the preform between the mold and a backing plate. For example, the pressing comprises pressing preform300between mold102and backing plate120. In some embodiments, the pressing comprises maintaining preform300at the pressing temperature and/or maintaining the pressing force on mold102for a dwell time sufficient to transform the preform into the shaped article. For example, the dwell time is at least about 5 minutes or at least about 10 minutes. Additionally, or alternatively, the dwell time is at most about 30 minutes or at most about 20 minutes.

FIG.2schematically illustrates some embodiments of mold102and preform300during the pressing. In some embodiments, during the pressing, engaging portions106C of mold protrusions106are pressed into preform300as shown inFIG.2. Such engagement and/or squeezing of preform300between mold102and backing plate120can cause material of the preform to flow into annular recesses114of mold body104and/or depressions122of the backing plate.

FIG.7is a cross-sectional schematic view of some embodiments of the pressing. In some embodiments, apparatus100comprises a plurality of molds102and a plurality of backing plates120as shown inFIG.7. Molds102and backing plates120can be arranged in an alternating stacked arrangement as shown inFIG.7. The pressing force can be applied to the stack of molds102and backing plates120. For example, the pressing force is applied by placing a weight140on top of the stack. Additionally, or alternatively, the pressing force is applied using a mechanical press, or another suitable pressing device. Using a plurality of molds and backing plates can enable an increase in the rate of manufacturing shaped articles.

FIG.8is a partial cross-sectional schematic view of some embodiments of a shaped article400following the pressing. Shaped article400comprises a first surface402corresponding to first surface302of preform300and a second surface404opposite the first surface and corresponding to second surface304of the preform. In some embodiments, shaped article400comprises a plurality of cavities406formed in first surface402and corresponding to the plurality of mold protrusions106of mold102. In some embodiments, cavities406are blind holes that do not extend entirely through shaped article400as shown inFIG.8. Thus, cavities406comprise an open end at first surface402of shaped article400and a closed end near second surface404of the shaped article. In other embodiments, the cavities are through-holes extending entirely through the shaped article. Cavities406can have a size and shape corresponding to mold protrusions106(e.g., engaging surfaces106C of the mold protrusions). For example, cavities406can have a diameter or width of at most about 5 mm, at most about 4 mm, at most about 3 mm, at most about 2 mm, or at most about 1 mm. Additionally, or alternatively, cavities406can have a diameter or width of at least about 0.5 mm or at least about 1 mm. The diameter or width of cavities406can refer to the diameter or width at first surface402of shaped article400and/or second surface404of the shaped article. Such small cavities with smooth and/or straight sidewalls can be enabled by the methods and apparatus described herein.

In some embodiments, a number of cavities406in the plurality of cavities corresponds to the number of mold protrusions106of mold102as described herein. For example, the number of cavities406in the plurality of cavities can be at least 100, at least 200, at least 300, at least 400, at least 500, at least 600, at least 700, at least 800, at least 900, at least 1000, at least 1100, at least 1200, at least 1300, at least 1400, or at least 1500.

In some embodiments, method200comprises cooling the shaped article at step208as shown inFIG.4. For example, cooling shaped article400comprises cooling the shaped article in the heating device such as the oven or the lehr. Thus, the cooling can be performed as a batch process (e.g., in a static oven) or a continuous process (e.g., in a dynamic lehr). In some embodiments, the cooling comprises cooling shaped article400to room temperature. In some embodiments, the cooling comprises ramping the temperature of shaped article (e.g., from the pressing temperature to room temperature) over a ramp period. For example, the ramp period is at least about 0.5 hours, at least about 1 hour, or at least about 1.5 hours. Additionally, or alternatively, the ramp period is at most about 5 hours, at most about 4 hours, at most about 3 hours, or at most about 2.5 hours. Gradually cooling the shaped article over the ramp period can help to avoid thermally shocking the shaped article.

