CN116670952A - Laser device and projector with same - Google Patents

Abstract

A laser device comprising a plurality of laser diodes, each laser diode emitting a beam having a fast axis and a slow axis and a beam direction; and one or more optical components configured to modify the divergence of the light beam in the fast axis plane and/or in the slow axis plane such that the light beam has the same focal plane in the fast axis plane and in the slow axis plane.

Description

Laser device and projector with same

This patent application claims priority from U.S. patent application Ser. No. 63/123,518, U.S. patent application Ser. No. 63/160,820, U.S. patent application Ser. No. 63/210,554, and U.S. patent application Ser. No. 17/444,082, the disclosures of which are incorporated herein by reference.

Technical Field

The present disclosure relates to a laser device, and in particular, to a system and method for matching fast axis and slow axis fields of view of a laser device. Furthermore, the present disclosure relates to a projector having a laser device. The laser device is used as a light source in a projector, which may be an image projector, for example for near-eye displays such as Augmented Reality (AR) and Virtual Reality (VR) applications.

Disclosure of Invention

According to at least one embodiment, the laser device comprises at least one group of at least one laser diode. The group of at least one laser diode may also be denoted as laser diode group in the following. Preferably, the at least one laser diode group comprises at least two laser diodes. Preferably, the laser diode group comprises or is a group of two or more laser diodes emitting light with the same or substantially the same color. Accordingly, the set of laser diodes may be defined by an emission color, which may be defined by the sum of the light emitted by all the laser diodes of the set of laser diodes. "same or substantially the same color" may for example mean that a human observer perceiving the respective light emitted from each of the laser diodes of the set of laser diodes has the impression that all laser diodes of the set of laser diodes emit light with the same or substantially the same color. This may for example mean that the laser diodes of the laser diode group emit light with the same or substantially the same color location (english). According to some embodiments, this may mean that the laser diodes of the laser diode group emit light with the same or similar or substantially similar spectral components.

According to a further embodiment, the projector comprises a laser device as described previously. Features and embodiments described below with respect to the laser device are equally applicable to projectors.

According to a further embodiment, the laser device comprises at least two laser diode groups, wherein each laser diode group comprises at least one laser diode, or preferably at least two laser diodes. Accordingly, the laser device may comprise a first set of laser diodes emitting a first color and a second set of laser diodes emitting a second color. The first color and the second color are preferably different from each other. In particular, this may mean that the first color and the second color are perceived by a human observer as different colors. In addition, the laser device may include a first set of laser diodes emitting a first color, a second set of laser diodes emitting a second color, and a third set of laser diodes emitting a third color. The first color and the second color and the third color are preferably different from each other. For example, the laser device may include a first set of laser diodes that emit light with a red color, a second set of laser diodes that emit light with a green color, and a third set of laser diodes that emit light with a blue color. Accordingly, the laser device may be a so-called RGB laser device. Each set of laser diodes may form a so-called color channel of the laser device and may comprise one or more laser diodes.

When features and/or attributes of a "set of laser diodes" or a "color channel" are described throughout the specification, these features and/or attributes apply to at least one set of laser diodes/color channels, and preferably to all sets of laser diodes/color channels of a laser device.

According to a further embodiment, the laser diode is attached to at least one submount. Correspondingly, the laser device may comprise at least one submount, wherein at least one or more laser diodes are attached to the submount. At least one submount may have a mounting surface on which at least one laser diode is mounted. For example, each of the plurality of laser diodes may be arranged on a respective allocated submount. Furthermore, it is possible that at least one submount has a first mounting surface, wherein at least one laser diode is arranged on the first mounting surface, and a second mounting surface opposite the first mounting surface, wherein at least one other laser diode is arranged on the second mounting surface. Further, at least one of the bases may comprise one or more conductors, such as conductors formed by connection pads. Furthermore, the laser device may comprise a plurality of such bases, wherein one or more laser diodes are attached to each base, respectively. Accordingly, the laser device may be constructed using one or more so-called Chip On Submount Assemblies (COSAs), where one or more laser diodes are placed on a submount, and the laser device may include one or more submounts forming an array.

Preferably, the laser diode may be part of a laser package. The laser device may include a laser package, or may be formed from a laser package. The laser package may comprise a base, which may be a carrier for the components of the laser package, and on which the laser diode is arranged.

According to a further embodiment, at least one abutment is arranged on the base. The base may have a base surface on which the at least one abutment is disposed. Here and hereinafter, the base surface may define a plane denoted as horizontal. In other words, the base surface defines a horizontal plane with respect to the laser device, and in particular with respect to the laser package. However, in a projector, the laser device, and in particular the laser package, may be arranged in any desired orientation relative to other components of the projector, such that the horizontal base surface may be arranged in a position deviating from a horizontal plane, e.g. defined by gravity.

