Surround view imaging system with integrated wide angle illuminator

Abstract

The present invention relates to a surround view imaging system for three-dimensional (3D) imaging of the surroundings of the system, and in particular to a surround view imaging system comprising an integrated wide angle illuminator. The surround view imaging system according to the invention comprises an imager (10) and an illuminator (20); wherein the illuminator (20) comprises a light source (24) and a diffuser (30), the diffuser providing illumination light (A) having a batwing-shaped intensity distribution, and wherein the illumination light (A) is directed towards the imager (10) in a vertical direction; and a deflector (38) located in the vertical direction between the light source (24) and the imager (10), configured to redirect the illumination light (A) from the vertical direction to a substantially horizontal direction in the field of view (FOV10) of the imager, where the field of view (FOV20) of the illuminator and the field of view (FOV10) of the imager at least partially overlap in the surroundings of the system.

Description

Technical Field

[0001] The present invention relates to a surround view imaging system for three-dimensional (3D) imaging of the surroundings of a system, and more particularly to a surround view imaging system including an integrated wide-angle illuminator. Background Art

[0002] For 3D imaging systems or sensors capable of locating objects in the 3D surroundings of a system, there are different methods available based on various technologies such as light detection and ranging (LiDAR), time-of-flight (ToF, direct and indirect versions), amplitude or frequency modulation illumination, structured light, etc. Such systems are typically present in autonomous mobile robots (AMRs), industrial mobile robots (IMRs), and automated guided vehicles (AGVs) such as forklift trucks, lift trucks, automobiles, and drones for collision avoidance, obstacle detection, passenger monitoring, and viewing restricted areas of machines and robots. Surround view imaging systems can also be used in collaborative robots, security, and surveillance camera applications.

[0003] A typical TOF depth sensing system consists of: an illumination system including beam forming (e.g., forming an electronic beam and / or a light beam in a temporal and / or spatial manner); an imaging system including receiving optics (e.g., a single lens or a lens system / objective); and an image detector for image detection. Additionally, evaluation electronics can be included for calculating distances and possibly setting some alarms based on the detected image signals. The illuminator typically emits modulated light or pulsed light. The distance to an object can be calculated based on the time it takes for the emitted light to travel from the illumination system to the object and back to the imaging system. Beam forming can be achieved by beam shaping optics included in the illumination system. The beam shaping optics and the receiving optics can be separate optical elements (one-way optics) or the beam shaping optics and the receiving optics can share individual, multiple, or all components of the corresponding optics (two-way optics).

[0004] When an imaging solution based on wide-angle lens optics is combined with a fixed array detector for image detection (e.g., CMOS, CCD, photodiode array, etc.), the moving and thus particularly error-prone scanner unit can be completely avoided in the system.

[0005] By using a wide-angle lens (e.g., a fish-eye lens or a rectilinear lens) as the first lens of the lens system in a corresponding imaging system, a surround view image can be generated. The wide-angle lens can have a field of view (AOV) of more than 180°, e.g., the lens can provide the maximum zenith angle range of the image in the vertical direction. A lens with an AOV of more than 180° is called an ultra-wide-angle lens. A field of view of up to about 300° can be achieved. In a typical axially symmetric imaging system, the azimuth range that can be imaged (e.g., in the horizontal direction) is usually 360°, thus allowing a surround view to be achieved in the azimuth direction. Therefore, an ultra-wide-angle lens can image a solid angle Ω of up to about 3π steradians. Wide-angle lenses typically exhibit strong curved barrel distortion, while rectilinear lenses can be optically corrected to some extent. Optical barrel distortion correction can also be included in the design of the relevant lens system. Therefore, a lens system with an AOV greater than 180° is called an ultra-wide-angle lens system.

[0006] Especially for AMR, IMR, and AGV applications, a high zenith angle in the range between 60° and 120° is usually required for an azimuth range Δθ of 360° in the horizontal plane. For such purposes, a fish-eye lens can usually be used in an upright position. However, conventional fish-eye lenses have several drawbacks, such as high incident angles and related coating problems. Another problem is that the very wide field of view combines low resolution, low f-number, and vignetting caused by off-axis illumination.

