Optical system and display device

Abstract

There is provided an optical system including a first optical system including a first reflective surface reflecting light emitted from a pupil side toward the pupil side and a second reflective surface reflecting light reflected toward the pupil side toward a display element side, and a second optical system including a second reflective surface reflecting light emitted from the pupil side toward the display element side. The first reflective surface has a concave shape and forms an intermediate image on the pupil side, the pupil side of the first reflective surface being filled with a material having a refractive index greater than 1, and the second optical system is placed on the display element side with respect to an intermediate image plane in which the intermediate image is formed, and a second optical system including an intermediate imaging plane and configured such that the intermediate imaging plane and the display element surface have a conjugate relationship, the second optical system including at least three lenses, two of the at least three lenses having different Abbe numbers from each other, and the second optical system having a positive refractive power as a whole.

Description

Technical Field

[0001] This disclosure relates to an optical system and a display device. Background Technology

[0002] A technique is known for displaying images rendered using augmented reality (AR) or virtual reality (VR) on, for example, a head-mounted display (HMD) or AR glasses (display device) worn by a user.

[0003] Reference List

[0004] Patent documents

[0005] PTL 1: JP 2010-122573 A Summary of the Invention

[0006] Technical issues

[0007] There is a desire for HMDs, AR glasses, and other display devices to be small in size, as they are worn on the user's head. Furthermore, it is desirable for the optical systems included in HMDs or AR glasses to have high optical performance and a wide viewing angle to provide users with realistic images. However, in the related technologies proposed so far, there are limitations to achieving optical systems with high optical performance and a wide viewing angle that also allow for a reduction in the size of HMDs or AR glasses.

[0008] Therefore, this disclosure proposes an optical system and a display device including the optical system, which has high optical performance and a wide field of view and enables the display device (such as an HMD or AR glasses) to be reduced in size.

[0009] Solution to the problem

[0010] According to this disclosure, an optical system is provided, comprising a first optical system and a second optical system sequentially from the user's pupil side to the display element side. The first optical system includes a first reflective surface and a second reflective surface. The first reflective surface reflects light emitted from the pupil side toward the pupil side, and the second reflective surface reflects light reflected toward the pupil side toward the display element side. The first reflective surface has a concave shape and forms an intermediate image on the pupil side. The pupil side of the first reflective surface is filled with a material having a refractive index greater than 1. The second optical system is placed on the display element side relative to the intermediate imaging plane forming the intermediate image and is configured such that the intermediate imaging plane and the display element surface have a conjugate relationship. The second optical system includes at least three lenses, two of which have different Abbe numbers, and the second optical system as a whole has positive power.

[0011] Additionally, according to this disclosure, a display device is provided, comprising a first optical system, a second optical system, and a display element from the pupil side. The first optical system includes a first reflective surface and a second reflective surface. The first reflective surface reflects light emitted from the pupil side toward the pupil side, and the second reflective surface reflects light reflected toward the pupil side toward the display element side. The first reflective surface has a concave shape and forms an intermediate image on the pupil side. The pupil side of the first reflective surface is filled with a material having a refractive index greater than 1. The second optical system is placed on the display element side relative to the intermediate imaging plane forming the intermediate image and is configured such that the intermediate imaging plane and the display element surface have a conjugate relationship. The second optical system includes at least three lenses, two of which have different Abbe numbers, and the second optical system as a whole has positive power. Attached Figure Description

[0012] Figure 1 Explanatory diagrams (part 1) are included to illustrate an overview of embodiments of this disclosure.

[0013] Figure 2 This is an explanatory diagram (part 2) for illustrating an overview of embodiments of the present disclosure.

[0014] Figure 3 Explanatory diagrams (part 3) are included to illustrate the overview of embodiments of this disclosure.

[0015] Figure 4 This is an explanatory diagram (part 4) used to explain the overview of embodiments of this disclosure.

[0016] Figure 5 Explanatory diagrams (part 5) are included to illustrate the overview of embodiments of this disclosure.

[0017] Figure 6 This is an explanatory diagram (part 6) used to explain the overview of embodiments of this disclosure.

[0018] Figure 7 Explanatory diagrams (part 7) are included to illustrate the overview of embodiments of this disclosure.

[0019] Figure 8 This is a schematic diagram illustrating an example structure of an optical system according to a first embodiment of the present disclosure.

[0020] Figure 9 This is a diagram illustrating an example of lens data of an optical system according to a first embodiment of the present disclosure.

[0021] Figure 10 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to a first embodiment of the present disclosure.

[0022] Figure 11 A diagram (part 1) showing aberration data of an optical system according to a first embodiment of the present disclosure.

[0023] Figure 12 A diagram (part 2) showing aberration data of an optical system according to a first embodiment of the present disclosure.

[0024] Figure 13 This is an explanatory diagram illustrating a variant of the first embodiment of this disclosure.

[0025] Figure 14 This is a schematic diagram illustrating an example of the structure of an optical system according to a second embodiment of the present disclosure.

[0026] Figure 15 This is a diagram illustrating an example of lens data of an optical system according to a second embodiment of the present disclosure.

[0027] Figure 16 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to a second embodiment of the present disclosure.

[0028] Figure 17 A diagram (part 1) showing aberration data of an optical system according to a second embodiment of the present disclosure.

[0029] Figure 18 A diagram (part 2) showing aberration data of an optical system according to a second embodiment of the present disclosure.

[0030] Figure 19 This is a schematic diagram illustrating an example structure of an optical system according to a third embodiment of the present disclosure.

[0031] Figure 20 This is a diagram illustrating an example of lens data for an optical system according to a third embodiment of the present disclosure.

[0032] Figure 21 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to a third embodiment of the present disclosure.

[0033] Figure 22 A diagram (part 1) showing aberration data of an optical system according to a third embodiment of the present disclosure.

[0034] Figure 23 A diagram (part 2) showing aberration data of an optical system according to a third embodiment of the present disclosure.

[0035] Figure 24 This is a schematic diagram illustrating an example structure of an optical system according to a fourth embodiment of the present disclosure.

[0036] Figure 25 This is a diagram illustrating an example of lens data for an optical system according to a fourth embodiment of the present disclosure.

[0037] Figure 26 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to a fourth embodiment of the present disclosure.

[0038] Figure 27 A diagram (part 1) showing aberration data of an optical system according to a fourth embodiment of the present disclosure.

[0039] Figure 28 A diagram (part 2) showing aberration data of an optical system according to a fourth embodiment of the present disclosure.

[0040] Figure 29 These are explanatory diagrams used to explain the overview of the fifth embodiment of this disclosure.

[0041] Figure 30 This is a schematic diagram illustrating an example structure of an optical system according to a fifth embodiment of the present disclosure.

[0042] Figure 31 This is a diagram illustrating an example of lens data for an optical system according to a fifth embodiment of the present disclosure.

[0043] Figure 32 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to a fifth embodiment of the present disclosure.

[0044] Figure 33 A diagram (part 1) showing aberration data of an optical system according to a fifth embodiment of the present disclosure.

[0045] Figure 34 A diagram (part 2) showing aberration data of an optical system according to a fifth embodiment of the present disclosure.

[0046] Figure 35 This is a schematic diagram illustrating an example structure of an optical system according to a sixth embodiment of the present disclosure.

[0047] Figure 36 This is a diagram illustrating an example of lens data for an optical system according to a sixth embodiment of the present disclosure.

[0048] Figure 37 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to a sixth embodiment of the present disclosure.

[0049] Figure 38 A diagram (part 1) showing aberration data of an optical system according to a sixth embodiment of the present disclosure.

[0050] Figure 39 A diagram (part 2) showing aberration data of an optical system according to a sixth embodiment of the present disclosure.

[0051] Figure 40 This is a schematic diagram illustrating a structural example of a variant optical system according to a sixth embodiment of the present disclosure.

[0052] Figure 41 Explanatory diagrams are included to illustrate the overview of the seventh embodiment of this disclosure.

[0053] Figure 42 This is a schematic diagram illustrating an example structure of an optical system according to a seventh embodiment of the present disclosure.

[0054] Figure 43 This is a diagram illustrating an example of lens data for an optical system according to a seventh embodiment of the present disclosure.

[0055] Figure 44 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to a seventh embodiment of the present disclosure.

[0056] Figure 45 A diagram showing aberration data of an optical system according to a seventh embodiment of the present disclosure.

[0057] Figure 46 This is a schematic diagram illustrating an example structure of an optical system according to an eighth embodiment of the present disclosure.

[0058] Figure 47 This is a diagram illustrating an example of lens data for an optical system according to an eighth embodiment of the present disclosure.

[0059] Figure 48 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to an eighth embodiment of the present disclosure.

[0060] Figure 49 A diagram showing aberration data of an optical system according to an eighth embodiment of the present disclosure.

[0061] Figure 50 This is a schematic diagram illustrating an example structure of an optical system according to a ninth embodiment of the present disclosure.

[0062] Figure 51 This is a diagram illustrating an example of lens data for an optical system according to a ninth embodiment of the present disclosure.

[0063] Figure 52 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to a ninth embodiment of the present disclosure.

[0064] Figure 53A diagram showing aberration data of an optical system according to a ninth embodiment of the present disclosure.

[0065] Figure 54 This is a schematic diagram illustrating an example structure of an optical system according to a tenth embodiment of the present disclosure.

[0066] Figure 55 This is a diagram illustrating an example of lens data for an optical system according to a tenth embodiment of the present disclosure.

[0067] Figure 56 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to the tenth embodiment of the present disclosure.

[0068] Figure 57 A diagram (part 1) showing aberration data of an optical system according to the tenth embodiment of this disclosure.

[0069] Figure 58 A diagram (part 2) showing aberration data of an optical system according to the tenth embodiment of this disclosure.

[0070] Figure 59 The diagram includes a schematic structural example of an optical system according to the eleventh embodiment of the present disclosure.

[0071] Figure 60 This is a diagram illustrating an example of lens data for an optical system according to the eleventh embodiment of the present disclosure.

[0072] Figure 61 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to the eleventh embodiment of the present disclosure.

[0073] Figure 62 A diagram (part 1) showing aberration data of an optical system according to the eleventh embodiment of the present disclosure.

[0074] Figure 63 A diagram (part 2) showing aberration data of an optical system according to the eleventh embodiment of the present disclosure.

[0075] Figure 64 A diagram (part 3) showing aberration data of an optical system according to the eleventh embodiment of the present disclosure.

[0076] Figure 65 A diagram (part 4) showing aberration data of an optical system according to the eleventh embodiment of the present disclosure.

[0077] Figure 66 This includes a diagram (part 1) illustrating an example arrangement of the light source and camera according to the eleventh embodiment of the present disclosure.

[0078] Figure 67The illustration includes a diagram showing an example of imaging using a camera according to the eleventh embodiment of the present disclosure.

[0079] Figure 68 This is a diagram (part 2) illustrating an example arrangement of the light source and camera according to the eleventh embodiment of the present disclosure.

[0080] Figure 69 This is an explanatory diagram used to explain the overview of the twelfth embodiment of this disclosure.

[0081] Figure 70 This is a schematic diagram illustrating an example structure of an optical system according to the twelfth embodiment of the present disclosure.

[0082] Figure 71 This is a diagram illustrating an example of lens data for an optical system according to the twelfth embodiment of the present disclosure.

[0083] Figure 72 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to the twelfth embodiment of the present disclosure.

[0084] Figure 73 A diagram (part 1) showing aberration data of an optical system according to the twelfth embodiment of the present disclosure.

[0085] Figure 74 A diagram (part 2) showing aberration data of an optical system according to the twelfth embodiment of the present disclosure.

[0086] Figure 75 This is a schematic diagram illustrating an example of the structure of an optical system according to the thirteenth embodiment of the present disclosure.

[0087] Figure 76 This is a diagram illustrating an example of lens data for an optical system according to the thirteenth embodiment of the present disclosure.

[0088] Figure 77 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to the thirteenth embodiment of the present disclosure.

[0089] Figure 78 A diagram showing aberration data of an optical system according to the thirteenth embodiment of this disclosure.

[0090] Figure 79 This is a schematic diagram illustrating an example structure of an optical system according to the fourteenth embodiment of the present disclosure.

[0091] Figure 80 This is a diagram illustrating an example of lens data for an optical system according to the fourteenth embodiment of the present disclosure.

[0092] Figure 81This is a diagram illustrating an example of aspheric coefficient data of an optical system according to the fourteenth embodiment of the present disclosure.

[0093] Figure 82 A diagram showing aberration data of an optical system according to the fourteenth embodiment of this disclosure.

[0094] Figure 83 This is a schematic diagram illustrating an example of the structure of an optical system according to the fifteenth embodiment of the present disclosure.

[0095] Figure 84 This is a diagram illustrating an example of lens data for an optical system according to the fifteenth embodiment of the present disclosure.

[0096] Figure 85 This is a diagram illustrating an example of aspheric coefficient data of an optical system according to the fifteenth embodiment of the present disclosure.

[0097] Figure 86 A diagram showing aberration data of an optical system according to the fifteenth embodiment of this disclosure.

[0098] Figure 87 This is a diagram illustrating data examples of an optical system according to embodiments thirteen through fifteen of this disclosure.

[0099] Figure 88 This is the external view of the head-mounted display. Detailed Implementation

[0100] The preferred embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that in this specification and the drawings, components having substantially the same functional structure are denoted by the same reference numerals, and redundant descriptions will be omitted. Furthermore, in this specification and the drawings, multiple components having substantially the same or similar functional structures can be distinguished from each other by adding different letter characters after the same reference numerals. However, when it is not necessary to specifically distinguish the multiple components having substantially the same or similar functional structures, only the same reference numerals are assigned.

[0101] Furthermore, the accompanying drawings, which will be referenced in the following description, are intended to explain embodiments of this disclosure and facilitate understanding thereof, and for ease of understanding, the shapes, sizes, and scales illustrated in the drawings may differ from actual shapes, sizes, and scales. Additionally, the design of the apparatus illustrated in the drawings can be modified as needed, taking into account the following description and known technology.

[0102] It is important to note that in the following description, "positive power" and "negative power" for a lens refer to the intensity at which the lens bends light, and the power is altered, for example, by adjusting the lens's refractive index or curvature. In the following description, "positive power" in the lens's optical power refers to the intensity at which light bends in the direction in which it is focused (towards the inside of the lens), and "negative power" refers to the intensity at which light bends in the direction in which it is diverged (towards the outside of the lens).

[0103] In the following description, the principal ray refers to the incident light passing through the center of the optical system. Additionally, the upper ray refers to the incident light passing through the edge located above the central axis (optical axis) of the optical system and forming an image, and the lower ray refers to the incident light passing through the edge located below the central axis of the optical system and forming an image. The marginal ray refers to the ray passing through the outer periphery of the pupil plane of the optical system. Furthermore, in the following description, the pupil plane refers to the plane located where the incident light on the optical system intersects the axis of the optical system.

[0104] It should be noted that the descriptions will be presented in the following order.

[0105] 1. Background leading to the creation of the embodiments of this disclosure

[0106] 1.1 Background

[0107] 1.2 Overview

[0108] 1.2.1 Structure 1

[0109] 1.2.2 Structure 2

[0110] 1.2.3 Structure 3

[0111] 1.2.4 Structure 4

[0112] 1.2.5 Structure 5

[0113] 2. First Embodiment

[0114] 2.1 Detailed Structure

[0115] 2.2 Variation

[0116] 3. Second Embodiment

[0117] 4. Third embodiment

[0118] 5. Fourth Embodiment

[0119] 6. Fifth Embodiment

[0120] 6.1 Structure 6

[0121] 6.2 Detailed Structure

[0122] 7. Sixth Embodiment

[0123] 7.1 Detailed Structure

[0124] 7.2 Variation

[0125] 8. Seventh Embodiment

[0126] 8.1 Structure 7

[0127] 8.2 Detailed Structure

[0128] 9. Eighth Embodiment

[0129] 10. Ninth Embodiment

[0130] 11. Tenth Embodiment

[0131] 12. Eleventh Embodiment

[0132] 12.1 Detailed Structure of the Optical System

[0133] 12.2 Eye-tracking mechanism

[0134] 13. Twelfth Embodiment

[0135] 14. Thirteenth Embodiment

[0136] 15. Fourteenth Embodiment

[0137] 16. Fifteenth Embodiment

[0138] 17. Summary

[0139] 18. Application Examples

[0140] 19. Supplement

[0141] 1. Background leading to the creation of the embodiments of this disclosure

[0142] 1.1 Background

[0143] First, the background that led to the creation of the embodiments of this disclosure by the inventors will be described.

[0144] As described above, technologies for displaying images rendered using AR or VR on, for example, HMD or AR glasses worn by a user are known. Such HMD or AR glasses mainly include: a display element for displaying images; and an optical system for guiding the display element to the user's pupils.

[0145] Since these HMD or AR glasses are worn on the user's head, it is desirable for them to be relatively small. Furthermore, it is desirable for the optical system included in the HMD or AR glasses to have high optical performance and a wide field of view (wide field of view) to provide the user with realistic images. In addition, in recent years, there has been a desire to manufacture these HMD or AR glasses at a lower cost for wider use.

[0146] However, in optical systems based on the related technologies proposed so far, it is difficult to avoid using large display elements to achieve a wide field of view. Furthermore, there are limitations in shortening the focal length in these related technologies. In other words, there are limitations in achieving optical systems with high optical performance and a wide field of view that also allow for a reduction in the size of HMD or AR glasses.

[0147] Therefore, considering this scenario, the inventors have created embodiments of this disclosure that implement an optical system capable of reducing the size of HMDs or AR glasses while possessing high optical performance and a wide field of view (e.g., field of view (FOV) = 80 to 120 degrees). In other words, according to embodiments of this disclosure, an optical system can be provided that has high optical performance and a wide field of view, and is capable of reducing the size of HMDs, AR glasses, etc. Hereinafter, an overview of the embodiments of this disclosure created by the inventors will be described sequentially.

