WO2018073575A1

WO2018073575A1 - Assembly for a side emitting optical fibre

Info

Publication number: WO2018073575A1
Application number: PCT/GB2017/053134
Authority: WO
Inventors: Malcolm Harry Dunn; Donald Walker; Graham M Miller
Original assignee: University Court Of The University Of St Andrews
Priority date: 2016-10-19
Filing date: 2017-10-17
Publication date: 2018-04-26
Also published as: GB201617704D0

Abstract

An assembly comprising an illuminator and/or at least one camera, the assembly further comprising or being configured to connect to at least one side emitting optical fibre, wherein the at least one side emitting optical fibre is configured or configurable to receive at least some of the light from one or more light sources and transmit the light along at least part or all of the length of the at least one optical fibre.

Description

Assembly for a Side Emitting Optical Fibre

Field

This disclosure is concerned with an assembly, such as a subsea assembly, for illuminating and/or collecting images of an area of interest. Particularly, the invention relates to an assembly in the form of a combined helmet light and/or camera and umbilical lighting device.

Background

In commercial subsea diving, supply of air to the diver from the surface is the preferred method (as compared to the use of bottled air carried by the diver) since such a supply scheme places less stringent limitations on diver operating time underwater. Surface supplied air requires the diver to be linked to the surface through an umbilical for the supply of the air along with other services.

In commercial surface air diving umbilical lengths of 75m with depths down to 50m combined with an underwater operating radius of up to 25m typically need to be covered. Alternatively, through the use of saturation diving techniques depths down to 300m can be reached through the use of a diving bell. In this case an umbilical is required to connect the diver to the bell for the supply of air, with a requirement for the diver being able to operate over a radius of up to 75m from the bell. In addition umbilicals may be required to connect remote operating vehicles (ROV) or their derivatives to a bell or other installations or vessels. Subsea commercial surface-air diving is globally important in the contexts of off-shore, submerged tidal and ocean power generation installations, wind farms, harbour clearance, pipeline inspection, and wreck inspection/salvage. In addition saturation diving techniques are required in connection with the inspection and maintenance of oil platforms, and submerged well heads, at depths where surface air diving cannot reach. One of the dangers faced by divers in these environments is entanglement or fouling of their umbilicals, which can significantly compromise diver safety and security.

Summary

According to one aspect of the present disclosure, there is provided an assembly comprising an illuminator and/or at least one camera, the assembly or illuminator further comprising or being configured to connect to at least one side emitting optical fibre, wherein the at least one side emitting optical fibre is configured or configurable to receive at least some of the light from one or more light sources and transmit the light along at least part or all of the length of the at least one optical fibre.

The illuminator may be configured to illuminate an area outwith the illuminator. The at least one light source may be comprised in the illuminator. Alternatively, the at least one light source may be provided outwith the illuminator and light from the light source may be conveyed to the illuminator, e.g. along the side emitting optical fibre. The illuminator may be configured to emit or project light from one or more or each of the light sources, e.g. to illuminate the area outwith the illuminator. The illuminator may comprise or be configured to connect to the at least one side emitting optical fibre. The at least one side emitting optical fibre may be configured or configurable to receive at least some of the light from one or more or each of the light sources and may be configured to transmit the light along at least part or all of the length of the at least one optical fibre or to provide light to the light source. The illuminator may be configured such that the light provided from the at least one light source to the at least one side emitting optical fibre is different from the light from the at least one light source used to illuminate the area outwith the illuminator. The illuminator may be configured to provide separate illumination to the at least one side emitting optical fibre.

The camera may be or comprise a digital camera. The camera may be or comprise a helmet or vehicle camera, which may be configured to record images or video of an area around, or a field of view of, the vehicle or wearer of the helmet. The camera may be or comprise a video and/or stills camera.

The assembly and/or the illuminator may be a combined helmet or vehicle light and/or camera, and umbilical lighting device. The assembly or illuminator may comprise a power connector or feed, connected to or for connecting to a power supply, such as an electrical power supply, preferably a helmet power supply or a power supply from the vehicle. The power connector may be configured to supply power, e.g. electrical power, to the at least one light source and/or to the camera.

The illuminator may be configured to provide light generally in a first direction to illuminate an area with respect to the wearer or vehicle and the at least one side emitting optical fibre may extend from the assembly and/or illuminator at least partially in a different, e.g. opposite direction, to the first direction. The illuminator may be configured to illuminate an area in front of the helmet or vehicle. The illuminator may be a free space illuminator. The at least one side emitting optical fibre may extend from the back of the helmet or vehicle and/or rearwardly from the helmet or vehicle.

The vehicle may be a remotely operated vehicle (ROV), a submarine, or diving bell. The vehicle may be an underwater vehicle or submersible. The vehicle may be manned or unmanned. The camera may be an underwater camera, which may be configured for use underwater.

