An optical system with a tracking system

Abstract

A mechanism for tracking an approximate position of a desired light beam. An optical system is configured to derive one or more first positions of one or more incident light beams from data produced by a position-sensitive device and one or more second positions of one or more incident light beams from image data produced by an image sensing arrangement. A tracking system processes the first position(s) and the second position(s) to determine or identify a position of the desired light beam.

Description

[0001] 2024PF80432

[0002] 1

[0003] An optical system with a tracking system

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to the field of optical wireless communication, and in particular to optical systems for tracking a desired light beam of one or more light beam, such optical systems may be used in optical wireless communication.

[0006] BACKGROUND OF THE INVENTION

[0007] Wireless communications by means of modulated light is becoming increasingly used, and is commonly called optical wireless communication (OWC).

[0008] Optical wireless communication refers to techniques in which information is communicated in the form of a signal embedded in light emitted by a light source. In this context, light may include any visible or invisible light (such as infrared light). Depending upon the specific wavelengths and / or data-throughput rates used, such techniques may also be referred to as coded light, Light Fidelity (LiFi), visible light communication (VLC) or free-space optical communication (FSO).

[0009] An exemplary FSO communication system is presented in “Fiber bundlebased beam tracking demonstrated across 30 km terrestrial FSO communications link”, by Michelle O’Toole et al, Free-Space Laser Communications XXXVI, Proc, of SPIE Vol. 12877, 12 March 2024, the paper discloses that FSO communications systems require robust pointing, acquisition, and tracking approaches to close and maintain links due to inherent beam directionality and susceptibility to atmospheric effects. It employs a three-stage nested loop approach, involving (1) rough line bearing pointing, (2) beacon acquisition using a infrared camera having a 5 degree field of view and gimbal, and finally (3) fiber bundle sensing using a Fast-Steering Mirror. In the last stage, an in-line position sensor and data receiver is used employing a 7-fiber hexagonally packed fiber bundle.

[0010] Another examplary FSO communication system is presented in Chinese patent application CN 115941038 A, which discloses a ship-based wireless optical communication system which is characterized by being provided with a communication processing unit, an optical antenna unit and an aiming acquisition tracking PAT unit which are sequentially 2024PF80432

[0011] 2 connected. The aiming acquisition tracking PAT unit employing a CCD camera and coarse tracking QD.

[0012] Optical wireless communication can be performed with concentrated or collimated beams of light. In such approaches, the transceivers on both sides need to be properly aligned to allow communication in both directions.

[0013] There is therefore a desire to improve mechanisms for aligning a beam generated by one optical wireless communication device with its communication partner. In particular, there is a desire to facilitate this alignment even in the presence of multiple beams of light.

[0014] SUMMARY OF THE INVENTION

[0015] The invention is defined by the claims.

[0016] In accordance with a proposed approach, there is provided an optical system for tracking a desired light beam of one or more light beams, incident upon the optical system, generated by one or more external devices in a field of regard. The optical system includes: a position-sensitive device configured to receive a first portion of each light beam incident upon the optical system from the field of regard and generate a respective electronic signal for each of a plurality of photo-sensitive segments on the position-sensitive device, generate a respective electronic signal (215) responsive to the first portion of each light beam incident upon the optical system; a signal processing system configured to process these electronic signals produced by the position-sensitive device to determine as a set of one or more first positions, an estimated position of at least the desired light beam incident upon the optical system from the one or more external devices in the field of regard and iteratively update the set of one or more first positions at a first frequency; an image sensing arrangement configured to receive a second portion of each light beam incident upon the optical system and generate image data representing the field of regard and to iteratively update the image data; an image processing system configured to receive the image data representing the field of regard and process the received image data to determine, as a set of one or more second positions, an estimated position of each light beam incident upon the optical system from the field of regard and iteratively update the set of one or more second positions at a second frequency; and a tracking system configured to perform a tracking process comprising processing the set of one or more first positions and the set of one or more second positions to determine an approximate position of the desired light beam and to iteratively perform a plurality of iterations of the tracking process, wherein each iteration of the tracking process comprises processing the 2024PF80432

[0017] 3 iteratively updated set of one or more first positions and the iteratively updated set of one or more second positions to determine the approximate position of the desired light beam for the said iteration and wherein: the second frequency is less than the first frequency; and the tracking system, when operating in a first mode, is configured to, for each iteration of the tracking process: responsive to the set of one or more second positions being updated more recently than the set of one or more second positions, define or update the approximate position of the desired light beam for said iteration using the set of one or more second positions; and responsive to the set of one or more first positions being updated more recently than the set of one or more second positions, define or update the approximate position of the desired light beam for said iteration using only the set of one or more first positions.

[0018] The present disclosure proposes an optical system that is able to track an approximate position of a desired light beam by processing electronic signals produced by a position-sensitive device and image data produced by an image sensing arrangement. By combining position-sensitive device data with image data, more robust tracking of a desired light beam is achieved. In particular, by using two distinct sensing methods, the proposed optical system is able to at least partially overcome limitations of either method alone, enhancing accuracy and reliability in varying environmental conditions.

[0019] The iterative approach allows for real-time tracking of moving light beams. By continuously updating position estimates from both sensing methods, the optical system is able to adapt to dynamic changes in the field of regard, maintaining accurate tracking even for rapidly moving targets.

[0020] In the optical system, the second frequency is less than the first frequency and the tracking system, when operating in a first mode, is configured to, for each iteration of the tracking process: responsive to the set of one or more second positions being updated more recently than the set of one or more second positions, define or update the approximate position of the desired light beam for said iteration using the set of one or more second positions; and responsive to the set of one or more first positions being updated more recently than the set of one or more second positions, define or update the approximate position of the desired light beam for said iteration using only the set of one or more first positions.

[0021] This approach recognizes that image processing is a complex task, that may require significant processing resources (e.g. time) to perform and produce the second position(s). The proposed dual-frequency approach allows the system to leverage the strengths of both sensing methods. By prioritizing the most recently updated data, the system is able to 2024PF80432

[0022] 4 maintain high update rates (associated with the first frequency) while still benefiting from the complementary nature of the two sensing techniques.

[0023] In some embodiments, each light beam generated by the one or more external devices comprises a first component carrying an embedded identifier. In such examples, the signal processing system may be configured to filter each electronic component to identify a target component representing the first component carrying the embedded identifier of the desired light beam, and process only the target component to determine the approximate position of the desired light beam.

[0024] This approach allows for selective identification of a specific light beam among multiple incident beams. By focusing on the embedded identifier, the system can maintain lock on the desired beam even in the presence of potential interference or multiple light sources.

[0025] In some embodiments, the first component comprises a first set of one or more modulation frequencies of the light beam, or an encoded modulation pattern of the light beam defining the embedded identifier. Utilizing modulation frequencies or encoded patterns provides a robust method for beam identification. This technique enables the system to distinguish between multiple beams even when they originate from similar sources or have similar spatial characteristics.

[0026] In some embodiments, each iteration of the tracking process comprises processing an approximate position of the desired light beam from at least one previous iteration of the tracking process, the iteratively updated set of one or more first positions and the iteratively updated set of one or more second positions to determine the position of the desired light beam for said iteration. By incorporating historical data from previous iterations, the system can implement predictive tracking algorithms. This enables smoother tracking performance and can help bridge temporary gaps in sensor data, improving overall system robustness.

[0027] In some embodiments, the image processing system is configured to define, for each second position, an intensity of the light beam incident upon the optical system at the second position. In such examples, the tracking system is configured to determine an estimated position of the desired light beam responsive to the defined intensity for each second position. By incorporating intensity information from the image data, the system is able to apply one or more prioritization or filtering rules based on intensities, e.g., to prioritize stronger signals and potentially filter out noise or weaker interfering sources. This thereby improves the tracking system's ability to maintain or perform tracking in complex environments with multiple light sources. 2024PF80432

[0028] 5

[0029] In some embodiments, the signal processing system is configured to process the electronic signals to determine, as the set of one or more first positions, a single estimated position for each embedded identifier.

[0030] The tracking system, when operating in a second mode and responsive to the set of one or more first positions comprising only a single first position and the set of one or more second positions comprising a plurality of second positions, may be configured to: if the first position matches a single one of the second positions, determine the first position as the approximate position of the desired light beam; and if the first position does not match any of the second positions, identify the second position having the brightest defined intensity amongst a sub-set of second positions that are all connected by a hypothetical line passing through the first position.

[0031] This mode of operation provides a sophisticated method for resolving discrepancies between position-sensitive device data and image data. In particular, if there is a discrepancy between the first position and the second positions, this is indicative that there is an undesirable reflection of the desired light beam that creates a reflected light beam incident upon the optical system. Any such reflections are likely to he on a hypothetical line connecting the first position to second positions. The second position associated with the brightest intensity is more likely to represent the true position of the desired, non-reflected light beam (as reflections will typically be attenuated).

