Patent Publication Number: US-11656454-B2

Title: Steerable optical assemblies

Description:
BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings illustrate implementations of the concepts conveyed in the present document. Features of the illustrated implementations can be more readily understood by reference to the following description taken in conjunction with the accompanying drawings. Like reference numbers in the various drawings are used wherever feasible to indicate like elements. Further, the left-most numeral of each reference number conveys the FIG. and associated discussion where the reference number is first introduced. 
    
    
     
         FIG.  1    is a side view of an example device implementation in accordance with the present concepts. 
         FIG.  2 A  is a top view of an example optical substrate implementation in accordance with the present concepts. 
         FIG.  2 B  is a side view of an example optical substrate implementation in accordance with the present concepts. 
         FIGS.  3 A- 6    are side views of example steerable configuration-enhancing optical assemblies in accordance with the present concepts. 
     
    
    
     DESCRIPTION 
     The present concepts relate to optical assemblies, such as optical micro electromechanical systems (MEMS). The present concepts can physically secure an optical substrate to a base substrate so that when the base substrate is steered, the motion is transferred to the optical substrate. The present concepts can ensure this motion transfer while otherwise isolating the optical substrate from the base substrate so that changes to the base substrate have less effect on the optical substrate. Further, these implementations can reduce distortions in the optical substrate for enhancing optical device performance. These and other aspects are described below. 
       FIG.  1    shows an example device  100  that can include a steerable configuration-enhancing optical assembly  101 , which may be viewed as an optical MEMS device. The steerable configuration-enhancing optical assembly can include an optical substrate  102  that can be physically secured to a base substrate  104  by an adhesive complex  108 . An orientation of the base substrate  104  can be controlled (e.g., steered) by a steering mechanism  110 . Thus, the optical substrate  102  can be steered by controlling the steering mechanism  110 . Various types of steering mechanisms can be employed, such as electrical/magnetic coils and magnetic field generators, among others. 
     In the illustrated example of  FIG.  1   , the optical substrate  104  is manifest as a mirror  112 . Other optical substrates, can includes lenses, prisms, etc. The mirror may be formed from a silicon or glass material, among others, with reflective layers positioned thereon. In this example, the mirror  112  can redirect light (represented by dashed arrow) from a source  114  to a target  116 , such as relating to a display  117 , among others. For example, at Instance one, the mirror  112  can redirect light from source  114  to target  116 ( 1 ). In Instance two, steering mechanism  110  has adjusted the orientation of the base substrate  104  and hence the optical substrate  102  as indicated at  118 . Now the mirror  112  can redirect the light from the source to target  116 ( 2 ). 
     Operation of the steering mechanism  110  can generate heat or thermal energy that can heat and/or distort the base substrate  104 . The adhesive complex  108  can reduce the extent to which the thermal energy is transferred to and/or otherwise negatively affects the optical substrate  102 . Toward this end, the adhesive complex  108  can physically secure the base substrate  104  to the optical substrate  102  with less adhesive than traditional techniques. Further, the adhesive can be applied as multiple relatively small, discrete, units of adhesive. Alternatively or additionally, the adhesive complex can generally be positioned toward a center of the optical substrate so that a majority of the optical substrate is insulated by air, which can flow between the base substrate and the optical substrate. These aspects are discussed in more detail below relative to  FIGS.  2 A- 6   . 
     Stated another way, the optical substrate  102  can be defined by design parameters to have an intended or design configuration that allows the optical substrate to act upon light as intended. For instance, the design configuration of mirror  112  can be planar. However, in practice, optical substrates that are actually produced may deviate from the design configuration. In some of the present implementations, individual adhesives can be selected for bonding to individual portions of the optical assembly to enhance performance of the optical substrate. One such example is discussed below starting at  FIG.  3 A . 
