Optical device with stray light reduction

Abstract

To provide a cost-effective optical device for minimizing stray light.SOLUTION: An optical device includes: a beam-forming element 12 made of a first material with a base surface 20 and a top surface 22, which are opposite one another, and with a surrounding lateral surface 24, which connects the base surface and the top surface to one another; a support body 14 made of a second material, which is formed with a receptacle 18 for the beam-forming element and has at least one common contact surface 26 with the lateral surface 24 of the beam-forming element. The first material and the second material are in direct contact with each other at the contact surface between the beam-forming element and the support body. The first material is permeable to a prescribed electromagnetic radiation, and the second material is absorbent of the prescribed electromagnetic radiation. The first material and the second material each have a prescribed refractive index (n1, n2) in relation to the prescribed electromagnetic radiation. The prescribed refractive index (n2) of the second material is set in a prescribed ratio to the prescribed refractive index (n1) of the first material.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an optical device, in particular a safety light barrier, a safety light grid or a safety laser scanner, and to a corresponding method for manufacturing such a device. [Background technology]

[0002] In general, an optical device is any technological device that uses electromagnetic radiation, especially light, to capture, process, manipulate or display information. Optical devices are used in many fields, such as photography, astronomy, microscopy, ophthalmology, communications, consumer electronics and many others. Optical devices use the properties of light, such as reflection, refraction and absorption. They use lenses, mirrors, prisms and other optical components to guide and shape light. Examples of optical devices include cameras, binoculars, microscopes, telescopes, lasers, projectors, screens and optical sensors.

[0003] Optical sensors are devices that use light to measure or detect certain physical or chemical properties. They convert the optical signal into an electrical signal that is then analyzed and interpreted.

[0004] Optical sensors are used in many fields (e.g. industry, medicine, environmental monitoring, safety technology and automation). Examples of optical sensors include light barriers, including light grids or laser scanners. Light barriers have one or more light sources (light transmitters) and one or more light receivers. If the light between the transmitter and receiver is interrupted, for example by an object or a person, the sensor detects the change and emits a signal. Light barriers and light grids are often used in automation technology for access control and in electro-sensitive protective equipment (ESPE).

[0005] When using ESPEs such as light grids in technical systems, various standards and safety regulations must be adhered to. In Europe these include EN ISO 13849-1, EN 61496-1 and EN 61496-2, and EN 62046.

[0006] EN ISO 13849-1 deals with the safety of machinery and specifies requirements for safety-related control systems, including the use of light curtains as protective devices. EN 61496-1 and EN 61496-2 describe the general requirements and methods for light curtains and light barriers, including their electrical and optical properties. EN 62046 deals with the use of light curtains for machine control and describes requirements for the function, installation, commissioning, operation and maintenance of light curtains.

[0007] For ESPE, these standards provide, inter alia, to limit the permissible aperture angles for the transmitters and receivers (i.e., to limit and minimize, inter alia, the effects of stray light in the system). A significant source of scattered light is the reflection and scattering of light at the walls of the housings that delimit the optical channels (e.g. tubes).

[0008] Known methods for dealing with stray light include light traps: these prevent light rays from being reflected or scattered off walls and reaching the detector.

[0009] As an example of such a light trap, the following Patent Document 1 shows an element holder as an element integral with a light-blocking component for limiting the scattering angle of light. The element holder has a cylindrical internal channel and can removably hold an optical element at one end. A lens is attached to one of the other ends of the element holder. The element holder is a molded plastic member and has a single light-blocking wall molded integrally with the element holder to extend across the internal channel in a plane approximately equidistant from the photoelectric detector element and the lens to limit the angle of light scattering.

[0010] US Pat. No. 5,399,633 gives another example of the use of optical traps in optical barriers or optical lattices.

[0011] Another way to deal with stray light is to use special filters or adapted light sources. An example of this is shown in US Pat. No. 5,399,633, where a phosphorus-based layer, e.g. comprising a mixture of nanophosphors and / or quantum dot phosphors, is used to filter the received light (including both intended reflected light and sunlight) before it is received by the photodetector. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] European Patent Application Publication No. 1 420 271 A2 [Patent Document 2] DE 199 10 321 A1 [Patent Document 3] European Patent Application Publication No. 2 535 741 A2 Summary of the Invention [Problem to be solved by the invention]

[0013] Against this background, it is an object of the present invention to provide a novel cost-effective method for minimizing stray light. Another object is to provide a manufacturing method for optical devices that efficiently implements the novel cost-effective method for minimizing stray light. [Means for solving the problem]

[0014] According to one aspect of the present disclosure, this problem is solved by an optical device comprising a beam shaping element of a first material having opposite base and top surfaces and surrounding sides connecting the base and top surfaces, and a support (carrier) of a second material formed with a receptacle (holder) for the beam shaping element and having at least one common contact surface with the sides of the beam shaping element.