[0032] In some embodiments, the signal processing system is configured to process the electronic signals produced by the position-sensitive device to determine the position of each light beam incident upon the optical system from the one or more external devices in the field of regard. This capability enables the system to track multiple light beams simultaneously, e.g., rather than only the desired light beam. By processing data for all incident beams, the system is able to provide comprehensive situational awareness, support multi-target tracking applications and able to make a decision on which light beam is to function as a desired light beam if this has not been previously established or determined.

[0033] In some embodiments, the image processing system is configured to process the received image data using a machine-learning method to determine the set of one or more second positions. Use of a machine-learning algorithm provides a robust and reliable mechanism for determining the set of one or more second positions.

[0034] In some embodiments, the position sensitive device is a quadrant photodetector. Quadrant photodetector have proven to provide a simple yet effective method for estimating 2024PF80432

[0035] 6 beam position. In particular, this component offers fast response times and is able to provide accurate position information with minimal processing overhead.

[0036] In accordance with a proposed approach, there is provided a steering control system for controlling the operation of a steerable element configured to control the relative position at which each light beam is incident on the optical system. The steering control system includes the optical system as described above and a control system configured to control the operation of the steerable element responsive to the determined approximate position of the desired light beam.

[0037] This steering control system enables active tracking and alignment with the desired light beam. By integrating the optical tracking system with a steerable element, the system can maintain optimal positioning even when the source or receiver is in motion.

[0038] In accordance with a proposed approach, there is provided a steering system comprising the steering control system described above and the steerable element. The complete steering system provides an integrated solution for tracking and aligning with desired light beams.

[0039] In accordance with a further proposed approach, there is provided a mobile communication device comprising the steering system described above, a light sensing module configured to receive each light beam incident upon the optical system and generate a data signal responsive to any embedded information in each light beam incident upon the optical system, a processing system configured to perform one or more operations responsive to the data signal, and a transmitter system configured to generate one or more output light beams, carrying output data, for directing towards the external device generating the desired light beam. In such examples, the steerable element is configured to synchronously control the relative position at which each light beam is incident upon the light sensing module with the relative position at which each light beam is incident upon the optical system.

[0040] This mobile communication device represents a device for use in a free-space optical communication system. By integrating the tracking and steering capabilities with data reception and transmission functions, the device can establish and maintain robust optical links in dynamic environments, enabling high-bandwidth, secure communications.

[0041] There is provided a method for tracking a desired light beam of one or more light beams, incident upon the optical system, generated by one or more external devices in a field of regard. The method comprises receiving, at a position-sensitive device, a first portion of each light beam incident upon the optical system from the field of regard; generating, for each of a plurality of photo-sensitive segments on the position-sensitive device, a respective 2024PF80432

[0042] 7 electronic signal responsive to the first portion of each light beam incident upon the optical system; processing the electronic signals produced by the position-sensitive device to determine, as a set of one or more first positions, an estimated position of at least the desired light beam incident upon the optical system from the one or more external devices in the field of regard and iteratively update the set of one or more first positions at a first frequency; receiving, at an image sensing arrangement, a second portion of each light beam incident upon the optical system from the field of regard; generating image data representing the field of regard responsive to the received second portion of each light beam and to iteratively update the image data; processing the received image data to determine, as a set of one or more second positions, an estimated position of each light beam incident upon the optical system from the field of regard and iteratively update the set of one or more second positions at a second frequency; and performing a tracking process comprising processing the set of one or more first positions and the set of one or more second positions to determine a position of the desired light beam and to iteratively perform a plurality of iterations of the tracking process, wherein each iteration of the tracking process comprises processing the iteratively updated set of one or more first positions and the iteratively updated set of one or more second positions to determine the approximate position of the desired light beam for the said iteration and wherein: the second frequency is less than the first frequency; and the tracking process when operating in a first mode, is configured to, for each iteration of the tracking process: responsive to the set of one or more second positions being updated more recently than the set of one or more second positions, define or update the approximate position of the desired light beam for said iteration using the set of one or more second positions; and responsive to the set of one or more first positions being updated more recently than the set of one or more second positions, define or update the approximate position of the desired light beam for said iteration using only the set of one or more first positions.

[0043] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

[0044] BRIEF DESCRIPTION OF THE DRAWINGS

[0045] For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0046] Fig. 1 illustrates a system in which embodiments may be employed;

[0047] Fig. 2 illustrates a proposed optical system; 2024PF80432

[0048] 8

[0049] Fig. 3 illustrates a proposed tracking method;

[0050] Fig. 4 illustrates another proposed tracking method;

[0051] Fig. 5 illustrates another proposed tracking method;

[0052] Fig. 6 illustrates a proposed steering system;

[0053] Fig. 7 illustrates a proposed mobile communication device; and

[0054] Fig. 8 is a flowchart illustrating a proposed method.

[0055] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] The invention will be described with reference to the Figures.

[0057] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0058] The invention provides a mechanism for tracking an approximate position of a desired light beam. An optical system is configured to derive one or more first positions of one or more incident light beams from data produced by a position-sensitive device and one or more second positions of one or more incident light beams from image data produced by an image sensing arrangement. A tracking system processes the first position(s) and the second position(s) to determine or identify a position of the desired light beam.

[0059] Figure 1 conceptually illustrates a system 100 in which embodiments may be employed, for improved contextual understanding. The system comprises two or more devices

[0060] 10, 20, 30 that are configured to communicate with one another using an optical wireless communication technique, i.e., mobile communication devices.

[0061] Each device 10, 20, 30 is thereby configured to generate a respective light beam

[0062] 11, 21, 31 for communication with another device, e.g., using an optical transmission system. In this way, each device is a light source that generates a respective light beam.

[0063] In some examples, each device (i.e., light source) is configured to encode at least a portion of the generated light beam(s) using a different encoded modulation pattern, i.e., a predetermined code such as those used for code-division multiple access (CDMA) 2024PF80432

[0064] 9 communication technologies. This facilitates later discrimination or separation of different light beams incident upon a same light-sensitive component.

[0065] However, other approaches for facilitating the discrimination or separation of different light beams may also be employed, such as frequency-modulation based separation (where data for different light beams is modulated using different sets of one or more frequencies) or wavelength based separation (where different light beams have different sets of one or more frequencies). Other examples will be apparent to the skilled person.

[0066] Thus, each light beam generated by the devices may comprise a first component carrying an embedded identifier, e.g., in the form of an encoded modulation pattern, set of one or more modulation frequencies, set of one or more frequencies and so on.

[0067] Each light beam may also comprise a second component (a communication component) carrying embedded information, for communication to another device, i.e., data to be transmitted to the other device. The second component may be encoded using any suitable modulation scheme.

[0068] Although preferred, it is not essential that a light beam carry the second component, e.g., if the intention of the system 100 is merely to facilitate tracking of the position of different devices (rather than inter-device communication).

[0069] Each device 10, 20, 30 is also configured to receive one or more light beams 11, 21, 31, e.g., at an optical device. In particular, each device 10, 20, 30 monitors afield of regard 15 (of which only one is illustrated for clarity) from which incoming light beams are received by the optical system of the device. Light beams originating from outside of this field of regard 15 may not be received by the optical system.

[0070] Each device is configured to process any received light beam(s) to extract or derive embedded information therefrom. Each device performs this process using an optical system, e.g., configured to generate one or more electronic signals responsive to incoming light beams, which can then be digitally processed by a microprocessor or other processing system to extract or derive information therefrom.

[0071] It will be appreciated that any modulation of the incoming light beam(s) is reflected in corresponding modulation of the electronic signal(s). For instance, amplitude modulation of the light beam may result in corresponding variations in the amplitude or intensity of the electronic signals. Similarly, frequency modulation may result in corresponding frequency modulation in the electronic signal(s).

[0072] Of course, the fidelity with which the modulation is reflected in the electronic signal(s) may depend on factors such as the sensitivity and bandwidth of any photodetectors, 2024PF80432

[0073] 10 the quality of the optical components, and any signal conditioning or amplification applied to the electronic signals. In some implementations, additional signal processing techniques may be applied to enhance the representation of the modulation in the electronic signal(s), leading to improved extraction of embedded information.

[0074] The present disclosure provides a mechanism for performing beam tracking. In particular, there is proposed an optical system for tracking a desired light beam using information from two separated light-sensitive components or chiplets. The optical system may be formed on a shared interposer, e.g., in a single package, to a chip or chip package that comprises the optical system.

