PATENT DOCUMENT

Publication Number: US-10667341-B1
Application Number: US-201916554651-A
Country: US
Kind Code: B1

Title: Light projector with integrated integrity sensor

Abstract:
An optical module includes a diffractive optical element (DOE) with a transparent conductive trace disposed over a surface of the DOE. An emitter is configured to direct a beam of optical radiation through the DOE. Control circuitry is coupled to measure a resistance of the transparent conductive trace and to control operation of the emitter responsively to the resistance.

Claims:
The invention claimed is: 
     
       1. An optical module, comprising:
 a diffractive optical element (DOE); 
 a transparent conductive trace disposed over a surface of the DOE; 
 an emitter, which is configured to direct a beam of optical radiation through the DOE; and 
 control circuitry, which is coupled to measure a resistance of the transparent conductive trace and to control operation of the emitter responsively to the resistance. 
 
     
     
       2. The module according to  claim 1 , wherein an increase in the resistance is indicative of a break in the transparent conductive trace, and the control circuitry is configured to inhibit the operation of the emitter responsively to the increase in the resistance. 
     
     
       3. The module according to  claim 1 , wherein the DOE is configured to diffract the beam of optical radiation so as to create a pattern of structured light. 
     
     
       4. The module according to  claim 1 , wherein the transparent conductive trace is disposed in a serpentine pattern across an active optical area of the DOE. 
     
     
       5. The module according to  claim 1 , wherein the surface of the DOE on which the transparent conductive trace is disposed is an interior surface, and wherein the module comprises contact pads, in electrical communication with the conductive trace, on an exterior surface of the DOE for connection to the control circuitry. 
     
     
       6. The module according to  claim 5 , and comprising vias, which pass through one or more layers of the DOE from the interior surface to the exterior surface and connect the conductive trace to the contact pads. 
     
     
       7. The module according to  claim 1 , wherein the DOE comprises:
 a transparent substrate having a first index of refraction at an emission wavelength of the emitter, wherein the transparent conductive trace has a second index of refraction at the emission wavelength of the emitter; and 
 an index-matching layer, which has a third index of refraction, intermediate the first and second indexes of refraction, at the emission wavelength of the emitter, and is disposed between the transparent substrate and the transparent conductive trace. 
 
     
     
       8. The module according to  claim 7 , wherein the third index of refraction is chosen so as to minimize a reflection of the optical radiation at the emission wavelength of the emitter by the transparent conductive trace. 
     
     
       9. The module according to  claim 1 , wherein the emitter comprises a laser diode. 
     
     
       10. The module according to  claim 1 , wherein the transparent conductive trace comprises indium tin oxide (ITO). 
     
     
       11. The module according to  claim 1 , and comprising:
 a housing containing the emitter and the control circuitry, and having an opening in which the DOE is mounted; and 
 conductive traces, which are embedded in the housing and connect the transparent conductive trace disposed over the surface of the DOE to the control circuitry. 
 
     
     
       12. The module according to  claim 11 , wherein the housing comprises a plastic material, and the conductive traces comprise metal leads, which are molded into the plastic material. 
     
     
       13. The module according to  claim 11 , wherein the conductive traces comprise a metal plated onto an inner surface of the housing. 
     
     
       14. A method for projecting light, comprising:
 providing a diffractive optical element (DOE) having a transparent conductive trace disposed over a surface of the DOE; 
 directing a beam of optical radiation from an emitter through the DOE; 
 measuring a resistance of the transparent conductive trace; and 
 controlling operation of the emitter responsively to the resistance. 
 
     
     
       15. The method according to  claim 14 , wherein an increase in the resistance is indicative of a break in the transparent conductive trace, and wherein controlling the operation comprises inhibiting the operation of the emitter responsively to the increase in the resistance. 
     
     
       16. The method according to  claim 14 , wherein the transparent conductive trace is disposed in a serpentine pattern across an active optical area of the DOE. 
     