According to a further embodiment, at least one abutment is arranged vertically on the base. This may mean that the mounting surface of the abutment or the first and second mounting surfaces of the abutment as described above are not parallel to the base surface, but are arranged vertically with respect to the horizontal base surface. In other words, the mounting surface(s) of at least one abutment are arranged perpendicular or at least substantially perpendicular to the base surface. Thus, in a vertical arrangement of the submount on the submount surface of the submount, the laser diode on the mounting surface may be positioned immediately adjacent the submount in a direction parallel or at least substantially parallel to the submount surface and thus parallel or at least substantially parallel to the horizontal plane of the laser device.

According to a further embodiment, the laser device comprises a plurality of laser diodes as explained before, wherein each laser diode emits a light beam having a fast axis and a slow axis and a beam direction during operation. The laser device preferably further comprises one or more optical components configured to modify the divergence of the light beam in the fast axis plane and/or in the slow axis plane. It is particularly preferred that the divergence of the light beam is modified such that the light beam has the same focal plane in the fast axis plane and in the slow axis plane.

According to a further embodiment, the one or more optical components comprise at least one lens or lens array. Preferably, the one or more optical components comprise at least two lenses. It is particularly preferred that each of the two lenses affects beam divergence in only one plane selected from the fast axis plane and the slow axis plane. For example, one of the two lenses affects beam divergence only in the fast axis plane, while the other of the two lenses affects beam divergence only in the slow axis plane. Alternatively, each of the two lenses affects beam divergence in only the fast axis plane or only the slow axis plane. The optical component that affects beam divergence in only one plane selected from the fast axis plane and the slow axis plane may preferably be a single cylindrical lens or a lens array comprising a plurality of cylindrical microlenses. Particularly preferably, in case the optical component is formed by a single lens, the lens is assigned to at least two laser diodes or more laser diodes or even all laser diodes. Here and hereinafter, if the light beam emitted by the laser diode is affected and modified by a lens, the lens is assigned to the laser diode.

According to a further embodiment, the one or more optical components comprise at least one converging optical component affecting beam divergence only in the fast axis plane.

According to a further embodiment, the one or more optical components comprise a converging lens or a converging lens array assigned to at least two laser diodes.

According to a further embodiment, the one or more optical components comprise at least one diverging optical component affecting beam divergence only in the slow axis plane.

According to a further embodiment, the one or more optical components comprise a diverging lens or a diverging lens array assigned to at least two laser diodes.

According to a further embodiment, the one or more optical components comprise two cylindrical lenses, wherein at least one of the cylindrical lenses is assigned to at least two laser diodes. In particular, one of the two cylindrical lenses is arranged downstream of the other of the two cylindrical lenses. In a preferred embodiment, the lenses assigned to the at least two laser diodes are single cylindrical lenses assigned to all laser diodes of the laser device. The other of the two cylindrical lenses may also be a single lens or an array of lenses.

According to a further embodiment, the lens array comprises a plurality of converging cylindrical microlenses arranged next to each other along a direction in the fast axis plane.

According to a further embodiment, the lens array comprises a plurality of diverging cylindrical microlenses arranged next to each other along a direction in the slow axis plane.

According to a further embodiment, each of the microlenses is assigned to at least one laser diode, wherein each of the microlenses has a cylindrical axis perpendicular to the fast axis and parallel to the slow axis.

According to a further embodiment, at the output surface of the lens array, the light beam of at least one laser diode is tilted in the fast axis plane with respect to the light beam of another one of the laser diodes at the output surface of the lens array and/or with respect to the optical axis of the assigned microlens.

According to a further embodiment, at least some of the laser diodes are tilted with respect to each other in the fast axis plane.

According to a further embodiment, the at least one laser diode is arranged eccentrically in the fast axis plane with respect to the optical axis of the assigned microlens.

According to a further embodiment, at least some of the laser diodes are tilted with respect to each other in the slow axis plane.

According to a further embodiment, the one or more optical components comprise diverging optical components that affect beam divergence only in the fast axis plane.

According to a further embodiment, the one or more optical components comprise cylindrical lenses assigned to all laser diodes, for example diverging cylindrical lenses in combination with the converging microlenses mentioned above or converging cylindrical lenses in combination with the diverging microlenses mentioned above.

According to a further embodiment, one or more of the plurality of laser diodes are tilted at an angle to the symmetry axis of the one or more optical components.

According to a further embodiment, the laser device further comprises a prism having two reflective sides onto which the laser diode emits light, wherein on each side there are a plurality of facets inclined with respect to each other. Preferably, the prism is mounted on the base of the laser package.

According to a further embodiment, in the projector, the light beam has an aperture in the fast axis plane and an aperture in the slow axis plane, the two apertures overlapping.

Drawings

Further features, advantages and convenience of the laser device will become apparent from the following description of exemplary embodiments and features in conjunction with the accompanying drawings. The embodiments shown in the figures, and in particular the features described accordingly, are not limited to the respective combinations of features shown in the figures. Rather, the illustrated embodiments and individual features can be combined with one another even if not all combinations are directly described.