[0007] An optimized fish-eye type lens (e.g., a catadioptric lens system) with a wide horizontal field of view (FOV) but a limited vertical FOV usually images the surrounding environment of the system onto a circular ring in the image plane of the imaging system. A two-dimensional array detector (e.g., CMOS, CCD, photodiode array, etc.) that can completely cover the circular image ring can be used to detect the image of the surrounding environment. However, for standard fish-eye lenses and other lenses without an optimized FOV region, the readout of the image detector may also be limited to a specific zenith angle or azimuth range, and in particular, also limited to a circular ring corresponding to the circular image region of the optimized fish-eye type lens. Through this spatially limited detection, incorrect depth signals caused by multiply reflected illumination light or image detector saturation can be avoided.

[0008] The illumination light can be provided by an illuminator which is preferably capable of illuminating the entire FOV of the imager through the corresponding FOV of the illuminator. However, it may ultimately be necessary to have a partial overlap between the two FOVs. Existing systems aligned in the upright position typically use multiple light sources to illuminate a 360° FOV in the horizontal direction (i.e., in the horizontal FOV) or use mechanical elements (e.g., MEMS) to sequentially illuminate the scene in the surroundings of the system. However, due to the limited durability and resilience of mechanical systems, their use should be avoided, especially in applications in robots and other autonomous devices. Using multiple light sources increases the manufacturing cost and complexity of the system.

[0009] Accordingly, the object problem of the present invention relates to providing an illuminator that allows for illuminating the 360° FOV of a surround view imaging system at low cost, which is less complex and provides high durability and resilience compared to prior art illuminators. Summary of the Invention

[0010] The present invention solves this objective problem by providing a surround view imaging system as defined in claim 1.

[0011] A surround view imaging system for imaging the surroundings of a system according to the present invention includes an imager and an illuminator; wherein, the illuminator is adapted to illuminate the surroundings of the system in the field of view of the illuminator such that the illumination light reflected by the surroundings can be imaged as imaging light by the imager in the field of view of the imager, wherein, the illuminator and the imager are arranged overlappingly in a vertical direction substantially parallel to the vertical axis of the system (e.g., along the optical axis of the imager), wherein, the system is configured to allow circumferential imaging (the imaging height is defined by the vertical field of view in the zenith angle direction) in a horizontal plane perpendicular to the vertical axis in the field of view of the imager (i.e., a 360° horizontal FOV in the azimuth direction). The illuminator includes a light source and a diffuser that provides illumination light having a batwing intensity distribution, wherein, the illumination light is directed towards the imager in the vertical direction; and a deflector that is located between the light source and the imager in the vertical direction and is configured to redirect the illumination light from the vertical direction to a substantially horizontal direction in the field of view of the imager (including divergent beams in the zenith direction above and below the central direction of the substantially horizontally deflected light to allow full addressing of the vertical FOV), wherein, the field of view of the illuminator and the field of view of the imager at least partially overlap in the surroundings.

[0012] An imager should be understood as a device capable of receiving, focusing, and detecting imaging light entering the imager from the imager's surrounding environment. The imager thus typically includes at least one (preferably a 360-degree annular circumference) entrance aperture adjacent to the surrounding environment, a lens or other optical element for generating an image of the surrounding environment, and a related image detector for detecting the generated image of the surrounding environment for further processing. Since the generation of the image is the most important aspect in ensuring good image quality, instead of using a single lens or optical element, a lens system (or generally a system of optical components) for correcting the occurring aberrations can be used in the imager. The imager can be a device that uses ambient light (e.g., 3D visible light or infrared light) for imaging or can be particularly adapted to image reflected light (illumination light) from an illumination source or illuminator as imaging light (e.g., flash LIDAR).

[0013] Preferably, an imager including a lens system (or a single lens) is also adapted to image (axially symmetric imaging) around the optical axis of the lens system in an image in an image plane perpendicular to the optical axis of the lens system. However, some components of the lens system can also be arranged off-axis, or the image plane can be moved and / or tilted relative to the optical axis of the optical system. Such embodiments allow an increase in the flexibility of matching the FOV of the imaging system to a specific region of interest (ROI), especially in TOF depth sensing applications.

[0014] An illuminator should be understood as a device capable of emitting illumination light in the illuminator's surrounding environment. In a surround-view imaging system, the illuminator can provide bright light pulses that are reflected by objects in the surrounding environment and then can be imaged as imaging light by an imager with a related image detector (e.g., flash LIDAR). However, the illuminator can also be configured to provide a spatially and / or spectrally well-defined light field that is also reflected by objects in the illuminator's surrounding environment and subsequently can be imaged (e.g., LiDAR / LaDAR or TOF). Thus, the term "illuminator" is not limited to a specific type of light source or a specific type of ambient illumination. Surround-view imaging systems of the type discussed are generally referred to as active imaging systems. In contrast, passive surround-view imaging systems are designed to use only ambient light for imaging and thus they do not require an illuminator as an essential component.

