WO2024017694A1

WO2024017694A1 - A light guiding system for a liquid volume

Info

Publication number: WO2024017694A1
Application number: PCT/EP2023/069105
Authority: WO
Inventors: Marc Andre De Samber; Harry Broers
Original assignee: Signify Holding B.V.
Priority date: 2022-07-18
Filing date: 2023-07-11
Publication date: 2024-01-25

Abstract

A mechanism for guiding and controlling light into a liquid volume. A light intake receives light, such as natural light or sunlight, which is optically coupled into a light guide volume of an optical waveguide. When the optical waveguide is immersed in the liquid volume, one or more light exit windows permit the exit of light from the light guide volume into the liquid volume at multiple depths of the liquid volume. A light control system is configured to modify or control the spectral power distribution of light exiting the light exit window(s) to differ at different depths of the liquid volume.

Description

A light guiding system for a liquid volume

FIELD OF THE INVENTION

The present invention relates to the field of light guiding systems.

BACKGROUND OF THE INVENTION

There is an increasing interest in the cultivation of underwater organisms, such as fish, kelp or crustaceans. It is recognized that different aquatic species will typically reside or prefer different depths. Due to the absorption of light by liquids such as water, the different aquatic species will experience different spectral power distributions of light, e.g., different light intensities and/or light spectrums or frequencies at varying depths.

It has been identified that changes in the spectral distribution will affect the homeostasis and physiology of an organism, as well as the visual perception (‘seeing ability’) and the associated behavior for higher order species. There is therefore a desire to facilitate control of the spectral power distribution of light incident upon an aquatic organism, to control behavior, growth and/or other characteristics of the organism.

WO 2013/090505 Al discloses a lighting assembly for enhancing the growth of aquatic life in an ecosystem and method of enhancing the growth of aquatic life in such an ecosystem. The assembly includes a vessel submerged within water of the ecosystem. A substrate is disposed within and surrounded by the vessel and provides electronics to provide a conditioned current to a plurality of light emitting diodes also contained on the substrate. The light emitting diodes emit light within the water of the ecosystem that provides for growth, not only in a larger volume of the ecosystem, but in addition enhances the growth of the aquatic life.

US 2016/0120157 Al discloses an illumination system for cultivation of aquatic animals in a volume of water, the cultivation using a feeding system defining a feeding axis in the volume of water. The system comprises at least a first illumination surface positioned in the volume of water and arranged for illuminating the feeding axis. The system also comprises a second illumination surface positioned in the volume of water and arranged for illuminating the feeding axis. The first illumination surface and second illumination surface are different surfaces arranged to illuminate the feeding axis from substantially different directions.

WO 2013/0968940 Al discloses a method for enhancing the production of aquatic organisms under cultivation, including the steps of exposing the aquatic organisms to a submerged illumination source inside water of a rearing unit and maintaining illumination in the rearing unit for a rearing period.

SUMMARY OF THE INVENTION

The invention is defined by the claims.

According to examples in accordance with an aspect of the invention, there is provided a light guiding system for guiding light into a liquid volume. The light guiding system comprises: a light intake configured to receive light; an optical waveguide for being immersed in the liquid volume and comprising: a light guide volume, wherein the optical waveguide is optically coupled to the light intake and configured to distribute light received at the light intake throughout the light guide volume; and one or more light exit windows configured, when the optical waveguide is immersed in the liquid volume, to permit the exit of light from the light guide volume into the liquid volume at a plurality of different depths; and a light control system configured to, when the optical waveguide is immersed in the liquid volume, control the spectral power distribution of light that exits the one or more light exit windows to differ at different depths.

The present disclosure provides a mechanism for directing light, such as sunlight or natural light, into a liquid volume, such as a body of water. In this way, light is effectively brought down or diverted down into the liquid volume, e.g., for illuminating organisms (such as plants, fish or other aquatic animals) in the liquid volume. This provides a cheap and energy-neutral method for improving and/or controlling the light conditions in deep water, e.g., for improving organism cultivation. In particular, light can be provided at depths at which at least some natural light (having all wavelengths as represented in natural sun light) would be filtered by the liquid volume.

A light guide is used to direct light from a light source to a place where the light is needed. Light guides are also sometimes referred to as light pipes. Light guides as used herein are configured to transport light from a light intake location to a light exit location. They may or may not be further configured to provide optical processing of the light, such as spectral filtering or reflection. A variety of purposes for light provided via the light exit windows is envisaged. For instance, the diverted light can be used to highlight or identify feed for animals to improve feed finding capabilities. As another example, the diverted light could be used to provide greater intensity light to growing kelp or other plants (e.g., encouraging greater photosynthesis and/or growth).

The proposed technique provides a light control system that modifies or otherwise defines the spectral power distribution (i.e., intensity and/or color) of light that exits the light guide volume into the liquid volume to differ at different depths of the liquid volume. This provides a mechanism for providing different forms of light at different depths, e.g. to encourage and/or stimulate desired characteristics at different depths or to account for changes in light that occur at different depths (due at least to differing absorption amounts of light with increased depth).

More particularly, the light control system can act to control the spectral power distribution (i.e., intensity and/or spectrum) of light that exits the light exit window(s). This control can be used, for instance, to control a type of light that is output by the light exit window(s).

The liquid volume may, for instance, be a body of water. The water may be fresh or salt water. The liquid volume may be enclosed by an enclosure or container, or may be open.

It will be apparent that the light exit window(s) is/are configured to, when the optical waveguide is immersed in the liquid volume, allow at least some of the light that is coupled into the light guide volume from the light intake to exit the light guide volume into the liquid volume.

The light received at the light intake is light generated externally to the liquid volume and/or the light guiding system, such as sunlight or natural light. However, the light may also be generated by a separate light emitting system, such as a luminaire. This approach would allow a luminaire to be distanced from the liquid volume, whilst the light generated is still able to be provided at depth within the liquid volume, which can improve a safety of such a system, e.g., by reducing a likelihood that the luminaire will come into contact with the liquid volume. Therefore, the light intake, when in use, is intended to be positioned above an uppermost surface of the liquid volume.