Fig. 1 illustrates a projector according to various embodiments.

Fig. 2 illustrates an example of side-by-side placement of laser diodes in a laser device according to a further embodiment.

Fig. 3 illustrates beam divergence of a laser device according to a further embodiment.

Fig. 4 illustrates an example of modifying the fast and slow axes of a six laser device according to a further embodiment.

Fig. 5 illustrates a system and method for modifying the field of view of both the fast and slow axes of a laser device according to a further embodiment.

Fig. 6A and 6B illustrate further examples of using optics to correct for different divergences along the fast and slow axes of a laser device, in accordance with various embodiments.

Fig. 7 illustrates an example of implementing laser beam tilting in a laser device according to a further embodiment.

Fig. 8 illustrates a further example of using optics to correct for different divergences along the fast and slow axes of a laser device, in accordance with various embodiments.

Fig. 9 illustrates a further example of using optics to correct for different divergences along the fast and slow axes of a laser device, in accordance with various embodiments.

Fig. 10 illustrates a further example of a field of view for modifying both the fast and slow axes of a laser device according to various embodiments.

Fig. 11 illustrates a laser device according to a further embodiment.

These and other features of the present embodiments will be better understood upon reading the following detailed description in conjunction with the drawings described herein. The figures are not intended to be drawn to scale. For purposes of clarity, not every component may be labeled in every drawing.

Detailed Description

Hereinafter, various embodiments of a laser device and a projector are described, wherein the laser device may be used as a light source in the projector. The projector may generally be a display system and in particular a near-eye display system based on scanning the laser beams side by side. For example, a laser device according to the depicted embodiment may comprise three laser diode groups, each having two laser diodes formed by edge emitting diode lasers, respectively, even if not always shown directly. Thus, for example, six laser diodes may be used in a laser device according to the illustrated embodiment. However, other numbers of laser diode groups and laser diodes per laser diode group are also possible.

Hereinafter, the laser diode is denoted by reference numeral 10, to which further information, such as "a", "B", "R", "G" or "B", may be added, for example, depending on the depicted view. In this regard, for example, a plurality of laser diodes may be represented in one figure as "laser diode 10a" or "laser diode 10B" for indicating arrangement properties, while the same plurality of laser diodes (e.g., laser diode(s) 10a shown in one figure) may be represented in another figure as "laser diode 10R", "laser diode 10G", and "laser diode 10B" for indicating color properties of those laser diodes.

Fig. 1 shows an exemplary embodiment of a projector in a projection application in view 15. The laser diode of the laser device (indicated by emission plane EP) emits a diverging light beam through the window 12 of the laser device, wherein the light beam is then reflected by the reflector 14. The lens 16 focuses the reflected beam onto two orthogonal scan mirrors 18a, 18b. Alternatively, a single dual axis scanning mirror may be used in the embodiments herein and below. In this case, a single mirror replaces the two scan mirrors 18a and 18b shown in FIG. 1. In addition, the reflector 14 may be omitted so that the laser diode may emit the generated light directly onto the lens 16. The focused beam angle is modified by a field lens 20 before being focused onto a Micro Lens Array (MLA) 22. The MLA22 thus forms a focal plane. The more divergent light beam emerging from the MLA22 is collimated by optics 24 forming relay optics before exiting the projector and, for example, enters a waveguide (not shown) that projects an image onto the viewer's eye.

There is an optical path from the laser diode represented by the emission plane EP to the MLA 22. The limiting aperture in this optical path is the scan mirror, and in particular the resonant scan mirror 18a as the smallest optical component. Thus, the superposition of all beams from the laser diode should have a minimum beam size at the location of at least one of the mirrors 18a, 18b, should illuminate the mirrors 18a, 18b with a minimum "spill over" (resulting in power loss), and should be focused on the MLA22, i.e., the focal plane. The minimum beam size of the beam emitted by the laser device (including the beam of all operating laser diodes) may also be denoted as the minimum aperture, or simply aperture hereinafter. As mentioned above, all of the features and embodiments previously and hereinafter explained are applicable also in the case where the scan mirrors 18a and 18b are replaced by a single biaxial scan mirror.

Fig. 2 illustrates an exemplary embodiment of a laser device comprising a laser package comprising three laser diode groups, wherein each of the laser diode groups comprises two laser diodes, in a side view 25 and in a front view 27. For example, the laser package of the laser device also includes a base 11, a prism 28, and a window 12. The layout shown in fig. 2 is only an example, and other architectures are possible for the placement and number of laser diodes and for the components of the laser package.

