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LENS

20210168305 · 2021-06-03

Assignee

Inventors

Cpc classification

International classification

Abstract

An infrared transmitting lens for mounting in an aperture of a housing containing an apparatus to be subjected to infrared inspection, comprising a grille and an infrared transmitting material. The grille comprises a network of bars with an array of apertures between the bars, the grille providing mechanical protection to the infrared transmitting lens. The infrared transmitting material is positioned, in a combination of: on one, or both sides of the grille, or within the apertures of the grille; and thus enables infrared inspection through the array of apertures of the grille and through the infrared transmitting material. A method of manufacturing an infrared transmitting lens for mounting in an aperture of a housing containing an apparatus to be subjected to infrared inspection.

Claims

1. An infrared transmitting lens for mounting in an aperture of a housing containing an apparatus to be subjected to an infrared inspection, the infrared transmitting lens comprising: a grille, the grille comprising a network of bars with an array of apertures between the bars, the grille providing mechanical protection to the infrared transmitting lens; infrared transmitting material, positioned on both sides of the grille.

2. An infrared transmitting lens according to claim 1, wherein the grille further comprises infrared transmitting material between the network of bars of the grille, such that the infrared transmitting material, at least partially, fills the array of apertures between the network of bars of the grille.

3. An infrared transmitting lens according to claim 1, wherein the array of apertures of the grille are equal in size and shape, and arranged in a regular array.

4. An infrared transmitting lens according to claim 1, wherein the apertures of the grille are square, or circular; or rectangular; or triangular; or polygonal; or hexagonal; or any combination of square, circular, rectangular, triangular, polygonal or hexagonal.

5. An infrared transmitting lens according to claim 1, wherein the array of apertures of the grille are arranged in a tessellation.

6. An infrared transmitting lens according to claim 1, wherein the infrared transmitting lens is planar.

7. An infrared transmitting lens according to claim 1, wherein the infrared transmitting material comprises a polymer.

8. An infrared transmitting lens according to claim 1, wherein the grille comprises: plastic, or metal, or a combination of metal and plastic.

9. An infrared transmitting lens according to claim 1, wherein the grille is in the range of 0.2 millimetres to 3 millimetres wide from one side of the grille to the other side of the grille at a portion of the network of bars.

10. An infrared transmitting lens according to claim 1, wherein the infrared transmitting material, is in the range of 0.15 millimetres to 0.45 millimetres wide, in total, from one side to the other.

11. An infrared transmitting lens according to claim 1, wherein the infrared transmitting material in total width is 0.4 millimetres.

12. An infrared transmitting lens according to claim 1, wherein the infrared transmitting material is nonplanar.

13. An infrared transmitting lens according to claim 1, wherein the infrared transmitting material forms a seal across the infrared transmitting lens, or the grille, such that the seal is impermeable to fluids.

14. An infrared transmitting lens according to claim 1, wherein the infrared transmitting material comprises protrusions.

15. An infrared transmitting lens according to claim 1, wherein further comprises double-sided adhesive-tape on, a portion, of both sides of the grille, the double-sided adhesive-tape is between the grille and the infrared transmitting material.

16. An infrared transmitting lens for mounting in an aperture of a housing containing an apparatus to be subjected to an infrared inspection, the infrared transmitting lens comprising: a grille, the grille comprising a network of bars with an array of apertures between the bars, the grille further comprising infrared transmitting material between the bars of the grille, such that the infrared transmitting material, at least partially fills, the array of apertures between the bars of the grille.

17. An infrared transmitting lens according to claim 16, wherein further comprises, infrared transmitting material on one side of the grille.

18. A method of manufacturing an infrared transmitting lens for mounting in an aperture of a housing containing an apparatus to be subjected to infrared inspection, comprising the steps of: providing a grille, wherein the grille comprises a network of bars with an array of apertures between the network of bars; providing an infrared transmitting material to a first side of the grille; and, providing an infrared transmitting material to a second side of the grille.

19. A method of manufacturing an infrared transmitting lens according to claim 18 wherein further comprising the step of: applying double-sided adhesive-tape to, a portion of the network of bars of the grille, on both sides of the grille, before; providing an infrared transmitting material to a first side of the grille and providing an infrared transmitting material to a second side of the grille.

Description

[0106] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

[0107] FIG. 1 is a perspective view of a grille suitable for use in the present invention;

[0108] FIG. 2 is a perspective view of an infrared transmitting material suitable for use in the present invention;

[0109] FIG. 3 is a perspective view of an infrared transmitting lens according to an embodiment of the invention;

[0110] FIG. 4 is a schematic view of an infrared lens of the invention;

[0111] FIG. 5 is a front view of the infrared lens assembly in FIG. 4;

[0112] FIG. 6 illustrates an exploded view of an infrared lens assembly;

[0113] FIG. 7 is a schematic section view of an infrared lens according to an embodiment of the invention;

[0114] FIG. 8 is a schematic section view of an infrared lens according to another embodiment;

[0115] FIG. 9 shows a schematic view of an infrared transmitting lens according to an embodiment;

[0116] FIG. 10 shows a schematic view of an infrared transmitting lens according to another embodiment;

[0117] FIG. 11 shows a schematic view of an infrared transmitting lens according to a further embodiment; and

[0118] FIG. 12 shows a schematic view of an infrared transmitting lens according to a yet further embodiment.