In some embodiments, following the pressing and/or the cooling, shaped article400comprises one or more raised portions408disposed on one or more surfaces of the shaped article as shown inFIG.8. For example, first surface402of shaped article400comprises raised portions408corresponding to annular recesses114of mold body104. Such raised portions408can result from flow of material of preform300into annular recesses114during the pressing. Additionally, or alternatively, second surface404of shaped article400comprises raised portions408corresponding to depressions122of backing plate120. Such raised portions408can result from flow of material of preform300into depressions122during the pressing. Thus, in various embodiments, first surface402and/or second surface404are non-planar following pressing.

In some embodiments, method200comprises polishing the shaped article at step210as shown inFIG.4. For example, polishing shaped article400comprises polishing at least one of first surface402of the shaped article or second surface404of the shaped article following the pressing and/or the cooling.

FIG.9is a cross-sectional schematic view of some embodiments of shaped article400following the polishing. In some embodiments, the polishing comprises removing material from first surface402of shaped article400. For example, the polishing comprises removing material from first surface402down to dashed line410shown inFIG.8. Such polishing can remove raised portions408on first surface402, resulting in a substantially planar surface, excluding cavities406, as shown inFIG.9. In some embodiments, the polishing comprises removing material from second surface404of shaped article400. For example, the polishing comprises removing material from second surface404down to dashed line412shown inFIG.8. Such polishing can remove raised portions408on second surface404, resulting in a substantially planar surface, excluding cavities406, as shown inFIG.9. The polishing can be achieved by mechanical grinding, chemical etching, thermal treatment, or another suitable polishing process. Mechanical grinding can be beneficial in enabling removal of material from the surfaces of the shaped article without altering the sidewalls of the cavities, which can help to preserve the surface quality of the sidewalls as described herein.

In some embodiments, after the pressing and prior to the polishing, cavities406of shaped article400comprise blind holes as shown inFIG.8and described herein. In some of such embodiments, the polishing opens the blind holes to transform the plurality of cavities406into a plurality of through-holes as shown inFIG.9. For example, the polishing removes the closed end of the blind holes to open the blind holes and form the through-holes.

In some embodiments, the polishing does not affect the surfaces of the sidewalls of cavities406. Thus, before and after the polishing, the sidewalls are unpolished sidewalls. In some embodiments, the sidewalls of cavities406of shaped article400have an unpolished or as-pressed surface roughness (e.g., following the pressing, the cooling, and/or the polishing) of at most about 120 nm, at most about 110 nm, at most about 100 nm, at most about 90 nm, at most about 80 nm, at most about 70 nm, at most about 60 nm, at most about 50 nm, at most about 40 nm, at most about 30 nm, at most about 20 nm, or at most about 10 nm. Additionally, or alternatively, the sidewalls of cavities406of shaped article400have an unpolished or as-pressed surface roughness of at least about 5 nm, at least about 10 nm, or at least about 20 nm. Such a smooth surface can be enabled by the smoothness of engaging portion106C of mold protrusion106, which can be enabled by the non-porous material from which mold102can be formed. In some embodiments, the sidewalls of cavities406of shaped article400are substantially straight. For example, the deviation of the sidewalls of cavities406from linear is within +/−0.25 μm over 1 mm along the sidewall through a thickness of shaped article400. In some embodiments, cavities406have a truncated conical shape with smooth and substantially straight sidewalls.

In some embodiments, a thickness of shaped article400(e.g., a distance between first surface402and second surface404), before or after polishing, can be at most about 5 mm, at most about 4 mm, at most about 3 mm, at most about 2 mm, at most about 1 mm, at most about 0.9 mm, at most about 0.8 mm, at most about 0.7 mm, at most about 0.6 mm, or at most about 0.5 mm. Additionally, or alternatively, the thickness of shaped article400, before or after polishing, can be at least about 0.1 mm, at least about 0.2 mm, at least about 0.3 mm, at least about 0.4 mm, at least about 0.5 mm, at least about 0.8 mm, at least about 0.9 mm, or at least about 1 mm.

