Optical wireless devices and method for laying out an optical arrangement

Abstract

An optical wireless device with a receiving unit is configured to receive an optical wireless signal. The receiving unit comprises an optical detector for detecting the optical wireless signal and a plurality of optics with at least a first optic with a first aperture size and a second optic with a second, smaller aperture size. The optics are arranged next to each other and essentially with the same preferred direction. Each of the plurality of optics is designed to simultaneously direct a light incident on the optic to the optical detector. The optical detector has an optical axis, and the first optic is arranged at a first distance from the optical axis, while the second optic is arranged at a greater, second distance from the optical axis.

Description

[0001] Optical-wireless devices and methods for designing an optical assembly

[0002] Description

[0003] The present invention relates to optical wireless devices for receiving optical wireless signals, to a communication system comprising such optical wireless devices, and to a method for designing an optical arrangement for a receiving device of an optical wireless device. In particular, the present invention relates to a highly efficient complex lens setup for high dynamic ranges for optical wireless or optical wireless transmitter / receiver systems.

[0004] Receivers of optical wireless or optical-wireless transceivers can be exposed to widely varying reception levels. On the one hand, high optical transmission power is required for a long range. However, increasing the transmission power also increases the minimum separation distance between the transceivers or the minimum separation between the transmitter and receiver. Below the minimum separation distance, the channel loss is so low that the receiver saturates and transmission is no longer possible. The separation range between the transmitter and receiver within which operation within the specifications is possible is defined as the dynamic range of the transceiver. This separation range is limited by the minimum separation distance and the maximum separation distance. A transceiver is particularly versatile if it has a large dynamic range.

[0005] There are various approaches to increase the dynamic reach of a link:

[0006] • Transmission power regulation: At short distances, the transmission power is adaptively reduced [1, 4] to avoid receiver saturation. However, this approach requires a driver circuit with adaptive control. Furthermore, the system must know when to reduce or increase the transmission power. This information is obtained from a receiver of the communicating party. This approach is typically limited to a control range of 3 dB to 20 dB.

[0007] • Regulation of the electrical receiver: the electrical receiver can be regulated, for example, by adjusting the gain of the transimpedance amplifier or by using an additional control at the input of the transimpedance amplifier [1, 6]. This approach is not always suitable, for example, when the saturation effect already occurs at the photodetector. Such saturation effects are common in avalanche photodiodes (APDs), single-photon avalanche photodiodes (SPADs), and also in silicon photomultiplier tubes (SiPMs). Although the internal gain of these detectors can be controlled via the bias voltage, this is only possible over a certain range, until the internal gain reaches 1 (lowest value) or until the effective photodiode capacitance no longer meets the specification.

[0008] • Use of one or more additional elements to attenuate the optical signal, such as a mechanical shutter [2], a variable aperture [5], a variable lens (electro-wetted lens, polymer lens, etc.), or a polarization-based shutter (e.g., liquid crystal shutter / attenuator [2]). All these approaches involve the introduction of an additional element in the system to specifically influence the channel loss, usually by increasing the channel loss in the geometric near field. The additional component and the necessary additional control increase system complexity and cost.

[0009] • The optical system can provide for the transmitter and receiver to be off-axis. The field of view is selected so that the receiver can barely see the transmitter at close range, or not at all. This approach is very simple, but the dynamic range is usually limited to 3 dB to 10 dB. This is particularly significant for small fields of view. This approach is particularly susceptible to offsets perpendicular to the optical axis. For example, if the receiver is defined to receive a signal strength from the transmitter at close range that is just within the range for evaluation, but the receiver is offset by a further 10 mm, for example, due to tolerances, the receiver may no longer be able to detect anything.

[0010] • This concept can be extended so that the transmitter also radiates at larger angles, see [3], and the receiver is also able to detect signals that arrive at these larger angles. The disadvantage of this approach, however, is that power is not used optimally at the transmitter because a receiver at a greater distance cannot detect this laterally radiated power. In addition, the receiver lens cannot be optimally designed for the actual acceptance angle because it has to collect radiation in the geometric near field even at larger radiation angles. The field of view is therefore no longer well defined, so that channel crosstalk with neighboring channels can occur. The approach is also sensitive to positioning tolerances between transmitter and receiver.

[0011] • The optical concept can provide multiple receivers. These can have different saturation thresholds, for example, by using different detectors (see [2]). In this case, one detector is used in the near field and one in the far field. This approach requires more hardware, as it also requires a second detector and additional amplifier electronics. Furthermore, both receiver channels must be combined, or a decision must be made as to which data stream is to be evaluated.

[0012] There is therefore a need for solutions for the efficient operation of optical wireless devices and for the design of required components that enable a high dynamic range between the transmitter and receiver of an optical wireless communication link.

[0013] An object of the present invention is therefore to provide optical wireless devices, an optical wireless communication system and a method for designing an optical arrangement for a receiving device of an optical wireless device, which enable efficient operation of optical wireless devices while simultaneously providing a high dynamic range between transmitter and receiver.

[0014] This problem is solved by the subject matter of the independent patent claims.

[0015] A core idea of ​​the present invention is the recognition that a saturation effect on an optical detector of a receiver can be reduced or avoided by equipping the receiver with a plurality of optical units that direct the received light onto the optical detector. In a geometric near field of the transmitter, the optical detector receives the optical signal from the transmitter only from a subset of the plurality of optical units, whereas in the geometric far field other optical units or a larger number of the plurality of optical units receive the optical signal. This is achieved, for example, by different optical units of the plurality of optical units being at different distances from an optical axis of the detector and by the optical units being arranged with essentially the same preferred direction.Based on the side-by-side arrangement, it is possible that as the distance to the transmitter decreases, some optics may be partially unilluminated or less illuminated, thus reducing their contribution to the total power at the optical detector, thus avoiding a saturation effect. This allows a small minimum distance to be achieved or even eliminates the minimum distance altogether. At the same time, a high degree of the transmitter's transmit power can be utilized in the geometric far field, thus achieving a high dynamic range and simultaneously high efficiency.

[0016] In one embodiment, an optical wireless device is provided which has a receiving device for receiving an optical wireless signal. The receiving device comprises an optical detector for detecting or receiving the optical wireless signal and a plurality of optical units with at least a first optical unit with a first aperture size and a second optical unit with a second, smaller aperture size. The optical units are arranged next to one another and essentially with the same preferred direction. Each of the plurality of optical units is designed to simultaneously direct light incident on the optical unit onto the optical detector. The optical detector has an optical axis, and the first optical unit is arranged at a first distance from the optical axis, wherein the second optical unit is arranged at a larger second distance from the optical axis.

[0017] According to one embodiment, an optical wireless device is provided, which comprises a receiving device having an optical detector and is configured to receive an optical wireless signal from an optical wireless transmitter. The receiving device is configured to receive the optical wireless signal in both a geometric near field and a geometric far field of the optical wireless transmitter and to detect it without saturation using the optical detector.

[0018] Further embodiments relate to an optical wireless communication system having an optical wireless device described herein.

[0019] According to one embodiment, a method for designing an optical arrangement for a receiving device of an optical wireless device comprises designing and positioning a plurality of optics with respect to a transmitting device configured to provide an optical wireless signal, such that the plurality of optics simultaneously redirects a received optical wireless signal, such that, at different distances between the receiving device and the transmitting device, a different number of the plurality of optics contributes to a total optical power directed onto the optical detector of the receiving device. The method further comprises manufacturing the plurality of optics in an arrangement according to the design and positioning.

[0020] Further advantageous embodiments are the subject of dependent patent claims.

