Lens design and manufacturing method

Abstract

The present invention discloses a lens, comprising a central portion comprising a first polymer; wherein the central portion is operable to emit electromagnetic radiation therethrough; and a peripheral portion comprising a second polymer; wherein the peripheral portion accommodates dimensional changes in the central portion by absorbing energy and transitioning from a lower energy state to a higher energy state. Also disclosed herein is a method of making a lens and an article comprising the lens, the method comprising injecting a molten polymer into a mold to produce the lens; wherein the lens comprises a central portion; and a peripheral portion; wherein the peripheral portion accommodates dimensional changes in the central portion by absorbing energy and transitioning from a lower energy state to a higher energy state.

Description

Technical Field

[0001] The present invention discloses a lens design and a manufacturing method thereof, and in particular, discloses a lens adapting to mismatched thermal expansion coefficients and a manufacturing method thereof. Background Art

[0002] Advanced Driver Assistance Systems (ADAS) are used in vehicles to assist drivers while driving. When designed with a safe human-machine interface, they aim to improve automotive safety and, more generally, road safety.

[0003] Advanced driver assistance systems are systems developed to automate, adapt, and enhance vehicle systems for safer and better driving. The automated systems that ADAS provide to vehicles have proven to reduce road accidents by reducing the human errors that often cause accidents. Safety features are designed to avoid collisions and accidents by providing technology that warns the driver of potential problems, or by implementing protective measures and taking over control of the vehicle to avoid a collision. Adaptive features can automatically illuminate, provide adaptive cruise control and collision avoidance, pedestrian collision avoidance mitigation (PCAM), incorporate satellite navigation / traffic warnings, warn the driver of other vehicles or hazards, lane departure warning systems, automatic lane centering, display blind spots, or connect to a smartphone for navigation instructions. ADAS relies on input from multiple data sources, including automotive imaging, LiDAR, radar, image processing, computer vision, and in-vehicle networks.

[0004] To facilitate automotive imaging, ADAS systems often incorporate lenses as part of the optical device. To make ADAS systems available to a larger population, it is desirable to reduce costs while improving performance. However, lower-cost lenses have drawbacks that should be overcome to make them suitable for use in ADAS systems. Summary of the invention

[0005] The lens includes a central portion comprising a first polymer and a peripheral portion comprising a second polymer. The central portion is operable to transmit electromagnetic radiation therethrough. The peripheral portion accommodates dimensional changes in the central portion by absorbing energy and transitioning from a lower energy state to a higher energy state.

[0006] In one embodiment, the peripheral portion undergoes a change in shape without any substantial change in size.

[0007] In another embodiment, the first polymer is the same as the second polymer.

[0008] In yet another embodiment, the first polymer is different from the second polymer.

[0009] In yet another embodiment, the peripheral portion surrounds the central portion along its entire circumferential periphery.

[0010] In yet another embodiment, the peripheral portion includes a plurality of elements that are not in contact with each other, and wherein each of the plurality of elements is in contact with the central portion.

[0011] In yet another embodiment, the cross-section of the peripheral portion has a linear profile or a curvilinear profile before absorbing energy.

[0012] In yet another embodiment, the linear profile changes to a curved profile due to energy absorption.

[0013] In yet another embodiment, the curved profile is a sinusoidal profile that may include one or more troughs and one or more peaks.

[0014] In yet another embodiment, the sinusoidal profile may contain multiple valleys and peaks with varying amplitude and periodicity, and wherein the amplitude or periodicity changes upon energy absorption.

[0015] In yet another embodiment, the peripheral portion comprises pre-arranged deformation points.

[0016] In yet another embodiment, the second polymer has a negative coefficient of thermal expansion and the first polymer has a positive coefficient of thermal expansion.

[0017] In yet another embodiment, the first polymer and the second polymer include cyclic olefin polymers.

[0018] In yet another embodiment, the cyclic olefin polymer comprises a cyclic olefin copolymer.

[0019] In yet another embodiment, an article includes a lens including a central portion comprising a first polymer and a peripheral portion comprising a second polymer. The central portion is operable to transmit electromagnetic radiation therethrough. The peripheral portion accommodates dimensional changes in the central portion by absorbing energy and transitioning from a lower energy state to a higher energy state.