     
       17. The method according to  claim 14 , wherein the DOE comprises a transparent substrate having a first index of refraction at an emission wavelength of the optical radiation, and the transparent conductive trace has a second index of refraction at the emission wavelength of the emitter, and the method comprises disposing an index-matching layer, which has a third index of refraction, intermediate the first and second indexes of refraction, at the emission wavelength, between the transparent substrate and the transparent conductive trace. 
     
     
       18. The method according to  claim 14 , wherein the emitter and the control circuitry are disposed in a housing having an opening in which the DOE is mounted, and the method comprises embedding conductive traces in the housing so as to connect the transparent conductive trace disposed over the surface of the DOE to control circuitry, which measures the resistance of the transparent conductive trace and controls the operation of the emitter responsively thereto. 
     
     
       19. The method according to  claim 18 , wherein the housing comprises a plastic material, and embedding the conductive traces comprises molding metal leads into the plastic material. 
     
     
       20. The method according to  claim 18 , wherein embedding the conductive traces comprises plating a metal onto an inner surface of the housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application 62/731,915, filed Sep. 16, 2018, which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to optical devices, and particularly to modules and methods for projection of optical radiation. 
     BACKGROUND 
     Optical modules are commonly used in consumer electronic devices. For example, almost all current portable telephones and computers include a miniature camera module. Miniature optical projection modules are also coming into increasing use in portable consumer devices for a variety of purposes. 
     Such projection modules may be used, for example, to cast a pattern of structured light onto an object for purposes of 3D mapping (also known as depth mapping). In some systems of this sort a light source, such as a laser diode or LED, transilluminates a transparency with optical radiation so as to project a pattern onto the object. (The terms “optical” and “light” as used in the present description and in the claims refer generally to any and all of visible, infrared, and ultraviolet radiation.) An image capture assembly captures an image of the pattern that is projected onto the object, and a processor processes the image so as to reconstruct a three-dimensional (3D) map of the object. 
     Optical projectors may, in some applications, project light through one or more diffractive optical elements (DOEs). In some cases two DOEs can be used together to diffract an input beam while reducing the energy in the zero-order (undiffracted) beam. The DOEs may be mechanically sealed to a substrate to help protect and ensure their integrity. 
     SUMMARY 
     Embodiments of the present invention that are described hereinbelow provide integrated optical devices with enhanced reliability and integrity. 
     There is therefore provided, in accordance with an embodiment of the invention, an optical module, including a diffractive optical element (DOE) and a transparent conductive trace disposed over a surface of the DOE. An emitter is configured to direct a beam of optical radiation through the DOE. Control circuitry is coupled to measure a resistance of the transparent conductive trace and to control operation of the emitter responsively to the resistance. 
     In a disclosed embodiment, an increase in the resistance is indicative of a break in the transparent conductive trace, and the control circuitry is configured to inhibit the operation of the emitter responsively to the increase in the resistance. Typically, the transparent conductive trace is disposed in a serpentine pattern across an active optical area of the DOE. In one embodiment, the transparent conductive trace includes indium tin oxide (ITO). 
     In some embodiments, the DOE is configured to diffract the beam of optical radiation so as to create a pattern of structured light. Additionally or alternatively, the emitter includes a laser diode. 
     In some embodiments, the surface of the DOE on which the transparent conductive trace is disposed is an interior surface, and the module includes contact pads, in electrical communication with the conductive trace, on an exterior surface of the DOE for connection to the control circuitry. In one embodiment, the module includes vias, which pass through one or more layers of the DOE from the interior surface to the exterior surface and connect the conductive trace to the contact pads. 