[0148] 1.2 Overview

[0149] Next, we will refer to Figures 1 to 7 An overview describing embodiments of this disclosure.

[0150] 1.2.1 Structure 1

[0151] First, refer to Figures 1 to 3 Sections 8 and 9 describe an overview of the common “structure 1” for optical systems according to embodiments of the present disclosure. Figures 1 to 3 These are all explanatory diagrams used to explain the overview of embodiments of this disclosure. Figure 8 This is a schematic diagram illustrating an example structure of an optical system 1 according to a first embodiment, which is an example of an embodiment of this disclosure.

[0152] like Figure 8 As shown, from the user's pupil 500 side (pupil plane 500a side) to the display element 502 side (display element surface 502a side), the optical system 1 according to an embodiment of this disclosure sequentially includes a first optical system 10 and a second optical system 20. It should be noted that... Figure 8The diagram also shows display element 502, which, combined with optical system 1, constitutes a display device. The first optical system 10 includes: a first reflective surface (semi-transmissive reflective surface) 102 that reflects light emitted from the pupil 500 side toward the pupil 500 side; and a second reflective surface 112 that reflects light reflected toward the pupil 500 side toward the display element 502 side. Hereinafter, this structure of the first optical system 10 is referred to as "Element 1". The first reflective surface 102 has a concave shape on the pupil 500 side, and this concave shape allows the first reflective surface 102 to form an intermediate image 510 on the pupil 500 side. Hereinafter, this structure of the first reflective surface 102 is referred to as "Element 2". The pupil 500 side of the first reflective surface 102 is filled with a material having a refractive index greater than 1. Hereinafter, this structure of the first reflective surface 102 is referred to as "Element 3". Furthermore, the second optical system 20 is positioned on the display element 502 side relative to the intermediate imaging plane 510a forming the intermediate image 510, and is configured such that the intermediate imaging plane and the surface of the display element have a conjugate relationship. The second optical system 20 includes at least three lenses, two of which have different Abbe numbers, and the second optical system 20 as a whole has positive optical power. Hereinafter, this structure of the second optical system is referred to as "Element 4". Additionally, the entire structure including Elements 1 to 4 described above is referred to as "Structure 1". It should be noted that the Abbe number is a quantity related to the light dispersion of a transparent material (such as optical glass) and is the reciprocal of the dispersion rate. The larger the Abbe number, the smaller the change in refractive index with wavelength.

[0153] Element 1

[0154] First, refer to Figure 1 Explanation of element 1. Specifically, a first optical system 10 having a reflective surface 102 is shown in... Figure 1 The first optical system 10, which is located in the upper part and has two reflective surfaces 102 and 112, is shown in Figure 1 In the lower part. From Figure 1 It is clear that the first optical system 10 includes two reflective surfaces 102 and 112, and therefore, the optical path can be folded, and the length of the optical system 1 in the optical axis direction can be shortened.

[0155] Element 2

[0156] Next, we will refer to Figure 2 Explain element 2. Figure 2 This illustrates a typical ophthalmic optical system without an intermediate imaging plane. (As shown from...) Figure 2 As can be seen from the expression shown, while maintaining the size d of the panel (display element)... LCOS At the same time, when the field of view angle θ FOVAs the focal length d increases, the focal length f decreases. For example, when the panel size d... LCOS The size was reduced from 1.3 inches to 0.7 inches and the field of view θ FOV When the angle changes from 70 degrees to 120 degrees, the focal length f decreases to approximately 1 / 5. However, in situations such as Figure 2 The structure shown in the diagram is difficult to implement due to the need to ensure optical performance (such as field curvature correction and lateral chromatic aberration correction).

[0157] With this in mind, in embodiments of this disclosure, optical system 1 has an intermediate imaging plane 510a, and therefore, two separate optical systems can be provided with the intermediate imaging plane 510a inserted between them. That is, the functions and roles of the first optical system 10 for increasing the field of view and the second optical system 20 for reducing the size of the panel (display element 502) can be separated. In embodiments of this disclosure, by using two optical systems 10 and 20 with different functions as described above, both an increase in the field of view and a reduction in the size of the panel (display element 502) can be achieved.

[0158] Element 3

[0159] Next, we will refer to Figure 3 Explain element 3. Filling the pupil 500 side of the first reflective surface 102 with a material having a refractive index greater than 1 has two effects. As the first effect, such as Figure 3 As shown on the left, by further applying semi-transmissive reflective properties to the first reflective surface 102, the length of the first optical system 10 in the height direction can also be shortened. As a second effect, such as... Figure 3 As shown on the right, through the first optical system 10, the optical path length can be increased from the air length L by (n-1)L due to the refractive index n. Therefore, while maintaining the size of the first optical system 10, the curvature can be reduced, and thus, the occurrence of aberrations can be suppressed, and the optical performance can be improved.

[0160] Element 4

[0161] Next, element 4 will be described. Since the second optical system 20 has a conjugate relationship between the intermediate imaging plane and the display element surface, the second optical system 20 itself must compensate for each aberration. Therefore, in embodiments of this disclosure, a technique called an astigmatism-correcting lens is used to eliminate spherical aberration, coma, field curvature, and astigmatism. In embodiments of this disclosure, all spherical aberration, coma, field curvature, and astigmatism are corrected by using, for example, a structure of three lenses or three lens groups. However, in the case where chromatic aberration is corrected by a refractive lens, this cannot be achieved by using three lenses with the same Abbe number, and therefore, in embodiments of this disclosure, two of the plurality of lenses have different Abbe numbers from each other.

[0162] In each embodiment of the present disclosure, since a structure 1 including the elements 1 to 4 described above is provided, an optical system 1 can be provided, which has high optical performance and a wide field of view, and can reduce the size of HMDs, AR glasses, etc.

[0163] 1.2.2 Structure 2

[0164] Next, we will refer to Figure 4 and 8 An overview of an optical system according to embodiments of the present disclosure (specifically, “structure 2” common to the first through sixth, tenth and eleventh embodiments of the present disclosure). Figure 4 These are explanatory diagrams used to illustrate an overview of embodiments of this disclosure.

[0165] like Figure 8As shown, from the pupil 500 side to the display element 502 side, the first optical system 10 according to an embodiment of the present disclosure sequentially includes, for example, a first optical element 100 and a second optical element 110. The first optical element 100, as a second reflective surface 112, functions to reflect a portion of the light. The second optical element 110 includes a transmissive surface 104 and a semi-transmissive reflective surface 102, which, as the first reflective surface, is positioned relative to the transmissive surface 104 on the display element 502 side and has a concave shape. Furthermore, the space between the transmissive surface 104 and the semi-transmissive reflective surface 102 is filled with a material having a refractive index greater than 1.4 and less than 2.2. Specifically, the first optical system 10 is configured such that light emitted from the pupil 500 side is transmitted through the first optical element 100, passes through the transmissive surface 104, is reflected by the semi-transmissive reflective surface 102, passes through the transmissive surface 104, is reflected by the first optical element 100, passes through the transmissive surface 104, and passes through the semi-transmissive reflective surface 102. The second optical system 20 is configured to have positive optical power as a whole relative to the light from the first optical system 10. Specifically, all surfaces of the second optical system 20 have a common axis of rotational symmetry. Furthermore, in embodiments of this disclosure, an intermediate image 510 is formed between the semi-transmissive reflective surface 102 of the second optical element 110 and the first optical element 100. Additionally, when the focal length of the semi-transmissive reflective surface 102 is represented by fR and the physical length from the surface of the first optical element 100 on the display element 502 side to the surface vertex of the semi-transmissive reflective surface 102 is represented by LR, the following expression (1) is preferably satisfied. Hereinafter, this structure of the optical system is referred to as "structure 2".

[0166] [Mathematical Expression 1]

[0167]

[0168] Next, we will refer to Figure 4 Explanation of Structure 2. Typically, to reduce the overall size of an optical system, the optical power of each surface included in the optical system must be increased. Therefore, in embodiments of this disclosure, by increasing the optical power of the semi-transparent reflective surface 102, such as... Figure 4 As shown, compared to the comparative example, the focal point is formed closer to the first optical element 100. As a result, the distance between the first optical element 100 and the display element 502 can be shortened, and therefore, the size of the optical system 1 can be reduced.

[0169] Furthermore, when LR / fR exceeds the upper limit (1.2), the optical power of the semi-transparent reflective surface 102 increases, which helps to reduce the size of the optical system 1, but aberrations occur, and therefore, the optical performance is reduced. On the other hand, when LR / fR is less than the lower limit (0.5), the optical power of the semi-transparent reflective surface 102 is reduced, and therefore, the intermediate imaging plane 510a moves toward the display element 502 side, resulting in an increase in the size of the optical system 1. Therefore, in the embodiments of this disclosure, in order to reduce the size of the optical system 1 while avoiding a reduction in optical performance, LR / fR is preferably set as in the above expression (1).

[0170] As described above, preferably, embodiments of the present disclosure have a structure 2, and by operating in such a way, an optical system 1 can be provided, which has high optical performance and a wide field of view, and can reduce the size of HMDs, AR glasses, etc.

[0171] 1.2.3 Structure 3

[0172] Next, we will refer to Figure 5 and 8 An overview describing an optical system according to embodiments of the present disclosure (specifically, “structure 3” common to the first through fourth embodiments of the present disclosure). Figure 5 Explanatory diagrams are included to illustrate the overview of embodiments of this disclosure.

[0173] like Figure 8 As shown, from the pupil 500 side to the display element 502 side, the second optical system 20 according to an embodiment of the present disclosure sequentially includes, for example: a first lens group 210 having negative optical power; and a second lens group 220 having positive optical power. Furthermore, when the optical power of the first lens group 210 is represented by Φ1 and the optical power of the entire second optical system 20 is represented by Φ, preferably, the following expression (2) is satisfied. Hereinafter, this structure of the optical system is referred to as "structure 3".

[0174] [Mathematical Expression 2]

[0175]

[0176] Next, we will refer to Figure 5 Explain structure 3. Specifically, Figure 5 The upper part of the diagram shows a second optical system 20, which includes a lens with positive optical power, and Figure 5The lower part of the diagram illustrates a second optical system 20, which includes a lens with positive optical power and a lens with negative optical power. In the first optical system 10, the optical power of the semi-transparent reflective surface 102 is increased to achieve a wide angle and a smaller size. As a result, the curvature of the semi-transparent reflective surface 102 is increased, and therefore, the light reflected by the semi-transparent reflective surface 102 is incident on the second optical system 20 while maintaining a large angle. In this case, as... Figure 5 As shown in the upper part, in the second optical system 20 which only includes lenses with positive optical power, when the length of the optical system 1 in the optical axis direction is shortened, it is difficult to guide a group of rays with large angles incident on the outermost periphery of the incident surface of the second optical system 20 toward the display element 502 side. On the other hand, as Figure 5 As shown in the lower part, in the second optical system 20, which includes lenses with positive and negative optical powers, even when the length of the optical system 1 in the optical axis direction is shortened, a group of rays with large angles incident on the outermost periphery of the incident surface of the second optical system 20 can be refracted upwards and guided to the display element 502 side. Therefore, according to structure 3, the size of the display element 502 can be reduced while shortening the length of the optical system 1 in the optical axis direction, and for example, in this embodiment, a display element 502 size of 1 inch or less (diagonal length) can be achieved.

[0177] When Φ1 / Φ exceeds the upper limit (-0.2), the optical power Φ1 of the first lens group 210 with negative optical power becomes too large, and the occurrence of aberrations increases, thus reducing optical performance. On the other hand, when Φ1 / Φ is less than the lower limit (-0.5), the optical power Φ1 of the first lens group 210 with negative optical power is reduced, and thus, the size of the optical system 1 increases. Therefore, in the embodiments of this disclosure, in order to reduce the size of the optical system 1 while avoiding a decrease in optical performance, Φ1 / Φ is preferably set as in the above expression (2).

[0178] As described above, preferably, embodiments of the present disclosure have structure 3, and by operating in such a way, an optical system 1 can be provided, which has high optical performance and a wide field of view, and can reduce the size of HMDs, AR glasses, etc.

[0179] 1.2.4 Structure 4

[0180] Next, we will refer to Figure 5 , 6 Sections 8 and 9 describe an overview of an optical system according to embodiments of the present disclosure (specifically, “structure 4” common to the first through fourth embodiments of the present disclosure). Figure 6 These are explanatory diagrams used to illustrate an overview of embodiments of this disclosure.

[0181] For example, according to an embodiment of the present disclosure, the first lens group 210 is adjacent to the second optical element 110 on the display element 502 side and has the function of reducing the angle of light at the periphery, such as... Figure 8 As shown. Additionally, as... Figure 6 As shown, when the angle of the principal ray from the second optical element 110 toward the display element 502 at its outermost position is represented by Ang1 and the angle of the principal ray from the first lens group 210 toward the second lens group 220 at its outermost position is represented by Ang2, preferably, the following expression (3) is satisfied. Hereinafter, this structure of the optical system is referred to as "structure 4".

[0182] [Mathematical Expression 3]

[0183]

[0184] When Ang1 / Ang2 exceeds the upper limit (3.5), the amount of light refracted by the first lens group 210 becomes too large, and it becomes difficult to guide the light to the display element 502 side. On the other hand, when Ang1 / Ang2 is below the lower limit (1.7), the amount of light refracted by the first lens group 210 becomes too small, and the size of the optical system 1 becomes large. Therefore, in the embodiments of this disclosure, in order to reduce the size of the optical system 1, it is preferable to set Ang1 / Ang2 as in the above expression (3).

[0185] As described above, preferably, embodiments of the present disclosure have structure 4, and by operating in this way, an optical system 1 can be provided, which has high optical performance and a wide field of view, and can achieve a reduction in size for HMDs, AR glasses, etc.

[0186] 1.2.5 Structure 5

[0187] Next, we will refer to Figure 6 , 7 Sections 8 and 9 provide an overview of an optical system according to embodiments of the present disclosure (specifically, “structure 5” common to the first, second, and tenth embodiments of the present disclosure). Figure 7 Explanatory diagrams are included to illustrate the overview of embodiments of this disclosure.

[0188] In embodiments of this disclosure, for example, such as Figure 6 As shown, the angle of the lower ray incident on the second lens group 220 from the edge ray of the light rays incident from the pupil plane 500a at a viewing angle of 60 degrees is represented by Ang3, and the angle of the lower ray incident on the display element 502 from the second lens group 220 is represented by Ang4. Additionally, as... Figure 7As shown, the distance on the optical axis 520 between the pupil plane 500a and the surface of the first optical element 100 located closest to the pupil plane 500a is represented by A. Furthermore, when the pupil 500 is separated from the first optical element 100 in the direction of the optical axis 520, the viewing angle is 60 degrees, and there is no ray vignetting in the second optical system 20, the distance on the optical axis 520 between the pupil plane 500a and the surface of the first optical element 100 located closest to the pupil plane 500a is represented by A'. Additionally, the exit pupil position of the first optical system 10 at distance A is represented by P, and the exit pupil position of the first optical system 10 at distance A' is represented by P'. In this case, in the embodiment of this disclosure, preferably, the following expression (4) is satisfied. Hereinafter, this structure of the optical system is referred to as "structure 5".

[0189] [Mathematical Expression 4]

[0190]

[0191] like Figure 7 As shown, when the user moves from a state of focusing on the center ( Figure 7 The upper left side of the eye changes to a state where the eyeballs move to look outwards. Figure 7 When the user's pupil is tilted (to the lower right side), it moves from the optical axis 520 in a direction substantially perpendicular to the optical axis 520. Therefore, in the embodiments of this disclosure, in this case, the change in optical path between the pupil 500 and the display element 502 is addressed by implementing a design that assumes distance A becomes distance A'. Since the light from the first optical system 10 passes through the lower side of the optical axis 520 due to this change in optical path, when distance A' is longer than distance A, the light deviates from the interior of the second optical system 20, that is, the probability of vignetting of the set of light rays increases.

[0192] Therefore, to avoid this vignetting of the light rays, the light rays incident on the second lens group 220 must be brought closer to the optical axis 520. Therefore, to ensure that the angle of the light rays incident on the second lens group 220 returns to the optical axis 520, it is preferable that the above expression (4) is satisfied. It should be noted that when Ang4 / Ang3 is less than the lower limit (-7), vignetting occurs because Ang3 is large. On the other hand, when Ang4 / Ang3 exceeds the upper limit (1.5), the positive optical power of the second lens group 220 becomes too large, and the optical performance of the optical system 1 decreases. Therefore, in the embodiments of this disclosure, it is preferable that the above expression (4) is satisfied.

[0193] As described above, preferably, the embodiments of this disclosure have structure 5, and by operating in such a way, an optical system 1 can be provided that has high optical performance and a wide field of view even taking into account the rotation of the pupil 500, and can achieve a reduction in the size of HMDs, AR glasses, etc.

[0194] In other words, as described above, in this embodiment, optical system 1 and optical system 1a, having at least one of the structures 1 to 5 described above, can achieve a reduction in the size of HMDs, AR glasses, etc., while possessing high optical performance and a wide field of view. Hereinafter, details of each embodiment of the present disclosure will be described.

[0195] 2. First Embodiment

[0196] 2.1 Detailed Structure

[0197] First, refer to Figures 8 to 10 An optical system 1 according to a first embodiment of the present disclosure is described. Figure 8 This is a schematic diagram illustrating an example of the structure of the optical system 1 according to this embodiment. Figure 9 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment. Specifically, the surfaces are numbered according to the order in which light from the pupil 500 side reaches them, and the shape type (assigned in the case of aspherical surfaces), radius of curvature, thickness (mm), refractive index (nd), Abbe number (vd), and annotations of each surface are illustrated in this order. Specifically, for example, in the lens data, the surface indicated by surface number s1 indicates the pupil plane 500a (pupil 500). It should be noted that in the lens data, the first optical element 100 is referred to as "optical element 1", the second optical element 110 is referred to as "optical element 2", the first lens group 210 is referred to as "lens group 1", and the second lens group 220 is referred to as "lens group 2". Furthermore, Figure 10 This is a diagram illustrating an example of aspheric coefficient data for the optical system 1 according to this embodiment. The number "SXX" assigned to each surface corresponds to... Figure 8 The surface number in, and Figure 10 K and Am (m = 3, 4, 5, 6, 7, 8, 9, 10) are the values ​​of the coefficients K and Am in the aspherical expression represented by the following expression (5).

