WO2023097813A1 - 光学系统以及头戴显示设备 - Google Patents

光学系统以及头戴显示设备 Download PDF

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Publication number
WO2023097813A1
WO2023097813A1 PCT/CN2021/140023 CN2021140023W WO2023097813A1 WO 2023097813 A1 WO2023097813 A1 WO 2023097813A1 CN 2021140023 W CN2021140023 W CN 2021140023W WO 2023097813 A1 WO2023097813 A1 WO 2023097813A1
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Prior art keywords
lens
optical system
optical
present application
fresnel
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PCT/CN2021/140023
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English (en)
French (fr)
Inventor
孙琦
赵博刚
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歌尔光学科技有限公司
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Application filed by 歌尔光学科技有限公司 filed Critical 歌尔光学科技有限公司
Priority to EP21957712.9A priority Critical patent/EP4215977A4/en
Priority to JP2023526884A priority patent/JP7462115B2/ja
Priority to US18/247,047 priority patent/US20240184094A1/en
Priority to KR1020237011024A priority patent/KR20230084150A/ko
Publication of WO2023097813A1 publication Critical patent/WO2023097813A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B25/00—Eyepieces; Magnifying glasses
    • G02B25/001—Eyepieces
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
    • G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
    • G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
    • G02B13/004—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having four lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
    • G02B1/041—Lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/02—Simple or compound lenses with non-spherical faces
    • G02B3/08—Simple or compound lenses with non-spherical faces with discontinuous faces, e.g. Fresnel lens
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
    • G02B9/12—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having three components only
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B2027/0118—Head-up displays characterised by optical features comprising devices for improving the contrast of the display / brillance control visibility
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B2027/0178—Eyeglass type

Definitions

  • the present application relates to the technical field of optical imaging, and more specifically, the present application relates to an optical system and a head-mounted display device.
  • augmented reality Augmented Reality
  • virtual reality Virtual Reality
  • the core components of augmented reality technology and virtual reality technology are both display optical systems. Therefore, the quality of the display optical system will directly determine the quality of smart wearable devices.
  • a VR device is taken as an example.
  • a 1.4-inch display screen achieves a large field of view (FOV) and a short total optical length (TTL)
  • the conventional optical solution is a folded optical path structure, but it has high production costs and low light efficiency. ( ⁇ 25%) and there is a problem of ghosting.
  • the purpose of this application is to provide a new technical solution for an optical system and a head-mounted display device.
  • an optical system includes a third lens, a second lens and a first lens arranged in sequence along the propagating direction of the incident light;
  • the refractive power of the third lens is positive
  • the viewing angle of the optical system is ⁇ 100 degrees.
  • the refractive powers of the first lens and the second lens are both positive;
  • the first lens, the second lens and the third lens are located on the same optical axis.
  • two adjacent surfaces of the first lens and the second lens are Fresnel surfaces.
  • the first lens includes a first surface and a second surface
  • the second lens includes a third surface and a fourth surface
  • the second surface and the third surface are adjacent to each other, and both are Fresnel surfaces;
  • Both the first surface and the fourth surface are aspherical.
  • the third lens includes a fifth surface and a sixth surface
  • One of the fifth surface and the sixth surface is a Fresnel surface, and the other of the fifth surface and the sixth surface is an aspherical surface;
  • the Fresnel surface of the third lens is adjacent to the fourth surface of the second lens.
  • a first interval T1 is set between the first lens and the second lens, and the first interval T1 is set to be 0.2mm ⁇ T1 ⁇ 1mm.
  • a second interval T2 is set between the second lens and the third lens, and the second interval T2 is set to 1mm ⁇ T1 ⁇ 3mm.
  • the effective focal length f1 of the first lens is: 30mm ⁇ f1 ⁇ 40mm;
  • the effective focal length f2 of the second lens is: 40mm ⁇ f2 ⁇ 460mm;
  • the effective focal length f3 of the third lens is: 65mm ⁇ f3 ⁇ 115mm.
  • the first lens, the second lens and the third lens are made of COP material, OKP material, EP material or PMMA material.
  • a head-mounted display device includes any one of the optical systems described above.
  • the embodiment of the present application provides a straight-through optical structure design scheme, in which three optical lenses are used, and three Fresnel surfaces are designed in the optical path structure, which can provide strong convergence ability, thereby reducing optical
  • the total optical length TTL of the system and the increased field of view FOV can also make the light efficiency of the optical system at a higher level; two Fresnel surfaces are adjacent to each other, which helps to reduce stray light.
  • the solution provided by the embodiment of the present application realizes the optical design requirements of short focal length, high light efficiency, and large FOV. Displays the development trend of miniaturization and light weight of equipment.
  • Fig. 1 is a schematic structural diagram of an optical system provided by an embodiment of the present application.
  • Fig. 2 is a schematic diagram of the imaging principle of the optical system provided by the embodiment of the present application.
  • Fig. 3 is a spot diagram of the optical system provided by Embodiment 1 of the present application.
  • FIG. 4 is a field curvature and distortion diagram of the optical system provided in Embodiment 1 of the present application.
  • FIG. 5 is a dispersion diagram of the optical system provided in Embodiment 1 of the present application.
  • Fig. 6 is a schematic diagram of the imaging principle of the optical system provided in Embodiment 2 of the present application.
  • Figure 7 is a spot diagram of the optical system provided by Embodiment 2 of the present application.
  • Fig. 8 is a field curvature and distortion diagram of the optical system provided by Embodiment 2 of the present application.
  • FIG. 9 is a dispersion diagram of the optical system provided by Embodiment 2 of the present application.
  • the first lens 2. The second lens; 3. The third lens; 4. Display screen; 5. Human eyes;
  • an optical system is provided.
  • the optical system is a short-focus, high-efficiency, and large-FOV straight-through optical structure solution, which is suitable for use in electronic equipment, such as head mounted display (head mounted display, HMD), such as VR equipment (such as VR glasses or VR headset, etc.). It has a good application prospect.
  • An optical system provided by an embodiment of the present application includes a third lens 3, a second lens 2 and a first lens 1 arranged in sequence along the propagation direction of incident light;
  • the refractive power of the third lens 3 is positive;
  • the viewing angle of the optical system is ⁇ 100 degrees.
  • the optical system provided in the embodiment of the present application is designed with a straight-through optical path structure, and the optical path structure is relatively simple, so that its manufacture is relatively easy.
  • the optical system may also include a display screen (display) 4 .
  • the display screen 4 can be used to emit light in the light path structure, that is, to provide incident light for the optical system.
  • a lens combination is designed and applied, and the lens combination includes, for example, three optical lenses, as shown in Figures 1 and 2.
  • the position on the light exit side of the screen 4 is specifically located in the propagation direction of the incident light emitted by the display screen 4, which can be used to project the incident light into the human eye 5 for imaging, thereby realizing the imaging function of the optical system.
