Patent Description:
The present specification generally relates to optical assemblies and apparatuses and methods for aligning components of optical assemblies and, more specifically, to apparatuses and methods for aligning optical axes of lenses of optical assemblies.

Optical assemblies, such as "doublets" or "triplets," may include two or more lenses that are adhered together with an optical adhesive between adjacent optical surfaces. Such apparatuses may be used in ultraviolet and visible wavelength imaging objectives in a range of applications such as, for example and without limitation, semiconductor inspection, microscope imaging, visible light cameras, and the like.

During manufacture of the optical assemblies, it is desired to properly align the optical axes of the individual lenses, which may prove difficult depending on the desired alignment tolerances.

Accordingly, a need exists for alternative apparatuses and methods for aligning components of optical assemblies for improved optical performance.

<CIT> provides a self-centering precision chuck for use in centering lenses. <CIT> provides an apparatus for centering lenses during bonding.

The invention provides an alignment apparatus for aligning components of an optical assembly according to claim <NUM>.

According to a preferred embodiment of the apparatus, the chuck is rotatable around the datum axis.

According to a preferred embodiment of the apparatus, the chuck includes a vacuum channel, and the optical assembly is supported on the chuck by vacuum pressure provided through the vacuum channel.

According to a preferred embodiment of the apparatus, further including a column supporting the chuck thereon, wherein the adjustable flexure assembly is disposed around the column and is slidable along the column so as to be adjustably positioned along a length of the column.

According to a preferred embodiment of the apparatus, the base plate defines a base plate aperture, the adjustable plate defines an adjustable plate aperture aligned with the base plate aperture, and the base plate aperture and the adjustable plate aperture are sized to allow passage of the chuck therethrough.

According to a preferred embodiment of the apparatus, the one or more adjustment actuators are configured to adjust a tilt of the adjustable plate relative to the support surface of the base plate.

According to a preferred embodiment of the apparatus, further including a plurality of flexure clamps coupled to the adjustable plate.

According to a preferred embodiment of the apparatus, each flexure clamp is coupled to the adjustable plate. Each flexure clamp includes a fixed portion, fixedly coupled to the adjustable plate, a sliding portion, wherein a flexure of the plurality of flexures is coupled to the sliding portion, and a flexible webbing coupling the fixed portion to the sliding portion. The adjustable flexure assembly further includes a sliding actuator associated with each flexure clamp, wherein the sliding actuator is configured to contact the sliding portion of the flexure clamp to displace the sliding portion relative to the adjustable plate thereby flexing the flexible webbing and adjusting the position of the flexure coupled to the flexure clamp relative to the adjustable plate and the chuck.

According to a preferred embodiment of the apparatus, further including a plurality of stops coupled to the adjustable plate proximate the sliding portion of the flexure clamp, wherein each stop limits the sliding of the sliding portion of the flexure clamp.

According to a preferred embodiment of the apparatus, further including a centration measurement apparatus configured to measure an optical axis alignment of one or more components of the optical assembly.

According to a preferred embodiment of the apparatus, wherein a force/displacement ratio applied by the plurality of flexures to the optical component is about <NUM> x <NUM>-<NUM> N/mm to about <NUM> x <NUM>-<NUM> N/mm.

According to a preferred embodiment of the apparatus, each flexure of the plurality of flexures comprises a length to diameter ratio of about <NUM>:<NUM> to about <NUM>:<NUM>.

The invention provides a method for aligning components of an optical assembly according to claim <NUM>.

According to a preferred embodiment of the method, further including measuring an optical axis alignment of the first lens and the second lens with a centration measurement apparatus, and evaporating the liquid when the optical axis alignment of the first lens and the second lens is within a predetermined alignment range.

According to a preferred embodiment of the method, the first lens comprises a convex coupling surface and the second lens comprises a concave coupling surface, wherein the concave coupling surface of the second lens is contacted to the convex coupling surface of the first lens with the liquid.

According to a preferred embodiment of the method, the liquid is an optical adhesive.

According to a preferred embodiment of the method, further including curing the optical adhesive when optical axis alignment of the first lens and the second lens is within a predetermined alignment range.

According to a preferred embodiment of the method, the adjustable flexure assembly is rotatable around a datum axis.

According to a preferred embodiment of the method, the chuck is rotatable around the datum axis.

According to a preferred embodiment of the method, the chuck includes a vacuum channel, and the optical assembly is supported on the chuck by vacuum pressure provided through the vacuum channel.

According to a preferred embodiment of the method, the adjustable flexure assembly further includes a tip-tilt assembly disposed around the chuck. The tip-tilt assembly includes a base plate defining a support surface, an adjustable plate adjustably coupled to the base plate, the adjustable plate supporting the plurality of flexures thereon, and one or more adjustment actuators configured to adjust a position of the adjustable plate relative to the support surface of the base plate.

According to a preferred embodiment of the method, the alignment apparatus further comprises a column supporting the chuck thereon, wherein the adjustable flexure assembly is disposed around the column and is slidable along the column so as to be adjustably positioned along a length of the column.

According to a preferred embodiment of the method, the base plate defines a base plate aperture, the adjustable plate defines an adjustable plate aperture aligned with the base plate aperture, and the base plate aperture and the adjustable plate aperture are sized to allow passage of the chuck therethrough.

According to a preferred embodiment of the method, the one or more adjustment actuators are configured to adjust a tilt of the adjustable plate relative to the support surface of the base plate.

According to a preferred embodiment of the method, the adjustable flexure assembly further includes a plurality of flexure clamps coupled to the adjustable plate.

According to a preferred embodiment of the method, each flexure clamp is coupled to the adjustable plate and includes a fixed portion, fixedly coupled to the adjustable plate, a sliding portion, wherein a flexure of the plurality of flexures is coupled to the sliding portion, and a flexible webbing coupling the fixed portion to the sliding portion, wherein the adjustable flexure assembly further comprises a sliding actuator associated with each flexure clamp, wherein the sliding actuator is configured to contact the sliding portion of the flexure clamp to displace the sliding portion relative to the adjustable plate thereby flexing the flexible webbing and adjusting the position of the flexure coupled to the flexure clamp relative to the adjustable plate and the chuck.

According to a preferred embodiment of the method, the adjustable flexure assembly further includes a plurality of stops coupled to the adjustable plate proximate the sliding portion of the flexure clamp, wherein each stop limits the sliding of the sliding portion of the flexure clamp.

According to a preferred embodiment of the method, the alignment apparatus further comprises a centration measurement apparatus configured to measure an optical axis alignment of one or more components of the optical assembly.