[0015] The first material and the second material are in direct contact with each other at the interface between the beam shaping element and the support. The first material is transparent to the predetermined electromagnetic radiation, and the second material is absorptive to the predetermined electromagnetic radiation. Furthermore, the first material and the second material each have a predetermined refractive index (n1, n2) for the predetermined electromagnetic radiation. In order to set a specific transition characteristic for the predetermined electromagnetic radiation at the interface, the predetermined refractive index of the second material is set to a predetermined ratio with respect to the predetermined refractive index of the first material.

[0016] According to a further aspect of the present disclosure, the problem is further solved by a manufacturing method for an optical device comprising a beam shaping element and a support. The method includes the steps of providing a first material for the beam shaping element, the first material being transparent to a predetermined electromagnetic radiation and having a first predetermined refractive index for the predetermined electromagnetic radiation; providing a second material for the support, the second material being absorptive to the predetermined electromagnetic radiation and having a second predetermined refractive index for the predetermined electromagnetic radiation; forming the beam shaping element from the first material and the support from the second material; and joining the first and second materials to form an integrally joined (integral and therefore non-destructively separable) part from the first and second materials, the beam shaping element having opposing base and top surfaces and an enclosing side surface joining the base and top surfaces to each other, the support being formed with an inlet for the beam shaping element and having at least one common contact surface with the enclosing side surface of the beam shaping element, at which the predetermined refractive index of the second material is set in a predetermined ratio to the predetermined refractive index of the first material in order to set a specific transition characteristic for the predetermined electromagnetic radiation.

[0017] This is therefore an idea to counteract the undesirable effects of stray light, which may affect optical devices, by selecting materials for the beam-shaping element and its support and by bonding them. For this purpose, at least one contact surface between the beam-shaping element and the support, where reflection or refraction of light is to be avoided or at least reduced, must be arranged in such a way that the material of the beam-shaping element and the material of the support are in direct contact with each other at the contact surface. Preferably, the beam-shaping element and the support are bonded to each other during assembly in such a way that there are no cavities at the contact surface, in particular that no gas medium is trapped between the first and second materials. Preferably, the first and second materials are therefore placed directly and flat against each other at the contact surface, without a third material different from the first and second materials being placed between them.

[0018] In some preferred embodiments, the first and second materials are integrally joined to one another in an injection molding process. For example, the first material can be cast onto the second material or vice versa. In other preferred embodiments, the first and second materials can be heat welded to one another, in particular by laser welding. In principle, it is also conceivable to join the first and second materials to form an integral part by melting with a volatile adhesive or by direct spraying and without an intermediate layer of a different material.

[0019] The beam-shaping element (e.g. lens) is made of a material that is transparent to the given electromagnetic radiation, in particular in the visible and / or infrared wavelength range. The support, at least in the part located behind the contact surface, is made of a material that absorbs the electromagnetic radiation in the wavelength range. Furthermore, the refractive index of the beam-shaping element and the support is selected for the electromagnetic radiation in such a way that a specific transition characteristic is realized at the contact surface. In particular, the refractive index is selected in such a way that the electromagnetic radiation can enter the second material at at least one contact surface as free as possible from reflection and is then absorbed by the second material as much as possible (i.e. in particular, due to the material combination, the contact surface is largely low-reflecting and low-refractive).

[0020] It turns out that the refractive index of the material of the beam-shaping element and the material of the support should be matched. The ratio between the refractive indexes is preferably 1. From the Fresnel formula, it follows that with essentially the same refractive index in a certain range of incidence angles, the incident light can enter the support material largely unreflected and unrefracted and can be absorbed thereby. Thus, light hitting the contact surface from this incidence angle can be prevented in a simple and effective way from propagating further through the beam-shaping element. In this way, the detection of the incident light or the emission of the light beam can be advantageously controlled while the scattered light effect can be effectively avoided or reduced. Preferably, the material for the beam-shaping element and the material for the support are the same material with different absorption coefficients. That is to say, the first material and the second material are based on the same basic material. The materials can be processed into the support and the beam-shaping element in a joint forming process.

[0021] The scattered light reduction is essentially set via the material of the support and the beam-shaping element and its processing, so that the structure of the beam-shaping element and the support can essentially be freely selected. This opens up new possibilities for the simpler, more efficient, faster and cheaper manufacture of optical devices. Thus, the object mentioned at the beginning is achieved.

[0022] In a further refinement, the predetermined ratio of the refractive indices of the support material and the material of the beam-shaping element may be between 0.9 and 1.1, preferably between 0.95 and 1.05, in particular 1.

[0023] In this configuration, the refractive indices of the different materials for the beam shaping element and the support are preferably made to be the same, or at least very similar, in order to achieve the desired transition characteristics, which can be easily achieved by using the same base material for both parts, whereby the base material is made radiation-absorptive relative to the support, for example by adding a dye.

