Patent ID: 12216269

Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.

DETAILED DESCRIPTION

An initial overview of the inventive concepts are provided below and then specific examples are described in further detail later. This initial summary is intended to aid readers in understanding the examples more quickly, but is not intended to identify key features or essential features of the examples, nor is it intended to limit the scope of the claimed subject matter.

According to one example of the present disclosure, a deformable mirror is provided that can include a mirror assembly. The mirror assembly can comprise a reflective face sheet having a reflective surface on a front side of the reflective face sheet, and one or more ferrous materials selectively positioned within the mirror assembly. The deformable mirror can further comprise one or more electromagnets operable to generate a magnetic field that acts on the one or more ferrous materials to deform the reflective face sheet.

In one example, the one or more ferrous materials can comprise ferrous particles integrated into the reflective face sheet. The reflective face sheet can have a non-uniform thickness between the front side of the reflective face sheet and a back side that is opposite the front side to provide stiffness for the reflective face sheet. The non-uniform thickness of the reflective face sheet can be defined by a pattern formed in the back side. The pattern can comprise an array of polygon shapes.

In another example, the deformable mirror can also comprise a base in support of the mirror assembly and the one or more electromagnets. The base can comprise mounting features for mounting the one or more electromagnets to the base. For example, the one or more electromagnets can be positioned relative to a back side of the reflective face sheet opposite the front side. The one or more electromagnets can comprise a plurality of electromagnets.

In one aspect of the disclosure, the mirror assembly can comprise a compliant ferrous backing attached to a back side of the reflective face sheet opposite the front side. The one or more ferrous materials can comprise ferrous particles embedded into the compliant ferrous backing. In one example, the ferrous particles can be distributed non-uniformly throughout the compliant ferrous backing.

The compliant ferrous backing can comprise a relatively high ferrous particle concentration portion having a relatively higher concentration of the ferrous particles and a relatively low ferrous particle concentration portion having a relatively lower concentration of the ferrous particles. The high ferrous particle concentration portion can be part of a plurality of high ferrous particle concentration portions, and the low ferrous particle concentration portion can be part of a plurality of low ferrous particle concentration portions, where the plurality of high and low ferrous particle portions can form a pattern in the compliant ferrous backing. In one example, the pattern can comprise an array of polygon shapes.

According to one aspect, the reflective face sheet can comprise a uniform thickness from the front side to the back side. On the other hand, the reflective face sheet can have a non-uniform thickness between the front side of the reflective face sheet and a back side that is opposite the front side to provide stiffness for the reflective face sheet. The non-uniform thickness of the reflective face sheet can be defined by a pattern formed in the back side. The pattern can comprise an array of polygon shapes. The deformable mirror can also comprise a compliant ferrous backing molded to fit within the pattern formed in the back side of the reflective face sheet, wherein ferrous materials in the form of ferrous particles can be embedded into the compliant ferrous backing.

In one aspect of the disclosure, the mirror assembly can comprise a thin ferrous metallic backing positioned relative to a back side of the reflective face sheet opposite the front side, the thin ferrous metallic backing comprising a ferrous material of the one or more ferrous materials.

In one aspect of the present disclosure, a deformable mirror system is provided. The deformable mirror system can comprise a deformable mirror that can include a mirror assembly. The mirror assembly can comprise a reflective face sheet having a reflective surface on a front side of the reflective face sheet, and one or more ferrous materials selectively positioned within the mirror assembly. The deformable mirror can further comprise one or more electromagnets operable to generate a magnetic field that acts on the one or more ferrous materials to deform the reflective face sheet.

The deformable mirror system can further comprise a control system operably coupled to the one or more electromagnets to control the magnetic field, and thereby a deformation of the reflective face sheet.

In one aspect of the disclosure, the mirror assembly can comprise a compliant ferrous backing attached to a back side of the reflective face sheet opposite the front side. The one or more ferrous materials can comprise ferrous particles embedded into the compliant ferrous backing. In one example, the ferrous particles can be distributed non-uniformly throughout the compliant ferrous backing.

The compliant ferrous backing can comprise a relatively high ferrous particle concentration portion having a relatively higher concentration of the ferrous particles and a relatively low ferrous particle concentration portion having a relatively lower concentration of the ferrous particles. The high ferrous particle concentration portion can be part of a plurality of high ferrous particle concentration portions, and the low ferrous particle concentration portion can be part of a plurality of low ferrous particle concentration portions, where the plurality of high and low ferrous particle portions can form a pattern in the compliant ferrous backing. In one example, the pattern can comprise an array of polygon shapes.