Embodiments described herein are directed to apparatuses and methods for aligning components of optical assemblies. For example, an alignment apparatus for aligning components of optical assemblies may include a chuck configured to support the optical assembly thereon, and an adjustable flexure assembly. The adjustable flexure assembly may be disposed around the chuck and include a plurality of flexures. The plurality of flexures are configured to contact the optical assembly, such as an edge of the optical assembly. Adjustment of a position of one or more flexures of the plurality of flexures causes an adjustment in an optical axis alignment of one or more components (e.g., lenses) of the optical assembly. Accordingly, alignment of the optical axes of the various components of the optical assembly may be achieved. The flexures may provide a subtle contact force to displace the components of the optical assembly into alignment. Such subtle contact force may decrease force disturbances and stress within an optical adhesive positioned between optical components, thereby improving the quality and optical properties of the optical assembly. Various embodiments of the alignment apparatus and methods of alignment, as well as optical assemblies, will be described in more detail herein.

Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment.

Directional terms as used herein - for example up, down, right, left, front, back, top, bottom, upper, lower - are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

As used herein, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes aspects having two or more such components, unless the context clearly indicates otherwise.

Referring now to <FIG> an optical assembly <NUM> is generally depicted. As used herein, "an optical assembly" is an arrangement of optical components (e.g., lenses, mirrors, etc.) that guide the transmission of light. The optical assembly <NUM> may include various components each comprising an optical axis. An optical axis, as used herein, is an imaginary line or line segment that passes through a center of curvature of a lens' surfaces. In particular, the optical assembly <NUM> may include a first lens <NUM> including a first lens optical axis <NUM> and a second lens <NUM> including a second lens optical axis <NUM>.

During conventional manufacturing of optical assemblies (e.g., doublets, triplets, or the like), fine alignment of the first lens optical axis <NUM> and the second lens optical axis <NUM> is desired. Alignment may be a tedious and difficult process especially when working with lenses of various sizes, mating curvatures, and curvature orientations. For example, it may be difficult to stabilize the top lens relative to the bottom lens in a preferred orientation such that the optical axes <NUM>, <NUM> are aligned. This may be especially true for small lenses (e.g., having a diameter of <NUM> or less) with short curvature radii.

Embodiments described herein are directed to apparatuses and methods for stabilizing the top and bottom lenses to provide a desired alignment. Additionally embodiments as provided herein may be used for alignment of micro-optic components (e.g., lenses having edge thickness of <NUM>-<NUM> or less and diameters of less than <NUM>). Furthermore, embodiments as provided herein may provide low contact forces that do not stress optical elements or the connecting adhesive layer to the same degree as conventional assembly techniques (i.e., wherein the adhesive is at least partially cured during alignment). Additionally, embodiments can provide fine adjustments for sub-micron and/or micro-radian level alignments.

Still referring to <FIG>, in <FIG> the optical assembly <NUM> is not aligned. That is, the first lens optical axis <NUM> is not aligned with second lens optical axis <NUM>. For example, in this unaligned state, the angle of deviation α between the first lens optical axis <NUM> and the second lens optical axis <NUM> is greater than a predetermined alignment range (e.g., greater than about <NUM>,<NUM>µrad, greater than about <NUM>µrad, greater than about <NUM>µrad, greater than about <NUM>µrad, greater than about <NUM>µrad, etc.) depending on the particular application or type of optical assembly.

By way of contrast, <FIG> depicts the first lens optical axis <NUM> aligned with the second lens optical axis <NUM>. While the first lens optical axis <NUM> is shown as coincident with the second lens optical axis <NUM>, the optical assembly <NUM> may be considered aligned when the angle of deviation α between the first lens optical axis <NUM> and the second lens optical axis <NUM> is within a predetermined alignment range. For example, alignment may be achieved when an angle of deviation α is less than about <NUM>,<NUM>µrad, less than about <NUM>µrad, less than about <NUM>µrad, less than about <NUM>µrad, less than about <NUM>µrad, etc. The predetermined threshold angle of deviation α may depend on the specific constraints or end use of the optical assembly <NUM>.

In the embodiments described herein, the first lens <NUM> may be a convex lens (e.g., biconvex, equi-convex, plano-convex, convex-concave, meniscus, or the like) such that at least one surface of the first lens <NUM> through which the first lens optical axis <NUM> extends is convex. For example, the first lens <NUM> may include a first lens first surface <NUM> and a first lens coupling surface <NUM> opposite the first lens first surface <NUM>. In particular, the first lens coupling surface <NUM> may be a convex coupling surface.

It is noted that while opposing surfaces (i.e., the first lens first surface <NUM> and the first lens coupling surface <NUM>) of the first lens <NUM> are shown to be convex, in embodiments, only one surface of the first lens <NUM> may be convex while the opposite surface is planar or concave. In embodiments where opposing surfaces of the first lens <NUM> are both convex, the radii of the curved surfaces may be the same or different.

The second lens <NUM> may be a concave lens (e.g., biconcave, equi-concave, plano-concave, meniscus, convex-concave, etc.) such that at least one surface of the second lens <NUM> through which the second lens optical axis <NUM> extends is concave. For example, the second lens <NUM> may include a second lens first surface <NUM> and a second lens coupling surface <NUM> opposite the second lens first surface <NUM>. In particular, the second lens coupling surface <NUM> may be a concave coupling surface.

It is noted that while opposing surfaces (i.e., the second lens first surface <NUM> and the second lens coupling surface <NUM>) of the second lens <NUM> are shown to be concave, in embodiments, only one surface may be concave while the opposite surface is planar or convex. In embodiments where the opposing surfaces of the second lens <NUM> are both concave, the radii of the curved surfaces may be the same or different.

Still referring to <FIG>, the concave coupling surface <NUM> of the second lens <NUM> may be bonded to the convex coupling surface <NUM> of the first lens <NUM> with an optical adhesive <NUM>. In embodiments, the concave coupling surface <NUM> and the convex coupling surface <NUM> may have similar radii such that the convex coupling surface <NUM> of the first lens <NUM> nests within the concave coupling surface <NUM> of the second lens <NUM>.

When the optical assembly <NUM> includes only a first lens <NUM> and a second lens <NUM>, as illustrated in <FIG>, the optical assembly <NUM> may be referred to as a doublet. However, it is noted that additional lenses may be added to the optical assembly <NUM>. For example, a third lens may be coupled to a free surface of the optical assembly <NUM> (e.g., the third lens may be coupled to the first lens first surface <NUM> or the second lens first surface <NUM>). The third lens may be convex, concave, or planar, to mate with the surface of the first lens <NUM> or the second lens <NUM>. An optical assembly <NUM> with three lenses may be referred to as a triplet. The third lens may be adhered to the optical assembly <NUM> using the same or a different optical adhesive than that used to bond the first lens <NUM> to the second lens <NUM>. It is noted that a greater number of lenses may be coupled to one another to form an optical assembly.

