Optical wireless communication transmitter apparatus

Abstract

A transmitter apparatus comprising: a plurality of optical wireless communication (OWC) transmitters arranged and configured to transmit OWC signals in an initial beam pattern, wherein the plurality of transmitters are provided in a planar light emitting surface; an optical device configured to transform the initial beam pattern to a beam pattern in a reception region at a distance from the optical device wherein the optical device is configured to form a tiled beam pattern, wherein the tiled beam pattern is a far field pattern and / or wherein the tiled beam pattern and / or at least one property of the tiled beam pattern is substantially maintained and / or unmodified along a propagation direction in the reception region, wherein the optical device comprises one or more optical components corresponding to or arranged as one or more optical layers, wherein each optical layer of the one or more optical layers is configured to modify one or more properties of light beams transmitted from the plurality of transmitters to form the tiled beam pattern in the reception region, wherein each optical layer lies substantially in and / or defines a plane that is substantially parallel to the planar light emitting surface.

Description

[0001] M&C PE963133GB

[0002] 1

[0003] Optical Wireless Communication Transmitter Apparatus Field

[0004] The present disclosure relates to an optical wireless communication transmitter device and associated methods.

[0005] Background

[0006] Optical wireless communication is a known technology in which data is transmitted using optical signals. It is known to transmit optical signals in a tiled pattern to obtain coverage over an area. Known solutions produce such tile patterns in experimental settings that may not be suitable in real world environments. There is a need to provide a transmitter apparatus that provides desired beam patterns for use in practical and real world environments.

[0007] Summary

[0008] In accordance with a first aspect, there is provided a transmitter apparatus comprising: a plurality of optical wireless communication (OWC) transmitters arranged and configured to transmit OWC signals in an initial beam pattern; an optical device configured to transform the initial beam pattern to a beam pattern in a reception region at a distance from the optical device wherein the optical device is configured to form a tiled beam pattern. The tiled beam pattern may alternatively be referred to as a tile beam pattern. The tiled beam pattern may be formed as a far field pattern. The tiled pattern may be substantially maintained and / or unmodified along a propagation direction in the reception region. At least one property of the tiled beam pattern may be substantially maintained and / or unmodified along a propagation direction in the reception region.

[0009] The tiled pattern may be substantially maintained and / or unmodified as the beams propagate along the propagation direction. The tiled pattern and / or at least one property of the tiles pattern may be substantially maintained and / or unmodified as the beams propagate along the propagation direction and as the size and / or coverage area of the tiled pattern increases in size along the propagation direction.

[0010] The at least one property of the tiled pattern may comprise: a degree of overlap between tiles; a separation between tiles; a relative position of the tiles; a shape of the plurality of tiles and / or an intensity profile of each tile.

[0011] The size and / or coverage area of the tiled pattern may increase in size as the beams propagate along the propagation direction through at least part of the reception region.

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[0014] The at least one property of the tiled pattern may be maintained as the size and / or coverage area grows through at least part of the reception region.

[0015] The optical device may be configured to transform the initial beam pattern to an exit beam pattern on exiting the optical device, wherein the exit beam pattern is a near field pattern that evolves and / or forms the tiled beam pattern as exit beam pattern propagates through free space or other medium.

[0016] The optical device may be configured to form one or more intermediate beam patterns, Each transmitter may have an initial field of illumination in respect of which it is configured to transmit OWC signals, wherein the optical device is configured to transform the initial field of illumination, wherein the transformed field of view of each transmitter forms at least part of a tile of the tiled beam pattern.

[0017] The tiled beam pattern may propagate through the reception region without substantial degradation. The tiled beam pattern may propagate through the reception region maintaining a separation between adjacent tiles. The tiled pattern may maintain a separation between tiles, a size and / or shape and / or relative position of each tile. The tiled pattern may retain a relative size of each tile such that each tile proportionally increase in size. The tiled beam pattern may comprise a planar pattern and / or wherein the tiled pattern comprises substantially no and / or minimal overlap and / or a desired degree of overlap between adjacent tiles. Each tile of the tiled pattern may be formed by at least one transmitter. The tiled beam pattern may cover a coverage area.

[0018] The pattern may be formed at a pattern formation distance from the optical device. The propagation distance may be a distance at which a Fresnel number is less than 1. The pattern formation distance may be in the range 0 to 1 m from the optical device. The apparatus may be provided in an environment and the reception region may span from the pattern formation distance to a boundary of an environment, for example, a wall or floor or ceiling of the environment. The reception region may have a size of 1 to 5 metres. The reception region may have a length in the propagation direction between 1 and 10 metres, optionally between 1 and 5 metres.

[0019] The optical device may comprise one or more optical components corresponding to or arranged as one or more optical layers, wherein each optical layer of the one or more

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[0022] optical layers is configured to modify one or more properties of light beams transmitted from the plurality of transmitters, wherein the one or more properties comprise one or more of: a beam divergence, a beam direction and a beam shape, optionally wherein the one or more optical layers together act to modify the beam divergence, beam direction and beam shape properties to form the tiled pattern in the reception region.

[0023] One or more of the optical components and / or optical layers may be movable and / or replaceable to adjust one or more properties of the tiled pattern, optionally at least one of the beam shape and / or size and / or relative position.

[0024] One or more of the optical layers may be moveable relative to the transmitters to control one or more properties of the tiled pattern. One or more of the optical layers and / or transmitters may be moveable to obtain a relative movement therebetween.

[0025] The one or more optical layers may comprises at least one beam collimation layer, at least one beam steering layer and at least one beam shaping layer and / or wherein the plurality of layers comprise an optical layer configured to perform at least two of collimation, beam shaping and beam steering.

[0026] At least the collimation and / or shaping layer may be configured to output a plurality of substantially parallel beams. The shaping layer may output a plurality of substantially parallel beams for the steering layer. The shaping and / or steering may form a single, substantially planar layer, configured to receive a plurality of parallel beams.

[0027] At least some, optionally all light beams from the transmitters may pass through each optical layer. At least one of the optical layers may comprise a shared surface or optical component through which at least some, optionally all beams from the transmitters pass through. The optical layers may comprise diffractive optical elements and / or nonfocussing optical elements.

[0028] The one or more optical layers comprise a plurality of optical layer arranged in a stacked arrangement. The stacked arrangement may comprise one or more spacing layers between adjacent optical layers.

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[0031] Each optical layer may be formed by one or more discrete optical components. The optical layers may be spaced apart in a propagation direction. One or more optical layers may comprise a discrete optical component.

[0032] Each optical layer may lie substantially in and / or define a plane and wherein the plurality of planes are in a parallel arrangement.

[0033] The plurality of optical layers may be substantially planar. The plurality of optical layers may be provided in a substantially parallel arrangement. The plurality of transmitters may be provided on or form a light emitting surface that is parallel to the plurality of optical layers. The optical device may comprise a collimating layer, a beam shaping layer and a beam steering layer arranged in a substantially parallel arrangement.

[0034] The plurality of transmitters may be provided in a planar light emitting surface, and the optical device may comprise one or more optical layers provided on one or more plurality of planes, wherein the one or more plurality of planes are parallel to the light emitting surface and / or wherein each is at a fixed distance from the light surface.

[0035] One or more of the optical layers may comprise a monolithic and / or one-piece construction and / or freeform optic.

[0036] The optical device may comprise a modular structure wherein one or more of the optical components, optionally optical layers, is interchangeable by a further optical component or layer to change at least one property of the tiled pattern

[0037] The optical device, optionally an optical layer of the optical device, may be configured to limit a degree of spread of each beam from a respective transmitter in dependence on a corresponding degree of beam steering provided by the optical device, optionally a further optical layer, to prevent and / or at least limit overlap between adjacent tiles in the reception region

[0038] The optical device may comprise a homogenising and / or beam shaping device, optionally configured to shape light to form a tile having a substantially uniform or flat-top distribution, further optionally at the reception region.

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[0041] The homogenising and / or beam shaping device may comprise a diffuser, a lens array or a freeform optic and / or metalens optic.

[0042] The homogenising and / or beam shaping device may comprise at least one shared, optionally planar, optical component and / or surface, wherein the at least one shared optical component and / or surface is shared between at least some of the transmitters forming the tiled pattern.

[0043] The beam shaping layer may comprise a single, optionally more than one, optionally two monolithic optical components.

[0044] Beam Shaping may comprise modifying an outline and / or intensity profile of an optical beam and / or spreading an optical beam to fill an outline. The tiled pattern formed by the optical device may be a far field pattern and may be formed at a distance from the optical device, optionally at a plane of interest, and the optical device may be configured to produce and substantially maintain the far field pattern as the light propagates from the optical device beyond the plane of interest. The tiled pattern may be substantially maintained along a propagation direction from the optical device and / or formed in a plurality of planes along a propagation direction. The tiled pattern may be formed in a plurality of reception planes at a respective plurality of different distances from the device. The tiled pattern may be formed and / or substantially maintained away from a focal plane of the optical device

[0045] At least one of the optical layers may comprise a plurality of inclined surfaces arranged to lie substantially in a single plane, optionally wherein each inclined surface intersects said plane and / or a non-inclined opposing surface of each inclined surface lies in said plane, wherein each inclined surface is configured to receive at least one light beam propagating along a first optical axis and redirect said at least one light beam along a second optical axis, optionally wherein the plurality of inclined surfaces comprises an array of inclined surfaces spatially aligned with a corresponding array of transmitters.

[0046] The plurality of inclined surfaces may form part of a multi-faceted optical element and / or a lens.

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[0049] The optical device, optionally an optical layer may be configured to compensate for degradation in the tiled pattern, for example, a separation between tiles, a shape of tiles and / or intensity of tiles and / or angular distortion and / or off angle propagation.

[0050] The optical device may be configured to transform the initial beam pattern to produce a distorted exit beam pattern, wherein the distorted exit beam pattern forms the tiled pattern in the reception region.

[0051] The distortion may comprise a skewed, twisted and / or otherwise distorted part of a tile.

[0052] The plurality of transmitters may comprise a first plurality of transmitters in a first arrangement, for example, a square array, wherein the optical device is aligned with the plurality of transmitters to receive light from the first plurality of transmitters, wherein the optical device comprises one or more peripheral or further transmitters configured to transmit OWC signals through a field of view that overlaps or coincides with part of the tiled pattern. The peripheral transmitters may be provided at the periphery or outside the first arrangement of transmitters

[0053] The optical device may be aligned with the transmitters such that a propagation direction of a beam from the peripheral or further transmitters is substantially unmodified by the optical device and / or such that the light of the peripheral or further transmitters is modified to the same degree as a selected beam of the plurality of beams and / or such that the light of the peripheral or further transmitters evolves to contribute to one or more tiles of the tiled pattern in the reception region, optionally one or more central tiles.