In one aspect of the disclosure, the mirror assembly can comprise a thin ferrous metallic backing attached to a back side of the reflective face sheet opposite the front side.

According to one aspect, the reflective face sheet can comprise a uniform thickness from the front side to the back side. On the other hand, the reflective face sheet can have a non-uniform thickness between the front side of the reflective face sheet and a back side that is opposite the front side to provide stiffness for the reflective face sheet. The non-uniform thickness of the reflective face sheet can be defined by a pattern formed in the back side. The pattern can comprise an array of polygon shapes. The deformable mirror can also comprise a compliant ferrous backing molded to fit within the pattern formed in the back side of the reflective face sheet, wherein ferrous particles are embedded into the compliant ferrous backing.

In one aspect of the present disclosure, a method for facilitating active shape control of a mirror is provided. The method can comprise obtaining a mirror assembly comprising a reflective face sheet, positioning one or more ferrous materials within at least a portion of the mirror assembly, and disposing one or more electromagnets about the mirror assembly operable to generate a magnetic field that acts on the one or more ferrous materials to deform the reflective face sheet and thereby control a shape of the reflective surface.

In one example, the method can further comprise adhering a compliant ferrous backing onto a back side of the reflective face sheet. The one or more ferrous materials can comprise ferrous particles distributed throughout the compliant ferrous backing. In one example, the ferrous particles can be distributed non-uniformly throughout the compliant ferrous backing. The compliant ferrous backing can comprise a relatively high ferrous particle concentration portion having a relatively higher concentration of the ferrous particles and a relatively low ferrous particle concentration portion having a relatively lower concentration of the ferrous particles. The high ferrous particle concentration portion can be part of a plurality of high ferrous particle concentration portions, and the low ferrous particle concentration portion can be part of a plurality of low ferrous particle concentration portions. The plurality of high and low ferrous particle portions can form a pattern in the compliant ferrous backing. The pattern can comprise an array of polygon shapes.

To further describe the present technology, examples are now provided with reference to the figures. With reference toFIGS.1-4, one example of a deformable mirror system100is illustrated. The deformable mirror system100can comprise a deformable mirror101and a control system102operable to control one or more controllable components the deformable mirror101. The deformable mirror101can comprise a mirror assembly109including a reflective face sheet110and a compliant ferrous backing120(or a thin ferrous metallic backing (seeFIG.9)). The deformable mirror101can further comprise one or more electromagnets130and a support structure140. The deformable mirror101is shown in a top perspective view inFIG.1, a bottom perspective view inFIG.2, a front view inFIG.3, and a front view with portions of the support structure140removed inFIG.4. A front side103and a back side104of the deformable mirror101and its components are indicated generally inFIGS.1-4.

The compliant ferrous backing120of the mirror assembly109can be formed of a compliant material that has one or more ferrous materials positioned within at least a portion of the mirror assembly. For example, as will be discussed in more detail below, the one or more ferrous materials can comprise ferrous particles distributed throughout a compliant ferrous backing, or in another example, the one or more ferrous materials can comprise a thin ferrous metallic backing. The reflective face sheet110of the mirror assembly109can cover a front side of the compliant ferrous backing120such that a back side of the reflective face sheet110is adhered or otherwise secured to the compliant ferrous backing120. The reflective face sheet110can have a reflective surface111on a front side of the reflective face sheet110opposite a back side. The reflective face sheet110can be constructed of any suitable material, such as silicon, glass, aluminum, beryllium, or others as will be apparent to those skilled in the art.

The electromagnets130can be positioned relative to the back side of the mirror assembly109(e.g., behind the compliant ferrous backing120). Any suitable number of electromagnets130can be utilized, such as only a single electromagnet or multiple electromagnets. Additionally, the electromagnets130can be the same size or different sizes (e.g., varying in diameter, height, etc.).

The control system102can be operably coupled to electromagnets130to control a magnetic field generated by the electromagnets130. The various structural components of the deformable mirror101(e.g., the support structure140) can be made of non-ferromagnetic materials, such as aluminum, to avoid undesirable magnetic field effects during operation of the electromagnets130.

The compliant ferrous backing120can be formed using an adhesive binder that has a plurality of ferrous particles distributed throughout the adhesive binder. For example, the adhesive binder can be formed from an epoxy, silicone, fluorosilicone, polyurethane, rubber, or other similar materials. A ferrite powder can be mixed into the adhesive binder to distribute the ferrous particles evenly throughout the adhesive binder. A layer of the adhesive binder with the ferrous particles can then be adhered to the back side of the reflective face sheet110to form the compliant ferrous backing120. The compliant ferrous backing120can be formed of a material having properties to allow the compliant ferrous backing120to be relatively rigid or stiff, such that it holds its shape, while also being sufficiently compliant for the purposes described herein. For example, the compliant ferrous backing120can be formed from a material having a shore hardness of at least 10, namely between 10 and 100. An example of an epoxy suitable for use as an adhesive binder for the compliant ferrous backing120is known under the trade name MASTERSIL, such as MASTERSIL980. In some examples, non-adhesive materials can be used as a base material through which the ferrous particles can be distributed. A non-adhesive material can be adhered to the back of the reflective face sheet110via a separate adhesive.

