Retardation optical element and method of manufacturing the same

Abstract

To provide a retardation optical element which can suppress variation in birefringence, and a method of manufacturing the same.SOLUTION: A retardation optical element is provided, comprising a substrate having a curved portion with a first diameter and a second diameter longer than the first diameter in plan view in an optical axis direction, and a retardation film with a fast axis and a slow axis pasted onto a curved surface of the curved portion, where an angle between the fast axis and the first diameter is less than 45° in plan view.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a retardation optical element and a method for manufacturing a retardation optical element. [Background technology]

[0002] In recent years, head mounted displays have been used in various fields such as virtual reality (VR), augmented reality (AR), and mixed reality (MR). The head mounted display has an optical system for focusing an image displayed on the display at the position of the user's eyes. In the head mounted display, a small, lightweight, and high-quality optical system is realized by folding the optical path using circularly polarized light and a half mirror. In addition, the head mounted display needs to be protected from the nose when worn by the user, and the optical elements need to avoid the driving device. For this reason, the shape of the optical elements used in the head mounted display is often not an axisymmetric circle like the optical elements used in digital cameras, but a non-axisymmetric shape such as a shape with a major axis and a minor axis with at least one side cut off. Furthermore, it is known that the head mounted display can be made small and lightweight by manufacturing an element in which a film having optical properties such as a polarizing film, a polarizing beam splitter (PBS) film, and a retardation film is bonded to a substrate having a curved surface.

[0003] Patent Document 1 discloses an optical element in which a retardation film or the like is laminated and fixed via an adhesive or the like. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-220853 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a retardation optical element in which a retardation film is attached to a curved substrate such as the optical element disclosed in Patent Document 1, the retardation, or so-called birefringence, fluctuates in the periphery of the retardation optical element. In particular, in a retardation film manufactured by uniaxial stretching, the film elongation rate differs between the fast axis direction and the slow axis direction of the retardation film, so the film elongates more in the direction parallel to the fast axis. Therefore, there is a problem that the fluctuation of the birefringence in the fast axis direction of the retardation film becomes larger.

[0006] An object of the present invention is to provide a retardation optical element capable of suppressing fluctuations in birefringence and a method for manufacturing a retardation optical element. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided a retardation optical element comprising: a substrate having a curved portion having a first diameter and a second diameter longer than the first diameter when viewed in a plane in the optical axis direction; and a retardation film having a fast axis and a slow axis and attached to the curved surface of the curved portion, wherein an angle between the fast axis and the first diameter is smaller than 45° when viewed in the plane.

[0008] According to another aspect of the present invention, there is provided a method for manufacturing a retardation optical element, comprising: arranging a substrate having a curved portion having a first diameter and a second diameter longer than the first diameter in a planar view seen in the optical axis direction; arranging a retardation film having a fast axis and a slow axis such that an angle between the fast axis and the first diameter in the planar view is smaller than 45°; and attaching the retardation film to the curved surface of the curved portion.

[0009] According to another aspect of the present invention, there is provided a method for manufacturing a retardation optical element, comprising: disposing a substrate having a curved portion; attaching a retardation film having a fast axis and a slow axis to the curved surface of the curved portion; and cutting off at least one end portion of the substrate including the curved portion in a direction such that the angle with the fast axis is smaller than 45° when viewed in a plane in the optical axis direction. Effect of the Invention

[0010] According to the present invention, it is possible to suppress the variation in birefringence in a retardation optical element. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing a retardation optical element according to a first embodiment of the present invention. [Figure 2A] 5A to 5C are schematic diagrams showing modified examples of the shape of the substrate in the retardation optical element according to the first embodiment of the present invention. [Figure 2B] 5A to 5C are schematic diagrams showing modified examples of the shape of the substrate in the retardation optical element according to the first embodiment of the present invention. [Figure 2C] 5A to 5C are schematic diagrams showing modified examples of the shape of the substrate in the retardation optical element according to the first embodiment of the present invention. [Figure 3A] 1A to 1C are schematic diagrams illustrating a method for manufacturing a retardation optical element according to a first embodiment of the present invention. [Figure 3B] 1A to 1C are schematic diagrams illustrating a method for manufacturing a retardation optical element according to a first embodiment of the present invention. [Figure 3C] 1A to 1C are schematic diagrams illustrating a method for manufacturing a retardation optical element according to a first embodiment of the present invention. [Figure 3D] 1A to 1C are schematic diagrams illustrating a method for manufacturing a retardation optical element according to a first embodiment of the present invention. [Figure 3E] 1A to 1C are schematic diagrams illustrating a method for manufacturing a retardation optical element according to a first embodiment of the present invention. [Figure 3F] 1A to 1C are schematic diagrams illustrating a method for manufacturing a retardation optical element according to a first embodiment of the present invention. [Figure 3G] 1A to 1C are schematic diagrams illustrating a method for manufacturing a retardation optical element according to a first embodiment of the present invention. [Figure 3H] 1A to 1C are schematic diagrams illustrating a method for manufacturing a retardation optical element according to a first embodiment of the present invention. [Figure 4A] FIG. 2 is a schematic diagram showing a substrate used in the retardation optical elements according to Examples 1 to 7 of the present invention. [Figure 4B] FIG. 2 is a schematic diagram showing a retardation film used in the retardation optical elements according to Examples 1 to 7 of the present invention. [Figure 4C] FIG. 2 is a schematic diagram showing the arrangement of retardation films relative to substrates when the retardation optical elements of Examples 1 to 7 of the present invention are produced. [Figure 5A] FIG. 2 is a schematic diagram showing a substrate used in the retardation optical elements of Examples 8 to 10 of the present invention. [Figure 5B] FIG. 1 is a schematic diagram showing the arrangement of retardation films relative to substrates when retardation optical elements according to Examples 8 to 10 of the present invention are produced. [Figure 6A] FIG. 13 is a schematic diagram showing a substrate used in the retardation optical element of Example 11 of the present invention. [Figure 6B] FIG. 15 is a schematic diagram showing the arrangement of a retardation film relative to a substrate when a retardation optical element according to Example 11 of the present invention is produced. [Figure 7A] FIG. 15 is a schematic diagram showing a substrate used in the retardation optical element of Example 12 of the present invention. [Figure 7B] FIG. 16 is a schematic diagram showing the arrangement of a retardation film relative to a substrate when a retardation optical element according to Example 12 of the present invention is produced. [Figure 8A] FIG. 4 is a schematic diagram showing a display device according to a second embodiment of the present invention. [Figure 8B] FIG. 4 is a schematic diagram showing a display device according to a second embodiment of the present invention. [Figure 8C] FIG. 4 is a schematic diagram showing a display device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [First embodiment] A retardation optical element and a method for manufacturing a retardation optical element according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3H.

[0013] First, the retardation optical element according to this embodiment will be described with reference to FIGS. 1 to 2C. The retardation optical element according to this embodiment is an optical element having a function of providing a phase difference between polarization components of incident light that are orthogonal or intersect with each other and then emitting the light. By providing a phase difference between the polarization components, the retardation optical element can convert incident circularly polarized light into linearly polarized light, convert incident linearly polarized light into circularly polarized light, or change the polarization state of the incident light.

