Patent Publication Number: US-2023164467-A1

Title: Heater with mounting pads for mechanical, thermal, and opto-mechanical functionality

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This Patent Application claims priority to U.S. Provisional Patent Application No. 63/264,523, filed on Nov. 24, 2021, and entitled “HEATER WITH MOUNTING PADS FOR MECHANICAL, THERMAL, AND OPTO-MECHANICAL FUNCTIONALITY.” The disclosure of the prior Application is considered part of and is incorporated by reference into this Patent Application. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to a heating element for an optical device and, more particularly, to a heating element with a mounting pad arranged in an opening in the heating element. 
     BACKGROUND 
     An optical device, such as a wavelength selective switch (WSS) or a light detection and ranging (LIDAR) device, may need to satisfy thermal requirements, mechanical/dynamic requirements, or opto-mechanical requirements, within a limited size and/or cost constraint. For example, in operation, an optical device may need to maintain a relatively constant temperature within an inner volume of the optical device. Further, an inner box of the optical device may need to be mechanically coupled to an outer box, with mechanical damping in between. Additionally, the inner box may need to be thermally isolated from the outer box. Finally, the size or volume of the optical device may need to be limited, meaning that the size or volume of the optical device may need to be minimized as much as possible. 
     SUMMARY 
     According to some implementations, an optical device may include an outer box; an inner box within the outer box; a heating element on a surface of the inner box, wherein the heating element includes one or more openings; and one or more mounting pads, wherein a mounting pad of the one or more mounting pads is arranged in an opening of the one or more openings and mechanically couples the inner box to the outer box through the opening. 
     According to some implementations, an optical package may include an inner box; a heating element including an opening, wherein the heating element is on a surface of the inner box; and a mounting pad mechanically coupling the inner box to an outer box, wherein the mounting pad is arranged such that the mounting pad passes through the opening in the heating element. 
     According to some implementations, a device may include a heating element on a surface of an inner box, wherein the heating element includes a plurality of openings; and a plurality of mounting pads coupling the inner box to an outer box, wherein a mounting pad of the plurality of mounting pads mechanically couples the inner box to the outer box through an opening of the plurality of openings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 - 5    are diagrams associated with an optical device that includes a heating element with one or more openings in which one or more mounting pads are arranged, in accordance with various aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description of example implementations refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. 
     In general, an optical device may include an inner volume, an inner box, and an outer box. As used herein, the term “inner volume” refers to a volume or space of an optical device in which optical components (e.g., optics) are located. As used herein, the term “inner box” refers to a structure that defines the inner volume (e.g., a structure within which the inner volume is contained). For example, the inner box may include a platform and one or more sidewalls (e.g., arranged at one or more edges of the platform). Here, the platform and the one or more sidewalls define a volume within which the optical components of the optical device can be mounted. The inner box may also provide an isothermal enclosure for the optical components of the optical device. As used herein, the term “outer box” refers to a structure within which the inner box is contained. The outer box may be designed to provide a hermetic seal and thermal insulation for the optical device. 
     As noted above, an optical device, such as a WSS or a LIDAR device, may need to satisfy thermal requirements, mechanical/dynamic requirements, or opto-mechanical requirements, within a limited size and/or cost constraint. In some optical devices, to provide mechanical coupling and isolation at the same time, the optical device may include one or more mounting pads (also referred to as damping pads) between the inner box and the outer box (e.g., such that the inner box is mechanically coupled to the outer box via the mounting pads). Further, to maintain a relatively constant temperature within the inner volume, the inner box may include one or more heating elements (i.e., a film heater) on one or more surfaces of the inner box. The one or more heating elements may enable a relatively constant temperature to be maintained in the inner volume. However, the need for the inner box to be mechanically coupled to, and thermally isolated from, the outer box is problematic due to the one or more heating elements because mounting the mounting pads directly on the heating element results in unreliable mechanical coupling and decreased thermal isolation. 
     Some implementations described herein provide an optical device comprising a heating element with a mounting pad arranged in an opening in the heating element. In some implementations, the design of the heating element, the mounting pad, and/or the opening enables thermal, dynamic, and/or opto-mechanical requirements of the optical device to be satisfied, while also enabling a physical size limitation and/or a material cost limitation to be satisfied. In some implementations, the opening improves reliability of the mechanical coupling between the inner box and the outer box (e.g., since mounting the mounting pads directly on the heating element results in unreliable mechanical coupling), while also facilitating thermal isolation of the inner box from the outer box. 
       FIGS.  1 - 5    are diagrams associated with an optical device  100  that includes a heating element with one or more openings in which one or more mounting pads are arranged, as described herein. In some implementations, as illustrated in  FIGS.  1 - 5   , the optical device  100  includes an outer box  102 , an inner box  104 , one or more mounting pads  106 , and one or more heating elements  108  including one or more openings  110 . 