[0119] FIG. 13 shows an exploded view of an infrared transmitting lens according to a further embodiment.

[0120] Like reference numerals are used to depict like features throughout.

[0121] FIG. 1 shows a grille 10. The grille 10 is generally planar and has a front side 12 and a rear side 16. The grille 10 also has a peripheral edge portion 14 defined between the front side 12 and the rear side 16. The grille 10 has a substantially circular shape in this embodiment. But in other embodiments, the grille 10 may take the form of another shape, such as, for example, a square, a rectangle, an ellipse or an oval. The grille 10 comprises a network of bars 18. In this particular embodiment, the grille 10 comprises aluminium, but it should be appreciated that the grille 10 may instead comprise different materials such as, for example, stainless steel, titanium, copper, plastic, a metal coated with plastic, or a plastic coated with a metal. The network of bars 18, which in this case is aluminium, has an array of apertures 20. The apertures 20 in this embodiment have a hexagonal shape extending through both the front side 12 and the rear side 16. That is, the apertures 20 extend through the thickness of the grille 10. The apertures 20 have a regular hexagonal shape. In this embodiment the edges of the hexagon have an equal length. In other embodiments however, the apertures 20 may have other shapes, for example but not limited to, a circular shape, a rectangular shape, a square shape, a triangular shape, a polygonal shape, or any combination of these shapes. It should further be appreciated that the array of apertures 20 may be arranged in a tessellation, and that the array of apertures 20 may extend to cover a larger area of the grille 10, or may extend across a smaller area of the grille 10. For example, the array of apertures 20 may extend to cover almost the entirety of the grille 10, or substantially the entirety of the grille 10. That is, the array of apertures 20 may extend towards and meet the outer periphery of the grille 10.

[0122] FIG. 2 illustrates an infrared transmitting lens 100. In this embodiment the infrared transmitting lens has an infrared transmitting material 130 on one side of a grille 110. In the FIG. 2 the infrared transmitting material 130 is largely blocking a view of the grille 110. For convenience the apertures 120 of the grille 110 are shown by dashed lines. The infrared transmitting lens 100 comprises a grille 110 and an infrared transmitting material 130. The grille 110 is substantially the same as the grille 10 in FIG. 1 and therefore will not be described again in detail. In this embodiment the infrared transmitting material 130 is on the front side 112 of the grille 110 and lies parallel and flush against it. The infrared transmitting material 130 in this embodiment is at least partially compressed into the grille 110. In this embodiment, the infrared transmitting material 130 comprises a polymer 138. An infrared transmitting material 130 comprises polymer 138 is particularly preferred because it has a relatively lost cost. Additionally, polymer material is easy to mould, compress and/or deform, which is beneficial, as will be discussed. Particularly in this embodiment, the infrared transmitting material 130 comprises polyethylene. However, in other embodiments other polymers may be used, for example, high molecular weight polyethylene (HMWPE), high density polyethylene, ultra-high molecular weight polyethylene (UHMWPE), polypropylene, sulphur-based polymers or polymethyl methacrylate. In this FIG. 2 embodiment the infrared transmitting material is positioned on one side of the grille and at least partially within the apertures of the grille.

[0123] In this embodiment, the infrared transmitting material 130 is relatively thin in width. More specifically, the infrared transmitting material 130 in this embodiment has a width of 0.2 millimetres. This is particularly important since the infrared transmitting material 130 is to enable transmitted infrared radiation to pass through the infrared transmitting material 130. The infrared transmitting material 130 enables infrared radiation in the wavelength range of about 0.5 micrometres to about 14 um to pass through. In specific embodiments the infrared the infrared transmitting material 130 has a front side 132 and a rear side 136, and a peripheral edge portion 134 defined in between the front side 132 and the rear side 136. When infrared radiation (not shown) passes through the hexagonal apertures 120 of the grille, the infrared radiation extends towards and transmits through the infrared transmitting material 130. In other embodiments the infrared transmitting material 130 may comprise a different material, and the infrared transmitting material 130 may have a different width from the front side 132 to the rear side 136 of the infrared transmitting material 130 so long as its width and the properties of the infrared transmitting material 130 allow infrared radiation to pass therethrough. In some embodiments, the infrared transmitting material 130 comprises protrusions (not shown) that correspond to the hexagonal apertures 120 of the grille 110 such that infrared can transmit through the hexagonal apertures 120 and through the protrusions of the infrared transmitting material 130.

