Optical wireless devices and methods for designing optical arrangements

Abstract

An optical wireless device having a receiving device is configured to receive an optical wireless signal. The receiving device includes a photodetector for detecting the optical wireless signal and a plurality of optical systems having at least a first optical system having a first aperture size and a second optical system having a second, smaller aperture size. The optical systems are arranged side by side in essentially the same preferred direction. Each of the plurality of optical systems is configured to simultaneously direct light incident on the optical system to the photodetector. The photodetector has an optical axis, and the first optical system is arranged at a first distance from the optical axis and the second optical system is arranged at a second, greater distance from the optical axis.

Description

[Technical Field]

[0001] The present invention relates to an optical wireless device for receiving optical wireless signals, a communication system having such an optical wireless device, and a method for designing an optical arrangement for a receiving device of the optical wireless device.The present invention particularly relates to a high-efficiency compound lens setup for high dynamic range for optical wireless or optical cordless transmitter / receiver systems. [Background technology]

[0002] The receiver of an optical wireless or optical codec transceiver may be exposed to widely varying reception levels. On the one hand, high optical transmission power is required for long distances. However, increasing the transmission power also increases the minimum distance between transceivers or between transmitter and receiver. Below the minimum distance, the channel loss is so low that the receiver saturates and transmission is no longer possible. The range of distances between transmitter and receiver that can operate within specifications is defined as the transceiver's dynamic range. This distance range is limited below by the minimum distance and above by the maximum distance. A transceiver is particularly versatile if it has a large dynamic range.

[0003] There are various techniques for increasing the dynamic range of a link. Transmit power adjustment: At short distances, transmit power is adaptively reduced to avoid receiver saturation [1, 4]. However, this approach requires a driver circuit with adaptive control. The system also needs to know when to reduce or increase transmit power. This information is received from the subscriber's receiver. This approach is generally limited to an adjustment range of 3 dB to 20 dB.

[0004] Adjusting the electrical receiver: The electrical receiver can be adjusted, for example, by adjusting the gain of the transimpedance amplifier or by using additional adjustment at the input of the transimpedance amplifier [1, 6]. This approach is not always appropriate, for example, when saturation effects already occur in the photodetector. Such saturation effects are common in avalanche photodiodes (APDs), single-photon avalanche photodiodes (SPADs), and silicon photomultipliers (SiPMs). The internal gain of these detectors can be adjusted via the bias voltage, but only over a certain range until the internal gain reaches unity (the minimum value) or the effective photodiode capacitance no longer meets the specifications.

[0005] The use of one or more additional elements to attenuate the optical signal, such as mechanical shutters [2], variable apertures [5], variable lenses (electrowetting lenses, polymer lenses, etc.), polarization-based shutters (e.g., liquid crystal shutters / attenuators [2]). What all these approaches have in common is that additional elements are used in the system to affect the channel loss, particularly by increasing the channel loss, usually in the geometric near field. The additional components and additional controls required increase the complexity and cost of the system.

[0006] In optical systems, the transmitter and receiver may not be on the same optical axis. The field of view is chosen so that the receiver can barely see the transmitter at close range. This technique is very simple, but is usually limited to a dynamic range of 3 dB to 10 dB. This is especially important when the field of view is small. This technique is particularly sensitive to offsets perpendicular to the optical axis. For example, a receiver may receive a strong signal from a transmitter at a short distance, just within the evaluation range, but if the receiver is then offset further, say by 10 mm due to tolerances, the receiver may no longer be able to detect anything.

[0007] This concept can be extended so that the transmitter emits at larger angles (see [3]), and the receiver can also detect signals arriving at these larger angles. However, a drawback of this approach is that the power is not optimally utilized at the transmitter, since the receiver at a greater distance cannot detect this laterally emitted power. In addition, the receiver lens cannot be optimally designed for the actual acceptance angle, because it must collect radiation in the geometric near field even at larger emission angles. Therefore, the field of view is no longer well defined, and as a result, channel crosstalk with adjacent channels may occur. This approach is also sensitive to positioning tolerances between the transmitter and receiver.

[0008] Optical concepts can provide multiple receivers. These can have different saturation limits, for example by using different detectors (see [2]). One detector is used at close range and one at long range. This approach requires more hardware, as a second detector and additional amplifier electronics are also needed. Furthermore, both receiver channels must be combined or it must be determined which data stream to analyze.

[0009] Therefore, a solution is needed for efficient operation of optical wireless devices and for designing the necessary components that enable a high dynamic range between the transmitter and receiver of an optical wireless communication link. Summary of the Invention [Problem to be solved by the invention]

[0010] It is therefore an object of the present invention to provide a method for designing an optical arrangement for an optical wireless device, an optical wireless communication system, and a receiving device of an optical wireless device that enables efficient operation of the optical wireless device while simultaneously having a high dynamic range between the transmitter and receiver. [Means for solving the problem]

[0011] This object is solved by the subject matter of the independent claims.

[0012] The key concept of the present invention is the realization that saturation effects in the receiver's photodetectors can be reduced or avoided by providing the receiver with multiple optical systems that direct received light to the photodetectors. In the transmitter's geometrical near field, the photodetector receives only the transmitter's optical signal from a subset of the multiple optical systems, while in the geometrical far field, it receives the transmitter's optical signal from other optical systems or more of the multiple optical systems. This is achieved, for example, by different optical systems from the multiple optical systems having different distances from each other relative to the detector's optical axis, with the optical systems being arranged with essentially the same preferred direction. Based on the parallel arrangement, as the distance to the transmitter decreases, the optical systems become partially unilluminated or less illuminated, thus reducing their contribution to the total power at the photodetector and thus avoiding saturation effects. This achieves a small minimum distance or avoids the minimum distance. At the same time, the transmitter's high transmission power can be utilized in the geometrical far field, resulting in a high dynamic range with high efficiency.

[0013] In one embodiment, an optical wireless device is provided, comprising a receiving device for receiving an optical wireless signal. The receiving device includes a photodetector for detecting or receiving the optical wireless signal and a plurality of optical systems, the plurality of optical systems having at least a first optical system having a first aperture size and a second optical system having a second, smaller aperture size. The optical systems are arranged side by side in essentially the same preferred direction. Each of the plurality of optical systems is configured to simultaneously direct light incident on the optical system to the photodetector. The photodetector has an optical axis, the first optical system is arranged at a first distance from the optical axis, and the second optical system is arranged at a second, greater distance from the optical axis.

[0014] According to one embodiment, there is provided an optical wireless device comprising a receiving device comprising a photodetector and configured to receive an optical wireless signal from an optical wireless transmitter, the receiving device being configured to receive the optical wireless signal in both the geometric near field and the geometric far field of the optical wireless transmitter and detect it without saturating it using the photodetector.

[0015] Further embodiments relate to optical wireless communication systems having the optical wireless devices described herein.

[0016] According to one embodiment, a method for designing an optical arrangement for a receiving device of an optical wireless device includes designing and positioning a plurality of optical systems relative to a transmitting device configured to provide an optical wireless signal, whereby the plurality of optical systems simultaneously deflect a received optical wireless signal so that at different distances between the receiving device and the transmitting device, different numbers of the plurality of optical systems contribute to a total optical power directed to a photodetector of the receiving device. The method further includes fabricating the plurality of optical systems in the designed and positioned arrangement.

[0017] Further advantageous embodiments are the subject matter of the dependent claims.

[0018] Particularly preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic cross-sectional side view of an optical wireless device according to one embodiment. [Figure 2] 1 is a schematic cross-sectional side view of an optical wireless communication system according to one embodiment. [Figure 3a] 1 is a schematic cross-sectional side view of an arrangement of a transmitting device and a receiving device in a geometric near field according to an embodiment described herein. [Figure 3b]FIG. 3B is a schematic cross-sectional side view of the same components as in FIG. 3a, but in the geometric far field. [Figure 4a] 1 is a schematic top view of an optical wireless device according to one embodiment. [Figure 4b] 4b is a representation of the device of FIG. 4a extended by a transmitting device on the opposite side. [Figure 4c] 4a and 4b are schematic partial perspective views of two devices according to one embodiment, which are mutual copies of each other; [Figure 4d] 1 is a schematic diagram of an optical wireless device according to an embodiment having receive optics with a substantially rectangular cross section according to an embodiment. [Figure 5] 1 is a schematic characteristic curve of received power at a photodetector for illustrating embodiments described herein; [Figure 6] 1 is a schematic front view of an optical wireless device according to an embodiment, comprising multiple secondary optical systems. [Figure 7] 7 is a schematic diagram of an exemplary total intensity as may be obtained with the optical arrangement of the optical wireless device of FIG. 6, according to one embodiment. [Figure 8] 1 is a schematic flow chart of a method according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Before the following embodiments of the present invention are described in more detail with reference to the drawings, it is pointed out that identical, functionally identical, or similarly acting elements, objects, and / or structures are provided with the same reference signs in different figures, and as a result, the descriptions of these elements shown in different embodiments are interchangeable or can be applied to one another.