     Additionally or alternatively, the DOE includes a transparent substrate having a first index of refraction at an emission wavelength of the emitter, wherein the transparent conductive trace has a second index of refraction at the emission wavelength of the emitter. An index-matching layer, which has a third index of refraction, intermediate the first and second indexes of refraction, at the emission wavelength of the emitter, is disposed between the transparent substrate and the transparent conductive trace. In a disclosed embodiment, the third index of refraction is chosen so as to minimize a reflection of the optical radiation at the emission wavelength of the emitter by the transparent conductive trace. 
     In some embodiments, the module includes a housing containing the emitter and the control circuitry, and having an opening in which the DOE is mounted. Conductive traces are embedded in the housing and connect the transparent conductive trace disposed over the surface of the DOE to the control circuitry. In one embodiment, the housing includes a plastic material, and the conductive traces include metal leads, which are molded into the plastic material. Alternatively or additionally, the conductive traces include a metal plated onto an inner surface of the housing. 
     There is also provided, in accordance with an embodiment of the invention, a method for projecting light, which includes providing a diffractive optical element (DOE) having a transparent conductive trace disposed over a surface of the DOE. A beam of optical radiation is directed from an emitter through the DOE. A resistance of the transparent conductive trace is measured, and the operation of the emitter is controlled responsively to the resistance. 
     The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic sectional view of an optical module with an integrated integrity sensor, in accordance with an embodiment of the invention; 
         FIG. 2  is a schematic sectional view of an optical module with an integrated integrity sensor, in accordance with another embodiment of the invention; 
         FIGS. 3A and 3B  are schematic frontal and sectional views, respectively, of a DOE on which a transparent conductive trace has been formed for purposes of integrity sensing, in accordance with an embodiment of the invention; 
         FIGS. 4A and 4B  are schematic sectional views of DOEs on which transparent conductive traces have been formed for purposes of integrity sensing, in accordance with other embodiments of the invention; 
         FIGS. 5A-5D  are schematic sectional views of DOEs on which transparent conductive traces have been formed for purposes of integrity sensing, in accordance with alternative embodiments of the invention; 
         FIGS. 6 and 7  are schematic frontal views of DOEs on which transparent conductive traces have been formed for purposes of integrity sensing, in accordance with further embodiments of the invention; 
         FIG. 8  is a flow chart that schematically illustrate a method for producing a DOE with an integrated intensity sensor, in accordance with an embodiment of the invention; 
         FIG. 9  is a schematic sectional view of a DOE on which a transparent conductive trace has been formed, showing details of optical index matching layers on the DOE in accordance with an embodiment of the invention; 
         FIG. 10  is a plot that schematically shows reflectance of a DOE on which a transparent conductive trace has been formed, in accordance with an embodiment of the invention; 
         FIG. 11A  is a schematic pictorial view of the housing of an optical module showing electrical traces molded into the housing, in accordance with an embodiment of the invention; 
         FIG. 11B  is a schematic frontal view of the housing of  FIG. 11A , showing a DOE connected to the electrical traces molded into the housing, in accordance with an embodiment of the invention; and 
         FIG. 11C  is a schematic pictorial view of the housing of an optical module showing electrical traces plated onto an inner surface of the housing, in accordance with another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Mass production of miniaturized optical devices calls for product designs that meet the often-conflicting objectives of high precision and reliability and low manufacturing cost. For example, a miniature projection module may be configured to project a structured light pattern, and images of the pattern captured by a camera module may then be processed for purposes of depth mapping. Loss of mechanical integrity, for instance if a mechanical or thermal shock causes the patterning element in a projection module, such as a DOE or other patterned transparency, to break, or even just crack, may cause the module to malfunction. 
