Multi-focal-plane optical system

Abstract

The invention belongs to the field of optical imaging devices, and particularly relates to a multi-focal-plane optical system, which comprises light sources including a first light source and a second light source, the first light source emits P polarized light, and the second light source emits S polarized light; the polarizing beam splitter comprises a first surface opposite to the first light source and a second surface opposite to the second light source, the polarizing beam splitter and the plane where the first light source is located form an included angle in a first range, and the polarizing beam splitter and the plane where the second light source is located form an included angle in a second range; the first lens group is arranged opposite to the polarizing beam splitter; light emitted by the first light source is transmitted by the polarizing beam splitter and the first lens group and then is emitted to form a first image with a first focal length; the light emitted by the second light source is reflected by the polarizing beam splitter, then enters the lens in the first lens group, and then is emitted by the lens to form a second image with a second focal length. Through the arrangement, a plurality of imaging focal planes are formed, and the use experience of viewers is improved.

Description

Technical Field

[0001] The present invention belongs to the field of optical imaging devices, and in particular relates to a multi-focal plane optical system. Background Art

[0002] Among common near-eye display systems, most are single-focal-plane systems presented by light sources. Since the presented image has only one focal plane, when the viewer watches, he can only focus on this focal plane. Long-term viewing will not conform to the natural observation state of the human eye, which will cause visual fatigue to the user. For enhanced display, a single focal plane cannot bring a good visual experience to the viewer; in addition, since the focal plane distance is fixed, the eyes cannot be adjusted, which can easily lead to myopia. Summary of the invention

[0003] The present invention is proposed based on the above-mentioned requirements of the prior art. The technical problem to be solved by the present invention is to provide a multi-focal plane optical system to form multiple imaging focal planes to enhance the viewing experience of viewers.

[0004] In order to solve the above problems, the technical solution provided by the present invention includes:

[0005] A multi-focal plane optical system is provided, comprising: a light source, comprising a first light source and a second light source, wherein the first light source emits P-polarized light, and the second light source emits S-polarized light; a polarization beam splitter, comprising a first surface opposite to the first light source and a second surface opposite to the second light source, wherein the polarization beam splitter forms an angle within a first range with a plane where the first light source is located, and forms an angle within a second range with a plane where the second light source is located; a first lens group, arranged opposite to the polarization beam splitter; light emitted by the first light source is transmitted through the polarization beam splitter and the first lens group, and then emitted to form a first image with a first focal length; light emitted by the second light source is reflected through the polarization beam splitter, and then incident on a lens in the first lens group, and then emitted from the lens to form a second image with a second focal length.

[0006] Such an arrangement enables the first light source and the second light source to share part of the optical device to save space for layout. In addition, the same optical device will perform different light processing on different light sources, thereby changing the imaging path of the light source so that the images finally formed by the two light sources have different focal lengths, which can effectively avoid visual fatigue caused by the human eye staring at a fixed and single focal length for a long time. In addition, when there are two different focal lengths, they can work together to produce defocus stimulation, so as to effectively prevent, control and alleviate myopia.

[0007] Preferably, the multi-focal optical system further comprises a prism, and the polarization beam splitter is arranged in the prism.

[0008] The polarization beam splitter is fixed by setting a prism without having a significant impact on the propagation of light, and the polarization beam splitter is kept in a flat state at all times, thereby ensuring that the brightness of the picture remains uniform.

[0009] Preferably, the multi-focal optical system further includes a second lens group, and the second lens group is arranged between the second light source and the polarization beam splitter.

[0010] A second lens group is arranged between the second light source and the polarization beam splitter to change the light of the second light source, so that when other conditions remain unchanged, more light can be ensured to be incident on the polarization beam splitter, so as to improve the light utilization rate of the second light source, reduce light loss, and ensure the brightness of the final image.

[0011] Preferably, the acute angle formed by the polarization beam splitter and the plane where the first light source is located is in the range of 40°-50°; the acute angle formed by the polarization beam splitter and the plane where the second light source is located is in the range of 40°-50°.

[0012] The above-mentioned arrangement ensures that the light from the first light source and the light from the second light source can both be incident on the polarization beam splitter. In addition, it can also ensure that the light from the first light source after passing through the multi-focal optical system and the light from the second light source after passing through the multi-focal optical system can both intersect at the exit pupil position, so as to ensure that the viewer can see the images formed after passing through the first light source and the second light source respectively at the exit pupil position.

[0013] Preferably, the multi-focal plane optical system further comprises a third lens group, and the third lens group is arranged between the first light source and the polarization beam splitter.

[0014] A third lens group is arranged between the first light source and the polarization beam splitter to change the light of the first light source, so that when other conditions remain unchanged, more light can be incident on the polarization beam splitter, so as to improve the light utilization rate of the first light source, reduce light loss, and ensure the brightness of the final image.