In some embodiments, method200comprises singulating the shaped article at step212as shown inFIG.4. For example, singulating shaped article400comprises separating the shaped article into two or more shaped sub-articles following the pressing, the cooling, and/or the polishing. In some embodiments, shaped article400comprises one or more cutting paths formed therein. For example, the cutting paths are thinned regions of shaped article400formed by ribs130of mold102and/or backing plate120. In some of such embodiments, singluating shaped article400comprises cutting or breaking the shaped article along the cutting paths. For example,FIG.10is a perspective view of some embodiments of a shaped sub-article400A formed by breaking shaped article400along a plurality of cutting paths. In some embodiments, singulating shaped article400comprises dicing the shaped article (e.g., with a mechanical dicing saw, a laser, or another suitable cutting device). For example, the singulating comprises dicing shaped article400to form a plurality of shaped sub-articles, and each sub-article comprises a single cavity406. Such shaped sub-articles can be used to form liquid lenses as described herein.

In some embodiments, the methods and apparatus described herein can be used to manufacture liquid lenses.FIG.11is a cross-sectional schematic view of some embodiments of a liquid lens500incorporating shaped article400. In some embodiments, liquid lens500comprises a lens body535and a cavity506formed in the lens body. A first liquid538and a second liquid539are disposed within cavity506. In some embodiments, first liquid538is a polar liquid or a conducting liquid. Additionally, or alternatively, second liquid539is a non-polar liquid or an insulating liquid. In some embodiments, first liquid538and second liquid539are immiscible with each other and have different refractive indices such that an interface540between the first liquid and the second liquid forms a lens. Interface540can be adjusted via electrowetting. For example, a voltage can be applied between first liquid538and a surface of cavity506(e.g., an electrode positioned near the surface of the cavity and insulated from the first liquid) to increase or decrease the wettability of the surface of the cavity with respect to the first liquid and change the shape of interface540. In some embodiments, adjusting interface540changes the shape of the interface, which changes the focal length or focus of liquid lens500. For example, such a change of focal length can enable liquid lens500to perform an autofocus (AF) function. Additionally, or alternatively, adjusting interface540tilts the interface relative to an optical axis576. For example, such tilting can enable liquid lens500to perform an optical image stabilization (OIS) function. Such adjustment of interface540via electrowetting can be sensitive to surface roughness and/or non-linearity of the sidewalls of cavity506. Thus, the methods and apparatus described herein for forming shaped article400having cavities506with smooth and/or substantially straight sidewalls may be beneficial for forming cavity506for liquid lens500. In some embodiments, first liquid538and second liquid539have substantially the same density, which can help to avoid changes in the shape of interface540as a result of changing the physical orientation of liquid lens500(e.g., as a result of gravitational forces).

In some embodiments, lens body535of liquid lens500comprises a first window541and a second window542. In some of such embodiments, cavity506is disposed between first window541and second window542. In some embodiments, lens body535comprises a plurality of layers that cooperatively form the lens body. For example, in the embodiments shown inFIG.11, lens body535comprises a cap543, a shaped plate544, and a base545. In some embodiments, shaped plate544with cavity506comprises or is formed from shaped article400with cavity406. For example, shaped plate544with cavity506is formed as described herein with reference to shaped article400with cavity406, cap543is bonded to one side (e.g., an object side) of the shaped plate, and base545is bonded to the other side (e.g., an image side) of the shaped plate such that the cavity is covered on opposing sides by the cap and the base. Thus, a portion of cap543covering cavity506serves as first window541, and a portion of base545covering the cavity serves as second window542. In other embodiments, the cavity is a blind hole that does not extend entirely though the shaped plate. In such embodiments, the base can be omitted, and the closed end of the cavity can serve as the second window.

In some embodiments, cavity506has a truncated conical shape as shown inFIG.11such that a cross-sectional area of the cavity decreases along optical axis576in a direction from the object side to the image side. Such a tapered cavity can help to maintain alignment of interface540between first liquid538and second liquid539along optical axis576. In other embodiments, the cavity is tapered such that the cross-sectional area of the cavity increases along the optical axis in the direction from the object side to the image side or non-tapered such that the cross-sectional area of the cavity remains substantially constant along the optical axis.