As noted above, an optical adhesive <NUM> is provided to bond the first lens <NUM> to the second lens <NUM>. Properties of the optical adhesive <NUM> (e.g., index, thickness, coefficient of thermal expansion, etc.) used in joining the lenses of the optical assembly <NUM> may affect optical performance. In particular, optical adhesives may be chosen to enhance the salient properties of the final optical assembly. Optical adhesives may also be chosen based on properties of the adhesive that may affect manufacturability of the optical assembly <NUM> such as, for example, cure time, cure temperature, shrinkage, etc. Accordingly, depending on the specific application, any commercially available optical adhesive may be used. In embodiments, optical adhesives may be provided as a liquid. The optical adhesive <NUM> may be applied between the lenses and, thereafter, cured (e.g., through UV curing, IR curing, thermal curing, timed curing, etc.) once the desired alignment between the lenses is achieved. In embodiments, the optical adhesive <NUM> may have a pre- or un-cured viscosity of less than about <NUM> cps or from about <NUM> cps to <NUM> cps. However, it should be understood that other viscosities for the optical adhesive <NUM> are contemplated and possible. In some embodiments, the optical adhesive <NUM> may be applied in a layer about <NUM> to about <NUM> thick.

As noted above, manufacturing optical assemblies with two or more lenses may be tedious. In particular, it may be difficult to properly align the respective optical axes of the various lenses. In addition, curing the optical adhesive <NUM> during alignment may affect the optical properties of the optical assembly <NUM>. Conventionally, one technique for providing stable positioning of the lenses during assembly is to use a viscous adhesive, which may allow for damping of positioning drift (e.g., slide off) of the lenses relative to on another. However, such viscous adhesives may have poor optical characteristics relative to lower viscosity adhesives. Another technique may be to partially cure the optical adhesive <NUM>, which can increase the viscosity of the optical adhesive <NUM> and improve the reaction of the lenses to forces during alignment. However, optical properties of the optical adhesive <NUM> may be adversely affected by introducing shear stress or compression during the partially cured stage, which may result in stress birefringence in the optical assembly <NUM>. The introduction of stress and the resulting stress birefringence degrades the optical quality of the optical assembly <NUM>. For example, stress birefringence may induce a change in the polarization state of the transmitted light. Embodiments provided herein may include the alignment of the optical axes of the various components of the optical element with the optical adhesive <NUM> in a liquid, uncured state, to reduce or substantially eliminate the introduction of stresses during the alignment phase. Accordingly, a reduced stress profile within the optical assembly <NUM> may be achieved as opposed to an optical assembly wherein alignment is performed while the optical adhesive <NUM> is at least partially cured.

For example, the optical adhesive <NUM> may be provided as a liquid adhesive that is coated or otherwise applied to the first lens coupling surface <NUM>, the second lens coupling surface <NUM>, or combinations thereof. While the optical adhesive <NUM> is in an uncured, liquid state, the first lens optical axis <NUM> and the second lens optical axis <NUM> may be aligned, using the apparatuses and methods as will be described in greater detail herein. Once aligned to a predetermined alignment threshold, the optical adhesive <NUM> may be cured so as to rigidly fix the first lens <NUM> to the second lens <NUM>. Because the optical adhesive <NUM> is provided in a liquid, uncured state, the optical adhesive <NUM> may act as a liquid bearing, which supports movement of the first lens <NUM> and/or the second lens <NUM> to align their respective optical axes <NUM>, <NUM>. Accordingly, undue stress introduced into the optical assembly <NUM> and corresponding stress birefringence may be avoided.

Referring now to <FIG> and <FIG>, an embodiment of an alignment apparatus <NUM> for aligning optical axes of two or more components of an optical assembly <NUM> is schematically depicted. The alignment apparatus <NUM> generally includes a chuck <NUM> and an adjustable flexure assembly <NUM>. A "chuck" as used herein is any device that holds a work piece (e.g., a lens) in place. The chuck <NUM> and the adjustable flexure assembly <NUM> may be mounted to a rotation mechanism (e.g., a rotating platform, rotational bearing, or the like) defining a datum axis <NUM>. A "datum axis" as used herein is an axis to which geometric and/or dimensional tolerances are referenced to. The chuck <NUM> and the adjustable flexure assembly <NUM> may be mounted on the rotation mechanism to rotate on a common axis of rotation, which corresponds to the datum axis <NUM> for alignment of components of the optical assembly <NUM>. The chuck <NUM> and the adjustable flexure assembly <NUM> may rotate around the datum axis <NUM> in synchronization with one another. For example and without limitation, a column <NUM> supporting both the chuck <NUM> and the adjustable flexure assembly <NUM> may be coupled to a motor (not shown) which may be controlled (e.g., through an electronic controller) to rotate the chuck <NUM> and the adjustable flexure assembly <NUM>. In embodiments, the chuck <NUM> and the adjustable flexure assembly <NUM> may be freely rotatable (e.g., via a bearing) through manual actuation (e.g., such as a turntable). In embodiments, the alignment apparatus <NUM> may be aligned with or otherwise define the datum axis <NUM> without rotating around the datum axis <NUM>.

The column <NUM> may comprise an upper surface <NUM> on which the chuck <NUM> may be mounted. In embodiments, the column <NUM> and the chuck <NUM> may be integral with one another. In embodiments, the column <NUM> and the chuck <NUM> may be separate components that may mate with one another to rigidly couple the chuck <NUM> to the column <NUM>. For example and with reference to <FIG>, the column <NUM> may define a chuck receiving opening <NUM> configured to receive a mating portion <NUM> of the chuck <NUM> therein. For example, the mating portion <NUM> may nest within the chuck receiving opening <NUM> of the column <NUM>. In embodiments, a retention tab <NUM> may engage with the chuck receiving opening <NUM> to inhibit withdrawal of the chuck <NUM> in the +Z direction of the depicted coordinate axes. Other engagement mechanisms (e.g., fasteners, welding, brazing, or the like) may be used to mount the chuck <NUM> to the column <NUM>.

The chuck <NUM> is configured to support an optical assembly <NUM> thereon. For example, the chuck <NUM> may comprise a support portion <NUM> that is configured to engage with and hold the optical assembly <NUM> thereon. For example, the support portion <NUM> may be a tubular wall extending from a body <NUM> of the chuck <NUM>. The tubular wall may be configured so as to only contact a portion of a surface of the optical assembly <NUM> (e.g., a surface of the first lens <NUM>). The tubular shape of the wall may allow for the avoidance of contact with a quality area of the first lens <NUM> (e.g., an area toward a center of curvature of the first lens <NUM>), thus preserving the surface quality and optical performance of the first lens <NUM>. It is noted that the tubular wall may have any cross section (e.g., circular, elliptical, rectangular, or other regular or irregular polygonal shapes) without departing from the scope of the present disclosure.