[0021] Particularly preferred embodiments of the present invention are explained below with reference to the accompanying drawings. They show:

[0022] Fig. 1 is a schematic side sectional view of an optical wireless device according to an embodiment;

[0023] Fig. 2 is a schematic diagram of an optical wireless communication system according to an embodiment;

[0024] Fig. 3a is a schematic side sectional view of an arrangement of a transmitting device and a receiving device in the geometric near field in accordance with embodiments described herein;

[0025] Fig. 3b is a schematic side sectional view of the same components as in Fig. 3a, but in the geometric far field;

[0026] Fig. 4a is a schematic plan view of an optical wireless device according to an embodiment;

[0027] Fig. 4b is an extended representation of the device from Fig. 4a with a transmitting device of an opposite device;

[0028] Fig. 4c is a schematic, only partially perspective view of two devices according to Fig. 4a and Fig. 4b, which are mutual copies of each other, according to an embodiment;

[0029] Fig. 4d is a schematic representation of an optical wireless device according to an embodiment with receiving optics with an approximately rectangular cross-section according to an embodiment; Fig. 5 is a schematic characteristic curve of a received power at an optical detector for discussing embodiments described herein;

[0030] Fig. 6 is a schematic front view of an optical wireless device according to an embodiment having a plurality of secondary optics;

[0031] Fig. 7 is a schematic diagram of an exemplary total intensity, such as can be obtained with an optical arrangement of the optical-wireless device of Fig. 6, according to an embodiment; and

[0032] Fig. 8 is a schematic flow diagram of a method according to an embodiment.

[0033] Before exemplary embodiments of the present invention are explained in more detail below with reference to the drawings, it is pointed out that identical, functionally equivalent or equivalent elements, objects and / or structures in the different figures are provided with the same reference numerals, so that the description of these elements shown in different exemplary embodiments is interchangeable or can be applied to one another.

[0034] The embodiments described below are described in conjunction with numerous details. However, embodiments may also be implemented without these detailed features. Furthermore, for clarity, embodiments are described using block diagrams instead of detailed illustrations. Furthermore, details and / or features of individual embodiments may be readily combined with one another, unless explicitly described otherwise.

[0035] The following embodiments relate to optical wireless signal transmission or data transmission. In the context of the embodiments described herein, this is also referred to as LiFi (Light Fidelity). The term "LiFi" refers to terms such as IrDA (Infrared Data Association) or OWC (Optical Wireless Communication). This means that the terms "optical wireless data transmission," "optical wireless data transmission," and "LiFi" are used synonymously. Optical wireless data transmission is understood to mean the transmission of an electromagnetic signal through a free transmission medium, for example, air or another gas or fluid.For this purpose, wavelengths in the ultraviolet (UV) range of at least 100 nm and the infrared range, for example, up to 1550 nm, can be used. Other wavelengths that differ from those used for radio standards are also possible. Optical wireless data transmission must also be distinguished from fiber-based optical data transmission, which is implemented, for example, using fiber optic cables or optical fibers.

[0036] Embodiments described herein refer to a near field and / or a far field, which are synonymously referred to as geometric near field and geometric far field, respectively.

[0037] The geometric near field is understood to be an area starting from the transmitter in which the position and size of individual elements of the receiver and transmitter, in addition to the radiation angle of the transmitter, play a major role in the reception level of optical wireless signals. In addition to the positions and dimensions, the angular ranges of the optics can also play a role. For example, a transmitter can emit the optical wireless signal in an angular range of -1° to +1°. If the acceptance angle of the receiver is smaller than the transmission angle, e.g. -0.5° to +0.5°, the angular effect also results in a loss, which, however, can be used as channel attenuation according to the invention and is initially not influenced by the spatial dimensions. In the geometric near field, in addition to the emission and reception angles, the lateral offset from transmitter to receiver, as well as the spatial extent of the transmitter and receiver aperture, also have an influence.

[0038] A different geometric far field, however, is understood as an area in which, starting from the transmitter, the radiation angle of the transmitter plays a major role, while the dimensions and position of the receiver components and the transmitter components, especially the optics, play a lesser role. A geometric far field, on the other hand, can be understood as an arrangement in which the emission characteristics of the transmitter and the reception characteristics of the receiver can be essentially described by their emission and reception angles, respectively.

[0039] The transition between the geometric near field and the geometric far field is fluid. Fig. 1 shows a schematic side sectional view of an optical wireless device 10. The optical wireless device 10 comprises a receiving device 12 configured to receive an optical wireless signal 14. The receiving device comprises an optical detector 16, which may, for example, comprise a photodiode, such as a PIN photodiode, an avalanche photodiode (APD), a single-photon avalanche photodiode (SPAD), and / or a silicon photomultiplier (SiPM).

[0040] Furthermore, the receiving device 12 has a plurality of optics 18i, 182. The number of optics in the plurality of optics is two or more, such as two, three, four, five or more.

[0041] At least some of the different optics 181 and 182 have a different aperture size, which is represented, for example, by a different size of the optics 181 and 182. In the illustration in Fig. 1, for example, the optic 181 has a first larger aperture size than the optic 182 with a second, smaller aperture size.

[0042] For further illustration, reference is made to a Cartesian coordinate system with axes a, b, and c, for example, where the axes are arranged orthogonally to one another in space merely by way of example. The optics 181 and 182 are arranged next to one another and have a substantially identical or matching preferred direction 22i and 222, respectively. These run, for example, along a negative a-direction, so that an arrangement of the optics 181 and 182 next to one another can be understood as an offset along a b-direction and / or c-direction, which does not exclude an additional offset along the a-direction. It should be noted that each of the optics 181 and 182 can be designed as a single optical element or as a combination of optical elements, for example as a single or multiple complex lens modules and / or as a combination of lenses and reflectors.

[0043] In the schematic representation of Fig. 1, the optics 181 and 182 are arranged offset from one another along the b-direction and spaced from one another. However, even with an additional offset along the c-direction, there could be an overlap between the optics 181 and 182 in a projection plane arranged parallel to the a-direction and b-direction. Each of the optics 181 and 182 is designed to direct light incident on the optics onto the optical detector 16, as shown by arrows 24i and 242. This occurs simultaneously, i.e., portions of the optical power incident on the optical detector are simultaneously detected by several optics and superimposed at the location of the optical detector. The superposition is preferably so low in interference, for example due to different paths of optical wireless signals, that correctably interference-affected or error-free reception is possible.

[0044] This means that when the optics 181 and 182 are simultaneously illuminated with the optical-wireless signal 14, it is possible for both optics 181 and 182 to simultaneously direct a corresponding portion onto the optical detector 16. When only a subset is illuminated, for example only one optic 181 or 182, it is also possible and provided within the scope of the exemplary embodiments described herein that only a subset of the optics 181 or 182 directs a portion onto the optical detector 16, but a portion of another optic is omitted or becomes negligible for the total optical power at the optical detector 16.

[0045] The optical detector 16 has an optical axis 26, which can, for example, extend in space along a main preferred direction of the optical detector 16. For example, the optical axis 26 additionally extends through a center point of a sensitivity curve, such as a geometric center point, of the optical detector 16 and / or is perpendicular to a detector surface of the optical detector 16.

[0046] The optics 181 have a distance 28i from the optical axis 26, while the optics 182 have a greater distance 282 from the optical axis 26. Coincident positions or features of the optics 181 and 182 can be considered as a reference point or reference range for determining the distance 28i and 282, for example, an optical center point or a position of the preferred directions 22i or 222, respectively. Alternatively, an outer edge or lateral boundary facing the optical axis 26 or other features can also be considered as a reference.

[0047] Such an arrangement of the optics 181 and 182 relative to one another and / or relative to the optical detector 16 makes it possible to assume different situations with regard to an emission angle 32 of the optical wireless signal 14 at different distances between the device 10, in particular the receiving device 12, and a transmitter of the optical wireless signal 14, in which, for example, at a comparatively large distance, several or even all of the optics 181 and 182 of the plurality of optics are illuminated or receive the optical wireless signal 14.A reduction in distance can result in at least one of the optics, such as optic 181, being less or no longer illuminated by the optical wireless signal 14, and correspondingly less power reaching the optical detector 16 through this optic, while possibly, but not necessarily, an increase in optical power through the other, still illuminated optic, i.e., optic 182. These two opposing effects can prevent saturation of the optical detector 16, even if the distance to the transmitter is significantly reduced.

[0048] In a preferred embodiment, the optical wireless device 10 can be positioned or arranged with respect to a transmitter in an optical wireless communication network or communication system such that the transmitter of the optical wireless signal 14 is arranged opposite an optic 182, also referred to as a secondary optic, with a smaller aperture, so that an optic referred to as the main optic with a larger aperture, the optic 181, is positioned out of an illumination cone of the optical wireless signal 14 as the distance to the transmitter decreases.