     Embodiments of the present invention that are described herein address these problems by incorporating electrical traces and control circuitry into integrated optical modules, in order to detect and handle faults of this sort. These embodiments provide means for detecting loss of mechanical integrity in such a module, so that inhibitory action can be taken (such as shutting off the light emitter in a projection module). Although the disclosed embodiments relate specifically to projection modules, the principles of the present invention may similarly be applied, mutatis mutandis, in enhancing the performance of other sorts of miniaturized and integrated optical modules. 
     In the disclosed embodiments, an optical module comprises a DOE, with a transparent conductive trace disposed over a surface of the DOE. An emitter directs a beam of optical radiation through the DOE, for example to create a pattern of structured light. Control circuitry is coupled to measure the resistance of the transparent conductive trace and to control operation of the emitter responsively to the resistance. Changes in the resistance of the transparent conductive trace can be indicative of faults, leading to corrective action by the control circuitry. For example, an increase in the resistance can indicate that the transparent conductive trace has broken. The control circuitry will inhibit the operation of the emitter, reducing the beam power and possibly shutting off the emitter entirely, when the resistance increases above some threshold. 
     In some embodiments, the transparent conductive trace is disposed in a serpentine pattern across an active optical area of the DOE in order to ensure detection of any possible cracks or other damage that may develop. The term “transparent” is used in the context of the present description and in the claims to mean that the trace transmits at least 90% of incident optical radiation at the emission wavelength of the emitter. 
     Typically, however, the index of refraction of the transparent conductive trace at this emission wavelength is substantially greater than that of the transparent substrate of the DOE. To avoid loss of beam power due to reflection as a result of this index mismatch, an index-matching layer, which has an intermediate index of refraction, between the indexes of refraction of the substrate and the conductive trace, is disposed between the substrate and the trace. The index of refraction of the index-matching layer is chosen so as to minimize the reflection of the optical radiation at the emission wavelength of the emitter by the transparent conductive trace, thus in effect rendering the trace nearly completely transparent at this wavelength. 
       FIG. 1  is a schematic sectional view of an optical module  20  with an integrated integrity sensor, in accordance with an embodiment of the invention. In this embodiment, an emitter  24 , such as a chip containing a laser diode or laser diode array, is mounted on a substrate  22 , which may comprise a silicon wafer or a dielectric material, such as a suitable polymer, alumina or ceramic. 
     Emitter  24  emits a beam of optical radiation (which may be visible, infrared and/or ultraviolet) through an optical stack  26 . In the pictured embodiment, emitter  24  comprises a vertical-cavity surface-emitting laser (VCSEL), which emits radiation vertically away from substrate. Alternatively, module  20  may comprise multiples VCSELs, for example, or one or more edge-emitting lasers, together with a suitable turning mirror (not shown), or any other suitable type of top- or edge-emitting device. Lenses in optical stack  26  collimate and direct the radiation from emitter  24  through an optical output element, for example a patterning element such as a diffractive optical element (DOE)  30 , which diffracts the radiation so as to produce a pattern of structured light that can be projected onto a scene. Additionally or alternatively, optical stack  26  may comprise other components, such as a diffuser. 
     For purposes of integrity sensing, an integrity sensor  32 , comprising a transparent conductive trace, is disposed over a surface of DOE  30 . (Details of the structure of sensor  32  are shown in the figures that follow.) Sensor  32  is connected to control circuitry  34 , which provides a drive current to emitter  24 . Circuitry  34  measures the resistance of the trace of sensor  32  and controls operation of emitter  24  accordingly. Sensor  32  may be connected to circuitry  34 , for example, by connecting traces  36  running along an inner surface of a housing  28  of module  20 , or by any other suitable sort of electrical connection. Emitter  24  and control circuitry  34  are contained in housing  28 , which has an opening in which DOE  30  is mounted. 
