CN108332082B

CN108332082B - Lighting module

Info

Publication number: CN108332082B
Application number: CN201810036240.5A
Authority: CN
Inventors: 许星
Original assignee: Shenzhen Orbbec Co Ltd
Current assignee: Shenzhen Orbbec Co Ltd
Priority date: 2018-01-15
Filing date: 2018-01-15
Publication date: 2020-06-30
Anticipated expiration: 2038-01-15
Also published as: CN108332082A

Abstract

The present invention provides a lighting module, comprising: a light source for emitting a light beam; a lens for diverging or converging the light beam; a diffractive optical element that replicates and expands the light beam to an illuminated space; a processor connected to and controlling one or more of the light source, lens, diffractive optical element to achieve flood or structured light illumination. And adjusting one or more of the light source, the lens and the diffraction optical element by the processor to meet the conditions of flood lighting or structured light illumination, so as to realize the flood lighting or the structured light illumination. This lighting module fuses these two kinds of functions of floodlight illumination and structured light projection to a module, can switch at any time as required in order to realize floodlight illumination or structured light illumination to have characteristics small, that the consumption is low, be favorable to being integrated to in the smart machine.

Description

Lighting module

Technical Field

The invention relates to the field of semiconductor illumination, in particular to an illumination module.

Background

Visual information is gradually becoming an important way for intelligent equipment to acquire information and sense the world, and along with the continuous increase of functions and diversified application scenes of the intelligent equipment, the requirements realized based on the visual information are more and more extensive. For example, functional requirements such as unlocking and payment based on face recognition, gesture and action interaction based on human body information, and the like, and meanwhile, the functions also need to have higher reliability under different scenes and different ambient lighting conditions. The traditional equipment has the defects that the requirements are difficult to meet by utilizing a camera to acquire color image information, the reliability of acquiring the visual information under different scenes and different environmental illumination conditions can be improved based on the visual information acquisition of active light illumination, for example, infrared images, and the functions which are difficult to realize by utilizing a depth camera to acquire depth images, such as high-precision face recognition and gesture interaction, can be realized. In addition, in the case of face recognition using a depth camera, it is necessary to perform floodlighting on a target at night to realize high-precision recognition.

Infrared lighting, infrared cameras, depth cameras, and the like will increasingly be used in smart devices to obtain visual information such as infrared, depth images, and the like. However, this also brings about some problems. The trend of miniaturization, lightness and thinness of smart devices makes it particularly difficult to integrate so many devices. On one hand, more devices bring higher power consumption, thereby reducing the endurance of the intelligent equipment; on the other hand, the requirement of the integration of multiple devices on the assembly process is greatly improved, so that the yield of products is reduced, and the production cost is increased.

Disclosure of Invention

In order to solve the problems, the invention provides the lighting module, two functions of flood lighting and structured light projection are integrated into one module, and the module can be switched at any time as required to realize the flood lighting or the structured light lighting, and has the advantages of small volume and low power consumption.

The invention provides a lighting module, comprising: a light source for emitting a light beam; a lens for diverging or converging the light beam; a diffractive optical element that replicates and expands the light beam to an illuminated space; a processor connected to and controlling one or more of the light source, lens, diffractive optical element to achieve flood or structured light illumination.

In some embodiments, the lens is a zoom lens and the processor is configured to control a change in focal length of the lens to achieve flood or structured light illumination.

In some embodiments, the diffractive optical element comprises a first diffractive pattern and a second diffractive pattern, and an included angle between adjacent diffracted light beams formed after diffraction by the first diffractive pattern is not larger than a divergence angle of an incident light beam so as to realize floodlight illumination; and an included angle between adjacent diffraction light beams formed after diffraction by the second diffraction pattern is larger than a divergence angle of the incident light beams, so that structured light illumination is realized.

In some embodiments, the light source comprises a first sub-light source and a second sub-light source, the processor controls the first sub-light source to emit a first sub-light beam, and the first sub-light beam is replicated and expanded by the diffractive optical element to cover and fill the illuminated space so as to realize floodlighting; the regulator controls the second sub-light source to emit a second sub-light beam, and the second sub-light beam is copied and expanded by the diffractive optical element to form spot-patterned structured light for illumination. The light source comprises an array light source which comprises a substrate, and the first sub light source and the second sub light source are arranged on the substrate. One or more of the light emitting area, the divergence angle, and the number of the first sub-light sources are different from those of the second sub-light sources. The lens is a micro lens array, and micro lens units in the micro lens array correspond to the sub light sources.