[0024] In a further refinement, certain transition characteristics can make the interface low-reflection and low-refraction (particularly reflection-free and refraction-free for certain electromagnetic radiation coupled through the base and top surfaces).

[0025] Furthermore, in a further refinement, the particular transfer characteristic can be such that certain electromagnetic radiation coupled by the base and top surfaces at a certain range of angles of incidence is absorbed by the second material.

[0026] The transition characteristics can be adjusted by the choice of material, thus making it possible to adapt the contact surface to the required conditions, which may be dictated by the structure of the beam-shaping element and / or the support, the type of electromagnetic radiation or the type of coupling of the electromagnetic radiation to the beam-shaping element. The optical device can be designed in this way in a particularly flexible manner.

[0027] In a further refinement, the first material may be a transparent plastic and the second material is a coloured or pigmented (in particular black pigmented) plastic.

[0028] Plastics can be easily molded into different shapes. The properties of plastics can also be influenced by adding various foreign bodies. This concerns the optical properties in particular. Furthermore, plastics can be well processed by injection molding processes. For example, different plastics can be simultaneously processed in an injection molding process to join together and form an integral part, in order to create a direct seamless connection between the individual plastics. Black plastics are particularly light absorbing. The use of plastics as a basic material therefore advantageously simplifies the construction of the optical device described above.

[0029] In a further refinement, the plastic used for the first and / or second material may comprise or consist of polycarbonate (PC), polymethyl methacrylate (PMMA), cycloolefin copolymer, optical polyester or polysulfone. PMMA or polymethyl methacrylate is also known as acrylic glass or plexiglas. PMMA is a transparent thermoplastic polymer formed with methyl methacrylate monomer units and is characterized by high light transmission and optical clarity. It is almost colorless to the human eye and has a transparency similar to glass, but with a lower weight. Therefore, the use of PMMA as a base material is advantageous for the optical properties of the optical device. Polycarbonate is preferred in some embodiments due to its good mechanical properties, such as elongation at break and impact strength. The polycarbonate substrate allows for connection options such as snap-on hooks or cold embossing points that would be difficult to achieve with PMMA.

[0030] The beam-forming element and the support can be designed as one piece (ie integrally joined parts) and can be formed by a multi-component injection molding process (eg a cascade injection molding process or a sandwich injection molding process).

[0031] A one-piece part, which is at least two parts joined together, simplifies the assembly of the optical device and allows it to be manufactured in a cost-effective way. The multi-component injection molding process allows a seamless connection between materials in a very efficient way, which is used in a proven and automated manufacturing process. This ensures that the effect of the above-mentioned material selection (adjustment of the refractive index) is manifested at the interface, since no other medium is trapped between the materials. In addition, injection molding generally allows a very flexible formation. In principle, however, one-piece parts can also be manufactured in other ways (for example, using a laser welding process, in which the beam-forming element and the support are joined together to form the one-piece part).

[0032] In a further refinement, the outlet is funnel-shaped and tapers in a direction from the top surface to the base surface.

[0033] According to this design, the inlet may be funnel-shaped, which allows an advantageous reduction in the dimensions of the beam-forming element. Funnel-shaped designs are generally rather unsuitable for reducing scattered light, but can nevertheless be used here thanks to the special selection of materials in such a way that the above-mentioned reduction in dimensions is realized. Reducing the dimensions of the beam-forming element helps to save material and minimizes the possibility of air bubbles forming in the element body, since the overall volume of the beam-forming element becomes smaller. This configuration therefore further contributes to a cost-effective and optimized design of the optical device.

[0034] In a further refinement, the plug can surround at least a part of the base surface with at least one opening for a given electromagnetic radiation, the opening being designed as an opening for a photoelectric element (e.g. a photoelectric emitter or detector) in the beam path. In a further refinement, which can alternatively or additionally be implemented, the plug forms a tube protruding from the top surface.

[0035] According to this design, one or more optical apertures in the beam path of the optical device can be realized directly through the support, thereby eliminating further elements and manufacturing steps. In some preferred embodiments, the support forms an aperture stop in the beam path. Furthermore, the support can form an aperture, which defines the resolution of the light grating with a number of light rays running parallel to one another. In particularly preferred embodiments, the beam shaping element and the inlet form a one-piece part implementing an optical lens and a tube with an aperture that defines the resolution. All these variants contribute to further cost savings in the manufacture of optical devices, especially in the form of safety light barriers or safety light gratings.

[0036] The aperture may be filled with the material of the beam forming element.

[0037] This design simplifies the design by facilitating the joining of the support and the beam shaping elements into a single piece. This improvement can therefore contribute to further cost savings. A further advantage of this design is that the two-component (2K) injection molding manufacturing process allows the lens axis and the pinhole axis (tube) to be located very precisely on top of each other and to keep the deviation from the ideal optical axis very small. This improves the usability and alignability of the optical grating.

[0038] In a further refinement, protruding structures are formed on the receptacle to act as light traps.

