Light projector device for projecting light rays onto an observation field and method for producing a light projector device

Abstract

The invention relates to a light projector device for projecting light rays onto an observation field and a method for producing a light projector device. According to the invention, a light projector device for projecting light beams onto an observation field comprises a light source for generating a first light beam of a first color propagating in a first entry direction and a second light beam of a second color propagating in a second entry direction and spaced apart from the first light beam in the transverse direction; a first diffraction unit for diffracting light beams generated by the light source along the transverse direction in a wavelength-dependent manner such that light beams diffracted by the first diffraction unit propagate in a propagation plane; a second diffraction unit for diffracting light beams diffracted by the first diffraction unit along the transverse direction in a wavelength-dependent manner such that the light beams diffracted by the first diffraction unit propagate as light beams at least partially superimposed in the transverse direction along an exit direction;and a microscanner with a mirror alignable along at least one rotation axis to controllably deflect light beams diffracted by the second diffraction unit.

Description

Technical field of the invention

[0001] The present invention relates to a light projector device for projecting light rays onto an observation field and a method for manufacturing a light projector device.

[0002] Light projector devices are frequently used in virtual reality (VR) or augmented reality (AR) headsets, helmets, or head-up displays. Light beams generated by a light source are projected onto a controllable mirror of a microscanner, such as a microelectromechanical system (MEMS). To generate an image or text information, the microscanner's controllable mirror directs the light beams onto an observation field. In VR applications, the observation field is a screen, whereas in AR applications, the observation field is a partially transparent glass. State of the art

[0003] To generate the image or text information, the mirror of the microscanner can perform rotary oscillations, for example, around a vertical axis and a horizontal axis, in order to direct the light beam in a scanning manner onto the observation field and thus generate the image or text information visible to the user line by line.

[0004] For an undistorted image, good collimation and (intermediate) focusing of the light beams, for example, using lenses, is important. To generate color images, the light source must also generate light beams of different colors. For this purpose, the light source typically includes diode lasers for generating red, green, and blue light beams. The differently colored light beams must then be superimposed before hitting the microscanner's mirror. This is usually achieved using a large number of lenses and semi-transparent mirrors.

[0005] The design and arrangement of the optical elements for collimating, (intermediate) focusing, and superimposing the multicolored light beams must be matched to their color. In known light projector devices, particularly those that use semi-transparent mirrors to superimpose the multicolored light beams, this results in a complicated structure and causes the light beams to spread out in multiple planes, resulting in complicated light beam guidance. This leads, among other things, to the disadvantage that such light projector devices are not, or only insufficiently, compatible with highly parallelized manufacturing processes, particularly those that use wafer-level assembly and the wafer-to-wafer bonding enabled thereby. Wafer-level assembly (also called wafer-level assembly) refers to a technology in which parts or components are formed directly on a wafer.A wafer is a disc of semiconductor material, such as silicon. Performing assembly at the wafer level can significantly reduce production time and costs.

[0006] US 2011 / 0310356 A1 discloses an image display device with an RGB lighting module including a diffractive beam combiner. The diffractive beam combiner includes a first light source configured to generate a first light beam of red color and a second light source configured to generate a second light beam of green color. A centerline of the first light beam and a centerline of the second light beam are arranged to intersect at an intersection point. A diffractive output grating is located near the intersection point. The diffractive output grating is arranged to form an output light beam by diffracting the light of the first light beam and the light of the second light beam substantially in the same direction. Description of the invention

[0007] It is an object of the present invention to overcome the disadvantages of the prior art and to provide a light projector device with a simplified structure and a method for manufacturing a light projector device with a simplified structure.

[0008] This object is achieved by a light projector device and a method for producing a light projector device according to the respective independent claim. The corresponding subclaims relate to advantageous embodiments of the invention.

[0009] The invention comprises a light projector device for projecting light rays onto an observation field comprising: a light source configured to generate a first light beam of a first color propagating along a first entry direction and a second light beam of a second color propagating along a second entry direction and spaced apart from the first light beam along a transverse direction, a first diffraction unit configured to diffract light rays generated by the light source along the transverse direction in a wavelength-dependent manner, so that light rays diffracted by the first diffraction unit propagate in a propagation plane, a second diffraction unit which is designed to diffract light beams diffracted by the first diffraction unit along the transverse direction in a wavelength-dependent manner such that the light beams diffracted by the first diffraction unit propagate as light beams at least partially superimposed in the transverse direction along an exit direction, and a microscanner with a mirror which can be aligned along at least one rotation axis and which is designed to controllably deflect light beams diffracted by the second diffraction unit, wherein the first diffraction unit is formed in a front side of a first wafer die and wherein the second diffraction unit is formed in a back side of the first wafer die opposite to the front side of the first wafer die.