[0020] In another embodiment, the article of manufacture is an advanced driver assistance system.

[0021] In one embodiment, a method of making a lens includes injecting a molten polymer into a mold to make a lens. The lens includes a central portion and a peripheral portion. The peripheral portion accommodates dimensional changes in the central portion by absorbing energy and transitioning from a lower energy state to a higher energy state.

[0022] In yet another embodiment, the molten polymer comprises a polyolefin.

[0023] In another embodiment, the polyolefin comprises a cyclic olefin copolymer.

[0024] In yet another embodiment, a method includes placing a lens in a fixture.

[0025] In yet another embodiment, the lens disposed in the fixture is disposed in a vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1(A) is a depiction of a side view of a prior art lens;

[0027] FIG. 1(B) is a depiction of a top view of the prior art lens of FIG. 1(A);

[0028] FIG. 2(A) is a depiction of a side view of an exemplary schematic diagram of a lens disclosed herein;

[0029] Fig. 2(B) is a view of a cross section taken along XX′ of Fig. 2(A);

[0030] FIG2(C) is another view of a cross section taken along XX′ of FIG2(A);

[0031] FIG. 3(A) is a depiction of a side view of an exemplary schematic diagram of a lens disclosed herein;

[0032] Fig. 3(B) is a view of a cross section taken along XX′ of Fig. 3(A);

[0033] FIG3(C) is an enlarged view of the CC′ section taken from FIG3(B);

[0034] FIG3(D) depicts the change in the profile of the peripheral portion of FIG3(C) from before energy absorption to after energy absorption;

[0035] FIG. 4(A) is a depiction of a lens having a peripheral portion containing pre-arranged deformation points;

[0036] FIG4(B) is a cross-sectional view of the lens of FIG4(A) before absorbing energy;

[0037] FIG4(C) is another cross-sectional view of the lens of FIG4(A) after absorbing energy;

[0038] FIG. 5(A) is an exemplary depiction of one embodiment of an element absorbing energy in a peripheral portion;

[0039] FIG5(B) is another exemplary depiction of one embodiment of an energy absorbing element in a peripheral portion;

[0040] FIG. 5(C) is another exemplary depiction of one embodiment of an energy absorbing element in a peripheral portion; and

[0041] Figure 6is a depiction of a lens including a peripheral portion whose coefficient of thermal expansion has a different sign than the coefficient of thermal expansion of the lens. DETAILED DESCRIPTION

[0042] The present invention discloses a polymer-containing lens for use in an ADAS system for an automobile. The present disclosure proposes a novel method to minimize radial stresses in a polymer lens caused by mismatched coefficients of thermal expansion (CTE) and other environmental stresses. The lens is designed to accommodate forces caused by CTE mismatch with a supporting device, thereby preventing damage to the lens and mitigating the effects of providing erroneous signals to the driver of the car containing the ADAS system. The polymer lens has a central portion through which light is transmitted and a peripheral portion surrounding the central portion, wherein the peripheral portion is designed to offset dimensional changes in the central portion by energy absorption. The use of the energy absorbing peripheral portion prevents deformation of the field of view of the lens, and the lens can undergo expansion and contraction without experiencing temporary or permanent deformation. The performance of the lens is thus stabilized while minimizing the cost of the lens used in the ADAS system.

[0043] Polymer lenses are also much cheaper than lenses containing glass. However, the CTE of these polymer lenses is higher than that of glass lenses, and the mismatch in the CTE of the supporting device (containing the polymer lens) often results in undesirable deformations. The high-performance lenses currently used in ADAS systems are made of a metal barrel and all glass elements to minimize aberrations. These lenses differ from the lenses used to display video to the driver in that the fidelity of the image produced by the lens is used by the algorithms trained to perform perception and modeling. When the user of the video is a human, such small aberrations do not matter and lower performance lenses can be used.

[0044] 1(A) and 1(B) depict a conventional lens 100. The lens includes a peripheral portion 102 surrounding a central portion 104. Light enters the lens through the central portion 104. The light entering the lens is ultimately transmitted to an image sensor (not shown), etc. The lens 100 is placed in a support device (not shown) that provides support and holds it in place during operation of the vehicle. In one embodiment, the peripheral portion and the central portion form a solid, integral piece. Neither the central portion nor the peripheral portion contains any cavity.