The laser diodes are placed side by side in a laser package on the base 11. The laser diodes form two groups of three RGB lasers on opposite reflective sides of a prism 28 on the base 11. When in operation, each of the laser diodes emits a light beam onto a reflective side of a prism, which reflects the light beam toward the window 12. In side view 25, only two laser diodes 10a, 10b are visible, wherein the appendices "a" and "b" denote the sides of the laser diodes with respect to the prism 28 on the base 11. The three laser diodes 10a on the left hand side of the prism 28 emit red, green and blue light, respectively, and form an RGB structure. The three laser diodes 10b on the right hand side of the prism 28 form another RGB structure. One of the RGB structures can be seen in the front view 27. In particular, the laser diodes of the illustrated RGB structure are denoted as "10R", "10G" and "10B". Each pairing of two laser diodes 10a, 10b emitting the same color forms a group of laser diodes, also called a color channel. Furthermore, each of the depicted laser diodes 10a, 10b represents an RGB group comprising a red emitting laser diode, a green emitting laser diode and a blue emitting laser diode. Therefore, hereinafter, it will also be referred to as "laser diode group 10a" and "laser diode group 10b".

As can be seen in the front view 27, each of the laser diodes 10R, 10G, 10B is placed on the base 26. The submount 26 may preferably be placed vertically on the submount 11 in the laser package. As explained above, this means that the base 11 has a base surface on which the base table is arranged and which defines the level of the laser package and thus the level of the laser device. The laser diode is arranged on a mounting surface of the submount, wherein the mounting surface of the submount is not parallel to the submount surface. Preferably, the mounting surface is perpendicular to the base surface. Light emitted from the laser diode is reflected perpendicularly by the prism 28 and passes through the window 12 which has been indicated in fig. 1. In other words, light emitted from the laser diode and thus from the laser package is emitted from the window 12 onto further optical components described in connection with fig. 1.

The arrangement of six laser diodes (three on each side of the prism 28) produces a six-dot pattern 32 in which each dot must be as clear as possible to achieve a clearly scanned image. Each point is marked with reference number 200, followed by an appendage according to the respective color (R, G or B) and the respective RGB group (a or B). Pattern 36 illustrates a different pattern that may be created when two laser diodes are placed on each submount 26. A single RGB group is also possible, wherein only three or four laser diodes (not shown in fig. 2) are present. Hereinafter, for clarity, the description of the laser device and projector will focus on a six laser structure as shown in fig. 25 and 27 and in pattern 32.

Fig. 3 illustrates beam divergence and a modification of beam divergence of a laser device according to various embodiments. The schematic 39 shows a laser diode 10 which typically transmits an asymmetric beam which diverges rapidly in one axis F, the so-called fast axis, and diverges slowly in the other axis S, the so-called slow axis. This asymmetric beam divergence results in a significant power loss because not all light can be collected by the projector optics.

Schematic diagram 41 illustrates a method for converting an elliptical beam into a circular beam using two cylindrical lenses 44 and 46. Schematic 48 shows the same structure but with different specifications: the solid line represents the fast axis ray, i.e. the beam in the fast axis plane, while the dashed line represents the view from the side visible from the slow axis, i.e. the beam in the slow axis plane.

Lenses 44, 46 are depicted as double headed arrows, which are optically effective only in this view. Thus, the lens 44 that affects the emitted light only with respect to the fast axis is shown only in the fast axis plan view, while the lens 46 that affects the emitted light only with respect to the slow axis is shown only in the slow axis plan view. In the following figures, the same specifications depicting cylindrical lenses are used.

Schematic 50 shows an alternative configuration in which both cylindrical lenses are active in the fast axis plane, but one is a converging lens 52 and the other is a diverging lens 54. This modifies the fast axis to overlap the slow axis (which is unchanged) in terms of angle and origin.

Here, for clarity, most of the structures depicted are equivalent to the structures according to the schematic diagram 50 in which only the fast axis is manipulated. However, a similar optical arrangement may include manipulation of two axes as depicted in schematic diagrams 41 and 48, wherein the axis of the second lens is parallel to the slow axis.

Fig. 4 illustrates an exemplary embodiment for modifying the fast axis and the slow axis of a laser device, i.e. for modifying the light beam emitted by a laser diode in the fast axis plane and in the slow axis plane, wherein the laser device comprises six laser diodes. Schematic 55 schematically illustrates how the array of six laser diodes whose fast axis planes overlap shown in fig. 2 can be modified based on the structure shown in schematic 50 to obtain a circular beam. Obviously, the distance between R, G and the B laser diode should be large enough so that their beams do not overlap when refracted by the second lens 54. However, the two laser diode groups 10a and 10b may be very close. Thus, the prism 28 may be narrow.

Schematic 56 shows the same six laser device with both the fast and slow axes modified as implemented in the structure shown in schematic 41 and 48 of fig. 3. The use of a single cylindrical lens for the fast axis allows the distance between R, G and B laser diode to be closer. However, the presence of the lens 46 along the slow axis means that the laser diode groups 10a and 10b must be spaced farther apart. The light beam of the laser diode has an approximately gaussian angular distribution. Thus, implementing lenses adjacent to each other will result in one beam leaking to the lens adjacent to the laser diode, resulting in crosstalk and degradation of the projected image. Thus, when attempting the depicted beam modification, the laser diode must be placed farther apart.