[0039] For example, the structure may include staircase steps, crenellated projections and / or multiple comb-like high walls. As explained at the beginning, optical traps are already known as such. However, this embodiment can be particularly advantageously combined with a specific transition characteristic at the interface between the first and second materials. This is because the favorable effect of the specific transition characteristic is particularly effective when the angle of incidence of a given electromagnetic radiation is smaller. On the other hand, optical traps are particularly effective when the angle of incidence is larger.

[0040] In a further refinement, the optical device comprises a number of beam-forming elements, each having its own insertion in the support.

[0041] In this refinement, the beam-shaping elements can be formed simultaneously with the support, which advantageously simplifies the manufacture of special optical devices such as light gratings having multiple optical elements.

[0042] In a further refinement, the optical device is an optical sensor, in particular a safety light grid or a laser scanner, which meets the safety requirement level SIL 3 according to IEC 61508 / IEC 61511 or the performance level PL d according to EN ISO 13849-1.

[0043] As already mentioned, optical sensors are devices that use light to measure or detect certain physical or chemical properties. They convert the optical signal into an electrical signal, which can then be analyzed and interpreted. In optical sensors, it is particularly important that only dedicated light triggers the detection, and that unwanted stray light is avoided, which may lead to false triggering or, even worse, may prevent the detection of safety-relevant objects. This can be advantageously achieved by the above-mentioned designs, resulting in an optimized optical sensor.

[0044] In a further refinement, the optical device may be an optical grating.

[0045] The optical grid comprises, for example, many optical elements which cooperate to create an electro-photosensitive protection device (ESPE), i.e. a contactless protection device. The optical grid can be implemented in this way in a particularly cost-effective manner, since many optical elements corresponding to the above-mentioned configurations can be realized in a simple manner.

[0046] It is understood that the features mentioned above and those to be explained below can be used not only in the combination suggested in each case but also in other combinations or on their own, without departing from the scope of the invention.

[0047] Examples of embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. [Brief description of the drawings]

[0048] [Figure 1] 1 shows a schematic cross-sectional view of an optical device having a light trap for minimizing stray light, according to the prior art; [Diagram 2] 1 shows a schematic cross-sectional view of an optical device according to an embodiment of the invention having a passive optoelectronic element; [Diagram 3] 3 shows a schematic cross-sectional view of an optical device according to the embodiment of FIG. 2 having an active optoelectronic element; [Figure 4A] A variant of the embodiment according to FIG. 2 is shown in plan view. [Figure 4B] A variant of the embodiment according to FIG. 2 is shown in cross section. [Figure 4C] A variant of the embodiment according to FIG. 2 is shown in cross section. [Diagram 5] A further variant of the embodiment according to FIG. 2 is shown in cross section. [Figure 6A] A further variant of the embodiment according to FIG. 2 is shown in cross section. [Figure 6B]A further variant of the embodiment according to FIG. 2 is shown in cross section. [Figure 7A] An application example of the optical device of the present disclosure is shown in a perspective view. [Figure 7B] 7B shows a plan view of the application example shown in FIG. 7A. [Figure 7C] FIG. 7B shows a side view of the application shown in FIG. 7A. [Figure 7D] An application example according to FIG. 7A is shown in cross section along line CC' in FIG. 7C. [Figure 8A] 13 shows a variant with additional light traps inside the support. [Figure 8B] 13 shows a variant with additional light traps inside the support. [Figure 8C] 13 shows a variant with additional light traps inside the support. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] FIG. 1 shows an optical device 1 with light traps for minimizing stray light, corresponding to the state of the art.

[0050] In the illustrated embodiment, the prior art optical device 1 consists of three separate parts: a beam-forming element (lens) 2, a support in the form of a tube 3, and a photoelectric element 4. Electromagnetic radiation (particularly light) is coupled into the optical device via the beam-forming element 2. The tube-shaped support 3 forms an optical channel for guiding the coupled light to the photoelectric element 4. A light trap is formed inside the tubular support 3 to prevent some incident light (particularly light reflected from the tube walls) from reaching the photoelectric element 4. The light trap 5 reduces the influence of stray light in the detection by the photoelectric element 4.

[0051] FIG. 2 shows an optical device according to an embodiment of the present invention.

[0052] Here, the optical device is designated as a whole by the reference number 10. Like the optical devices of the prior art, the optical device 10 also comprises a beam-forming element 12 and a corresponding support 14. In addition, an optoelectronic element 16 may be provided, which in the present example is designed as a detector for electromagnetic radiation (in particular light). In other embodiments, the optoelectronic element may also comprise a transmitter for electromagnetic radiation (in particular light in the visible and / or infrared range). Such a transmitter will be referred to below as an active element and the detector as a passive optoelectronic element.

