Optical element, optical instrument, imaging device, display device, and method for manufacturing an optical element

Abstract

Even when optical elements are affected by environmental factors, this suppresses the occurrence of adhesion defects in the optical film. [Solution] An optical element 10 having a uniaxially stretched optical film 12 and a substrate 11, wherein the optical film is bonded to the curved surface 11a of the substrate via an adhesive layer 13, wherein the second phase difference between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in at least a portion of the outer peripheral portion 12c of the substrate is small with respect to the first phase difference between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the central part 12a of the substrate.

Description

Technical Field

[0001] The present invention relates to an optical element, an optical device, an imaging device, a display device, and a method for manufacturing an optical element, in which a uniaxially stretched optical film is adhered to a curved surface of a substrate via an adhesive layer.

Background Art

[0002] In recent years, head-mounted displays (HMDs) have been used in various fields such as virtual reality (VR), augmented reality (AR), and mixed reality (MR). A head-mounted display has an optical system for forming an image of an image displayed on a display at the position of a user's eyes. In a head-mounted display, a small, lightweight, and high-image-quality optical system is realized by folding an optical path using circular polarization and a half mirror. Further, a head-mounted display is made smaller and lighter by using an optical element in which an optical film having desired optical characteristics is bonded to a substrate having a curved surface. Examples of the optical film include a polarizing film, a reflective polarizing film (polarizing beam splitter (PBS) film), a retardation film, and the like. Patent Document 1 discloses an optical element to which a reflective polarizing film is adhered.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when an optical element, which has a uniaxially stretched optical film such as a reflective polarizing film attached to a curved substrate, is exposed to temperature changes such as high or low temperatures or subjected to impact, adhesion defects (bulging) of the optical film may occur around the periphery of the optical element. This is because the optical film is stretched and bonded to the curved surface of the substrate while stress is maintained inside the optical film. Temperature changes such as those during durability tests further increase the internal stress of the optical film, leading to adhesion defects such as bulging or peeling.

[0005] Therefore, the present invention provides an optical element in which a uniaxially stretched optical film is attached to a curved surface of a substrate via an adhesive layer, and even when the optical element is affected by the environment, the present invention provides an optical element that suppresses the occurrence of adhesion defects of the optical film on the outer periphery of the optical element. [Means for solving the problem]

[0006] According to one embodiment of the present invention, an optical element having a uniaxially stretched optical film and a substrate, wherein the optical film is bonded to the curved surface of the substrate via an adhesive layer, is characterized in that, with respect to a first phase difference between the polarization component in the stretching direction and the polarization component in a direction perpendicular to the stretching direction at the center of the substrate, the second phase difference between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in at least a portion of the outer peripheral portion of the substrate is small. [Effects of the Invention]

[0007] According to the present invention, even when the optical element is affected by the environment, it is possible to suppress the occurrence of adhesion defects of the optical film on the outer periphery of the optical element. [Brief explanation of the drawing]

[0008] [Figure 1] A diagram showing the optical element of Example 1. [Figure 2] A diagram illustrating a method for manufacturing optical elements. [Figure 3] A perspective view of an optical instrument, including optical elements. [Figure 4] Cross-sectional view of a camera including optical elements. [Figure 5] A schematic diagram showing the configuration of a head-mounted display, including optical elements. [Figure 6] A diagram showing the optical element of Example 2. [Figure 7] A diagram showing the optical element of Example 3. [Figure 8] A diagram showing the optical element of Example 4. [Figure 9] A diagram showing the optical element of Example 5. [Figure 10] A diagram showing the optical element of Example 6. [Figure 11] A diagram showing an optical element of a comparative example. [Modes for carrying out the invention]

[0009] The optical element and the method for manufacturing the optical element according to the present invention will be described below with reference to the attached drawings. [Examples]

[0010] (Optical element) Figure 1 shows an optical element 10 of Example 1. Figure 1(a) is a front view of the optical element 10. Figure 1(b) is a cross-sectional view of the optical element 10 taken along the IB-IB line in Figure 1(a). The optical element 10 includes a substrate 11, an optical film 12, and an adhesive layer 13. The substrate 11 has a convex curved surface portion 11a. The optical film 12 is bonded (attached) to the curved surface portion 11a of the substrate 11 via the adhesive layer 13.

[0011] The substrate 11 is a convex lens having a convex curved surface. However, the substrate 11 may also be a concave lens having a concave curved surface. If the curvature of the curved surface portion 11a is R (or the optimal value obtained by the least squares method in the case of an aspherical surface) and the diameter of the curved surface portion 11a is L, then the half-opening angle θ is defined by the following equation 1. sinθ={(L / 2) / R} ···· Formula 1 The half-opening angle θ can be appropriately set according to the design of the substrate 11 which functions as a lens. From the viewpoint of the substrate 11 functioning as a lens, it is preferable that the half-opening angle θ is 0° < θ ≤ 30°.

[0012] (Substrate) The substrate 11 is formed of a plastic mainly composed of a cycloolefin copolymer (COC) by injection molding. However, the material of the substrate 11 is not limited to the cycloolefin copolymer, and may be a transparent plastic, glass, etc. that has permeability to light such as visible light targeted by the optical element 10. As the plastic material, a plastic that can be formed by injection molding and is optically used is preferable. Examples of the plastic material of the substrate 11 include polycarbonate (PC), polyester (PEs), (meth)acrylic (PMMA), cycloolefin polymer (COP), etc. As the glass material, the material is not particularly limited, and examples include synthetic quartz and general glass material BK-7, etc.

[0013] (Optical film) The optical film 12 is obtained by stretching a polymer or a multilayer polymer in one direction (uniaxial stretching). The optical film 12 of Example 1 is a reflective polarizing film. The reflective polarizing film is configured by alternately laminating several hundred layers of a first sheet and a second sheet having different materials and refractive indexes, and stretching the laminated first sheet and second sheet in one direction to have a reflective polarizing function. Since the birefringence generated in the stretched first sheet and second sheet is different, light incident on the optical film 12 parallel to the stretching direction (reflection axis) is reflected without passing through, and light incident on the optical film 12 perpendicular to the stretching direction (transmission axis) passes through. The reflection axis direction of the uniaxially stretched reflective polarizing film is the stretching direction, and the transmission axis direction is the direction perpendicular to the stretching direction. The component of the light incident on the reflective polarizing film in the stretching direction (reflection axis) and reflected is the polarization component in the stretching direction. The component of the light incident on the reflective polarizing film in the direction perpendicular to the stretching direction (transmission axis) and transmitted is the polarization component in the direction perpendicular to the stretching direction.

[0014] (Manufacturing method of optical element) Using FIG. 2, a method for manufacturing the optical element 10 will be described. FIG. 2 is a diagram showing the method for manufacturing the optical element 10. The manufacturing apparatus 70 includes a first chamber 71, a second chamber 72, a film holding portion 73, a substrate holding portion 74, a lifting member 75, a sealing member 76, a vacuum device 77, and an infrared heater 78. The first chamber 71 is provided with an opening 71a at the upper part. The film holding portion 73 is provided near the opening 71a of the first chamber. The film holding portion 73 is configured to hold the optical film 12. The second chamber 72 is provided with an opening 72a at the lower part. The sealing member 76 is provided near the opening 72a of the second chamber 72. The opening 71a of the first chamber 71 and the opening 72a of the second chamber 72 are arranged to face each other. The first chamber 71 and the second chamber 72 are configured to approach and separate from each other. The substrate holding portion 74 is configured to hold the substrate 11. The substrate holding portion 74 is configured to be lifted and lowered by the lifting member 75.