       FIG.  1    illustrates an external view of the outer box  102  of the optical device  100 . In some implementations, the outer box  102  is a structure within which an inner box  104  is arranged. In some implementations, the outer box  102  provides a hermetic seal and thermal insulation for the optical device  100 . 
       FIG.  2    illustrates an example of the inner box  104  of the optical device  100 . As noted above, the inner box  104  may be arranged within the outer box  102  (not shown in  FIG.  2   ). In some implementations, the inner box  104  is a structure that defines an inner volume of the optical device  100  (e.g., a volume of the optical device  100  in which optical components are located). For example, as illustrated in  FIG.  2   , the inner box  104  may include a platform and a pair of sidewalls. Here, optical components of the optical device  100  may be mounted within an inner volume defined by the platform and the sidewalls of the inner box  104 . That is, in the example shown in  FIG.  2   , the inner box  104  includes a platform and two sidewalls, with optical components of the optical device  100  being mounted in an inner volume that is on an underside of the platform (e.g., between the sidewalls). In some implementations, the inner box  104  provides an isothermal region or enclosure for the optical device  100 . 
     In some implementations, the one or more mounting pads  106  are arranged on one or more surfaces of the inner box  104 . For example, in the example optical device  100  shown in  FIG.  2   , four mounting pads  106  are arranged on a surface of the inner box  104  (e.g., a surface opposite that on which the optical components of the optical device  100  are mounted). In some implementations, the one or more mounting pads  106  mechanically couple the inner box  104  to, and thermally isolate the inner box  104  from, the outer box  102  (not shown in  FIG.  2   ). 
     In some implementations, the one or more mounting pads  106  are designed to account for a number of considerations. For example, the one or more mounting pads  106  may be designed so that the one or more mounting pads  106  provide sufficient thermal isolation of the (heated) inner box  104  from the outer box  102 . As another example, the one or more mounting pads  106  may be designed to provide isolation from other forces, such as a coefficient of thermal expansion (CTE) mismatch between materials, from stress, from strain, or from external forces (e.g., shock, vibration, or the like), among other examples. As another example, the one or more mounting pads  106  may be designed so that a number, size, and locations of the one or more mounting pads  106  are determined by analyzing physical constraints of a package size of the optical device  100 , thermal isolation requirements, a required adhesion strength between the mounting pads  106  and the inner box  104  and/or the outer box  102 , stress/strain isolation requirements, or external force isolation requirements. In some implementations, a selection of one or more thermal properties (e.g., thermal conductivity) and/or one or more mechanical properties (e.g., a Young&#39;s modulus, a dynamic modulus, a damping ratio, or the like) of a material of the one or more mounting pads  106  may take these factors into consideration. 
     Therefore, in some implementations, one or more characteristics of a mounting pad  106  may be based on a dynamic requirement associated with the optical device  100 , a thermal requirement associated with the optical device  100 , and/or an opto-mechanical requirement associated with the optical device  100 . Such characteristics of the given mounting pad  106  may include, for example, a size of the mounting pad  106  (e.g., a length, a width, a thickness, or the like), a geometry or shape of the mounting pad, a location of the mounting pad  106  on the surface of the inner box  104  (e.g., a location relative to another mounting pad  106 , a location relative to an edge of the heating element  108 , or the like), or a material property of the mounting pad  106 . The material property of the mounting pad may include, for example, a damping ratio, a dynamic modulus as a function of temperature and compression ratio, a thermal conductivity, or a CTE, among other examples. In some implementations, the mounting pad  106  may have a pad geometry (e.g., a thin planar structure, as illustrated in  FIG.  2   ) or may have some other geometry or structure, such as a grommet geometry. In some implementations, one or more characteristics may vary among the mounting pads  106  of the optical device  100 . 
     In some implementations, the one or more heating elements  108  are on one or more surfaces of the inner box  104 .  FIG.  3    illustrates examples of the inner box  104  with a heating element  108  arranged on a surface of the inner box  104 . In some implementations, the one or more heating elements include one or more openings  110 . For example, as illustrated in the left diagram of  FIG.  3   , the heating element  108  may include three openings  110 , and a mounting pad  106  may be arranged within each of the three openings  110  (e.g., such that the three mounting pads  106  mechanically couple the inner box  104  to the outer box  102  through a respective one of the three openings  110 ). As another example, as illustrated in the right diagram of  FIG.  3   , the heating element  108  may include four openings  110 , and a mounting pad  106  may be arranged within each of the four openings  110  (e.g., such that the four mounting pads  106  mechanically couple the inner box  104  to the outer box  102  through a respective one of the four openings  110 ). 
