CN112764159B

CN112764159B - Optical waveguide element, method of manufacturing the same, and holographic optical waveguide display device

Info

Publication number: CN112764159B
Application number: CN201911002010.8A
Authority: CN
Inventors: 雍海波; 陈淑丹; 魏一振; 张卓鹏
Original assignee: Hangzhou Guangli Technology Co ltd
Current assignee: Hangzhou Guangli Technology Co ltd
Priority date: 2019-10-21
Filing date: 2019-10-21
Publication date: 2023-06-16
Anticipated expiration: 2039-10-21
Also published as: CN112764159A

Abstract

The invention relates to an optical waveguide element, a preparation method thereof and holographic optical waveguide display equipment. The optical waveguide element comprises a laminate of at least two carriers and a photopolymer film, wherein the photopolymer film is located between the at least two carriers; the photopolymer film has at least one light in-coupling region and at least one light out-coupling region; the light in-coupling area is not connected with the light out-coupling area; and the positions of the light in-coupling area and the light out-coupling area are respectively provided with a grating structure. The optical waveguide element has higher refractive index modulation degree, diffraction efficiency, sensitivity and light transmittance, and has excellent optical waveguide imaging effect.

Description

Optical waveguide element, method of manufacturing the same, and holographic optical waveguide display device

Technical Field

The invention belongs to the technical field of optics, in particular to an optical element and a preparation field thereof, and particularly relates to an optical waveguide element and a preparation method thereof in the field of augmented reality, or a holographic optical waveguide display device using the optical waveguide element.

Background

Near-eye display and head-mounted display technologies have been widely used in the field of augmented reality in recent years. The existing optical imaging schemes mainly include: coaxial prisms, off-axis prisms, coaxial curved surfaces, optical waveguides, etc., wherein optical waveguides are the focus of current research. The optical waveguide is to couple the light imaged by the optical machine into the glass substrate, and transmit the light to the front of the eye for coupling out by the principle of total reflection, and the waveguide is only responsible for transmitting the image in the process and can be understood as 'parallel light in and parallel light out', which is a separate optical device independent of the imaging system. The optical waveguide technology can be used for enabling the augmented reality glasses to be equivalent to normal glasses in size, not blocking the sight and conforming to human engineering, so that wearing experience is improved.

Existing optical waveguides can be generally divided into two types, geometric optical waveguides (array waveguide, geometric Waveguide) and diffractive optical waveguides (Diffractive Waveguide). The geometrical optical waveguide is equivalent to a plurality of semi-transparent and semi-reflective prisms which are glued together, and semi-transparent and semi-reflective are generated once through one prism surface, so that the geometrical optical waveguide is finally imaged to an eyeball. But the geometric optical waveguide has poor mass productivity, high cost and poor appearance. The diffraction optical waveguide is characterized in that light irradiates the coupling grating to diffract, the angle of the light reaches the total reflection condition of the substrate after diffraction, the light propagates through total reflection in the waveguide (similar to an optical fiber), and when the light propagates to the coupling grating, the light is coupled out and imaged to an eyeball.

The diffraction optical waveguide is further divided into a surface relief grating optical waveguide and a volume hologram grating optical waveguide. The core of the surface relief grating waveguide is formed by etching gratings with sub-wavelengths, and the image is guided by high-efficiency diffraction. The micro-nano structure form of the surface relief grating waveguide is changeable, and the degree of freedom of grating combination is high; it is also a biaxial pupil expansion, enabling large viewing angles, exit pupil sizes and eye relief. In addition, the surface relief grating waveguide has high transparency and light and thin structure. However, the main method for preparing the surface relief grating waveguide is nano-imprinting, but the nano-imprinting has high cost, complex design, complex master plate preparation and complex production process.

The volume holographic grating optical waveguide is a method of utilizing interference exposure to record all information (including amplitude and phase) of the object light wave in the form of interference fringes. When the recording medium is thick (the thickness is much larger than the recorded interference fringe spacing), the two phase beams interact within the medium to form a three-dimensional grating-like volume hologram. The light and dark fringes produced by the interference modulate the phase of the recording material (or understood as the refractive index modulation degree Δn) during recording. The absorption coefficient and refractive index of the volume hologram are periodically changed, and when the readout light satisfies the bragg diffraction condition, the stored information is restored in the form of diffraction image. However, the volume holographic grating optical waveguide has high requirements on materials and system design and manufacturing process.

Reference 1 discloses an optical waveguide and a display device, the optical waveguide including an optical waveguide body including a light beam coupling-in region and a light beam coupling-out region, the light beam coupling-in region being provided with a coupling-in grating configured to couple a light beam into the optical waveguide body and propagate in the optical waveguide body in a total reflection manner; the light beam coupling-out region is provided with a coupling-out grating configured to couple the light beam propagating to the light beam coupling-out region out of the light waveguide body and such that the light beam is not secondarily diffracted at the coupling-in grating and has a continuous extended exit pupil; the coupling-out grating comprises a transmission coupling-out grating and a reflection coupling-out grating which are arranged on two sides of the optical waveguide body and are parallel to the light beam propagation direction. The optical waveguide has the advantages of complex structure, higher preparation cost and single propagation mode.

Reference 2 discloses a holographic waveguide lens comprising one, two, three or more holographic waveguide lens units, a method of manufacturing the same and a three-dimensional display device using the same; the holographic waveguide lens unit is provided with three functional areas, and nano diffraction gratings are arranged in the functional areas; an in-coupling functional region for input optical coupling, a relay functional region for X-direction image diffusion, and an out-coupling functional region for Y-direction image diffusion and output, respectively. The holographic waveguide lens has the advantages of complex structure, higher preparation cost, complex post-treatment and small angle selectivity of grating diffraction.

It can be seen that although some improvements have been made in the prior art to optical waveguide components, there is still room for further improvement in the overall performance of these materials.

Citation literature:

citation 1: CN 109901298A

Citation 2: CN 109239842A

Disclosure of Invention

Problems to be solved by the invention

In view of the above-mentioned drawbacks in the prior art, the present invention aims to provide an optical waveguide element, which has the advantages of high light transmittance, high diffraction efficiency, high angle selectivity of optical waveguide element diffraction, excellent optical waveguide imaging effect, and the like compared with the optical waveguide element in the prior art.

Furthermore, the invention also provides a preparation method of the optical waveguide element, which is simple, low in cost and free from complex post-treatment.

Solution for solving the problem

According to the intensive studies of the present inventors, it was found that the above technical problems can be solved by the implementation of the following technical scheme:

[1] the present invention provides an optical waveguide element comprising a laminate of at least two carriers and a photopolymer film, wherein

The photopolymer film is located between at least two carriers;

the photopolymer film has at least one light in-coupling region and at least one light out-coupling region;

the light in-coupling area is not connected with the light out-coupling area; and is also provided with

The positions of the light in-coupling region and the light out-coupling region are respectively provided with a grating structure.

[2] The optical waveguide element according to [1], wherein the photopolymer film has a thickness of 5 μm to 50 μm.

[3] The optical waveguide element according to the above [1] or [2], wherein the shortest distance between the light incoupling region and the light outcoupling region is 10mm to 10cm.