[0015] First, as shown in FIG. 1, a substrate 11 made of plastic mainly composed of a cycloolefin copolymer (COC) formed by injection molding is prepared. The curved surface portion 11a of the substrate 11 has a diameter of 40 mm. The substrate 11 is a convex lens with a half opening angle θ of 22°. Next, as the optical film 12, an IQPE (Image Quality Polarizer Enhanced), which is a reflective polarizing film manufactured by 3M (registered trademark), is prepared. The optical film 12 has a thickness of about 0.07 mm. An adhesive layer (sticky layer) 13 is provided on one surface of the optical film 12. The size of the optical film 12 is 100 mm × 100 mm.

[0016] As shown in Figure 2(a), the first chamber 71 is separated from the second chamber 72. The substrate 11 is placed on a substrate holding portion 74 provided inside the first chamber 71. The substrate 11 is held by the substrate holding portion 74. The optical film 12 is placed on a film holding portion 73 provided at the top of the first chamber 71. The optical film 12 is held by the film holding portion 73. At this time, the optical film 12 is positioned so as to face the substrate 11 between the first chamber 71 and the second chamber 72. An adhesive layer 13 is uniformly provided on one surface of the optical film 12 that faces the substrate 11. The adhesive layer 13 is formed of, for example, an optically transparent adhesive or tack. For example, the adhesive may be transparent OCA8171, available from 3M in St. Paul, Minnesota.

[0017] A protective film (not shown) may be provided on the side of the optical film 12 opposite to the substrate 11. The glass transition temperature of the protective film is lower than that of the optical film 12. By providing a protective film, the optical film 12 is less likely to tear when it is bonded to the substrate 11. Since the optical film 12 is more expensive than general films, a size slightly larger than the area of ​​the curved portion 11a of the substrate 11 (an area 1.5 to 2.5 times the area when the curved portion 11a is viewed from above) is sufficient. A support film made of a separate material may be bonded to the optical film 12. In this case, in order to make the deflection of the optical film 12 uniform when the optical film 12 is heated, the support film should have a glass transition temperature equivalent to or about 20°C lower than that of the optical film 12.

[0018] Next, as shown in Figure 2(b), the first chamber 71 and the second chamber 72 are brought close to each other and brought into contact via a sealing member 76, and the first chamber 71 is closed by the second chamber 72. The first chamber 71 and the second chamber 72 are each connected to a vacuum device 77. The vacuum device 77 creates a vacuum inside the first chamber 71 and the second chamber 72. The optical film 12 placed between the first chamber 71 and the second chamber 72 is heated. The optical film 12 is heated directly by an infrared heater 78. However, the heating means for heating the optical film 12 is not limited to the infrared heater 78; the entire structure of the first chamber 71 and the second chamber 72 may be heated by a heater or the like. When the entire first chamber 71 and the second chamber 72 are heated, the substrate holder (base) 74 should be made of a heat insulating structure so that the substrate 11 made of plastic material does not deform due to the heat. Regardless of the temperature of the optical film 12, the temperature of the substrate 11 should be maintained at 120°C or below.

[0019] After heating the optical film 12 to a predetermined bonding temperature (e.g., 150°C), as shown in Figure 2(c), the lifting member 75 is raised to bring the substrate 11 into contact with the optical film 12, and the inside of the second chamber 72 is opened to the atmosphere to increase the pressure inside the second chamber 72. As a result, the optical film 12 is bonded to the curved surface of the substrate 11 via the adhesive layer 13 (bonding process). The bonding process is performed while the optical film is heated. Furthermore, if necessary, high-pressure gas (e.g., compressed air) is introduced into the second chamber 72 to raise the pressure inside the second chamber 72 to a desired pressure (e.g., 0.2 MPa), pressurizing the optical film 12 and pressing it against the substrate 11. Also, if necessary, the heating and pressurizing of the optical film 12 may be continued for a certain period of time (e.g., 30 seconds).

[0020] Next, the heating and pressurization of the optical film 12 are stopped, and the pressure in the second chamber 72 is returned to atmospheric pressure, after which the first chamber 71 is also opened to the atmosphere. Then, as shown in Figure 2(d), the second chamber 72 is separated from the first chamber 71.

[0021] Next, the substrate 11 to which the optical film 12 is bonded is removed from the manufacturing apparatus 70. As shown in Figure 2(e), the optical film 12 on the outer periphery of the substrate 11 is heated to a predetermined heating temperature (hereinafter referred to as the post-heating temperature) as a post-bonding heat treatment using a heating element 79 such as a heater. For example, the post-heating temperature is set to 180°C. The heating element 79 is pressed against the optical film 12 on the outer periphery of the substrate 11 to heat the outer periphery 12c (Figure 1(a)) of the optical film 12 (heating step). The post-heating temperature in the heating step is higher than the heating temperature in the bonding step. At this time, the outer periphery that is heated is a region with a width of 4 mm from the edge of the substrate 11, which is 10% of the diameter (lens diameter) of the curved surface portion 11a of the substrate 11, which is 40 mm. At least a portion of the outer periphery of the substrate 11 bonded to the optical film 12 may be heated by the heating element 79.

[0022] When the optical film 12 is bonded to the curved surface portion 11a of the substrate 11, the optical film 12 is stretched, generating stress inside the optical film 12. Temperature changes, such as those during durability testing, further increase the internal stress of the optical film 12. As a result, adhesion defects such as lifting or peeling of the optical film 12 may occur, particularly on the outer periphery of the substrate 11. Therefore, as described above, the optical film 12 on the outer periphery of the substrate 11 is heated to a desired temperature by the heating element 79 to reduce the internal stress of the optical film 12. This suppresses the occurrence of adhesion defects such as lifting or peeling of the optical film 12.

[0023] After heating the optical film 12 on the outer periphery of the substrate 11, as shown in Figure 2(f), the blade 80 is applied along the outer edge of the curved surface 11a to cut off the unnecessary portion of the optical film 12, leaving the optical film 12 on the curved surface 11a of the substrate 11. The cutting means is not limited to the blade 80; a configuration in which a laser beam is applied along the outer edge of the curved surface 11a to cut off the unnecessary portion of the optical film 12 may also be used. In this way, as shown in Figure 2(g), an optical element 10 is manufactured in which the optical film 12 is bonded to the curved surface 11a of the substrate 11. The optical element 10 of Example 1 is a reflective polarizing optical element in which a reflective polarizing film is bonded to the substrate 11 via an adhesive layer 13 as the optical film 12.