  • the optical system provided by the embodiment of the present application is based on the combination of three optical lenses, that is, the combination of the first lens 1, the second lens 2 and the third lens 3 Combination, and the surface combination of these three lenses is designed as Fresnel surface + aspheric surface, the three Fresnel surfaces in the optical path structure can provide greater focal power and achieve ultra-short focus, Moreover, the collocation of two Fresnel surfaces arranged adjacent to each other helps to reduce stray light. Moreover, by rationally setting the surface shape of the third lens 3, it is helpful to realize high resolution and low dispersion.
  • the Fresnel surfaces of the first lens 1 , the second lens 2 and the third lens 3 include but are not limited to planar substrates.
  • the Fresnel surfaces of the first lens 1, the second lens 2, and the third lens 3 can also be curved substrates, and those skilled in the art can adjust the substrates of the Fresnel surfaces according to specific conditions. form, which is not specifically limited in this application.
  • the lens can be made thinner and lighter.
  • the embodiment of the present application provides a straight-through optical structure design scheme, in which three optical lenses are used, and three Fresnel surfaces are designed in the optical path structure, which can provide strong convergence ability, thereby reducing optical
  • the total optical length TTL of the system and the increased field of view FOV can also make the light efficiency of the optical system at a higher level; among them, two Fresnel surfaces are adjacently arranged, and this design helps to reduce stray light.
  • the solution provided by the embodiment of the present application realizes the optical design requirements of short focus, high light efficiency, and large FOV, and the formed optical system can be applied to, for example, head-mounted display devices (such as VR devices), and also helps to realize head-mounted display The development trend of miniaturization and light weight of equipment.
  • head-mounted display devices such as VR devices
  • the optical path design scheme provided by the embodiment of the present application overcomes the fact that the existing single-chip lens + display screen (display) scheme brings the lens far away from the display screen, resulting in a larger size of the VR device, which is not conducive to product quality.
  • the problem of miniaturization is not feasible to product quality.
  • the folded optical path scheme has disadvantages such as high cost, low light efficiency and ghosting.
  • the solution provided in the embodiment of the present application adopts a straight-through optical solution, which can provide strong converging ability (focal power, optical power), thereby reducing the total optical length TTL of the optical system and increasing the field of view of the optical system FOV can also improve the light efficiency, so that the light effect is at a higher level.
  • a display screen 4 is provided in the optical system, and the display screen 4 is, for example, a 1.4inch Display, which realizes a 100-degree viewing angle.
  • the display screen 4 is, for example, a 1.4inch Display, which realizes a 100-degree viewing angle.
  • neither the conventional single-lens (1P) structure nor the double-lens (2P) structure is sufficient to distinguish this type of display screen. The reason is that:
  • the monolithic lens (1P) only has the optimization of the degree of freedom of the two surfaces, its converging ability is limited, and the aberration or chromatic aberration cannot be corrected.
  • the resolvable pixel size (spot size) of the full field of view is about 80 ⁇ m ⁇ 100 ⁇ m, and more importantly, the purpose of short focal length cannot be achieved.
  • the double-piece lens (2P) increases the freedom of lens surface optimization and can achieve short focus, it still has limitations in resolution.
  • the resolvable pixel size (spot size) of the full field of view is about 60 ⁇ m ⁇ 80 ⁇ m.
  • the optical lens combination structure adopted in the embodiment of the present application can further improve the resolving power, and can correct chromatic aberration to a certain extent, forming a straight-through short-focus optical path structure.
  • the combined use of three Fresnel surfaces can provide greater optical power, and the third lens 3 near the display screen 4 can be used for achromatic treatment, which helps to improve the imaging quality.
  • optical system provided in the embodiment of the present application is not limited to setting only three Fresnel surfaces.
  • the optical system may also include more lenses, and more Fresnel surfaces are set in the optical path structure, and those skilled in the art can flexibly adjust according to specific conditions.
  • the refractive powers of the first lens 1 and the second lens 2 are positive; the first lens 1, the second lens 2 and the third lens 3 are located on the same optical axis.
  • the three lenses provided in the embodiments of the present application are all designed as positive lenses.
  • the light emitted by the display screen 4 enters into the second lens 2 (positive lens) after passing through the third lens 3 (positive lens) as incident light, and the incident light passes through the The second lens 2 then converges and then enters the first lens 1 .
  • the first lens 1 is still a converging positive lens, and the incident light transmitted through the first lens 1 enters the human eye 5 for imaging.
  • the entire optical path structure does not involve the optical path folding scheme, which is a straight-through optical path structure.
  • the two adjacent surfaces of the first lens 1 and the second lens 2 are Fresnel surfaces. Employing this design in the optical system helps reduce stray light.
  • the first lens 1 includes a first surface 11 and a second surface 12, and the second lens 2 includes a third surface 21 and a fourth surface 22 ;
  • the second surface 12 and the third surface 21 are adjacent to each other, and both are Fresnel surfaces;
  • Both the first surface 11 and the fourth surface 22 are aspherical.
  • the first surface 11 of the first lens 1 directly faces the human eye 5, which is located outside, the first surface 11 is for example Set as an aspheric surface (further, the first surface 11 is a convex surface); the second surface 12 of the first lens 1 is set as a Fresnel surface, and like this, the first lens 1 (positive lens) just forms There are two types of combination of aspheric surface + Fresnel surface.
  • Anti-Reflective coatings are respectively coated on the first surface 11 and the second surface 12 of the first lens 1 .
  • the reflected light can be reduced through the anti-reflection film, so as to increase the light transmission on the two surfaces of the first lens 1 Overrate.
  • a hardening coating may also be coated on the first surface 11 .
  • the first surface 11 of the first lens 1 is facing the outside, and it needs to avoid damages such as scratches and bruises, and the use of the first lens 1 can be improved by coating the hardened film. life. Coating a hardened film on the first surface 11 , that is, hardening the first surface 11 , can improve the hardness, strength, etc. of the first surface 11 . This is beneficial for increasing the service life of the entire optical system.
  • the first lens 1 also has the following parameters.
  • the absolute value of the radius R 1 of the first surface 11 of the first lens 1 satisfies: 50mm ⁇ Abs(R 1 ) ⁇ 80mm;
  • the absolute value of the radius R 2 satisfies: 25mm ⁇ Abs(R 2 ) ⁇ 30mm;
  • the absolute value of the conic coefficient K 1 of the first surface 11 and the second surface 12 satisfies: Abs(K 1 ) ⁇ 10.
  • the surface designs of the first surface 11 and the second surface 12 are different.
  • the outwardly facing first surface 11 is designed as an aspheric surface (such as a convex surface), and the second surface 12 is designed as a Fresnel surface, and the first surface formed by combining the Fresnel surface and the aspheric surface
  • the lens 1 in the optical path structure helps to achieve the effect of short focus and high resolution.