[0124] FIG. 3 illustrates an embodiment of an infrared transmitting lens 200. The infrared transmitting lens 200 comprises a grille 210 and a first infrared transmitting material 230. The grille 210 is substantially the same as the grille 10 in FIG. 1 and thus will not be described again in detail. Likewise, the first infrared transmitting material 230 is substantially the same as the infrared transmitting material 130 in FIG. 2 and thus will not be described again in detail. The infrared transmitting lens 200 further comprises a second infrared transmitting material 240 on the rear side (not shown) of the grille 210 and lies parallel and flush against the grille.

[0125] In the FIG. 3 embodiment, the second infrared transmitting material 240 comprises a polymer. In other embodiments, the second infrared transmitting material 240 may comprise glass or crystalline, for example. The advantage that both infrared transmitting materials 230, 240 are polymer or comprise polymer, include ease of manufacture and lower costs. Suitable polymers include, but not limited to, for example, high molecular weight polyethylene (HMWPE), high density polyethylene, ultra-high molecular weight polyethylene (UHMWPE), polypropylene, sulphur-based polymers or polymethyl methacrylate. In this particular embodiment, both the first infrared transmitting material 230 and the second infrared transmitting material 240 are comprises polypropylene, however it should be appreciated that the materials of the first infrared transmitting material 230 and the second infrared transmitting material 240 may be different polymers, and in other examples, the first infrared transmitting material 230 and the second infrared transmitting material 240 may be different materials altogether, such as, for example, a polymer and a glass.

[0126] In this embodiment, the second infrared transmitting material 230 also has a relatively thin width. More specifically, the second infrared transmitting material 240 in this embodiment has a width, or thickness, of 0.2 millimetres. Likewise, the first infrared transmitting material 230 also has a width, or thickness, of 0.2 millimetres. Thus, the overall total width of the first infrared transmitting material 230 combined with the second infrared transmitting material 240 has a width of 0.4 millimetres. The grille 210 in this embodiment has a width, from front side of the grille (not shown) to the rear side, of 0.5 millimetres. The material of the first 230 and second 240 infrared transmitting materials and the width of same, allow infrared radiation to pass therethrough. That is, when infrared radiation (not shown) passes through either one of the first 230 and second 240 infrared transmitting materials, the infrared radiation passes through the hexagonal apertures 220 (for convenience shown as dashed lines) of the grille 210 and extends towards and transmits through the other one of the first 230 and second 240 infrared transmitting materials. In some embodiments each of the infrared transmitting materials 230, 240 may comprise a number of different materials, and each of the infrared transmitting materials 230, 240 may have a different width, so long as its width and the properties of the infrared transmitting material 230, 240 allow infrared radiation to pass therethrough.

[0127] When the infrared transmitting lens 200 is assembled together, the first infrared transmitting material 230 and the second infrared transmitting material 240 are compressed inwards towards the grille 210, in this embodiment. In some alternative embodiments the first and second infrared transmitting materials are not compressed. In this embodiment a compressive force is applied onto the front side 232, of the first infrared transmitting material 230 in a direction towards the grille 210. A compressive force is also applied on the rear side 246 of the second infrared transmitting material 240 compressing towards the grille 210. The first infrared transmitting material 230 in this embodiment is a polymer. When a compressive force is applied onto the front side 232 of the first infrared transmitting material 230, a portion of the first infrared transmitting material 230 is positioned between the network of bars. Thus, in this embodiment the grille comprises infrared transmitting material between the bars of the grille. In this specific FIG. 3 embodiment there is an air gap in the apertures, after compressing the first and second infrared transmitting material together. In this specific FIG. 3 embodiment the infrared transmitting material at least partially fills the apertures of the grille. In some alternative embodiments, the first transmitting material 230 deforms and fills the array of apertures 220. Likewise, in some embodiments, when a compressive force is applied onto the rear side 246 of the second infrared transmitting material 240, a portion of the second infrared transmitting material 240 is positioned between the network of bars. In some embodiments, the second transmitting material 240 deforms and fills the array of apertures 220. In some embodiments it is the infrared transmitting material from either one side or both sides that may at least partially fill the apertures. In embodiments when the apertures of the grilles are partially filled there may be an air gap. In embodiments where the apertures of the grille are filled there may be little to no air gap. The filling of the array of apertures in this way will be described in more detail later with reference to FIG. 7.

[0128] The present invention covers embodiments where the grille has infrared transmitting material positioned on both sides of the grille. This embodiment may look similar to that of FIG. 3 shown. In some embodiments where there is infrared transmitting material on both sides of the grille, there need not be necessarily any compression of the infrared transmitting material. In embodiments where there is no compression the infrared material may comprise, for example, polymer, crystalline or glass or any combination thereof. In embodiments where the infrared transmitting material is positioned to a side of the grille the infrared transmitting material may comprise, for example, polymer, crystalline or glass, or any combination thereof.