       FIGS.  2 A- 3 C  collectively show how a steerable configuration-enhancing optical assembly  101 A can improve the optical substrate by decreasing the deviation (e.g., bringing the optical substrate  102 A closer to the design configuration).  FIGS.  2 A and  2 B  show an example configuration of mirror  112 A.  FIGS.  3 A- 3 C  show an example of how the steerable configuration-enhancing optical assembly  101 A can improve the mirror configuration. 
       FIG.  2 A  shows an example contour map  200  of mirror  112 A.  FIG.  2 B  shows a sectional view of mirror  112 A as indicated in  FIG.  2 A . The view of  FIG.  2 B  is similar to the view of  FIG.  1   . The mirror  112 A has a design or intended configuration  202 . In this case, the design configuration  202  is planar (e.g., the mirror  112 A is designed to be planar relative to the xy-reference plane). However, the mirror  112 A has deviations  204  from the planar configuration. In this example, deviations above the plane are represented at  204 A (dashed lines on  FIG.  2 A ) and deviations below the plane are represented at  204 B (dotted lines on  FIG.  2 A ).  FIGS.  3 A- 3 C  collectively show an example of how the present concepts can both secure the optical substrate  102 A to the base substrate  104 A and decrease the deviations of the optical substrate  102 A. 
       FIG.  3 A  shows the optical substrate  102 A ready to be positioned relative to the base substrate  104 A by adhesive complex  108 A. In this case, the adhesive complex includes a first adhesive  302  and a second adhesive  304 . At this point, the first and second adhesives are in a relatively more flowable state (e.g., relatively flowable application state). 
     The optical substrate  102 A includes upper and lower surfaces  306  and  308 . In the designed configuration, the upper and lower surfaces  306  and  308  would be equidistance from the plane along the length of the optical substrate (e.g., both surfaces would be planar and the plane of the design configuration would lie equidistance from each surface). Such a situation is shown at height H 1A  ( FIG.  3 B ) to lower surface  308  where the design configuration plane  202  lies midway between the upper and lower surfaces. 
       FIG.  3 B  shows the optical substrate  102 A lowered toward the base substrate  104 A until contacting the first adhesive  302  and the second adhesive  304 . The first and second adhesives remain in the relatively flowable state. Note that the first adhesive  302  is contacting a first portion  310  of the optical substrate  102 A that is distorted below the design configuration plane  202  as represented by height H 2A  which is less than height H 1A . The second adhesive  304  is contacting a second portion  312  of the optical substrate that is distorted above the design configuration plane  202  as indicated by height H 3A  which is greater than height H 1A . 
       FIG.  3 C  shows the optical substrate  102 A secured to the base substrate  104 A by the adhesive complex  108 A and deviation of the optical substrate has decreased relative to  FIG.  3 B . For instance, deviation  204 A of second portion  312  is less in  FIG.  3 C  than in  FIG.  3 B . In this example, the securing can be accomplished by transitioning (e.g., curing) the first adhesive  302  and the second adhesive  304  from the relatively pliant flowable state of  FIG.  3 B  to a less pliant (e.g., relatively less flowable) adhesive state. 
     One effect of this state transitioning of adhesives  302  and  304  is that the adhesives tend to contract (e.g., an individual adhesive tends to have a smaller volume in the less pliant adhesive state than in the more pliant flowable state). As the adhesives contract they impart forces that can bend the optical substrate (e.g., distortive forces). However, the percent of volume contraction associated with the adhesive phase change in not uniform for all types of adhesives. In fact, some adhesives contract to a much greater extent than other types. The present concepts can leverage this property and match adhesive type to the contour map ( 200 ,  FIG.  2 A ) of the optical substrate. 
     In this implementation, the first portion  310  has a deviation  204 B below the design configuration  202  (e.g., toward the base substrate  104 A) and the second portion  312  is above the design configuration  202  (e.g., away the base substrate  104 A). Accordingly, the first adhesive  302  can be selected to have a relatively low contraction coefficient to reduce the extent to which the first portion is pulled farther from the design configuration  202 . In contrast, the second adhesive  304  can be selected that has a relatively large coefficient of contraction so that it can pull the second portion toward the design configuration. Stated another way, transition of the second adhesive  304  can impart a relatively greater distortive force per unit area between the second portion  312  of the optical substrate  102 A and the base substrate  104 A. This force can pull the second portion  312  toward the base substrate  104 A. This is evidenced in that height H 3B  in  FIG.  3 C  between the base substrate  104 A and the second portion  312  is less than height H 3A  in  FIG.  3 B . 