     Housing  28  may comprise a suitable polymer, for example, in which case traces  36  are embedded, for example by molding or deposition on the polymer, using any suitable process that is known in the art. Traces  36  are connected to sensor  32  and to circuitry  34  by a conductive adhesive, such as conductive epoxy, or by soldering, for example. Details of the design and production of traces  36  in housing are shown in  FIGS. 11A-C  and described with reference to these figures hereinbelow. Embedding the traces into housing  28  provides a more robust design and reduces potential failure modes. 
     Control circuitry  34  in the pictured embodiment is embodied in an integrated circuit chip, such as an application-specific integrated circuit (ASIC), which is mounted on substrate  22 . Alternatively, the functions of control circuitry  34  may be distributed among a number of separate electronic components in module  20 . Control circuitry  34  comprises a suitable analog interface to measure the resistance of the trace in sensor  32 , as well as a drive circuit, which generates an output current at the appropriate voltage to drive emitter  24  (in either pulsed or continuous mode), along with programmable or hard-wired hardware logic circuits. 
     The hardware logic circuits in control circuitry  34  control operation of the emitter based on the measured resistance of the trace in sensor  32 , and will inhibit operation of the emitter when the resistance changes (increases or decreases) by more than a certain limit, which may be fixed or programmable. In particular, when the resistance increases sufficiently to indicate that the trace in sensor  32  may have broken, control circuitry  34  will shut off emitter  24  entirely, typically by shutting down the current provided to emitter  24 . By appropriate configuration of sensor  32  and circuitry  34 , the hardware logic circuits are able to detect conditions such as damage to DOE  30  or detachment of the DOE from housing  28 . Thus, the potential of unwanted emission from optical module  20  due to compromised integrity of DOE  30  will be avoided. 
       FIG. 2  is a schematic sectional view of an optical module  40  with an integrated integrity sensor, in accordance with another embodiment of the invention. The components and principles of operation of module  40  are similar to those of module  20 , as described above, but module  40  does not include an optical stack separate from DOE  30 . In this case, the DOE itself may perform focusing and/or collimating functions, for example, in addition to pattern generation. In addition, connecting traces  36  in module  40  are embedded in housing  28 , rather than running along the inner surface as in the preceding embodiments. 
     In other embodiments (not shown in the figures), a module with an integrated integrity sensor of this sort also comprises other components, such as a detector for collecting and sensing the projected radiation that is reflected back from a scene to the module. 
       FIGS. 3A and 3B  are schematic frontal and sectional views, respectively, of DOE  30  on which a transparent conductive trace  42  of sensor  32  has been formed for purposes of integrity sensing, in accordance with an embodiment of the invention. Transparent conductive trace  42  is disposed in a serpentine pattern across an active optical area  46  of the DOE. For example, trace  42  may comprise indium tin oxide (ITO), which is sputtered or otherwise deposited on the surface of DOE  30 , and is then patterned, using photolithographic methods that are known in the art, to define the desired form. Contact pads  44  are provided at the ends of trace  42  for connection (via traces  36  or other means) to control circuitry  34 . 
     DOE  30  may be produced by any suitable technique that is known in the art, such as photolithographic etching or replication. These techniques, along with the deposition of trace  42 , may be implemented in wafer-scale manufacturing, in which multiple DOEs  30 , with the corresponding traces  42 , are produced on a transparent wafer and then diced to singulate the DOEs. In the embodiment that is shown in  FIG. 3B , DOE  30  comprises two gratings  48 ,  50 , which are formed on respective surfaces of transparent substrates  54  and  56 , comprising glass or a suitable polymer, for example. Gratings  48  and  50  are then bonded together by an intermediate layer of a bonding material  52 . Typically, gratings  48  and  50  comprise a material with a high index of refraction, while bonding material  52  has a low index; but alternatively, gratings  48  and  50  may have a low index, while bonding material  52  has a high index. Other DOE configurations are shown in the figures that follow. 
     Trace  42  may be formed on an exterior surface of DOE  30 , or it may alternatively be covered by or encapsulated in a dielectric layer  58 , which provides mechanical protection and may also perform index-matching functions, as described below. Dielectric layer  58  may comprise a passivation layer, such as a layer of SiO2 or SiN. Openings may be etched through layer  58  to connect pads  44  to trace  42 . 
