PATENT DOCUMENT

Publication Number: US-10877285-B2
Application Number: US-201916242019-A
Country: US
Kind Code: B2

Title: Wavelength-based spatial multiplexing scheme

Abstract:
An optoelectronic apparatus includes an enclosure including a front face and a rear face. An array of emitters is contained in the enclosure and configured to generate first beams of optical radiation at a first wavelength and second beams of radiation at a second wavelength different from the first wavelength. Projection optics contained in the enclosure have an entrance face and an exit face and are configured to receive the beams of optical radiation through the entrance face and to project the beams through the exit face. A wavelength-based spatial multiplexer is contained in the enclosure and positioned to intercept the projected beams and configured to direct the first beams through the front face and the second beams through the rear face. A controller is coupled to selectively drive the array so as to control relative proportions of the optical radiation that are emitted through the front and rear faces.

Claims:
The invention claimed is: 
     
       1. An optoelectronic apparatus, comprising:
 an enclosure comprising a front face and a rear face; 
 an array of emitters, which is contained in the enclosure and configured to generate first beams of optical radiation at a first wavelength and second beams of radiation at a second wavelength different from the first wavelength; 
 projection optics contained in the enclosure and having an entrance face and an exit face and configured to receive the beams of optical radiation through the entrance face and to project the beams through the exit face; 
 a wavelength-based spatial multiplexer, which is contained in the enclosure and positioned to intercept the projected beams and configured to direct the first beams through the front face and the second beams through the rear face; and 
 a controller, which is coupled to selectively drive the array so as to control relative proportions of the optical radiation that are emitted through the front and rear faces. 
 
     
     
       2. The optoelectronic apparatus according to  claim 1 , wherein the wavelength-based spatial multiplexer comprises a dichroic beamsplitter configured to reflect the beams of the first wavelength toward the front face of the enclosure and to transmit the beams of the second wavelength. 
     
     
       3. The optoelectronic apparatus according to  claim 2 , wherein the wavelength-based spatial multiplexer comprises a mirror positioned to intercept the beams of the second wavelength transmitted by the dichroic beamsplitter and to reflect the intercepted beams toward the rear face of the enclosure. 
     
     
       4. The optoelectronic apparatus according to  claim 3 , wherein the mirror is configured to transmit a portion of the intercepted beams, and the apparatus comprises an optical sensor positioned to intercept the portion of the beams and configured to emit a signal to the controller responsively to an optical power of the portion of the intercepted beams. 
     
     
       5. The optoelectronic apparatus according to  claim 1 , wherein the array comprises a plurality of pairs of first and second emitters, wherein the first emitters are configured to emit the first beams of optical radiation at the first wavelength and the second emitters are configured to emit the second beams of radiation at the second wavelength. 
     
     
       6. The optoelectronic apparatus according to  claim 5 , wherein the emitters comprise lasers. 
     
     
       7. The optoelectronic apparatus according to  claim 5 , wherein the emitters comprise broadband emitters overlaid with spectral filters. 
     
     
       8. The optoelectronic apparatus according to  claim 5 , wherein the projection optics comprise:
 first cylindrical lenses, which are aligned respectively with the pairs of emitters, so that each first cylindrical lens intercepts one first beam and one second beam, and have respective, mutually parallel first cylindrical axes; and 
 a second cylindrical lens positioned adjacent to the first cylindrical lenses and having a second cylindrical axis perpendicular to the first cylindrical axes. 
 
     
     
       9. An optoelectronic apparatus, comprising:
 an array of pairs of first and second emitters, wherein the first emitters are configured to emit respective first beams of optical radiation at a first wavelength, and the second emitters are configured to emit respective second beams of optical radiation at a second wavelength; 
 projection optics having an entrance face and an exit face and configured to receive the first and second beams of the optical radiation through the entrance face and to project the beams through the exit face; and 
 a dichroic beamsplitter, which is positioned to intercept the projected beams and configured to transmit the optical radiation of the first wavelength and to reflect the optical radiation of the second wavelength. 
 