The invention also provides an imaging device, which comprises the lighting module and a light module, wherein the lighting module is used for providing floodlight lighting or structured light lighting; the processor is connected with the lighting module and the image sensor, controls the lighting module to acquire a floodlight image by using the image sensor under floodlight illumination, and controls the lighting module to acquire a structured light image by using the image sensor under structured light illumination.

In some embodiments, the processor calculates a depth image based on the structured light image. The processor is configured to fuse the depth image and the flood image. The invention has the beneficial effects that: the processor adjusts one or more of the light source, the lens and the diffraction optical element to meet the conditions of flood lighting or structured light illumination, so that the flood lighting or the structured light illumination is realized. This lighting module fuses these two kinds of functions of floodlight illumination and structured light projection to a module, can switch at any time as required in order to realize floodlight illumination or structured light illumination to have characteristics small, that the consumption is low, be favorable to being integrated to in the smart machine.

Drawings

Fig. 1 is a schematic view of a floodlight module according to an embodiment of the present invention.

Fig. 2 is a schematic view of a floodlight module comprising a lens according to an embodiment of the invention.

FIG. 3 is a schematic view of a focused illumination according to an embodiment of the invention.

FIG. 4a is a schematic view of a regular floodlight pattern according to an embodiment of the present invention.

FIG. 4b is a schematic diagram of a regular speckle pattern in accordance with an embodiment of the present invention.

Fig. 5a is a schematic view of an irregular floodlight pattern according to an embodiment of the present invention.

FIG. 5b is a schematic diagram of an irregular speckle pattern according to an embodiment of the present invention.

Fig. 6 is a schematic view of overlapping floodlight patterns according to an embodiment of the present invention.

FIG. 7 is a schematic view of a density variation spread flood pattern in accordance with an embodiment of the present invention.

Fig. 8 is a schematic diagram of a floodlight module comprising a beam-shaping modulator according to an embodiment of the present invention.

FIG. 9 is a schematic diagram of a flood pattern formed by a square beam of light according to an embodiment of the present invention.

Fig. 10a is a schematic view of an irregular floodlight pattern formed by the array light source according to an embodiment of the present invention.

FIG. 10b is a schematic diagram of an irregular speckle pattern formed by the array light source according to an embodiment of the present invention.

FIG. 11 is a schematic diagram of a flood and structured light illumination module according to an embodiment of the present invention.

FIG. 12 is a schematic view of a light source according to an embodiment of the invention.

Fig. 13 is a schematic diagram of an array light source according to an embodiment of the invention.

FIG. 14 is a schematic diagram of a flood and structured light illumination module according to an embodiment of the present invention.

FIG. 15 is a schematic view of an imaging device according to an embodiment of the invention.

FIG. 16 is a schematic view of dynamic projection according to an embodiment of the present invention.

Detailed Description

Fig. 1 is a schematic view of a floodlighting module according to one embodiment of the invention. The module 10 includes a light source 11 and a Diffractive Optical Element (DOE)12, where the light source 11 may be a light source such as an LED or a laser, and is configured to emit light beams such as infrared light, ultraviolet light, and visible light. The light source 11 emits a light beam, which forms an incident light beam on an incident surface of the DOE12, the DOE12 receives the incident light beam, diffracts the incident light beam and spreads the light beam to a wider space 13 to realize flood illumination, and in one embodiment, the DOE12 plays a role of beam splitting, i.e., a single incident light beam is replicated and spread into a plurality of emergent light beams without changing basic properties, wherein the basic properties include a light beam size, a polarization direction, a phase, a divergence angle, and the like. As shown in fig. 1, the light beam emitted from the light source 11 is diffracted by the DOE12 to form a plurality of exit beams of diffraction orders (only-1, 0, 1 order diffracted beams are shown in the figure), and the space 13 is illuminated by the plurality of exit beams. For the purpose of flood lighting, the multiple outgoing light beams need to substantially cover and fill the illuminated space 13, where the substantially covered filling means that the multiple outgoing light beams need to cover the illuminated space, so that each area of the illuminated space is illuminated and no obvious non-illuminated area appears, and it is desirable that the light intensity distribution in the illuminated space is substantially uniform, and specifically, referring to fig. 4(a), 5(a), 6 and 7, no obvious gap exists between adjacent outgoing light beams, and the outgoing light beams are adjacent or overlap each other.

