CN117631432A - Fresnel screen and laser display device - Google Patents
Fresnel screen and laser display device Download PDFInfo
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- CN117631432A CN117631432A CN202311840861.6A CN202311840861A CN117631432A CN 117631432 A CN117631432 A CN 117631432A CN 202311840861 A CN202311840861 A CN 202311840861A CN 117631432 A CN117631432 A CN 117631432A
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Abstract
The embodiment of the invention discloses a Fresnel screen and laser display equipment, and relates to the technical field of optics. The Fresnel screen is used in laser display and comprises a substrate and a Fresnel structure layer positioned on one side of the substrate; the Fresnel structure layer comprises a curved grating, image light beams displayed by laser are converged into eyes of a user after entering the Fresnel structure layer, and external environment light beams are turned to an area outside the eyes of the user after entering the Fresnel structure layer. The embodiment of the invention can weaken the light intensity of stray light entering eyes of a user, improve the image quality of laser display, and simultaneously improve the reflectivity of an incident light beam and the brightness of laser display by utilizing the principle of grating reflection.
Description
Technical Field
The invention relates to the technical field of optics, in particular to a Fresnel screen and laser display equipment.
Background
The laser display generally adopts an ultra-short focal front projection mode to project a picture onto a Fresnel screen, so that light emitted by a projector irradiates the screen and is reflected to an observer so as to improve the brightness of the picture. Meanwhile, the surface of the Fresnel screen is also provided with a plurality of fine saw-tooth structures, and stray light in the environment irradiates the fine structures and is reflected to other directions except for an observer, so that the influence of the stray light in projection display is weakened, and the contrast ratio of a picture is improved. However, the conventional fresnel screen is generally manufactured by an embossing method, and requires a relatively large device, so that the manufacturing method is relatively complex, and meanwhile, the fine structure of the surface reflects all the light rays with the wavelength, and stray light in the same direction as the projection light rays is reflected into eyes of an observer, so that the contrast ratio is reduced, and the image quality is affected.
Disclosure of Invention
The embodiment of the invention provides a Fresnel screen and laser display equipment, wherein the Fresnel screen has selectivity to wavelength, an external environment beam cannot be incident into eyes of a user, the light intensity of stray light entering the eyes of the user is weakened, the image quality of laser display is improved, and meanwhile, the reflection rate of an incident beam is improved and the brightness of laser display is improved by utilizing the principle of grating reflection.
According to an aspect of the present invention, there is provided a fresnel screen for use in a laser display, the fresnel screen comprising:
a substrate and a Fresnel structure layer positioned on one side of the substrate;
the Fresnel structure layer comprises a curved grating, image light beams displayed by laser are converged into eyes of a user after entering the Fresnel structure layer, and external environment light beams are turned to an area outside the eyes of the user after entering the Fresnel structure layer.
Optionally, the fresnel structure layer comprises a holographic recording material;
performing interference exposure on the position of the holographic recording material by using two coherent light beams with the same wavelength and a preset included angle in the direction to form the curved grating;
the two coherent light beams comprise a reference light beam and an object light beam, and the object light beam is spherical wave.
Optionally, the object beam is a divergent spherical wave or a convergent spherical wave.
Optionally, the reference beam is at least one of a plane wave, a divergent spherical wave, and a convergent spherical wave.
Optionally, the reference beam is a plane wave, the object beam is a spherical wave, and the regions with the same refractive index in the curved grating are in a ring shape.
Optionally, the substrate is a transparent substrate, and the image light beam enters the eyes of the user in a mode of back projection from a side of the transparent substrate away from the fresnel structure layer, or the image light beam enters the eyes of the user in a mode of front projection from a side of the fresnel structure layer away from the transparent substrate.
Optionally, the substrate is a light absorbing material substrate, and the image beam is projected forward from one side of the fresnel structure layer away from the light absorbing material substrate, reflected by the fresnel structure layer, and enters the eyes of the user.
Optionally, the holographic recording material comprises at least one of a photopolymer, a silver halide emulsion, a dichromated gelatin, a photodegradable polymer material, a photoconductive thermoplastic material, a photoisomerization material, a photorefractive material, and a super surface material.
Optionally, the holographic recording material comprises a photopolymer, wherein the photopolymer consists of a photosensitive dye, an initiator, a chain transfer agent, a monomer, a film-forming resin and a plasticizer, wherein the refractive index of the monomer is different from that of the film-forming resin, and the monomer is polymerized by utilizing illumination to generate diffusion due to concentration difference to form a phase-type holographic grating with refractive index modulation with the film-forming resin so as to realize holographic recording.