[0021] The following embodiments are described with reference to numerous details. However, embodiments may be implemented without these detailed features. Moreover, for clarity, the embodiments are described using block diagrams instead of detailed illustrations. Furthermore, details and / or features of individual embodiments may be combined with each other unless expressly stated to the contrary.

[0022] The following embodiments refer to optical wireless signal or data transmission, which is also referred to as LiFi (Light Fidelity) in the context of the embodiments described herein. LiFi is a term such as IrDA (Infrared Data Association) or OWC (Optical Wireless Communication). This means that the terms "optical wireless data transmission," "optical cordless data transmission," and "LiFi" are used synonymously. Optical wireless data transmission is understood to mean transmitting electromagnetic signals through a free transmission medium, such as air or another gas or fluid. For example, wavelengths in the ultraviolet (UV) range of at least 100 nm and the infrared range, for example, up to 1550 nm, can be used for this purpose, although other wavelengths different from those used in wireless standards are also possible. Optical wireless data transmission should also be distinguished from optical fiber data transmission, which is implemented, for example, using optical waveguides or optical waveguide cables.

[0023] The embodiments described herein relate to near-field and / or far-field, which are interchangeably referred to as geometric near-field or geometric far-field.

[0024] The geometric near field is understood to be the region starting from the transmitter where, in addition to the transmitter emission angle, the position and size of the individual elements of the receiver and transmitter play a major role in the reception level of the optical wireless signal. In addition to the position and dimensions, the angular range of the optical system can also play a role. For example, a transmitter can emit an optical wireless signal in an angular range of -1° to +1°. If the receiver's reception angle is smaller than the transmission angle, for example, -0.5° to +0.5°, angular effects also result in losses, but these losses can be used as channel attenuation according to the present invention and are initially unaffected by spatial dimensions. In addition to the emission angle and reception angle, the lateral offset from the transmitter to the receiver and the spatial extent of the transmitter and receiver apertures also affect the geometric near field.

[0025] In contrast, the geometrical far field is understood to be another region, starting from the transmitter, in which the emission angle of the transmitter plays a major role and the dimensions and position of the receiver and transmitter components, especially the optics, play a lesser role. On the other hand, the geometrical far field can be understood as an arrangement in which the emission characteristics of the transmitter and the reception characteristics of the receiver can essentially be described by their emission and reception angles.

[0026] The transition between the geometrical near field and the geometrical far field is fluid.

[0027] 1 shows a schematic cross-sectional side view of an optical wireless device 10. The optical wireless device 10 includes a receiving device 12 configured to receive an optical wireless signal 14. The receiving device includes a photodetector 16, which may comprise a photodiode such as, for example, a PIN photodiode, an avalanche photodiode (APD), a single-photon avalanche photodiode (SPAD), and / or a silicon photomultiplier tube (SiPM).

[0028] Furthermore, the receiving device 12 includes a plurality of optical systems 181, 182. The number of optical systems in the plurality of optical systems is two or more, such as two, three, four, five, or more.

[0029] At least some of the different optical systems 181 and 182 have different aperture sizes, as represented, for example, by the different sizes of optical systems 181 and 182. In the illustration of Figure 1, for example, optical system 181 has a first aperture size that is larger than optical system 182, which has a second, smaller aperture size.

[0030] For further explanation, reference is made to, for example, a Cartesian coordinate system having axes a, b, and c, which are arranged orthogonal to one another in space, merely by way of example. Optical systems 181 and 182 are arranged side by side and have essentially identical or coincident preferred directions 221 and 222. They extend, for example, along the negative a direction; therefore, the side-by-side arrangement of optical systems 181 and 182 can be understood as an offset along the b direction and / or the c direction, which does not exclude an additional offset along the a direction. It should be noted that each of optical systems 181 and 182 may be configured as a single optical element, but may also be configured as a combination of optical elements, for example, as a single or multiple compound lens modules and / or as a combination of a lens and a reflector.

[0031] 1, optical systems 181 and 182 are offset from each other along the b direction and spaced apart from each other. However, even with an additional offset, for example along the c direction, there may be an overlap in the projection planes arranged parallel to the a and b directions between optical systems 181 and 182.

[0032] Each of the optical systems 181 and 182 is configured to direct light incident on the optical system to the photodetector 16, as indicated by arrows 241 and 242. This is done simultaneously, i.e., portions of the optical power incident on the photodetector are detected by the multiple optical systems simultaneously and superimposed at the photodetector. The superposition preferably results in very low interference, for example due to different optical wireless signal paths, so that correctable interference-free or error-free reception is possible.

[0033] This means that when optical systems 181 and 182 are simultaneously illuminated with optical wireless signal 14, both optical systems 181 and 182 can simultaneously direct corresponding portions onto photodetector 16. When only a subset, such as only one optical system 181 or 182, is illuminated, it is also possible that only the subset of optical systems 181 or 182 directs a portion onto photodetector 16, while a portion of another optical system is omitted or becomes negligible relative to the total optical power at photodetector 16, provided in the context of the embodiments described herein.

[0034] The photodetector 16 has an optical axis 26, which may extend, for example, along a primary preferred direction in space of the photodetector 16. For example, the optical axis 26 may also pass through a center point of a sensitivity curve, such as a geometric center point of the photodetector 16, and / or may be disposed perpendicular to the detector surface of the photodetector 16.

[0035] Optical system 181 has a distance 281 relative to optical axis 26, and optical system 182 has a greater distance 282 relative to optical axis 26. A coincident position or feature of optical systems 181 and 182 can be considered as a reference point or reference range for determining distances 281 and 282, for example the position of the optical center point or preferred direction 221 or 222. Alternatively, an outer edge or lateral boundary facing optical axis 26 or another feature may be considered as a reference.

[0036] Such an arrangement of optics 181 and 182 relative to each other and / or relative to photodetector 16 allows different situations to be assumed at different distances between device 10, particularly receiving device 12, and the transmitter of optical wireless signal 14, with respect to emission angle 32 of optical wireless signal 14; for example, multiple or all of optics 181 and 182 of the multiple optics are illuminated or receive optical wireless signal 14 at a relatively large distance. If the distance is reduced, this may result in at least one of optics, such as 181, being illuminated less or not illuminated any more by optical wireless signal 14, and correspondingly, less power reaching photodetector 16 through this optic, while possibly, but not necessarily, optical power may be increased through the other optic that continues to be illuminated, i.e., optic 182. These two opposing effects may result in photodetector 16 not being saturated, even if the distance to the transmitter is significantly reduced.

[0037] In a preferred embodiment, the optical wireless device 10 may be positioned or arranged relative to a transmitter in an optical wireless communications network or system such that the transmitter of the optical wireless signal 14 is positioned opposite the optics 182, also referred to as the secondary optics, having a smaller aperture, such that the optics 181, which is the optics with a larger aperture, referred to as the primary optics, is positioned outside the illumination cone of the optical wireless signal 14 as the distance to the transmitter decreases.

[0038] Distance 281 is smaller than distance 282, and preferably, distance 281 is at least within zero or essentially zero manufacturing tolerances, which means that optical system 181 can be centered above photodetector 16. Placement above photodetector 16 should not be understood as meaning that the height direction must necessarily be considered for this purpose; such designations refer to directions along optical axis 26. In general, designations such as left, right, top, bottom, front, or back related to the embodiments described herein are used only for better illustration and have no limiting effect unless explicitly stated. It is understood that such relative designations can be freely changed by shifting and / or rotating in space.

