Optical element, optical component using the optical element, and apparatus

Abstract

The present invention provides an optical element that can increase the diffraction angle while suppressing light leakage from oblique directions. [Solution] The device has a first surface and a second surface opposite to the first surface, and has a first birefringence layer and a second birefringence layer in this order from the first surface toward the second surface, the first birefringence layer has a plurality of first orientation regions along a predetermined direction in the surface in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees, the second birefringence layer has a plurality of second orientation regions along a predetermined direction in the surface in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees, and when the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees in the first birefringence layer is defined as P1, at least some of the P1 of the first orientation regions show a different value from the P1 of other first orientation regions, and P1 is the shortest value of the plurality of first orientation regions. min An optical element in which the [nm] and the thickness d[nm] of the first birefringence layer satisfy a predetermined relationship.

Description

Technical Field

[0001] The present disclosure relates to an optical element, an optical member, and a device using the optical element.

Background Art

[0002] <--0000080-->There is a technical field in which optical elements are used to change the polarization state of light or the traveling direction of light.

[0003] The above-described optical element is used, for example, in a dimming device. In recent years, in personal authentication and vehicle autonomous driving, the development of devices equipped with optical sensors has been progressing. Examples of devices equipped with optical sensors include face recognition devices, LiDAR (light detection and ranging), and the like. In such devices equipped with optical sensors, optical elements may also be used. In recent years, display devices for displaying virtual reality (VR: Virtual Reality), augmented reality (AR: Augmented Reality), and mixed reality (MR: Mixed Reality) have been released. In this specification, the technology of displaying things that do not exist in reality such as VR, AR, and MR is referred to as "cross-reality (XR: X Reality)". In display devices for cross-reality, display elements may also be used.

[0004] Among the above-described optical elements, there are optical elements that utilize light diffraction. In optical elements that utilize light diffraction, optical elements in which a plurality of birefringence layers having a diffraction effect are stacked have been proposed (Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0005] <00C0095>

Patent Document 1

Patent Document 2

[0006] Optical elements with multiple stacked birefringence layers exhibiting diffraction properties, as described in Patent Documents 1 and 2, can achieve a larger diffraction angle compared to cases with a single birefringence layer. However, devices equipped with optical elements with multiple stacked birefringence layers exhibiting diffraction properties frequently suffer from problems such as reduced contrast and the occurrence of double images. [Means for solving the problem]

[0007] The inventors diligently studied to solve the aforementioned problems. They identified that the cause of the problems is that when a birefringence layer has orientation regions with different orientation pitches of liquid crystal molecules, light is not diffracted properly and light leakage tends to increase. In this specification, "orientation pitch" means "the length over which the arrangement direction of liquid crystal molecules changes in steps of 180 degrees." As a result of further investigation, the inventors discovered that the above problem can be solved by setting a specific relationship between the orientation pitch and thickness of the liquid crystal molecules in the birefringence layer.

[0008] This disclosure is as follows: <1> ~ <3> The present invention provides an optical element, an optical member using the optical element, and an apparatus. <1> An optical element, The optical element has a first surface and a second surface opposite to the first surface, and has a first birefringence layer and a second birefringence layer in this order from the first surface toward the second surface. The first birefringence layer and the second birefringence layer each have an in-plane phase difference of (λ1 / 2) × 0.95 or more and (λ1 / 2) × 1.05 or less when the wavelength λ1 is 635 nm or 1550 nm. The first birefringence layer and the second birefringence layer each include one or more liquid crystal layers in the thickness direction. The first birefringence layer has a plurality of first orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. The second birefringence layer has a plurality of second orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. In the first birefringence layer, when P1 is defined as the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, at least a portion of the first orientation region's P1 shows a different value from the other first orientation regions' P1. The value of P1 is the shortest of the multiple first orientation regions. min An optical element that satisfies the following equation 1, given that the first birefringence layer has a refractive index of [nm] and the thickness of the first birefringence layer is defined as d[nm]. asin(λ1 / P1 min ) <atan(P1 min / d) Formula 1 [In Equation 1, "λ1" is at least one of the wavelengths 635 nm and 1550 nm that satisfies the range of the in-plane phase difference.] <2> <1> An optical component comprising the optical element described above and a substrate to be attached, laminated together. <3> <1> An apparatus including the optical elements described above. [Effects of the Invention]

[0009] The optical element and apparatus including the optical element of this disclosure can increase the diffraction angle and suppress light leakage. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view showing one embodiment of the optical element of the present disclosure. [Figure 2] This is a schematic plan view illustrating the state of the first and second birefringence layers. [Figure 3] This is a schematic plan view illustrating the alignment direction of liquid crystal molecules in the first and second birefringence layers. [Figure 4]This is a schematic planar diagram showing the state in which liquid crystal molecules are arranged radially in multiple directions within the plane of a birefringence layer. [Figure 5] This is a plan view showing one embodiment of the arrangement pattern of recesses in a pattern layer, which is one embodiment of the orientation layer. [Figure 6] This is a schematic diagram illustrating the method for measuring light leakage. [Figure 7] This is a diagram illustrating Equation 1 of the optical element in this disclosure. [Modes for carrying out the invention]

[0011] The following describes embodiments of the optical element, the apparatus including the optical element, and the method for manufacturing the optical element according to this disclosure.

[0012] [Optical elements] The optical elements disclosed herein are It has a first surface and a second surface opposite to the first surface, and has a first birefringence layer and a second birefringence layer in this order from the first surface toward the second surface. The first birefringence layer and the second birefringence layer each have an in-plane phase difference of (λ1 / 2) × 0.95 or more and (λ1 / 2) × 1.05 or less when the wavelength λ1 is 635 nm or 1550 nm. The first birefringence layer and the second birefringence layer each include one or more liquid crystal layers in the thickness direction. The first birefringence layer has a plurality of first orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. The second birefringence layer has a plurality of second orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. In the first birefringence layer, when P1 is defined as the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, at least a portion of the first orientation region's P1 shows a different value from the other first orientation regions' P1. The value of P1 is the shortest of the multiple first orientation regions. minWhen the thickness of the first birefringence layer is defined as [nm] and d[nm], the following equation 1 is satisfied. asin(λ1 / P1 min ) <atan(P1 min / d) Formula 1 [In Equation 1, "λ1" is at least one of the wavelengths 635 nm and 1550 nm that satisfies the range of the in-plane phase difference.]

[0013] In this specification, "asin" means "arcsin," which is the inverse trigonometric function of sin, and "atan" means "arctan," which is the inverse trigonometric function of tan.

[0014] Figure 1 is a cross-sectional view showing one embodiment of the optical element of the present disclosure. The optical element 100 in Figure 1 has a first surface 10a and a second surface 10b opposite to the first surface, and has a first birefringence layer 31 and a second birefringence layer 32 in that order from the first surface 10a toward the second surface 10b. In Figure 1, the first birefringence layer 31 has a liquid crystal layer 31r. In Figure 1, the second birefringence layer 32 has a liquid crystal layer 32r. The optical element 100 in Figure 1 has a first alignment layer 21 and a first substrate 11 on the first surface 10a side of the first birefringence layer 31, and a second alignment layer 22 and a second substrate 12 on the second surface 10b side of the second birefringence layer 32. The optical element 100 in Figure 1 has an adhesive layer 41 between the first birefringence layer 31 and the second birefringence layer 32. In Figure 1, the optical element 100 has layers from the first surface 10a to the second surface 10b that are tightly packed and integrated. Figure 1 is a schematic cross-sectional view. That is, the scale of each layer constituting the optical element 100 is a schematic representation for ease of illustration and differs from the actual scale. The same applies to the other figures.

[0015] Figure 2 is a schematic plan view illustrating the state of the first birefringence layer and the second birefringence layer. To facilitate the explanation of the state of the first birefringence layer 31 and the second birefringence layer 32, Figure 2 separates the first birefringence layer 31 and the second birefringence layer 32, and also shifts the two layers in the XY plane. In Figure 2, reference numeral 31a indicates the alignment direction of liquid crystal molecules in the plane of the first birefringence layer 31, and reference numeral 32a indicates the alignment direction of liquid crystal molecules in the plane of the second birefringence layer 32. In Figure 2, the first birefringence layer 31 has a first orientation region in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along the X-axis direction in the XY plane. In Figure 2, the second birefringence layer 32 has a second orientation region in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along the X-axis direction in the XY plane. In Figure 2, the symbols P1 and P2 indicate the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, respectively. In Figure 2, for simplification, there is only one orientation region in the X-axis direction in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, but the optical element of this disclosure has multiple such orientation regions in a predetermined direction.

[0016] Figure 3(a) is a schematic plan view illustrating the alignment direction of liquid crystal molecules in the first birefringence layer. Figure 3(b) is a schematic plan view illustrating the alignment direction of liquid crystal molecules in the second birefringence layer. In Figure 3(a), reference numeral 31a indicates the alignment direction of liquid crystal molecules in the plane of the first birefringence layer 31. In Figure 3(b), reference numeral 32a indicates the alignment direction of liquid crystal molecules in the plane of the second birefringence layer 32. In Figure 3(a), the first birefringence layer 31 has multiple first orientation regions along the X-axis in the XY plane where the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. In Figure 3(a), the symbols P1-1 to P1-5 indicate the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, respectively. The lengths of P1-1, P1-2, and P1-3 are different from the lengths of P1-4 and P1-5. That is, in Figure 3(a), the P1 of at least some of the first orientation regions of the first birefringence layer shows a different value from the P1 of other first orientation regions. In Figure 3(b), the second birefringence layer 32 has multiple second orientation regions along the X-axis in the XY plane where the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. In Figure 3(b), the symbols P2-1 to P2-5 indicate the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, respectively. The lengths of P2-1, P2-2, and P2-3 are different from the lengths of P2-4 and P2-5. That is, in Figure 3(b), the P2 of at least some of the second orientation regions of the second birefringence layer shows a different value from the P2 of other second orientation regions.

[0017] <Layered structure> The optical element of this disclosure has a first surface and a second surface opposite to the first surface. The first surface means one surface in the thickness direction of the optical element, and the second surface means the other surface in the thickness direction of the optical element. The optical element of this disclosure is required to have a first birefringence layer and a second birefringence layer in this order, from the first surface toward the second surface.

[0018] The optical element of this disclosure may have layers other than the first birefringence layer and the second birefringence layer. Examples of other layers include the first substrate, the first alignment layer, the adhesive layer, the second substrate, and the second alignment layer. Other examples of other layers include phase difference layers such as the positive A layer, negative A layer, positive B layer, negative B layer, and positive C layer. Other examples of other layers include birefringence layers other than the first birefringence layer and the second birefringence layer, such as the third birefringence layer.

[0019] In the optical element of this disclosure, it is preferable that each layer from the first surface to the second surface is in close contact and integrated. In the integrated configuration described above, it is preferable to have an adhesive layer between the first birefringence layer and the second birefringence layer.

[0020] The laminated configurations of the optical element of this disclosure include the following (1) to (10). The order in which the layers are described in (1) to (10) below refers to the order of the layers from the first surface to the second surface. In the optical element of this disclosure, the layers from the first surface to the second surface do not have to be in close contact, but it is preferable that the layers from the first surface to the second surface are in close contact and integrated. The laminated configurations of the optical element of this disclosure are not limited to the following (1) to (10). For example, in (1) to (10) below, there may be one or more adhesive layers between the layers from the first surface to the second surface. Also, in (1) to (10) below, there may be a primer layer between the substrate, such as the first substrate, and the orientation layer, such as the first orientation layer. Laminated structures that do not have substrates such as (1) and (8) below are preferred because they allow for thinning of the optical element and are less susceptible to the influence of the substrate's inherent phase difference. (1) First birefringence layer, second birefringence layer (2) First substrate, first birefringence layer, second birefringence layer, second substrate (3) First substrate, first orientation layer, first birefringence layer, second birefringence layer, second orientation layer, second substrate (4) First substrate, first birefringence layer, second substrate, second birefringence layer (5) First substrate, first orientation layer, first birefringence layer, second substrate, second orientation layer, second birefringence layer (6) First birefringence layer, first substrate, second substrate, second birefringence layer (7) First birefringence layer, first orientation layer, first substrate, second substrate, second orientation layer, second birefringence layer (8) First birefringence layer, second birefringence layer, third birefringence layer (9) First substrate, first orientation layer, first birefringence layer, second substrate, second orientation layer, second birefringence layer, third birefringence layer, third orientation layer, third substrate (10) First substrate, first orientation layer, first birefringence layer, second birefringence layer, second orientation layer, second substrate, third birefringence layer, third orientation layer, third substrate

[0021] In the optical element of this disclosure, the first birefringence layer and the second birefringence layer are required to have an in-plane phase difference of (λ1 / 2) × 0.95 or more and (λ1 / 2) × 1.05 or less when the wavelength λ1 is 635 nm or 1550 nm, respectively. In other words, the first birefringence layer and the second birefringence layer must satisfy at least one of the following in-plane phase differences (1) and (2). (1) The in-plane phase difference at a wavelength of 635 nm is between 301.625 nm and 333.375 nm. (2) The in-plane phase difference at a wavelength of 1550 nm is between 736.25 nm and 813.75 nm.

[0022] 635nm is a typical wavelength for red lasers, and 1550nm is a typical wavelength for infrared lasers.

[0023] By setting the in-plane phase difference between the first birefringence layer and the second birefringence layer to the above range, the optical element can be made more likely to perform the functions (X1) to (X2) described later.

[0024] The in-plane phase difference between the first birefringence layer and the second birefringence layer is preferably (λ1 / 2) × 0.97 or more and (λ1 / 2) × 1.03 or less, and more preferably (λ1 / 2) × 0.99 or more and (λ1 / 2) × 1.01 or less (λ1 is 635 nm or 1550 nm).