The illuminator may comprise at least one optical element that receives at least some of the light from one or more or each of the light sources, the at least one optical element being configured to emit or project the light from the illuminator, e.g. to illuminate the area outwith the illuminator. The optical element may be configured to emit or project the light into free space, e.g. not into an optical fibre. The at least one optical element may be or comprise a transparent window. The transparent window may be configured so that light from the light sources passes through the transparent window substantially unmodified. The illuminator may be configured to illuminate the area outwith the illuminator directly from one or more or each of the light sources, e.g. substantially without modifying the light emitted from one or more or each light source. The optical element, e.g. transparent window, may be configured to reduce or limit the divergence of the light emitted by the at least one light source by refraction, which may be due to the medium external to the illuminator being of a higher refractive index than the medium inside the illuminator (e.g. when the internal medium is air and the external medium is water).

The at least one side emitting optical fibre may be comprised in an umbilical, such as a diver's umbilical or an underwater vehicle umbilical. The at least one side emitting optical fibre may extend along at least part, the majority of, or all of the length of the umbilical. The umbilical may be configured such that it does not carry any electrical power supply along its length, i.e. it may be electrically unpowered. However, alternatively the umbilical may be powered, e.g. it may carry an electrical supply along its length. The umbilical may carry the images or feed from the camera, e.g. to the surface or to a dive bell. The images or feed from the camera may be conveyed along the umbilical by optical wireless communications, e.g. using the side emitting optical fibre or as an electrical or acoustic carrier signal.

The at least one side emitting optical fibre may be comprised in or permanently joined to the illuminator. The umbilical and/or the at least one side emitting optical fibre may be selectively lockable or attachable, e.g. connectable / disconnectable from, the illuminator, e.g. via an optical connection. The optical connection of the illuminator may comprise a transparent surface for receiving light from at least one of the light sources. The at least one optical fibre may comprise a corresponding transparent face for receiving light from the transparent surface of the optical connection.

The at least one optical fibre may be configured to receive light from at least one or each of the same light sources that provide light used to illuminate the area, e.g. that provide light to the optical element that emits or projects light from the illuminator. The at least one light source or fibre may be configured to receive light from the light source via a non-imaging concentrator. The non-imaging light concentrator may be provided for directing light from the light source to the fibre and/or for the purpose of optimally coupling the light into the fibre. In other words, at least one or each of the light sources may provide both light for illuminating the area and for the at least one optical fibre, e.g. the light from at least one or each of the light sources may be shared between the at least one optical fibre that lights the umbilical and the optical element that emits or projects light from the illuminator. The at least one optical fibre may be configured to receive light from at least one of the light sources that is different from at least one of the light sources that provide light to the optical element. In other words, different light sources may be used for the at least one optical fibre for lighting the umbilical and the optical element for projecting light from the illuminator.

The illuminator may be configured to emit or project a beam of light from the illuminator, e.g. using the at least one optical element. The beam of light may illuminate an area of interest, such as an area proximate the illuminator, in use. In this way, the illuminator may be operable as a helmet light or work area light, in use, by emitting or projecting the beam of light. The light emitted or projected by the at least one optical element may be for illuminating an area in front of the helmet upon which the illuminator is mounted. The illuminator may be configured such that, in use, the illuminated field of view moves as the helmet or vehicle moves, e.g. such that the illuminated field of view corresponds to what the wearer of the helmet is looking at.

At least one of the optical elements may comprise a lens, such as a spherical or aspherical lens. At least one of the optical elements may comprise a total internal reflector. At least one of the optical elements may comprise a mirror or other reflector, such as a spherical mirror. At least one of the optical elements may comprise a collimator. At least one of the optical elements or a combination of the optical elements may be configured to control, constrain or reduce divergence of the light emitted by at least one or each of the light sources. At least one of the optical elements or a combination of the optical elements may be configured to focus the light emitted by at least one or each of the light sources. At least one of the optical elements may be or may be comprised in a transparent window, e.g. configured so as to allow light to pass through substantially unmodified. For example, the optical elements may consist of the transparent window. At least one of the optical elements (such as one or more of the optical elements listed above) may be or comprise a non-imaging optical element. At least one of the optical elements may be or comprise a non-imaging concentrator, such as a conical or frustoconical concentrator. It will be appreciated that the illuminator may comprise a plurality of optical elements which may comprise optical elements of one of more different types, such as those listed above, at least some of which may indirectly receive the light emitted from at least one or each of the light sources, e.g. via another one of the optical elements.

The illuminator may comprise or be configured to connect to a plurality of side emitting optical fibres, which may be intertwined, e.g. to form a bundle or light rope. The bundle or light rope may comprise a transparent sheath, which may at least partially enclose the optical fibres. The light rope or bundle may be configured to emit light along its length, e.g. from the side emitting optical fibres. The side emitting optical fibre(s) may be configured to emit a continuous light along the length of the optical fibre, e.g. not only at discrete points.

The power connector may be configured to connect to a corresponding power supply connector in or on a worn garment, such as a helmet, e.g. a diver's helmet, and/or in a vehicle such as the ROV, submarine or diving bell. The illuminator may be comprised in or mounted or mountable on the worn garment, which may be the helmet, e.g. the diver's helmet, or on the vehicle, e.g. ROV. The at least one optical fibre may be lit from the helmet or vehicle end, e.g. by at least one or each of the light sources in the illuminator. The assembly or illuminator may have a single power connector. The umbilical may be adapted for use as a diver or underwater vehicle umbilical. The umbilical may be adapted for use between a surface and a subsea location and/or between a diving bell and an individual diver and/or between two or more locations subsea or surface to sea. The umbilical may be adapted to be connected to an underwater remote operating vehicle (ROV), a diving bell or a submarine.