In embodiments, the optical assembly <NUM> is secured to the chuck <NUM> through one or more securing means. Such securing means may include, for example and without limitation, a temporary adhesive, vacuum pressure, or the like. When vacuum pressure is used, the chuck <NUM> may be plumbed to a vacuum pressure source (not shown) such that vacuum pressure may be achieved through the support portion <NUM> of the chuck <NUM> to hold an optical assembly <NUM> to the chuck <NUM>. In some embodiments, a vacuum channel <NUM> may extend from the support portion <NUM> of the chuck <NUM> and through the column <NUM>, to provide fluidic communication between the vacuum pressure source (not depicted) and the support portion <NUM> of the chuck <NUM>.

Referring again to <FIG>, the adjustable flexure assembly <NUM> may be disposed around the chuck <NUM> and includes a plurality of flexures (e.g., flexures 150a, 150b, 150c) that are configured to contact a component (e.g., a lens) of the optical assembly <NUM> positioned on the chuck <NUM>. A "flexure," as used herein, is a flexible element that is elastically displaceable and recoverable in at least one plane. For example, the plurality of flexures 150a, 150b, 150c may be elastically displaceable and recoverable in a plane that is parallel to at least a portion of each of the plurality of flexures 150a, 150b, 150c. For example, <FIG> illustrates each of the flexures 150a, 150b, 150c extending parallel to the X-Y plane of the depicted coordinate axes. The flexures 150a, 150b, 150c are elastically displaceable and recoverable within the X-Y plane to contact an edge of the optical assembly <NUM> to cause adjustment of the alignment of the optical assembly <NUM>. In yet further embodiments, the plurality of flexures 150a, 150b, 150c may be elastically displaceable and recoverable through other or multiple planes (e.g., an X-Z plane, a Y-Z plane, and/or any plane angled with respect to the X-Y plane, the X-Z plane, and or the Y-Z plane.

Each flexure 150a, 150b, 150c may be coupled to a corresponding flexure clamp <NUM> (described in greater detail herein) and cantilevered therefrom. For example, with reference to flexure 150a, a first end <NUM> of the flexure 150a may be rigidly held by a dedicated flexure clamp <NUM> and a second end <NUM> of the flexure 150a may extend past the support portion <NUM> of the chuck <NUM> so as to be cantilevered from the end of the flexure clamp <NUM>. The length at which the flexure 150a, 150b, 150c extends from the corresponding flexure clamp <NUM> may be dependent upon the size of the optical assembly <NUM> being aligned. For example, each flexure 150a, 150b, 150c may extend so as to tangentially contact an edge of the optical assembly <NUM>, or a sub-component thereof (e.g., second lens <NUM>), when the optical assembly <NUM> is disposed in the chuck <NUM>. In some embodiments, it is contemplated that one or more flexures 150a, 150b, and/or 150c may be oriented to the edge of the optical assembly <NUM> in a direction normal to the edge of the optical assembly <NUM>. In some embodiments, the plurality of flexures 150a, 150b, 150c may be positioned so as to be oriented perpendicular to the vertical axis (e.g., the Z-axis of the depicted coordinate axis) and radially contact the edge of the optical assembly <NUM>.

Each flexure 150a, 150b, 150c may be made from a resilient material configured to impart a force onto one or more components of the optical assembly <NUM>. For example, each flexure 150a, 150b, 150c may be a wire made from steel, plastic, or the like. Each flexure may have a round, square, rectangular, or any other cross-section. Additionally, while each flexure is depicted as a straight wire, in various embodiments, the flexures may have various contoured shapes (e.g., curved, hooked, s-shaped, o-shaped, etc.). Contact of the plurality of flexures 150a, 150b, and/or 150c with the optical assembly <NUM> may cause one or more of the flexures to bend. Because the flexures 150a, 150b, 150c are resilient, they resist bending, and so impart a radial adjusting force to the component of the optical assembly <NUM> that the flexures 150a, 150b, 150c are contacted with. While it is contemplated that the plurality of flexures 150a, 150b, and/or 150c may deflect when contacted with the optical assembly <NUM>, such deflection may be on a small scale. For example, the deflection or bending may be on a scale of tens of nanometers (e.g., less than about <NUM>, less than about <NUM>, less than about <NUM>, between about <NUM> and about <NUM>, e.g., between about <NUM> and about <NUM>, between about <NUM> and about <NUM>, etc.) relative to the initial position of the flexure 150a, 150b, 150c. The amount of deflection or bending is measured at the free end of the flexure 150b, 150b, 150c (i.e., the end of the flexure proximate to the optical assembly <NUM>) and is the difference in the position of the flexure 150a, 150b, 150c prior to bending (i.e., the initial position) and after bending (i.e., the final position). Because the sub-component (e.g., second lens <NUM>) of the optical assembly <NUM> is not initially aligned (e.g., the optical axes are not aligned within tolerance), the imbalance of forces provided by the plurality of flexures 150a, 150b, 150c guides the optical component into the desired alignment.

Each flexure 150a, 150b, 150c may have a flexural rigidity (or resiliency) which may be chosen based on the size of the lens and/or the viscosity of the optical adhesive <NUM> used to join the components of the optical assembly <NUM>. For example, a larger lens may benefit from a more rigid flexure to affect adjustment, while a smaller lens may require a more flexible flexure to provide fine adjustment. Additionally, an optical adhesive <NUM> having a higher viscosity may benefit from a flexure with a higher flexural rigidity to overcome the damping force of the optical adhesive <NUM>.

The adjustable flexure assembly <NUM> facilitates adjustment of a position of the one or more flexures 150a, 150b, and/or 150c of the plurality of flexures 150a, 150b, 150c relative to the support portion <NUM> of the chuck <NUM> to adjust an alignment of an optical axis of one or more components of the optical assembly <NUM> supported on the support portion <NUM> of the chuck <NUM>. For example, to facilitate positional adjustment of the plurality of flexures 150a, 150b, 150c, the adjustable flexure assembly <NUM> may include a tip-tilt assembly <NUM>. The tip-tilt assembly <NUM> may include a base plate <NUM>, an adjustable plate <NUM>, and one or more adjustment actuators <NUM> (shown in <FIG>). As will be described in greater detail herein, the adjustable plate <NUM> may be tilted relative to the base plate <NUM> to adjust the position of the plurality of flexures (150a, 150b, 150c) coupled thereto.