[0014] FIG. 1 is a schematic diagram showing the retardation optical element 10 according to this embodiment. In FIG. 1, the left figure is a plan view showing the retardation optical element 10 in a plan view as seen in the direction in which light is incident on the retardation optical element 10, and the right figure is a cross-sectional view showing a cross-section of the retardation optical element 10 along the minor axis 11c described later.

[0015] As shown in FIG. 1, the retardation optical element 10 according to this embodiment includes a substrate 11 and a retardation film 12. The substrate 11 has a curved surface portion 11a located at the center and a peripheral portion 11b provided adjacent to the curved surface portion 11a at the periphery of the curved surface portion 11a. The retardation film 12 is provided by being attached to the curved surface of the curved surface portion 11a.

[0016] The curved surface portion 11a has an axially asymmetric shape in a plan view as seen in the optical axis direction of the substrate 11, and has a minor axis 11c and a major axis 11d that is longer than the minor axis 11c. The optical axis direction of the substrate 11 is the optical axis direction of the retardation optical element 10, which is the direction in which light is incident on the retardation optical element 10. The minor axis 11c is the shortest diameter among the diameters passing through the reference point of the shape of the substrate 11 in a plan view. The major axis 11d is the longest diameter among the diameters passing through the reference point of the shape of the substrate 11 in a plan view. Specifically, the curved surface portion 11a has an oval shape surrounded by an arc that is a part of the circumference of a circle and a line connecting both ends of the arc in a plan view as seen in the optical axis direction of the substrate 11. The line connecting both ends of the arc is, for example, a straight line, but may also be a curve, a bent line, or the like. In this case, the minor axis 11c is the shortest diameter among the diameters passing through the center point O of the circle of the arc of the curved surface portion 11a in a plan view with the center point O as the reference point. Also, the major axis 11d is the longest diameter among the diameters passing through the center point O of the circle of the arc of the curved surface portion 11a in a plan view with the center point O as the reference point. The minor axis 11c and the major axis 11d do not necessarily have to be perpendicular to each other.

[0017] The substrate 11 can function as a lens by the curved surface portion 11a. The curved surface to which the retardation film 12 of the curved surface portion 11a is attached has a convex or concave shape, and may be a spherical shape or an aspherical shape. The surface on the side opposite to the curved surface to which the retardation film 12 of the curved surface portion 11a is attached may be a flat surface, or may be a convex or concave curved surface. In the case of a curved surface, it may be a spherical shape or an aspherical shape.

[0018] The peripheral portion 11b is an optically ineffective region. For example, the peripheral portion 11b may be provided as a mold release margin when manufacturing the substrate 11, particularly when manufacturing the substrate 11 by injection molding, or may be provided for mounting to a housing of an optical device such as a head-mounted display. The peripheral portion 11b may be curved or flat, and may have an axisymmetric shape or a non-axisymmetric shape. In addition, the peripheral portion 11b does not need to be provided around the entire circumference of the curved portion 11a, and may be provided on a part of the entire circumference of the curved portion 11a. In some cases, the peripheral portion 11b may not be provided.

[0019] The shape of the substrate 11 in plan view in the optical axis direction of the substrate 11 is not limited to the shape shown in Fig. 1. Figures 2A to 2C are plan views showing other examples of the shape of the substrate 11 in plan view in the optical axis direction of the substrate 11.

[0020] In the case of the substrate 11 shown in Fig. 2A, in plan view, the curved surface portion 11a has a shape surrounded by two opposing arcs and two opposing parallel sides that respectively connect two sets of opposing ends of the two arcs. The two arcs are part of the circumference of the same circle. In this case, the substrate 11 has a peripheral portion 11b that is provided to have a circular outer shape in plan view.

[0021] In the case of the substrate 11 shown in FIG. 2B, in a plan view, the curved surface portion 11a has a shape surrounded by two sides that do not face each other and face in different directions, and two arcs that connect two adjacent sets of ends of these two sides. The two arcs are part of the circumference of the same circle. In this case, the substrate 11 has a peripheral portion 11b that is provided with the same width on the outer periphery of the curved surface portion 11a in a plan view. Note that the curved surface portion 11a may have multiple sides, three or more sides, in addition to two sides, in a plan view. In this case, the curved surface portion 11a has three or more multiple arcs that are each part of the same circumference in a plan view, and it is sufficient that two adjacent ends of two sides in the multiple sides are connected by an arc.

[0022] 2A and 2B, the minor axis 11c is the shortest diameter among the diameters that pass through the center point O of the circle of the arc of the curved surface portion 11a in plan view as a reference point. In these cases, the major axis 11d is the longest diameter among the diameters that pass through the center point O of the circle of the arc of the curved surface portion 11a in plan view as a reference point.

[0023] In the case of the substrate 11 shown in Fig. 2C, in a plan view, the curved surface portion 11a has a shape having a plurality of arcs with different curvatures, such as a spectacle lens. In this case, the substrate 11 can be configured not to have a peripheral portion 11b. In this case, the minor axis 11c is the shortest diameter among the diameters passing through the center of gravity G of the shape of the curved surface portion 11a in a plan view as a reference point, and the major axis 11d is the longest diameter among the diameters passing through the center of gravity G of the shape of the curved surface portion 11a in a plan view as a reference point.

[0024] In an optical device using the retardation optical element 10, particularly a head mounted display, the size of the device is restricted because it is expected to be worn on the user's face, particularly around the eyes and nose. Therefore, in order to protect the user's nose and to ensure installation space for electronic devices such as motors and sensors, the shape of the substrate 11 is often not axially symmetric but rather asymmetrical having a minor axis and a major axis.

[0025] The material of the substrate 11 may be a transparent material, regardless of plastic or glass, that is transparent to light such as visible light that is the target of the retardation optical element 10. In the case of plastic, it is preferable that it can be molded by injection molding and is used optically. In addition, it is preferable that the material has a small birefringence. The value of birefringence is, for example, 30×10 -5 It is preferable that the number of the particles is less than or equal to 12×10 -5Specifically, examples of the plastic material of the substrate 11 include polycarbonate (PC), polyester (PEs), polymethyl methacrylate (PMMA), cycloolefin polymer (COP), cycloolefin copolymer (COC), etc. In the case of glass, there is no particular restriction on the material, but examples include synthetic quartz and the general glass material BK-7.

[0026] As shown in FIG. 1, the retardation film 12 is attached to the curved surface of the curved portion 11a of the substrate 11 via an adhesive layer 13. The retardation film 12 is made by stretching a film made of, for example, COP, COC, or PC in a certain direction, although it is not particularly limited thereto. The retardation film 12 has a fast axis 12a and a slow axis 12b perpendicular to the fast axis 12a, and can delay the phase of light incident parallel to the slow axis 12b by a certain wavelength and emit the light. The directions of the fast axis 12a and the slow axis 12b can be confirmed, for example, from the orientation angle calculated when birefringence measurement is performed. At this time, the direction of the orientation angle of 0° is the direction of the fast axis 12a, and the direction perpendicular to the direction of the fast axis 12a is the direction of the slow axis 12b. The retardation film 12 has different film elongation rates in the directions of the fast axis 12a and the slow axis 12b, and specifically, is more easily elongated in the direction of the fast axis 12a than in the direction of the slow axis 12b. The retardation film 12 is stretched as described below and provided on the curved surface of the curved portion 11a.