     
     
       10. The optoelectronic apparatus according to  claim 9 , wherein the projection optics comprise:
 first cylindrical lenses, which are aligned respectively with the pairs of emitters, so that each first cylindrical lens intercepts one first beam and one second beam, and have respective, mutually parallel first cylindrical axes; and 
 a second cylindrical lens positioned adjacent to the first cylindrical lenses and having a second cylindrical axis perpendicular to the first cylindrical axes. 
 
     
     
       11. The optoelectronic apparatus according to  claim 9 , wherein the projection optics are configured to provide a uniform illumination. 
     
     
       12. The optoelectronic apparatus according to  claim 9 , wherein the projection optics are configured to provide a patterned illumination. 
     
     
       13. The optoelectronic apparatus according to  claim 9 , and comprising a controller, which is coupled to drive the first and second emitters so as to set relative proportions of the optical radiation that are transmitted and reflected. 
     
     
       14. A method for projecting optical radiation, comprising:
 providing an enclosure comprising a front face and a rear face and containing an array of emitters, configured to generate first beams of optical radiation at a first wavelength and second beams of radiation at a second wavelength different from the first wavelength, and projection optics, having an entrance face and an exit face and configured to receive the beams of optical radiation through the entrance face and to project the beams through the exit face; 
 positioning a wavelength-based spatial multiplexer in the enclosure to intercept the projected beams and direct the first beams through the front face and the second beams through the rear face; and 
 selectively driving the array so as to control relative proportions of the optical radiation that are emitted through the front and rear faces. 
 
     
     
       15. The method according to  claim 14 , wherein the wavelength-based spatial multiplexer comprises a dichroic beamsplitter configured to reflect the beams of the first wavelength toward the front face of the enclosure and to transmit the beams of the second wavelength. 
     
     
       16. The method according to  claim 15 , wherein the wavelength-based spatial multiplexer comprises a mirror positioned to intercept the beams of the second wavelength transmitted by the dichroic beamsplitter and to reflect the intercepted beams toward the rear face of the enclosure. 
     
     
       17. The method according to  claim 16 , wherein the mirror is configured to transmit a portion of the intercepted beams, and wherein selectively driving the array comprises intercepting the portion of the beams and driving the array responsively to an optical power of the portion of the intercepted beams. 
     
     
       18. The method according to  claim 14 , wherein the array comprises a plurality of pairs of first and second emitters, wherein the first emitters are configured to emit the first beams of optical radiation at the first wavelength and the second emitters are configured to emit the second beams of radiation at the second wavelength. 
     