[0129] By combining different materials for the infrared transmitting materials used may lead to many different final compositions of the infrared transmitting lens. For example, an infrared transmitting material comprising crystalline may be used on one side of the grille and an infrared transmitting material comprising polymer on the other side of the lens. In this embodiment the apertures of the grille may comprise air. In this specific embodiment with different transmitting material on different sides of the grille may optionally further comprise a compression step such that the infrared transmitting material comprising polymer may be also positioned between the bars on the grille, at least partially filling the apertures of the grille.

[0130] FIG. 4 shows, an infrared transmitting lens, of the present invention, optionally within a window assembly 300. The embodiment shown in FIG. 4 is not to be construed as requiring the optional window frame, covers and other window assembly components, these are included for illustrative purposes only. The infrared transmitting lens comprises a grille 310 and infrared transmitting material 330, 340 positioned on both sides of the grille 310, a first infrared transmitting material 330 positioned on one side of the grille 310 and a second infrared transmitting material 340 positioned on the other side of the grille 310. Thus, this embodiment comprises a grille 310 wherein the grille 310 further comprises infrared transmitting material on two sides of the grille 310. The infrared transmitting lens, in this embodiment, is a composition of parts. The arrangement of the grille 310, first infrared transmitting material 330 and second infrared transmitting material 340 is substantially the same as the infrared transmitting lens 200 in FIG. 3 so will not be described here again in detail. The infrared transmitting lens 300 of the FIG. 4 embodiment is however shown after compression. The FIG. 4 embodiment of an infrared transmitting lens 300 is illustrated after the first 330 and second 340 infrared transmitting materials are compressed together by hand towards the grille 310. In alternative embodiments the compression may be by a machine. The compression used to compress the first 330 and second 340 infrared transmitting material, in this embodiment, is in the range of 5 to 38 Newtons. The infrared transmitting lens 300 in this embodiment is shown, for illustrative purposes, optionally with a window comprising a rim 352, 362, and also optionally an attachment mechanism 364, 370. As the first 330 and second 340 infrared transmitting material is compressed a portion of the infrared transmitting material enters the array of apertures of the grille 310 and therefore at least a portion of the infrared transmitting material is positioned between network of bars of the grille 310. Thus, in this embodiment the grille 310 comprising bars, further comprises infrared transmitting material between the bars of the grille 310. The polymer (in this embodiment) of the first 330 and second 340 infrared transmitting materials coats the outer surfaces of the grille 310, on both sides of the grille 310 in the network of bars of the grille 310. At the aperture portion of the grille 310 where the first and second infrared transmitting material are compressed together a portion of the first and second infrared transmitting material is at least partially positioned between the network of bars of the grille 310. In this embodiment the infrared transmitting lens is shown optionally sitting in a window frame that comprises removable protective screens 350, 360, with protrusions 356, 366. The infrared transmitting lens is held in the window frame or ridge 362 and 352 by attachment mechanisms 364, 370. In specific embodiments the removable screens 350, 360 would be normally positioned over the infrared transmitting lens but when inspection is required both protective screens 350, 360 would be temporarily removed, for example, by sliding these out of view of the infrared transmitting lens. Ideally both protective screens 250, 360 are slid out of view, by a mechanism or operation from the outer side of the window thus the container does not have to be opened to remove the protective screens 350, 360. The grille in this embodiment is 0.4 millimetres in width. Both the first and second infrared transmitting materials are 0.2 millimetres in width before compression. However, after compression, as a portion of the first 330 and second 340 infrared transferring material is positioned between the network of bars of the grille 310, the width of the combined first 330 and second 340 infrared transmitting material is 0.4 millimetres in width. millimetres. Thus, even though the total width of the infrared transmitting material is required to be relatively thin, preferably less than 0.45 millimetres, this arrangement of the FIG. 4 embodiment enables a grille of a larger width (than the total width of the infrared transmitting material) to be used. Advantageously a wider and stronger grille can be used to give mechanical strength or protection, that still enables a relatively thin (preferably less than 0.45 millimetres) width of infrared transmitting material to be used.

[0131] FIG. 5 shows a plan view of the infrared transmitting lens of the FIG. 4 embodiment in use, also showing the optional window rim 452 and optional attachment points 466, 456 for the optional protective screens 350, 360.

[0132] FIG. 6 illustrates an exploded assembly view of window assembly 500 comprising an infrared transmitting lens, also shown in exploded view. The infrared transmitting lens comprises a grille 510 and infrared transmitting material 530, 540 on both sides of the grille. FIG. 6 also shows the optional components that make up the window assembly 500, the window assembly 500 having a central axis 570. The FIG. 6 embodiment window assembly shows optional front and back protective screens 550, 560. Each component is generally planar in shape, having a front side and a rear side. Each component in this embodiment is also substantially circular in shape. The window assembly 500 shows an infrared transmitting lens comprising a grille 510 positioned centrally in the infrared transmitting lens. The grille 510 is formed from a network of bars. In this embodiment, the grille 510 is formed from aluminium. The network of bars (aluminium), has an array of apertures 520. In this embodiment the apertures 520 have a hexagonal planar shape. The apertures 520 extend through the width of the grille 510. It should be appreciated that the array of apertures 520 may extend to cover a larger side surface area of the grille 510, or may extend to cover a smaller side surface area of the grille 510. For example, the array of apertures 520 may extend to cover substantially the entirety of the grille 510. That is, the array of apertures 520 may extend towards and meet the outer periphery of the grille 510.