     Transition of the first adhesive  302  can impart relatively less distortive force per unit area between the first portion  310  of the optical substrate  102 A and the base substrate  104 A. This is evidenced in that height H 2B  in  FIG.  3 C  between the base substrate  104 A and the first portion  310  is only slightly less (e.g., approximately equal) to height H 2A  in  FIG.  3 B . In this implementation, other portions of the optical assembly represented by height H 1A  and H 1B  can remain approximately equal during the adhesion process. As a result, deviation of second portion  312  is decreased in  FIG.  3 C  compared to  FIG.  3 B  while deviation of first portion  310  remains generally constant. Thus, the overall configuration of the optical substrate  102 A is closer to the design configuration when the adhesives  302  and  304  of the adhesive complex  108 A have secured the optical substrate  102 A to the base substrate  104 A. 
     Further, the improved configuration of  FIG.  3 C  can be achieved with the adhesive complex  108 A bonded to a relatively small percentage of the optical substrate  102 A. For instance, improved configurations can be achieved when the adhesive complex is bonded to less than 10% of the total area of the optical substrate when measured along the xy-reference plane. Bonding a relatively small area of the optical substrate to the base substrate can reduce degradation of the optical substrate due to factors associated with the base substrate, such as heat generated by steering the steerable configuration-enhancing optical assembly. 
       FIGS.  4 A- 4 E  collectively show another example implementation of a steerable configuration-enhancing optical assembly  101 B. This implementation is similar to steerable configuration-enhancing optical assembly  101 A and includes additional features. 
       FIG.  4 A  shows a location  402  of the adhesive complex  108 B (not yet added). Arrows  404  correlate specific portions  406  of the base substrate  104 B to specific portions  310 B and  312 B of the optical substrate  102 B. (This correlation can occur in  3 D, but is represented in  2 D (along the yz-reference plane) for ease of illustration). For instance, portion  406 ( 1 ) is aligned with first portion  310 B and portion  406 ( 2 ) is aligned with second portion  312 B. Note that first portion  310 B has a negative deviation  204 B and second portion  312 B has a positive deviation  204 C. 
     As explained above relative to  FIGS.  3 A- 3 C  the present implementations can advantageously select individual adhesives for each of these deviations based upon the properties of the adhesive and the deviation that the adhesive will contact. However, often adhesives that could reduce some of the deviations may have other characteristics or properties that are unsatisfactory for this application. For instance, some of these adhesives may be so flowable that they tend to flow beyond the portions of the base substrate  104 B to which they are applied. Adhesive flow can result in the adhesive contacting and bonding to unintended portions of the optical substrate  102 B. This unintended bonding could result in increasing deviations of the optical substrate rather than decreasing the deviations. The unintended bonding can also increase the percentage of the optical substrate that is thermally bonded by adhesive to the base substrate and thereby undesirably increase thermal transfer from the base substrate to the optical substrate.  FIG.  4 B  introduces a solution to this problem. 
       FIG.  4 B  shows retainment features  410 ( 1 ) and  410 ( 2 ) added to base substrate  104 B at portions  406 ( 1 ) and  406 ( 2 ), respectively. The retainment features can be formed in various ways, such as by removing material from the base substrate and/or by selectively adding material to the top surface of the base substrate (e.g., patterning the retainment features). The location of the retainment features  410  on the base substrate can be based upon the contours (e.g., the locations of deviations  204 C) of the optical substrate  102 B. 