The umbilical may extend from the illuminator, e.g. from a diver or underwater vehicle, to the surface. The at least one optical fibre that is comprised in the umbilical may be lit from the subsea, e.g. diver or vehicle, end. By using a side emitting light fibre rope, the umbilical can emit light along its length, thereby alleviating some of the risks faced by divers. Such an umbilical has numerous advantages. For example, it can provide a guide-path to the surface and provides general illumination of the sub-sea environment within which the diver or divers are working. This improves the working conditions, and thereby increases efficiency of working. This is particularly important in situations where working time is limited by external constraints, as in the case of sub-sea working. An illuminated umbilical also provides individual divers engaged with others on common tasks with an improved overall visual sense of the communal working environment. The light rope umbilical of the present invention provides a distributed illumination source that is: capable of being installed as one element/strand of the overall umbilical; service-free within the usual lifetime of the umbilical; capable of being retrofitted to existing umbilicals or capable of being pre-installed as part of the standard manufacturing process for umbilicals, and activated if and when required without further modification of the umbilical; capable of withstanding the rigours of the sub-sea environment, particularly with regard to the impact of salt water; physically robust, thereby not suffering damage or failure as a consequence of being incorporated within the bundle of other connections associated with the umbilical; capable of being illuminated without requiring a distributed electrical or other supply along the length of the source for this purpose (i.e. it is a passive source along the length of the umbilical); and capable of withstanding local failure/damage at points along its length without undergoing universal failure. The assembly and/or illuminator may be watertight and/or configured for use underwater, which may be underwater at depth, e.g. at depths of at least 5m, such as at least 10m, 50m, 100m or more.

Since the illuminator both emits or projects a beam of light, e.g. using the optical element, and also lights the at least one side emitting fibre optic cable that illuminates or lights up the umbilical, a common power supply, such as an existing helmet light or camera power supply or a vehicle power supply, can be used to power the light sources that provide both a helmet light (e.g. the projected beam of light) and provide the light to the light rope and/or also provide power to a camera such as a helmet or vehicle camera. This may also allow the umbilical illumination via the at least one side emitting optical fibre to be easily retrofitted to an existing system, e.g. by replacing the helmet light or camera with the assembly. In addition, by providing one or more of the light sources that provide light to both the optical element (e.g. to provide the projected beam of light) and the at least one optical fibre, a low power illuminator may be provided. Furthermore, the assembly may advantageously allow a helmet or vehicle light for illuminating an area of interest or work area, a camera for recording the illuminated area of interest or work area and a side emitting optical fibre umbilical to be powered from a single common connection, which may allow easier retro-fitting, e.g. to an existing light or camera connector on a helmet or vehicle. In addition, an area of interest to be recorded by the camera can be illuminated and at the same time the side emitting optical fibre lit in a manner that can give rise to synergistic savings, e.g. by using the same light source to both illuminate the area of interest and light the side emitting optical fibres.

The at least one light source may be configured to generate light or comprise a light emitter. The at least one light source may be or comprise a light emitting diode (LED). The at least one light source may be or comprise at least one of: a laser; a diode laser; a diode-laser-pumped solid-state laser. Optionally, at least some or all of the light for the light projection system may be provided via the at least one optical fibre, e.g. from a surface or other remote location. In this way, the at least one optical fibre may act as the light source or may provide light to the light source. The light may be modulated to carry a message or information. The light modulation may be visible directly by eye, for example as in the case of a general warning message. Additionally or alternatively, an optical receiver may be provided for decoding the modulated message for presentation to a user. In which case, the light modulation may be visible or invisible to the eye.

The umbilical may include at least one of: a tube or hose; a cable for supplying power; a communications link, e.g. for carrying image or video data from the camera. The at least one tube or hose may be provided for supplying gas, for example air, or fluid, for example water. The optical fibre or optical fibre bundle may be wound round or intertwined with one or all of the tube or hose, the cable and the communications link.

The assembly or illuminator may comprise a housing, such as a waterproof or water resistant housing. The housing may be pressurised. The housing may comprise a window, such as a clear or transparent window. The window in the housing may be considered as one of the optical elements. The illuminator may be configured to project the light, e.g. the beam of light, out of the illuminator via the window into the environment surrounding the illuminator. The at least one light source and one or more of the optical elements and optionally also the camera may be contained within the housing.