  • the conic coefficient (Coin Constant) of the first lens 1 namely
  • K 1 is, for example, set at [-10, 10], and the radius R of the Fresnel surface of the first lens 2>23mm.
  • the surface combination form of the second lens 2 and the first lens 1 may be the same, and a narrow air gap is maintained between them.
  • the third surface 21 of the second lens 2 is a Fresnel surface
  • the fourth surface 22 of the second lens 2 is configured as an aspheric surface (further, the fourth surface 11 is also a convex surface).
  • the second lens 2 is also a positive lens, which is located between the first lens 1 and the third lens 3 , and the second lens 2 is arranged closer to the first lens 1 .
  • an anti-reflective coating (Anti-Reflective coating, AR) is coated on the third surface 21 and the fourth surface 22 of the second lens 2 .
  • the anti-reflection coating is used to reduce reflected light, so as to increase the transmittance of light on both surfaces of the second lens 2 .
  • the second lens 2 also has the following parameters.
  • the absolute value of the radius R 3 of the second surface 21 of the second lens 2 satisfies: 25mm ⁇ Abs(R 3 ) ⁇ 30mm;
  • the absolute value of the radius R 4 satisfies: Abs(R 4 ) ⁇ 120mm;
  • the absolute value of the conic coefficient K 2 of the third surface 21 and the fourth surface 22 satisfies: Abs(K 2 ) ⁇ 10.
  • the conic coefficient (Coin Constant) of the second lens 2 that is, The value of K 2 is designed to be [-10, 10], and the radius of the Fresnel surface of the second lens 2 is >23mm.
  • the third lens 3 includes a fifth surface 31 and a sixth surface 32; one of the fifth surface 31 and the sixth surface 32 is a Fresnel surface, the other of the fifth surface 31 and the sixth surface 32 is an aspheric surface; the Fresnel surface of the third lens 3 and the fourth surface 22 of the second lens 2 set for the neighbors.
  • the fifth surface 31 is configured as a Fresnel surface
  • the sixth surface 32 is configured as a concave surface.
  • the surface adjacent to the fourth surface 22 of the second lens 2 is a Fresnel surface
  • the surface adjacent to the display screen 4 is a concave surface.
  • the third lens 3 can be used for achromatization in the entire optical path structure.
  • both the fifth surface 31 and the sixth surface 32 are coated with an anti-reflective coating (Anti-Reflective coating, AR).
  • Anti-Reflective coating AR
  • the reflected light can be reduced through the anti-reflection film, so as to increase the light transmission on the two surfaces of the third lens 3 Overrate.
  • the optical system is optimally designed, wherein the two Fresnel surfaces + aspheric surface (convex surface) of the first lens 1 and the second lens 2 are used, combined with the third lens 3
  • the combination of Fresnel surface + aspheric surface (concave surface) well realizes the characteristics of short focus, high light efficiency, low dispersion and large FOV.
  • the third lens 3 also has the following parameters.
  • the absolute value of the radius R 5 of the fifth surface 31 of the third lens 3 satisfies: 30mm ⁇ Abs(R 5 ) ⁇ 50mm; the radius R 5 of the sixth surface 32 of the third lens 3 The absolute value of the radius R 6 satisfies: 110mm ⁇ Abs(R 6 ) ⁇ 170mm; the absolute value of the conic coefficient K 3 of the fifth surface 31 and the sixth surface 32 satisfies: Abs(K 3 ) ⁇ 10.
  • the conic coefficient (Coin Constant) of the third lens 3 that is, The value of K 2 is designed to be [-10, 10], and the radius of the Fresnel surface of the third lens 3 is >23mm.
  • the first lens 1 , the second lens 2 and the third lens 3 all have Fresnel surfaces.
  • the surface parameters it is necessary to set the surface parameters within a certain range, otherwise there will be low processing accuracy or risk of tool breakage (this is because the processing of the tooth profile is difficult, the smaller the sharp angle of the tooth profile, the more difficult it is to process the more difficult the inclination and movement).
  • the first lens 1 and the second lens 2 are combined by aspheric (convex) + Fresnel surface
  • the third lens 3 is an aspheric
  • the optical system includes a display screen 4, and the first lens 1, the second lens 2 and the third lens 3; wherein, the display screen 4 As a display light source, it can emit light, which can enter each lens as incident light; both the first lens 1 and the second lens 2 are positive lenses, and both are convex + Fresnel surfaces
  • the third lens 3 is also a positive lens, which is a Fresnel surface + a concave surface.
  • the surfaces of the three lenses are coated with an anti-reflection coating, and the first surface 11 of the first lens 1 is also treated with a hardening coating and an anti-reflection coating.
  • the incident light emitted by the display screen 4 enters the inside of the third lens 3 through the sixth surface 31 (concave surface) of the third lens 3 coated with an antireflection film, and passes through the transmission of the third lens 3
  • the light enters the second lens 2 again, and the two surfaces of the second lens 2 are also coated with an anti-reflection film. In this way, the incident light is converged after passing through the second lens 2, and then enters into the second lens 2.
  • a lens 1, the first lens 1 is still a converging positive lens, after the light is transmitted through the first lens 1, it enters the human eye 5 for imaging. There is no optical path folding in the entire optical system, and the surface of each lens is coated with an anti-reflection film, so that the light transmission efficiency is high.
  • a first interval T 1 is set between the first lens 1 and the second lens 2 , and the first interval T 1 is set to be 0.2 mm ⁇ T 1 ⁇ 1 mm.
  • a second interval T 2 is set between the second lens 2 and the third lens 3 , and the second interval T 2 is set to be 1 mm ⁇ T 1 ⁇ 3 mm.
  • a narrow air gap is set between the first lens 1 and the second lens 2; at the same time, between the second lens 2 and the third lens 3 A narrower air gap is also provided.
  • the optimized design of the air space between the lenses helps to realize the miniaturization of the entire optical system.
  • the distance between the third lens 3 and the display screen 4 needs to be considered after the distance between the lenses is arranged reasonably.
  • the third lens 3 is arranged near the side of the display screen 4 .
  • a third interval T 3 is set between the third lens 3 and the display screen 4 .
  • the third interval T 3 is set to be 5mm ⁇ T 2 ⁇ 15mm.
  • the effective focal length f 1 of the first lens 1 is: 30mm ⁇ f 1 ⁇ 40mm ;
  • the effective focal length f2 of the second lens 2 is: 40mm ⁇ f2 ⁇ 460mm ;
  • the effective focal length f 3 of the third lens 3 is: 65mm ⁇ f 3 ⁇ 115mm.
  • the first lens 1, the second lens 2 and the third lens 3 all have a Fresnel surface, which can provide a larger optical power, so that the optical system has a short focal characteristics.