[0015] The present invention also provides a multi-focal plane optical system, comprising: a light source, comprising a first light source and a second light source, wherein the first light source and the second light source both emit P polarized light; a polarization beam splitter, comprising a first surface and a second surface, wherein the first surface is arranged opposite to the first light source and the second light source at the same time, wherein the polarization beam splitter forms an angle within a first range with a plane where the first light source is located, and forms an angle within a second range with a plane where the second light source is located; a first lens group, comprising a lens, wherein the lens is arranged opposite to the polarization beam splitter; a quarter wave plate, arranged opposite to the second surface and the second light source; a first optical device, arranged opposite to the quarter wave plate, capable of reflecting at least a portion of light incident thereon; light emitted by the first light source is transmitted through the polarization beam splitter and the first lens group, and then emitted to form a first image with a first focal length; light emitted by the second light source is transmitted through the polarization beam splitter, then passes through the quarter wave plate and is incident on the first optical device, then passes through the quarter wave plate again after being reflected by the first optical device, is incident on the second surface of the polarization beam splitter, then is reflected by the polarization beam splitter and is incident on and passes through the first lens group, forming a second image with a second focal length.

[0016] Such an arrangement enables the first light source and the second light source to share the same optical device to save space and ensure that the light from each light source can meet at the exit pupil position. In addition, the same optical device will process the light of different light sources differently, thereby changing the imaging path of the light source, so that the images finally formed by the two light sources have different focal lengths, which can effectively avoid visual fatigue caused by the human eye staring at a fixed and single focal length for a long time. When there are two different focal lengths, they can work together to produce defocus stimulation, so as to effectively prevent and alleviate myopia.

[0017] Preferably, the multi-focal optical system further comprises a prism, and the polarization beam splitter is arranged in the prism.

[0018] The polarization beam splitter is fixed by setting a prism without having a significant impact on the propagation of light, and the polarization beam splitter is kept in a flat state at all times, thereby ensuring that the brightness of the picture remains uniform.

[0019] Preferably, the multi-focal optical system further includes a second lens group, and the second lens group is arranged between the second light source and the polarization beam splitter.

[0020] A second lens group is arranged between the second light source and the polarization beam splitter to change the light of the second light source, so that when other conditions remain unchanged, more light can be ensured to be incident on the polarization beam splitter, so as to improve the light utilization rate of the second light source, reduce light loss, and ensure the brightness of the final image.

[0021] Preferably, the acute angle formed by the polarization beam splitter and the plane where the first light source is located is in the range of 40°-50°; the acute angle formed by the polarization beam splitter and the plane where the second light source is located is in the range of 40°-50°.

[0022] The above-mentioned arrangement ensures that the light from the first light source and the light from the second light source can both be incident on the polarization beam splitter. In addition, it can also ensure that the light from the first light source after passing through the multi-focal optical system and the light from the second light source after passing through the multi-focal optical system can both intersect at the exit pupil position, so as to ensure that the viewer can see the images formed after passing through the first light source and the second light source respectively at the exit pupil position.

[0023] Preferably, the multi-focal optical system has a thickness of less than 31 mm.

[0024] Preferably, the first optical device includes a transmissive reflector, and the multi-focal plane optical system also includes a third light source, which emits S-polarized light and is arranged below the transmissive reflector; the light emitted by the third light source is incident on a polarizing beam splitter, is reflected by the polarizing beam splitter and passes through the first lens group to form a third image with a third focal length.

[0025] The third light source is arranged to be able to present a third image having a third focal length through the multi-focal-plane optical system.

[0026] Preferably, the multi-focal plane optical system further comprises a fourth lens group, which is arranged between the third light source and the transparent reflector.

[0027] A second lens group is arranged between the third light source and the transflector to change the light of the third light source, so that when other conditions remain unchanged, more light can be ensured to be incident on the polarization beam splitter, so as to improve the light utilization rate of the third light source, reduce light loss, and ensure the brightness of the final image.

[0028] Compared with the prior art, the present invention arranges multiple light sources, and by setting the positions of the multiple light sources and the properties of the emitted light, the multiple light sources have two different light propagation paths in the same optical system, thereby making the final imaging have multiple different focal lengths; in addition, the first transparent group is set to cover the paths of the light emitted after being processed by the polarization splitter so as to intersect at the exit pupil position, so that the viewer can see images of different focal lengths at the same viewing position at the same time, and can alleviate or suppress myopia to a certain extent by controlling the display of different light sources. When used in VR or AR, it can ensure the natural combination of virtuality and display. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this specification. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0030] Figure 1 A schematic diagram of a multi-focal plane optical system in one implementation of Example 1 of the present invention;

[0031] Figure 2 A schematic diagram of the light path of a first light source in an implementation manner of Example 1 of the present invention;

[0032] Figure 3 A schematic diagram of the optical path of a second light source in an implementation manner of Example 1 of the present invention;

[0033] Figure 4 A schematic diagram of a multi-focal plane optical system in another implementation manner of Example 1 of the present invention;