[0027] Examples of the retardation film 12 include, but are not limited to, a 1 / 2 wavelength film, a 1 / 4 wavelength film, etc. The 1 / 2 wavelength film is a film that can delay the phase of light incident parallel to the slow axis 12b by a half wavelength. The 1 / 4 wavelength film is a film that can delay the phase of light incident parallel to the slow axis 12b by a quarter wavelength.

[0028] Incidentally, the retardation film 12 made of COP or COC is known to have a small change in birefringence with respect to the stretching of the film, but has a weak adhesive force with the adhesive layer 13 and is inferior in adhesive strength with the substrate 11. On the other hand, the retardation film 12 made of PC is known to have a large change in birefringence with respect to the stretching of the film, but has a strong adhesive force with the adhesive layer 13 and is superior in adhesive strength with the substrate 11.

[0029] The retardation film 12 is attached to the substrate 11 so that the angle between the fast axis 12a and the minor axis 11c of the curved surface portion 11a is smaller than 45° in plan view in the optical axis direction of the substrate 11. Since the angle between the fast axis 12a and the minor axis 11c is small, the length of the curved surface portion 11a in the direction of the fast axis 12a in which the retardation film 12 is likely to stretch is shorter. As a result, in the retardation optical element 10 according to the present embodiment, the retardation film 12 is attached to the curved surface portion 11a of the substrate 11 without excessive stretching, so that the variation in birefringence can be suppressed. From the viewpoint of further suppressing the variation in birefringence, it is preferable that the retardation film 12 is attached to the substrate 11 so that the angle between the fast axis 12a and the minor axis 11c of the curved surface portion 11a is within 30° in plan view in the optical axis direction of the substrate 11. More preferably, the fast axis 12a is attached to the substrate 11 so that the fast axis 12a and the minor axis 11c of the curved surface portion 11a are substantially parallel in a plan view in the optical axis direction of the substrate 11. "Substantially parallel" means that the angle between the fast axis 12a and the minor axis 11c of the curved surface portion 11a is in the range of ±2°, including 0°. If the angle between the fast axis 12a and the minor axis 11c is 45° or more, the length of the curved surface portion 11a in the direction of the fast axis 12a is not sufficiently short, and suppression of fluctuations in birefringence cannot be expected.

[0030] Here, when the radius of curvature of the curved surface of curved portion 11a to which retardation film 12 is attached is R and the length of major axis 11d of curved portion 11a is L2, the half open angle θ of the curved surface of curved portion 11a is defined by the following formula 1. When the curved surface of curved portion 11a is aspheric, the radius of curvature R can be an optimal value, an approximate value, or the like obtained by optimal fitting using the least squares method. sinθ=(L2 / 2) / R (Equation 1)

[0031] The half aperture angle θ can be set appropriately depending on the design of the substrate 11 functioning as a lens, but it is preferable that 0°<θ≦30° from the viewpoint of the substrate 11 functioning as a lens.

[0032] Furthermore, if the length of the minor axis 11c of the curved surface portion 11a is L1 and the angle between the fast axis 12a and the minor axis 11c is φ, it is preferable that the length L1 of the minor axis 11c and the length L2 of the major axis 11d satisfy the following formula 2 for the half opening angle θ in the range 10°≦θ≦30°. 0.2≦(L1 / cosφ) / L2≦-0.023×θ+1.2 (Formula 2)

[0033] Equation 2 indicates that the larger the half-open angle θ, the more the retardation film 12 needs to be stretched and attached, and that in order to suppress the variation in birefringence, it is preferable to reduce the ratio of the length L1 of the minor axis 11c to the length L2 of the major axis 11d. In other words, Equation 2 indicates that the larger the half-open angle θ, the more preferably the length L1 of the minor axis 11c is made shorter.

[0034] Next, a method for manufacturing the retardation optical element 10 according to the present embodiment will be described with reference to Figs. 3A to 3H. The upper view of Fig. 3A and Figs. 3E to 3H are cross-sectional views showing a method for manufacturing the retardation optical element 10 according to the present embodiment. The lower view of Fig. 3A is a plan view showing the substrate 11 and the retardation film 12 in the step shown in the upper view of Fig. 3A, and is a plan view seen in a direction perpendicular to the film surface of the retardation film 12. Figs. 3B to 3D are cross-sectional views showing examples of the form of the retardation film 12 when it is attached to the substrate 11.

[0035] First, as shown in FIG. 3A, a substrate 11 having a minor axis 11c and a major axis 11d is prepared by being placed in a first chamber 33. The substrate 11 is placed on a stage 32 having a lifting mechanism in the first chamber 33. A second chamber 34 is placed above the first chamber 33. An opening that can connect the first chamber 33 and the second chamber 34 is provided at the top of the first chamber 33 and the bottom of the second chamber 34, respectively. A retardation film 12 is placed between the first chamber 33 and the second chamber 34 that are connected through these openings. At this time, the retardation film 12 is placed so as to face the substrate 11. In addition, a uniform adhesive layer 13 (see FIGS. 3B to 3D) is provided on the surface of the retardation film 12 on the substrate 11 side.

[0036] In the above arrangement, the retardation film 12 is arranged so that, in a plan view seen in the optical axis direction of the substrate 11, the angle between the minor axis 11c of the curved portion 11a of the substrate 11 and the fast axis 12a of the retardation film 12 is smaller than 45°, preferably within 30°, and more preferably the minor axis 11c and the fast axis 12a are approximately parallel. By doing so, as described later, when the retardation film 12 is attached to the substrate 11, the length of the curved portion 11a in the direction of the fast axis 12a in which the retardation film 12 is more likely to stretch is shortened. This makes it possible to prevent the excessively stretched retardation film 12 from being attached to the curved surface of the curved portion 11a of the substrate 11, and to suppress the variation in birefringence.

[0037] In addition, in the above arrangement, it is preferable to arrange the substrate 11 at an incline so that the tangent at the center point of the minor axis 11c of the curved surface portion 11a of the substrate 11 is parallel to the retardation film 12. The means for arranging the substrate 11 at an incline is not particularly limited, but for example, the substrate 11 can be arranged at an incline by installing a pedestal 32a having an inclined surface on the stage 32 and arranging the substrate 11 on the incline. In addition, instead of arranging the substrate 11 at an incline, the retardation film 12 may be arranged at an incline so that the tangent at the center point of the minor axis 11c of the curved surface portion 11a is parallel to the retardation film 12. This allows the retardation film 12 to be attached more evenly to the curved surface portion 11a. Therefore, it is possible to more reliably prevent the excessively stretched retardation film 12 from adhering to the curved surface portion 11a of the substrate 11, and to further suppress the variation in birefringence.

[0038] 3B, the retardation film 12 may have a protective film 14 provided on the surface of the retardation film 12 opposite to the substrate 11. In this case, the glass transition temperature of the protective film 14 is preferably lower than the glass transition temperature of the retardation film 12. This increases the strength of the retardation film 12, making it less likely that the retardation film 12 will break when attached to the substrate 11.

