TECHNICAL FIELD

The present invention relates to detection of laser illumination. In particular but not exclusively the invention relates to the detection of laser illumination during the installation of fibre optic cables using a passive detector device.

BACKGROUND

It is known to provide fibre optic cables for carrying communication signals carried by infrared (IR) radiation. The IR radiation may have a wavelength of around 1080nm or greater. It is difficult or impossible to detect such radiation with the naked eye.

In order to assist engineers installing fibre optic cables, it is known to provide a device for detecting laser radiation (or ‘illumination’) in the form of a card formed from a sheet of plastics material and having a phosphor layer provided on one face. When exposed to IR radiation of a predetermined wavelength or range of wavelengths, the phosphor emits visible light. Accordingly, a user may determine whether a fibre optic cable is ‘live’ or ‘lit’ by presenting the card to an exposed end of the cable, with the side of the card bearing the phosphor coating facing toward the exposed end and in an expected path of radiation from the exposed end.

FIG. 1 is a schematic illustration of a known passive IR radiation detection device 10. The device has a substrate 11 formed from a plastics material and a phosphor coating 12 deposited on a front major surface thereof. The device 10 is shown with the front major surface facing an exposed free end 5E of a fibre optic cable 5. A beam L of IR radiation generated by a laser source S emanates from the exposed free end 5E and is incident upon the phosphor coating 12, which in turn emits visible light E. A user holding the device 10 is required to view the front of the device, for example along the direction of arrow V, thereby to see the visible light E emitted. If visible light is present, the user is able to determine that the cable is lit.

It is known to employ infra-red radiation of different wavelengths in fibre optic cables. Furthermore, the radiation may be carried at different power levels. Radiation of relatively high power levels may be capable of substantial damage to exposed skin and/or eyes of a user. These higher power levels can also damage (e.g., burn or melt) cards made with plastic substrates.

It is an aim of the present invention to address one or more disadvantages associated with the prior art.

SUMMARY OF THE INVENTION

Embodiments of the present invention may be understood with reference to the appended claims.

Aspects of the present invention provide a device and a method.

In one aspect of the invention there is provided a detector device, optionally a passive infrared (IR) detector device, comprising: a first portion arranged to receive IR illumination incident upon the device; and a second portion arranged to emit visible light from the device in response to the IR illumination, wherein: the first portion comprises a wavelength-selective filter portion arranged to pass IR radiation of a predetermined wavelength or range of wavelengths; and the second portion comprises a light-emitting portion arranged to emit visible light responsive to illumination with IR radiation, wherein the second portion is provided downstream of the first portion with respect to a path of a beam of IR radiation incident upon the first portion.

Embodiments of the present invention have the advantage that a passive IR detector may be provided that is arranged to emit visible light responsive to radiation of a predetermined wavelength of range of wavelengths. The device is thereby able to discriminate between incident radiation of different wavelengths.

It is to be understood that beams of IR radiation of different wavelengths may be carried by the same fibre optic cable. The power level of the beams may be different. In some systems, the higher power beams are of longer wavelength, e.g., 1400nm or greater. In some systems, the higher power beams may be in the range 1400-2000nm, optionally in the range 1450-2000nm. The lower power beams may be in the range of from around 1080nm but less than 1400nm. It is desirable to discriminate between the frequencies when installing or maintaining fibre optic cables. Thus, an engineer may wish to determine whether a fibre optic cable is currently being illuminated by a beam of IR radiation of high intensity. Current detector devices are not capable of enabling an operator to determine whether a beam is a beam of relatively high intensity or a beam of relatively low intensity.

It is to be understood that field engineers may be permitted to perform one or more predetermined or agreed installation or maintenance operations on a fiber optic cable, for example the splicing of two fibre optic cables together, when a beam of lower power (i.e., lower IR wavelength) is passing through the cable but not when a beam of higher power (i.e., higher IR wavelength) is passing through the cable. Accordingly, the user may perform the one or more predetermined or agreed installation or maintenance operations on the cable provided the user has determined that a beam of higher power is not present.