[0053] The support 14 is designed as a plug 18 or has at least one such plug, to which the beam shaping element 12 is attached. The beam shaping element 12 has a base surface 20, a top surface 22 opposite the base surface, and a side surface 24 connecting the base surface and the top surface. The beam shaping element 12 may be a homogenous object having a uniform composition and structure, i.e. the material properties such as density, chemical composition and physical properties may be the same in every part of the object.

[0054] As shown here, the inlet 18 for the beam shaping element 12 may be designed as a tube, the free end of which protrudes beyond the top surface 22 and thus forms an aperture. In a light barrier, a light grating or a laser scanner, this aperture may define the resolution with which the optical device can detect objects.

[0055] However, the shape of the receptacle 18 is not limited thereto. The beam shaping element 12 received in the receptacle 18 has at least one common contact surface 26 with the support 14, where the contact surface 26 is a section of the side surface 24. In various embodiments, the contact surface 26 may comprise the entire side surface 24 and even a portion of the base surface 20.

[0056] Top surface 22, or at least a portion thereof, is exposed from support 14. Electromagnetic radiation may be coupled into optical device 10 from the outside via top surface 22 (see FIG. 2) or electromagnetic radiation may be emitted from optical device 10 via top surface 22 (see FIG. 3).

[0057] In the illustrated example, the optical axis 28 of the optical device 10 extends along a first direction (hereinafter referred to as the x-direction). The base surface 20 and the top surface 22 of the beam-shaping element 12 are oriented transversely, in particular perpendicular to the x-direction. The side surface 24 may then be a surface of rotation about the optical axis 28 or a surface consisting of multiple side surfaces connecting the base surface 20 and the top surface 22 together. In the illustrated example, the side surface has a first side surface and a second side surface extending in a second direction (in particular perpendicularly) perpendicular to the first direction (hereinafter referred to as the y-direction). The first side surface and the second side surface are here part of a contact surface 26 with the support 14. The top surface 22 may be free from the support 14 in the x-direction.

[0058] Electromagnetic radiation is coupled into the optical device 10 from the outside or emitted via the top surface 22. A base surface 20 is opposite the top surface 22 and is at least partially covered by the support 14. An opening (aperture) 30 may be provided in the base surface 20, through which the electromagnetic radiation can be emitted to the photoelectric element 16 or through which the photoelectric element 16 can couple radiation into the beam-forming element 12. The opening 30 may also perform other optical functions, for example as an aperture stop. In a third direction running perpendicular to both the first direction and the second direction (hereinafter referred to as the z-direction), the beam-forming element 12 may also be surrounded by the support 14, so that these parts may also be part of the contact surface 26.

[0059] The material forming the beam shaping element 12 (first material) and the material forming the support 14 (second material) are selected or prepared in a specific way in order to achieve a predetermined transition characteristic of the electromagnetic radiation propagating through the beam shaping element 12 at the contact surface 26. The first material is a material that is transparent to the electromagnetic radiation, preferably colorless and has a transparency similar to that of glass. In contrast, the second material is an opaque material that absorbs the electromagnetic radiation. The degree of absorption of the second material for the electromagnetic radiation is made as high as possible. The second material is therefore preferably black.

[0060] The beam shaping element 12 is integrated into the receptacle 18 in such a way that the first material is seamless to the second material at least at the common interface 26. The transition characteristics at the interface 26 are essentially determined by the refractive indices (n1, n2) of the first and second materials according to the Fresnel formula. In order to achieve the lowest possible reflective and refractive transition characteristics at the interface, the refractive indices (n1, n2) of the first and second materials are preferably within a narrow tolerance (e.g., less than 5%). TIFF2025026799000002.tif1132

[0061] In this case, light rays impinging on the contact surface 26 (at least within a certain range of angles of incidence) are not refracted or reflected at the contact surface, or are only slightly refracted or reflected, but pass almost completely into the second material of the support 14, where they are absorbed.

[0062] Unwanted scattered light, illustrated here by arrow 32, which is coupled through the top surface 22 into the beam forming element 12 at an angle to the optical axis 28, is usually not reflected at the contact surface 26 towards the photoelectric element 16, as illustrated here by dashed arrow 34, but is absorbed by the material of the support 14. This prevents the unwanted scattered light from reaching the photoelectric element 16 and causing a false detection. Thus, in some embodiments, the optical device according to Fig. 2 can be realized without the light trap shown in Fig. 1 or the filter mentioned in the introduction to the description. However, in other embodiments, the optical device may have additional structures inside the receptacle 18 that act as light traps.

[0063] The structure may for example be stepped steps formed in a funnel-shaped section tapering towards the base surface 20 (FIG. 8A), concentric walls rising from the base surface 20 in a comb-like cross section (FIG. 8B), or crenellated protrusions on the inner wall of the inlet 18 (FIG. 8C). Hence, minimization of scattered light can only (or in addition to light trapping) be achieved by a proper choice of material and a seamless construction of the beam shaping elements 12 at the inlets 18 of the support 14.