According to another aspect of the present invention, there is provided a laser display apparatus comprising a laser projection device and a fresnel screen as described above.
The Fresnel screen and the laser display device provided by the embodiment of the invention. The Fresnel structure layer comprises a curved surface grating, the curved surface grating has selectivity to wavelength, the curved surface grating can only act on image beams displayed by laser through setting the wavelength of the beams acted on by the curved surface grating, so that the beams are converged into eyes of a user, and when the external environment beams are incident to the curved surface grating, the external environment beams turn to the area outside the eyes of the user and cannot enter the eyes of the user, stray light intensity entering the eyes of the user is weakened, the image quality of laser display is improved, the reflectivity of the Fresnel screen is improved, and the brightness of the laser display is improved.
It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic side view of a first Fresnel screen according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a first embodiment of a holographic recording material exposure process according to the present invention;
FIG. 3 is a schematic diagram of a second embodiment of a hologram recording material exposure process according to the present invention;
FIG. 4 is a schematic diagram of a third embodiment of an exposure process for holographic recording materials;
FIG. 5 is a schematic diagram of a fourth embodiment of the exposure process for holographic recording material;
FIG. 6 is a schematic cross-sectional view of a curved grating according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a fifth embodiment of the exposure process for holographic recording materials;
fig. 8 is a schematic side view of a second fresnel screen according to an embodiment of the present invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Fig. 1 is a schematic side view of a first fresnel screen according to an embodiment of the present invention, and referring to fig. 1, the fresnel screen includes a substrate 10 and a fresnel structure layer 20 located on one side of the substrate 10. The fresnel structure layer 20 includes a curved grating, and an image beam displayed by laser is incident on the fresnel structure layer 20 and then converged into the eyes of the user, and an external environment beam is incident on the fresnel structure layer 20 and then turned to an area outside the eyes of the user.
The curved grating has selectivity to wavelength, and by setting the wavelength of the light beam which can act on the curved grating, the curved grating can only act on the image light beam displayed by the laser, so that the light beam is converged into the eyes of the user, and when the external environment light beam is incident to the curved grating, the external environment light beam is turned to the area outside the eyes of the user and cannot enter the eyes of the user, the light intensity of stray light entering the eyes of the user is weakened, the image quality of laser display is improved, the reflectivity of the Fresnel screen is improved, and the brightness of laser display is improved.
The Fresnel structure layer comprises the curved surface grating, the curved surface grating has selectivity to wavelength, only the image light beam displayed by the laser is acted, so that the light beam is converged into the eyes of the user, when the external environment light beam is incident to the curved surface grating, the light beam is turned to the area outside the eyes of the user and cannot enter the eyes of the user, the light intensity of stray light entering the eyes of the user is weakened, the image quality of the laser display is improved, the reflectivity of the Fresnel structure layer is improved, and the brightness of the laser display is improved.
Illustratively, referring to fig. 1, the fresnel structure layer 20 includes a holographic recording material 201, and two coherent light beams having the same wavelength and a predetermined angle are used to perform interference exposure at the position of the holographic recording material 201 to form a curved grating, where the two coherent light beams include a reference light beam and an object light beam, and the object light beam is a spherical wave. The hologram recording material 201 is a material for recording and reconstructing information in the hologram technology. The holographic technique is to record information in the form of holograms in a holographic material using the principle of interference of light, and recover all stored information in the form of diffraction imaging under the condition that the readout light satisfies diffraction matching. The characteristic of the holographic recording material is that the internal structure or composition changes correspondingly under the illumination with the difference of light intensity, thereby causing the change of refractive index and forming the modulation of refractive index. The holographic recording material includes at least one of a photopolymer, a silver halide emulsion, a dichromated gelatin, a photodegradable high molecular material, a photoconductive thermoplastic material, a photoisomerization material, a photorefractive material, and a super surface material.
Optionally, the holographic recording material 201 includes a photopolymer, which is composed of a photosensitive dye, an initiator, a chain transfer agent, a monomer, a film-forming resin, and a plasticizer, wherein the refractive index of the monomer is different from that of the film-forming resin, and the holographic recording is realized by using light to make the monomer diffuse due to the concentration difference and form a phase-type holographic grating with modulated refractive index with the film-forming resin after polymerization.