Fig. 5 illustrates a system and method for modifying the field of view of both the fast and slow axes of a laser device, according to various embodiments. The schematic diagram 58 in fig. 5 shows a set of parallel divergent beams 60 that are refracted by an array of lenses 62 to produce a set of parallel less divergent beams 64. The schematic 65 shows an arrangement that produces the same optical result as the arrangement of the schematic 58, except that the set of divergent light beams 66 enters a single lens 68, the optical power of this lens 68 being in the same plane as the distribution of the light beams 66 emitted by at least two laser diodes and preferably more than two or even all laser diodes of the laser device. In other words, the lens 68 is assigned to at least two laser diodes and preferably to more than two or even all laser diodes of the laser device. The optical power of the lens 68 being in the same plane as the distribution of the two or more light beams means that the two or more light beams are arranged next to each other in the direction in the first plane and the curvature of the lens is in the second plane, which is the same as the distribution of the light beams, as is easily seen in the schematic diagram 65. In the case where the cylindrical lens 68 has a cylindrical axis, the first plane (i.e., the plane in which the directions in which the light beams are arranged immediately adjacent to each other) is perpendicular to the cylindrical axis of the cylindrical lens 68.

In order for the set of parallel less divergent beams 64 exiting from a single lens 68 to be the same as the set of beams exiting from the array of lenses 62 shown in schematic diagram 58, beams 66 enter a single lens 68 at an oblique angle. Although converging lenses 62, 68 are shown in fig. 5, corresponding effects may be obtained in the case of diverging lenses.

Fig. 6A illustrates an example of using optics to correct for different divergences along the fast and slow axes of a laser device in a projector, in accordance with various embodiments. Schematic 70 shows the corrected fast axis orientation. The RBG laser diode 10 of the laser device emits light onto converging optics, which reduces fast axis divergence. In the illustrated embodiment, the converging optical components are formed by a lens array 72. The lens array 72 comprises converging cylindrical microlenses arranged next to each other in the plane of the fast axis, wherein the effect of the microlenses is equivalent to the function of the lenses 52 in fig. 3. Thus, the cylindrical microlenses each have a cylindrical axis perpendicular to the fast axis of the light emitted by the laser diode and parallel to its slow axis. Each of the microlenses is assigned to a laser diode. The lens array 72 may be more compact than a single lens, allowing for a more compact design of the laser device.

Preferably, the lens array 72 comprising microlenses is part of the laser device and may be arranged, for example, below the window 12 or on the window 12. Alternatively, the lens array 72 may form the window 12. It is also possible that the lens array 72 is part of a projector and is arranged downstream of the laser device with respect to the beam direction of the light emitted by the laser device.

Downstream of the converging optical component (i.e. the lens array 72 in the embodiment shown) other optical components assigned to all laser diodes are arranged. In the illustrated embodiment, the other optical components are formed by a single diverging cylindrical lens 74. The light beam leaving the lens array 72 enters a single diverging cylindrical lens 74 having a cylindrical axis that is also perpendicular to the fast axis of the light emitted by the laser diode and parallel to its slow axis. A single diverging cylindrical lens 74 replaces the set of diverging lenses 54 in fig. 3. The single lens 74 may be more compact than a single lens, allowing for a more compact design of the laser device.

Preferably, the lens 74 may also be part of the laser device and may be arranged, for example, below the window 12 or on the window 12. The lens array 72 and the individual lenses 74 may be placed on the same side of the window 12, or on different sides of the window, with respect to the beam direction of the light emitted by the laser device. Alternatively, the lens array 72 may form the window 12. It is also possible that the lens 74 is part of the projector and is arranged downstream of the laser device with respect to the beam direction of the light emitted by the laser device. Lens 74 may also be a converging lens oriented along the slow axis (equivalent to diagrams 41 and 48).

The lens 16 of the projector focuses the laser beam emitted from the single lens 74 onto the MLA plane 22. The minimum aperture of the group of light beams in the fast axis plane is indicated by reference numeral 76. Preferably, the scan mirror 18a may be located at this position when the fast axis orientation is considered. However, the schematic diagram 78 shows that in the slow axis orientation (which has the same focal plane formed by the MLA plane 22 as in FIG. 70), the location of the smallest aperture 80 of the group of light beams in the slow axis plane is not the same location as the fast axis oriented aperture 76. Thus, when considering the slow axis orientation, the scan mirror 18a may preferably be located at this other position. Thus, since the apertures of the six lasers in the slow axis orientation and in the fast axis orientation do not overlap, neither possibility (i.e. placing the scanning mirror at the location of aperture 76 with respect to the fast axis of the emitted light or at the location of aperture 80 with respect to the slow axis of the emitted light) is perfect with respect to the respective other orientation, and therefore energy will spill over at the scanning mirror.