[0075] In the context of the present disclosure, the position of a light beam may be defined by the central axis of the light beam. This central axis typically represents the path along which the light beam propagates and is thereby usable as a reference point for tracking or aligning optical systems. Light beams will typically have a Gaussian intensity profile, where the intensity is highest at the center and decreases towards the edges. As such, the peak intensity point (coinciding with the center of the beam) serves as a practical reference for defining the beam's position.

[0076] In the context of the present disclosure, a desired light beam is a light beam from a desired external device (e.g., of the system 100). This facilitates tracking of a light beam from a desired external device, e.g., for facilitating or maintaining a communication link with the desired external device.

[0077] Figures 2 illustrates a proposed optical system 200.

[0078] The optical system 200 is designed for tracking a desired light beam of one or more light beams, incident upon the optical system. The one or more light beams are generated by one or more external devices in a field of regard, as previously explained.

[0079] The skilled person will appreciate that the various components of the optical system 200 may be mounted on a same shared interposer or substrate, or may be stacked in any suitable arrangement or alignment.

[0080] The optical system comprises a position-sensitive device 210 configured to receive a first portion 291 of each light beam 290 incident upon the optical system from the field of regard.

[0081] The position-sensitive device comprises a plurality of photosensitive segments. Each photosensitive segment is configured to generate a respective electronic signal responsive to the first portion of each light beam incident upon the optical system, thereby producing a plurality of electronic signals 215. It will be appreciated that an intensity of each electronic 2024PF80432

[0082] 11 signal will be dependent upon the intensity of the first portion of each light beam that is incident upon the relevant photosensitive segment.

[0083] A suitable example of a position-sensitive device 210 is a quadrant photodetector (QPD). A QPD typically comprises four separate photodiodes arranged in a 2x2 grid. When light is incident on the QPD, each quadrant generates an electronic signal proportional to the intensity of light falling on that quadrant. By comparing the relative strengths of these signals, the position of the incident light beam on the QPD can be precisely determined.

[0084] In another example, the position-sensitive device may be an array of photodiodes. The array may comprise a two-dimensional grid of individual photodiodes, each capable of generating an electronic signal in response to incident light. For instance, the array may include a 3x3 grid or 4x4 grid of photodiodes. When light is incident on the array, each photodiode generates an electronic signal proportional to the intensity of light falling on its active area. By analyzing the pattern of signals across the entire array, it is possible to determine the relative position of any incident light beam.

[0085] The optical system 200 also comprises a signal processing system 220 configured to process the electronic signals 215 produced by the position-sensitive device to determine, as a set of one or more first positions, an estimated position of at least the desired light beam incident upon the optical system from the one or more external devices in the field of regard.

[0086] The set of one or more first positions may comprise at least a first position for the desired light beam and, optionally (as exemplified below) a first position for each other light beam incident upon the optical system 200 (if present).

[0087] Approaches for processing electronic signals produced by a position-sensitive device to determine a position of one or more light beams are well established in the art.

[0088] As a simple example, where there is only a single incoming light beam incident upon the position-sensitive device, then the amplitude of each electronic signal may be directly processed to derive or determine an estimated position of the incoming light beam (which functions as a first position). This may, for instance, make use of a centroid calculation method in which the weighted average of the intensity of each electronic signal from the photosensitive segments is processed to determine the beams position. More detail on the operation of an exemplary position-sensitive device can be found in, inter aha, Shen, C. B., et al. "Research of signal-processing methods in four-quadrant photodetector." 2008 International Conference on Electrical Machines and Systems. IEEE, 2008. 2024PF80432

[0089] 12

[0090] One scenario in which there may only be a single incoming light beam upon the position-sensitive device may occur when there is a wavelength-selective component (e.g., a Bragg grating) that directs light of a limited set of wavelengths to the position-sensitive device and different light beams are associated with different wavelengths.

[0091] In a more complex example, when there are (or there is the potential for there to be) multiple incoming light beams from multiple different light sources incident upon the position-sensitive device, then the signal processing system may be configured to process the electronic signals to determine, as the set of one or more first positions, a single estimated position for each embedded identifier. In this way, a single estimated position is produced for each light source that produces a light beam incident upon the optical system.

[0092] In such an approach, each electronic signal may need to be separately pre- processed to separate components representing lights beams from different light sources (i.e., components representing different embedded identifiers) from one another. The separate components may then be processed to determine, as the set of one or more first positions, a single estimated position for each embedded identifier (i.e., each light source producing a beam incident upon the optical system).

[0093] In a first scenario, each (incoming) light beam is encoded with a particular encoded modulation pattern by its light source (e.g., where different light sources have different codes). In other words, each light beam may carry an embedded identifier in the form of an encoded modulation pattern. In this scenario, each electronic signal may be processed to separate different signal components of said electronic signal, where each signal component represents the first component of the electronic signal encoded with a particular encoded modulation pattern. For instance, the signal processing system may apply appropriate signal processing techniques, such as correlation or matched filtering, to extract the components corresponding to each unique encoded modulation pattern (i.e., each embedded identifier). This process effectively separates each combined signal into distinct components, representing the contribution from the light beam(s) of each light source.

[0094] Once the signal components are separated, they may be grouped into one or more sets based on their shared encoding. Each set corresponds to a different light source and contains the signal components (from the different segments of the position-sensitive device) that were encoded with that light source’s unique encoded modulation pattern. In this way, the electronic signals are processed to produce one or more sets of signal components, each set representing a different light source and having a same shared encoding. Each set of separated signal components can then be individually processed to determine the estimated position of 2024PF80432

[0095] 13 the light beam from the corresponding light source, i.e., associated with the same embedded identifier. This individual processing may be performed using the centroid calculation method previously described.

[0096] In a second scenario, each light source may modulate its emitted light beam at a different frequency. In other words, each light beam may carry an embedded identifier in the form of a particular modulation frequency. Here, frequency domain analysis techniques, such as Fourier transforms, can be applied to each electronic signal to separate the components corresponding to different modulation frequencies. Once the components of all electronic signals are separated, they may be grouped into one or more sets based on their shared frequency. Each set corresponds to a different light source and contains the signal components from the electronic signals that correspond to a same shared frequency, i.e., a same embedded identifier.

[0097] In this way, the electronic signals are processed to produce one or more sets of signal components, each set representing a different light source and having a same shared frequency (i.e., embedded identifier). Each set of separated signal components can then be individually processed to determine the estimated position of a light beam from the corresponding light source, i.e., associated with the same embedded identifier. This individual processing may be performed using the centroid calculation method previously described.

[0098] It will be appreciated that the electronic signals produced by the positionsensitive device also indicate the number of light sources that produce a light beam that is incident upon the position-sensitive device. In particular, the number of sets of signal components determined by the signal processing system indicates the number of separable light sources that produce a respective light beam that is incident upon the position-sensitive device. The number of such light sources may be employed during later processing, as exemplified below.

[0099] The optical system 200 further comprises an image sensing arrangement 230 configured to receive a second portion 292 of each light beam 290 incident upon the optical system from the field of regard and generate image data 235 representing the field of regard. Thus, the image data contains a digital representation of the field of regard, e.g., effectively a projection of the field of regard upon the image sensing arrangement.

[0100] A suitable example of an image sensing arrangement is a camera or image sensor, such as a CCD image sensor or CMOS sensor. Other examples would be readily apparent to the skilled person. As compared to the position-sensitive device 210, the image sensing device may use an image sensor array that is read-out as a rolling-shutter or global- 2024PF80432

[0101] 14 shutter approach and thus outputs samples for all respective image elements or pixels in frames- at a much lower rate, generally below 200 frames per second.

[0102] Thus, the position-sensitive device may be configured to update the electronic signals at a higher frequency than the frequency at which the image sensing arrangement is able to update the image data, e.g., a frequency no less than lOx greater.

[0103] The optical system 200 further comprises an image processing system 240 configured to receive the image data 235 representing the field of regard. The image processing system is also configured to process the received image data to determine, as a set of one or more second positions, an estimated position of each light beam incident upon the optical system from the field of regard.

[0104] By way of brief explanation, in some examples the image processing system is configured to process the received image data using an image segmentation or object detection technique to identify one or more objects (each representing a light beam) in the image data. Each position of the object(s) in the image data is used to derive each second position.

[0105] A more detailed explanation of this and other example approaches that may be employed by the image processing system 240 to produce the set of one or more second positions are provided later in this disclosure.

[0106] The signal processing system 220 and the image processing system 240 are preferably formed from separate and distinct processing devices, e.g., separate microcontrollers or the like. In other examples, the processing systems are formed from a single, shared processor.

[0107] In the optical system, the first and second positions are defined in a same shared coordinate space to facilitate accurate tracking of the desired light beam. This shared coordinate space may be established relative to a common reference point or plane within the optical system.

