WO2018121010A1

WO2018121010A1 - Projection objective and three-dimensional display device

Info

Publication number: WO2018121010A1
Application number: PCT/CN2017/106805
Authority: WO
Inventors: 赵改娜; 浦东林; 黄文彬; 乔文; 陈林森
Original assignee: 苏州苏大维格光电科技股份有限公司; 苏州大学
Priority date: 2016-12-30
Filing date: 2017-10-19
Publication date: 2018-07-05
Also published as: CN106646885A; CN106646885B

Abstract

Provided is a large visual field projection objective, comprising a light-splitting device (1), a relay lens group (2) and a light-splitting assembly (3). The relay lens group (2) includes: a non-spherical lens group and a piece of nano lens (24). In an optical system, introducing the nano lens (21) provided with a diffraction face, and replacing a bi-cemented lens with the nano lens (24) may reduce the weight of the system. The three-dimensional display device, especially a near-to-eye three-dimensional display device, which is constructed by cooperatively using the projection objective with a DMD, LCD or LCOS display device and a corresponding illumination light source and collecting light beams reflected by the display device at the position of an exit pupil (4), wherein the exit pupil (4) is outside a projection structure and matches a subsequent nano waveguide lens, has the features of displaying a large visual field, a high image quality and a high light utilisation efficiency.

Description

Projection objective lens and three-dimensional display device

The present application claims priority to Chinese Patent Application Serial No. No. No. No. No. No. No. No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No

Technical field

The present invention relates to the field of display device technologies, and more particularly to a projection objective lens and a three-dimensional display device.

Background technique

Augmented Reality (AR) technology is a new technology that integrates real world information and virtual world information "seamlessly". It is an entity information (visual information, which is difficult to experience in a certain time and space of the real world. Sound, taste, touch, etc., through computer and other science and technology, simulation and then superimposition, the virtual information is applied to the real world, perceived by human senses, thus achieving a sensory experience beyond reality. The real environment and virtual objects are superimposed in real time on the same picture or space.

The optical system of augmented reality (AR) technology is an image magnifying system. The image generated by the microdisplay is magnified by the optical system to present an enlarged virtual image at a certain distance in front of the human eye, so that the user can completely immerse in the virtual situation. , not subject to interference from outside information. If a 3D video signal is input, 3D stereoscopic display can be directly realized without other auxiliary devices.

With the development of semiconductor technology, for example, digital micro-mirror devices (DMDs), liquid crystal display panels (LCD panels), and silicon crystal chips (Lcos chips) are being miniaturized while increasing pixels, miniaturizing the helmet display. Providing conditions, the AR optical system is gradually moving toward a large field of view, high resolution, Low weight and small size development. The projection system is an important part of the helmet display. The projection system design not only affects the quality of the image display, but also affects the size and weight of the helmet display, as well as the comfort level of the observer, which determines the viewer's visual experience.

U.S. Patent No. 2014/0211322 A1 proposes a projection optical system in which the diameter of the reflective plano-convex lens 238 is large in the case of a large field of view, resulting in an increase in volume of the entire optical system. As shown in Figure 1.

Based on this, a miniaturized, large field of view, high pixel projection lens and its three-dimensional display device are urgently needed.

Summary of the invention

In view of this, the present invention provides a miniaturized, large field of view, high pixel projection objective and a three-dimensional display device thereof.

In order to achieve the above object, the technical solution of the present invention is as follows:

A projection objective includes a beam splitting device, a relay lens group, and a beam splitting assembly, and the beam splitting assembly includes a positive lens in an exit pupil direction. The positive lens is used to collimate light.

The projection objective lens designed by the invention is used in combination with a DMD, LCD or LCOS display device and a corresponding illumination source to collect the reflected light beam of the display device at the exit pupil, outside the projection structure, and the subsequent converging nanolens waveguide lens. The matched and constructed three-dimensional display device, especially the near-eye three-dimensional display device, has the characteristics of displaying a large field of view, high image quality, and high light utilization efficiency.