[0045] The central portion 104 is generally circular with a radius R2 and the peripheral portion 102 is also circular with a radius R1 greater than R2. When the lens 100 is subjected to temperature changes, the peripheral portion 102 expands and contracts most in the circumferential direction (as shown by arrow R3). The maximum expansion (which will occur when the temperature rises) will generally promote an increase in the outer circumference of the lens 100. However, because the lens 100 is constrained in a support device (not shown) that contacts the lens 100 at its periphery 102, the material located at the periphery of the lens 100 will be subject to compressive forces.

[0046] Similarly, when the lens 100 is subjected to a decrease in temperature, the circumferential length of the lens 100 will decrease. However, because the lens 100 is constrained in a support device (not shown) that contacts the lens 100 at its periphery 102, the material at the periphery of the lens 100 will be subject to elongation forces.

[0047] Over time, these continuous compressive and elongation forces will promote deformation of the lens. In addition, if any of these forces become too great, it may cause temporary deformation of the lens prescription, resulting in aberrations. In order to overcome these aberrations, it is desired to change the periphery of the lens by causing the peripheral portion to accommodate the expansion of the central portion of the lens by absorbing energy. Therefore, the peripheral portion is initially in a position representing a lower energy state E1. It is to be noted that the lower energy state referred to in the present invention may or may not be the lowest energy state E0. Upon deformation by the lens, the peripheral portion undergoes a shape change to a higher energy state E2, such that E2 is greater than E1, which may or may not be greater than E0. When the deforming forces on the lens are removed, the peripheral portion returns to its original lower energy state E1.

[0048] In one embodiment, the peripheral portion of the lens has spring-like properties and undergoes deformation to accommodate the expansion of the central portion caused by temperature changes. The central portion can expand or contract depending on the ambient temperature conditions. In one embodiment, the deformation causes the shape of the peripheral portion to change without simultaneously experiencing any changes in the dimensions of the peripheral portion (e.g., overall length, overall width, overall thickness, etc.). When the driving force for the deformation is removed (e.g., the temperature returns to its original state), the spring-like properties of the peripheral portion cause it to return to its original shape.

[0049] In another embodiment, the peripheral portion comprises a material having a coefficient of thermal expansion opposite to the coefficient of thermal expansion of the material of the lens. In one embodiment, if the central portion of the lens has a positive coefficient of thermal expansion, the peripheral portion will have a negative coefficient of thermal expansion. In another embodiment, if the central portion of the lens has a negative coefficient of thermal expansion, the peripheral portion will have a positive coefficient of thermal expansion. In one embodiment, the peripheral portion generally has a coefficient of thermal expansion that accommodates the difference in thermal expansion between the central portion of the lens and a fixture that holds the lens.

[0050] 2(A), 2(B) and 2(C) show an exemplary schematic embodiment of a lens 200 that can accommodate compressive or tensile stresses without any deformation of the lens because the peripheral portion includes a material having energy absorbing properties. The energy absorbing properties are due to the properties of the material (e.g., being elastic) or due to the shape of the material (e.g., being in the form of a coil or spring). The lens 200 includes a peripheral portion 204 surrounding a central portion 202. The peripheral portion is in partial or continuous contact with the central portion. In one embodiment, the peripheral portion and the central portion form a solid, integral piece and include the same material. In another embodiment, the peripheral portion and the central portion form a solid, integral piece, even though they each may include different materials. In yet another embodiment, the peripheral portion and the central portion may include two or more separate components, even though they each may include the same material. In another embodiment, the peripheral portion and the central portion may include two or more separate components, each of which includes different materials.