[0198] [Mathematical Expression 5]

[0199]

[0200] In expression (5), Zd represents the aspherical depth, Y represents the height, and C represents the curvature.

[0201] Figure 11 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically shows longitudinal aberration, astigmatism and distortion. Figure 12 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically, lateral aberrations are shown.

[0202] like Figure 8 As shown, from the user's pupil 500 side to the display element 502 side, the optical system 1 according to this embodiment sequentially includes a first optical system 10 and a second optical system 20. The first optical system 10 includes: a first reflective surface (semi-transmissive reflective surface) 102, which reflects light emitted from the pupil 500 side towards the pupil 500 side; and a second reflective surface 112, which reflects light reflected towards the pupil 500 side towards the display element 502 side. The first reflective surface 102 has a concave shape and is capable of forming an intermediate image 510 on the pupil 500 side. The pupil 500 side of the first reflective surface 102 is filled with a material having a refractive index greater than 1. Furthermore, the second optical system 20 is placed on the display element 502 side relative to the intermediate imaging plane forming the intermediate image 510, and is configured such that the intermediate imaging plane and the display element surface have a conjugate relationship. The second optical system 20 includes at least three lenses, two of which have different Abbe numbers, and the second optical system 20 as a whole has positive power.

[0203] From the pupil 500 side to the display element 502 side, the first optical system 10 according to this embodiment further includes a first optical element 100 and a second optical element 110 in sequence. The first optical element 100, as a second reflective surface 112, functions to reflect a portion of the light. The second optical element 110 includes a transmissive surface 104 and a semi-transmissive reflective surface 102, having a concave shape, and is positioned relative to the transmissive surface 104 on the display element 502 side as the first reflective surface. Furthermore, the space between the transmissive surface 104 and the semi-transmissive reflective surface 102 is filled with a material having a refractive index greater than 1.4 and less than 2.2. Specifically, the first optical system 10 is configured such that light emitted from the pupil 500 side is transmitted through the first optical element 100, passes through the transmissive surface 104, is reflected by the semi-transmissive reflective surface 102, passes through the transmissive surface 104, is reflected by the first optical element 100, passes through the transmissive surface 104, and passes through the semi-transmissive reflective surface 102. The second optical system 20 is configured to have positive optical power as a whole relative to the light from the first optical system 10. Specifically, all surfaces of the second optical system 20 have a common axis of rotational symmetry. An intermediate image 510 is formed between the semi-transmissive reflective surface 102 of the second optical element 110 and the first optical element 100. Furthermore, in this embodiment, when the focal length of the semi-transmissive reflective surface 102 is represented by fR and the physical length from the surface of the first optical element 100 on the display element 502 side to the surface vertex of the semi-transmissive reflective surface 102 is represented by LR, LR / fR is 1.01, which satisfies the above expression (1).

[0204] Furthermore, from the pupil 500 side to the display element 502 side, the second optical system 20 according to this embodiment sequentially includes a first lens group 210 with negative optical power and a second lens group 220 with positive optical power. In addition, when the optical power of the first lens group 210 is represented by Φ1 and the optical power of the entire second optical system 20 is represented by Φ, Φ1 / Φ is "-0.15", which satisfies the above expression (2).

[0205] Furthermore, according to this embodiment, the first lens group 210 is adjacent to the display element 502 side of the second optical element 110 and has the function of reducing the angle of light rays at the periphery. In addition, when the angle of the principal ray from the second optical element 110 toward the display element 502 side at the outermost position is represented by Ang1 and the angle of the principal ray from the first lens group 210 toward the second lens group 220 at the outermost position is represented by Ang2, Ang1 / Ang2 is "1.74", which satisfies the following expression (3).

[0206] In this embodiment, the angle of the lower ray incident on the second lens group 220 from the edge ray of the light rays incident from the pupil plane 500a at a viewing angle of 60 degrees is represented by Ang3, and the angle of the lower ray incident on the display element 502 from the second lens group 220 is represented by Ang4. Furthermore, the distance on the optical axis 520 between the pupil plane 500a and the surface of the first optical element 100 located closest to the pupil plane 500a is represented by A. Additionally, when the pupil 500 is separated from the first optical element 100 in the direction of the optical axis 520, the viewing angle is 60 degrees, and there is no light vignetting in the second optical system 20, the distance on the optical axis 520 between the pupil plane 500a and the surface of the first optical element 100 located closest to the pupil plane 500a is represented by A'. Furthermore, the exit pupil position of the first optical system 10 at a distance A is represented by P, and the exit pupil position of the first optical system 10 at a distance A' is represented by P'. In this case, in this embodiment, Ang4 / Ang3 is "-0.17" and (A' - A) / (P' - P) is "-0.59", which satisfies the above expression (4).

[0207] The optical system 1 according to this embodiment may further include a third optical element 300, disposed on the display element 502 side relative to the second optical element 110. In this embodiment, both the first optical element 100 and the third optical element 300 may have a parallel plate shape. It should be noted that details (variations) of the first optical element 100 and the third optical element 300 will be described below.

[0208] In addition, optical simulations were performed using light with wavelengths of 460.0000 nm, 550.0000 nm, and 620.0000 nm, and the results were obtained. Figure 11 and 12 The results of the aberrations are shown in the figure. For example... Figure 11 and 12 As shown in this embodiment, it was found that focus variation (aberration) was suppressed over a wide wavelength range, and aberrations were improved. That is, as obtained from optical simulation... Figure 11 and 12 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics.

[0209] In other words, this embodiment includes structures 1, 2, 3, 4, and 5 as described above. Therefore, the optical system 1 according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while maintaining high optical performance and a wide field of view.

[0210] 2.2 Variation

[0211] Next, we will refer to Figure 13 Variations of this embodiment are described. Figure 13 This is an explanatory diagram illustrating a schematic structural example of a variation of this embodiment, and it shows the main parts of this variation.

[0212] In this variant, the first optical element 100 of the first optical system 10 may include a first waveplate 402 that shifts the phase of the vertically polarized component of light by 90 degrees. Additionally, in this variant, the second optical system 20 may include second waveplates 404a and 404b that shift the phase of the vertically polarized component of light by 90 degrees. It is assumed that the slow axes of the first waveplate 402 and the second waveplates 404a and 404b are orthogonal to or parallel to each other. Furthermore, in this variant, a first polarizer 412 may be provided relative to the first waveplate 402 at a position on the pupil 500 side. The first polarizer 412 transmits only linearly polarized light and reflects other polarized light. The first polarizer 412 is capable of limiting the polarized light incident on the first waveplate 402. Relative to the second waveplates 404a and 404b, a second polarizer 414 may be provided relative to the display element 502 side. The second polarizer 414 transmits only linearly polarized light and reflects other polarized light. The second polarizer 414 can limit the polarized light incident on the second waveplate 404b.

[0213] Figure 13 The illustration shows an example of the arrangement of a first waveplate 402, second waveplates 404a and 404b, a first polarizer 412, and a second polarizer 414. For example, optical system 1 may include the first polarizer 412 and the first waveplate 402 as a first optical element 100 of the first optical system 10. Optical system 1 may include, for example, second waveplates 404a and 404b placed as... Figure 8 The third optical element 300 is located on the display element 502 side of the second optical element 110 shown in the figure.

[0214] In this variation, the combination is as follows Figure 13 The structure and optical system 1 shown can achieve higher optical performance.

[0215] 3. Second Embodiment

[0216] Next, we will refer to Figures 14 to 18 An optical system 1 according to a second embodiment of the present disclosure is described. Figure 14 This is a schematic diagram illustrating an example of the structure of the optical system 1 according to this embodiment. Figure 15 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment, and the description is consistent with... Figure 9 The descriptions are the same. Figure 16 This is a diagram illustrating an example of aspheric coefficient data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 10The descriptions are the same. Figure 17 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically shows longitudinal aberration, astigmatism and distortion. Figure 18 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically, lateral aberrations are shown.

[0217] Although detailed descriptions are omitted, the optical system 1 according to this embodiment also includes the structures 1, 2, 3, 4, and 5 described above, similar to the first embodiment. More specifically, in this embodiment, LR / fR is "1.01", which satisfies the above expression (1). In this embodiment, Φ1 / Φ is "-0.21", which satisfies the above expression (2). In this embodiment, Ang1 / Ang2 is "2.01", which satisfies the following expression (3). In this embodiment, Ang4 / Ang3 is "-0.60" and (A' - A) / (P' - P) is "-0.61", which satisfies the above expression (4).

[0218] In addition, optical simulations were performed using light with wavelengths of 460.0000 nm, 550.0000 nm, and 620.0000 nm, and the results were obtained. Figure 17 and 18 The aberration results are shown in the figure. (As obtained from optical simulation.) Figure 17 and 18 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics. Therefore, the optical system 1 according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while having high optical performance and a wide field of view.

[0219] 4. Third embodiment

[0220] Next, we will refer to Figures 19 to 23 An optical system 1 according to a third embodiment of the present disclosure is described. Figure 19 This is a schematic diagram illustrating an example of the structure of the optical system 1 according to this embodiment. Figure 20 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment, and the description is consistent with... Figure 9 The descriptions are the same. Figure 21 This is a diagram illustrating an example of aspheric coefficient data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 10 The descriptions are the same. Figure 22 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically shows longitudinal aberration, astigmatism and distortion. Figure 23 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically, lateral aberrations are shown.

[0221] Although detailed descriptions are omitted, the optical system 1 according to this embodiment also includes the structures 1, 2, 3, 4, and 5 described above, similar to the first embodiment. More specifically, in this embodiment, LR / fR is “0.96”, which satisfies the above expression (1). In this embodiment, Φ1 / Φ is “-0.38”, which satisfies the above expression (2). In this embodiment, Ang1 / Ang2 is “3.24”, which satisfies the following expression (3). In this embodiment, Ang4 / Ang3 is “-1.48” and (A' - A) / (P' - P) is “-0.51”, which satisfies the above expression (4). It should be noted that Ang1 and Ang2 in this embodiment are shown in Figure 19 middle.

[0222] Such as those obtained through optical simulation Figure 22 and 23 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics. Therefore, the optical system 1 according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while having high optical performance and a wide field of view.

[0223] 5. Fourth Embodiment

[0224] Next, we will refer to Figures 24 to 28 An optical system 1 according to a fourth embodiment of the present disclosure is described. Figure 24 This is a schematic diagram illustrating an example of the structure of the optical system 1 according to this embodiment. Figure 25 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment, and the description is consistent with... Figure 9 The descriptions are the same. Figure 26 This is a diagram illustrating an example of aspheric coefficient data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 10 The descriptions are the same. Figure 27 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically shows longitudinal aberration, astigmatism and distortion. Figure 28 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically, lateral aberrations are shown.

[0225] Although detailed descriptions are omitted, the optical system 1 according to this embodiment also includes the structures 1, 2, 3, 4, and 5 described above, similar to the first embodiment. More specifically, in this embodiment, LR / fR is "0.98", which satisfies the above expression (1). In this embodiment, Φ1 / Φ is "-0.29", which satisfies the above expression (2). In this embodiment, Ang1 / Ang2 is "1.86", which satisfies the following expression (3). In this embodiment, Ang4 / Ang3 is "-1.44" and (A' - A) / (P' - P) is "-0.15", which satisfies the above expression (4).

[0226] In addition, optical simulations were performed using light with wavelengths of 460.0000 nm, 550.0000 nm, and 620.0000 nm, and the results were obtained. Figure 27 and 28 The aberration results are shown in the figure. (As obtained from optical simulation.) Figure 27 and 28 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics. Therefore, the optical system 1 according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while having high optical performance and a wide field of view.

[0227] 6. Fifth Embodiment

[0228] 6.1 Structure 6

[0229] Next, we will refer to Figure 29 and 30 The “structure 6” included in the fifth and sixth embodiments is described. Figure 29 These are explanatory diagrams used to explain the overview of this embodiment, and Figure 30 This is a schematic diagram illustrating an example of the structure of an optical system 1 according to a fifth embodiment of the present disclosure.

[0230] In the fifth and sixth embodiments of this disclosure, for example, as Figure 30 As shown, the second optical system 20 includes: a first lens group 210 with positive optical power located on the pupil 500 side; and a second lens group 220 with positive optical power located on the display element 502 side, and having a principal ray of the second optical system 20 intersecting the optical axis 520. When the optical power of the first lens group 210 is represented by Φ1 and the optical power of the entire second optical system 20 is represented by Φ, preferably, the following expression (6) is satisfied. Hereinafter, this structure of the optical system is referred to as "structure 6".

[0231] [Mathematical Expression 6]

[0232]

[0233] like Figure 29 As shown, in order to maintain the magnitude of the light flux diverging with a large numerical aperture (NA) from the intermediate imaging 510 (intermediate imaging plane 510a) on the optical axis 520 while converging the light flux with favorable aberrations, the optical power Φ1 of the first lens group 210 is preferably set to be equal to or greater than the optical power Φ of the entire second optical system 20.

[0234] However, when Φ1 / Φ is less than the lower limit (0.8), the optical power Φ1 of the first lens group 210 is reduced, and the size of the optical system 1 is increased. On the other hand, when Φ1 / Φ exceeds the upper limit (2.0), the amount of spherical aberration in the first lens group 210 increases, and the imaging performance of the optical system 1 decreases. Therefore, in the fifth and sixth embodiments, Φ1 / Φ is preferably set as in the above expression (6).

[0235] As described above, in the fifth and sixth embodiments of this disclosure, structure 6 is preferably provided, and by such operation, an optical system 1 is provided that has high optical performance and a wide field of view, and is capable of reducing the size of HMDs, AR glasses, etc.

[0236] 6.2 Detailed Structure

[0237] Next, we will refer to Figures 30 to 34 An optical system 1 according to a fifth embodiment of the present disclosure is described. Figure 31 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment, and the description is consistent with... Figure 9 The descriptions are the same. Figure 32 This is a diagram illustrating an example of aspheric coefficient data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 10 The descriptions are the same. Figure 33 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically shows longitudinal aberration, astigmatism and distortion. Figure 34 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically, lateral aberrations are shown.

[0238] like Figure 30As shown, from the user's pupil 500 side to the display element 502 side, the optical system 1 according to this embodiment sequentially includes a first optical system 10 and a second optical system 20. The first optical system 10 includes: a first reflective surface (semi-transmissive reflective surface) 102, which reflects light emitted from the pupil 500 side towards the pupil 500 side; and a second reflective surface 112, which reflects light reflected towards the pupil 500 side towards the display element 502 side. The first reflective surface 102 has a concave shape and is capable of forming an intermediate image 510 on the pupil 500 side. The pupil 500 side of the first reflective surface 102 is filled with a material having a refractive index greater than 1. Furthermore, the second optical system 20 is placed on the display element 502 side relative to the intermediate imaging plane forming the intermediate image 510, and is configured such that the intermediate imaging plane and the display element surface have a conjugate relationship. The second optical system 20 includes at least three lenses, two of which have different Abbe numbers, and the second optical system 20 as a whole has positive power.

[0239] From the pupil 500 side to the display element 502 side, the first optical system 10 according to this embodiment further includes a first optical element 100 and a second optical element 110 in sequence. The first optical element 100, as a second reflective surface 112, functions to reflect a portion of the light. The second optical element 110 includes a transmissive surface 104 and a semi-transmissive reflective surface 102, which, as the first reflective surface, is positioned relative to the transmissive surface 104 on the display element 502 side and has a concave shape. Furthermore, the space between the transmissive surface 104 and the semi-transmissive reflective surface 102 is filled with a material having a refractive index greater than 1.4 and less than 2.2. Specifically, the first optical system 10 is configured such that light emitted from the pupil 500 side is transmitted through the first optical element 100, passes through the transmissive surface 104, is reflected by the semi-transmissive reflective surface 102, passes through the transmissive surface 104, is reflected by the first optical element 100, passes through the transmissive surface 104, and passes through the semi-transmissive reflective surface 102. The second optical system 20 is configured to have positive optical power as a whole relative to the light from the first optical system 10. Specifically, all surfaces of the second optical system 20 have a common axis of rotational symmetry. An intermediate image 510 is formed between the semi-transmissive reflective surface 102 of the second optical element 110 and the first optical element 100. Furthermore, in this embodiment, when the focal length of the semi-transmissive reflective surface 102 is represented by fR and the physical length from the surface of the first optical element 100 on the display element 502 side to the surface vertex of the semi-transmissive reflective surface 102 is represented by LR, LR / fR is “0.80”, and the above expression (1) is satisfied.

[0240] Additionally, in this embodiment, as Figure 30As shown, the second optical system 20 includes: a first lens group 210 with positive optical power located on the pupil 500 side; and a second lens group 220 with positive optical power located on the display element 502 side, and having a principal ray of the second optical system 20 intersecting the optical axis 520. When the optical power of the first lens group 210 is represented by Φ1 and the optical power of the entire second optical system 20 is represented by Φ, Φ1 / Φ is “0.96”, which satisfies the above expression (6).

[0241] In addition, such as Figure 30 As shown, the optical system 1 according to this embodiment may include a third optical element 300 placed on the side of the display element 502 relative to the second optical element 110, similar to the first embodiment.

[0242] In addition, optical simulations were performed using light with wavelengths of 460.0000 nm, 550.0000 nm, and 620.0000 nm, and the results were obtained. Figure 32 and 33 The results of the aberrations are shown in the figure. For example... Figure 32 and 33 As shown in this embodiment, it was found that focus variation (aberration) was suppressed over a wide wavelength range, and aberrations were improved. That is, as obtained from optical simulation... Figure 32 and 33 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics.