[0054] The optical device and transmitters may be arranged and / or sized so that the optical device steers beams from the first plurality of transmitters to form the tiled pattern and so that beams from the peripheral or further transmitters avoid or are steered to a lesser degree by the optical device.

[0055] The optical device may comprises at least two co-operating optical layers or components configured to co-operate to at least shape optical beams thereby to form tiles of the tiled pattern with a desired shape, wherein the shape and / or size and / or a further property of the produced optical beam is dependent on a relative positioning of the at least two cooperating optical layers or components.

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[0058] The at least two co-operating optical layers and / or components may be moveable between a first configuration in which the formed tile has a first size and / or shape and / or other property and a second configuration in which the formed tile has a second size and / or shape and / or other property. The first size and / or shape and / or other property may comprise a maximum tile size and the second size and / or shape and / or other property may comprise a minimum tile size. The at least two co-operating optical layers may be moveable to a plurality of intermediate configurations having intermediate size, shape and / or other property.

[0059] The device may comprise a mechanism to obtain relative movement, optionally translational and / or rotational movement of the co-operating optical layers

[0060] Each of the co-operating optical layers may comprise a rotational and / or a translation symmetry. The co-operating layers may comprise an array of spherical, cylindrical and / or aspherical refractive portions. The co-operating layers may comprise at least one continuous surface and / or undulating and / or ridged surface. The co-operating layers may comprise a continuous surface formed of maxima and minima. The co-operating layers may comprise a continuous surface formed of a repeated array of maxima and minima.

[0061] The co-operating layers may comprise a plurality of refractive elements, optionally focusing and diverging elements, in a regular arrangement, optionally a lattice and / or array.

[0062] The co-operating layers may comprise a repeating unit cell comprising focussing and diverging elements, optionally elements of positive and negative curvature, wherein the shape of the optical beam is dependent on the relative position between the focussing and divergent elements of the respective optical layers.

[0063] A degree of beam shaping and / or size of a tile may be dependent on a relative position and / or orientation between the unit cell of the first refractive device and the unit cell of the second refractive device.

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[0066] When spatially aligned, the focusing effect of the focusing element substantially cancels the divergent effect of the divergent element of beams through both layers and / or wherein the focusing element focuses light to the same degree that the second divergent element disperses light. The focusing element and the divergent element may have equal and opposite degrees of curvature. The co-operating optical layers may comprise a lens array or freeform optic or other one-piece optical component comprising a plurality of focusing and / or diverging protrusions and / or depressions. The co-operating optical layers may have first focusing / diverging surfaces and a second substantially planar surface, wherein the devices are arranged such that their planar surfaces are adjacent

[0067] Each tile may comprise an intensity or power distribution and / or an optical beam profile, optionally, wherein the light distribution comprises a substantially uniform or flat-top distribution. The formed tiled pattern substantially may cover a combined area of a plane in a field of transmission of the plurality of transmitters. Each tile may have a position. The tiled pattern may comprise a tessellation pattern and / or the desired tile shape may comprise a shape capable of being tessellated. Each tile may comprise a desired shape, for example, a square, rectangular, quadrilateral, hexagonal, polygonal or any other symmetric or asymmetric shape. Each tile is tile-able and / or tessellate-able. The optical device of any preceding claim, wherein the tiled pattern comprises an arrangement of tiles without gaps or overlapping. The tiled pattern may comprise a regular pattern.

[0068] The transformed beam of each transmitter may have an intensity distribution of defined shape or perimeter or contour, optionally wherein the defined shape or perimeter or contour is configured to interface with or match the defined shape or perimeter or contour of a transmission field of view of an adjacent transmitter thereby to at least reduce or limit overlapping of the respective transmission field of views, optionally wherein the intensity distribution within the transmission field of view across a plane of reception within the operating region is a substantially uniform intensity distribution.

[0069] The OWC signals may comprise LiFi signals. The OWC light signals may comprise modulated visible, infra-red, ultraviolet or terahertz signals. The OWC signals may be in accordance with one or more of IEEE 802.15.7, 802.15.13, 802.11 or extensions or developments thereof; ITU-T G.9960 or extensions or developments thereof; or ITU-T G.vlc or extensions or developments thereof.

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[0072] The apparatus may comprise, or forms part of, an access point. The access point may be connectable to a network, for example a local area network (LAN) and / or the internet or other remote network, via a wired connection and / or a mains power data connection and / or a wireless connection.

[0073] The OWC signals transmitted by the apparatus may include data received from the network and / or the OWC signals may establish and / or maintain a communication session via the network with the or a remote device. At least one of the transmitters may be, or form part of, an illumination light source, for example an uplighter, downlighter, spot lamp, standard lamp or table lamp.

[0074] Each transmitter may comprise at least one light-emitting diode (LED) or vertical-cavity surface-emitting laser (VCSEL).

[0075] In accordance with a second aspect there is provided a receiver apparatus. The receiver apparatus may be configured for use with a transmitter apparatus as provided in accordance with the first aspect or as described herein. The receiver apparatus may comprise one or more receivers and one or more optical components, arranged separately and / or in one or more optical layers, wherein the one or more optical components are configured to steer and focus or otherwise transform light received from one or more tiles of the formed tiled pattern for the plurality of receivers.

[0076] The one or more optical components may be configured to match the degree of steering and / or focussing to the tiled pattern formed by the transmitter apparatus. Each receiver of the plurality of receivers may correspond to a transmitter and / or a tile of the formed tiled pattern. The one or more optical components may be configured to transform a plurality of incoming beams in a plurality of direction determined by the tiled pattern to a plurality of parallel beams for the receivers.

[0077] The corresponding transmitter apparatus may be configured to transmit OWC signals into one or more zones corresponding to said one or more tiles of the tiled pattern and the one or more optical components may be configured to transform light carrying OWC signals transmitted from said one or more zone for reception by said receivers. Transforming said light may comprise steering and / or focussing. The one or more optical

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[0080] components may be configured to match the degree of steering and / or focussing to the tiled pattern formed by the transmitter apparatus.

[0081] Each receiver of the plurality of receivers may correspond to a transmitter and / or a tile of the formed tiled pattern formed by a transmitter apparatus as claimed or described herein. The plurality of receivers may be provided on a single circuit and / or in a planar arrangement.

[0082] Each receiver may have an initial field of view. The apparatus may comprise one or more optical components, arranged separately and / or in one or more optical layers, configured to transform the field of view of the plurality of receivers to receive OWC signals from further devices respective tiles of the tiled pattern formed by the transmitter apparatus.

[0083] The one or more optical components may at least tilt the field of view relative to the initial field of view.

[0084] The one or more optical components may be configured to steer and / or focus light from each of the plurality of tiles of the tiled pattern. The transformed field of view may be matched to the direction and / or size of a corresponding tile of the tiled pattern. The field of view may be sized to receive an OWC signal from a device in a tile of the tiled pattern formed by the transmitter apparatus.

[0085] The one or more optical components may be configured to transform a plurality of incoming beams, for example, received from zones corresponding to a tiled pattern, and transformed the incoming beams to a plurality of parallel beams.

[0086] The optical components may be comprise one or more inclined and / or shaped and / or offset portions configured to transform the field of view. The optical components may be configured to receive OWC signals from each tile of the formed tiled pattern and redirect said signals to the plurality of receivers.

[0087] The receiver optical components may comprise an upper and a lower surface, wherein one or more reflective, refractive and / or diffractive optical features are formed on the upper and / or lower surface to transform the field of view. The optical features may comprise one or more protrusions and / or depressions.

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[0090] At least some of the receiver optical components may be provided in a single, monolithic and / or free-formed optic.

[0091] The transmitter apparatus may be configured to emit OWC signals into reception zones of an environment corresponding to the tiled pattern. Each reception zone of the environment may correspond to a tiled pattern. The receiver apparatus may be configured to modify light carrying OWC signals transmitted from within said zones for the plurality of receivers.

[0092] The one or more optical components may comprise at least one optical component and / or surface shared between two or more, optionally all, receivers, and configured to steer light to said two or more, optionally all, receivers.

[0093] In accordance with a third aspect there is provided a transceiver apparatus comprises the transmitter apparatus of the first aspect or as described herein and the receiver apparatus of the second aspect or as described herein.

[0094] In accordance with a fourth aspect there is provided a system comprising the transmitter apparatus of the first aspect or as described herein and the receiver apparatus of the second aspect or as described herein. The transmitter apparatus and receiver apparatus may be provided at separate locations within an environment.

[0095] In accordance with a fifth aspect, there is provided an optical device comprising at least two optical components configured to co-operate to shape optical beams from one or more OWC transmitters to shape the one or more beams, wherein the shape and / or size and / or further property of the produced tile is dependent on a relative positioning of the co-operating optical components. The optical device may form part of an access point and / or other network connected device.

[0096] In accordance with a fifth aspect, there is a method of transmitting optical wireless communication signals comprising: transmit OWC signals in an initial beam pattern and transforming the initial beam pattern to a tiled beam pattern in a reception region at a distance from the optical device. The tiled beam pattern may be formed as a far field pattern. The tiled beam pattern may be substantially maintained and / or unmodified along

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[0099] a propagation direction in the reception region. At least one property of the tiled beam pattern may be substantially maintained and / or unmodified along a propagation direction in the reception region.

[0100] In accordance with a sixth aspect, there is a method of receiving optical wireless communication signals comprising: receiving light from one or more tiles of a tiled pattern; steering, optionally focussing and / or otherwise transforming said light for a plurality of receivers.

[0101] Features of one aspect may be provided as features of another aspect. For example, apparatus and / or device feature may be provided as method features and vice versa.

[0102] Brief Description of Figures

[0103] Various aspects of the invention will now be described by way of example only, and with reference to the accompanying drawings, of which:

[0104] Figure 1 is a schematic diagram of an OWC transmitter device in accordance with an embodiment;

[0105] Figure 2 is a schematic diagram of an OWC transmitter device in accordance with an embodiment;

[0106] Figure 3(a) depicts a transmitter array and Figure 3(b) depicts a tiled pattern; Figure 4 is a schematic diagram of an OWC transmitter device in accordance with an embodiment;

[0107] Figure 5 depicts simulated results from an OWC transmitter device in accordance with an embodiment;

[0108] Figure 6(a) depicts a transmitter array and Figure 6(b) depicts a tiled pattern, in accordance with a further embodiment;

[0109] Figure 7 depicts a transmitter device in accordance with a further embodiment; Figure 8(a) and Figure 8(b) depict simulated results;

[0110] Figure 9(a) and (b) are perspective views of a transmitter device in accordance with an embodiment and Figure 9(c) depicts an optical layer of the device;

[0111] Figure 10, 11 and 12 depicts simulated results from a transmitter device in accordance with an embodiment;

[0112] Figure 13 is a plot of a height variation of an optical component of the device; Figure 14 is an illustration of an optical component for beam shaping;

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[0115] Figure 15 is an illustration of two co-operating optical components for beam shaping;

[0116] Figure 16 depicts an optical component of the device;

[0117] Figure 17 is a plot of a height variation of an optical component of the device; Figure 18 depicts simulated results from a transmitter device in accordance with an embodiment;

[0118] Figure 20(a) and (b) depict a transceiver apparatus in accordance with an embodiment;

[0119] Figure 21 depicts optical components for a plurality of receivers.