[0051] FIG. 2(A) shows a front view of one embodiment of a lens 200 that includes an energy absorbing peripheral portion 204 that completely surrounds a central portion 202 (the lens is used as a lens for transmitting electromagnetic radiation such as visible light or infrared light). FIG. 2(B) depicts a cross-sectional view of the lens of FIG. 2(A) taken from section XX′. As can be seen from FIGS. 2(A) and 2(B), the peripheral portion is tilted at a preferred angle α relative to a vertical line drawn through the lens (when the central portion is placed vertically). The lens is mounted in a fixture 208 that holds the lens so that the peripheral portion 204 can be tilted at the preferred angle α at a desired predetermined temperature T1. In one embodiment, T1 is preferably room temperature. When the temperature rises to T2, the lens 202 expands, forcing the axis AA' of the peripheral portion (in the fixture) to travel in the direction indicated by arrow 206 to a new position A″A″′. The travel distance in the fixture depends on the temperature difference T2-T1. When the temperature returns to T1, the axis of the peripheral portion returns from A″A″′ to its original position AA'. Thus, when the axis of the peripheral portion is in position AA', the peripheral portion is in a lowest energy state. When the temperature of the central portion changes, the axis of the peripheral portion moves to A"A"', which is a higher energy state. After returning the lens to its original temperature, the peripheral portion returns to the lowest energy state represented by the original position AA'. It is noted that the fixture 208 can have one or more predetermined paths (not shown here), such as grooves, splines, etc., along which the peripheral portion can travel when it is deformed from its lowest energy state to a higher energy state (or vice versa).

[0052] FIG. 2(C) shows another embodiment of the deformation of the peripheral portion from its lowest energy state to a higher energy state. In the lowest energy state (as can be seen in FIG. 2(B)), the peripheral portion occupies a position represented by the axis AA' (which is linear). When subjected to a temperature change, the peripheral portion is in a higher energy state, so its axis AA' is now curved. FIG. 2(C) does not show the fixture 208, but the fixture constrains the peripheral portion so that it deforms to the higher energy state represented by the curved axis AA'.

[0053] In one embodiment, the peripheral portion may optionally contain a cavity (not shown) for receiving a fastener such as a screw, bolt, nut, rivet, etc., which is typically used to secure the lens to a support device.

[0054] Figures 3(A), 3(B), 3(C) and 3(D) each illustrate another embodiment of a lens 200 in which a peripheral portion 204 deforms from a lower energy state to a higher energy state as the central portion 202 changes its size due to temperature changes. Figure 3(A) depicts an exemplary embodiment of a front view of a lens 200 having a peripheral portion 204. Figure 3(B) shows a cross-sectional view of the lens of Figure 3(A) (constrained in a fixture 208) taken along section XX'. Figure 3(C) is an enlarged view of the peripheral portion 204 shown in section CC' of Figure 3(B). Figures 3(B) and 3(C) depict the contour length of the end-to-end distance of the peripheral portion (represented by curve C1). The end-to-end distance is measured along the contour of the peripheral portion from the outer edge of the lens to the outermost edge of the peripheral portion. It can be seen that the contour is curved. Therefore, C1 represents the length of the curved path measured along the contour of the peripheral portion. In one embodiment, the curved contour can be a sinusoidal curve with regular periodicity and amplitude. In another embodiment, the curved profile can be a sinusoidal curve with regular periodicity and varying amplitude. When the temperature of the central portion of the lens changes, the lens expands, causing such periodicity and amplitude changes in the peripheral portion. FIG. 3(D) depicts the change in the profile as the shape of the peripheral portion changes. It can be seen that as the temperature changes, the length L1 of the profile measured in the radial direction decreases to a value L2.

[0055] When L1 is greater than L2, the actual size of the peripheral portion (the length or cross-sectional area of ​​the curvilinear path C1) does not change. Despite the fact that the periodicity and amplitude of the curvilinear profile change, the length C1 of the peripheral portion remains substantially the same. In other words, the length C1 of the curvilinear profile remains the same as the peripheral portion transitions from its lower energy state (having a length L1 in the radial direction) to its higher energy state (having a length L2 in the radial direction). When the temperature returns to its original value, the curvilinear portion will return to its original lower energy state (radial length L1).