In some examples, a weight percentage of the ferrous particles in the compliant ferrous backing120can be from 20% to 70%. In some examples, the ferrous particles used in the compliant ferrous backing120can be sized between 1 μm to 1 mm in diameter. However, these are not intended to be limiting in any way. Indeed, other weight percentages are contemplated, which can depend upon the particular application.

The electromagnets130can be operable to generate a magnetic field that acts on the ferrous particles in the compliant ferrous backing120. This magnetic field can cause the compliant ferrous backing120to locally deform based on the position and strength of the magnetic field generated by the electromagnets130. The deformations of the compliant ferrous backing120function to cause a deformation of the reflective face sheet110based on the interface between the compliant ferrous backing120and the reflective face sheet110.

In particular, as current flows through one or more of the electromagnets130, one or more localized magnetic fields are created. The magnetic field(s) generated by the electromagnets130can act on the compliant ferrous backing120to induce a localized deformation in the compliant ferrous backing120. This in turn can induce a localized stress or load on the reflective face sheet110to locally deform the reflective face sheet110along with the compliant ferrous backing120. In this manner, the electromagnets130can be referred to as actuators that act on the mirror assembly109to cause select; precision deformations within the mirror assembly109. For example, the electromagnets can pull on or actuate the compliant ferrous backing120to deform the reflective face sheet110adhered to the compliant ferrous backing120. An actuator stroke can refer to the deflection of the reflective surface111by a single electromagnet130or actuator; referred to as a “poke.”

One benefit of the present technology is that forces exerted on the reflective face sheet110do not produce “quilting” effects often associated with discrete actuators (e.g., mechanical or electromechanical actuators) in other types of deformable mirrors. This is because the actuators are not mechanically coupled to the face sheet. In prior deformable mirrors where the actuators are mechanically coupled to the face sheet; differences in the coefficient of thermal expansion (CTE) between the bonding material and the other surrounding materials contribute to the quilting patterns as temperature changes.

In one aspect, the control system102can be operable to independently control (e.g., independently power) each of the electromagnets130for optimum shape control of the reflective face sheet110. For example, pokes of each electromagnet130can be measured by an interferometer. A linear combination of these pokes can create many different mirror shapes. In a particular aspect, the control system102can be operable to reverse polarity of the electromagnets130(e.g., reverse current polarity of the individual electromagnets130, such as reversed polarity in adjacent electromagnets) to provide further control over the shape of the reflective face sheet110, and to create pokes between actuators. Thus, the electromagnets130can be energized in a coordinated manner by the control system102to generate a magnetic field operable to achieve a desired shape or response of the reflective face sheet110. For example, a boundary condition shape on the reflective face sheet110can be controlled to achieve optical power correction for various mirror angles of incidence, to control or correct wave front error, etc.

In one aspect, the deformable mirror101can include a heat transfer device105thermally coupled to the electromagnets130to facilitate cooling the electromagnets130, which can allow for more current, thereby increasing actuator stroke. The heat transfer device105can be of any suitable type or configuration known in the art, such as any suitable passive or active heat transfer device.

For example, the heat transfer device105can include a liquid coolant contained in cooling jackets about the electromagnets130. The liquid can be heated by the electromagnets130(e.g., by wire coils or windings of the electromagnets) and can flow away from the electromagnets130where the liquid can be cooled, e.g., by a heat exchanger, fins, etc. Fluid flow can be forced to actively cool the electromagnets130or it can be driven by natural convection to passively cool the electromagnets130. Any suitable liquid coolant can be utilized, such as ethylene glycol mixed with water (EGW), or polyalphaolefin (PAO).

In one aspect, the support structure140can include a base141in support of the electromagnets130and the mirror assembly109(i.e., the compliant ferrous backing120and the reflective face sheet110). The support structure140can also include one or more stand-off supports142coupling the mirror assembly109to the base141. The mirror assembly109can be secured to the stand-off supports142in any suitable manner.