[0034] Figure 5 A schematic diagram of a light path of a first light source in yet another implementation manner of Example 1 of the present invention;

[0035] Figure 6 A schematic diagram of a light path of a second light source in another implementation manner of Example 1 of the present invention;

[0036] Figure 7 is a schematic diagram of the propagation path of light from the first light source in Embodiment 2 of the present invention;

[0037] Figure 8 is a schematic diagram of the propagation path of the light from the second light source in Embodiment 2 of the present invention;

[0038] Fig. 9 A schematic diagram of a multi-focal plane optical system in one implementation of Example 2 of the present invention;

[0039] Fig.10 A schematic diagram of a light path of a first light source in an implementation manner of Example 2 of the present invention;

[0040] Fig.11 A schematic diagram of the optical path of a second light source in an implementation manner of Example 2 of the present invention;

[0041] Fig.12 A schematic diagram of a multi-focal plane optical system in another implementation manner of Example 2 of the present invention;

[0042] Fig.13 A schematic diagram of a light path of a first light source in yet another implementation manner of Example 2 of the present invention;

[0043] Fig.14 A schematic diagram of a light path of a second light source in yet another implementation manner of Example 2 of the present invention;

[0044] Fig.15 A schematic diagram of the light path of a third light source in yet another implementation manner of Example 2 of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "connected" should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection, or an integral connection, which can be a mechanical connection, or an electrical connection, which can be a direct connection, or can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] The terms "top", "bottom", "above", "lower", and "on" used throughout the description are relative to the relative positions of components of a device, such as the relative positions of the top and bottom substrates within a device. It is understood that devices are multifunctional regardless of their orientation in space.

[0048] To facilitate understanding of the embodiments of the present application, further explanation will be given below with reference to specific embodiments in conjunction with the accompanying drawings. The embodiments do not constitute a limitation on the embodiments of the present application.

[0049] Example 1

[0050] This embodiment provides a multi-focal plane optical system, such as Figure 1-Figure 6 shown.

[0051] The multi-focal optical system includes a light source, a polarization beam splitter 2 and a first lens group 3 .

[0052] The light source includes a first light source 101 and a second light source 102. The first light source 101 and the second light source 102 can be screens, that is, they can display images. The first light source 101 emits P polarized light, and an LCD liquid crystal display can be used as the first light source 101. The second light source 102 has a higher pixel density than the first light source 101, and the second light source 102 also emits S polarized light. The second light source 102 can be Micro OLED, Micro LED, LCOS, etc. When the light emitted by the second light source 102 is not polarized light or is not S polarized light, the light can be changed by processing methods such as filming so that the processed light is S polarized light.

[0053] The polarization beam splitter 2 is capable of transmitting P polarized light and reflecting S polarized light. The polarization beam splitter 2 includes a first surface and a second surface, the first surface is arranged opposite to the first light source 101, and the second surface is arranged opposite to the second light source 102. Specifically, the polarization beam splitter 2 forms an angle within a first range with the plane where the first light source 101 is located, and forms an angle within a second range with the plane where the second light source 102 is located.

[0054] Furthermore, the acute angle formed by the polarization beam splitter 2 and the plane where the first light source 101 is located is in the range of 40°-50°; the acute angle formed by the polarization beam splitter 2 and the plane where the second light source 102 is located is in the range of 40°-50°.

[0055] Preferably, the acute angle formed by the polarization beam splitter 2 and the plane where the first light source 101 and the plane where the second light source 102 are located is 45°.

[0056] The above-mentioned arrangement ensures that the light from the first light source and the light from the second light source can both be incident on the polarization beam splitter. In addition, it can also ensure that the light from the first light source after passing through the multi-focal optical system and the light from the second light source after passing through the multi-focal optical system can both intersect at the exit pupil position, so as to ensure that the viewer can see the images formed after passing through the first light source and the second light source respectively at the exit pupil position.

[0057] The first lens group 3 includes a lens, and the lens is arranged opposite to the polarization beam splitter 2. The purpose of setting the lens is to change the propagation path of the light and intersect at the exit pupil 8. The shape and position of the lens are set according to the position of the optical element. The first lens group 3 can be only one lens or multiple lenses. The lens is set to be a spherical or aspherical lens, and the material is optical resin or moldable glass. The preferred material should be a low-stress optical resin aspherical surface or optical glass aspherical surface to reduce the number of lenses in the lens group and ensure the stability of the polarization state during light transmission.

[0058] Based on the above arrangement, when the P polarized light emitted by the first light source 101 is incident on the polarization beam splitter 2 and passes through the polarization beam splitter 2 to the first lens group 3, it intersects at the exit pupil 8 after being refracted by the first lens group 3 and forms a first image with a first focal length.

[0059] When the light emitted by the second light source 102 is S-polarized light, the light is reflected when it is incident on the polarization beam splitter 2, that is, the S-polarized light is reflected to the first lens group 3. After being refracted by the first lens group 3, the light converges at the exit pupil 8 and forms a second image with a second focal length.