[0056] Although Figures 2(A)-2(C) and 3(A)-3(D) all depict that the peripheral portion 204 is continuous around the central portion 202, the peripheral portion can also include multiple elements that contact the central portion 202 but do not contact each other. This can be seen in Figure 4(A), where the peripheral portion 204 includes multiple elements 204A, 204B, 204C, etc. that contact the central portion 202 but do not contact each other. Each of the elements 204A, 204B, 204C, etc. has spring-like properties that allow them to deform from a lower energy state to a higher energy state (or vice versa) when the central portion changes its size. The central portion can expand or contract depending on the ambient temperature. Figures 4(B) and 4(C) depict an embodiment where each of the elements 204A, 204B, 204C, etc. has a pre-arranged deformation point 210 that accommodates the size changes of the central portion 202. The pre-arranged deformation points 210 are points that use a lower activation energy than the surrounding material (which forms the elements 204A, 204B, etc.) in order to deform. In one embodiment, each of the elements 204A, 204B, 204C, etc. can have multiple pre-arranged deformation points (not shown) that can accommodate changes in the size of the central portion 202. In one embodiment, the multiple pre-arranged deformation points can act synchronously and cooperatively to accommodate changes in the size of the central portion 202. In another embodiment, the multiple pre-arranged deformation points can act asynchronously and / or cooperatively to accommodate changes in the size of the central portion 202. Synchronously means that multiple elements deform simultaneously. Cooperatively means that multiple elements all experience the same amount of deformation in the same direction (i.e., they all contract by the same amount at the same time or they all expand by the same amount at the same time).

[0057] Fig. 4 (B) and 4 (C) are cross-sectional views taken at the XX' section of Fig. 4 (A), and show another embodiment of the lens 200, wherein the peripheral portion 204 has a pre-arranged deformation point 210, which accommodates the size change of the central portion 202. Fig. 4 (B) shows the deformation point before deformation, and Fig. 4 (C) shows the deformation point after deformation. The pre-arranged deformation point 210 can be a groove, a notch or a cavity that makes it the weakest point on the peripheral portion. When the temperature change causes the lens size to change, the peripheral portion deforms at the pre-arranged deformation point 210.

[0058] Although Figures 4(A), 4(B) and 4(C) each show a plurality of elements 204A, 204B, 204C, etc. that are not in contact with one another, it will be appreciated that the peripheral portion in these figures may include a continuous portion that contacts the central portion 202 continuously around its periphery. In this case, there will be a continuous pre-arranged deformation point 210 that extends throughout the entire peripheral portion. It can be seen in Figures 4(A), 4(B) and 4(C) that each element 204A, 204B, 204C, etc. has a locating element at either end thereof that can contact the support means at one end and contact the lens at the other end. One locating element can secure the lens (i.e., the central portion), while the locating element at the opposite end can be used to secure the entire lens in place.

[0059] Figures 5(A), 5(B) and 5(C) depict a variety of different shapes (elements) that can be deployed in the peripheral area as one continuous element or multiple elements. Figures 5(A) and 5(B) show a spring-shaped element 204 with a sinusoidal profile. The element can absorb dimensional changes (of the central portion) in the form of energy and can return this energy to the lens when the deforming force is removed. Figure 5(A) depicts an element 204 with a sinusoidal profile having multiple troughs and peaks with uniform periodicity (all with constant amplitude). Each element 204 has a positioning element 212 at each end, which helps to contact the lens (at one end) and the support device (at the other end). Figure 5(B) depicts an element 204 with a sinusoidal profile that includes only one trough and peak, each trough and peak having the same amplitude and periodicity. The element 204 of Figure 5(B) also has a positioning element 212 at each end.

[0060] 5(C) depicts a pair of elements 204 having a plurality of pre-arranged inflection points 210 with positioning elements 212 at each end. Note that the various shapes shown for elements 204 are merely exemplary and that elements of various different shapes may be used in place of those shown herein.

[0061] Figure 6 Another exemplary embodiment of a lens 200 is shown in which the central portion 202 and the peripheral portion 204 have thermal expansion coefficients with opposite signs. For example, if the central portion has a positive thermal expansion coefficient, the peripheral portion has a negative thermal expansion coefficient. Conversely, if the central portion has a negative thermal expansion coefficient, the peripheral portion has a positive thermal expansion coefficient. In one embodiment, the material used in the peripheral portion has a thermal expansion coefficient that accommodates the difference in expansion between the central portion and the support device.