[0015] The FOV of the illuminator and the FOV of the imager must at least partially overlap to allow the reflected illumination light to be received as imaging light. However, to avoid saturation and overexposure of the related image detector, these two FOVs can be adapted to be different from each other or include different FOV regions. However, it is highly preferred that the FOV of the imager and the corresponding FOV of the illuminator are the same or at least have only a very small distance from each other to avoid complex angle corrections for evaluation.

[0016] Preferably, the illuminator is arranged vertically above the lens of the imager (e.g., a 360° lens as the first lens of the imager). The field of view of the lens and the deflector preferably includes an azimuth angle θ of 360° in the horizontal plane (i.e., providing a 360° horizontal FOV). However, the present invention is not limited to 360° surround view imaging systems. Depending on the specific requirements of the application, the effective FOV of the corresponding surround view imaging system can also be correspondingly limited.

[0017] Preferably, the diffuser is arranged above the emitter surface of the semiconductor light source. The semiconductor light source can be a vertical cavity surface emitting laser (VCSEL). The emitter surface can be a flat surface. A planar emitter can provide a beam with a symmetric beam profile. A symmetric beam profile is preferred because in this case, the diffuser can also be symmetric and does not have to be optimized and carefully aligned to a specific axis of the emitter during system assembly.

[0018] Preferably, the diffuser is configured to convert a circular input beam into a substantially annular output beam (a rotationally symmetric batwing intensity profile), wherein the maximum intensity in the annular region of the output beam with high intensity exceeds the maximum intensity in the central region of the annular output beam with low intensity by at least a factor of 2. For an ideal batwing intensity distribution, the intensity in the central region of the annular output beam is zero, and thus all the intensity of the beam is located in the annular region surrounding the central region. However, an actual batwing intensity distribution typically still has a non-zero intensity distribution in the inner region of the annular output beam, which is caused by non-perfect beam shaping or transformation. However, a typical batwing intensity distribution may be characterized by two independent high-intensity peaks (with a specific width, e.g., FWHM width) in the beam cross-section, and they are rotationally symmetric about the center of the annular beam distribution.

[0019] Preferably, the diffuser is substantially a half-shell, which includes a circular wing structure that forms a crown around the vertex of the diffuser. The circular wing structure and the crown can be formed symmetrically about the central axis of the diffuser. The interior of the half-shell diffuser is preferably filled with a solid refractive index material. However, a gas or liquid refractive index material can also be used. The interior of the half-shell diffuser can also be unfilled (evacuated) or integrally formed with the material of the half-shell structure (hemispherical structure). In an alternative preferred embodiment, the diffuser can be a diffractive optical element (DOE). These optical elements can even provide a symmetric output beam from an asymmetric input beam. Additional beam shaping features can be integrated in the DOE. For surface relief DOEs, microstructural replication techniques such as imprinting, molding, and casting can be used for simple and cost-effective manufacturing.

[0020] Preferably, the external shape of the deflector corresponds to a conical section (e.g., the section of a right or oblique cone) or a freeform shape. While a deflector based on a relatively simple conical section may reflect the beam profile provided by the diffuser only at limited angles, a freeform shape is intended to allow for the definition of spatially dependent deflection angles within the full FOV. Additionally, a deflector based on a freeform shape can be used for further beam shaping and further modifying the intensity distribution of the incident beam. In particular, the batwing-shaped intensity distribution of the diffuser and the angular dependence of the deflection of the deflector can be configured such that uniform illumination of the field of view of the imager is achieved collaboratively.

[0021] Preferably, the diffuser and the deflector are configured to prevent directly scattered illumination light from entering the imager. This can be achieved by ensuring that light cannot enter the imager without being reflected by the surroundings of the system.

[0022] Preferably, the intensity of the illumination light in the field of view of the illuminator has a maximum at an azimuth angle θ between 80° and 90°, and a full width at half maximum (FWHM) Δθ at an azimuth angle between 10° and 40°. FWHM . These angular ranges are typically required for robotic and other autonomous system applications.