[0108] In some examples, the shared coordinate space may be a relative coordinate space, such as an error coordinate space. In this approach, the positions of light beams may be defined relative to a reference point or desired position, rather than in absolute coordinates. For example, the error coordinate space may define the position of each light beam as an offset or deviation from a target position. This target position could be the center of the positionsensitive device, a predefined optimal position on the image sensing arrangement, or any other reference point within the optical system. 2024PF80432

[0109] 15

[0110] By way of example only, in a relative coordinate space, a position at (0,0) may indicate perfect alignment of the (first / second) position of the light beam with the target position, while non-zero coordinates represent the magnitude and direction of misalignment.

[0111] In some examples, the position-sensitive device and the image sensing arrangement may be calibrated to align their respective coordinate systems. This calibration process may involve using known reference points or patterns to map the coordinates of the position-sensitive device to those of the image sensing arrangement. Accordingly, the signal processing system and / or image processing system may be configured to apply appropriate coordinate transformations to convert the raw determined position(s) from their respective sensing components into the shared coordinate space. These transformations may account for factors such as the physical placement and orientation of the sensing components within the optical system.

[0112] By defining the first and second positions in a same shared coordinate space, it is possible to directly compare and combine the positions from both sensing components.

[0113] The optical system 200 also comprises a tracking system 250 configured to perform a tracking process. The tracking process comprises processing the set of one or more first positions and the set of one or more second positions to determine an approximate position of the desired light beam.

[0114] In this way, the tracking system 250 is able to approximate a position of the desired light beam using the first position(s) and the second position(s). Thus, the tracking position is able to make a decision as the approximate position of the desired light beam using the first position(s) and the second position(s).

[0115] The optical system 200 may further comprise one or more beam directing components 260 configured to direct a respective portion 291, 292, of any incoming light beam 290 to the optical system to the position-sensitive device 210 and the image sensing arrangement 230.

[0116] For instance, the beam directing component(s) may be configured to split the incoming light beam(s) into two portions, which are respectively directed (e.g., via mirrors or other guiding elements) to the position-sensitive device and the image sensing arrangement. The beam directing components may thereby comprise one or more beam splitters, partially reflective mirrors, or other optical elements that can divide the incoming light beam into multiple paths. 2024PF80432

[0117] 16

[0118] The skilled person would readily understand a wide variety of tracking processes that may be employed for processing the first and second position(s) to approximate the position of the desired light beam.

[0119] A number of example tracking processes that may be performed by the tracking system 250 are hereafter described for the sake of completeness. These strategies are designed to handle various situations, from simple single-beam scenarios to more complex multi-beam environments with potential interference.

[0120] Figure 3 illustrates an example tracking process 300 for approximating the position of the desired light beam in a first scenario, in which there is only one light beam incident upon the optical system. This single light beam functions as the desired light beam.

[0121] The tracking process 300 is iteratively performed by the tracking system and may be performed by the tracking system when operating in the first mode.

[0122] In this scenario, the tracking system is configured to use the most recently available first and / or second position to update the approximated position of the desired light beam. This approach ensures that the tracking system maintains an up-to-date estimate of the beam's location.

[0123] The tracking process 300 begins with step 310, comprising checking whether or not a new second position (2ndPos) is available from the image processing system. If a new second position is available, the tracking process moves to step 315, which comprises setting the approximated position using the second position.

[0124] In one example, step 315 comprises setting the approximated position to be equal to the second position. This step prioritizes the use of the image-based data, which has been identified as providing a more reliable indicator of the position of a light beam.

[0125] In another example, step 315 may comprise predicting the future position of the light beam using one or more past second positions, and setting the approximated position responsive to the predicted future position. For instance, one or more past second positions of the light beam may be processed to predict a trajectory of the position of the light beam. This trajectory may be used to predict a future position of the light beam, which can define the approximated position of the light beam.

[0126] Another example for performing step 315 is later described.

[0127] If no new second position is available, the tracking process 300 proceeds to a step 320 of checking whether or not a new first position (1stPos) is available from the positionsensitive device. If no new first position is available, the tracking process 300 may restart (e.g., keeping the approximated position the same). 2024PF80432

[0128] 17

[0129] If a new first position is determined to be available in step 320, the process continues to a step 330 of determining whether or not there has been a change in the first position (i.e., from a previous iteration). If there is no change in the first position, the tracking process 300 may restart (e.g., keeping the approximated position the same).

[0130] However, a change in the first position indicates a movement of the light beam, prompting the system to modify the approximated position in step 340. Thus, if there is a change in the first position, step 340 is performed which comprises adjusting the approximated position based on the change detected in the first position.

[0131] The adjustment performed in step 340 may comprise modifying the approximated position based on the magnitude and direction of the change observed in the first position. In particular, the adjustment to the approximated position may mirror or match the change in magnitude and direction of the change observed for the first position. For example, if the first position shows a shift of 2 units in the one direction and 1 unit in the another, orthogonal direction on the position-sensitive device, the tracking system would apply a corresponding adjustment to the approximated position.

[0132] In some examples, step 340 may comprise predicting the future position of the light beam using one or more past first positions, and setting the approximated position responsive to the predicted future position. For instance, one or more past first positions of the light beam may be processed to predict a trajectory of the position of the light beam. This trajectory may be used to predict a future position of the light beam, which can define the approximated position of the light beam.

[0133] In some variants, step 330 is omitted, and step 340 is performed immediately following a positive determination in step 320, i.e., responsive to a new first position being determined in step 320.

[0134] The approach proposed by the tracking process 300 effectively functions to calibrate the approximated position to the second position when available, while using the more frequently updated first positions to make interim adjustments. This strategy recognizes the inherent differences in processing complexity and update frequency between the image processing system and the position-sensitive device.

[0135] More particularly, image processing is a highly complex task, requires significant processing time that limits the speed at which the second position(s) can be updated. However, the first position, derived from the position-sensitive device, involves a lower complexity task and can be updated more frequently. By prioritizing the use of second positions 2024PF80432

[0136] 18 derived from the image processing system when available, and using the first positions for interim updates, the tracking system maintains a balance between accuracy and responsiveness.

[0137] Thus, the tracking process 300 provides a mechanism which is particularly useful when the signal processing system is configured to iteratively update the set of one or more first positions at a first frequency and the image processing system is configured to iteratively update the set of one or more second positions at a second frequency, wherein the first frequency is greater than the second frequency.

[0138] Figure 4 illustrates another example tracking process 400 for approximating the position of the desired light beam in a second scenario, in which there may be more than one light beam incident upon the optical system. The tracking process 400 may be performed by the tracking system when operating in a second mode.

[0139] The process 400 generally operates under the assumption that only one first position is determined by the signal processing system. This single first position may result from either an inherent output of the position-sensitive device (i.e., only one light beam is received), or through digital filtering techniques that identify the position of a specific desired light beam among multiple incident beams. As previously explained, such filtering might involve identifying a light beam with a particular modulation or encoding characteristic.

[0140] That being said, in some examples, the tracking process 400 begins with an optional initialization step 405, which involves selecting a first position. This step may be employed to identify the first position associated with the desired light beam, typically based on its unique encoding. However, if the system inherently detects only a single first position, this step can be omitted.

[0141] The process 400 comprises a step 410 of determining whether more than one second position has been identified by the image processing system.

[0142] If only one second position is detected in step 410, the process moves to step 420. In step 420, either the first position, the second position, or a combination of both is used to define the approximated position of the desired light beam. For instance, the first position may be selected as the approximated position. As another example, the second position may be selected as the approximated position. Preference is given to using the second position due to its generally higher reliability, e.g., as it is derived from image data which typically provides more comprehensive spatial information. In another example, a weighted position may be determined, such as a point between the first and second positions - e.g., a midway point or a point at some other location between the first and second positions. 2024PF80432

[0143] 19

[0144] If multiple second positions are detected in step 410, the process 400 may advance to step 430 of determining whether or not the first position falls within a predetermined error margin (EM) of any of the second positions. This error margin accounts for any slight discrepancies between the position-sensitive device and image sensing arrangement measurements.

[0145] If the first position is determined, in step 430, to not align closely with any second position, process 400 moves to step 440, which is designed to handle situations where reflections or other optical phenomena may be causing false beam detections in the image data.

[0146] In this variant, step 440 comprises a substep 441 of identifying a set of two or more second positions that can be connected by a hypothetical line passing through the first position. This approach assumes that the reflection(s) of the light beam emitted by a single light source will cause the first position to he on this hypothetical line, i.e., the reflection will cause the first position to be biased away from the true position in the direction of the reflection(s).