In some embodiments, the illumination module is configured to provide active infrared illumination, and the light source 11 may be an edge-emitting laser emitter, a vertical cavity surface laser emitter (VCSEL), and the like, and compared with the difference in beam shape, divergence angle, and the like of different lasers, so that, according to different types of laser emitters, there is also a difference in requirements of the DOE for implementing flood illumination, for example, the divergence angle of the edge-emitting laser emitter is larger than that of the VCSEL, and therefore, when the DOE is used to split beams emitted by the edge-emitting laser emitter, an included angle between beams of adjacent diffraction orders may be set to be larger when the DOE is designed. In addition, the edge-emitting laser emitter often emits a light beam with an elliptical cross section, so that in order to realize floodlight illumination, an included angle between adjacent diffraction order light beams in the major axis direction of the ellipse can be set smaller than an included angle between adjacent diffraction order light beams in the minor axis direction of the ellipse when the DOE is designed.

In some embodiments, a lens may also be added between the light source and the DOE in order to further modulate the light source beam to achieve the required flood illumination. As shown in fig. 2, the lens 20 is disposed between the light source and the DOE, the light source 11 emits a light beam, the lens 20 refracts the light beam emitted by the light source to realize converging and diverging of the light beam, the light beam refracted from the lens forms an incident light beam on an incident surface of the DOE, and the DOE receives the incident light beam, diffracts the incident light beam and then diffuses the diffracted incident light beam to the target space region. The lens can be a concave lens, a convex lens and the like, wherein the concave lens is used for realizing the divergence of the light beam, and the convex lens is used for realizing the convergence of the light beam. For example, in one embodiment, in order to increase the distance of the flood illumination, the converging lens 20 is arranged to reduce the sectional area of the incident light beam incident on the DOE, and simultaneously increase the light intensity in a unit area, so that the beam split by the DOE can irradiate a farther spatial region; illumination at close distances can instead be achieved by providing a diverging lens 20.

In some embodiments, the control of the incident/emergent beam cross-sectional area of the DOE can be achieved by setting the distance between the light source and the lens, so as to further control the beam intensity. Taking the convex lens as an example, in the range that the distance between the light source and the convex lens is smaller than the focal length of the convex lens, the larger the distance between the light source and the lens is, the larger the beam sectional area of the light beam incident on the DOE surface is, and conversely, the smaller the beam sectional area of the light beam incident on the DOE surface is. FIG. 3 is a schematic illustration of a focused illumination according to one embodiment of the invention. When the distance between the light source and the lens is not less than the focal length of the lens, the diffracted light beams can be collimated or focused at a certain position in space. In contrast to fig. 1 and 2, the illumination module projects a spot-patterned beam, which can be used for structured light projection.

The generation of a spot patterned beam can be achieved by controlling the DOE beam splitting effect in addition to using a lens to control beam focusing. According to DOE diffraction equation:

sinθ_x＝m_xλ/P_x(1)

sinθ_y＝m_yλ/P_y(2)

in the above equation, θ_x、θ_yRespectively, the diffraction angles in the x and y directions, m_x、m_yDenotes the number of diffraction orders in the x and y directions, respectively, λ denotes the wavelength of the light beam, P_x、P_yThe periods of the DOE in the x and y directions, respectively, are referred to as the dimensions of the elementary cells.