     
       19. The method according to  claim 18 , wherein the emitters comprise lasers. 
     
     
       20. The method according to  claim 18 , wherein the projection optics comprise:
 first cylindrical lenses, which are aligned respectively with the pairs of emitters, so that each first cylindrical lens intercepts one first beam and one second beam, and have respective, mutually parallel first cylindrical axes; and 
 a second cylindrical lens positioned adjacent to the first cylindrical lenses and having a second cylindrical axis perpendicular to the first cylindrical axes.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present patent application claims the benefit of U.S. Provisional Patent Application 62/648,957, filed Mar. 28, 2018, which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to optoelectronic systems, and particularly to illumination devices. 
     BACKGROUND 
     Portable electronic devices, such as cellular phones, commonly employ one or more integral light sources. These light sources may provide illumination for a scene recorded by a camera integrated into the device. As an example, U.S. Pat. No. 9,400,177 describes a pattern projector, including a light source, configured to emit a beam of light. The inventors describe a system for 3D mapping, which may be produced as a very compact unit, for example being included in a mobile station (e.g., PDA, cellular phone) and/or a portable computer. 
     SUMMARY 
     Embodiments of the present invention that are described herein provided improved sources of optical radiation. 
     There is therefore provided, in accordance with an embodiment of the invention, an optoelectronic apparatus, which includes an enclosure including a front face and a rear face. An array of emitters is contained in the enclosure and configured to generate first beams of optical radiation at a first wavelength and second beams of radiation at a second wavelength different from the first wavelength. Projection optics contained in the enclosure have an entrance face and an exit face and are configured to receive the beams of optical radiation through the entrance face and to project the beams through the exit face. A wavelength-based spatial multiplexer is contained in the enclosure and positioned to intercept the projected beams and configured to direct the first beams through the front face and the second beams through the rear face. A controller is coupled to selectively drive the array so as to control relative proportions of the optical radiation that are emitted through the front and rear faces. 
     In some embodiments, the wavelength-based spatial multiplexer includes a dichroic beamsplitter configured to reflect the beams of the first wavelength toward the front face of the enclosure and to transmit the beams of the second wavelength. In a disclosed embodiment, the wavelength-based spatial multiplexer includes a mirror positioned to intercept the beams of the second wavelength transmitted by the dichroic beamsplitter and to reflect the intercepted beams toward the rear face of the enclosure. In one embodiment, the mirror is configured to transmit a portion of the intercepted beams, and the apparatus includes an optical sensor positioned to intercept the portion of the beams and configured to emit a signal to the controller responsively to an optical power of the portion of the intercepted beams. 
     In some embodiments, the array includes a plurality of pairs of first and second emitters, wherein the first emitters are configured to emit the first beams of optical radiation at the first wavelength and the second emitters are configured to emit the second beams of radiation at the second wavelength. The emitters may include lasers or, alternatively, broadband emitters overlaid with spectral filters. 
     Additionally or alternatively, the projection optics include first cylindrical lenses, which are aligned respectively with the pairs of emitters, so that each first cylindrical lens intercepts one first beam and one second beam, and have respective, mutually parallel first cylindrical axes, and a second cylindrical lens positioned adjacent to the first cylindrical lenses and having a second cylindrical axis perpendicular to the first cylindrical axes. 
     There is also provided, in accordance with an embodiment of the invention, an optoelectronic apparatus, including an array of pairs of first and second emitters, wherein the first emitters are configured to emit respective first beams of optical radiation at a first wavelength, and the second emitters are configured to emit respective second beams of optical radiation at a second wavelength. Projection optics having an entrance face and an exit face are configured to receive the first and second beams of the optical radiation through the entrance face and to project the beams through the exit face. A dichroic beamsplitter is positioned to intercept the projected beams and configured to transmit the optical radiation of the first wavelength and to reflect the optical radiation of the second wavelength. 
     In some embodiments, the projection optics are configured to provide a uniform illumination. Alternatively, the projection optics are configured to provide a patterned illumination. 
     Additionally or alternatively, the apparatus includes a controller, which is coupled to drive the first and second emitters so as to set relative proportions of the optical radiation that are transmitted and reflected. 