For example, the support structure140can include a front clamping ring146and a back clamping ring147. The mirror assembly109can be disposed between the front clamping ring146and the back clamping ring147such that the front clamping ring146and the back clamping ring147support and secure the mirror assembly109to the stand-off supports142. One or more mounting features143can be used to attach the front clamping ring146and the back clamping ring147to the stand-off supports142and to secure the mirror assembly109between the front clamping ring146and the back clamping ring147. For example, the mounting features143can comprise one or more fasteners143that tighten the front clamping ring146to the back clamping ring147and that connect the front clamping ring146and the back clamping ring147to the stand-off supports142. The mounting features143can be of any suitable type or configuration, such as a socket, pin, tab, bracket, fastener, or any other suitable mounting device or assembly.

In one example, the mirror assembly109can be magnetically attached to the back clamping ring147and the front clamping ring146can be omitted. Because the mirror assembly109comprises the compliant ferrous backing120, one or more magnets can be distributed throughout the back clamping ring147. The mirror assembly109can then be attached and held to the back clamping ring147via a magnetic attraction between the magnets in the back clamping ring147and the compliant ferrous backing120. This can help ensure that uneven stress is not placed on the reflective face sheet110when it is mounted to the support140. Uneven stresses on the reflective face sheet110can cause distortions in the deformable mirror101.

In one aspect, the compliant ferrous backing120and the electromagnets130can be physically independent from one another (e.g., not affixed or directly joined to one another). In other words, in this example, the compliant ferrous backing120and the electromagnets130can be in direct physical contact, but not attached or joined together at such an interface. Thus, the electromagnets130are not directly physically coupled the compliant ferrous backing120or the reflective face sheet110. Physically separate components can enable a modular design where the electromagnets130, the compliant ferrous backing120, and/or the reflective face sheet110can be easily reconfigured or replaced for a given application or repair. This is not to be limiting in any way. Indeed, examples are contemplated where the compliant ferrous backing120and one or more of the electromagnets130are directly joined together.

A thickness of the compliant ferrous backing120can influence actuator stroke. Therefore, the thickness of the compliant ferrous backing120can be changed to achieve a desired response. In addition, the reflective face sheet110can have any suitable size or shape, such as circular, elliptical, polygonal (e.g., triangle, rectangle, pentagon, hexagon, octagon, etc.), freeform, etc. Different face sheet configurations (e.g., size, shape, and non-uniform thickness characteristics described below) can provide different performance attributes. Thus, the reflective face sheet110and/or the compliant ferrous backing120can be selected or changed to achieve a desired mirror response.

In one example, the compliant ferrous backing120and the electromagnets130can be physically separated from one another by a gap131, as shown inFIG.4. Such a gap131can be provided by positioning the compliant ferrous backing at a height144from the base141that exceeds a height132of the electromagnets130from the base141. The gap131can be of any suitable size to enable ease of assembly/disassembly for reconfiguring or replacing components, although the gap131may be minimized for improved influence of the electromagnets130on the compliant ferrous backing120.

The base141can include mounting features143for mounting the electromagnets130to the base141. The mounting features143can be of any suitable type or configuration, such as a socket, pin, tab, bracket, fastener, or any other suitable structure for mounting an electromagnet130to the base141. In some examples, a number of the mounting features143can exceed a number of the electromagnets130to provide alternate mounting arrangements for the electromagnets130on the base141. Thus, an electromagnet130array pattern, pitch, spacing, quantity, size, shape, etc. can be adjusted by appropriately configuring the number and location of the mounting features143on the base141.

In general, the reflective face sheet110can have any suitable configuration (e.g., size, shape, thickness, etc.) for a given application. For example, in some applications (e.g., when the deformable mirror101is mounted on a static or slow-moving platform) a uniform thickness may be suitable for the reflective face sheet110. In other applications (e.g., when the deformable mirror101is mounted on a dynamic or fast-moving platform), a uniform thickness may not provide the performance required of the reflective face sheet110. In a particular example, in order to operate in a tactical, airborne environment, a uniform thickness reflective face sheet may not allow for an adequate actuator stroke, since the face sheet must be thick enough to minimize wave front error due to gravity sag (e.g., mirror deflection due to gravity) as well as increasing the natural frequency of the mirror surface (e.g., maximize structural modes so that vibration does not impact performance). Thus, the thickness required to provide adequate stiffness for gravity sag and structural mode considerations can greatly limit the magnitude of wave front error that can be corrected by a uniform thickness face sheet.