[0010] The first diffraction unit can be designed as a grating, in particular as a volume holographic grating. In this case, the first diffraction unit can diffract the light beams generated by the light source by a diffraction angle φ1 along the transverse direction as a function of the wavelength λ of the light beam according to the equation λ = d1 sin(φ1), wherein the first diffraction unit has a grating constant d1.

[0011] The first diffraction unit can be designed to diffract the light rays generated by the light source along the transverse direction in a wavelength-dependent manner, so that the diffracted light rays are focused in a focal point located in the second diffraction unit.

[0012] The second diffraction unit can be designed as a grating, in particular as a volume holographic grating. In this case, the second diffraction unit can diffract light beams diffracted by the first diffraction unit by a diffraction angle φ2 along the transverse direction as a function of the wavelength λ of the light beam according to the equation λ = d2 sin(φ2), wherein the second diffraction unit has a grating constant d2.

[0013] In order for the light beams diffracted by the first diffraction unit to propagate as light beams at least partially superimposed in the transverse direction along an exit direction, the second diffraction unit can be designed to diffract the light beams diffracted by the first diffraction unit in a wavelength-dependent manner in the opposite direction to that of the first diffraction unit.

[0014] According to an advantageous aspect, the light source is designed such that the light rays generated by the light source propagate in the propagation plane, and the second diffraction unit is designed such that the light rays diffracted by the second diffraction unit propagate in the propagation plane.

[0015] This allows the light beam path from the light source to the microscanner to lie entirely in the propagation plane. This enables a particularly simple and compact design of the light projector devices, which is particularly suitable for wafer-level assembly techniques, such as wafer-to-wafer bonding.

[0016] According to a further advantageous aspect, the second diffraction unit is designed such that the exit direction is perpendicular to the transverse direction.

[0017] This can be achieved by designing the second diffraction unit as a grating with a surface normal, and by designing the grating such that the surface normal is parallel to the propagation direction. This enables a particularly simple and compact design of the light projector devices, which is particularly suitable for wafer-level assembly techniques, such as wafer-to-wafer bonding.

[0018] According to a particularly advantageous aspect, the second diffraction unit is designed to diffract light beams diffracted by the first diffraction unit along the transverse direction in a wavelength-dependent manner such that the light beams diffracted by the first diffraction unit propagate as light beams superimposed in the transverse direction in a range between 80% and 100% of their cross-sectional area, in particular in a range between 90% and 95% of their cross-sectional area, along the exit direction.

[0019] This allows the superimposed light beams to propagate further to the microscanner, so that all superimposed light beams can be deflected by the microscanner in the same controllable manner. The superimposed light beams can include the colors red, green, and blue, or any other combination of at least two colors.

[0020] According to a preferred aspect, the light source is designed to generate a third light beam of a third color propagating along a third entrance direction and spaced apart from the first light beam and second light beam along the transverse direction.

[0021] The first light beam can be blue, the second light beam green, and the third light beam red. The light source can be configured such that the first, second, and third entry directions are parallel to each other.

[0022] According to a further preferred aspect, the first diffraction unit and / or the second diffraction unit are each designed such that at least two of the light beams generated by the light source are diffracted in opposite directions along the transverse direction.

[0023] This can be achieved by having the first diffraction unit and / or the second diffraction unit each comprise an optical metamaterial. The optical metamaterial can have a nanostructure. The optical metamaterial can have a negative diffraction index for at least one color, so that light rays of this color are diffracted in the opposite direction along the transverse direction compared to diffraction with a positive diffraction index.

[0024] The material of the wafer die can be a semiconductor material. The first diffraction unit can be formed by nanostructuring in a front side of the first wafer die, and the second diffraction unit can be formed in a back side of the first wafer die opposite the front side of the first wafer die.

[0025] According to an advantageous aspect, the light projector device comprises a beam shaping unit arranged between the light source and the first diffraction unit, which is designed to completely collimate or not completely collimate light rays propagating from the light source in the direction of the first diffraction unit.

[0026] The beam-shaping unit can be designed such that, upon complete collimation, the light beams fully collimated in the direction of the first diffraction unit are parallel to each other and perpendicular to the first diffraction unit. If the beam-shaping unit does not fully collimate, a virtual or real focal point can be created along an optical axis of the beam-shaping unit.

[0027] According to a further advantageous aspect, the beam shaping unit comprises cylindrical lenses, in particular pairs of plano-cylindrical lenses rotated by 90° relative to one another about the optical axis, and / or spherical, and / or aspherical, and / or acylindrical lenses.

[0028] According to a particularly advantageous aspect, the light projector device comprises a focusing unit arranged between the second diffraction unit and the microscanner, which is designed to focus light beams diffracted by the second diffraction unit and propagating along the exit direction in the direction of the microscanner.