     There is additionally provided, in accordance with an embodiment of the invention, a method for projecting optical radiation, which includes providing an enclosure including a front face and a rear face and containing an array of emitters, configured to generate first beams of optical radiation at a first wavelength and second beams of radiation at a second wavelength different from the first wavelength, and projection optics, having an entrance face and an exit face and configured to receive the beams of optical radiation through the entrance face and to project the beams through the exit face. A wavelength-based spatial multiplexer is positioned in the enclosure to intercept the projected beams and direct the first beams through the front face and the second beams through the rear face. The array is selectively driven so as to control relative proportions of the optical radiation that are emitted through the front and rear faces. 
     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 perspective illustration of an optoelectronic apparatus, in accordance with an embodiment of the invention; and 
         FIG. 2  is a schematic perspective illustration of an optoelectronic apparatus, in accordance with another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     A portable electronic device may employ more than one light source for providing illumination for sub-systems integral to the device, such as front- and rear-side cameras. Realizing these light sources and their switching mechanisms within the constraints of volume and cost of a typical portable electronic device, such as a cellular phone, is challenging. 
     Embodiments of the present invention that are described herein address these problems by providing a compact optoelectronic apparatus featuring a spatially multiplexed light source. 
     In the disclosed embodiments, the optoelectronic apparatus includes an enclosure, with an array of emitters of beams of optical radiation at two different wavelengths, projection optics, a wavelength-based spatial multiplexer, and a controller contained in the enclosure. (The terms “optical radiation” and “light” as used in the present description and in the claims refer generally to any and all of visible, infrared, and ultraviolet radiation.) 
     The projection optics are common to all of the emitted beams, and in some embodiments include an array of first cylindrical lenses with mutually parallel first cylinder axes and a second cylindrical lens, adjacent to the array of first cylindrical lenses, with a second cylinder axis perpendicular to the first axes. Depending on the optical parameters, this arrangement can be used to create uniform flood lighting or patterned radiation over the field of interest. 
     The beams of optical radiation emitted by the array of emitters are received by the projection optics and projected toward the wavelength-based spatial multiplexer, comprising, for example, a dichroic beamsplitter. The spatial multiplexer directs the beams, depending on their wavelength, to be emitted through the front face or the rear face of the enclosure. 
     The beams emitted through the front or rear faces may have different functionalities. For instance, the beams emitted through the front face may project patterned illumination onto a scene, enabling 3D mapping based on triangulation, whereas a scanner may be added to scan the beams emitted through the rear face, enabling 3D mapping based on time-of-flight (TOF). Alternatively or additionally, the beams may be used for other purposes, such as uniform flood lighting. 
     In an embodiment of the present invention, the array of emitters includes first emitters emitting first beams of optical radiation at a first wavelength and second emitters emitting second beams of optical radiation at a second wavelength, different from the first wavelength. Each first cylindrical lens of the lens array receives one beam of each wavelength and projects them toward the second cylindrical lens, which, in turn, projects the beams toward the wavelength-based spatial multiplexer. The spatial multiplexer receives the first and second beams, and reflects the first beams and transmits the second beams. The first, reflected beams are emitted through one face of the enclosure, for example the front face. 
     A mirror, either free standing or embedded in a cube, can be included in the spatial multiplexer for deflecting the second beams transmitted through the beamsplitter. The second, transmitted beams impinge on and are reflected by the mirror, and are thus emitted through the opposite face of the enclosure, for example the rear face. 
     The controller drives either the first or second emitters or both, so that beams can be directed through either the front face, rear face, or both faces of the enclosure. The controller may further adjust the relative proportions of the optical powers emitted by the first and the second emitters, respectively, so as to control the relative proportions of the optical radiation that are emitted through the front and rear faces 
     In the present description, the terms “front face” and “rear face” are used by way of example only, and in general can denote any two faces of the enclosure. Furthermore, although some of the embodiments described herein are particularly well suited for integration in a narrow enclosure as described above, the principles of the present invention may also be applied to provide wavelength-based spatial multiplexing in other settings, irrespective of any particular type of enclosure. 