[0064] To achieve the specific material selection and the required seamless configuration of the beam-shaping elements 12 on the support 14, the optical device 10 can be advantageously realized by injection molding. Injection molding allows two materials, especially plastics, to be joined in such a way that the joint is seamless and generally inseparable. Injection molding, in which at least two materials are combined to form a one-piece part, is also known as two-component (2K) or multi-component injection molding. There are various two-component injection moldings that can be used. These include cascade injection molding and sandwich injection molding. In cascade injection molding, a first component is injected into an injection mold and then a second component is injected into the first component. The mold is usually designed so that the second component flows into the cavity of the first component to form a solid bond. In sandwich injection molding, two components are injected into the mold at the same time, one component surrounding the other.

[0065] The beam shaping element 12 can be one part and the support 14 can be the other part. It does not matter which part is the first part and which is the second part. Depending on the desired application and the desired structure of the optical device 10, the beam shaping element 12 can be injected into the support 14 during injection molding or vice versa. Preferably, the beam shaping element 12 (lens) is injected first, followed by the enclosing tube 14 as support, since in this case the tube shrinks into the lens during cooling.

[0066] In addition, the material selection required to achieve the desired effect is also facilitated by the use of injection molding processes, since multi-component injection molding processes are generally designed for the use of different materials. The starting materials for the beam shaping elements 12 and the support 14 are preferably the same material, in particular a plastic such as polycarbonate or PMMA. In order to adjust the required absorption capacity of the second material, the common starting material for the support 14 may be provided with pigments to achieve a high absorption for electromagnetic radiation. While a high absorption is achieved by this modification, the refractive index remains unchanged by this modification of the starting material, so that the first material and the second material have essentially the same refractive index. The starting material (first material) and the modified starting material (second material) can then be injection molded in a manner known per se to form a one-piece part with the above-mentioned structure and material properties.

[0067] The use of a common base material also has the advantage that temperature effects act equally on both parts and therefore stresses between the individual parts (in this case the beam-forming element 12 and the support 14) can be advantageously avoided.

[0068] FIG. 3 shows an optical device according to the embodiment of FIG. 2 having an active optoelectronic element 16'.

[0069] The optical device 10 according to Fig. 3 corresponds to the optical device 10 according to Fig. 2 with respect to the beam-forming element 12 and the support 14. This embodiment differs only with respect to the active optoelectronic element 16', which is now an active element. The active element 16' is designed to emit electromagnetic radiation and couple it into the beam-forming element 12, so that a large part of the radiation coupled by the optoelectronic element 16' propagates through the beam-forming element 12 and is emitted to the outside via the top surface 22. However, some of the radiation may also impinge on the contact surface 26 between the beam-forming element 12 and the support 14, as shown by the light ray 36. This radiation is also absorbed as completely as possible by the support 14, according to the special design of the support 14 and the beam-forming element 12, so that no or only little reflection occurs, as shown here by the light ray 38.

[0070] Advantageously, the described structure can therefore also improve the radiation characteristics of the optical device 10. It is understood that the designs shown in Figures 2 and 3 can also be combined. For example, a so-called transceiver optical grating has many optoelectronic elements on each side of the optical grating, which alternately contain transmitters or receivers.

[0071] 4A, 4B and 4C each show a schematic diagram of a further variant of the embodiment according to FIG. 2 from different perspectives.

[0072] As can be seen from the illustrated reference system and section lines, Figure 4A shows a plan view in the x direction, while Figures 4B and 4C show cross-sectional views in the z and y directions, respectively. The same reference numbers refer to the same parts as in Figure 2.

[0073] In this embodiment, the beam shaping element and the inlet 18 of the support 14 are elliptical in cross section, i.e. the beam shaping element 12 has a smaller dimension in the y direction than in the z direction. In this figure, the inlet 18 of the support 14 surrounds the beam shaping element in the shape of a ring. The wall thickness of the inlet 18 is small relative to the width and length of the beam shaping element 12. Depending on the application or manufacturing process, the wall thickness may be homogeneous or non-homogeneous, especially for structures acting as light traps (see FIG. 8C). The design of the optical device shown in FIGS. 4A, 4B and 4C is preferred because of the reduced wall thickness resulting in a thin profile, which is therefore advantageous for injection molding processes.

[0074] FIG. 5 shows a cross-sectional view of a further variant of the embodiment according to FIG. 2 in side view.

[0075] In contrast to the previous embodiment, in this embodiment according to Fig. 5 the plug 18 of the support 14 is funnel-shaped. The opening width at the top surface 22 of the beam-shaping element 12 is therefore larger than the opening width of the plug 18 at the base surface 20 side. In prior art devices, a funnel-shaped design is generally undesirable, since with this shape the light may be reflected and scattered at the inner surface of the plug 18 towards the photoelectric element. However, due to the configuration of the beam-shaping element 12 and the support 14 (i.e. the choice of their materials and joints), in this case scattering or reflection at the contact surface 26 is little or absent, so that the above-mentioned advantages are particularly pronounced.