Embodiments of the present invention allow a user such as a field engineer to determine whether a beam of high intensity IR radiation is present in a fibre optic cable by discriminating between higher and lower intensity IR beams on the basis of wavelength. By providing a detector device according to an embodiment of the present invention, in which the first portion is arranged to block beams of lower IR wavelength and pass only the beams of higher IR wavelength, optionally to block IR radiation having a wavelength below 1400nm and to pass IR radiation having a wavelength in the range 1400-2000nm, optionally in the range 1450-2000nm, the user is able to determine whether or not a beam of IR radiation of relatively high intensity is currently being carried by the fibre optic cable based on a determination whether visible light is being emitted from the device by the second portion when the first portion of the device is placed in an expected path of IR radiation emitted by the fibre optic cable.

By providing a passive detector device capable of distinguishing between the low and high power beams of IR radiation, personnel working with fibre optical cables in systems configured to transmit IR radiation along the cables may enjoy enhanced levels of safety. Devices according to embodiments of the present invention facilitate convenient, uninterrupted use since they require no power supply, being passive devices. In some embodiments, the device does not have any moving parts, is readily portable and capable of single-handed manipulation in use.

It is to be understood that it is challenging to produce passive light emitting portions that are responsive to particular ranges of IR wavelength, such as IR radiation having a wavelength of 1400nm or greater but not IR radiation of wavelength less than 1400nm. Embodiments of the present invention enable a light emitting portion to be used that is responsive to IR radiation having wavelengths in the range of both the relatively low power, shorter wavelength beams and the relatively high power, longer wavelength beams, by using a wavelength-selective filter portion upstream of the light emitting portion rather than by adapting the light emitting portion itself to be responsive only to the longer wavelength beams.

Optionally, the first portion of the device comprises a filter layer provided on an I etransmitting substrate.

By IR-transmitting is meant that the substrate allows IR radiation to pass therethrough.

Optionally, the first portion is arranged to provide a long pass filter function in respect of incident IR radiation.

Optionally, the IR-transmitting substrate has a first, upstream major surface and a second, downstream major surface facing the second portion, the filter layer being provided on the second major surface.

Optionally, IR radiation incident on the device passes through the IR transmitting substrate before passing through the filter layer.

Optionally, the first major surface is provided with an anti-reflection (AR) coating thereon.

This feature has the advantage that reflection of IR radiation emitted by a fiber-optic cable may be reduced, thereby reducing a risk that IR radiation is scattered by the device and incident on personnel in the vicinity of the cable.

Optionally, the substrate comprises or consists of a glass material, quartz or sapphire.

It is to be understood that IR-transmitting substrates that have a melting point in excess of 500C may be useful in some embodiments.

In some embodiments, IR-transmitting substrates that have a melting point of 1000C or more may be advantageous.

In some embodiments, IR-transmitting substrates that have a melting point of 1350C or more may be advantageous. Optionally, the first portion is arranged to block IR radiation having a wavelength of less than substantially 1400nm.

Thus, the first portion may be arranged to allow IR radiation having a wavelength of substantially 1400nm or greater to pass through to the second portion. It is to be understood that the second portion may be arranged to emit visible light responsive to IR radiation of a range of wavelengths including wavelengths below and above 1400nm. However, radiation of wavelength below 1400nm may be blocked by the first portion, rendering the device responsive only to IR radiation having a wavelength of substantially 1400nm or greater.

In some embodiments, the first portion may be arranged to transmit IR radiation having a wavelength in the range from 1400nm-2000nm, optionally 1450nm-2000nm, and to block IR radiation having a wavelength below 1400nm. Optionally, the first portion is arranged to block radiation having a wavelength in the range from UV to 1350nm such that, in use, ambient UV radiation does not cause the second portion to emit light in response to the visible or UV radiation incident on the device 100. In some embodiments, the first portion may be arranged to block radiation having a wavelength in the range from around 400nm to 1350nm, optionally around 300nm to 1350nm, optionally around 200nm to 1350nm. Other ranges may be useful in some embodiments.

Optionally, the second portion comprises a light emitting layer provided on a substrate comprised by the second portion.

Optionally, the substrate has a first, upstream major surface facing the first portion and a second, downstream major surface, the light emitting layer being provided on the first major surface.

It is to be understood that in the case that the light emitting layer is provided on the first major surface of the substrate of the second portion, the substrate should be a substrate that is transmits the wavelength or at least a portion of the range of wavelengths of visible light emitted by the light emitting layer.