[0060] Through the optical path formed by the above optical devices, the first image and the second image formed by the first light source 101 and the second light source 102 have different focal lengths, that is, different focal planes are formed, which can prevent the viewer from focusing on a fixed focal plane for a long time to cause visual fatigue or cause certain damage to the eyes.

[0061] Further, the multi-focal optical system also includes a prism 4, and the polarization beam splitter 2 is arranged in the prism 4. Specifically, the prism 4 includes a plurality of sub-prisms 401 placed closely adjacent to each other. Exemplarily, the prism includes two sub-prisms placed one above the other, the upper surface of the sub-prism 401 located at the top and the lower surface of the sub-prism 401 located at the bottom are parallel to the plane where the second light source 102 is located, and the sides of the upper and lower sub-prisms 401 close to the first light source 101 are parallel to the plane where the first light source 101 is located, and the polarization beam splitter 2 arranged in the middle of the two is tilted under the clamping of the two sub-prisms 401. The two sub-prisms 401 can fix the position of the polarization beam splitter 2 while ensuring that the polarization beam splitter 2 is stably in a flat state. When the efficiency of the polarization beam splitter 2 is high, the uniformity of the light emitted by the light source will basically not change after passing through the prism 4.

[0062] The multi-focal optical system further includes a second lens group 5, which is disposed between the second light source 102 and the polarization beam splitter 2. When the second light source 102 emits light, the propagation angle of the light can be changed under the guidance of the second lens group 5; in addition, under the condition that other conditions remain unchanged, more light can be incident on the polarization beam splitter 2 to improve the light utilization rate of the second light source 102, that is, when the second light source 102 is incident on the polarization beam splitter 2 without passing through the second lens group 5, its propagation path is straight, so that a part of the light will be incident on the external environment, and when the second light source 102 passes through the second lens group 5, its propagation path can refract part of the light incident on the external environment during straight-line propagation under the action of the second lens group 5 so that it is incident on the polarization beam splitter 2, thereby achieving the improvement of light utilization rate.

[0063] The multi-focal optical system further includes a third lens group 6, which is disposed between the first light source 101 and the polarization beam splitter 2. Similar to the second lens group 5, the third lens is also disposed to improve light utilization.

[0064] By setting the properties and materials of various optical devices, the entire system occupies a smaller space, that is, this embodiment can present an image with multiple focal planes in a limited space.

[0065] In one implementation of this embodiment, Figure 1-Figure 3 As shown, the first light source 101 emits P polarized light, and the second light source 102 emits S polarized light. The first light source 101 is arranged in a vertical downward direction, and the second light source 102 is arranged in a horizontal left direction. The polarization beam splitter 2 is arranged at the intersection of the light path emitted by the first light source 101 and the light path emitted by the second light source 102, tilted to the left and downward, and arranged at an angle of 45° with the horizontal direction. The lower surface of the polarization beam splitter 2 is the first surface, and the upper surface is the second surface. The first light source 101 is arranged opposite to the first surface, and the second light source 102 is arranged opposite to the second surface. The polarization beam splitter 2 is clamped by two upper and lower sub-prisms 401. A second lens group is arranged between the second light source 102 and the self-prism 4 located above, including a first lens 501A, a second lens 502A and a third lens 503A arranged from top to bottom. The prism 4 is made of glass, and HK9 material can be preferably used. A first lens group is arranged on the left side of the prism 4, including a fourth lens 301A and a fifth lens 302A arranged from right to left, both of which are aspherical lenses made of optical resin materials. The right side surface of the fifth lens 302A is a Fresnel surface, which can reduce the thickness of the system.

[0066] The properties of the optical devices involved are shown in Tables 1 to 4, wherein Tables 1 and 2 are the optical path system parameters involved in the light propagation process of the first light source 101, and Tables 3 and 4 are the optical path system parameters involved in the light propagation process of the second light source 102.

[0067] Table 1:

[0068] Surface number Face type Radius of curvature thickness Refractive Index Abbe number Alpha Tilt Exit pupil Aperture / 10 / / / Left side of the fifth lens even aspherical surface 60.34 6.76 1.49 57.5 / The right side of the fifth lens Fresnel Aspheric -17.09 0.10 / / / Left side of the fourth lens even aspherical surface 21.37 6.34 1.49 57.5 / Right side of the fourth lens even aspherical surface 42.67 4.74 / / / Left side of prism Spherical unlimited 10 1.52 64.2 / Right side of prism Spherical unlimited 2.7 / / / First light source Spherical unlimited 0 / / /

[0069] Table 2:

[0070]

[0071]

[0072] Table 3:

[0073]

[0074] Table 4:

[0075]

[0076] Among the above surfaces, the spherical surface satisfies the equation: Where c is the inverse of the radius of curvature and r is the radial distance from a point on the surface.