[0062] exist Figure 6In the embodiment shown, the peripheral portion 204 may include a single continuous element that contacts the lens at all points on its periphery via positioning elements 212A. The other end of the peripheral portion opposite the end that contacts the lens contacts a support device (not shown) via positioning elements 212B. In another embodiment, the peripheral portion 204 may include a plurality of elements (not shown), each of which contacts the lens at one end via positioning elements 212A and contacts the support device at the other end via another positioning element 212B.

[0063] The use of a peripheral portion that absorbs dimensional changes in the central portion by transitioning to a higher energy state or by having a thermal expansion coefficient with an opposite sign to that of the central portion prevents deformation of the central portion and minimizes aberrations of the imaged object. It also prevents the necessary replacement of the lens that may occur due to permanent deformation (sometimes referred to as permanent fixation). In another embodiment, when the central portion and the peripheral portion have respective thermal expansion coefficients with different signs (positive or negative), the entropy of the central portion and the entropy of the peripheral portion both decrease simultaneously with increasing temperature, and vice versa.

[0064] The material used in the lens is an optically transparent polymer. In one embodiment, the polymer is preferably a water-resistant, UV radiation-resistant and abrasion-resistant polymer. If desired, a waterproof and / or abrasion-resistant coating can be provided on the lens. UV-resistant coatings, heat stabilizers, UV absorbers, infrared-resistant coatings, etc. can also be used in or on the lens. It is desirable that the transmittance of the polymer material is greater than 85%, preferably greater than 90%, and more preferably greater than 95% when measured according to ASTM D1003. The refractive index of the polymer used in the lens can be 1.1 to 1.7, preferably 1.2 to 1.65, and more preferably 1.45 to 1.58. If desired, a coating with a higher refractive index, such as a coating containing titanium dioxide or zirconium oxide, can be provided on the lens.

[0065] In one embodiment, a single polymer may be used throughout the lens. In another embodiment, a first polymer may be used in the central portion of the lens and a second polymer may be used in the peripheral portion. In one embodiment, the first polymer may be the same as the second polymer. In another embodiment, the first polymer may be different from the second polymer.

[0066] The first polymer used in the central portion will have a different elastic modulus than the second polymer used in the peripheral region. In one embodiment, the first polymer may have a higher elastic modulus than the second polymer. In another embodiment, the first polymer may have a lower elastic modulus than the second polymer. Even when the central portion comprises the same polymer as the peripheral portion, the peripheral portion will have a different elastic modulus than the central portion. This is typically achieved by using fillers and / or impact modifiers.

[0067] The polymer used in the lens can be selected from a variety of thermoplastic polymers, blends of thermoplastic polymers, thermosetting polymers, or blends of thermoplastic polymers and thermosetting polymers. The polymer is preferably an organic polymer. The polymer may include a blend, a copolymer, a terpolymer, or a combination thereof of polymers. The polymer may also be an oligomer, a homopolymer, a copolymer, a block copolymer, an alternating block copolymer, a random copolymer, a graft copolymer, a star block copolymer, a dendrimer, a polyelectrolyte (a polymer with some repeating groups, which contains an electrolyte), a polyampholyte (a polyelectrolyte with cationic and anionic repeating groups), an ionomer, etc., or a combination thereof. The number average molecular weight of the organic polymer is greater than 10,000 g / mol, preferably greater than 20,000 g / mol, and more preferably greater than 50,000 g / mol. The upper limit of the number average molecular weight of the polymer may be 1,000,000 g / mol.

[0068] Examples of organic polymers that can be used in the lenses are polyolefins, polyacrylates, polyacrylates, polymethacrylates, polycarbonates, polystyrenes, polyesters, polyimides, polyetherimides, and the like, or combinations thereof. Polyolefin lenses are preferred.

[0069] The polyolefin is preferably a polyolefin having low ultraviolet (UV) absorption when exposed to ambient light. Suitable examples of polyolefins are cyclic olefin polymers. In one embodiment, the cyclic olefin polymers include cyclic olefin copolymers. Cyclic olefin copolymers are obtained by combining cyclic monomers such as 8,9,10-trinorbornene-2-ene (norbornene) or 1,2,3,4,4a,5,8,8a-octahydro-1,4:5,8-dimethylnaphthalene (tetracyclododecene) with ethylene (e.g., TOPAS Advanced Polymer). Mitsui Chemical ) or by ring-opening metathesis polymerization of various cyclic monomers followed by hydrogenation (Japan Synthetic Rubber Zeon Chemical and ) manufactured.