The light control system is preferably configured to at least partially attenuate light coupled into the light guide volume from the light intake differently for each of the plurality of depths. In some examples, the one or more light exit windows comprises a plurality of light exit windows. Using a plurality of light exit windows facilitates improved ease of control of spectral light distribution at different depths, e.g., by controlling the light that is output by different light exit windows differently.

In some examples, the optical waveguide is configured such that, when the optical waveguide is immersed in the liquid volume, at least two of the light exit windows are configured to permit the exit of light from the light guide volume into the liquid volume at a different depth of the liquid volume.

The optical waveguide may be configured such that, when the optical waveguide is immersed in the liquid volume, the at least two of the light exit windows are configured to permit the exit of light from the light guide volume into the liquid volume at a respective predetermined depth of the liquid volume.

In some examples, the light control system is configured to control the spectral power distribution of light that exits each light exit window differently for each light exit window. This provides a simple and easily implementable mechanism for controlling or defining different spectral power distributions at different depths.

The light control system may be configured to, for each of a plurality of different reference depths, control the spectral power distribution of light that exits the at least one light exit window at the reference depth to at least partially compensate for a spectral attenuation, by the liquid volume, of light that reaches the reference depth from a boundary between a surface of the liquid volume and air. This approach provides an aquatic environment with more homogenous light. This can, for instance, encourage aquatic animals to spread themselves over a larger range of depths (as such species may be attracted to certain light levels/colors) for improved wellbeing of the aquatic animals and/or to facilitate increased numbers of the aquatic animals within the liquid volume. This approach can also improve availability of light for plants or other organisms (e.g., algae) that make use of photosynthesis. For most organisms, photosynthesis is particularly efficient with light having the same spectral light distribution as sunlight. Thus, compensating for spectral attenuation can improve efficiency of organism growth and development.

Spectral attenuation refers to the wavelength-dependent loss of intensity of light with increasing depth in a liquid volume. Generally, red light is attenuated at shallower depths than blue/green light. At least partially compensating for this spectral attenuation may comprise supplementing light at certain depths with additional light to bring the spectral power distribution at said depths closer or more aligned with the spectral power distribution of natural light or sunlight.

At least partially compensating for the spectral attenuation may therefore comprise providing additional light from the light guiding system into the liquid volume at different depths such that the combination of light reaching the depths from an air-liquid boundary of the liquid volume and additional light provided from the light guiding system produces light having the same or similar spectral characteristics of the light at the air-liquid boundary of the liquid volume.

The boundary between the surface of the liquid volume and air may represent an uppermost surface of the liquid volume.

The light control system may be configured to control the spectral power distribution of light that exits the light exit window (e.g., at each different depth) to stimulate a desired behavior, growth or other characteristics of an organism (e.g., at each different depth). It is recognized that different spectral power distributions will encourage or stimulate certain characteristics in aquatic organisms. This approach provides a mechanism for stimulating these characteristics at different depths, e.g., to define different zones or areas for the organism(s) for achieving different characteristics.

In some examples, the light control system may be configured to control the spectral power distribution of light that exits the light exit window (e.g., at each different depth) to provide light having a spectral power distribution configured to encourage photosynthesis by kelp (or other aquatic plants) at a plurality of depths.

In some examples, the light control system is configured to control the spectral power distribution of light that exits the light exit window to encourage greater distribution of a plurality of organisms throughout the liquid volume or to provide homogenous light at a plurality of depths.

Embodiments recognize that the intensity and/or color of light in liquid can define the location of aquatic organisms. For instance, certain species/types of fish are attracted to particular light levels/colors over other light levels/colors. Using the proposed technique allows the same light intensities/colors to be provided at more locations/depths than previously possible, encouraging or causing a greater distribution of the organisms.

In some examples, the light control system comprises one or more light filters and/or frequency-selective partially-reflective surfaces.

The light control system may comprise an internal lighting arrangement configured to, for each of the plurality of depths, generate and provide light of a different, respective spectral power distribution for exiting the one or more light exit windows. Thus, the spectral power distribution of light generated for any one of the plurality of depths may be different to the spectral power distribution of light produced for any other of the plurality of depths.

The light control system may comprise, for each of the plurality of depths, a light guide positioned within the light guide volume, the light guide being configured to guide light from the light intake to the one or more light exit windows, wherein each light guide is configured to cause light to exit the one or more light exit windows at a different depth (i.e., to any other light guide).

The light control system may further comprise, for each light guide, a light attenuating element configured to at least partially attenuate light transmitted through the corresponding light guide. Preferably, each light attenuating element attenuates a different amount and/or frequency of light such that the light that exits the one or more light exit windows has a different spectral power spectrum at each of the plurality of depths.

The structure and/or shape of each light guide, from the light intake, may be configured such that, when the optical waveguide is immersed, a different amount of light is coupled from the light intake to different depths of the liquid volume (via the one or more light exit windows).

For example, the structure and/or shape of the entrance to each light guide, from the light intake, may be configured such that a different amount of light is coupled from the light intake into different light guides. This approach provides a mechanism for controlling how much light passes from the light intake to the light guide.

By way of example, light guides for deeper depths may have a larger entrance than light guides for shallower depths. This would result in more light being guided to deeper depths, e.g., for improved homogeneity of light throughout the liquid volume.

In preferred examples, the optical waveguide is configured so that light in the light guide volume is only able to exit the light guide volume via the one or more light exit windows.