[0120] Detailed Description

[0121] The term light herein may be used, for example, to refer to electromagnetic waves with wavelengths in a range 1 nm to 2360 nm, which includes ultraviolet, visible light and near-infrared wavelengths.

[0122] In the following description, the terms near field and far field are used. In this context, near field may be understood as a region (the distance from a light source or optic) in which a wavefront of propagating light is approximately spherical while far field can be understood as a region in which the wavefront of propagating light is approximately planar. Near field domain behaviour can be modelled using Fresnel diffraction theory and far field domain behaviour may be modelled using Fraunhofer diffraction theory.

[0123] More concretely, the far field could be considered to correspond to a region in which the Fresnel number is less than one. Fresnel number is defined as:

[0124]

[0125] where a is aperture size, L is propagation length and lambda is wavelength. For a given size of optic, a propagation distance can be calculated beyond which the far field radiation pattern is adopted.

[0126] In the following embodiments, the aperture may be defined by the collimation optics. In the embodiments describes below, the collimation optics are presented as the first optic

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[0129] to set the initial beam size. The aperture is therefore a design variable, the wavelength is set by external factors like what VCSEL or APD is selected, and the propagation length a design goal. In some embodiments, design considerations include forming an optic having a minimum useable distance (L in the equation above with Fresnel number <1) while keeping the spot size large enough to make optics easy to manufacture. Eye safety may also be a consideration.

[0130] In the absence of optics, the wavefronts of the propagating light will change from spherical to planar (i.e. near field to far field) as the light propagates over a suitable distance. Once the light has propagated to form the far field pattern, it will continue to propagate with this pattern unless it interacts with further objects. Propagation from near filed to far field can be understood as a spherical wave (near field approximation) evolving to a plane wave approximation. In practice, the far field pattern can be considered to be formed at a distance from the optics at which point the Fresnel number, defined above is lower than 1.

[0131] In accordance with embodiments, a transmitting apparatus, for forming a grid of beams is provided. The grid of beams may be tessellated, or at least partially overlapping. In accordance with embodiments, the transmitter optics are configured to collimate, steer and shape light from a transmitter.

[0132] Figure 1(a) is a schematic view of an optical wireless communication (OWC) transmitter apparatus, in accordance with an embodiment. The transmitter apparatus 10 has a plurality of transmitters 18 and an optical device 15.

[0133] The optical device 15 has a number of optical layers. The optical layers can be considered to form functional units or modules. It will be understood that two or more of the layers may be combined as a single layer configured to perform one or more optical function. Each layer can be formed by more than one optical device or optical components or may be a single monolithic optical component. Each optical layer is configured to modify one or more properties of a light beam.

[0134] The optical device 15 is for use with a plurality of optical wireless communication transmitters 18. The transmitters 18 are configured to emit optical signals carried by or forming part of a plurality of beams (indicated by reference 11). In some embodiments

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[0137] the transmitters form a light emitting surface. In accordance with embodiments, each transmitter may be an addressable light source, such that a subset of the plurality of transmitters can be activated at one time, for example, in accordance with a suitable OWC transmission algorithm or scheme.

[0138] Each transmitter has an initial field of illumination into which optical signals are transmitted. The field of illumination of the transmitter determines the initial beam divergence or spread of a beam. The transmitters are provided in an arrangement such that the transmitters together output beams in accordance with an initial beam pattern. The field of illumination of the transmitters is such that, in the absence of the optical device, the beams would propagate in a propagation direction from the transmitter and eventually overlap. As such the initial beam pattern of the transmitters can be understood to be a near field beam radiation pattern. The initial beam pattern will be understood as existing between the transmitters and the optical device. In general, the optical device is provided sufficiently close to the transmitters that the beams do not overlap before reaching the optical device.

[0139] The optical device 15 is configured to receive the plurality of beams 11 in the initial beam pattern and transform the initial beam pattern into a beam pattern The beam pattern formed by the optical device has a number of desired properties. For example, the beam pattern may have no or minimal or a desired degree of overlap. In addition, each tile of the beam pattern may have a desired shape or intensity profile. An example of a beam pattern is depicted in Figure 3(b). In accordance with embodiments, the beam pattern is a tiled beam pattern or tile beam pattern. The tiled beam pattern may also be referred to as a tiled pattern or tile pattern and will be understood to be formed by a plurality of beams. The tiled beam pattern is formed at a propagation distance from the optical device in a desired reception region. The tiled beam pattern will be understood to be a far field radiation pattern.

[0140] To form the beam pattern, the primary properties modified by the layers of the optical device include beam divergence, beam direction and beam shape. As such, for the purposes of illustration, the optical device has a collimation layer 12 for collimating a received light beam, a beam steering layer 14 for steering a light beam and a beam shaping layer 16 for shaping a light beam. In some embodiments a single optical layer may perform both beam steering and beam shaping.

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[0143] In the present embodiment, the collimation layer collimates the beam to the highest degree possible, leading to the steepest edge to the tile. In alternative embodiments, the collimating layer may collimate the beam to a lesser degree. By adjusting the degree of collimation, the edge shape of the formed tile may be controlled.

[0144] To form the tiled beam pattern, in some embodiments, the optical device modifies one or more properties of light received from the transmitters to transform the initial beam pattern to one or more intermediate beam patterns. In particular, the optical device transforms the initial beam pattern to an exit beam pattern on immediate exit from the optical device. The exit beam pattern is a near field pattern that evolves as it propagates through free space (or any other medium) to form the tiled pattern at the reception region. The tiled pattern is formed as a far field radiation pattern.

[0145] It will be understood that substantially all of the light beams pass through every optical layer to form the tile pattern. In addition, the ordering of optical layers may differ between embodiments. For example, in some embodiments, beam shaping may be performed prior to beam steering and vice versa. By combining one or more optical layers that perform collimation, shaping and steering with the transmitters the beam pattern can be formed at a reception region.

[0146] Figure 1(b) depicts the transmitter apparatus in an environment, in accordance with an embodiment. The device may be used in a number of environments. In one example, the device may be used in an interior and may be fixed to a ceiling and the reception region may be at a distance from the transmitter that is determined by the dimensions of the room. A user in the environment can communicate with the transmitter by being present in an active tile of the tile pattern projected into the environment.

[0147] Figure 1(b) depicts the transmitter apparatus 10 provided at a ceiling and a user device 40 in the environment. The user device may be provided at a fixed static position or may be movable in the environment. A general direction of propagation 41 of light is indicated in Figure 1(b). The transmitter apparatus is configured to form a tile pattern at a distance 44 from the transmitter apparatus. At this distance the tile pattern is formed as a far field pattern and may be referred to as a pattern formation distance. The pattern formation distance can be determined, for example, using Equation (1) defined above.

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[0150] At distances smaller than the pattern formation distance (indicated by near region 42) the tile patterns are not formed. In the near region, there is a higher chance of saturating receivers due to the signal intensity. The pattern formation distance is generally larger than the separation between transmitters.

[0151] The region beyond the pattern formation distance 44 is referred to as the reception region 46. At distances greater than the pattern formation distance the beam pattern is maintained as the light propagates from the transmitter apparatus (towards the floor). There is also a limitation to the dimensions of the environment that may be caused by the pattern spreading over a large area such that the signal at any one point is too weak.

[0152] In embodiments, the maintenance of the beam pattern along the propagation direction can be considered to include an absence of degradation in at least one of a beam shape and / or tile separation and / or degree of overlap between tiles. In some embodiments, the maintenance along the propagation direction may include a maintenance of a tile shape and / or a distribution of the intensity across a tile. In embodiments, the beam pattern is substantially maintained or unmodified in that while each tile may grow in size, a separation or another property of the beam pattern is maintained as the beams propagate. In some embodiments a maintained tile pattern may comprise a plurality of tiles at a first distance from the optical device, each tile having a first size arranged in the tile pattern, for example, a grid and a plurality of tiles having a second, larger size, arranged in the same pattern.

[0153] The distances will vary depending on the transmitters used and other factors. However, as a non-limiting example, the pattern formation distance is ata distance between 20 cm and 1m (for example, 30 cm) from the transmitter apparatus with the reception area having a size spanning a distance from 3 to 5 metres from the transmitter apparatus. The beam pattern may be substantially maintained or unmodified along a propagation distance that has a size corresponding the reception area such that the pattern is substantially unmodified as it propagates through the reception area.

[0154] In accordance with embodiments, the size of each formed tile will depend on the distance from the transmitter apparatus. In terms of angular size, individual tiles may cover angles between, for example, 2 to 10 degrees, with a total field of illumination of the transmitters

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[0157] being between 10 to 60 degrees. The position of each tile in the grid is dependent on the divergence therefore if we have a 2 degree divergence we want to space the tiles on a 2 degree grid.

[0158] Figure 2 is a view of a transmitter apparatus 120 including an optical device 110 and plurality of transmitters 118 in accordance with an embodiment. In this embodiment, the optical device 110 has collimation optics comprising a plurality of collimating lenses 112, a steering device array 114 and a beam shaping optical component in the form of a homogeniser 116. It will be understood that the collimating lenses, steering device and beam shaping component correspond to the collimating, steering and shaping optical layers described in overview with reference to Figure 1.

[0159] In the embodiment of Figure 2, the plurality of light sources are formed by a VCSEL array. The VSCEL array, in this embodiment, is a 3x3 array. The VSCEL array 118 is configured to output a plurality of beams each having a degree of divergence corresponding to the field of propagation of the respective VSCEL. The field of propagation of a VSCEL is depicted in Figure 2 as field of propagation 120. Each field of propagation is substantially along a direction of propagation 122. In this embodiment, the direction of propagation is substantially normal to the plane in which the VSCEL array 118 lies and is, in general, in a direction of emission of light from the light source. The VSCEL array thus forms a substantially planar light emission surface. Together the VSCEL array produces beams in an initial beam pattern.