[0024] (Phase difference measurement) To evaluate the internal stress of the optical film 12, the phase difference σ (nm) is measured. The stress F accumulated in the optical film 12 can be seen from the following equation 2, where d (cm) is the thickness of the optical film 12 and β( / 10) is the photoelastic coefficient of the optical film 12. 5 It is known that Pa is correlated with the phase difference σ. F=σ / (β×d) · ··· Formula 2

[0025] In other words, measuring the phase difference σ is effective in evaluating whether the stress in the outer peripheral portion 12c (Figure 1) of the optical film 12 is reduced by the manufacturing method of the optical element 10 in Example 1. In Example 1, as shown in Figure 1, the optical film 12 is divided into a central portion 12a, a middle band portion 12b, and an outer peripheral portion 12c. The phase difference of the central portion 12a (first phase difference) and the phase difference of the outer peripheral portion 12c (second phase difference) of the optical film 12 are measured, and the stress of the optical film 12 is evaluated based on the measurement results of the phase differences.

[0026] In the optical element 10, the central part 12a of the optical film 12 is located at a position corresponding to the center of the optical element 10 and the center of the substrate 11. Also, in the optical element 10, the outer peripheral part 12c of the optical film 12 is located at a position corresponding to the outer peripheral part of the optical element 10 and the outer peripheral part of the substrate 11. Therefore, for the sake of convenience in the following explanation, the central part 12a of the optical film 12 may be referred to as the central part 12a of the optical element 10 or the substrate 11, and the outer peripheral part 12c of the optical film 12 may be referred to as the outer peripheral part 12c of the optical element 10 or the substrate 11. The phase difference of the optical element 10 is measured using a phase difference measuring device KOBRA (manufactured by Oji Instruments Co., Ltd.), but it may also be measured using other devices. The average value RET1 (nm) of the phase difference of the central part 12a of the optical element 10 and the average value RET2 (nm) of the phase difference of the outer peripheral part 12c of the optical element 10 are measured. Since the phase difference and the stress held in the optical film 12 are proportional, the average value RET2 of the phase difference in the outer periphery 12c must be smaller than the average value RET1 of the phase difference in the central part 12a. According to our research, when the ratio of the average value RET2 of the phase difference in the outer periphery 12c to the average value RET1 of the phase difference in the central part 12a (RET2 / RET1) is 97% or less, the durability of the optical element 10 during high and low temperature tests is good. Therefore, when RET2 / RET1 is 97% or less, it is determined that the stress inside the optical film 12 has been sufficiently reduced.

[0027] The optical element 10 of Example 1 is evaluated using the KOBRA phase difference measuring device. The central region 12a is defined as the region within a diameter of 20 mm, which corresponds to 50% of the diameter from the center of the optical element 10. The average value RET1 of the phase difference (first phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction at the central region 12a of the substrate 11 is calculated. The outer periphery 12c is defined as the region of the optical element 10 heated by the heating member 79, with a width of 4 mm from the edge of the substrate 11. The average value RET2 of the phase difference (second phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction at the outer periphery 12c of the substrate 11 is calculated. The ratio of the phase difference (second phase difference) of the outer periphery 12c to the phase difference (first phase difference) of the central region 12a, calculated from the average values ​​RET1 and RET2, is 97%. Therefore, the RET2 / RET1 ratio of the optical element 10 in Example 1 is 97% or less.

[0028] (Appearance evaluation after the end of the durability test) The optical element 10 of Example 1 will be evaluated for its appearance. The appearance of the optical element 10 can be evaluated, for example, by observing the condition of its edges with a microscope. In this example, a digital microscope VHX (manufactured by Keyence Corporation) will be used as the microscope. Specifically, the area 2 mm inward from the edge of the substrate 11 will be observed with the microscope. If no lifting with a width of 200 μm or more is observed, the optical element 10 will be evaluated as good, as it will not be affected by peeling in the durability test under high temperature conditions. Furthermore, as a temperature cycle test, 30 cycles of 30 minutes at 70°C and 30 minutes at -30°C will be repeated, and the condition of the edges of the optical element 10 after the temperature cycle test will be observed with a microscope to confirm whether peeling has progressed to an area of ​​2 mm or more from the edge of the substrate 11.

[0029] Table 1 below shows the specifications and evaluation results of the optical elements of Example 1, Examples 2 to 6 described later, and Comparative Example 1. In the visual evaluation after the temperature cycle test of the optical element 10 of Example 1, no lifting or peeling was observed, so the appearance of the optical element 10 of Example 1 is judged to be good (○) as shown in Table 1. According to Example 1, even when the optical element 10 is affected by the environment, it is possible to suppress the occurrence of poor adhesion of the optical film 12 to the outer peripheral portion 12c of the optical element 10.

[0030] [Table 1]

[0031] The optical element 10 can be applied to various devices and equipment such as optical instruments, imaging devices, and display devices. Specific examples of applications of the optical element 10, such as optical instruments, imaging devices, and display devices, will be described below.

[0032] (optical equipment) Specific examples of applications for the optical element 10 include lenses that constitute optical equipment (photographic optical systems) for cameras and video cameras, and lenses that constitute optical equipment (projection optical systems) for liquid crystal projectors. The optical element 10 can also be used in the pickup lens of optical equipment such as DVD recorders. Figure 3 is a perspective view of an optical device 301 including the optical element 10. The optical device 301 is a lens barrel that uses the optical element 10 in at least one lens located inside the housing (lens barrel) 301a.

[0033] (Imaging device) Figure 4 is a cross-sectional view of the camera 302 including the optical element 10. The camera (main body) 302 as an imaging device comprises the optical element 10 and an image sensor 306 that receives the image formed by the optical element 10. The image sensor 306 is a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor that converts the received light into an electrical signal.

[0034] (display device) Figure 5 is a schematic diagram showing the configuration of a head-mounted display (hereinafter referred to as HMD) 100 including an optical element 10. Figure 5(a) is a side view showing the HMD 100 as a display device. Figure 5(b) is a front view showing the HMD 100. Figure 5(c) is an explanatory diagram of the structure of the display unit 103 of the HMD 100. As shown in Figures 5(a) and 5(b), the HMD 100 has a housing 101, a mounting device 102, and display units 103 for the left eye and the right eye. Each of the left eye and right eye display units 103 is provided inside the housing 101. The HMD 100 is mounted on the user's head by the mounting device 102 so that the left eye and right eye display units 103 are positioned corresponding to the user's left eye and right eye, respectively.

[0035] As shown in Figure 5(c), each display unit 103 includes a display panel (display section) 104 and an optical system 108 that guides the light emitted from the display panel. The optical system 108 includes an optical member 105, an optical element 10, and an optical member 106. The optical system 108 includes one optical element 10, but may include two or more optical elements 10. The optical system 108 preferably includes at least one optical element 10. The display panel 104 and the optical system 108 are arranged inside the housing 101. The display panel 104 is a display section such as an organic electroluminescent (EL) panel or a liquid crystal panel, and displays the corresponding image for the left eye or right eye. The optical system 108 images the image light emitted from the display panel 104 at the position of the user's eye 107. The optical elements 105 and 106 included in the optical system 108 may include, depending on the design of the HMD 100, transmissive optical elements such as convex and concave lenses, reflective optical elements such as concave mirrors, mirrors, optical path changing elements such as half mirrors and polarizing beam splitters (PBSs), etc. Optical element 10 is positioned between optical element 105 and the eye 107. Optical element 10, together with optical elements 105 and 106, constitutes the optical system 108 that guides the image light, which is light emitted from the display panel 104, to the user's eye 107. Optical element 10 functions as at least one lens in the optical system 108.