Optionally, the optical waveguide is configured such that any light exiting each light exit window exits at an angle no greater than 25° from a horizontal plane, and more preferably at an angle no greater than 15° from the horizontal plane. This approach helps to provide more distinct or separable zones or layers of light (e.g., of different spectral power distributions) in the liquid volume. In some examples, the optical waveguide is configured to, when immersed in the liquid volume, extend in a first direction away from a surface of the liquid volume. The first direction is a substantially vertical direction. This approach helps to guide the light deep within the liquid volume efficiently, using less material.

The optical waveguide may comprise an elongate prism. In some examples, the optical waveguide comprises one or more elongate members configured to extend outwardly from the elongate prism, wherein each light exit window is located at a distal end of a respective elongate member.

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

BRIEF DESCRIPTION OF THE DRAWINGS

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

Fig, 1 illustrates a light guiding system;

Fig, 2 illustrates another light guiding system;

Fig, 3 illustrates another light guiding system;

Fig, 4 illustrates another light guiding system;

Fig, 5 illustrates another light guiding system;

Fig, 6 illustrates a use-case scenario for a light guiding system; and

Fig. 7 illustrates various artificial lighting arrangements for a light guiding system.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention will be described with reference to the Figures.

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

The invention provides a mechanism for guiding and controlling light into a liquid volume. A light intake receives light, such as natural light or sunlight, which is optically coupled into a light guide volume of an optical waveguide. When the optical waveguide is immersed in the liquid volume, one or more light exit windows permit the exit of light from the light guide volume into the liquid volume at multiple depths of the liquid volume. A light control system is configured to modify or control the spectral power distribution of light exiting the light exit window(s) to differ at different depths of the liquid volume.

Embodiments are based on the realization that it would be advantageous to provide light of different spectral power distributions at different depths, e.g., to compensate for depth-dependent loss of light frequencies and/or to encourage different organism characteristics at different depths and/or to define different zones for aquatic organisms at different depths. Proposed approaches facilitate improved control or management of organisms within the liquid volume.

Approaches proposed by the present disclosure can be employed in any suitable aquatic environment for which distribution of light is desired, e.g., for aquatic agriculture or aquaculture.

In the context of the present disclosure, sunlight refers to light generated by the sun and can be alternatively labelled natural light.

Figure 1 illustrates a light guiding system 100 for guiding light 190 into a liquid volume 195. Here, the liquid volume is a volume of water, e.g., bounded by a (sea) cage 196 or other form of enclosure. However, this is not essential, and the volume of water may be unbounded or be defined in a dedicated container.

The liquid volume 195 may house or contain one or more organisms 199, such as fish, other aquatic animals, aquatic plants and/or algae.

The light 190 may be natural light or sunlight. Alternatively, the light may be light generated by an artificial light source, such as a lamp or luminaire. By adding such an artificial light source, the effective 'length of day' could be extended and/or kept nearconstant over time or over different seasons.

The light guiding system 100 comprises a light intake 110. The light intake is configured to receive the light 190. In some examples, the light intake may be configured to collimate the received light. Although illustrated as having a tapered shape, the light intake 110 may have any suitable structure for receiving and/or guiding light into the light guiding system 100, such as: a flat (panel) like structure, a rounded or hemi-spherical shape/structure or any other structure.

The light guiding system 100 also comprises an optical waveguide 120, comprising a light guide volume 121 and a light exit window 123. The optical waveguide is configured to be immersible in the liquid volume 195.

The optical waveguide 120 is optically coupled to the light intake 110, and is configured to distribute light or natural light, received at the light intake 110, throughout the light guide volume 121. The optical waveguide 120 thereby acts to direct light beams received at the light intake 110 in the light guide volume 121.

In the illustrated example, the optical waveguide 120 comprises an elongate prism 122. The elongate prism 122 defines or sets the bounds of the light guide volume 121, i.e., the bounds of the volume in which light is retained or contained by the optical waveguide 120. The light guide volume 121 and/or optical waveguide 120 is configured to retain all (e.g., >99% or >99.9%) of light coupled into the light guide volume 121 via the light intake 110 within the light guide volume 121 (except for when exiting via the light intake 110 or light exit window as later described).

The optical waveguide 120 may use the principles of total internal reflection and/or reflective material on the surface of the optical waveguide to contain the light within the light guide volume.

As one example, the elongate prism 122 of the optical waveguide 120 may be formed from a (uniform or continuous) block of optically conductive material (e.g., glass or plastic). The block of material may define the bounds of the light guide volume. The block of material may be coated with a reflective material to contain light within the light guide volume and/or may rely upon the principle of total internal reflection to retain/contain the light.

In another example, the light guide volume 121 is a hollow space within the optical waveguide 120. Thus, the elongate prism may define the bounds or perimeter of the hollow space. Put another way, the elongate prism may form sides around a hollow space (e.g., filled with air). The bounds of the optical waveguide 120 may be made of a reflective material to retain/contain light within the hollow space defining the light guide volume.

The light exit window 123 is configured to permit or allow the exit or passage of light (which has been coupled into the light guide volume via the light intake) from the light guide volume 121 to the liquid volume 195. Of course, such light only exits or passes from the light guide volume 121 to the liquid volume 195 when the optical waveguide 120 is immersed in the liquid volume 195.

The light exit window 123 is configured to permit the exit/passage of light into a plurality of different depths di, d2, ds of the liquid volume. A number of different depths di, d2, ds are identified for illustrative purposes, but it will be appreciated that a greater or smaller number of depths could be provided.

The light exit window 123 may be formed of any suitable transparent or translucent material that permits or allows the passage of light out of the light guide volume. The light exit window may be, for instance, comprise a lens or array of lenses configured, e.g., shaped or otherwise structured, to permit or allow the passage of light out of the light guide volume 121. Any other type of out-coupling element can be used as a light exit window, for instance, simple modifications on the surface of the optical waveguide can be configured to allow light to exit the optical waveguide and the light guide volume 121 at desired locations.

In preferred examples, the optical waveguide 120 is configured so that light in the light guide volume 121 is only able to exit the light guide volume 121 via the light exit window 123. This can be achieved through appropriate material selection of the optical waveguide 120.