Wherein the principle of the photopolymer is as follows: the photosensitizing dye determines the photosensitizing spectral range of the material that can transfer energy to the initiator upon absorption of photon energy. The initiator initiates polymerization of the monomer by cleavage or hydrogen abstraction reactions to form reactive species (radicals or anions). The chain transfer agent has the function of enabling the free radicals with large volume and low activity (including chain growth free radicals) to generate free radical transfer reaction, generating free radicals with small volume and high activity, and rapidly initiating the polymerization of the monomers. The monomer is the main component of the photopolymer, has unsaturated group or epoxy group, and is polymerized under the action of free radical or anion and cation. The film-forming resin mainly plays a role in forming and supporting and provides a certain mechanical stability for the material. The plasticizer has the function of weakening secondary valence bonds among polymer molecules and increasing the plasticity and flexibility of the polymer so as to facilitate the migration of the monomer. When exposed, the photosensitizing dye in the bright area of the interference fringes absorbs photons and activates the photoinitiator to generate active species through electron transfer or energy transfer, thereby initiating the polymerization reaction of the monomers. The monomer concentration of the dark area is hardly consumed along with the gradual reduction of the polymerization concentration of the monomer of the bright area, the monomer concentration difference of the light and dark area promotes the monomer of the dark area to start to migrate to the bright area, meanwhile, the substrate film-forming resin of the bright area is extruded to the dark area, the refractive index of the final bright area is close to that of the polymer, and the refractive index of the dark area is close to that of the film-forming resin, so that the phase type volume holographic grating with refractive index modulation is formed.
Fig. 2 is a schematic structural diagram of an exposure process of a first holographic recording material according to an embodiment of the present invention, referring to fig. 2, after a beam emitted from a laser light source 30 is expanded at a beam expander 40, parallel light with the same size as that of the holographic recording material 201 is obtained, and the parallel light is split into two beams after passing through a polarization splitting prism 50, wherein one beam (i.e., a reference beam) directly irradiates the holographic recording material 201, and the other beam (i.e., an object beam) irradiates the holographic recording material 201 after being reflected by a reflecting mirror 60 and a spherical reflecting mirror 70 after being modulated by light intensity. The two beams of light interfere at the position of the holographic recording material 201 to form specific intensity distribution, and the holographic recording material 201 is exposed, so that the refractive index of the holographic recording material 201 is changed under the change of the light intensity, and a curved grating with specific refractive index distribution is formed. The hologram recording material 201 is prepared as a thin film having a thickness of several micrometers to several tens micrometers, and is coated on the substrate 10 to form the fresnel structure layer 20. The Fresnel structure layer 20 is prepared by using an exposure mode, so that the steps are simpler, and the method is suitable for mass production.
Fig. 3 is a schematic structural diagram of an exposure process of a second holographic recording material according to an embodiment of the present invention, and referring to fig. 2 and 3, an object beam is a divergent spherical wave or a convergent spherical wave. When the object beam is a convergent spherical wave, the light intensity entering the eyes of the user is concentrated, so that the brightness of laser display is improved; when the object beam is a divergent spherical wave, the range of the beam entering the eyes of the user is enlarged, and the visual angle of laser display can be improved.
Fig. 4 is a schematic structural diagram of an exposure process of a third holographic recording material according to an embodiment of the present invention, fig. 5 is a schematic structural diagram of an exposure process of a fourth holographic recording material according to an embodiment of the present invention, and referring to fig. 2, fig. 4 and fig. 5, a reference beam is at least one of a plane wave, a divergent spherical wave and a convergent spherical wave. By providing the optical system 80 in the structure, the reference beam can be a divergent spherical wave (fig. 4) and a convergent spherical wave (fig. 5), and when the reference beam is provided as a divergent spherical wave or a convergent spherical wave, the brightness of the laser display can be improved.
Furthermore, the optical system 80 may be further configured to make the reference beam be a plane wave, a divergent spherical wave, and a convergent spherical wave, where each beam has a different direction and a convergent mode, so as to form a projection image with multiple viewpoints or a combination of large viewing angles, and improve the quality of laser display.
Exemplary, fig. 6 is a schematic cross-sectional structure of a curved grating according to an embodiment of the present invention, and referring to fig. 1 and 6, a reference beam is a plane wave, an object beam is a spherical wave, and regions with the same refractive index in the curved grating are in a ring shape.
Fig. 7 is a schematic structural diagram of an exposure process of a fifth holographic recording material according to an embodiment of the present invention, referring to fig. 7, after a beam emitted from a laser light source 30 is expanded at a beam expander 40, parallel light with the same size as that of the holographic recording material 201 is obtained, the parallel light is split into two beams after passing through a polarization splitting prism 50, one beam (i.e., a reference beam) is directly irradiated onto the holographic recording material 201, and the other beam (i.e., an object beam) is reflected by a spherical mirror 70 after being modulated by light intensity and irradiated onto the holographic recording material 201. The two beams of light interfere at the position of the holographic recording material 201 to form specific intensity distribution, and the holographic recording material 201 is exposed, so that the refractive index of the holographic recording material 201 is changed under the change of the light intensity, and a curved grating with specific refractive index distribution is formed.