[0039] Placing the optical system 181 above, in the middle, or centered above the photodetector 16 simultaneously means that the optical system 182 is positioned at a distance from the optical axis 26 of the photodetector 16 .

[0040] While optical system 181 may be configured to direct incident light to photodetector 16 along preferred direction 221 of optical system 181, optical system 182 may be configured differently to direct incident light to photodetector 16 along a direction different from preferred direction 222. This may be obtained by different optical effects, such as refraction and / or reflection; i.e., optical system 182 may change the direction of light traveling through optical system 182. The orientation of preferred directions 221 and 222 may be along any positive or negative a-direction in space. Optical system 182 may be configured for refraction and at least first total internal reflection, but possibly second or further total internal reflection, to direct incident light to photodetector 16 along a direction different from preferred direction 222, for example.

[0041] 2 shows a schematic diagram of an optical wireless communication system 200 according to one embodiment, including an optical wireless device 20 according to one embodiment and a further optical wireless device 25 that may be configured to transmit an optical wireless signal 14. The optical wireless device 25 may include, for example, a transmitting device 34 capable of receiving an optical emitter 36 and downstream transmission optics 38. The transmitting device 34 may be configured to transmit the optical wireless signal 14 along a primary transmission axis 42, which is positioned in space parallel to a preferred direction 41, but need not be parallel to the a direction, for example, and may be positioned in a region of maximum optical power for the optical wireless signal 14.

[0042] The emission profile of the optical wireless signal 14 may be composed of any number of sub-profiles, such as one, two, three, four, or more. For example, the transmitting device 25 may comprise an emitter array, a device for amplifying an apparent source at the transmitter side, or a device for generating multiple apparent sources from the optical emitter 36. According to a preferred embodiment of the optical wireless communication system, the transmitting device 34 is configured as a device for amplifying an apparent source or for generating multiple apparent sources originating from the optical emitter 36. It comprises the optical emitter 36 for generating an optical signal and a separation optical system configured to spatially split the optical signal into multiple optical partial signals, thereby splitting the optical power of the optical signal into multiple optical partial signals having related spectral ranges, the multiple spectral ranges at least partially coinciding. Such a separation optical system is described, for example, in [7]. In such a case, the partial signals 441-444 can be obtained in a corresponding number by the separation optical system. The emission angles 461-464 of the partial signals 441-444 may be the same or different. Despite this, and despite the implementation with several partial signals altogether, the optical wireless signal 14 may have an emission angle that may result in an increase in the area illuminated by the optical wireless signal as the distance from the transmitting device 34 increases.

[0043] The optical wireless device 20 may be configured according to the description of the optical wireless device 10 and includes a receiver optics 48 having at least two optics, such as optics 181 and 182. The receiver optics 48 may have an acceptance angle 52, such that, for example, a receive field of view 54 may have a planar extent, e.g., in the b / c plane, that increases as the distance 561, 562 from the receiver optics 48 increases. According to one embodiment, the optics 181 and 182 of the optical wireless device 10 differ in terms of the size of the receive field of view associated with each optic. The primary optics 181 may be the optic with the largest receive field of view among the multiple optics. Here, the receive field of view 54 should be understood such that each optics 181, 182 has an associated receive field of view, and the receive fields of view overlap among the multiple optics.

[0044] Alternatively or additionally, referring to FIG. 1 , optical system 181 may have the smallest angle of incidence on photodetector 16 among the multiple optical systems. According to one embodiment therefor, the optical axes between the receive fields of view of each optical system 181, 182 may be parallel to each other in the region between the receive fields and the optical system, such that each optical system may have an individual optical axis 58 that may result in an overall optical axis 58 of receiver optical system 48. Optical axis 581 of optical system 181 is shown as an example. Referring to FIG. 1 , the respective optical axes between the optical systems and photodetector 16 may be tilted with respect to the optical axis of the primary optical system, for example, because the received light is deflected more by the secondary optical system than by the primary optical system, which may result in little or no change in direction.

[0045] According to one embodiment, in an optical wireless communication system, the optical axis 581 of the primary optics 181 is offset from the primary transmission axis 42 by a distance or offset 62. This can allow the primary optics 181 to be less illuminated by the optical wireless signal 14 when the distance 64 between the transmitter and receiver is sufficiently reduced, avoiding saturation of the photodetector 16 by directing no or only low optical power through the primary optics 181 to the photodetector 16, particularly with respect to the possibly largest aperture in the plurality of optics. According to one embodiment, the primary transmission axis 42 may substantially coincide with the optical axis of a secondary optic of the plurality of optics, e.g., the optic having the smallest aperture.

[0046] In this way, it can be achieved in an optical wireless communication system that at different distances between optical wireless devices 20 and 25, different numbers of optical systems in receiving device 12 contribute to the total optical power illuminated by transmitted optical wireless signal 14 and directed to detector 16.

[0047] According to one embodiment, optical system 181 as a primary optical system among multiple optical systems in the geometrical far field of optical transmitter device 34 can provide a dominant portion of the total optical power at photodetector 16, and a secondary optical system such as optical system 182 of FIG. 1 in the geometrical near field of transmitter device 34 can provide a dominant portion of the total optical power at photodetector 16.

[0048] With respect to the primary transmission axis 42 , the secondary optics, or all of the secondary optics, may be positioned at a shorter distance from the primary transmission axis 42 than the primary optics 181 .

[0049] The acceptance angle 52 of the optical systems, ie, the receiving device 12, is preferably less than the resulting total emission angle of the transmitting device 12.

[0050] 2 initially considers a possible unidirectional link from optical wireless device 25 to optical wireless device 20. By placing a corresponding transmitting device on or in device 20 and a suitable receiving device on or in device 25, a bidirectional link can be made possible. In other words, some of the previous discussion is initially limited to a unidirectional link, i.e., a data link consisting of transmitter 25 and receiver 20. All concepts considered here can be extended to bidirectional communication as well. An example design for a bidirectional transceiver is described below.

[0051] Although this description is directed to optical wireless / optical cordless communications, the present invention can be extended to other applications where an optical emitter and optical receiver are used and a large dynamic range is maintained between the two. This is true, for example, for optical range finders. This means that the optical wireless devices 10 and / or 20 can be used for communications, but the optical wireless signal 14 may carry a different type of information, for example, for distance measurement.

[0052] In other words, FIG. 2 shows a schematic diagram of an optical wireless transmitter / receiver system consisting of, or at least including, a transmitter 25, an optical free-space channel, and a receiver 20. The transmitter 25 comprises at least one optical emitter 36, such as a laser diode (LD) or a light-emitting diode (LED). In most cases, additional transmit optics 38, such as a refractive or total internal reflection lens, can be used. This transmit optics 38 can shape the emission profile. An emission angle 46 can characterize the angle at which the beam of the optical wireless signal 14 is emitted at its maximum. The beam can be emitted along a preferred direction 41. The preferred direction 41 can correspond to the a-axis, but this is not essential. By way of example, reference numeral 42 denotes the optical axis of the transmitter 34, and reference numeral 581 denotes the optical axis of the primary receiving lens 181 of the optical wireless device 20. The receiver 12 comprises a photodetector 16 and receive optics 48. The receive optics 48 has an acceptance angle 52.

[0053] The embodiments enable the discussed high dynamic range by specifically increasing the channel loss at short communication distances 64, for example by moving at least one, particularly the primary optics, outside the light cone of the optical wireless signal 14, while at long distances 64 no additional channel loss is introduced. The embodiments are based on the knowledge that one or more of the following effects may be specifically used to appropriately control the channel loss:

[0054] the offset 62 between the optical axis 42 of the transmitter 25 and the optical axis 581 of the primary receiving lens 181, and / or · Selection of a smaller acceptance angle 52 compared to a larger emission angle 46.

[0055] To further enhance the utility of the embodiments described herein, it is advantageous to provide that alignment tolerances perpendicular to optical axis 42 and / or 581 are acceptable and the communication system still functions. This can be achieved by:

[0056] · Transmit optics 38 with a parallel output beam or low divergence output beam and / or an expanded source or multiple apparent sources.

[0057] This is illustrated in Figure 2 by a larger apparent source that may consist of multiple beams 441-444. This can be achieved, among other things, as follows.