[0133] On either side of the grille 510, there is provided infrared transmitting material 530, 540. Specifically, in this embodiment, a first infrared transmitting material 530 made of a polymer is positioned on a front side of the grille 510. A second infrared transmitting material 540 also made of a polymer is positioned on a rear side of the grille 510. In this embodiment the grille 510 comprises infrared transmitting material on two sides of the grille 510. The infrared transmitting material 530, 540 on either side of the grille 510 lies parallel and flush against the grille 510. The material of the first 530 and second 540 infrared transmitting materials and the width of same, allow infrared radiation to pass therethrough. When infrared radiation (not shown) passes through either one of the first 530 and second 540 infrared transmitting materials, the infrared radiation passes through he hexagonal apertures 520 of the grille 510 and extends towards and transmits through the other one of the first 530 and second 540 infrared transmitting materials.

[0134] In this embodiment, the infrared transmitting materials 530, 540 have a width from one side to the other, of 0.2 millimetres, and they comprise a polymer. However, it should be appreciated that each of the infrared transmitting materials 530, 540 may comprise a different material, and each of the infrared transmitting materials 530, 540 may have a different width, so long as its width and the properties of the infrared transmitting material 530, 540 allow infrared radiation to pass therethrough.

[0135] For illustrative purposes of showing the lens of the present invention in use, optional covers, and rim and other optional window components are shown. A first movable optional cover 550 is provided on a front side, positioned near to the first infrared transmitting material 530. The first removable optional cover 550 has a rim 552 positioned around the periphery of the first movable optional cover 550. The rim 552 is provided with attachment points 556.

[0136] Similarly, a second optional cover 560 is provided at the rear side, positioned near the second infrared transmitting material 540. The second optional cover 560 also has a rim 562 positioned around the periphery of the second cover 560. The rim 562 also has attachment points 568. In this embodiment the optional attachment points 568, 556 assists to hold the optional cover in place when viewing is not required but enable easy removal of the optional covers from any one side when viewing through the infrared transmitting lens is required.

[0137] In use, the infrared transmitting lens 530, 510, 540 can be mounted in an aperture of a housing containing an apparatus to be subjected to infrared inspection. The window assembly 500 can be mounted within a housing. Thus, infrared radiation can be transmitted through the apertures 520 of the grille 510 and through the infrared transmitting materials 530, 540 to inspect inside the housing. In this embodiment, the infrared transmitting lens comprising the grille 510 and the first 530 and second 540 transmitting materials can be assembled together by compressing the first infrared transmitting material 530 and the second infrared transmitting material 540 inwards towards the grille 510. In some embodiments, when a compressive force is applied on the first infrared transmitting material 530, the first infrared transmitting material 530 deforms and fills the array of apertures 520 of the grille 510. This is better shown in FIG. 7.

[0138] FIG. 7 shows an embodiment comprising an infrared transmitting lens 600 comprising a grille 610, a first infrared transmitting material 630 on one side of the grille 610 and a second infrared transmitting material 640 on the other side of the grille 610. Thus, this embodiment comprises a grille 610 further comprising infrared transmitting material 630, 640 on both sides of the grille 610. The grille 610 comprises an array of apertures 620. In this embodiment, the grille comprises steel. In this embodiment the first infrared transmitting material 630 and the second infrared transmitting material 640 both comprise a polymeric material. More specifically, the first infrared transmitting material 630 and the second infrared transmitting material 640 comprise polyethylene. When a compressive force is applied on the outside of the first infrared transmitting material 630 towards the grille 610, the first infrared transmitting material 630 deforms and fills the array of apertures 620 from the front side. Likewise, when a compressive force is applied on the outside of the second infrared transmitting material 640 towards the grille 610, the second infrared transmitting material 640 deforms and fills the array of apertures 620 from the rear side. Thus, the apertures 620 are at least partially filled with the deformed polymer infrared transmitting materials 630,640. The embodiment shown in FIG. 7 is shown already compressed towards both sides of the grille. The apertures 620 are at least partially filled with polymer of the infrared transmitting materials 630 and 640. In this embodiment the infrared transmitting materials 630, 640 cover the grille 610 giving protection to the steel grille from corrosion. Infrared radiation is able to pass through the infrared transmitting materials 630, 640 and through the apertures 620 of the grille 610. In this embodiment the width of the grille 610 is 0.2 millimetres. In this embodiment the width of both the first 630 and second 640, infrared transmitting materials, after compression are 0.2 millimetres each. The total width of the infrared transmitting lens 600 of the FIG. 7 embodiment is 0.4 millimetres. In some embodiments, the apertures 620 are completely filled with infrared transmitting material 630, 640 from one or both sides of the grille 610, from the first infrared transmitting material 630 or the second infrared transmitting material 640, or both the first transmitting material 630 and second infrared transmitting material 640. Aptly the infrared transmitting material 630 and 640 form a seal. In some embodiments the infrared transmitting material 630, 640 form a seal that is fluid tight. Thus, in embodiments with a fluid tight seal, fluids, gas and liquids, cannot pass through the infrared transmitting lens. In other embodiments the infrared transmitting material may form a liquid tight seal and thus gas could pass through.