[0029] This allows the divergence of the light rays propagating along the exit direction toward the microscanner to be influenced in such a way that imaging errors are minimized or eliminated. This advantageously contributes to deflecting the light rays from the microscanner in such a way that a sharp image is projected onto the observation field.

[0030] According to a preferred aspect, the beam shaping unit is formed in a second wafer die and the focusing unit is formed in a third wafer die.

[0031] The formation of the beam shaping unit in a second wafer die and the formation of the focusing unit in a third wafer die enables the application of highly parallelized wafer-based processes.

[0032] According to a further preferred aspect, the first wafer die is arranged on the second wafer die by wafer-to-wafer bonding, and the third wafer die is arranged on the first wafer die by wafer-to-wafer bonding.

[0033] In this case, a plurality of first wafer dies can be formed at each location of a regular grid arrangement of a first wafer, a plurality of second wafer dies can be formed at each location of a regular grid arrangement of a second wafer, and a plurality of third wafer dies can be formed at each location of a regular grid arrangement of a third wafer. The regular grid arrangements are designed such that, during wafer-to-wafer bonding, a first wafer die, a second wafer die, and a third wafer die are assigned to one another. Following wafer-to-wafer bonding, wafer dies can be singulated. This enables highly parallelized production.

[0034] According to a particularly preferred aspect, the microscanner is designed as a micro-electromechanical system (MEMS).

[0035] According to an advantageous aspect, the light source comprises a semiconductor laser unit, in particular designed as a VCSEL, for generating a light beam of a specific color.

[0036] Furthermore, the invention relates to a method for producing a light projector device comprising the method steps: A) providing a first wafer in which, for each location of a regular grid arrangement, a first diffraction unit is formed in a front side of the first wafer and a second diffraction unit is formed in a rear side of the first wafer opposite the front side of the first wafer; B) providing a second wafer in which a beam-forming unit for the complete or incomplete collimation of light beams is formed for each location of a regular grid arrangement; C) providing a third wafer in which a focusing unit is formed for each location of a regular grid arrangement; D) wafer-to-wafer bonding of the first wafer to the second wafer such that a first diffraction unit formed in the first wafer is associated with a beam shaping unit formed on the second wafer; E) wafer-to-wafer bonding of the third wafer to the second wafer such that a focusing unit formed on the third wafer is associated with a second diffraction unit formed in the first wafer; F) providing one light source per beam-shaping unit and arranging one light source at each beam-shaping unit; G) Providing one microscanner each with a mirror alignable along at least one rotation axis per focusing unit and arranging one microscanner each on a focusing unit; and H) Singulating wafer dies from the wafer-to-wafer bonded wafers.

[0037] In this case, the first diffraction units and the second diffraction units can be formed on the first wafer, the beam shaping units on the second wafer and the focusing units on the third wafer by assembly at the wafer level.

[0038] Each method step can additionally comprise the provision of a protective gas and / or a negative pressure in cavities present during the method for manufacturing the light projector device. This can be achieved, for example, by carrying out all or some of the method steps within an environment with a protective gas and / or negative pressure. The provision of a protective gas serves in particular to protect against external influences, such as contamination by particles contained in normal ambient air. The provision of a negative pressure serves in particular to protect the moving mechanical and optical components by reducing friction and mitigating thermal effects. Cavities can be formed within an encapsulation present around the mirror of the microscanner, which hermetically encloses the mirror.

[0039] In process step F), the positioning of the light source can be carried out by means of a position measurement (passive) or by measuring the emerging beam (active).

[0040] Wafer-to-wafer bonding can be achieved, for example, using bonding materials comprising metals, polymers, epoxy, or acrylic resins, which are applied to the wafer in a structured or full-surface manner. The bonding materials can be applied to the wafer, for example, over the entire surface and subsequently structured, or they can be applied only to certain areas of the wafer using selective processes, such as stamping processes.

[0041] The allocation of optical components, each located at a location in the regular grid arrangement of the corresponding wafers, can be achieved by aligning the wafers to one another using microscopes and traversing devices on which the wafers are arranged. This allows an allocation accuracy in the micrometer range to be achieved.

[0042] The separation of wafer dies from the wafer-to-wafer connected wafers can be carried out by mechanically sawing the wafers in such a way as to capture one location of the regular grid arrangement of a wafer and to separate it from other locations of the regular grid arrangement of a wafer.

[0043] A wafer die can thus represent a composite optical device comprising at least a first diffraction unit, a second diffraction unit, a beam shaping unit and a focusing unit.

[0044] According to a preferred aspect, in method step F), providing one light source per beam-shaping unit and arranging one light source at a beam-shaping unit comprises: F1) Providing a fourth wafer in which one light source is formed per location of a regular grid arrangement; and F2) Wafer-to-wafer bonding of the fourth wafer to the second wafer, such that a light source formed on the fourth wafer is assigned to a beam-shaping unit formed in the second wafer.