[0070] When the peripheral portion absorbs the dimensional changes of the central portion by absorbing energy due to its spring-like properties, the material used does not have to be optically transparent. Ideally, during the energy absorption process, the material used in the peripheral portion deforms to a point below the yield point of the material. The polymer used in the peripheral portion may not be optically transparent and may contain fillers and impact modifiers to give it the desired mechanical properties for energy absorption and energy release.

[0071] Suitable polymers for the peripheral portion include polyacetal, polyacrylate, polycarbonate, polyalkyd acid, polystyrene, polyolefin, polyester, polyamide, polyaramid, polyamideimide, polyarylate, polyurethane, epoxy resin, phenolic resin, silicone resin, polyaryl sulfone, polyether sulfone, polyphenylene sulfide, polysulfone, polyimide, polyetherimide, polytetrafluoroethylene, polyetherketone, polyetheretherketone, polyetherketoneketone, polybenzoxazole, polyoxadiazole, polybenzothiazine and benzothiazine, polybenzothiazole, polypyrazinoquinoxaline, polypyromellitic acid imide, polyquinoxaline, polybenzimidazole, polyindole, polyphenylene sulfide, polyimide, polyetherimide, polytetrafluoroethylene, polyetherketone, polyetheretherketone, polyetherketoneketone, polybenzoxazole, polyoxadiazole, polybenzothiazine and benzothiazine, polybenzothiazole, polypyrazinoquinoxaline, polypyromellitic acid imide, polyquinoxaline, polybenzimidazole, polyindole, polyindole, polyphenylene sulfide, polyimide, polyetherimide ...etherimide, polytetrafluoroethylene, polyetherketone, polyetheretherketone, polyetherketone Indole, polyoxyisoindoline, polydioxyisoindoline, polytriazine, polypyridazine, polypiperazine, polypyridine, polypiperidine, polytriazole, polypyrazole, polycarborane, polyoxabicyclononane, polydibenzofuran, polyphthalate, polyacetal, polyanhydride, polyvinyl ether, polyvinyl sulfide, polyvinyl alcohol, polyvinyl ketone, polyvinyl halide, polyvinyl nitrile, polyvinyl ester, polysulfonate, polysulfide, polythioester, polysulfone, polysulfoneamide, polyurea, polyphosphazene, polysilazane, polypropylene, polyethylene, polyethylene terephthalate, polyvinylidene fluoride, polysiloxane, etc., or a combination thereof.

[0072] When the peripheral portion comprises a polymer having a CTE of opposite sign to the material used in the lens, it is desirable that the polymer used in the peripheral portion is an elastomer. Examples of elastomers include polybutadiene, polyisoprene, styrene-butadiene rubber, poly(styrene)-block-poly(butadiene), poly(acrylonitrile)-block-poly(styrene)-block-poly(butadiene) (ABS), polychloroprene, epichlorohydrin rubber, polyacrylic rubber, silicone elastomer (polysiloxane), fluorosilicone elastomer, fluoroelastomer, perfluoroelastomer, polyether block amide (PEBA), chlorosulfonated polyethylene, ethylene propylene diene rubber (EPR), ethylene-vinyl acetate elastomer, etc., or combinations thereof. In one embodiment, the elastomeric polymer or the polymer in its elastomeric form (above the glass transition temperature) generally has a negative coefficient of thermal expansion and can therefore be used with a central portion having a positive coefficient of thermal expansion.

[0073] In one embodiment, in a method of making the disclosed lens, a suitable polymer (e.g., one or more of the cyclic olefin copolymers listed above) is fed into an injection molding machine where it is molded in a mold having a negative image of the lens shown in the figure. The polymer is injected into the mold at a suitable flow temperature that prevents the formation of pinholes and other defects. The walls of the mold are cooled with a coolant, thereby solidifying the melt, at which point it is ejected from the mold. Large quantities of lenses can be produced in this manner.