       FIG.  4 C  shows adhesive  302 B positioned in retainment feature  410 ( 1 ) of portion  406 ( 1 ) and adhesive  304 B positioned in retainment feature  410 ( 2 ) of portion  406 ( 2 ). The adhesives can be applied in their relatively flowable state. The retainment features  410  can function to retain the adhesive relative to the intended portion and reduce/limit and/or prevent migration of adhesive in the x and/or y reference directions. This is especially important because as explained above relative to  FIGS.  3 A- 3 C , the present implementations can select adhesives with specific properties at specific locations on the base substrate  104 B that underly specific portions of the optical substrate. The selected adhesives can have contraction coefficients selected to impart more or less forces on the individual portions of the optical substrate. The present implementations can also bond a smaller percentage of the optical substrate to the base substrate with adhesive than traditional techniques. Further, the present techniques can utilize multiple small discrete units of adhesive at point specific locations and the retainment features facilitate these approaches. 
       FIG.  4 D  shows the optical substrate  102 B moved toward the base substrate  104 B until the adhesives  302 B and  304 B are contacting the optical substrate. At this point, the adhesives  302 B and  304 B remain in their relatively flowable state. 
       FIG.  4 E  shows the steerable configuration-enhancing optical assembly  101 B after state transition (e.g., curing or transitioning to the cured state) of the adhesives  302 B and  304 B. At this point, the cured adhesives contracted and are applying forces to the base substrate  104 B (upward) and the optical substrate  102 B (downward). The forces are more extensive relative to adhesive  304 B that  302 B. Given that the base substrate is relatively stiffer than the optical substrate, little or no deflection of the base substrate occurs. However, adhesive  304 B causes a relatively large amount of downward deflection of the optical substrate at the second portion  312 B such that deviation  204 C is reduced in  FIG.  4 E  relative to  FIG.  4 D . Thus, strategically selecting adhesives based upon which portions of the optical substrate they bond to and the deviation of those portions, the present implementations can produce a finished steerable configuration-enhancing optical assembly where the integrated (e.g., secured) optical substrate has less deviation than the optical substrate had before integration. 
       FIGS.  5 A- 5 B  collectively show another steerable configuration-enhancing optical assembly  101 C. In this case, the adhesive complex  108 C can be used to affect the optical substrate toward the design configuration  202 C. In this example, assume that the design configuration  202 C specifies a curved optical substrate  102 C, but that for various reasons, such as difficulty in manufacturing, optical substrate conforming to the design configuration are not available. 
       FIG.  5 A  shows the optical substrate  102 C in contact with the adhesives  302 C and  304 C of the adhesive complex  108 C. The adhesives are in the relatively flowable state at this point. In this case, the adhesives include adhesive  304 C which experiences relatively little shrinkage during curing. Adhesives  302 C( 1 ) and  302 C( 2 ) are positioned on each side of adhesive  304 C and are selected to experience relatively high amounts of shrinkage during curing. 
       FIG.  5 B  shows the resultant steerable configuration-enhancing optical assembly  101 C after curing the adhesives  302 C and  304 C. As indicated adhesives  302 C( 1 ) and  302 C( 2 ) have experienced a high rate of shrinkage as represented by a greater change in height (↑ΔH) compared to adhesive  304 C (↓ΔH). This shrinkage pulls down on the ends of the optical assembly  101 C while the middle stays relatively stationary. The forces of this shrinkage can bend the optical substrate  102 C toward the design configuration  202 C. Thus, the present concepts can be used to achieve a desired optical substrate configuration that is otherwise difficult to achieve. This desired optical substrate can be achieved by selecting adhesives having different shrinkage ratios based upon the overlying deviation of the optical substrate. 
     In the examples described above, the optical substrates  102  have been generally symmetrical and the adhesive complex  108  has been positioned in the geometric center of the optical substrates.  FIG.  6    shows an alternative scenario. 