[4] The optical waveguide element according to any one of the above [1] to [3], wherein the thickness of the carrier is 1.5mm or less and the refractive index is 1.4 to 1.6.

[5] The optical waveguide element according to any one of the above [1] to [4], wherein the photopolymer film is derived from a photopolymer composition, wherein the photopolymer composition comprises the following components:

polymerizing a reactive monomer;

a dye compound;

an initiator;

a film-forming component; and

a plasticizer;

wherein the refractive index difference (n _{Polymerization of reactive monomers} -n _{Film-forming component} ) The value is above 0.075.

[6] The method according to the above [5], wherein the polymerization-active monomer is one or more selected from the group consisting of an acrylic monomer and an epoxy monomer.

[7] A method of manufacturing an optical waveguide element, comprising the steps of:

a step of preparing a photopolymer film;

a step of compounding and molding the support and the photopolymer film;

a step of forming a grating structure, the photopolymer film having at least one light incoupling region and at least one light outcoupling region, the light incoupling region being unconnected to the light outcoupling region,

and grating structures are respectively formed in the light in-coupling region and the light out-coupling region.

[8] The method for manufacturing an optical waveguide element according to the above [7], wherein the step of forming a grating structure includes a step of exposing the light in-coupling region and the light out-coupling region with coherent light.

[9] The method for producing an optical waveguide element according to the above [8], wherein the coherent light is coherent light having a wavelength of around 532 nm.

[10] A holographic optical waveguide display device comprising one or more optical waveguide elements according to any one of the above [1] to [6] or optical waveguide elements obtained by the method of any one of the above [7] to [9 ].

ADVANTAGEOUS EFFECTS OF INVENTION

Through implementation of the technical scheme, the invention can obtain the following technical effects:

the optical waveguide element has high refractive index modulation degree, diffraction efficiency, sensitivity and light transmittance, and also has excellent optical waveguide imaging effect.

Further, the optical waveguide element of the present invention can also have improved dimensional shrinkage and diffraction efficiency, and the optical waveguide element has a large angular selectivity of diffraction, a wider angular selectivity, and is less affected by environmental humidity.

The optical waveguide element has the advantages of simple manufacturing process, cheap and easily available raw materials, no need of complex post-treatment and easy large-scale industrial production.

Drawings

FIG. 1 is a schematic view showing the structure of an optical waveguide element in one embodiment of the present invention;

In fig. 1, 101: carrier, 102: photopolymer film, 103: light incoupling region, 104: light outcoupling regions.

Fig. 2 is a schematic view showing a light propagation path of an optical waveguide element in one embodiment of the present invention.

Fig. 3 is a schematic view showing a light propagation path of an optical waveguide element in still another embodiment of the present invention.

Fig. 4 is a schematic view showing a light propagation path of an optical waveguide element in still another embodiment of the present invention.

FIG. 5 shows a light path design of an optical waveguide element in one embodiment of the present invention;

in fig. 5, 1: a half-wave plate; 2: a beam splitting cube; 3: a shutter; 4: a beam expander; 5: a pinhole; 6: a collimating lens; 7: a beam splitter; 8: a reflecting mirror; 9: a reflecting mirror; 10: an optical waveguide element.

Fig. 6 shows an effect display diagram of an optical waveguide element in one embodiment of the present invention.

Detailed Description

The following describes the present invention in detail. The following description of the technical features is based on the representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

in the present specification, the numerical range indicated by the term "numerical value a to numerical value B" means a range including the end point numerical value A, B.

In the present specification, a numerical range indicated by "above" or "below" is a numerical range including the present number.

In the present specification, light of a certain wavelength is described using "vicinity", and it is understood that some errors may occur in use from theoretical values due to instrument errors or the like for a specific wavelength, and therefore, the use of "vicinity" is used to indicate that various types of wavelengths defined by the present invention include instrument errors or the like.

As used herein, "acrylate" includes the meaning of "(meth) acrylate" as well as "acrylate".

In the present specification, the meaning of "can" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

In this specification, the use of "optional" or "optional" means that certain substances, components, steps of performing, conditions of applying, etc. may or may not be used.

In the present specification, unit names used are international standard unit names, and "%" used represent weight or mass% unless otherwise specified.

As used herein, the term "particle size" refers to "average particle size" unless otherwise specified, and can be measured by a commercial particle sizer.

Reference throughout this specification to "some specific/preferred embodiments," "other specific/preferred embodiments," "an embodiment," and so forth, means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the elements may be combined in any suitable manner in the various embodiments.

The first aspect of the present invention provides an optical waveguide element comprising a laminate of at least two carriers 101 and a photopolymer film 102, wherein

The photopolymer film 102 is located between at least two carriers 101;

the photopolymer film 102 has at least one light in-coupling region and at least one light out-coupling region;

the light in-coupling region 103 is not connected to the light out-coupling region 104; and is also provided with

The positions of the light incoupling region 103 and the light outcoupling region 104 have grating structures, respectively.

< photopolymer film >

The optical waveguide element of the present invention is formed by sandwiching a layer of photopolymer film 102 between at least two layers of carriers 101.

In some embodiments of the present invention, the photopolymer film 102 has at least two unconnected exposed areas that can be exposed separately or simultaneously by a set of identical coherent light sources, and after post-processing, light in-coupling areas 103 and light out-coupling areas 104, each having a grating structure, can be formed in one light guiding element.

In some specific embodiments of the invention, the polymer film has a thickness of 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, still more preferably 20 μm or more, and further, the polymer film has a thickness of 50 μm or less, preferably 45 μm or less, more preferably 40 μm or less. For the above thickness of the polymer film, in practice, it may be coordinated or matched with the use of spacers, for example as described below.

Further, in order to more effectively realize diffraction imaging, the shortest distance between the light in-coupling region 103 and the light out-coupling region 104 of the present invention is 10mm or more, preferably 15mm or more; the shortest distance between the light in-coupling region 103 and the light out-coupling region 104 is 10cm or less, preferably 5cm or less, and more preferably 1cm or less.

Typically, the optical waveguide element has a regular shape to facilitate use and installation, and may be in the shape of an elongated sheet, a square sheet, or a circular sheet.

In some preferred embodiments, the optical waveguide element of the present invention has the shape of a strip as shown in fig. 1. The photopolymer film 102 has light in-coupling regions 103 and light out-coupling regions 104 at both end regions in the longitudinal direction thereof, and grating (hologram recording) structures are formed in the light in-coupling regions 103 and the light out-coupling regions 104, respectively.

Fig. 2 is a schematic view showing a light propagation path of an optical waveguide element in one embodiment of the present invention. Fig. 3 is a schematic view showing a light propagation path of an optical waveguide element in still another embodiment of the present invention. Specifically, as shown in fig. 2 and fig. 3, the light emitted by the optical machine enters the optical waveguide element, diffraction is generated at the position of the grating structure of the light coupling-in region 103, the angle of the diffracted light in the waveguide element satisfies the total reflection condition, the light is totally reflected inside the waveguide element, propagates to the grating structure of the light coupling-out region 104, and then diffracts again, so that the light is coupled out, and the required visual effect is obtained.