[0139] For illustrative purposes only, embodiments of the invention including those of FIGS. 4, 5, 6, 7 and 8 are shown and explained by embodiments of a lens of the present invention in use with optional window frame and optional covers and optional other window components. Window frame components and covers are optional and not to be limitations to these or other embodiments of the invention.

[0140] In the FIG. 8 embodiment, as illustrated in FIG. 8, the infrared transmitting lens (the combined, grille 710, first infrared transmitting material 730, and the second infrared transmitting material 740) may be curved. Window assembly 700 comprises an infrared transmitting lens comprising a grille 710, and first and second infrared transmitting materials 730, 740. The window assembly 700 of this FIG. 8 embodiment also shows optional, first and second covers 752, 762. The optional covers 752 and 762 are also curved. In this embodiment, the grille 710 has a curved profile, as does the first infrared transmitting material 730 and second infrared transmitting material 740. The first 730 and second 740 infrared transmitting materials have substantially the same curvature as the grille 710 so as to engagingly contact with the grille 710. Advantageously by having the infrared transmitting material 730, 740 with the same curvature as the grille 710 aids even distribution of the infrared transmitting material 730, 740 into the aperture of the grille 710 or over the grille 710. As previously described, the first infrared transmitting material 730 or the second transmitting material 740, or both the first 730 and second 740 infrared transmitting material, in some embodiments, may deform and at least partially fill the array of apertures (not shown) in the grille 710. The window assembly 700 is further provided with an optional curved first cover 752 and an optional curved second cover 762. Again, the first optional cover 752 and second optional cover 762 have substantially the same curvature as the grille 710, and as the first and second transmitting materials 730, 740. This arrangement is particularly advantageous as the curved infrared transmitting lens may be exposed to more potential damage. The curvature of the components within the infrared transmitting lens or window assembly 700 can be modified to correspond to the required curvature wanted for the infrared transmitting lens. Advantageously, in this embodiment, both infrared transmitting materials 730 and 740 comprise a polymeric infrared transmitting material, to allow the curved construction. The grille comprises a metal, in this embodiment.

[0141] FIG. 9 shows a part cross cut section of an infrared transmitting lens 800 according to an embodiment of the present invention. The infrared transmitting lens 800 comprises a grille 810 formed from a network of bars. The grille 810 comprises a network of bars. In this particular embodiment, grille 810 and the network of bars of the grille 810 comprises stainless steel. The network of bars of the grille has an array of apertures, however for simplicity, only one aperture is shown. The aperture is filled with an infrared transmitting material 830. In this embodiment, the infrared transmitting material is a polymeric material. More specifically, the infrared transmitting material comprises polyethylene. When infrared radiation (not shown) is directed towards the aperture of the grille 810, and the infrared transmitting material 830 therein, the infrared radiation transmits through the aperture and the infrared transmitting material 830. The Infrared transmitting material 830 enables infrared radiation in the wavelength range of about 0.5 micrometres to about 1 millimetre to transmit through the infrared transmitting material 830 and thus through the infrared transmitting lens 800. In this particular embodiment, the infrared transmitting material 830 has a width, from one side to the other side, of 0.4 millimetres. This is the same in this particular embodiment as the width of the grille at 0.4 millimetres. In other embodiments the infrared transmitting material 830 may have a different width, so long as its width and the properties of the infrared transmitting material 830 allow infrared radiation to pass therethrough. In this FIG. 9 embodiment there is no infrared transmitting material 830 on the outer surface of the sides of the grille 810 at the network of bars portion of the grille. Advantageously the grille is made of stainless steel and therefore is resistant to corrosion. The infrared transmitting lens of the FIG. 9 embodiment may be produced by extruding infrared transmitting polymer 830 into the apertures of the grille 810.