Preferably, the positive lens of the beam splitting component in the exit pupil direction is a plano-convex lens.

Preferably, the relay lens group comprises:

An aspherical lens group using aspherical aberration correction;

And/or comprising at least one nanolens provided as a diffractive surface.

The invention introduces a diffractive surface nanolens in an optical system, and replaces the achromatic aberration with a nano lens. The double-glued lens can both achromatic and greatly reduce the weight of the system.

Preferably, the exit pupil of the projection objective is located outside the positive lens for collimating light.

Preferably, the relay lens group is sequentially disposed in the direction of light propagation: a first positive lens, a second positive lens, a first negative lens, a nano lens, a third positive lens, and a second negative lens.

Preferably, the first positive lens is a convex lens whose both faces are aspherical, the second positive lens is a convex lens whose both faces are aspherical, and the first negative lens has a concave surface on both faces. The lens of the third positive lens is a lens having two convex surfaces, and the second negative lens is a concave lens whose both concave surfaces are aspherical.

Preferably, the nanolens is a lens engraved with a grating structure having a radius from a small to a large concentric shape on one or both sides.

Preferably, the diffractive surface of the nanolens is disposed near a conjugate plane of the exit pupil of the projection objective.

Preferably, the beam splitting component sequentially includes a light splitting prism, a reflective lens, and a positive lens for collimating light, respectively, in order from the light propagation direction.

Preferably, the spectroscopic surface of the dichroic prism is a semi-reverse semi-transparent surface; the reflective lens is glued on the dichroic prism; the convex surface of the reflective lens is plated with a reflective film that reflects incident light back to the dichroic prism; and is used for collimating light. The positive lens is glued to the face of the beam splitting prism near the exit pupil.

Preferably, the convex surface of the reflective lens is aspherical.

Preferably, the projection objective lens is sequentially disposed along the direction of light propagation: a light splitting device, a relay lens group, and a beam splitting component; and the relay lens group is sequentially disposed along the direction of light propagation: a first positive lens and a second positive lens a first negative lens, a nano lens, a third positive lens, and a second negative lens, wherein the first positive lens is a convex lens having aspherical surfaces on both sides, and the second positive lens is aspherical on both faces a convex lens, wherein the first negative lens is a lens having two concave surfaces, and the third positive lens is convex for both surfaces The second negative lens is a concave lens in which both concave surfaces are aspherical.

The aspherical correction aberration and the nano-lens correction system chromatic aberration are used in the relay lens group to ensure the image quality under large field of view conditions.

Preferably, the diffractive surface of the nanolens is disposed near the conjugate plane of the exit pupil of the projection objective.

Preferably, the shape of the first positive lens, the second positive lens and the second negative lens containing an aspherical surface is obtained by the following polynomial:

Where Z represents the distance of the point on the aspheric surface from the aspherical vertex in the direction of the optical axis; r represents the distance from the point on the aspheric surface to the optical axis; c represents the central curvature of the aspheric surface; k represents the cone rate; a4, a6, a8 A10 represents the aspherical high-order coefficient.

Preferably, the order of the beam splitting lens from the direction of light propagation includes:

A beam splitting prism, a reflective lens, a positive lens for collimating light.

Preferably, the exit pupil of the projection objective is located outside of the positive lens for collimating light. Preferably, the projection objective of the projection objective is provided with a nano-waveguide lens.

The present invention also provides a three-dimensional display device comprising the projection objective lens of any of the above, and an image information generating device.

Preferably, the image information generating device comprises a DMD, an LCD or an LCOS display device, and an illumination source.

DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the technical description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention. Other drawings may also be obtained from those of ordinary skill in the art in light of the inventive work.