  • the application provides a short-focus optical system. There is no optical path folding in the entire optical system, and it is a straight-through optical system that can achieve high-definition imaging.
  • the central thickness h 1 of the first lens 1 is: 2mm ⁇ h 1 ⁇ 4mm; the central thickness h2 of the second lens 2 is: 3mm ⁇ h 2 ⁇ 5mm; The central thickness h 3 of the third lens 3 is: 2mm ⁇ h 3 ⁇ 4mm.
  • each lens will not be too thick, which is also beneficial to reduce the weight of the entire optical path structure.
  • the first lens 1 , the second lens 2 and the third lens 3 are made of COP material, OKP material, EP material or PMMA material.
  • the application provides a short-focus optical system. There is no optical path folding in the entire optical system, and it is a straight-through optical system that can achieve high-definition imaging.
  • the distortion is less than 38.3%, and the curvature of field is less than 1.1mm.
  • the color difference is less than 236um.
  • the virtual image distance is 1500mm.
  • the spot size of the optical system is less than 73um, realizing clear imaging in the visible light band (450nm ⁇ 630nm).
  • the effective focal length of the entire optical system is 17mm.
  • Embodiment 1 provides an optical system, and Table 1 is used to show the structural parameters in the optical system.
  • Table 1 lists the optical surface number (Surface) numbered sequentially from the human eye 5 (diaphragm) to the display screen 4, the curvature (C) of each optical surface on the optical axis, and the number of optical surfaces from the human eye 5 (diaphragm) The distance (T) between each optical surface and the next optical surface on the optical axis of the display screen 4, and even-order aspheric coefficients ⁇ 2 , ⁇ 3 , ⁇ 4 .
  • the aspheric coefficient can satisfy the following equation:
  • z is the coordinate along the optical axis
  • Y is the radial coordinate in units of lens length
  • C is the curvature (1/R)
  • K is the cone coefficient (Coin Constant)
  • ⁇ i is the height
  • the coefficient of the second term, 2i is the order of Aspherical Coefficient (the order of Aspherical Coefficient).
  • the smoothness of field curvature is considered, and the spherical coefficient of no high-order term is up to 4th order.
  • the maximum spot size is the maximum field of view 1.0F, and its maximum value is ⁇ 72 ⁇ m;
  • the RGB wavelengths of field curvature in the T&S direction are all less than 0.5mm, and the maximum distortion is ⁇ 38.3% at the maximum field of view;
  • the maximum dispersion of RGB is the maximum position of the field of view, the entire RGB is 450nm to 610nm, and the LCA is 246.8 ⁇ m.
  • the weight of the first lens 1 is 2.62g
  • the weight of the second lens 2 is 2.96g
  • the weight of the third lens 3 is 4.1g
  • the weight of the three lenses The total weight is 9.68g.
  • Embodiment 2 provides an optical system, and Table 2 is used to show the structural parameters in the optical system.
  • the optical system can be shown in FIG. 6 .
  • Table 2 lists the optical surface number (Surface) numbered sequentially from the human eye 5 (diaphragm) to the display screen 1, the curvature (C) of each optical surface on the optical axis, and the number of optical surfaces from the human eye 5 (diaphragm) The distance (T) between each optical surface and the next optical surface on the optical axis of the display screen 1, and even-order aspheric coefficients ⁇ 2 , ⁇ 3 , ⁇ 4 .