The base plate <NUM> may comprise a base plate aperture <NUM> for slidably receiving the column <NUM> and the chuck <NUM> therethrough. For example, the base plate <NUM> may be positionable in the +/- Z direction of the depicted coordinate axes along the column <NUM>. For example, the base plate <NUM> may slide to a desired position along the column <NUM> and then be fixed relative thereto by fixing structure <NUM> (e.g., a bracket, collar, clamp, or the like).

The base plate <NUM> may define a support surface <NUM> upon which the adjustable plate <NUM> may be positioned. It is noted that while the base plate <NUM> is depicted as round, the base plate <NUM> may be any shape (e.g., elliptical, rectangular, or any regular or irregular polygonal shape) without departing from the scope of the present disclosure. As illustrated, the base plate aperture <NUM> is sized to allow passage of the column <NUM> and chuck <NUM> therethrough to allow for height adjustment of the base plate <NUM> in the +/-Z direction of the depicted coordinate axes relative to the column <NUM>. By positioning the base plate <NUM> relative to the column <NUM>, the entire tip-tilt assembly <NUM> can be move relative to the support portion <NUM> of the chuck <NUM>. Accordingly, optical assemblies of different dimensions may be aligned using the alignment apparatus <NUM>. That is, as additional lenses are added to the optical assembly <NUM> positioned on the support portion <NUM> of the chuck <NUM>, the base plate <NUM> may be moved up the column <NUM> in the +Z direction of the depicted coordinate axes to allow for adjustment of the added lens.

Additionally, and to facilitate adjustment of the entire tip-tilt assembly <NUM> relative to the column <NUM>, the adjustable plate <NUM> may define an adjustable plate aperture <NUM> that aligns with the base plate aperture <NUM> of the base plate <NUM> such that a continuous opening extends through the base plate <NUM> and the adjustable plate <NUM>. It is noted that while the base plate aperture <NUM> and the adjustable plate aperture <NUM> are illustrated as having substantially equal diameters, in embodiments the base plate aperture <NUM> and the adjustable plate aperture <NUM> may have different diameters.

The adjustable plate <NUM> may be coupled to the base plate <NUM> through the one or more adjustment actuators <NUM>. As used herein, adjustment actuators include any devices that are configured or otherwise capable of adjusting a position (e.g., a tilt, or a position) of the adjustable plate <NUM> relative to the support surface <NUM> of the base plate <NUM>. The one or more adjustment actuators <NUM> may include any actuators capable of tilting or otherwise adjusting a position of the adjustable plate <NUM> relative to the support surface <NUM> of the base plate <NUM>. In embodiments, the one or more adjustment actuators <NUM> may include several adjustment actuators. In embodiments, the number of adjustment actuators may correspond to the number of flexures disposed on the adjustable plate <NUM>. For example, where there are three flexures 150a, 150b, 150c there may be three adjustment actuators corresponding to a position of the three flexures 150a, 150b, 150c to allow for fine adjustment of the position of each flexure 150a, 150b, 150c.

<FIG> illustrates a particular example of an actuator of the one or more adjustment actuators <NUM>. In such embodiments, the one or more adjustment actuators <NUM> may include a push bar <NUM> (e.g., a fine pitch screw) that extends through a thickness T of the base plate <NUM> to contact an underside surface <NUM> of the adjustable plate <NUM>. The push bar <NUM> may include a first end <NUM> and a second end <NUM>. The first end <NUM> of the push bar <NUM> may be coupled to an adjuster <NUM> (e.g., crank, knob, rotary actuator, etc.) configured to adjust a length of the push bar <NUM> which extends through the support surface <NUM> of the base plate <NUM> by rotating the push bar <NUM>.

The second end <NUM> of the push bar <NUM> may extend through the support surface <NUM> of the base plate <NUM> and contact the underside surface <NUM> of the adjustable plate <NUM>. In embodiments, the second end <NUM> of the push bar <NUM> may be coupled (e.g., pivotably coupled) to the underside surface <NUM> of the adjustable plate <NUM> to allow the adjustable plate <NUM> to tilt around the second end <NUM> of the push bar <NUM> without detaching therefrom.

In embodiments, the push bar <NUM> may be threaded along its length between the first end <NUM> and the second end <NUM>. The thread may engage a threaded passage <NUM> extending through the base plate <NUM>. In such embodiments, a twisting motion of the push bar <NUM> may allow the push bar <NUM> to traverse the threaded passage <NUM> to extend through the support surface <NUM> of the base plate <NUM> and push the adjustable plate <NUM> away from contact with the base plate <NUM>. Accordingly, the adjustable plate <NUM> may be tilted at a tilt angle β relative to the support surface <NUM> of the base plate <NUM>, as illustrated in <FIG>. When in contact with a lens, tilting the adjustable plate <NUM> may cause the plurality of flexures 150a, 150b, and/or 150c to push or tilt a position of the lens to which they are contacted to urge the lens into a position to align the optical axis of the contacted lens (e.g., the second lens <NUM>) with the optical axis of the first lens <NUM>.

Referring again to <FIG>, each flexure (150a, 150b, 150c) of the plurality of flexures may be part of a flexure assembly (e.g., flexure assembly 161a, 161b, or 161c) that is coupled to an upper surface <NUM> of the adjustable plate <NUM>. In the illustrated embodiment there is provided a first flexure assembly 161a, a second flexure assembly 161b, and a third flexure assembly 161c. However, there may be a fewer or greater number of flexure assemblies without departing from the scope of the present disclosure. Each of the flexure assemblies 161a, 161b, and 161c may include the flexure clamp <NUM>, a sliding actuator <NUM>, and a stop <NUM>. That is, the alignment apparatus <NUM> may include a plurality of flexure clamps, a plurality of sliding actuators, and a plurality of stops. It is noted that each of the flexure assemblies 161a, 161b, 161c may be substantially identical to one another and circumferentially spaced around the chuck <NUM>.