[0049] The distance 28i is smaller than the distance 282; preferably, the distance 28i is at least 0 or substantially 0 within manufacturing tolerances, meaning that the optics 181 can be arranged centrally above the optical detector 16. An arrangement above the optical detector 16 is not necessarily to be understood as meaning that a height direction must be considered for this purpose; such an indication refers to a direction along the optical axis 26. In general, in connection with the exemplary embodiments described herein, indications such as left, right, top, bottom, front, or rear are used merely for better illustration and have no restrictive effect unless explicitly stated. It is understood that such relative indications can be changed as desired by displacement and / or rotation in space.

[0050] An arrangement of the optics 181 above, centrally, or centered above the optical detector 16 simultaneously means that the optics 182 are arranged at a distance from the optical axis 26 of the optical detector 16. While the optics 18i can be designed to direct incident light along the preferred direction 22i of the optics 181 toward the optical detector 16, the optics 182 can be designed differently to direct incident light toward the optical detector 16 along a direction different from the preferred direction 222. This can be achieved through different optical effects with respect to refraction and / or reflection or the like, meaning that the optics 182 can change the direction of the light passing through the optics 182. The orientation of the preferred directions 22i and 222 can be arbitrarily along the positive or negative a-direction in space.The optics I82 can, for example, be designed for refraction and at least a first total reflection, but possibly also a second or further total reflection, in order to direct the incident light along the direction different from the preferred direction 222 towards the optical detector 16.

[0051] Fig. 2 shows a schematic representation of an optical wireless communication system 200 according to an embodiment, which comprises an optical wireless device 20 according to an embodiment and a further optical wireless device 25, which can be configured to transmit the optical wireless signal 14. The optical wireless device 25 can comprise a transmitting device 34, which can receive, for example, an optical emitter 36 and downstream transmitting optics 38. The transmitting device 34 can be configured to transmit the optical wireless signal 14 along a main transmission axis 42, which is arranged in space parallel to a preferred direction 41, for example but not necessarily parallel to the a-direction, and can be arranged, for example, in the region of a maximum optical power of the optical wireless signal 14.

[0052] An emission profile of the optical wireless signal 14 can be composed of any number of one, two, three, four, or more sub-profiles. For example, the transmitting device 25 can comprise an emitter array, a device for magnifying the apparent source on the transmitter side, or a device for generating multiple apparent sources from the optical emitter 36. According to a preferred embodiment of an optical wireless communication system, the transmitting device 34 is configured as a device for magnifying the apparent source or for generating multiple apparent sources from the optical emitter 36.It comprises the optical emitter 36 for generating an optical signal and a separation optics configured to spatially divide the optical signal into a plurality of optical sub-signals in order to divide an optical power of the optical signal among a plurality of optical sub-signals with an associated spectral range, wherein the plurality of spectral ranges at least partially coincide. Such a separation optics is described, for example, in [7], so that in such a case, the sub-signals 44i to 444 can be obtained in a corresponding number by the separation optics. Emission angles 46i to 464 of the sub-signals 44i to 444 can be the same or different from one another.Notwithstanding this, and independent of an implementation in a number of sub-signals, 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 with increasing distance from the transmitting device 34.

[0053] The optical-wireless device 20 can be configured in accordance with the discussions regarding the optical-wireless device 10 and, for example, has a receiver optics 48 that has at least two optics, such as optics 181 and 182. The receiver optics 48 can have an acceptance angle 52, which can, for example, cause a reception field of view 54 to have a planar extent, such as in a b / c plane, that increases with increasing distance 56i, 562 from the receiver optics 48. According to one embodiment, the optics 181 and 182 of the optical-wireless device 10 differ with respect to a size of a reception field of view assigned to the respective optics 181, 182. The main optics 181 can be the optics with the largest reception field of view of the plurality of optics.The reception field of view 54 is to be understood such that a respective optics I81, 182 has a reception field of view assigned to the optics, and the reception fields of view overlap in the plurality of optics.

[0054] Alternatively or additionally, with reference to Fig. 1, the optics 181 can have the smallest angle of incidence on the optical detector 16 among the plurality of optics. According to an exemplary embodiment based on this, optical axes between the receiving fields of view of the respective optics 181, 182 can run parallel to one another in a region between the receiving fields of view and the optics, so that each optic can have an individual optical axis 58, which can result in an overall optical axis 58 of the receiver optics 48. An optical axis 58i of the optics 181 is shown by way of example. Between the optics and the optical detector 16, with reference to Fig. 1, a respective optical axis can be inclined relative to an optical axis of the main optics, for example because the received light is deflected more strongly by the secondary optics than by the main optics, which may make a slight or no change in direction.According to one embodiment, in an optical wireless communication system, the optical axis 58i of the main optics 181 is offset from the main transmission axis 42 by a distance or offset 62. This can make it possible for the main optics 181 to no longer be illuminated by the optical wireless signal 14 if a distance 64 between transmitter and receiver is sufficiently reduced, and thus, and in particular with regard to a potentially largest aperture within the plurality of optics, to avoid saturation of the optical detector 16 by directing no or only low optical power through the main optics 181 onto the optical detector 16. According to one embodiment, the main transmission axis 42 can substantially coincide with an optical axis of a secondary optics of the plurality of optics, for example, with the optics having the smallest aperture.

[0055] This makes it possible to achieve that in an optical wireless communication system, at different distances between the optical wireless devices 20 and 25, a different number of optics of the receiving device 12 are illuminated with the transmitted optical wireless signal 14 and contribute to a total optical power directed to the detector 16.

[0056] According to one embodiment, the optics 18i, as a main optic of the plurality of optics, can provide a dominant portion of the total optical power at the optical detector 16 in a geometric far field of the optical transmitting device 34, and a secondary optics, such as the optics 182 from Fig. 1, can provide a dominant portion of the total optical power at the optical detector 16 in a geometric near field of the transmitting device 34.

[0057] With reference to the main transmission axis 42, the secondary optics or all secondary optics can be arranged at a smaller distance from the main transmission axis 42 than the main optics 181.

[0058] It is preferred if an acceptance angle 52 of the plurality of optics, ie of the receiving device 12, is smaller than the resulting total emission angle of the transmitting device 12.

[0059] Fig. 2 initially considers a possible unidirectional link from the optical wireless device 25 to the optical wireless device 20. By arranging a corresponding transmitting device on or in the device 20 and arranging a suitable receiving device on or in the device 25, a bidirectional link can be enabled. In other words, some of the previous considerations are initially limited to a unidirectional link, i.e., a data connection consisting of a transmitter 25 and a receiver 20. All concepts considered here can also be extended to bidirectional communication. Design examples for bidirectional transceivers will be discussed below.

[0060] Although the discussion refers to optical-wireless / optical-wireless communication, the invention can also be extended to other applications in which an optical emitter and an optical receiver are used and a large dynamic range between the two is to be ensured. This also applies, for example, to optical distance meters. This means that the optical-wireless device 10 and / or 20 can possibly be used for communication, but the optical-wireless signal 14 can also carry a different type of information, such as for distance measurement.

[0061] In other words, Fig. 2 shows a schematic representation of an optical wireless transmitter-receiver system, which consists of, or at least comprises, a transmitter 25, an optical free-space channel, and a receiver 20. The transmitter 25 consists of at least one optical emitter 36, such as a laser diode (LD) or a light-emitting diode (LED). In most cases, a transmitting optic 38 can also be used, which can be, for example, a refractive lens or a totally reflecting lens. This transmitting optic 38 can shape the emission profile. The emission angle 46 can indicate the angle at which the rays of the optical wireless signal 14 are emitted at their maximum. The rays can be emitted along a preferred direction 41. The preferred direction 41 can correspond to the axis a, but this is not mandatory.The reference numeral 42 denotes, for example, the optical axis of the transmitter 34, and the reference numeral 58i denotes the optical axis of the main receiving lens 181 of the optical-wireless device 20. The receiver 12 consists of or includes the optical detector 16 and the receiving optics 48. The receiving optics 48 has the acceptance angle 52.