[0058] a single optical emitter 36 in combination with a multi-pass lens or separation optics, which is preferred in the context of this embodiment; and / or A plurality of optical emitters, for example as LED arrays and / or laser arrays, optionally in combination with a lens array, and / or One or more optical emitters and a diffuser such as a scattering diffuser, optical diffuser, or color converter.

[0059] From the model's perspective, the output profile of the optical wireless transmitter can then be viewed as multiple counted or uncounted sources that may initially have the same or at least similar emission profiles.

[0060] 1, the receive optics 48 includes a primary receive lens 181 and at least one secondary lens 182. The secondary lens 182 may be positioned in the geometric near field within the field of view of the transmitter 25, as shown in FIG. 3a. The secondary lens 182 may also focus incident light onto the photodetector 16. By determining the area of ​​the secondary lens 182 and the dimensions of its offset 622 relative to the optical axis 42 of the transmitter 25, the received power in the geometric near range may be defined, and the received power in the geometric far range may be defined via the primary receive lens 181.

[0061] FIG. 3a shows a schematic cross-sectional side view of an arrangement of a transmitting device 34 and a receiving device 12′ according to an embodiment described herein. The receiving device 12′ can essentially correspond to the embodiment of the receiving device 12, with an advantageous optional additional feature that at least one optical system from the plurality of optical systems, here, for example, optical systems 181 and 182, is fixed relative to one another via a connecting structure 66. The connecting structure 66 may have optical properties, but this is not required. One task of the connecting structure 66 is the relative positioning and / or fixation of the optical systems 181 and 182 connected thereto. For example, the connecting structure 66 can be obtained and used during an injection molding or another molding process, for example, to introduce material into a mold, identify any artifacts that may occur in optically irrelevant areas, and simultaneously simplify manufacturing, since at least some of the plurality of optical systems can be manufactured in a single process step. It is conceivable that the connecting structure and one or more optical systems connected thereto or fixed relative to one another form a common monolithic body.

[0062] In Figure 3a, the receiver 12' is located in the geometric near field of the transmitter 34, i.e., the distance 64a between the transmitter 34 and the receiver 12' is small. Figure 3b shows a schematic side cross-sectional view of the same components, but in the geometric far field, i.e., the distance 64b between the transmitter 34 and the receiver 12' is large.

[0063] One possible operation of an optical wireless communication system may be such that the transmitter 34 emits optical radiation 14 with a well-defined emission range / emission profile 44, which may, for example, but not necessarily, have multiple virtual sources. The radiation is emitted along a preferred direction parallel to the direction along the optical axis 42. On the other hand, there exists a receiver 12' in which the optical axis 581 of the primary receiving lens 181 may have an offset 621 relative to the axis 42. The offset 621 may be measured perpendicular to the optical axis 42 and, in the described embodiment, may lie in a plane parallel to the b and c directions. The optical axes 581 and 582 may be positioned at a distance 74 from each other.

[0064] The receiving optics 48 can direct the incident radiation onto the detector 16. Here, the receiving optics 48 comprises at least two optically active parts: a primary receiving lens 181, which provides a large concentration factor and is not illuminated in the geometric near field than in the geometric far field, or is illuminated only to a lesser extent, such as at most 20%, at most 10%, or at most 5%, in order to transfer power to the photodetector 16. For example, with the transmitting optics and the primary optics 181 aligned parallel but opposite each other, the emission angle of the transmitting device 34 may be larger than the acceptance angle of the primary optics 181, which may result in the primary optics 181 still being illuminated by the optical wireless signal 14 at a certain distance due to the difference in angle, but this signal is not transferred to the photodetector. On the other hand, the secondary optics 182 is illuminated to a similar extent in both the geometric near field and the geometric far field, and thus can act in both the geometric near field and the geometric far field, although in some embodiments, its effect in the far field is fairly negligible.

[0065] The primary optic or primary receiving lens 181 may be any imaging or non-imaging optical system for light collection, such as a spherical lens, an aspherical lens, a freeform lens, a total internal reflection lens, a reflector, or a so-called compound parabolic concentrator (a concentrator composed of at least two corrugations, CPC). The primary receiving lens or primary optic 181 is, for example, centrally positioned above the photodetector 16 to enable a high concentration factor. The primary receiving lens 181 may simultaneously have the smallest angle of incidence 68 from the group of angles of incidence 681, 682 of the multiple optics 181, 182 on the photodetector 16. Thus, the secondary lens 182 is offset with respect to the photodetector 16 and can direct the incident radiation onto the detector 16 at an angle 682, as shown by the beam 721 of the optic 181 and the beam 722 of the optic 182. According to an embodiment, 681≦682 may apply.

[0066] Beams 721 and 722 show diagrammatically how the ray paths can be realized in a design example. This progression may deviate from this, for example, by using additional optical components or optical fibers for beam steering. The optical axis 582 of the secondary optics 182 may not be equal to the optical axis 581 of the primary receiving optics 181. According to an embodiment, the optical axis 182 may be positioned at least substantially or completely identical or coincident with the optical axis 42 of the transmitter 34, or may have an intentional or tolerance-related offset 622. This means that the offset 622 may also essentially correspond to a value of zero.

[0067] Offset 622 is typically smaller than offset 621. Secondary lens 182 may be a lens or a reflector or a combination of both. In the case of a lens, it is conceivable that the lens uses refraction and / or total internal reflection to deflect the radiation.

[0068] 4a shows a schematic top view of an optical wireless device 40 according to one embodiment. For clarity, the photodetector 16 is not shown. However, the optical wireless device 40 may include a transmitting device 76, which may be formed according to the transmitting device 34 and may enable bidirectional exchange of optical wireless signals. By way of example, axes 781 and 782 are depicted to divide the side of the illustrated housing 82 into quadrants 841-844.

[0069] According to a preferred embodiment, the optical wireless device 40 is configured to accurately configure a structurally similar or identical further device 40 for bidirectional exchange to utilize the advantages of the present invention on both sides of the communication link. In the case of juxtaposition, i.e., when the device 40 and its copy are positioned opposite each other, as shown in FIGS. 3a and 3b, for example, the arrangement of the transmitting device 76 and at least the primary optical system 181 and the secondary optical system 182, which may optionally be connected by a connecting structure 66, may be such that the secondary optical system 182 is closer to the transmission power center 86, such as the origin of the primary transmission axis 42, than the primary optical system of the copy. If the exemplary copy is rotated 180° about the axis 782 and shifted in space along the negative a direction, the copied transmitting device 76 will overlap the optical system 182 when projected onto the c / b plane, and in some cases the secondary optical system 182 will also overlap the copied power center. On the other hand, the primary optical system 181 is at a distance from the copied transmitting device and may be illuminated only by optical wireless signals if the distance between the device 40 and its copy is large enough.

[0070] Although the primary optical system 181 is shown as circular, it may have a different shape, for example an at least substantially rectangular cross section, and may additionally have rounded edges, for example as shown by way of example in Figure 4d.

[0071] In an embodiment, the receiving device of the optical wireless device is configured to receive the received optical wireless signal of the emitting optical wireless transmitter in both the geometric near field and the geometric far field and detect it with photodetector 16 without saturating it. This aspect can also be implemented independently of the particular geometry of the optical system described in connection with FIG.

[0072] Each of the optical systems 181 and 182 may have a respective receive field of view, which may be associated with the optical system. The receive fields of the optical systems may have different sizes, which may be represented, for example, by different angles of incidence and / or aperture sizes. The receive fields of the optical systems may at best only partially overlap, resulting in the location of an optical transmitter at various distances between the transmitter and receiver resulting in the transmitter not being seen by at least one receive optical system at some distances and therefore not transmitting light to the optical detector 16. At different distances, the same receive optical system may be able to see the transmitter, i.e., be illuminated by the transmitter, and therefore transmit a signal to the detector 16.

[0073] 4b shows a representation of device 40 extended by a copy of device 40, transmitting device 34. By rotation about axis 782, transmitting device 34, which is structurally identical to transmitting device 76, is positioned opposite secondary optics 182, with offset 62 clearly visible.