The optical connection may be provided for pressing the end of the fibre or fibre bundle against the optical connection to provide a butt coupled optical connection. The illuminator may be configured to emit or project the light, e.g. the beam of light, from the illuminator in a first direction, and may be configured to provide light to the at least one optical fibre along a different direction. The optical connection may be provided at an opposite end of the housing to the window from which the light, e.g. the light beam, is projected. The housing may be flared or outwardly tapered at one or both ends. The housing may be cylindrical. The window may be provided in one of the ends of the housing, e.g. in one of the flared or outwardly tapered ends. The optical connection and/or the power connector may be provided in the other end of the housing, e.g. in the other of the flared or outwardly tapered ends. The housing may be in the shape of a diabolo. The power connector and/or the optical connection may comprise waterproof or shuttered connections. A controller may be provided for controlling an output of the at least one light source. The controller may be adapted to cause flashing and/or a change in colour of the light emitted. The controller may be coupled between the power connector and the at least one light source.

According to a second aspect of the present disclosure is a helmet, such as a diver's helmet, comprising at least one assembly of the first aspect. The helmet may be a waterproof helmet. The helmet may comprise a power supply or power supply connector for connecting to the power connector of the assembly, e.g. for providing electrical power for the at least one light source and/or the controller of the assembly. The assembly may be mounted or mountable on the top or to one or both sides of the helmet. The illuminator of the assembly may be configured to project the light, e.g. the beam of light, to the front of the helmet, e.g. to illuminate an area of interest in front of the helmet. The assembly may be configured such that the at least one optical fibre and/or the umbilical extends upwardly and/or rearwardly of the helmet and/or the assembly.

According to a third aspect of the present disclosure is a vehicle, such as an underwater vehicle, e.g. a remotely operated vehicle (ROV), comprising at least one assembly of the first aspect.

It should be understood that the features defined above in accordance with any aspect of the present invention or below in relation to any specific embodiment of the invention may be utilised, either alone or in combination with any other defined feature, in any other aspect or embodiment of the invention. Furthermore, the present invention is intended to cover apparatus configured to perform any feature described herein in relation to a method and/or a method of using or producing or manufacturing any apparatus feature described herein. Brief Description of the Drawings

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

Figure 1 is a side-view of an illuminator;

Figure 2 is a view of the front of the illuminator of Figure 1 ; Figure 3 is a rear end view of the illuminator of Figure 1 ;

Figure 4 is a cut-away cross sectional view of the illuminator of Figure 1 ;

Figure 5 is a schematic representation of an alternative illuminator comprising a light rope umbilical system;

Figure 6 is a view of a fibre-bundle as incorporated within the umbilical;

Figure 7 is a side view of an individual fibre of a light rope for use in the system of Figure 5;

Figure 8 is a view of a fibre bundle showing helical pitch;

Figure 9 is an end view of bundle showing arrangement of individual fibres and sleeving;

Figure 10 is a perspective view of an alternative illuminator;

Figure 11 is a side view of the illuminator of Figure 10;

Figure 12 is a front view of the illuminator of Figure 10;

Figure 13 is a rear view of the illuminator of Figure 10;

Figure 14 is a different perspective view of the illuminator of Figure 10;

Figure 15 is another different perspective view of the illuminator of Figure 10;

Figure 16 is a side view of the illuminator of Figure 10;

Figure 17 is a side cross sectional view of an assembly comprising a camera and a side emitting optical fibre umbilical;

Figure 18 shows a diver helmet with the illuminator of Figure 10 mounted to it;

Figure 19 shows an alternative view of the diver helmet of Figure 18 with the illuminator of Figure 10 mounted to it;

Figure 20 shows an underwater vehicle with the illuminator of Figure 10 mounted to it; and

Figures 21 to 24 show the umbilical in use in various operational environments. Detailed Description of the Drawings

Figures 1 to 5 show an illuminator 5 according to the invention. The illuminator is configured with a light projection system 10 for projecting a directed beam of light in a first direction (indicated as a forward direction) and an optical fibre connector 12 at a different end or side of the illuminator 5 for connecting to one or more side emitting optical fibres 15 that form a light rope that is comprised in an umbilical 20. The illuminator 5 also comprises a single common power connector 25 for connecting to a power supply. The single common power connector 25 provides electrical power for use by the light sources 40a, 40b that provide the illumination for both the light projection system 10 and for the one or more side emitting optical fibres 15.

The illuminator comprises a housing 30 that houses the components of the light projection system 10, control electronics 35 (see Figures 4 and 5) and the means for lighting the optical fibres 15. In the example shown in Figures 1 to 5, the housing 40 is in the form a diabolo shaped housing, having outwardly flared ends and a cinched in middle section. This arrangement may advantageously provide improved illumination with the light projection system 10 and more area in which to provide the power connector 25 and the optical fibre connector 12, but at the same time is easy to handle and mount.

In one embodiment of the illuminator 5, as shown in Figure 4, the light projection system 10 is formed by a light source 40a, such as a light emitting diode (LED), an optical element in the form of a reflector 45 for reflecting light from the light source towards a transparent window 50 in the housing 30. The transparent window 50 is another optical element and forms a lens that focuses or reduces the divergence of the light emitted through the window 50. It will be appreciated that the window receives light both directly from the light source 40a and also reflected light from the reflector 45. In this way, the light projection system 10 is configured to form and project a beam of light out from the window 50. In particular, the light emitted by the light source 40a is formed into a beam by optical components in the form of the reflector 45 and the lens properties of the window 50 in order to maximise the light directed out of the window and to focus or reduce the divergence of the light. The beam of light illuminates an area of interest in front of the illuminator 5. For example, when the illuminator 5 is mounted on a diving helmet or other helmet, the window 50 generally faces the front of the helmet so that the area in front of the wearer is illuminated by the light projection system 10 of the illuminator 5. It will be appreciated that as the wearer moves their head and thereby the helmet, the area of illumination also moves correspondingly.