[0147] Step 440 may then comprise performing a substep 442 of defining the approximated position using the brightest second position from the set identified in substep 441. The brightness is used as a proxy for the most likely true beam position, as reflections typically have lower intensity than the original beam. As used herein, the term "brightest second position" refers to the second that corresponds to the highest intensity or luminance value detected in the image data. This position may represent the location of the light beam with the strongest signal or greatest apparent brightness as captured by the image sensing arrangement.

[0148] In some examples, the brightest second position may be selected as the approximated position.

[0149] In some variations, performable when the process 400 is iteratively repeated, substep 442 may comprise predicting the future position of the light beam using one or more past brightest second positions, and setting the approximated position to the predicted future position. For instance, one or more past brightest second positions of the light beam may be processed to predict a trajectory of the position of the light beam. This trajectory may be used to predict a future position of the light beam, which can define the approximated position of the light beam.

[0150] In another example, substep 442 comprises determining a weighted position, such as a point between the first position and the brightest second position - e.g., a midway 2024PF80432

[0151] 20 point or a point at some other location between the first position and the brightest second position.

[0152] In some variations, substep 442 comprises setting the weighted position is set as the approximate position.

[0153] In other variations, performable when the process 400 is iteratively repeated, substep 442 may comprise predicting the future position of the light beam using one or more past weighted positions, and setting the approximated position to the predicted future position. For instance, one or more past weighted positions of the light beam may be processed to predict a trajectory of the position of the light beam. This trajectory may be used to predict a future position of the light beam, which can define the approximated position of the light beam.

[0154] If the first position is determined, in step 430, to align closely with a second position, the process proceeds to step 450. In step 450, the approximated position is defined using either the first position, the matching second position, or a combination of both. This may be performed any approach described in the context of step 420.

[0155] In some variations, performable when the process 400 is iteratively repeated, step 450 may comprise predicting the future position of the light beam using one or more past first positions, and setting the approximated position to the predicted future position. For instance, one or more past first positions of the light beam may be processed to predict a trajectory of the position of the light beam. This trajectory may be used to predict a future position of the light beam, which can define the approximated position of the light beam.

[0156] As another example, the (closely aligned) second position may be selected as the approximated position. Preference is given to using the (closely aligned) second position due to its generally higher reliability.

[0157] In some variations, performable when the process 400 is iteratively repeated, step 450 may comprise predicting the future position of the light beam using one or more past second positions, and setting the approximated position to the predicted future position. For instance, one or more past second positions of the light beam may be processed to predict a trajectory of the position of the light beam. This trajectory may be used to predict a future position of the light beam, which can define the approximated position of the light beam.

[0158] In another example, step 450 comprises determining a weighted position, such as a point between the first and (closely aligned) second positions - e.g., a midway point or a point at some other location between the first and (closely aligned) second positions.

[0159] In some variations, step 450 comprises setting the weighted position is set as the approximate position. 2024PF80432

[0160] 21

[0161] In other variations, performable when the process 400 is iteratively repeated, step 450 may comprise predicting the future position of the light beam using one or more past weighted positions, and setting the approximated position to the predicted future position. For instance, one or more past weighted positions of the light beam may be processed to predict a trajectory of the position of the light beam. This trajectory may be used to predict a future position of the light beam, which can define the approximated position of the light beam.

[0162] Step 450 functions to functions to correct for any non-data carrying light source(s), whilst also functioning to ignore any non-desired light beams that are represented in the image data. In particular, step 450 allows for selection of the second position that represents the desired light beam.

[0163] The tracking processes 300 (Figure 3) and 400 (Figure 4) may be combined in some approaches. In particular, the tracking process 300 may be adapted such that step 315 instead comprises performing the tracking process 400. In this combined approach, the tracking process 300, which is designed for scenarios with a single light beam, is modified to incorporate the more complex tracking process 400, which can handle multiple light beams.

[0164] In this combined approach, step 405 (if performed) may instead be performed before step 310.

[0165] Figure 5 illustrates another example tracking process 500 for approximating the position of the desired light beam, which may be performed by the tracking system when operating in a third mode.

[0166] The tracking process 500 is designed for selecting one of the light beam(s) incident upon the optical system as the desired light beam. In particular, the tracking process 500 is designed to use a property of the light beam(s), from one or more light sources, represented in the electronic signals and the image data to select a light beam to function as the desired light beam.

[0167] Thus, the tracking process 500 may be performed before a desired light beam has been identified and / or when the position of a desired light beam has been lost.

[0168] The tracking process 500 is performed when the first position(s) and the second position(s) are available. In this context, the first position(s) may comprise a plurality of first positions, indicating a plurality of light sources generating a light beam that is incident upon the optical system.

[0169] To select the most appropriate light beam as the desired beam, the tracking process 500 may determine or receive 510 one or more properties associated with each of the first positions and / or the second positions. 2024PF80432

[0170] 22

[0171] Example properties are provided below.

[0172] In some examples, each first position is associated with a signal strength, indicating the (average) intensity or signal strength of the component(s) of the electronic signal from which the first position was derived. This property indicates the ease with which a communication link can be established with the light source. A stronger signal generally suggests a more reliable connection. The signal strength for each first position may be generated by the signal processing system (in communication with the position-sensitive device).

[0173] In some examples, each second position is associated with a measure of movement or motion blur. In particular, where an image segmentation or object detection process is used in determining any second positions, then each detected object may be processed (e.g., by the tracking system or by the image processing system) to measure a motion blur. This may be performed by processing each detected object to analyze the shape, intensity distribution, or edge characteristics of the object in the image data. Objects with significant motion blur may appear elongated or have blurred edges compared to stationary objects. The degree of motion blur associated with each second position may thereby be quantified. The measure of motion blur for each second position may be generated by the image processing system.

[0174] In some examples, each second position is associated with an intensity or brightness, indicating the intensity or brightness of the representation of the corresponding light beam (having the second position) in the image data. The brightness of a light beam in the captured image data may function as a proxy for a measure of proximity of its source. Brighter spots in the image may indicate closer light sources, which could be preferable for establishing a stable connection. The image processing system may generate a measure of intensity or brightness for each second position.

[0175] Thus, the image processing system may be configured to define, for each second position, an intensity of the light beam incident upon the optical system at the second position. In such examples, the tracking system may be configured to determine an approximate position of the desired light beam responsive to the defined intensity for each second position.

[0176] In some examples, each second position is associated with a size, indicating the size of the representation of the corresponding light beam (having the second position) in the image data. Assuming that all emitters have the same emitter footprint, the apparent size of a light beam in the image data is also an indicator of proximity, in which larger spots are more likely to represent closer light sources, which might be more suitable for reliable 2024PF80432

[0177] 23 communication. The image processing system may determine a measure of size for each second position, e.g., a measure of size of the representation of the light beam associated with each second position.

[0178] The tracking process 500 comprise processing 520 the one or more properties (determined in step 510) and / or the first position(s) and / or the second positions to select an approximate position of the desired light beam. In particular, one or more of the light beams represented in the electronic signals and / or image data may be selected, with a position corresponding to that light beam being identified as the position of the desired light beam.

[0179] The precise selection criteria for selecting a light beam may be dependent upon one or more settings or rules, which can be predefined, user-configurable and / or dependent upon a policy (which can be optionally updated).

[0180] In some examples, e.g., usable where a position of the desired light beam has been lost, step 520 may comprise identifying a first and / or second position closest to a last known approximate position of the desired light beam. Thus, the tracking system may store an approximate position of a desired light beam and, if another tracking process fails to identify or update the approximate position, perform tracking process 500 to identify the first / second position closest to the last known approximate position.

[0181] In another example (e.g., usable when no desired light beam has yet been identified) step 520 may prioritize stable light sources (e.g., those with low motion blur) that are sufficiently close to establish a communication link (e.g., having sufficient signal strength or proximity, e.g., as indicated by having a sufficient size and / or intensity). For instance, a threshold-based approach may be used in which a motion blur threshold is set to identify light sources with acceptably low motion, while a signal strength threshold or size / intensity threshold is used to identify light sources that are close enough for reliable communication. Light sources meeting these thresholds may be given higher priority in the selection process. The specific threshold values may be adjustable based on system requirements and environmental conditions.

[0182] Other suitable examples will be readily apparent to the skilled person.

[0183] Once a light beam is selected as the desired beam, its approximate position can be tracked using any previously disclosed tracking process.

[0184] Figure 6 illustrates a proposed steering system 600 comprising a proposed steering control system 610 and a steerable element 620.

[0185] The steering control system is designed for controlling the operation of the steerable element 620. More particularly, the steering control system 610 comprises any 2024PF80432

[0186] 24 previously disclosed optical system 200 and a control system 615 configured to control the operation of the steerable element responsive to the determined approximate position of the desired light beam.