Illustratively, referring to fig. 1, 2 and 7, the substrate 10 is a transparent substrate 101, and the image beam enters the user's eye by back projection from the side of the transparent substrate 101 remote from the fresnel structure layer 20, or by forward projection from the side of the fresnel structure layer 20 remote from the transparent substrate 101. The transparent substrate 101 does not affect the incident light beam to be projected to the fresnel structure layer 20 for phase modulation, and the effect of laser display is not affected when the incident light beam is projected from the side of the transparent substrate 101 away from the fresnel structure layer 20 and projected from the side of the fresnel structure layer 20 away from the transparent substrate 101.
Fig. 8 is a schematic side view of a second fresnel screen according to an embodiment of the present invention, referring to fig. 8, the substrate 10 is a light absorbing material substrate 102, and an image beam is projected forward from a side of the fresnel structure layer 20 away from the light absorbing material substrate 102, reflected by the fresnel structure layer 20, and enters the eyes of a user. The light absorbing material substrate absorbs external environment light beams, reduces the light intensity of stray light entering eyes of a user, and improves the image quality of laser display.
Based on the same technical conception, the embodiment of the invention also provides laser display equipment. The laser display device comprises the Fresnel screen provided by any embodiment of the invention. Therefore, the laser display device provided by the embodiment of the present invention has the corresponding beneficial effects of the fresnel screen provided by the embodiment of the present invention, and will not be described herein.
The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.
Claims (10)
1. A fresnel screen for use in a laser display, the fresnel screen comprising:
a substrate and a Fresnel structure layer positioned on one side of the substrate;
the Fresnel structure layer comprises a curved grating, image light beams displayed by laser are converged into eyes of a user after entering the Fresnel structure layer, and external environment light beams are turned to an area outside the eyes of the user after entering the Fresnel structure layer.
2. The fresnel screen of claim 1, wherein the fresnel structure layer comprises holographic recording material;
performing interference exposure on the position of the holographic recording material by using two coherent light beams with the same wavelength and a preset included angle in the direction to form the curved grating;
the two coherent light beams comprise a reference light beam and an object light beam, and the object light beam is spherical wave.
3. The fresnel screen according to claim 2, wherein the object beam is a diverging spherical wave or a converging spherical wave.
4. The fresnel screen of claim 2, wherein the reference beam is at least one of a plane wave, a divergent spherical wave, and a convergent spherical wave.
5. The fresnel screen of claim 4, wherein the reference beam is a plane wave, the object beam is a spherical wave, and the regions of equal refractive index in the curved grating are in the shape of a ring.
6. The fresnel screen of claim 1, wherein the substrate is a transparent substrate and the image light beam enters the user's eye by back projection from a side of the transparent substrate remote from the fresnel structure layer or by forward projection from a side of the fresnel structure layer remote from the transparent substrate.
7. The fresnel screen of claim 1, wherein the substrate is a light absorbing material substrate and the image beam is projected forward from a side of the fresnel structure layer remote from the light absorbing material substrate, reflected by the fresnel structure layer, and then enters the user's eye.
8. The fresnel screen of claim 2, wherein the holographic recording material comprises at least one of a photopolymer, a silver halide emulsion, a dichromated gelatin, a photodegradable polymer material, a photoconductive thermoplastic material, a photoisomerization material, a photorefractive material, and a super surface material.
9. The fresnel screen of claim 8, wherein the holographic recording material comprises a photopolymer composed of a photosensitive dye, an initiator, a chain transfer agent, a monomer, a film-forming resin, and a plasticizer, wherein the monomer and the film-forming resin have refractive indices different from each other, and wherein holographic recording is achieved by light irradiation to cause diffusion of the monomer due to the concentration difference and the film-forming resin to form a refractive index modulated phase type holographic grating.
10. A laser display device comprising a laser projection means and a fresnel screen according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311840861.6A CN117631432A (en) | 2023-12-27 | 2023-12-27 | Fresnel screen and laser display device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311840861.6A CN117631432A (en) | 2023-12-27 | 2023-12-27 | Fresnel screen and laser display device |
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| Publication Number | Publication Date |
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| CN117631432A true CN117631432A (en) | 2024-03-01 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202311840861.6A Pending CN117631432A (en) | 2023-12-27 | 2023-12-27 | Fresnel screen and laser display device |
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| CN (1) | CN117631432A (en) |
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- 2023-12-27 CN CN202311840861.6A patent/CN117631432A/en active Pending
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