In some embodiments, image light enters liquid lens500through first window541, is refracted at interface540between first liquid538and second liquid539, and exits the liquid lens through second window542. In some embodiments, cap543and/or base545comprise a sufficient transparency to enable passage of image light. For example, cap543and/or base545comprise a polymeric material, a glass material, a ceramic material, a glass-ceramic material, or a combination thereof. In some embodiments, outer surfaces of cap543and/or base545are substantially planar. Thus, even though liquid lens500can function as a lens (e.g., by refracting image light passing through interface540), outer surfaces of the liquid lens can be flat as opposed to being curved like the outer surfaces of a fixed lens. In other embodiments, outer surfaces of the cap and/or the base are curved. Thus, the liquid lens comprises an integrated fixed lens. In some embodiments, shaped plate544comprises a glass material, a glass-ceramic material, or a combination thereof as described herein. Because image light can pass through the cavity through shaped plate544, the shaped plate may or may not be transparent.

AlthoughFIG.11illustrates a single liquid lens500, liquid lenses can be manufactured in arrays using a wafer manufacturing process as described herein. For example, a liquid lens array comprises a plurality of liquid lenses500attached in a plate or wafer. Thus, prior to singulation to form single liquid lens500, shaped plate544comprises a plurality of cavities506. Additionally, or alternatively, prior to singulation, cap543comprises a plate with a plurality of first windows541corresponding to the plurality of cavities506. Additionally, or alternatively, prior to singulation, base545comprises a plate with a plurality of second windows542corresponding to the plurality of cavities506. After formation, the liquid lens array can be singulated to form the individual liquid lenses500.

FIG.12is a flowchart representing some embodiments of a method600for manufacturing a liquid lens. In some embodiments, method600comprises forming a shaped plate comprising a plurality of cavities. For example, method600comprises forming shaped plate544comprising the plurality of cavities506at step602(e.g., as described herein with reference to forming shaped article400comprising the plurality of cavities406).

In some embodiments, method600comprises bonding a base to a surface of the shaped plate. For example, method600comprises bonding base545to shaped plate544at step604. The bonding comprises, for example, laser bonding, adhesive bonding, or another suitable bonding technique.

In some embodiments, method600comprises depositing first and second liquids into the plurality of cavities of the shaped plate. For example, method600comprises depositing first liquid538and second liquid539in each of the plurality of cavities506of shaped plate544at step606.

In some embodiments, method600comprises bonding a cap to a surface of the shaped plate to seal the first liquid and the second liquid within the plurality of cavities and form a liquid lens array. For example, method600comprises bonding cap543to shaped plate544to seal first liquid538and second liquid539within the plurality of cavities506of the shaped plate608. The bonding comprises, for example, laser bonding, adhesive bonding, or another suitable bonding technique.

In some embodiments, method600comprises singulating the liquid lens array to form a plurality of individual liquid lenses. For example, method600comprises singulating the liquid lens array comprising cap543, shaped plate544, and optionally, base545to form the plurality of individual liquid lenses500at step610. The singulating comprises, for example, mechanical dicing, laser dicing, or another suitable dicing technique.

The methods and apparatus described herein for forming shaped articles with a plurality of cavities formed therein can enable large-scale production of shaped plates having cavities with sufficiently smooth surfaces to be used in electrowetting applications, which in turn, can enable efficient manufacturing of liquid lens arrays and/or singulated liquid lenses.

AlthoughFIG.12illustrates using the methods and apparatus described herein to manufacture liquid lenses, other embodiments are included in this disclosure. For example, in other embodiments, the methods and apparatus described herein can be used to make shaped articles for use in optics, biological, microfluidic, or any other suitable applications.

In some embodiments, a shaped article comprises a plate comprising a glass material, a glass-ceramic material, or a combination thereof and a plurality of cavities formed in the plate. In some of such embodiments, an unpolished sidewall of each of the plurality of cavities has a surface roughness of less than or equal to 120 nm. Additionally, or alternatively, the plate comprises a first surface and a second surface opposite the first surface, and the first surface of the plate has an area of at least about 100 cm2. Additionally, or alternatively, each of the plurality of cavities has a truncated conical shape. Additionally, or alternatively, the sidewall of each of the plurality of cavities is substantially straight.

It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the claimed subject matter. Accordingly, the claimed subject matter is not to be restricted except in light of the attached claims and their equivalents.