[0045] The light source can be formed on the fourth wafer by wafer-level assembly.

[0046] The method step H) of singulating wafer dies from the wafer-to-wafer bonded wafers can be carried out after the method step F2) of wafer-to-wafer bonding the fourth wafer on the second wafer, so that a wafer die represents a composite optical device which comprises at least a first diffraction unit, a second diffraction unit, a beam shaping unit, a focusing unit and a light source.

[0047] According to a further preferred aspect, in method step G), the provision of one microscanner each with a mirror alignable along at least one rotation axis per focusing unit and the arrangement of one microscanner each on a focusing unit comprises: G1) Providing a fifth wafer in which one microscanner is formed per location of a regular grid arrangement; and G2) Wafer-to-wafer bonding of the fifth wafer to the third wafer, such that a microscanner formed on the fifth wafer is assigned to a focusing unit formed in the third wafer.

[0048] The microscanner can be formed on the fifth wafer by wafer-level assembly.

[0049] The method step H) of singulating wafer dies from the wafer-to-wafer bonded wafers can be carried out after the method step G2) of wafer-to-wafer bonding the fifth wafer on the third wafer, so that a wafer die represents a composite optical device which comprises at least a first diffraction unit, a second diffraction unit, a beam shaping unit, a focusing unit and a microscanner.

[0050] Additional wafers with optical functions, such as beam shaping, can be mounted on the fifth wafer before or after singulation into wafer dies.

[0051] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations indicated, but also in other combinations or on their own, without departing from the scope of the present invention. Short description of the drawings

[0052] The invention is explained in more detail below using exemplary embodiments. In the following: Fig. 1 Schematic sectional view in the propagation plane AA of a light projector device in an asymmetrical embodiment; Fig. 2 Schematic sectional view in the propagation plane AA of a light projector device in a symmetrical embodiment; Fig. 3a Perspective view of an arrangement of parts of a light projector device after process steps A), B), C), D), and E) of a method for producing a light projector device have been carried out; Fig. 3b Perspective view of an arrangement of parts of a light projector device after method steps A), B), C), D), E), and H) of a method for producing a light projector device have been carried out; Fig. 3c Perspective view of an arrangement of parts of a light projector device after process steps A), B), C), D), E), H), and F) of a method for manufacturing a light projector device have been carried out; and Fig. 4 Perspective view of an arrangement of parts of a light projector device after process steps A), B), C), D), E), F), and G) of a method for producing a light projector device have been carried out; Fig. 5a Schematic representation of process steps of the method for producing a light projector device, which in Fig. 3a have been and have not yet been carried out; Fig. 5b Schematic representation of process steps of the method for producing a light projector device, which in Fig. 3b have been and have not yet been carried out; Fig. 5c Schematic representation of process steps of the method for producing a light projector device, which in Fig. 3c have been and have not yet been carried out; and Fig. 5d Schematic representation of process steps of the method for producing a light projector device, which in Fig. 4 have been and have not yet been completed. Detailed description of the drawings

[0053] Fig. 1 and Fig. 2 are described together below, whereby Fig. 1 is a schematic sectional view in the propagation plane AA of a light projector device 1 in an asymmetrical embodiment and Fig. 2 shows a schematic sectional view in the propagation plane AA of a light projector device 1 in a symmetrical embodiment. The asymmetrical or symmetrical embodiment refers to the respective design of the first diffraction unit 20 and the second diffraction unit 21 such that the beam path of the light beams 11b, 12b, 13b diffracted by the first diffraction unit 20 is asymmetrical between the first diffraction unit 20 and the second diffraction unit 21 as in Fig. 1 or symmetrical as in Fig. 2 is.

[0054] The light projector device 1 comprises a light source 10 with three semiconductor laser units 14, 15, 16, each of which is designed as a VCSEL for generating a light beam 11a, 12a, 13a of a specific color.

[0055] The light source 10 is designed such that the first semiconductor laser unit 14 generates a first light beam 11a of the color blue, propagating along a first entry direction E1 and in the propagation plane AA, the second semiconductor laser unit 15 generates a second light beam 12a of the color green, propagating along a second entry direction E2 and in the propagation plane AA and spaced from the first light beam 11a along a transverse direction T, and the third semiconductor laser unit 16 generates a third light beam 13a of the color red, propagating along a third entry direction E3 and in the propagation plane AA and spaced from the first light beam 11a and second light beam 12a along the transverse direction T.

[0056] The first semiconductor laser unit 14, the second semiconductor laser unit 15 and the third semiconductor laser unit 15 are arranged in the light source 10 such that the first entrance direction E1, the second entrance direction E2 and the third entrance direction E3 are parallel to each other.