Therefore, in one aspect, the reflective face sheet110can have a non-uniform thickness between the front and back sides of the reflective face sheet110to provide adequate stiffness for the reflective face sheet110in meeting gravity sag and structural mode design objectives while also providing for sufficient actuator stroke to correct a large magnitude of wave front error. In other words, a non-uniform thickness of the reflective face sheet110can improve actuator stroke (e.g., increase influence of actuators on the face sheet), while simultaneously improving gravity sag and stiffness over a uniform thickness face sheet. Thus, a non-uniform thickness reflective face sheet110can be designed to optimize (e.g., maximize) actuator stroke and minimize gravity sag, which can facilitate tuning a mirror for different platforms. These principles are discussed in more detail below with reference toFIGS.5A-7D.

FIGS.5A-7Dillustrate non-uniform thickness reflective face sheets310,410,510in accordance with several examples of the present disclosure. It should be noted that the topology due to non-uniform thickness of the reflective face sheets310,410,510is evident on respective back sides304,404,504of the reflective face sheets310,410,510, as the respective reflective front sides303,403,503are maintained flat or featureless to provide suitable reflective surfaces311,411,511.

The non-uniform thickness of the reflective face sheets310,410,510can be configured in any suitable manner to provide a desired stiffness and/or actuator responsiveness. In one aspect, the non-uniform thickness can be defined by a pattern formed on the respective back sides304,404,504of the reflective face sheets310,410,510. Any suitable uniform or non-uniform pattern can be implemented, and can include any shape or combination of shapes, lines, curves, raised portions, etc. of any suitable size or configuration. In one illustrated example, the pattern comprises a polygon (e.g., hexagon) shape in a “honeycomb” pattern (seeFIGS.5A-5D).

In another example, the non-uniform thickness can be defined on the back sides304,404,504by various or random shapes, lines, curves, etc. of various sizes. In one aspect, the non-uniform thickness can be defined on the back sides304,404,504in a symmetrical relationship with the outer or perimeter shape of the respective reflective face sheets310,410,510, which can provide a symmetric or uniform distribution of features defining the non-uniform thickness about the reflective face sheets310,410,510. This can locate stiffness enhancing features (e.g., thicker portions, such as the ribs discussed below, or any other similar features) symmetrically or uniformly about the reflective face sheets310,410,510.

In still another example, the non-uniform thickness can be defined on the respective back sides304,404,504in an asymmetrical relationship with the outer or perimeter shape of the reflective face sheets310,410,510, which can provide an asymmetric or non-uniform distribution of features defining the non-uniform thickness about the reflective face sheets310,410,510. This can locate stiffness enhancing features (e.g., thicker portions) asymmetrically or non-uniformly about the reflective face sheets310,410,510.

A uniform or symmetric distribution of features may be utilized when the reflective face sheets310,410,510will be primarily oriented facing in a vertical direction (e.g., up or down relative to a gravity direction) or when the reflective face sheets310,410,510will be subjected to variable and dynamic loading, orientations, etc. A non-uniform or asymmetric distribution of features defining the non-uniform thickness about the reflective face sheets310,410,510can be utilized when the reflective face sheets310,410,510will be primarily oriented facing in a horizontal direction (e.g., perpendicular relative to a gravity direction). In this case, a higher concentration of stiffness enhancing features (e.g., thicker portions) can be located in areas of greatest need, such as at a bottom end of the reflective face sheets310,410,510when oriented facing a horizontal direction to more effectively counteract the effects of gravity sag.

In one aspect, the non-uniform thickness of the reflective face sheets310,410,510can be configured and defined on the respective back sides304,404,504to correspond to one or more electromagnets of a deformable mirror. For example, a size, location, etc. of a stiffness enhancing feature (e.g., thicker portions) of the reflective face sheets310,410,510can be configured to facilitate responsiveness to actuation (e.g., can be configured to increase actuator stroke). The reflective face sheets310,410,510(e.g., non-uniform shaping) can be manufactured by any suitable process, such as silicon etching and others.

The thickness of the reflective face sheets310,410,510can vary in any suitable manner and in any location across the reflective face sheets310,410,510, such as an abrupt or step change in thickness, a gradual transition in thickness, or a combination of these. In the example illustrated inFIGS.5A-5D, the non-uniform thickness is defined by several abrupt step changes in thickness of the back side304of the reflective face sheet310to form various ribs313arranged along the back side304in the honeycomb pattern shown. InFIGS.5A-5D, the ribs313are an example of stiffness enhancing features. In this case, as shown inFIG.5D, which illustrates a detailed cross-section of one of the ribs313of the reflective face sheet310, the illustrated rib313has a first thickness361at a first location371and a second thickness363at a second location373. The first and second thicknesses361,363are different from one another. The first and second locations371,373lie on a planar surface portion312on the back side304of the reflective face sheet310substantially perpendicular to the reflective surface311on the front side303.