Optionally, the light emitting layer comprises a phosphor material arranged to emit visible light in response to irradiation with IR radiation.

Other light emitting materials may be useful for the light emitting layer. Optionally, a gap portion is provided between the first portion and the second portion in a path of IR radiation, the gap portion allowing IR radiation entering the gap portion from the first portion to be transmitted therethrough.

Optionally, the gap portion has a refractive index value that is less than a refractive index of the IR-transmitting substrate of the filter layer and the substrate on which the light emitting layer of the second portion is provided.

It is to be understood that the air gap may be provided for correct operation of the filter in some embodiments. The filter may be designed based on the relative refractive indices of the filter materials and air, which has a refractive index of 1.0. By having an air gap, the filter thereby operates as designed, i.e., the filter passes the intended range of wavelengths and blocks others.

Optionally, the gap portion is an air gap.

Optionally, the gap portion comprises a spacer portion between the first and second portions and in abutment therewith thereby to space the first and second portions and provide the air gap.

The spacer portion may comprise a frame portion that defines an aperture through which IR radiation may pass from the first portion to the second portion.

Optionally, the device comprises a planar portion having a first side and a second side opposite the first side, and IR illumination incident upon the device and received by the first portion is received from the first side of the device and visible light emitted from the device by the second portion is emitted from the second side of the device.

This feature has the advantage that the device may be made in a relatively compact, substantially flat form that is readily portable and usable by a user.

Furthermore, a user may view the device from an opposite side of the device to that which is illuminated by IR irradiation.

Alternatively, the visible light emitted from the device by the second portion may be emitted from the first side of the device, for example by reflection by means of a reflector. The arrangement may be such that the light exits the device from a location different from that at which the first portion receives incident IR radiation. Alternatively or in addition light may exit from the device at a location that is substantially the same as that at which the first portion receives incident IR radiation.

Optionally, the planar portion is substantially flat.

The device may comprise a housing in which the first and second portions are provided.

Optionally, the housing comprises a substantially flat planar body in which the first and second portions are provided, the first portion being arranged to receive IR radiation incident on the housing from a first side thereof, the second portion being arranged to emit visible light from a second side of the housing opposite the first.

Optionally, the housing is in the form of an elongate wand.

In an aspect of the invention for which protection is sought there is provided a kit or system comprising: a device according to a preceding aspect; and a fibre optic cable, the kit or system optionally further comprising an IR radiation source, optionally a laser device.

In a further aspect of the invention for which protection is sought there is provided a telecommunications system comprising: a device according to a preceding aspect; a fibre optic cable; and an IR radiation source, optionally a laser device.

In a further aspect of the invention for which protection is sought there is provided a method of detecting infra-red (IR) radiation by means of a detector device, optionally a passive infrared (IR) detector device, comprising: receiving IR radiation incident upon the device; and emitting visible light from the device in response to the IR illumination received, wherein: the method comprises filtering the IR radiation incident upon the device to pass IR radiation of a predetermined wavelength or range of wavelengths; and subsequently causing the filtered IR radiation to be incident upon a light-emitting portion arranged to emit visible light from the device responsive to the IR radiation received by the device.

The method may comprise filtering the IR radiation by means of a filter layer provided on an IR-transmitting substrate. The filter layer may provide a long pass filter function in respect of incident IR radiation.

The method may comprise filtering the IR radiation to block IR radiation having a wavelength of less than substantially 1400nm.

Optionally, causing the filtered IR radiation to be incident upon a light-emitting portion comprises causing the filtered IR radiation to be incident on a light emitting layer provided on a substrate, the light emitting layer comprising a phosphor material arranged to emit visible light in response to irradiation with IR radiation.

The method may comprise presenting the device to a free end of a fibre optic cable whereby IR radiation is received by the device and visible light is emitted from the device responsive to the IR radiation received by the device.

In another aspect of the invention for which protection is sought there is provided a passive infra-red (IR) detector device, the device being arranged to receive IR illumination incident upon the device and to emit visible light from the device in response to the IR illumination, wherein the device is responsive to emit visible light in response to IR radiation of a predetermined wavelength or range of wavelengths and not IR radiation having a wavelength or range of wavelengths less than the predetermined wavelength or range of wavelengths, optionally not IR radiation, visible light or UV light having a wavelength or range of wavelengths less than the predetermined wavelength or range of wavelengths.