[0243] In other words, this embodiment includes structures 1, 2, and 6 as described above. Therefore, the optical system 1 according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while maintaining high optical performance and a wide field of view.

[0244] 7. Sixth Embodiment

[0245] 7.1 Detailed Structure

[0246] Next, we will refer to Figures 35 to 39 An optical system 1 according to a sixth embodiment of the present disclosure is described. Figure 35 This is a schematic diagram illustrating an example of the structure of the optical system 1 according to this embodiment. Figure 36 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment, and the description is consistent with... Figure 9 The descriptions are the same. Figure 37 This is a diagram illustrating an example of aspheric coefficient data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 10 The descriptions are the same. Figure 38The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically shows longitudinal aberration, astigmatism and distortion. Figure 39 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically, lateral aberrations are shown.

[0247] Although detailed descriptions are omitted, the optical system 1 according to this embodiment also includes the structures 1, 2, and 6 described above, similar to the fifth embodiment. More specifically, in this embodiment, LR / fR is "0.85", which satisfies the above expression (1). In this embodiment, Φ1 / Φ is "1.84", which satisfies the above expression (6). It should be noted that in this embodiment, as... Figure 35 As shown, the fourth optical element 302 can be placed in the second lens group 220 of the second optical system 20. It should be noted that the fourth optical element 302 will be described in detail below.

[0248] In addition, optical simulations were performed using light with wavelengths of 460.0000 nm, 550.0000 nm, and 620.0000 nm, and the results were obtained. Figure 38 and 39 The aberration results are shown in the figure. (As obtained from optical simulation.) Figure 38 and 39 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics. Therefore, the optical system 1 according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while having high optical performance and a wide field of view.

[0249] 7.2 Variation

[0250] Next, we will refer to the following Figure 40 Variations of this embodiment are described. Figure 40 This is an explanatory diagram illustrating a schematic structural example of an optical system 1 according to a variant of this embodiment, and showing the main parts of the variant.

[0251] In this variant, such as Figure 40 The polarizing element shown, which separates polarized light and has a surface tilted at 45 degrees relative to the optical axis, can be provided as... Figure 35 The fourth optical element 302 is shown in the figure. In this variant, using this structure, a light source 550 can be provided on the back side of the fourth optical element 302. The light source 550 can emit light through the field lens 304. It should be noted that the light source 550 will be described in detail in the eleventh embodiment of this disclosure.

[0252] 8. Seventh Embodiment

[0253] 8.1 Structure 7

[0254] Next, we will refer to Figure 41 and 42 The "structure 7" included in the seventh to ninth embodiments is described. Figure 41 Includes explanatory diagrams for explaining the overview of this embodiment, and Figure 42 This is a schematic diagram illustrating an example of the structure of an optical system 1a according to a seventh embodiment of the present disclosure.

[0255] Element 1

[0256] In the seventh to ninth embodiments of this disclosure, for example, as Figure 42 As shown, from the pupil 500 side to the display element 502 side, the first optical system 10 sequentially includes a first refractive surface 182 and a second refractive surface 184. The first optical system 10 also includes: a first concave reflective surface 172, which, as a first reflective surface, reflects light from the first refractive surface 182 toward the pupil 500 side; and a second concave reflective surface 174, which, as a second reflective surface, reflects light from the first concave reflective surface 172 toward the display element 502 side. The second refractive surface 184 functions to refract light from the second concave reflective surface 174. Furthermore, in these embodiments, the space between the first refractive surface 182 and the second refractive surface 184 is filled with a material having a refractive index greater than 1.4 and less than 2.2. Additionally, in these embodiments, an intermediate image 510 is formed between the first concave reflective surface 172 and the second concave reflective surface 174. The second optical system 20 forms an intermediate image on the display element 502, and light rays at the center of the display element 502 become light rays that are perpendicularly incident on the pupil plane 500a. Hereinafter, this structure of the optical system is referred to as "Element 1 of Structure 7".

[0257] Element 2

[0258] Additionally, in the seventh and ninth embodiments of this disclosure, for example, as... Figure 42 As shown, the second optical system 20 is configured to be rotationally symmetric, and the pupil plane 500a and the display element surface 502a are arranged in parallel. Furthermore, the length of the ray having the longest optical path from the pupil plane 500a to the first concave reflective surface 172 in a direction perpendicular to the pupil plane 500a is represented by L1. Additionally, when the length from the pupil plane 500a to the center of the surface of the second optical system 20 on the pupil 500 side in a direction perpendicular to the pupil plane 500a is represented by L2, the following expression (7) is preferably satisfied. Hereinafter, this structure of the optical system is referred to as "element 2 of structure 7".

[0259] [Mathematical Expression 7]

[0260]

[0261] With the light guide 350, the optical system 1 according to the first to sixth embodiments and the optical system 1a according to the seventh to ninth embodiments of this disclosure can be used, such as Figure 41 As shown on the right. Specifically, as Figure 41 As shown on the right, the light guide 350 is indicated by the frame 352 and is worn on the user's head to be positioned in front of the user's pupil 500, and is capable of guiding the image projected by the display element 502 to the pupil 500. For example, as Figure 41 As shown in the upper right portion, the optical system 1 according to the first to sixth embodiments is positioned along the frame 352 between the display element 502 and the light guide 350. Additionally, for example, as... Figure 41 As shown in the lower right portion, the optical system 1a according to the seventh to ninth embodiments is placed along the frame 352 between the display element 502 and the light guide 350. The light guide 350 enables light from the first optical system 10 and the second optical system 20 of the optical systems 1 and 1a to be imaged on the pupil 500.

[0262] Light traveling in the light guide 350 is repeatedly reflected inside the light guide 350 (on its inner wall) and guided to the pupil 500. As the number of reflections increases, the brightness of the light decreases. Therefore, to avoid this decrease in brightness, it is preferable to shorten the length of the light guide 350.

[0263] For example, such as Figure 41 As shown in the upper right portion, when the optical system 1 according to the first to sixth embodiments is placed along the frame 352, the length of the light guide 350 is increased, and the degrees of freedom in designing the frame 352 are reduced. Therefore, for example, as... Figure 41 As shown in the lower right portion, when the optical system 1a according to the seventh to ninth embodiments is placed along the frame 352, the length of the light guide 350 is shortened, and the degree of freedom in designing the frame 352 is increased. The light guide 350 and the frame 352 are typically placed to intersect each other perpendicularly. Therefore, preferably, the pupil plane 500a of the optical system 1a that guides light to the light guide 350 and the display element surface 502a are arranged in parallel. Therefore, in order to reduce the size of the optical system 1a while reducing the length of the light guide 350 under the constraint of this arrangement, more preferably, L1 / L2 satisfies the above expression (7), as shown above. Figure 41 As shown on the left.

[0264] When in Figure 41 In the left-hand diagram, when the second optical system 20 moves to the right, causing L1 / L2 to be less than the lower limit (0.8), the optical system 1 becomes larger. On the other hand, when in Figure 41In the left-hand diagram, when the second optical system 20 moves to the left and L1 / L2 exceeds the upper limit (1.25), the second optical system 20 interferes with the first optical system 10. Therefore, in the seventh and ninth embodiments, L1 / L2 is preferably set as in the above expression (7).

[0265] As described above, in the seventh to ninth embodiments of this disclosure, element 1 of structure 7 is preferably included, and element 2 of structure 7 is more preferably included. By operating in this way, according to these embodiments, an optical system 1a can be provided, which has high optical performance and a wide field of view, and can achieve a reduction in size for HMDs, AR glasses, etc.

[0266] 8.2 Detailed Structure

[0267] Next, we will refer to Figures 42 to 45 An optical system 1a according to a seventh embodiment of the present disclosure is described. Figure 43 This is a diagram illustrating an example of lens data for the optical system 1a according to this embodiment. Specifically, the surfaces are numbered according to the order in which light from the pupil 500 side reaches them, and the shape type (assigned in the case of aspherical surfaces, free surfaces, etc.), radius of curvature, thickness (mm), refractive index (nd), Abbe number (vd), and annotations of each surface are illustrated in this order. Specifically, for example, in the lens data, the surface indicated by surface number s1 indicates the pupil plane 500a (pupil 500). Figure 44 This is a diagram illustrating examples of aspherical coefficient data and freeform surface data of the optical system 1 according to this embodiment, and the number "SXX" assigned to each surface corresponds to... Figure 43 The surface number in [the document / reference]. Figure 44 In this context, K, Am, and ARm (m = 3, 4, 5, 6, 7, 8, 9, 10) are the values ​​of the coefficients K and Am(ARm) in the aspherical expression represented by the above expression (5). Figure 44 In this context, XnYm is the coefficient (coefficient of the xy polynomial) indicated by Cj in the freeform surface expression represented by the expression (8) below. In addition, XDE, YDE and ZDE are eccentric data and indicate the amount of movement in the X, Y and Z directions, respectively.

[0268] [Mathematical Expression 8]

[0269]

[0270] In expression (8), Z represents the sag parallel to the central axis, c represents the curvature at the vertex of the surface, k represents the conic constant, and h represents the distance relative to the origin in a plane that intersects the origin perpendicularly to the central axis.

[0271] Figure 45 The diagram includes aberration data of the optical system 1a according to this embodiment, and specifically, lateral aberrations are shown.

[0272] like Figure 42 As shown, from the user's pupil 500 side to the display element 502 side, the optical system 1a according to this embodiment sequentially includes a first optical system 10 and a second optical system 20. The first optical system 10 includes: a first reflective surface that reflects light emitted from the pupil 500 side toward the pupil 500 side; and a second reflective surface that reflects light reflected toward the pupil 500 side toward the display element 502 side. The first reflective surface has a concave shape and is capable of forming an intermediate image 510 on the pupil 500 side. The pupil 500 side of the first reflective surface is filled with a material having a refractive index greater than 1. Furthermore, the second optical system 20 is placed on the display element 502 side relative to the intermediate imaging plane forming the intermediate image 510, and is configured such that the intermediate imaging plane and the display element surface have a conjugate relationship. The second optical system 20 includes at least three lenses, two of which have different Abbe numbers, and the second optical system 20 as a whole has positive power.

[0273] In this embodiment, as Figure 42 As shown, from the pupil 500 side to the display element 502 side, the first optical system 10 sequentially includes a first refractive surface 182 and a second refractive surface 184. Additionally, the first optical system 10 further includes: a first concave reflective surface 172, which, as a first reflective surface, reflects light from the first refractive surface 182 toward the pupil 500 side; and a second concave reflective surface 174, which, as a second reflective surface, reflects light from the first concave reflective surface 172 toward the display element 502 side. The second refractive surface 184 functions to refract light from the second concave reflective surface 174. In this embodiment, the space between the first refractive surface 182 and the second refractive surface 184 is filled with a material having a refractive index greater than 1.4 and less than 2.2. Furthermore, in these embodiments, an intermediate image 510 is formed between the first concave reflective surface 172 and the second concave reflective surface 174. The second optical system 20 forms an intermediate image on the display element 502, and light rays at the center of the display element 502 become light rays that are perpendicularly incident on the pupil plane 500a.

[0274] Additionally, in this embodiment, as Figure 42As shown, the second optical system 20 is configured to be rotationally symmetric, and the pupil plane 500a and the display element surface 502a are arranged in parallel. Furthermore, the length of the ray having the longest optical path from the pupil plane 500a to the first concave reflective surface 172 in a direction perpendicular to the pupil plane 500a is represented by L1. Additionally, when the length from the pupil plane 500a to the center of the surface of the second optical system 20 on the pupil 500 side in a direction perpendicular to the pupil plane 500a is represented by L2, L1 / L2 is "0.90", which satisfies the above expression (7).

[0275] In addition, optical simulations were performed using light with wavelengths of 460.0000 nm, 550.0000 nm, and 620.0000 nm, and the results were obtained. Figure 45 The results of the aberrations are shown in the figure. For example... Figure 45 As shown in this embodiment, it was found that focus variation (aberration) was suppressed over a wide wavelength range, and aberrations were improved. That is, as obtained from optical simulation... Figure 45 As can be seen from the aberrations shown, it should be understood that the optical system 1a according to this embodiment has high optical characteristics.

[0276] In other words, this embodiment includes elements 1 and 2 of structures 1 and 7 described above. Therefore, the optical system 1a according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while having high optical performance and a wide field of view.

[0277] 9. Eighth Embodiment

[0278] Next, we will refer to Figures 46 to 49 An optical system 1a according to an eighth embodiment of the present disclosure is described. Figure 46 This is a schematic diagram illustrating an example of the structure of the optical system 1a according to this embodiment. Figure 47 This is a diagram illustrating an example of lens data for the optical system 1a according to this embodiment, and the description is consistent with... Figure 43 The descriptions are the same. Figure 48 This is a diagram illustrating examples of aspherical coefficient data and freeform surface data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 44 The descriptions are identical. Additionally, Figure 49 The diagram includes aberration data of the optical system 1a according to this embodiment, and specifically, lateral aberrations are shown.

[0279] Although detailed descriptions are omitted, in the optical system 1a according to this embodiment, from the pupil 500 side to the display element 502 side, the first optical system 10 sequentially includes a first refractive surface 182 and a second refractive surface 184. Additionally, the first optical system 10 further includes: a first concave reflective surface 172, which, as a first reflective surface, reflects light from the first refractive surface 182 toward the pupil 500 side; and a second concave reflective surface 174, which, as a second reflective surface, reflects light from the first concave reflective surface 172 toward the display element 502 side. The second refractive surface 184 functions to refract light from the second concave reflective surface 174. In this embodiment, the space between the first refractive surface 182 and the second refractive surface 184 is filled with a material having a refractive index greater than 1.4 and less than 2.2. Furthermore, in this embodiment, an intermediate imaging 510 is formed between the first concave reflective surface 172 and the second concave reflective surface 174. The second optical system 20 forms an intermediate image on the display element 502, and the light rays at the center of the display element 502 become light rays that are perpendicularly incident on the pupil plane 500a. Therefore, the optical system 1a according to this embodiment includes element 1 of the above-described structures 1 and 7.

[0280] In addition, optical simulations were performed using light with wavelengths of 460.0000 nm, 550.0000 nm, and 620.0000 nm, and the results were obtained. Figure 49 The aberration results are shown in the figure. (As obtained from optical simulation.) Figure 49 As can be seen from the aberrations shown, it should be understood that the optical system 1a according to this embodiment has high optical characteristics. Therefore, the optical system 1a according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while having high optical performance and a wide field of view.

[0281] 10. Ninth Embodiment

[0282] Next, we will refer to Figures 50 to 53 The optical system 1a according to the ninth embodiment of the present disclosure is described. Figure 50 This is a schematic diagram illustrating an example of the structure of the optical system 1a according to this embodiment. Figure 51 This is a diagram illustrating an example of lens data for the optical system 1a according to this embodiment, and the description is consistent with... Figure 43 The descriptions are the same. Figure 52 This is a diagram illustrating examples of aspherical coefficient data and freeform surface data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 44 The descriptions are identical. Additionally, Figure 53 The diagram includes aberration data of the optical system 1a according to this embodiment, and specifically, lateral aberrations are shown.

[0283] Although detailed descriptions are omitted, the optical system 1a according to this embodiment includes elements 1 and 2 of structures 1 and 7 described above. Specifically, in this embodiment, L1 / L2 is “0.80”, which satisfies the above expression (7), and therefore, structure 7 is included.

[0284] In addition, optical simulations were performed using light with wavelengths of 460.0000 nm, 550.0000 nm, and 620.0000 nm, and the results were obtained. Figure 53 The aberration results are shown in the figure. (As obtained from optical simulation.) Figure 53 As can be seen from the aberrations shown, it should be understood that the optical system 1a according to this embodiment has high optical characteristics. Therefore, the optical system 1a according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while having high optical performance and a wide field of view.

[0285] 11. Tenth Embodiment

[0286] Next, we will refer to Figures 54 to 58 An optical system 1 according to the tenth embodiment of this disclosure is described. Figure 54 This is a schematic diagram illustrating an example of the structure of the optical system 1 according to this embodiment. Figure 55 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment, and the description is consistent with... Figure 9 The descriptions are the same. Figure 56 This is a diagram illustrating an example of aspheric coefficient data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 10 The descriptions are the same. Figure 57 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically shows longitudinal aberration, astigmatism and distortion. Figure 58 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically, lateral aberrations are shown.

[0287] Although detailed descriptions are omitted, the optical system 1 according to this embodiment includes structures 1, 2, and 5 as described above. More specifically, in this embodiment, LR / fR is 0.86, which satisfies expression (1) above. In this embodiment, Ang4 / Ang3 is "1.00" and (A' - A) / (P' - P) is "-0.78", which satisfies expression (4) above.

[0288] In addition, optical simulations were performed using light with wavelengths of 460.0000 nm, 550.0000 nm, and 620.0000 nm, and the results were obtained. Figure 57 and 58The aberration results are shown in the figure. (As obtained from optical simulation.) Figure 57 and 58 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics. Therefore, the optical system 1 according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while having high optical performance and a wide field of view.

[0289] 12. Eleventh Embodiment

[0290] 12.1 Detailed Structure of the Optical System

[0291] The eleventh embodiment of this disclosure has the function of tracking the movement of a user's pupil and adjusting the optical system 1 according to the position of the pupil so that an image from the display element 502 is properly formed on the pupil (eye tracking).

[0292] First, refer to Figures 59 to 65 An optical system 1 according to the eleventh embodiment of the present disclosure is described. Figure 59 This includes a diagram illustrating a schematic structural example of the optical system 1 according to this embodiment. Specifically, the upper part shows the state when the user points their line of sight in the optical axis direction (Wide). The lower part shows the state when the user points their line of sight in an upward tilt direction (Tele). Figure 60 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment, and the description is consistent with... Figure 9 The descriptions are the same. Figure 61 This is a diagram illustrating an example of aspheric coefficient data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 10 The descriptions are the same. Figure 62 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically illustrates longitudinal aberrations, astigmatism, and distortion in the wide direction. Figure 63 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically illustrates longitudinal aberrations, astigmatism, and distortion in Tele. Figure 64 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically illustrates lateral aberrations in the wide area. Figure 65 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically illustrates the lateral aberration in Tele.