  • the maximum spot size is the maximum field of view 1.0F, and its maximum value is less than 80 ⁇ m.
  • the RGB wavelengths of field curvature in the T&S direction are all less than 1.5mm, and the maximum distortion is ⁇ 40% at the maximum field of view;
  • the maximum dispersion of RGB is the maximum position of the field of view, the entire RGB is 450nm to 630nm, and the LCA is 265nm.
  • the weight of the first lens 1 is: 2.39g, the weight of the second lens 2 is 3.9g; the weight of the third lens 3 is 4.26g, and the weight of the three lenses The total weight is 10.89g.
  • the embodiment of this application provides a short-focus, high-definition through-type optical system, which does not involve folding optical paths:
  • a head-mounted display device is provided.
  • the head-mounted display device includes any one of the optical systems described above.
  • the head-mounted display device is, for example, a VR device.

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Abstract

一种光学系统以及头戴显示设备；其中，光学系统包括沿入射光的传播方向依次设置的第三透镜(3)、第二透镜(2)和第一透镜(1)；光学系统中有三个菲涅尔面，其中有两个菲涅尔面为相邻设置；第三透镜(3)的光焦度为正；光学系统的视场角≥100度。提供了一种短焦、高光效、大FOV的光学结构设计方案，光学系统可应用于头戴显示设备中。

Description

光学系统以及头戴显示设备
本申请要求于2021年11月30日提交中国专利局、申请号为202111445295.X、发明名称为“光学系统以及头戴显示设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光学成像技术领域，更具体地，本申请涉及一种光学系统以及头戴显示设备。
背景技术
近年来，增强现实(Augmented Reality，AR)技术及虚拟现实(Virtual Reality，VR)技术等在智能穿戴设备中得到了应用，并快速发展起来。增强现实技术和虚拟现实技术的核心部件均是显示光学系统。因此，显示光学系统显示效果的好坏将直接决定着智能穿戴设备的质量。
在现有的相关技术中，以VR设备为例。在目前的VR设备中，若基于1.4inch的显示屏幕实现大视场角(FOV)和短光学总长(TTL)，常规的光学方案为折叠光路结构，但却存在制作成本较高、光效低(＜25％)且存在鬼影的问题。
发明内容
本申请的目的在于提供的一种光学系统以及头戴显示设备的新技术方案。
根据本申请的一个方面，提供了一种光学系统。所述光学系统包括沿入射光的传播方向依次设置的第三透镜、第二透镜和第一透镜；
所述光学系统中有三个菲涅尔面，其中有两个菲涅尔面为相邻设置；
所述第三透镜的光焦度为正；
所述光学系统的视场角≥100度。
可选地，所述第一透镜和所述第二透镜的光焦度均为正；
所述第一透镜、所述第二透镜及所述第三透镜位于同一光轴上。
可选地，所述第一透镜和所述第二透镜相邻的两个面为菲涅尔面。
可选地，所述第一透镜包括第一表面和第二表面，所述第二透镜包括第三表面和第四表面；
所述第二表面与所述第三表面为相邻设置，均为菲涅尔面；
所述第一表面和所述第四表面均为非球面。
可选地，所述第三透镜包括第五表面和第六表面；
所述第五表面和所述第六表面中的一个为菲涅尔面，所述第五表面和所述第六表面中的另一个为非球面；
所述第三透镜的菲涅尔面与所述第二透镜的第四表面为相邻设置。
可选地，所述第一透镜与所述第二透镜之间设置有第一间隔T1，所述第一间隔T1设置为0.2mm≤T1≤1mm。
可选地，所述第二透镜与所述第三透镜之间设置有第二间隔T2，所述第二间隔T2设置为1mm≤T1≤3mm。
可选地，所述第一透镜的有效焦距f1为：30mm≤f1≤40mm；
所述第二透镜的有效焦距f2为：40mm≤f2≤460mm；
所述第三透镜的有效焦距f3为：65mm≤f3≤115mm。
可选地，所述第一透镜、所述第二透镜和所述第三透镜的材质为COP材料、OKP材料、EP材料或者PMMA材料。
根据本申请的另一个方面，提供了一种头戴显示设备。所述头戴显示设备包括如上任一种所述的光学系统。
本申请的有益效果在于：
本申请实施例提供了一种直透式光学结构设计方案，其中采用了三片光学镜片，并在光路结构中设计了三个菲涅尔面，既可以提供较强的汇聚能力，从而减少光学系统的光学总长TTL和增大视场角FOV，又可以使得光学系统的光效在较高的水平；其中有两个菲涅尔面为相邻设置，有助于降低杂散光。本申请实施例提供的方案实现了短焦、高光效、大FOV的光学设计要求，所形成的光学系统可应用于例如头戴显示设备(如，VR设备)中，还有助于实现头戴显示设备的小型化、轻量化发展趋势。
通过以下参照附图对本申请的示例性实施例的详细描述，本申请的其它 特征及其优点将会变得清楚。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一部分附图，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据提供的附图获得其他的附图。
图1是本申请实施例提供的光学系统的结构示意图；
图2是本申请实施例提供的光学系统的成像原理示意图；
图3是本申请实施例1提供的光学系统的点列图；
图4是本申请实施例1提供的光学系统的场曲和畸变图；
图5是本申请实施例1提供的光学系统的色散图；
图6是本申请实施例2提供的光学系统的成像原理示意图；
图7是本申请实施例2提供的光学系统的点列图；
图8是本申请实施例2提供的光学系统的场曲和畸变图；
图9是本申请实施例2提供的光学系统的色散图。
附图标记说明：
1、第一透镜；2、第二透镜；3、第三透镜；4、显示屏幕；5、人眼；
11、第一表面；12、第二表面；
21、第三表面；22、第四表面；
31、第五表面；32、第六表面。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本申请及其应用或使用的任何限制。
对于相关领域普通技术人员已知的技术、方法和设备可能不作详细 讨论，但在适当情况下，所述技术、方法和设备应当被视为说明书的一部分。
