Method for producing hologram of retroreflector and method for producing retroreflector for vehicle
By applying photosensitive recording materials and laser radiation on the retroreflector to generate a hologram, the problems of limited design of vehicle retroreflectors and insufficient angle reflection are solved, and a retroreflector with flexibility in large-angle reflection and visual appearance design is realized to meet the law Require.
Patent Information
- Application Number
- CN202410764166.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-06-16
- Filing Date
- 2024-06-14
- Publication Date
- 2024-12-17
AI Technical Summary
The prior art is difficult to manufacture retroreflectors for vehicles because the visual appearance design of the prism of conventional retroreflectors is limited and cannot reflect incident light within a large angle range, which violates the law.
By applying a photosensitive recording material on the retroreflector and generating a hologram using laser radiation, the photosensitive recording material forms a hologram on the prism surface, reflecting light along the incident direction, and without a visible structure in the unilluminated state, Suitable for transparent or opaque carriers.
A retroreflector that reflects light in a large angle range is realized, improving the flexibility of visual appearance design, and allowing holograms to be applied on the transparent surface of the vehicle to meet legal requirements.
Smart Images
Figure CN119148272A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for producing a hologram for a retroreflector, a hologram produced by the method, a method for producing a retroreflector for a vehicle and a retroreflector for a vehicle produced by the method. Background Art
[0002] Retroreflectors for vehicles are known. They increase the visibility of the vehicle and contribute to road traffic safety. Current technical implementations allow for relatively few design possibilities here. In particular, the visual appearance of the facets of conventional retroreflectors can only be designed to a limited extent.
[0003] DE 30 12 500 A1 discloses a method for producing a retroreflector, in which the reflective surfaces of the individual facets arranged at an angle to one another are partially formed by spatially superimposed diffraction gratings, each of which is constructed as a volume hologram. In particular, in the method described in DE 30 12 500 A1, two holographic gratings are recorded in the volume hologram, which are at an angle of 90° to one another. An incident light beam is first reflected parallel to the plane of the first grating. Subsequently, the light beam emitted from the first grating is reflected at the second grating. Since the gratings are oriented at an angle of 90° to one another and at 45° or -45° to the substrate normal, a 180° retroreflection can be achieved. In this method, the recording design is complicated, since for this purpose the two light beams of each grating must be superimposed. The reference beam impinges on the hologram in the direction of the substrate normal. The object beam must enter the medium at an angle of 90° to the substrate normal. This is not possible with thin recording media, since the Fresnel reflection at 90° is almost 100%. Therefore, only very thick recording media that can be coupled in from the side are suitable for this method. In addition, the angular selectivity of the volume holograms used is also problematic. Only beams that strike the retroreflector almost perpendicularly are reflected back by it. Non-parabolic beams are not reflected but are transmitted through the hologram.
[0004] Therefore, it is not possible to produce retroreflectors for vehicles using the method described in DE 30 12 500 A1, since retroreflectors for motor vehicles and bicycles must reflect light incident on them from a wide range of angles according to legal regulations. Summary of the invention
[0005] The problem underlying the invention is to provide a method of the type mentioned at the outset by which a hologram can be produced which is suitable in a retroreflector for vehicles for reflecting light substantially in the direction from which the light was incident on the retroreflector. Furthermore, a hologram produced by the method, a method for producing a retroreflector for vehicles of the type mentioned at the outset and a retroreflector for vehicles produced by the method are to be provided.
[0006] According to the invention, this is achieved by a method of the type mentioned at the outset with the features of claim 1, a hologram with the features of claim 11, a method of the type mentioned at the outset with the features of claim 12, and a retroreflector of the type mentioned at the outset with the features of claim 15. The dependent claims relate to preferred embodiments of the invention.
[0007] According to claim 1, the method for producing a hologram comprises the following steps:
[0008] A retroreflector is provided, the retroreflector having a plurality of facets, wherein the plurality of facets are respectively configured to reflect light incident thereon back.