[0062] Embodiments enable the discussed high dynamic range by deliberately increasing channel loss at short communication distances 64, for example, by moving at least one, and in particular the main, optics out of a light cone of the optical wireless signal 14. At long distances 64, however, no additional channel loss is introduced. Embodiments are based on the realization that one or more of the following effects can be deliberately used to suitably control channel loss:

[0063] • the offset 62 between the optical axis 42 of the transmitter 25 and the optical axis 58i of the main receiving lens 18i; and / or

[0064] • the choice of a smaller acceptance angle 52 compared to a larger emission angle 46.

[0065] To further increase the practicality of the embodiments described herein, it is advantageous to provide for an alignment tolerance perpendicular to the optical axis 42 and / or 58i to be tolerable and the communication system to still function. This can be achieved by:

[0066] • The transmitting optics 38 have a parallel output beam or a low-divergence output beam and / or a magnified source or multiple apparent sources. This is indicated in Fig. 2 by showing a larger apparent source, which may consist of multiple beams 44I-444. This can be achieved, among other things, as follows:

[0067] ■ a single optical emitter 36 in conjunction with a multi-path lens or separation optics, which is preferred in connection with the present embodiments; and / or

[0068] ■ several optical emitters, such as LED arrays and / or laser arrays, in conjunction with an optional lens array; and / or

[0069] ■ one or more optical emitters and a diffuser, such as a scattering diffuser, an engineered diffuser, a color converter or the like). o From the modeling standpoint, the output profile of the optical wireless transmitter can then be viewed as a plurality of sources, countable or uncountable, which may initially have the same or at least a similar emission profile. • The receive optics 48 has, as described in connection with Fig. 1, a main receive lens 181 and at least one secondary lens 182. The secondary lens 182 can be located in the geometric near field within a field of view of the transmitter 25, as shown in Fig. 3a. The secondary lens 182 can also concentrate the incident light onto the photodetector 16.The reception power in the geometric near range can be adjusted by dimensioning the secondary lens 182 in relation to the area and offset 622 to the optical axis 42 of the transmitter 25, and the reception power in the geometric far range can be adjusted by the main reception lens 181.

[0070] Fig. 3a shows a schematic side sectional view of an arrangement of the transmitting device 34 and a receiving device 12' in accordance with embodiments described herein. The receiving device 12' can essentially correspond to the embodiments of the receiving device 12, wherein, as an advantageous optional further feature, at least one optic from the plurality of optics, here for example the optics 181 and 182, is fixed with respect to their relative position to one another via a connecting structure 66. The connecting structure 66 can have an optical property, but this is not required. One task of the connecting structure 66 is the relative positioning and / or fixation of the optics 181 and 182 connected thereto.For example, the connecting structure 66 can be retained and used during injection molding or another molding process, for example, to introduce material into a mold and locate potentially resulting artifacts in an optically irrelevant area, while simultaneously simplifying manufacturing, since at least a portion of the majority of the optics can be manufactured in a single process step. It is possible for the connecting structure and one or more optics connected to it or fixed relative to one another to form a common monolithic body.

[0071] In Fig. 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. Fig. 3b shows a schematic side 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.

[0072] One possible operation of the optical wireless communication system can be such that the transmitter 34 emits optical radiation 14 in a well-defined emission range / emission profile 44, which here can, for example, but not necessarily, have multiple virtual sources. The radiation is emitted along the preferred direction parallel to direction a along the optical axis 42. Opposite this is the receiver 12', whose optical axis 58i of the main receiving lens 181 can have the offset 62i from the axis 42. The offset 62i can be measured perpendicular to the optical axis 42 and, in the described embodiment, can lie in a plane parallel to the b-direction and c-direction. The optical axes 58i and 582 can be arranged at a distance 74 from one another.

[0073] The receiving optics 48 can direct the incident radiation onto the detector 16. The receiving optics 48 comprises at least two optically active parts, the main receiving lens 181, which offers a large optical concentration factor and is not irradiated or is irradiated only to a lesser extent of at most 20%, at most 10%, or at most 5% in the geometric near field than in the geometric far field, and transmits power to the optical detector 16. It is possible, for example, that when the transmitting optics and the main optics 181 are aligned parallel but opposite to one another, an emission angle of the transmitting device 34 is greater than an acceptance angle of the main optics 181, which can lead to the main optics 181 still being illuminated by the optical wireless signal 14 at certain distances due to the angular difference, but this signal is not transmitted to the optical detector.The secondary optics 182, on the other hand, can act both in the geometric near field and in the geometric far field since it is irradiated to a similar extent in both cases, although its influence in the far field is rather negligible in some embodiments.

[0074] The main optics or main receiving lens 181 can be any imaging or non-imaging optics for concentrating, such as a spherical lens, an aspherical lens, a freeform lens, a totally reflecting lens, a reflector, a so-called compound parabolic concentrator (a concentrator composed of at least two curves, CPC), or the like. The main receiving lens or main optics 181 is arranged, for example, centrally above the photodetector 16 to enable the high concentration factor. The main receiving lens 181 can simultaneously have the smallest or lowest angle of incidence 68 from the group of angles of incidence 681, 682 of the plurality of optics 181, 182 to the photodetector 16.The secondary lens 182 can accordingly be offset from the photodetector 16 and direct the incident radiation onto the detector 16 at an angle 682, as illustrated by the beam bundles 72i for the optics 181 and the beam bundle 722 for the optics 182. According to exemplary embodiments, 681 < 682 can apply. The beam bundles 72i and 722 schematically indicate how the beam path can be implemented in the design example. This path can also deviate from this, for example, with the aid of additional optical components for beam steering or even optical fibers. The optical axis 582 of the secondary optics 182 can be different from the optical axis 58i of the main receiving optics 181. According to embodiments, the optical axis 182 can be arranged at least substantially or completely identically or coincidentally to the optical axis 42 of the transmitter 34 or can have an intentional or tolerance-related offset 622.This means that the offset 622 can essentially also correspond to the value 0.

[0075] The offset 622 is typically smaller than the offset 62i. The secondary lens 182 can be a lens or a reflector, or a combination thereof. In the case of a lens, it is conceivable that the lens uses refraction and / or total internal reflection to redirect the radiation.

[0076] Fig. 4a shows a schematic top view of an optical wireless device 40 according to one embodiment. For clarity, the optical detector 16 is not shown. However, the optical wireless device 40 can have a transmitting device 76, which can be formed in correspondence with the transmitting device 34 and can enable a bidirectional exchange of optical wireless signals. Axes 78i and 782 are shown by way of example to divide the illustrated side of a housing 82 into quadrants 84i-844.

[0077] According to a preferred embodiment, the optical-wireless device 40 is designed such that a structurally identical further device 40 can be precisely configured for bidirectional exchange in order to utilize the inventive advantages on both sides of the communication link. In a juxtaposition, i.e., an arrangement of the device 40 and its copy opposite one another, as indicated, for example, in Figs. 3a and 3b, an arrangement can be obtained such that, in the arrangement of the transmitting device 76 and at least the main optics 181 and secondary optics 182, which can optionally be connected by the connecting structure 66, the secondary optics 182 has a shorter distance from a transmission power center 86, for example an origin of the main transmission axis 42, than the main optics of the copy.If an exemplary copy is rotated approximately 180° around axis 782 and shifted in space along the negative a-direction, the copied transmitting device 76 would overlap with the optics 182 when projected into the c / b plane; the secondary optics 182 might even overlap the copied power center. The main optics 181, on the other hand, would be spaced apart from the copied transmitting device and might only be illuminated by the optical-wireless signal if the distance between device 40 and its copy is sufficiently large.

[0078] Although the main optics 181 is shown as round, it may also have a different shape, for example an at least substantially rectangular cross-section, for example by additionally rounded edges as shown by way of example in Fig. 4d or the like.

[0079] Embodiments allow a receiving device of an optical wireless device to be configured to receive the received optical wireless signal of a transmitting optical wireless transmitter both in a geometric near field and in a geometric far field and to detect it without saturation using the optical detector 16. This aspect can also be implemented independently of the specific geometry of the optics described in connection with Fig. 1.

[0080] Each of the optics 181 and 182 can have a respective receiving field of view or this can be assigned to the optics. The receiving fields of view of the plurality of optics can have a different size from one another, which can be expressed, for example, in different angles of incidence and / or the aperture size. The receiving fields of view of the plurality of optics overlap at most incompletely, so that a location of the optical transmitter with a varying distance between transmitter and receiver can lead to the transmitter not being seen by at least one receiving optic at certain distances and thus not directing its light to the optical detector 16. At a different distance, in turn, the same receiving optics can see the transmitter, i.e., it is irradiated by the transmitter, and can thus direct the signal to the detector 16.