[0039] In addition, the retardation film 12 is more expensive than a general film. For this reason, the retardation film 12 may have a size slightly larger than the area of the curved surface portion 11a of the substrate 11. Specifically, for example, the retardation film 12 may have an area 1.5 to 2.5 times the area of the curved surface portion 11a in a plan view as seen in the optical axis direction of the substrate 11. In this case, in order to ensure the size required for arranging the retardation film 12 between the first chamber 33 and the second chamber 34, as shown in FIG. 3C, a support film 37 made of a member different from the retardation film 12 may be attached onto the retardation film 12. At this time, in order to make the deflection of the film uniform when the film is heated, the glass transition temperature of the support film 37 is preferably equal to the glass transition temperature of the retardation film 12 or about 20° C. lower.

[0040] Also, as shown in FIG. 3D, the support film 37 may be attached only to the outer peripheral portion of the retardation film 12. Note that the support film 37 can be peeled off from the retardation film 12 at an appropriate timing after the retardation film 12 is attached to the substrate 11.

[0041] Next, as shown in FIG. 3E, the opening of the first chamber 33 and the opening of the second chamber 34 are connected such that the retardation film 12 is interposed therebetween. Subsequently, the inside of the first chamber 33 and the inside of the second chamber 34 are evacuated, and the retardation film 12 is heated. Here, the heating method of the retardation film 12 is not particularly limited, and examples thereof include a method using an infrared heater that directly heats the retardation film 12, and a method of heating the entire first chamber 33 and the second chamber 34 with a heater or the like. However, in the case of the latter method, the substrate 11 is also heated. When the substrate 11 is heated, particularly when the material of the substrate 11 is a plastic material, deformation of the substrate 11 due to heat is a concern. Therefore, when the substrate 11 is heated, it is important to make the pedestal 32a or the like of the substrate 11 have a heat-insulating structure, and it is preferable to keep the temperature of the substrate 11 at 120° C. or lower regardless of the temperature of the retardation film 12.

[0042] Next, after the retardation film 12 is heated to a desired temperature, as shown in FIG. 3F, the position of the substrate 11 is raised by a stage 32 having a lifting function until the adhesive layer 13 of the retardation film 12 contacts the curved surface portion 11a of the substrate 11. Next, only the second chamber 34 is opened to the atmosphere to increase the pressure therein, and further, as necessary, high-pressure gas is introduced into the second chamber 34 to pressurize the retardation film 12 and press it against the substrate 11 including the curved surface portion 11a. As a result, the retardation film 12 is attached to the curved surface of the curved surface portion 11a of the substrate 11. The retardation film 12 is stretched by being pressed against the curved surface portion 11a and provided on the curved surface of the curved surface portion 11a. If necessary, the heating and pressurization of the retardation film 12 may be continued for a certain period of time.

[0043] Next, as shown in FIG. 3G, the heating and pressurization of the retardation film 12 are stopped, the inside of the second chamber is returned to atmospheric pressure, and then the inside of the first chamber 33 is also opened to the atmosphere.

[0044] Next, the retardation film 12 and the substrate 11 to which it is attached are taken out from the first chamber 33 and the second chamber 34. Next, as shown in FIG. 3H, the unnecessary retardation film 12 is cut off together with the adhesive layer 13 so as to leave only the retardation film 12 on the curved surface portion 11a of the substrate 11. The cutting method includes a method of cutting off the unnecessary retardation film 12 by applying a blade to the retardation film 12 along the outer edge of the curved surface portion 11a, and a method of cutting off the unnecessary retardation film 12 by applying a laser beam to the retardation film 12 along the outer edge of the curved surface portion 11a. In this manner, the retardation optical element 10 in which the retardation film 12 is attached to the curved surface portion 11a of the substrate 11 is manufactured.

[0045] The method for manufacturing the retardation optical element 10 is not limited to the manufacturing method shown in FIGS. 3A to 3H, and the retardation optical element 10 can be manufactured by other manufacturing methods.

[0046] For example, as in Example 11 described later, after the retardation film 12 is attached to the curved surface portion 11a of the substrate 11 in which there is no distinction between the minor axis 11c and the major axis 11d, a predetermined end portion including the curved surface portion 11a of the substrate 11 can be cut off to manufacture the retardation optical element 10 according to this embodiment. In this case, first, the substrate 11 having the curved surface portion 11a of an axisymmetric planar shape such as a perfect circle shape in which there is no distinction between the minor axis 11c and the major axis 11d in a plan view seen in the optical axis direction of the substrate 11 is arranged and prepared. Next, the retardation film 12 is attached to the curved surface of the curved surface portion 11a. The retardation film 12 can be attached in the same manner as the above-mentioned manufacturing method. Next, at least one end portion including the curved surface portion 11a of the substrate 11 is cut off together with the retardation film 12 attached to the end portion in a direction in which the angle between the retardation film 12 and the fast axis 12a in a plan view seen in the optical axis direction of the substrate 11 is smaller than 45°. The direction in which at least one end of the substrate 11 including the curved surface portion 11a is cut off is preferably substantially parallel to the fast axis 12a. In this manner, the retardation optical element 10 according to this embodiment can also be manufactured.

[0047] Thus, according to this embodiment, even when a retardation film 12 having different film elongation rates in the directions of the fast axis 12a and the slow axis 12b is attached to the curved surface of the curved surface portion 11a, it is possible to prevent an excessively elongated retardation film 12 from being attached to the curved surface. Therefore, according to this embodiment, it is possible to suppress the variation in birefringence even in the peripheral portion of the retardation optical element 10. Thus, according to this embodiment, it is possible to suppress the variation in birefringence of the retardation optical element 10.

[0048] The retardation optical element 10 can be evaluated, for example, by measuring the birefringence. In this evaluation, the birefringence value RET1 of the retardation film 12 alone and the birefringence value RET2 of the retardation optical element 10 are measured, and the evaluation can be performed based on the rate of change of birefringence from RET1 to RET2 (RET1-RET2) / RET1. Specifically, for example, when the rate of change of birefringence is ±10% or less, it can be evaluated as good because it does not have a significant effect on optical performance, and when the rate of change of birefringence is ±8% or less, it can be evaluated as even better or excellent. The value of birefringence can be measured, for example, by a retardation measuring device KOBRA (manufactured by Oji Scientific Instruments).

[0049] [Example] Next, the retardation optical element 10 according to the first embodiment and the method for manufacturing the retardation optical element 10 will be specifically described using examples.

[0050] Example 1 The retardation optical element 10 of the first embodiment and a method for manufacturing the retardation optical element 10 will be described with reference to FIGS. 3A to 4C.

[0051] First, in Example 1, a substrate 11 made of plastic mainly composed of cycloolefin copolymer (COC) molded by injection molding was prepared. Fig. 4A shows the substrate 11 prepared in Example 1, with the left figure being a plan view showing the substrate 11 in a plan view seen in the optical axis direction of the substrate 11, and the right figure being a cross-sectional view showing the cross section of the substrate 11 along the minor axis 11c. As shown in Fig. 4A, the substrate 11 was a convex lens with a length L1 of the minor axis 11c of the curved surface portion 11a of 30 mm, a length L2 of the major axis 11d of 50 mm, and a half opening angle θ of 20°, and did not have a peripheral portion 11b.