[0293] Although detailed descriptions are omitted, the optical system 1 according to this embodiment includes structures 1, 2, 4, and 5 as described above. More specifically, in this embodiment, LR / fR is "0.77", which satisfies expression (1) above. In this embodiment, Φ1 / Φ is "-0.15", which satisfies expression (2) above. In this embodiment, Ang1 / Ang2 is "1.74", which satisfies expression (3) below. In this embodiment, Ang4 / Ang3 is "0.01" and (A' - A) / (P' - P) is "-0.41", which satisfies expression (4) above.

[0294] In addition, optical simulations were performed using light with wavelengths of 460.0000 nm, 550.0000 nm, and 620.0000 nm, and the results were obtained. Figures 62 to 65 The aberration results are shown in the figure. (As obtained from optical simulation.) Figures 62 to 65 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics. Therefore, the optical system 1 according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while having high optical performance and a wide field of view.

[0295] 12.2 Eye-tracking mechanism

[0296] Next, we will refer to Figure 59 and 66 Sections 68 describe structural examples of the eye-tracking mechanism according to this embodiment. Figure 66 and 68 This includes illustrations showing an example of the arrangement of the light source and camera according to this embodiment, and... Figure 67 This includes illustrations showing an example of imaging using a camera according to this embodiment.

[0297] like Figure 66As shown, optical systems 1 and 1a according to this embodiment include: a camera (imaging optical system) 560, which serves as a detection unit for capturing the movement of a user's pupil, arranged on the display element 502 side of the first reflective surface 102 and positioned without overlapping with the second optical system 20, and capable of detecting infrared light having a wavelength from, for example, 400 nm to 700 nm. Additionally, optical systems 1 and 1a according to this embodiment include: a light source 550, arranged on the display element 502 side of the first reflective surface 102 and positioned without overlapping with the second optical system 20 and the camera 560, and illuminating the user's pupil with infrared light having a wavelength from, for example, 400 nm to 700 nm. For example, the light source 550 may be configured as a light-emitting diode (LED). To achieve this structure, in optical system 1, for infrared light having a wavelength from 400 nm to 700 nm, the semi-transmissive reflective surface 102 of the second optical element 110 is preferably used as a transmissive surface. Alternatively, in optical system 1a, preferably, for infrared light having wavelengths from 400 nm to 700 nm, the first concave reflective surface 172 is used as a transmission surface.

[0298] like Figure 67 As shown, in this embodiment, the detection unit detects the movement of the user's pupil as the amount of radial movement of the center of the reference eyeball. Specifically, Figure 67 The upper part shows a state where the pupil is facing forward, and the center of the pupil overlaps with the center of the eyeball. Additionally, the state where the pupil has moved is shown. Figure 67 In the lower part of the eye, and using the center of the eyeball as a reference, the detection unit detects the amount of pupil movement in the radial direction. Additionally, in this embodiment, a control unit (not shown) is provided, which changes the overall optical power of the second optical system 20 based on the detected amount of movement. In this way, in this embodiment, the optical system 1 can be adjusted according to the position of the pupil, so that the image from the display element 502 is appropriately formed on the pupil (eye tracking).

[0299] Specifically, such as Figure 59 As shown, by moving at least two lens groups 210 and 220 included in the second optical system 20 along the optical axis 520, the control unit is able to change the optical power of the entire second optical system 20. At this time, in this embodiment, the distance between the first optical element 100 and the display element 502 remains unchanged, and therefore, the size of the entire optical system 1 (its length in the direction of the optical axis 520) remains unchanged.

[0300] It should be noted that, in this embodiment, the control unit is not limited to changing the optical power of the entire second optical system 20 by moving at least two lens groups 210 and 220 included in the second optical system 20 along the optical axis 520. In this embodiment, for example, at least two liquid lenses may be provided in the second optical system 20, and the control unit may change the optical power of the entire second optical system 20 by applying a voltage to the liquid lenses to change the curvature of the liquid lenses.

[0301] Additionally, in this embodiment, one or more cameras 560 and one or more light sources 550 may be provided. In this case, as... Figure 68 As shown, preferably, the plurality of cameras 560 are positioned symmetrically with respect to the central axis of the first reflective surface 102. Additionally, preferably, the plurality of light sources 550 are also positioned symmetrically with respect to the central axis of the first reflective surface 102. By positioning the cameras 560 and light sources 550 in this manner, blind spots are eliminated, and therefore, the movement of the user's pupils can be tracked with high accuracy.

[0302] As described above, in this embodiment, even taking into account the rotation of the pupil 500, high optical performance and a wide field of view can be maintained. Furthermore, since the optical system 1 itself can be made compact, the display device (such as an HMD, AR glasses, etc.) can also be reduced in size.

[0303] 13. Twelfth Embodiment

[0304] In many embodiments of the present disclosure described above, the pupil plane 500a and the display element surface 502a face each other, and the optical system 1 according to the embodiments of the present disclosure guides light to travel along a predetermined optical path between the pupil plane 500a and the display element surface 502a.

[0305] However, since HMDs and AR glasses are worn on the user's head, it is strongly desired that they be smaller. Therefore, by reviewing the positional relationship between the pupil plane 500a and the display element surface 502a, the inventors have envisioned further reducing the size of HMDs and AR glasses. Specifically, in this embodiment, the display element 502 is provided above the user's pupil 500 using a total internal reflection surface in the optical system 1. By doing so, the optical system 1 can be reduced in size, and therefore, the size of HMDs, AR glasses, etc., can be reduced. Based on this idea, the inventors have then created an optical system 1 according to the twelfth embodiment of this disclosure, which uses a total internal reflection surface.

[0306] The following will refer to Figure 69 An optical system 1 according to the twelfth embodiment of the present disclosure is described. Figure 69These are explanatory diagrams used to explain the overview of this embodiment.

[0307] like Figure 69 As shown, in this embodiment, a display element 502 is provided above the user's pupil 500. From the pupil plane 500a side to the display element 502 side, the optical system 1 according to this embodiment sequentially includes a first optical system 10 and a second optical system 20. The first optical system 10 includes a second optical element 110 and a first optical element 100. The second optical element 110 includes: a first reflective surface (semi-transmissive reflective surface) 102, which reflects light emitted from the pupil 500 side toward the pupil 500 side; and a transmissive surface (first transmissive surface) 104. In addition, the first optical element 100 includes: a second reflective surface, which reflects light reflected toward the pupil 500 side toward the opposite side of the pupil 500 (towards the display element 502 side). In addition, similar to the embodiments of this disclosure described above, in this embodiment, the second reflective surface also has the function of reflecting a portion of the light. Furthermore, in this embodiment, the first reflective surface (semi-transmissive reflective surface) 102 is positioned on the opposite side of the pupil 500 (display element 502 side) relative to the transmissive surface (first transmissive surface) 104, has a concave shape, and is capable of forming an intermediate image on the pupil 500 side. Additionally, in this embodiment, the pupil 500 side of the first reflective surface (semi-transmissive reflective surface) 102 is also filled with a material having a refractive index greater than 1. Specifically, in this embodiment, preferably, the space between the transmissive surface (first transmissive surface) 104 and the first reflective surface (semi-transmissive reflective surface) 102 is also filled with a material having a refractive index greater than 1.4 and less than 2.2.

[0308] In this embodiment, when the focal length of the first reflective surface (semi-transmissive reflective surface) 102 is represented by fR and the physical length from the surface of the first optical element 100 on the opposite side of the pupil 500 (the display element 502 side) to the surface vertex of the first reflective surface (semi-transmissive reflective surface) 102 is represented by LR, the following expression (1a) is preferably satisfied.

[0309] [Mathematical Expression 9]

[0310]

[0311] In this embodiment, the first optical system 10 is configured such that light emitted from the pupil 500 side is transmitted through the first optical element 100, transmitted through the transmission surface (first transmission surface) 104 of the second optical element 110, reflected by the first reflective surface (semi-transmittance reflective surface) 102 of the second optical element 110, transmitted through the transmission surface (first transmission surface) 104 of the second optical element 110, reflected by the first optical element 100 on the pupil 500 side or the display element 502 side, transmitted through the transmission surface (first transmission surface) 104 of the second optical element 110, and transmitted through the first reflective surface (semi-transmittance reflective surface) 102 of the second optical element 20.

[0312] Furthermore, the second optical system 20 is positioned on the display element 502 side (in optical path) relative to the intermediate imaging plane forming the intermediate image, and is configured such that the intermediate imaging plane and the display element surface 502a have a conjugate relationship, as in the embodiments described above. In this embodiment, the second optical system 20 includes at least two surfaces with positive optical power and one surface with negative optical power, and the second optical system 20 as a whole has positive optical power.

[0313] Additionally, in this embodiment, as Figure 69 As shown, the second optical system 20 is an optical system having positive optical power as a whole relative to the light flux from the first optical system 10, and has a fifth optical element 450 filled with a material having a refractive index greater than 1.4 and less than 2.2. In this embodiment, the second optical system 20 also includes a third lens group 460, which includes at least three lenses.

[0314] In this embodiment, from the pupil plane 500a side to the display element 502 side, the fifth optical element 450 sequentially has a transmissive surface (second transmissive surface) 702, a third reflective surface 711, and a fourth reflective surface 712. Furthermore, in this embodiment, the fifth optical element 450 is configured such that light emitted from the first optical system 10 side is transmitted through the transmissive surface (second transmissive surface) 702, reflected by the third reflective surface 711, totally reflected by a surface identical to the transmissive surface (second transmissive surface) 702 (total internal reflection surface 700), reflected by the fourth reflective surface 712, and transmitted through a surface identical to the transmissive surface (second transmissive surface) 702 (transmissive surface 703). In this embodiment, light transmitted through the transmissive surface 703 is focused by the third lens group 460 and imaged.

[0315] In addition, in this embodiment, the third reflective surface 711 can be, for example, the surface of a diffraction element.

[0316] In this embodiment, by using the total internal reflection surface 700 of the fifth optical element 450, the optical system 1 can be further reduced in size. Specifically, in order to reduce the size of the optical system 1, the depth D and width W of the optical system must be reduced, such as... Figure 69 As shown in the figure. In this embodiment, the third reflective surface 711 is preferably configured to satisfy the following expression (9), wherein the angle of the third reflective surface 711 relative to the fifth optical element 450 of the pupil plane 500a is represented by Ang5, the pupil plane 500a is set to 0°, the clockwise direction is defined as a negative angle, and the counterclockwise direction is defined as a positive angle.

[0317] [Mathematical Expression 10]

[0318]

[0319] When the angle Ang5 of the third reflecting surface 711 of the fifth optical element 450 relative to the pupil plane 500a exceeds the upper limit of expression (9), light cannot be totally reflected by the total reflection surface 700. When the angle Ang5 is less than the lower limit of expression (9), the depth D of the optical system 1 increases, and the optical system 1 may increase in size. Therefore, in this embodiment, expression (9) is preferably satisfied.

[0320] In addition, in this embodiment, the fourth reflective surface 712 is preferably configured to satisfy the following expression (10), wherein the angle of the fourth reflective surface 712 relative to the fifth optical element 450 of the pupil plane 500a is represented by Ang6, the pupil plane 500a is set to 0°, the clockwise direction is defined as a negative angle, and the counterclockwise direction is defined as a positive angle.

[0321] [Mathematical Expression 11]

[0322]

[0323] Furthermore, in this embodiment, the transmission surface (second transmission surface) 702, the total internal reflection surface 700, and the transmission surface 703 of the fifth optical element 450 are formed as a single surface, such as... Figure 69 As shown in the figure. In addition, in this embodiment, when the angle of the total reflection surface 700 (the total reflection surface 700 is the same surface as the transmission surface (second transmission surface) 702 of the fifth optical element 450, which performs total reflection of light) relative to the direction A of light traveling perpendicularly from the pupil plane 500a is represented by Ang7, the transmission surface (second transmission surface) 702, the total reflection surface 700 and the transmission surface 703, which are the same surface, are preferably configured to satisfy the following expression (11).

[0324] [Mathematical Expression 12]

[0325]

[0326] In this way, in this embodiment, the depth D and width W of the optical system 1 can be further reduced.

[0327] Furthermore, in this embodiment, the fifth optical element 450 is preferably configured to satisfy the following expression (12), where Ang9 is the angle of ray B relative to the direction A of light traveling perpendicularly from the pupil plane 500a when ray B enters the transmission surface (second transmission surface) 702. Figure 69 The dashed line indicates that the light enters the transmission surface (second transmission surface) 702, is reflected by the third reflection surface 711, and is totally reflected by the total reflection surface 700.

[0328] [Mathematical Expression 13]

[0329]

[0330] In this embodiment, the smaller the angle Ang9, the smaller the aforementioned angles Ang5 and Ang6 can be, and therefore, the smaller the depth D of the optical system 1 can be. Specifically, when the angle Ang9 of the ray B that enters the transmission surface (second transmission surface) 702 relative to the direction A of the light traveling perpendicularly from the pupil plane 500a exceeds the upper limit of expression (12), the angle Ang5 increases, and the depth D of the optical system 1 increases. When the angle Ang9 is less than the lower limit of expression (12), the light incident on the transmission surface (second transmission surface) 702 travels to the fourth reflection surface 712, and therefore, the fifth optical element 450 needs to be extended in the vertical direction in this figure, resulting in an increase in the width D of the optical system 1. Therefore, in this embodiment, expression (12) is preferably satisfied.

[0331] Next, Figures 70 to 74 The illustration shows a specific example of the optical system 1 according to this embodiment. Figure 70 This is a schematic diagram illustrating an example of the structure of the optical system 1 according to this embodiment. Figure 71 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment, and the description is consistent with... Figure 9 The descriptions are the same, but in the lens data, the fifth optical element 450 is referred to as "optical element 3" and the third lens group 460 is referred to as "lens group 1". Figure 72 This is a diagram illustrating an example of aspheric coefficient data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 10 The descriptions are the same. Figure 73The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically shows longitudinal aberration, astigmatism and distortion. Figure 74 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically, lateral aberrations are shown.

[0332] In addition, optical simulations were performed using light with wavelengths of 450.0000 nm, 522.0000 nm, and 630.0000 nm, and the results were obtained. Figure 73 and 74 The aberration results are shown in the figure. (As obtained from optical simulation.) Figure 73 and 74 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics. Therefore, the optical system 1 according to this embodiment can achieve a reduction in the size of HMDs, AR glasses, etc., while having high optical performance and a wide field of view.

[0333] 14. Thirteenth Embodiment

[0334] The thirteenth to fifteenth embodiments described below are embodiments that enable further size reduction of HMDs and AR glasses by re-examining the positional relationship between the pupil plane 500a and the display element surface 502a, similar to the twelfth embodiment described above. Specifically, in these embodiments, the display element 502 is also provided above the user's pupil 500 using a total internal reflection surface via the optical system 1. According to these embodiments, by doing so, the optical system 1 can be reduced in size, and therefore, HMDs, AR glasses, etc., can be reduced in size. Therefore, specific examples of the thirteenth to fifteenth embodiments will be shown in the following order, followed by a description of the structure of these embodiments.

[0335] First, refer to Figures 75 to 78 A specific example of an optical system 1 according to the thirteenth embodiment of this disclosure is described. Figure 75 This is a schematic diagram illustrating an example of the structure of the optical system 1 according to this embodiment. Figure 76 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment, and the description is consistent with... Figure 9 The descriptions are the same. Figure 77 This is a diagram illustrating an example of aspheric coefficient data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 10 The descriptions are the same. Figure 78 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically, lateral aberrations are shown.

[0336] like Figure 75As shown, in this embodiment, a display element 502 (display element surface 502a) is provided above the user's pupil 500 (pupil plane 500a). In this embodiment, from the user's pupil 500 side to the display element 502 side, the optical system 1 sequentially includes a first optical system 10 and a second optical system 20. The first optical system 10 includes: a first reflective surface 142 that reflects light emitted from the pupil 500 side toward the pupil plane 500a side; and a second reflective surface 143 that reflects light reflected toward the pupil 500 side toward the opposite side of the pupil plane 500a (towards the display element surface 502a side). The first reflective surface 142 has a concave shape and is capable of forming an intermediate image 510 on the pupil plane 500a side. The pupil 500 side of the first reflective surface 142 is filled with a material having a refractive index greater than 1.

[0337] In this embodiment, the second optical system 20 is configured such that it is placed on the display element surface 502a side relative to the intermediate imaging plane forming the intermediate image 510, and the intermediate imaging plane and the display element surface 502a have a conjugate relationship. In this embodiment, the second optical system 20 includes at least two surfaces with positive optical power and one surface with negative optical power, and the second optical system 20 as a whole has positive optical power.

[0338] Specifically, in this embodiment, as follows: Figure 75 As shown, from the pupil plane 500a side to the display element surface 502a side, the first optical system 10 sequentially includes a third refractive surface 131 and a fourth refractive surface 133. The first optical system 10 also includes: a third concave reflective surface 142, serving as a first reflective surface, reflecting light from the third refractive surface 131 towards the pupil plane 500a side; and a fourth concave reflective surface 143, serving as a second reflective surface, reflecting light from the third concave reflective surface 142 towards the display element surface 502a side. Furthermore, in this embodiment, the fourth refractive surface 133 is capable of refracting light from the fourth concave reflective surface 143. Additionally, in this embodiment, preferably, the space between the third refractive surface 131 and the fourth refractive surface 133 is filled with a material having a refractive index greater than 1.4 and less than 2.2. Furthermore, in this embodiment, an intermediate image 510 is formed between the third concave reflective surface 142 and the fourth concave reflective surface 143.