[0023] Preferably, the image detector can have an active detection area adapted to the image size or a specifically defined region of interest (ROI). Since the central region of the image may be irrelevant for imaging and may correspond to zenith angles outside the effective FOV of the imager, these regions of the image detector can be completely omitted or ignored from the image readout or by selective mapping to the effective active detector surface. This has the advantage that the passive regions of the image detector do not saturate due to accidentally captured ambient light and scattered light. Additionally, since it is not necessary to read out unimportant detector regions, for a specific detector configuration, the effective frame rate of a particular type of detector can be increased. With a higher frame rate, the accumulation of photo-induced charge carriers in the individual pixels of the detector can be reduced, such that the signal-to-noise ratio (SNR) of the detector can be optimized for image detection over a wide dynamic range without using high dynamic range (HDR) techniques.

[0024] The illuminator according to the present invention enables the illumination of the 360° horizontal FOV of a surround view imaging system with only a single light source. The single light source can be mounted above the optical axis of the imager, directly on top of the first 360° lens of the imager. It can use a customized extreme batwing-shaped diffuser distribution to illuminate the deflector, which substantially deflects the light rays into the 360° horizontal FOV. Any undeflected light can be used to illuminate the lower part of the scene in the surroundings within the vertical FOV of the imager. The deflected light can then be used to illuminate the higher part of the scene in the surroundings.

[0025] The combination of a customized diffuser and a customized deflector can be optimized for a specific required vertical FOV and prevent stray light from entering the 360° lens. Using only a single light source simplifies the electrical / thermal design, calibration process, and timing alignment of the surround view imaging system (especially in TOF systems). Since only a single light source is sufficient to illuminate the 360° horizontal view, a smaller form factor, less critical electrical / thermal requirements, and lower costs can be achieved. Since timing alignment between different light sources, which is usually used in prior art illuminator designs, is no longer required, system performance can be improved.

[0026] Further preferred embodiments of the present invention result from the features recited in the dependent claims.

[0027] Unless otherwise specified in particular circumstances, the various embodiments and aspects of the present invention mentioned in this application can be combined with each other to obtain advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Hereinafter, the present invention will be described in further detail with reference to the drawings. The examples given are suitable for describing the present invention. The drawings show:

[0029] Figure 1 is a schematic diagram of an exemplary embodiment of an imager according to the prior art;

[0030] Figure 2 is a) a schematic diagram of a light source with a diffuser according to the present invention and b) an exemplary batwing intensity distribution generated by a surround view imaging system according to the present invention;

[0031] Figure 3 is a schematic diagram of an exemplary embodiment of a surround view imaging system according to the present invention; and

[0032] Figure 4 is a schematic diagram for optimizing the image resolution and FOV of an imager of a surround view imaging system using different alignments of images on a detector. DETAILED DESCRIPTION

[0033] Figure 1 A schematic diagram of an exemplary embodiment of an imager 10 according to the prior art is shown. The optical path of the imaging light B received from the imaging area and calculated within the optical system of the imager 10 is shown. The imager 10 includes a lens stack having a plurality of fisheye lenses, and the plurality of fisheye lenses form a continuous field of view FOV10 of the imager. For example, the imaging area can cover a zenith angle between 60° and 120°. In the inset of this figure, the definition of the zenith angle and the azimuth angle θ with respect to the optical axis / vertical axis 14 of the imager 10 is shown. and the definition of the azimuth angle θ.

[0034] The exemplary lens system 10 shown is all-refractive and can consist of 10 glass lenses, including a first lens 18 for collecting imaging light B. However, the number and type of materials of the lenses can vary. In particular, the shown lens system is designed for a 20° vertical FOV starting from a zenith angle of 80°. All received light beams are focused such that an image 16 of the surrounding environment is formed on a common image plane / detector 12, which can be aligned perpendicular to the optical axis 14 of the imager 10.

[0035] The image 16 projected onto the image plane / detector 12 can be an annular image, but it can also be smaller, larger, or have a different shape, depending on the illumination and lens design of the imager 10. Additionally, the detector setup or image detector readout can be limited to a specific ROI, thus restricting the volume of the surrounding environment that can be imaged.

[0036] Figure 2 a) A schematic diagram of a light source 24 with a diffuser 30 according to the present invention and b) an exemplary bat-wing intensity distribution generated by a surround-view imaging system according to the present invention are shown. The light source 24 can be, for example, a single light-emitting diode (LED) or a diode laser (e.g., VCSEL), which can be mounted on a substrate 22. The diffuser 30 can be arranged above the emitter surface of the light source 24. The light source 24 and the diffuser 30 should provide illumination light with a bat-wing intensity distribution. Thus, the diffuser 30 can be configured to convert the circular input beam of the light source 24 into a substantially annular output beam, wherein the maximum intensity in the annular region of the output beam with high intensity significantly exceeds the maximum intensity in the central region of the annular output beam with low intensity, preferably by at least a factor of 2. The circular input beam can be a diverging beam. The substantially annular output beam can be a diverging, collimated, or focused beam.