[0036] In this description, the HMD100 is described as a display device including the optical element 10, but the display device is not limited to this. For example, the optical element 10 may be used in a display device such as a projector. [Examples]

[0037] (Optical element) Next, the optical element 20 of Example 2 will be described using Figure 6. Figure 6 is a diagram showing the optical element 20 of Example 2. Figure 6(a) is a front view of the optical element 20. Figure 6(b) is a cross-sectional view of the optical element 20 taken along the line VIB-VIB in Figure 6(a). The optical element 20 includes a substrate 21, an optical film 22, and an adhesive layer 23. The substrate 21 has a convex curved surface portion 21a. The optical film 22 is bonded to the curved surface portion 21a of the substrate 21 via the adhesive layer 23. The adhesive layer 23 is formed of, for example, an optically transparent adhesive or tack.

[0038] (Optical film) The optical film 12 of the optical element 10 in Example 1 is a reflective polarizing film, while the optical film 22 of the optical element 20 in Example 2 is a phase difference film stretched in one direction (uniaxially stretched) using COP, COC, or PC. A phase difference film has a leading phase axis and a slow phase axis perpendicular to the leading phase axis. The slow phase axis direction of a uniaxially stretched phase difference film is the stretching direction, and the leading phase axis direction is perpendicular to the stretching direction. A phase difference film can delay the phase of light incident parallel to the slow phase axis by a predetermined wavelength before emission. Examples of phase difference films include a half-wavelength film that delays the phase of light incident parallel to the slow phase axis by half a wavelength, and a quarter-wavelength film that delays the phase of light incident parallel to the slow phase axis by a quarter wavelength. The component of light incident on the phase difference film in the stretching direction (slow phase axis) and emitted with a predetermined wavelength delay is the polarization component in the stretching direction. When light is incident on a phase difference film in a direction perpendicular to the stretching direction (the phase-advancing axis) and transmitted, the component of the light is the polarization component perpendicular to the stretching direction.

[0039] (Manufacturing method for optical elements) The manufacturing apparatus 70 for producing the optical element 20 of Example 2 is the same as that of Example 1, so its description will be omitted. First, a substrate 21 made of plastic mainly composed of COC, molded by injection molding, is prepared. The curved portion 21a of the substrate 21 has a diameter of 50 mm. The substrate 21 is a plastic convex lens with a half-opening angle θ of 12°. Next, a quarter-wavelength film from Nippon Kayaku Co., Ltd. is prepared as the optical film 22. The optical film 22 has a thickness of 0.1 mm. An adhesive layer 23 is provided on one side of the optical film 22.

[0040] Similar to Example 1 described in Figure 2, a substrate 21 is placed on the substrate holding section 74 of the manufacturing apparatus 70, and an optical film 22 is placed on the film holding section 73. The bonding temperature of the optical film 22 is set to 120°C, and the optical film 22 is bonded to the substrate 21 via the adhesive layer 23 (bonding step). The substrate 21 with the bonded optical film 22 is removed from the manufacturing apparatus 70, and the outer periphery of the substrate 21 (a region with a width of 5 mm from the edge) is heated by a heating member 79 at a post-heating temperature of 140°C (heating step). The post-heating temperature in the heating step is higher than the heating temperature in the bonding step. At least a portion of the outer periphery of the substrate 21 with the bonded optical film 22 may be heated by the heating member 79. A blade 80 is applied along the outer edge of the substrate 21 to cut off the unnecessary portion of the optical film 22, and the optical element 20 is manufactured. The optical element 20 of Example 2 is a phase difference optical element in which a phase difference film is bonded to the substrate 21 via the adhesive layer 23 as the optical film 22.

[0041] (Phase difference measurement) The optical element 20 of Example 2 is evaluated using the KOBRA phase difference measuring device. In Example 2, as shown in Figure 6, the optical film 22 is divided into a central part 22a, a middle band 22b, and an outer peripheral part 22c. The central part 22a is defined as the region within a diameter of 25 mm, which corresponds to 50% of the diameter from the center of the optical element 20. The average value RET1 of the phase difference (first phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the central part 22a of the substrate 21 is calculated. The outer peripheral part 22c is defined as the region of the optical element 20 heated by the heating member 79, with a width of 5 mm from the edge of the substrate 21. The average value RET2 of the phase difference (second phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the outer peripheral part 22c of the substrate 21 is calculated. The ratio of the phase difference of the outer periphery 22c (second phase difference) to the phase difference of the central part 22a (first phase difference), calculated from the average values ​​RET1 and RET2, is RET2 / RET1, which is 87%. Therefore, the RET2 / RET1 of the optical element 20 of Example 2 is 97% or less.

[0042] (Appearance evaluation after the end of the durability test) Even after the temperature cycling test of the optical element 20 in Example 2, no lifting or peeling was observed in the visual evaluation, so the appearance of the optical element 20 in Example 2 is judged to be good (○) as shown in Table 1. According to Example 2, even when the optical element 20 is affected by the environment, it is possible to suppress the occurrence of adhesion defects of the optical film 22 on the outer peripheral portion 22c of the optical element 20. The optical element 20 in Example 2 can be applied to various devices and equipment such as optical instruments, imaging devices, and display devices, similar to Example 1. [Examples]

[0043] (Optical element) Next, the optical element 30 of Example 3 will be described using Figure 7. Figure 7 is a diagram showing the optical element 30 of Example 3. Figure 7(a) is a front view of the optical element 30. Figure 7(b) is a cross-sectional view of the optical element 30 taken along the line VIIB-VIIB in Figure 7(a). The optical element 30 includes a substrate 31, an optical film 32, and an adhesive layer 33. The substrate 31 has a concave curved surface portion 31a. The optical film 32 is bonded to the curved surface portion 31a of the substrate 31 via the adhesive layer 33. The adhesive layer 33 is formed of, for example, an optically transparent adhesive or tack.

[0044] (Manufacturing method for optical elements) The manufacturing apparatus 70 for producing the optical element 30 of Example 3 is the same as that of Example 1, so its description will be omitted. First, a substrate 31 made of glass is prepared. The curved portion 31a of the substrate 31 has a diameter of 40 mm. The substrate 31 is a glass concave lens with a half-opening angle θ of 22°. Next, as the optical film 32, IQPE, a reflective polarizing film manufactured by 3M, is prepared, as in Example 1.

[0045] Similar to Embodiment 1 described in Figure 2, a substrate 31 is placed on the substrate holding section 74 of the manufacturing apparatus 70, and an optical film 32 is placed on the film holding section 73. The bonding temperature of the optical film 32 is set to 150°C, and the optical film 32 is bonded to the substrate 31 via the adhesive layer 33 (bonding step). The substrate 31 with the bonded optical film 32 is removed from the manufacturing apparatus 70, and the outer periphery of the substrate 31 (a region with a width of 4 mm from the edge) is heated by a heating member 79 at a post-heating temperature of 190°C (heating step). The post-heating temperature in the heating step is higher than the heating temperature in the bonding step. At least a portion of the outer periphery of the substrate 31 with the bonded optical film 32 may be heated by the heating member 79. The blade 80 is applied along the outer edge of the substrate 31 to cut off the unnecessary portion of the optical film 32, and the optical element 30 is manufactured. The optical element 30 of Example 3 is a reflective polarizing optical element in which a reflective polarizing film is bonded to a substrate 31 via an adhesive layer 33 as an optical film 32.