[0076] In many cases, a funnel-shaped design may be desirable because it facilitates removal of the injection molded part from the injection mold. Additionally, a funnel-shaped design has the advantage that it reduces the volume of the beam shaping element 12 and therefore preferably reduces the occurrence of air bubbles. Additionally, the reduced volume allows for less material to be used for the beam shaping element 12.

[0077] 6A and 6B show a cross-sectional view and a side view of two further variants of the embodiment according to FIG.

[0078] As already described with respect to Figures 2 and 3, the insert 18 of the support 14 may have an opening 30 in the base surface 20, which serves for example as an optical diaphragm. The opening 30 may be formed in different ways. On the other hand, it may be left open, as shown in Figure 6A, while in Figure 6B it is filled with the material of the beam shaping element 12 (first material). Both variants may be suitable depending on the application or manufacturing process and are equally feasible in an injection moulding process. However, the latter variant is particularly suitable with respect to the injection moulding process in order to achieve a good bond between the support 14 and the beam shaping element 12.

[0079] Fig. 7A shows an example application of the optical device of the present disclosure in a perspective view, Fig. 7B shows the example application according to Fig. 7A in a plan view, Fig. 7C shows a side view, and Fig. 7D shows a cross-sectional view along line CC' in Fig. 7C.

[0080] An application example relates to an optical grating 40, the base 42 of which is shown in Fig. 7A-7D. The base 42 is a one-piece part, formed in two parts by injection molding. The first part is the support 14 and the second part is the beam-shaping element 12. More precisely, the second part here comprises ten beam-shaping elements 12a-12j, each of which is attached to a corresponding inlet 18a-18j of the support 14. As mentioned above, the support material (second material) and the material of the beam-shaping element 12 (first material) are selected in such a way that reflections and refractions in the inlet 18 are avoided or reduced.

[0081] In addition to the plugs 18a-18j, the support 14 may also serve as a base frame for the light grid 40. The beam-forming elements 12a-12j may also have further structures, such as connecting webs 44 between the beam-forming elements and, if necessary, further light guides 46 for other tasks. Thus, other components present in the light grid, such as status indicators in the form of LEDs, can be advantageously realized together with the support 14 and the beam-forming elements 12 by means of one-piece components. In this way, the light grid 40 can be realized in a cost-effective manner. In particular, the assembly operations can be significantly reduced.

[0082] The cross section through the beam-shaping element 12 shown in FIG. 7D along the line C-C' in FIG. 7C corresponds to the schematic diagram of the embodiment of the previous figures and in each case shows the combination of the features described therein. The inlet 18 for the beam-shaping element 12 is therefore pot-shaped with the beam-shaping element 12 extending more in the y direction than in the z direction and therefore as narrow as possible in the z direction. Furthermore, the side wall of the inlet 18, on which the contact surface 26 is formed between the support 14 and the beam-shaping element 12, is obliquely inclined at an angle into the x direction and then forms the optical axis 28. The inlet is therefore slightly funnel-shaped and has the advantages mentioned above for FIG. 5, in particular with regard to the removal of the inlet from the injection mould (not shown here). Finally, on the side of the base surface 20 of the beam-shaping element, an opening 30 is provided in the inlet 18 as an optical opening. However, on the opposite side (the side of the top surface 22), the beam-forming element is devoid of supports 14, as can be seen especially from the perspective view of FIG. 7A.

[0083] As already mentioned, the substrate 42 for the light grating 40 can be manufactured by two-component injection molding. The method starts with the selection of a first and a second material for the support 14 and the beam shaping elements 12, or with the preparation of a common base material for the first and the second materials (for example by coloring the base material). The first material for the beam shaping elements 12 is made transparent to a given electromagnetic radiation (in particular the light relevant for this application). The second material for the support is made absorbent to this electromagnetic radiation or is made absorbent to this radiation. Both materials have the same refractive index for the electromagnetic radiation or have similar refractive indices within a tolerance range. TIFF2025026799000003.tif1132

[0084] This is preferably achieved by using a common base material.

[0085] The first and second materials are then loaded into an injection molding machine designed for multi-component injection molding and the injection molding process begins.

[0086] Depending on the process, the first and second materials are injected simultaneously or sequentially into an injection mold, which is a negative mold of the substrate 42 shown in Figures 7A-7D. Depending on the process, the support 14 may be molded first and then the beam shaping elements 12 may be injection molded onto it. However, it is also conceivable to first form the plurality of beam shaping elements 12a-12j, including the connecting webs 44 and the optical light guides 46, and then overmold this structure with the support material.

[0087] In principle, the choice of injection molding process depends only on the desired shape of the substrate, as long as the common contact surface 26 in the socket 18 is seamless between the beam shaping element 12 and the support 14, so that the above-mentioned optical properties (in particular the absorption of scattered light by the support 14) can occur.

