KR20130105381A

KR20130105381A - Projectors of structured light

Info

Publication number: KR20130105381A
Application number: KR1020130023877A
Authority: KR
Inventors: 자프릴 모르
Original assignee: 프라임센스 엘티디.
Priority date: 2012-03-15
Filing date: 2013-03-06
Publication date: 2013-09-25
Also published as: CN103309137A; CN104730825B; CN203385981U; CN103309137B; CN104730825A

Abstract

Optoelectronic devices include a monolithic array of light emitting elements disposed on a substrate in a two-dimensional pattern rather than a regular substrate and a regular grating.

Description

Projector of structured light {PROJECTORS OF STRUCTURED LIGHT}

The present invention relates generally to optical and optoelectronic devices, and more particularly to devices for the projection of patterns.

Small optical projectors are used in a variety of applications. For example, such a projector can be used to cast a pattern of coded or structured light to an object for the purpose of three-dimensional (3D) mapping (or known as depth mapping). In this regard, US Patent Application Publication No. 2008/0240502, whose disclosure is incorporated herein by reference, discloses an illumination assembly in which a light source, such as a laser diode or LED, transmits a transparency with optical radiation to project the pattern onto an object. Describe. (The terms "optical" and "light" as used in the present description and claims generally refer to any and all of visible, infrared, and ultraviolet radiation.) The image capture assembly is used to determine the pattern projected onto an object. The image is captured and the processor processes the image to reconstruct the 3D map of the object.

PCT International Publication WO 2008/120217, the disclosure of which is incorporated herein by reference, further describes aspects of the kind of lighting assembly shown in the above mentioned US 2008/0240502. In one embodiment, the slide comprises an array of micro-lenses arranged in a non-uniform pattern. The micro-lens produces a corresponding pattern of focus projected onto the object.

Optical projectors, in some applications, project light through one or more diffractive optical elements (DOEs). For example, US Patent Application Publication 2009/0185274, the disclosure of which is incorporated herein by reference, discloses an apparatus for projecting a pattern comprising two DOEs configured together to diffract an input beam to at least partially cover the surface. Describe. The combination of DOE reduces the energy in the zero-order (undiffed) beam. In one embodiment, the first DOE produces a pattern of multiple beams, and the second DOE functions as a pattern generator for forming a diffraction pattern for each beam. A similar kind of arrangement is described in US Patent Application Publication 2010/0284082, the disclosure of which is incorporated herein by reference.

As another example, US Patent Application Publication No. 2011/0188054, whose disclosure is incorporated herein by reference, describes a photonics module comprising optoelectronic components and optical elements in a single integrated package. In one embodiment, the integrated photon module (IPM) comprises a radiation source in the form of a two-dimensional matrix of optoelectronic elements disposed on the substrate and emitting radiation in a direction orthogonal to the substrate. Such IPMs typically include multiple parallel rows of emitters, such as light emitting diodes (LEDs) or vertical-cavity surface-emitting laser (VCSEL) diodes, which form a grid in the X-Y plane. The radiation from the emitter is directed to the optical module, with the appropriate patterned element and projection lens, which projects the resulting pattern onto the screen.

In many optical projection applications, the pattern must be projected over a wide angle range. For example, in the type of 3D mapping application described in the background section above, the pattern of light used to generate the map is preferably projected in a field of 90 ° or more. However, in conventional optical designs, achieving adequate optical quality for this wide field of view (FOV) requires the use of expensive multi-element projection optics. The cost and size of such optics can be very expensive for consumer applications, which is generally small and requires a low cost solution.

Embodiments of the present invention described below provide an improved apparatus and method for the projection of patterned light.

Accordingly, in accordance with an embodiment of the present invention, a photovoltaic device is provided that includes a semiconductor substrate and a monolithic array of light emitting elements disposed on the substrate in two dimensions rather than a regular grating.

In the disclosed embodiment, the light emitting device comprises a vertical-cavity surface-emitting laser (VCSEL) diode.

In some embodiments, the two-dimensional pattern of the light emitting device is an uncorrelated pattern.