[0074] In one embodiment, the lens may also be manufactured by methods such as compression molding, vacuum molding, blow molding, etc. In another embodiment, additive manufacturing may be used to manufacture the lens disclosed herein. In yet another embodiment, a combination of one or more of injection molding, vacuum molding, blow molding, compression molding may be used in conjunction with additive manufacturing.

[0075] In one embodiment, the molding operation for making the mold is prepared in a two-step process. In another embodiment, when the lens includes a foamed peripheral portion, the foamed peripheral portion can be first injection molded in a first molding step. A suitable foaming agent, such as liquid carbon dioxide, liquid nitrogen, etc., can be used to produce the foam. The molded foamed peripheral portion is then placed in a second mold, and then the central portion is injected into the mold and fused with the peripheral portion during the second molding operation. The polymer used in the central portion (first polymer) can be the same or different from the polymer used in the peripheral portion (second polymer). The mold is then cooled, and the molded lens with the foamed peripheral portion and the optically transparent central portion is ejected.

[0076] The lens can be processed to remove any mold lines and then placed in structural devices used in automobiles, medical devices inserted into the human body (such as catheters), and downhole drilling tools (to measure the progress of excavation). In one embodiment, the lens can be positioned in the appropriate position by using positioning elements present on one or more ends of the peripheral portion.

[0077] Although the present invention has been described with reference to some embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for its elements without departing from the scope of the present invention. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the present invention without departing from its basic scope. Therefore, it is intended that the present invention is not limited to the specific embodiments disclosed as the best mode intended for carrying out the present invention, but that the present invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A lens comprising: a central portion comprising a first polymer; wherein said central portion is operable to emit electromagnetic radiation through said central portion; and a peripheral portion comprising a second polymer; wherein the peripheral portion accommodates changes in size of the central portion by absorbing energy and transitioning from a lower energy state to a higher energy state; The cross section of the peripheral portion has a curved profile before absorbing energy; the curved profile is a sinusoidal profile, and when the temperature changes, the periodicity and amplitude of the cross section of the peripheral portion change.

2. The lens of claim 1 , wherein the peripheral portion undergoes a change in shape without any substantial change in size.

3. The lens of claim 1, wherein the first polymer is the same as the second polymer. The lens of claim 1 , wherein the first polymer is different from the second polymer.

5. The lens of claim 1, wherein the peripheral portion surrounds the central portion along its entire circumferential periphery.

6. The lens of claim 5, wherein the peripheral portion comprises a plurality of elements that are not in contact with each other.

7. The lens of claim 6, wherein the curved profile is a sinusoidal profile that may include one or more troughs and one or more peaks.

8. The lens of claim 7, wherein the sinusoidal profile may contain a plurality of troughs and peaks having varying amplitudes and periodicities, and wherein the amplitude or periodicity changes upon energy absorption.

9. The lens of claim 1, wherein the second polymer has a negative coefficient of thermal expansion and the first polymer has a positive coefficient of thermal expansion.

10. The lens of claim 1, wherein the first polymer and the second polymer comprise cyclic olefin polymers.

11. The lens of claim 10, wherein the cyclic olefin polymer comprises a cyclic olefin copolymer.

12. An article comprising the lens of claim 1.

13. The article of manufacture of claim 12, wherein the article is an advanced driver assistance system.

14. A method for manufacturing a lens, comprising: injecting a molten polymer into a mold to produce the lens; The lens comprises: central portion; and A peripheral portion; wherein the peripheral portion accommodates the dimensional change of the central portion by absorbing energy and transitioning from a lower energy state to a higher energy state; wherein the cross-section of the peripheral portion has a curved profile before absorbing energy; the curved profile is a sinusoidal profile, and the periodicity and amplitude of the cross-section of the peripheral portion change when the temperature changes.

15. The method of claim 14, wherein the molten polymer comprises a polyolefin.

16. The method of claim 15, wherein the polyolefin comprises a cyclic olefin copolymer.

17. The method of claim 15, further comprising placing the lens in a fixture. 18 . The method according to claim 17 , wherein the fixing device in which the lens is arranged is provided in an advanced driver assistance system.

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