[0052] On the other hand, a 1 / 4 wavelength film was prepared as the retardation film 12. FIG. 4B shows the retardation film 12 prepared in Example 1, with the upper figure being a plan view showing the retardation film 12 in a plan view seen in a direction perpendicular to the film surface, and the lower figure being a cross-sectional view showing the cross section of the retardation film 12 along the fast axis 12a. As shown in FIG. 4B, the retardation film 12 was a 1 / 4 wavelength film having a square planar shape of 160 mm×160 mm and a thickness of about 0.1 mm, with an adhesive layer 13 provided on one surface.

[0053] Next, as shown in FIG. 3A, the substrate 11 was placed in the first chamber 33, and the retardation film 12 was placed between the first chamber 33 and the second chamber 34. At this time, the retardation film 12 was placed so as to face the substrate 11 with the adhesive layer 13 facing the substrate 11. FIG. 4C is a plan view showing the arrangement of the retardation film 12 with respect to the substrate 11 in Example 1, and is a plan view seen in a direction perpendicular to the film surface of the retardation film 12. As shown in FIG. 4C, the retardation film 12 was placed so that the minor axis 11c of the curved surface portion 11a of the substrate 11 and the fast axis 12a of the retardation film 12 were parallel (angle φ was 0°).

[0054] Next, as shown in FIG. 3E, the first chamber 33 and the second chamber 34 were evacuated, and the retardation film 12 arranged between the first chamber 33 and the second chamber 34 was heated by an infrared heater.

[0055] Next, the retardation film 12 was heated to 100° C., and then, as shown in FIG. 3F, the position of the substrate 11 was raised by the stage 32 until the curved surface portion 11a of the substrate 11 contacted the adhesive layer 13 of the retardation film 12. Then, only the inside of the second chamber 34 was opened to the atmosphere. Thereafter, compressed air was introduced into the second chamber 34 to increase the pressure inside the second chamber 34 to 0.3 MPa, and the retardation film 12 was pressurized and pressed against the substrate 11 for 10 seconds.

[0056] Next, as shown in FIG. 3G, the heating and pressurization of the retardation film 12 were stopped, the second chamber was returned to atmospheric pressure, and the first chamber 33 was also opened to the atmosphere.

[0057] Next, as shown in Fig. 3H, the retardation film 12 and the substrate 11 to which it was attached were taken out from the first chamber 33 and the second chamber 34. Next, the unnecessary retardation film 12 was cut off together with the adhesive layer 13 by applying a blade to the retardation film 12 along the outer edge of the curved portion 11a so as to leave only the retardation film 12 on the curved portion 11a of the substrate 11. In this manner, a retardation optical element 10 in which the retardation film 12 was attached to the curved portion 11a of the substrate 11 was manufactured.

[0058] The retardation optical element 10 of Example 1 was evaluated by measuring the birefringence using a retardation measuring device KOBRA. The birefringence value RET1 of the retardation film 12 alone and the value RET2 of the portion where the birefringence of the retardation optical element 10 changed the most were measured, and the rate of change in birefringence (RET1-RET2) / RET1 was calculated from these, and the rate of change in birefringence was 8%. Therefore, the retardation optical element 10 of Example 1 was evaluated as excellent as shown in Table 1.

[0059] Example 2 In Example 2, the shape of the substrate 11 in Example 1 was changed, and in the shape of the substrate 11 shown in Fig. 4A, the length L1 of the minor axis 11c of the curved portion 11a was set to 35 mm, the length L2 of the major axis 11d was set to 50 mm, and the curved portion 11a was set to a convex lens with a half opening angle θ of 12°. Except for the change in the shape of the substrate 11, the retardation optical element 10 in Example 2 was manufactured in the same manner as in Example 1.

[0060] The retardation optical element 10 of Example 2 was evaluated in the same manner as in Example 1, and the rate of change in birefringence was 5%. Therefore, the retardation optical element 10 of Example 2 was evaluated as excellent as shown in Table 1.

[0061] Example 3 In Example 3, the shape of the substrate 11 in Example 1 was changed, and in the shape of the substrate 11 shown in Fig. 4A, the length L1 of the minor axis 11c of the curved portion 11a was set to 25 mm, the length L2 of the major axis 11d was set to 50 mm, and the curved portion 11a was set to a convex lens with a half opening angle θ of 30°. Except for the change in the shape of the substrate 11, in Example 3 as well, a retardation optical element 10 was manufactured in the same manner as in Example 1.

[0062] The retardation optical element 10 of Example 3 was evaluated in the same manner as in Example 1, and the rate of change in birefringence was 10%. Therefore, the retardation optical element 10 of Example 3 was evaluated as being good, as shown in Table 1.

[0063] Example 4 In Example 4, the shape of the substrate 11 in Example 1 was changed, and in the shape of the substrate 11 shown in Fig. 4A, the length L1 of the minor axis 11c of the curved portion 11a was set to 35 mm, the length L2 of the major axis 11d was set to 50 mm, and the curved portion 11a was set to a convex lens with a half opening angle θ of 20°. Except for the change in the shape of the substrate 11, in Example 4 as well, a retardation optical element 10 was manufactured in the same manner as in Example 1.

[0064] The retardation optical element 10 of Example 4 was evaluated in the same manner as in Example 1, and the rate of change in birefringence was 10%. Therefore, the retardation optical element 10 of Example 4 was evaluated as being good, as shown in Table 1.

[0065] Example 5 In Example 5, the shape of the substrate 11 in Example 1 was changed, and in the shape of the substrate 11 shown in Fig. 4A, the length L1 of the minor axis 11c of the curved portion 11a was set to 48 mm, the length L2 of the major axis 11d was set to 50 mm, and the curved portion 11a was set to a convex lens with a half opening angle θ of 10°. Except for changing the shape of the substrate 11, in Example 5 as well, a retardation optical element 10 was manufactured in the same manner as in Example 1.

[0066] The retardation optical element 10 of Example 5 was evaluated in the same manner as in Example 1, and the change rate of birefringence was 7%. Therefore, the retardation optical element 10 of Example 5 was evaluated as excellent as shown in Table 1.

[0067] Example 6 In Example 6, the shape of the substrate 11 in Example 1 was changed, and in the shape of the substrate 11 shown in Fig. 4A, the length L1 of the minor axis 11c of the curved portion 11a was 10 mm, the length L2 of the major axis 11d was 50 mm, and the curved portion 11a was a convex lens with a half opening angle θ of 20°. Except for the change in the shape of the substrate 11, the retardation optical element 10 in Example 6 was manufactured in the same manner as in Example 1.

[0068] The retardation optical element 10 of Example 6 was evaluated in the same manner as in Example 1, and the change rate of birefringence was 8%. Therefore, the retardation optical element 10 of Example 6 was evaluated as excellent as shown in Table 1.