     In a further embodiment, the mirror of the spatial multiplexer is configured to transmit a portion of the optical radiation impinging on it. An optical sensor receives this leaked portion of the optical radiation, and emits a signal that can be used, for example, for measuring the optical power of the beams transmitted by the spatial multiplexer or, if in a scanning system, the relative position of the optical output. 
       FIG. 1  is a schematic perspective illustration of an optoelectronic apparatus  20 , in accordance with an embodiment of the invention. Optoelectronic apparatus  20  includes an emitter array  22 , projection optics  26 , a wavelength-based spatial multiplexer  28 , and a controller  32 , which are all typically contained in an enclosure  30 . Enclosure  30  comprises a front face  72  and a rear face  74 . For the sake of simplicity and clarity, any actuating mechanisms that would be provided to scan the optical output are omitted. 
     Cartesian coordinate axes  33  are shown in  FIGS. 1-2  for reference. 
     Emitter array  22  includes first emitters  34  and second emitters  36 . First emitters  34  emit optical radiation at a first wavelength λ 1 , and second emitters  36  emit optical radiation at a second wavelength λ 2 . Wavelengths λ 1  and λ 2  differ from each other sufficiently to ensure that the emission spectra of the first and second emitters do not overlap. Both first emitters  34  and second emitters  36  are arranged in emitter array  22  along a line in the x-direction of Cartesian coordinate axes  33 , with alternating first and second emitters, so as to form pairs of first and second emitters. Emitters  34  and  36  may comprise, for example, vertical-cavity surface emitting lasers (VCSELs) or light-emitting diodes (LEDs) emitting respectively at wavelengths λ 1  and λ 2 , or broadband emitters of any suitable type, which are overlaid with spectral filters centered respectively at wavelengths λ 1  and λ 2 . 
     Projection optics  26  include a lens array  38  of first cylindrical lenses  40 , wherein the entrance faces of the first cylindrical lenses define an entrance face  42  of projection optics  26 . First cylindrical lenses  40  are oriented so that their cylinder axes are mutually parallel along the y-axis (perpendicular to the line of first and second emitters  34  and  36 , respectively). Each first cylindrical lens  40  is aligned with a pair of first and second emitters  34  and  36 , respectively. Projection optics  26  further include a second cylindrical lens  46 , whose exit face defines an exit face  50  of projection optics  26 . Second cylindrical lens  46  is positioned adjacent to lens array  38 , and oriented with its cylinder axis along the x-axis (perpendicular to the cylinder axes of first cylindrical lenses  40 ). 
     Spatial multiplexer  28  includes a dichroic beamsplitter  58 , positioned adjacent to exit face  50  of projection optics  26 , and oriented typically at an angle of 45 degrees with respect to the z-axis. Dichroic beamsplitter  58  is configured to reflect optical radiation at wavelength λ 1  emitted by first emitters  34  and to transmit optical radiation at wavelength λ 2  emitted by second emitters  36 . Spatial multiplexer  28  also includes a partially-transmitting mirror  60 , positioned adjacent to dichroic beamsplitter  58  and oriented typically at an angle of −45 degrees with respect to the z-axis, i.e., in a direction perpendicular to that of the dichroic beamsplitter in the present example. Spatial multiplexer  28  further includes an optical sensor  84  added behind the partially-transmitting mirror. 
     Controller  32  is coupled to drive emitter array  22  as well as to receive signals from optical sensor  84 . Controller  32  may be positioned either inside or outside enclosure  30 . In some embodiments, the controller is programmed in software and/or firmware to carry out the functions that are described herein. Additionally or alternatively, at least some of the functions of the controller may be carried out by hardware logic circuits, which may be hard-wired or programmable. In either case, the controller has suitable interfaces for receiving and transmitting data and instructions to and from other elements of the optoelectronic apparatus, as well as other apparatus with which the optoelectronic apparatus is integrated. 
     The functioning of optoelectronic apparatus  20  is shown schematically in  FIG. 1 , with first optical rays  110  and second optical rays  112  denoting the beams of optical radiation emitted by first and second emitters  34  and  36 , respectively, and projected by the apparatus. The beams are received in projection optics  26  through entrance face  42 , with each first cylindrical lens  40  receiving one beam from one first emitter  34  and one beam from one second emitter  36 . First cylindrical lenses  40  collimate the beams in the x-direction and project them toward second cylindrical lens  46 , which in turn collimates the beams in the y-direction and projects them through exit face  50  toward dichroic beamsplitter  58 . 