A further light source 40b comprising one or more LEDs for providing light to the optical fibres 15 is also provided within the housing 30. The illuminator 5 comprises a further reflector 55 for reflecting at least some of the light emitted by the further light source 40b towards the optical fibre connector 12. The optical fibre connector 12 is provided in another (in this example opposite) end or side of the housing 30 to the window 50 so that light is emitted from the optical fibre connector 12 in a different direction to the light emitted from the light projection system 10 via the window 50. The optical fibre connector 12 comprises a transparent window 60 and a waterproof locking connector 65 such as a gasket sealed screw fit connector (or any other suitable secure, selectively releasable, waterproof optical fibre connector known in the art). The locking connector 65 is configured to selectively connect to a corresponding connector on the umbilical 20 so as to hold ends of the optical fibres 15 in position facing and abutting the transparent window 60. In this way, light from the further light source 40b is provided to the transparent window 60 of the optical fibre connector 12 both directly and via reflection from the reflector 55. When the optical fibres 15 comprised in the light rope in the umbilical 20 are connected to the optical fibre connector 12, the light emitted from the transparent window 60 is conveyed into and along the optical fibres 15 wound into the light rope that is comprised in the umbilical 20. Since the optical fibres 15 are side emitting leaky fibres, the light is emitted along the length of the optical fibres 15 in a continuous manner, i.e. not only at discrete locations.

The illuminator 5 comprises the control electronics 35 for controlling operation of the light sources 40a, 40b. In particular, the illuminator 5 comprises the single common power connector 25 provides electrical power for use by the light sources that provide the illumination for both the light projection system 10 and for the one or more side emitting optical fibres 15. The control electronics 35 controls the power supplied to the light sources 40a, 40b in order to selectively turn them on or off responsive to a user selection. The common power connector 20 comprises a suitable waterproof power connector known in the art. Advantageously, the power connector 20 is configured to connect to a diver's helmet light power connector and the illuminator 5 is configured to mount to a diver's helmet, e.g. in replacement of the diver's helmet light. In this case, the light projection system 10 serves the role of the helmet light, supplying a bright beam of light into an area of interest generally in front of the wearer (i.e. the diver). The optical fibres 15 that provide the light for the light rope that is comprised in the umbilical 20 are illuminated either by their own light sources 40b that draw their power from the same helmet connector as the light sources 40a of the light projection system 10 or receive their light from a common light source 40 shared with the light projection system 10 (see e.g. Figure 5). As such, whilst the example of Figures 1 to 4 comprises two sets of light sources 40a, 40b, one for the light projection system 10 and the other for lighting the light rope of the umbilical 20, which provides maximum light and independent operation for each, it will be appreciated that in alternative embodiments a common light source 40 (see Figure 5) that is shared by the light projection system 10 and the light rope could be used, e.g. in order to provide power savings. In embodiments with more than one light source 40a, 40b, one of the light sources 40a, 40b could optionally be a different colour to the other, e.g. the light source 40a for the light projection system 10 is a white light source whilst the light source 40b for providing light to the optical fibre connector 12 is a coloured light source, e.g. green or blue. Optionally, one or each of the light sources 40, 40a, 40b comprises a multicolour light source, such as a RGB light source that is capable of selectively producing red, green and blue light from the same light source. Alternatively coloured filters could be provided between the light source 40 or one or both of the light sources 40a, 40b and the optical fibre connector 12 and/or the window 50. In this way, different coloured light can be provided to each of the light projection system 10 and the optical fibre connector 12, e.g. so that green, blue or other coloured light is provided to the optical fibres 15 whilst white or differently coloured light can be projected by the light projection system 10. In addition, although optical elements in the form of reflectors and windows 45, 50, 55, 60 are used to focus or reduce the divergence of the light form the light source(s) 40a, 40b, it will be appreciated that other arrangements of suitable optical elements could be used to provide the same effect, e.g. by using a collimator, a total internal reflector, one or more lenses, a non-imaging concentrator such as a conical or frusto-conical concentrator, and/or the like. Optionally, the optical elements can comprise or be comprised in a variable focus arrangement.

The illuminator 5 of the present invention provides several important advantages. The illuminator is easy to retrofit to a diver's helmet, as it can be simply interchanged with an existing helmet light using a single connector. Furthermore, since the power for the light source for the umbilical 20 light rope is drawn from the helmet light connection, no electrical power needs to be transmitted along the umbilical from the surface. In addition, there are synergistic energy savings that can be achieved by providing at least one common light source for the light projection system 10 and the optical fibres 15 that form the light rope in the umbilical 20. As indicated above, Figure 5 shows an alternative example of an illuminator 5, that is substantially similar to that of Figures 1 to 4, other than a single common light source 40 is provided to provide the light for both the optical projections system 10 to form the projected light beam and also to illuminate the optical fibres 15. In addition, different optical elements such as lenses are provided between the light source 40 and the window 50 of the optical projection system and between the light source 40 and the window 60 of the optical fibre connector 12 in order to focus or constrain the dispersion of light from the light source 40.