     In some implementations, the one or more mounting pads  106  and the one or more heating elements  108  including the one or more openings  110  are on a single surface of the inner box  104  (e.g., such that mechanical coupling is provided between the outer box  102  and a single surface of the inner box  104 ). Alternatively, in some implementations, the one or more mounting pads  106  and the one or more heating elements  108  including the one or more openings  110  may be on multiple (e.g., two, three, four, or the like) surfaces of the inner box  104  (e.g., such that mechanical coupling is provided between the outer box  102  and multiple surfaces of the inner box  104 ). For example, in some implementations, the optical device  100  may include one or more heating elements  108  on two or more surfaces of the inner box  104 . In this example, the inner box  104  includes a second platform (e.g., arranged on the opposite side of the sidewalls from the first platform), and a second heating element  108  may be arranged on a surface of the second platform, with the second heating element  108  including one or more openings  110 . Here, one or more mounting pads  106  may be arranged in the one or more openings  110  of the second heating element  108  in order to provide further mechanical coupling of the inner box  104  to the outer box  102  (e.g., such that the inner box  104  is mechanically coupled to the outer box  102  via mounting pads  106  on two opposing surfaces of the inner box  104 ). 
     In some implementations, a shape of each of the one or more heating elements  108 , a shape of each of the one or more openings  110 , a size of each of the one or more openings  110 , or a location of each of the one or more openings  110  may be configured for optimization of thermal, dynamic, and opto-mechanical requirements. In some implementations, the optimization may include, for example, minimizing temperature gradients on optics of the optical device  100 , minimizing power consumption of the heating element  108 , minimizing optical performance sensitivity of the optical device  100  to changes or variation in ambient pressure or temperature, or maximizing impact survivability, among other examples. In some implementations, variables based at least in part on which the optimization can be performed may include, for example, a geometry (e.g., a size, a shape, a location, or the like) of a given heating element  108 , a geometry of a given mounting pad  106 , a geometry of a given opening  110 , one or more material properties of a given mounting pad  106 , or a power density distribution on a given heating element  108 , among other examples. 
       FIG.  4    illustrates a diagram of the  100  showing the inner box  104  with four mounting pads  106  arranged in four openings  110  of a heating element  108  after placement of the inner box  104  in the outer box  102  (the outer box  102  is shown as transparent in  FIG.  4   ). 
     In this way, one or more heating elements  108  may include one or more openings  110 , and the one or more mounting pads  106  may be arranged in the one or more openings  110  to enable the one or more mounting pads  106  to be mounted on the inner box  104 , rather than the heating element  108 . As a result, the one or more openings  110  improve reliability of the mechanical coupling between the inner box  104  and the outer box  102  (e.g., since mounting the mounting pads  106  directly on the heating element  108  would result in unreliable mechanical coupling), while also providing sufficient thermal isolation of the inner box  104  from the outer box  102  and enabling a physical size limitation and/or a material cost limitation to be satisfied. 
     In some implementations, a heating element  108  may be a non-unitary heating element. That is, a heating element  108  may have multiple (e.g., physically separate) sections, each of which is mounted on a surface of the inner box  104 . In such a case, an opening  110  may be defined as a region between two or more sections of a non-unitary heating element  108  (e.g., a space between two separate sections of the non-unitary heating element  108 ). 
       FIG.  5    illustrates an example of the inner box  104  with a non-unitary heating element  108  arranged on a surface of the inner box  104 . In the example shown in  FIG.  5   , the heating element  108  is a non-unitary heating element that includes three sections arranged on the surface of the inner box. Here, regions between adjacent sections of the heating element  108  are defined as openings  110  (indicated with dashed lines in  FIG.  5   ). As further shown, four mounting pads  106  are arranged in the openings  110  (e.g., two mounting pads  106  are arranged in each opening  110 ). 
     As indicated above,  FIGS.  1 - 5    are provided as examples. Other examples may differ from what is described with regard to  FIGS.  1 - 5   . 
     Notably, while the techniques and apparatus described herein can be applied in an optical device such as a WSS, or a LIDAR device, these techniques and apparatuses can be applied in another type of optical device with relatively tight optical, mechanical, or thermal requirements. That is, the improved packaging concept for packaging optical and/or opto-electronic components described herein can be applied to a variety of optical devices. 
     The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementations to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the implementations. Furthermore, any of the implementations described herein may be combined unless the foregoing disclosure expressly provides a reason that one or more implementations may not be combined. 
     As used herein, satisfying a threshold may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, or the like. 
     Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various implementations. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various implementations includes each dependent claim in combination with every other claim in the claim set. As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiple of the same item. 
     No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Further, as used herein, the article “the” is intended to include one or more items referenced in connection with the article “the” and may be used interchangeably with “the one or more.” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, or a combination of related and unrelated items), and may be used interchangeably with “one or more.” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Also, as used herein, the term “or” is intended to be inclusive when used in a series and may be used interchangeably with “and/or,” unless explicitly stated otherwise (e.g., if used in combination with “either” or “only one of”). Further, spatially relative terms, such as “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the apparatus, device, and/or element in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.