[0046] (Phase difference measurement) The optical element 30 of Example 3 is evaluated using the KOBRA phase difference measuring device. In Example 3, as shown in Figure 7, the optical film 32 is divided into a central part 32a, a middle band 32b, and an outer peripheral part 32c. The central part 32a is defined as the region within a diameter of 20 mm, which corresponds to 50% of the diameter from the center of the optical element 30. The average value RET1 of the phase difference (first phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the central part 32a of the substrate 31 is calculated. The outer peripheral part 32c is defined as the region of the optical element 30 heated by the heating member 79, with a width of 4 mm from the edge of the substrate 31. The average value RET2 of the phase difference (second phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the outer peripheral part 32c of the substrate 31 is calculated. The ratio of the phase difference of the outer periphery 32c (second phase difference) to the phase difference of the central part 32a (first phase difference), calculated from the average values ​​RET1 and RET2, is RET2 / RET1, which is 95%. Therefore, the RET2 / RET1 of the optical element 30 of Example 3 is 97% or less.

[0047] (Appearance evaluation after the end of the durability test) Even after the temperature cycling test of the optical element 30 in Example 3, no lifting or peeling was observed, so the appearance of the optical element 30 in Example 3 is judged to be good (○) as shown in Table 1. According to Example 3, even when the optical element 30 is affected by the environment, it is possible to suppress the occurrence of poor adhesion of the optical film 32 to the outer peripheral portion 32c of the optical element 30. The optical element 30 in Example 3 can be applied to various devices and equipment such as optical instruments, imaging devices, and display devices, similar to Example 1. [Examples]

[0048] (Optical element) Next, the optical element 40 of Example 4 will be described using Figure 8. Figure 8 is a diagram showing the optical element 40 of Example 4. Figure 8(a) is a front view of the optical element 40. Figure 8(b) is a cross-sectional view of the optical element 40 taken along the line VIIIB-VIIIB in Figure 8(a). The optical element 40 includes a substrate 41, an optical film 42, and an adhesive layer 43. The substrate 41 has a concave curved surface portion 41a. The optical film 42 is bonded to the curved surface portion 41a of the substrate 41 via the adhesive layer 43. The adhesive layer 43 is formed of, for example, an optically transparent adhesive or tack.

[0049] (Manufacturing method for optical elements) The manufacturing apparatus 70 for producing the optical element 40 of Example 4 is the same as that of Example 1, so its description will be omitted. First, a substrate 41 made of plastic is prepared. The curved portion 41a of the substrate 41 has a diameter of 50 mm. The substrate 41 is a plastic concave lens with a half-opening angle θ of 12°. Next, as the optical film 42, IQPE, a reflective polarizing film manufactured by 3M, is prepared, as in Example 1.

[0050] Similar to Embodiment 1 described in Figure 2, a substrate 41 is placed on the substrate holding section 74 of the manufacturing apparatus 70, and an optical film 42 is placed on the film holding section 73. The bonding temperature of the optical film 42 is set to 130°C, and the optical film 42 is bonded to the substrate 41 via the adhesive layer 43 (bonding step). The substrate 41 with the bonded optical film 42 is removed from the manufacturing apparatus 70, and the outer periphery of the substrate 41 (a region with a width of 5 mm from the edge) is heated by a heating member 79 at a post-heating temperature of 190°C (heating step). The post-heating temperature in the heating step is higher than the heating temperature in the bonding step. At least a portion of the outer periphery of the substrate 41 with the bonded optical film 42 may be heated by the heating member 79. A blade 80 is applied along the outer edge of the substrate 41 to cut off the unnecessary portion of the optical film 42, and the optical element 40 is manufactured. The optical element 40 of Example 4 is a reflective polarizing optical element in which a reflective polarizing film is bonded to a substrate 41 via an adhesive layer 43 as an optical film 42.

[0051] (Phase difference measurement) The optical element 40 of Example 4 is evaluated using the KOBRA phase difference measuring device. In Example 4, as shown in Figure 8, the optical film 42 is divided into a central part 42a, a middle band 42b, and an outer peripheral part 42c. The central part 42a is defined as the region within a diameter of 25 mm, which corresponds to 50% of the diameter from the center of the optical element 40. The average value RET1 of the phase difference (first phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the central part 42a of the substrate 41 is calculated. The outer peripheral part 42c is defined as the region of the optical element 40 heated by the heating member 79, with a width of 5 mm from the edge of the substrate 41. The average value RET2 of the phase difference (second phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the outer peripheral part 42c of the substrate 41 is calculated. The ratio RET2 / RET1, which is the ratio of the phase difference of the outer periphery 42c (second phase difference) to the phase difference of the central part 42a (first phase difference) calculated from the average values ​​RET1 and RET2, is 97%. Therefore, the RET2 / RET1 of the optical element 40 of Example 4 is 97% or less.

[0052] (Appearance evaluation after the end of the durability test) Even after the temperature cycling test of the optical element 40 in Example 4, no lifting or peeling was observed, so the appearance of the optical element 40 in Example 4 is judged to be good (○) as shown in Table 1. According to Example 4, even when the optical element 40 is affected by the environment, it is possible to suppress the occurrence of poor adhesion of the optical film 42 to the outer peripheral portion 42c of the optical element 40. The optical element 40 in Example 4 can be applied to various devices and equipment such as optical instruments, imaging devices, and display devices, similar to Example 1. [Examples]

[0053] (Optical element) Next, the optical element 50 of Example 5 will be described using Figure 9. Figure 9 is a diagram showing the optical element 50 of Example 5. Figure 9(a) is a front view of the optical element 50. Figure 9(b) is a cross-sectional view of the optical element 50 taken along the line IXB-IXB in Figure 9(a). The optical element 50 includes a substrate 51, an optical film 52, and an adhesive layer 53. The substrate 51 has a concave curved surface portion 51a. The optical film 52 is bonded to the curved surface portion 51a of the substrate 51 via the adhesive layer 53. The adhesive layer 53 is formed of, for example, an optically transparent adhesive or tack.

[0054] (Manufacturing method for optical elements) The manufacturing apparatus 70 for producing the optical element 50 of Example 5 is the same as in Example 1, so its description will be omitted. First, a plastic substrate 51 is prepared. The curved portion 51a of the substrate 51 has a diameter of 45 mm. The substrate 51 is a plastic concave lens with a half-opening angle θ of 22°. Next, as the optical film 52, IQPE, a reflective polarizing film manufactured by 3M, is prepared, as in Example 1.

[0055] Similar to Example 1 described in Figure 2, a substrate 51 is placed on the substrate holding section 74 of the manufacturing apparatus 70, and an optical film 52 is placed on the film holding section 73. The bonding temperature of the optical film 52 is set to 150°C, and the optical film 52 is bonded to the substrate 51 via the adhesive layer 53 (bonding step). The substrate 51 with the bonded optical film 52 is removed from the manufacturing apparatus 70, and a predetermined area PA (at least a portion of the outer periphery) within a 4.5 mm width from the edge of the substrate 51 is heated at a post-heating temperature of 200°C by a heating member 79 (heating step). The post-heating temperature in the heating step is higher than the heating temperature in the bonding step.