In one embodiment, the light emitting elements comprise a first and a second set of light emitting elements, the first and second sets of light emitting elements being interleaved on the substrate in respective first and second patterns ( interleaved), said device comprises a first and a second conductor, said first and second set of light emitting elements such that said device selectively emits light in either or both of said first and second patterns. They are each connected to drive them separately. The device is a projection optics configured to project light emitted by the light emitting element onto an object, and only the first set of light emitting elements is driven to emit the light, so as to project a low resolution pattern onto the object, the low resolution mode And, wherein the first and second sets of light emitting elements are both driven to emit the light, the imaging device being configured to capture an image of the object, in a high resolution mode while projecting a high resolution pattern onto the object. can do.

In some embodiments, the device is mounted on a semiconductor substrate and focuses the light emitted by the light emitting element to project an optical beam onto the substrate, the optical beam comprising a light pattern corresponding to the two-dimensional pattern of the light emitting element. And a projection lens configured to focus. The apparatus may also include diffractive optics (DOE) mounted on the substrate and configured to stretch the projected optical beam by producing multiple mutually adjacent replicas of the pattern. The projection lens and the DOE may be formed on opposite sides of a single optical substrate.

Alternatively, the apparatus is adapted to project an optical beam comprising a light pattern corresponding to the two-dimensional pattern of the light emitting element on the substrate while stretching the projected optical beam by producing multiple mutually duplicate copies of the pattern. And a single diffractive optical element (DOE) configured to focus and focus the light emitted by the light emitting element and mounted on the semiconductor substrate.

In accordance with an embodiment of the present invention, there is additionally provided a method for pattern projection comprising generating an optical beam having a pattern inherent in the optical beam. The optical beam is projected using a projection lens to cast the pattern into a first region in space with a first angular range. A field multiplier is applied to extend the optical beam projected by the projection lens to cast the pattern to a second area in space having a second angle range that is at least 50% larger than the first angle range.

According to an embodiment of the invention, there is further provided a method of calculating a photovoltaic device. The method includes providing a semiconductor substrate and forming a monolithic array of light emitting devices on the substrate in a two-dimensional pattern rather than a regular grating.

The invention will be further understood from the following detailed description of the embodiment with reference to the drawings.

1 is a schematic side view of a 3D mapping system according to an embodiment of the invention;
2 is a schematic top view of a semiconductor die having a patterned emitter array formed thereon in accordance with an embodiment of the invention;
3A-3C are schematic side views of an integrated optical projection module, in accordance with an embodiment of the present invention;
4A and 4B are schematic front views of a pattern projected by an optical projection module according to an embodiment of the present invention, and
5 is a top view of a semiconductor die having a patterned emitter array formed thereon in accordance with an alternative embodiment of the present invention.

(survey)

In many optical projection applications, the pattern must be projected over a wide angle range. For example, in the type of 3D mapping application described in the background section above, the pattern of light used to generate the map is preferably projected in a field of 90 ° or more. In conventional optical designs, achieving adequate optical quality for this wide field of view (FOV) requires the use of expensive multi-element projection optics. The cost and size of such optics can be very expensive for consumer applications, which is generally small and requires a low cost solution.

Some embodiments of the present invention described below address these needs by means of a field multiplier that follows the projection optics in the optical train and stretches the field onto which the desired pattern is projected while maintaining the optical quality of the projected pattern. . The addition of a field multiplier makes it possible to project patterns over a large area using small, low cost projection optics which themselves have a relatively narrow FOV.

In the disclosed embodiment, the optical device has a beam source for producing a patterned optical beam. The projection lens projects the patterned optical beam and casts the pattern to a given area in space with a particular angular range corresponding to the field of view (FOV) of the projection lens, without a field multiplier. (The term "lens" as used in the context of this description and claims refers to both simple and complex, multi-element lenses unless otherwise clearly indicated.) The interposed, patterned beam is stretched between given regions in to cause the pattern to be cast into a region in space having an angular range that is at least 50% larger than the FOV of the projection lens. Depending on the design, the extended beam following the field magnifier may have an FOV of twice or more than the projection lens.

In some embodiments, the beam source has a monolithic array of light emitting elements disposed on the semiconductor substrate in a two-dimensional pattern that corresponds to a pattern imparted on the optical beam.

(System description)

1 is a schematic side view of a 3D mapping system 20 according to an embodiment of the invention. System 20 is described herein as an example (but not by way of limitation) of the kind of field multiplier described below. The principles of the present invention can be similarly applied in other types of optical projection systems that require a wide field of view and can benefit from the miniaturization and low cost benefits provided by the disclosed embodiments.