[0081] Fig. 4b shows an expanded representation of the device 40 to include the transmitting device 34 of the copy of the device 40. Due to the rotation about the axis 782, the transmitting device 34, which is identical in construction to the transmitting device 76, is located opposite the secondary optics 182, whereby the offset 62 is clearly visible.

[0082] In other words, Fig. 4a shows a front view of an embodiment of a bidirectional communication link. For a product, it is advantageous if all devices are identical and the peripherals, such as cable connections or the like, are located on the same side. The discussed advantageous arrangement according to embodiments, as shown in Fig. 4a, can arrange the transmitter 76 and receiver, represented by optics 181 and 182, on one side of the housing 82, so that the previously described optical arrangement is achieved. The transmitter device 76 can be used by the device 40 to implement a return channel. If the device 40 is rotated by 180° about the axis b or 782, the transmitter and receiver are each positioned opposite each other such that the optical axis of the secondary lens is approximately or exactly on the optical axis of the transmitter or has a predefined offset. The secondary lens 182 can thus cover the geometric near field.The main receiving lens I81, however, is located on the optical axis of the optical detector 16.

[0083] In other words, for better illustration, the representation in Fig. 4b shows the same system, with the transmitter 34 of the opposing device drawn in to clarify the relative positions of the transmitter 34 / 76 and the receiver 181, 182. Alternatively or additionally, it is conceivable to design both receiving lenses as a single complex lens module, which can reduce the number of components to be manufactured and assembled. In this case, for example, the components, parts, or lenses 181 and 182 could be connected via a connecting structure 66, possibly formed as a web. The connecting structure 66 does not have to fulfill an optical function.

[0084] Fig. 4c shows a schematic, only partially perspective view of two devices 40a and 40b, which are mutual copies of each other and are used to discuss the statements regarding Fig. 4a and Fig. 4b. Due to the described embodiment, it is possible for the respective secondary optics 182a and 182b to be arranged opposite one another with respect to the respective transmitting device 76b or 76a of the other device, approximately along the a-direction. An illuminated area 88a or 88b of the respective transmitting device 76a or 76b is variable due to the described emission angle by the distance 64 and becomes larger as the distance 64 from the transmitter increases. As can be seen from Fig. 4c, a reduction in the distance 64 can lead to the main optics 18i a and 18i bare illuminated decreasingly and are not illuminated or at least only partially illuminated as the distance decreases further. Deviating from the illustration in Figs. 4a and 4b, it would also be conceivable for the main receiving lens 181 to be designed differently and, for example, cover a large part of the housing area or the entire lower area of ​​the housing. For example, a predominant or even entire portion of quadrants 84a and 844 can be covered by the lens, or even part of quadrants 84i and 842. For example, it could be a lens with a rectangular cross-section in order to make optimal use of the space, as is shown, for example, in Fig. 4d. The shape of the optics 181 shown there is understood to be rectangular, regardless of the rounded corners, since at least 80%, 90% or 95% of the outer edges are straight and would form a quadrilateral if extended accordingly.In general, the cross-section of the main receiving lens 181 can be arbitrary. It is advantageous for the secondary lens 182 to be at least approximately level with the transmitter 76 along direction b when the system is rotated about the axis 782.

[0085] In other words, the system can function well if the system is rotated around axis 782 and the transmitter covers part of the upper left half and the secondary lens covers part of the right half. The extent of the components along the b-axis may play a minor role in the basic function. However, the aim can be to make the distance between a respective transmitter device 76 and the main optics 181 along the b-axis as large as possible so that the power maximum 99 shown in Fig. 5 only occurs at the greatest possible distance x and is thus correspondingly small.

[0086] It is fundamentally conceivable that the system could also be rotated around a different axis, and the transmitters and receivers arranged accordingly to achieve a similarly effective arrangement in the geometric near field and geometric far field. Rotating the device around axis 782 is particularly advantageous, as possible cables and connectors on both devices can be directed downwards or upwards, for example, in the positive b-direction or negative b-direction.

[0087] In a configuration that is particularly robust against placement tolerances of the transmitter and receiver, the transmitting lens of the transmitting device 76 can cover at least one quadrant of the housing 82, such as quadrant 84i. The secondary lens 182 can, for example, be located approximately in the center of the adjacent quadrant 84i, such that, when the device is positioned opposite, the secondary lens 182 is positioned exactly or at least approximately on the optical axis of the transmitter. In this case, both devices can be displaced relative to each other to a maximum extent before the secondary optics 182 of the opposing device is no longer directly in front of the transmitter 76.

[0088] Fig. 5 shows a schematic characteristic curve for discussing embodiments described herein. The graph shows an optical radiant power or radiant flux on the ordinate. <t>, where value <t> m into a lower detection threshold of an exemplary optical receiver or receiving device and <t> ma x is an upper threshold above which the receiver operates poorly, approximately reaching saturation. On the abscissa, a distance x is plotted, approximately the distance 64 between transmitter and receiver. At a maximum distance x ma x, starting from larger distances, the optical power received by a transmitter by means of an optical-wireless signal 14 increases until the minimum power <t> m in is reached and the optical detector 16 is able to process the signal according to the specification. The specification here is understood to mean normal operation, because even below this threshold, a signal can be physically received and possibly evaluated, but may be decoded with an unacceptable error rate, which is why the threshold <t> m can be system dependent.

[0089] A characteristic curve 92i shows an exemplary profile of an optical power which is directed by the main optics 181 onto the optical detector 16. A characteristic curve 922 shows an exemplary schematic profile of an optical power which can be directed by the secondary lens 182 onto the optical detector 16. Due to the smaller aperture, the secondary optics 182 would only deliver sufficient optical power to the optical detector 16 at a significantly smaller distance. It can be seen that the secondary optics delivers a negligible contribution in the geometric far field, and that in the geometric far field the main optics delivers a dominant contribution to the total optical power at the optical detector 16.In the combined characteristic curve 94, which shows a sum of the characteristic curves 92i and 922, it can be seen that at a distance Xi the power provided by the main optics I81 decreases and deviates from an expected curve 96, the reason for this being that the main optics 181 is illuminated less and, with further decreasing distance x, possibly no longer by the optical-wireless transmitter.

[0090] In the geometric near field, the optical power of the secondary optics 182 becomes the dominant component, since the main optics 181 is no longer illuminated when the distance X2 is undershot. Here, the optical power can increase until a minimum distance X3 is reached. By appropriately designing the individual components, this can be achieved in such a way that the total power represented by the characteristic curve 94 is always within the working interval below the power <t> ma x. A performance level 98 can be corrected and adjusted accordingly. A maximum 99 can be designed by designing the corresponding components, which is represented by arrow 101.

[0091] In other words, Fig. 5 shows the received power plotted on the vertical axis against the distance between transmitter and receiver along the x-axis. The horizontal line <t> ma x marks the maximum power at which the receiver still operates within specifications. The horizontal line <t> m in marks the minimum power at which the receiver still operates within specifications. Only when the received power 94 lies between these two values ​​does the function fulfill the requirements of the example.