From the above diffraction equations, the angle of the diffracted beam is inversely proportional to the period of the elementary cells on the DOEThe angle between adjacent diffracted beams is thus controlled by controlling the period of the basic cells when designing the DOE, and typically, when the angle between adjacent diffracted beams is greater than the divergence angle of the incident beam on the DOE, a significant gap between adjacent beams is seen, separating the beams to produce a spot-patterned beam. Due to the error of the optical system, the relationship between the angle between the adjacent diffracted beams and the divergence angle of the incident beam when the speckle pattern is illuminated is not required to strictly satisfy the above relationship, and some entrance and exit are allowed. In addition, if the incident beam is a focused beam, the divergence angle of the incident beam is not changed after passing through the diffractive optical element, and the beam may be a speckle pattern near the focusing plane, and the beam may be overlapped and blurred at a far place due to the continuous divergence of the beam. Further, the divergence angle of the incident light beam can be more accurately understood as the angle formed by the light spot formed by the diffracted light beam on a certain surface (the surface forming the spot pattern) in space relative to the diffractive optical element, such as the angle a in fig. 1₂As shown. Since the distance between the patterned surface and the diffractive optical element is much greater than the distance between the diffractive optical element and the light source, the incident light beam divergence angle a₁And angle a₂Are almost equal. When the included angle a₂When the included angle is smaller than that between adjacent diffracted light beams, a gap is formed between the adjacent light beams to form a spot pattern, and when the included angle is smaller than that₂When the included angle between the adjacent diffracted light beams is not less than the included angle between the adjacent diffracted light beams, the adjacent light beams are overlapped to form a floodlight pattern. It will be understood, therefore, that the relationship between the angles described above is the best example for implementing a patterned light beam (hereinafter a flood light beam will also appear), and other slight differences due to errors or other causes are included in the technical solution of the present invention as an exemplary representative.

FIG. 4 is a schematic diagram of a flood pattern and a spot pattern, respectively, according to one embodiment of the present invention. Fig. 4(a) is a flood pattern of diffracted beams substantially covering a fill space to achieve flood illumination, and fig. 4(b) is a speckle pattern of diffracted beams by focusing to achieve structured light projection. The individual beams of light in the flood pattern abut and substantially cover the space to be illuminated. There are significant gaps between the individual beams in the speckle pattern to form an independently arranged speckle pattern. In the embodiment shown in fig. 4, the DOE diffracts the light beams in a regular arrangement, which is advantageous in that the DOE design is facilitated and the intensity distribution of the flood pattern is more uniform, and is disadvantageous in that the spot pattern is not favorable for the calculation of the subsequent depth image. Thus, in some embodiments, the DOE is designed such that the arrangement of the light beams is irregular, as shown in fig. 5, where fig. 5(a) shows a flood pattern formed by irregular arrangement of the light beams and fig. 5(b) shows a spot pattern formed by irregular arrangement of the light beams.

The more uniform the intensity distribution of the flood pattern, the better the quality of the acquired image. In some embodiments, to obtain a flood pattern with a more uniform intensity distribution, the illuminated space is filled by overlapping the light beams with each other, as shown in fig. 6. By overlapping each other, gaps between adjacent beams in adjacent alignment can be avoided, thereby increasing the uniformity of the intensity distribution of the pattern.

The intensity of the light beam decreases as the number of diffraction orders increases, and thus the arrangement density of the light beams is set to a non-uniform form in order to obtain a flood pattern having a relatively uniform intensity distribution, which is obtained by increasing the arrangement density of the light beams of higher diffraction orders in one embodiment, as shown in fig. 7.

In some embodiments, a relatively uniform intensity distribution pattern may also be obtained by modulation of the beam shape. Fig. 8 is a schematic diagram of an illumination module including a beam shape modulator according to one embodiment of the present invention. The module contains light source, beam shape modulator 80, DOE, and the light beam that the light source launches forms the preset pattern after beam shape modulator 80 modulates, and DOE will preserve the pattern and carry out the floodlight pattern of filling in the space of being lighted after duplicating in order to form beam intensity distribution relatively even. The beam shape modulator modulates the beam shape into a square as in the embodiment shown in fig. 9, but may modulate other shapes in other embodiments. The beam shape modulator 80 may be one or a combination of optical elements including refractive, reflective, diffractive, transmissive, masked, etc. It is understood that any optical element that can modulate a light beam can be used in the present invention.

In some embodiments, the light emission properties of the light source itself may be directly set, such as by changing the size and shape of the light emission aperture to modulate the final pattern. For example, configuring a light source to emit a square beam of light may achieve a flood pattern as shown in FIG. 9.