The system 20 includes a projection assembly 30 that projects the patterned beam 38 onto the surface of the object 28 (in this example, at the user's side of the system). Imaging assembly 32 processes the image to capture an image of the pattern projected on the surface and derive a 3D map of the surface. For this purpose, the assembly 32 generally includes objective optics as well as a digital processor (not shown) that processes the image to produce a 3D map, and an image sensor 42 that captures the image. Include. Image capture and processing aspects of system 20 are described, for example, in the above-mentioned US Patent Application Publication 2010/0118123 and US Patent Application Publication 2010/0007717, the disclosures of which are incorporated herein by reference.

Projection assembly 30 includes a patterned beam generator 34 that projects a patterned illumination beam with a particular FOV, and a field multiplier 36 that extends the projected beam into a patterned beam 38 generated with a wider FOV. ). In this example, the pattern has a high contrast light spot on a dark background, in a random or quasi-random arrangement, as described in the above-described patent application publication. Alternatively, other suitable types of patterns (including images) can be projected in this way.

(Integrated pattern generator)

VCSEL arrays can advantageously be used in the manufacture of small, high intensity light sources and projectors. In a conventional VCSEL array, the laser diodes are arranged in a regular grid, such as the straight grid pattern, or the hexagonal grid pattern described in the above-mentioned US patent application publication 2011/0188054. As used in the context of this description and claims, the term "regular lattice" means a two-dimensional pattern in which the space between adjacent elements in a pattern (eg between adjacent emitters in a VCSEL array) is constant. . In that sense, the term "regular lattice" is similar to a periodic lattice.

Embodiments of the invention described below deviate from this model and instead provide a VCSEL array in which the laser diodes are arranged in a pattern rather than a regular grating. The optics may be combined to project into the space the light pattern emitted by the elements of the VCSEL array as a pattern of corresponding spots, where each spot includes light emitted by the corresponding laser diode in the array. In general (but not necessarily), the pattern of laser diode positions in the array, and thus the pattern of spots, is such that the auto-correlation of the position of the laser diode as a function of transverse shift There is no correlation in the sense that it is not important for any shift larger than magnitude. Random, pseudorandom, and quasi-periodical patterns are examples of such unrelated patterns. The projected light pattern will thus also be independent of each other.

This kind of patterned VCSEL array is particularly useful for producing integrated pattern projection modules, as described below. Such a module can achieve cost and size reduction with the benefit of simplicity of design and manufacturing as well as better performance compared to projection devices known in the art.

2 is a schematic top view of a photovoltaic device having a semiconductor die 100 in which a monolithic array of VCSEL diodes 102 is formed in a two dimensional pattern rather than a regular grating, according to an embodiment of the invention. The array yields a VCSEL array known in the art, with a suitable thin film layer structure that forms the laser diode, and a conductor that supplies power and ground connection from the contact pad 104 to the laser diode 102 in the array. It is formed on a semiconductor substrate by the same kind of photolithographic method as is used to.

The arrangement of the irregular gratings of FIG. 2 is simply achieved by the proper design of the photolithographic mask used for array calculation, in any desired two dimensional pattern. Alternatively, an irregular array of other types of surface emitting devices, such as light emitting diodes (LEDs), can be similarly calculated in this way (although incoherent light sources such as LEDs are less suitable for some pattern projection applications). .

Monolithic VCSEL arrays of the type shown in FIG. 2 have the advantage of high power scalability. For example, using current technology, a die having an active area of 0.3 mm 2 may include 200 emitters, and the total optical power output is about 500 mW or more. VCSEL diodes can be designed to emit circular beams and emit circular Gaussian beams in a single crossing mode, which has the advantage of generating high contrast and high density spot patterns. Since the VCSEL emission wavelength is relatively stable as a function of temperature, the spot pattern will be similarly stable during operation, even without active cooling of the array.

3A is a schematic side view of an integrated optical projection module 110 that includes a VCSEL array, such as the array shown in FIG. 2, in accordance with an embodiment of the present invention. The VCSEL die 100 is generally tested at the wafer level, then diced and mounted on the appropriate sub-mount 114 with the appropriate electrical connections 116, 118. Electrical connections, and also possible control circuits (not shown), may be coupled to die 100 by wire bonding conductors 122.