In another aspect of the invention for which protection is sought there is provided a passive infra-red (IR) detector device, the device being arranged to receive IR illumination incident upon the device and to emit visible light from the device in response to the IR illumination, wherein the device is responsive to emit visible light in response to IR radiation of a predetermined wavelength or range of wavelengths and not IR radiation having a wavelength or range of wavelengths greater than the predetermined wavelength or range of wavelengths. Within the scope of this application, it is envisaged that the various aspects, embodiments, examples and alternatives, and in particular the individual features thereof, set out in the preceding paragraphs, in the claims and/or in the following description and drawings, may be taken independently or in any combination. For example, features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

For the avoidance of doubt, it is to be understood that features described with respect to one aspect of the invention may be included within any other aspect of the invention, alone or in appropriate combination with one or more other features.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying figures in which:

FIGURE 1 is a schematic illustration of a known passive IR radiation detector device;

FIGURE 2 is a schematic illustration of a passive IR radiation detector device according to an embodiment of the present invention;

FIGURE 3 is a further schematic illustration of the passive IR radiation detector device of FIG. 2;

FIGURE 4 shows (a) a front side and (b) a back side of a passive IR radiation detector device according to an embodiment of the present invention in the form of a wand device;

FIGURE 5 shows (a) a back side of the passive IR radiation detector device of FIG. 4 and (b) a cross-sectional view of the device shown in (a) along line A-A in the direction of arrows B; and

FIGURE 6 shows a back side of a passive IR radiation detector device according to a further embodiment of the present invention in the form of a wand device.

DETAILED DESCRIPTION

FIG. 2 is a schematic illustration of a passive IR radiation detection device 100 according to an embodiment of the present invention. The device 100 has a has an optical structure that comprises a first portion 100a and a second portion 100b downstream of the first portion 100a with respect to a path of a beam of IR radiation through the device 100, in use.

The first portion 100a comprises a substrate 150 that transmits IR radiation of the wavelength or range of wavelengths that it is desired to detect. The IR-transmitting substrate 150 has a first, upstream major surface and a second, downstream major surface facing the second portion 100b. An anti-reflection (AR) layer 160 is provided on the first major surface of the IR-transmitting substrate 150 and a wavelength-selective filter portion in the form of a filter layer 140 is provided on the second major surface.

In the present embodiment, the AR layer 160 is a multilayer dielectric broad band IR AR coating tuned to provide <2% reflectance between wavelengths 1100-2000nm. Other values may be useful in some embodiments. In the present embodiment the AR coating is an alternating stack of zirconia and silicon dioxide layers. It is to be understood that other multilayer AR layers may be employed in some embodiments. Single layer AR layers may be employed in some embodiments. In the present embodiment the substrate 150 is a glass substrate 1mm thick but other IR-transmitting substrates may be used such as silicon, quartz or sapphire. Other thicknesses of substrate may also be used in some embodiments.

In the present embodiment, the filter layer 140 is deposited on the side of the substrate 150 opposite that having the AR layer 160. The filter layer 140 is also a dielectric coating that is tuned to the desired wavelength or wavelength range. In the present embodiment the filter layer 140 is arranged to block radiation having a wavelength in the range from UV to 1350nm and to transmit radiation at a transmission level greater than 90% for wavelengths in the range from 1450-2000nm. Thus, ambient sunlight, including UV and visible light are prevented from reaching the second portion 100b. In the present embodiment the transmission is around 50% at 1410 +/- 7nm. The filter layer 140 may be optimised for an air interface.

It is to be understood that other values of the range of wavelengths blocked by the filter layer 140 may be useful in some embodiments. Similarly, it is to be understood that other values of the range of wavelengths transmitted by the filter layer 140 may be useful in some embodiments.

The second portion 100b comprises a substrate 110 having a first, upstream major surface facing the first portion 100a and a second, downstream major surface. The first major surface has a light-emitting portion provided thereon in the form of a light emitting layer (120). The light emitting layer 120 is arranged to emit visible light in response to IR radiation transmitted by the first portion 100a. The substrate 110 is arranged to transmit the visible light emitted by the light emitting layer (120).