[0074] In other words, FIG. 4a shows a front view of one embodiment of a bidirectional communication link. It is advantageous for a product if all devices are identical and peripherals such as cable connections are located on the same side. The advantageous arrangement discussed in the embodiment shown in FIG. 4a allows the transmitter 76 and receiver, represented by optical systems 181 and 182, to be located on one side of the housing 82, so that the optical arrangement described above is achieved. The transmitting device 76 can be used by the device 40 to implement a return channel. When the device 40 is rotated 180° about the b-axis or 782, the transmitter and receiver are positioned opposite each other so that the optical axis of the secondary lens is approximately or exactly on the optical axis of the transmitter, or has a predetermined offset. Therefore, the secondary lens 182 can cover the geometric near field. Meanwhile, the primary receiving lens 181 is positioned on the optical axis of the photodetector 16.

[0075] In other words, for better illustration, the illustration in Fig. 4b shows the same system with the transmitter 34 of the opposite device drawn to clarify the relative positions of the transmitter 34 / 76 and the receivers 181, 182. Alternatively or additionally, it is conceivable to design both receiver lenses as a single compound lens module, thereby reducing the number of components to be manufactured and assembled. In this case, for example, the components, parts or lenses 181 and 182 can be connected via a connecting structure 66, possibly formed as a web. The connecting structure 66 does not have to perform any optical function.

[0076] Figure 4c shows a schematic perspective view of two devices 40a and 40b, which are mutual copies of each other and are used for the discussion of the description of Figures 4a and 4b. 2a and 18 2b4c, the primary optics 18 can be positioned opposite the respective transmitting device 76b or 76a of the other device, for example along direction a. The illumination area 88a or 88b of each transmitting device 76a or 76b varies by distance 64 due to the emission angle described above, and increases as the distance 64 to the transmitter increases. As can be seen in FIG. 4c, the decrease in distance 64 reduces the primary optics 18 1a and 18 1b may be illuminated in decreasing order, resulting in no illumination or at least only partial illumination as the distance decreases further.

[0077] Deviating from the illustrations of FIGS. 4a and 4b, it is conceivable that the primary receiving lens 181 could be configured differently, for example, covering most of the housing area or the entire lower area of ​​the housing. For example, most or even all of quadrants 843 and 844 could be covered by the lens, or even just parts of quadrants 841 and 842. For example, it could be a lens with a rectangular cross-section for optimal space utilization, as shown in FIG. 4d. The shape of the optical system 181 shown therein is understood to be rectangular, despite the rounded corners, because at least 80%, 90%, or 95% of the outer edge, if shown as straight lines and expanded accordingly, forms a square. Generally, the cross-section of the primary receiving lens 181 may be arbitrary. Advantageously, the secondary lens 182 is at least approximately the same height as the transmitter 76 along direction b when the system is rotated about axis 782.

[0078] In other words, the system can function well if it rotates around axis 782, with the transmitter covering part of the upper left half and the secondary lens covering part of the right half. The expansion of the components along the b-axis may play a lesser role in basic functionality. However, the objective may be to design the distance along the b-axis between each transmitting device 76 and the primary optics 181 as large as possible, so that the maximum power 99 shown in FIG. 5 occurs only at the maximum possible distance x and is therefore correspondingly small.

[0079] In principle, it is conceivable to rotate the system about different axes and position the transmitters and receivers accordingly to achieve equally effective placement in the geometric near field and the geometric far field. Rotating the device about axis 782 is particularly advantageous, as it allows possible cables and connectors to be routed downwards or upwards, e.g., in the positive b or negative b direction, on both devices.

[0080] In a configuration that is particularly robust with respect to transmitter and receiver placement tolerances, the transmit lens of the transmitting device 76 can cover at least one quadrant of the housing 82, such as quadrant 841. The secondary lens 182 may, for example, be located approximately in the center of the adjacent quadrant 842, such that the secondary lens 182 is positioned exactly or at least approximately on the optical axis of the transmitter for the opposite device. In this case, both devices can be shifted relative to each other as far as possible before the secondary optics 182 of the opposite device is no longer directly in front of the transmitter 76.

[0081] 5 shows a schematic characteristic curve for illustrating the embodiments described herein. The graph shows the optical radiant power or radiant flux Φ on the vertical axis, and the value Φ min may denote the lower detection threshold of an exemplary optical receiver or receiving device, and Φ max can indicate the upper threshold above which the receiver will perform poorly, e.g., saturate. On the horizontal axis, the distance x is plotted, which is approximately equal to the distance 64 between the transmitter and receiver. The maximum distance x max , the optical power received by the transmitter using the optical wireless signal 14 is the minimum power Φ min Starting at greater distances, the threshold Φ is increased until it reaches a value where the photodetector 16 can process the signal according to specifications. Signals may also be physically receivable and possibly analyzable below this threshold, but may be decoded with an unacceptable error rate, which is why the threshold Φ min Because this may be system dependent, in this document specification is understood as intended behavior.

[0082] Characteristic curve 921 shows an exemplary profile of optical power directed by primary optics 181 to photodetector 16. Characteristic curve 922 shows an exemplary schematic profile of optical power that can be directed by secondary lens 182 to photodetector 16. Due to its smaller aperture, secondary optics 182 only provides sufficient optical power to photodetector 16 at a much smaller distance. It can be seen that the secondary optics provides a negligible portion in the geometrical far field, while the primary optics provides a dominant portion of the total optical power at photodetector 16 in the geometrical far field. In combined characteristic curve 94, which shows the sum of characteristic curves 921 and 922, it can be seen that at distance x1, the power provided by primary optics 181 decreases and deviates from expected profile 96. The reason for this is that primary optics 181 is less illuminated, and in some cases no longer illuminated, by the optical wireless transmitter as distance x decreases further.

[0083] In the geometrical near field, the optical power of the secondary optical system 182 becomes the dominant part, since the primary optical system 181 is no longer illuminated when the distance x2 is not reached. Here, the optical power can be increased until the minimum distance x3 is reached. By configuring the individual components accordingly, this means that the total power represented by the characteristic curve 94 is always less than the power Φ max The maximum value 99 may be configured by configuring the corresponding components, as indicated by arrow 101.

[0084] In other words, Figure 5 shows the received power Φ plotted on the vertical axis over the distance between the transmitter and receiver along the x-axis. max indicates the maximum power at which the receiver still operates within specifications. min indicates the minimum power at which the receiver will still operate within specifications. Functionality according to this example is provided only if the received power 94 is between the two values.

[0085] In other words, characteristic curve 921 can exemplarily illustrate the received power that primary receiver lens 181 directs to photodetector 16 of FIG. 1 , and the implementation is readily applicable to other embodiments described herein. Coming from a long distance, the received power can increase as the communication distance decreases, i.e., as the x value decreases. If the transmitter and primary receiver lens 181 do not have offset 621, i.e., their optical axes 42 and 581 are identical, the received power continues to increase, as shown by line 96. Due to offset 621, the transmitter gradually moves out of the field of view of primary receiver lens 181 at short distances, and as a result, the received power may eventually reach a maximum value and eventually rapidly decrease at even shorter distances, rather than continuing to increase. The received power that secondary lens 182 directs to detector 16 is shown as characteristic curve 922. The total power incident on detector 16 can correspond to the sum of the primary optics 181 and at least one secondary optics 182, and is shown as characteristic curve 94 for the configurations of devices 10 and 40. A system using only the offset primary lens 182 moves from distance x2 to distance x max By using and combining the secondary optics 182, the minimum distance is improved to a significantly smaller value x3, but the maximum range x max is not adversely affected. The secondary lens 182 can also direct power to the detector 16 at a greater distance due to the smaller version of the aperture, but this portion of the power may be significantly lower than the portion received by the primary optics 181.

[0086] The embodiment is configured to operate at a maximum power Φ max or the minimum power Φ min One or more of the following design parameters are particularly suitable for influencing the characteristic curves 921, 922, and / or 94: The characteristic curve 922 is particularly suited to influencing the lower and upper power limits Φ min or Φ maxIf the primary receiving optics 181 have the maximum distance to the center of the primary receiving optics 181, i.e., are located approximately in the center of the primary receiving optics 181, a complete system is obtained that is particularly robust not only in terms of system tolerances but also in terms of alignment tolerances. The parameters of the primary receiving optics 181 that can modify the characteristic curve 921 in order to adjust the maximum power level, especially along the arrow 101, can be:

[0087] The offset of the optical axes 42 and 581, see for example FIG. 2, i.e. the offset 62 between the transmitter and the primary receiving lens 181.