[0187] The steerable element 620 is configured to control the relative position at which each light beam is incident on the optical system. The steerable element 620 may include one or more adjustable optical elements, such as mirrors, prisms, or lenses, that can be manipulated to redirect any incoming light beam. In some examples the steering element may comprise a pan-tilt actuator (or similar mechanical system) for manipulating the direction in which at least the optical system (particularly, the position-sensitive device and the image sensing arrangement of the optical system) faces, to thereby control the relative position at which any light beam is incident on the optical system.

[0188] The steering control system 620 may operate in a closed-loop manner, iteratively or continuously adjusting its configuration based on the approximated position of the desired light beam produced by the tracking system. For example, if the tracking system detects that an approximate position of the light beam is not at a desired position (e.g., aligns with a predetermined central position), the steering system may make fine adjustments to realign the incident beam(s). This dynamic steering capability allows the optical system to maintain optimal alignment even in the presence of environmental disturbances or relative motion between communicating devices.

[0189] Figure 7 illustrates a proposed mobile communication device 700. The mobile communication device comprises the steering system 600, a (optional) light sensing module 710, a processing system 720 and a transmitter system 730.

[0190] The light sensing module 710 is separate to the position-sensitive device and is configured to receive a second portion of the incoming light beam(s).

[0191] The second portion of each light beam carries embedded information, and the lighting sensing module 710 may be configured to generate a data signal responsive to the embedded information in the second portion of each light beam incident upon the optical system. The data signal may include decoded information extracted from the light beam. This decoded information may represent data such as text, images, audio, or any other form of digital content transmittable via light beam communication technology.

[0192] The light sensing module 710 may include one or more photodetectors that convert light incident thereon into a data signal 715. The photodetector(s) may comprise one or more photodiodes, phototransistors, or other photosensitive elements capable of converting light intensity into electrical current or voltage. It will be appreciated that any modulation of 2024PF80432

[0193] 25 the second component of the incoming light beam(s) is reflected in corresponding modulation of the data signal. For instance, (amplitude) modulation of the light beam may result in corresponding variations in the amplitude or intensity of the data signal.

[0194] The data signal 715 may then be provided to the processing system 720.

[0195] The processing system 720 is configured to perform one or more operations responsive to the data signal 715. In particular, the processing system may be configured to digitize the intermediate electrical signal e.g., using an analogue-to-digital converter (ADC). The digitized signal may then be demodulated to extract the embedded information. Of course, the specific demodulation technique used may depend on the modulation scheme employed in the optical wireless communication system. The processing system 720 may then process the extracted / embedded information to perform one or more operations (e.g., control tasks or monitoring tasks).

[0196] In some variations, the dedicated light sensing module 710 may be omitted and position-sensitive device may function as the light sensing module. Thus, the electronic signal(s) produced by the position sensitive device may further be responsive to the embedded information, e.g., such that the embedded information is extractable or derivable from the electronic signal(s).

[0197] When the optical system comprises a light sensing module, the steerable element 620 is configured to synchronously control the relative position at which each light beam is incident upon the light sensing module 710 with the relative position at which the light beam 290 is incident upon the optical system. Thus, a movement of the position of incidence between the light beam and the optical system may be matched (i.e., proportional or exactly proportional to) the position of incidence between the light beam and the light sensing module 710.

[0198] The steering control system may be designed to align the light beam upon a desired position of the light sensing module, e.g., to improve or maximize a signal strength of the light beam. This may define the desired position for the light beam on the optical system (against which the approximated position produced by the tracking system is compared). The desired position may therefore correspond to a region of maximum sensitivity or optimal focus. This position may be predetermined based on the design of the light sensing module, or it may be dynamically determined during operation.

[0199] The transmitter system 730 is configured to generate one or more output light beams, carrying output data, for directing towards the external device generating the desired light beam. 2024PF80432

[0200] 26

[0201] In order to generate the output light beam(s), the transmitter system comprises a light source, such as a laser diode or light-emitting diode (LED), capable of emitting light at one or more wavelengths. The transmitter system may also include appropriate modulation circuitry for encoding information onto the light beam.

[0202] In this way, the transmitter system may generate a light beam with (e.g., at least) the first component and optionally the second component.

[0203] The first component carries an embedded identifier. This component may be modulated using a unique code or sequence, such as a CDMA code, to provide a distinct signature for the light beam. The embedded identifier allows the receiving optical system to distinguish this light beam from others, as previously explained.

[0204] The second component carries embedded information. This second component may contain the actual data to be transmitted, modulated using any suitable scheme such as orthogonal frequency-division multiplexing (OFDM), amplitude-shift keying (e.g., on-off keying (OOK)), pulse-position modulation (PPM), or quadrature amplitude modulation (QAM).

[0205] The transmitter system may employ different modulation techniques or frequency bands for each component. For example, the first sub-component carrying the embedded identifier may have a different peak wavelength to the second sub-component. Similarly, the second component with embedded information may have a different peak wavelength to the first sub-component or the second sub-component.

[0206] It will be appreciated that, to support the multi-component structure of the light beam, the transmitter system may comprise multiple signal generators and modulators, each responsible for producing a specific component of the beam. These individual components may then be combined using optical combining techniques before being emitted as a single coherent light beam.

[0207] In some examples, the transmitter system comprises a beam steering mechanism to adjust the direction of the transmitted light beam, e.g., based on feedback from the receiving device.

[0208] The beam steering mechanism may comprise one or more adjustable optical elements, such as mirrors, prisms, or lenses. These elements may be controlled by actuators or other positioning mechanisms to alter the path of the transmitted light beam. The beam steering module may work in conjunction with a control system that processes feedback information from the receiving external device (i.e., the external device that receives the transmitted light beam) to determine optimal beam alignment. 2024PF80432

[0209] 27

[0210] The feedback from the receiving external device may, for instance, be embedded within a return signal from the receiving external device, e.g., in the form of a light beam generated by the receiving external device. This feedback may include information about the received signal strength, signal quality, or specific alignment parameters derived from the position-sensitive device in the receiving system. For instance, a receiving external device (also comprising a proposed optical system) may be configured to provide a feedback signal (e.g., light beam) containing the approximate position corresponding to the transmitted light beam provided by the transmitter system.

[0211] It will be appreciated that the transmitter system may employ a closed-loop control algorithm to continuously adjust the beam direction. This control algorithm may, for instance, analyze the feedback signal and make one or more incremental adjustments to the beam steering mechanism to improve the link quality, e.g., to bring the transmitted light beam into closer alignment with a desired position on an optical system of the receiving external device. The control system may use techniques such as gradient descent or other optimization methods to converge on the beam alignment.

[0212] The transmitter system may therefore be designed to work in conjunction with the previously described optical system, enabling efficient and reliable optical wireless communication with enhanced tracking and alignment capabilities.

[0213] In some examples, the transmitter system may be configured to provide, e.g., as part of the embedded information, the approximate position corresponding to the light beam received from the external device with which the mobile communication device is in communication.

[0214] In some examples, there is provided an optical transceiver system comprising the herein proposed steering system (defining a receiving side) and the herein proposed transmitter system (defining a transmitting side). The optical transceiver system thereby incorporates the capabilities of both the receiving and transmitting components, enabling full- duplex communication.

[0215] On the receiving side, the steering system of the transceiver system is able to track and align with a desired light beam, as well as the ability to distinguish between multiple incident beams using embedded identifiers. This receiving functionality allows the transceiver to accurately detect and process incoming optical signals, even in complex environments with multiple light sources.

[0216] On the transmitting side, the transmitter system of the optical transceiver system is able to generate light beams with multiple components: a first component carrying an 2024PF80432

[0217] 28 embedded identifier, and optionally a second component carrying the actual data to be transmitted. This multi-component structure of the transmitted beam facilitates improved tracking and alignment at the receiving end, while also enabling efficient data transmission.

[0218] It will be appreciated that the optical transceiver system may be configured such that the receiving side and transmitter side cooperate to improve beam alignment through a dynamic feedback loop. In this process, the receiving side may continuously analyze / iteratively the incoming light beam and provide feedback to the transmitting side for adjusting the direction of the transmitted light beam, allowing for real-time adjustments to improve the communication link.

[0219] More particularly, the optical system (of the receiving side) may process embedded information carried by a desired light beam (produced by a desired external device) to identify the approximate position of the transmitted light beam upon the optical system of the desired external device.

[0220] The transmitter system may receive the approximate position of the transmitted light beam upon the optical system of the desired external device and process said approximate position to define one or more adjustments to the outgoing light beam's direction to improve an alignment of said approximate position with a desired position for the desired external device. These adjustments may involve small changes to the angles of mirrors, prisms, or other optical elements in the beam path.