[0037] The diffuser 32 can be substantially a half-shell including a circular wing structure 32. Since the bat-wing intensity distribution is preferably centrosymmetric about the light propagation axis, the wing structure 32 can form a (centrosymmetric) crown 34 around the vertex of the diffuser 30. However, in some embodiments, the wing structure 32 can be non-centrosymmetric to provide a non-centrosymmetric bat-wing intensity distribution, i.e., a bat-wing intensity distribution optimized for at least one specific spatial direction. This can be useful for specific applications where the illumination light only has to be directed to a very limited area. The interior 36 of the half-shell-shaped diffuser 30 is preferably filled with a solid refractive index material. However, a gas or liquid refractive index material can also be used. The interior 36 of the half-shell-shaped diffuser 30 can also be unfilled (evacuated) or the interior 36 can be integrally formed with the material of the half-shell basic structure (hemispherical structure).

[0038] An exemplary batwing-shaped intensity distribution according to the invention b) shows in cross-section the relative intensity at zenith angle for a surround view imaging system according to the invention. A typical "batwing" starts at a zenith angle of about 40° Ends at a zenith angle of about 110° and at a zenith angle of about 85° The "bat wing" distribution has a full width at half maximum (FWHM) value of about 40°. It should be noted that this figure does not refer to a bat wing intensity distribution directly generated by the diffuser according to the invention, but rather represents the final intensity distribution in the FOV of the luminaire. However, in addition to the specifically demonstrated angular dependence, the general structure of the bat wing intensity distribution can also be clearly seen.

[0039] Figure 3 A schematic diagram of an exemplary embodiment of a surround view imaging system according to the present invention is shown. The surround view imaging system comprises an imager 10 and an illuminator 20; wherein the illuminator 20 is adapted to illuminate the surroundings of the system in the field of view FOV20 of the illuminator, so that illumination light A reflected by the surroundings can be imaged by the imager 10 in the field of view FOV10 of the imager as imaging light B, wherein the illuminator 20 and the imager 10 are arranged overlapping in a vertical direction parallel to a vertical axis 14 of the system, wherein the system is configured to allow circumferential imaging in a horizontal plane perpendicular to the vertical axis 14 in the field of view FOV10 of the imager.

[0040] The illuminator 20 includes a light source 24 and a diffuser 30, the diffuser providing an illumination light A having a bat-wing-shaped intensity distribution, wherein the illumination light A is directed toward the imager 10 in a vertical direction; and a deflector 38, which is located between the light source 24 and the imager 10 in a vertical direction and is configured to redirect the illumination light A from the vertical direction to a substantially horizontal direction in the field of view FOV10 of the imager, wherein the field of view FOV20 of the illuminator and the field of view FOV10 of the imager may at least partially overlap in a surrounding environment.

[0041] The imager 10 corresponds to Figure 1 The embodiment shown, however, the invention is not limited to such an embodiment and other system designs compatible with the general idea of ​​the invention as defined in the appended claims may also be implemented alternatively. The same considerations apply to the light source 24 and the diffuser 30, which correspond to Figure 2 a is an embodiment shown in FIG. Figure 1 and Figure 2 , and therefore will not be explained in detail here.

[0042] The illuminator 20 can be arranged vertically above the lens 18 of the imager 10, where the fields of view of the lens 18 and the deflector 28 can include an azimuth angle θ of 360° in the horizontal plane. The batwing intensity distribution of the diffuser 30 and the angular dependence of the deflection of the deflector 38 can be configured such that uniform illumination of the field of view FOV10 of the imager can be achieved collaboratively. The diffuser 30 and the deflector 38 can be configured to prevent directly scattered illumination light A from entering the imager 10. In a preferred embodiment, the intensity of the illumination light in the field of view FOV20 of the illuminator can have a maximum value at an azimuth angle θ between 80° and 90°, and a full width at half maximum (FWHM) Δθ at an azimuth angle between 10° and 40° FWHM . Preferably, the projection of the surrounding environment on the image plane (detector plane) 16 can be adjusted to different ROIs.