[0088] The larger the offset 62, the greater the distance at which the maximum detected power occurs, i.e., the maximum may be shifted along arrow 101. The direction of arrow 101 roughly corresponds to the progression of curve 96, with the actual maximum being below curve 96. Because primary receiving lens 181 can only detect radiation from the transmitter at greater distances, the maximum value, i.e., maximum power, may decrease as the offset increases. The greater the distance, the lower the power density.

[0089] ·Adjustment of the concentration factor according to the acceptance angle 52 of the primary receiving lens or the angle of incidence of the radiation. · Dimensions of the primary receiving lens 181 and coupling angles 681, 682 to the detector element 16.

[0090] Alternatively or additionally, parameters for adjusting the secondary receiving optics 182, in particular for adjusting the power level 98, that can change the characteristic curve 922 are: the position of the secondary optics 182 relative to the opposite transmitter, i.e., the offset 622 in FIG. 3a; the position of the secondary receiving lens 182 relative to the detector 16, i.e., the coupling angle 682 to the detector; the aperture size of the secondary optics 182; The acceptance angle of the secondary receiving optics 182 and its incidence angle dependent efficiency of radiation deflection onto the detector 16 may include:

[0091] Alternatively or additionally, parameters of the transmitter emission profile may be changed, for example to change the characteristic curve 921 or 94 .

[0092] The transmitter can distribute the optical power so that it is uniformly distributed across the output aperture, or so that each virtual source has similar power. The opposite is also possible: for example, a greater power density can occur in the center of the transmitter's output aperture than at the edges. The power signal of the secondary optics 182 can be influenced by changing the local power density. Such a distribution can also affect the power directed by the primary receiving lens 181 to the detector 16. This occurs precisely when the transmitter is at the edge of the primary receiving lens's field of view, which sees only a portion of the transmitter aperture.

[0093] The channel loss, and therefore the received level of the characteristic curves 922, 94, may depend on the emission and reception angles of the primary receiving optics 181 and the secondary optics 182. Therefore, both characteristic curves can be influenced by changing the emission angle above the transmitter's output aperture. For example, each virtual source located directly opposite the secondary optics 182 can have a smaller emission angle than the remaining virtual sources, so that the secondary optics 182 can direct as much power as possible from the transmitter to the detector 16. The opposite is also possible, i.e., a larger emission angle to reduce the detected power.

[0094] Referring to FIG. 4d, an optical wireless communication system according to one embodiment may be configured for a minimum distance x3 between an optical wireless transmitter and an optical wireless receiver, or between two transceivers, that are movably positioned relative to each other. The minimum distance may result from, for example, a working area or be influenced by the area in which communication takes place. The minimum tolerance of the optical wireless communication system with respect to positioning inaccuracies related to the offset of components relative to each other along the c and / or a directions and / or the tilt of the primary optical axes relative to each other may be determined by the size or aperture of the transmit optics. This may be expressed such that, at the minimum distance, the secondary optics of the optical wireless receiver at least partially oppose the transmit optics of the optical wireless transmitter so that the emitted optical power is still sufficiently directed by the secondary optics to the photodetector.

[0095] FIG. 6 shows a schematic front view of an optical wireless device 60 according to one embodiment. It may be configured similarly to device 40, but in contrast, it may include multiple secondary optical systems 182, 183, and 184. The secondary optical systems 182-184 may be arranged in any number, for example, one, two, three, four, or more as shown in FIGS. 4a and 4b. Preferably, the multiple secondary optical systems 182-184 are arranged relative to the primary optical system 181 such that the secondary optical systems 182-184 have decreasing aperture sizes as the distance from the optical center 1021 of the primary optical system 181 increases. This is illustrated in FIG. 6 by the different sizes of the optical systems 182-184, particularly by decreasing the size along the offset 62; however, other means for decreasing aperture size may also be used, such as lens shapes other than circular lens shapes.

[0096] The multiple optical systems 181-184 can potentially be manufactured as a common body which may have different optically active areas within the area of ​​the optical systems 181-184. Alternatively or additionally, the optical systems can be spaced apart and connected to each other, for example via connecting structures 66, to achieve high positioning accuracy.

[0097] The secondary optical systems 182, 183, 184 may be arranged along a straight line, but may also be arranged along a line that is only partially straight relative to their optical centers 1022, 1023, and 1024, as shown in FIG. 6, or along a curve, etc.

[0098] In other words, generalizing for further embodiments, an implementation can be provided in which not only one secondary lens 182 but also N>2 secondary lenses 182, 183, 184, ... are arranged, and each of these secondary lenses or secondary optics can be optimized for a specific distance range. This embodiment offers the advantage of further reducing the maximum reception level, i.e., further improving the dynamic range, or further smoothing the received power over distance. Figure 6 is a front view showing how exemplary secondary lenses or secondary optics 182, 183, 184 can be arranged. There are different configurations in which each additional secondary lens can attempt to reduce the offset 621 or individual offset of the secondary optics relative to the optical axis of the transmitter 34. The secondary optics may be configured such that the following applies: the greater the offset 621-624 relative to the optical axis of the transmitter 34, the less power the lens will focus in the geometrical near field and the more power it will focus in the geometrical far field. The further discussion related to Figures 4a and 4b applies here as well. For better visualization, the transmitter 34 is shown only as an unshaded boundary, but may have the same functionality as that described in relation to FIG. 4b.

[0099] 7 shows a schematic diagram of an exemplary total intensity Φ, for example, as may be obtained with the optical arrangement of optical wireless device 60. In contrast to the representation of FIG. 5, a total characteristic curve 94′ may be formed from four characteristic curves 921, 922, 923, and 924, similar to the number of primary and secondary optical systems of device 60. By designing and aligning transmitter 34 accordingly, characteristic curve 94′ may be advantageously made more uniform compared to characteristic curve 94 of FIG. 5.

[0100] 7 shows an exemplary graph of received power for device 60 with transmitter 34 associated with FIG. 6, which together can form an exemplary system. Each of secondary receiving lenses 182, 183, 184, like primary optics 181, can generate received power for detector 16 of the receiving device. These are collectively represented by corresponding characteristic curves 921, 922, 923, and 924. The total power incident on detector 16 is shown by example characteristic curve 94'. It is clear that the use of multiple secondary lenses can significantly reduce fluctuations in received levels.

[0101] In the optical wireless communication system according to the present invention, the optical systems of the receiving device of the first optical wireless device on the one hand and the transmission power of the transmitting optical wireless device on the other hand may be matched. At any distance between the first optical wireless device and the second optical wireless device, the photodetector 16 may remain free of saturation, as shown in both Figures 5 and 7.

[0102] According to one embodiment, the multiple optical systems may include a first optical system as a primary optical system, such as optical system 181, and multiple secondary optical systems, as described in connection with FIG. 6. Each of the multiple secondary optical systems may be configured for a distance range to the second optical wireless device specific to that optical system that at most incompletely overlaps with the distance range of another secondary optical system. This may mean, for example, that the relevant regions or regions with maximum optical power are shifted relative to each other, as shown in FIG. 7. The adjustment may be performed by selecting an offset along the b and / or c directions in the coordinate system of FIG. 6 and may alternatively or additionally include the lens type and / or aperture size. For this purpose, the optical axis of the transmitter 34 may be considered, as well as the transmit power of the transmitter 34.

[0103] According to one embodiment, in an optical wireless communication system, the emission angle of a transmitting optical wireless device may be larger than the total field of view angle or total acceptance angle of multiple optical systems of a receiving optical wireless device, which can allow a certain tolerance for tilt when positioning the transmitter and receiver.

[0104] 8 shows a simplified flowchart of a method 800 according to one embodiment. Step 810 includes designing and positioning multiple optical systems relative to a transmitting device configured to provide an optical wireless signal. This may be done so that multiple optical systems simultaneously direct the received optical wireless signal toward the photodetector 16 of the receiving device, such that at different distances between the receiving device and the transmitting device, different numbers of multiple optical systems contribute to the total optical power directed toward the photodetector 16 of the receiving device.

[0105] Step 820 includes fabricating a plurality of optical systems in a design and alignment arrangement.