For the sake of illustrative clarity, the general direction of light movement from the light intake 110 to the light exit window 123 is illustrated in Figure 1 using dotted lines. It will be appreciated that the actual movement of light may be less direct (e.g., involve one or more reflections of side/bottom surfaces of the optical waveguide 120).

The light guiding system 100 further comprises a light control system 130. The light control system 130 is configured to modify, change or otherwise control the spectral power distribution of light that exits the light exit window 123. In particular, the light control system 130 is configured such that the spectral power distribution of light exiting the light guide volume into the liquid volume is different at different depths (of the liquid volume). More particularly, the illustrated light control system 130 is configured to perform different attenuations of light coupled into the light guide volume from the light intake for different respective depths (of the liquid volume).

Controlling the spectral power distribution effectively controls an intensity and/or color (e.g., the location of peak/dominant wavelengths and/or frequencies and/or the magnitude at different wavelengths/frequencies) of the light exiting the light guiding system into the liquid volume. It will be apparent that changes to intensity and/or frequency of light will change the spectral power distribution of the light.

In the illustrated example, the light control system 130 comprises a light filter positioned on the light exit window. The light filter 130 may be a graduated filter that changes the amount and/or color of light that is filtered (i.e., attenuated) at different locations of the light exit window, such that the spectral color distribution of light that exits the light exit window differs at different locations, and particularly different depths. A light filter that filters certain colors may be labelled a color filter or color light filter.

This approach allows controlled intensity and/or color at different depths and/or output locations of the light guiding system 100.

An alternative to a single, graduated light filter is a light filter array or light filter arrangement comprising a plurality of different light filters (e.g., arranged in an array or the like). The light filter array may therefore comprise a plurality of separate and/or distinct light filters, such that light filtered by different filters exits the light exit window at different depths and/or positions of the liquid volume 195. Each light filter may be adapted to filter a different color and/or amount of light, to thereby modify the spectral power distribution at different depths.

In some examples, the light filter may instead be positioned on the entrance to the light guide volume 121, i.e., on the boundary between the light intake and the light guide volume. One advantage of this approach is that the light filter can be easily installed and/or modified after installation (e.g., for maintenance or to adjust to changing light conditions).

Of course, in some examples, there is a light filter on both the entrance and the light exit window.

If a light filter is positioned at the entrance to the light guide volume 121, in preferred examples, the light filter and/or the light guiding system may be configured such that (when the optical waveguide is immersed in the liquid volume) the light filter is above the uppermost surface of the liquid volume. This increases an ease of maintenance and/or replacement of the light filter.

Suitable example modifications to the intensity and/or color of light output by the light exit window for different depths are later described.

Preferably, and as illustrated, the optical waveguide is configured to, when immersed in the liquid volume, extend in a first direction 150 away from a surface 197 of the liquid volume 195. The surface 197 is the natural surface or boundary between the liquid volume and air. The first direction is a substantially vertical direction. This guides the light deep within the liquid volume efficiently, using less material.

The optical waveguide may be configured such that any light exiting each light exit window exits at an angle no greater than 25° from a horizontal plane, and more preferably at an angle no greater than 15° from the horizontal plane, e.g., no greater than 5° from the horizontal plane. This can be achieved through appropriate selection and configuration of the light exit window, e.g., appropriate shaping of the light exit window. This approach facilitates improved control over the spectral power distribution of light emitted by the light guiding system at specific depths, e.g., by reducing an amount of light emitted at a particular depth that is able to disperse to a more shallow or more deep depth of the liquid volume.

Figure 2 illustrates another light guiding system 200 for guiding light 190 into a liquid volume 195.

The light guiding system 200 differs from the earlier light guiding system 100 in that the light control system comprises a partially reflective surface or mirror 230, rather than a filter. The light control system continues to perform different attenuations of light coupled into the light guide volume from the light intake for different depths (of the liquid volume).

The partially reflective surface 230 may be configured to (at different locations of the surface/mirror) absorb different amounts and/or frequencies of light, such that the spectral power distribution of light reflected by the reflective surface changes dependent upon the location at which said light is incident upon the reflective surface. Thus, the partially reflective surface is a frequency-selective partially reflective surface.

At least some of the light that is incident upon the partially reflective surface is redirected (e.g., via zero or more other reflections) towards the light exit window 123. Light incident of different parts of the partially reflective surface is redirected towards different parts of the light exit window. As different amounts/frequencies of light are absorbed by different portions of the partially reflective surface, the spectral power distribution of light that exits the light exit window will differ for different positions and/or depths of the liquid volume.

An alternative to a single partially reflective surface is a mirror array, comprising a plurality of separate and/or distinct partially refl ective/ab sorb ent surfaces.

Of course, a combination of the (graduated) partially reflective surface(s) and light filter(s) could be used in some embodiments. Figure 3 illustrates a light guiding system 300 for guiding light 190 into a liquid volume 195.

The light guiding system 300 differs from the earlier light guiding systems 100, 200 in that the (single) light exit window is replaced by a plurality 323 of light exit windows 323 A, 323B, 323C. Each light exit window is configured to allow the exit or passage of light (which has been coupled into the light guide volume via the light intake) out from the light guide volume 121 and into the liquid volume (when the optical waveguide is immersed in the liquid volume 195).

In this context, each light exit window is distinct and separate from each other light exit window. Thus, there is at least a portion of the optical waveguide through which light does not exit the light exit window between each light exit window.

More particularly, in the illustrated example, each light exit window is configured to permit the exit of light from the light guide volume into the liquid volume at a different depth di, d2, ds of the liquid volume. Thus, each light exit window may be associated with a different depth of the liquid volume.

In the illustrated example, the plurality of light exit windows comprises three light exit windows. However, the light guiding system 300 may comprise any number of light exit windows, e.g., 2 light exit windows, 4 lights exits windows, 6 light exit windows, 10 light exit windows or more than 10 light exit windows.