In some specific embodiments of the invention, the photopolymer film 102 is derived from a photopolymer composition. Specifically, the photopolymer composition comprises the following components:

Polymerizing a reactive monomer;

a dye compound;

an initiator;

a film-forming component; and

a plasticizer;

In some embodiments of the invention, the above components are mixed and then provided for further use in a molten or liquid form.

Initiation system

In the present invention, for a system for initiating polymerization of the system under light irradiation, a dye compound and an initiator are included. After the dye compound is excited by light, the initiator can react with the dye in an excited state to generate free radicals and cause the polymerization-active monomer in the system to start polymerization.

(dye compound)

In the present invention, the dye compound is a photosensitive dye compound. The photosensitizing dye compounds of the present invention may have excitation activity in the vicinity of any viable wavelength of light.

In particular, the dye compounds of the present invention may be selected according to different types of polymerization-active monomers. Examples of the compound include one or more of phycoerythrin B, eosin Y, erythrosin B,

basic red

2 and 2, 5-bis { [4- (diethylamino) -2-methylphenyl ] methylene } cyclopentanone, irgacure 784, new methylene blue, thionine, basic yellow, pinacol chloride, rhodamine 6G, betacyanine, ethyl violet, victoria blue R, azulene, quinaldine red, crystal violet, brilliant green, basic orange G (astrazon orangeG), darow red, pyronine Y, rose bengal, milone, 3.3' -carbonylbis (7-diethylaminocoumarin), pyrylium (pyrillium I), diiodofluorescein, anthocyanin and methylene blue, day a, crystal violet (leuconitrile) or malachite green (leuconitrile).

In some specific embodiments of the present invention, the dye compounds of the present invention may be selected from those dyes having excitation activity at least in the vicinity of 532nm wavelength. These dye compounds can have a maximum absorption peak or be excited to generate an activity when irradiated with green light (wavelength of around 532 nm), and as a result, energy transfer and/or change in properties such as self-structure and color can be generated. In addition, the dye compound of the present invention may have excitation activity in the vicinity of a light wavelength of 532nm, and optionally may have excitation activity in the vicinity of other light wavelengths, but in this case, the dye compound of the present invention preferably has a maximum absorption peak in the vicinity of a light wavelength of 532 nm.

In other specific embodiments of the present invention, the dye compounds of the present invention exhibit excitation activity only around 532nm wavelength of light, while exhibiting no apparent excitation activity or no absorption peak appearance, which can be considered to be strong, under other wavelengths of light.

In a preferred embodiment of the present invention, the dye compound may be selected from one or more of phycoerythrin B, eosin Y, erythrosin B,

basic red

2 and 2, 5-bis { [4- (diethylamino) -2-methylphenyl ] methylene } cyclopentanone.

In some specific embodiments of the present invention, the content of the dye compound having an excitation activity in the vicinity of a wavelength of 532nm in the photopolymer composition is 70% or more, preferably 80% or more, more preferably 90% or more, still more preferably 95% or more based on the total weight of the dye compound used.

(initiator)

In the above-mentioned initiating system of the present invention, an initiator (may be referred to as a co-initiator under some conditions) is used in combination in addition to the dye compound described above. Initiators suitable for use in the present invention are generally those photoinitiators which can be activated by irradiation with light and initiate polymerization of the corresponding polymerizable groups, or alternatively, initiators suitable for use in the present invention can react with an excited dye to form free radicals and thereby initiate polymerization of the monomers.

The photoinitiators which may be used in the present invention may be distinguished as single-molecule initiators (type I) and as double-molecule initiators (type II). They are further distinguished by their chemical characteristics by photoinitiators of the polymerization type used for free radicals, anions, cations or mixtures.

Photoinitiators of type I for free radical photopolymerization (Norrish type I) form free radicals by cleavage of single molecular bonds when irradiated.

Photoinitiators of type I are, for example, triazines, such as tris (trichloromethyl) triazine, oximes, benzoin ethers, benzil ketals, alpha-dialkoxyacetophenones, phenylglyoxylates, bisimidazoles, 2- (4-chlorophenyl) -4, 5-diphenylimidazoles, aroylphosphine oxides (e.g., 2,4, 6-trimethylbenzoyl diphenylphosphine oxide), sulfonium and iodonium salts and the like.

Photochemistry of these compounds has been studied for a long time for sulfonium and iodonium salts. Iodonium salts, after excitation, first homolytically decompose and thereby generate a radical and a radical cation, which finally releases protons by hydrogen abstraction and thus initiates cationic polymerization (Dectar et al J.Org.Chem.1990,55,639;J.Org.Chem, 1991,56.1838). This mechanism makes iodonium salts equally useful for free radical photopolymerization. The choice of counterions is likewise very important here. Also preferred is the use of SbF ^6- 、AsF ^6- Or PF (physical pattern) ^6- . On the other hand, this structural class is quite free in terms of substitution on the choice of aromatic compound, essentially determined by the availability of suitable synthetic starting units. Sulfonium salts are compounds that decompose according to the Norrish type II mechanism (Crivello et al, macromolecules,2000,33,825). The choice of counter ion in sulfonium salts is also extremely important, as it is essentially reflected in the cure rate of the polymer. In some preferred embodiments of the invention iodonium salts are preferably used and are used as PF ^6- As counter ion.

A photoinitiator of type II (Norrish type II) for free radical polymerization undergoes a bimolecular reaction when irradiated, wherein the photoinitiator reacts in the excited state with a second molecule (co-initiator) to form free radicals which induce polymerization by electron or proton transfer or direct hydrogen abstraction.

Type II photoinitiators such as quinones, for example camphorquinone, aryl ketone compounds, for example benzophenones, alkyl benzophenones, halogenated benzophenones, 4' -bis (dimethylamino) benzophenone (Michler ketone), anthrone, methyl 4-dimethylaminobenzoate, thioxanthone, ketocoumarin, alpha-aminoalkylbenzophenone or alpha-hydroxy-alkylbenzene ketone, in combination with tertiary amines.

In the present invention, the photoinitiator of type I, II may be used in the UV and/or visible light region.

In some specific embodiments of the invention, mixtures of these photoinitiators may also be used advantageously. Depending on the conditions of the radiation source used, the type and concentration of the photoinitiator should be matched in a manner known to the person skilled in the art. Additional details are described, for example, in P.K.T.Olding (Ed.), chemistry & Technology of UV & EB Formulations For Coatings, inks & paint, vol.3,1991, SITA Technology, london, pages 61-328.

In some specific embodiments of the present invention, the initiator is selected from one or more of diphenyliodonium hexafluorophosphate, ethyl 4-dimethylaminobenzoate, N-phenylglycine, 2- (4-chlorophenyl) -4, 5-diphenylimidazole.

Polymerization of reactive monomers

In the present invention, a monomer having polymerization activity is used to perform polymerization reaction and form a crosslinked structure upon exposure to light. The polymerization active monomer suitable for the invention comprises one or more of acrylic ester monomers and epoxy compounds. In some preferred embodiments of the present invention, the polymerization active monomer has a refractive index of 1.55 or more, preferably 1.57 or more, and more preferably 1.58 or more, in view of increasing the refractive index modulation degree.