[0106] According to one embodiment, the design and positioning 810 includes considering at least one element from the group including the aperture angle of the transmitting device, the transmit power of the transmitting device, the power distribution across the output aperture of the transmitting device, the relative distances of the multiple optics to each other and to the optical axis of the transmitting device, the acceptance angle of the multiple optics of the aperture geometry of the multiple optics, and / or the saturation limit of the photodetector 16 of the receiving device.

[0107] It is particularly advantageous if the parameters of the transmitting and receiving devices are known and taken into account in step 810. However, an advantageous design of the receiving optics can also be made using only rough information about the transmitter or about estimated characteristics of the transmitter, for example by making assumptions about the average transmission power and / or the average or expected spread of the transmitter, etc. This may still allow relevant improvements compared to known concepts.

[0108] Embodiments can be used, for example, as a data light barrier. In this case, data can be transmitted along a linear axis, and both transceivers can be individually fixed or mobile. Such arrangements are found, for example, in hall cranes, bridge cranes, and port cranes, mobile trolleys for transporting containers, pallets, and grid boxes, or automated parking systems for horizontal or vertical parking. For example, port cranes can move within a few centimeters of the transmitter, but may be hundreds of meters away, requiring a high dynamic range.

[0109] Embodiments provide an optical wireless transmission and reception system or a component for such a system having one or more of the following features.

[0110] a transmitter for transmitting an optical wireless signal, a receiver for receiving optical wireless signals; a receiver comprising a detector; a receiver comprising a lens module or optical module including a primary receiving lens whose optical axis is offset from the optical axis of the transmitter; A receiver including at least one secondary receiving lens whose optical axis has a smaller offset relative to the optical axis of the transmitter compared to the primary receiving lens, or no offset at all relative to the optical axis of the transmitter.

[0111] A further aspect features relates to the fact that the field of view of the transmitter is larger than the field of view of the receiver, and the field of view of the primary receiving lens may be designed to be different from the field of view of the secondary receiving lens.

[0112] The embodiments described herein relate to optical concepts for transmitters and receivers based on defined geometric transmitter and receiver arrangements, which may not require additional components to achieve improved dynamic range compared to known concepts. In particular, if the primary and secondary optics are designed as an integrated or monolithic component, additional components can be avoided. Even if the optics are manufactured as separate components, these additional components can be easily and inexpensively used. To implement the present invention, it may be sufficient to implement a single receiver, so that the complexity of the electronic circuitry is not unnecessarily increased. This problem can already be solved by the design of the transmit and receiver optics that are required in the system anyway. In this respect, the secondary receiver optics can be considered as a design within the existing components. This concept also requires only minor changes to the design of the transmit and receive optics in terms of optical efficiency / performance in the optical channel compared to known solutions. Thus, in embodiments, radiation cannot be utilized, or only low radiation can be utilized, at relatively large angles that are no longer usable over large distances. The present invention allows for a relatively large tolerance regarding the lateral offset of the devices relative to each other perpendicular to the optical axis, which may occur in practice due to tolerances. Advantages of the embodiments described herein include, but are not limited to, the following:

[0113] High to very high efficiency, as there is no need to accept power losses to cover the geometric near field, Very high achievable dynamic range, Robustness against mechanical misalignment between transmitter and receiver, Low channel crosstalk, No active control loop required, no frequency dependency required, Only existing detectors are required; Only a transmit lens is required; A compound lens module on the receiver is sufficient, and the receiver lens is already present and in embodiments split into two or more lenses / optics; · Compatibility with other techniques that introduce additional controls such as adaptive transmitter power.

[0114] Although some aspects have been described in the context of devices, it will be understood that these aspects also constitute a description of a corresponding method, and thus a block or component of a device should also be understood as a corresponding method step or feature of a method step. Similarly, aspects described in the context of or as a method step also constitute a description of a corresponding block or detail or feature of a corresponding device.

[0115] The above-described embodiments are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended that the present invention be limited only by the scope of protection of the following claims, and not by the specific details presented in the description and explanation of the embodiments herein.

[0116] Literature: [1]ROJAS CALVENTE FRANCISCO; SUMASTA PAMUNGKAS:METHOD AND APPARATUS FOR AVOIDING SATURATION IN OPTICAL WIRELESS POINT-TO-POINT SYSTEMS, WO22200124 A1, SIGNIFY HOLDING BV. [2]S. Huang and M. Safari, "Reliable Optical Empfaenger for Highly Dynamic Wireless Channels:An Experimental Demonstration,"2021 IEEE Global Communications Conference (GLOBECOM),2021, pp.1-6, doi:10.1109 / GLOBECOM46510.2021.9685634. [3]Bassam Hanal, Thalwtl (CH). Hartmut Rudmann. Jona (CH), Mario Cessna, Au (CH); Nicole Ebentheuer, Zurich (CH):TRANSCEIVER MODULE INCLUDING OPTICAL SENSOR AT A ROTATIONALLY SYMMETRIC POSITION, US Patent, US10,547,385 B2, ams Sensors Singapore Pte. Ltd., Singapore (SCJ) [4]Fritz Gfeller, DRAHTLOSES OPTISCHES UEBERTRAGUNGSSYSTEM MIT ADAPTIVER DATENUEBERTRAGUNGSGESCHWINDIGKEIT, DE69411954.7, International Business Machines Corporation, Armonk, N.Y., US, int. Publication date:26.10.1995 [5]Yakov G. Soskind, Thirukumar Vethanayagam ,,Optical Empfaenger With High Dynamic Range“, US6,954,580B2, JDS Unipahse Corporation,11.10.2005. [6]Eken, Yalcin Alper, Oguz, Alp, ANALOG FRONT-END RECEIVER WITH WIDE DYNAMIC RANGE FOR LONG-RANGE LIDAR, DE102018106762 A1 Analog Devices Global Unlimited Company, publication:2018.09.27. [7] Kirrbach, Rene; Schneider, T., “Eye-safe optical-wireless communication”, WO2021 / 228697A1, Publication date: 18.11.2021

Claims

1. An optical wireless device having a receiving device (12) configured to receive an optical wireless signal (14), The receiving device (12) includes a photodetector (16) for detecting the optical wireless signal (14) and a first optical system (18) having at least a first aperture size. １ ) and a second optical system (18) having a second smaller aperture size. ２ ) have substantially the same preferred direction (22 １ , 22 ２ ) and a plurality of optical systems (18) arranged side by side. １ ~18 ４ ) and The plurality of optical systems (18 １ ~18 ４ ) are each configured to simultaneously direct light entering the optical system to the photodetector (16); The photodetector (16) has an optical axis (26), and the first optical system (18) １ ) is a first distance (28) from the optical axis (26). １ ), and the second optical system (18) ２ ) at a second greater distance (28) from the optical axis (26). ２ ) will be placed in Optical wireless devices.

2. The first optical system (18 １ ) is centrally located above the photodetector (16) and is connected to the second optical system (18) ２ 2. The optical wireless device of claim 1, wherein a first optical fiber (12) is disposed at a distance from the optical axis (26) of the photodetector (16).

3. The optical wireless device of claim 1 , wherein the first optical system is spaced apart from the second optical system.

4. The first optical system (18 １ ) directs the incident light to the first optical system (18) １ ) preferred direction (22 １ ) along the optical axis to the photodetector (16), The second optical system (18 ２ ) directs the incident light to the first optical system (18) １ ) preferred direction (22 １ 10. The optical wireless device of claim 1, configured to direct the optical detector (16) along a direction different from the direction of the optical fiber (14).

5. The first optical system (18 １ ) and the second optical system (18 ２ ) differ in terms of the size of the receiving field of view associated with each optical system, and １ ) is a plurality of optical systems (18 １ ~18 ４ 5. The optical wireless device of claim 4, wherein the optical system has a largest receiving field of view (54) among

6. The second optical system (18 ２ ) directs the incident light to the first optical system (18) １ ) the preferred direction (22 １ 6. The optical wireless device of claim 4, wherein the optical wireless device is configured for refraction and at least a first total internal reflection to direct the light toward the photodetector along the direction different from the direction of the first total internal reflection.

7. The first optical system (18 １ ) is a plurality of optical systems (18 １ ~18 ４ ) on the photodetector (16). １ ~18 ４ ) the smallest incident angle (68 １ ), and the second optical system (18) ２ ) is a plurality of optical systems (18 １ ~18 ４ 10. The optical wireless device of claim 1, wherein the optical wireless device is a secondary optical system of the optical fiber.