[0092] In other words, the characteristic curve 92i can exemplarily show the received power that the main receiving lens 181 directs onto the photodetector 16 of Fig. 1, wherein the statements also apply readily to other embodiments described herein. Coming from large distances, the received power can increase with decreasing communication distance, smaller x values. If the transmitter and the main receiving lens 18i did not have an offset 62i, i.e., if their optical axes 42 and 58i were identical, the received power would continue to increase, as indicated by the line 96. Due to the offset 62i, the transmitter gradually moves out of the field of view of the main receiving lens 181 at short distances, so that the received power does not continue to increase, but eventually reaches a maximum value and can finally decrease rapidly for even shorter distances.The received power directed by the secondary lens 182 to the detector 16 is shown as curve 922. The total power incident on the detector 16 may correspond to the sum of the main optics 181 and the at least one secondary optics 182 and is shown for the structure of the devices 10 and 40 as curve 94. A system that would use only the offset main lens 182 would have a dynamic range 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, whereas the maximum range x max is not negatively affected. Although the secondary lens 182 can also direct power to the detector 16 at great distances, due to the smaller aperture designs, this power share can be significantly lower than the share received by the main optics 181. Embodiments provide for matching the characteristic curves 92i and 922 to achieve the maximum power <t> ma x or within the working range the minimum power <t>min. One or more of the following design parameters are particularly suitable for influencing the characteristic curves 92i, 922 and / or 94. A particularly tolerant overall system with regard to system tolerances, but also alignment tolerances, can result if, in particular, the characteristic curve 922 determines the maximum distance to the lower and upper power limits <t> m in or <t> ma x, ie, is located approximately in the middle thereof. Parameters of the main receiving optics 18i, which can change the characteristic curve 92i, in particular for adjusting the maximum power level along the arrow 101, can be:

[0093] • an offset of the optical axes 42 and 58i, see for example Fig. 2, ie the offset 62 between the transmitter and the main receiving lens 181; o the greater the offset 62, the greater the distance at which the maximum of the detected power occurs, ie the maximum can be shifted along the arrow 101. The direction of the arrows 101 corresponds approximately to the course of the curve 96, with the actual maximum value lying below the curve 96. The maximum value, ie the maximum power, can decrease accordingly with increasing offset, since the main receiving lens 181 can only detect radiation from the transmitter at greater distances. At a greater distance, the power density is lower.

[0094] • An acceptance angle 52 of the main receiving lens or adjustments of the optical concentration factor depending on the angle of incidence of the radiation;

[0095] • Dimensions of the main receiving lens 181 and coupling angles 681, 682 to the detector element 16.

[0096] Alternatively or additionally, parameters for adjusting the secondary reception optics 182, which can change the characteristic curve 922, in particular for adjusting the power level 98, may include:

[0097] • a position of the secondary optics 182 with respect to the opposite transmitter, ie the offset 622 of Fig. 3a;

[0098] • Position of the secondary receiving lens 182 in relation to the detector 16, ie also the coupling angle 682 to the detector

[0099] • an aperture size of the secondary optics 182, an acceptance angle of the secondary receiving optics 182, as well as its angle-dependent efficiency of radiation guidance to the detector 16

[0100] Alternatively or additionally, parameters of the transmitter's emission profile can be changed, for example to change the characteristics 92i or 94.

[0101] • The transmitter can distribute the optical power so that it is distributed homogeneously across the output aperture, or so that each virtual source has a similar power. The opposite is also possible; for example, a greater power density could occur in the center of the transmitter's output aperture than at the edge. By varying the local power density, the power signal of the secondary optics I82 can be influenced. Such a distribution can also influence the power directed by the main receiving lens I81 to the detector 16. This occurs precisely when the transmitter is located at the edge of the main receiving lens's field of view and the main receiving lens only sees part of the transmitter aperture.

[0102] • The channel loss and thus the reception level of the characteristic curves 922, 94 can depend on the emission angle and the acceptance angles of the main reception optics 181 and the secondary optics 182. Accordingly, both characteristic curves can be influenced by changing the emission angle across the output aperture of the transmitter. For example, each virtual source located directly opposite the secondary optics 182 could 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 reverse case, i.e., larger emission angles to reduce the detected power, is also possible.

[0103] With reference to Fig. 4d, an optical wireless communication system according to one embodiment can be configured for a minimum distance X3 between a mutually movably arranged optical wireless transmitter and optical wireless receiver, or between two transceivers. The minimum distance can, for example, result from or be influenced by a working area within which communication is to take place. A minimum tolerance of the optical wireless communication system with respect to positioning inaccuracies with respect to an offset of the components relative to one another along the directions c and / or a and / or with respect to a tilt of the main optical axes relative to one another can be determined by a size or aperture of the transmitting optics.This can be represented in such a way that, at the minimum distance, the secondary optics of the optical wireless receiver are at least partially opposite the transmitting optics of the optical wireless transmitter in such a way that the emitted optical power is still sufficiently directed by the secondary optics onto the optical detector.

[0104] Fig. 6 shows a schematic front view of an optical-wireless device 60 according to an embodiment. This device can be configured similarly to device 40, but can have a plurality of secondary optics 182, 183, and 184. The secondary optics 182-184 can be arranged in any number, for example 1, as shown in Fig. 4a and Fig. 4b, 2, 3, 4, or more. It is preferred if the plurality of secondary optics 182-184 are arranged relative to the main optics 181 such that the secondary optics 182-184 have a decreasing aperture size with increasing distance from an optical center 1021 of the main optics 181. This is illustrated in Fig. 6 by different sizes and, in particular, by decreasing sizes of the optics 182-184 along the offset 62, whereby other means for reducing an aperture size can also be used, such as a lens shape other than a round one.

[0105] The plurality of optics I81-I84 can possibly be manufactured as a common body, which can have different optically active regions in the region of the optics 181-I84. Alternatively or additionally, the optics can also be spaced apart from one another and connected to one another, for example, via a connecting structure 66, in order to achieve high positioning precision.

[0106] The secondary optics 182, 183, 184 can be arranged along a straight line, but can also be arranged with respect to their optical centers 1022, 102s and 1024 along a merely partial straight line or along a curve or the like, as shown, for example, in Fig. 6.

[0107] In other words, in general terms compared to the other exemplary embodiments, an implementation can be provided in which not just one secondary lens 182 is arranged, but a number of N>2 secondary lenses 182, 183, 184, ... , wherein each of these secondary lenses or secondary optics can be optimized for a specific distance range. This embodiment has the advantage that the maximum in the reception level can be further reduced, i.e. the dynamic range can be further improved or the reception power can be further smoothed over the distance. Fig. 6 shows a front view of how exemplary secondary lenses or secondary optics 182, 183, 184 can be arranged. There are different arrangements, wherein an attempt can be made to reduce the offset 62i or the individual offset of a secondary optic to the optical axis of the transmitter 34 with each additional secondary lens.The secondary optics can be designed such that the greater the offset 62I-624 from the optical axis of the transmitter 34, the less power the lens focuses in the geometric near field and the more in the geometric far field. The further explanations in connection with Figs. 4a and 4b apply analogously here. For clarity, the transmitter 34 is shown only as a border without shading, but can have the same functionality as described in connection with Fig. 4b.

[0108] Fig. 7 shows a schematic graph of an exemplary total intensity <t>, as can be obtained, for example, with an optical arrangement of the optical-wireless device 60. Unlike the illustration in Fig. 5, an overall characteristic curve 94' can be formed from four characteristic curves 92i, 922, 923, 924, analogous to the number of main optics and secondary optics of the device 60. By appropriately designing the transmitter 34 and the alignment thereto, the course of the characteristic curve 94' can be more uniform compared to the characteristic curve 94 from Fig. 5, which is advantageous.

[0109] In other words, Fig. 7 shows an exemplary graph of the received power corresponding to Fig. 6 for the device 60 together with the transmitter 34, which together can form an exemplary system. Each of the secondary receiving lenses 182, 183, 184 can generate a received power on the detector 16 of the receiving device, just like the main optics 181. These are collectively represented by the corresponding characteristic curves 92i, 922, 92a, and 924. The sum of the power incident on the detector 16 is represented by the characteristic curve 94'. By using a plurality of secondary lenses, it becomes clear that the fluctuations in the received level can be significantly reduced.

[0110] In an optical wireless communication system described herein, the plurality of optics of the receiving device of a first optical wireless device, on the one hand, and the transmission power of the transmitting optical wireless device, on the other hand, can be adapted to one another. At any distance between the first optical wireless device and the second optical wireless device, the optical detector 16 can remain saturation-free, as illustrated by both the illustrations in Fig. 5 and Fig. 7. According to one exemplary embodiment, the plurality of optics can have a first optic as the main optic, such as optic 18i, and a plurality of secondary optics, as described in connection with Fig. 6. Each of the plurality of secondary optics can be configured for an optic-specific distance range from the second optical wireless device, which at most incompletely overlaps with a distance range of another secondary optic.This may mean, for example, that a relevant region or a region exhibiting the maximum optical power is shifted relative to each other, as shown, for example, in Fig. 7. The adjustment can be achieved by selecting the offset along directions b and / or c in the coordinate system of Fig. 6; alternatively or additionally, it can also include a lens type and / or an aperture size. For this purpose, an optical axis of the transmitter 34 can be taken into account, as can a transmission power of the transmitter 34.