[0339] In addition, in this embodiment, the second optical system 20 forms an intermediate image 510 on the surface 502a of the display element, and the light rays at the center of the display element 502 are light rays that are perpendicularly incident on the pupil plane 500a.

[0340] More specifically, in this embodiment, as Figure 75As shown, starting from the pupil plane 500a side, the first optical system 10 includes: a third refractive surface 131 having a concave shape; and a first reflective surface 142, which is a concave reflective surface. Additionally, the first optical system 10 includes: a second reflective surface 143, which is the same surface as the third refractive surface 131 and has a convex shape relative to the light reflected by the first reflective surface 142; and a fourth refractive surface 133, on which the light reflected by the second reflective surface 143 is incident. Furthermore, in this embodiment, the luminous flux incident on the third refractive surface 131 from among the set of light rays incident on the second reflective surface 143 satisfies the total internal reflection condition represented by the following expression (13) relative to the third refractive surface 131. In this embodiment, the luminous flux incident on a region different from the third refractive surface 131 from among the set of light rays incident on the second reflective surface 143 does not satisfy the total internal reflection condition represented by the following expression (13) relative to the region different from the third refractive surface 131. In addition, in this embodiment, the intermediate imaging position of the reference ray 522 is located inside the first optical system 10.

[0341] [Mathematical Expression 14]

[0342]

[0343] In expression (13), θ is the angle of incidence and n is the refractive index.

[0344] In this embodiment, the second optical system 20 includes four refractive surfaces 231, 233, 234, and 236, a fifth reflective surface 242, and a reflective surface 245. In this embodiment, the light reflected by the fifth reflective surface 242 of the second optical system 20 forms an image on the display element surface 502a.

[0345] In this embodiment, optical simulations were performed using light with wavelengths of 450.0000 nm, 525.0000 nm, and 630.0000 nm, and the results were obtained. Figure 78 The aberration results are shown in the figure. (As obtained from optical simulation.) Figure 78 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics. Therefore, the optical system 1 according to this embodiment has high optical performance.

[0346] 15. Fourteenth Embodiment

[0347] Next, we will refer to Figures 79 to 82 A specific example of an optical system 1 according to the fourteenth embodiment of this disclosure is described. Figure 79 This is a schematic diagram illustrating an example of the structure of the optical system 1 according to this embodiment. Figure 80 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment, and the description is consistent with... Figure 9 The descriptions are the same. Figure 81 This is a diagram illustrating an example of aspheric coefficient data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 10 The descriptions are the same. Figure 82 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically, lateral aberrations are shown.

[0348] In this embodiment, as Figure 79 As shown, the optical system 1 has the same structure as the thirteenth embodiment described above. Furthermore, in this embodiment, the optical system 1 includes a lens 230 located between the fourth refractive surface 133 of the first optical system 10 and the refractive surface 231 of the second optical system 20. Additionally, in this embodiment, the optical system 1 includes a lens 240 located between the refractive surface 233 and the refractive surface 234 of the second optical system 20.

[0349] In this embodiment, optical simulations were performed using light with wavelengths of 450.0000 nm, 525.0000 nm, and 630.0000 nm, and the results were obtained. Figure 82 The aberration results are shown in the figure. (As obtained from optical simulation.) Figure 82 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics. Therefore, the optical system 1 according to this embodiment has high optical performance.

[0350] 16. Fifteenth Embodiment

[0351] Next, we will refer to Figures 83 to 86 A specific example of an optical system 1 according to the fifteenth embodiment of this disclosure is described. Figure 83 This is a schematic diagram illustrating an example of the structure of the optical system 1 according to this embodiment. Figure 84 This is a diagram illustrating an example of lens data for the optical system 1 according to this embodiment, and the description is consistent with... Figure 9 The descriptions are the same. Figure 85 This is a diagram illustrating an example of aspheric coefficient data of the optical system 1 according to this embodiment, and the description is consistent with... Figure 10 The descriptions are the same. Figure 86 The diagram includes aberration data of the optical system 1 according to this embodiment, and specifically, lateral aberrations are shown.

[0352] In this embodiment, as Figure 83As shown, the optical system 1 has a first optical system 10, which has the same structure as the thirteenth embodiment described above. Furthermore, in this embodiment, the optical system 1 has a second optical system 20, which has a structure different from that of the thirteenth embodiment described above.

[0353] In this embodiment, the second optical system 20 includes two refractive surfaces 231 and 233 and a fifth reflective surface 242. In this embodiment, light reflected by the fifth reflective surface 242 of the second optical system 20 is transmitted through the refractive surface 233 and imaged on the display element surface 502a by the fourth lens group 470.

[0354] In this embodiment, optical simulations were performed using light with wavelengths of 450.0000 nm, 525.0000 nm, and 630.0000 nm, and the results were obtained. Figure 86 The aberration results are shown in the figure. (As obtained from optical simulation.) Figure 86 As can be seen from the aberrations shown, it should be understood that the optical system 1 according to this embodiment has high optical characteristics. Therefore, the optical system 1 according to this embodiment has high optical performance.

[0355] As described above, in the thirteenth to fifteenth embodiments of this disclosure, a display element 502 (display element surface 502a) is provided above the user's pupil 500 (pupil plane 500a). In these embodiments, from the user's pupil 500 side to the display element 502 side, the optical system 1 sequentially includes a first optical system 10 and a second optical system 20. The first optical system 10 includes: a first reflective surface 142 that reflects light emitted from the pupil 500 side toward the pupil plane 500a side; and a second reflective surface 143 that reflects light reflected toward the pupil 500 side toward the opposite side of the pupil plane 500a (towards the display element surface 502a side). The first reflective surface 142 has a concave shape and is capable of forming an intermediate image 510 on the pupil plane 500a side. The pupil 500 side of the first reflective surface 142 is filled with a material having a refractive index greater than 1.

[0356] In addition, in these embodiments, the second optical system 20 is configured such that it is placed on the display element surface 502a side relative to the intermediate imaging plane forming the intermediate image 510, and the intermediate imaging plane and the display element surface 502a have a conjugate relationship. The second optical system 20 includes at least two surfaces with positive optical power and one surface with negative optical power, and the second optical system 20 as a whole has positive optical power.

[0357] Specifically, in these embodiments, such as Figure 75 , 79As shown in Figure 83, from the pupil plane 500a side to the display element surface 502a side, the first optical system 10 sequentially includes a third refractive surface 131 and a fourth refractive surface 133. The first optical system 10 further includes: a third concave reflective surface 142, serving as a first reflective surface, reflecting light from the third refractive surface 131 towards the pupil plane 500a side; and a fourth concave reflective surface 143, serving as a second reflective surface, reflecting light from the third concave reflective surface 142 towards the display element surface 502a side. Furthermore, in these embodiments, the fourth refractive surface 133 can refract light from the fourth concave reflective surface 143. Additionally, in these embodiments, preferably, the space between the third refractive surface 131 and the fourth refractive surface 133 is filled with a material having a refractive index greater than 1.4 and less than 2.2. Furthermore, in these embodiments, an intermediate image 510 is formed between the third concave reflective surface 142 and the fourth concave reflective surface 143.

[0358] In addition, in these embodiments, the second optical system 20 forms an intermediate image 510 on the surface 502a of the display element, and the light rays at the center of the display element 502 are light rays that are perpendicularly incident on the pupil plane 500a.

[0359] More specifically, in these embodiments, such as Figure 75 , 79 As shown in Figure 83, starting from the pupil plane 500a side, the first optical system 10 includes: a third refractive surface 131 having a concave shape; and a first reflective surface 142, which is a concave reflective surface. Additionally, the first optical system 10 includes: a second reflective surface 143, which is the same surface as the third refractive surface 131 and has a convex shape relative to the light reflected by the first reflective surface 142; and a fourth refractive surface 133, on which the light reflected by the second reflective surface 143 is incident. Furthermore, in these embodiments, the luminous flux incident on the third refractive surface 131 from among the set of light rays incident on the second reflective surface 143 satisfies the total internal reflection condition expressed by the above expression (13) relative to the third refractive surface 131. Furthermore, in these embodiments, the luminous flux incident on a region different from the third refractive surface 131 from among the set of light rays incident on the second reflective surface 143 does not satisfy the total internal reflection condition expressed by the above expression (13) relative to the region different from the third refractive surface 131. In addition, in these embodiments, the intermediate imaging position of the reference ray 522 is located inside the first optical system 10.

[0360] Additionally, in these embodiments, the second optical system 20 includes at least two refractive surfaces 231, 233, 234, and 236; and at least one reflective surface, including a fifth reflective surface 242. In these embodiments, light reflected by the fifth reflective surface 242 of the second optical system 20 images onto the display element surface 502a.

[0361] In addition, in these embodiments, when the direction of the light emitted from the pupil plane 500a is the Z direction and the direction perpendicular to the Z direction is the Y direction, the focal length of the first optical system 10 in the Y cross section is represented by fy1 and the optical path length from the third refractive surface 131 to the fourth refractive surface 133 is represented by OP1, the system is preferably configured such that the following expression (14) is satisfied.

[0362] [Mathematical Expression 15]

[0363]

[0364] When fy1 / OP1 is less than the lower limit of the above expression (14), the optical path length through the first optical system 10 becomes longer, and therefore, the first optical system 10 becomes larger. Conversely, when fy1 / OP1 exceeds the upper limit of the above expression (14), since the focal plane is placed in the second optical system 20, the entire optical system 1 is focused, and the entire optical system 1 is increased in size. Therefore, in these embodiments, expression (14) is preferably satisfied.

[0365] In addition, in these embodiments, when the focal length of the Y-section of the first reflecting surface 142 reflecting the reference ray is represented by fr1y and the focal length of the entire optical system 1 in the Y-section is represented by fy, the following expression (15) is preferably satisfied.

[0366] [Mathematical Expression 16]

[0367]

[0368] When fy / fr1y is below the lower limit of the above expression (15), the optical power of the first reflecting surface 142 increases, and aberrations occur. When fy / fr1y exceeds the upper limit of the above expression (15), the optical power of the first reflecting surface 142 is reduced, and the intermediate imaging plane cannot be formed in the first optical system 10, thereby increasing the size of the first optical system 10. Therefore, in these embodiments, expression (15) is preferably satisfied.

[0369] In addition, in these embodiments, the following expression (16) is preferably satisfied.

[0370] [Mathematical Expression 17]

[0371]

[0372] When fy1 / fr1y is below the lower limit of the above expression (16), the optical power of the first reflecting surface 142 increases, and aberrations occur. Conversely, when fy1 / fr1y exceeds the upper limit of the above expression (16), the optical power of the first reflecting surface 142 decreases, and the intermediate imaging plane cannot be formed in the first optical system 10, thus increasing the size of the first optical system 10. Therefore, in these embodiments, expression (16) is preferably satisfied.

[0373] Additionally, in these embodiments, preferably, the following expression (17) is satisfied, where fray is the focal length of the Y-section relative to the first reflective surface 142 of the predetermined ray 522a, which has the maximum angle of incidence relative to the third refractive surface 131 and passes through the region where the third refractive surface 131 and the first reflective surface 142 of the first optical system 10 are physically close to each other, and fray is the composite focal length of the Y-section when the predetermined ray 522a passes through the third refractive surface 131 and the first reflective surface 142.

[0374] [Mathematical Expression 18]

[0375]

[0376] When fay / fra1y is lower than the lower limit of the above expression (17), the optical power of the first reflecting surface 142 reflecting the predetermined ray 522a is small. Therefore, the angle of the ray 522a incident on the pupil plane 500a becomes larger, and the total internal reflection condition is not satisfied on the second reflecting surface 143, which is on the same surface as the third refractive surface 131. When fay / fra1y exceeds the upper limit of the above expression (17), the optical power of the first reflecting surface 142 reflecting the predetermined ray 522a becomes larger, and therefore, aberrations occur. In addition, since the third refractive surface 131 and the first reflecting surface 142 physically interfere with each other, the predetermined ray 522a cannot enter the second reflecting surface 143. Therefore, in these embodiments, expression (17) is preferably satisfied.

[0377] In addition, in these embodiments, preferably, the following expression (18) is satisfied.

[0378] [Mathematical Expression 19]

[0379]

[0380] When fra1y / fr1y is lower than the lower limit of the above expression (18), the optical power of the first reflecting surface 142 reflecting the predetermined ray 522a increases, and therefore, aberrations occur. Furthermore, since the third refractive surface 131 and the first reflecting surface 142 physically interfere with each other, the predetermined ray 522a cannot enter the second reflecting surface 143. Additionally, when fra1y / fr1y exceeds the upper limit of the above expression (18), the optical power of the first reflecting surface 142 reflecting the predetermined ray 522a is lower. Therefore, the angle of the ray 522a incident on the pupil plane 500a increases, and the total internal reflection condition is not satisfied on the second reflecting surface 143, which is on the same surface as the third refractive surface 131. Therefore, in these embodiments, expression (18) is preferably satisfied.

[0381] In addition, in these embodiments, when the focal length of the Y-section of the fifth reflecting surface 242 is represented by fr3y and the focal length of the entire optical system 1 in the Y-section is represented by fy, the following expression (19) is preferably satisfied.

[0382] [Mathematical Expression 20]

[0383]

[0384] When fy / fr3y is below the lower limit of the above expression (19), the divergence of the luminous flux from the fifth reflecting surface 242 increases, and the size of the entire optical system 1 increases. When fy / fr3y exceeds the upper limit of the above expression (19), the convergence capability increases, and aberrations occur. Therefore, in these embodiments, expression (19) is preferably satisfied.

[0385] The values ​​of fy1 / OP1, fy / fr1y, fy1 / fr1y, fay / fra1y, fra1y / fr1y, and fy / fr3y in embodiments thirteen to fifteen are shown in Figure 87 middle, Figure 87 This is a diagram illustrating data examples of an optical system 1 according to embodiments thirteen through fifteen of this disclosure.

[0386] As described above, the optical system 1 according to the thirteenth to fifteenth embodiments of this disclosure can reduce the size of HMDs, AR glasses, etc. while having high optical performance and a wide field of view.

[0387] 17. Summary Statement

[0388] As described above, in each embodiment of the present disclosure, optical systems 1 and 1a may be provided, having high optical performance and a wide field of view (e.g., field of view (FOV) = 80 to 120 degrees), and enabling size reduction of HMDs, AR glasses, etc.

[0389] It should be noted that, in the embodiments of this disclosure, optical systems 1 and 1a are not limited to the modes illustrated in the accompanying drawings, and various modifications can be made.

[0390] It should be noted that the optical systems 1 and 1a described above according to the embodiments of this disclosure are not limited to being applied to projection-type HMD or AR glasses, but can also be applied to light-emitting devices (such as small projectors), imaging devices (such as wide-angle stereoscopic 3D cameras), etc.

[0391] 18. Application Examples

[0392] For example, the technology according to this disclosure can be applied to the display portion of various electronic devices. Therefore, examples of electronic devices to which this technology can be applied will be described below.

[0393] Figure 88 This is an external view of the head-mounted display 600. On either side of the eyeglass-shaped display portion 611, the head-mounted display 600 includes, for example, ear loop portions 612 for wearing on a user's head. In the head-mounted display 600, the optical system 1 according to an embodiment of this disclosure can be used as the optical system of the display portion 611.

[0394] 19. Supplement

[0395] While preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the scope of the present disclosure is not limited to such examples. It will be apparent to those skilled in the art that various variations or modifications will arise within the scope of the technical concept described in the claims, and it should be understood that these also naturally fall within the scope of the present disclosure.

[0396] Furthermore, the effects described in this specification are merely illustrative or exemplary and are not limited thereto. That is, in conjunction with or in lieu of the effects described above, the technology according to this disclosure can exhibit other effects that are clear to those skilled in the art from the description herein.

[0397] This technology can be implemented using the structure described below.

[0398] (1) An optical system comprising, sequentially from the user's pupil side to the display element side, a first optical system and a second optical system, wherein the first optical system comprises:

[0399] The first reflecting surface reflects light emitted from the pupil side toward the pupil side; and

[0400] The second reflective surface reflects light reflected towards the pupil from the display element side.

[0401] The first reflecting surface has a concave shape and forms an intermediate image on the pupil side.

[0402] The pupil side of the first reflecting surface is filled with a material having a refractive index greater than 1.

[0403] The second optical system is positioned on the display element side relative to the intermediate imaging plane that forms the intermediate image, and is configured such that the intermediate imaging plane and the surface of the display element have a conjugate relationship.

[0404] The second optical system includes at least three lenses, two of which have different Abbe numbers, and the second optical system as a whole has positive power.

[0405] (2) The optical system as described in (1), wherein the first optical system comprises, from the pupil side to the display element side, a first optical element and a second optical element in sequence.

[0406] The first optical element, acting as the second reflective surface, functions to reflect a portion of the light.

[0407] The second optical element includes:

[0408] Transmitting surface; and

[0409] A semi-transmissive reflective surface, serving as the first reflective surface, is positioned relative to the transmissive surface on the display element side and has a concave shape.

[0410] The space between the transmissive surface and the semi-transmissive reflective surface is filled with a material having a refractive index greater than 1.4 and less than 2.2.

[0411] All surfaces of the second optical system share a common axis of rotational symmetry.

[0412] Intermediate imaging is formed between the semi-transparent reflective surface of the second optical element and the first optical element, and

[0413] When the focal length of the semitransparent reflective surface is represented by fR and the physical length from the surface of the first optical element on the display element side to the vertex of the semitransparent reflective surface is represented by LR, the following expression (1) is satisfied.

[0414] [Mathematical Expression 21]

[0415] .

[0416] (3) The optical system as described in (2), wherein the second optical system comprises, from the pupil side to the display element side, the following in sequence:

[0417] The first lens group has negative optical power; and

[0418] The second lens group has positive optical power.

[0419] When the optical power of the first lens group is represented by Φ1 and the optical power of the entire second optical system is represented by Φ, the following expression (2) is satisfied.

[0420] [Mathematical Expression 22]

[0421] .