[0088] After injection molding, the substrate 42 includes at least the support 14 and the beam forming element 12. For a functional light grating, essentially all that needs to be added is the photoelectric element and electronics with external connections and an enclosing housing. Compared to conventional light gratings that use separate parts for the support and beam forming element, the assembly work and associated manufacturing costs can be significantly reduced.

[0089] 8A-8C show variations of an optical device 10 of the kind described above, having additional light traps 50a, 50b and 50c, respectively, within the support 14. In the embodiment shown in FIG.

[0090] The scope of protection of the invention is determined by the following claims and is not limited by the features described in the description or illustrated in the drawings.

Claims

1. a beam forming element (12) formed of a first material having opposed base and top surfaces (20 and 22) and an enclosing side surface (24) connecting said base and top surfaces (20 and 22); a support (14) made of a second material, formed with a plug (18) for the beam shaping element (12) and having at least one common contact surface (26) with the side surface (24) of the beam shaping element (12); the first material and the second material are in direct contact with each other at the contact surface (26) between the beam shaping element (12) and the support (14); the first material being transparent to a predetermined electromagnetic radiation and the second material being absorptive to the predetermined electromagnetic radiation; The first material and the second material each have a predetermined refractive index (n 1 , n 2 ) The predetermined refractive index (n 2 ) is the predetermined refractive index (n 1 ) at a predetermined ratio.

2. The predetermined ratio n 1 / n 2 The optical device according to claim 1, wherein the ratio is between 0.9 and 1.

1.

3. The predetermined ratio n 1 / n 2 The optical device according to claim 1 , wherein

4. 2. The optical device of claim 1, wherein the particular transition characteristic renders the interface (26) low reflective and low refractive for the given electromagnetic radiation coupled by the base surface (20) and the top surface (22).

5. The optical device of claim 4, wherein the particular transition characteristic makes the interface (26) non-reflective and non-refractive.

6. 2. The optical device of claim 1, wherein the particular transition characteristic causes the predetermined electromagnetic radiation coupled by the base surface (20) and the top surface (22) at a predetermined range of incidence angles to be absorbed from the interface surface (26) by the second material.

7. 2. The optical device of claim 1, wherein the first material is a first transparent plastic and the second material is a second colored plastic that absorbs the predetermined electromagnetic radiation.

8. 8. The optical device of claim 7, wherein the second material is a black plastic.

9. 8. The optical device of claim 7, wherein the first clear plastic and the second colored plastic each comprise polycarbonate, polymethylmethacrylate (PMMA), cycloolefin copolymer, optical polyester, or polysulfone.

10. 2. The optical device according to claim 1, wherein the beam shaping element (12) and the support (14) are integrally joined parts.

11. 2. The optical device of claim 1, wherein the outlet (18) is funnel-shaped and tapers in a direction from the top surface (22) to the base surface (20).

12. 2. The optical device according to claim 1, wherein the inlet (18) surrounds at least a portion of the base surface (20) with at least one opening (30) for the predetermined electromagnetic radiation, the opening (30) being designed as a diaphragm for a photoelectric element (16) in the beam path.

13. 13. The optical device of claim 12, wherein the aperture (30) is filled with the first material of the beam shaping element (12).

14. The optical device of claim 1 , wherein the receptacle (18) forms a tube protruding from the top surface (22).

15. 2. The optical device of claim 1, wherein a protruding structure is formed in the receptacle (18) and acts as a light trap.

16. 2. The optical device according to claim 1, comprising a plurality of beam forming elements (12a-12j), each having its own inlet (18a-18j) formed in the support (14).

17. 10. The optical device according to claim 1, wherein the optical device is a safety light barrier or a safety laser scanner.

18. A manufacturing method for an optical device (10) having a beam shaping element (12) and a support (14), comprising: a first predetermined refractive index (n 1 providing a first material for the beam shaping elements (12), the first material having a thickness of 100 nm; absorptive for the predetermined electromagnetic radiation and having a second predetermined refractive index (n 2 providing a second material for the support (14), the second material having a thickness of 1000 .mu.m; forming the beam shaping elements (12) from the first material and the supports (14) from the second material; and bonding the beam forming element (12) and the support (14) to form an integrally bonded part formed of the first material and the second material; The beam shaping element (12) has opposing base and top surfaces (20, 22) and an enclosing side surface (24) connecting the base and top surfaces (20, 22), the support (14) is formed with a plug (18) for the beam shaping element (12) and has at least one common contact surface (26) with the surrounding side surface (24) of the beam shaping element (12); The second predetermined refractive index (n 2 ) is the first predetermined refractive index (n 1 ) is set to a predetermined ratio.

19. The method of claim 18 , wherein the manufacturing and assembling comprises injection molding.

20. 19. The method according to claim 18, wherein the injection molding is multi-component injection molding.

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