The umbilical 20 is also shown in more detail in Figure 5 and 6 (although it will be appreciated that the umbilical 20 shown in these Figures is equally applicable to the illuminator 5 shown in Figures 1 to 4). This has various conventional umbilical parts 70 that are wound together, such as a gas hose and a power line, as best seen in Figure 6. In addition, the umbilical 20 includes a bundle 75 comprising a plurality of the side- emitting optical fibres 15. The side-emitting optical fibres 15 provide a distributed source of light that allows the umbilical 20 to be lit along its length, thereby providing a guide-path as well as general illumination of the sub-sea environment within which the diver or divers are working.

For the purpose of illuminating the fibre bundle 75 the light source 40 in the form of a light emitting diode (LED) 40, for example, is powered by the control electronics 35. The LED 40 is enclosed within the compact watertight housing 30, which is located adjacent to an umbilical interconnect-interface 85. Radiation from the LED 40 passes through an optical coupling arrangement 90 that transforms the spatial characteristics of the primary radiation from the LED 40 to optimize its coupling into the optical fibres 15 of the fibre-bundle 75. The radiation then passes through the window 60 that is mounted on a water-tight seal 95 in the side of the watertight housing 30, before entering the fibre-bundle 75. The prepared ends of the optical fibres 15 making up the bundle 75 are held in compression by the locking connection 65 so as to be in contact with and hence butt-coupled to the outer surface of the window 60. The optical arrangement described is such that this location of the fibre-ends also optimizes the coupling of the radiation into the optical fibres 15. Whilst any LED 40, 40a, 40b may be used, in a preferred example, the LED 40 or 40b generates light in the green or blue spectral regions. As detailed above, in a preferred arrangement the light projected by the light projection system 10 is preferably white whilst the light received by the optical fibres 15 is preferably green or blue, which can be achieved by providing appropriate LEDs 40, 40a and/or 40b or by using filters, etc. Typically for an electrical input power to the LED 40 of 12W, the optical output power from the LED 40 in the green spectral region is of the order of 400 mW, and the coupling efficiency for this radiation into the optical fibres 15 is of the order of 23-28% The fibre bundle 75 may be made up of any number of optical fibres 15. In a preferred example fourteen individual plastic fibres 15 are used with a core diameter of 0.74mm and refractive index of 1.49, and with an outer cladding of wall thickness 0.06mm and refractive index 1.40, see Figure 7. As a specific example these optical fibres 15 could be any suitable plastic optical fibre. The optical fibres 15 are wound in the tight helical bundle 75 with a pitch of 10cm, see Figure 8. The packing of the optical fibres 15 as appears at each end of the bundle 75 is of the form of four central optical fibres 15 surrounded by ten other fibres 15, all encased within an outer sheath 100 that is transparent to the light that is to be used, see Figure 9. The plastic sheath 100 has a nominal wall thickness of 0.85mm, the walls of the sheath 100 being transparent to the visible radiation. Typically the fibre bundle 75 would be of length 100m, compatible with a standard umbilical 20.

The fibre-bundle 75 geometry of Figure 9 typically experiences a loss of the order of 5%/m due to radiation escaping through the side walls of the optical fibres 15 as required, this being determined largely by the inherent transmission losses of the fibre but also influenced by both the tightness of winding and the compression of the bundle 75 by the outer sheave 100. Both these aspects are controllable for the purposes of optimization during the manufacturing process. For the specifications given above satisfactory illumination and brightness of emission is attained for fibre lengths up to 100m. The watertight housing 30 also contains a back-up battery 105 with a built in charger circuit 110. This allows remote operation in the event of no mains electrical supply. The system in normal operation requires 12W @18V DC.

Under normal operating conditions the illuminator 5 is powered by the diver's electrical supply via the connection for the helmet light but with reserve power available via the battery 105 if required. This arrangement significantly increases illumination levels in the vicinity of the diver(s), and provides back-up through built-in redundancy in the event of fibre damage or light source failure. It can also significantly increase umbilical 20 operational length.

The light injected into the fibre bundle 75 may be modulated so as to carry a message or information. The modulation of light may be such that it can be seen directly by eye, for example in the case of a general warning message. Alternatively or additionally, an optical receiver capable of decoding the modulated message may be provided for subsequent oral, visual or other mode of presentation to divers or other relevant parties.