Schematic 82 illustrates an implementation of the principles described with respect to fig. 5. The light beam of at least one or more of the laser diodes is tilted in the fast axis plane at the output surface of the converging optics formed by the lens array 72. This means that the light beam emitted by at least one of the laser diodes leaves the converging optical component in a direction which is not parallel to the optical axis of the converging optical element. In the case of the illustrated lens array 72, the light beam emitted by at least one of the laser diodes leaves the assigned microlens in a direction that is not parallel to the optical axis of the microlens. In particular, the light beam of at least one or more of the laser diodes may also be tilted in the fast axis plane at the input surface of the converging optical element formed by the lens array 72. In the illustrated embodiment, tilting of at least one or more of the beams is achieved by tilting some of the laser diodes (labeled 10RT, 10 GT) relative to each other in the plane of the fast axis indicated in the schematic 82.

The beam of a laser diode being tilted at the input or output surface of the converging optical component may mean that the beam direction of the tilted beam deviates from the beam direction of the beam emitted by another laser diode at the input or output surface of the converging optical element. In particular, in the case of a lens array as shown in fig. 6A, the beam of the tilted laser diode may mean that the beam direction of the tilted beam deviates from the optical axis of the assigned microlens of the lens array at the input or output surface of the lens array. A tilted laser diode may mean that the main emission direction of light emitted by the tilted laser diode is not parallel to the main emission direction of light emitted by another laser diode. The main emission direction of a laser diode is the direction of the beam as it leaves the laser diode.

As a result of tilting some of the beams, for example by tilting some of the laser diodes, the focal plane given by the MLA plane 22 is maintained at the same position, but the smallest aperture 84 of the beam group in the fast axis plane may be shifted, for example closer to the laser diode. By adjusting the tilt angle of the tilted laser diode, the shift of the aperture 84 can be optimized so that it overlaps the slow axis aperture 80 in the diagram 78. Now, the superposition of all laser diode beams has overlapping minimum apertures in the fast axis plane and in the slow axis plane, and the minimum optical power is lost when the scanning mirror is placed at the location of the overlapping apertures.

Fig. 6B illustrates a further example of using optics to correct for different divergences along the fast and slow axes of a laser device, in accordance with various embodiments. As shown in the schematic 83, the light beam emitted by the laser diode 10 enters the microlenses of the lens array 72B, which forms a converging optical component that is eccentric in the fast axis plane with respect to the optical axis (indicated by the dashed line) of the microlenses. In the illustrated embodiment, this is achieved by arranging the laser diode 10 eccentrically in the fast axis plane with respect to the optical axis of the micro lens, thereby creating a beam tilt at the output surface of the lens array 72 and thus behind the lens array 72B. This principle is implemented in the laser device of the projector shown in the schematic diagram 84, in which all lasers (laser diodes 10RS, 10G, and 10 BS) are arranged in parallel at predetermined intervals, while the microlenses of the lens array 72B have slightly smaller intervals. Thus, the light beams from the lasers 10BS and 10RS are arranged eccentrically and thus are tilted to be converged (equivalent to the effect of tilting the laser diodes 10RT and 10BT in the schematic diagram 82), while the light beam from the laser diode l0G is not eccentric and thus continues without tilting. The same approach may be used for different shifts from the center of the laser diodes 10R and 10B depending on chromatic dispersion or other aberration effects. Furthermore, if a divergent beam is required, the interval of the microlenses may be wider. If the microlenses of the lens array 72/72B have different optical powers, chromatic aberration can be compensated for.

Fig. 7 illustrates an exemplary embodiment of implementing the described beam tilting in a laser device, according to various embodiments. Schematic 86 shows the placement of the laser and submount 26 at different relative angles with respect to the center parallel prism 28A. For clarity, only the laser diode l0aRT corresponding to the laser diode 10RT shown in fig. 6A is marked.

Schematic 88 shows the parallel placement of the laser diodes while prism 28B has a modified face that reflects light from each laser diode at the corresponding correct (oblique or non-oblique) angle desired. Schematic 90 is a close-up view of prism 28B. As can be seen, the prism 28B has two reflective sides onto which the laser diode emits light, with multiple facets 94 on each facet that are tilted with respect to each other. The face 94 of the prism 28B is additionally marked by color (R, G and B) and sides (a and B) depending on the laser diode assigned.

Schematic 96 illustrates an example of an exemplary size of lens array 72 that may be placed adjacent to or embedded in window 12. In this preferred configuration of the array, each cylindrical array acts on two opposing laser diodes simultaneously from both sides of the prism.