[0221] Simultaneously, the receiving side may be configured to perform its own steering operation to improve beam alignment with the desired light beam, using a herein described approach

[0222] This cooperative alignment process may operate continuously during communication.

[0223] For the sake of completeness, Figure 8 is a flowchart illustrating a proposed method 800 for tracking a desired light beam of one or more light beams, incident upon the optical system, generated by one or more external devices in a field of regard. The method 800 may be performed by a herein proposed optical system.

[0224] The method 800 comprises a step 810 of receiving, at a position-sensitive device (PSD), a first portion of each light beam incident upon the optical system from the field of regard.

[0225] The method 800 also comprises a step 820 of generating, for each of a plurality of photo-sensitive segments on the position-sensitive device, a respective electronic signal responsive to the first portion of each light beam incident upon the optical system. 2024PF80432

[0226] 29

[0227] The method 800 also comprises a step 830 of processing the electronic signals produced by the position-sensitive device to determine, as a set of one or more first positions, an estimated of at least the desired light beam incident upon the optical system from the one or more external devices in the field of regard.

[0228] The method 800 also comprises a step 840 of receiving, at an image sensing arrangement (ISA), a second portion of each light beam incident upon the optical system from the field of regard.

[0229] The method 800 also comprises a step 850 of generating image data representing the field of regard responsive to the received second portion of each light beam.

[0230] The method 800 also comprises a step 860 of processing the received image data to determine, as a set of one or more second positions, an estimated position of each light beam incident upon the optical system from the field of regard.

[0231] The method 800 also comprises a step 870 of performing a tracking process comprising processing the set of one or more first positions and the set of one or more second positions to predict a position of the desired light beam. Example tracking processes have been previously described.

[0232] It has been previously mentioned how the image processing system is configured to process received image data to determine, as a set of one or more second positions, an estimated position of each light beam incident upon the optical system from the field of regard.

[0233] Conceptually, each light beam will be represented as a bright or high intensity spot within the image data. Moreover, different positions within the image data represent different positions upon the optical system. Bearing these principles in mind, it will be readily appreciated how the image processing system may process the image data to delineate or identify the centroid of each bright spot within the image data, to thereby identify the position of each light beam.

[0234] In particular, the image processing system may employ one or more image segmentation techniques and / or object detection techniques to identify one or more parts of the image data, each part representing a respective light beam incident upon the optical system. The position(s) of the centroid(s) of the identified part(s) of the image data function as the second position(s).

[0235] The skilled person would be readily capable of configuring the image processing system to use any suitable image segmentation technique for identifying parts of the image data representing a light beam. 2024PF80432

[0236] 30

[0237] One example is a threshold technique, in which parts of the image data having values breaching a predetermined threshold value are classified as representing a light beam. Another example is a region growing technique, in which seeds are selected within the image data (e.g., for parts having the highest intensity values) and regions are grown around these seeds based on similarity criteria. To improve robustness to potentially overlapping light beams, the image segmentation technique may employ a watershed segmentation approach. Such approaches help to distinguish between closely spaced or partially overlapping light beams.

[0238] Once the image segmentation technique has identified parts of the image data representing light beams, the position of each light beam may then be derived from these segmented parts. This process typically involves calculating the centroid of each segmented region.

[0239] A suitable approach is the weighted centroid method, which takes into account the intensity values within the segmented part. Another technique may, for instance, fit a (e.g., two-dimensional) Gaussian function to the intensity profile of the segmented region, with the peak of this fitted function representing the estimated beam position (and therefore the second position).

[0240] In some examples, the image processing system may be configured to process the received image data using a machine-learning method to determine the set of one or more second positions.

[0241] More specifically, the machine-learning method may be configured to function as an image segmentation technique to perform image segmentation on the image data to identify different parts of the image data representing a light beam. A suitable machine-learning method is the you-only-look-once algorithm, e.g., set out by Redmon, J. "You only look once: Unified, real-time object detection." Proceedings of the IEEE conference on computer vision and pattern recognition. 2016. Another suitable example is the faster R-CNN approach, e.g., set out by Ren, Shaoqing, et al. "Faster R-CNN: Towards real-time object detection with region proposal networks." IEEE transactions on pattern analysis and machine intelligence 39.6 (2016): 1137-1149. Yet another suitable example is the single shot detector approach, e.g., set out by Liu, Wei, et al. "Ssd: Single shot multibox detector." Computer Vision-ECCV 2016: 14th European Conference, Amsterdam, The Netherlands, October 11-14, 2016, Proceedings, Part I 14. Springer International Publishing, 2016. Other suitable examples will be apparent to the skilled person. The segmented part(s) may then be processed as previously described to derive the second position(s). 2024PF80432

[0242] 31

[0243] In another example, the machine-learning method may be configured to directly output the second position(s) by processing the image data. In this approach, a suitably trained machine learning method is used to directly map the input image data to the positions of light beams within the field of regard.

[0244] It is noted that a machine-learning algorithm is any self-training algorithm that processes input data in order to produce or predict output data. Here, the input data comprises image data and the output data comprises a segmentation result and / or positions of light beams.

[0245] Suitable machine-learning algorithms for being employed in the present invention will be apparent to the skilled person. Examples of suitable machine-learning algorithms include decision tree algorithms and artificial neural networks. Other machinelearning algorithms such as logistic regression, support vector machines or Naive Bayesian models are suitable alternatives.

[0246] The structure of an artificial neural network (or, simply, neural network) is inspired by the human brain. Neural networks are comprised of layers, each layer comprising a plurality of neurons. Each neuron comprises a mathematical operation. In particular, each neuron may comprise a different weighted combination of a single type of transformation (e.g. the same type of transformation, sigmoid etc. but with different weightings). In the process of processing input data, the mathematical operation of each neuron is performed on the input data to produce a numerical output, and the outputs of each layer in the neural network are fed into the next layer sequentially. The final layer provides the output.

[0247] Methods of training a machine-learning algorithm are well known. Typically, such methods comprise obtaining a training dataset, comprising training input data entries and corresponding training output data entries. The training output data entries may be defined by one or more suitable trained and / or experienced (human) individuals.

[0248] For some machine-learning algorithms, such as a neural network, training is performed by applying an initialized machine-learning algorithm to each input data entry to generate predicted output data entries. An error between the predicted output data entries and corresponding training output data entries is used to modify the machine-learning algorithm. This process can be repeated until the error converges, and the predicted output data entries are sufficiently similar (e.g. ±1%) to the training output data entries. This is commonly known as a supervised learning technique.

[0249] For example, where the machine-learning algorithm is formed from a neural network, (weightings of) the mathematical operation of each neuron may be modified until the 2024PF80432

[0250] 32 error converges. Known methods of modifying a neural network include gradient descent, backpropagation algorithms and so on.

[0251] In the context of the present disclosure, the training input data entries correspond to instances of image data. The training output data entries correspond to segmentation results and / or positions of light beams.

[0252] In some examples, the image processing system is configured to perform one or more preprocessing steps upon the image data, e.g., before processing with any image segmentation, object detection and / or machine-learning method. For instance, the image data may be pre-processed to enhance features and remove any noise that may interfere with (object or position) detection. Common preprocessing techniques include resizing, normalization, and converting images to grayscale. These steps ensure that the image data is clean and standardized before analytical processing.

[0253] Suitable examples of components for forming the image processing system will be readily apparent to the skilled person. A number of examples are hereafter provided for the sake of completeness.

[0254] In particular the image processing system may be designed for running machine learning models (e.g., particularly neural networks like CNNs) at high speed with low power consumption. This image processing system may, for instance, comprise one or more graphic processing units (GPUs), neural processing units (NPUs), digital signal processors (DSPs), field-programmable gate arrays (FPGAs), and application-specific integrated circuits (ASICs).

[0255] GPUs have been adapted for the performance of machine-learning models, including object detection and tracking, and have exhibited high efficiency in doing so. NPUs are specialized processing units dedicated to accelerating machine-learning method tasks and also exhibit high efficiency. DSPs are commonly used for real-time data processing. FPGAs allow developers to customize the hardware architecture for specific machine-learning model tasks, offering both flexibility and speed for image processing. ASICs are custom-designed chips tailored for specific machine-learning tasks, such as high-performance deep learning inference for image detection.

[0256] Some proposed embodiments make use of one or more processing systems (e.g., the signal processing system, the image processing system or the control system). Each processing system can be implemented in numerous ways, with software and / or hardware, to perform the various functions required. A processor is one example of a processing system which employs one or more microprocessors that may be programmed using software (e.g., microcode) to perform the required functions. A processing system may however be 2024PF80432

[0257] 33 implemented with or without employing a processor, and also may be implemented as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions.