[0025] When the wavelength λ1 is 635 nm, it is preferable that the in-plane phase difference between the first birefringence layer and the second birefringence layer is within the aforementioned range. Furthermore, it is preferable that the in-plane phase difference between the first birefringence layer and the second birefringence layer is also within the aforementioned range when the wavelength λ1 is 450 nm and 532 nm. By satisfying the above configuration, it is possible to easily exhibit the functions (X1) to (X2) described later over a wide band of visible light wavelengths.

[0026] In order to make it easier to set the in-plane phase difference range to (λ¹ / ²) × 0.95 or more and (λ¹ / ²) × 1.05 or less over a wide wavelength range (broadband), it is preferable that the first birefringence layer and the second birefringence layer satisfy the configuration of (1) or (2) below. (1) The first birefringence layer and the second birefringence layer exhibit negative wavelength dispersion in the entire visible light region. (2) The first birefringence layer and the second birefringence layer are each configured to include two or more liquid crystal layers in the thickness direction. Further, in at least one liquid crystal layer, the liquid crystal molecules are configured to be helically oriented in the thickness direction of the liquid crystal layer (a liquid crystal layer in which the liquid crystal molecules are helically oriented and a liquid crystal layer in which the liquid crystal molecules are not helically oriented may be combined). Further, at least one of the thickness of the liquid crystal layer and the period (twist angle) of the helix of the liquid crystal layer is made different for each liquid crystal layer. In the first birefringence layer and the second birefringence layer, the number of liquid crystal layers in the thickness direction is preferably 2 or more and 5 or less, and more preferably 3 or more and 4 or less.

[0027] Negative wavelength dispersion is a characteristic in which the phase difference imparted to the transmitted light increases as the wavelength of the transmitted light becomes longer. Positive wavelength dispersion is a characteristic in which the phase difference imparted to the transmitted light decreases as the wavelength of the transmitted light becomes longer. In this specification, when the in-plane phase difference at a wavelength of 450 nm is defined as Re450 and the in-plane phase difference at a wavelength of 550 nm is defined as Re550, the characteristic of Re450 < Re550 is referred to as negative wavelength dispersion. In this specification, the characteristic of Re450 > Re550 is referred to as positive wavelength dispersion. In this specification, the in-plane phase difference is represented by the following formula when the refractive index in the slow axis direction with the highest refractive index in the plane is Nx, the refractive index in the direction orthogonal to the slow axis in the plane is Ny, the refractive index in the thickness direction is Nz, and the thickness of the layer is d (nm). Also, in this specification, the phase difference in the thickness direction is represented by the following formula. In-plane phase difference = (Nx - Ny) × d Phase difference in the thickness direction = ((Nx + Ny) / 2 - Nz) × d

[0028] As described in (2) above, the method of broadening bandwidth using two or more layers is described, for example, in Reference 1 below. Furthermore, as described in "2.2. Theory" of the reference below, the conditions for achieving broadband bandwidth with multiple liquid crystal layers can be simulated by using the standard transfer matrix method. The conditions are the number of liquid crystal layers, the thickness of each liquid crystal layer, and the period (twist angle) of the helix of each liquid crystal layer. In other words, the conditions for the number of liquid crystal layers, the thickness of each liquid crystal layer, and the period (twist angle) of the helix of each liquid crystal layer required to make the phase difference of the birefringence layer λ / 2 in the desired wavelength range can be determined by simulation. Reference 1: Ravi K. Komanduri, Kristopher F. Lawler, and Michael J. Escuti, “Multi-twist retarders: broadband retardation control using self-aligning reactive liquid crystal layers,” OPTICS EXPRESS 404, USA, Optica, January 14, 2013, Vol. 21, No. 1

[0029] In the optical element of this disclosure, the first birefringence layer and the second birefringence layer each must include one or more liquid crystal layers in the thickness direction. By having a liquid crystal layer in the first birefringence layer, the in-plane phase difference of the first birefringence layer can be set to the above range, and a first orientation region can be easily formed in the first birefringence layer. By having a liquid crystal layer in the second birefringence layer, the in-plane phase difference of the second birefringence layer can be set to the above range, and a second orientation region can be easily formed in the second birefringence layer. In the first and second birefringence layers, the number of liquid crystal layers in the thickness direction may be only one or two or more. In order to make it easier to set the in-plane phase difference range to (λ¹ / ²) × 0.95 or more and (λ¹ / ²) × 1.05 or less over a wide bandwidth, it is preferable to have two or more liquid crystal layers in the thickness direction in the first and second birefringence layers, more preferably two or more and five or less, and even more preferably three or more and four or less.

[0030] In the first and second birefringence layers, if the number of liquid crystal layers in the thickness direction is two or more, each liquid crystal layer must be in contact with each other in the thickness direction. By forming two or more liquid crystal layers continuously so that they are in contact with each other in the thickness direction, the orientation of the liquid crystal molecules can be matched at the interface of the liquid crystal layers that are in contact with each other. As a result, each liquid crystal layer will have a substantially common orientation region. The first and second birefringence layers have two or more liquid crystal layers in the thickness direction, which makes it easier for them to exhibit the functions (X1) to (X2) described later over a wide wavelength range.

[0031] In the optical element of this disclosure, the first birefringence layer and the second birefringence layer each have a plurality of orientation regions along a predetermined in-plane direction in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. The first birefringence layer and the second birefringence layer having the above-described configuration each have the effect of diffracting light. Therefore, the optical element of this disclosure can increase the diffraction angle. Furthermore, in the first birefringence layer of the optical element of this disclosure, when P1 is defined as the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, at least a portion of the P1 of the first orientation region exhibits a different value from the P1 of other first orientation regions. In other words, the optical element of this disclosure has orientation regions with different orientation pitches within the first birefringence layer. Therefore, the optical element of this disclosure can be given different diffraction angles at different locations within the plane of the optical element. However, devices equipped with optical elements consisting of multiple stacked birefringent layers that exhibit diffraction properties sometimes suffered from problems such as reduced contrast or the appearance of double images. The inventors diligently studied how to solve these problems. They identified that the cause of the problems was that when the birefringent layers had orientation regions with different orientation pitches, light was not properly diffracted, leading to increased light leakage. As a result of further investigation, the inventors discovered that the problems could be solved by adjusting the orientation pitch and thickness of the birefringent layers to satisfy the relationship in Equation 1. Generally, the term "direction" simply means a straight-line state, such as the vertical direction or the horizontal direction. In this specification, an "alignment region where the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined direction in the plane" can be rephrased as "an alignment region where the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined straight-line direction in the plane".

[0032] The following formula A is a formula showing the relationship of the diffraction angle θ of light incident perpendicular to the birefringent layer. In the following formula A, "λ" represents the wavelength [nm] of the incident light, and "P" represents the length [nm] until the alignment direction of the liquid crystal molecules in the birefringent layer changes by 180 degrees. Psinθ = λ Formula A When formula A is transformed, it becomes sinθ = λ / P. Further transformation gives θ = asin(λ / P). That is, the diffraction angle θ of light incident perpendicular to the birefringent layer can be calculated by asin(λ / P). "λ1" in formula 1 means at least one of the wavelengths of 635 nm and 1550 nm that satisfies the range of the in-plane phase difference. Therefore, "asin(λ1 / P" on the left side of formula 1 min ) corresponds to the diffraction angle of light with a wavelength of 635 nm or 1550 nm incident perpendicular to the region where the alignment pitch of the first birefringent layer is the shortest. On the other hand, "atan(P1" on the right side of formula 1 min / d)" corresponds to the angle formed by the diagonal line of the vertical cross-section in the thickness direction of the region where the alignment pitch of the first birefringent layer is the shortest and the perpendicular line to the plane direction of the first birefringent layer. Hereinafter, the reason why light leakage can be suppressed by satisfying formula 1 will be specifically explained using FIGS. 7(a) and (b). FIGS. 7(a) and (b) are schematic views of the vertical cross-section in the thickness direction of the first birefringent layer 31. In FIGS. 7(a) and (b), P1 min indicates the region where the alignment pitch is the shortest, P1 n is P1 min where the alignment pitch is longer than P1 min and indicates a region where the alignment pitch is different from P1 A In FIGS. 7(a) and (b), θ min corresponds to "asin(λ1 / P1 B ) and θ minThis corresponds to / d). In Figures 7(a) and (b), the dashed-dotted arrows indicate the diagonals of the cross-section in the thickness direction of the region with the shortest orientation pitch of the first birefringence layer, and the double-dotted arrows indicate the diffraction direction of light incident perpendicularly to the region with the shortest orientation pitch of the first birefringence layer. atan(P1 min / d) is better than asin(λ1 / P1 min If ) is larger, then as shown in Figure 7(a), the orientation pitch P1 min Light incident on this region and diffracted will enter regions with different orientation pitches (orientation pitch P1 min The light penetrates into the region shown in Figure 7(a). As shown in Figure 7(a), when diffracted light penetrates into regions with different orientation pitches, a shift in the phase difference of the diffracted light occurs, making it easier for the light to leak out. On the other hand, atan(P1 min / d) is better than asin(λ1 / P1 min If ) is smaller, the orientation pitch P1 min Light incident on this region and diffracted will enter regions with different orientation pitches (orientation pitch P1 min It is difficult for the diffracted light to penetrate into the region (of which the light is diffracted). As shown in Figure 7(b), by making it difficult for the diffracted light to penetrate into regions with different orientation pitches, it is possible to suppress the shift in the phase difference of the diffracted light, thus making it easier to suppress light leakage.

[0033] As mentioned above, 635 nm is a typical wavelength for red lasers. When the laser wavelength is blue or green, the wavelength becomes shorter. Therefore, the value on the left side of Equation 1 is smaller when λ1 is a blue or green wavelength than when λ1 is 635 nm. In other words, even if "λ1" on the left side of Equation 1 is changed from 635 nm to a blue or green wavelength, the relative magnitudes of the left and right sides of Equation 1 do not change. Therefore, if Equation 1 is satisfied when the wavelength λ1 is 635 nm, it will also be satisfied at blue and green wavelengths, so light leakage can be suppressed even when using blue and green lasers. Equation 1 shows the region with the shortest orientation pitch, "P1 min It specifies the following regarding "P1" in Equation 1. minIf "P1" is changed to a larger value, the value on the left side of Equation 1 will decrease, and the value on the right side of Equation 1 will increase. That is, if "P1" in Equation 1 is changed to a larger value, the value on the left side of Equation 1 will decrease, and the value on the right side of Equation 1 will increase. min Even if the value of " is changed to a large value, the relative magnitudes of the left and right sides of Equation 1 do not change. Therefore, if Equation 1 is satisfied, light leakage of light incident on the region with a long orientation pitch can also be suppressed.

[0034] The length of time it takes for the alignment direction of liquid crystal molecules to change stepwise by 180 degrees in the first to third birefringence layers, and the thickness of the first to third birefringence layers, can be measured using the method described later.

[0035] atan(P1 min / d)-asin(λ1 / P1 min The temperature is preferably 0.01 degrees or more and 89.95 degrees or less, more preferably greater than 0.05 degrees and 75.00 degrees or less, and even more preferably greater than 0.10 degrees and 50.00 degrees or less. atan(P1 min / d)-asin(λ1 / P1 min By setting the angle to 0.01 degrees or higher, light leakage can be more easily suppressed. min / d)-asin(λ1 / P1 min By setting the temperature to 89.95 degrees or less, the thickness of the first birefringence layer can be easily reduced.

[0036] In the first birefringence layer, d / P1 min It is preferably 0.40 to 2.90, more preferably 0.45 to 2.80, and even more preferably 0.50 to 2.80. d / P1 min By setting the range as described above, light leakage can be more easily suppressed.

[0037] P1 min A smaller value of P1 makes it easier to increase the diffraction angle. min The wavelength is preferably 4000 nm or less, more preferably 3000 nm or less, and even more preferably 2000 nm or less. Meanwhile, P1 minIf the value of is too small, P1 min In the region, liquid crystal molecules may have difficulty aligning. However, P1 min Even if the value of is small, the orientation of liquid crystal molecules can be improved by stacking thin films. Also, P1 min If the value of is too small, the value of d required to satisfy Equation 1 becomes small, which can make it difficult to impart a predetermined in-plane phase difference to the first birefringence layer. However, if a liquid crystal material with high birefringence is used, a predetermined in-plane phase difference can be imparted to the first birefringence layer even if the value of d is small. For this reason, P1 min The lower limit is not particularly limited, but it is preferably 200 nm or more, more preferably 300 nm or more, and even more preferably 400 nm or more.

[0038] In the constituent elements described herein, if multiple options are provided for both the upper and lower limits of a numerical value, the description shall refer to embodiments within a range that combines one selected from the upper limits and one selected from the lower limits. For example, P1 above min Examples of the range embodiments include 200 nm to 4000 nm, 200 nm to 3000 nm, 200 nm to 2000 nm, 300 nm to 4000 nm, 300 nm to 3000 nm, 300 nm to 2000 nm, 400 nm to 4000 nm, 400 nm to 3000 nm, and 400 nm to 2000 nm.

[0039] The thickness d of the first birefringence layer is not particularly limited as long as it satisfies Equation 1, but is preferably 1000 nm or more and 7000 nm or less, more preferably 1250 nm or more and 6500 nm or less, and even more preferably 1500 nm or more and 6000 nm or less.

[0040] <Birefringence layer> The optical element of this disclosure has a first birefringence layer and a second birefringence layer in this order, from the first surface toward the second surface. Having a first birefringence layer and a second birefringence layer allows for a larger diffraction angle compared to the case where the birefringence layer is a single layer. Even with a single birefringence layer, the diffraction angle can be increased by shortening the orientation pitch. However, shortening the orientation pitch too much may reduce the orientation of the liquid crystal molecules.