[0422] (4) The optical system as described in (3), wherein the first lens group and the second optical element are adjacent on the display element side and have the function of reducing the angle of light rays in the periphery, and

[0423] When the angle of the principal ray from the second optical element toward the outermost position of the display element is represented by Ang1 and the angle of the principal ray from the first lens group toward the outermost position of the second lens group is represented by Ang2, the following expression (3) is satisfied.

[0424] [Mathematical Expression 23]

[0425] .

[0426] (5) The optical system as described in (4), wherein the angle of the lower ray incident on the second lens group from the edge ray of the light rays incident from the pupil plane at a viewing angle of 60 degrees is denoted by Ang3, and the angle of the lower ray incident on the display element from the second lens group is denoted by Ang4.

[0427] The distance along the optical axis between the pupil plane and the surface of the first optical element located closest to the pupil plane is denoted by A.

[0428] When the pupil is separated from the first optical element along the optical axis, the viewing angle is 60 degrees, and there is no vignetting in the second optical system, the distance along the optical axis between the pupil plane and the surface of the first optical element located closest to the pupil plane is denoted by A'.

[0429] The position of the exit pupil of the first optical system at a distance A is denoted by P, and

[0430] The position of the exit pupil of the first optical system at a distance A' is denoted by P'.

[0431] Then the following expression (4) is satisfied.

[0432] [Mathematical Expression 24]

[0433] .

[0434] (6) The optical system as described in (2), wherein the second optical system comprises:

[0435] The first lens group, having positive optical power, is located on the pupil side; and

[0436] The second lens group, having positive optical power, is located on the display element side. The principal ray of the second optical system intersects the optical axis.

[0437] When the optical power of the first lens group is represented by Φ1 and the optical power of the entire second optical system is represented by Φ, the following expression (6) is satisfied.

[0438] [Mathematical Expression 25]

[0439] .

[0440] (7) The optical system as described in (1), wherein the first optical system comprises:

[0441] A first refractive surface and a second refractive surface are arranged sequentially from the pupil side to the display element side;

[0442] A first concave reflective surface, serving as a first reflective surface, reflects light from the first refractive surface toward the pupil side; and

[0443] The second concave reflective surface, as a second reflective surface, reflects light from the first concave reflective surface toward the display element side.

[0444] The second refractive surface refracts light from the second concave reflective surface.

[0445] The space between the first and second refracting surfaces is filled with a material having a refractive index greater than 1.4 and less than 2.2.

[0446] The intermediate image is formed between the first concave reflective surface and the second concave reflective surface.

[0447] The second optical system forms an intermediate image on the display element, and

[0448] The light rays at the center of the display element are incident perpendicularly on the pupil plane.

[0449] (8) The optical system as described in (7), wherein the second optical system is configured to be rotationally symmetric.

[0450] The pupil plane and the display element surface are arranged in parallel, and

[0451] When the length of the ray with the longest optical path from the pupil plane to the first concave reflecting surface in the direction perpendicular to the pupil plane from the pupil plane to the first concave reflecting surface is represented by L1, and

[0452] The length from the pupil plane to the center of the pupil-side surface of the second optical system in a direction perpendicular to the pupil plane is represented by L2.

[0453] Then the following expression (7) is satisfied.

[0454] [Mathematical Expression 26]

[0455] .

[0456] (9) An optical system as described in any one of (2) to (6), wherein the first optical element comprises a first waveplate that shifts the phase of the vertical polarization component of the light by 90 degrees.

[0457] The second optical system includes a third optical element, which includes a second waveplate that shifts the phase of the vertical polarization component of the light by 90 degrees.

[0458] The slow axes of the first and second wave plates are orthogonal or parallel to each other.

[0459] (10) The optical system as described in (9) further includes: a first polarizer for transmitting linearly polarized light, located on the pupil side relative to the first waveplate.

[0460] (11) The optical system as described in (9) further includes:

[0461] The second polarizer for transmitting linearly polarized light is located on the display element side relative to the second waveplate.

[0462] (12) The optical system as described in (9), wherein the first optical element and the third optical element have a parallel plate shape.

[0463] (13) The optical system as described in (9), wherein the third optical element is placed on the display element side relative to the second optical element.

[0464] (14) The optical system as described in (9), wherein the second optical system further includes a fourth optical element that separates polarized light and has a surface tilted at 45 degrees relative to the optical axis.

[0465] (15) The optical system as described in any one of (1) to (14) further includes:

[0466] A light guide, worn by the user and positioned in front of the pupil, guides the image projected by the display element to the pupil.

[0467] The first and second optical systems are placed between the display element and the light guide, and

[0468] The light guide causes light from the first and second optical systems to be imaged on the pupil.

[0469] (16) An optical system as described in any of (2) to (6), wherein a semi-transmissive reflective surface is used as a transmissive surface for light having a wavelength from 400 nm to 700 nm.

[0470] (17) An optical system as described in (7) or (8), wherein for light having wavelengths from 400 nm to 700 nm, a first concave reflective surface is used as a transmission surface.

[0471] (18) The optical system as described in (16) further includes:

[0472] An imaging optical system, which acts as a detection unit to capture the movement of the user's pupil, is positioned on the display element side of the first reflective surface and does not overlap with the second optical system, and detects infrared light.

[0473] (19) The optical system as described in (18) includes:

[0474] The plurality of imaging optical systems, including a first imaging optical system and a second imaging optical system,

[0475] The first imaging optical system and the second imaging optical system are placed symmetrically relative to the central axis of the first reflective surface.

[0476] (20) The optical system as described in (18) further includes:

[0477] The light source is arranged on the display element side of the first reflective surface and in a position that does not overlap with the second optical system and the imaging optical system, and emits infrared light.

[0478] (21) The optical system as described in (20) includes:

[0479] The plurality of light sources, including a first light source and a second light source,

[0480] The first light source and the second light source are placed symmetrically with respect to the central axis of the first reflective surface.

[0481] (22) An optical system as described in (20) or (21), wherein the light source includes an LED.

[0482] (23) The optical system as described in any one of (18) to (22) further includes: a control unit for changing the optical power of the entire second optical system.

[0483] The detection unit detects the movement of the user's pupil as the radial movement relative to the center of the eyeball, and

[0484] The control unit adjusts the optical power of the entire second optical system based on the detected amount of movement.

[0485] (24) The optical system as described in (23), wherein the control unit changes the optical power of the entire second optical system by moving at least two lens groups included in the second optical system along the optical axis.

[0486] (25) The optical system as described in (23), wherein the second optical system comprises at least two liquid lenses, and

[0487] The control unit changes the optical power of the entire second optical system by applying voltage to the liquid lens.

[0488] (26) The optical system as described in (24) or (25), wherein when the control unit changes the optical power of the entire second optical system,

[0489] The distance between the first optical element and the display element remains constant.

[0490] (27) An optical system as described in any of (18) to (26), wherein the detection unit detects light having a wavelength from 400 nm to 700 nm that has passed through the first optical system.

[0491] (28) A display device, starting from the pupil side, includes a first optical system, a second optical system, and a display element, wherein the first optical system includes:

[0492] The first reflecting surface reflects light emitted from the pupil side toward the pupil side; and

[0493] The second reflective surface reflects light reflected towards the pupil from the display element side.

[0494] The first reflecting surface has a concave shape and forms an intermediate image on the pupil side.

[0495] The pupil side of the first reflecting surface is filled with a material having a refractive index greater than 1.

[0496] The second optical system is positioned on the display element side relative to the intermediate imaging plane that forms the intermediate image, and is configured such that the intermediate imaging plane and the surface of the display element have a conjugate relationship.

[0497] The second optical system includes at least three lenses, two of which have different Abbe numbers, and the second optical system as a whole has positive power.

[0498] (29) An optical system comprising, sequentially from the user's pupil side to the display element side, a first optical system and a second optical system, wherein the first optical system comprises:

[0499] The first reflecting surface reflects light emitted from the pupil side toward the pupil side; and

[0500] The second reflective surface reflects light reflected towards the pupil from the display element side.

[0501] The first reflecting surface has a concave shape and forms an intermediate image on the pupil side.

[0502] The pupil side of the first reflecting surface is filled with a material having a refractive index greater than 1.

[0503] The second optical system is positioned on the display element side relative to the intermediate imaging plane that forms the intermediate image, and is configured such that the intermediate imaging plane and the surface of the display element have a conjugate relationship.

[0504] The second optical system includes at least two surfaces with positive optical power and one surface with negative optical power, and

[0505] The second optical system as a whole has positive optical power.

[0506] (30) The optical system as described in (29), wherein the first optical system comprises, from the pupil side to the display element side, a first optical element and a second optical element in sequence.

[0507] The first optical element, acting as the second reflective surface, functions to reflect a portion of the light.

[0508] The second optical element includes:

[0509] First transmission surface; and

[0510] A semi-transmissive reflective surface, serving as the first reflective surface, is positioned relative to the first transmissive surface on the display element side and has a concave shape.

[0511] The space between the first transmissive surface and the semi-transmissive reflective surface is filled with a material having a refractive index greater than 1.4 and less than 2.2.

[0512] Intermediate imaging is formed between the semi-transparent reflective surface of the second optical element and the first optical element, and

[0513] When the focal length of the semi-transparent reflective surface is represented by fR and the physical length from the surface of the first optical element on the display element side to the vertex of the semi-transparent reflective surface is represented by LR, the following expression (1a) is satisfied.

[0514] [Mathematical Expression 27]

[0515] .

[0516] (31) The optical system as described in (29), wherein the first optical system comprises:

[0517] The third and fourth refractive surfaces are arranged sequentially from the pupil side to the display element side.

[0518] The third concave reflective surface, acting as the first reflective surface, reflects light from the third refractive surface toward the pupil side; and

[0519] The fourth concave reflective surface, acting as the second reflective surface, reflects light from the third concave reflective surface toward the display element side.

[0520] The fourth refractive surface refracts light from the fourth concave reflective surface.

[0521] The space between the third and fourth refractive surfaces is filled with a material having a refractive index greater than 1.4 and less than 2.2.

[0522] The intermediate image is formed between the third concave reflective surface and the fourth concave reflective surface.

[0523] The second optical system forms an intermediate image on the display element, and

[0524] The light rays at the center of the display element are incident perpendicularly on the pupil plane.

[0525] (32) The optical system as described in (29), wherein the first optical system comprises, from the pupil side to the display element side, a first optical element and a second optical element in sequence.

[0526] The first optical element, acting as the second reflective surface, functions to reflect a portion of the light.

[0527] The second optical element includes:

[0528] First transmission surface; and

[0529] A semi-transmissive reflective surface, serving as the first reflective surface, is positioned relative to the first transmissive surface on the display element side and has a concave shape.

[0530] The space between the first transmissive surface and the semi-transmissive reflective surface is filled with a material having a refractive index greater than 1.4 and less than 2.2.

[0531] The second optical system is an optical system that has positive optical power for the light flux from the first optical system as a whole, and includes a fifth optical element filled with a material having a refractive index greater than 1.4 and less than 2.2.

[0532] The fifth optical element, from the pupil side to the display element side, includes a second transmissive surface and a third reflective surface, respectively.

[0533] The first optical system is configured such that light emitted from the pupil side is transmitted through the first optical element, transmitted through the first transmissive surface of the second optical element, reflected by the semi-transmissive reflective surface of the second optical element, transmitted through the first transmissive surface of the second optical element, reflected at the pupil side or display element side of the first optical element, transmitted through the first transmissive surface of the second optical element, and transmitted through the semi-transmissive reflective surface of the second optical element.

[0534] The fifth optical element is configured such that light emitted from the first optical system side is transmitted through the second transmission surface, reflected by the third reflection surface, and totally reflected by the same surface as the second transmission surface.

[0535] (33) In the optical system described in (32), the following expression (9) is satisfied when the angle between the third reflecting surface of the fifth optical element and the pupil plane is represented by Ang5, the pupil plane is 0° and the clockwise direction is negative.

[0536] [Mathematical Expression 28]

[0537] .

[0538] (34) The optical system as described in (32), wherein the third reflecting surface is the surface of the diffractive element.

[0539] (35) The optical system as described in (33), wherein the second optical system further includes a third lens group comprising at least three lenses.

[0540] The fifth optical element also includes a fourth reflective surface.

[0541] The fifth optical element is configured such that light emitted from the first optical system side is transmitted through the second transmission surface, reflected by the third reflection surface, totally internally reflected by a surface identical to the second transmission surface, reflected by the fourth reflection surface, and transmitted through a surface identical to the second transmission surface.

[0542] Light transmitted through the same surface as the second transmission surface is focused by the third lens group and imaged.

[0543] (36) In the optical system described in (35), the following expression (10) is satisfied when the angle between the fourth reflecting surface of the fifth optical element and the pupil plane is represented by Ang6, the pupil plane is 0° and the clockwise direction is negative.

[0544] [Mathematical Expression 29]

[0545] .

[0546] (37) The optical system as described in (35), wherein when the angle between the surface of the fifth optical element, which is the same as the second transmission surface, which performs total internal reflection of light, and the direction of light traveling perpendicularly from the pupil plane is represented by Ang7, the following expression (11) is satisfied.

[0547] [Mathematical Expression 30]

[0548] .

[0549] (38) The optical system as described in (29), wherein the first optical system includes, from the pupil side, a third refractive surface, a first reflective surface, a second reflective surface, and a fourth refractive surface, the third refractive surface having a concave shape, the first reflective surface being a concave reflective surface, the second reflective surface being the same surface as the third refractive surface and having a convex shape relative to the light reflected by the first reflective surface, and the light reflected by the second reflective surface being incident on the fourth refractive surface.

[0550] In a set of rays incident on the second reflecting surface, the luminous flux incident on the third refractive surface satisfies the total internal reflection condition relative to the third refractive surface, as expressed by the following expression (13).

[0551] The luminous flux incident on the second reflecting surface onto a region different from the third refractive surface does not satisfy the total internal reflection condition expressed by the following expression (13) relative to the region different from the third refractive surface.

[0552] The intermediate imaging position of the reference ray is located inside the first optical system.

[0553] The second optical system includes at least two refractive surfaces and at least one reflective surface, wherein the at least one reflective surface includes a fifth reflective surface, and

[0554] The light reflected by the fifth reflective surface of the second optical system forms an image on the surface of the display element.

[0555] [Mathematical Expression 31]

[0556]

[0557] In expression (13), θ is the angle of incidence and n is the refractive index.

[0558] (39) The optical system as described in (38), wherein when the direction of the light emitted from the pupil plane is the Z direction, the direction perpendicular to the Z direction is the Y direction, the focal length of the first optical system in the Y cross section is represented by fy1, and the optical path length from the third refractive surface to the fourth refractive surface is represented by OP1, the following expression (14) is satisfied.

[0559] [Mathematical Expression 32]

[0560] .

[0561] (40) The optical system as described in (38), wherein the following expression (15) is satisfied when the focal length of the Y-section of the first reflecting surface reflecting the reference ray is represented by fr1y and the focal length of the entire optical system in the Y-section is represented by fy.

[0562] [Mathematical Expression 33]

[0563] .

[0564] (41) The optical system as described in (40), wherein when the focal length of the first optical system in the Y cross section is represented by fy1, the following expression (16) is satisfied.

[0565] [Mathematical Expression 34]

[0566] .

[0567] (42) In the optical system described in (38), where the focal length of the first reflecting surface relative to the Y-section of the predetermined ray is denoted by fray, the predetermined ray has the maximum angle of incidence relative to the third refractive surface and passes through the region where the third refractive surface and the first reflecting surface of the first optical system are physically close to each other, and the combined focal length of the Y-section of the predetermined ray when passing through the third refractive surface and the first reflecting surface is denoted by fay, then the following expression (17) is satisfied.

[0568] [Mathematical Expression 35]

[0569] .

[0570] (43) The optical system as described in (42), wherein when the focal length of the Y-section of the first reflecting surface reflecting the reference ray is represented by fr1y, the following expression (18) is satisfied.

[0571] [Mathematical Expression 36]

[0572] .

[0573] (44) The optical system as described in (38), wherein the following expression (19) is satisfied when the focal length of the Y-section of the fifth reflecting surface is represented by fr3y and the focal length of the entire optical system in the Y-section is represented by fy.

[0574] [Mathematical Expression 37]

[0575] .

[0576] (45) A display device, starting from the pupil side, includes a first optical system, a second optical system, and a display element, wherein the first optical system includes:

[0577] The first reflecting surface reflects light emitted from the pupil side toward the pupil side; and

[0578] The second reflective surface reflects light reflected towards the pupil from the display element side.

[0579] The first reflecting surface has a concave shape and forms an intermediate image on the pupil side.

[0580] The pupil side of the first reflecting surface is filled with a material having a refractive index greater than 1.

[0581] The second optical system is positioned on the display element side relative to the intermediate imaging plane that forms the intermediate image, and is configured such that the intermediate imaging plane and the surface of the display element have a conjugate relationship.

[0582] The second optical system includes at least two surfaces with positive optical power and one surface with negative optical power, and

[0583] The second optical system as a whole has positive optical power.

[0584] List of labels

[0585] 1.1a Optical System

[0586] 10 First Optical System

[0587] 20 Second Optical System

[0588] 100 First Optical Element

[0589] 102 First reflecting surface

[0590] 104, 702, 703 Transmitting Surfaces

[0591] 110 Second optical element

[0592] 112 Second reflective surface

[0593] 131 Third Refractive Surface

[0594] 133 Fourth refractive surface

[0595] 142 Third concave reflective surface

[0596] 143 Fourth concave reflective surface

[0597] 172 First concave reflective surface

[0598] 174 Second concave reflective surface

[0599] 182 First Refractive Surface

[0600] 184 Second Refractive Surface

[0601] 210 First Lens Group

[0602] 220 Second Lens Group

[0603] 230 and 240 lenses

[0604] Refracting surfaces 231, 233, 234, 236

[0605] 242 Fifth reflecting surface

[0606] 245 Reflective Surface

[0607] 300 Third optical element

[0608] 302 Fourth optical element

[0609] 304 field lens

[0610] 350 optical waveguide

[0611] 352 Frame

[0612] 402 First Wave Film

[0613] 404a, 404b Second Wave Film

[0614] 412 First Polarizer

[0615] 414 Second Polarizer

[0616] 450 Fifth optical element

[0617] 460 Third Lens Group

[0618] 470 Fourth Lens Group

[0619] 500 pupils

[0620] 500a Pupil Plane

[0621] 502 Display Component

[0622] 502a Display element surface

[0623] 510 Intermediate Imaging

[0624] 510a Intermediate Imaging Plane

[0625] 520 optical axis

[0626] 522 reference ray

[0627] 522a Light Ray

[0628] 550 light source

[0629] 560 camera

[0630] 600 Head-Mounted Display

[0631] 611 Display Section

[0632] 612 Ear hook part

[0633] 700 Total Internal Reflection Surface

[0634] 711 Third Reflecting Surface

[0635] 712 Fourth reflective surface.