[0069] Example 7 In Example 7, the shape of the substrate 11 in Example 1 was changed, and in the shape of the substrate 11 shown in Fig. 4A, the length L1 of the minor axis 11c of the curved portion 11a was set to 30 mm, the length L2 of the major axis 11d was set to 50 mm, and the curved portion 11a was made into a concave lens with a half opening angle θ of 20°. Except for the change in the shape of the substrate 11, in Example 7, the retardation optical element 10 was manufactured in the same manner as in Example 1.

[0070] The retardation optical element 10 of Example 7 was evaluated in the same manner as in Example 1, and the change rate of birefringence was 8%. Therefore, the retardation optical element 10 of Example 7 was evaluated as excellent as shown in Table 1.

[0071] Example 8 In Example 8, a substrate 11 having the shape shown in FIG. 5A was prepared. FIG. 5A shows the substrate 11 prepared in Example 8. The left figure is a plan view of the substrate 11 as viewed in the optical axis direction of the substrate 11, and the right figure is a cross-sectional view showing a cross-section of the substrate 11 along the minor axis 11c. As shown in FIG. 5A, in plan view, the curved surface portion 11a of the substrate 11 has two arcs facing each other and two parallel sides facing each other that connect two sets of opposite ends of these two arcs, and has a peripheral portion 11b adjacent to the curved surface portion 11a. In Example 8, the length L1 of the minor axis 11c of the curved surface portion 11a was 28 mm, the length L2 of the major axis 11d was 40 mm, and the curved surface portion 11a was a convex lens with a semi-aperture angle θ of 20°. Further, as the peripheral portion 11b, a flat peripheral portion 11b with an outer diameter of 46 mm was provided. Except for changing the shape of the substrate 11, in Example 8 as well, the retardation optical element 10 was manufactured in the same manner as in Example 1. Note that FIG. 5B is a plan view showing the arrangement of the retardation film 12 with respect to the substrate 11 in Example 8, and is a plan view as viewed in a direction perpendicular to the film surface of the retardation film 12. As shown in FIG. 5B, the retardation film 12 was arranged such that the minor axis 11c of the curved surface portion 11a of the substrate 11 and the fast axis 12a of the retardation film 12 were parallel (angle φ was 0°). Note that in FIG. 5B, for ease of viewing, the angle φ is emphasized and shown large.

[0072] As an evaluation of the retardation optical element 10 of Example 8, the same evaluation as in Example 1 was performed, and the change rate of birefringence was 10%. Therefore, as shown in Table 1, the retardation optical element 10 of Example 8 was evaluated to be good.

[0073] (Example 9) In Example 9, the shape of the substrate 11 in Example 8 was changed, and in the shape of the substrate 11 shown in FIG. 5A, the length L1 of the minor axis 11c of the curved surface portion 11a was set to 35 mm, the length L2 of the major axis 11d was set to 45 mm, and the curved surface portion 11a was set to a convex lens with a half-open angle θ of 12°. In addition, a flat peripheral portion 11b with an outer diameter of 50 mm was provided as the peripheral portion 11b. In Example 9, the retardation optical element 10 was manufactured in the same manner as in Example 8, except that the shape of the substrate 11 was changed and the angle φ between the fast axis 12a of the retardation film 12 and the minor axis 11c of the curved surface portion 11a was set to 20°.

[0074] The retardation optical element 10 of Example 9 was evaluated in the same manner as in Example 1, and the rate of change in birefringence was 5%. Therefore, the retardation optical element 10 of Example 9 was evaluated as excellent as shown in Table 1.

[0075] Example 10 In Example 10, the shape of the substrate 11 in Example 8 was changed, and in the shape of the substrate 11 shown in FIG. 5A, the length L1 of the minor axis 11c of the curved surface portion 11a was set to 35 mm, the length L2 of the major axis 11d was set to 45 mm, and the curved surface portion 11a was set to a convex lens with a half-open angle θ of 20°. In addition, a flat peripheral portion 11b with an outer diameter of 50 mm was provided as the peripheral portion 11b. In Example 10, the retardation optical element 10 was manufactured in the same manner as in Example 8, except that the shape of the substrate 11 was changed and the angle φ between the fast axis 12a of the retardation film 12 and the minor axis 11c of the curved surface portion 11a was set to 30°.

[0076] The retardation optical element 10 of Example 10 was evaluated in the same manner as in Example 1, and the change rate of birefringence was 10%. Therefore, the retardation optical element 10 of Example 10 was evaluated as being good as shown in Table 1.

[0077] Example 11 In Example 11, a substrate 11 having the shape shown in FIG. 6A was prepared. FIG. 6A shows the substrate 11 prepared in Example 11. The left figure is a plan view of the substrate 11 in a plan view seen in the optical axis direction of the substrate 11, and the right figure is a cross-sectional view showing a cross-section of the substrate 11 along the minor axis 11c. As shown in FIG. 6A, in a plan view, the curved surface portion 11a of the substrate 11 is a convex lens having a circular shape with a minor axis 11c length L1 of 50 mm, a major axis 11d length L2 of 50 mm, and a half-opening angle θ of 20°, and the peripheral portion 11b is not provided. Except for changing the shape of the substrate 11 and not specifically specifying the direction of the fast axis 12a when arranging the retardation film 12, in Example 11, the retardation optical element 10 was manufactured in the same manner as in Example 1. Note that FIG. 6B is a plan view showing the arrangement of the retardation film 12 with respect to the substrate 11 in Example 11, and is a plan view seen in a direction perpendicular to the film surface of the retardation film 12. As shown in FIG. 6B, the retardation film 12 was arranged without specifically specifying the direction of the fast axis 12a in relation to the substrate 11.

[0078] Regarding the retardation optical element 10 manufactured as described above, when birefringence was measured in the same manner as in Example 1, a region where the change rate of birefringence was up to 15% was measured at the outer peripheral portion of the retardation optical element 10 in the direction parallel to the fast axis 12a. Therefore, in Example 11, in the above retardation optical element 10, the end portions including the curved surface portions 11a on both sides from both ends, which are regions where the change rate of birefringence exceeds 10% in the direction parallel to the fast axis 12a, were cut off by 7 mm. In this way, in Example 11, after the retardation film 12 was attached to the curved surface portion 11a of the substrate 11, the region with a large change rate of birefringence was cut off to manufacture the retardation optical element 10.

[0079] As an evaluation of the retardation optical element 10 of Example 11, the same evaluation as in Example 1 was performed, and the change rate of birefringence was 10%. Therefore, the retardation optical element 10 of Example 11 was evaluated as being good as shown in Table 1.