The individual light sources tend to be less powerful and the energy of the individual beams is reduced more significantly after beam splitting by the DOE. To address this issue, an array of light sources may be utilized. In one embodiment, a VCSEL array is used as the light source, and the VCSEL array is formed by arranging a plurality of VCSEL light sources on a semiconductor substrate, which has the advantages of small volume, low power consumption, and the like. The VCSEL array emits an array beam that is split by the DOE to fill the illuminated space to form a flood pattern, as shown in fig. 10 (a). By controlling the focal length of the lens, the distance between the light source and the lens, and other factors, the structured light spot pattern illumination as shown in fig. 10(b) can be realized. In the pattern shown in fig. 10, the dashed line frame is only for illustration, and the pattern in the dashed line frame corresponds to the VCSEL array light source, and typically, if no lens is included, it is generally the same as the arrangement pattern of the VCSEL array light source; if a lens is included, it is generally in a central symmetrical relationship with the arrangement pattern of the VCSEL array light sources. It can be understood that, after the array light source is used to replace a single light source, a single dashed frame can be regarded as a "single light beam", and therefore, the arrangement manner of the single dashed frame can also be similar to that of a single light source lighting module, and the single dashed frame can be arranged regularly or irregularly, can be arranged adjacently or overlapped, and can also be arranged at different densities. In the embodiment shown in fig. 10, the coverage of the illuminated space is realized by the regular and adjacent arrangement between the adjacent dashed boxes.

The above embodiments mainly illustrate that the light source and the DOE are used to realize flood lighting or structured light illumination/projection, and currently, some intelligent devices often need to have both flood lighting and structured light projection functions, and call one or both of flood lighting and structured light illumination when needed. For example, in devices such as mobile phones, tablets, computers and the like, high-precision face recognition needs to be realized by collecting infrared images and depth images, and thus infrared floodlighting and structured light depth cameras are needed. It is clear that this can be achieved by integrating a separate infrared floodlight and a separate structured light depth camera into the device, which however increases the cost of the device and the difficulty of the manufacturing process, especially for miniature smart devices such as mobile phones, where the space available to accommodate these components is very limited. In order to solve the problem, the invention provides a lighting module with both flood lighting and structured light projection, which can realize the switching between the flood lighting and the structured light, or realize the flood lighting and the structured light at the same time.

Fig. 11 is a schematic diagram of a flood and structured light lighting module according to an embodiment of the present invention, which can realize flood lighting or structured light lighting, and can freely switch between the flood lighting and the structured light lighting. The module comprises a light source 111, a lens 112, a DOE113 and an adjuster 114, wherein the adjuster 114 is connected with one or more of the light source 111, the lens 112 and the DOE113 to realize adjustment. The adjuster 114 is controlled by the processor to adjust one or more of the light source, lens, DOE to achieve flood or structured light illumination.

In some embodiments, the adjuster controls the movement and the focal length change of the lens 112 to implement different lighting, for example, the adjuster includes a voice coil motor, the lens is a zoom lens, the voice coil motor is used to control the zoom lens to zoom, if the current focal length is greater than the distance between the light source and the lens, the lens diverges the light beam emitted by the light source, and the diverged light beam is suitable for floodlight lighting after being diffracted by the DOE; if the current focal length is smaller than the distance between the light source and the lens, the lens focuses the light beam, and the focused light beam can be used for structured light illumination after being diffracted by the DOE. Therefore, the single lighting module can have two functions of floodlighting and structured light illumination by controlling the focal length of the lens by using the adjuster. According to the requirement of practical application, the illumination mode required by the current application is transmitted to the adjuster in the form of signals, and the adjuster controls the focal length of the lens to change accordingly, so that the corresponding illumination can be realized.