In addition, the polymerizable reactive monomer of the present invention may include a polymerizable reactive monomer having one or more (two or more) functional groups. Such polymerization-active monomers may be all acrylate monomers, all epoxy compounds, or a mixture thereof. Preferably, such polymerization-active monomers include at least acrylic monomers. The content of the monomer having a plurality of functional groups is 20 to 50%, preferably 25 to 40% based on the total weight of the polymerization-active monomers, in terms of improving diffraction efficiency, dimensional stability and improving refractive index modulation.

For the acrylate monomer having one functional group suitable for the present invention, it may have the structure of the following general formula (I-1) or (I-2):

Ar-L-(X-O) _n -C(O)-CH＝C(R ₁ ) ₂ (I-1)

Ar-L-(X-O) _n -C(O)-C(CH ₃ )＝C(R ₁ ) ₂ (I-2)

wherein, the liquid crystal display device comprises a liquid crystal display device,ar represents a group having one or more aromatic groups, preferably having 1 to 3 benzene rings, further preferably phenyl, naphthyl or biphenyl, optionally substituted or unsubstituted; l is an oxygen atom or a sulfur atom; x represents a linear or branched alkyl group having 1 to 6 carbon atoms, preferably a linear or branched alkyl group having 2 to 3 carbon atoms, optionally substituted or unsubstituted; n represents an integer of 1 to 5, preferably an integer of 1 to 3; the method comprises the steps of carrying out a first treatment on the surface of the R is R ₁ Each occurrence, identical or different, independently represents a hydrogen or halogen atom.

For the acrylate monomer having a plurality of functional groups suitable for the present invention, it may have the structure of the following general formula (II-1) or (II-2):

wherein R is ₁ X, L are as defined in (I-1) and (I-2) above, n represents an integer of 1 to 5, preferably an integer of 1 to 3, Z represents a group containing one or more aromatic groups, preferably Z represents a substituted or unsubstituted phenyl or biphenyl group.

In the present invention, for the acrylic monomer having a refractive index of 1.55 or more, an acrylic monomer substituted with an aromatic group selected from one or more of phenyl, biphenyl, naphthyl, and fluorenyl or with halogen may be used in addition to the monomer having the above-described structure.

In some specific embodiments, the acrylate monomer having an aromatic group may be selected from: biphenyl-containing acrylates such as [1, 1-biphenyl ] -4, 4-diylbis (2-methacrylate), 4' -biphenyl diacrylate, and the like; naphthalene-containing acrylates such as 1-naphthalene methacrylate, 2 '-bis (2-acryloyloxy) -1,1' -thiobinaphthyl, 2 '-bis [2- (2-acryloyloxyethoxy) -1,1' -binaphthyl, 2 '-bis [ 2-acryloyloxyethoxy) -1,1' -thiobinaphthyl and the like.

In some specific embodiments, the halogen in the substituted acrylate comprises a fluorine element, a chlorine element, or a bromine element, preferably the halogen is a bromine element. Such acrylate monomers as p-chlorophenyl acrylate, p-bromophenyl acrylate, pentachlorophenyl acrylate, pentabromophenyl acrylate, 2,4, 6-tribromophenyl acrylate, 2,4, 6-trichlorophenyl acrylate and the like can be cited.

Furthermore, as the epoxy-based compound monomer suitable for the present invention, those having a higher refractive index (1.55 or more) are preferable, which is advantageous in improving dimensional stability.

In the present invention, the epoxy compound that can be used may have the structure of the following general formula (III):

Wherein E represents an epoxy group-containing group. In some specific embodiments, each E group may contain 1 or 2 epoxy groups. Further, from the viewpoint of suppressing the dimensional shrinkage after film formation, in a preferred embodiment, each E group contains 1 epoxy group when it appears.

The structure of the epoxy group is not particularly limited, and the epoxy group is preferably present as an aliphatic epoxy group. In addition, in other embodiments, the epoxy group or epoxy structure in the E group is bonded to Ar as described above through an ether group ₁ The groups are linked. The ether group may be a thioether group or an oxyether group, and is preferably an oxyether group in view of suppressing the dimensional shrinkage after film formation.

In the above general formula (III), n representing the number of E groups is an integer of 0 to 4, and each E group is the same or different. It goes without saying that the total number of n is not 0 in the present invention. In some preferred embodiments, n is 1 for each occurrence.

In the above formula (III), each Ar ₁ Identical or different, independently represent aryl-containing groups. In some preferred embodiments of the inventionAr in (1) ₁ Represents a group having 1 or two substituted or unsubstituted benzene rings, typically Ar ₁ May be selected from the following structures:

wherein X in formula (b) is selected from a single bond, O or S atom.

In the above formula (III), -C (R) ₃ R ₄ ) -carbonyl formation, or, R ₃ 、R ₄ The same or different, each occurrence independently represents a hydrogen atom, an aryl group having 6 to 30 carbon atoms, or an alkyl or alkoxy group having 1 to 10 carbon atoms, and R ₃ 、R ₄ Can be connected by single bond; preferably an alkyl group or an alkoxy group having 1 to 3 carbon atoms;

in some preferred embodiments of the present invention, the epoxy-based compounds suitable for use in the present invention have a structure represented by the following general formula (IV):

wherein R is ₃ And R is ₄ The same definition as in formula (III).

R ₅ Each occurrence of which is the same or different and is independently selected from hydrogen, halogen and alkyl groups having 1 to 5 carbon atoms; preferably an alkyl group of 1 to 3, x is an integer of 0 to 4, preferably 0 or 1. The halogen may be F, cl or Br atoms.

In a further preferred embodiment, the epoxy compound suitable for use in the present invention has a structure represented by the following general formulae (IV-1) to (IV-3):

the epoxy compound of the present invention may be used singly or as a mixture of two or more epoxy compounds.

For the epoxy compounds suitable for use in the present invention, the epoxy compounds described above can be obtained by methods common in the art, and in typical embodiments, can be prepared using a coupling reaction of epichlorohydrin with a phenolic compound:

in addition, other polymerizable components including other acrylate monomers or epoxy compound monomers, which are different from the acrylate monomers and epoxy compound monomers, may be used in the photopolymer composition of the present invention, in addition to the above-described polymerizable reactive monomers such as acrylate monomers and epoxy compound monomers, without affecting the technical effects of the present invention.

These other acrylate monomers that may be used include mono-and multifunctional acrylates, mono-and multifunctional urethane acrylates, in particular:

other acrylates which may be used are, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, ethoxyethyl acrylate, ethoxyethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, hexyl acrylate, hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, butoxyethyl acrylate, butoxyethyl methacrylate, dodecyl acrylate, dodecyl methacrylate.

Other useful urethane acrylates are understood to mean compounds having at least one acrylate group with at least one urethane bond. Such compounds are known to be obtainable by reacting hydroxy-functional acrylates with isocyanate-functional compounds.