Each light exit window may be formed of any suitable transparent or translucent material that permits or allows the passage of light out of the light guide volume. Each light exit window may, for instance, be or comprise a lens or array of lenses configured to permit or allow the passage of light out of the light guide volume.

In preferred examples, the optical waveguide 120 is configured so that light in the light guide volume 121 is only able to exit the light guide volume 121 via the light exit windows 323 A, 323B, 323C. This can be achieved through appropriate material selection.

In some examples, the optical waveguide may be configured so that each light exit window permits the exit of light from the light guide volume into the liquid volume at a respective predetermined depth of the liquid volume. The depth can be predetermined by, for instance, defining a position of each light exit window with respect to the optical waveguide, as well as defining the position of the optical waveguide with respect to a surface of the liquid volume (e.g., by appropriately weighting and/or floating the light guiding system and/or defining a location of the base of the light guiding system). The light control system 330 may be configured to control the spectral power distribution of light that exits each light exit window differently for each light exit window. Thus, the spectral power distribution of light that exits each light exit window may be defined differently.

In particular, the light control system 330 is configured to perform different attenuations of light coupled into the light guide volume from the light intake for different light exit windows, and therefore for different depths (of the liquid volume).

In this way, if the optical waveguide is configured so that each light exit window permits the exit of light from the light guide volume into the liquid volume at a respective predetermined depth of the liquid volume, this allows the light control system to control the spectral power distribution of light at predetermined depths.

This can be achieved, for instance, by providing a different light filter, e.g., a color and/or intensity filter, 33 A, 33B, 33C for each light exit window 323 A, 323B, 323C (e.g., as illustrated in Figure 3).

Another approach is to use a similar graduated filter as illustrated in Figure 1 (but positioned to cover all/each light exit window(s)). Yet another approach is to use a similar partially reflective surface/mirror as illustrated in Figure 2, or an array of partially reflective surfaces/mirrors (e.g., a partially reflective surface/mirror for each light exit window). Yet another approach is to position a light filter on the entrance to the light guide volume 121.

Figure 4 illustrates a light guiding system 400 for guiding light 190 into a liquid volume 195.

The light guiding system differs from the earlier light guiding system 300 in that the optical waveguide 420 comprises one or more elongate members 425 configured to extend outwardly from the elongate prism 422 (that defines the bounds of the light guide volume 421). Each light exit window 423 A, 423B, 423C of the plurality 423 of light exit windows is located at a distal end of a respective elongate member.

This approach allows further penetration of light in the horizontal plane.

Although illustrated as having a same length, the elongate members 425 may be of two or more different lengths. This allows further penetration of light further in the horizontal plane, e.g., for improved distribution of light.

Figure 5 illustrates yet another light guiding system 500 for guiding light 190 into a liquid volume 195. The light guiding system differs from earlier light guiding systems in that the light control system 530 comprises a plurality of light guides 531, 532, 533. Each light guide is configured to guide light from the light intake 110 to the one or more light exit windows 523 and cause light to exit the one or more light exit windows at a different depth. The number of light guides is equal to the number of the plurality of different depths. This approach allows for finer, and more specific control over the amount of light that is controlled to exit the light exit window at each depth.

In the illustrated example, each light guide guides light from the light intake 110 to a different, single light exit window 523 A, 523B, 523C.

In alternative examples, one or more of the light guides is configured to guide light from the light intake to two or more light exit windows. In some examples, two or more of the light guides are configured to guide light from the light intake to a respective (nonoverlapping) part/portion of a same light exit window or a respective set of (non-overlapping) parts/portions of a same set of light exit windows.

The light control system 530 may further comprise, for each light guide, a light attenuating element 535 configured to at least partially attenuate light transmitted through the corresponding light guide, Each light attenuating element attenuates a different amount and/or frequency of light such that the light that exits the one or more light exit windows has a different spectral power spectrum at each of the plurality of depths. This approach allows for control of the spectral power distribution of light that exits the one or more light exit windows to differ at different depths.

One example of a light attenuating filter is a light filter. Each light filter is different, so that the amount and/or color of light that is filtered by each light filter differs. Another example of a light attenuating element is a partially reflective surface/mirror (e.g., a frequency-selective reflective mirror). This may be used instead of or in additional to a light filter.

The light attenuating element may be positioned at the entrance of the corresponding light guide, as illustrated. Thus, each light attenuating element may be placed at the boundary between the light intake 110 and the optical waveguide 120. One advantage of this approach is that the light attenuating element can be easily installed and/or modified after installation (e.g., for maintenance or to adjust to changing light conditions).

If positioned at the entrance to the light guide volume, in preferred examples, the light attenuating elements and/or the light guiding system may be configured such that (when the optical waveguide is immersed in the liquid volume) the light attenuating elements are above the uppermost surface of the liquid volume. This increases an ease of maintenance and/or replacement of these elements.

Alternatively, the light attenuating element may be placed at any point within the corresponding light guide (e.g., to cover the light exit window or portion(s) of the light exit window).

For instance, the structure and/or shape of the entrance to each light guide, from the light intake, may be configured such that a different amount of light is coupled from the light intake into different light guides.

This approach provides a mechanism for controlling how much light passes from the light intake to the light guide, and thereby to the light exit window. For instance, the entrance to different light guides may have different widths/diameters/dimensions to thereby control an amount of light carried by each light guide to their respective depths.

The proposed approach for using a plurality of light guides allows for different amounts of light to be guided by different light guides, thereby affecting the amount of light that is guided to different depths of the light liquid volume by the light guiding system. This mechanism can be exploited, for instance, to guide more light to deeper depths, e.g., to account for the depth-dependent loss of light from a surface of the liquid volume.