In some embodiments, the adjuster achieves different illumination by controlling the DOE. For example, two different diffraction patterns are arranged on the DOE and are respectively used for generating flood illumination and structured light illumination, the diffraction patterns determine the mode of copying and expanding the diffracted light beams, when the included angle between the adjacent diffraction light beams is smaller than or equal to the divergence angle of the incident light beams on the DOE, the fact that the copying light beams are mutually adjacent or overlapped can be achieved, and therefore the flood illumination is generated, and when the included angle between the adjacent diffraction light beams is larger than the divergence angle of the incident light beams on the DOE, the fact that the copying light beams are arranged at intervals can be achieved, and the spot patterned structured light illumination is generated. Two kinds of diffraction patterns are configured on the same lens substrate at the same time, and in practical use, according to specific application requirements (floodlighting or structured light illumination), the regulator can correspond the corresponding diffraction patterns with the light source by controlling the DOE in the modes of moving, rotating and the like so as to realize floodlighting or structured light illumination. Such as: the same incidence plane of the DOE is divided into a left part and a right part, the left part and the right part are respectively provided with different diffraction patterns for generating floodlight illumination and structured light illumination, and the corresponding diffraction patterns correspond to the light source by controlling the horizontal movement of the DOE through the regulator. Or different diffraction patterns are arranged on two adjacent surfaces of the DOE and are used for generating floodlight illumination and structured light illumination respectively, and the regulator controls the DOE to rotate so as to enable the corresponding diffraction patterns to correspond to the light source.

In some embodiments, the modulator achieves different illumination by controlling the light sources. Reference may be made specifically to the following description of fig. 12, 13 and 14.

FIG. 12 is a schematic view of a light source according to one embodiment of the invention. The light source is composed of a substrate 121, a first sub light source 123 and a second sub light source 122, the substrate may be a semiconductor substrate, the first sub light source 123 and the second sub light source 122 are disposed on the substrate, and a typical light source is, for example, a VCSEL array chip light source. The first sub light source 123 is different from the second sub light source 122 in one of light emitting area, beam divergence angle, and the like. In one embodiment, the light-emitting area of the second sub-light source 122 is small, and when the light-emitting area is diffracted by the DOE and projected to a space with a significant gap between adjacent light beams, so as to realize structured light illumination, the light-emitting area of the first sub-light source 123 is large, and the light beams emitted by the first sub-light source are diffracted and split by the DOE to form adjacent or overlapped light beams so as to form a floodlight pattern; in some embodiments, the divergence angle of the light beam emitted by the second sub-light source 122 is small, such that the divergence angle of the incident light beam incident on the DOE is smaller than the angle between adjacent diffracted light beams, such that there is a significant gap between the light beams in the pattern, thereby forming a speckle pattern, and the divergence angle of the light beam emitted by the second light source 123 is large, such that the divergence angle of the incident light beam incident on the DOE is larger than the angle between adjacent light beams, such that adjacent or overlapping light beams in the pattern, thereby forming a flood pattern. It can be understood that the lighting module based on the light source may or may not include a lens, and when lighting is performed, the regulator in the module performs independent control on different sub-light sources in the light source to realize flood lighting or structured light lighting. In a specific application, when the floodlight/structured light illumination is required to be realized, the processor in the device transmits a signal to the regulator and controls the regulator to regulate so as to realize the floodlight/structured light illumination.

FIG. 13 is a schematic view of a light source according to yet another embodiment of the present invention. Unlike the light source of fig. 12, the first sub-light sources 132 and the second sub-light sources 133 are each in the form of an array on the substrate 131. It is understood that the first sub-light sources for realizing flood lighting and the second sub-light sources for realizing structured light lighting may be the same in number or may be different; the first sub-light sources and the second sub-light sources can be distributed separately and uniformly or distributed in a crossed mode. In one embodiment, only 1 first sub-light source is used for flood lighting, while a plurality of second sub-light sources are used for structured light illumination. The first light source and the second light source may be on the same substrate or on different substrates.

In some embodiments, the first sub-light source and the second sub-light source may also be light sources with the same light emitting property, and in the lighting module based on the light sources, the flood lighting and the structured light lighting are realized by arranging lenses with different properties and the light sources. Fig. 14 is a schematic diagram of a floodlight and structured-light illumination module according to another embodiment of the present invention, which comprises a light source composed of a substrate 141, a first sub-light source 143, a second sub-light source 142, a lens composed of a first lens 145, a second lens 144, and a DOE 146. The lens here may also be a microlens array MLA, where the microlens units in the MLA correspond to the sub-light sources in the light source array. The first sub-light source 143 can realize flood illumination after being diffracted by the DOE146 through the first lens 145, and the second sub-light source 142 can realize structured light illumination after being diffracted by the DOE146 through the second lens 144. The adjuster in the module can realize the flood lighting or the structured light lighting of the module by controlling the on or off of the first sub-light source 143 and the second sub-light source 144. In some embodiments, the DOE with different properties is arranged in the lighting module to correspond to the first sub-light source and the second sub-light source, so that the flood lighting and the structured light lighting can be implemented. For example, a first DOE corresponding to a first sub-light source is adjacent to a beam when splitting the beam, and a second DOE corresponding to a second sub-light source is spaced apart from the adjacent beam when splitting the beam, so as to implement flood lighting and structured light illumination, where the first DOE and the second DOE can be fabricated on the same substrate.