Isocyanate-functional compounds such as aromatic, araliphatic, aliphatic and cycloaliphatic di-, tri-or polyisocyanates can be used for this purpose. Mixtures of such di-, tri-or polyisocyanates may also be used. Suitable di-, tri-or polyisocyanates are, for example, butylene isocyanate, hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), 1, 8-diisocyanato-4- (isocyanatomethyl) octane, 2, 4-and/or 2, 4-trimethylhexamethylene diisocyanate, bis (4, 4 '-isocyanatocyclohexyl) methane isomers and mixtures thereof having any desired isomer content, isocyanatomethyl-1, 8-octane diisocyanate, 1, 4-cyclohexyl diisocyanate, cyclohexanedimethylene diisocyanate isomers, 1, 4-phenylene diisocyanate, 2, 4-and/or 2, 6-toluene diisocyanate, 1, 5-naphthalene diisocyanate, 2,4' -or 4,4 '-diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, m-methylthiophenyl isocyanate, triphenylmethane 4,4',4 "-triisocyanate and tris (p-isocyanatophenyl) thiophosphate or mixtures thereof having a urethane, urea, carbodiimide, urethane, dioxazine or derivatives thereof. Aromatic or araliphatic di-, tri-or polyisocyanates are preferred.

Hydroxy-functional acrylates or methacrylates suitable for the preparation of urethane acrylates are the following compounds: 2-hydroxyethyl (meth) acrylate, polyethylene oxide mono (meth) acrylate, polypropylene oxide mono (meth) acrylate, polybutylene oxide mono (meth) acrylate, poly (. Epsilon. -caprolactone) mono (meth) acrylate, e.g.

M100 (Dow, schwalbach, germany), 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxy-2, 2-dimethylpropyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl acrylate, polyols such as trimethylolpropane, glycerol, pentaerythritolHydroxy-functional mono-, di-or tetraacrylates of tetrol, dipentaerythritol, ethoxylated, propoxylated or alkoxylated trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol or technical mixtures thereof. Among them, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate and poly (. Epsilon. -caprolactone) mono (meth) acrylate are preferable.

In the present invention, the addition of a polyfunctional monomer is advantageous for increasing the crosslinking density, and therefore, for the other polyfunctional acrylate monomers which can be used, some acrylate monomers having a functional group of 3 or more, for example, pentaerythritol tetraacrylate, octafunctional hyperbranched monomer ETERCURE6361-100 or polyfunctional urethane acrylate, etc. are preferably used.

Among the acrylic monomers used in the present invention, the acrylic monomer having the refractive index of more than 1.55 according to the present invention has a weight sum of 80% or more, preferably 90% or more, and more preferably 95% or more, based on the total weight of all acrylic monomers.

Further, it is preferable that the epoxy compound having a certain refractive index, for example, a refractive index of 1.5 or more, preferably 1.52 or more, and more preferably 1.55 or more, is used as the other epoxy compound.

Further, other epoxy compounds such as:

/>

wherein Y represents a single bond or a heteroatom such as O or S.

In some specific embodiments of the present invention, when the epoxy compound of the present invention is used in combination with epoxy compounds of other structures, the epoxy compound of the above structure (formula (III)) of the present invention is used in an amount of 80% or more, preferably 90% or more, and more preferably 95% or more, based on the total weight of the epoxy compounds.

Film-forming component

The film-forming component used in the present invention may be selected from polymers or resin materials having a molecular weight of 1000 or more and a certain adhesiveness. Preferably, these materials have a lower refractive index, and in some specific embodiments, the refractive index of these materials is 1.480 or less, preferably 1.475 or less, and more preferably 1.470 or less.

In the present invention, suitable film-forming components include:

homopolymers of vinyl acetate or copolymers of vinyl acetate with acrylic esters, ethylene, styrene, etc.;

cellulose esters such as cellulose acetate, cellulose acetate-succinate, cellulose acetate-butyrate;

cellulose ethers such as methyl cellulose, ethyl cellulose, benzyl cellulose, and the like;

polyvinyl alcohol;

polyvinyl acetals such as polyvinyl butyral, polyvinyl formal, and the like;

polyurethanes, typically obtained by reacting polyols such as polytetrahydrofuran, polyethylene glycol, polypropylene glycol, castor oil, and isocyanates such as hexamethylene-1, 6-diisocyanate, 1, 4-cyclohexane diisocyanate, methyl-2, 4-diisocyanate;

styrene/butadiene block copolymers;

polyvinylpyrrolidone, and the like.

The preferable film-forming component of the present invention is at least one selected from the group consisting of cellulose acetate butyrate, polyvinylpyrrolidone, polyvinyl alcohol, and polyvinyl acetate from the viewpoint of suppressing dimensional shrinkage of the final optical waveguide product, and improving diffraction efficiency and refractive index modulation degree.

In addition, in the present invention, the higher the refractive index of the above-mentioned polymerization active monomer and the larger the refractive index difference with the film-forming component, it is advantageous to improve the diffraction efficiency and refractive index modulation degree of the final hologram recording material. Thus, in the present invention, the refractive index difference (n _{Polymerization of reactive monomers} -n _{Film formationComponent (A)} ) The value is 0.075 or more, preferably 0.078 or more, further preferably 0.080 or more, for example, 0.085 or more, 0.090 or more, and 0.100 or more.

Plasticizer(s)

In the present invention, the plasticizer is used to increase the flexibility of the photopolymer composition and to alleviate the degree of dimensional shrinkage that occurs after film formation and curing.

In some specific embodiments, plasticizers suitable for use in the present invention are polymeric materials having good compatibility/dissolution characteristics, low volatility, and high boiling point. Typically, these polymeric materials may be polyols or glycidyl ethers of polyols. From the viewpoint of suppressing dimensional shrinkage, in a preferred embodiment of the present invention, the polyhydric alcohol may be polyethylene glycol, polypropylene glycol, or the like; the glycidyl ether of the polyol can be polyethylene glycol diglycidyl ether or polypropylene glycol diglycidyl ether. The plasticizer may be stabilized by adding a substance such as an acid anhydride or a polyisocyanate.

Some plasticizers that may additionally be used may include small molecule plasticizers such as butylene phthalate, N-vinyl pyrrolidone, and the like.

For the plasticizer of the present invention, one or a combination of two or more kinds may be used.

Other ingredients

In the present invention, as long as the technical effects of the present invention are not affected, other components commonly used in the art may be used according to actual production needs, and these components include: solvents, levelling agents, wetting agents, defoamers or adhesion promoters, as well as polyurethanes, thermoplastic polymers, oligomers, compounds with additional functional groups (e.g. acetals, epoxides, oxetanes, oxazolines, dioxolanes) and/or compounds with hydrophilic groups (e.g. salts and/or polyethylene oxides) can be used as additional auxiliaries and additives.

In some embodiments of the invention, the optional solvent is a volatile solvent having good compatibility with the components of the invention, such as ethyl acetate, butyl acetate, and/or acetone, among others. Although the use of solvents is generally believed to result in a significant dimensional shrinkage effect, in the present invention, even if solvents are used in the provided photopolymer composition, the effect of suppressing dimensional shrinkage can be significantly observed as compared to the conventional photopolymer composition.

Composition

For the composition of the photopolymer composition provided by the present invention, in some preferred embodiments, it may be (based on the total weight of the composition):

the content of the polymerization active monomer can be 30-60%, preferably 35-50%, when the content is lower than 30%, the shrinkage rate of the grating structure in the optical waveguide element is higher, the optical waveguide element is easy to deform, and when the content is higher than 60%, the diffraction efficiency of the grating structure is lower, and the imaging quality of the optical waveguide element is deviated. In some specific embodiments, the monofunctional monomer content in the polymerization-active monomer is 20% to 40%, and the multifunctional monomer content is 10% to 20%.