[0009] applying a light-sensitive recording material to the retroreflector,
[0010] Produces laser radiation,
[0011] A plurality of facets of the retroreflector are sequentially loaded with laser radiation that has passed through a recording material, so that the laser radiation is respectively reflected back by the facets and passes through the recording material again, wherein the laser radiation that has passed through the recording material in the direction of the facets is respectively used as a reference wave and the laser radiation that has been reflected back by the facets is respectively used as an object wave, so that a segment of a hologram is generated in a portion of the photosensitive recording material that is arranged in front of the corresponding facet by overlapping the laser radiation that has passed through the facets with the reflected laser radiation.
[0012] When light strikes a hologram produced by this method, it corresponds to a reference wave from which the object wave is reconstructed. The object wave will move away from the hologram essentially in the opposite direction to the reference wave, so that the hologram acts like a retroreflector, which reflects light back in the direction from which it was incident. The recording material into which the hologram is read is usually unstructured, so that the retroreflector realized by the hologram has no visible structure, such as facets, in the unilluminated state. This improves the visual appearance of the retroreflector realized with the hologram.
[0013] It can be provided that the facets of the retroreflector are respectively arranged to reflect light incident thereon from a first direction back in a second direction opposite to the first direction. Thus, the part of the manufactured hologram arranged in front of the corresponding facet during manufacture can also reflect the light incident thereon back like the corresponding facet.
[0014] It is possible for the retroreflector to be transparent to visible light. This ensures that the recording material with the hologram read in by the method is also transparent in the unilluminated state. This offers significant design advantages, since the hologram can be applied to transparent surfaces of the vehicle and since correspondingly other optical functions can be arranged behind the hologram used as retroreflector.
[0015] It can be provided that the retroreflector has a smooth, unstructured surface, wherein the light-sensitive recording material is applied to the smooth surface. The recording material can be applied better to the smooth surface. For example, the light-sensitive recording material can be laminated onto the retroreflector, in particular onto the smooth surface of the retroreflector.
[0016] It is possible that the light-sensitive recording material is designed as a film, in particular as a photopolymer film. Such a film can be easily applied to the smooth surface of the retroreflector used in the production method. In addition, such a film can also be easily applied to different carriers or vehicle parts for use as a retroreflector.
[0017] It can be provided that the laser radiation is focused in the direction of the respective facet when passing through the recording material, in particular wherein substantially the entire facet is respectively impinged by the laser radiation. In this way it is ensured that the retroreflector realized by the hologram can reflect light back over a large angle range.
[0018] It is possible for the laser radiation to be colored laser radiation which, for example, has a wavelength in the red spectral range, or for the laser radiation to consist of a plurality of laser radiations of different wavelengths, so that a white impression is generated.
[0019] By using colored, in particular red, laser radiation to produce a hologram, only the red object wave is reconstructed when white light is incident on a corresponding retroreflector provided with the hologram. Thus, a hologram read in with red laser radiation can realize a red retroreflector, such as is used, for example, in taillights.
[0020] By producing a hologram using white laser radiation, a white object wave is reconstructed when the white light is incident on a corresponding retroreflector provided with the hologram. Thus, a hologram read in with white laser radiation can realize a white retroreflector. The white light incident on the retroreflector provided with the hologram can be, in particular, the light of the headlights of other vehicles.
[0021] It can be provided that after the exposure of the hologram the light-sensitive recording material is removed from the retroreflector.The hologram removed from the retroreflector in this way can be used in particular as a master hologram for producing a replica hologram.
[0022] According to claim 11 , a hologram is produced by the method according to the invention, wherein the hologram is provided in particular for use with a light source that generates white light.
[0023] According to claim 12, the method for producing a retroreflector comprises the following method steps:
[0024] producing a hologram, in particular a replica hologram, by means of the method according to the invention for producing a hologram,
[0025] The hologram is applied to a carrier.
[0026] Application to the carrier can be effected, for example, by laminating the film containing the hologram onto the carrier.
[0027] It can be provided that the carrier is transparent to at least a portion of the visible light spectrum, wherein the carrier can in particular be a component of the lighting device that is transparent to at least a portion of the visible light spectrum, for example a cover plate of the lighting device. In this way, the hologram is not visible to an observer in the unilluminated state. Only when exposed to light does the hologram become visible by reflected light.