Lens 120 mounted on a die on appropriate spacer 122 focuses and projects the output beam of the VCSEL emitter. For temperature stability, glass lenses can be used. Diffractive optical element (DOE) 124, positioned by spacer 126, creates multiple copies 128 of the pattern fanning out over the extended angular range. For example, the DOE includes a Dammann grating or similar device, as described in the above-mentioned U.S. Patent Application Publications 2009/0185274 and 2010/0284082.

4A is a schematic front view of the stretched pattern 160 projected by the optical projection module 110 in accordance with an embodiment of the present invention. This figure illustrates a kind of fan out pattern generated by DOE 124. The DOE in this example stretches the projected beam to an array of 11 x 11 tiles 162 centered on each axis 164, although more or fewer tiles may alternatively be calculated. Each tile 162 (having a twisted square shape by pincushion distortion) in FIG. 4A includes a pattern of bright spots 166 that are replicas of the pattern of the VCSEL array.

In general, the fan out angle between adjacent tiles in this example is in the range of 4-8 °. For example, assuming that each such tile contains about 200 spots in an unrelated pattern, corresponding to about 200 laser diodes 102 in the VCSEL array, the 11 x 11 fan out shown in FIG. 4A. Pattern 160 then includes more than 20,000 spots. DOE 124 is designed such that a projected copy of a pattern can tile a surface or spatial area into a tile, as described, for example, in US Patent Application Publication 2010/0284082.

FIG. 3B is a schematic side view of an integrated optical projection module 130 that includes an irregular VCSEL array, such as the array shown in FIG. 2, in accordance with an alternative embodiment of the present invention. In this embodiment, the refractive projection lens 120 of the module 110 is replaced by the diffractive lens 130. Lens 130 and fan out DOE 134 (similar to DOE 124) may be formed on opposite sides of the same optical substrate 132. Although the diffractive lens is sensitive to wavelength changes, the relative stability of the wavelength of the VCSEL device makes this approach feasible. DOE 134 is protected by window 138 mounted on spacer 140.

3C is a schematic side view of an integrated optical projection module 150 that includes an irregular VCSEL array, according to another embodiment of the present invention. Here, the functions of the diffractive lens and the fan out DOE are formed on the optical substrate 152 and combined into a single diffractive element 154, which also functions as a window. The element 154 performs both focusing and fan out functions: it corresponds to the two-dimensional pattern of the luminous means on the substrate, while stretching the projected optical beam by producing multiple mutually adjacent copies of the pattern as shown above. The light emitted by the light emitting element is focused and focused on the die 100 to project an optical beam including the light pattern.

While assembling the modules shown in FIGS. 3A-C, the DOE is generally aligned in four dimensions (X, Y, Z, and rotation) relative to the VCSEL die 100. The embodiments of 9B and 9C show that the photolithographic process used to calculate both the VCSEL array and the DOE / diffractive lens structure is accurate to about 1 μm, and thus simply by matching the fiducial mark X, Y Since it allows passive alignment in, and rotation, there is an advantage with regard to alignment. Z-alignment (ie, the distance between the VCSEL die and the DOE and the lens) requires only a small range of motion, due to the high production accuracy. Z-alignment is thus actively achieved while the VCSEL array is powered, for example, using a height-measuring device such as a confocal microscope to measure the distance between the VCSEL surface and the DEO surface, Or passively.

The modules of FIGS. 3A-C can be used as pattern projectors in the 3D mapping system 20. The tiled pattern (eg, as shown in FIG. 4A) is projected onto the object of interest, and imaging module 32 captures an image of the pattern on object 28. As described above, the processor associated with the imaging module measures, at each point in the image, a local transverse shift of the pattern, for a known reference, and then coordinates the depth of that point by triangulation based on the local shift. Find it.

Each copy of the pattern, corresponding to one of the tiles 162 in FIG. 4A, is internally uncorrelated, but is generally highly correlated with neighboring tiles. Since each copy of the pattern includes a relatively small number of spots 166, distributed over a relatively small angular range, depth coordinates when the transverse shift of the pattern on the object is an order above the pitch of the tile 162. There may be uncertainty at. To reduce this ambiguity, the VCSEL die 100 can be calculated with a larger number of laser diodes, and the optics of the projection module can thus yield more tiles; This solution increases the complexity and cost of both the VCSEL die and optics.