The content of the dye compound may be 0.1 to 2%, preferably 0.4 to 1%, and when the content is less than 0.1%, insufficient photosensitivity causes low efficiency, and when the content is more than 2%, there is a possibility that film forming processability of the photopolymer composition is lowered, affecting diffraction efficiency of the finally obtained optical waveguide element.

The content of the film-forming component may be 10 to 40%, preferably 15 to 30%, and when the content is less than 10%, it is disadvantageous to the film-forming process, and when the content is more than 40%, it may cause a decrease in the refractive index modulation degree.

The initiator content may be 0.5 to 5%, preferably 1.5 to 2.5%; the plasticizer may be contained in an amount of 10 to 40%, preferably 15 to 35%.

The content of the components other than the above components is not particularly limited, and the components may be used in accordance with the usual use amount range in the art, provided that the technical effects of the present invention are not impaired.

< vector >

For the carrier 101, the substrate may preferably be a layer of material or a composite of materials that is transparent in the visible spectrum (light transmittance greater than 85% in the wavelength range 400-780 nm).

Preferred materials or material composites of the substrate of the carrier 101 are based on Polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene, polypropylene, cellulose acetate, cellulose hydrate, nitrocellulose, cyclic olefin polymer, polystyrene, polyepoxide, polysulfone, cellulose Triacetate (CTA), polyamide, polymethyl methacrylate, polyvinyl chloride, polyvinyl butyral or polydicyclopentadiene or mixtures thereof. They are more preferably based on PC, PET and CTA. The material composite may be a foil laminate or a co-extrusion. Preferred material composites are dual or triple foils constructed according to one of schemes A/B, A/B/A or A/B/C. PC/PET, PET/PC/PET and PC/TPU (tpu=thermoplastic polyurethane) are particularly preferred.

As an alternative to the substrates of the aforementioned carriers 101, it is also possible to use flat glass plates or transparent plastic films, in particular for large-area precision imaging exposure, for example for holographic lithography (holographic interference lithography for integrated optics, IEEE Transactions on Electron Devices (1978), ED-25 (10), 1193-1200, ISSN: 0018-9383).

The thickness of the support 101 suitable for the present invention may be 1.5mm or less, preferably 20 μm to 1mm, further preferably 100 μm to 900 μm, for example: 200 μm to 400 μm, etc.

The refractive index of the carrier 101 may be 1.4 or more in the present invention, and specifically, considering that total reflection only occurs between the carrier 101 and the air (optical density to optical transparency), the refractive index of the carrier 101 is preferably 1.4 to 1.6 because it is close to the refractive index of most organic polymers to facilitate the total reflection when the refractive index of the carrier 101 is 1.4 to 1.6. Further, the present invention preferably uses a carrier 101 of a larger refractive index and a photopolymer film 102 of a larger refractive index because the angle required for the total reflection condition between the carrier 101 and air will be larger, i.e. the FOV (viewing angle) of the waveguide sheet will be significantly increased.

In other cases, the optical waveguide element may additionally comprise a cover layer and/or other functional layer, optionally each at least partially connected to the photopolymer film 102.

In addition, in still other cases, a cover layer and/or other functional layer, optionally each at least partially attached to the carrier 101, may also be additionally included on a side of the carrier 101 remote from the photopolymer film 102. For example, the optical waveguide element may optionally have cladding and/or other functional layers attached to the carrier 101 locally at other locations than the light in-coupling region 103 and the light out-coupling region 104.

The optical waveguide element obtained in the present invention may be a planar optical waveguide element or a curved optical waveguide element having a predetermined curvature. For curved surface optical waveguide components, light will be deflected in the waveguide, the display image will be elongated, and if the distortion of the light source is adjusted, the output image of the optical machine can be adapted to the display effect of the waveguide sheet, so that the FOV (visual angle) of the waveguide sheet is improved, as shown in fig. 4.

A second aspect of the present invention provides a method of manufacturing an optical waveguide element of the first aspect, comprising the steps of:

A step of preparing a photopolymer film 102;

a step of compounding the support 101 with the photopolymer film 102;

a step of forming a grating structure, the photopolymer film 102 having at least one light incoupling region 103 and at least one light outcoupling region 104, the light incoupling region 103 being unconnected to the light outcoupling region 104,

grating structures are formed in the light incoupling region 103 and the light outcoupling region 104, respectively.

The step of forming the carrier 101 and the photopolymer film 102 in a composite manner and the step of forming the grating structure in a composite manner are not particularly limited, and the step of forming the carrier 101 and the photopolymer film 102 in a composite manner may be performed before forming the grating structure, or the step of forming the grating structure in a composite manner and the step of forming the carrier 101 and the photopolymer film 102 in a composite manner may be performed before forming the grating structure, preferably the step of forming the carrier 101 and the photopolymer film 102 in a composite manner.

Step of preparing photopolymer film 102

In the present invention, the raw materials of the photopolymer film 102 are mixed to obtain a mixture, and the mixture is formed into a film. Specifically, the raw material of the photopolymer film 102 may be the photopolymer composition described above.

Specifically, the compositions are mixed in a suitable container in proportion, and mechanical stirring or the like may be employed to make the mixing uniform, if any desired. The temperature of the mixing is not particularly limited, and in general, the mixing may be carried out under ambient conditions or heating conditions.

In some embodiments of the invention, the use of a suitable heating process facilitates the formation of a homogeneous mixture, particularly without the additional use of solvents. The heating temperature may be determined based on the activity of the components in the photopolymer composition and the desired viscosity of the system. Under some conditions it is desirable to increase the mixing temperature to obtain lower viscosities, but this is desirable to avoid excessive polymerization reactions in unnecessary processing windows to cause difficulties in subsequent processing.

In some preferred embodiments of the invention, the temperature used in the step of mixing is above 60 ℃, more preferably above 70 ℃, and below 115 ℃, preferably below 110 ℃. The resulting molten or liquid mixture can be used immediately or stored at the processing temperature for a short period of time awaiting use.

In addition, in the preferred embodiment of the present invention, the use of spacers in the photopolymer film 102 is advantageous for process control in view of controlling the thickness of the photopolymer film 102, suppressing shrinkage of the optical waveguide element size, and maintaining high diffraction efficiency, especially in the case of the present invention in which one photopolymer film 102 is sandwiched with two-layer carriers 101.

For the spacer, in some specific embodiments of the present invention, particles that are substantially opaque to visible light may be used. These particles may be inorganic particles, organic particles or metallic particles. The present invention preferably uses inorganic particles in view of suppressing the dimensional shrinkage of the optical waveguide element and production cost.

The kind of the inorganic particles is not particularly limited, and silica, titania, and the like can be used, for example. In some specific embodiments, the inorganic particles have a substantially spherical, three-dimensional shape; in other specific embodiments, the inorganic particles have an average particle size of 2 to 50 μm, preferably 3 to 40 μm, and the particle size of the spacers may be coordinated, selected or determined with the thickness of the formed photopolymer film 102.