[0160] As described with reference to Figure 1, the optical device 110 is configured to receive a plurality of beams emitted from the VCSEL array in the initial beam pattern and transform the beams to form a beam pattern, also referred to as an exit beam pattern. Generally, beams produced by the VSCEL propagate away from the VSCEL array generally along the direction of propagation 122 and are modified as they pass through the optical device.

[0161] The optical device 110 has a layered structure in which the optical components of the different modules (in this embodiment, the collimation optics, the steering array and beam shaping optic) are provided as separate layers. The layers are oriented in a substantially parallel arrangement. The layers are oriented to have a width and length perpendicular to the direction of propagation such that light emitted from the plurality of

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[0164] light sources passes through each optical layer in sequence. The depth of each layer extends along the propagation direction. The orientation of the layers may be described as substantially parallel to the light emitting surface of the VSCEL array.

[0165] Parallel in this sense may be understood in some embodiments, that each optical layer lies in or defines a plane and the planes are parallel to one another. For example, in embodiments, an optical layer has a length, width and depth and the length and width extend along two orthogonal directions that define a plane of the optical layer. The planes defined by the optical layers are parallel and / or have a normal that are parallel to the propagation direction.

[0166] In accordance with embodiments, two or more parallel layers may be understood to be parallel within a tolerance. For example, a layer or part of a layer may be inclined within an acceptable tolerance. In some embodiments, optical layers may be substantially planar but have a variable depth. In some embodiments, an optical layer may be defined by one or more substantially flat surfaces of the layer.

[0167] In the present embodiment, each optical layer acts to modify the beam pattern of the light received at a first surface (closest to the transmitters) to produce a modified beam pattern exiting the optical device from the second surface (furthest from the transmitter).

[0168] In the embodiment of Figure 2, each VCSEL emits a corresponding beam having a field of propagation. The beam spreads or diverges as it is emitted from the VCSEL before being incident on the collimation optics. The beams produced by the VSCEL array are first received by the collimation optics. The collimation optics receive the beams and collimate each beam thus forming a corresponding number of collimated beams 124 in a collimated beam pattern. The collimated beams continue to propagate in the propagation direction 122 to the steering array 114.

[0169] In the present embodiment, the steering array has a number of surfaces, also referred to as facets corresponding to the number of beams. In the present embodiment, the steering array is a 3x3 array of facets. Depicted in Figure 2 are three surfaces: first facet 114a, second facet 114b and third facet 114c. A facet will be understood in the present embodiment as a small, planar or flat surface. The facets are configured to receive light

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[0172] propagating in a first direction and redirect or steer the light along a second, different direction.

[0173] In the present embodiment, the central facet (corresponding to second facet 114b) is parallel to the plane of the VSCEL array (the light emitting surface). As such, the central collimated beam 124b continues along the optical path without changing a direction of propagation. The propagation directions of the other collimated beams (for example, first and third collimated beams depicted in Figure 2) are modified by the corresponding facet of the faceted array. In Figure 2, the first facet 114a causes the first collimated beam 124a to be directed away from the propagation direction 122. In Figure 2, the third facet 114c causes the first collimated beam 124c to be directed away from the propagation direction 122. In some embodiments, non-inclined facets, such as the central facet may be omitted from the facet array.

[0174] Collectively, the field of propagation or size of the tile pattern of the plurality of beams can be considered to diverge as a result of the steering array. Collectively, the plurality of beams propagate within a first cone having a first spread or degree of divergence before being incident on the beam steering array. Each beam is separately steered by a corresponding facet of the steering array such that the steered beams continue to propagate in a second cone having a second, larger spread or second degree of divergence. The plurality of beams therefore have a greater degree of separation after interaction with the faceted array. Each facet has one or more surfaces inclined to steer a beam and separate a beam of light incident on said surface. The faceted array therefore receives a plurality of collimated beams and produces a plurality of separated beams.

[0175] The separated beams produced by the steering array continue to propagate substantially along their modified propagation direction towards the beam shaping element 116. The beam shaping element is configured to receive each redirected beam and shape said beams to form a corresponding plurality of reshaped beams. As part of the beam shaping, in accordance with embodiment, homogenisation of light can be considered as a type of beamshaping. For example, the beams may be homogenised and the beams are also reshaped to reshape the overall shape of intensity distribution. In the present embodiment, the beam shaping layer homogenised the beams to produce a plurality of homogenised beams.

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[0178] As a result of the steering and shaping optical layers, the collimated beam pattern is transformed to an exit beam pattern on exiting the final surface of the final optical layer. The exit beam pattern then continues to propagate in the propagation direction. The near field exit beam pattern evolves as the beams propagate through free space to form the tiled pattern as a far field radiation pattern.

[0179] The far field radiation propagates through a reception region and is substantially maintained in the propagation direction through the reception region. As the beams propagate, the tile pattern is maintained. In particular, the size, shape, separation and final position of the tiles are maintained for a minimum distance. By maintaining the tile pattern for a minimum distance along the propagation direction, the transmitter may be used to emit OWC signals into spaces of varying sizes, for example, installed in ceilings at different heights, without additional calibration being required.

[0180] Figure 3(a) illustrates the 3x3 VSCEL array in two dimensions, in accordance with an embodiment. For clarity, the top left VSCEL 302a and the centre VSCEL 302b are labelled. The 3x3 array is formed by identical addressable VCSELs. Each VCSEL is configured to produce a beam that is transformed by the optical device to form a tile at a desired distance such that the tiles form a tile pattern.

[0181] Figure 3(b) illustrates the tiled beam pattern formed by providing the VSCEL array and the optical device, in accordance with an embodiment. As can be seen in Figure 3(b), the tile pattern formed is a 3x3 grid of square tiles. The tile produced by each VCSEL has a position relative to the position of the VCSEL of the array.

[0182] As an example, the central VCSEL 302b produces the central tile of the tile pattern 304b, and the top left VCSEL 302a produces the top left tile 304a of the tile pattern.

[0183] Figure 4 depicts, in profile, a simulation of a transmitter apparatus, in accordance with an embodiment. In this embodiment, a 4x4 square tile pattern is produced by a corresponding 4x4 array of light sources (not shown).

[0184] As described with reference to Figure 2 and Figure 1, the optical device 410 of Figure 4 is formed by a number of optical layers. In this embodiment, the layers include a

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[0187] collimation layer comprising a microlens array 412, a beam shaping layer in the form of a single beam shaping optical element 416 and a beam steering layer 414 in the form of a single optical element. In contrast to Figure 2, the beam shaping element 416 is provided before the beam steering element 414.

[0188] In the embodiment of Figure 4, the beam steering layer is a spherical lens. It will be understood that beam steering can be achieved using different optical components or devices, such as a prismatic array, or blazed gratings. In the embodiment of Figure 4, the beam shaping layer is a diffuser. It will be understood that other beam shaping components may be provided.

[0189] As can be seen in Figure 4, each of the optical layers have a width and length perpendicular to the propagation direction of the beam. The width and length of each optical layer lie within or define a respective plane, and the planes are provided in a parallel arrangement.

[0190] In embodiments, each transmitter may comprise a plurality of light sources. In this embodiment, each transmitter of the 4x4 array is itself formed of four VCSELs connected in series. The transmitter lies in a surface and the optical layers are provided at predetermined distances and parallel to the surface.

[0191] Figure 5(a) and (b) depicts an example of the tiled output from a 3x3 array, for example, the array described with reference to Figure 2 above. The results are modelled in Zemax with separate collimation, steering and flat top homogenisation layers. Figure 5(a) depicts a beam pattern formed when all transmitters of the VSCEL array are switched on. Figure 5(b) depicts a pattern in which three of the transmitters of the VSCEL array are switched on.

[0192] The images will be understood as the pattern produced by the VSCEL array and optical device when projected onto a flat plane. The simulated results are therefore indicative of how the coverage would look when illuminating a room with an access point (for example, when installed at the ceiling).

[0193] In embodiments, the tiles may have a degree of overlap. This can be controlled by varying the degree of steering, collimation and / or spreading performed by the optical

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[0196] device. In Figure 5(a) and (b) the overlaps are controlled by modifying the beam shaping optical layer. For example, the steepness of the edges can be increased or decreased by changing the homogenising optic. In the example of Figure 5(a), the edges are steep. As shown in Figure 5(a) and Figure 5(b), the tiles experience distortion at higher steering angles (the periphery of the cone of propagation).

[0197] In accordance with embodiments, if the beam shaping optical layer is a single flat top homogeniser a distortion of the final tile shape may be observed. In some embodiments, a homogenising array may be provided having separate regions for homogenising light to different degrees to account for the distortion associated with projecting onto and angle plane.

[0198] Without limitation, such an optic may be designed as followed. As a first example, an iterative Fourier Transform algorithm may be used. In this example, a model diffuser optic is designed that provides the desired intensity pattern is calculated without high angle deflection. This is used as a target for an Iterative Fourier Transform Algorithm (IFTA). The IFTA iteratively pushes the far field towards target and calculates the near field phase that creates this target (Fourier T ransforms take you between the two, hence the name). The final near field phase is used to calculate the surface shape required, given a material of known refractive index. In some embodiments, the optic could take the form of a diffuser.

[0199] As a second example, an array of freeform micro optics may be used. For example, a lens array on a square grid will make a square shape tile. There will be a freeform optic comprises a non-rotationally symmetric aspherical lens which will create the required distorted tile shape. If made into an array, such an optic may work for any incoming beam shape. It will be understood that there may be many ways to calculate this surface, from pure ray tracing I intensity mapping to diffraction based calculations.

[0200] In accordance with embodiments, distortion of tiles in the reception area may be compensated. As an example, the optical device, specifically, the beam shaping optical layer may be configured to form a skewed shape tile at the exit pattern. The skewed tile may take into account the change in direction provided by the beam steering layer such that, while the near field pattern exiting the optical device is skewed, the far field pattern

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[0203] is the desired shape. Specifically, the effects of projecting the beam onto a plane in the reception region is compensated for to provide uniform tiles in the tile array.

[0204] There may be multiple limiting constraints on a maximum output power from a transmitter apparatus such as the array depicted in Figure 2. For example, these include, but are not limited to eye safety, thermal effects or commercial availability. The limit in output power may limit the maximum distance over which a desired link speed between two OWC devices can be maintained. The signal strength may decrease with an increasing link distance.

[0205] A total output power of a transmitter may be increased by including additional transmitters that are physically separated by relatively large distances. As an example, with regard to eye safety, transmitters may be separated by 7mm as this is the maximum diameter of a dilated human pupil. In embodiments, a minimum distance between peripheral transmitters is required for eye safety considerations, however, this may be dependent on the transmitter.