As used herein, a "flexure clamp" may include any device capable of mounting a flexure (e.g., flexure 150a, 150b, and/or 150c) to the adjustable plate <NUM>. The flexure clamp <NUM> may include a fixed portion <NUM> fixedly coupled to the upper surface <NUM> of the adjustable plate <NUM> and a sliding portion <NUM> configured to slidably move across the upper surface <NUM> of the adjustable plate <NUM> in response to an application of force to the sliding portion <NUM>. To facilitate such sliding movement, the sliding portion <NUM> may be coupled to the fixed portion <NUM> via a flexible webbing <NUM>. As used herein the term "flexible webbing" is the portion of the flexure clamp <NUM> having a reduced cross-section relative to the fixed portion <NUM> of the flexure clamp <NUM>. The reduced cross-section allows the flexible webbing <NUM> to be elastically displaceable and recoverable in at least one plane. In embodiments, the flexible webbing <NUM> may be integral with the sliding portion <NUM> and the fixed portion <NUM> or may be a separate article coupled to the sliding portion <NUM> and the fixed portion <NUM> via any coupling technique (adhesive, welding, fasteners, etc.). For example, the flexure clamp <NUM> may be milled or otherwise formed from the same block of material (e.g., plastic, metal, etc.) such that the fixed portion <NUM>, the sliding portion <NUM>, and the flexible webbing <NUM> are integrally formed. The flexible webbing <NUM> may have a thickness of about <NUM> or (e.g., about <NUM> or less, about <NUM> or less, etc.). As noted above, the flexible webbing <NUM> is elastically displaceable and recoverable in at least one plane. In particular, the flexible webbing <NUM> may be elastically displaceable and recoverable in a plane that is parallel to the upper surface <NUM> of the adjustable plate <NUM>. Stated another way, the flexible webbing <NUM> may comprise a flexural rigidity that provides some resistance to bending and a tendency to resume its previous shape prior to bending. Such flexural rigidity may allow for fine (nanometer scale) adjustments to the portion of the sliding portion <NUM> across the upper surface <NUM> of the adjustable plate <NUM>.

The fixed portion <NUM> of the flexure clamp <NUM> may be immovably coupled to the adjustable plate <NUM> with for example, a bolt <NUM> or other coupling device or method (e.g., fastening, adhering, brazing, welding, etc.). The sliding portion <NUM> may define a flexure support surface <NUM> to support a flexure (e.g., flexure 150a) thereon. The sliding portion <NUM> may comprise a clamping device <NUM> configured to fix a position of the flexure 150a to the flexure support surface <NUM>. Accordingly, the clamping device <NUM> may include any device configured to rigidly hold a portion of the flexure 150a to the sliding portion <NUM>. For example, one or more bolts may be coupled to the sliding portion <NUM> to clamp the flexure 150a to the sliding portion <NUM> with a flange (or washer) of the one or more bolts.

During adjustment, the sliding portion <NUM> is configured to slide across the upper surface <NUM> of the adjustable plate <NUM> when a force acts thereon, which introduces a bending moment in the flexible webbing <NUM>. This may allow for positioning of the flexure 150a relative to the optical assembly <NUM> supported on the chuck <NUM> such that alignment of different sized optical assemblies (e.g., optical assemblies with larger or smaller diameters (e.g., less <NUM>)) may be facilitated.

A sliding actuator <NUM> may be coupled to the upper surface <NUM> of the adjustable plate <NUM>. As used herein, a "sliding actuator" may include any device that is capable or sliding or displacing the sliding portion <NUM> of the flexure clamp <NUM> to a desired position relative to the adjustable plate <NUM>. For example, the sliding actuator <NUM> may be positioned on one side of the sliding portion <NUM> of the flexure clamp <NUM>. The sliding actuator <NUM> may include a plunger <NUM> (e.g., a fine pitch screw) which can be extended or retracted (e.g., manually with a handle, crank, or similar device or with an electronic actuator). The plunger <NUM> may contact the sliding portion <NUM> of the flexure clamp <NUM> and push the sliding portion <NUM> thereby introducing a bending moment in the flexible webbing <NUM>, which displaces the sliding portion <NUM> to the desired position. In some embodiments, the plunger <NUM> may be coupled to the sliding portion <NUM> of the flexure clamp <NUM> to facilitate sliding of the sliding portion <NUM> in a clockwise and/or counter clockwise direction about the fixed portion <NUM> across the upper surface <NUM> of the adjustable plate <NUM>. In other embodiments, the plunger <NUM> may not be coupled to the sliding portion <NUM> of the flexure clamp <NUM>. For example, the plunger <NUM> may only contact the sliding portion <NUM> of the flexure clamp <NUM> to move the sliding portion <NUM> of the flexure clamp <NUM> across the upper surface <NUM> of the adjustable plate <NUM> and then be moved out of contact with the sliding portion <NUM> of the flexure clamp <NUM> to allow the sliding portion <NUM> to be biased by the flexible webbing <NUM> back to its original position. The plunger <NUM> may be controllably positioned via an electronic, pneumatic, or hydraulic actuator, with an electronic controller or may be manually advanced and/or retracted.

The stop <NUM> may be coupled to the adjustable plate <NUM> proximate to the sliding portion <NUM> and on an opposite side of the sliding portion <NUM> of the flexure clamp <NUM> from the sliding actuator <NUM>. The stop <NUM> may be positioned so as to limit further displacement of the sliding portion <NUM> of the flexure clamp <NUM> about the fixed portion <NUM> in the clockwise direction, for example. The stop <NUM> may include stopper member <NUM> (e.g., a bolt, set screw, spring, etc.) or similar structure that can be advanced into contact with the sliding portion <NUM> of the flexure clamp <NUM> to rigidly hold the sliding portion <NUM> of the flexure clamp <NUM> in the desired position between the sliding actuator <NUM> and the stop <NUM>. Similar to the plunger <NUM>, the stopper member <NUM> may be controllably positioned via an electronic, pneumatic, or hydraulic actuator, with an electronic controller or may be manually advanced and/or retracted.

During use, the sliding portions <NUM> of the flexure clamps <NUM> can be moved by the one or more sliding actuators <NUM> to contact the plurality of flexures 150a, 150b, 150c with the tops lens (e.g., the second lens <NUM>) of the optical assembly <NUM>. Such contact may introduce a bending moment into one or more flexures 150a, 150b, and/or 150c of the plurality of flexures 150a, 150b, 150c, which causes the top lens to be urged into a desired alignment. To mitigate the inducement of stresses within components of the optical assembly <NUM> or the optical adhesive <NUM> during alignment, the force applied by the plurality of flexures 150a, 150b, 150c to the optical assembly <NUM> may be relatively low. For example, a force/displacement ratio of the each flexure (150a, 150b, 150c) of the plurality of flexures 150a, 150b, 150c may be equal to about <NUM> x <NUM>-<NUM> N/mm to about <NUM> x <NUM>-<NUM> N/mm. The bending of a flexure may be proportional to a length of the flexure to the third power and inversely proportional to the diameter of the flexure to the fourth power. For example, a steel flexure having a diameter of <NUM> to <NUM> and a length of about <NUM> to about <NUM> provides a length to diameter ratio of about <NUM>:<NUM> to about <NUM>:<NUM>, when displacing a lens having a mass of less than <NUM> grams, the force/displacement ratio may be approximated using conventional beam bending calculations. As noted above, such force/displacement ratio may be equal to about <NUM> x <NUM>-<NUM> N/mm to about <NUM> x <NUM>-<NUM> N/mm and may provide enough force for fine (e.g., micro-radian or sub-micron level) adjustments and sufficient friction to maintain contact with the optical assembly <NUM>. It is noted that the greater the bending of the flexure, the less force it applies to the component of the optical assembly <NUM>. Conversely too little bending may not allow for fine adjustments to align the optical axes of the optical assembly <NUM>.