As for the method of using the spacer, in the present invention, the spacer may be formed on the surface of the support 101 in advance, which can be achieved by a coating method of a dispersion system containing the spacer. In some embodiments, the spacer may be dispersed in a hydrocarbon, alcohol, or ketone solvent, for example, to form a dispersion. For these solvents, it is preferable to use a substance having a low boiling point, and the solvents which may be cited include one or more of benzene, toluene, cyclohexane, pentane, ethanol, isopropanol, acetone, butanone, and the like. The dried spacer particles (powder) may be directly dispersed in these solvents, or the sol-like substance formed by the spacer may be dispersed in these solvents.

For the concentration of the spacer-containing dispersion, in some embodiments of the invention, it may be 0.1 to 3mg/mL, preferably 0.1 to 0.3mg/mL, and too high a concentration may deteriorate the uniformity of dispersion, and at the same time light propagates in the waveguide and is scattered by the spacer to generate stray light, forming a hazy background, resulting in a decrease in diffraction efficiency of the optical waveguide element.

In the present invention, the spacers can be uniformly coated on the surface of the carrier 101 by a coating method, and the coating method is not particularly limited and can be performed by a spray coating method or a spin coating method. After forming spacers on the surface of the carrier 101 by a coating method, the solvent may be removed by heating or blowing, or the like.

A step of compositely molding the support 101 and the photopolymer film 102

In this step, a film is formed on the support 101 by using the molten and liquid mixture obtained above. In some specific embodiments of the invention, the photopolymer 102 film has a thickness of 5 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and in addition, the polymer film has a thickness of 50 μm or less, preferably 40 μm or less. For the above thickness of the polymer film, in practice, it may be coordinated or matched with the use of spacers, for example as described below.

As for the material of the carrier 101, the same definition as the above < first aspect >, and in a preferred embodiment, glass may be used as the carrier 101. Optionally, the carrier 101 is subjected to cleaning, drying, etc. prior to use.

Further, the (hot) melt or liquid obtained as described above is formed into a film on the surface of the side having the spacers on the support 101. For example, flat onto the carrier 101, in which case, for example, means known to those skilled in the art such as doctor blade devices (doctor blade, knife roll, curved bar (Commabar), etc.), slit nozzles, etc. can be used. Optionally, a degassing step is carried out after the film coating to eliminate air bubbles that may be present in the film. After coating, the photopolymer film may be obtained by cooling or the like.

In the present invention, the photopolymer film 102 described above, which can be used as a holographic medium, can be processed into holograms for various optical applications by a suitable exposure operation. Visual holograms include all holograms which can be recorded by methods known to the person skilled in the art.

Step of Forming a Grating Structure

The grating structure is formed on at least two unconnected positions of the photopolymer film 102 by exposure, bleaching and the like in the present invention, so as to form the light in-coupling region 103 and the light out-coupling region 104 with the grating structure. In this process, exposure to coherent light may be used to control the microstructure. The coherent light may have any feasible wavelength, and preferably, coherent light having a wavelength around 532nm is used.

In some preferred embodiments of the present invention, the exposure treatment of the photopolymer film 102 can be performed with two beams of coherent light. There is no particular limitation on the source of the coherent light having a wavelength of around 532nm, and in some embodiments of the present invention, the photopolymer film 102 obtained as described above may be simultaneously exposed by dividing a green laser light into two coherent light beams of the same or different light intensities through an optical element.

By exposure with coherent light, it is possible to present spaced bright and dark regions in the photopolymer film 102 (two beams of coherent light create alternating bright and dark fringes in the photopolymer film 102). The monomer in the bright area is polymerized under the action of an initiator, so that the concentration of the monomer is reduced; the difference in concentration between the light and dark regions causes phase separation of the monomer, and the monomer in the dark region migrates to the light region, and forms a refractive index difference Δn (refractive index modulation degree) between the light and dark regions. For exposure intensity, it may be 5-30mJ/cm in some embodiments of the invention ² . The exposure sensitivity of the invention can reach 5mJ/cm ² Has higher exposure efficiency.

In some embodiments of the invention, two beams of coherent light may be simultaneously exposed from one side of the polymer film (transmissive grating structure); in other embodiments, two beams of coherent light are used to expose the polymer (reflective grating structure) from two sides of the polymer film, respectively.

After exposure, a refractive index distribution with a sine function distribution is formed in the photopolymer film 102, and a diffraction grating structure is obtained. The difference between the sine wave peaks is Δn (refractive index modulation degree). In some specific embodiments of the invention, Δn may be 0.025 or more, preferably 0.030 or more, more preferably 0.032 or more, 0.035 or more, 0.040 or more, 0.045 or more, 0.05 or more, or 0.06 or more.

In view of improving the grating angle selectivity, in a preferred embodiment of the present invention, the polymer film is exposed to light from both sides of the polymer film by two coherent light beams, respectively, to form a reflective grating structure, thereby obtaining an optical waveguide element. Such an optical waveguide element may have a large angular selection range up to ±14° or even up to ±16° and a diffraction efficiency of 70% or more, preferably 80% or more, further preferably 90% or more. Thus, this also illustrates that the above-described photopolymer composition of the present invention is particularly suitable for use in the preparation of reflective diffractive optical waveguide elements.

As shown in fig. 5, fig. 5 shows a typical optical path design of the present invention, where a visible laser beam is split into two laser beams with the same or different intensities, and the two coherent laser beams are reflected and converged on the photopolymer film 102 by a mirror to perform exposure. The photopolymer film 102 is then moved so that the light is concentrated at other locations of the photopolymer film 102 that are not connected to the previously exposed locations and re-exposed.

After exposure, a holographic diffraction grating structure is formed in the photopolymer film 102, which is irradiated with natural light (without the need for further complicated post-treatments) to obtain the final reflective diffraction grating structure comprising the photopolymer film 102.

In addition, the present invention is not particularly limited to a method for manufacturing a curved optical waveguide element, and in some specific embodiments, a film may be formed on a substrate having a certain curvature and exposed to light. In other embodiments, a planar substrate may be used, and the coated film may be exposed to light and then processed (e.g., using an external force) to form a curved optical waveguide element having a certain curvature.

In a third aspect of the present invention, an application of the optical waveguide element obtained as described above of the present invention is disclosed. Without limitation, one or more of the optical waveguide elements of the present invention described above may be used in a variety of holographic optical waveguide display devices in the art, and may be used alone or in combination with other optical elements.

Further, the optical waveguide element of the present invention can be used in a holographic optical waveguide display device, and is particularly suitable for head-display devices for augmented reality (Augmented Reality, AR), such as AR display glasses devices, and the like.

Examples

Hereinafter, the present invention will be described by way of specific examples.