[0080] (Example 12) In Example 12, the substrate 11 shown in FIG. 7A was prepared. FIG. 7A shows the substrate 11 prepared in Example 12, with the left side diagram being a plan view showing the substrate 11 in plan view seen in the optical axis direction of the substrate 11, and the right side diagram being a cross-sectional view showing the cross section of the substrate 11 along the minor axis 11c. As shown in FIG. 7A, in plan view, the substrate 11 had a shape in which the curved surface portion 11a had two sides facing in different directions and two arcs connecting two adjacent pairs of ends of these two sides, and had a peripheral portion 11b adjacent to the curved surface portion 11a. The two arcs were parts of the circumference of the same circle. In Example 12, the length L1 of the minor axis 11c of the curved surface portion 11a was 40 mm, the length L2 of the major axis 11d was 60 mm, and the curved surface portion 11a was a convex lens with a half opening angle θ of 20°. In addition, a flat peripheral portion 11b with a width of 2 mm was provided as the peripheral portion 11b. In Example 12, a retardation optical element 10 was manufactured in the same manner as in Example 1, except that the shape of the substrate 11 was changed. Fig. 7B is a plan view showing the arrangement of the retardation film 12 with respect to the substrate 11 in Example 12, as viewed in a direction perpendicular to the film surface of the retardation film 12. As shown in Fig. 7B, the retardation film 12 was arranged so that the minor axis 11c of the curved portion 11a of the substrate 11 and the fast axis 12a of the retardation film 12 were parallel (angle φ was 0°).

[0081] The retardation optical element 10 of Example 12 was evaluated in the same manner as in Example 1, and the change rate of birefringence was 10%. Therefore, the retardation optical element 10 of Example 12 was evaluated as being good as shown in Table 1.

[0082] Comparative Example 1 In Comparative Example 1, a substrate 11 having a shape shown in Fig. 6A was prepared. As shown in Fig. 6A, the substrate 11 was a convex lens having a curved surface 11a in a circular shape with a minor axis 11c length L1 of 50 mm and a major axis 11d length L2 of 50 mm in a plan view, a half-open angle θ of 20°, and no peripheral portion 11b. In Comparative Example 1, a retardation optical element 10 was manufactured in the same manner as in Example 1, except that the shape of the substrate 11 was changed and the direction of the fast axis 12a was not particularly specified when the retardation film 12 was disposed.

[0083] The retardation optical element 10 of Comparative Example 1 was evaluated in the same manner as in Example 1, and the rate of change in birefringence was found to be 15%. Therefore, the retardation optical element 10 of Comparative Example 1 was evaluated as defective as shown in Table 1.

[0084] Comparative Example 2 In Comparative Example 2, a substrate 11 having a shape shown in Fig. 5A was prepared. As shown in Fig. 5A, the substrate 11 was a convex lens in which the curved surface portion 11a had a length L1 of the minor axis 11c of 40 mm, a length L2 of the major axis 11d of 50 mm, and a half-open angle θ of 20° in a plan view, and a flat peripheral portion 11b having an outer diameter of 56 mm was provided. In Comparative Example 2, a retardation optical element 10 was manufactured in the same manner as in Example 8, except that the shape of the substrate 11 was changed and the angle φ between the fast axis 12a of the retardation film and the minor axis 11c of the curved surface portion 11a was set to 45°.

[0085] The retardation optical element 10 of Comparative Example 2 was evaluated in the same manner as in Example 1, and the rate of change in birefringence was found to be 18%. Therefore, the retardation optical element 10 of Comparative Example 2 was evaluated as defective, as shown in Table 1.

[0086] The retardation optical elements 10 of the above-mentioned examples and comparative examples are evaluated together with details such as the shape of the substrate 11 in Table 1 below.

[0087] [Table 1]

[0088] [Second embodiment] The retardation optical element 10 according to the first embodiment can be applied to various devices and apparatuses such as optical instruments, display devices, imaging devices, etc. In this embodiment, optical instruments and display devices will be described as specific application examples of the retardation optical element according to the first embodiment.

[0089] (optical equipment) Specific application examples of the retardation optical element 10 according to the first embodiment include lenses constituting optical devices (photography optical systems) for cameras and video cameras, and lenses constituting optical devices (projection optical systems) for liquid crystal projectors. It can also be used as a pickup lens for DVD recorders and the like. These optical systems are composed of at least one lens arranged in a housing, and the retardation optical element 10 according to the first embodiment can be used for at least one of the lenses.

[0090] (display device) 8A to 8C are schematic diagrams showing a configuration of a head mounted display (HMD) 100, which is an example of a preferred embodiment of a display device using the retardation optical element 10 according to the first embodiment. Fig. 8A is a side view showing the HMD 100. Fig. 8B is a front view showing the HMD 100. Fig. 8C is a schematic diagram showing the optical system of the HMD 100.

[0091] 8A and 8B, the HMD 100 has a housing 101, a wearing device 102, and display units 103 for the left and right eyes. Each display unit 103 is provided inside the housing 101. The HMD 100 is worn on the user's head H by the wearing device 102 so that the display units 103 for the left and right eyes are positioned corresponding to the left and right eyes of the user, respectively.

[0092] As shown in FIG. 8C, each display unit 103 has a display panel 104, optical systems 105 and 106, and a retardation optical element 10 according to the first embodiment. The display panel 104 is a display unit such as an organic electroluminescence (EL) panel or a liquid crystal panel, and displays an image for the corresponding left eye or right eye. The optical systems 105 and 106 are for forming an image of the image light emitted from the display panel 104 at the position of the user's eye E. The optical system 105 may include a transmissive optical element such as a convex lens or a concave lens, a reflective optical element such as a concave mirror, a mirror, a light path changing element such as a half mirror or a polarizing beam splitter (PBS), etc., depending on the design of the HMD 100. The retardation optical element 10 is installed so as to be located between the optical systems 105 and 106 and the eye E. The retardation optical element 10, together with optical systems 105 and 106, constitutes an optical system that guides image light, which is light emitted from the display panel 104, to the user's eye E, and functions as at least one of the optical elements, that is, lenses, in the optical system.

[0093] Although the display device has been described above using an HMD, the retardation optical element 10 can also be used in a projector or the like.