In the present embodiment the light emitting layer 120 is a layer of phosphor material of thickness 50 microns (urn) +/- 10% although other thicknesses may be useful in some embodiments. The phosphor material in the present embodiment is a doped yttrium oxysulphide (Y2O2S:Yb, Er) having ytterbium and erbium dopant. Other materials may be useful in some embodiments such as Y2O2S:Er. Other phosphors may be used provided they are able to convert IR radiation to visible light. Similarly, other light emitting materials may be used provided they are able to convert IR radiation to visible light.

The substrate 110 is a glass substrate in the present embodiment although other substrate materials may be useful in some embodiments such as quartz or sapphire. It is to be understood that the use of substrates able to withstand substantial heating may be important in some embodiments where relatively high power IR radiation is being employed. Accordingly, in some embodiments thermally stable substrate materials may be used such as glass, quartz or sapphire instead of plastics materials. In the present embodiment the glass substrate is 1mm in thickness but other thicknesses may be useful in some embodiments. The phosphor material may be deposited on the substrate by a sedimentation process from a solvent in some embodiments. Other deposition processes may be useful in some embodiments.

As shown in FIG. 2, the device 100 is arranged wherein IR radiation L in the wavelength range from 1450-2000nm emitted by a fibre optic cable 5 coupled to an I R radiation source S is transmitted by the first portion 100a to the second portion 100b where the IR radiation is incident on the light emitting layer 120. Visible light E emitted by the light emitting layer 120 is transmitted by light emitting layer substrate 110 and exits the device 100 where it may be viewed by a user. In the arrangement shown the source S comprises a laser source but other sources may be used in some embodiments.

As shown in FIG. 2 and FIG. 3 a gap portion 130 is provided between the first portion 100a and the second portion 100b in a path of IR radiation from the filter layer 140 to the second portion 100b, the gap portion 130 being arranged to transmit the IR radiation entering the gap portion 130 from the first portion 100a. In the embodiment of FIG. 2 the gap portion 130 comprises an air gap defined by a spacer element 132 (FIG. 3). The spacer element 132 is the form of an annular ring formed from a suitable material such as a polymer (e.g., polyimide or PET) or a foam or sponge material. In the embodiment of FIG. 2 and FIG. 3 the spacer element 132 has a thickness of around 0.2mm such that the first and second portions have an air gap of substantially 0.2mm therebetween. Other thicknesses of air gap may be useful in some embodiments such as 0.5mm or any other suitable thickness. The spacer element 132 provides a frame that defines an aperture through which IR radiation may pass from the first portion to the second portion.

It is to be understood that the air gap is provided for correct operation of the filter layer 140 in the embodiments described. The filter layer 140 is designed based on the relative refractive indices of the filter materials used and air, air having a refractive index of 1.0. By providing an air gap, the filter layer 140 operates as designed, i.e., the filter layer 140 passes the intended range of wavelengths and blocks others as described above.

The first and second portions 100a, 100b, together with the spacer element 132, are held in a housing 105 in the form of a wand (FIG. 3-5). The wand 105 provides a mechanical housing for the first and second portions 100a, 100b and spacer element 132, holding the portions 100a, 100b in a fixed position with the spacer element 132 therebetween.

FIG. 4(a) is a 3D view of the device 100 from a side at which IR radiation L to be detected is incident upon the device 100. FIG. 4(b) is a 3D view of the device 100 from the side opposite that shown in FIG. 4(a), being the side from which visible light generated by the light emitting layer 140 exits the device 100. As shown in FIG. 4, a circular aperture 105A is provided through the housing 105 such that IR radiation external to the device 100 may enter the first portion 100a and visible light generated by the light emitting layer 120 may exit the device 100. The circular aperture is defined by a rim 105R formed in the housing 105. A diameter of the rim 105R decreases in steps as a function of distance through the housing 105 from a front surface 105F to a back surface 105B of the housing 105 as may be seen schematically in FIG. 5(b). It is to be understood that the aperture may be non-circular in some embodiments, such as square, rectangular, oval or any other suitable shape.