[0077] The surface constructed as an aspheric surface satisfies the equation: c is the inverse of the radius of curvature, r is the radial distance of a point on the surface, k is the quadratic constant, A i are the coefficients of the higher-order terms.

[0078] like Figure 2 As shown, the light emitted by the first light source 101 enters the prism 4. Since the first light source 101 emits P polarized light, it can pass through the polarization beam splitter 2, and the light path is changed by the fourth lens 301A and the fifth lens 302A in sequence, and finally forms a first image with the focal plane at the first position. The focal length of the light path formed by the first light source 101 is about 25mm to 40mm.

[0079] like Figure 3 As shown, the light emitted by the second light source 102 adjusts the propagation path through the first lens 501A, the second lens 502A and the third lens 503A in sequence, and passes through the prism 4 located above to be incident on the polarization beam splitter 2. Since the second light source 102 emits S-polarized light, when the S light reaches the second surface, it is reflected, and the reflected light changes the light path through the fourth lens 301A and the fifth lens 302A in sequence, and finally forms a second image with the focal plane at the second position. The light propagation path of the second light source 102 is greater than the light propagation path of the first light source 101, so that the focal plane of the first image is farther than the focal plane of the second image. The focal length of the light path formed by the second light source 102 is about 14mm to 20mm.

[0080] In another implementation of this embodiment, Figure 4-Figure 6As shown. The first light source 101 emits P polarized light, and the second light source 102 emits S polarized light. The first light source 101 is arranged in a vertically upward direction, and the second light source 102 is arranged in a horizontally left direction. The polarization beam splitter 2 is arranged at the intersection of the light path emitted by the first light source 101 and the light path emitted by the second light source 102, tilted to the right and downward, and arranged at an angle of 45° with the horizontal direction. The upper surface of the polarization beam splitter 2 is the first surface, and the lower surface is the second surface. The first light source 101 is arranged opposite to the first surface, and the second light source 102 is arranged opposite to the second surface. The polarization beam splitter 2 is clamped by two upper and lower sub-prisms 401. A second lens group is arranged between the second light source 102 and the sub-prism 401 located below, including a first lens 501B and a second lens 502B arranged from bottom to top; a third lens group is arranged between the first light source 101 and the prism 4, including a third lens 601B; and a first lens group is arranged on the left side of the prism 4, including a fourth lens 301B. The properties of the optical devices involved are shown in Tables 5 to 8, wherein Tables 5 and 6 are the optical path system parameters involved in the light propagation process of the first light source 101, and Tables 7 and 8 are the optical path system parameters involved in the light propagation process of the second light source 102.

[0081] Table 5:

[0082] Device surface Face type Radius of curvature thickness Refractive Index Abbe number Alpha Tilt Exit pupil Aperture / 10 / / / Left side of the fourth lens even aspherical surface 60.41 2.25 1.49 57.5 / Right side of the fourth lens Fresnel Aspheric -22.58 1.18 / / / Left side of prism Spherical unlimited 10 1.52 64.2 Right side of prism Spherical unlimited 1.18 / / The left side of the third lens even aspherical surface 19.09 5.26 1.54 56.2 / The left side of the third lens even aspherical surface 29.01 12.35 / / / First light source Spherical unlimited / / / /

[0083] Table 6:

[0084]

[0085] In the above-mentioned surface, the equations for whether the surface type is spherical or aspherical are the same as those in the previous embodiment and will not be described in detail here.

[0086] The sagittal height of each ring zone in the Fresnel aspheric surface is 0.1mm.

[0087] Table 7:

[0088]

[0089]

[0090] Table 8:

[0091]

[0092] like Figure 5As shown, the light emitted by the first light source 101 first passes through the third lens 601B, and after the light path is adjusted by the third lens 601B, it is incident on the prism 4. Since the first light source 101 emits P polarized light, it passes through the polarization beam splitter 2, and changes the light path through the fourth lens 301B, and intersects at the position of the exit pupil 8, and finally forms a first image of the focal plane at the first position. The focal length of the first light source after passing through the light path is about 20mm to 30mm.

[0093] like Figure 6 As shown, the light emitted by the second light source 102 passes through the first lens 501B and the second lens 502B in sequence to adjust the propagation path, and passes through the prism 4 located below to be incident on the polarization beam splitter 2. Since the second light source 102 emits S polarized light, when the S light reaches the second surface, it is reflected, and the reflected light passes through the fourth lens 301B in sequence to change the propagation light path, and the light intersects at the position of the exit pupil 8 to form a second image of the calibration plane at the second position. The focal length of the second light source after passing through the light path is about 15mm to 21mm.

[0094] Example 2

[0095] This embodiment provides a multi-focal plane optical system, such as Figure 7-Figure 15 shown.

[0096] The multi-focal optical system comprises a light source, a polarization beam splitter 2 , a quarter wave plate 9 , a transflector 10 and a first lens group 3 .