[0094] The disclosure of this embodiment includes the following configurations and methods. (Configuration 1) a substrate having a curved surface portion having a first diameter and a second diameter longer than the first diameter when viewed in a plan view in the optical axis direction; a retardation film having a fast axis and a slow axis and attached to the curved surface of the curved surface portion; In the plan view, an angle between the fast axis and the first diameter is smaller than 45°. A phase difference optical element characterized by: (Configuration 2) The retardation film is stretched and provided on the curved surface. 2. The retardation optical element according to configuration 1. (Configuration 3) In the plan view, the curved surface portion has a shape surrounded by arcs and straight lines connecting adjacent ends of the arcs, The first diameter is the shortest diameter among the diameters passing through the center point of the circle of the arc in the plan view. 3. The retardation optical element according to configuration 1 or 2. (Configuration 4) In the plan view, the curved surface portion has a shape surrounded by a plurality of arcs and lines connecting adjacent ends of the arcs, The first diameter is the shortest diameter among the diameters passing through the center of gravity of the shape of the curved surface portion in the plan view. 3. The retardation optical element according to configuration 1 or 2. (Configuration 5) When the half open angle of the curved surface is θ, θ satisfies 0°<θ≦30°. 5. The retardation optical element according to any one of configurations 1 to 4. (Configuration 6) When the angle between the first diameter and the fast axis is φ, the length of the first diameter is L1, and the length of the second diameter is L2, for 10°≦θ≦30°, L1 and L2 satisfy the following formula 2. 6. The retardation optical element according to configuration 5. 0.2≦(L1 / cosφ) / L2≦-0.023×θ+1.2 (Formula 2) (Configuration 7) In the plan view, the angle between the fast axis and the first diameter is within 30°. 7. The retardation optical element according to any one of configurations 1 to 6. (Configuration 8) In the plan view, the fast axis and the first diameter are substantially parallel to each other. 7. The retardation optical element according to any one of configurations 1 to 6. (Configuration 9) The substrate has a peripheral portion provided on the periphery of the curved surface portion. 9. The retardation optical element according to any one of configurations 1 to 8. (Configuration 10) The retardation film is attached to the curved surface via an adhesive layer. 10. The retardation optical element according to any one of configurations 1 to 9. (Configuration 11) The retardation film is a 1 / 2 wavelength film or a 1 / 4 wavelength film. 11. The retardation optical element according to any one of configurations 1 to 10. (Method 1) A substrate is disposed, the substrate having a curved surface portion having a first diameter and a second diameter longer than the first diameter when viewed in a plan view in the optical axis direction; A retardation film having a fast axis and a slow axis is arranged so that an angle between the fast axis and the first diameter in the plan view is smaller than 45°, and the retardation film is attached to the curved surface of the curved surface portion. 2. A method for producing a retardation optical element comprising the steps of: (Method 2) The retardation film is pressed against the substrate, thereby attaching the retardation film to the curved surface. 2. The method for producing a retardation optical element according to claim 1, (Method 3) The retardation film having the fast axis and the slow axis is disposed so that an angle between the fast axis and the first diameter in the plan view is within 30°. 3. The method for producing a retardation optical element according to method 1 or 2, (Method 4) The substrate is disposed so that a tangent to a center point of the first diameter of the curved surface portion is parallel to the retardation film. 3. The method for producing a retardation optical element according to method 1 or 2, (Method 5) After the retardation film is heated, the retardation film is attached to the curved surface. 5. The method for producing a retardation optical element according to any one of Methods 1 to 4, (Method 6) A substrate having a curved surface is placed; a retardation film having a fast axis and a slow axis is attached to the curved surface of the curved surface portion; cutting off at least one end of the substrate including the curved surface portion in a direction in which the angle with respect to the fast axis is smaller than 45° in a plan view in the optical axis direction; 2. A method for producing a retardation optical element comprising the steps of: (Configuration 12) 12. An optical device comprising a housing and an optical system having at least one optical element disposed within the housing, wherein at least one of the optical elements is a retardation optical element according to any one of configurations 1 to 11. (Configuration 13) 12. A display device comprising: a housing; an optical system having at least one optical element disposed within the housing; and a display unit that emits light guided by the optical system, wherein at least one of the optical elements is a retardation optical element according to any one of configurations 1 to 11. [Explanation of symbols]

[0095] 10 Phase difference optical element 11 Substrate 11a Curved part 11b Periphery 12 Phase contrast film 13 Adhesive layer 14 Protective film 32 Stages 32a Pedestal 33 First Chamber 34 Second Chamber 37 Support Film 100 Head Mounted Display (HMD) 101 Case 102 Wearing equipment 103 Display unit 104 Display Panel 105, 106 Optical system

Claims

1. a substrate having a curved surface portion having a first diameter and a second diameter longer than the first diameter when viewed in a plan view in the optical axis direction; a retardation film having a fast axis and a slow axis and attached to the curved surface of the curved surface portion; In the plan view, the angle between the fast axis and the first diameter is smaller than 45°. A phase difference optical element characterized by:

2. The retardation film is stretched and provided on the curved surface.

2. The retardation optical element according to claim 1 .

3. In the plan view, the curved surface portion has a shape surrounded by arcs and straight lines connecting adjacent ends of the arcs, The first diameter is the shortest diameter among the diameters passing through the center point of the circle of the arc in the plan view.

3. The retardation optical element according to claim 1, wherein the retardation optical element is a retardation optical element.

4. In the plan view, the curved surface portion has a shape surrounded by a plurality of arcs and lines connecting adjacent ends of the arcs, The first diameter is the shortest diameter among diameters passing through a center of gravity of the shape of the curved surface portion in the plan view.

14. The retardation optical element according to claim 13.

5. When the half open angle of the curved surface is θ, θ satisfies 0°<θ≦30°.

3. The retardation optical element according to claim 1, wherein the retardation optical element is a retardation optical element.

6. When the angle between the first diameter and the fast axis is φ, the length of the first diameter is L1, and the length of the second diameter is L2, for 10°≦θ≦30°, L1 and L2 satisfy the following formula 2.

6. The retardation optical element according to claim 5. 0.2≦(L1 / cosφ) / L2≦-0.023×θ+1.2 (Formula 2)

7. In the plan view, the angle between the fast axis and the first diameter is within 30°.

3. The retardation optical element according to claim 1, wherein the retardation optical element is a retardation optical element.

8. In the plan view, the fast axis and the first diameter are substantially parallel to each other.

3. The retardation optical element according to claim 1, wherein the retardation optical element is a retardation optical element.

9. The substrate has a peripheral portion provided on the periphery of the curved surface portion.

3. The retardation optical element according to claim 1, wherein the retardation optical element is a retardation optical element.

10. The retardation film is attached to the curved surface via an adhesive layer.

3. The retardation optical element according to claim 1, wherein the retardation optical element is a retardation optical element.

11. The retardation film is a 1 / 2 wavelength film or a 1 / 4 wavelength film.

3. The retardation optical element according to claim 1, wherein the retardation optical element is a retardation optical element.

12. a substrate is disposed, the substrate having a curved surface portion having a first diameter and a second diameter longer than the first diameter when viewed in a plan view in the optical axis direction; A retardation film having a fast axis and a slow axis is arranged such that an angle between the fast axis and the first diameter in the plan view is smaller than 45°, and the retardation film is attached to the curved surface of the curved surface portion.

2. A method for producing a retardation optical element comprising the steps of:

13. The retardation film is pressed against the substrate, thereby attaching the retardation film to the curved surface. The method for producing a retardation optical element according to claim 12 .

14. The retardation film having the fast axis and the slow axis is disposed such that an angle between the fast axis and the first diameter in the plan view is within 30°.

14. The method for producing a retardation optical element according to claim 12 or 13.

15. The substrate is disposed so that a tangent to a center point of the first diameter of the curved surface portion is parallel to the retardation film.

14. The method for producing a retardation optical element according to claim 12 or 13.

16. After the retardation film is heated, the retardation film is attached to the curved surface.

14. The method for producing a retardation optical element according to claim 12 or 13.

17. A substrate having a curved surface is placed; a retardation film having a fast axis and a slow axis is attached to the curved surface of the curved surface portion; cutting off at least one end of the substrate including the curved surface portion in a direction in which the angle with the fast axis is smaller than 45° in a plan view in the optical axis direction; 2. A method for producing a retardation optical element comprising the steps of:

18. 3. An optical device comprising a housing and an optical system having at least one optical element disposed within the housing, wherein at least one of the optical elements is the retardation optical element according to claim 1 or 2.

19. 3. A display device comprising: a housing; an optical system having at least one optical element disposed within the housing; and a display unit that emits light guided by the optical system, wherein at least one of the optical elements is a retardation optical element according to claim 1.

Images