[0041] The first birefringence layer must have multiple orientation regions in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined direction in the plane. The second birefringence layer must have multiple orientation regions in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined direction in the plane. The first and second birefringence layers have orientation regions in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined direction in the plane, thereby enabling them to perform the following functions (X1) to (X2), respectively. (X1) A function that diffracts the incident light and reverses the phase of the incident light when circularly polarized light is incident on it. (X2) A function that diffracts the incident light when natural light or linearly polarized light is incident on it, and separates it into right-circularly polarized and left-circularly polarized light.

[0042] The direction of the slow axis and / or the fast axis of a birefringent layer varies along the alignment direction of the liquid crystal molecules. Therefore, a birefringent layer having an orientation region in which the direction of the slow axis and / or the fast axis changes stepwise by 180 degrees along a predetermined direction in the plane can be said to have an orientation region in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined direction in the plane. Thus, whether or not a birefringent layer has an orientation region in which the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees along a predetermined direction in the plane can be determined by measuring the direction of the slow axis and / or the fast axis. An example of a device capable of measuring the direction of the slow axis and / or the fast axis of a birefringence layer is the 2D birefringence evaluation system (product name: WPA-Micro) from Photonic Lattice. In this specification, the slow axis refers to the direction in which the refractive index is greatest within the plane, and the fast axis refers to the direction in which the phase-advancing axis is perpendicular to the slow axis within the plane.

[0043] The diffraction angle θ can be expressed by the following formula, where x [nm] is the length until the alignment direction of the liquid crystal molecules in the birefringence layer changes by 180 degrees, λ [nm] is the wavelength of light, and θ0 is the angle of incidence of the light. θ and θ0 are angles when the direction perpendicular to the plane of the birefringence layer is defined as 0 degrees. In the following formula, θ0 is the case when it is in the positive direction from the aforementioned perpendicular direction. The ± sign is added because, depending on the rotation direction of the incident circularly polarized light, diffraction can occur in either the positive or negative direction relative to the aforementioned perpendicular direction. sinθ = ±(λ / x) + sinθ 0

[0044] For example, if the incident angle θ0 is fixed at 0 degrees and the wavelength of light at 1550 nm, the relationship between the orientation pitch (the length required for the alignment direction of liquid crystal molecules to change by 180 degrees) and the diffraction angle is as shown in Table 1 below. [Table 1]

[0045] The diffraction angles in Table 1 are for the case where there is a single birefringence layer. If the polarization state is the same, increasing the number of birefringence layers increases the diffraction angle by a multiplier of the number of birefringence layers. If the diffraction angle at an arbitrary orientation pitch is θ (degrees) and the number of birefringence layers is n, then the diffraction angle is 2 n-1 It can be expressed as ×θ (degrees).

[0046] In regions where the alignment direction of liquid crystal molecules in birefringence layers such as the first and second birefringence layers changes by 180 degrees in steps, the liquid crystal molecules may be arranged linearly, semicircularly, or in an arc shape. In Figures 2 and 3, the liquid crystal molecules are arranged in an arc shape.

[0047] The first birefringence layer has multiple orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes in steps by 180 degrees. The predetermined direction of the first birefringence layer may be a specific one direction of the first birefringence layer. That is, the first birefringence layer may have multiple orientation regions along a specific one direction in the plane in which the alignment direction of liquid crystal molecules changes in steps by 180 degrees. In Figure 3(a), there are multiple orientation regions along the X-axis direction in the XY plane in which the alignment direction of liquid crystal molecules changes in steps by 180 degrees. The second birefringence layer has multiple orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes in steps by 180 degrees. The predetermined direction of the second birefringence layer may be a specific one direction of the second birefringence layer. That is, the second birefringence layer may have multiple orientation regions along a specific one direction in the plane in which the alignment direction of liquid crystal molecules changes in steps by 180 degrees. In Figure 3(b), there are multiple orientation regions along the X-axis direction in the XY plane in which the alignment direction of liquid crystal molecules changes in steps by 180 degrees.

[0048] In the birefringence layers, such as the first birefringence layer and the second birefringence layer, the alignment region is formed by a liquid crystal layer. When the first birefringence layer and the second birefringence layer each contain one liquid crystal layer in the thickness direction, the alignment region is formed in one liquid crystal layer. When one liquid crystal layer is formed in contact with another liquid crystal layer that has an alignment region, the other liquid crystal layer will have an alignment region that reflects the alignment region of the underlying liquid crystal layer. Therefore, when two or more liquid crystal layers are formed in a continuous manner so that they are in contact with each other, a substantially common alignment region will be formed in the two or more liquid crystal layers.

[0049] As shown in Figure 3(a), the first birefringence layer may have spacing between the reference numerals 31a indicating the alignment direction of liquid crystal molecules within the plane of the first birefringence layer 31, but it may not have such spacing. As shown in Figure 3(b), the second birefringence layer may have spacing between the reference numerals 32a indicating the alignment direction of liquid crystal molecules in the plane of the first birefringence layer 31, but it may not have such spacing.

[0050] In the second birefringence layer, when P2 is defined as the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, the P2 of at least some of the second orientation regions may show a different value from the P2 of other second orientation regions. On the other hand, the second birefringence layer may have multiple second orientation regions P2 that are all the same.

[0051] The optical element of this disclosure may have the following configuration 1. 《Structure 1》 The predetermined direction of the first birefringence layer is a specific one direction of the first birefringence layer, the predetermined direction of the second birefringence layer is a specific one direction of the second birefringence layer, and the specific one direction of the first birefringence layer and the specific one direction of the second birefringence layer are substantially the same direction.

[0052] By providing the above configuration 1, it is possible to easily increase the diffraction angle of the optical element. In the above configuration 1, "approximately the same direction" means that the angle between the specific direction of the first birefringence layer and the specific direction of the second birefringence layer is 1.0 degree or less, preferably 0.7 degrees or less, and more preferably 0.5 degrees or less. In Figure 3(a), the predetermined direction of the first birefringence layer is a specific one direction along the X-axis in Figure 3(a). In Figure 3(b), the predetermined direction of the second birefringence layer is a specific one direction along the X-axis in Figure 3(b). That is, the first birefringence layer in Figure 3(a) and the second birefringence layer in Figure 3(b) have the same specific one direction.

[0053] In the configuration 1 described above, where the liquid crystal molecules of the first birefringence layer and the second birefringence layer are arranged in a semicircular or arc shape, it is preferable that the orientation of the semicircle or arc of the first birefringence layer differs from the orientation of the semicircle or arc of the second birefringence layer by 180 degrees. For example, in Figure 2, the arc of the first birefringence layer 31 is convex downwards, and the arc of the second birefringence layer 32 is convex upwards, so the orientation of the arc of the first birefringence layer differs from the orientation of the arc of the second birefringence layer by 180 degrees. By making the orientation of the semicircle or arc of the first birefringence layer differ from the orientation of the semicircle or arc of the second birefringence layer by 180 degrees, the diffraction angle can be easily widened. If the optical element of this disclosure further has a third birefringence layer, it is preferable that the orientation of the semicircle or arc of the second birefringence layer differs from the orientation of the semicircle or arc of the third birefringence layer by 180 degrees.

[0054] The optical element of this disclosure may have the following configuration 2. When the optical element has configuration 2, it is preferable that it also has configuration 1. 《Structure 2》 In the first birefringence layer, the first orientation region P1 becomes progressively shorter from the first orientation region at one end in a specific direction toward the first orientation region at the other end in the specific direction. In the second birefringence layer, when P2 is defined as the length until the alignment direction of the liquid crystal molecules changes by 180 degrees in steps, the length of the second orientation region P2 gradually shortens from the second orientation region at one end of the specific direction toward the second orientation region at the other end of the specific direction.

[0055] In Figure 3(a), the labels P1-1 to P1-5 represent the lengths until the alignment direction of the liquid crystal molecules in the first birefringence layer changes by 180 degrees in steps. In Figure 3(a), the lengths of labels P1-1 to P1-3 are the same, the lengths of labels P1-4 to P1-5 are the same, and the lengths of labels P1-1 to P1-3 > the lengths of labels P1-4 to P1-5. Therefore, in Figure 3(a), P1 gradually shortens from the first orientation region at the left end in the X-axis direction to the first orientation region at the right end. In Figure 3(b), the labels P2-1 to P2-5 represent the lengths until the alignment direction of the liquid crystal molecules in the second birefringence layer changes by 180 degrees in steps. In Figure 3(b), the lengths of labels P2-1 to P2-3 are the same, the lengths of labels P2-4 to P2-5 are the same, and the lengths of labels P2-1 to P2-3 > the lengths of labels P2-4 to P2-5. Therefore, in Figure 3(b), P2 decreases in steps from the second orientation region at the left end in the X-axis direction to the second orientation region at the right end.

[0056] By providing the above configuration 2, it is possible to assign different diffraction angles to different locations within the plane of the optical element. In configuration 2, the P1 of the first birefringence layer and the P2 of the second birefringence layer do not necessarily have to be approximately the same, but it is preferable that they be approximately the same. By making P1 and P2 approximately the same, it is possible to facilitate interaction between each birefringence layer. For P1 and P2 to be approximately identical means that P1 / P2 is between 0.97 and 1.03. Preferably, P1 / P2 is between 0.98 and 1.02, and more preferably between 0.99 and 1.01.

[0057] The optical element of this disclosure may have the following configuration 3. 《Structure 3》 The predetermined direction of the first birefringence layer is a multi-directional radial direction with respect to the center of the arrangement pattern of the liquid crystal molecules, and the predetermined direction of the second birefringence layer is a multi-directional radial direction with respect to the center of the arrangement pattern of the liquid crystal molecules.

[0058] Figure 4 is a schematic plan view showing the arrangement of liquid crystal molecules radially in multiple directions within the plane of a birefringence layer. In Figure 4, each line corresponding to reference numeral 31c indicates the orientation of the liquid crystal molecules at each location. In Figure 4, orientation regions in which the orientation of the liquid crystal molecules changes in steps of 180 degrees are present in multiple radial directions relative to the center of the liquid crystal molecule arrangement pattern. For example, along the X-axis, the orientation of the liquid crystal molecules changes in steps of 180 degrees between reference numerals A1 and A2, A2 and A3, B1 and B2, and B2 and B3. Figure 4 corresponds to a schematic plan view of the first birefringence layer and the second birefringence layer satisfying configuration 3.

[0059] In configuration 3, as shown in Figure 4, it is preferable that regions where the alignment direction of liquid crystal molecules is the same are provided concentrically within the planes of the first birefringence layer and the second birefringence layer. In the case of configuration 3, it is preferable that the multi-directional orientations of the first birefringence layer and the multi-directional orientations of the second birefringence layer are substantially the same. Substantially the same orientation means that the angle between the orientation of the first birefringence layer and the orientation of the second birefringence layer is 1.0 degree or less, preferably 0.7 degrees or less, and more preferably 0.5 degrees or less.

[0060] In the case of the above configuration 3, it is preferable that the rotation direction of the liquid crystal molecules along the radial patterns of the first and second birefringence layers be in opposite directions. To explain the rotation direction of the orientation of the liquid crystal molecules, in the radial pattern of Figure 4, the orientation of the liquid crystal molecules rotates counterclockwise in the region from A1 to A2. For example, if the radial pattern of Figure 4 is the radial pattern of the first birefringence layer, it is preferable that the orientation of the liquid crystal molecules rotates clockwise, which is the opposite direction to that in Figure 4, in the region from A1 to A2 of the radial pattern of the second birefringence layer. If the radial pattern of Figure 4 is the radial pattern of the first birefringence layer, by making the radial pattern of the second birefringence layer a mirror image pattern of Figure 4, the rotation direction of the liquid crystal molecules along the radial patterns of the first and second birefringence layers can be made opposite directions for the first and second birefringence layers. By making the rotation directions of the liquid crystal molecules along the radial patterns of the first and second birefringence layers opposite for the first and second birefringence layers, the diffraction angle can be broadened, making it easier to focus or diverge light. If the optical element of this disclosure further has a third birefringence layer, it is preferable that the rotation directions of the liquid crystal molecules along the radial patterns of the second and third birefringence layers are opposite for the second and third birefringence layers.

[0061] The optical element of this disclosure may have the following configuration 4. When the optical element has configuration 4, it is preferable that it also has the configuration 3. 《Structure 4》 In the first birefringence layer, P1 gradually shortens from the first orientation region located at the center of the array pattern toward the first orientation region located outside the array pattern. When P2 is defined as the length in the orientation region of the second birefringence layer until the alignment direction of the liquid crystal molecules changes by 180 degrees in steps, P2 gradually decreases from the second orientation region located at the center of the alignment pattern toward the second orientation region located on the outside of the alignment pattern.

[0062] By providing the above configuration 4, light can be focused or diverged, making it easier to impart a lens function to the optical element. In configuration 4, the first birefringence layer P1 and the second birefringence layer P2 do not necessarily have to be approximately the same, but it is preferable that they be approximately the same. When P1 and P2 are approximately the same, it becomes easier to adjust the lens function. For P1 and P2 to be approximately identical means that P1 / P2 is between 0.97 and 1.03. Preferably, P1 / P2 is between 0.98 and 1.02, and more preferably between 0.99 and 1.01.

[0063] In Figure 4, the intervals between symbols A1 and A2, A2 and A3, B1 and B2, and B2 and B3 indicate the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees. Also, in Figure 4, the interval between symbols A1 and A2 > the interval between symbols A2 and A3, and the interval between symbols B1 and B2 > the interval between symbols B2 and B3. In other words, in the birefringence layer of Figure 4, the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees decreases stepwise from the alignment region located at the center of the alignment pattern to the alignment region located outside the alignment pattern. Therefore, Figure 4 corresponds to a schematic plan view of the first birefringence layer and the second birefringence layer satisfying configuration 4.

[0064] The optical element of this disclosure further has the third birefringence layer, and has the first birefringence layer, the second birefringence layer and the third birefringence layer in this order from the first surface to the second surface, and the third birefringence layer may have a plurality of third orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. By incorporating the above configuration, it becomes easier to increase the diffraction angle.