8. The plurality of optical systems (18 １ ~18 ４ and the optical axis (58) of the primary optical system in the region between the receiving field (54) associated with each optical system. １ ) is the optical axis (58) of the secondary optical system. ２ ) is substantially parallel to the plurality of optical systems (18) １ ~18 ４ 8. The optical wireless device of claim 7, wherein in a region between the optical axis of the secondary optical system and the optical detector, the optical axis of the secondary optical system is tilted with respect to the optical axis of the primary optical system.

9. the optical wireless signal (14) is a first optical wireless signal received from a receive direction, the optical wireless device comprising a transmit device (76) for transmitting a second optical wireless signal along a transmit direction parallel to and opposite the receive direction; the transmitting device is positioned relative to the receiving device (12) such that a comparison of the copy (40b) of the optical wireless device with the optical wireless device results in the secondary optics of the copy being at a smaller distance from the transmission power center (42, 86) of the transmitting device of the optical wireless device with respect to the orientation of the receiving device (12) and the transmitting device (76b) of the copy than the primary optics of the copy (40b).

8. The optical wireless device according to claim 6 or 7.

10. The optical wireless device of any one of claims 7 to 11, wherein the primary optic has a rectangular cross section.

11. 11. The optical wireless device of claim 7, comprising a plurality of secondary optical systems, the plurality of secondary optical systems being arranged relative to the primary optical system such that the secondary optical systems have aperture sizes that decrease with increasing distance from an optical center of the primary optical system.

12. 10. The optical wireless device of claim 1, further comprising a transmitting device (76) for transmitting an optical wireless signal, said transmitting device (76) comprising an emitter array, a device for magnifying the apparent source, or a device for generating one of a plurality of apparent sources of optical emitters.

13. the transmitting device (76) is configured as a device for amplifying the apparent source or for generating multiple apparent sources; an optical transmitter (36) for generating an optical signal (14); and separation optics configured to spatially split the optical signal (14) into a plurality of partial optical signals to split the optical power of the optical signal into the plurality of partial optical signals having associated spectral ranges, the plurality of spectral ranges at least partially coinciding. The optical wireless device of claim 12.

14. The plurality of optical systems (18 １ ~18 ４ Each optical system of the plurality of optical systems (18) is associated with a respective receiving field of view (54). １ ~18 ４ 10. The optical wireless device of claim 9, wherein the reception fields (54) of the first and second antennas (10) and (20) have different sizes.

15. The plurality of optical systems (18 １ ~18 ４ Each optical system of the plurality of optical systems (18) is associated with a respective receiving field of view (54). １ ~18 ４ 10. The optical wireless device of claim 1, wherein the reception fields (54) of the first and second antennas (10) and (20) are at most incompletely overlapping.

16. The plurality of optical systems (18 １ ~18 ４ 10. The optical wireless device according to claim 9, wherein the first and second electrodes (12) are monolithically fixed with respect to their relative positions with respect to each other via a connecting structure (66).

17. 10. The optical wireless device of claim 1, wherein the receiving device is configured to receive the optical wireless signal of an emitting optical wireless transmitter in both a geometrical near field and a geometrical far field and to detect it at the receiving device without saturation.

18. 1. An optical wireless device having a receiving device (12) including a photodetector (16) and configured to receive an optical wireless signal (14) from an optical wireless transmitter, the receiving device (12) being configured to receive the optical wireless signal (14) in both a geometric near field and a geometric far field of the optical wireless transmitter and to detect the optical wireless signal (14) at the receiving device (12) without saturating.

19. The receiving device (12) includes a plurality of optical systems (18 １ ~18 ４ ) the first optical system (18) １ ) and a second optical system (18) ２ ), and the plurality of optical systems are arranged side by side in substantially the same preferred direction (22 １ , 22 ２ ) and The plurality of optical systems (18 １ ~18 ４ ) are each configured to simultaneously direct light entering the optical system to the photodetector (16); The photodetector (16) has an optical axis (26), and the first optical system (18) １ ) is disposed at a first distance from the optical axis (26), and the second optical system (18 ２ ) is positioned at a second, greater distance from the optical axis (26); 20. The optical wireless device of claim 18.

20. 1. An optical wireless communication system, comprising: A first optical wireless device (20) according to any one of the preceding claims; a second optical wireless device (25) that transmits the optical wireless signal (14); At different distances (64) between the first optical wireless device (20) and the second optical wireless device (25), different numbers of optical systems of the receiving device (12) of the first optical wireless device (25) contribute to the total optical power illuminated with the transmitted optical wireless signal (14) and directed to the detector (16). Optical wireless communication system.

21. The plurality of optical systems (18) in the geometrical far field of an optical transmitting device (34) of the second optical wireless device (25). １ ~18 ４ The first optical system (18) as the primary optical system of １ ) provides a major portion of the total optical power at the photodetector (16) of the first optical wireless device, and the plurality of optical systems (18) in the geometrical near field of the transmitting device (34) of the second optical wireless device (25) １ ~18 ４ the second optical system (18) as a secondary optical system of the ２ 21. The optical wireless communication system of claim 20, wherein a .lambda. 16 provides a major portion of the total optical power at the photodetector.

22. The second optical wireless device (25) is configured to transmit the optical wireless signal (14) along a primary transmission axis (42), and the plurality of optical systems (18) １ ~18 ４ The secondary optical system among the plurality of optical systems (18) １ ~18 ４ 22. The optical wireless communication system of claim 20, wherein the optical fiber is positioned at a shorter distance from the primary transmission axis (42) than a primary optical system of the optical fiber.

23. The plurality of optical systems (18) of the first optical wireless device １ ~18 ４ 23. The optical wireless communication system of claim 20, wherein an acceptance angle (52) of a first optical wireless device (25) is smaller than an emission angle (46) of a transmitting device (34) of the second optical wireless device (25) configured to transmit the optical wireless signal (14).

24. The plurality of optical systems (18) of the receiving device (12) of one of the first optical wireless devices (20) １ ~18 ４ 24. The optical wireless communication system according to claim 20, wherein the transmit power of the first optical wireless device and the transmit power of the second optical wireless device are aligned with each other, and the receive device is maintained without saturating at any distance between the first optical wireless device and the second optical wireless device.

25. 25. The optical wireless communication system of claim 20, configured for a minimum distance between the first optical wireless device and the second optical wireless device, wherein a minimum tolerance of the optical wireless communication system for positioning inaccuracies is determined by an aperture size of the transmitting optics such that at the minimum distance, the secondary optics of the first optical wireless device is positioned opposite the transmitter.

26. The plurality of optical systems (18 １ ~18 ４ ) is the first optical system (18) as a primary optical system １ 26. The optical wireless communication system of claim 20, further comprising: a plurality of secondary optical systems, each configured for a unique range of distance to the second optical wireless device that at most incompletely overlaps with a range of distance of another secondary optical system.

27. The emission angle (46) of the transmitting device (34) of the second optical wireless device (25) is greater than the emission angle (46) of the plurality of optical systems (18) of the first optical wireless device. １ ~18 ４ 27. The optical wireless communication system of claim 20, wherein the total acceptance angle is greater than the total acceptance angle of the first and second optical fibers.

28. A method (800) for designing an optical arrangement for a receiving device of an optical wireless device, comprising: designing and positioning (810) a plurality of optical systems relative to a transmitting device configured to provide an optical wireless signal, whereby the plurality of optical systems simultaneously direct received optical wireless signals to a photodetector of the receiving device, whereby at different distances between the receiving device and the transmitting device, different numbers of the plurality of optical systems contribute to a total optical power directed to the photodetector of the receiving device; fabricating (820) the plurality of optical systems in the designed and positioned arrangement; A method comprising:

29. Designing and positioning the opening angle of the transmitting device; the transmission power of the transmitting device; a power distribution across the output aperture of the transmitting device; the relative distances of the optical systems to each other and to the optical axis of the transmitting device; the acceptance angles of the optical systems; the geometric shapes of the apertures of the optical systems; and the saturation limit of a photodetector of said receiving device; 29. The method of claim 28, comprising considering at least one of:

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