在这里示出和讨论的所有例子中，任何具体值应被解释为仅仅是示例性的，而不是作为限制。因此，示例性实施例的其它例子可以具有不同的值。
应注意到：相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步讨论。
下面结合附图1至图9对本申请实施例提供的光学系统以及头戴显示设备进行详细地描述。
根据本申请实施例的一个方面，提供了一种光学系统。所述光学系统为一种短焦、高光效、大FOV的直透式光学结构方案，其适合应用于电子设备中，例如头戴显示设备(head mounted display，HMD)，如VR设备(如VR眼镜或者VR头盔等)。其具有良好的应用前景。
本申请实施例提供的一种光学系统，如图1和图2所示，其包括沿入射光的传播方向依次设置的第三透镜3、第二透镜2和第一透镜1；
所述光学系统中有三个菲涅尔面，其中有两个菲涅尔面为相邻设置；
所述第三透镜3的光焦度为正；
所述光学系统的视场角≥100度。
本申请实施例提供的光学系统，其为直透式光路结构设计，光路结构较为简单，使得其制作较为容易。
需要说明的是，所述光学系统还可以包括显示屏幕(display)4。
所述显示屏幕4在光路结构中可用于发射光线，即为光学系统提供入射光。
也就是说，在本申请实施例提供的光学系统方案中，设计应用一个透镜组合，该透镜组合例如包括有三片光学镜片，如图1和图2所示，将这一透镜组合布设在如显示屏幕4的出光侧位置，其具体位于显示屏幕4发射出的入射光的传播方向上，其能够用于将所述入射光投射到人眼5中进行成像，从而实现光学系统的成像功能。
如图1和图2所示，本申请实施例提供的光学系统，基于三个光学透镜的搭配组合，即所述第一透镜1、所述第二透镜2及所述第三透镜3的搭配组合，且这三个透镜的面型组合均设计为菲涅尔面+非球面，光路结构中的三个菲涅尔面能够提供较大的光焦度(focal power)和实现超短焦，且两个菲涅尔面相邻设置的搭配有助于降低杂散光。并且，通过合理设置所述第三透镜3的面型，有助于实现高解析及低色散。
需要说明的是，在本申请实施例提供的方案中，所述第一透镜1、所述第二透镜2及所述第三透镜3的菲涅尔面包括但不限于平面基底。
也就是说，所述第一透镜1、所述第二透镜2及所述第三透镜3的菲涅尔面还可以是曲面基底，本领域技术人员可以根据具体情况调整菲涅尔面的基底形式，本申请在此不作具体限定。当采用曲面基底时，可以使透镜更加轻薄。
本申请实施例提供了一种直透式光学结构设计方案，其中采用了三片光学镜片，并在光路结构中设计了三个菲涅尔面，既可以提供较强的汇聚能力，从而减少光学系统的光学总长TTL和增大视场角FOV，又可以使得光学系统的光效在较高的水平；其中，两个菲涅尔面为相邻设置，这一设计有助于降低杂散光。
本申请实施例提供的方案实现了短焦、高光效、大FOV的光学设计要求，形成的光学系统可应用于例如头戴显示设备(如，VR设备)中，还有助于实现头戴显示设备的小型化、轻量化发展趋势。
综合比较，本申请实施例提供的光路设计方案克服了现有单片式透镜+显示屏幕(display)的方案带来的透镜距离显示屏较远，导致VR设备的尺寸较大，不利于产品的小型化的问题。
与此同时，还能够改善采用折叠光路带来的缺陷问题。折叠光路方案存在成本高、光效低及鬼影等缺点。本申请实施例提供的方案采用的是直透式光学方案，既可以提供较强的汇聚能力(focal power，光焦度)，从而减少光学系统的光学总长TTL和加大光学系统的视场角FOV，又可以提高光效，使得光效处在较高的水平。
例如，如图1和图2所示，在所述光学系统中设置有一显示屏幕4， 该显示屏幕4例如为1.4inch Display，实现了100度视场角。在此基础上，常规的单片式透镜(1P)结构或者双片式透镜(2P)结构均不足以分辨该类型的显示屏幕。究其原因在于：
单片式透镜(1P)仅存在两个表面的面型自由度的优化，其汇聚能力有限，而且像差或者色差无法校正，全视场可分辨的像素大小(光斑尺寸spot size)约为80μm～100μm，而更重要的是无法达到短焦的目的。
双片式透镜(2P)虽然增加了透镜表面面型优化的自由度，可实现短焦，但仍存在解析力的限制，其全视场可分辨的像素大小(光斑尺寸spot size)约为60μm～80μm。
本申请实施例中采用的光学镜片组合结构，能够进一步提升解析力，并能够在一定程度上校正色差，所形成的是一种直透式的短焦光路结构。其中，配合采用三个菲涅尔面能够提供较大的光焦度，而近显示屏幕4侧的所述第三透镜3可用来进行消色差处理，有助于提高成像质量。
此外，需要说明的是，在本申请实施例提供的光学系统中并不限于仅设置三个菲涅尔面。所述光学系统还可以包括更多个透镜，在光路结构中设置更多个菲涅尔面，本领域技术人员可以根据具体情况灵活进行调整。
在本申请的一些例子中，所述第一透镜1和所述第二透镜2的光焦度均为正；所述第一透镜1、所述第二透镜2及所述第三透镜3位于同一光轴上。
本申请实施例中提供的三个透镜均设计为正透镜。
如图2所示，所述显示屏幕4发射出的光线作为入射光在经所述第三透镜3(正透镜)之后进入至所述第二透镜2(正透镜)内，入射光经所述第二透镜2之后进行汇聚，再进入所述第一透镜1，所述第一透镜1仍为汇聚的正透镜，经所述第一透镜1的入射光传输后进入人眼5进行成像。整个光路结构中并不涉及光路折叠方案，为直透式光路结构。
在本申请的一些例子中，如图1和图2所示，所述第一透镜1和所述第二透镜2相邻的两个面为菲涅尔面。在所述光学系统中采用该设计有助于减少杂散光。
在本申请的一些例子中，如图1和图2所示，所述第一透镜1包括第 一表面11和第二表面12，所述第二透镜2包括第三表面21和第四表面22；
所述第二表面12与所述第三表面21为相邻设置，均为菲涅尔面；
所述第一表面11和所述第四表面22均为非球面。
在本申请实施例提供的光学系统中，如图1和图2所示，所述第一透镜1的第一表面11直接面向人眼5，其是位于外部的，所述第一表面11例如设置为非球面(进一步地，所述第一表面11为凸面)；所述第一透镜1的第二表面12设置为菲涅尔面，这样，所述第一透镜1(正透镜)就形成了非球面+菲涅尔面的两种面型组合形式。
可选的是，在所述第一透镜1的第一表面11和第二表面12上分别镀有增透膜(Anti-Reflective coating，AR)。
在所述第一透镜1的两个表面上分别镀有增透膜之后，可通所述增透膜来减少反射光，以此来增加光线在所述第一透镜1两个表面上的透过率。
可选的是，在所述第一透镜1的第一表面11上除了镀有所述增透膜之外，在所述第一表面11上还可以镀上硬化膜。
这是因为：所述第一透镜1的第一表面11是面向外部的，其需要避免划伤、碰伤等损伤，通过镀上所述硬化膜之后就能够提高所述第一透镜1的使用寿命。在所述第一表面11上镀硬化膜，即对所述第一表面11进行硬化处理，以此就能够提高所述第一表面11的硬度、强度等。这对于提高整个光学系统的使用寿命是有利的。
当然，本申请实施例中并不限于在所述第一透镜1的第一表面11上镀硬化膜，还可以在所述第一透镜1的第二表面12上镀有硬化膜，本领域技术人员可以根据具体需要灵活调整，本申请在此不做具体限制。
此外，本申请实施例中，所述第一透镜1还具有如下参数。
在本申请的一些例子中，所述第一透镜1的第一表面11的半径R 1的绝对值满足：50mm≤Abs(R 1)≤80mm；所述第一透镜1的第二表面12的半径R 2的绝对值满足：25mm≤Abs(R 2)≤30mm；所述第一表面11和所述第二表面12的圆锥系数K 1的绝对值满足：Abs(K 1)≤10。
其中，所述第一表面11与所述第二表面12的面型设计不同。
具体地，朝向外的所述第一表面11被设计为非球面(例如凸面)，而所述第二表面12被设计为菲涅尔面，利用菲涅尔面和非球面组合形成的第一透镜1应用于光路结构中有助于实现短焦、高分辨的效果。