[0065] In the third birefringence layer, when P3 is defined as the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, the P3 of at least some of the third orientation regions may show a different value from the P3 of other third orientation regions. On the other hand, the third birefringence layer may have multiple third orientation regions P3 that are all the same.

[0066] The optical element of this disclosure may further have a fourth birefringence layer, etc., as a layer having a plurality of orientation regions in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined direction in the plane. Embodiments of the fourth birefringence layer, etc., can be the same as embodiments of the first to third birefringence layers.

[0067] When the first birefringence layer and the second birefringence layer have the configuration 1 described above, the optical element having the third birefringence layer preferably has the following configuration 1'. In configuration 1', substantially the same direction means that the angle between the specific direction of the first birefringence layer and the specific direction of the second birefringence layer, and the angle between the specific direction of the second birefringence layer and the specific direction of the third birefringence layer are 1.0 degree or less, preferably 0.7 degree or less, and more preferably 0.5 degree or less. 《Composition 1'》 The predetermined direction of the third birefringence layer is a specific one direction of the third birefringence layer, and the specific one direction of the first birefringence layer, the specific one direction of the second birefringence layer, and the specific one direction of the third birefringence layer are substantially the same direction.

[0068] When the first birefringence layer and the second birefringence layer have the configuration 2 described above, the optical element having the third birefringence layer preferably has the following configuration 2'. When configuration 2' is included, P1, P2, and P3 do not have to be substantially the same, but it is preferable that they be substantially the same. 《Composition 2'》 When P3 is defined as the length in the third orientation region of the third birefringence layer until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, P3 gradually decreases from the third orientation region at one end of the specific direction toward the third orientation region at the other end of the specific direction.

[0069] When the first birefringence layer and the second birefringence layer have the configuration 3 described above, it is preferable that the optical element having the third birefringence layer has the following configuration 3'. In configuration 3', it is preferable that regions where the alignment direction of liquid crystal molecules is the same are provided concentrically within the plane of the third birefringence layer. When configuration 3' is provided, it is preferable that the multi-directions of the first birefringence layer, the multi-directions of the second birefringence layer, and the multi-directions of the third birefringence layer are substantially the same direction. Substantially the same direction means that the angle between the direction of the first birefringence layer and the direction of the second birefringence layer, and the angle between the direction of the second birefringence layer and the direction of the third birefringence layer are each 1.0 degree or less, preferably 0.7 degrees or less, and more preferably 0.5 degrees or less. 《Composition 3'》 The predetermined direction of the third birefringence layer is a multi-directional radial direction with respect to the center of the arrangement pattern of the liquid crystal molecules.

[0070] When the first birefringence layer and the second birefringence layer have the configuration 4 described above, the optical element having the third birefringence layer preferably has the following configuration 4'. When configuration 4' is included, P1, P2, and P3 do not have to be substantially the same, but it is preferable that they be substantially the same. 《Composition 4'》 When P3 is defined as the length in the third orientation region of the third birefringence layer until the alignment direction of the liquid crystal molecules changes by 180 degrees in steps, P3 gradually decreases from the third orientation region located at the center of the alignment pattern toward the third orientation region located on the outside of the alignment pattern.

[0071] The orientation regions in which the liquid crystal molecules in each birefringence layer change in a stepwise manner, such as the first birefringence layer and the second birefringence layer, or the first birefringence layer, the second birefringence layer, and the third birefringence layer, do not necessarily have to coincide in the planar direction. Even if the orientation regions of each birefringence layer do not coincide in the planar direction, interaction between each birefringence layer can be obtained if the arrangement directions of the liquid crystal molecules in each birefringence layer are substantially the same. Furthermore, by not having the orientation regions of each birefringence layer coincide in the planar direction, moiré patterns can be suppressed. To facilitate the interaction of each birefringence layer, it is preferable that the first birefringence layer and the second birefringence layer, or the first birefringence layer, the second birefringence layer and the third birefringence layer, do not shift their positions too much in the planar direction of the orientation region where the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees. When the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees is defined as the orientation pitch, and the maximum value of the orientation pitch of the multiple birefringence layers included in the optical element is defined as Pmax, it is preferable that the positional shift in the planar direction of the orientation region of the first birefringence layer, the second birefringence layer and the third birefringence layer is less than Pmax, and more preferably less than or equal to Pmax / 2.

[0072] The position in the planar direction of the orientation region of each birefringence layer is determined from the cross-sectional photographs obtained in (B1) to (B4) below. Since the degree of staining of the birefringence layer differs depending on the orientation direction of the liquid crystal molecules, the orientation region of each birefringence layer, such as the first birefringence layer, the second birefringence layer, and the third birefringence layer, can be identified from the cross-sectional photographs obtained in (B1) to (B4) below. In addition, P1 min The orientation pitch of each birefringence layer and the thickness of each birefringence layer can also be determined. In this specification, the thickness of each birefringence layer shall be the average of the thicknesses of any 10 locations in the cross-sectional photographs obtained in (B1) to (B4) below.

[0073] (B1) Prepare cut samples by cutting the optical element into strips. Prepare embedded samples by embedding the cut samples in thermosetting resin. (B2) Using a microtome, ultrathin section samples are prepared by cutting the embedded sample. The cutting is performed so that the cross section perpendicular to the thickness direction of the optical element is exposed. The microtome conditions are set to use a diamond knife and a set section thickness of 80 nm. (B3) The ultrathin section samples are stained by immersing them in osmium tetroxide solution for 30 minutes and then in ruthenium tetroxide solution for 5 minutes. (B4) Observe the stained sample using a scanning transmission electron microscope (STEM) under the following conditions.

[0074] The first, second, and third birefringence layers have multiple orientation regions in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined direction in the plane. The phase difference layers, such as the positive A layer, negative A layer, positive B layer, negative B layer, and positive C layer, described later, differ from the first, second, and third birefringence layers in that they do not have multiple orientation regions in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees along a predetermined direction in the plane.

[0075] In the first, second, and third birefringence layers, the length until the alignment direction of the liquid crystal molecules changes by 180 degrees is not particularly limited. The lower limit of the length is preferably 0.2 μm or more, more preferably 0.8 μm or more, and even more preferably 2.0 μm or more. Setting the length to 0.2 μm or more makes it easier to suppress alignment defects when the alignment layer described later is a pattern layer. The upper limit of the length is preferably 500 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. To make it easier to achieve a visible diffraction angle, the angle is preferably 500 μm or less.

[0076] Materials for the liquid crystal layer Each of the birefringence layers, such as the first birefringence layer, the second birefringence layer, and the third birefringence layer, contains one or more liquid crystal layers in the thickness direction. The liquid crystal compound constituting the liquid crystal layer can be one or more selected from rod-shaped liquid crystal compounds such as nematic liquid crystal compounds and smectic liquid crystal compounds, cholesteric liquid crystal compounds, discotic liquid crystal compounds (disc-shaped liquid crystal compounds), etc. The liquid crystal layer may also contain a chiral agent in addition to the liquid crystal compound. For example, in a liquid crystal layer containing a nematic liquid crystal compound and a chiral agent, the liquid crystal molecules are oriented helically in the thickness direction. When liquid crystal molecules are oriented helically in the thickness direction within a liquid crystal layer, the twist angle of the helix gradually changes in the thickness direction of the liquid crystal molecules. A liquid crystal layer with a helical period of exactly one period will have virtually no in-plane phase difference. The helical period is the period during which the twist angle of the helix changes by 360 degrees in the thickness direction of the liquid crystal layer. Even with liquid crystal layers of the same thickness using the same liquid crystal molecules, the in-plane phase difference can be changed by adjusting the helical period. Even with liquid crystal layers of different thicknesses using the same liquid crystal molecules, the value of the in-plane phase difference can be made the same by adjusting the helical period. The helical period can be adjusted, for example, by the type of chiral agent or the concentration of the chiral agent. For example, increasing the concentration of the chiral agent tends to shorten the helical period.

[0077] The liquid crystal layer is preferably homogeneously oriented to facilitate the imparting of a predetermined in-plane phase difference to the liquid crystal layer. For this reason, the liquid crystal compound of the liquid crystal layer is preferably a rod-shaped liquid crystal compound.

[0078] The liquid crystal compound is preferably a rod-shaped liquid crystal compound. The rod-shaped liquid crystal compound is not particularly limited, but examples include the compounds shown in (1) to (28) and (A-1) to (A-24) below. In order to increase the birefringence of the liquid crystal compound, a rod-shaped liquid crystal compound containing a sulfur atom in the molecule is preferred.

[0079] [ka]

[0080] [ka]

[0081] [ka]

[0082] [ka]

[0083] [ka]

[0084] [ka]

[0085] [ka]

[0086] [ka]

[0087] [ka]

[0088] The liquid crystal compound is preferably a polymerizable rod-shaped liquid crystal material. Polymerizable functional groups of the polymerizable rod-shaped liquid crystal material include those that polymerize by the action of ultraviolet light, ionizing radiation such as electron beams, or heat. Specific examples include radical polymerizable functional groups. Radical polymerizable functional groups include functional groups having at least one addition polymerizable ethylenically unsaturated double bond, and more specifically, vinyl groups, acrylate groups (a general term encompassing acryloyl groups, methacryloyl groups, acryloyloxy groups, and methacryloyloxy groups), with or without substituents.

[0089] The liquid crystal layer may have positive wavelength dispersion or negative wavelength dispersion.

[0090] The birefringence of the liquid crystal compound is preferably 0.10 to 0.30, and more preferably 0.15 to 0.26. A larger birefringence of the liquid crystal compound is preferable because it allows the same optical performance to be obtained even with a thinner liquid crystal layer. In other words, a larger birefringence of the liquid crystal compound is preferable because it allows the same optical performance to be obtained even with a thinner birefringence layer. However, the greater the birefringence of the liquid crystal compound, the more necessary it becomes to add units sensitive to ultraviolet light, such as aromatic rings like benzene rings, to the liquid crystal molecular structure. For this reason, it is preferable that the birefringence of the liquid crystal compound be 0.30 or less. The birefringence of liquid crystal compounds can be calculated by dividing the in-plane phase difference, measured in an area without pattern pitch, by the thickness. The in-plane phase difference can be measured using, for example, a "KOBRA-WR" manufactured by Oji Instruments Co., Ltd., and the thickness can be measured from a cross-sectional SEM. Alternatively, the birefringence of liquid crystal compounds can also be measured using the prism coupler method.

[0091] A liquid crystal layer can be formed, for example, by applying a liquid crystal layer forming solution containing a liquid crystal compound onto a substrate, and then drying and curing it as needed. When a birefringence layer includes two or more liquid crystal layers, it is preferable to form them so that each liquid crystal layer is in contact with the others. To facilitate the formation of orientation regions in the liquid crystal layer (birefringence layer), it is preferable to form an orientation layer on the substrate in advance.

[0092] <Other layers> The optical element of this disclosure may have layers other than the first birefringence layer and the second birefringence layer. Examples of other layers include the third birefringence layer and the fourth birefringence layer described above. Other layers may include the first substrate, the first alignment layer, the adhesive layer, the second substrate, and the second alignment layer. Other layers may include phase difference layers other than the positive A layer, negative A layer, positive B layer, negative B layer, and positive C layer.

[0093] 《Base material》 The optical element of this disclosure may have a substrate. For example, the optical element of this disclosure preferably has the following configuration 5. By having configuration 5, the first birefringence layer can be protected by the first substrate, and the second birefringence layer can be protected by the second substrate. Furthermore, by arranging the substrates as in configuration 5, there is no substrate that can change the phase between the first birefringence layer and the second birefringence layer, so it is possible to make it easier for light to interact with the first birefringence layer and the second birefringence layer. In addition, by arranging the substrates as in configuration 5, it is possible to suppress curling of the optical element.

[0094] -Composition 5- The first birefringence layer has a first substrate on its first surface side, and the second birefringence layer has a second substrate on its second surface side.

[0095] When the optical element of this disclosure includes the third birefringence layer described above, it is preferable to have the following configuration 5'. When the following configuration 5' is provided, there may or may not be a substrate between the second birefringence layer and the third birefringence layer. -Composition 5'- The first birefringence layer has a first substrate on its first surface side, and the third birefringence layer has a third substrate on its second surface side.

[0096] Various materials can be used as the base material for each base material, but materials with good mechanical properties, optical properties, stability, and processability are preferred. Examples of such materials include polymer resins having an alicyclic structure, methacrylic resins, polycarbonate resins, polystyrene resins, acrylonitrile-styrene copolymers, methyl methacrylate-styrene copolymers, ABS resins, polyethersulfones, triacetylcellulose, polyethylene terephthalate, epoxy acrylates, urethane acrylates, and other resins; glass; etc., with resins being preferred. In other words, each base material is preferably a resin base material. The in-plane phase difference of each substrate is preferably 20 nm or less, more preferably 5 nm or less, even more preferably 3 nm or less, even more preferably 1 nm or less, and most preferably 0 nm. In this specification, the wavelength of light used as the reference for refractive index and phase difference is 550 nm unless otherwise specified.

[0097] The thickness of each substrate can be appropriately adjusted within the range of 5 μm to 1000 μm. The thickness of the substrate can be measured with a film thickness gauge. Examples of film thickness gauges include Mitutoyo's Digimatic Standard Outside Micrometer (model number: MDC-25SX). The substrate thickness can be determined by the average value of measurements taken at any 10 points.

[0098] Each substrate preferably has a total light transmittance of 70% or more, more preferably 80% or more, and even more preferably 85% or more, according to JIS K7361-1:1997. Each substrate preferably has a haze of 5% or less according to JIS K7136:2000, more preferably 3% or less, and even more preferably 1% or less.