4B is a schematic front view of the stretched pattern 170 projected by the optical projection module, in accordance with an alternative embodiment of the present invention that addresses the problem of correlation between neighboring tiles. (The DOE-based field multipliers of FIGS. 3A and 3B may be similarly configured to yield a pattern similar to pattern 160 or 170.) The tiled pattern of the interleaved kind shown in FIG. 4B is a fan out DOE. Is calculated by proper design. In this design, at least a portion of the tiles of the pattern are transversely offset relative to neighboring tiles by an offset of some degree of pitch. In particular, in this example, tile 172 is offset transversely by one-half tile relative to neighboring tile 174. (According to the assumption that only the transverse shift in the horizontal direction was used for the depth measurement, the offset is vertical in this example.)

As a result of this offset between the tiles, the range of clear depth measurements is substantially doubled. Other interleaving in which adjacent tiles are shifted by one third or one quarter of the tile pitch can provide a larger clear measurement range, for example. DOEs providing these and other fan out patterns can be designed using methods known in the art, such as those based on the Gerchberg--Saxton algorithm.

5 is a schematic top view of a semiconductor die 180 with a monolithic VCSEL array formed in accordance with another embodiment of the present invention. This array is similar to the array of FIG. 2 except that in the embodiment of FIG. 5 there are two groups of VCSEL diodes 182 and 184 driven by separate conductors 186 and 188. Although diodes 182 and 184 are shown in the figures as having different shapes, the differences in these shapes are for visual clarity only, and in practice, all VCSEL diodes in both groups generally have the same shape.

The two groups of VCSEL diodes 182 and 184 shown in the figure can be used with the high resolution image sensor 42 in the imaging module 32 (FIG. 1) to implement a zoom function in the depth mapping system 20. Can be. The individual power lines supplying the two groups can be implemented by supplying individual power traces to two groups within a single metal layer of the VCSEL die, or adding a metal layer so that each group is powered by a different layer. Can be. The two groups may include the same or different number of diodes depending on the desired performance characteristics of the system. It is assumed that the image sensor supports binning neighboring detector elements (which accept reduced resolution and provide improved sensitivity and speed) and cropping the sensing area and adjustable clock speed. These features are provided by various commercially available image sensors.

In wide angle mode, one of the two groups of VCSEL diodes (eg, diode 182) receives power while the other group is blocked. As a result, the powered groups can be driven at high power to increase the brightness of individual spots in the pattern without exceeding the overall power requirement of the VCSEL die. (Higher power per emitter is possible because of the increased distance between active neighboring emitters in this mode, which reduces the associated thermal effect.) On the other hand, the image sensor 42 operates in the binning mode and , Thus forming a low resolution image of the entire field of view of the system. Since the detector element of the image sensor is binned, the image sensor can capture and output the image at high speed. The processor measures the transverse shift of the pattern in this image to produce the initial low resolution depth map.

The processor may segment and analyze the low resolution depth map to recognize, within the field of view, an object of potential interest, such as a human body. In this step, the processor selects to zoom in on the object of interest. For this purpose, the processor turns on all VCSEL diodes 182 and 184 in both groups to produce a high resolution pattern. The processor also directs the image sensor 42 to operate in cropping mode to scan only the area within the field of view in which the object of interest was found. The image sensor at this stage is typically read at full resolution (within the cropped area) without binning, and thus can capture a high resolution image of a high resolution pattern. Due to the cropping of the reading area, the image sensor can also output the image at high speed in the high resolution mode. The processor now measures the transverse shift of the pattern in this latter image to form a high resolution depth map of the object of interest.

The embodiment described above allows for optimal use of both the power resources of the VCSEL-based pattern projector and the detection resources of the image sensor. In both wide angle and zoom modes, the scanning speed and sensitivity of the image sensor are typically (by binning, cropping, and clock speed adjustments) to provide a depth map of the appropriate resolution at a constant frame rate, such as 30 frames / second. Can be adjusted.

Although some of the above embodiments specifically refer to pattern based 3D mapping, the pattern projector described above can be similarly used in other applications, including both 2D and 3D imaging applications using patterned light. Accordingly, it is to be understood that the above-described embodiments are cited by way of example and that the invention is not limited to those specifically shown and described above. Rather, the scope of the present invention includes both combinations and sub-combinations of the various features described above, as well as variations and modifications that may occur to those skilled in the art upon reading the foregoing description.