Fig. 8 illustrates a further example of using optics to correct for different divergences along the fast and slow axes of a laser device, in accordance with various embodiments. Fig. 8 includes a reproduction of the schematic diagram 70 of fig. 6A and a new schematic diagram 100 showing two laser diode groups l0aT, 10bT tilted relative to each other in the slow axis plane. The two laser groups l0aT, 10bT are tilted so that the aperture 102 in the slow axis plane (i.e., the apertures of the laser diode groups 10a and 10 b) overlaps the aperture 76 in the fast axis plane (R, G, B in each group) of fig. 6. Thus, the apertures of all six lasers are overlapping.

Fig. 9 illustrates a further example of using optics to correct for different divergences along the fast and slow axes of a laser device, in accordance with various embodiments. In the schematic diagram 104, the laser diodes (only visible laser diodes 10aRW and 10 bw are marked) are tilted on the submount 26 with respect to a horizontal plane defined by a submount (e.g., submount 11 shown in fig. 2) on which the submount 26 is mounted. In this way, the light beam strikes the prism 28 (a or b) at a specific angle and is reflected at a specific angle. Alternatively, as shown in the schematic diagram 106, a structure is also possible in which the reflecting surface of the prism 28 includes an angle deviated from 90 ° at the top of the prism 28 so that the reflected light beam receives a desired angle, and the laser diode may be horizontally mounted, i.e., to emit in the horizontal direction.

Fig. 10 illustrates a further example of using optics to correct for different divergences along the fast and slow axes of a laser device, in accordance with various embodiments. In contrast to the previously described embodiments, the lens array 72 is replaced by a single converging cylindrical lens 112 that covers all of the laser beams as described in fig. 5. Schematic 107 shows a three-dimensional schematic illustration of lenses 112, 74 and 16 and scan mirror 18A. The schematic diagram 108 shows in the fast axis plane the light beam emerging from one of the laser diodes 10B or 10R placed outside through a cylindrical lens 112 (preferably as laser window 12) and a second diverging lens 74 (e.g. the diverging lens as shown in fig. 6A), wherein the tilt of the laser diode compensates for both lenses 112 and 74 according to the principles described in connection with fig. 5. For reference, a schematic diagram 110 shows beams of light that collectively illuminate the central laser diode of the same scanning mirror 18A. Schematic 114 shows a slow axis orientation in which light in this plane is refracted only by conventional lens 16. In this example, the ellipticity of the beam is from 1:3.5 to acceptable 1: ellipticity of 1.5.

The structure shown in fig. 10 includes a laser device with a 3-laser package in which three laser diodes lie in the same plane (shown as a single beam in schematic 114). However, another laser array (such as six shown in schematic 32 or twelve shown in schematic 36) may also be implemented, with additional vertical tilting (as shown in FIG. 9) implemented if desired.

In some embodiments, the laser diodes may be vertically oriented such that the slow axis planes are overlapping (rather than the fast axis). In this case, the same arrangement of tilting is applicable, with the lenses in an orthogonal orientation.

The distance and lateral placement of the lens arrays 72, 72B or individual lenses 112 is very important, as misalignment can result in significant defocusing or undesirable beam shifting. Fig. 11 shows an embodiment in which a lens array/single lens (labeled "72/112") is placed in the laser package of a laser device. In the schematic 116, a lens array/single lens is combined with the window 12. In other words, the lens array/individual lenses form a window through which light emitted by the laser diode exits the laser package. The frame 117 holds the lens array/individual lenses to achieve optical power and sealing of the laser cavity of the laser package. In the schematic diagram 118, the lens array/individual lenses are placed directly on the submount 26, thereby enabling a shorter optical path from the laser diode and a more accurate positioning. Schematic diagrams 120 and 122 show the placement of an upward-facing or downward-facing lens array/individual lenses, respectively, on top of a submount. A similar placement is possible, wherein the lens array/individual lenses are placed on a mount (not shown) similar to the submount 26, but in close proximity to the submount 26, thereby achieving a stronger support with the same accuracy, as the lens array/individual lenses are positioned on the same mount 11 as the submount 26.

Unless otherwise indicated, use of the word "substantially" may be construed to include precise relationships, conditions, arrangements, orientations, and/or other characteristics, as well as deviations as understood by one of ordinary skill in the art, to the extent such deviations do not materially affect the disclosed methods and systems.

According to further embodiments, the features and embodiments described in connection with the figures may also be combined with each other even if not all such combinations are directly described. Furthermore, the embodiments described in connection with the figures may have additional and/or alternative features to those described in the general section.

The foregoing description of the embodiments of the disclosure has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations are possible in light of the present disclosure. The scope of the disclosure should not be limited by this detailed description, but rather by the appended claims.