[0043] Figure 4 A schematic diagram showing the use of different alignments of the images on the detector to optimize the image resolution and FOV of the imager of a surround view imaging system. The projection of the scene on the detector can be adjusted to obtain a smaller but higher-resolution horizontal / vertical FOV. While in example a), the FOV of the imager is fully imaged on the effective surface of the detector, example b) shows an alignment where the horizontal FOV is slightly reduced to θ = 270° at a detector with an effective surface of the same size. Example c) shows another example with a smaller detector and a different aspect ratio. On this particular detector, the horizontal FOV is even further reduced to θ = 180°. However, the full vertical FOV can still be covered by the detector.

[0044] List of reference numerals

[0045] 10 Imager

[0046] 12 Image detector / plane

[0047] 14 Optical / vertical axis

[0048] 16 Image

[0049] 18 Lens (e.g., 360° lens as the first lens of a lens system)

[0050] 20 Illuminator

[0051] 22 Substrate

[0052] 24 Light source

[0053] 30 Diffuser

[0054] 32 Wing structure

[0055] 34 Crown

[0056] 36 Inside

[0057] 38 Deflector

[0058] θ Azimuth angle (related to the horizontal field of view, e.g., 360°)

[0059] Zenith angle (related to the vertical field of view, e.g., between 60° and 120°)

[0060] A Illumination light

[0061] B Imaging light

[0062] AOV Angle of view

[0063] FOV10 Field of view of the imager

[0064] FOV20 Field of view of the illuminator

Claims

1. A surround view imaging system for imaging the surrounding environment of a system, comprising: an imager (10) and an illuminator (20); wherein the illuminator (20) is adapted to illuminate the surrounding environment of the system in a field of view (FOV20) of the illuminator such that illumination light (A) reflected by the surrounding environment can be imaged as imaging light (B) by the imager (10) in a field of view (FOV10) of the imager, wherein the illuminator (20) and the imager (10) are arranged overlappingly in a vertical direction parallel to a vertical axis (14) of the system, and wherein the system is configured to allow circumferential imaging in a horizontal plane perpendicular to the vertical axis (14) in the field of view (FOV10) of the imager; characterized in that the illuminator (20) comprises: a light source (24) and a diffuser (30), the diffuser providing illumination light (A) having a batwing intensity distribution, wherein the illumination light (A) points in the vertical direction towards the imager (10); and a deflector (38), the deflector being located in the vertical direction between the light source (24) and the imager (10), configured to redirect the illumination light (A) from the vertical direction to a substantially horizontal direction in the field of view (FOV10) of the imager, wherein the field of view (FOV20) of the illuminator and the field of view (FOV10) of the imager at least partially overlap in the surrounding environment.

2. The surround view imaging system according to claim 1, wherein The illuminator (20) is arranged above a lens (18) of the imager (10) in the vertical direction, wherein the fields of view of the lens (18) and the deflector (28) preferably include an azimuth angle θ of 360° in the horizontal plane.

3. The surround view imaging system according to claim 1 or 2, wherein The diffuser (30) is arranged above a emitter surface of the semiconductor light source (22).

4. The surround view imaging system according to any one of the preceding claims, wherein, The diffuser (30) is configured to convert a circular input beam into a substantially annular output beam, wherein the maximum intensity in the annular region with high intensity of the output beam exceeds the maximum intensity in the central region with low intensity of the annular output beam by at least a factor of 2.

5. The surround view imaging system according to claim 4, wherein The diffuser (32) is substantially a half-shell, which includes a circular wing structure (32) that forms a crown (34) around the apex of the diffuser (30), wherein the interior (36) of the half-shell-shaped diffuser 30 is preferably filled with a solid refractive index material; or wherein the diffuser (32) is a diffractive optical element.

6. The surround view imaging system according to any one of the preceding claims, wherein, The profile of the deflector (38) corresponds to the profile of a conical section or is a free-form shape.

7. The surround view imaging system according to any one of the preceding claims, wherein, The batwing intensity distribution of the diffuser (30) and the angular dependence of the deflection of the deflector (38) are configured to collaboratively achieve uniform illumination of the field of view (FOV10) of the imager.

8. The surround view imaging system according to any one of the preceding claims, wherein, The diffuser (30) and the deflector (38) are configured to prevent directly scattered illumination light (A) from entering the imager (10).

9. The surround view imaging system according to any one of the preceding claims, wherein, The illumination light intensity in the field of view (FOV20) of the illuminator has a maximum value at an azimuth angle θ between 80° and 90°, and a full width at half maximum Δθ at azimuth angles between 10° and 40° FWHM .

10. The surround view imaging system according to any one of the preceding claims, wherein, The image detector (12) can have an active detection area adapted to the image size or a specifically defined region of interest.

Images