The planar surface portion312can at least partially define the rib313or protrusion, which can comprise a rectangular or other cross-section. In one aspect, the reflective face sheet310can have a base portion314or layer having a baseline thickness370, and the ribs313can extend beyond the base portion314and the baseline thickness370. The ribs313can be integrally formed with the material or structure of the base portion314as a single component or the ribs313can be a separate or independent component, which may or may not be coupled or affixed to the base portion314.

In one aspect, a similar type of rib or other protrusion can form a relatively thick rim315as a stiffener about a periphery or edge of the reflective face sheet310to maintain flexibility of the reflective face sheet310while preventing unwanted distortion, such as due to an interface with an adhesive or sealant coupling the reflective face sheet310to a compliant ferrous backing. Thus, non-uniform thickness features can also reduce or minimize the sensitivity of the reflective face sheet310to the attachment interface to a compliant ferrous backing.

In the examples illustrated inFIGS.6A-7D, the non-uniform thickness is formed by a gradual change in thickness or a gradual transition of thickness between two points. With regard to the example illustrated inFIGS.6A-6D, as particularly shown inFIG.6D, the gradual change in thickness is defined by a planar surface, but this is not to be limiting in any way as a non-planar surface is also contemplated.

In the example shown, the reflective face sheet410can comprise a plurality of ribs413as examples of stiffness enhancing features. Each of the ribs413can have a first thickness461at a first location471, a second thickness462at a second location472, and a third thickness463at a third location473. The first, second, and third thicknesses461,462,463are different from one another. The first, second, and third locations471,472,473lie on a planar surface portion412on the back side404of the reflective face sheet410non-perpendicular to the reflective surface411on the front side403.

The planar surface portion412can at least partially define the rib413or protrusion having a generally trapezoidal cross-section. In one aspect, the reflective face sheet410can have a base portion414or layer having a baseline thickness470, and the ribs413can extend beyond the base portion414and the baseline thickness470. The ribs413can be integrally formed with the material or structure of the base portion414as a single component or the ribs413can be a separate component, which may or may not be coupled or affixed to the base portion414.

In one aspect, a similar type of rib or other protrusion can form a relatively thick rim415as a stiffener about a periphery or edge of the reflective face sheet410to maintain flexibility of the reflective face sheet410while preventing unwanted distortion, such as due to an interface with an adhesive or sealant coupling the reflective face sheet410to a compliant ferrous backing. Thus, non-uniform thickness features can also reduce or minimize the sensitivity of the reflective face sheet410to the attachment interface to a compliant ferrous backing.

With regard to the example illustrated inFIGS.7A-7D, as particularly shown inFIG.7D, the gradual change in thickness is defined by a curved surface. The reflective face sheet510can comprise a plurality of ribs513as examples of stiffness enhancing features. Each of the ribs513can have a first thickness561at a first location571, a second thickness562at a second location572, and a third thickness563at a third location573. The first, second, and third thicknesses561,562,563are different from one another. The first, second, and third locations571,572,573lie on a curved surface portion512on the back side504of the reflective face sheet510.

The curved surface portion512can at least partially define the rib513or protrusion. In one aspect, the reflective face sheet510can have base portion514or layer having a baseline thickness570, and the ribs513can extend beyond the base portion514and the baseline thickness570. The ribs513can be integrally formed with the material or structure of the base portion514as a single component or the ribs513can be a separate component, which may or may not be coupled or affixed to the base portion514.

In one aspect, a similar type of rib or other protrusion can form a relatively thick rim515as a stiffener about a periphery or edge of the reflective face sheet510to maintain flexibility of the reflective face sheet510while preventing unwanted distortion, such as due to an interface with an adhesive or sealant coupling the reflective face sheet510to a compliant ferrous backing. Thus, non-uniform thickness features can also reduce or minimize the sensitivity of the reflective face sheet510to the attachment interface to a compliant ferrous backing.

The compliant ferrous backing (see the compliant ferrous backing120ofFIGS.1-4) can be adhered to the reflective face sheet, such as reflective face sheets110,310,410,510, regardless of the configuration of the reflective face sheet as it is designed and configured to conform to the reflective face sheet,FIGS.8A-8Cshow examples of an interface between the reflective face sheet and the compliant ferrous backing. InFIG.8A, an interface between a uniform reflective face sheet610and a compliant ferrous backing620is shown. Similar as was described above, the compliant ferrous backing620is adhered to the back side604of the reflective face sheet610. The compliant ferrous backing620can be adhered to the reflective face sheet610by way of an adhesive binder, such as an epoxy or other material used to form the compliant ferrous backing, or by way of a separate adhesive.