[0097] The light source includes a first light source 101 and a second light source 102. The first light source 101 and the second light source 102 can be screens, that is, they can display images. The first light source 101 and the second light source 102 both emit P polarized light, and the second light source 102 has a higher pixel density than the first light source 101. Other properties or further descriptions are the same as those in Example 1 and will not be described here.

[0098] The polarization beam splitter 2 is capable of transmitting P polarized light and reflecting S polarized light. The polarization beam splitter 2 includes a first surface and a second surface, and the first surface is respectively arranged opposite to the first light source 101 and the second light source 102, so as to ensure that the light emitted by the first light source 101 and the second light source 102 can be incident on the polarization beam splitter 2. Specifically, the polarization beam splitter 2 forms an angle within a first range with the plane where the first light source 101 is located, and forms an angle within a second range with the plane where the second light source 102 is located.

[0099] Furthermore, the acute angle formed by the polarization beam splitter 2 and the plane where the first light source 101 is located is in the range of 40°-50°; the acute angle formed by the polarization beam splitter 2 and the plane where the second light source 102 is located is in the range of 40°-50°.

[0100] Preferably, the acute angle formed by the polarization beam splitter 2 and the plane where the first light source 101 and the plane where the second light source 102 are located is 45°.

[0101] The quarter wave plate 9 is arranged opposite to the second surface and the second light source 102. The quarter wave plate 9 is arranged opposite to the second light source 102 so that the light of the second light source 102 passing through the polarization beam splitter 2 is incident on the quarter glass plate, so as to convert the P light into right-handed circularly polarized light (R light); the quarter wave plate 9 is arranged opposite to the second surface so as to convert the right-handed circularly polarized light (R light) reflected from the reflector 10 into S polarized light, and the S polarized light is incident on the second surface, so as to be reflected and emitted to the first lens group 3.

[0102] The reflector 10 is arranged opposite to the quarter wave plate 9 so as to reflect the right circularly polarized light (R light) passing through the quarter wave plate 9 back and convert the right circularly polarized light into S polarized light by passing through the quarter wave plate 9 again.

[0103] The first lens group 3 is similar to the first lens group 3 in Embodiment 1 and will not be described again here.

[0104] Based on the above settings, Figure 7 As shown, the light propagation path of the first light source 101 does not change significantly. After being allowed to pass through the polarization beam splitter 2, it passes through the first lens group 3. After the first lens group 3 adjusts the direction of the light, it intersects at the exit pupil 8 to form a first image with a first focal length.

[0105] like Figure 8 As shown, the second light source 102 emits P polarized light, which, like the first light source 101, is emitted along the original propagation path through the polarization beam splitter 2 and passes through the quarter wave plate 9. At this time, the P polarized light is converted into right-handed circularly polarized R light and continues to propagate until it is incident on the reflector 10. Through reflection, a part of the right-handed circularly polarized R light is propagated along the opposite path of the original path and is made to pass through the quarter wave plate 9 again. At this time, the R light is converted into S polarized light. Since the polarization beam splitter 2 can only allow P polarized light to pass through, when the S polarized light is incident on the polarization beam splitter 2, reflection occurs, and the reflected light is incident on the first lens group 3. Under the light adjustment of the first lens group 3, it intersects at the exit pupil 8 to form a second image with a second focal length.

[0106] Furthermore, the multi-focal optical system further includes a prism 4 and a second lens group 5. The setting principle of the prism 4 in this embodiment is the same as that in Embodiment 1, and will not be described again, but there are differences in specific forms, which will be described in detail below.

[0107] The light source further includes a third light source 103 , which emits S-polarized light and is disposed below the transflective mirror 10 .

[0108] The multi-focal optical system further comprises a fourth lens group 7, which is arranged between the third light source 103 and the transflector 10. Similar to the second lens group 5, the third lens is also arranged to improve the light utilization rate.

[0109] By setting the properties and materials of various optical devices, the entire system occupies a smaller space, that is, this embodiment can present an image with multiple focal planes in a limited space.

[0110] In one implementation of this embodiment, Figure 9-11 As shown, the first light source 101 and the second light source 102 both emit P polarized light, the first light source 101 is arranged in a vertically downward direction, and the second light source 102 is arranged in a horizontally left direction. The polarization beam splitter 2 is arranged at the intersection of the light path emitted by the first light source 101 and the light path emitted by the second light source 102, tilted to the right and downward, and arranged at an angle of 45° with the horizontal direction. The upper surface of the polarization beam splitter 2 is the first surface, and the first light source 101 and the second light source 102 are both arranged opposite to the first surface. The polarization beam splitter 2 is clamped by two upper and lower sub-prisms 401, and a second lens group is arranged between the second light source 102 and the self-prism 4 located above, including a first lens 501C and a second lens 502C arranged from top to bottom. The prism 4 is made of glass, and HK9 material can be preferably used. A first lens group is arranged on the left side of the prism 4, including a third lens 301C and a fourth lens 302C arranged from right to left, both of which are aspherical lenses made of optical resin materials.