The control electronics 35 cause the light emitted from the fibres 15 to be altered. For example, the light could be caused to flash on and off. This could be used by divers in emergency situations to provide a general warning, for example, highlighting a change in operational conditions or a specific diver in difficulty, thereby making colleagues immediately aware of a changed state. A lit and flashing umbilical 20 could speed up rescue operations in identifying the diver at risk. The assembly in the form of the illuminator 5 shown in Figures 1 to 5 is only exemplary and it will be appreciated that other forms of assemblies or illuminators could be used. An example of an alternative assembly comprising an illuminator 505 is shown in Figures 10 to 16. The illuminator 505 is substantially similar to that of the illuminator 5 shown in Figures 1 to 5, but a housing 530, power connector 525 and optical fibre connector 512 of the illuminator 505 take slightly different forms. For example, the housing 530 of the illuminator 505 of Figures 10 to 16 is generally cylindrical, in contrast to the diabolo form of the housing 30 of the illuminator 5 of Figures 1 to 5. In addition, in the embodiment of Figures 10 to 16, the power connector 525 extends rearwardly from a protruding portion at the top of the housing 530. The power cable that connects to the power connector 530 and a side emitting optical fibre 515 are entwined in an umbilical 520 that extends from the rear of the illuminator 505, whilst the light is emitted forwardly from a transparent window 550 at the front of the illuminator 505, which is operable to illuminate an area of interest. Figure 17 shows an example of an assembly 1005 that comprises a camera in the form of a digital imaging device 1 100 such as a CCD or CMOS or photodiode based imaging sensor which is located generally in place of the light source 40a in the embodiment of Figures 1 to 5. The imaging device 1 10 images the area in front of the assembly 1005 through a transparent window 1050. The other components are generally similar to those of the embodiment of Figures 1 to 5. Although Figure 17 shows the imaging device 1 100 in place of the light source 40a of Figures 1 to 5 in other embodiments, the imaging device 1 100 may be provided in a combined illuminator, camera and side emitting optical fibre assembly, e.g. the imaging device 1 100 may be provided in addition to the light source 40a. In this case, the umbilical 520 may carry a data feed line to carry digital image data from the digital imaging device 1 100 in addition to the side emitting optical fibre 515. In another embodiment, the data feed line and the optical fibre 515 can be combined and the image data transmitted using optical communication using the optical fibre 520.

Figures 18 and 19 show the illuminator 505 in use as a diver's helmet light combined with the side emitting optical fibre 512 umbilical 520. Figure 20 shows the illuminator 505 in use in an underwater vehicle (in this particular example an ROV) combined with the side emitting optical fibre 512 umbilical 520. Although figures 18 to 20 show the illuminator 505 mounted on the diver's helmet and ROV, it will be appreciated that it could equally be the illuminator 5 of Figures 1 to 5 or the camera and side emitting optical fibre umbilical assembly or camera, illuminator and side emitting optical fibre umbilical assembly of Figure 17. Figures 21 to 24 show various different operational environments in which the umbilical

20 and illuminator 5 and/or imaging device 1100 of the invention could be used. Figure

21 shows the umbilical 20 being provided between the surface and a subsea location (surface-air diving application), whereas Figure 22 shows the umbilical 20 being provided between two or more subsea locations for example between a diving bell and individual divers (saturation diving). The umbilical may also be used in connection with remote operating vehicles (ROVs), an example of which is shown in Figure 23. However, it will be appreciated that the arrangements in which the umbilical 20 and illuminator 5 and/or imaging device 1 100 could be used. For example, the ROV arrangement shown in Figure 23 is often used for smaller ROVs, such as those used for observation and other light tasks. However, larger ROVs, such as work class ROVs, can be used with a tether management systems (TMS), such as that shown in Figure 24. The tether management system sits between the ROV and the vessel and acts to manage the umbilical 20 / tether between the ROV and the vessel. Particularly, the TMS is operable to effectively lengthen or shorten the overall umbilical / tether as required. In this respect, as shown in Figure 24, the TMS based system is similar in configuration to the diving bell arrangement shown in Figure 22, but with the TMS in place of the diving bell and an ROV in place of the diver. The TMS based system may comprise a first tether / umbilical between the vessel on the surface and the TMS and a second tether / umbilical between the TMS and the ROV or alternatively comprise a single tether / umbilical 20 extending from the ROV via the TMS to the vessel. In either case, one or both of the umbilicals / tethers can be wound or otherwise stowable in, and configured for deployment from, the TMS. The single umbilical 20 or one or both of the first and/or second umbilicals / tethers may comprise at least one side emitting optical fibre 15. In addition, the TMS itself may be lit or lightable using the at least one side emitting optical fibre, e.g. when it is spooled, stowed or otherwise provided on the TMS in a manner that is visible from the outside of the TMS.

Embodiments described above provide a safe, low-power illuminator 5 that provides both a light projection system 10 that illuminates the area in front of the diver so that the diver has visibility of their working area but that also provides an umbilical 20 that comprises a light rope in the form of a bundle 75 of optical fibres 15 that is continuous, flexible and distributed along the full length of the umbilical 20. The illuminator 5 can be used in any underwater environment for example subsea and any inland waters including lakes, rivers, lochs, harbours, docks, canals and all other types of waterways. The illuminator 5 requires no electrical power within the structure of the umbilical 20 itself and can provide high intensity light at the peak eye response, as well as light of other colours if required. It provides a clear return path back to safety resulting from the distributed and continuous nature of the light emitted along the length of the umbilical 20. It provides visual information between divers as to their relative locations in the subsea environment, as well as general illumination of the underwater working environment thereby increasing the visual acuity of operatives so improving both their safety and their efficiency of working.