[0206] Figure 6(a) depicts an example VCSEL array with additional boosting transmitters that is compatible with the optical device described above. Figure 6(a) depicts a central 3x3 array of VCSELs. The central array is as described with reference to Figure 3. As described with reference to Figure 3, the central array has, for example, a top left VCSEL 602a and a centre VCSEL 602b. At the periphery of the central array, at each of the four corners, an additional booster VCSEL is provided. A first booster VSCEL 606 is labelled in Figure 6(a).

[0207] The peripheral transmitters may be the same type as the transmitters of the central array. The peripheral transmitters may be operated in response to a monitored property of the transmitted or received signal.

[0208] The optical device for the array of transmitters and peripheral transmitters may be as described with reference to the embodiments above, in which the optical device is configured to receive light from the central array. The optics can be designed in a way that these transmitters will cover any of the sub tiles , in this case they will all cover the central area.

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[0211] Figure 6(b) is an illustration of the central array and peripheral boosters. For the purposes of illustration, the tile pattern produced at a propagation distance from the central array and boosters is overlaid on Figure 6(b). It will be understood Figure 6(b) is viewed in the reception region at a distance from the optical device (not shown) with the propagation direction of the transmitters out of the page. As illustrated in Figure 6(a), the 3x3 central array produces a corresponding 3x3 tile array. For clarity the optical device is not shown in Figure 6(b).

[0212] The central tile 604b and the top left tile 604a are labelled. As illustrated in Figure 6(b), light originating from the top left transmitter 602a forms the top left tile 604a after passing through the optical device (not shown). Light originating from the central transmitter 602b forms the central tile 604b after passing through the optical device (not shown). It will be understood that, in this embodiment, each transmitter forms a corresponding tile.

[0213] In this embodiment, the peripheral transmitters (for example 606) are spatially aligned with the tiled pattern such that they contribute to part of the central tile without steering or at least a smaller degree of steering.

[0214] In accordance with embodiment, light from the peripheral boosters may pass through one or more layers of the optical device, for example, as shown in Figure 7, the light beams from the peripheral light sources are collimated and beam shaped by the collimation and beam shaping layers. The peripheral transmitters can therefore boost light intensity and / or signal strength at the central tile. In the present embodiment, beams from the peripheral transmitters are steered to the same degree as beams from the central transmitter. As such, beams from the peripheral transmitters have the same angular output after the optical device and so will overlap in the far field. In theory, the far field is formed after an infinite propagation, but in practical applications, the far field is formed at a distance that is large relative to the separation of the transmitters.

[0215] In a further embodiment, peripheral transmitters may be configured to boost light intensity and / or signal strength of other selected tiles of the tile pattern. In such embodiments, the optical device is configured to steer the beams from the peripheral transmitters to the same degree as the beam forming the boosted tile. As an example, to boost a corner tile, the optical device is configured to steer the beam from the peripheral transmitter(s) to the same degree as the beam from the corner transmitter.

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[0218] Such an application may be of use when additional speed / signal is required in a corner of a room or other environment.

[0219] Figure 7 depicts, in profile, simulated optics including a peripheral transmitter. The optical device of Figure 7 has a collimation layer in the form of a microlens array 712. The optical device of Figure 7 has a beam shaper layer, in this embodiment, a non-imaging homogeniser (a micro-lens array). The optical device of Figure 7 also has a steering layer 714 formed by a plurality of inclined wedges. The steering layer may also be formed by a plurality of prisms.

[0220] Figure 7 also depicts light emitted by a 3x3 transmitter array (not shown). As Figure 7 is depicted in profile, only light beams transmitted by three transmitters of the 3x3 array are depicted. This includes first light beam 730a, second light beam 730b and third light beam 730c. The light from the 3x3 light source array is collimated, shaped and steered, as described with reference to Figure 2 to form a tile pattern.

[0221] In addition to the 3x3 light source array, peripheral transmitters are provided. A light beam 732 from a single peripheral transmitter is depicted in Figure 7. Similar to the light from the central light source array, the light from the peripheral transmitter is incident on the collimating layer 712 then the beam shaper layer 716 and collimated and shaped by those layers respectively. However, the light from the peripheral transmitters 732 bypass the steering layer. In this embodiment, the size of the beam steering layer matches the cone of light originating from the central array. The light beams outside this cone are therefore not incident on the steering device and are not steered by the steering layer.

[0222] In further detail, light emitted by peripheral transmitter 732 propagates from peripheral transmitter to the collimation layer 712, in the propagation direction. The light emitted by the peripheral transmitter is collimated by collimation layer 712 then subsequently shaped by the beam-shaping layer 716 to form collimated and shaped light. The collimated and shaped light continues to propagate substantially along the propagation direction.

[0223] The tile pattern produced by the arrangement of Figure 7 is therefore a combined pattern formed by the tile pattern produced by the 3x3 light source array and optical device combined with the collimated and shaped light produced by the peripheral transmitters

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[0226] and optical device. As such, the combined tiled pattern includes a combination of steered and un-steered light.

[0227] In the far field beams transmitted by the peripheral transmitter will overlap with the signal from the central transmitter. All the other optics in front of the booster VCSELs are the same as the central transmitter so these will be shaped into a uniform square as with all the other sub cells.

[0228] The overlap between light produced by the peripheral transmitters is dependent on the separation of the peripheral transmitters. In embodiments, with a large separation between peripheral transmitters, the area uniformly covered by the peripheral transmitters can be smaller than the area with uniform coverage with a single VCSEL,. The patterns from each transmitter have not yet fully overlapped, in theory this happens after an infinitely long propagation but overlap at a certain plane can be increased by spacing the VCSELs closer together. Therefore there may be a trade-off between the spacing of the VCSELs and the boosted irradiance pattern.

[0229] The peripheral transmitters may be sufficiently separated so that the total output power is greater than that allowed from a single transmitter. A large enough separation is required so that the individual beams stay separate until they have propagated and spread out enough that the combination of beams meets eye safety requirements. It may also provide a more energy efficient system. Grid of beams may be more efficient because it does not cover the entire addressable area, in this case efficiency is may be further increased as boosters can be turned off at shorter distances where the high power levels are not needed. In addition, there may not be saturation at short distances as boosters are turned off.

[0230] In the above described embodiment, the transmitter booster is described at the periphery of the array and is described as contributing to a central tile. However, it will be understood that boosters may be provided at other points relative to the array and may create bespoke areas with higher data rates than other areas within a room or environment.

[0231] Figure 8(a) and (b) are simulation results in accordance with an embodiment. Figure 8(a) depicts irradiance in the central square at 3m link distance. There is only one transmitter

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[0234] illuminating this area. Figure 8(a) shows the irradiance after 3m propagation with only the central VCSEL active. Note the maximum irradiance is just above 2 W / m2. Figure 8(a) depicts a square tile of high irradiance 802a surrounded by a region of low irradiance 804a. In Figure 8(a), a thin, well defined boundary region 806a having an intermediate value of irradiance is formed at the edge of the tile.

[0235] Figure 8(b) depicts the irradiance pattern when all 4 boosters are activated, in this case the maximum irradiance is now 10.4 W / m2. Figure 8(b) depicts a square tile of high irradiance 802b surrounded by a region of low irradiance 804b. In Figure 8(a), a boundary region 806b having an intermediate value of irradiance is formed at the edge of the tile. Figure 8(b) depicts irradiance in the central square at 3m link distance. In this example, there are five transmitters illuminating this area, the original transmitter and four additional boosters. Each transmitter is the same type of VCSEL (multiple transmitters of the same array).

[0236] In this model the boosters are separated by 40mm. The separation of the peripheral transmitters has a direct impact on the fields of view overlap with the original tile pattern. A larger separation means a longer propagation distance is required to fully overlap so the edge area (5 W / m2) of intermediate irradiance will be larger. To decrease this and have a larger higher irradiance area, the peripheral transmitter spacing can be reduced.

[0237] Figures 9(a) and 9(b) depict a first and second exploded view of an optical device and a light source array in accordance with an embodiment. In this embodiment, the light source array 1120 is provided as part of a base layer 1120. As can be seen in Figure 9(a) and (b), the light source array 1120 is a 3x3 light source array. The base layer has a finned structure to aid in thermal dissipation. It can be seen that Figures 9(a) and 9(b) depict a transmitter device provided in accordance with a stacked or layered arrangement, in which optical layers are stacked to form the OWC transmitter.

[0238] The optical device has a number of layers. In this embodiment, the optical device has a collimation layer 1112, a beam shaping layer 1116 and a beam steering layer 1114.

[0239] The collimation layer 1112 is a lens array which is provided as a single monolithic part with mounting holes. In this embodiment, only the upper portion of the lens protrusions are visible, to aid with polishing, strength and stability. In some embodiments, a further

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[0242] spacer layer may be provided to space the lenses from the VSCEL layer. In some embodiments, the lens array has a portion or structural element to provide spacing between the lens array and adjacent layers of the device. A single part with mounting holes and only the tops of the domes showing to help with polishing, part strength and stability. In this embodiment, the collimation layer has a first flat surface closest to the transmitters and a second non-flat surface.

[0243] The beam steering layer 1114 is formed by steering optics 1114a seated in a frame 1114b. The frame has nine apertures. The frame has spacing portions in the form of legs to provide spacing between the lens array / shaping layer and the beam steering optics. In this embodiment, the spacer layer has four legs. In this embodiment, the beam steering layer has a first flat surface closest to the transmitters and a second, opposing surface that is non-flat surface.

[0244] The beam shaping layer 1116 is a single monolithic piece with mounting holes. The holes may help to reduce cost, aid assembly and reduce alignment requirements. In this embodiment, the beam shaping layer 1116 is a diffuser. In this embodiment, the diffuser layer has a first flat surface closest to the transmitters and a second opposing flat surface.

[0245] In the present embodiment, the layers are secured together by a number of securing bolts. Corresponding holes are provided in the base layer, collimation layer, diffuser layer and spacer layers. An additional frame or structure may also be provided, for example, to align the facets of the steering layer in with the 3x3 array.

[0246] The stacked arrangement of Figure 9(a) and 9(b) may reduce for the need for off-axis or angular alignment. In particular, as the optical layers are assembled as layers in the stacked arrangement and no angular alignment is required.

[0247] Figure 9(c) depicts the one-piece lens array of the collimation layer in further detail. It can be seen that the one-piece lens array has a translational symmetry and is formed by a 3x3 array of lenslets.