It is noted that the plurality of flexures 150a, 150b, and 150c may be moved into contact with a component of the optical assembly <NUM> such that only a single flexure of the plurality of flexures 150a, 150b, and 150c bends thereby providing increased force on the optical assembly <NUM> at that flexure. However, the total resultant force acting on the optical assembly <NUM> does not change significantly as the two opposite flexures (e.g., non-bending flexures) balance the increased force of the single bending flexure. This imbalance causes the component of the optical assembly <NUM> in contact with the plurality of flexures 150a, 150b, 150c to move into alignment while maintaining a low stress condition within the optical assembly <NUM>.

Referring now to <FIG>, the alignment apparatus <NUM> may further include a centration measurement apparatus <NUM>, such as an alignment telescope, a displacement measuring sensor, or other metrology devices, configured to measure an optical axis alignment of one or more components of an optical assembly. For example, a commercially available Trioptics OpticCentric® Measuring Device uses a light signal directed into the optical article to determine the location of an optical axis of the top lens and provide feedback as to the alignment. The centration measurement apparatus <NUM> may detect or otherwise measure the location of an optical axis of the top lens relative to the datum axis <NUM> and provide feedback of position to a user, an electronic controller, or a combination thereof. Based on this information, the user, or the electronic controller can adjust the positions of the one or more flexures 150a, 150b, and/or 150c (e.g., with the one or more adjustment actuators <NUM> and/or the one or more sliding actuators <NUM>) to align the optical axes <NUM>, <NUM> as desired. As shown in FIGS. 4A-4D the centration measurement apparatus <NUM> may be positioned over the support portion <NUM> of the chuck <NUM> to measure optical alignment of an optical assembly <NUM> positioned thereon.

<FIG> depicts a flow chart of a method <NUM> for aligning components of an optical assembly <NUM>. It is noted that while the method <NUM> illustrates a number of steps in a specific order, it is noted that a greater or fewer number of steps may be performed without departing from the scope of the present disclosure. Additionally, such steps may be taken in a different order than depicted without departing from the scope of the present disclosure.

In a first step <NUM>, a first lens <NUM> of an optical assembly <NUM> may be positioned on the support portion <NUM> of the chuck <NUM>, as described above. As noted herein, the first lens <NUM> may be held in place using, for example, vacuum pressure. The first lens optical axis <NUM> may be aligned with the datum axis <NUM> of the assembly. For example, using the centration measurement apparatus <NUM>, the alignment of the first lens optical axis <NUM> of the first lens <NUM> may be determined and positioned so as to be aligned with the Z-axis of the depicted coordinate axes. In the illustrated embodiment, the first lens <NUM> is a bi-convex lens. It is noted that placing a convex side of the first lens <NUM> into contact with the chuck <NUM> may allow the chuck <NUM> to better seal against the lens. It is also noted the first lens <NUM> may be any other type of lens as described herein.

Once aligned and mounted to the chuck <NUM>, the first lens coupling surface <NUM> of the first lens <NUM> may be coated with an optical adhesive <NUM>, as described herein, at step <NUM>. The optical adhesive <NUM> may be applied in a liquid state. At step <NUM>, the second lens <NUM> may be placed on the first lens <NUM>. The second lens coupling surface <NUM> of the second lens <NUM> may also be coated with the liquid optical adhesive <NUM>. The second lens <NUM> may be a concave lens so as to mate with a convex surface of the first lens <NUM>. During initial engagement of the first lens <NUM> with the second lens <NUM>, the plurality of flexures (150a, 150b, 150c) may be positioned so as to not contact any portion of the optical assembly <NUM>. As shown in <FIG>, once the second lens <NUM> is positioned on the first lens <NUM>, an operator may move the plurality of flexures (150a, 150b, 150c) into contact with the edge <NUM> of the second lens <NUM>, at step <NUM>. As noted above, the plurality of flexures (150a, 150b, 150c) may be brought into contact with a top surface of the lens (such as when the top lens has a convex top surface and a very small edge surface) by application of force by the one or more sliding actuators <NUM> to the sliding portion <NUM> of the one or more flexure clamps <NUM> to introduce a bending moment in the flexible webbing <NUM> to allow the sliding portion <NUM> to slide across the upper surface <NUM> of the adjustable plate <NUM>. It is noted that while the sliding portion <NUM> may slide across the upper surface <NUM> of the adjustable plate <NUM>, the sliding portion <NUM> need not be in contact with the upper surface <NUM> of the adjustable plate <NUM>. For example, and as illustrated in <FIG>, the sliding portion <NUM>, and the flexible webbing <NUM> in some embodiments, may be spaced from the adjustable plate <NUM> in the Z direction of the depicted coordinate axes, such that an air gap <NUM> separates the sliding portion <NUM> and the upper surface <NUM> of the adjustable plate <NUM>. Accordingly, friction between the sliding portion <NUM> and the adjustable plate <NUM> may be avoided. When sliding the sliding portion <NUM>, the flexible webbing <NUM> may deflect a small amount (e.g., less than about <NUM>, less than <NUM>, less than <NUM>, etc.) to cause placement of the plurality of flexures 150a, 150c, 150b. Additionally, the tip-tilt assembly <NUM> may adjustment the tilt of the adjustable plate <NUM> relative to the base plate <NUM> for proper positioning of the one or more flexures 150a, 150b, 150c so as to contact a non-quality area of the lens. Avoiding contact to the quality area of the lens (e.g., away from the optical axis, may prevent unwanted damage to the quality area of the lens.