[0111] The properties of the optical devices involved are shown in Tables 9 and 10, wherein the optical path system parameters involved in the light propagation process of the first light source 101 refer to Tables 1 and 2, and Tables 9 and 10 are the optical path system parameters involved in the light propagation process of the second light source 102.

[0112] Table 9:

[0113]

[0114] Fig.10 :

[0115]

[0116] like Fig.10As shown, the light emitted by the first light source 101 first passes through the right side of the prism 4 to reach the polarization beam splitter 2, and the polarization beam splitter 2 allows P polarized light to pass through. The light passes through the polarization beam splitter 2 and the left side of the prism 4 in turn, and after the propagation path is changed by the first lens group, the light is made to intersect at the position of the exit pupil 8, and finally forms a first image with a first focal length. The first focal length is 25mm to 40mm.

[0117] like Fig.11 The light emitted by the second light source 102 is redirected by the first lens 501C and the second lens 502C in sequence, and then passes through the prism 4 and is incident on the polarization beam splitter 2. The polarization beam splitter 2 transmits the light emitted by the second light source 102 and continues to propagate along the original path until it is incident on the quarter wave plate 9. The light passing through the quarter wave plate 9 becomes right-handed circularly polarized light R and continues to be emitted, and is incident on the transflector 10. Through reflection, a part of the right-handed circularly polarized light R is propagated along the opposite path of the original path, and is made to pass through the quarter wave plate 9 again. At this time, the R light is converted into S polarized light. Since the polarization beam splitter 2 can only allow P polarized light to pass, when the S polarized light is incident on the polarization beam splitter 2, reflection occurs, and the reflected light is incident on the first lens group. Under the light adjustment of the first lens group, it intersects at the position of the exit pupil 8 to form a second image with a second focal length. The second focal length is 5mm to 7mm.

[0118] In another embodiment of the embodiment, Figure 12-Figure 15As shown. The first light source 101 and the second light source 102 emit P polarized light, and the third light source 103 emits S polarized light. The first light source 101 is arranged in a vertically downward direction, the second light source 102 is arranged in a horizontally leftward direction, and the third light source 103 is arranged in a vertically upward direction. The polarization beam splitter 2 is arranged at the intersection of the light path emitted by the first light source 101 and the light path emitted by the second light source 102, tilted to the right and downward, and arranged at an angle of 45° to the horizontal direction. The upper surface of the polarization beam splitter 2 is the first surface, and the lower surface is the second surface. The first light source 101 and the second light source 102 are arranged opposite to the first surface, and the third light source 103 is arranged opposite to the second surface. The polarization beam splitter 2 is sandwiched by two upper and lower sub-prisms 401. A second lens group is arranged between the second light source 102 and the sub-prism 401 located below, including a first lens 501D and a second lens 502D arranged from top to bottom; a fourth lens group is arranged between the third light source 103 and the prism 4, including a fifth lens 701D and a sixth lens 702D arranged from bottom to top; a first lens group is arranged on the left side of the prism 4, including a third lens 301D and a fourth lens 302D arranged from right to left. The properties of the above-mentioned optical devices are shown in Table 5, Table 6, Table 11-Table 13, wherein Table 5 and Table 6 are the optical path system parameters involved in the light propagation process of the first light source 101, Table 11 and Table 12 are the optical path system parameters involved in the light propagation process of the second light source 102, and Table 13 is the optical path system parameters involved in the light propagation process of the third light source 103.

[0119] Table 11:

[0120]

[0121]

[0122] Table 12:

[0123]

[0124] Table 13:

[0125]

[0126]

[0127] like Fig.13 As shown, the propagation path of the light emitted by the first light source 101 is the same as that of the previous embodiment, first passing through the right side of the prism 4 to reach the polarization beam splitter 2, the polarization beam splitter 2 allows P polarized light to pass, and the light passes through the polarization beam splitter 2 and the left side of the prism 4 in turn, and after the propagation path is changed by the first lens group, the light is made to intersect at the position of the exit pupil 8, and finally forms a first image with a first focal length. The first focal length is 25mm to 40mm.

[0128] like Fig.14 As shown, the light emitted by the second light source 102 passes through the first lens 501D and the second lens 502D in sequence, passes through the prism 4 and is incident on the polarization beam splitter 2. The polarization beam splitter 2 passes through the light emitted by the second light source 102 and continues to propagate along the original path until it is incident on the quarter wave plate 9. The light passing through the quarter wave plate 9 becomes right-handed circularly polarized light R light and continues to be emitted, and is incident on the transflector 10. Through reflection, a part of the right-handed circularly polarized light R light is propagated along the opposite path of the original path, and is made to pass through the quarter wave plate 9 again. At this time, the R light is converted into S polarized light. Since the polarization beam splitter 2 can only allow P polarized light to pass, when the S polarized light is incident on the polarization beam splitter 2, reflection occurs, and the reflected light is incident on the third lens 301D and the fourth lens 302D of the first lens group. Under the light adjustment of the first lens group, they intersect at the position of the exit pupil 8 to form a second image with a second focal length. The second focal length is 15mm to 25mm.