[0248] Figures 9(a) and 9(b) illustrate an embodiment in which the optical device is formed by optical components that form or are arranged in parallel optical layers. In this embodiment, each of the collimation layer 1112, beam shaping layer 1116 and beam

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[0251] steering layer can be considered to be substantially planar and to lie in or define parallel planes. As an example, beam steering layer 1114 has a width and length (that are equal in this embodiment) defining two directions that define a plane in which the layer lies. As with the collimation layer 1112, the depth of the layer varies but the depth extension is smaller than the extension in the width and length directions.

[0252] Figures 10, 11 and 12 depict simulated results. Figure 10(a) depicts simulated coverage in a reception region at 1 metre in which each individual transmitter produces a tile having a size 12cm x 12 cm. Figure 10(b) depicts simulated coverage at 2 metres in which each individual transmitter produces a tile having a size 20cm x 20 cm.

[0253] Figure 11 depicts simulated coverage in a reception region at 2 metres in which a tile pattern is clearly formed by activating all transmitters.

[0254] Figure 12(a) depicts simulated coverage at 2 metre in which only a single transmitter is active. Figure 12(b) depicts coverage at 2 metre in which only a single transmitter is active to form a different tile. The design of Figure 12 is a high coverage area design in which wide angle illumination optics are used. The beams are being projected at high angles and being distorted at the reception region. The path length to the edge of the overall square coverage area is therefore sqrt(2) longer than to the centre so the light has a longer distance to spread out. To address this issue, the beam shaping optical layer may have beam shaping portions for each individual transmitter which compensates for the distortion.

[0255] Using a lens-array it is possible to create desired tile shapes as far field radiation patterns. A problem may occur at the transition between lenslets at a discontinuous or sharp interface, which may not be polished. As described in the following, if the curvature of the lenses is alternated but the magnitude of the radius of curvature is maintained then the overall slope content is the same. The light is deflected to the same place overall, but the sharp transitions may be eliminated. In the above described embodiments, the beam shaping function of the optical device is provided by an optical layer comprising a single optical component in the form of a flat-top homogeniser.

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[0258] In a further embodiment, the beam shaping device is formed of two optical components, specifically two optical arrays that co-operate to shape and / or control the size of the resulting beam in the far field. The optical arrays may have undulating surfaces.

[0259] The optical arrays, in accordance with embodiments, can be considered to be formed of a continuous surface formed by a repeated array of alternating maxima and minima.

[0260] As described in the following, two optical components can be provided as part of the beam steering optical layer. The optical components can co-operate to achieve a desired effect. Figure 13 depicts the heights of part of an example embodiment of one of a pair of co-operating components. In this embodiment, the array is formed by a repeated unit cell formed of a first outward cylindrical protrusion 1302 and a second inward cylindrical protrusion 1302. The cylindrical protrusions extend along a length of the optical element. Figure 13 depicts the heights of the protrusion.

[0261] The optical array has alternating cylindrical lenses. In both embodiments, the outward protrusions and inward depressions may be referred to, for brevity, as lenses, and the operation of both embodiments is described with reference to the one dimensional illustration of Figure 14 and 15.

[0262] Figure 14 depicts an illustration of one of the two co-operating optical components. The optical component is formed by a unit cell having a first outward protrusion and a second inward depression. The first protrusion is referred to as a first lens 904 (or lens portion) and has a first curvature and the second depression is referred to as a second lens 906 (or lens portion) having a second curvature. In this embodiment, the second curvature is equal and opposite to the first curvature. The optical component has a flat surface opposing the curved surface. The protrusions may form a ridge like structure.

[0263] In accordance with embodiments, beam shaping of a beam can be controlled by controlling the relative position between the two optical components. In Figure 15(a) and 15(b), a first optical component 902a and a second optical component 902b are arranged such that their flat surfaces are parallel. The optical components are configured to move laterally relative to each other and a mechanism is provided to obtain lateral movement, in accordance with embodiments. This movement is such that the corresponding, facing surfaces remain parallel but their curved surfaces are moveable relative to each other.

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[0266] As such, optical effects from the optical components may be combined for beams incident on the beam shaping device from either a lower or upper direction.

[0267] Figure 15(a) depicts a first configuration for the two optical components 902a, 902b and Figure 15(b) depicts a second configuration. In both the first and second configuration, a lens or protrusion of the first lens arrays is aligned with a corresponding lens or protrusion of the second array. To aid with the description of Figure 15(a) and (b), a direction of propagation is defined as indicated by arrow 1502, however, it will be understood that the two components can be configured to receive light in an opposing or at an inclined direction of propagation.

[0268] Relative to the direction of propagation, the first and second optical components can be referred to as forward and rearward components. Their respective lenses can also be defined in terms of the direction of propagation. In this embodiment, the positive curvature lenses of the forward optical component 902a protrude in the forward direction and therefore can be referred to as forward lenses. Likewise, the negative curvature lenses can be considered to be concave and can be referred to as rearward lenses. On the contrary, as the rearward optical component is facing an opposing direction, the positive curvature lens of the rearward optical component 902b protrude in the rearward direction and therefore can be referred to as backward lenses. Likewise, the negative curvature lenses can be considered to be concave and can be referred to as forward lenses 902b. The distance between adjacent unit cells or adjacent lenses of the same type may be referred to as the pitch. The pitch 905 is indicated in Figure 14. For purposes of illustration a first forward lens 904a and a backward lens 606a of the first optical component 902a and a first forward lens 904a and a second forward lens 906b of the second optical component 902a are depicted in Figure 15(a) and 15(b).

[0269] In the first configuration of Figure 15(a), optical components are aligned such that their corresponding forward lenses of the forward and rearward optical components are aligned. As such, the backward lenses of the forward and rearward optical components are also aligned. In the second configuration of Figure 15(b), the lens arrays are aligned such that the forward lenses of the forward optical component and the backward lenses of the rearward optical array are aligned. As such, the backward lenses of the forward optical component and the rearward lenses of the rearward optical component are aligned.

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[0272] It will be understood that by controlling the relative lateral position of a lens array relative to a second lens array, the shape and / or size of the beam of the tile pattern can be modified. The lateral position can be characterised by a lateral offset 908, indicated in Figure 15(a). Without limitation, this may be defined as the lateral distance between a forward lens of the first array and a forward lens of the second array or by a lateral distance between a starting point of the unit cell of the first array and a starting point of the unit cell of the second array. Any suitable reference may be used. In Figure 15(b), the lateral offset is defined as the lateral distance between a maximum of the first cylindrical protrusions of the first component and the maximum of the first cylindrical protrusion of the second component. In the first configuration, the lateral offset is zero, as the forward lenses of the respective arrays are aligned. In the second configuration the lateral offset is half the pitch of the lens array such that the forward lens of the first array is aligned with the backward lens of the second array. It will be understood that, in the present embodiment, the lateral offset can range between a minimum value of 0 and a maximum value equal to the pitch of the optical component.

[0273] In the first configuration, substantially no beam shaping occurs as the forward optical component cancels any phase change from the rearward optical component. The first optical component provides a first contribution to beam shaping and the second optical component provided a second contribution to beam shaping. In the first configuration, the first and second contributions cancel. In the second configuration, the first and second contributions are additive such that light passing through the device experiences a first phase change from the first component and a second, equal phase change from the second component.

[0274] The first and second configurations offer the maximum and minimal beam shaping possible by the device. By varying the lateral offset between the components, other beam shaping effects can be obtained. A suitable mechanism may be provided for controlling the lateral offset.

[0275] Figure 16 depicts part of a beam shaping device, in accordance with an embodiment. Figure 16 depicts the optical component from a first perspective (left hand side) that shows a first surface 1602a of the optical component and Figure 16 depicts the same optical component from a second perspective (right hand side) showing the opposing

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[0278] surface 1602b of the optical component. The optical layer is a freeform optic having two surfaces: a first surface 1602a having a plurality of parallel protrusions extending in a first direction and a second, opposing surface 1602b, having a plurality of protrusions extending in a second direction that is orthogonal to the first direction. The first direction 1604 and second direction 1606 are indicated in Figure 16.

[0279] As can be seen in Figure 16, on the first surface 1602a the cylindrical protrusions extend along a length of the array in the first direction 1604. On the second surface 1602b the cylindrical protrusions extend along a width of the array in the second direction 1606. The cylindrical protrusions are formed in a single continuous surface. The surface will be understood to be continuous such that, for example, traversing along the first surface in the second direction is smooth and continuous and corresponds to the undulating surface shown in Figure 14.

[0280] The two surfaces of the optical component contribute to a phase change for light to produce a square tile. As such the optical layer with undulating surfaces can be used alone to form the desired tile shape. In addition, in accordance with embodiments, two optical layers can be provided and moved relative to each other to provide a variable spot size.

[0281] Figure 16 depicts cylindrical protrusions formed on opposing surfaces of an optical component. In an alternative embodiment, the features of the opposing surfaces may be combined on a single surface. Such an embodiment is described with reference to Figure 17.

[0282] Figure 17 depicts a regular array in accordance with another embodiment. In Figure 17, a single surface of the optical element is formed by combining a first array of cylindrical protrusions with a second array of cylindrical protrusions in which the first array is orthogonal to the second array. In Figure 17 the first array is aligned in a horizontal direction 1708 and the second array is aligned in a vertical direction 1710. This combination produces an undulating surface having a varying depth. The surface is continuous at all points i.e. traversing the distance along any path is continuous.

[0283] A unit cell 1702 is indicated in the figure. The depth of the surface is indicated in Figure 17. By combining the two cylindrical arrays as a single surface, the unit cell 1702 has a

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[0286] concave portion 1704 and a convex portions 1706. The unit cell also has two transition portions (1703a, 1703b). The curvature on the concave and convex portions have the same magnitude but different directions of radius of curvature. Between the concave and convex portion of each unit cell and between corresponding portions of adjacent unit cell is a continuous surface. The transition portions may be understood as saddle points between adjacent maxima and / or minima. In the present embodiment, the unit cell is formed by a maxima, a minima and two saddle points.

[0287] As described above, if two of these optical arrays are aligned so that the convex portions are aligned with the convex portions, the overall phase shift introduced in a collimated beam is zero. However, if the convex portions are aligned with the corresponding convex portions, a phase shift is maximised to form a desired square tiled in the far field. The spot size created at the far field is proportional to the magnitude of the phase change introduced at the beam shaping optical layer, so by moving one relative to the other the coverage area may be varied and / or controlled.

[0288] It will be understood that the algorithm for controlling transmission of beams may depend on the area of coverage of each tile. The movable pair of layers may be used in conjunction with a beam selection or handover algorithm. The variable beam shaping may be best with thinner lenses, as such it is expected that this approach will be particularly effective when used with metalenses. In a similar manner the collimation optics may also be used to optimise handover. As an example, by moving the lenses closer or further from the VCSELs the effectiveness of the collimation can be changed. This directly affects the steepness of our shaped beam, the rate of change of the intensity from zero to the central plateau value. Again, this may be to manipulate how our cells overlap and to optimise beam selection and handover. By mounting the collimation lenses with actuators to move them closer or further to the PCB, this control is provided. A set of actuators may be moving in an orthogonal direction to those controlling the displacement of the two freeform optics.