     Beams from first emitters  34 , depicted by first optical rays  110 , are reflected by dichroic beamsplitter  58  to a first exit window  62  and are emitted through the window. Beams from second emitters  36 , depicted by second optical rays  112 , are transmitted by dichroic beamsplitter  58  and reflected by partially transmitting mirror  60  to a second exit window  64  and are emitted through the window. Exit windows  62  and  64  are located respectively on front and rear faces  72  and  74  of enclosure  30 . Exit windows  62  and  64  are manufactured of a material that is transparent to wavelengths λ 1  and λ 2 . Alternatively, exit windows  62  and  64  may simply be openings in enclosure  30 . A portion of second optical rays  112  passes through partially transmitting mirror  60  and is received by optical sensor  84  (transmitted rays not shown). Optical sensor  84 , coupled to controller  32 , may be used, for example, for measuring the power emitted by second emitters  36 . 
     When controller  32  energizes only first emitters  34 , only first optical rays  110  are present, and optical radiation is emitted only through first exit window  62 . Similarly, when controller  32  energizes only second emitters  36 , only second optical rays  112  are present, and optical radiation is emitted only through second exit window  64 . 
     The compact size of optoelectronic apparatus  20  is indicated by a scale  114 , wherein the length of the scale is 2 mm. Alternatively, the elements of apparatus  20  may be made to a larger or smaller scale, depending on application requirements. 
       FIG. 2  is a schematic perspective illustration of an optoelectronic apparatus  120 , in accordance with another embodiment of the invention. For the components substantially identical to those in  FIG. 1 , the same labels are used. Cartesian coordinate axes  33  are again shown for reference, but enclosure  30  is omitted for the sake of simplicity. 
     Optoelectronic apparatus  120  includes an emitter array  124  of first emitters  126  and second emitters  128 . First emitters  126  emit optical radiation at a first wavelength λ 1 , and second emitters  128  emit optical radiation at a second wavelength λ 2 . As in the previous embodiment, emitters  126  and  128  may comprise, for example, VCSELs, LEDs, or broadband sources with suitable filters. First emitters  126  and second emitters  128  are positioned, respectively, along two parallel straight lines in the x-direction, with each first emitter  126  aligned above a second emitter  128  in the y-direction, forming pairs of first and second emitters so that each pair is aligned with one cylindrical lens  40 . The remaining elements of apparatus  120  are similar to those shown and described above. 
     The functioning of optoelectronic apparatus  120  is shown schematically in  FIG. 2 , with first optical rays  130  and second optical rays  132  denoting the beams of optical radiation emitted by first and second emitters  126  and  128 , respectively, and passed through the apparatus. 
     The beams are received through entrance face  42 , with each first cylindrical lens  40  receiving one beam from one first emitter  126  and one beam from one second emitter  128 . Projection optics  26  collimate the beams in the x- and y-directions as in the previous embodiment depicted in  FIG. 1 , and project them through exit face  50  to dichroic beamsplitter  58 . Beams from first emitters  126 , depicted by first optical rays  130 , are reflected by dichroic beamsplitter  58  to first exit window  62  and are emitted through the window. Beams from second emitters  128 , depicted by second optical rays  132 , are transmitted by dichroic beamsplitter  58  and reflected by partially-transmitting mirror  60  to second exit window  64  and are emitted through the window. 
     When controller  32  energizes only first emitters  126 , only first optical rays  130  are present, and optical radiation is emitted only through first exit window  62 . Similarly, when controller  32  energizes only second emitters  128 , only second optical rays  132  are present, and optical radiation is emitted only through second exit window  64 . 
     The compact size of optoelectronic apparatus  120  is indicated by a scale  134 , wherein the length of the scale is 2 mm. 
     Although the disclosed embodiments refer to optical beams being emitted through the front face and the rear face of the enclosure, the wavelength-based spatial multiplexer may be modified in a straightforward manner to emit the beams through other faces of the enclosure, such as through faces at right angles to each other or through two windows on the same face. Furthermore, although the embodiments described above use pairs of emitters with different wavelengths, in alternative embodiments (not shown in the figures), each pair of emitters may be replaced by a single tunable emitter, such as a tunable laser diode, which can be controlled to emit radiation at either λ 1  or λ 2 , or by a single broadband emitter with the addition of a tunable wavelength filter between the emitters and the spatial multiplexer. 
     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: 20190108
Publication Date: 20201229
Grant Date: 20201229
Priority Date: 20180328
Inventors: MACKINNON, NEIL
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B19/0014", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04J14/0209", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/141", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B10/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/1006", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B19/0057", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B19/0066", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B10/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04J14/0209", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/1006", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 68054242