Reference numerals

10 diode laser

10R, 10G, 10B laser diode

10RT, 10GT laser diode

10RS, 10G, 10BS laser diode

10aRT, 10aRW, 10bBW laser diode

10a, 10b, l0aT, 10bT laser diode group

11 base

12 window

14 reflector

15 views

16 lens

18A, 18b scanning mirror

20 field lens

22 Micro Lens Array (MLA)

24 optical device

26 base station

25 side view

27 front view

26 base station

28. 28A prism

32. 36 dot pattern

200aR, 200bB, 200bG, 200bR, 200aG, 200aB point

39. 41 schematic diagram

44. 46 cylindrical lens

48. 50 schematic diagram

52. 54 lens

55. 58 schematic diagram

60. 64, 66 beam

62. 68, 74 lens

65. 70 schematic diagram

72. 72B lens array

76. 80, 84, 102 pore diameter

78. 82, 83 schematic diagram

86. 88, 90 schematic diagram

94 faces

96. 104, 106 schematic diagram

112 lens

107. 108, 110, 114, 116 schematic diagrams

117 frame

118. 120, 122 schematic diagram

F fast axis

S slow axis

Claims (20)

1. A laser apparatus, comprising:

a laser package comprising a plurality of laser diodes (10), each laser diode emitting a light beam having a fast axis (F) and a slow axis (S) and a beam direction; and

one or more optical components configured to modify the divergence of the light beam in a fast axis plane and/or in a slow axis plane such that the light beam has the same focal plane in the fast axis plane and in the slow axis plane,

wherein the laser diodes are mounted on one or more bases (26),

Wherein the one or more abutments are arranged vertically on the base (11),

wherein the one or more optical components comprise two cylindrical lenses or at least one cylindrical lens and a lens array,

wherein at least one cylindrical lens of the one or more optical components is assigned to at least two laser diodes.

2. The laser device of claim 1, wherein at least one optical component (72, 112) is placed directly on the one or more submounts.

3. The laser device of claim 2, wherein the one or more abutments are arranged in a vertical direction between the base and the at least one optical component that is placed directly on the one or more abutments.

4. The laser device according to any of the preceding claims, wherein said at least one optical component forms a window (12) of the laser package.

5. The laser device according to any of the preceding claims, wherein at least one cylindrical lens assigned to at least two laser diodes is a single cylindrical lens assigned to all laser diodes.

6. The laser device of any of the preceding claims, wherein the one or more optical components comprise converging optical components that affect beam divergence only in the fast axis plane.

7. The laser device according to any of the preceding claims, wherein the lens array comprises a plurality of converging cylindrical microlenses arranged next to each other along a direction in the fast axis plane.

8. The laser device of claim 7, wherein each of the microlenses is assigned to at least one laser diode, wherein each of the microlenses has a cylindrical axis perpendicular to the fast axis and parallel to the slow axis.

9. The laser device according to any of the preceding claims, wherein at the output surface of the lens array the light beam of at least one laser diode is tilted in the fast axis plane with respect to the light beam of another one of the laser diodes at the output surface of the lens array and/or with respect to the optical axis of the assigned microlens.

10. The laser device of claim 9, wherein at least some of the laser diodes are tilted with respect to each other in the fast axis plane.

11. The laser device according to claim 9 or 10, wherein at least one laser diode is arranged eccentrically in the fast axis plane with respect to the optical axis of the assigned microlens.

12. The laser device according to any of the preceding claims, wherein the lens array comprises a plurality of micro lenses with different optical powers.

13. The laser device according to any of the preceding claims, wherein at least some of the laser diodes are tilted with respect to each other in the slow axis plane.

14. The laser device of any of the preceding claims, wherein the one or more optical components comprise diverging optical components that affect beam divergence only in the slow axis plane.

15. The laser device of any of the preceding claims, wherein the one or more optical components comprise diverging cylindrical lenses assigned to all laser diodes.

16. The laser device of any of the preceding claims, wherein one or more of the plurality of laser diodes are tilted at an angle to an axis of symmetry of the one or more optical components.

17. The laser device of any of the preceding claims, further comprising a prism having two reflective sides onto which the laser diode emits light, wherein on each side there are a plurality of facets tilted with respect to each other.

18. A projector comprising a laser device according to any of the preceding claims, wherein for the light beam, the aperture in the fast axis plane overlaps with the aperture in the slow axis plane.

19. A laser apparatus, comprising:

a laser package comprising a plurality of laser diodes (10), each laser diode emitting a light beam having a fast axis (F) and a slow axis (S) and a beam direction; and

one or more optical components configured to modify the divergence of the light beam in a fast axis plane and/or in a slow axis plane such that the light beam has the same focal plane in the fast axis plane and in the slow axis plane,

wherein at least two laser diodes emit light beams arranged next to each other in a direction in a first plane,

wherein the one or more optical components include a lens assigned to the at least two laser diodes and having a curvature lying in a second plane identical to the first plane.

20. The laser device of claim 19, wherein said lens is a cylindrical lens having a cylindrical axis, wherein said cylindrical axis is perpendicular to said first plane.