[0111] According to one embodiment, in an optical wireless communication system, an emission angle of a transmitting device of the transmitting optical wireless device may be greater than a total field of view angle or total acceptance angle of the plurality of optics of the receiving optical wireless device. This may allow for a certain tolerance to tilting in the arrangement of the transmitter and receiver.

[0112] Fig. 8 shows a schematic flow diagram of a method 800 according to an embodiment. A step 810 comprises laying out and positioning a plurality of optical systems with respect to a transmitting device configured to provide an optical wireless signal. This can be done such that the plurality of optical systems simultaneously direct a received optical wireless signal to an optical detector 16 of the receiving device, so that at different distances between the receiving device and the transmitting device, a different number of the plurality of optical systems contributes to a total optical power directed to an optical detector 16 of the receiving device.

[0113] A step 820 includes manufacturing the plurality of optics in an arrangement according to the design and positioning.

[0114] According to one embodiment, the design and positioning 810 includes taking into account at least one of an aperture angle of the transmitting device, a transmission power of the transmitting device, a power distribution across the output aperture of the transmitting device, a relative distance of the plurality of optics from one another and from the optical axis of the transmitting device, an acceptance angle of the plurality of optics, the geometric shapes of the apertures of the plurality of optics, and / or a saturation limit of an optical detector 16 of the receiving device.

[0115] It is particularly advantageous if the parameters of the transmitting device and the receiving device are known and taken into account in step 810. However, even with only rough information regarding the transmitter or an estimated property of the transmitter, an advantageous design of the receiving optics can be achieved, for example, by assuming an average transmission power and / or an average or expected size of the transmitter, or the like. This can still enable a relevant improvement over known concepts.

[0116] Examples of such applications include optical data barriers. Data can be transmitted along a linear axis, with each transceiver being either stationary or mobile. Such arrangements are found, for example, in overhead, bridge, and harbor cranes; in mobile trolleys; in mobile carts for transporting wages, pallets, and lattice boxes; or in automated parking systems for horizontal or vertical parking. Harbor cranes, for example, require a high dynamic range because they can be moved within a few centimeters of a transmitter, yet can also be several hundred meters away.

[0117] Embodiments enable components for an optical wireless transmit and receive system or such a system with one or more of the following features:

[0118] • a transmitter for transmitting an optical wireless signal;

[0119] • a receiver for receiving an optical wireless signal;

[0120] • the receiver has a detector;

[0121] • the receiver has a lens module or optical module which comprises a main receiving lens, the optical axis of which is offset from the optical axis of the transmitter;

[0122] • the receiver comprises at least one secondary receiving lens, the optical axis of which has a smaller offset to the optical axis of the transmitter compared to the main receiving lens or no offset at all to the optical axis of the transmitter.

[0123] A feature of further aspects relates to the fact that the field of view angle of the transmitter is larger than that of the receiver and the field of view angle of the main receiving lens can also be designed differently than the field of view angle of the secondary receiving lens.

[0124] The embodiments described herein relate to an optical concept of transmitter and receiver which, compared to known concepts, may not require additional components in order to improve the dynamic range, but is based on a defined geometric transmitter and receiver arrangement. Additional components can be avoided, in particular, by designing the main and secondary optics as integral or monolithic components. Even if the optics are manufactured as separate components, these additional components are then simple and inexpensive to use. To implement the invention, it may be sufficient to implement a single receiver, so that the complexity of the electronics is not unnecessarily increased. This problem can be solved simply by designing the transmitter and receiver optics, which are required in the system anyway.The secondary receiving optics can therefore be considered a configuration within an existing component. Furthermore, the concept requires only a marginal modification of the design of the transmitting and receiving optics with regard to optical efficiency / performance in the optical channel compared to known solutions. Thus, in embodiments, no or only minimal radiation can be used at comparatively large angles, which would no longer be usable over long distances. The present invention enables a comparatively large tolerance with respect to a lateral offset of the devices relative to one another perpendicular to the optical axis, which can occur in practice due to tolerances. Advantages of the exemplary embodiments described herein include, among others:

[0125] • high to very high efficiency, since no power loss has to be accepted in order to cover the geometric near field;

[0126] • a very high achievable dynamic range;

[0127] • robustness against mechanical misalignment of transmitter and receiver;

[0128] • low channel crosstalk; • no need for an active control loop, which also eliminates frequency dependence;

[0129] • only an existing detector is required;

[0130] • only an existing transmitting lens is required;

[0131] • a complex lens module on the receiver is sufficient; a receiving lens is already present, which is divided into two or more lenses / optics in some designs.

[0132] • Compatibility with other approaches that introduce additional control, such as adaptive transmitter performance

[0133] Although some aspects have been described in connection with a device, it is understood that these aspects also represent a description of the corresponding method, so that a block or component of a device can also be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block, detail, or feature of a corresponding device.

[0134] 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 invention be limited only by the scope of the following claims and not by the specific details presented in the description and explanation of the embodiments herein.

[0135] Literature:

[0136] [1] ROJAS CALVENTE FRANCISCO; SUMASTA PAMUNGKAS: METHOD AND APPARATUS FOR AVOIDING SATURATION IN OPTICAL WIRELESS POINT-TO-POINT SYSTEMS, W022200124 A1, SIGNIFY HOLDING BV.

[0137] [2] S. Huang and M. Safari, "Reliable Optical Receiver for Highly Dynamic Wireless Channels: An Experimental Demonstration," 2021 IEEE Global Communications Conference (GLOBECOM), 2021, pp. 1-6, doi: 10.1109 / GLOBECOM46510.2021.9685634.

[0138] [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, US 10,547,385 B2, ams Sensors Singapore Pte. Ltd., Singapore (SCJ)

[0139] [4] Fritz Gfeller, WIRELESS OPTICAL TRANSMISSION SYSTEM WITH ADAPTIVE DATA TRANSMISSION RATE, DE 694 11 954.7, International Business Machines Corporation, Armonk, NY, US, int. Publication date: 26.10.1995

[0140] [5] Yakov G. Soskind, Thirukumar Vethanayagam “Optical Receiver With High Dynamic Range”, US 6,954, 580B2, JDS Unipahse Corporation, October 11, 2005.

[0141] [6] Eken, Yalcin Alper, Oguz, Alp, WIDE DYNAMIC RANGE ANALOGUE FRONT-END RECEIVER FOR LONG-RANGE LIDAR, DE 10 2018 106 762 A1 Analog Devices Global Unlimited Company, publication: 2018.09.27.

[0142] [7] Kirrbach, Rene; Schneider, T., "Eye-safe optical wireless communication”, WO 2021 / 228697 A1 , Publication: 18.11.2021< / t> < / t> < / t> < / t> < / t> < / t> < / t> < / t> < / t> < / t> < / t> < / t> < / t>

Claims

Patent claims 1. An optical wireless device, comprising a receiving device (12) configured to receive an optical wireless signal (14); wherein the receiving device (12) comprises an optical detector (16) for detecting the optical wireless signal (14) and a plurality of optical units (181-184) having at least a first optical unit (181) with a first aperture size and a second optical unit (182) with a second, smaller aperture size, which are arranged adjacent to one another and substantially with the same preferred direction (22i, 222); wherein each of the plurality of optical units (181-184) is configured to simultaneously direct light incident on the optical unit onto the optical detector (16); wherein the optical detector (16) has an optical axis (26) and the first optics (181) are arranged at a first distance (28i) from the optical axis (26) and the second optics (182) are arranged at a greater second distance (282) from the optical axis (26).

2. The optical wireless device of claim 1, wherein the first optic (181) is arranged centrally above the optical detector (16); and the second optic (182) is arranged spaced apart from the optical axis (26) of the optical detector (16).

3. Optical wireless device according to claim 1 or 2, wherein the first optic is spaced from the second optic.

4. Optically wireless device according to one of the preceding claims, wherein the first optics (181) are configured to direct incident light along a preferred direction (22i) of the first optics (181) toward the optical detector (16); wherein the second optics (182) are configured to direct incident light along a direction different from a preferred direction (22i) of the first optics (181) toward the optical detector (16).