It will be appreciated that the light guiding system 500 may be configured such that the optical waveguide comprises one or more elongate members configured to extend outwardly from the elongate prism, which defines the bounds of the light guide volume 521. Each light exit window of the plurality of light exit windows is located at a distal end of a respective elongate member. In this approach, each elongate member effectively forms part of a different light guide.

In some examples, more than one elongate member may be optically coupled to a single light guide. For instance, each light guide may couple light into a respective set of one or more, and preferably two or more, elongate members. This can improve light coverage in the liquid volume.

Although illustrated as having a bent or L-shaped configuration, each light guide may instead have a straight or substantially straight configuration. In such embodiments, each light exit window may be positioned on a side of a particular light guide. In the illustrated examples of Figures 3, 4 and 5, each light exit window is at a different depth to another light exit window. However, in alternative examples, two or more of the light exit windows emit light at a same depth of the liquid volume.

Preferably, when the optical waveguide is immersed in the liquid volume 195, at least two of the light exit windows are configured to permit the exit of light from the light guide volume into the liquid volume at a different, respective depth of the liquid volume. This does not prohibit there being two or more light exit windows at a same depth.

In some examples, of any herein described light guiding system, the light control system 130, 230, 330, 535 comprises a tunable light control system. This allows for specific control over the spectral power distribution of light emitted by the light guiding system at different depths of the liquid volume. In other words, this provides a mechanism for actively tuning or modifying the spectral power distribution of light emitted by the light guiding system at different depths of the liquid volume.

For instance, the light control system may comprise one or more tunable light filters and/or one or more tunable partially reflective surfaces. Suitable tunable light filters and/or partially reflective surfaces are known in the art. Examples may employ one or more monochromators, Lyot filters, tunable fiber Bragg gratings, tunable optical resonators, liquid crystal modulators and so on.

As an example, a light control system may comprise a mechanical system that moves or changes the position of light filters or partially reflective surfaces. This movement may (re)position said elements to control the spectral power distribution of light that exits the light exit window(s).

For instance, in one scenario, the light control system comprises one or more sets of different light filters (e.g. a set for each depth), e.g., light filters of different colors. Each set may controllably cover and uncover a light exit window or a part/portion of a light exit window. The light control system may be configured so that, for each set, each light filter in the set can be mechanically controlled or moved to cover or uncover a/the (portion of the) light exit window. This would facilitate control over the amount and/or color of light that exits the portion of the light exit window.

Other approaches for providing a tunable light control system will be apparent to the skilled person.

The optical waveguide and/or light control system of any preceding embodiment may be configured such that the light control system can control the spectral power distribution of light at a plurality of predetermined depths. This can be achieved when the depths of the water at the light exit window is known/predetermined or can be determined.

The depth can be predetermined by, for instance, defining a position of the light exit window with respect to the optical waveguide, as well as defining the position of the optical waveguide with respect to a surface of the liquid volume (e.g., by appropriately weighting and/or floating the light guiding system and/or defining a location of the base of the light guiding system).

From the preceding embodiments, it will be clear that any light guiding system proposed by this disclosure comprises one or more light exit windows, and a control system that controls the spectral power distribution of light that exits the light exit window(s).

In particular, it has previously been described how the light control system, of any embodiment, is configured to control the spectral power distribution of light that exits the one or more light exit windows to differ at different depths.

This control technique may be used, for instance, to at least partially compensate for the natural attenuation of natural light or sunlight by the liquid volume. This can be used, for instance, to create a more homogenous light environment in the liquid volume.

Alternatively and/or additionally, this control technique can be used to stimulate a desired behavior, growth or other characteristics of an organism in the liquid volume.

In particular examples, the control technique can be used to create a plurality of different zones in the liquid volume, each zone receiving light (from the light guiding system) having different spectral power distributions, e.g., for targeting different purposes and/or tasks for the zone - such as encouraging different behaviors or other characteristics of organisms in different zones.

It is known that there is an absorption of light by liquid, because of which the light intensity degrades quite rapidly with water depth. The absorption coefficient of the liquid is also dependent on the wavelength. In this way, there is a spectral attenuation of light generated externally to the liquid volume, such as sunlight or natural light, into the liquid volume. The spectral attenuation is different at different depths. In general, red light is absorbed at shallower depths compared to blue light. Put another way, there is a depthdependent loss of light frequencies of natural light entering a surface of the liquid volume.

A spectral attenuation refers to any attenuation that differs for different frequencies or wavelengths of light. In some embodiments, the light control system is configured to, for each of a plurality of different reference depths, control the spectral power distribution of light that exits the at least one light exit window at the reference depth to at least partially compensate for a spectral attenuation, by the liquid volume, of light that reaches the reference depth (from a natural surface of the liquid volume - i.e., the natural boundary between the top of the liquid volume and air).

A reference depth may be a desired or intended depth at which light will exit the light exit window(s). If the optical waveguide and/or light control system is configured such that the light control system can control the spectral power distribution of light at predetermined depths, each reference depth may be a corresponding predetermined depth.

Thus, for shallower reference depths, the light control system may filter out more red light than at deeper reference depths. Put another way, the light control system may be configured to increase an amount of red light output by the light exit window(s) as depth increases. This can be achieved through appropriate selection and positioning of filters or partially reflective mirrors, e.g., to reduce an amount of red light that exits at shallower depths.

This approach at least partially compensates for the spectral attenuation of light with depth. In this way, the light at a plurality of depths of the liquid volume can be controlled to align with or more closely resemble natural light at the surface of the liquid volume (i.e., with reduced spectral attenuation).

Thus, the light that penetrates the liquid volume from the surface can be compensated with ‘corrected’ light via the light guiding system. In particular, the light emitted from the light guiding system can be manipulated and/or filtered to provide compensating light for spectral attenuation, e.g., to compensate for a loss of red at depth.