In some embodiments, the first light source and the second light source have different wavelengths, such as near infrared light and far infrared light, except that the first light source and the second light source have different properties to generate flood light and structured light, respectively. Due to different wavelengths, the first light source and the second light source can be turned on simultaneously to realize the synchronous illumination of the floodlight and the structured light.

The illumination module is described above, and the invention further provides an imaging device based on the illumination module. FIG. 15 is a schematic diagram of an imaging apparatus according to one embodiment of the invention. The device comprises an illumination module 159, a processor 153 and a collection module 158, wherein the illumination module 159 illuminates the space by emitting light with a certain wavelength, and the collection module 158 generally comprises a filter corresponding to the wavelength so as to realize imaging of the light reflected by the object in the space. The lighting module 159 includes an adjuster 154, a light source 155, a lens 156, and a DOE157, and after the processor 153 sends out a corresponding lighting signal, the adjuster 154 adjusts one or more of the light source, the lens, and the DOE to achieve corresponding lighting, such as flood lighting or structured light lighting. The imaging module 158 includes an image sensor 151 and a lens 152, light reflected by an object in space passes through the lens 152 and is imaged on the image sensor 151, the image sensor 151 may be a CCD or a CMOS, and the image sensor 151 converts an optical signal into an electrical signal and transmits the electrical signal to the processor 153 for processing to form an image. The capture module 151 may also include an image processor, such as a DSP, and the electrical signal is processed by the DSP to form an image and then transmitted to the processor. The processor 153 realizes the floodlight image acquisition and the structural light spot pattern acquisition of the imaging device through the control of the illumination module 159 and the acquisition module 158. In addition, the processor 153 may further calculate a depth image using the speckle pattern. In one embodiment, the processor may also fuse the depth image with the flood image to output an image containing both depth and texture information.

For the situation of floodlight illumination and structured light illumination synchronous illumination, a plurality of collecting modules can be arranged to synchronously collect floodlight images and structured light images. Preferably, in a single acquisition module, the optical filter allowing the first light source and the second light source to have corresponding wavelengths is configured to realize synchronous acquisition of the floodlight and the structured light information on a single image sensor, and the floodlight image and the structured light image are segmented through post-image processing.

Problems are often encountered when using imaging devices for image acquisition. For example, for the collection of a floodlight image, when the ambient light also has a light beam with the same wavelength as the light source and the ambient light changes obviously, the collection of the floodlight image is affected; for depth image acquisition, for example, when the depth of the target changes significantly, the sizes of the spots at different depths of the target are different, which also affects the calculation accuracy of the subsequent depth image. The invention provides an imaging device based on dynamic illumination. The imaging device can realize that: dynamic projection under flood lighting, dynamic projection under structured light, and dynamic switching projection between flood lighting and structured light.

FIG. 16 is a schematic view of a dynamic projection according to one embodiment of the invention. Taking the projection of the structural light spot pattern as an example (also applicable to flood lighting), in the process of collecting images by using the collecting module, the processor controls one or more of a light source, a lens and a DOE in the lighting module to realize dynamic lighting, in one embodiment, the processor controls the regulator to realize dynamic lighting, so that a plurality of images are collected, and finally, the processor fuses the collected images to generate a high-quality image.

In one embodiment, the adjuster is used to control the focal length of the lens to focus at different distances in the target space and simultaneously acquire corresponding images, such as

images

161, 162, 163 of FIG. 16, acquired at different distances, in which when a portion of the target object is located directly near the plane of the current focal length, the spots projected onto that portion are most concentrated, the corresponding spots in the acquired image have the highest contrast (e.g., spot 166), and the spots not at the focal plane have a relatively lower contrast (e.g., spot 165). After acquiring multiple images, a single high quality image 164 can be obtained by identifying the speckle pattern and a fusion algorithm.