[0289] Without limitation, some preliminary modelling results obtained for the variable beam shaping device are provided in Figures 19(a) to (d). In these results, a perfectly collimated beam is incident upon the pair of beamshaper components, and the illumination at 2m. The beam shapers are moved laterally relative to each other to

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[0292] confirm that the optics can cancel beam shaping, as predicted. The optics are then shifted by smaller amounts to check the tuenability of the coverage.

[0293] Figure 19(a) depicts a first modelled simulation result in which a maximum tile size is obtained. In this Figure, the two optical components are in a configuration in which both optical components contribute to a maximum phase shift on incident light. In Figure 19(b) the two optical components are in a configuration in which the phase shift of the first optical component substantially cancels the phase shift of the second optical component to produce a minimum tile size. It will be understood that intermediate configurations are also possible in which the tile that is formed is between the minimum and maximum values. For example, Figure 19(c) depicts a half-way result in which the formed tile is half the size of the maximum size and Figure 19(d) depicts a 10% reduction from the maximum tile size.

[0294] In accordance with embodiments, the optical device may have a first mechanism for moving the co-operating optical layers laterally to each other. The optical device may have a second mechanism for moving the collimation layer in a propagation direction.

[0295] In some embodiments, the tile pattern may have a high degree of overlap. Figure 18(a) and (b) depicts two tiles. The edges of the tiles correspond to a gradual reduction in link speeds. By controlling the overlap, a continuous coverage area may be defined to allow for handover between transmitters for a user moving in the coverage area. In some situations, overlap may be avoided completely, for example, for security reasons or privacy.

[0296] In the above described embodiments, a variable beam shaping device is described that has two moveable components where the size, optionally the shape, of the produced tile is dependent on the relative position of the two optical components. An overlap between tiles may be controlled by changing the positioning of the optical components. The variable beam shaping device is operable to be moved between a first configuration and a second configuration by a translational movement, namely by varying the lateral position. In further embodiments, optical components may be used in which the phase shift contribution of each optical component is modified by rotational movement such that the size and shape of the formed tile is modified by a relative rotation of the two optical components.

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[0299] The optical components of the variable beam shaping device may have a regular array of cylindrical or spherical portions. In further embodiments, the optical component may comprise a regular array of aspherical portions.

[0300] In the above described embodiments, a variable beam shaping device is described as part of a transmitter apparatus configured to produce a grid of beams, to control the size and / or shape of the produced beams, for example, to control a size of overlap between tiles. The variable beam shaping device may also be used to control between beams formed by two or more networked Access Points (AP). For example, in a large interior environments, multiple access points may be provided in the ceiling to provided signal coverage across the entire room. For example, each access point may provide one or more reception zone in the room the size of which is dependent on the beam formed by the access point. Overlap in the reception zones of the access points may cause crosstalk between signals. The variable beam shaper may be used to control shape and size of the beam for each access point and therefore allow for control of overlap between different access points.

[0301] A transmitter apparatus may communicate with an OWC receiver apparatus. The transmitter apparatus may be or comprise a transmitter device as described above. The transmitter apparatus may be configured to send OWC signals in which information is encoded through an optical communication channel to a receiver apparatus. The transmitter will be understood to have additional components, such as driving circuitry, configured to drive the light emitting device to generate light representing data. The optical communication channel may be a free-space communication channel. The optical communication channel may have a characteristic wavelength. Free space communication channels include transmission of optical signals through air, space, vacuum, liquid such as water or similar.

[0302] Transmitters and receivers may be provided on the same devices. The receiver may form part of a remote device that may provide access to a further network, for example the internet. In some embodiments the transmitter apparatus may form part of a transceiver or may form part of an Access Point device. Data connectivity may be via network connection, wireless connection, PLC connection, PoE connection OWC connection or other known data connections. The transmitter and / or receiver may be

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[0305] provided as part of a portable or fixed device. Without limitation, examples of remote device include personal computers, desktops, laptops and smart devices, including mobile devices (for example, mobile phones, tablets or digital book readers). The remote device may be powered by its own battery resource.

[0306] An OWC device may provide data transmission to and / or from a wired network or a WiFi or other wireless network and / or other optical wireless communications network, optionally a Li Fi network. Any suitable modulation scheme may be used. For example, orthogonal frequency division multiplexing (OFDM) modulation schemes are used in some embodiments, and the demodulation uses the OFDM demodulation scheme. In further embodiments and without limitation, other modulation schemes may be used, for example on-off keying (00K), phase shift keying (PSK), M-ary pulse amplitude modulation (M-PAM), M-ary quadrature amplitude modulation (M-QAM), Discrete Hartley transformation, Wavelet packet division multiplexing (WPDM), Hadamard coded modulation (HOM), pulse-position modulation (PPM), Colour shift keying (CSK), carrierless amplitude and phase (CAP), or discrete multi-tone (DMT). The light may be modulated at a modulation rate between 1 kHz and 1 PHz, for example at a modulation rate between 1 MHz and 100 GHz. The modulation scheme may form part of an OWC communication protocol, such that the optical signal is produced according to the OWC communication protocol. The OWC communication protocol may be packet-based.

[0307] Figure 20(a) depict a transmitter apparatus 2002 in accordance with an embodiment and Figure 20(b) depicts a receiver apparatus 2004 in accordance with an embodiment. As depicted in Figure 20(a), a tile pattern 2006 is formed by the transmitters and an optical device as described above. In this embodiment, a 4x4 pattern is formed that provided a corresponding 4x4 array of reception zones in the environment. The tile pattern forms a part of a downlink between the transmitter apparatus and one or more devices present in the tile pattern formed in the environment.

[0308] In Figure 19(b), a receiver apparatus 2004 having a plurality of receivers is depicted. In the present embodiment, a receiver is provided for each tile formed by the transmitter apparatus. The number of receivers therefore matches the tiles formed. The tile pattern 2006 formed by the transmitter apparatus is depicted in Figure 19(b).

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[0311] It will be understood that the transmitter apparatus and receiver apparatus may be combined as a single transceiver apparatus or may be provided separately, for example, at separate physical locations within the environment.

[0312] Each receiver of the receiver apparatus has an initial field of view. As the receivers are provided in a planar array, in the present embodiment, on a single circuit board, the initial fields of view of the receivers are substantially parallel (i.e. have directions of propagation that are parallel).

[0313] The receiver apparatus has corresponding receiver optics (provided as separate optical components or as one or more optical layers) that are configured to match the receivers to the tile pattern formed by a corresponding transmitter apparatus. Specifically, the reception optical components transform the initial field of view to a transformed field of view having, for example, a different angular size and, importantly angle or orientation. In the present embodiment, the reception optical components receive optical beams carrying OWC signals from a plurality of directions and steer the optical beams to be substantially parallel. The substantially parallel beams are then incident on the receiver array.

[0314] As can be seen in Figure 19(b) each receiver has a corresponding transformed field of view matching the receiver to the tile pattern. For example, a first transformed field of view 2008a for a first receiver is depicted. Figure 19(b) depicts an OWC signal 2010 emitted by a device and received by said receiver. As such, OWC signals transmitted by devices in each tile (or a zone in an environment that corresponds to a tile) can be received by a dedicated receiver.

[0315] In operation, an algorithm to control active receivers may be implemented based on the tiles that have been enabled. As an example, for a device in a corner tile, the other 15 receivers cannot receive the signal from the user in the corner, they only contribute noise and worsen the link. The apparatus may therefore be configured to enabled receivers based on active tile. In addition, multiple users in different locations may be supported without sharing the same transmission and reception channels.

[0316] It will be understood that the reception optics may transform fields of view using a number of different optical arrangements. An example embodiment is depicted in Figure 21. In

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[0319] Figure 21, a single optical component in the form of an optical layer is provided parallel to a surface on which the receivers are provided (in this embodiment, a printed circuit board) and has a plurality of steering and focusing portions. In the present embodiment, these optical portions are provided for each receiver. Light from different angles (i.e. originating from the zones defined by the tile pattern) are incident on the optical layer and are steered and focussed by the optical layer to the plurality of receivers. A further lens array (comprising lenses for each receiver) focusses the light from the optical layer for each receiver. A tilt effect for the field of view is obtained.

[0320] In the embodiment of Figure 21, an optical layer 2100 is provided. Figure 21 also depicts the plurality of receivers 2112a, 2112b. Each receiver2112a, 2112b has a corresponding lens that may be provided as part of a lens array. The optical layer 2100 is an optical component that has an upper (entrance) surface 2102 and a lower (exit surface) 2104. Each of the surfaces has optical structures or features formed thereon to provide steering and / or focusing of incoming light. In the present embodiment, the upper surface 2102 has a plurality of protrusions (for example, 2103a, 2103b) formed on the upper surface. The protrusions provide different degrees of steering to rays making up an incoming beam. In particular, rays at an outer position are steered to a greater degree by the protrusion than rays at an inner position. By offering a varying degree of steering across the beam, the direction of an incoming beam having a width can be steered towards the exit surface.

[0321] In the present embodiment, the exit surface 2104 has a number of optical structures or features, in the form of depressions 2105a, 2105b. The depressions are shaped to further steer and / or focus a beam as the beam exits the optical component. The combination of focussing and steering of the upper and lower surfaces results parallel beams being incident on the plurality of receivers.

[0322] It will be understood that the optical component may be matched to a desired tiled pattern of the transmitter apparatus. In some embodiment, the optical component may be swappable to change the degree of transformation applied to the incoming beams.

[0323] In use, an incoming beam 2106, originating from a device present in a zone in the environment (corresponding to a tile) is incident on the upper surface 2102. The incoming beam is steered and focussed to a first degree by the protrusion 2103a to form

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[0326] intermediate beam 2108. The intermediate beam propagates through the optic, and is transformed to a second degree by the depression 2105a on the lower surface 2104, to form the exit beam 2110. The exit beam 2110 continues to propagate towards the receiver 2112. In this embodiment, the exit beam 2110 is incident on a lens 2114 provided above the receiver. The lens 2114 focusses and collected the exit beam for the receiver.

[0327] In an alternative embodiment, a lens array is provided that is offset with respect to the array of receivers. The spot will move across the receiver as the user moves within the field of view of the receiver, and will eventually move to a point beyond the edge of the receiver. The lens array may be formed so that the light falls onto another of the diodes, due to alignment of the field of view of each. For example, as a user moves from one tile to another, the optics are configured so that light moves from one receiver to another.