[0056] The predetermined region PA is the regions on both sides opposite each other with respect to the transmission axis TA passing through the center of the optical film 52, that is, the regions at both ends in the direction of the reflection axis RA passing through the center of the optical film 52. The predetermined region PA is arc-shaped with respect to the center of the substrate 51 and extends to both sides with respect to the reflection axis RA passing through the center of the optical film 52. The central angle CA of the predetermined region PA is approximately 90°. The direction of the reflection axis RA is the stretching direction of the optical film 52. The optical film 52 obtained by uniaxial stretching tends to have internal stress in the stretching direction. Therefore, it is effective to reduce internal stress by heating the predetermined region PA at both ends in the direction of the reflection axis RA, which is parallel to the stretching direction.

[0057] The blade 80 is applied along the outer edge of the substrate 51 to cut off the unnecessary portion of the optical film 52, thereby manufacturing the optical element 50. The optical element 50 of Example 5 is a reflective polarizing optical element in which a reflective polarizing film is bonded to the substrate 51 via an adhesive layer 53 as the optical film 52.

[0058] (Phase difference measurement) The optical element 50 of Example 5 is evaluated using the KOBRA phase difference measuring device. In Example 5, as shown in Figure 9, the optical film 52 is divided into a central part 52a, a middle band 52b, and an outer peripheral part 52c. The central part 52a is defined as the region within a diameter of 22.5 mm, which corresponds to 50% of the diameter from the center of the optical element 50. The average value RET1 of the phase difference (first phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the central part 52a of the substrate 51 is calculated. The outer peripheral part 52c is defined as the region with a width of 4.5 mm from the edge of the substrate 51. A predetermined region PA is defined as an arc-shaped region with a central angle CA of 90°, which is at least a part of the outer peripheral part 52c and heated by the heating member 79. The average value RET2 of the phase difference (second phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in at least a part of the outer peripheral part 52c of the substrate 51 (predetermined region PA) is calculated. The ratio of the phase difference of the outer periphery 52c (second phase difference) to the phase difference of the central part 52a (first phase difference), calculated from the average values ​​RET1 and RET2, is RET2 / RET1, which is 81%. Therefore, the RET2 / RET1 of the optical element 50 of Example 5 is 97% or less.

[0059] (Appearance evaluation after the end of the durability test) Even after the temperature cycle test of the optical element 50 in Example 5, no lifting or peeling was observed, so the appearance of the optical element 50 in Example 5 is judged to be good (○) as shown in Table 1. According to Example 5, even when the optical element 50 is affected by the environment, it is possible to suppress the occurrence of poor adhesion of the optical film 52 to the outer peripheral portion 52c of the optical element 50. The optical element 50 in Example 5 can be applied to various devices and equipment such as optical instruments, imaging devices, and display devices, similar to Example 1.

[0060] The central angle CA of the predetermined region PA of the optical element 50 in Example 5 is not limited to 90°. Within the range where the RET2 / RET1 of the optical element 50 is 97% or less, the central angle CA of the predetermined region PA may be greater than or less than 90°. It is preferable that the optical film 52 be heated by the heating member 79 in at least a portion of the outer peripheral region of the substrate 51 of the optical element 50. [Examples]

[0061] (Optical element) Next, the optical element 60 of Example 6 will be described using Figure 10. Figure 10 is a diagram showing the optical element 60 of Example 6. Figure 10(a) is a front view of the optical element 60. Figure 10(b) is a cross-sectional view of the optical element 60 taken along the XB-XB line in Figure 10(a). The optical element 60 includes a substrate 61, an optical film 62, and an adhesive layer 63. The substrate 61 has a concave curved surface portion 61a. The optical film 62 is bonded to the curved surface portion 61a of the substrate 61 via the adhesive layer 63. The adhesive layer 63 is formed of, for example, an optically transparent adhesive or tack.

[0062] (Manufacturing method for optical elements) The manufacturing apparatus 70 for producing the optical element 60 of Example 6 is the same as that of Example 1, so its description will be omitted. First, a substrate 61 made of plastic is prepared. The curved portion 61a of the substrate 61 has a diameter of 45 mm. The substrate 61 is a plastic concave lens with a half-opening angle θ of 22°. Next, as the optical film 62, IQPE, a reflective polarizing film manufactured by 3M, is prepared, as in Example 1.

[0063] Similar to Embodiment 1 described in Figure 2, a substrate 61 is placed on the substrate holding section 74 of the manufacturing apparatus 70, and an optical film 62 is placed on the film holding section 73. The bonding temperature of the optical film 62 is set to 150°C, and the optical film 62 is bonded to the substrate 61 via the adhesive layer 63 (bonding step). The substrate 61 to which the optical film 62 has been bonded is removed from the manufacturing apparatus 70, and the arc-shaped portion 61b shown by the dotted line in Figure 10 is cut off (cutting step). At least one location on the substrate 61 may be cut off so that at least a portion of the outer periphery of the substrate 61 that will be post-heated remains. After that, the outer periphery of the substrate 61 (an arc-shaped region with a width of 4.5 mm from the edge) is heated at a post-heating temperature of 200°C by a heating member (heating step). The post-heating temperature in the heating step is higher than the heating temperature in the bonding step. At least a portion of the outer periphery of the substrate 61 to which the optical film 62 has been bonded may be heated by a heating member 79. The blade 80 is applied along the outer edge of the substrate 61 to cut off the unnecessary portion of the optical film 62, thereby manufacturing the optical element 60. The optical element 60 of Example 6 is a reflective polarizing optical element in which a reflective polarizing film is bonded to the substrate 61 via an adhesive layer 63 as the optical film 62. In this embodiment, at least one location of the substrate 61 is cut off before the heating step, but it is not limited to this. After the heating step, at least one location of the substrate 61 may be cut off so that a portion of at least a part of the outer periphery of the substrate 61 that will be heated afterwards remains.

[0064] (Phase difference measurement) The optical element 60 of Example 6 is evaluated using the KOBRA phase difference measuring device. In Example 6, as shown in Figure 10, the segmental circular optical film 62 is divided into a central part 62a, a middle band 62b, and an outer peripheral part 62c. The central part 62a is defined as the region within a diameter of 22.5 mm, which corresponds to 50% of the diameter from the center of the optical element 60. The average value RET1 of the phase difference (first phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the central part 62a of the substrate 61 is calculated. The outer peripheral part 62c is defined as the arc-shaped region with a width of 4.5 mm from the edge of the substrate 61 after removing the arc-shaped portion 61b, which is the region of the optical element 60 heated by the heating member 79. The average value RET2 of the phase difference (second phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the outer peripheral part 62c of the substrate 61 (at least a portion of the outer peripheral part before removing the arc-shaped portion 61b) is calculated. The ratio of the phase difference of the outer periphery 62c (second phase difference) to the phase difference of the central part 62a (first phase difference), calculated from the average values ​​RET1 and RET2, is RET2 / RET1, which is 91%. Therefore, the RET2 / RET1 of the optical element 60 of Example 6 is 97% or less.