This approach could be used, for instance, to provide a (more) homogeneous light environment in a tank or pond, at multiple different depths or layers of the liquid volume. This homogenous environment can be achieved by the combination of the light penetration and the appropriately controlled or manipulated emission of light from the light exit windows at particular depths. Thus, the light control system can be used to select light characteristics (i.e., a spectral power distribution) that encourages a behavior of feeding by enhancing the highlighting of food beyond that that would otherwise be naturally available from natural light.

This same principle can be used to provide modified (natural) light at different depths of the water to create different zones for different desired behaviors or purposes. For instance, different lighting characteristics can be provided at different depths to provide different zones for resting, feeding and movement or different zones for layering of fish populations.

Put another way, the light control system may be configured to control the spectral distribution of light that exits the light exit window to define, at different depths of the liquid volumes, different zones. Each zone may represent a zone for a desired behavior, task or purpose. Different zones may therefore be associated with different spectral power distributions.

As an example, a low intensity spectral power distribution may be provided for resting zone. A high intensity spectral power distribution may be provided for a feeding zone.

Zones adjacent to a ‘zone of interest’ might be manipulated to increase the (positive or negative) contrast between the ‘zone of interest’ and adjacent zones. For instance, if a zone of interest is a feeding zone, then the light control system may be configured to provide extremely bright light at the depth for the feeding zone, but light of a lower intensity at adjacent depths, e.g., immediately above and/or below the feeding zone.

It has previously been explained how the optical waveguide may be configured such that any light exiting each light exit window exits at an angle no greater than 25° from a horizontal plane, and more preferably at an angle no greater than 15° from the horizontal plane, e.g., no greater than 5° from the horizontal plane. This approach is particularly advantageous for the creation of zones or (horizontal) layers within the liquid volume, as the boundaries of the zones or layers can be more clearly defined.

It has previously been explained how it is possible to actively tune or modify the spectral power distribution of light output by the light exit window(s) at different depths. In particular, the light control system may be a tunable light control system.

The light guiding system may comprise a light sensing arrangement, e.g., comprising one or more light sensors, configured to sense one or more characteristics of light externally to the optical waveguide. In examples where there are a plurality of light exit windows, a light sensor may be positioned to sense one or more characteristics of light in the vicinity of each light exit window

In one example, a light sensing arrangement is configured to sense an intensity and/or color of light at one or more depths of the liquid volume. This can be achieved using a respective one or more light sensors located at each relevant depth. The sensed color(s) can be used to control the light control system to control the spectral power distribution of light output by the light exit window(s) to achieve a desired intensity and/or color of light (e.g., to compensate for spectral loss) at each of the one or more depths. In other words, the properties of light output by the light guiding system can be used to regulate the light in the vicinity of the light exit window(s) by monitoring the intensity and/or color of this light, and controlling the amount and/or color of light output at the light exit window(s) at the various depths.

Any above described light guiding system can be repurposed for use as a floating buoy and/or an attachment point for kelp or other organisms (such as algae). In some examples, the light guiding system comprises one or more attachments points for such organisms, e.g., one or more appropriately coated portions or surfaces for connecting to any such organisms.

Any above described light guiding system may further comprise an artificial lighting arrangement. The artificial lighting arrangement may be configured and/or positioned to provide light into the light guide volume. The artificial lighting arrangement may comprise one or more artificial lighting sources for generating (artificial) light for the light guide volume. Examples of artificial light sources are well known to the skilled person, and may include one or more LEDs, one or more halogen bulbs and so on.

The artificial lighting arrangement may be integrated into and/or controlled by the light control system. In particular, the light control system may use the light generated by the artificial lighting arrangement to perform additional control over the spectral power distribution of light that exits the one or more light exit windows.

Figure 7 illustrates various optional embodiments or elements for an artificial lighting arrangement, for improved contextual understanding. For improved illustrative clarity, other components of the light control system which may be present are not illustrated. The hereafter described optional elements or components may be used in any herein described embodiment.

For instance, the artificial lighting arrangement may comprise an external lighting arrangement 710. The external lighting arrangement 710 may be positioned apart or separated from the light intake and optical waveguide. In some examples, the external lighting arrangement 710 is connected to the light intake and/or optical waveguide by a lighting support 715. However, this is not essential.

The external lighting arrangement 710 may be designed to enhance or supplement the or any natural light 190 received at the light intake. Thus, the external lighting arrangement may generate light 717 for the light intake, e.g., direct generated light towards the light intake. Optionally, the external lighting arrangement may comprise a natural light sensor 718. The natural light sensor may monitor a spectral power distribution of natural light 190, e.g., at the uppermost surface of the liquid volume. The external lighting arrangement 710 may be configured to generate light responsive to the monitored spectral power distribution, e.g., to emit light that combines with the natural light to achieve a desired spectral power distribution of light received by the light intake. The desired spectral power distribution may, for instance, be a spectral power distribution of sunlight during the day. This approach can be used to energy-efficiently extend the day period (e.g., the period during which the light at the light intake is at the desired spectral power distribution). The system can also be used when natural light is absent.

In some examples, the artificial lighting arrangement comprises an internal lighting arrangement 720 being a lighting arrangement located within the optical waveguide 120 and/or light guide volume 121.

In some examples, the internal lighting arrangement comprises a light guide volume lighting module 721 configured to supplement the light coupled into the light guide volume from the light intake. This can, for instance, allow the light in the light guide volume to have a desired spectral power distribution. Such an internal lighting arrangement may comprise a light sensor configured to monitor a spectral power distribution of light in the light guide volume. The internal lighting arrangement may be configured to generate light responsive to the monitored spectral power distribution, e.g., to emit light that combines with the light received via the light intake to achieve a desired spectral power distribution of light within the light guide volume.

In some examples, the internal lighting arrangement is configured to, for each of the plurality of depths, generate and provide light of a different spectral power distribution for exiting the one or more light exit windows.