[0328] As set out above, there are a number of methods of obtaining a transformed or tilted field of view without tilting the PCB of the receivers. For example, in apparatuses with compound parabolic concentrators (CPCs), the field of view may be tilted / by adding an offset lens, or Fresnel lens, to an entrance surface. In further example, reflective, refractive or diffractive features may also be added to the entrance surface (upper surface in Figure 21). Reflective features may also be added to the exit surface (lower surface). For example, lenses, off axis reflectors, asymmetric CPC’s may be used.

[0329] The optical component and layers describes above may be formed from any suitable optical materials. For example, suitable materials include, for example, PMMA, polycarbonate or any suitable at least partially transparent material may be used, such as glass, plastic. Suitable glass can include flint and / or crown.

[0330] In embodiments described above a tiled pattern is described that is maintained and / or unmodified as the beams propagate through a reception region. It will be understood that at least one property of the tile pattern may be maintained and / or unmodified as the beams propagated through at least part of the reception region. In some embodiments, at least one property of the tiled pattern may be maintained as the size and / or coverage area of the tiled pattern increases in size. In some embodiments, a degradation in one or more properties of the tile pattern may be within a tolerance while allowing sufficient signal to reach a device within the reception region.

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[0333] In accordance with embodiments, the device may have a substantially flat optical design with parallel layers. Such a design may avoid the need for mechanical tilt for one or more components. In addition, in embodiments, the modular design may allow each layer to have a function.

[0334] A skilled person will appreciate that variations of the described embodiments are possible without departing from the invention. Accordingly, the above description of specific embodiments is provided by way of example only and not for the purposes of limitation. It will be clear to the skilled person that modifications may be made to the embodiments without departing from the scope of \the invention.

[0335] 55759840-1

Claims

M&C PE963133GB43CLAIMS1. A transmitter apparatus comprising:a plurality of optical wireless communication (OWC) transmitters arranged and configured to transmit OWC signals in an initial beam pattern, wherein the plurality of transmitters are provided in a planar light emitting surface;an optical device configured to transform the initial beam pattern to a beam pattern in a reception region at a distance from the optical device wherein the optical device is configured to form a tiled beam pattern, wherein the tiled beam pattern is a far field pattern and / or wherein the tiled beam pattern and / or at least one property of the tiled beam pattern is substantially maintained and / or unmodified along a propagation direction in the reception region,wherein the optical device comprises one or more optical components corresponding to or arranged as one or more optical layers, wherein each optical layer of the one or more optical layers is configured to modify one or more properties of light beams transmitted from the plurality of transmitters to form the tiled beam pattern in the reception region, wherein each optical layer lies substantially in and / or defines a plane that is substantially parallel to the planar light emitting surface.

2. The apparatus of any preceding claim, wherein the one or more properties modified by the one or more optical layers comprise one or more of: a beam divergence, a beam direction and a beam shape.

3. The apparatus off claim 1 or 2 wherein the one or more optical layers together act to modify the beam divergence, beam direction and beam shape properties to form the tiled beam pattern in the reception region.

4. The apparatus of any preceding claim, wherein one or more of the optical layers is moveable relative to the transmitters to control one or more properties of the tiled beam pattern.

5. The apparatus as claimed in any preceding claim, wherein the one or more optical layers comprises at least one beam collimation layer, at least one beam steering layer and at least one beam shaping layer and / or wherein the plurality of layers comprise55759840-1M&C PE963133GB44an optical layer configured to perform at least two of collimation, beam shaping and beam steering.

6. The apparatus as claimed in any preceding claim, wherein the one or more optical layers comprise a plurality of optical layers arranged in a stacked arrangement, optionally wherein the stacked arrangement comprises one or more spacing layers between adjacent optical layers.

7. The apparatus as claimed in any preceding claim, wherein the plurality of planes are in a parallel arrangement and / or wherein each plane is at a fixed distance from the light surface.

8. The apparatus as claimed in any preceding claim, wherein one or more of the optical layers comprises a monolithic and / or one-piece construction and / or freeform optic.

9. The apparatus as claimed in any preceding claim, wherein the optical device comprises a modular structure wherein one or more of the optical components, optionally optical layers, is interchangeable by a further optical component or layer to change at least one property of the tiled beam pattern10. The apparatus as claimed in any preceding claim, wherein the optical device, optionally an optical layer of the optical device, is configured to limit a degree of spread of each beam from a respective transmitter in dependence on a corresponding degree of beam steering provided by the optical device, optionally a further optical layer, to prevent and / or at least limit overlap between adjacent tiles in the reception region11. The apparatus as claimed in any preceding claim, wherein the optical device comprises a homogenising and / or beam shaping device, optionally configured to shape light to form a tile having a substantially uniform or flat-top distribution, further optionally at the reception region.

12. The apparatus of claim 11, wherein the homogenising and / or beam shaping device comprises a diffuser, a lens array or a freeform optic and / or metalens optic.55759840-1M&C PE963133GB4513. The apparatus of any of claims 11 to 12, wherein the homogenising and / or beam shaping device comprises at least one shared, optionally planar, optical component and / or surface, wherein the at least one shared optical component and / or surface is shared between at least some of the transmitters forming the tiled pattern.

14. The apparatus of any of claims 11 to 13, wherein the beam shaping layer comprises a single, optionally two monolithic optical components.

15. The apparatus of any preceding claim, wherein at least one of the optical layers comprises a plurality of inclined surfaces arranged to lie substantially in a single plane, optionally wherein each inclined surface intersects said plane and / or a non-inclined opposing surface of each inclined surface lies in said plane, wherein each inclined surface is configured to receive at least one light beam propagating along a first optical axis and redirect said at least one light beam along a second optical axis, optionally wherein the plurality of inclined surfaces comprises an array of inclined surfaces spatially aligned with a corresponding array of transmitters.

16. The apparatus of any preceding claim, wherein the plurality of inclined surfaces form part of a multi-faceted optical element and / or a lens.

17. The apparatus of any preceding claim, wherein at least one optical layer is configured to compensate for a degradation in the tiled pattern, for example, a separation between tiles, a shape of tiles and / or intensity of tiles and / or angular distortion and / or off angle propagation.

18. The apparatus of any preceding claim, wherein the optical device is configured to transform the initial beam pattern to produce a distorted exit beam pattern, wherein the distorted exit beam pattern forms the tiled pattern in the reception region.

19. The apparatus of claim 18, wherein the distorted exit beam pattern comprises a distortion comprising a skewed, twisted and / or otherwise distorted part of a tile.

20. The apparatus of any preceding claim wherein the optical device is configured to transform the initial beam pattern to an exit beam pattern on exiting the optical device55759840-1M&C PE963133GB46wherein the exit beam pattern is a near field pattern that evolves and / or forms the tiled beam pattern as exit beam pattern propagates, optionally through free space.

21. The apparatus of any preceding claim, wherein the plurality of transmitters comprise a first plurality of transmitters in a first arrangement, for example, a square array, wherein the optical device is aligned with the plurality of transmitters to receive light from the first plurality of transmitters, wherein the optical device comprises one or more peripheral or further transmitters provided at the periphery or outside the first arrangement of transmitters configured to transmit OWC signals through a field of view that overlaps or coincides with part of the tiled pattern.

22. The apparatus of claim 21, wherein the optical device is aligned with the transmitters such that a propagation direction of a beam from the peripheral or further transmitters is substantially unmodified by the optical device and / or such that the light of the peripheral or further transmitters evolves to contribute to one or more tiles of the tiled pattern in the reception region, optionally one or more central tiles.

23. The apparatus of claim 21 or 22, wherein the optical device and transmitters are arranged and / or sized so that the optical device steers beams from the first plurality of transmitters to form the tiled pattern and so that beams from the peripheral or further transmitters avoid or are steered to a lesser degree by the optical device.

24. The apparatus of any preceding claim, wherein the optical device comprises at least two co-operating optical layers or components configured to co-operate to at least shape optical beams thereby to form tiles of the tiled pattern with a desired shape, wherein the shape and / or size and / or a further property of the produced optical beam is dependent on a relative positioning of the at least two co-operating optical layers or components.

25. The apparatus of any preceding claim, further comprising a mechanism to obtain relative movement, optionally translational and / or rotational movement of the cooperating optical layers55759840-1M&C PE963133GB4726. The apparatus of claim 24 or 25 wherein the co-operating layers comprise a plurality of refractive elements, optionally focusing and diverging elements, in a regular arrangement, optionally a lattice and / or array.

27. The apparatus of claim 24 to 26 wherein the co-operating layers comprise a repeating unit cell comprising focussing and diverging elements, optionally elements of positive and negative curvature, wherein the shape of the optical beam is dependent on the relative position between the focussing and divergent elements of the respective optical layers.

28. The apparatus of claims 24 to 27, wherein a degree of beam shaping and / or size of a tile is dependent on a relative position and / or orientation between the unit cell of the first refractive device and the unit cell of the second refractive device.

29. A receiver apparatus configured for use with a transmitter apparatus as claimed in any of claims 1 to 28 wherein the receiver apparatus comprises one or more receivers and one or more optical components, arranged separately and / or in one or more optical layers, wherein the one or more optical components are configured to steer and focus or otherwise transform light received from one or more tiles of the formed tiled pattern for the plurality of receivers.

30. The receiver apparatus of claim 29, wherein the one or more optical components are configured to match the degree of steering and / or focussing to the tiled pattern formed by the transmitter apparatus.

31. The receiver apparatus of claim 30, wherein each receiver of the plurality of receivers corresponds to a transmitter and / or a tile of the formed tiled beam pattern.

32. The receiver apparatus of claims 29 to 31, wherein the one or more optical components are configured to transform a plurality of incoming beams in a plurality of direction determined by the tiled beam pattern to a plurality of parallel beams for the receivers.

33. A method of transmitting optical wireless communication signals comprising: transmitting OWC signals in an initial beam pattern from a plurality of transmitters in a55759840-1M&C PE963133GB48planar light emitting surface and transforming, by an optical device, the initial beam pattern to a tiled beam pattern in a reception region, wherein the tiled beam pattern is formed as a far field pattern and / or wherein the tiled beam pattern or at least one property of the tiled beam pattern is substantially maintained and / or unmodified along a propagation direction in the reception region,wherein the optical device comprises one or more optical components corresponding to or arranged as one or more optical layers, wherein each optical layer of the one or more optical layers is configured to modify one or more properties of light beams transmitted from the plurality of transmitters to form the tiled beam pattern in the reception region, wherein each optical layer lies substantially in and / or defines a plane that is substantially parallel to the planar light emitting surface..55759840-1

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