5. Optical-wireless device according to claim 4, wherein the first optic (181) and the second optic (182) differ with respect to a size of a reception field of view associated with the respective optic and the first optic (181) is the optic with the largest reception field of view (54) of the plurality of optics (181-184).

6. Optically wireless device according to claim 4 or 5, wherein the second optics (182) are designed for refraction and at least a first total reflection in order to direct the incident light along the direction different from the preferred direction (22i) of the first optics (181) towards the optical detector (16).

7. An optical wireless device according to one of the preceding claims, wherein the first optic (181) is a main optic of the plurality of optics (181-184) and has a smallest angle of incidence (681) on the optical detector (16) within the plurality of optics (181-184); wherein the second optic (182) is a secondary optic of the plurality of optics (181-184).

8. Optically wireless device according to claim 7, wherein in a region between the plurality of optics (I81-I84) and the receiving fields of view (54) assigned to the respective optics, an optical axis (58i) of the main optics is substantially parallel to an optical axis (582) of the secondary optics; and in a region between the plurality of optics (I81-I84) and the optical detector (16), an optical axis of the secondary optics is inclined with respect to an optical axis of the main optics.

9. Optical wireless device according to claim 6 or 7, wherein the optical wireless signal (14) is a first optical wireless signal received from a receiving direction; wherein the optical wireless device has a transmitting device (76) for transmitting a second optical wireless signal along a transmitting direction arranged parallel to and opposite to the receiving direction; wherein the transmitting device is arranged with respect to the receiving device (12) such that a juxtaposition of a copy (40b) of the optical wireless device to the optical wireless device results in the secondary optics of the copy having a smaller distance to a transmitting power center with respect to an arrangement of the receiving device (12) and the transmitting device (76b) of the copy. (42, 86) of the transmitting device of the optical-wireless device than the main optics of the copy (40b).

10. Optical wireless device according to one of claims 7 to 11, wherein the main optics has a rectangular cross-section.

11. Optically wireless device according to one of claims 7 to 10, comprising a plurality of secondary optics arranged relative to the main optics such that with increasing distance from an optical center of the main optics, the secondary optics have a decreasing aperture size.

12. An optical wireless device according to any one of the preceding claims, comprising transmitting means (76) for transmitting optical wireless signals; wherein the transmitting means (76) comprises an emitter array, means for magnifying the apparent source, or means for generating one of multiple apparent sources of an optical emitter.

13. The optical wireless device according to claim 12, wherein the transmitting device (76) is configured as a device for magnifying the apparent source or for generating multiple apparent sources and comprises: an optical transmitter (36) for generating an optical signal (14); and separation optics configured to spatially divide the optical signal (14) into a plurality of optical sub-signals in order to distribute an optical power of the optical signal among the plurality of optical sub-signals having an associated spectral range, wherein the plurality of spectral ranges at least partially coincide.

14. Optically wireless device according to one of the preceding claims, wherein each optic of the plurality of optics (18I-184) is assigned a respective receiving field of view (54), and receiving fields of view (54) of the plurality of optics (18I-184) have a different size from one another.

15. Optical-wireless device according to one of the preceding claims, wherein each optic of the plurality of optics (I81-I84) has a respective receiving field of view (54) is assigned, and the reception fields of view (54) of the plurality of optics (181- I84) overlap at most incompletely.

16. Optically wireless device according to one of the preceding claims, wherein the plurality of optics (I81-I84) are monolithically fixed via a connecting structure (66) with respect to their relative position to one another.

17. Optical wireless device according to one of the preceding claims, wherein the receiving device (12) is designed to receive the optical wireless signal (14) of a transmitting optical wireless transmitter both in a geometric near field and in a geometric far field and to detect it with the receiving device (12) without saturation.

18. An optical wireless device comprising a receiving device (12) having an optical detector (16) and configured to receive an optical wireless signal (14) from an optical wireless transmitter; wherein the receiving device (12) is configured to receive the optical wireless signal (14) both in a geometric near field and in a geometric far field of the optical wireless transmitter and to detect it without saturation using the receiving device (12).

19. Optically wireless device according to claim 18, wherein the receiving device (12) comprises a first optical system (181) and a second optical system (182) of a plurality of optical systems (181-184) arranged side by side and substantially with the same preferred direction (22i, 222); wherein each of the plurality of optical systems (181-184) is designed to simultaneously direct light incident on the optical system onto the optical detector (16); wherein the optical detector (16) has an optical axis (26), and the first optical system (181) is arranged at a first distance from the optical axis (26), and the second optical system (182) is arranged at a greater second distance from the optical axis (26).

20. Optical wireless communication system with: a first optical wireless device (20) according to one of the preceding claims; and a second optical wireless device (25) which is configured to transmit the optical wireless signal (14); wherein, at different distances (64) between the first optical wireless device (20) and the second optical wireless device (25), a different number of optics of the receiving device (12) of the first optical wireless device (25) are illuminated with the transmitted optical wireless signal (14) and make a contribution to a total optical power directed onto the detector (16).

21. Optical wireless communication system according to claim 20, wherein the first optic (181) as a main optic of the plurality of optics (181-184) in a geometric far field of an optical transmitter (34) of the second optical wireless device (25) provides a dominant component to the total optical power at the optical detector (16) of the first optical wireless device; and the second optic (182) as a secondary optic of the plurality of optics (181-184) in a geometric near field of the transmitter (34) of the second optical wireless device (25) provides a dominant component to the total optical power at the optical detector (16).

22. Optical wireless communication system according to claim 20 or 21, wherein the second optical wireless device (25) is configured to transmit the optical wireless signal (14) along a main transmission axis (42); wherein a secondary optic of the plurality of optics (18i-184) is arranged at a smaller distance from the main transmission axis (42) than a main optic of the plurality of optics (181-184).

23. Optical wireless communication system according to one of claims 20 to 22, wherein an acceptance angle (52) of the plurality of optics (18I-184) of the first optical wireless device 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. Optical wireless communication system according to one of claims 20 to 23, wherein the plurality of optics (I81-I84) of the receiving device (12) of the first optical wireless device (20) on the one hand and a transmission power of the second optical wireless device (25) on the other hand are adapted to one another, and at any distance (64) between the first optical wireless device and the second optical wireless device, the receiving device (12) remains saturation-free.

25. Optical wireless communication system according to one of claims 20 to 24, which is arranged for a minimum distance between the first optical wireless device (20) and the second optical wireless device (25), and a minimum tolerance of the optical wireless communication system to positioning inaccuracies is determined by an aperture size of the transmitting optics, so that at the minimum distance the secondary optics of the first optical wireless device (20) are arranged opposite the transmitter.

26. Optical wireless communication system according to one of claims 20 to 25, wherein the plurality of optics (181-184) comprises the first optic (181) as a main optic and a plurality of secondary optics, wherein each of the plurality of secondary optics is configured for an optic-individual distance range to the second optical wireless device, which at most incompletely overlaps with a distance range of another secondary optic.

27. Optical wireless communication system according to one of claims 20 to 26, wherein an emission angle (46) of a transmitting device (34) of the second optical wireless device (25) is greater than a total acceptance angle of the plurality of optics (I81-I84) of the first optical wireless device.

28. A method (800) for designing an optical arrangement for a receiving device of an optical wireless device, comprising the following steps: Laying out and positioning (810) a plurality of optics with respect to a transmitting device configured to provide an optical wireless signal; such that the plurality of optics simultaneously directs a received optical wireless signal to an optical detector of the receiving device; such that, when different distances between the receiving device and the transmitting device, a different number of the plurality of optics contributes to a total optical power directed to an optical detector of the receiving device; and Producing (820) the plurality of optics in an arrangement according to the design and positioning.

29. The method according to claim 28, wherein the designing and positioning comprises taking into account at least one of: an aperture angle of the transmitting device; a transmission power of the transmitting device; a power distribution across the output aperture of the transmitting device; a relative distance of the plurality of optics from one another and from an optical axis of the transmitting device; an acceptance angle of the plurality of optics; the geometric shapes of the apertures of the plurality of optics; and a saturation limit of an optical detector of the receiving device.

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