本申请的实施例中，在对所述第一透镜1的面型优化之后，考虑到加工难度及成本，更为优选的是，将所述第一透镜1的圆锥系数(Coin Constant)，即K 1值例如设计在[-10，10]，并且，所述第一透镜2的菲涅尔面的半径R>23mm。
在本申请的一些例子中，所述第二透镜2与所述第一透镜1的面型组合形式可以是相同的，二者之间保持较窄的空气间隔。
例如，所述第二透镜2的第三表面21为菲涅尔面，所述第二透镜2的第四表面22设置为非球面(进一步地，所述第四表面11也为凸面)。
所述第二透镜2也为正透镜，其位于所述第一透镜1与所述第三透镜3之间，所述第二透镜2更加靠近所述第一透镜1设置。
可选的是，所述第二透镜2的第三表面21和第四表面22上镀有增透膜(Anti-Reflective coating，AR)。通过所述增透膜来减少反射光，以此来增加光线在所述第二透镜2两个表面上的透过率。
此外，本申请实施例中，所述第二透镜2还具有如下参数。
在本申请的一些例子中，所述第二透镜2的第二表面21的半径R 3的绝对值满足：25mm≤Abs(R 3)≤30mm；所述第二透镜2的第三表面22的半径R 4的绝对值满足：Abs(R 4)≥120mm；所述第三表面21和所述第四表面22的圆锥系数K 2的绝对值满足：Abs(K 2)≤10。
本申请的实施例中，在对所述第二透镜2的面型优化之后，考虑到加工难度及成本，更为优选的是，将所述第二透镜2的圆锥系数(Coin Constant)，即K 2值设计在[-10，10]，并且所述第二透镜2的菲涅尔面的半径>23mm。
在本申请的一些例子中，如图1和图2所示，所述第三透镜3包括第五表面31和第六表面32；所述第五表面31和所述第六表面32中的一个为菲涅尔面，所述第五表面31和所述第六表面32中的另一个为非球面；所述第三透镜3的菲涅尔面与所述第二透镜2的第四表面22为相邻设置。
进一步地，所述第五表面31设置为菲涅尔面，所述第六表面32设置为凹面。这样，在整个光路结构中，与所述第二透镜2的第四表面22相邻的面为菲涅尔面，而与所述显示屏幕4相邻的面为凹面。所述第三透镜3在整个光路结构中可用以进行消色差。
可选的是，在所述第五表面31和所述第六表面32上均镀有增透膜(Anti-Reflective coating，AR)。
在所述第三透镜3的两个表面上分别镀有增透膜之后，可通所述增透膜来减少反射光，以此来增加光线在所述第三透镜3两个表面上的透过率。
本申请的方案中，对光学系统进行了优化设计，其中利用所述第一透镜1和所述第二透镜2的两个菲涅尔面+非球面(凸面)，结合所述第三透镜3的菲涅尔面+非球面(凹面)的组合，很好地实现了短焦、高光效、低色散和大FOV的特点。
此外，本申请实施例中，所述第三透镜3还具有如下参数。
在本申请的一些例子中，所述第三透镜3的第五表面31的半径R 5的绝对值满足：30mm≤Abs(R 5)≤50mm；所述第三透镜3的第六表面32的半径R 6的绝对值满足：110mm≤Abs(R 6)≤170mm；所述第五表面31和所述第六表面32的圆锥系数K 3的绝对值满足：Abs(K 3)≤10。
本申请的实施例中，在对所述第三透镜3的面型优化之后，考虑到加工难度及成本，更为优选的是，将所述第三透镜3的圆锥系数(Coin Constant)，即K 2值设计在[-10，10]，并且所述第三透镜3的菲涅尔面的半径>23mm。
需要说明的是，在本申请的实施例中，所述第一透镜1、所述第二透镜2和所述第三透镜3均具有菲涅尔面。考虑到镜片面型的加工，因而需要将面型参数设定到某一范围内，否则会出现加工精度低或者断刀风险(这是因为齿形加工困难大，齿形的锐角越小，加工的倾角和动作越困难)。也正因为如此，设定圆锥系数K值较为优选地范围为[-10，10]，且各透镜的菲涅尔面的R值在23mm以上。
在本申请实施例提供的光学系统方案中，所述第一透镜1和所述第二透镜2均为利用非球面(凸面)+菲涅尔面组合的方式，所述第三透镜3 为非球面(凹面)+菲涅尔面组合的方式，再基于不同折射率&阿贝数材料选择及配合，就能够实现光路结构的低色散及高解析。
在本申请实施例提供的光学系统方案中，所述光学系统包括有显示屏幕4，以及所述第一透镜1、所述第二透镜2和所述第三透镜3；其中，所述显示屏幕4作为显示光源，其可以发出光线，该光线可作为入射光进入各透镜中；所述第一透镜1和所述第二透镜2均为正透镜，且二者为凸面+菲涅尔面的面型组合形式，所述第三透镜3也为正透镜，其为菲涅尔面+凹面。在这三个透镜的各表面均进行了镀增透膜处理，还对所述第一透镜1的第一表面11进行了硬化膜加硬+增透膜处理。在此基础上，如图2所示：
所述显示屏幕4发射出的入射光经过镀有增透膜的所述第三透镜3的第六表面31(凹面)进入到所述第三透镜3内部，经所述第三透镜3的传递光线再进入到所述第二透镜2，所述第二透镜2的两个表面也均镀有增透膜，这样，入射光经所述第二透镜2后进行汇聚，然后进入至所述第一透镜1，所述第一透镜1仍为汇聚的正透镜，经所述第一透镜1的光线传输后，再进入到人眼5进行成像。整个光学系统中并无光路折叠，且各透镜的表面均镀有增透膜，光线传递效率高。
在本申请的一些例子中，所述第一透镜1与所述第二透镜2之间设置有第一间隔T 1，所述第一间隔T 1设置为0.2mm≤T 1≤1mm。
在本申请的一些例子中，所述第二透镜2与所述第三透镜3之间设置有第二间隔T 2，所述第二间隔T 2设置为1mm≤T 1≤3mm。
本申请实施例提供的方案中，所述第一透镜1与所述第二透镜2之间设置为较窄尺寸的空气间隔；同时，所述第二透镜2与所述第三透镜3之间也设置了较窄的空气间隔。本申请的方案中通过对各透镜之间空气间隔的优化设计，这有助于实现整个光学系统的小型化。
此外，在所述光学系统中若还设置有显示屏幕4，则各透镜的间距在经过合理布置之后，还需要考虑所述第三透镜3与所述显示屏幕4之间的间隔尺寸。
其中，所述第三透镜3是靠近所述显示屏幕4一侧设置的。
例如，所述第三透镜3与所述显示屏幕4之间设置有第三间隔T 3。
可选的是，所述第三间隔T 3设置为5mm≤T 2≤15mm。
在本申请的一些例子中，所述第一透镜1的有效焦距f 1为：30mm≤f 1≤40mm；
所述第二透镜2的有效焦距f 2为：40mm≤f 2≤460mm；
所述第三透镜3的有效焦距f 3为：65mm≤f 3≤115mm。
在本申请的方案中设计，所述第一透镜1、所述第二透镜2和所述第三透镜3均具有菲涅尔面、，可以提供较大的光焦度，使光学系统具有短焦的特点。
本申请提供的是一种短焦光学系统。整个光学系统中并无光路折叠，是一种直透式的光学系统，能够实现高清成像。
在本申请的一些例子中，所述第一透镜1的中心厚度值h 1为：2mm≤h 1≤4mm；所述第二透镜2的中心厚度h 2为：3mm≤h 2≤5mm；所述第三透镜3的中心厚度h 3为：2mm≤h 3≤4mm。
各透镜的厚度不会过厚，这也有利于降低整个光路结构的重量。
在本申请的一些例子中，所述第一透镜1、所述第二透镜2和所述第三透镜3的材质为COP材料、OKP材料、EP材料或者PMMA材料。
本申请的方案中，对于各透镜(即所述第一透镜1、所述第二透镜2及所述第三透镜3)，在材料选择上，基于短焦和色差的考虑，选择高折射率及高低阿贝数的材料组合进行优化设计。
本申请提供的是一种短焦光学系统。整个光学系统中并无光路折叠，是一种直透式的光学系统，能够实现高清成像。
以下为本申请实施例提供的方案的一个应用实例：
(1)配合1.4inch显示屏幕4实现了100度视场角。
(2)畸变小于38.3％，场曲小于1.1mm。
(3)色差小于236um。虚像距离为1500mm.。
(4)光学系统的spot size＜73um，实现可见光波段(450nm～630nm)清晰成像。整个光学系统的有效焦距为17mm。
实施例1