[0099] When an orientation layer is present between the substrate and the birefringence layer, it is preferable to keep the refractive index of the orientation layer and the refractive index of the substrate close together in order to suppress the refraction of light. Specifically, the ratio of the refractive index of the orientation layer to the refractive index of the substrate is preferably 0.97 or more and 1.03 or less, and more preferably 0.99 or more and 1.01 or less. When an orientation layer is present between the substrate and the birefringence layer, a primer layer may also be present between the substrate and the orientation layer.

[0100] 《Orientation layer》 The optical element of this disclosure may have an alignment layer. For example, when the optical element of this disclosure has the above configuration 5, it is preferable to have the following configuration 6. By having configuration 6, the first birefringence layer and the second birefringence layer can be more easily provided with the orientation region described above.

[0101] -Composition 6- A first orientation layer is provided between the first substrate and the first birefringence layer, and a second orientation layer is provided between the second substrate and the second birefringence layer.

[0102] The optical element of this disclosure preferably includes the following configuration 6' when it has the configuration 5'. By including configuration 6', the first birefringence layer and the third birefringence layer can be more easily provided with the orientation region described above. -Composition 6'- A first orientation layer is provided between the first substrate and the first birefringence layer, and a third orientation layer is provided between the third substrate and the third birefringence layer.

[0103] Examples of orientation layers include a rubbing layer, a pattern layer, and a photo-alignment layer. Among these, the pattern layer and the photo-alignment layer are preferred.

[0104] (Pattern layer) The patterned layer is a layer that has recesses on the side in contact with the birefringence layer. The patterned layer facilitates the alignment of liquid crystal molecules in the liquid crystal layer contained in the birefringence layer along the direction of extension of the recesses.

[0105] It is preferable to arrange the recesses in the pattern layer so that the direction of extension of the recesses changes gradually by 180 degrees. The direction of extension of the recesses is the direction of the tangent line drawn to the plan view shape of the recesses. In Figures 5(a) and 5(b), the reference numeral 211 corresponds to a recess. In Figures 5(a) and 5(b), the extension direction of the recess changes gradually by 180 degrees in the region indicated by the reference numeral W1. The recesses in the pattern layer may be continuous for a predetermined length, as shown in Figure 5(a), or they may be finely divided, as shown in Figure 5(b). In Figure 5(b), there is a slight gap between adjacent recesses.

[0106] The arrangement pattern of the recesses in the pattern layer should be designed to match the desired arrangement pattern of liquid crystal molecules. The uniaxial length and depth of the recesses in the pattern layer can be appropriately adjusted within a range that facilitates the alignment of liquid crystal molecules along the direction of the recess extension. The depth of the recesses is preferably 2 nm to 200 nm, more preferably 10 nm to 100 nm, and even more preferably 15 nm to 50 nm. Because the depth of the recesses in the pattern layer is on a nanometer scale and therefore small, it has almost no effect on the thickness of the birefringence layer.

[0107] The pattern layer can be formed, for example, by shaping the pattern layer before shaping using a plate having a shape complementary to the surface shape of the pattern layer. More specifically, the pattern layer can be formed, for example, by the following steps 1 and 2.

[0108] Step 1: A step of applying a coating liquid for forming a pattern layer containing resin onto a substrate to form a resin-containing layer. Step 2: A step of forming a resin-containing layer using a plate having a shape complementary to the surface shape of the pattern layer.

[0109] If the coating liquid for forming the pattern layer contains a solvent, it is preferable to dry the solvent in step 1.

[0110] The resin for the pattern layer is preferably a curable resin. A general-purpose curable resin such as a thermosetting resin or an ionizing radiation-curable resin can be used. When a curable resin is used as the resin, it is preferable to use a coating solution containing a curable resin composition as the coating solution for forming the pattern layer in step 1. In other words, when a curable resin is used as the resin, it is preferable that the curable resin in the coating solution in step 1 be in an uncured state. When using a pattern layer forming coating liquid containing an ionizing radiation-curable resin composition as the coating liquid for forming the pattern layer in step 1, it is preferable to irradiate the formed layer with ionizing radiation simultaneously with the forming in step 2 to cure the ionizing radiation-curable resin composition contained in the formed layer.

[0111] The printing plate used in step 2 can be manufactured by general-purpose methods such as laser lithography, electron beam lithography, or focused ion beam. The uneven surface shape formed on the plate can be designed using general-purpose simulation software. It is also preferable to manufacture many copies of the plate manufactured by the aforementioned methods and arrange these copies to create a multi-plate. The plate can be duplicated by general-purpose methods such as electroforming. The shape of the printing plate can be flat, cylindrical, or other shapes. Cylindrical plates are preferable because they can be processed roll-to-roll, resulting in superior productivity.

[0112] (photo alignment layer) The photo-alignment layer can be formed, for example, by irradiating a photo-alignable material with polarized or unpolarized light. Polarized light irradiation can be performed perpendicular or oblique to the photo-alignment layer, while unpolarized light irradiation can be performed obliquely to the photo-alignment layer.

[0113] The photo-alignment layer can be patterned, for example, by the methods described in (1) and (2) below. (1) A method of exposing an orientation layer using a polarizing mask patterned to a predetermined pattern. A wire grid type polarizing mask is an example of the polarizing mask. It is preferable that the orientation layer and the polarizing mask be in close contact during exposure. It is preferable that the ultraviolet light used for exposure be parallel light. (2) A method of exposing the alignment layer with polarized laser light. By changing the polarization direction of the laser at different locations on the alignment film, the alignment direction can be patterned into a predetermined pattern.

[0114] Examples of photo-oriented materials include photoisomerized and photodimerized resins. Examples of photodimerized resins include resins having structures such as cinnamate, coumarin, benzylidenephthalimidine, benzylideneacetophenone, diphenylacetylene, stilbazole, uracil, quinolinone, maleimide, and cinnamyridene acetate derivatives. Examples of photoisomerized resins include resins containing azo compounds.

[0115] The thickness of the alignment layer such as the pattern layer and the photo-alignment layer may be appropriately adjusted according to the purpose.

[0116] 《Adhesive layer》 The optical element of the present disclosure may have an adhesive layer. The adhesive layer is disposed, for example, between the first birefringence layer and the second birefringence layer.

[0117] As the adhesive layer, a general-purpose adhesive layer such as a pressure-sensitive adhesive layer, a heat-sensitive adhesive layer, or a curable adhesive layer can be used. The thickness of the adhesive layer may be appropriately adjusted according to the purpose.

[0118] 《Retardation layer》 The optical element of the present disclosure may have one or more layers selected from a positive A layer, a negative A layer, a positive B layer, a negative B layer, and a positive C layer between the first birefringence layer and the second birefringence layer. When the optical element of the present disclosure further includes a third birefringence layer, it may have one or more layers selected from a positive A layer, a negative A layer, a positive B layer, a negative B layer, and a positive C layer between the second birefringence layer and the third birefringence layer.

[0119] When the refractive index in the slow axis direction with the highest refractive index in the plane of the positive C layer is defined as Nx, the refractive index in the direction orthogonal to the slow axis in the plane is defined as Ny, and the refractive index in the layer thickness direction is defined as Nz, it is a layer that satisfies the relationship of Nx≒Ny<Nz. Nx≒Ny means that the difference between Nx and Ny is 0.02 or less. The difference is preferably 0.01 or less. <G The positive A layer is a layer that satisfies the relationship of Nx>Ny≒Nz. Ny≒Nz means that the absolute value of the difference between Ny and Nz is 0. We 02 or less. The absolute value of the difference is preferably 0.01 or less. The negative A layer is a layer that satisfies the relationship of Nx≒Nz>Ny. Nx≒Nz means that the absolute value of the difference between Nx and Nz is 0.02 or less. The absolute value of the difference is preferably 0.01 or less. Positive layer B is a layer that satisfies the relationship Nz > Nx > Ny. Negative layer B is a layer that satisfies the relationship Nx > Ny > Nz.

[0120] The refractive index of each layer, such as the positive C layer, can be measured using the following methods C1 to C3, for example, by using Fresnel's formula for reflectance under normal incidence. However, the refractive index cannot be measured in regions with orientation pitch in the planar direction because diffraction occurs. Therefore, a measurement sample without orientation pitch in the planar direction is prepared, and the refractive index of each layer is measured using this sample. C1: Light is incident on each layer at a 5-degree angle from the perpendicular, and the reflectance is measured at the angle in the specular reflection direction. The incident light is linearly polarized and parallel to the slow axis of each layer. Then, the refractive index (Nx) is calculated from the obtained reflectance in the slow axis direction using the following formula. * Calculate ). Reflectance in the slow phase axis direction = ((1-Nx * ) / (1+Nx * )) 2 C2: For each layer, light is incident at a 5-degree angle from the perpendicular, and the reflectance is measured at the angle in the specular reflection direction. The incident light is linearly polarized and parallel to the phase-advancing axis of each layer. Then, the refractive index (Ny) is calculated from the obtained reflectance in the direction of the phase-advancing axis using the following formula. * Calculate ). Reflectance in the phase-advancing axis direction = ((1-Ny * ) / (1+Ny * )) 2 C3: The three-dimensional refractive index values ​​(Nx, Ny, Nz) calculated from the phase difference measuring instrument (product name: KOBRA, manufactured by Oji Instruments Co., Ltd.) are equal to the in-plane refractive index Nx of C1 and C2. * and Ny * The values ​​of the three-dimensional refractive index are adjusted to match the requirements. Then, the adjusted three-dimensional refractive index values ​​(Nx, Ny, Nz) are set as Nx, Ny, and Nz for each layer.

[0121] Positive layer A, negative layer A, positive layer B, negative layer B, and positive layer C can be general-purpose positive layer A, negative layer A, positive layer B, negative layer B, and positive layer C.

[0122] The optical elements of this disclosure can be manufactured, for example, by the following steps A1 and A2. Step A1: A step of preparing a first laminate having a first birefringence layer on a first substrate, and a second laminate having a second birefringence layer on a second substrate. Step A2: A step of bonding the first laminate and the second laminate together.

[0123] <Application> The optical element of this disclosure can be used, for example, as a diffractive optical element. Furthermore, the optical element of this disclosure can also be used as a component of a light-adjusting device. It is preferable that the optical element of this disclosure is used such that the first surface is the light incident surface. Light transmitted through a diffractive optical element can be adjusted to a predetermined diffraction angle range. Therefore, for example, by using a diffractive optical element, the illumination range of light can be broadened or narrowed. Furthermore, directionality can also be imparted by using a diffractive optical element. Furthermore, by causing the light that has passed through the diffractive optical elements to interfere with each other, it is possible to create effects such as those of a lens and a prism. Due to the effects described above, diffractive optical elements can be used as components in devices such as cross-reality displays, optical sensors, and laser projectors.

[0124] [Optical components] The optical component of this disclosure is formed by laminating the optical element of this disclosure described above with a substrate.

[0125] The optical element constituting the optical member of this disclosure preferably does not have a substrate. The absence of a substrate in the optical element of this disclosure is preferable because it makes the optical member less susceptible to the influence of the substrate's inherent phase difference.

[0126] Examples of adherends include panels for image display devices such as liquid crystal display panels and organic EL display panels; lenses such as convex lenses and concave lenses; polarizers such as absorbing polarizers and reflective polarizers; optical films such as phase difference films; and the like. In the optical component of this disclosure, it is preferable to bond the optical element and the adherend member via an adhesive layer.

[0127] The laminated configurations of the optical members of this disclosure include the following (D1) to (D8). Of the layers constituting the optical members of (D1) to (D8) below, the layers other than the adherend are layers constituting optical elements. In the optical members of this disclosure, it is preferable that each layer is tightly attached and integrated. The laminated configurations of the optical members of this disclosure are not limited to the following (D1) to (D8). For example, in the following (D1) to (D8), there may be one or more adhesive layers between each layer. In particular, in the following (D1) to (D8), it is preferable to have an adhesive layer between the adherend and the layer in contact with the adherend. The laminated configurations of (D1) to (D8) below can be obtained, for example, by a transfer method. The following lamination configurations (D1) to (D8) are preferable because the optical elements do not have a substrate, and therefore the optical components are less affected by the phase difference inherent to the substrate.

[0128] (D1) Adhered member, first birefringence layer, second birefringence layer (D2) First birefringence layer, second birefringence layer, adherend (D3) Adhered member, first orientation layer, first birefringence layer, second birefringence layer, second orientation layer (D4) First orientation layer, first birefringence layer, second birefringence layer, second orientation layer, adherend (D5) Adhered member, first birefringence layer, second birefringence layer, third birefringence layer (D6) First birefringence layer, second birefringence layer, third birefringence layer, adherend (D7) Adhered member, first orientation layer, first birefringence layer, second birefringence layer, second orientation layer, third birefringence layer, third orientation layer (D8) First orientation layer, first birefringence layer, second birefringence layer, second orientation layer, third birefringence layer, third orientation layer, adherend

[0129] The optical member of this disclosure can be manufactured, for example, by the following steps B1 to B4. By steps B1 to B4, an optical member having a substrate, a first birefringence layer, and a second birefringence layer in that order can be obtained. In other words, the optical member obtained by steps B1 to B4 is an optical member with the above-described laminated configuration (D1). Steps B1 to B4 are an example of a manufacturing method using a transfer method. By applying steps B1 to B4, optical members with the above-described laminated configurations (D2) to (D8) can be obtained. For example, if the first laminate in step B1 has a first substrate, a first orientation layer, and a first birefringence layer, and the interface between the first orientation layer and the first birefringence layer is peelable, and the second laminate in step B1 has a second substrate, a second orientation layer, and a second birefringence layer, and the interface between the second orientation layer and the second birefringence layer is peelable, then an optical member with the above-described laminated configuration (D3) can be obtained. Optical components manufactured by the transfer method are preferable because they allow for the omission of the substrate for the optical element, enabling the optical component to be made thinner, and are less susceptible to the effects of the substrate's inherent phase difference.