Claims

1. An optical system comprising, sequentially from the user's pupil side to the display element side, a first optical system and a second optical system, wherein the first optical system comprises: The first reflective surface reflects light emitted from the pupil side towards the pupil side. The second reflective surface reflects light reflected towards the pupil from the display element side. The first reflecting surface has a concave shape and forms an intermediate image on the pupil side. The pupil side of the first reflecting surface is filled with a material having a refractive index greater than 1. The second optical system is positioned on the display element side relative to the intermediate imaging plane that forms the intermediate image, and is configured such that the intermediate imaging plane and the surface of the display element have a conjugate relationship. The second optical system includes at least three lenses, two of which have different Abbe numbers, and the second optical system as a whole has positive power.

2. The optical system of claim 1, wherein the first optical system comprises, from the pupil side to the display element side, a first optical element and a second optical element in sequence. The first optical element, acting as the second reflective surface, functions to reflect a portion of the light. The second optical element includes: Transmitting surface; and A semi-transmissive reflective surface, serving as the first reflective surface, is positioned relative to the transmissive surface on the display element side and has a concave shape. The space between the transmissive surface and the semi-transmissive reflective surface is filled with a material having a refractive index greater than 1.4 and less than 2.

2. All surfaces of the second optical system share a common axis of rotational symmetry. Intermediate imaging is formed between the semi-transparent reflective surface of the second optical element and the first optical element, and When the focal length of the semitransparent reflective surface is represented by fR and the physical length from the surface of the first optical element on the display element side to the vertex of the semitransparent reflective surface is represented by LR, the following expression (1) is satisfied. [Mathematical Expression 1] 。 3. The optical system of claim 2, wherein the second optical system comprises, from the pupil side to the display element side, the following components in sequence: The first lens group has negative optical power; and The second lens group has positive optical power. When the optical power of the first lens group is represented by Φ1 and the optical power of the entire second optical system is represented by Φ, the following expression (2) is satisfied. [Mathematical Expression 2] 。 4. The optical system of claim 3, wherein the first lens group and the second optical element are adjacent on the display element side and have the function of reducing the angle of light rays at the periphery, and When the angle of the principal ray from the second optical element toward the outermost position of the display element is represented by Ang1 and the angle of the principal ray from the first lens group toward the outermost position of the second lens group is represented by Ang2, the following expression (3) is satisfied. [Mathematical Expression 3] 。 5. The optical system of claim 4, wherein when the angle of the lower ray incident on the second lens group from the edge ray of the light rays incident from the pupil plane at a viewing angle of 60 degrees is represented by Ang3 and the angle of the lower ray incident on the display element from the second lens group is represented by Ang4, The distance along the optical axis between the pupil plane and the surface of the first optical element located closest to the pupil plane is denoted by A. When the pupil is separated from the first optical element along the optical axis, the viewing angle is 60 degrees, and there is no vignetting in the second optical system, the distance along the optical axis between the pupil plane and the surface of the first optical element located closest to the pupil plane is denoted by A'. The position of the exit pupil of the first optical system at a distance A is denoted by P, and The position of the exit pupil of the first optical system at a distance A' is denoted by P'. Then the following expression (4) is satisfied. [Mathematical Expression 4] 。 6. The optical system of claim 2, wherein the second optical system comprises: The first lens group, having positive optical power, is located on the pupil side; and The second lens group, having positive optical power, is located on the display element side. The principal ray of the second optical system intersects the optical axis. When the optical power of the first lens group is represented by Φ1 and the optical power of the entire second optical system is represented by Φ, the following expression (6) is satisfied. [Mathematical Expression 5] 。 7. The optical system of claim 1, wherein the first optical system comprises: A first refractive surface and a second refractive surface are arranged sequentially from the pupil side to the display element side; A first concave reflective surface, serving as the first reflective surface, reflects light from the first refractive surface toward the pupil side; as well as The second concave reflective surface, as a second reflective surface, reflects light from the first concave reflective surface toward the display element side. The second refractive surface refracts light from the second concave reflective surface. The space between the first and second refracting surfaces is filled with a material having a refractive index greater than 1.4 and less than 2.

2. The intermediate image is formed between the first concave reflective surface and the second concave reflective surface. The second optical system forms an intermediate image on the display element, and The light rays at the center of the display element are incident perpendicularly on the pupil plane.

8. The optical system of claim 7, wherein the second optical system is configured to be rotationally symmetric. The pupil plane and the display element surface are arranged in parallel, and When the length of the ray with the longest optical path from the pupil plane to the first concave reflecting surface in the direction perpendicular to the pupil plane from the pupil plane to the first concave reflecting surface is represented by L1, and The length from the pupil plane to the center of the pupil-side surface of the second optical system in a direction perpendicular to the pupil plane is represented by L2. Then the following expression (7) is satisfied. [Mathematical Expression 6] 。 9. The optical system of claim 2, wherein the first optical element comprises a first waveplate, the first waveplate shifting the phase of the vertical polarization component of the light by 90 degrees. The second optical system includes a third optical element, which includes a second waveplate that shifts the phase of the vertical polarization component of the light by 90 degrees. The slow axes of the first and second wave plates are orthogonal or parallel to each other.

10. The optical system of claim 9, further comprising: The first polarizer for transmitted linearly polarized light is located on the pupil side relative to the first waveplate.

11. The optical system of claim 9, further comprising: The second polarizer for transmitting linearly polarized light is located on the display element side relative to the second waveplate.

12. The optical system of claim 9, wherein the first optical element and the third optical element have a parallel plate shape.

13. The optical system of claim 9, wherein the third optical element is positioned relative to the second optical element on the display element side.

14. The optical system of claim 9, wherein the second optical system further comprises a fourth optical element, the fourth optical element separating polarized light and having a surface tilted at 45 degrees relative to the optical axis.

15. The optical system of claim 1, further comprising: A light guide, worn by the user and positioned in front of the pupil, guides the image projected by the display element to the pupil. The first and second optical systems are placed between the display element and the light guide, and The light guide causes light from the first and second optical systems to be imaged on the pupil.

16. The optical system of claim 2, wherein for light having wavelengths from 400 nm to 700 nm, the semi-transmissive reflective surface is used as a transmissive surface.

17. The optical system of claim 7, wherein for light having wavelengths from 400 nm to 700 nm, the first concave reflective surface serves as a transmissive surface.

18. The optical system of claim 16, further comprising: An imaging optical system, which acts as a detection unit to capture the movement of the user's pupil, is positioned on the display element side of the first reflective surface and does not overlap with the second optical system, and detects infrared light.

19. The optical system of claim 18, comprising: The plurality of imaging optical systems, including a first imaging optical system and a second imaging optical system, The first imaging optical system and the second imaging optical system are placed symmetrically relative to the central axis of the first reflective surface.

20. The optical system of claim 18, further comprising: The light source is arranged on the display element side of the first reflective surface and in a position that does not overlap with the second optical system and the imaging optical system, and emits infrared light.

21. The optical system of claim 20, comprising: The plurality of light sources, including a first light source and a second light source, The first light source and the second light source are placed symmetrically with respect to the central axis of the first reflective surface.

22. The optical system of claim 20, wherein the light source comprises an LED.

23. The optical system of claim 18, further comprising: The control unit changes the optical power of the entire second optical system. The detection unit detects the movement of the user's pupil as the radial movement relative to the center of the eyeball, and The control unit adjusts the optical power of the entire second optical system based on the detected amount of movement.

24. The optical system of claim 23, wherein the control unit changes the optical power of the entire second optical system by moving at least two lens groups included in the second optical system along the optical axis.

25. The optical system of claim 23, wherein the second optical system comprises at least two liquid lenses, and The control unit changes the optical power of the entire second optical system by applying voltage to the liquid lens.

26. The optical system of claim 24, wherein when the control unit changes the optical power of the entire second optical system, The distance between the first optical element and the display element remains constant.

27. The optical system of claim 18, wherein the detection unit detects light having a wavelength from 400 nm to 700 nm that has passed through the first optical system.

28. A display device comprising, from the pupil side, a first optical system, a second optical system, and a display element, wherein the first optical system comprises: The first reflecting surface reflects light emitted from the pupil side towards the pupil side; and The second reflective surface reflects light reflected towards the pupil from the display element side. The first reflecting surface has a concave shape and forms an intermediate image on the pupil side. The pupil side of the first reflecting surface is filled with a material having a refractive index greater than 1. The second optical system is positioned on the display element side relative to the intermediate imaging plane that forms the intermediate image, and is configured such that the intermediate imaging plane and the surface of the display element have a conjugate relationship. The second optical system includes at least three lenses, two of which have different Abbe numbers, and the second optical system as a whole has positive power.

29. An optical system comprising, sequentially from the user's pupil side to the display element side, a first optical system and a second optical system, wherein the first optical system comprises: The first reflecting surface reflects light emitted from the pupil side towards the pupil side; and The second reflective surface reflects light reflected towards the pupil from the display element side. The first reflecting surface has a concave shape and forms an intermediate image on the pupil side. The pupil side of the first reflecting surface is filled with a material having a refractive index greater than 1. The second optical system is positioned on the display element side relative to the intermediate imaging plane that forms the intermediate image, and is configured such that the intermediate imaging plane and the surface of the display element have a conjugate relationship. The second optical system includes at least two surfaces with positive optical power and one surface with negative optical power, and The second optical system as a whole has positive optical power.

30. The optical system of claim 29, wherein the first optical system comprises, from the pupil side to the display element side, a first optical element and a second optical element in sequence. The first optical element, acting as the second reflective surface, functions to reflect a portion of the light. The second optical element includes: First transmission surface; and A semi-transmissive reflective surface, serving as the first reflective surface, is positioned relative to the first transmissive surface on the display element side and has a concave shape. The space between the first transmissive surface and the semi-transmissive reflective surface is filled with a material having a refractive index greater than 1.4 and less than 2.

2. Intermediate imaging is formed between the semi-transparent reflective surface of the second optical element and the first optical element, and When the focal length of the semi-transparent reflective surface is represented by fR and the physical length from the surface of the first optical element on the display element side to the vertex of the semi-transparent reflective surface is represented by LR, the following expression (1a) is satisfied. [Mathematical Expression 7] 。 31. The optical system of claim 29, wherein the first optical system comprises: The third and fourth refractive surfaces are arranged sequentially from the pupil side to the display element side. The third concave reflective surface, acting as the first reflective surface, reflects light from the third refractive surface toward the pupil side; as well as The fourth concave reflective surface, acting as the second reflective surface, reflects light from the third concave reflective surface toward the display element side. The fourth refractive surface refracts light from the fourth concave reflective surface. The space between the third and fourth refractive surfaces is filled with a material having a refractive index greater than 1.4 and less than 2.

2. The intermediate image is formed between the third concave reflective surface and the fourth concave reflective surface. The second optical system forms an intermediate image on the display element, and The light rays at the center of the display element are incident perpendicularly on the pupil plane.

32. The optical system of claim 29, wherein the first optical system comprises, from the pupil side to the display element side, a first optical element and a second optical element in sequence. The first optical element, acting as the second reflective surface, functions to reflect a portion of the light. The second optical element includes: First transmission surface; and A semi-transmissive reflective surface, serving as the first reflective surface, is positioned relative to the first transmissive surface on the display element side and has a concave shape. The space between the first transmissive surface and the semi-transmissive reflective surface is filled with a material having a refractive index greater than 1.4 and less than 2.

2. The second optical system is an optical system that has positive optical power for the light flux from the first optical system as a whole, and includes a fifth optical element filled with a material having a refractive index greater than 1.4 and less than 2.

2. The fifth optical element, from the pupil side to the display element side, includes a second transmissive surface and a third reflective surface, respectively. The first optical system is configured such that light emitted from the pupil side is transmitted through the first optical element, transmitted through the first transmissive surface of the second optical element, reflected by the semi-transmissive reflective surface of the second optical element, transmitted through the first transmissive surface of the second optical element, reflected at the pupil side or display element side of the first optical element, transmitted through the first transmissive surface of the second optical element, and transmitted through the semi-transmissive reflective surface of the second optical element. The fifth optical element is configured such that light emitted from the first optical system side is transmitted through the second transmission surface, reflected by the third reflection surface, and totally reflected by the same surface as the second transmission surface.

33. The optical system of claim 32, wherein the following expression (9) is satisfied when the angle between the third reflecting surface of the fifth optical element and the pupil plane is represented by Ang5, the pupil plane is 0° and the clockwise direction is negative. [Mathematical Expression 8] 。 34. The optical system of claim 32, wherein the third reflecting surface is the surface of a diffractive element.

35. The optical system of claim 33, wherein the second optical system further comprises a third lens group, the third lens group comprising at least three lenses. The fifth optical element also includes a fourth reflective surface. The fifth optical element is configured such that light emitted from the first optical system side is transmitted through the second transmission surface, reflected by the third reflection surface, totally internally reflected by a surface identical to the second transmission surface, reflected by the fourth reflection surface, and transmitted through a surface identical to the second transmission surface. Light transmitted through the same surface as the second transmission surface is focused by the third lens group and imaged.

36. The optical system of claim 35, wherein the following expression (10) is satisfied when the angle between the fourth reflecting surface of the fifth optical element and the pupil plane is represented by Ang6, the pupil plane is 0° and the clockwise direction is negative. [Mathematical Expression 9] 。 37. The optical system of claim 35, wherein when the angle between the surface of the fifth optical element, which is identical to the second transmission surface, which performs total internal reflection of light, and the direction of light traveling perpendicularly from the pupil plane is represented by Ang7, the following expression (11) is satisfied. [Mathematical Expression 10] 。 38. The optical system of claim 29, wherein the first optical system includes, from the pupil side, a third refractive surface, a first reflective surface, a second reflective surface, and a fourth refractive surface, the third refractive surface having a concave shape, the first reflective surface being a concave reflective surface, the second reflective surface being the same surface as the third refractive surface and having a convex shape relative to the light reflected by the first reflective surface, and the light reflected by the second reflective surface incident on the fourth refractive surface. In a set of rays incident on the second reflecting surface, the luminous flux incident on the third refractive surface satisfies the total internal reflection condition relative to the third refractive surface, as expressed by the following expression (13). The luminous flux incident on the second reflecting surface onto a region different from the third refractive surface does not satisfy the total internal reflection condition expressed by the following expression (13) relative to the region different from the third refractive surface. The intermediate imaging position of the reference ray is located inside the first optical system. The second optical system includes at least two refractive surfaces and at least one reflective surface, wherein the at least one reflective surface includes a fifth reflective surface, and The light reflected by the fifth reflective surface of the second optical system forms an image on the surface of the display element. [Mathematical Expression 11] In expression (13), θ is the angle of incidence and n is the refractive index.

39. The optical system of claim 38, wherein when the direction of the light emitted from the pupil plane is the Z direction, the direction perpendicular to the Z direction is the Y direction, the focal length of the first optical system in the Y cross section is represented by fy1, and the optical path length from the third refractive surface to the fourth refractive surface is represented by OP1, the following expression (14) is satisfied. [Mathematical Expression 12] 。 40. The optical system of claim 38, wherein the following expression (15) is satisfied when the focal length of the Y-section of the first reflecting surface reflecting the reference ray is represented by fr1y and the focal length of the entire optical system in the Y-section is represented by fy. [Mathematical Expression 13] 。 41. The optical system of claim 40, wherein when the focal length of the first optical system in the Y-section is represented by fy1, the following expression (16) is satisfied. [Mathematical Expression 14] 。 42. The optical system of claim 38, wherein when the focal length of the first reflecting surface relative to the Y-section of the predetermined ray is denoted by fray, the predetermined ray has the maximum angle of incidence relative to the third refractive surface and passes through the region where the third refractive surface and the first reflecting surface of the first optical system are physically close to each other, and the combined focal length of the Y-section of the predetermined ray when passing through the third refractive surface and the first reflecting surface is denoted by fay, then the following expression (17) is satisfied. [Mathematical Expression 15] 。 43. The optical system of claim 42, wherein when the focal length of the Y-section of the first reflecting surface reflecting the reference ray is represented by fr1y, the following expression (18) is satisfied. [Mathematical Expression 16] 。 44. The optical system of claim 38, wherein the following expression (19) is satisfied when the focal length of the Y-section of the fifth reflecting surface is represented by fr3y and the focal length of the entire optical system in the Y-section is represented by fy. [Mathematical Expression 17] 。 45. A display device comprising, from the pupil side, a first optical system, a second optical system, and a display element, wherein the first optical system comprises: The first reflecting surface reflects light emitted from the pupil side towards the pupil side; and The second reflective surface reflects light reflected towards the pupil from the display element side. The first reflecting surface has a concave shape and forms an intermediate image on the pupil side. The pupil side of the first reflecting surface is filled with a material having a refractive index greater than 1. The second optical system is positioned on the display element side relative to the intermediate imaging plane that forms the intermediate image, and is configured such that the intermediate imaging plane and the surface of the display element have a conjugate relationship. The second optical system includes at least two surfaces with positive optical power and one surface with negative optical power, and The second optical system as a whole has positive optical power.

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