The centration measurement apparatus <NUM> may measure the optical axis alignment of the second lens optical axis <NUM> relative to the datum axis <NUM>, to which the first lens optical axis <NUM> is aligned. Based on the feedback, which may be provided to the operator through a user interface such as a display, the operator, or an electronic controller, may adjust one or more flexures of the plurality of flexures (e.g., flexures 150a, 150b, and/or 150c) with, for example, the one or more adjustment actuators <NUM> and/or the one or more sliding actuators <NUM> to gently move the second lens optical axis <NUM> of the second lens <NUM> into alignment with the first lens optical axis <NUM> of the first lens <NUM> within tolerance, at step <NUM>. As noted herein, movement of the second lens <NUM> into an aligned position may occur while the optical adhesive <NUM> is in a liquid, uncured state, such that the optical adhesive <NUM> acts as a liquid bearing to reduce the introduction of stress into the optical adhesive <NUM> layer, as may occur when the optical adhesive <NUM> is partially cured. Throughout measuring and alignment, the alignment apparatus <NUM> may be rotating about the datum axis <NUM> (e.g., at about <NUM> RPM). Once alignment is achieved within the preferred tolerance (which may take less than <NUM> minutes or between about <NUM> and <NUM> minutes), at step <NUM>, the optical adhesive <NUM> may be cured (e.g., with IR-curing, time, UV-curing, or combinations thereof). After curing, the process may be repeated with additional lenses being added to the optical assembly <NUM>. As noted above, the height of the adjustable flexure assembly <NUM> may be adjusted along the column <NUM> to facilitate adding additional lenses to the optical assembly <NUM>.

In some embodiments, the optical adhesive <NUM> may be replaced with a temporary liquid acts as a liquid bearing to assist with alignment. Examples of temporary liquids include, but are not limited to, water, alcohol, hydroxide solutions, any combinations thereof, or the like. Such temporary liquids may evaporate to initiate very close contact of surfaces of the first and second lenses and/or enable chemical bonding at the atomic level between surfaces. For example, when proper alignment is achieved, as described above, the liquid may be allowed to evaporate such that the two opposing surfaces of the first lens <NUM> and the second lens <NUM> come into contact with one another while remaining aligned. An atomic or molecular level bonding (e.g., through diffusion bonding, optical contact bonding, chemically activated bonding, etc.) may then be achieved between the first lens <NUM> and the second lens <NUM> to provide an adhesive-free bond. That is, embodiments described herein may perform alignment using either an adhesive <NUM> or other low viscosity liquid (e.g., less than about <NUM> cps or from about <NUM> cps to <NUM> cps). Accordingly, any description provided above in regards to alignment using an optical adhesive is equally applicable to alignment using a temporary liquid that is later evaporated.

Alignment using the alignment apparatus <NUM> as described herein, may reduce stress in the optical assembly <NUM>. As noted above, stress can cause birefringence, which induces a change in the polarization state of the transmitted light through the optical assembly <NUM>. Alignment using the described methods and apparatuses allow for the polarization state of light transmission through assemblies or systems to be maintained to maximize the transmitted intensity or transmitted intensity uniformity for the system. This property may be quantified using a conventional light polarization measurement device (e.g., including, but not limited to, a polarized light source, one or more waveplates, an analyzing polarizer, and/or a detector) and an article or system under test to determine a polarized light transmission efficiency ratio, or inversely, an extinction ratio for certain polarization states. For example, the measurement of the polarization performance can be done with polarizers and intensity detectors for the appropriate wavelengths or with commercially available polarimeter equipment from, for example, Hinds Instruments™ (e.g., Stokes Polarimeters) or Ilis (e.g., Strain Scope ®) for making optical retardance measurements. For example, an article with very little birefringence can be quantified with a very high extinction ratio (e.g., <NUM>: <NUM> or greater) when evaluated with a linear polarizer measurement device. Optical assemblies with significant birefringence may exhibit extinction ratios on the scale of <NUM>:<NUM> or <NUM>:<NUM>. Optical assemblies subjected to alignment methods and apparatuses as described herein exhibit extinction ratios of greater than <NUM>: <NUM> (e.g., greater than <NUM>: <NUM>, greater than <NUM>: <NUM>, greater than <NUM>: <NUM>, etc.). However, optical assemblies produced with partially cured adhesives often have extinction ratios of less than <NUM>:<NUM> or even less than <NUM>:<NUM>. Accordingly, embodiments as described herein provide for reduced stress compared to optical assemblies aligned using a partially cured adhesive during alignment.

It should now be understood that embodiments provided herein are directed to apparatuses and methods for aligning components of an optical assembly. For example, an alignment apparatus for aligning components of an optical assembly may include a chuck configured to support the optical assembly thereon, and an adjustable flexure assembly. The adjustable flexure assembly may be disposed around the chuck and include a plurality of flexures. The plurality of flexures may are configured to contact an edge of the optical assembly. Adjustment of a position of one or more flexures of the plurality of flexures causes an adjustment in an optical axis alignment of one or more components of the optical assembly. Accordingly, alignment of the optical axis of the various components of the optical assembly may be achieved. Flexures may provide a subtle force to move the components of the optical assembly to encourage alignment. Such subtle contact may decrease force disturbances within an adhesive positioned between optical components, and provide for better quality optical assemblies.

Claim 1:
An alignment apparatus (<NUM>) for aligning components of an optical assembly (<NUM>), the alignment apparatus (<NUM>) comprising:
a chuck (<NUM>) configured to support the optical assembly (<NUM>) thereon; and
an adjustable flexure assembly (<NUM>) disposed around the chuck (<NUM>), the adjustable flexure assembly (<NUM>) comprising a plurality of flexures (150a, 150b, 150c), wherein:
the plurality of flexures (150a, 150b, 150c) are positioned relative to the chuck (<NUM>) such that each of the plurality of flexures (150a, 150b, 150c) contact the optical assembly (<NUM>) when the optical assembly (<NUM>) is positioned on the chuck (<NUM>); and
adjustment of a position of one or more flexures (150a, 150b, 150c) of the plurality of flexures (150a, 150b, 150c) adjusts an alignment of an optical axis of an optical component of the optical assembly (<NUM>) when the optical assembly (<NUM>) is positioned on the chuck (<NUM>), wherein the alignment apparatus (<NUM>) is configured to align optical axes of the optical components to an angle of deviation (α) of less than about <NUM>,<NUM> grad and provide a polarization extinction ratio within the optical assembly (<NUM>) of greater than or equal to <NUM>: <NUM>;
wherein the adjustable flexure assembly (<NUM>) is rotatable around a datum axis (<NUM>);
wherein the adjustable flexure assembly (<NUM>) further comprises a tip-tilt assembly (<NUM>) disposed around the chuck (<NUM>), the tip-tilt assembly (<NUM>) comprising:
a base plate (<NUM>) defining a support surface (<NUM>);
an adjustable plate (<NUM>) adjustably coupled to the base plate (<NUM>), the adjustable plate (<NUM>) supporting the plurality of flexures (150a, 150b, 150c) thereon; and
one or more adjustment actuators (<NUM>) configured to adjust a position of the adjustable plate (<NUM>) relative to the support surface (<NUM>) of the base plate (<NUM>).