Claims

A semiconductor substrate; And
A monolithic array of light emitting elements disposed on the substrate in a two dimensional pattern rather than a regular grid;
Optoelectronic device comprising a.
2. The photovoltaic device of claim 1, wherein the light emitting element comprises a vertical-cavity surface-emitting laser (VCSEL) diode.
The photovoltaic device of claim 1, wherein the two-dimensional pattern of the light emitting element is an uncorrelated pattern.
2. The light emitting device of claim 1, wherein the light emitting elements comprise first and second sets of light emitting elements, the first and second sets of light emitting elements being interleaved on the substrate in respective first and second patterns ( interleaved),
The device comprises a first and a second connection respectively for individually driving the first and second sets of light emitting elements such that the device selectively emits light in either or both of the first and second patterns. An optoelectronic device comprising first and second conductors.
5. The method of claim 4,
Projection optics configured to project light emitted by the light emitting element onto an object; And
While only the first set of light emitting elements is driven to emit the light, projecting a low resolution pattern onto the object, the image of the object is captured in a low resolution mode, and both the first and second sets of light emitting elements And an imaging device configured to capture an image of the object in a high resolution mode while being driven to emit light and projecting a high resolution pattern onto the object.
2. The method of claim 1, further comprising focusing and focusing the light emitted by the light emitting element to project an optical beam onto the substrate that is mounted on the semiconductor substrate and includes a light pattern corresponding to the two-dimensional pattern of the light emitting element. And a projection lens configured to.
7. An optoelectronic device according to claim 6, comprising a diffractive optical element (DOE) mounted on the substrate and configured to stretch the projected optical beam by producing multiple mutually adjacent replicas of the pattern. .
8. The photovoltaic device of claim 7, wherein the projection lens and the DOE are formed on opposite sides of a single optical substrate.
2. The method of claim 1, further comprising: projecting the optical beam including a light pattern corresponding to the two-dimensional pattern of the light emitting element on the substrate while stretching the projected optical beam by calculating multiple mutually adjacent copies of the pattern. And a single diffractive optical element (DOE) configured to focus and focus the light emitted by the light emitting element and mounted on the semiconductor substrate.
As a method of calculating a photoelectric device,
Providing a semiconductor substrate; And
Forming a monolithic array of light emitting elements on the substrate in a two-dimensional pattern rather than a regular lattice.
The method of claim 10, wherein the light emitting device comprises a vertical-cavity surface-emitting laser (VCSEL) diode.
The method of claim 10, wherein the two-dimensional pattern of the light emitting element is a mutually unrelated pattern.
11. The method of claim 10, wherein forming the monolithic array includes forming first and second sets of light emitting elements, wherein the first and second sets of light emitting elements are respectively first and second. Interleaved on the substrate in two patterns, and
The method comprises the steps of individually driving the first and second sets of light emitting elements such that the device selectively emits light in either or both of the first and second patterns. How to calculate the photoelectric device.
The method of claim 13,
Projecting light emitted by the light emitting element onto an object;
Capturing a first image of the object in a low resolution mode while only the first set of light emitting elements is driven to emit the light to project a low resolution pattern onto the object; And
Capturing a second image of the object in a high resolution mode while both the first and second sets of light emitting elements are driven to emit the light to project a high resolution pattern onto the object;
Method for calculating a photovoltaic device comprising a.
12. The semiconductor substrate of claim 10, wherein a projection lens is projected on the semiconductor substrate to focus and focus light emitted by the light emitting element to project an optical beam including the light pattern corresponding to the two-dimensional pattern of the light emitting element onto the substrate. Mounting to a phase.
16. The photoelectric of claim 15 comprising mounting a diffractive optical element (DOE) on said substrate to extend the projected optical beam by calculating multiple mutually replicas of said pattern. How to calculate the device.
17. The method of claim 16, wherein the projection lens and the DOE are formed on opposite sides of a single optical substrate.
18. The method of claim 17, further comprising: projecting an optical beam comprising a light pattern corresponding to the two-dimensional pattern of the light emitting element on the substrate while stretching the projected optical beam by calculating multiple mutually adjacent copies of the pattern. Mounting a single diffractive optical element (DOE) on the semiconductor substrate to focus and focus the light emitted by the light emitting element.