[0129] like Fig.15 As shown, the light emitted by the third light source 103 is redirected by the fifth lens 701D and the sixth lens 702D in sequence, passes through the transflector 10 and is incident on the quarter wave plate 9 to form right-handed circularly polarized light R, and part of the light passing through the prism 4 and incident on the polarization beam splitter 2 can pass through the polarization beam splitter 2, while the other part cannot pass through, that is, it is incident on the first lens group in a reflected manner, and passes through the third lens 301D and the fourth lens 302D in sequence, and the light intersects at the exit pupil 8 to form a third image with a third focal length. The third focal length is 12mm to 18mm.

[0130] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation method of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A multi-focal optical system, characterized in that: include: The light source comprises a first light source and a second light source, wherein the first light source emits P-polarized light and the second light source emits S-polarized light; A polarizing beam splitter, comprising a first surface opposite to the first light source and a second surface opposite to the second light source, wherein the polarizing beam splitter forms an angle within a first range with the plane where the first light source is located, and forms an angle within a second range with the plane where the second light source is located; A first lens group, arranged opposite to the polarization beam splitter; The light emitted by the first light source is transmitted through the polarization beam splitter and the first lens group, and then emitted to form a first image with a first focal length; the light emitted by the second light source is reflected by the polarization beam splitter, and then incident on the lens in the first lens group, and then emitted from the lens to form a second image with a second focal length.

2. The multi-focal optical system according to claim 1, characterized in that: The multi-focal optical system further comprises a prism, and the polarization beam splitter is arranged in the prism.

3. The multi-focal optical system according to claim 1 or 2, characterized in that: The multi-focal optical system further includes a second lens group, and the second lens group is arranged between the second light source and the polarization beam splitter.

4. The multi-focal optical system according to claim 3, characterized in that: The acute angle formed by the polarization beam splitter and the plane where the first light source is located is in the range of 40°-50°; the acute angle formed by the polarization beam splitter and the plane where the second light source is located is in the range of 40°-50°.

5. The multi-focal optical system according to claim 4, characterized in that: The multi-focal plane optical system further includes a third lens group, and the third lens group is arranged between the first light source and the polarization beam splitter.

6. A multi-focal optical system, characterized in that: include: The light source comprises a first light source and a second light source, wherein the first light source and the second light source both emit P polarized light; A polarizing beam splitter, comprising a first surface and a second surface, wherein the first surface is arranged opposite to the first light source and the second light source at the same time, and the polarizing beam splitter forms an angle within a first range with the plane where the first light source is located, and forms an angle within a second range with the plane where the second light source is located; A first lens group includes a lens, wherein the lens is arranged opposite to the polarization beam splitter; a quarter wave plate, arranged opposite to the second surface and the second light source; a first optical device, disposed opposite to the quarter wave plate, capable of reflecting at least a portion of light incident thereon; The light emitted by the first light source is transmitted through the polarization beam splitter and the first lens group, and then emitted to form a first image with a first focal length; the light emitted by the second light source is transmitted through the polarization beam splitter, passes through a quarter wave plate and is incident on the first optical device, is reflected by the first optical device, passes through the quarter wave plate again, is incident on the second surface of the polarization beam splitter, is reflected by the polarization beam splitter, and then is incident on and passes through the first lens group to form a second image with a second focal length.

7. The multi-focal optical system according to claim 6, characterized in that: The multi-focal optical system further comprises a prism, and the polarization beam splitter is arranged in the prism.

8. The multi-focal optical system according to claim 6 or 7, characterized in that: The multi-focal optical system further includes a second lens group, and the second lens group is arranged between the second light source and the polarization beam splitter.

9. The multi-focal optical system according to claim 8, characterized in that: The acute angle formed by the polarization beam splitter and the plane where the first light source is located is in the range of 40°-50°; the acute angle formed by the polarization beam splitter and the plane where the second light source is located is in the range of 40°-50°.

10. The multi-focal optical system according to claim 1 or 6, characterized in that: The multi-focal optical system has a thickness of less than 31 mm.

11. The multi-focal optical system according to claim 9, characterized in that: The first optical device includes a transmissive reflector, and the multi-focal optical system also includes a third light source, which emits S-polarized light and is arranged below the transmissive reflector; the light emitted by the third light source is incident on a polarizing beam splitter, is reflected by the polarizing beam splitter and passes through the first lens group, thereby forming a third image with a third focal length.

12. The multi-focal optical system according to claim 11, characterized in that: The multi-focal plane optical system further includes a fourth lens group, which is arranged between the third light source and the transparent reflector.

Images