[0028] Alternatively, it can be provided that the carrier is opaque to visible light, wherein the carrier can be a painted component in particular. Thus, the hologram in the film can also be applied to any part of the vehicle body. The reflection back of painted parts, in particular dark parts, is also known as the blackboard effect.
[0029] According to claim 15 , a retroreflector is produced by the method according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The present invention is described in detail below with reference to the accompanying drawings.
[0031] Figure 1 Schematically illustrates a method for producing a hologram according to the present invention;
[0032] Figure 2 Shown for use according to Figure 1 A cross-sectional view of a retro reflector of the method.
[0033] In the figures, identical and functionally identical parts are provided with the same reference symbols. DETAILED DESCRIPTION
[0034] Figure 2A retroreflector 1 is schematically shown, which can be used for a method for producing a hologram. The retroreflector 1 has a plurality of facets 2, which are each formed, for example, by three mutually perpendicular reflection surfaces 3. The reflection surfaces 3 of the facets 2 can be arranged relative to one another in a known manner, for example, like the inner faces of a hollow cube touching at the corners.
[0035] The facets 2 of the retroreflector 1 have the following properties: light 4 incident thereon in a first direction is reflected by the face 3 so that it moves as reflected light 5 in a second direction substantially opposite to the first direction (see Figure 2 ).
[0036] The retroreflector 1 can be designed in different ways. In particular, the retroreflector 1 can be formed by a transparent substrate, which is Figure 2 The upper side of the substrate has a smooth surface (not shown) which is not structured. The incident light 4 can enter the substrate through this smooth surface. In this embodiment, the mutually perpendicular surfaces 3 of the individual facets 2 can be formed inside the substrate, wherein the reflection function can be achieved, for example, by total reflection or by a mirror coating on the underside of the substrate.
[0037] To carry out the method for producing a hologram, a photosensitive recording material 6 is applied to a retroreflector 1 which is preferably transparent to visible light. In particular, the recording material 6 can be applied to a smooth, unstructured upper side (not shown) of the retroreflector 1. The recording material 6 can be designed as a film, in particular as a photopolymer film. The recording material 6 or the film can be adhesively bonded or laminated to the retroreflector 1, in particular.
[0038] Figure 1 Laser radiation 7 is shown, which is Figure 1 The laser radiation 7 is incident on the facets 2 of the retroreflector 1 or on its reflecting surface 3 from above through the recording material 6. In the exemplary embodiment shown, the laser radiation 7 is converging. In this case, substantially the entire facet 2 is impinged upon by the laser radiation 7.
[0039] The laser radiation 7 can be colored laser radiation 7 which, for example, has a wavelength in the red spectral range. Alternatively, the laser radiation 7 can consist of a plurality of laser radiations of different wavelengths, so that a white impression is generated.
[0040] The laser radiation 7 is reflected back by the facet 2 so that it passes through the recording material 6 again as reflected laser radiation 8. In this case, the laser radiation 7 that passes through the recording material 6 in the direction of the facet 2 serves as a reference wave, while the laser radiation 8 that is reflected back by the facet 2 serves as an object wave. Due to the superposition of the laser radiation 7 that passes in the direction of the facet 2 and the reflected laser radiation 8, a section of the hologram is generated in the part 9 of the light-sensitive recording material 6 that is arranged in front of the facet 2.
[0041] The method provides that when the current position of the recording material 6 is arranged Figure 1 After a segment of the hologram has been generated or read into the portion 9 in front of the facet 2 impinged by the laser radiation 7, the laser radiation 7 is moved so that it impinges on another facet 2. In front of this facet 2, a segment of the hologram is also read into a segment of the recording material 6. In this way, all facets 2 of the retroreflector 1 are impinged upon with laser radiation 7 in sequence until a corresponding segment of the hologram has been read into each segment of the recording material 6 located in front of a facet 2.
[0042] After the hologram has been read into the recording material 6, the recording material is removed from the retroreflector 1, for example peeled off. When light is incident on a hologram produced by this method, the light acts as a reference wave for reconstructing the object wave. The object wave will move away from the hologram substantially in the opposite direction to the reference wave, so that the hologram acts like a retroreflector, which reflects light back in the direction from which it was incident.
[0043] The hologram read into the recording material 6 can be used, for example, in a known manner as a master hologram for producing replica holograms.