[0057] A second wafer die 43 with a beam-shaping unit 40 is arranged on the light source 10. The beam-shaping unit 40 comprises, for each light beam 11a, 12a, 13a, a pair of plano-cylindrical lenses 41a, 41b, each rotated 90° relative to the optical axis, in order to completely collimate the light beams 11a, 12a, 13a propagating from the light source 10 in the direction of the first diffraction unit 20 such that the light beams 11a, 12a, 13a impinge on the first diffraction unit 20 parallel to one another and perpendicular to the first diffraction unit 20.

[0058] A first wafer die 22 is arranged on the second wafer die 43. A first diffraction unit 20 is formed by nanostructuring in a front side of the first wafer die 22, and a second diffraction unit 21 is formed by nanostructuring in a back side of the first wafer die 22 opposite the front side of the first wafer die 22.

[0059] The first diffraction unit 20 is designed to diffract the light beams 11a, 12a, 13a generated by the light source 10 along the transverse direction T in a wavelength-dependent manner, so that light beams 11b, 12b, 13b diffracted by the first diffraction unit 20 propagate in the propagation plane AA.

[0060] The second diffraction unit 21 is designed to diffract the light beams 11b, 12b, 13b diffracted by the first diffraction unit 20 along the transverse direction T in a wavelength-dependent manner such that the light beams 11b, 12b, 13b diffracted by the first diffraction unit 20 propagate as light beams 11c, 12c, 13c superimposed in the transverse direction T in a range between 90% and 95% of their cross-sectional area along an exit direction A which is perpendicular to the transverse direction T and lies in the propagation plane AA.

[0061] The distances of the first entry direction E1, the second entry direction E2 and the third entry direction E3 to one another along the transverse direction T, the first diffraction unit 20 and the distance of the second diffraction unit 21 to the first diffraction unit 20 are coordinated with one another in such a way that the diffracted light beams 11b, 12b, 13b are focused in a focal point located in the second diffraction unit 21.

[0062] A third wafer die 51 with a focusing unit 50 is arranged on the first wafer die 22. The focusing unit 50 is designed to focus light beams 11c, 12c, 13c diffracted by the second diffraction unit 21 and propagating along the exit direction A in the direction of the microscanner 30. As a result, the light beams 11c, 12c, 13c can be deflected by the microscanner 30 such that a sharp image is projected onto the observation field.

[0063] The microscanner 30, which is designed as a micro-electromechanical system (MEMS), is arranged on the third wafer die 51 and has a mirror 31 which can be aligned along a rotation axis and which is designed to controllably deflect light beams 11c, 12c, 13c diffracted by the second diffraction unit 21 and focused by the focusing unit 50.

[0064] As previously described, the light projector device 1 is configured such that the entire beam path of the light beams 11a, 11b, 11c, 12a, 12b, 12c, 13a, 13b, 13c from the light source 10 to the microscanner 30 lies entirely within the propagation plane AA. This enables the particularly simple and compact design of the light projector device 1 shown, which is suitable for wafer-to-wafer bonding.

[0065] The wafer-to-wafer bonding of the first wafer die 22 to the second wafer die 43 and the wafer-to-wafer bonding of the third wafer die 51 to the first wafer die 22 involve the application of highly parallelized wafer-based processes. Initially, a plurality of first wafer dies 22 are each formed at a location in a regular grid arrangement of a first wafer, a plurality of second wafer dies 43 are each formed at a location in a regular grid arrangement of a second wafer, and a plurality of third wafer dies 51 are each formed at a location in a regular grid arrangement of a third wafer. The regular grid arrangements are configured such that, during the wafer-to-wafer bonding, a first wafer die 22, a second wafer die 43, and a third wafer die 51 are each assigned to one another (see also Fig. 3a). Following wafer-to-wafer bonding, wafer dies are separated (see also Fig. 3b).

[0066] A difference between the shown embodiments of the light projector devices 1 in Fig. 1 and Fig. 2 is that in Fig. 1 the first diffraction unit 20 is designed as a volume holographic grating with grating constant d1 and the second diffraction unit 21 is designed as a volume holographic grating with grating constant d2, so that the light beams 11a, 12a, 13a generated by the light source 10 are diffracted by the first diffraction unit 20 by a diffraction angle φ1 along the transverse direction T as a function of the wavelength λ of the light beam 11a, 12a, 13a according to the equation λ = d1 sin(φ1) and the light beams 11b, 12b, 13a diffracted by the first diffraction unit 20 are diffracted by a diffraction angle φ2 = -φ1 in the opposite direction to the first diffraction unit 20 along the transverse direction T.

[0067] In Fig. 2, the first diffraction unit 20 and the second diffraction unit 21 each comprise an optical metamaterial having a nanostructure such that the optical metamaterial has a negative diffraction index only for the color red. As a result, the first diffraction unit 20 and the second diffraction unit 21 are each configured such that the first light beam 11a of the color blue is diffracted in the opposite direction along the transverse direction T as the third light beam 11a of the color red.