实施例1提供了一种光学系统，采用表1示出光学系统中的结构参数。
表1中分别列出由人眼5(光阑)到显示屏幕4依序编号的光学面号码(Surface)、在光轴上各光学面的曲率(C)、从人眼5(光阑)到显示屏幕4的光轴上各光学面与后一光学面的距离(T)，及偶次非球面系数α 2、α 3、α 4。
其中，非球面系数可以满足如下的方程：
Figure PCTCN2021140023-appb-000001
式(1)中：z是沿光轴方向的坐标，Y为以透镜长度单位为单位的径向坐标，C是曲率(1/R)，K为圆锥系数(Coin Constant)，αi是各高次项的系数，2i是非球面的高次方(the order of Aspherical Coefficient)，本申请的方案设计中考虑到场曲的平缓，无高次项球面系数至4阶。
表1
Surf Type Radius Thickness GLASS Clear Diam Mech Diam Conic 4th
OBJ STANDARD Infinity -1500   3575.261 3575.261 0  
STO STANDARD Infinity 12   4 4 0  
2 EVENASPH 78.1965 3.000 K26R 34.685 37.308 -10.000 -1.0463E-05
3 FRESNELS -25.99979 0.540   37.308 37.308 -0.052 -8.3559E-06
4 FRESNELS 25.99979 3.186 K26R 37.692 37.692 0.040 1.4948E-05
5 EVENASPH -139.9991 0.500   36.233 36.233 -9.992 3.8032E-06
6 FRESNELS 45.1666 2.998 OKP-1 34.997 34.997 -10.000 -7.6959E-06
7 EVENASPH 112.1967 11.921   31.724 31.724 9.712 1.2888E-05
8 STANDARD Infinity 0.450 BK7 25.547 25.547 0.000  
9 STANDARD Infinity 0.095   25.367 25.547 0.000  
IMA STANDARD Infinity     25.139 25.139 0.000  
通过如下参数反应实施例1提供的光学系统的性能好坏：
如图3所示，spot size最大处为最大视场1.0F，其最大值＜72μm；
如图4所示，T&S方向场曲RGB波长均小于0.5mm，最大畸变为最大视场处＜38.3％；
如图5所示，RGB最大色散为视场最大位置，整个RGB 450nm～610nm，LCA为246.8μm。
在实施例1提供的光学系统中，所述第一透镜1的重量为：2.62g，所述第二透镜2的重量为2.96g；所述第三透镜3的重量为4.1g，三个透镜的总 重量为9.68g。
实施例2
实施例2提供了一种光学系统，采用表2示出光学系统中的结构参数。
该光学系统可如图6所示。
表2中分别列出由人眼5(光阑)到显示屏幕1依序编号的光学面号码(Surface)、在光轴上各光学面的曲率(C)、从人眼5(光阑)到显示屏幕1的光轴上各光学面与后一光学面的距离(T)，及偶次非球面系数α 2、α 3、α 4。
表2
Figure PCTCN2021140023-appb-000002
通过如下参数反应实施例2的光学系统的性能好坏：
如图7所示，spot size最大处为最大视场1.0F，其最大值小于80μm。
如图8所示，T&S方向场曲RGB波长均小于1.5mm，最大畸变为最大视场处＜40％；
如图9所示，RGB最大色散为视场最大位置，整个RGB 450nm～630nm，LCA为265nm。
在实施例2提供的光学系统中，所述第一透镜1的重量为：2.39g，所述第二透镜2的重量为3.9g；所述第三透镜3的重量为4.26g，三个透镜的总重量为10.89g。
本申请实施例提供了一种短焦、高清晰的直透式光学系统，其中并 不涉及折叠光路：
(1)在整个光路结构中通过三个菲涅尔镜面的搭配实现了超短焦；
(2)在整个光路结构中设置三个菲涅尔面，并使两个菲涅尔面相邻设置，这一方面有助于减低杂散光，另一方面可减少镜片的口径进而减轻重量；
(3)对光学系统进行了优化，利用所述第三透镜，它是凹面+菲涅尔面两种面型组合作为靠近所述显示屏幕4的光学元件，有助于实现高解析和低色散的特点；
(4)通过不同透镜材料的选择即通过不同折射率和阿贝数的选择及配合，实现了光路结构的低色散。
根据本申请的另一个方面，提供了一种头戴显示设备。
所述头戴显示设备包括如上任一种所述的光学系统。
所述头戴显示设备例如为VR设备。
上文实施例中重点描述的是各个实施例之间的不同，各个实施例之间不同的优化特征只要不矛盾，均可以组合形成更优的实施例，考虑到行文简洁，在此则不再赘述。
虽然已经通过例子对本申请的一些特定实施例进行了详细说明，但是本领域的技术人员应该理解，以上例子仅是为了进行说明，而不是为了限制本申请的范围。本领域的技术人员应该理解，可在不脱离本申请的范围和精神的情况下，对以上实施例进行修改。本申请的范围由所附权利要求来限定。

Claims (10)

  1. 一种光学系统，其特征在于，包括沿入射光的传播方向依次设置的第三透镜(3)、第二透镜(2)和第一透镜(1)；
    所述光学系统中有三个菲涅尔面，其中有两个菲涅尔面为相邻设置；
    所述第三透镜(3)的光焦度为正；
    所述光学系统的视场角≥100度。
  2. 根据权利要求1所述的光学系统，其特征在于，所述第一透镜(1)和所述第二透镜(2)的光焦度均为正；
    所述第一透镜(1)、所述第二透镜(2)及所述第三透镜(3)位于同一光轴上。
  3. 根据权利要求1所述的光学系统，其特征在于，所述第一透镜(1)和所述第二透镜(2)相邻的两个面为菲涅尔面。
  4. 根据权利要求3所述的光学系统，其特征在于，所述第一透镜(1)包括第一表面(11)和第二表面(12)，所述第二透镜(2)包括第三表面(21)和第四表面(22)；
    所述第二表面(12)与所述第三表面(21)为相邻设置，均为菲涅尔面；
    所述第一表面(11)和所述第四表面(22)均为非球面。
  5. 根据权利要求4所述的光学系统，其特征在于，所述第三透镜(3)包括第五表面(31)和第六表面(32)；
    所述第五表面(31)和所述第六表面(32)中的一个为菲涅尔面，所述第五表面(31)和所述第六表面(32)中的另一个为非球面；
    所述第三透镜(3)的菲涅尔面与所述第二透镜(2)的第四表面(22)为相邻设置。
  6. 根据权利要求1所述的光学系统，其特征在于，所述第一透镜(1)与所述第二透镜(2)之间设置有第一间隔T1，所述第一间隔T1设置为0.2mm ≤T1≤1mm。
  7. 根据权利要求1所述的光学系统，其特征在于，所述第二透镜(2)与所述第三透镜(3)之间设置有第二间隔T2，所述第二间隔T2设置为1mm≤T1≤3mm。
  8. 根据权利要求1所述的光学系统，其特征在于，所述第一透镜(1)的有效焦距f1为：30mm≤f1≤40mm；
    所述第二透镜(2)的有效焦距f2为：40mm≤f2≤460mm；
    所述第三透镜(3)的有效焦距f3为：65mm≤f3≤115mm。
  9. 根据权利要求1所述的光学系统，其特征在于，所述第一透镜(1)、所述第二透镜(2)和所述第三透镜(3)的材质为COP材料、OKP材料、EP材料或者PMMA材料。
  10. 一种头戴显示设备，其特征在于：包括：
    如权利要求1-9中任意一项所述的光学系统。
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