Importantly, the illuminator 5 can be easily retro-fitted into a connection for a standard diver's helmet light and provides both a light beam that illuminates the diver's working area and the light emitting umbilical 20 that is illuminated via the side emitting optical fibres 15.

A skilled person will appreciate that variations of the disclosed arrangements are possible without departing from the invention. For example, although the invention is described with reference to a bundle 75 of fibres 15, a single fibre or a light pipe may be used. Equally, the light source 40 or light sources 40a, 40b may be any suitable device, such as a filament / halogen / thermal resistance light, or a laser, for example a diode laser, such as a diode-laser-pumped solid-state laser. The wavelength of the radiation generated by the laser may be shifted in frequency by some optically nonlinear technique so as to be suited to the purpose. Whilst green is a preferred colour any spectral colour may be used. In embodiments where a common light source 40 is provided that provides light for both the light projection system 10 and the side emitting optical fibres 15 used to light the umbilical 20, a white light could be preferably but not essentially used. Accordingly the above description of the specific embodiment is made by way of example only and not for the purposes of limitation. It will be clear to the skilled person that minor modifications may be made without significant changes to the operation described.

Claims

1. An assembly comprising an illuminator and/or at least one camera, the assembly further comprising or being configured to connect to at least one side emitting optical fibre, wherein the at least one side emitting optical fibre is configured or configurable to receive at least some of the light from one or more light sources and transmit the light along at least part or all of the length of the at least one optical fibre.

2. The assembly of claim 1 , wherein the illuminator is configured to emit or project light to illuminate an area outwith the illuminator, and wherein the illuminator comprises or is configured to connect to the at least one side emitting optical fibre.

3. The assembly of claim 1 or claim 2, wherein the at least one light source is comprised in the illuminator and the at least one side emitting optical fibre receives at least some of the light from one or more or each of the light sources.

4. The assembly of claim 3 comprising a power connector or feed, connected to or for connecting to a power supply, the power connector being configured to supply electrical power to the at least one light source.

5. The assembly of any preceding claim, wherein the at least one side emitting optical fibre is comprised in a diver's umbilical or in the umbilical of an underwater vehicle.

6. The assembly of claim 5, wherein the umbilical is configured to transmit light along at least part or all of the length of the umbilical and optionally also convey power and/or data representing images collected by the camera.

7. The assembly of any preceding claim, wherein the at least one side emitting optical fibre is selectively lockable or attachable or connectable / disconnectable from the assembly, e.g. from the illuminator.

8. The assembly of any preceding claim, wherein the at least one optical fibre is configured to receive light from at least one or each of the same light sources that provide light to the optical element that projects light from the illuminator.

9. The assembly of any of claims 1 to 7, wherein the at least one optical fibre is configured to receive light from at least one of the light sources that is different from the light sources that provide light to the optical element.

10. The assembly according to any preceding claim, wherein the at least one optical elements comprise one or more of: a lens, a total internal reflector, a mirror or other reflector, a collimator and/or a transparent window.

1 1. The assembly according to any preceding claim, wherein at least one of the optical elements or a combination of the optical elements are configured to control, constrain or reduce divergence of the light emitted by at least one or each of the light sources and/or to focus the light emitted by at least one or each of the light sources.

12. The assembly according to any preceding claim, comprising or being configured to connect to a plurality of side emitting optical fibres that are intertwined to form a bundle or light rope, the bundle or light rope comprising a transparent sheath that at least partially encloses the optical fibres and the side emitting optical fibres are configured to emit light along the length of the light rope or bundle.

13. The assembly according to any preceding claim, wherein the side emitting optical fibre(s) are configured to emit a continuous light along the length of the optical fibre.

14. The assembly according to claim 5 or any claims dependent thereon, wherein the power connector is configured to connect to a corresponding power supply connector in a diver's helmet or the underwater vehicle.

15. The assembly according to any preceding claim wherein

the assembly is configured for use underwater; and/or

the illuminator and/or camera are provided in a waterproof housing.

16. A helmet comprising at least one illuminator according to any of claims 1 to 15.

17. The helmet of claim 16, wherein the helmet is a diver's helmet.

18. The helmet of claim 15 or claim 16, wherein the helmet comprises a power supply or power supply connector for connecting to the power connector of the illuminator so as to provide electrical power for the at least one light source of the illuminator, in use.

19. The helmet of any of claims 16 to 18, wherein the illuminator is mounted or mountable on the top or to one or both sides of the helmet.

20. The helmet of any of claims 16 to 19, wherein the illuminator is configured to project the beam of light to the front of the helmet to illuminate an area of interest in front of the helmet and the illuminator is configured such that the at least one optical fibre and/or the umbilical extends upwardly and/or rearwardly of the helmet and/or the illuminator.

21. An underwater vehicle comprising the assembly of any of claims 1 to 15.