[0142] FIG. 10 shows an infrared transmitting lens 900 according to another embodiment. The infrared transmitting lens 900 comprises a grille 910 that is substantially the same as the grille 810 in FIG. 8, so will not be described again in detail. In this particular embodiment, the infrared transmitting lens comprises an infrared transmitting material 930 on a front side of the grille 910 positioned parallel and flush against the grille 910. The infrared transmitting material 930 comprises polymer, in this embodiment. To produce the FIG. 10 embodiment a sheet of infrared transmitting polymer 930 is placed, or positioned, on one side of the grille 910, and compressed into the grille by hand. A force of compression of approximately twenty newtons is used to compress the sheet of infrared transmitting material into the grille 910. In some alternative embodiments the compressing process of the infrared transmitting material may be a mechanical process. The infrared transmitting material 930 deforms and partially fills the aperture 920 of the grille 910. The apertures are filled sufficiently enough to offer protection, and prevent movement of objects through the infrared transmitting lens. In this FIG. 10 embodiment the sheet of infrared transmitting material is 0.2 millimetres in width before compression. After compression the sheet of infrared transmitting material is has a width of 0.4 millimetres in the apertures 920 portions of the grille and a width of 0.1 millimetres at the network of bars portion of the grille 910. The grille is 0.5 millimetres in width from one side to the other side, at the network of bars portion of the grille. Infrared radiation is able to travel through the grille at the aperture portions of the grille 910, through the infrared transmitting material 930. In this embodiment the infrared transmitting material 930 forms a fluid seal, preventing fluid from passing though the grille 910. The polymeric infrared transmitting material 930 also protects the grille from degradation for example from corrosion, or harmful chemicals.

[0143] In a further embodiment similar to that shown in FIG. 10, another infrared transmitting material, comprising polymer, similar to the first infrared transmitting material 930 could be positioned on the other side of the grille 910 and compressed together to give infrared transmitting material on both sides of the grille 910. The second infrared transmitting material (not shown) would be a mirror image of the infrared transmitting material 930 shown in the FIG. 10. Ideally the two infrared transmitting materials would join in the apertures of the grille 910. Again, the infrared transmitting materials form a fluid seal across the grille 910.

[0144] FIG. 11 shows an infrared transmitting lens 1000 according to a further embodiment. The infrared transmitting lens 1000 comprises a grille 1010 that is substantially the same as the grille 810 in FIG. 8 and grille 910 in FIG. 9, so will not be described again here in detail. The infrared transmitting lens 1000 further comprises a first infrared transmitting material 1030 positioned parallel and flush against a front side of the grille 1010 and a second infrared transmitting material 1040 positioned parallel and flush against a rear side of the grille 1010. The FIG. 11 embodiment is manufactured by placing, or positioning, two identical infrared transmitting sheets 1030, 140 comprising polymer on either side of a grille 1010 and compressing the two sheets of infrared transmitting material together into the grille 1010. The two infrared transmitting materials 1030 and 1040 both comprise polymer. The two infrared transmitting materials 1030 and 1040 are both manufacture as largely planar sheets with protrusions. The protrusions of the sheets of infrared transmitting materials are configured to correspond to the configuration, shape and positioning of the apertures in the grille 1010, such that the protrusions of the infrared transmitting materials 1030 and 1040 fit into the corresponding apertures of the grille. Further, in this embodiment the infrared transmitting materials 1030 and 1040 may abut, for example, flat, against a side, or opposites sides of the grille, with the protrusions within the apertures of the grille 1010. Advantageously, no compression is required in this embodiment. Each infrared transmitting material 1030 and 1040 may form a fluid seal. Advantageously such a configuration may give a good seal, and is easy to fit. Further the protrusion configuration of this embodiment is easy to manufacture and store. Similar embodiments may use only one preformed infrared transmitting material with protrusions where the protrusions correspond to the array of apertures of the grille. In some embodiments the preformed sheets of infrared transmitting material with protrusions on one side may be planar and smooth on the opposite side of the preformed sheet of infrared transmitting material. In some alternative embodiments the preformed sheets of infrared transmitting materials with protrusions on one side, may have corresponding indents on the opposite side of the sheet of infrared transmitting material.

[0145] A force may still be applied to compress this embodiment but it is not necessary to produce a seal or a complete infrared transmitting lens. Both sides of the grille need not be covered by an infrared transmitting material to produce an infrared transmitting lens. The infrared transmitting lens may comprise a sheet of infrared transmitting material wherein the infrared transmitting material comprises a preformed sheet of infrared transmitting material. Further the infrared transmitting material may comprise protrusions. The protrusions of the sheet of infrared transmitting material may correspond to the apertures of the grille.

[0146] In an alternative embodiment where a compression force is desired, the force used to compress the two sheets of infrared transmitting material 1030, 1040 into the grille 1010 may be between 15 and 40 Newtons of force. In this embodiment, the first infrared transmitting material 1030 on a front side of the grille 1010 deforms and partially fills the aperture between the bars of the grille 1010 from the front side. The second infrared transmitting material 1040 on the rear side of the grille 1010 deforms and partially fills the aperture of the grille 1010 from the rear side. In this particular embodiment, the first infrared transmitting material 1030 and the second infrared transmitting material 1040 deform and fill the aperture of the grille 1010 from their respective sides and contact in the middle of the aperture, thus, partially at least, filling the aperture. In other embodiments, the first infrared transmitting material 1030 and the second infrared transmitting material 1040 deform and partially fill the aperture of the grille 1010 from their respective sides and are separate from one another. Thus, the aperture remains partially filled. The width of both the first 1030 and second 1040 infrared transmitting material are equal, at 0.2 millimetres in diameter before compression. After compression the width of the first 1030 and second 1040 infrared transmitting material together, in total, is 0.4 millimetres at the aperture portion of the grille 1010. The grille 1010 has a width of 0.35 millimetres. In this FIG. 11 embodiment the infrared transmitting material 1030, 1040 coats the grille, thus offering protection against degradation, for example, corrosion. The grille 1010 gives structural protection to the infrared transmitting material and the infrared transmitting lens.