In one embodiment, the processor may be used to control the adjustment device to adjust the illumination module during the single frame image capture period, i.e., the illumination module continuously changes its illumination state during the exposure time of the single frame image, so that the captured image has better image quality than the unique illumination. Compared with the multi-frame image fusion mode, the mode does not need subsequent calculation. For example, for the flood lighting, in the above embodiment, the lighting mode of filling the illuminated space is covered by copying and expanding the light beams, and since the intensity distribution of the single light beam and the intensity distribution among the light beams are difficult to be completely uniform, the effect of the flood lighting cannot be optimal, so that when the flood lighting is performed, in a single-frame exposure period of the image sensor, the processor is used for controlling the changes of factors such as the focal length of the lens in the lighting module, the power of the light source and the like, so that the intensity in the illuminated space is dynamically changed, and the problem of uneven illumination intensity distribution caused by the single lighting can be solved. In addition, for structured light illumination, the problem of focusing of targets in space at different distances is also faced, that is, the distances are different, the contrast of spots is different, and the contrast in a structured light image collected under a single illumination condition is greatly different. Aiming at the problem, the processor can be used for controlling the change of factors such as the focal length of a lens in the illumination module and the like in a single frame exposure period of the image sensor so as to increase the contrast of spots in the finally collected structured light image.

The foregoing is a more detailed description of the invention in connection with specific/preferred embodiments and is not intended to limit the practice of the invention to those descriptions. It will be apparent to those skilled in the art that various substitutions and modifications can be made to the described embodiments without departing from the spirit of the invention, and these substitutions and modifications should be considered to fall within the scope of the invention.

Claims

1. A lighting module, comprising:

a light source for emitting a light beam;

a lens for diverging or converging the light beam;

a diffractive optical element that replicates and expands the light beam to an illuminated space;

a processor connected to and controlling one or more of the light source, lens, diffractive optical element to achieve flood or structured light illumination;

the lens is a zoom lens, and the processor is used for controlling the focal length of the lens to be larger than the distance between the light source and the lens so as to realize floodlighting; or controlling the focal length of the lens to be smaller than the distance between the light source and the lens to realize structured light illumination.

2. A lighting module, comprising:

a light source for emitting a light beam;

a lens for diverging or converging the light beam;

the diffraction optical element comprises a first diffraction pattern and a second diffraction pattern, and an included angle between adjacent diffraction light beams formed after diffraction by the first diffraction pattern is not larger than a divergence angle of an incident light beam so as to realize floodlight illumination; and an included angle between adjacent diffraction light beams formed after diffraction by the second diffraction pattern is larger than a divergence angle of the incident light beams, so that structured light illumination is realized.

3. A lighting module, comprising:

a light source for emitting a light beam;

a lens for diverging or converging the light beam;

the light source comprises a first sub-light source and a second sub-light source, the processor controls the first sub-light source to emit a first sub-light beam, and the first sub-light beam is copied and expanded by the diffractive optical element to cover and fill the illuminated space so as to realize flood illumination; and the processor controls the second sub-light source to emit a second sub-light beam, and the second sub-light beam is copied and expanded by the diffraction optical element to form spot-patterned structured light for illumination.

4. The lighting module of claim 3, wherein the light source comprises an array light source comprising a substrate, the first sub-light source and the second sub-light source being disposed on the substrate.

5. The lighting module of claim 3, wherein the first sub-light source and the second sub-light source differ in one or more of light emitting area, divergence angle, and number.

6. The illumination module of claim 3, wherein the lens is a microlens array, and the microlens units in the microlens array correspond to the sub-light sources.

7. An image forming apparatus, comprising:

a lighting module as claimed in any one of claims 1 to 6, for providing flood or structured light illumination;

the processor is connected with the lighting module and the image sensor, controls the lighting module to acquire a floodlight image by using the image sensor under floodlight illumination, and controls the lighting module to acquire a structured light image by using the image sensor under structured light illumination.

8. The imaging apparatus of claim 7, wherein the processor calculates a depth image based on the structured light image.

9. The imaging apparatus of claim 8, wherein the processor is to fuse the depth image and the flood image.