[0068] Fig. 3a shows a perspective view of an arrangement of parts of a light projector device 1 after method steps A), B), C), D), and E) of a method for producing a light projector device 1 have been carried out.

[0069] With method step A), the first wafer W1 was provided, in which, for each location of a regular grid arrangement R1, a first diffraction unit 20 is formed in a front side VS of the first wafer W1 and a second diffraction unit 21 is formed in a rear side RS of the first wafer W1 opposite the front side VS of the first wafer W1 by nanostructuring.

[0070] Furthermore, with method step B), the second wafer W2 was provided, in which a beam shaping unit 40 for the complete or incomplete collimation of light beams is formed for each location of a regular grid arrangement R2.

[0071] Furthermore, with method step C), the third wafer W3 was provided, in which a focusing unit 50 is formed for each location of a regular grid arrangement R3.

[0072] Furthermore, in method step D), the first wafer W1 was connected wafer-to-wafer to the second wafer W2, so that a first diffraction unit 20 formed in the first wafer W1 is assigned to a beam shaping unit 40 formed on the second wafer W2.

[0073] Furthermore, with method step E), the third wafer W3 was connected wafer-to-wafer to the second wafer W2, so that a focusing unit 50 formed on the third wafer W3 is assigned to a second diffraction unit 21 formed in the first wafer W1.

[0074] The wafer-to-wafer bonding was achieved using bonding materials that were applied in a structured manner to the wafers W1, W2, W3. The assignment of the optical components, i.e., the first diffraction units 20 and second diffraction units 21, the beam-shaping units 40, and the focusing units 50, which are each located at positions in the regular grid arrangements R1, R2, R3 of the corresponding wafers W1, W2, W3, was achieved by aligning the wafers W1, W2, W3 to one another using microscopes and traversing devices on which the wafers W1, W2, W3 are arranged, thereby achieving an assignment accuracy in the micrometer range.

[0075] The wafers W1, W2, W3 connected by wafer-to-wafer bonding thus have a plurality of wafer dies D, in particular one wafer die D per location of the regular grid arrangements R1, R2, R3.

[0076] Fig. Figure 3b shows a perspective view of an arrangement of parts of a light projector device 1 after method steps A), B), C), D), E) (see Fig. 3a), and H) of a method for producing a light projector device 1.

[0077] With process step H), wafer dies D were produced from the wafer-to-wafer bonded wafers W1, W2, W3 (in Fig. 3a) is singulated, whereby a wafer die D is Fig. 3b is shown.

[0078] The separation of the wafer dies D by mechanical sawing of the wafer-to-wafer connected wafers W1, W2, W3 (in Fig. 3a) in such a way that one place of the regular grid arrangements R1, R2, R3 (in Fig. 3a) the wafers W1, W2, W3 (in Fig. 3a) and from other locations of the regular grid arrangements R1, R2, R3 (in Fig. 3a) the wafers W1, W2, W3 (in Fig. 3a) were separated.

[0079] The wafer die D shown thus represents a composite optical device comprising a first diffraction unit 20, a second diffraction unit 21, a beam shaping unit 40 and a focusing unit 50.

[0080] Fig. Figure 3c shows a perspective view of an arrangement of parts of a light projector device 1 after method steps A), B), C), D), E), H) (see Fig. 3b), and F) of a method for manufacturing a light projector device.

[0081] In method step F), a light source 10 was provided and arranged on the beam-shaping unit 40. The positioning of the light source 10 was carried out using a position measurement, i.e., passively.

[0082] Following method step F), method step G) of providing a microscanner with a mirror that can be aligned along at least one rotation axis and arranging the microscanner on the focusing unit takes place, wherein method step G) in Fig. 3c has not yet taken place.

[0083] Fig. Fig. 4 shows a perspective view of an arrangement of parts of a light projector device 1 after method steps A), B), C), D), E) (see Fig. 3a), F), and G) of a method for producing a light projector device 1.

[0084] With method step A), the first wafer W1 was provided, in which, for each location of a regular grid arrangement R1, a first diffraction unit 20 is formed in a front side VS of the first wafer W1 and a second diffraction unit 21 is formed in a rear side RS of the first wafer W1 opposite the front side VS of the first wafer W1 by nanostructuring.

[0085] Furthermore, with method step B), the second wafer W2 was provided, in which a beam shaping unit 40 for the complete or incomplete collimation of light beams is formed for each location of a regular grid arrangement R2.

[0086] Furthermore, with method step C), the third wafer W3 was provided, in which a focusing unit 50 is formed for each location of a regular grid arrangement R3.

[0087] Furthermore, with method step F1), the fourth wafer W4 was provided, in which a light source 10 is formed for each location of a regular grid arrangement R4.