FIG.8Bshows an interface between a non-uniform reflective face sheet710and a compliant ferrous backing720. Similar as was described above, the compliant ferrous backing720is adhered to the back side704of the reflective face sheet710. The compliant ferrous backing720can be adhered to the reflective face sheet710by way of an adhesive binder, such as an epoxy or other material used to form the compliant ferrous backing720, or by way of a separate adhesive.

In this example, the non-uniform reflective face sheet710comprises a plurality of relatively thicker portions and areas784as compared to a plurality of thinner portions and areas782formed in a back side704of the reflective face sheet710. The non-uniform reflective face sheet710can take on a variety of shapes and thickness similar to the reflective face sheets310,410,510described above. The compliant ferrous backing720is molded or formed onto the back side703of the reflective face sheet710to conform to the topography of the back side704of the reflective face sheet710. Accordingly, the compliant ferrous backing720comprises relatively thicker portions and areas794that conform into the relatively thinner portions and areas782of the reflective face sheet710, as well as relatively thinner portions and areas792that conform around the relatively thicker portions and areas784of the reflective face sheet710.FIGS.8A and8Bfurther illustrate compliant ferrous backings having uniformly distributed ferrous particles throughout.

In one example shown inFIG.8C, a uniform reflective face sheet810(or non-uniform reflective face sheet) can interface with a compliant ferrous backing820where the ferrous particles are distributed non-uniformly throughout the compliant ferrous backing820. In this example, the compliant ferrous backing820has relatively high ferrous particle concentration portions896having a relatively higher concentration of the ferrous particles and relatively low or no ferrous particle concentration portions898having a relatively lower concentration of the ferrous particles, or none at all. Indeed, the high ferrous particle concentration portions896can include portions of the compliant ferrous backing820in which ferrous particles are distributed, and the low ferrous particle concentration portions898can include portions of the compliant ferrous backing820in which no ferrous particles are distributed. In other examples, ferrous particles can be distributed throughout the compliant ferrous backing820, but are distributed in a higher concentration in the relatively high ferrous particle concentration portions896as compared to the relatively low ferrous particle concentration portions898.

In one example, the compliant ferrous backing820can be formed by first curing the relatively high ferrous particle concentration portions896in a desired pattern. Then, the relatively low or no ferrous particle concentration portions898are cured together with the relatively high ferrous particle concentration portions896to form the compliant ferrous backing820. Other manufacturing methods can also be used.

Using the uniform reflective face sheet810with the above describe compliant ferrous backing820having ferrous particles distributed non-uniformly throughout the compliant ferrous backing provides several advantages. For example, the production of the reflective face sheet810can be kept relatively simple and cheap as compared to producing a non-uniform reflective face sheet. At the same time, the non-uniform distribution of the ferrous particles throughout the compliant ferrous backing820can provide similar advantages as when the non-uniform reflective face sheet is used. For example, the positioning, distribution, and configuration of the relatively high ferrous particle concentration portions896can facilitate accurate control the actuator strokes and can increase in the maximum size of the actuator strokes.

The high and low ferrous particle concentration portions896,898can form a pattern in the compliant ferrous backing820. The pattern may be any suitable pattern and can include any shape or combination of shapes, lines, curves, etc. of any suitable size or configuration. For example, the pattern can comprises an array or matrix of polygon shapes (e.g., hexagons in a “honeycomb” pattern).

In another example, the pattern can be defined by various or random shapes, lines, curves, etc. of various sizes. In one aspect, the pattern can have a symmetrical relationship with the outer or perimeter shape of the compliant ferrous backing820, which can provide a symmetric or uniform distribution of the high and low ferrous particle concentration portions896,898defining the pattern in the compliant ferrous backing820.

On the other hand, the pattern can have an asymmetrical relationship with the outer or perimeter shape of the compliant ferrous backing820which can provide an asymmetric or non-uniform distribution of the high and low ferrous particle concentration portions896,898defining the pattern in the compliant ferrous backing820.

In one aspect, the pattern of the high and low ferrous particle concentration portions can be defined and configured to correspond to one or more electromagnets of a deformable mirror. For example, a size, location, etc. of a high ferrous particle concentration portion896can be configured to facilitate responsiveness to actuation of one or more electromagnets (e.g., increase actuator stroke). The transition from a high ferrous particle concentration portion896to a low ferrous particle concentration portion898of the compliant ferrous backing820can be formed in any suitable manner. For example, the transition from a high ferrous particle concentration portion896to a low ferrous particle concentration portion898can comprise an abrupt or step change in ferrous particle distribution, a gradual change in distribution, or a combination of these.