       FIG.  6    shows a steerable configuration-enhancing optical assembly  101 D. In this case, the optical substrate  102 D is manifest as a prism  602 . In this example, the adhesive complex  108 D includes two identical adhesives  302 D( 1 ) and  302 D( 2 ). The optical adhesive are positioned in features  410 D( 1 ) and  410 D( 2 ) which serve to reduce migration and spreading of the adhesive. The use of multiple small adhesive areas can effectively bond the optical substrate  102 D to the base substrate  104 D with less adhesive area than a single large amount of adhesive. The small adhesive area can keep the optical assembly more thermally isolated from the base substrate than a single large adhesive. Further, in this case the adhesive complex is positioned approximately under a center of gravity of the prism  602  to decrease any dynamic load experienced by the prism when the optical substrate is steered by the steering mechanism. 
     The present implementations can utilize multiple small discrete units of adhesives to bond the optical substrate to the base substrate. Further, individual adhesives can be selected to have properties that facilitate compliance of the optical substrate to its design configuration. 
     Various examples are described above. Additional examples are described below. One example includes a device comprising a steering mechanism, a base substrate positioned relative to the steering mechanism, an optical substrate positioned over the base substrate, and an adhesive complex securing the optical substrate relative to the base substrate, the adhesive complex comprising a first adhesive securing a first portion of the base substrate and the optical substrate and that imparts a relatively greater distortive force per unit area between the optical substrate and the base substrate and a second adhesive securing a second portion of the base substrate and the optical substrate and that imparts a relatively less distortive force per unit area between the optical substrate and the base substrate. 
     Another example can include any of the above and/or below examples where the steering mechanism comprises a magnetic coil and a magnetic field generator. 
     Another example can include any of the above and/or below examples where the optical substrate comprises a mirror, a lens, or a prism. 
     Another example can include any of the above and/or below examples where the optical substrate is designed to extend along a plane. 
     Another example can include any of the above and/or below examples where the optical substrate includes portions that deviate from the plane away from the base substrate and other portions that deviate away from the plane toward the base substrate. 
     Another example can include any of the above and/or below examples where the first adhesive is secured to the portions and the second adhesive is secured to the other portions. 
     Another example can include any of the above and/or below examples where the first adhesive experiences a greater change in volume when transitioning from a more flowable application state to a more rigid securing state. 
     Another example can include any of the above and/or below examples where the base substrate includes a retainment feature that limits migration of the second adhesive in the more flowable application state. 
     Another example can include any of the above and/or below examples where the base substrate includes other retainment features that limit migration of the first adhesive in the more flowable application state. 
     Another example can include any of the above and/or below examples where the retainment feature is formed on a first surface of the base substrate that faces the optical substrate. 
     Another example can include any of the above and/or below examples where the retainment feature is formed into the base substrate through the first surface. 
     Another example can include any of the above and/or below examples where location of the retainment feature is based upon contours of the optical substrate away from the plane. 
     Another example includes a device comprising a steering mechanism, a base substrate positioned relative to the steering mechanism, an optical substrate positioned over the base substrate, and an adhesive complex securing the optical substrate relative to the base substrate with multiple different types of adhesives. 
     Another example can include any of the above and/or below examples where the adhesive complex comprises less than 10% of a total area of the optical substrate. 
     Another example can include any of the above and/or below examples where the multiple different types of adhesives have different shrinkage ratios between an application state and a cured state. 
     Another example can include any of the above and/or below examples where the application state is a relatively more flowable state and the cured state is a relatively less flowable state. 
     Another example can include any of the above and/or below examples where adhesive of the adhesive complex is aligned with deviations of the optical substrate from a planar configuration. 
     Another example can include any of the above and/or below examples further comprising retainment features on the base substrate that align with the deviations. 
     Another example can include any of the above and/or below examples where the retainment features are formed into the base substrate. 
     Another example includes a device comprising a display and a steerable configuration-enhancing optical assembly comprising a base substrate secured to an optical substrate by multiple discrete adhesives. 
     CONCLUSION 
     Although techniques, methods, devices, systems, etc., pertaining to steerable configuration-enhancing optical assemblies are described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claimed methods, devices, systems, etc.