FIG. 5(a) is a 3D view of the back side 105B of the device 100 whilst FIG. 5(b) is a cross- sectional view of the device 100 along line A-A as viewed in the direction of arrows B of FIG. 5(a). It can be seen that the first and second portions 100a, 100b sit within a machined recess of the wand 105 defined by the rim 105R such that substrate 110 of the second portion 100b abuts a shoulder 112 of the rim 105R.

A retaining ring 170 sits in abutment with the side of the substrate 150 on which the AR coating 160 is provided. The retaining ring 170 is in the form of a split ring and is captured in a recess 172 in the rim 105R. The retaining ring 170 may be resiliently deformed to reduce a diameter thereof in order to snap-fit the retaining ring 170 into the recess 172, which is held in the recess 172 by shoulders of the rim 105R on either side of the retaining ring 170. Alternatively, the rim 105R may be arranged not to capture the retaining ring 170, which may be provided in the form of a ring not being a split ring, and bonded to the housing 105 within the rim 105R. It is to be understood that other means for retaining the first and second portions 100a, 100b may be useful without the use of a retaining element, such as by means of an adhesive to directly adhere one or both of the portions 100a, 100b to the housing 105. In some embodiments the housing 105 may be provided in two parts, a front part comprising the front surface 105F and a back part comprising the back surface 105B, the two parts being joined together to capture the first and second portions 100a, 100b therebetween. Other arrangements may be useful.

It is to be understood that, in some embodiments, the device 100 may be provided without the housing, but rather in the form of a device 100 having the first and second portions 100a, 100b separated by an air gap with the spacer element 132 between the portions 100a, 100b as shown in FIG. 1. The spacer element 132 may be bonded or otherwise attached to the first and second potions 100a, 100b in order to hold the components 100a, 132, 100b together. Other arrangements may be useful.

It is to be understood that, in use, a user may hold the device 100 in the path of a beam of IR radiation from a source such as a free end of a fibre optic cable with the front face 105F of the device 100 towards the source as shown in FIG. 2 or FIG. 5(b). The user views the back face 105B of the device 100 from a direction that is not along the beam path, such as that indicated by arrow V in FIG. 2 or FIG. 5(b). This is so as to reduce a risk of damage to a user’s eyesight. As a precaution, a user may wear suitable safety glasses when using the device. If the user observes light emitted from the device through the substrate 110, the user is alerted to the presence of IR radiation of relatively long wavelength and therefore relatively high power. A user may then suspend work on the fibre until the fibre is no longer emitting such IR radiation, and no visible light is therefore emitted by the device through the substrate 110. It is to be understood that one or more protective optical elements may be provided downstream of the substrate 110 with respect to a direction of travel of light emitted by the light emitting layer 120 through the substrate 110, for example a scratch-resistant or other protective element such as a sheet of glass or other suitable material that transmits light generated by the light emitting layer 120.

Similarly, one or more suitable optical elements may be provided upstream of the substrate 150 and AR coating 160 provided they transmit a sufficient amount of the IR radiation that it is desired to detect.

FIG. 6 shows a passive IR detector device 200 according to a further embodiment of the invention. Like features of the embodiment of FIG. 6 to those of the embodiment of FIG. 4 are shown with like reference numerals incremented by 100.

The device 200 has a housing 205 in the form of a wand, having an elongate rectangular external profile as viewed from a front or rear as in the embodiment of FIG. 4. FIG. 6 shows a back surface 205B, a front surface having a corresponding external profile. The device 200 has an aperture 205A formed therethrough, the aperture 205A having a substantially square profile when viewed from the front or back of the device 200, the aperture 205A being defined by a rim 205R of the aperture 205A. When viewed from the rear, a light emitting layer substrate 210 is visible, filling the aperture 205A. A smaller aperture 205K is provided through the housing in a distal corner of the housing 205, arranged to allow the device 200 to be attached to a key ring or other item.

In some embodiments the device 200 may be provided in a holder that provides protection for the device 200 when not in use.

It is to be understood that embodiments of the present invention may be useful in detecting IR irradiation generated by a laser or other source such as a filament lamp source or any other suitable source. Passive detector devices according to embodiments of the present invention may be provided in the form of a portable device or as a substantially fixed installation.

Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of the words, for example “comprising” and “comprises”, means “including but not limited to”, and is not intended to (and does not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.