[0130] Step B1: A step of preparing a first laminate having a first birefringence layer on a peelable first substrate, and a second laminate having a second birefringence layer on a peelable second substrate. Step B2: A step to obtain a laminate X1 by bonding the first laminate and the second laminate such that the first birefringence layer and the second birefringence layer face each other. Process B3: A process of peeling the first substrate from the laminate X1 and bonding the exposed surface to the adherend. Process B4: Process for peeling off the second substrate

[0131] [Device] The apparatus of this disclosure includes the optical elements of this disclosure described above.

[0132] Examples of devices include display devices such as cross-reality displays, optical sensors, and laser projectors. In the device of this disclosure, it is preferable to arrange the optical elements such that the first surface of the optical element becomes the light incident surface.

[0133] This disclosure is as follows: <1> ~ <16> Includes. <1> An optical element, The optical element has a first surface and a second surface opposite to the first surface, and has a first birefringence layer and a second birefringence layer in this order from the first surface toward the second surface. The first birefringence layer and the second birefringence layer each have an in-plane phase difference of (λ1 / 2) × 0.95 or more and (λ1 / 2) × 1.05 or less when the wavelength λ1 is 635 nm or 1550 nm. The first birefringence layer and the second birefringence layer each include one or more liquid crystal layers in the thickness direction. The first birefringence layer has a plurality of first orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. The second birefringence layer has a plurality of second orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. In the first birefringence layer, when P1 is defined as the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, at least a portion of the first orientation region's P1 shows a different value from the other first orientation regions' P1. The value of P1 is the shortest of the multiple first orientation regions. min An optical element that satisfies the following equation 1, given that the first birefringence layer has a refractive index of [nm] and the thickness of the first birefringence layer is defined as d[nm]. asin(λ1 / P1 min ) <atan(P1 min / d) Formula 1 [In Equation 1, "λ1" is at least one of the wavelengths 635 nm and 1550 nm that satisfies the range of the in-plane phase difference.] <2> d / P1 min The value is between 0.40 and 2.90. <1> Optical elements as described above. <3> P1 min The wavelength is between 200 nm and 4000 nm. <1> or <2> Optical elements as described above. <4> In the second birefringence layer, when P2 is defined as the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, at least a portion of the second orientation region's P2 shows a different value from the other second orientation regions' P2. <1> ~ <3> An optical element described in any of the following. <5> The predetermined direction of the first birefringence layer is a specific one direction of the first birefringence layer, the predetermined direction of the second birefringence layer is a specific one direction of the second birefringence layer, and the specific one direction of the first birefringence layer and the specific one direction of the second birefringence layer are substantially the same direction. <1> ~ <4> An optical element described in any of the following. <6> In the first birefringence layer, the first orientation region P1 becomes progressively shorter from the first orientation region at one end in a specific direction toward the first orientation region at the other end in the specific direction. In the second birefringence layer, when P2 is defined as the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, the P2 of the second alignment region gradually shortens from the second alignment region at one end of the specific direction toward the second alignment region at the other end of the specific direction. <5> Optical elements as described above. <7> The predetermined direction of the first birefringence layer is a radial multidirectional direction with respect to the center of the arrangement pattern of the liquid crystal molecules, The predetermined direction of the second birefringence layer is a radial multidirectional direction with respect to the center of the arrangement pattern of the liquid crystal molecules. <1> ~ <4> An optical element described in any of the following. <8> In the first birefringence layer, P1 gradually shortens from the first orientation region located at the center of the array pattern toward the first orientation region located outside the array pattern. When P2 is defined as the length in the orientation region of the second birefringence layer until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, P2 gradually decreases from the second orientation region located at the center of the alignment pattern toward the second orientation region located outside the alignment pattern. <7> Optical elements as described above. <9> The first birefringence layer has a first substrate on its first surface side, and the second birefringence layer has a second substrate on its second surface side. <1> ~ <8> An optical element described in any of the following. <10> A first alignment layer is provided between the first substrate and the first birefringence layer, and a second alignment layer is provided between the second substrate and the second birefringence layer. <9> Optical elements as described above. <11> Between the first birefringence layer and the second birefringence layer, there is one or more layers selected from a positive A layer, a negative A layer, a positive B layer, a negative B layer, and a positive C layer. <1> ~ <10> An optical element described in any of the following. <12> Furthermore, it has a third birefringence layer, The third birefringence layer includes one or more liquid crystal layers in the thickness direction. The first birefringence layer, the second birefringence layer, and the third birefringence layer are arranged in this order from the first surface toward the second surface. The third birefringence layer has an in-plane phase difference of (λ1 / 2) × 0.95 or more and (λ1 / 2) × 1.05 or less when the wavelength λ1 is 635 nm or 1550 nm. The third birefringence layer has a plurality of third orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. <1> ~ <11> An optical element described in any of the following. <13> The optical element is formed in which each layer from the first surface to the second surface is tightly packed and integrated. <1> ~ <12> An optical element described in any of the following. <14> An adhesive layer is provided between the first birefringence layer and the second birefringence layer. <1> ~ <13> An optical element described in any of the following. <15> <1> ~ <14> An optical component comprising an optical element described in any of the above and a substrate to be adhered to, laminated together. <16> <1> ~ <14> An apparatus containing an optical element as described in any of the above. [Examples]

[0134] Next, the present disclosure will be described in more detail by examples, but the present disclosure is not limited in any way by these examples. Unless otherwise specified, "parts" and "%" refer to mass.

[0135] 1. Measurement and Evaluation The following measurements and evaluations were performed on the optical elements of the examples and comparative examples. The ambient conditions during each measurement and evaluation were a temperature of 23±5°C and a relative humidity of 40% to 65%. Before starting each measurement and evaluation, the target sample was exposed to the aforementioned atmosphere for 30 to 60 minutes before measurement and evaluation.

[0136] 1-1. Light leakage The laser light source 61, polarizer 62, λ / 4 phase difference plate 63, optical elements 100 of the examples and comparative examples, and detector 64 were arranged in the order shown in Figure 6. When the optical element 100 had multiple birefringence layers, it was positioned so that the first birefringence layer side of the optical element 100 faced the λ / 4 phase difference plate 63 side. The detector 64 is a detector equipped with an integrating sphere, and the angle of the aperture of the integrating sphere with respect to the irradiation direction of the laser light is variable. When the angle of the aperture with respect to the irradiation direction of the laser light is perpendicular, the angle connecting the incident point of the laser light on the optical element and the aperture radius of the integrating sphere was adjusted to 2 to 3 degrees. The light transmitted through the λ / 4 phase difference plate 63 is left-circularly polarized. Laser light was irradiated perpendicular to the plane of the polarizer in Figure 6, and the intensity of the laser light that traveled in a straight line was detected by the detector. The intensity of the laser light at this time was defined as the "intensity through the optical element at 0 degrees". In addition, the intensity of the laser light that traveled in a straight line with the optical element removed from Figure 6 was detected by the detector. The intensity of the laser light at this time was defined as the "blank intensity." Then, the percentage of light leakage at 0 degrees of incidence was calculated using the following formula. The results are shown in Table 2. In Figure 6, the laser light that travels in a straight line without being diffracted by the optical element 100 can be considered a laser with light leakage because it has not been properly diffracted. The percentage of light leakage was calculated for laser light of three wavelengths: 450 nm, 532 nm, and 635 nm. A light leakage percentage of 1.2% or less is considered acceptable. Percentage of light leakage at 0 degrees of incidence (%) = (Intensity through the optical element at 0 degrees / Intensity of the blank) × 100

[0137] 1-2. Alignment Pitch and Thickness Cross-sectional photographs of the optical elements of the examples and comparative examples were obtained by the methods of (B1) to (B4) in the main text of the specification, and the minimum alignment pitch and thickness of each birefringent layer were measured. The STEM conditions were as follows. <STEM Conditions> · Apparatus (manufactured by Hitachi High-Tech Corporation, product number: S-4800 TYPE1) · Acceleration voltage; 30.0 kV · Emission current; 10 μA · W.D; 8 mm · Detector; TE

[0138] 2. Plate Production <Shape Design by Simulation> Using a simulation tool, the pattern of the concave portions of the pattern layer was designed. The patterns of the concave portions were designed with the following first to fifth patterns. 《First Pattern》 The pattern of the concave portion was a pattern corresponding to the alignment direction 31c of the liquid crystal molecules in FIG. 4. In the said pattern, the minimum value of the alignment pitch, which is the length until the extending direction of the concave portion changes stepwise by 180 degrees, was 3 μm. The maximum value of the alignment pitch was 300 μm (the maximum value of the alignment pitch for the second to fifth patterns was also 300 μm). The width in the short-axis direction of each concave portion was 25 nm, and the depth of each concave portion was 30 nm. 《Second Pattern》 The second pattern was designed in the same manner as the first pattern, except that the minimum value of the alignment pitch, which is the length until the extending direction of the concave portion changes stepwise by 180 degrees, was changed to 2 μm. 《Third Pattern》 The pattern of the recesses was designed to correspond to the arrangement direction 31a of the liquid crystal molecules in Figure 3(a). Although the number of patterns in the X and Y axes is small in Figure 3(a), the number of patterns in the X and Y axes was increased until a sufficient number was reached. In the above pattern, the minimum value of the orientation pitch, which is the length until the extension direction of the recesses changes by 180 degrees in steps, was set to 3 μm. The width in the short axis direction of each recess was 25 nm, and the depth of each recess was 30 nm. 《The fourth pattern》 The fourth pattern was designed in the same manner as the third pattern, except that the minimum value of the orientation pitch, which is the length until the extension direction of the recess changes by 180 degrees in steps, was changed to 2 μm. 《The Fifth Pattern》 The fifth pattern was designed in the same manner as the third pattern, except that the minimum value of the orientation pitch, which is the length until the direction of extension of the recess changes by 180 degrees in steps, was changed to 1.5 μm.

[0139] <Creating a version using the above data> 《Preparation of the first roll-shaped plate》 Using a 6-inch square synthetic quartz plate, a quartz matrix was fabricated with recesses of the first pattern designed in simulation, through an electron beam lithography process using an electron beam lithography system and a dry etching system. Next, UV-curable resin was poured into the mold, and a transparent substrate was placed on top of the UV-curable resin. Then, the resin was cured by irradiation with ultraviolet light. After that, the transparent substrate and resin were peeled off from the mold to obtain a resin plate having a shape complementary to the shape of the mold. Next, a duplicate mold of the mold, having a shape complementary to the shape of the resin plate, was obtained by electroforming. Multiple duplicate molds were made. Multiple duplicate molds were wound onto a roll to produce a first roll-shaped plate. 《Preparation of the 2nd to 5th roll-shaped printing plates》 Except for changing the first pattern to the second to fifth patterns, the second to fifth roll-shaped plates were obtained in the same manner as the first roll-shaped plate.

[0140] 3. Fabrication of optical elements [Example 1] <Fabrication of the first laminate> A primer layer with a thickness of 0.5 μm was formed by applying and drying a primer layer with the following formulation onto a substrate (a cycloolefin polymer with a thickness of 40 μm; product name "Zeonor" from Nippon Zeon Co., Ltd.). Next, a pattern layer forming solution according to the following formulation was applied to the primer layer and dried to form a layer containing uncured resin. Next, using the first roll-shaped plate prepared in "2" above, a layer containing uncured resin is formed, and at the same time, ultraviolet light is irradiated from the substrate side (cumulative light intensity: 500 mJ / cm²). 2 The formed resin-containing layer was then cured. Next, the formed layer was peeled off the plate to obtain a laminate having a primer layer and a pattern layer on a substrate. The pattern layer corresponds to an orientation layer. Next, the liquid crystal layer forming solution 1 described below is applied to the pattern layer, which is the alignment layer, and after drying, ultraviolet light is irradiated (cumulative light intensity: 150 mJ / cm²). 2 ), the first liquid crystal layer was formed. On top of the first liquid crystal layer, the second to fourth liquid crystal layers were further formed, creating a birefringence layer consisting of four liquid crystal layers. The four liquid crystal layers are in contact with each other. The liquid crystal layer used liquid crystal molecules with an in-plane birefringence (Δn) of 0.24. The thickness of the birefringence layer (total thickness of the four liquid crystal layers) was set to 2000 nm. Through the above steps, a first laminate used in Example 1 was obtained, having a substrate, a primer layer, an orientation layer, and a birefringence layer in that order. The substrate, primer layer, orientation layer, and birefringence layer of the first laminate used in Example 1 correspond to the first substrate, the first primer layer, the first orientation layer, and the first birefringence layer. As will be described later, the in-plane phase difference at a wavelength of 450 nm, the in-plane phase difference at a wavelength of 532 nm, and the in-plane phase difference at a wavelength of 635 nm of the first birefringence layer is in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less (λ is wavelength (nm)).

[0141] <Fabrication of the second layer> A second laminate used in Example 1 was obtained using the same materials and the same process as for the first laminate. The substrate, primer layer, orientation layer, and birefringence layer of the second laminate used in Example 1 correspond to the second substrate, second primer layer, second orientation layer, and second birefringence layer. The thickness of the second birefringence layer is 2000 nm. As will be described later, the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm of the second birefringence layer is in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less (λ is wavelength (nm)).

[0142] <Preparation of the first transfer film> A first transfer film for use in Example 1 was prepared, having a peelable first substrate, a first adhesive layer, and a peelable second substrate in that order. The relationship is that the peel strength between the peelable first substrate and the first adhesive layer is less than the peel strength between the peelable second substrate and the second adhesive layer.