       FIGS. 4A and 4B  are schematic sectional views of DOEs  60  and  66 , respectively, on which transparent conductive traces  42  have been formed for purposes of integrity sensing, in accordance with other embodiments of the invention. In both of these embodiments, the DOE comprises only a single grating  48 , which is covered by a fill layer  62 , having a different refractive index (lower or higher) than that of grating  48 . In both of DOEs  60  and  66 , transparent conductive trace  42  is formed on an interior surface, while contact pads  44  are formed on an exterior surface of the DOE for connection to control circuitry  34  ( FIG. 1 ). Trace  42  is therefore connected to contact pads  44  by metal-filled vias  64  or  68 . Vias  64  pass through fill layer  62  of DOE  60 , while vias  68  pass through substrate  54  of DOE  66 . 
       FIGS. 5A-5D  are schematic sectional views of DOEs  61 ,  63 ,  65  and  67 , on which transparent conductive traces  42  have been formed for purposes of integrity sensing, in accordance with alternative embodiments of the invention. The components of these DOEs are marked with the same indicator numbers as in the preceding figures, and the configurations of DOEs  61 ,  65  and  67  will thus be self-evident on the basis of the figures and the foregoing description. In DOE  61  ( FIG. 5A ), trace  42  is connected to contact pads by  44  by vias  68  passing through substrate  54 . In DOE  63  ( FIG. 5B ), electrodes  44  and connected to transparent conductive trace  42  by metal traces  69  that are formed along the sides of substrate  54 . In DOE  65  ( FIG. 5C ), trace  42  is encapsulated in dielectric layer  58  and is connected to pads  44  by openings etched through the dielectric layer. In DOE  67  ( FIG. 5D ), dielectric layer  58  is formed on the opposite side of substrate  56 , and trace  42  is encapsulated in this dielectric layer  58  with connections to pads  44  etched through the dielectric layer. 
       FIGS. 6 and 7  are schematic frontal views of DOEs  70  and  74 , respectively, on which serpentine transparent conductive traces  72 ,  76  have been formed for purposes of integrity sensing, in accordance with further embodiments of the invention. Trace  72  is formed in a zigzag pattern, which both increases the baseline resistance of the trace and gives denser coverage of the surface of DOE  70 , thus enabling finer detection of small, local defects in the DOE. Trace  76  is shaped to fit the active optical area of DOE  74 . Alternatively, traces of other suitable shapes, patterns, densities and extents may be used, depending upon application requirements. 
       FIG. 8  is a flow chart that schematically illustrate a method for producing an integrated intensity sensor on a DOE, in accordance with an embodiment of the invention. The method may be carried out in a wafer-scale process, after production of the DOE layers and before singulation. 
     An optical index-matching layer is deposited over an outer surface of the DOE, such as over substrate  54 , at an index matching step  80 . Assuming substrate  54  to have a certain index of refraction at the emission wavelength of emitter  24  ( FIGS. 1-2 ), and that the transparent conductive trace of integrity sensor  32  will have a different index of refraction at this wavelength—typically greater than the index of refraction of the substrate—the index-matching layer will be designed to have index of refraction that is intermediate between the indexes of refraction of the substrate and the sensor trace. The index of refraction of the index-matching layer is chosen so as to minimize reflection of the optical radiation at the emission wavelength of emitter  24  by the transparent conductive trace.  FIGS. 9 and 10  show an example of such a design. 
     A layer of ITO is then deposited over the index-matching layer, at an ITO deposition step  82 . The ITO is patterned, for example by photolithographic etching, to produce the desired trace, at a patterning step  84 . A passivation layer is then deposited over the ITO trace, at a passivation step  86 . Vias are etched through the passivation layer to the ends of the trace, and are filled with metal to enable contact with pads  44 , at a via production step  88 . 
       FIG. 9  is a schematic sectional view of a DOE  90  on which transparent conductive trace  42  has been formed, in accordance with an embodiment of the invention. An index-matching layer  94  is deposited over substrate  54 , after which trace  42  is formed over the index-matching layer, and a passivation layer  92  is then deposited over the trace. As shown in the inset on the right side of  FIG. 9 , index-matching layer  94  in this example comprises an intermediate layer  98  of SiOH, sandwiched between upper and lower layers  96  and  100  of SiO2. Good index-matching can be achieved using the following layer thicknesses, for instance: layer  96 —39.1 nm; layer  98 −44.4 nm; and layer  100 —20.3 nm. Alternative designs will be apparent to those skilled in the art and are considered to be within the scope of the present invention. 