[0088] Furthermore, with method step G1), the fifth wafer W5 was provided, in which a microscanner 30 is formed for each location of a regular grid arrangement R5.

[0089] Furthermore, in method step D), the first wafer W1 was connected wafer-to-wafer to the second wafer W2, so that a first diffraction unit 20 formed in the first wafer W1 is assigned to a beam shaping unit 40 formed on the second wafer W2.

[0090] Furthermore, with method step E), the third wafer W3 was connected wafer-to-wafer to the second wafer W2, so that a focusing unit 50 formed on the third wafer W3 is assigned to a second diffraction unit 21 formed in the first wafer W1.

[0091] Furthermore, with method step F2), the fourth wafer W4 was connected wafer-to-wafer to the second wafer W2, so that a light source 10 formed on the fourth wafer W4 is assigned to a beam shaping unit 40 formed in the second wafer W2.

[0092] Furthermore, with method step G2), the fifth wafer W5 was connected wafer-to-wafer to the third wafer W3, so that a microscanner 30 formed on the fifth wafer W5 is assigned to a focusing unit 50 formed in the third wafer W3.

[0093] The wafer-to-wafer bonding was carried out using bonding materials that were applied in a structured manner to the wafers W1, W2, W3, W4, W5. The assignment of the optical components, i.e. the first diffraction units 20 and second diffraction units 21, the beam shaping units 40, the focusing units 50, the light source 10 and the microscanner 30, which are each present at locations of the regular grid arrangements R1, R2, R3, R4, R5 of the corresponding wafers W1, W2, W3, W4, W5, was carried out by aligning the wafers W1, W2, W3, W4, W5 to one another using microscopes and traversing devices on which the wafers W1, W2, W3, W4, W5 are arranged, whereby an accuracy of the assignment in the micrometer range was achieved.

[0094] The method step H) of singulating wafer dies from the wafer-to-wafer bonded wafers W1, W2, W3, W4, W5 has not yet been carried out, but then takes place after the method step G2, so that a wafer die represents a composite optical device which comprises a first diffraction unit 20, a second diffraction unit 21, a beam shaping unit 40, a focusing unit 50, a light source 10 and a microscanner 30.

[0095] Fig. 5a - 5d show schematic representations of the process steps of the method for producing a light projector device, which in Fig. 3a - 3c respectively Fig. 4 have been completed and have not yet been completed. Solid lines indicate procedural steps that have been completed, and dashed lines indicate procedural steps that have not yet been completed.