[0065] (Appearance evaluation after the end of the durability test) Even after the temperature cycling test of the optical element 60 in Example 6, no lifting or peeling was observed, so the appearance of the optical element 60 in Example 6 is judged to be good (○) as shown in Table 1. According to Example 6, even when the optical element 60 is affected by the environment, it is possible to suppress the occurrence of poor adhesion of the optical film 12 to the outer peripheral portion 62c of the optical element 60. The optical element 60 in Example 6 can be applied to various devices and equipment such as optical instruments, imaging devices, and display devices, similar to Example 1.

[0066] In Example 6, the arc-shaped portion 61b is cut off from the substrate 61 after the optical film 62 has been bonded. However, the shape of the portion cut off from the substrate 61 is not limited to an arc shape; it may be an arc shape, a crescent shape, or other shapes. Furthermore, the portion cut off from the substrate 61 is not limited to one location; it may be multiple locations. As long as the RET2 / RET1 of the optical element 60 is within the range of 97% or less, at least one portion may be cut off from the substrate 61.

[0067] <Comparative Example> (Optical element of the comparative example) Next, the comparative optical element 90 will be described using Figure 11. Figure 11 is a diagram showing the comparative optical element 90. Figure 11(a) is a front view of the optical element 90. Figure 11(b) is a cross-sectional view of the optical element 90 taken along the line XIB-XIB in Figure 11(a). The optical element 90 includes a substrate 91, an optical film 92, and an adhesive layer 93. The substrate 91 has a concave curved surface portion 91a. The optical film 92 is bonded to the curved surface portion 91a of the substrate 91 via the adhesive layer 93. The adhesive layer 93 is formed of, for example, an optically transparent adhesive or tack.

[0068] (Method of manufacturing the optical element of the comparative example) The manufacturing apparatus 70 for producing the comparative optical element 90 is the same as in Example 1, so its description will be omitted. First, a substrate 91 made of plastic is prepared. The curved portion 91a of the substrate 91 has a diameter of 45 mm. The substrate 91 is a plastic concave lens with a half-opening angle θ of 22°. Next, as the optical film 92, IQPE, a reflective polarizing film manufactured by 3M, is prepared, as in Example 1.

[0069] Similar to Example 1 described in Figure 2, a substrate 91 is placed on the substrate holding section 74 of the manufacturing apparatus 70, and an optical film 92 is placed on the film holding section 73. The bonding temperature of the optical film 92 is set to 150°C, and the optical film 92 is bonded to the substrate 91 via the adhesive layer 93. After the substrate 91 with the bonded optical film 92 is removed from the manufacturing apparatus 70, a heating step is not performed in which the outer periphery of the substrate 91 is heated by the heating member 79. The blade 80 is applied along the outer edge of the substrate 91 to cut off the unnecessary portion of the optical film 92, and the optical element 90 is manufactured. The optical element 90 of the comparative example is a reflective polarizing optical element in which a reflective polarizing film is bonded to the substrate 91 via the adhesive layer 93 as the optical film 92.

[0070] (Phase difference measurement) The comparative optical element 90 is evaluated using the KOBRA phase difference measuring device. In the comparative example, as shown in Figure 11, the optical film 92 is divided into a central part 92a, a middle band 92b, and an outer peripheral part 92c. The central part 92a is defined as a region with a diameter of 22.5 mm, corresponding to 50% of the diameter from the center of the optical element 90. The average value RET1 of the phase difference (first phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction at the central part 92a of the substrate 91 is calculated. The outer peripheral part 92c is defined as a region with a width of 4.5 mm from the edge of the substrate 91 of the optical element 90. The average value RET2 of the phase difference (second phase difference) between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction at the outer peripheral part 92c of the substrate 91 is calculated. The ratio RET2 / RET1, which is the ratio of the phase difference of the outer periphery 92c (second phase difference) to the phase difference of the central part 92a (first phase difference) calculated from the average values ​​RET1 and RET2, is 101%. Therefore, the RET2 / RET1 of the comparative optical element 90 is greater than 97%.

[0071] (Appearance evaluation after the end of the durability test) In the visual inspection of the comparative optical element 90 after the temperature cycling test, a float was observed at the end of the optical element 90. Therefore, the appearance of the comparative optical element 90 is judged to be NG (×) as shown in Table 1.

[0072] The central areas 12a, 22a, 32a, 42a, 52a, and 62a of substrates 11, 21, 31, 41, 51, and 61 are regions with a diameter corresponding to 50% of the diameter of substrates 11, 21, 31, 41, 51, and 61 from the center of optical elements 10, 20, 30, 40, 50, and 60. 50% of the diameter includes areas from 49.5% to 50.4% of the diameter. However, the central areas 12a, 22a, 32a, 42a, 52a, and 62a may also be regions with a diameter corresponding to 40%, 45%, 55%, or 60% of the diameter, or other diameters less than 50% of the diameter, or 50% or more of the diameter.

[0073] The outer periphery portions 12c, 22c, 32c, 42c, 52c, and 62c of substrates 11, 21, 31, 41, 51, and 61 are regions with a width corresponding to 10% of the diameter of substrates 11, 21, 31, 41, 51, and 61, extending from the edges of the substrates. 10% of the diameter includes 9.5% to 10.4% of the diameter. However, the outer periphery portions 12c, 22c, 32c, 42c, 52c, and 62c may be regions with a width corresponding to 7%, 8%, 9%, 11%, 12%, or 13% of the diameter.

[0074] The substrates 11, 21, 31, 41, and 51 in Examples 1 to 5 are circular, but the shape of the substrates 11, 21, 31, 41, and 51 is not limited to this. The substrates 11, 21, 31, 41, and 51 may be rectangular, rhombus, trapezoidal, triangular, polygonal, segmental, or other shapes.

[0075] In Examples 1 to 4, the optical films 12, 22, 32, and 42 are heated by the heating element 79 over substantially the entire area of ​​the outer periphery portions 12c, 22c, 32c, and 42c of the substrates 11, 21, 31, and 41 after bonding. However, the optical films 12, 22, 32, and 42 may also be heated by the heating element 79 over at least a portion of the outer periphery portions 12c, 22c, 32c, and 42c of the substrates 11, 21, 31, and 41 after bonding.