[0143] <Bonding> The first substrate, which is peelable, was peeled off the first transfer film. Next, the first adhesive layer of the first transfer film, which was exposed after peeling off the first substrate, and the first birefringence layer of the first laminate were bonded together facing each other. Next, the second substrate, which is peelable, was peeled off the first transfer film. Next, the first adhesive layer of the first transfer film, which was exposed after peeling off the second substrate, and the second birefringence layer of the second laminate were bonded together facing each other. Through the above process, an optical element of Example 1 was obtained, having a first substrate, a first primer layer, a first alignment layer, a first birefringence layer, a first adhesive layer, a second birefringence layer, a second alignment layer, a second primer layer, and a second substrate in this order, with these layers tightly bonded and integrated. The first birefringence layer and the second birefringence layer were aligned in the planar direction so that the direction of the arrangement of liquid crystal molecules changes stepwise by 180 degrees. The planar positional displacement of the alignment regions of the first and second birefringence layers was kept to less than 300 μm. In Example 1, Examples 2-4 described later, and Comparative Example 1, the first birefringence layer and the second birefringence layer satisfy configurations 3 and 4 described in the main text of the specification. Furthermore, in Example 1, Examples 2-4 described later, and Comparative Example 1, the rotation direction of the liquid crystal molecules along the radial patterns of the first birefringence layer and the second birefringence layer was opposite for the first birefringence layer and the second birefringence layer (because the first birefringence layer and the second birefringence layer are stacked facing each other, the radial patterns of the first birefringence layer and the radial patterns of the second birefringence layer are mirror images of each other).

[0144] 《Coating liquid for forming a primer layer》 • Polyolefin resin: 70 parts by mass (Manufactured by Mitsubishi Chemical Corporation, product name: Surflen P-1000) • Silica-based lubricant: 5 parts by mass (Manufactured by CIK Nanotech, product name: SIRMIBK15WT%-E65) Methyl ethyl ketone: 25 parts by mass

[0145] 《Coating liquid for forming patterned layers》 Pentaerythritol triacrylate: 96 parts by mass (Manufactured by Nippon Kayaku Co., Ltd., product name: PET-30) • Photopolymerization initiator: 4 parts by mass (Manufactured by IGM, product name: Omnirad184)

[0146] 《Coating solution for forming liquid crystal layer 1》 ·Rod-shaped liquid crystal molecules: 10 parts by mass (Nematic liquid crystal compound as specified in (A-1) of the specification. In-plane birefringence (Δn)) • Photopolymerization initiator: 0.4 parts by mass (Manufactured by IGM, product name: Omnirad184) • Chiral agent: appropriate amount (BASF, Paliocolor® LC756) Methyl ethyl ketone: 89.6 parts by mass (Note: Except for Comparative Example 5, the chiral agent content was adjusted within a range where the helical period of each liquid crystal layer in the Examples and Comparative Examples was a predetermined period. The predetermined period mentioned above is the helical period required for the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm in each birefringence layer to be in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less (λ is wavelength (nm)). As described in the main text of the specification, the conditions for the number of liquid crystal layers stacked, the thickness of each liquid crystal layer, and the helical period (twist angle) of each liquid crystal layer to make the phase difference of the birefringence layer λ / 2 in the desired wavelength range can be determined by simulation. Based on the simulation results, the amount of chiral agent in each Example and Comparative Example can be adjusted. As described in the main text of the specification, increasing the concentration of the chiral agent shortens the helical period. In the case of a liquid crystal layer that does not have a helical structure, the chiral agent content can be set to 0.

[0147] [Example 2] An optical element of Example 2 was obtained in the same manner as in Example 1, except that the thickness of the first birefringence layer (total thickness of the four liquid crystal layers) and the thickness of the second birefringence layer (total thickness of the four liquid crystal layers) were changed to 5000 nm, respectively. However, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm in the first and second birefringence layers were in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less.

[0148] [Example 3] <Fabrication of the first laminate> The first laminate used in Example 3 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to a second roll-shaped plate and the thickness of the birefringence layer (total thickness of the four liquid crystal layers) was changed to 3000 nm. However, in the first birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Fabrication of the second layer> A second laminate used in Example 3 was obtained using the same materials as the first laminate in Example 3 and by the same process as the first laminate in Example 3. However, in the second birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Preparation of the first transfer film> As the first transfer film used in Example 3, the same type as the first transfer film used in Example 1 was prepared. <Bonding> Except for changing the first and second laminates to the first and second laminates used in Example 3, the same bonding process as in Example 1 was used to obtain the optical element of Example 3, which has a first substrate, a first primer layer, a first alignment layer, a first birefringence layer, a first adhesive layer, a second birefringence layer, a second alignment layer, a second primer layer, and a second substrate in this order, with these layers tightly bonded and integrated. The first and second birefringence layers were arranged so that the direction in which the arrangement direction of liquid crystal molecules changes stepwise by 180 degrees was approximately coincided in the planar direction. The positional displacement in the planar direction of the alignment regions of the first and second birefringence layers was kept to less than 300 μm.

[0149] [Example 4] An optical element of Example 4 was obtained in the same manner as in Example 3, except that the thickness of the first birefringence layer (total thickness of the four liquid crystal layers) and the thickness of the second birefringence layer (total thickness of the four liquid crystal layers) were changed to 5000 nm, respectively. However, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm in the first and second birefringence layers was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less.

[0150] [Example 5] <Fabrication of the first laminate> The first laminate used in Example 5 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to a third roll-shaped plate and the thickness of the birefringence layer (total thickness of the four liquid crystal layers) was changed to 3000 nm. However, in the first birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Fabrication of the second layer> A second laminate used in Example 5 was obtained using the same materials as the first laminate in Example 5 and by the same process as the first laminate in Example 5. However, in the second birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Preparation of the first transfer film> As the first transfer film used in Example 5, the same type as the first transfer film used in Example 1 was prepared. <Bonding> Except for changing the first and second laminates to the first and second laminates used in Example 5, the same bonding process as in Example 1 was used to obtain the optical element of Example 5, which has a first substrate, a first primer layer, a first alignment layer, a first birefringence layer, a first adhesive layer, a second birefringence layer, a second alignment layer, a second primer layer, and a second substrate in this order, with these layers tightly bonded and integrated. The first and second birefringence layers were arranged so that the direction in which the arrangement direction of liquid crystal molecules changes stepwise by 180 degrees was approximately coincided in the planar direction. The positional displacement in the planar direction of the alignment regions of the first and second birefringence layers was kept to less than 300 μm. In Example 5, Examples 6-9 (described later), and Comparative Examples 2-3, the first and second birefringence layers satisfy configurations 1 and 2 of the specification. Furthermore, in Example 8 and Comparative Example 3 (described later), the third birefringence layer satisfies configurations 1' and 2' of the specification. In Example 5, Examples 6 to 9 described later, and Comparative Examples 2 to 3, the alignment patterns of the liquid crystal molecules in the first birefringence layer and the second birefringence layer are arc-shaped. In Example 5, Examples 6 to 9 described later, and Comparative Examples 2 to 3, lamination was performed such that the direction of the arc of the first birefringence layer was 180 degrees different from the direction of the arc of the second birefringence layer. Further, in Examples 8 and Comparative Example 3 described later, the alignment pattern of the liquid crystal molecules in the third birefringence layer is arc-shaped, and lamination was performed such that the direction of the arc of the second birefringence layer was 180 degrees different from the direction of the arc of the third birefringence layer.

[0151] [Example 6] <Production of the First Laminate> The first laminate used in Example 6 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to the fourth roll-shaped plate and the thickness of the birefringence layer (total thickness of the four liquid crystal layers) was changed to 3000 nm. However, in the first birefringence layer, the in-plane retardation at a wavelength of 450 nm, the in-plane retardation at a wavelength of 532 nm, and the in-plane retardation at a wavelength of 635 nm were adjusted so as to be in the range of (λ / 2)×0.95 or more and (λ / 2)×1.05 or less by adjusting the amount of the chiral agent in the coating liquid 1 for forming the liquid crystal layer. <Production of the Second Laminate> Using the same materials as the first laminate of Example 6 and by the same process as the first laminate of Example 6, the second laminate used in Example 6 was obtained. However, in the second birefringence layer, the in-plane retardation at a wavelength of 450 nm, the in-plane retardation at a wavelength of 532 nm, and the in-plane retardation at a wavelength of 635 nm were adjusted so as to be in the range of (λ / 2)×0.95 or more and (λ / 2)×1.05 or less by adjusting the amount of the chiral agent in the coating liquid 1 for forming the liquid crystal layer. <Preparation of the First Transfer Film> As the first transfer film used in Example 6, the same one as the first transfer film of Example 1 was prepared. <Lamination> Except for changing the first and second laminates to the first and second laminates used in Example 6, the same bonding process as in Example 1 was used to obtain the optical element of Example 6, which has a first substrate, a first primer layer, a first alignment layer, a first birefringence layer, a first adhesive layer, a second birefringence layer, a second alignment layer, a second primer layer, and a second substrate in this order, with these layers tightly bonded and integrated. The first and second birefringence layers were arranged so that the direction in which the arrangement direction of liquid crystal molecules changes stepwise by 180 degrees was approximately coincided in the planar direction. The positional displacement in the planar direction of the alignment regions of the first and second birefringence layers was kept to less than 300 μm.

[0152] [Example 7] <Fabrication of the first laminate> The first laminate used in Example 7 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to a fourth roll-shaped plate and the thickness of the birefringence layer (total thickness of the four liquid crystal layers) was changed to 4000 nm. However, in the first birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Fabrication of the second layer> A second laminate used in Example 7 was obtained in the same manner as the second laminate in Example 5. However, in the second birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm in the second birefringence layer was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Bonding> Except for changing the first and second laminates to the first and second laminates used in Example 7, the same bonding process as in Example 1 was used to obtain the optical element of Example 7, which has a first substrate, a first primer layer, a first alignment layer, a first birefringence layer, a first adhesive layer, a second birefringence layer, a second alignment layer, a second primer layer, and a second substrate in this order, with these layers tightly bonded and integrated. The first and second birefringence layers were arranged so that the direction in which the arrangement direction of liquid crystal molecules changes stepwise by 180 degrees was substantially aligned in the planar direction. The positional displacement in the planar direction of the alignment regions of the first and second birefringence layers was kept to less than 300 μm.

[0153] [Example 8] <Fabrication of the first laminate> The first laminate used in Example 8 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to a third roll-shaped plate and the thickness of the birefringence layer (total thickness of the four liquid crystal layers) was changed to 4000 nm. However, in the first birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Fabrication of the second layer> A second laminate used in Example 8 was obtained using the same materials as the first laminate in Example 8 and by the same process as the first laminate in Example 8. However, in the second birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Fabrication of the third layer> A third laminate used in Example 8 was obtained using the same materials as the first laminate in Example 8 and by the same process as the first laminate in Example 8. The substrate, primer layer, orientation layer, and birefringence layer of the third laminate used in Example 8 correspond to the third substrate, third primer layer, third orientation layer, and third birefringence layer. However, in the third birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Preparation of the first transfer film> As the first transfer film used in Example 8, the same type as the first transfer film used in Example 1 was prepared. <Preparing the second transfer film> As the second transfer film used in Example 8, the same type as the first transfer film used in Example 1 was prepared. The second transfer film used in Example 8 has, in this order, a peelable first substrate, a second adhesive layer, and a peelable second substrate. <Bonding> The first substrate, which is peelable, was peeled from the first transfer film. Next, the first adhesive layer of the first transfer film, which was exposed after peeling off the first substrate, was bonded to the first birefringence layer of the first laminate facing each other. Next, the second substrate, which is peelable, was peeled from the first transfer film. Next, the first adhesive layer of the first transfer film, which was exposed after peeling off the second substrate, was bonded to the second birefringence layer of the second laminate facing each other. Next, the first substrate, which is peelable, was peeled from the second transfer film. Next, the first adhesive layer of the second transfer film, which was exposed after peeling off the first substrate, was bonded to the second substrate of the second laminate facing each other. Next, the second substrate, which is peelable, was peeled from the second transfer film. Next, the second adhesive layer of the second transfer film, which was exposed after peeling off the second substrate, was bonded to the third birefringence layer of the third laminate facing each other. Through the above process, an optical element of Example 8 was obtained, having a first substrate, a first primer layer, a first alignment layer, a first birefringence layer, a first adhesive layer, a second birefringence layer, a second alignment layer, a second primer layer, a second substrate, a second adhesive layer, a third birefringence layer, a third alignment layer, a third primer layer, and a third substrate in this order, with these layers tightly bonded and integrated. The first birefringence layer, the second birefringence layer, and the third birefringence layer were aligned in the planar direction so that the direction of the arrangement of liquid crystal molecules changes stepwise by 180 degrees. The planar positional displacement of the alignment regions of the first to third birefringence layers was kept to less than 300 μm.

[0154] [Example 9] <Fabrication of the first laminate> The first laminate used in Example 9 was obtained in the same manner as the first laminate in Example 6, except that the substrate was changed to a substrate that can be peeled off between the substrate and the primer layer. <Fabrication of the second layer> The second laminate used in Example 9 was obtained in the same manner as the second laminate in Example 6, except that the substrate was changed to a substrate that can be peeled off between the substrate and the primer layer. <Preparation of the first transfer film> As the first transfer film used in Example 9, the same type as the first transfer film used in Example 1 was prepared. <Bonding> The first removable substrate was peeled from the first transfer film. Next, the first adhesive layer of the first transfer film, which was exposed after peeling off the removable first substrate, and the first birefringence layer of the first laminate were bonded together facing each other. Next, the second removable substrate was peeled from the first transfer film. Next, the first adhesive layer of the first transfer film, which was exposed after peeling off the removable second substrate, was bonded together facing each other with the second birefringence layer of the second laminate. Next, the removable substrates of the first laminate and the removable substrates of the second laminate were peeled off. Through the above process, an optical element of Example 9 was obtained, having a first primer layer, a first orientation layer, a first birefringence layer, a first adhesive layer, a second birefringence layer, a second orientation layer, and a second primer layer in this order, with these layers tightly bonded and integrated. The optical element of Example 9 does not have a substrate. The first birefringence layer and the second birefringence layer were arranged so that the direction in which the arrangement direction of liquid crystal molecules changes stepwise by 180 degrees was substantially aligned in the planar direction. The positional displacement in the planar direction of the orientation regions of the first and second birefringence layers was kept to less than 300 μm.