Example 1

An optical waveguide element prepared by the steps of:

1) In a darkroom or red light environment, mixing 10mL of polymer (obtained by heating to 100 ℃) and 2mg of silica microsphere spacers with average particle size of 20 μm according to the following proportion to form a mixture, heating to 100 ℃ and stirring for 4 hours until the mixture is uniform;

2) Coating the mixed solution obtained in the step (1) on a glass substrate with the thickness of 1mm and the size of 20mm multiplied by 70mm under the condition of maintaining the temperature of 100 ℃, covering the upper surface of the mixed solution with another glass substrate with the thickness of 1mm and the size of 20mm multiplied by 70mm, and cooling to normal temperature to obtain a solid-state photopolymer dry plate;

3) Performing interference exposure (shown in figure 5) on one side of the dry plate obtained in the step (2) after 532nm laser beam expansion and beam splitting, wherein the exposure area is 15mm multiplied by 15mm, and forming a volume holographic grating structure; the dry plate is exposed by adopting a high laser intensity short exposure time mode, and the exposure energy density is 5mJ/cm ² ；

4) Translating the dry plate obtained in the step (3), selecting a blank area with the length of 15mm multiplied by 15mm on the other side, and repeating the step (3) to obtain a group of optical waveguide elements of the volume holographic grating, wherein the distance between two exposure areas is 30mm;

5) And (3) completely fixing and bleaching the optical waveguide element of the volume holographic grating obtained in the step (4) after natural light irradiation for about 30min, and no post-treatment is needed.

The resulting dry film component content of the photopolymer is shown in table 1 below:

TABLE 1

Composition of the composition	Content of
		2, 5-bis { [4- (diethylamino) -2-methylphenyl ]]Methylene } cyclopentanone	0.2％
N-phenylglycine	0.8％
		2-phenylthioethyl acrylate (n=1.557)	28％
9, 9-bis (methyl acrylate) fluorene (n=1.606)	14％
		Cellulose acetate butyrate (n=1.475)	28％
Polyethylene glycol	29％

The diffraction efficiency of the optical waveguide element is more than 70%, the angle selectivity reaches +/-6 degrees, and the effect display diagram of the prepared optical waveguide element is shown in fig. 6.

Example 2

The same procedure as in example 1, but with an exposure energy density of 8mJ/cm ² And the resulting dry film component contents of the photopolymer are shown in table 2 below:

TABLE 2

Composition of the composition	Content of
		Basic Red 2	0.2％
N-phenylglycine	0.8％
		2- (4-chlorophenyl) -4, 5-diphenylimidazole	1％
2-naphthylthio ethyl acrylate (n=1.620)	33％
		9, 9-bis (methyl acrylate) fluorene (n=1.606)	11％
Cellulose acetate butyrate (n=1.475)	22％
		N-vinylpyrrolidone	32％

The diffraction efficiency of the optical waveguide element obtained by the embodiment is more than 95%, the angle selectivity reaches +/-12 degrees, the exposure is sensitive, and the refractive index modulation degree reaches 0.08.

Example 3

The same method as in example 1, but with exposure energyDensity is 20mJ/cm ² The resulting dry film component content of the photopolymer is shown in Table 3 below:

TABLE 3 Table 3

Composition of the composition	Content of
		Basic Red 2	0.2％
4-Dimethylaminobenzoic acid ethyl ester	0.8％
		Diphenyliodonium hexafluorophosphate	1％
2-naphthalenyl acrylate (n=1.608)	39％
		9, 9-bis (methyl acrylate) fluorene (n=1.606)	13％
Cellulose acetate butyrate (n=1.475)	13％
		Glutaric anhydride	7％
Polyethylene glycol	26％

In the embodiment, after the polyethylene glycol is modified by glutaric anhydride and then mixed with cellulose acetate butyrate, the diffraction efficiency of the prepared optical waveguide element is as high as 85%.

It should be noted that, although the technical solution of the present invention is described in specific examples, those skilled in the art can understand that the present disclosure should not be limited thereto.

The foregoing description of the embodiments of the present disclosure has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or the improvement of technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Industrial applicability

The optical waveguide element of the present invention can be industrially produced and used in a holographic optical waveguide display device.

Claims

1. A reflective diffractive optical waveguide element, characterized by: comprising a laminate of two supports and a photopolymer film, wherein

The photopolymer film is located between two carriers;

The positions of the light in-coupling area and the light out-coupling area are respectively provided with a grating structure; wherein, the liquid crystal display device comprises a liquid crystal display device,

the photopolymer film is derived from a photopolymer composition, wherein the photopolymer composition comprises the following components:

polymerizing a reactive monomer;

a dye compound;

an initiator;

a film-forming component; and

a plasticizer;

wherein the refractive index difference (n _{Polymerization of reactive monomers} -n _{Film-forming component} ) A value above 0.075;

the polymerization active monomer is selected from one or more of acrylic ester monomers and epoxy compound monomers;

the acrylic monomer comprises an acrylic monomer with one or more functional groups,

the acrylate monomer with one functional group comprises a monomer with the following general formula (I-1) or (I-2):

Ar-L-(X-O) _n -C(O)-CH＝C(R ₁ ) ₂ (I-1)

Ar-L-(X-O) _n -C(O)-C(CH ₃ )＝C(R ₁ ) ₂ (I-2)

wherein Ar represents a group containing one or more aromatic groups; l represents an oxygen atom or a sulfur atom; x represents a linear or branched alkyl group having 1 to 6 carbon atoms; n represents an integer of 1 to 5; r is R ₁ Each occurrence, same or different, independently represents a hydrogen or halogen atom;

the acrylic monomer with multiple functional groups comprises a monomer with the following general formula (II-1) or (II-2):

wherein R is ₁ X, L are as defined in the above (I-1) and (I-2), n represents an integer of 1 to 5, and Z represents a group containing one or more aromatic groups;

the epoxy compound monomer has a structure shown in the following general formula (III):

wherein E represents an epoxy-containing group, each E group containing 1 or 2 epoxy groups;

n represents the number of E groups, and n is an integer of 0 to 4;

each Ar is provided with ₁ Identical or different, independently represent aryl-containing groups;

R ₃ 、R ₄ the same or different, each occurrence independently represents a hydrogen atom, an aryl group having 6 to 30 carbon atoms, or an alkyl or alkoxy group having 1 to 10 carbon atoms.

2. The reflective diffractive optical waveguide element according to claim 1, characterized in that the photopolymer film has a thickness of 5 μm to 50 μm.

3. The reflective diffractive optical waveguide element according to claim 1 or 2, characterized in that the shortest distance between the light incoupling region and the light outcoupling region is 10mm-10cm.

4. The reflective diffraction optical waveguide element according to claim 1 or 2, wherein the thickness of the carrier is 1.5mm or less and the refractive index is 1.4 to 1.6.

5. A method of making a reflective diffractive optical waveguide element comprising the steps of:

a step of preparing a photopolymer film;

a step of compounding and molding the support and the photopolymer film;

grating structures are respectively formed in the light in-coupling region and the light out-coupling region;

the photopolymer film is the photopolymer film of any one of claims 1-4.

6. The method of manufacturing a reflective diffractive optical waveguide element according to claim 5, characterized in that in the step of forming a grating structure, a step of exposing the light incoupling region and the light outcoupling region with coherent light is included.

7. The method of manufacturing a reflective diffractive optical waveguide element according to claim 6, wherein the coherent light is coherent light having a wavelength of around 532 nm.

8. Holographic optical waveguide display device, characterized in that it comprises one or more reflective diffractive optical waveguide elements according to any of claims 1-4 or obtainable by a method according to any of claims 5-7.