       FIG. 10  is a plot that schematically shows reflectance of DOE  90 , based on the above design parameters, in accordance with an embodiment of the invention. ITO has an index of refraction of 1.696 at near-infrared wavelengths. In the absence of index-matching layer  94 , this high index of refraction would result in reflection of roughly 10% of the radiation that is incident on the interface between substrate  54  and trace  42 . Index-matching layer  94 , however, reduces the reflection due to trace  42  to less than 0.5% for all angles of incidence up to about 30°. The reflection by passivation layer  92  in the area between the lines of trace  42  is likewise held below 0.5% in this angular range. Therefore, trace  42  is effectively nearly invisible to the incident radiation and has only a negligible effect on the radiation emitted from the optical module. 
     Reference is now made to  FIGS. 11A and 11B , which schematically illustrate electrical traces  100  embedded into housing  28  of an optical module for connection of sensor  32  on the surface of a DOE to control circuitry (not shown in this figure), in accordance with an embodiment of the invention. Traces  100  can take the place of traces  36  in modules  20  and  40  that are shown in  FIGS. 1 and 2 .  FIG. 11A  is a schematic pictorial view of housing  28 , while  FIG. 11B  is a schematic frontal view of the housing of  FIG. 11A , showing sensor  32  connected to traces  100 . In this embodiment, housing  28  is made from a plastic material. To create traces  100 , metal leads are inserted into the plastic mold, and the plastic is then around the metal leads. 
       FIG. 11C  is a schematic pictorial view of housing  28  of an optical module showing electrical traces  102  plated onto an inner surface of the housing, in accordance with another embodiment of the invention. In this embodiment, traces  102  are produced by laser direct structuring (LDS). This process, as is known in the art, uses a special type of plastic resin which, when exposed to a specific laser power will activate the surface of the part so that it can then be plated with a metal. The interior surfaces of housing  28  can then be selectively metal plated with this process to create embedded traces  102  running along a continuous path, which can connect sensor  32  to control circuitry. 
     The preceding figures illustrate a typical implementation of integrity control circuits and techniques, in accordance with example embodiments of the invention. The principles of these circuits and techniques, however, may similarly be implemented in other sorts of optical modules, with different sorts of trace configurations and control circuits, as will be apparent to those skilled in the art after reading the present disclosure. Although the embodiments described above related specifically to certain types of optical projection modules with DOEs for projection of structured light, and with particular module geometries, the principles of the present invention may similarly be applied to optical modules of other sorts, with different types of optical output and patterning elements and other geometries. All such alternative implementations of these principles are considered to be within the scope of the present invention. 
     It will thus be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.

Metadata:
Filing Date: 20190829
Publication Date: 20200526
Grant Date: 20200526
Priority Date: 20180916
Inventors: KRIMAN, MOSHE
MAGEN, ADAR
CHAKRAVARTULA, ARUN KUMAR NALLANI
GE, ZHENBIN
COHOON, GREGORY A.
O'CONNOR, EAMON H.
WONG, CALVIN K.
MISCHKE, COLLEEN F.
HU, Christopher
ALNAHHAS, YAZAN Z.
Assignee: APPLE INC
CPC Classifications: [{"code": "G01R31/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05B47/105", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/4233", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01S5/02248", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05B33/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B27/4233", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01R31/026", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05B37/0227", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05B44/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01S5/02325", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01S5/02257", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01R31/2843", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01S5/423", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01S5/06825", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/4227", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 70775090