[0076] (Configuration 1) An optical element comprising a uniaxially stretched optical film and a substrate, wherein the optical film is bonded to the curved surface of the substrate via an adhesive layer, characterized in that the second phase difference between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in at least a portion of the outer periphery of the substrate is small with respect to a first phase difference between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the central part of the substrate. (Configuration 2) An optical element comprising a uniaxially stretched reflective polarizing film and a substrate, wherein the reflective polarizing film is bonded to the curved surface of the substrate via an adhesive layer, characterized in that the second phase difference between the polarizing component in the reflective axis direction and the polarizing component in the transmission axis direction in at least a portion of the outer peripheral portion of the substrate is small with respect to a first phase difference between the polarizing component in the reflective axis direction and the polarizing component in the transmission axis direction in the central part of the substrate. (Configuration 3) An optical element comprising a uniaxially stretched phase difference film and a substrate, wherein the phase difference film is bonded to the curved surface of the substrate via an adhesive layer, characterized in that the second phase difference between the polarization component in the slow phase axis direction and the polarization component in the fast phase axis direction in at least a portion of the outer peripheral region of the substrate is small with respect to the first phase difference between the polarization component in the slow phase axis direction and the polarization component in the fast phase axis direction in the central part of the substrate. (Configuration 4) The optical element according to any one of Configurations 1 to 3, characterized in that the ratio of the second phase difference to the first phase difference is 97% or less. (Configuration 5) The optical element according to any one of Configurations 1 to 4, characterized in that the partial region having the second phase difference is located at each of the opposing ends of the substrate. (Configuration 6) The optical element according to any one of Configurations 1 to 5, characterized in that the adhesive layer is formed of an optically transparent adhesive or tack. (Configuration 7) The optical element according to any one of Configurations 1 to 6, characterized in that the substrate is circular, the central part is a region with a diameter corresponding to 50% of the diameter of the substrate from the center of the substrate, and the outer periphery is a region with a width corresponding to 10% of the diameter of the substrate from the edge of the substrate. (Configuration 8) The optical element according to any one of Configurations 1 to 6, characterized in that the substrate has a circular, rectangular, rhombus, trapezoidal, triangular, polygonal, segmental, or other shape. (Configuration 9) An optical instrument comprising a lens barrel and an optical element according to any one of Configurations 1 to 8 arranged inside the lens barrel. (Configuration 10) An imaging device comprising a main body, an optical element described in any one of Configurations 1 to 8, and an image sensor disposed within the main body for receiving an image formed by the optical element. (Configuration 11) A display device comprising a housing, an optical system disposed within the housing, and a display unit that emits light guided by the optical system, wherein the optical system includes the optical element described in any one of Configurations 1 to 8. (Method 1) A method for manufacturing an optical element, comprising the steps of: bonding a uniaxially stretched optical film to a curved surface of a substrate via an adhesive layer; and heating at least a portion of the outer periphery of the substrate to which the optical film is bonded. (Method 2) The method for manufacturing an optical element according to Method 1, characterized in that the bonding step is performed such that the second phase difference between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in at least a portion of the outer periphery of the substrate becomes smaller with respect to the first phase difference between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the central part of the substrate. (Method 3) The method for manufacturing an optical element according to Method 1 or 2, characterized in that the bonding step is performed while the device is heated, and the heating temperature in the bonding step is higher than the heating temperature in the bonding step. (Method 4) A method for manufacturing an optical element according to any one of Methods 1 to 3, further comprising the step of cutting off at least one location of the substrate after the heating step, such that a portion of at least a part of the outer periphery remains. (Method 5) A method for manufacturing an optical element according to any one of Methods 1 to 4, characterized in that the optical film is a reflective polarizing film or a phase difference film. [Explanation of symbols]

[0077] 10, 20, 30, 40, 50, 60, 90 ····· Optical elements 11, 21, 31, 41, 51, 61, 91 ····· Circuit board 11a, 21a, 31a, 41a, 51a, 61a, 91a... Curved section 12, 22, 32, 42, 52, 62, 92 ····· Optical film 12a, 22a, 32a, 42a, 52a, 62a, 92a... Center 12c, 22c, 32c, 42c, 52c, 62c, 92c...Outer periphery 13, 23, 33, 43, 53, 63, 93... Adhesive layer 70 Optical element manufacturing equipment 71 First Chamber 71a Opening of the first chamber 72 Second Chamber 72a Opening of the second chamber 73 Film holding section 74 Board holding part 75 Lifting Member 76 sealing member 77 Vacuum equipment 78 Infrared Heater 79 Heating element

Claims

1. An optical element comprising a uniaxially stretched optical film and a substrate, wherein the optical film is bonded to the curved surface of the substrate via an adhesive layer, An optical element characterized in that, with respect to a first phase difference between a polarization component in the stretching direction and a polarization component in a direction perpendicular to the stretching direction at the center of the substrate, the second phase difference between a polarization component in the stretching direction and a polarization component in a direction perpendicular to the stretching direction at least in a portion of the outer periphery of the substrate is small.

2. An optical element comprising a uniaxially stretched reflective polarizing film and a substrate, wherein the reflective polarizing film is bonded to the curved surface of the substrate via an adhesive layer, An optical element characterized in that, with respect to a first phase difference between the polarization component in the reflection axis direction and the polarization component in the transmission axis direction at the center of the substrate, the second phase difference between the polarization component in the reflection axis direction and the polarization component in the transmission axis direction at least a portion of the outer periphery of the substrate is small.

3. An optical element comprising a uniaxially stretched phase difference film and a substrate, wherein the phase difference film is bonded to the curved surface of the substrate via an adhesive layer, An optical element characterized in that, with respect to a first phase difference between the polarization component in the slow phase axis direction and the polarization component in the fast phase axis direction in the central part of the substrate, the second phase difference between the polarization component in the slow phase axis direction and the polarization component in the fast phase axis direction in at least a portion of the outer peripheral part of the substrate is small.

4. The optical element according to claim 1, characterized in that the ratio of the second phase difference to the first phase difference is 97% or less.

5. The optical element according to claim 1, characterized in that the partial region having the second phase difference is located at each of the opposing ends of the substrate.

6. The optical element according to claim 1, characterized in that the adhesive layer is formed of an optically transparent adhesive or tack.

7. The aforementioned substrate is circular, The central area is a region with a diameter corresponding to 50% of the diameter of the substrate, extending from the center of the substrate. The optical element according to any one of claims 1 to 6, characterized in that the outer peripheral portion is a region with a width corresponding to 10% of the diameter of the substrate, extending from the edge of the substrate.

8. The optical element according to any one of claims 1 to 6, characterized in that the substrate has a circular, rectangular, rhombus, trapezoidal, triangular, polygonal, segmental, or other shape.

9. The telescope tube and An optical element according to any one of claims 1 to 6, disposed inside the lens barrel, An optical instrument characterized by being equipped with the following features.

10. The main unit and An optical element according to any one of claims 1 to 6, An imaging device characterized by comprising an image sensor disposed within the main body and receiving light from an image formed by the optical element.

11. The casing and An optical system arranged inside the aforementioned housing, A display unit that emits light guided by the optical system, Equipped with, The optical system is characterized by including the optical element described in any one of claims 1 to 6.

12. A process of bonding a uniaxially stretched optical film to a curved surface of a substrate via an adhesive layer, A step of heating at least a portion of the outer periphery of the substrate to which the optical film is bonded, A method for manufacturing an optical element characterized by including

13. The method for manufacturing an optical element according to claim 12, characterized in that the bonding step is performed such that the second phase difference between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in at least a portion of the outer periphery of the substrate becomes smaller with respect to the first phase difference between the polarization component in the stretching direction and the polarization component in the direction perpendicular to the stretching direction in the central part of the substrate.

14. The bonding process is carried out while the device is heated. The method for manufacturing an optical element according to claim 12, characterized in that the heating temperature in the heating step is higher than the heating temperature in the bonding step.

15. The method for manufacturing an optical element according to claim 12, further comprising the step of cutting off at least one location of the substrate after the heating step, such that a portion of at least a part of the outer periphery remains.

16. The method for manufacturing an optical element according to any one of claims 12 to 15, characterized in that the optical film is a reflective polarizing film or a phase difference film.

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