The compliant ferrous backing820can be adhered to the back side804of the reflective face sheet810. The compliant ferrous backing820can be adhered to the reflective face sheet810by way of an adhesive binder, such as an epoxy or other material used to form the compliant ferrous backing820, or by way of a separate adhesive.

The above described examples of a deformable mirror system and deformable mirror provide several advantages and benefits. For example, significant stroke improvement can be achieved as well as stroke control. In one example, where a prior art system (e.g. a system utilizing a Ferro fluid or piezoelectric direct actuators) having a reflective face sheet with a given configuration can achieve peak strokes from around 6 μm-10 μm, the deformable mirror system described herein using a similar reflective face sheet can achieve a peak stroke of up to 17 μm due to the actuation of the compliant ferrous backing and the interface between the compliant ferrous backing and the reflective face sheet.

Other advantages of the above described system and mirror include the elimination of the need for liquid containment which can pose risks of leaks, allowing for the above described system and mirror to provide a robust design for use in a variety of applications. Additionally, the above described system can be formed with relatively few parts, including interchangeable parts allowing for faster and cheaper manufacturing and increasing reparability. The compliant ferrous backing material used in the above described system and mirror can also be easily tuned to a specific design need.

In operation, the deformable mirror system and deformable mirror can be deformed based on the actuation of the electromagnets which locally attract the compliant ferrous backing to deform the deformable mirror. The deformation of the deformable mirror can be controlled to correct alignment in an optical system, to correct or optimize dynamic wave front error and aberrations, or the like.

In some examples, the electromagnets can be controlled to vary the strength of the magnetic field produced by the electromagnets. In one example, a deformable mirror system can be provided where the electromagnets can actuate the deformable mirror with a 10 μm stroke. That is, the electromagnets can attract the compliant ferrous backing to locally pull and deform the deformable mirror a distance of 10 μm. When the system is activated the electromagnets can be actuated to create a magnetic field sufficiently strong to poke the deformable mirror at a distance of 5 μm, which can be considered a zero position. If a portion of the deformable mirror needs to be raised, the electromagnet can decrease the strength of the electromagnetic field to allow the portion of the deformable mirror to rise, such as up to 5 μm in this example. If a portion of the deformable mirror needs to lowered, the electromagnet can increase the strength of the electromagnetic field to further deform and lower the portion of the deformable mirror up to 5 μm in this example.

Various modifications can be made to the above described systems and deformable mirrors in accordance with the present disclosure. For example, instead of the mirror assembly comprising a compliant ferrous backing, a thin ferrous or magnetic metallic backing could be used within the mirror assembly of a deformable mirror, such as the various mirror assemblies discussed above and shown in the drawings. As shown inFIG.9, the mirror assembly can comprise a thin ferrous metallic backing920positioned adjacent a back side904of the reflective face sheet910. The thin ferrous metallic backing920can be adhered or otherwise attached or positioned adjacent to (and not necessarily joined together, but could be) a reflective face sheet910on a back side904of the reflective face sheet910. The thin ferrous metallic backing920can be formed from a magnetically attracted material, such as iron, steel, cobalt, or nickel. The thin metallic backing920can be operable similar to the compliant ferrous backing described above in that it can facilitate select, precision deformations within the mirror assembly, and specifically deformation of the reflective face sheet910, via actuation of one or more electromagnets (as described above) that function to induce a magnetic field that acts upon the thin ferrous metallic backing. The thin ferrous metallic backing920can be sized and configured or formed to be sufficiently thin so as to be able to flex or deform upon actuation of the electromagnets and with the reflective face sheet910, as well as to conform to the profile of the back side904of the reflective face sheet910, whether uniform or non-uniform.

Reference was made to the examples illustrated in the drawings and specific language was used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the technology is thereby intended. Alterations and further modifications of the features illustrated herein and additional applications of the examples as illustrated herein are to be considered within the scope of the description.

Although the disclosure may not expressly disclose that some embodiments or features described herein may be combined with other embodiments or features described herein, this disclosure should be read to describe any such combinations that would be practicable by one of ordinary skill in the art. The use of “or” in this disclosure should be understood to mean non-exclusive or, i.e., “and/or,” unless otherwise indicated herein.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more examples. In the preceding description, numerous specific details were provided; such as examples of various configurations to provide a thorough understanding of examples of the described technology. It will be recognized, however, that the technology may be practiced without one or more of the specific details, or with other methods, components, devices, etc. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring aspects of the technology.

Although the subject matter has been described in language specific to structural features and/or operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features and operations described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. Numerous modifications and alternative arrangements may be devised without departing from the spirit and scope of the described technology.