For instance, the internal lighting arrangement 720 may comprise a light source 722, 723, 724 for each of the plurality of depths (e.g., each portion of a light exit window or light exit window). Suitable examples of light sources are well known to the skilled person, e.g., LEDs, halogen bulbs, fluorescent tubes and so on,

Each light source provides additional, preferably controllable light, that can be controlled to modify or control the spectral power distribution of light emitted at each of the plurality of different depths. This provides a further level of control over the spectral power distribution at different depths and could, for instance, be exploited to provide homogenous lighting at different depths of the liquid volume. Each light source may be associated with a light source guide, that guides the light emitted by the light source to a particular location at the light exit window(s). This ensure that the light generated by a light source is provided at a respective or corresponding depth. However, the light source guides may be omitted if, for instance, the light sources are appropriately positioned and/or configured to collimate light.

Each light source may be housed or positioned in a different light guide, if present. Thus, if the light guiding system comprises a plurality of light guides (e.g., as illustrated in Figure 5), then the internal lighting arrangement may comprise a controllable light source located in each light guide.

In such examples, the light source may, for instance, comprise a ring light or a light located around the perimeter of the light guide. This approach can reduce or mitigate any blocking of natural light entering the light guide.

As another example, the internal lighting arrangement 720 may comprise a single light source that emits light. Different light attenuation elements may filter the emitted light differently for different depths.

The internal lighting arrangement may comprise, for each different depth, a depth light sensor for sensing a spectral power distribution at the depth. The light source for that depth may then be controlled (e.g., in addition to other parts of the light control system) to control the spectral power distribution of light at the different depths, e.g. to achieve or target a desired spectral power distribution.

Illustrated embodiments make use of a light control system that at least partially attenuates light coupled into the light guide differently for different depths. However, in some examples, these elements can be omitted and the light control system may comprise only the artificial lighting arrangement.

Illustrated embodiments demonstrate the light exit window(s) being positioned on a single side of the optical waveguide. However, it will be appreciated that the light exit window(s) can be positioned on any of a plurality of sides of the optical waveguide.

Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to". If the term "arrangement" is used in the claims or description, it is noted the term "arrangement" is intended to be equivalent to the term "system", and vice versa. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A light guiding system (100, 200, 300, 400, 500) for guiding light (190) into a liquid volume (195), the light guiding system comprising: a light intake (110) configured to receive light generated externally to the liquid volume and/or the light guiding system, the light intake for being positioned above an uppermost surface of the liquid volume; an optical waveguide (120) for being immersed in the liquid volume and comprising: a light guide volume (121), wherein the optical waveguide is optically coupled to the light intake and configured to distribute light received at the light intake throughout the light guide volume; and a plurality of light exit windows (122, 322A, 322B, 322C) configured, when the optical waveguide is immersed in the liquid volume, to permit the exit of light from the light guide volume into the liquid volume at a plurality of different depths, and a light control system (130, 230, 330) configured to, when the optical waveguide is immersed in the liquid volume, control the spectral power distribution of light that exits the plurality of light exit windows to differ at different depths.

2. The light guiding system of claim 1, wherein the optical waveguide is configured such that, when the optical waveguide is immersed in the liquid volume, at least two of the light exit windows are configured to permit the exit of light from the light guide volume into the liquid volume at a different depth of the liquid volume.

3. The light guiding system of claim 2, wherein the optical waveguide is configured such that, when the optical waveguide is immersed in the liquid volume, the at least two of the light exit windows are configured to permit the exit of light from the light guide volume into the liquid volume at a respective predetermined depth of the liquid volume.

4. The light guiding system of any of claims 1 to 3, wherein the light control system is configured to control the spectral power distribution of light that exits each light exit window differently for each light exit window.

5. The light guiding system of any of claims 1 to 4, wherein the light control system is configured to, for each of a plurality of different reference depths, control the spectral power distribution of light that exits a light exit window, of the plurality of light exit windows, at the reference depth to at least partially compensate for a spectral attenuation, by the liquid volume, of light that reaches the reference depth from a boundary between a surface of the liquid volume and air.

6. The light guiding system of any of claims 1 to 5, wherein the light control system is configured to control the spectral power distribution of light that exits the light exit window to stimulate a desired behavior, growth or other characteristics of an organism.

7. The light guiding system of claim 6, wherein the light control system is configured to control the spectral power distribution of light that exits the light exit window to encourage greater distribution of a plurality of organisms throughout the liquid volume or to provide homogenous light at a plurality of depths.

8. The light guiding system of any of claims 1 to 7, wherein the light control system comprises one or more color filters and/or frequency-selective absorbent reflective surfaces.

9. The light guiding system of any of claims 1 to 8, wherein the light control system comprises an internal lighting arrangement configured to, for each of the plurality of depths, generate and provide light of a different, respective spectral power distribution for exiting the plurality of light exit windows.

10. The light guiding system of any of claims 1 to 9, wherein the light control system comprises, for each of the plurality of depths, a light guide positioned within the light guide volume, the light guide being configured to guide light from the light intake to one or more light exit windows of the plurality of light exit windows, wherein each light guide is configured to cause light to exit said one or more light exit windows of the plurality of light exit windows at a different depth.

11. The light guiding system of claim 10, wherein: the light control system further comprises, for each light guide, a light attenuating element configured to at least partially attenuate light transmitted through the corresponding light guide; and each light attenuating element attenuates a different amount and/or frequency of light such that the light that exits the one or more light exit windows of the plurality of light exit windows has a different spectral power spectrum at each of the plurality of depths.

12. The light guiding system of any of claims 1 to 8, wherein the optical waveguide is configured so that light in the light guide volume is only able to exit the light guide volume via the one or more light exit windows of the plurality of light exit windows.

13. The light guiding system of any of claims 1 to 12, wherein the optical waveguide comprises an elongate prism.

14. The light guiding system of claim 13, wherein the optical waveguide comprises one or more elongate members configured to extend outwardly from the elongate prism, wherein each light exit window is located at a distal end of a respective elongate member.