[0147] FIG. 12 shows an infrared transmitting lens 1100 according to a yet further embodiment. The infrared transmitting lens 1100 comprises a grille 1120 that is substantially the same as the grilles as described in FIGS. 9, 10 and 11, so will not be described again here in detail. The infrared transmitting lens 1100 further comprises a first infrared transmitting material 1130 positioned parallel and plush against a front side of the grille 1110 and a second infrared transmitting material 1140 positioned parallel and flush against a rear side of the grille 1110. The grille 1110 is formed from a network of bars. In this particular embodiment, the grille and bars comprise aluminium, however alternatively in other embodiments the bars may comprise a different material, such titanium or copper, plastic, plastic coated with a metal, or a different metal. The network of bars, which in this embodiment is aluminium, has an array of apertures 1120, however for simplicity, only one aperture 1120 is shown. In this embodiment, each of the first infrared transmitting material 1130 and the second infrared transmitting material 1140 are not compressed, and thus do not deform to fill the aperture 1120 of the grille 1110. In some embodiments an air gap may exists in the apertures 1120 of the grille 1110 between the first 1130 and second 1140 infrared transmitting materials. Both, the first 1030 and second 1040 infrared transmitting material is 0.2 millimetres in width. The grille 1110 is 0.5 millimetres in width. The first 1030 and second 1040 infrared transmitting material cover the grille 1110 protecting the grille 1110 from, for example, corrosion. The total width of the infrared transmitting lens of the FIG. 12 embodiment is 0.7 millimetres.

[0148] FIG. 13 shows an exploded view of an infrared transmitting lens 500 that, in this particular embodiment, uses double-sided adhesive-tape 555. An exploded view of FIG. 13 is shown to assist in understanding the component parts but in use the double-sided adhesive-tape 555 would contact both the grille 510 and the infrared transmitting material 550, 560; holding the infrared transmitting material 550, 560 to the grille 510. In this embodiment there are two infrared transmitting materials 550, 560, one on each side, or face, of the grille 510. In this embodiment the grille 510 comprises stainless steel, metal, to give strength and structural rigidity to the infrared transmitting lens 500. The grille 510 comprises an array of apertures 520 to enable the infrared light to pass through. The grille is 0.2 millimetres in width, from one side, or face, to the other side, or face, of the grille in this example. To each side, or face, of the grille there is a double-sided adhesive tape 555 with an array of apertures 557 that correspond to the array of apertures 520 of the grille 510. In the embodiment shown here, the corresponding array of apertures 557 of the double-sided adhesive-tape 555 is an exact, or almost exact, match to the array of apertures 520 of the grille 510. In this embodiment a jig (not shown) could be used to cut the array of apertures 557 of the double-side adhesive-tape 555. In other embodiments the corresponding array of apertures 557 of the adhesive tape 555 may not an exact match, for example the double-side adhesive tape may be only near the peripheral edge of the sides of the grille 510. In this FIG. 13 the central axis 570 is shown by a dashed line, however this dashed line does not exist in the embodiment.

[0149] Various modifications to the detailed designs are described above are envisaged. For example, previously it is described that the first infrared transmitting material and the second infrared transmitting material are compressed inwards towards the grille. This urges the first transmitting material and the second infrared transmitting material towards the grille and optionally, deforming the infrared transmitting material into the apertures of the grille. In some embodiments the grille may be formed by extrusion. In some embodiments, one or more, of the infrared transmitting material may be extruded around the grille. That is, the grille is produced by feeding a material such as, for example, aluminium, through an extruder along with infrared transmitting material on one or both sides of the grille. This produces an infrared transmitting lens having a grille and infrared transmitting material(s) in one step such that the grille is provided with infrared transmitting material(s) provided within, around or on, or any combination of within, on or around the grille, removing the need for a compression step to attachingly engage the infrared transmitting material with the grille. When the infrared transmitting material, for example, an infrared transmitting material comprising polymer, surrounds, or partially surrounds, the grille, the infrared transmitting material protects the grille from degradation, for example, from corrosion.

[0150] It will be clear to a person skilled in the art that features described in relation to any of the embodiments described above can be application interchangeably between the different embodiments. The embodiments described above are examples to illustrate various features of the invention.

[0151] Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Through 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.

[0152] 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. All of the features disclosed in this specification (including any accompanying claims, abstract or drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0153] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.