[0155] [Comparative Example 1] <Fabrication of the first laminate> The first laminate used in Comparative Example 1 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to a second roll-shaped plate, the liquid crystal layer forming coating solution 1 was changed to the liquid crystal layer forming coating solution 2 described below, and the thickness of the birefringence layer (total thickness of the four liquid crystal layers) was changed to 7000 nm. However, in the first birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 2 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. 《Coating solution for forming liquid crystal layer 2》 ·Rod-shaped liquid crystal molecules: 10 parts by mass (A mixture of a liquid crystal compound manufactured by Tokyo Chemical Industry Co., Ltd. (CAS RN: 132900-75-5, product code: D5936) and a liquid crystal compound manufactured by BASF (Paliocolor LC1057 (trade name)), in a mass ratio of 7:3. In-plane birefringence (Δn) = 0.17) • Photopolymerization initiator: 0.4 parts by mass (Manufactured by IGM, product name: Omnirad184) • Chiral agent: appropriate amount (BASF, Paliocolor® LC756) Methyl ethyl ketone: 89.6 parts by mass <Fabrication of the second layer> Using the same materials as the first laminate of Comparative Example 1 and through the same process as the first laminate of Comparative Example 1, a second laminate used in Comparative Example 1 was obtained. However, in the second birefringent layer, the in-plane retardation at a wavelength of 450 nm, the in-plane retardation at a wavelength of 532 nm, and the in-plane retardation at a wavelength of 635 nm were adjusted so as to be in the range of (λ / 2)×0.95 or more and (λ / 2)×1.05 or less by adjusting the amount of the chiral agent in the coating liquid 2 for forming the liquid crystal layer. <Preparation of the First Transfer Film> As the first transfer film used in Comparative Example 1, the same one as the first transfer film of Example 1 was prepared. <Lamination> The first laminate and the second laminate were laminated in the same lamination process as in Example 1 except that they were changed to the first laminate and the second laminate used in Comparative Example 1, to obtain an optical element of Comparative Example 1 having, in this order, a first substrate, a first primer layer, a first alignment layer, a first birefringent layer, a first adhesive layer, a second birefringent layer, a second alignment layer, a second primer layer, and a second substrate, with these layers being in close contact and integrated. The alignment directions of the liquid crystal molecules in the first birefringent layer and the second birefringent layer were made to substantially coincide in the plane direction in which the alignment direction changes stepwise by 180 degrees. The deviation in the plane direction of the alignment regions of the first to second birefringent layers was made less than 300 μm.

[0156] [Comparative Example 2] <Production of the First Laminate> The first laminate used in Comparative Example 2 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to the fifth roll-shaped plate and the thickness of the birefringent layer (total thickness of the four liquid crystal layers) was changed to 4000 nm. Then, the first laminate was used as the optical element of Comparative Example 2. However, in the first birefringent layer, the in-plane retardation at a wavelength of 450 nm, the in-plane retardation at a wavelength of 532 nm, and the in-plane retardation at a wavelength of 635 nm were adjusted so as to be in the range of (λ / 2)×0.95 or more and (λ / 2)×1.05 or less by adjusting the amount of the chiral agent in the coating liquid 1 for forming the liquid crystal layer.

[0157] [Comparative Example 3] <Production of the First Laminate> The first laminate used in Comparative Example 3 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to a fifth roll-shaped plate and the thickness of the birefringence layer (total thickness of the four liquid crystal layers) was changed to 5000 nm. However, in the first birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Fabrication of the second layer> The second laminate used in Comparative Example 3 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to a fourth roll-shaped plate and the thickness of the birefringence layer (total thickness of the four liquid crystal layers) was changed to 5000 nm. However, in the second birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm were in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Preparation of the first transfer film> As the first transfer film used in Comparative Example 1, the same type as the first transfer film used in Example 1 was prepared. <Bonding> Except for changing the first and second laminates to the first and second laminates used in Comparative Example 3, the same bonding process as in Example 1 was used to obtain the optical element of Comparative Example 3, which has a first substrate, a first primer layer, a first orientation layer, a first birefringence layer, a first adhesive layer, a second birefringence layer, a second orientation layer, a second primer layer, and a second substrate in this order, with these layers tightly bonded and integrated. The first and second birefringence layers were arranged so that the direction in which the arrangement direction of liquid crystal molecules changes stepwise by 180 degrees was approximately coincided in the planar direction. The positional displacement in the planar direction of the orientation regions of the first and second birefringence layers was kept to less than 300 μm.

[0158] [Comparative Example 4] <Fabrication of the first laminate> The first laminate used in Comparative Example 4 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to a fifth roll-shaped plate and the thickness of the birefringence layer (total thickness of the four liquid crystal layers) was changed to 4500 nm. However, in the first birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Fabrication of the second layer> A second laminate used in Comparative Example 4 was obtained in the same manner as the first laminate used in Example 1. However, in the second birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase differences at wavelengths of 450 nm, 532 nm, and 635 nm were in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Fabrication of the third layer> A third laminate used in Comparative Example 4 was obtained in the same manner as the first laminate used in Example 1. However, in the third birefringence layer, the amount of chiral agent in the liquid crystal layer forming coating solution 1 was adjusted so that the in-plane phase difference at wavelengths of 450 nm, 532 nm, and 635 nm was in the range of (λ / 2) × 0.95 or more and (λ / 2) × 1.05 or less. <Preparation of the first transfer film> As the first transfer film used in Comparative Example 4, the same type as the first transfer film used in Example 1 was prepared. <Preparing the second transfer film> As the second transfer film used in Comparative Example 4, the same type as the first transfer film used in Example 1 was prepared. The second transfer film used in Comparative Example 4 has, in this order, a peelable first substrate, a second adhesive layer, and a peelable second substrate. <Bonding> Except for changing the first, second, and third laminates to the first and second laminates used in Comparative Example 4, the same bonding process as in Example 8 was used to obtain the optical element of Comparative Example 4, which has the following layers in this order: first substrate, first primer layer, first alignment layer, first birefringence layer, first adhesive layer, second birefringence layer, second alignment layer, second primer layer, second substrate, second adhesive layer, third birefringence layer, third alignment layer, third primer layer, and third substrate, with these layers tightly bonded and integrated. The first, second, and third birefringence layers were arranged so that the direction in which the arrangement direction of liquid crystal molecules changes stepwise by 180 degrees was approximately aligned in the planar direction. The planar positional displacement of the alignment regions of the first to third birefringence layers was kept to less than 300 μm.

[0159] [Comparative Example 5] <Fabrication of the first laminate> The first laminate used in Comparative Example 5 was obtained in the same manner as the first laminate used in Example 1, except that the first roll-shaped plate was changed to a fifth roll-shaped plate and the thickness of the birefringence layer (total thickness of the four liquid crystal layers) was changed to 500 nm. The first laminate was then used as the optical element of Comparative Example 5. The amount of chiral agent in the liquid crystal layer forming coating solution 1 of Comparative Example 5 was the same as in Example 1. The birefringence layer of the optical element of Comparative Example 5 could not achieve a phase difference of λ / 2 over a wide bandwidth.

[0160] [Table 2]

[0161] In Table 2, "P1 min " in the first birefringence layer means that the length P1 until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees is the shortest value. min " in the second birefringence layer means that the length P2 until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees is the shortest value. min This means that in the third birefringence layer, the length P3 until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees is the shortest value.

[0162] As shown in Table 2, the optical element of the example has asin(λ1 / P1) when λ1 is 635 nm. min ) <atan(P1 min The relationship (d) is satisfied. The optical element of the example can achieve a diffraction angle of 20 degrees or more, and it can be confirmed that light leakage can be suppressed at 450 nm (blue), 532 nm (green), and 635 nm (red). On the other hand, the optical elements of Comparative Examples 1 to 4, when λ1 is 635 nm, (λ1 / P1 min ) <atan(P1 min The relationship / d) is not satisfied (for Comparative Examples 1 to 4, the relationship is not satisfied when λ1 is 635 nm, and therefore the relationship is also not satisfied when λ1 is 1550 nm, which is when the value on the left side becomes larger). The optical elements of Comparative Examples 1 to 4 had light leakage exceeding 1.2% in at least one of the wavelength ranges of 450 nm (blue), 532 nm (green), and 635 nm (red), and were unable to suppress light leakage. The optical element in Comparative Example 5 had the following characteristics: "The diffraction angle was increased by using a single-layer birefringence layer, which shortened the orientation pitch of the liquid crystal molecules and made it easier for the orientation of the liquid crystal molecules to decrease," and "When λ1 is 635 nm, asin(635 / P1 min ) <atan(P1 min Although the relationship / d) was satisfied, the thickness of the birefringence layer was made excessively thin to satisfy the aforementioned relationship, which resulted in the inability to obtain a phase difference of λ / 2 over a wide bandwidth, and thus light leakage could not be suppressed. [Explanation of Symbols]

[0163] 10a: First face 10b: Second face 11: First substrate 12: Second base material 21: First orientation layer 22: Second orientation layer 31: First birefringence layer 31r: Liquid crystal layer 32: Second birefringence layer 32r: Liquid crystal layer 41:Adhesive layer 100: Optical element

Claims

1. An optical element, The optical element has a first surface and a second surface opposite to the first surface, and has a first birefringence layer and a second birefringence layer in this order from the first surface toward the second surface. The first birefringence layer and the second birefringence layer are, respectively, wavelength λ １ The in-plane phase difference when the wavelength is 635 nm or 1550 nm is (λ １ / 2)×0.95 or more (λ １ / 2) is within the range of 1.05 or less, The first birefringence layer and the second birefringence layer each include one or more liquid crystal layers in the thickness direction. The first birefringence layer has a plurality of first orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. The second birefringence layer has a plurality of second orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees. In the first birefringence layer, when P1 is defined as the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, at least a portion of the first alignment region's P1 shows a different value from the other first alignment regions' P1. The value of the shortest P1 among the plurality of the first orientation regions is P1 ｍｉｎ An optical element that satisfies the following equation 1, given that the thickness of the first birefringence layer is defined as [nm] and d [nm]. asin(λ １ / P1 ｍｉｎ )<atan(P1 ｍｉｎ / d) Equation 1 [λ in Equation 1] １ This refers to at least one of the wavelengths, 635 nm and 1550 nm, that satisfies the range of the in-plane phase difference.

2. d / P1 ｍｉｎ The optical element according to claim 1, wherein ｍｉｎ is not less than 0.40 and not more than 2.

90.

3. P1 ｍｉｎ The optical element according to claim 1, wherein the wavelength is 200 nm or more and 4000 nm or less.

4. The optical element according to claim 1, wherein, in the second birefringence layer, when P2 is defined as the length until the alignment direction of the liquid crystal molecules changes stepwise by 180 degrees, at least a portion of the second orientation region's P2 exhibits a different value from the other second orientation regions' P2.

5. The optical element according to claim 1, wherein the predetermined direction of the first birefringence layer is a specific one direction of the first birefringence layer, the predetermined direction of the second birefringence layer is a specific one direction of the second birefringence layer, and the specific one direction of the first birefringence layer and the specific one direction of the second birefringence layer are substantially the same direction.

6. In the first birefringence layer, the first orientation region P1 becomes progressively shorter from the first orientation region at one end in a specific direction toward the first orientation region at the other end in the specific direction. The optical element according to claim 5, wherein, in the second birefringence layer, when P2 is defined as the length until the arrangement direction of the liquid crystal molecules changes stepwise by 180 degrees, the P2 of the second orientation region gradually shortens from the second orientation region at one end of the specific direction toward the second orientation region at the other end of the specific direction.

7. The predetermined direction of the first birefringence layer is a radial multidirectional direction with respect to the center of the arrangement pattern of the liquid crystal molecules, The optical element according to claim 1, wherein the predetermined direction of the second birefringence layer is a radial multidirectional direction with respect to the center of the arrangement pattern of the liquid crystal molecules.

8. In the first birefringence layer, P1 gradually shortens from the first orientation region located at the center of the array pattern toward the first orientation region located outside the array pattern. The optical element according to claim 7, wherein when P2 is defined as the length until the alignment direction of the liquid crystal molecules in the alignment region of the second birefringence layer changes by 180 degrees in steps, P2 gradually decreases from the second alignment region located at the center of the alignment pattern toward the second alignment region located outside the alignment pattern.

9. The optical element according to claim 1, wherein the first birefringence layer has a first substrate on the first surface side and the second birefringence layer has a second substrate on the second surface side.

10. The optical element according to claim 9, wherein a first alignment layer is provided between the first substrate and the first birefringence layer, and a second alignment layer is provided between the second substrate and the second birefringence layer.

11. The optical element according to claim 1, wherein one or more layers selected from a positive A layer, a negative A layer, a positive B layer, a negative B layer, and a positive C layer are provided between the first birefringence layer and the second birefringence layer.

12. Furthermore, it has a third birefringence layer, The third birefringence layer includes one or more liquid crystal layers in the thickness direction. The first birefringence layer, the second birefringence layer, and the third birefringence layer are arranged in this order from the first surface toward the second surface. The third birefringence layer has a wavelength λ １ The in-plane phase difference when the wavelength is 635 nm or 1550 nm is (λ １ / 2)×0.95 or more (λ １ / 2) is within the range of 1.05 or less, The optical element according to claim 1, wherein the third birefringence layer has a plurality of third orientation regions along a predetermined direction in the plane in which the alignment direction of liquid crystal molecules changes stepwise by 180 degrees.

13. The optical element according to claim 1, wherein each layer from the first surface to the second surface is in close contact and integrated.

14. The optical element according to claim 13, further comprising an adhesive layer between the first birefringence layer and the second birefringence layer.

15. An optical member comprising an optical element according to any one of claims 1 to 14 and a member to be adhered to, laminated together.

16. An apparatus comprising an optical element according to any one of claims 1 to 14.

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