[0258] Examples of processing system components that may be employed in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs).

[0259] In various implementations, a processor or processing system may be associated with one or more storage media such as volatile and non-volatile computer memory such as RAM, PROM, EPROM, and EEPROM. The storage media may be encoded with one or more programs that, when executed on one or more processors and / or processing systems, perform the required functions. Various storage media may be fixed within a processor or processing system or may be transportable, such that the one or more programs stored thereon can be loaded into a processor or processing system.

[0260] It will be understood that disclosed methods are preferably computer- implemented methods. As such, there is also proposed the concept of a computer program comprising code means for implementing any described method when said program is run on a processing system, such as a computer. Thus, different portions, lines or blocks of code of a computer program according to an embodiment may be executed by a processing system or computer to perform any herein described method.

[0261] There is also proposed a non-transitory storage medium that stores or carries a computer program or computer code that, when executed by a processing system, causes the processing system to carry out any herein described method.

[0262] In some alternative implementations, the functions noted in the block diagram(s) or flow chart(s) may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

[0263] Ordinal numbers (e.g. “first”, “second” and so on) have been used purely to distinguish different elements from one another for the sake of clarity, and does not necessarily imply a specific order, importance, relationship, or presence of all numbered elements. Reference to a non-“firsf ’ (e.g. “second” or “third”) element does not necessitate that a “first” element be present. The skilled person would be capable of relabeling any such elements as appropriate (e.g. relabeling a “second” element as a “first” element if only the second element is present). 2024PF80432

[0264] 34

[0265] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0266] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to". If the term "arrangement" is used in the claims or description, it is noted the term "arrangement" is intended to be equivalent to the term "system", and vice versa.

[0267] A single processor or other unit may fulfill the functions of several items recited in the claims. If a computer program is discussed above, it may be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0268] Any reference signs in the claims should not be construed as limiting the scope.

Claims

2024PF8043235CLAIMS:

1. An optical system (200) for tracking a desired light beam of one or more light beams (290), incident upon the optical system, generated by one or more external devices (20, 30) in a field of regard (15), the optical system comprising: a position-sensitive device (210) configured to receive (810) a first portion (291 ) of each light beam incident upon the optical system from the field of regard and, for each of a plurality of photo-sensitive segments on the position-sensitive device, generate (820) a respective electronic signal (215) responsive to the first portion of each light beam incident upon the optical system; a signal processing system (220) configured to process (830) the electronic signals produced by the position-sensitive device to determine, as a set of one or more first positions, an estimated position of at least the desired light beam incident upon the optical system from the one or more external devices in the field of regard and iteratively update the set of one or more first positions at a first frequency; an image sensing arrangement (230) configured to receive (840) a second portion of each light beam incident upon the optical system from the field of regard and generate (850) image data (235) representing the field of regard and to iteratively update the image data; an image processing system (240) configured to receive the image data representing the field of regard and process the received image data to determine (860), as a set of one or more second positions, an estimated position of each light beam incident upon the optical system from the field of regard and iteratively update the set of one or more second positions at a second frequency; and a tracking system (250) configured to performatracking process (300, 400, 500, 870) comprising processing the set of one or more first positions and the set of one or more second positions to determine an approximate position of the desired light beam and to iteratively perform a plurality of iterations of the tracking process, wherein each iteration of the tracking process comprises processing the iteratively updated set of one or more first positions and the iteratively updated set of one or more second positions to determine the approximate position of the desired light beam for the said iteration and wherein:2024PF8043236 the second frequency is less than the first frequency; and the tracking system, when operating in a first mode, is configured to, for each iteration of the tracking process: responsive to the set of one or more second positions being updated more recently than the set of one or more second positions, define or update the approximate position of the desired light beam for said iteration using the set of one or more second positions; and responsive to the set of one or more first positions being updated more recently than the set of one or more second positions, define or update the approximate position of the desired light beam for said iteration using only the set of one or more first positions.

2. The optical system of claim 1, wherein: each light beam generated by the one or more external devices comprises a first component carrying an embedded identifier; the signal processing system is configured to: filter each electronic component to identify, for each electronic signal, a target component of the electronic signal that represents the first component carrying the embedded identifier of the desired light beam; and process only the target component to determine the approximate position of the desired light beam.

3. The optical system of claim 2, wherein the first component comprises: a first set of one or more modulation frequencies of the light beam; or an encoded modulation pattern of the light beam defining the embedded identifier.

4. The optical system of claim 1, wherein each iteration of the tracking process comprises processing an approximate position of the desired light beam from at least one previous iteration of the tracking process, the iteratively updated set of one or more first positions and the iteratively updated set of one or more second positions to determine the position of the desired light beam for said iteration.

5. The optical system of any one of claims 1 to 4, wherein: the image processing system is configured to define, for each second position, an intensity of the light beam incident upon the optical system at the second position; and2024PF8043237 the tracking system is configured to determine an estimated position of the desired light beam responsive to the defined intensity for each second position.

6. The optical system of claim 5, when dependent upon claim 2, wherein: the signal processing system is configured to process the electronic signals produced by the position-sensitive device to determine, as the set of one or more first positions, a single estimated position for each embedded identifier; the tracking system, when operating in a second mode, is configured to, responsive to the set of one or more first positions comprising only a single first position and the set of one or more second positions comprising a plurality of second positions: if the first position matches a single one of the second positions, determine the first position as the approximate position of the desired light beam; and if the first position does not match any of the second positions, identify the second position having the brightest defined intensity amongst a sub-set of second positions that are all connected by a hypothetical line passing through the first position.

7. The optical system of any one of claims 1 to 6, wherein the signal processing system is configured to process the electronic signals produced by the position-sensitive device to determine the position of each light beam incident upon the optical system from the one or more external devices in the field of regard.

8. The optical system of any one of claims 1 to 7, wherein the image processing system is configured to process the received image data using a machine-learning method to determine the set of one or more second positions.

9. The optical system of any one of claims 1 to 8, wherein the position sensitive device is a quadrant photodetector.

10. A steering control system (610) for controlling the operation of a steerable element configured to control the relative position at which each light beam is incident on the optical system, the steering control system comprising: the optical system (200) of any one of claims 1 to 9; and a control system (615) configured to control the operation of the steerable element responsive to the determined approximate position of the desired light beam.2024PF804323811. A steering system (600) comprising: the steering control system (610) of claim 10; and the steerable element (620).

12. A mobile communication device (700) comprising: the steering system (600) of any one of claims 10 or 11; a light sensing module (710) configured to receive each light beam incident upon the optical system and generate a data signal responsive to any embedded information in each light beam incident upon the optical system; a processing system (720) configured to perform one or more operations responsive to the data signal; and a transmitter system (730) configured to generate one or more output light beams, carrying output data, for directing towards the external device generating the desired light beam. wherein the steerable element is configured to synchronously control the relative position at which each light beam is incident upon the light sensing module with the relative position at which each light beam is incident upon the optical system;13. A method (800) for tracking a desired light beam of one or more light beams, incident upon an optical system, generated by one or more external devices in a field of regard, the method comprising: receiving (810), at a position-sensitive device, a first portion of each light beam incident upon the optical system from the field of regard; generating (820), for each of a plurality of photo-sensitive segments on the position-sensitive device, a respective electronic signal responsive to the first portion of each light beam incident upon the optical system; processing (830) the electronic signals produced by the position-sensitive device to determine, as a set of one or more first positions, an estimated position of at least the desired light beam incident upon the optical system from the one or more external devices in the field of regard and iteratively update the set of one or more first positions at a first frequency; receiving (840), at an image sensing arrangement, a second portion of each light beam incident upon the optical system from the field of regard, generating (850) image data2024PF8043239 representing the field of regard responsive to the received second portion of each light beam and to iteratively update the image data; processing (860) the received image data to determine, as a set of one or more second positions, an estimated position of each light beam incident upon the optical system from the field of regard and iteratively update the set of one or more second positions at a second frequency; and performing (870) a tracking process comprising processing the set of one or more first positions and the set of one or more second positions to determine a position of the desired light beam and to iteratively perform a plurality of iterations of the tracking process, wherein each iteration of the tracking process comprises processing the iteratively updated set of one or more first positions and the iteratively updated set of one or more second positions to determine the approximate position of the desired light beam for the said iteration and wherein: the second frequency is less than the first frequency; and the tracking process when operating in a first mode, is configured to, for each iteration of the tracking process: responsive to the set of one or more second positions being updated more recently than the set of one or more second positions, define or update the approximate position of the desired light beam for said iteration using the set of one or more second positions; and responsive to the set of one or more first positions being updated more recently than the set of one or more second positions, define or update the approximate position of the desired light beam for said iteration using only the set of one or more first positions.

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