Claims

[1] Light projector device (1) for projecting light rays onto an observation field, comprising: - a light source (10) which is designed to generate a first light beam (11a) of a first color propagating along a first entry direction (E1) and a second light beam (12a) of a second color propagating along a second entry direction (E2) and spaced apart from the first light beam (11a) along a transverse direction (T), - a first diffraction unit (20) which is designed to diffract light beams (11a, 12a) generated by the light source (10) along the transverse direction (T) in a wavelength-dependent manner, so that light beams (11b, 12b) diffracted by the first diffraction unit (20) propagate in a propagation plane (AA), - a second diffraction unit (21) which is designed to diffract light beams (11b, 12b) diffracted by the first diffraction unit (20) along the transverse direction (T) in a wavelength-dependent manner such that the light beams (11b, 12b) diffracted by the first diffraction unit (20) propagate as light beams (11c, 12c) at least partially superimposed in the transverse direction (T) along an exit direction (A), and - a microscanner (30) with a mirror (31) which can be aligned along at least one rotation axis and which is designed to controllably deflect light beams (11c, 12c) diffracted by the second diffraction unit (21), characterized by , that - the first diffraction unit (20) is formed in a front side of a first wafer die (22) and the second diffraction unit (21) is formed in a back side of the first wafer die (22) opposite the front side of the first wafer die (22). [2] The light projector device (1) according to claim 1, wherein the light source (10) is configured such that the light beams (11a, 12a) generated by the light source (10) propagate in the propagation plane (AA), and wherein the second diffraction unit (21) is configured such that the light beams (11c, 12c) diffracted by the second diffraction unit (21) propagate in the propagation plane (AA). [3] Light projector device (1) according to one of the preceding claims, wherein the second diffraction unit (21) is designed such that the exit direction (A) is perpendicular to the transverse direction (T). [4] Light projector device (1) according to one of the preceding claims, wherein the second diffraction unit (21) is designed to diffract light beams (11b, 12b) diffracted by the first diffraction unit (20) along the transverse direction (T) in a wavelength-dependent manner such that the light beams (11b, 12b) diffracted by the first diffraction unit (20) propagate as light beams (11c, 12c) superimposed in the transverse direction (T) in a range between 80% and 100% of their cross-sectional area, in particular in a range between 90% and 95% of their cross-sectional area, along the exit direction (A). [5] Light projector device (1) according to one of the preceding claims, wherein the light source (10) is designed to generate a third light beam (13a) of a third color propagating along a third entrance direction (E3) and spaced apart from the first light beam (11a) and second light beam (12a) along the transverse direction (T). [6] Light projector device (1) according to one of the preceding claims, wherein the first diffraction unit (20) and / or the second diffraction unit (21) are each designed such that at least two of the light beams (11a, 12a, 13a) generated by the light source (10) are diffracted in opposite directions along the transverse direction (T). [7] Light projector device (1) according to one of the preceding claims, comprising a beam shaping unit (40) arranged between the light source (10) and the first diffraction unit (20), which is designed to completely collimate or not completely collimate light beams (11a, 12a, 13a) propagating from the light source (10) in the direction of the first diffraction unit (20) in such a way that a virtual or real focal point is created along the optical axis. [8] Light projector device (1) according to claim 1, wherein the beam shaping unit (40) comprises cylindrical lenses (41), in particular pairs of plano-cylindrical lenses (41a, 41b) rotated by 90° relative to one another about the optical axis, and / or spherical, and / or aspherical, and / or acylindrical lenses (42). [9] Light projector device (1) according to one of the preceding claims, comprising a focusing unit (50) arranged between the second diffraction unit (21) and the microscanner (30), which is designed to focus light beams (11c, 12c, 13c) diffracted by the second diffraction unit (21) and propagating along the exit direction (A) in the direction of the microscanner (30). [10] The light projector device (1) according to claim 1 or 7 and claim 8, wherein the beam shaping unit (40) is formed in a second wafer die (43), and wherein the focusing unit (50) is formed in a third wafer die (51). [11] The light projector device (1) according to claim 9, wherein the first wafer die (22) is arranged on the second wafer die (43) by wafer-to-wafer bonding, and wherein the third wafer die (51) is arranged on the first wafer die (22) by wafer-to-wafer bonding. [12] Light projector device (1) according to one of the preceding claims, wherein the microscanner (30) is designed as a micro-electromechanical system (MEMS). [13] Light projector device (1) according to one of the preceding claims, wherein the light source (10) comprises a semiconductor laser unit (14, 15, 16), in particular designed as a VCSEL, for generating a light beam (11a, 12a, 13a) of a specific color. [14] Method for producing a light projector device (1) comprising the method steps: A) Providing a first wafer (W1) in which, for each location of a regular grid arrangement (R1), a first diffraction unit (20) is formed in a front side (VS) of the first wafer (W1) and a second diffraction unit (21) is formed in a rear side (RS) of the first wafer (W1) opposite the front side (VS) of the first wafer (20); B) providing a second wafer (W2) in which a beam-forming unit (40) for the complete or incomplete collimation of light beams is formed for each location of a regular grid arrangement (R2); C) providing a third wafer (W3) in which a focusing unit (50) is formed for each location of a regular grid arrangement (R3); D) wafer-to-wafer bonding of the first wafer (W1) to the second wafer (W2) such that a first diffraction unit (20) formed in the first wafer (W1) is assigned to a beam shaping unit (40) formed on the second wafer (W2); E) wafer-to-wafer bonding of the third wafer (W3) on the second wafer (W2) such that a focusing unit (50) formed on the third wafer (W3) is assigned to a second diffraction unit (21) formed in the first wafer (W1); F) providing one light source (10) per beam-shaping unit (40) and arranging one light source (10) on each beam-shaping unit (40); G) Providing one microscanner (30) each with a mirror alignable along at least one rotation axis per focusing unit (50) and arranging one microscanner (30) each on a focusing unit (50); and H) Singulating wafer dies (D) from the wafer-to-wafer bonded wafers (W1, W2, W3, W4, W5). [15] Method according to claim 14, wherein in method step F) the provision of one light source (10) per beam-shaping unit (40) and the arrangement of one light source (10) on each beam-shaping unit (40) comprises: F1) providing a fourth wafer (W4) in which a light source (10) is formed for each location of a regular grid arrangement (R4); and F2) wafer-to-wafer bonding of the fourth wafer (W4) on the second wafer (W2), such that a respective light source (10) formed on the fourth wafer (W4) is assigned to a beam-shaping unit (40) formed in the second wafer (W2). [16] Method according to claim 14 or 15, wherein in method step G) the provision of one microscanner (30) with a mirror alignable along at least one rotation axis per focusing unit (50) and the arrangement of one microscanner (30) on a focusing unit (50) comprises G1) providing a fifth wafer (W5) in which a microscanner (30) is formed for each location of a regular grid arrangement (R5); and G2) Wafer-to-wafer bonding of the fifth wafer (W5) on the third wafer (W3), such that a microscanner (30) formed on the fifth wafer (W5) is assigned to a focusing unit (50) formed in the third wafer (W3).

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