[0044] The hologram read into the recording material 6 or the replica hologram produced therefrom can be applied, in particular laminated, to a carrier in a further method step not shown. The carrier with the applied hologram can be used as a retroreflector.
[0045] The carrier can be transparent to at least part of the visible light spectrum, wherein the carrier can be in particular a component of the lighting device that is transparent to at least part of the visible light spectrum, such as a cover plate of the lighting device. Alternatively, the carrier can be opaque to visible light, wherein the carrier can be in particular a painted component.
[0046] Reference numerals list
[0047] 1 Retroreflector
[0048] 2 Facets of retroreflector
[0049] 3-sided reflective surface
[0050] 4 Light incident on the edge
[0051] 5 Light reflected by facets
[0052] 6 Recording Materials
[0053] 7 Laser radiation
[0054] 8Reflected laser radiation
[0055] 9 The portion of the recording material arranged in front of the facet
Claims
1. A method for producing a hologram for a retroreflector, comprising the following method steps: A retroreflector (1) is provided, which has a plurality of facets (2), each of which is configured to reflect light (4) incident thereon back. applying a light-sensitive recording material (6) to the retroreflector (1), generating laser radiation (7), A plurality of facets (2) of a retroreflector (1) are successively impinged upon by laser radiation (7) which has passed through a recording material (6), so that the laser radiation (7) is reflected back from each facet (2) and passes through the recording material (6) again, wherein: Laser radiation (7) moving through the recording material (6) in the direction of the facet (2) is used as a reference wave and laser radiation (8) reflected back by the facet (2) is used as an object wave, so that a section of a hologram is generated in a portion (9) of the photosensitive recording material (6) arranged in front of the corresponding facet (2) by overlapping the laser radiation (7) moving in the direction of the facet (2) and the reflected laser radiation (8).
2. The method according to claim 1, characterized in that The facets (2) of the retroreflector (1) are respectively arranged to reflect light (4) incident thereon from a first direction back in a second direction opposite to the first direction.
3. The method according to any one of claims 1 or 2, characterized in that The retroreflector (1) is transparent to visible light.
4. The method according to any one of claims 1 to 3, characterized in that The retroreflector (1) has an unstructured smooth surface, wherein a light-sensitive recording material (6) is applied to the smooth surface.
5. The method according to any one of claims 1 to 4, characterized in that The light-sensitive recording material (6) is laminated onto the retroreflector (1), in particular onto the smooth surface of the retroreflector (1).
6. The method according to any one of claims 1 to 5, characterized in that The light-sensitive recording material (6) is in the form of a film, in particular a photopolymer film.
7. The method according to any one of claims 1 to 6, characterized in that The laser radiation (7) is focused in the direction of the respective edge facet (2) while passing through the recording material (6), in particular, substantially the entire edge facet (2) being impinged upon by the laser radiation (7).
8. The method according to any one of claims 1 to 7, characterized in that The laser radiation (7) is colored laser radiation (7) whose wavelength is, for example, in the red spectral range, or the laser radiation (7) consists of a plurality of laser radiations of different wavelengths, thereby producing a white impression.
9. The method according to any one of claims 1 to 8, characterized in that After exposure of the hologram, the light-sensitive recording material (6) is removed from the retroreflector (1).
10. The method according to any one of claims 1 to 9, characterized in that The hologram produced by the method according to one of claims 1 to 8 is used as a master hologram for producing a replica hologram.
11. A hologram, in particular a replica hologram, produced by a method according to claim 1, wherein: Holograms are particularly intended for use with light sources that generate white light.
12. A method for producing a retroreflector for a vehicle, comprising the following method steps: Producing a hologram, in particular a replica hologram, by a method according to one of claims 1 to 10, The hologram is applied to a carrier.
13. The method according to claim 12, characterized in that The carrier is transparent to at least a portion of the visible light spectrum, wherein the carrier is in particular a component of the lighting device that is transparent to at least a portion of the visible light spectrum, for example a cover plate of the lighting device.
14. The method according to claim 12, characterized in that The carrier is opaque to visible light, wherein the carrier is in particular a painted component.
15. Retroreflector produced by the method according to one of claims 12 to 14.