1 is a schematic structural view of a prior art;

2 is a schematic structural view of a projection objective lens of the present invention;

Figure 3 is a schematic view of a nanolens

4-6 are aberration curves observed for a wavelength of 459 nm, a wavelength of 525 nm, and a wavelength of 618 nm, respectively.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

A projection objective comprises a beam splitting device, a relay lens group and a beam splitting component, wherein the beam splitting component is provided with a positive lens in a direction of exit and exit. The positive lens is used to collimate light.

The present invention provides a positive lens in the exit pupil direction, preferably a plano-convex lens, which can greatly expand the viewing angle range.

The relay lens group includes:

An aspherical lens group using aspherical aberration correction;

In the relay lens group, at least one nanolens provided with a diffractive surface may be used instead of the double-adhesive lens for achromatization, the nano-lens is a lens with a small to large concentric circular grating structure engraved on one or both sides, such as Figure 3 shows the addition of a nanolens. It is also possible to replace the relevant lens assembly with more nanolenses, both to correct system chromatic aberration and to greatly reduce the weight of the relay lens group.

The invention introduces a diffractive surface nano lens provided in the optical system, and replaces the double cemented lens for achromatic use with the nano lens, which can greatly reduce the weight of the system. The projection objective lens designed by the invention is used in combination with a DMD, LCD or LCOS display device and a corresponding illumination source to collect the reflected light beam of the display device at the exit pupil, outside the projection structure, and the subsequent converging nanolens waveguide lens. The matched and constructed three-dimensional display device has the characteristics of displaying a large field of view, high image quality, and high light utilization efficiency.

As shown in FIG. 2, in some embodiments, the display device 5, the spectroscopic device 1, the relay lens group 2 and the beam splitting assembly 3 are sequentially arranged in the direction of beam propagation, and the image information beam (light) is used when constructing the three-dimensional display device. It is emitted by the display device 5 (image information generating device), and after passing through the spectroscopic device 1 (generally, a dichroic prism), is concentrated by the relay lens group 2 to be imaged near the spectroscopic surface of the dichroic prism 31 of the spectroscopic component 3, and then by the spectroscopic component. 3 After collimation, it is concentrated from the exit pupil 4 into the subsequent nano-waveguide lens or other three-dimensional display assembly, and finally the nano-lens waveguide lens or other three-dimensional display component converges the image information in the space in the human eye or in front of the human eye. Magnified virtual 3D image.

In the embodiment of the present invention, the selection of each parameter is determined according to requirements. For example, the parameters of the projection objective lens may be: a large field of view of 60°, a display device size of 0.37 inches, f=8.6 mm, and a size of 4 mm. 5 mm behind the positive lens 33.

The display device 5 according to the embodiment of the present invention may be in various modes of DMD, LCD or LCOS, and the illumination mode of the display device 5 may be LED, OLED or laser multiple illumination modes; the light splitting device 1 may be a beam splitting prism, A variety of spectroscopic methods such as polarizing prisms or semi-reflex lens sheets.

In some embodiments, the projection objective lenses are respectively disposed in the order of the direction in which the light is transmitted, including the light splitting device 1, the relay lens group 2, and the light splitting component 3; and the relay lens group 2 is sequentially disposed in the direction of the light propagation: first a positive lens 21, a second positive lens 22, a first negative lens 23, a nanolens 24, a third positive lens 25, and a second negative lens 26, wherein the first positive lens 21 is a convex lens whose both surfaces are aspherical. The second positive lens 22 is a convex lens whose both faces are aspherical, and the first negative lens 23 is a lens whose both faces are concave, and the nano lens 24 is engraved on one side or both sides from small to small A lens having a large concentric circular grating structure, the third positive lens 25 is a lens having two convex surfaces, and the second negative lens 26 is a concave lens having two concave surfaces which are all aspherical.

The aspherical correction aberration and the nanolens correction system chromatic aberration are used in the relay lens group to ensure the image quality under large field of view conditions, and the use of the nanolens 24 is due to the unique negative dispersion characteristics of the nanolens 24 as a diffractive optical element. The nanolens 24 provided with a diffractive surface is introduced into the optical system, and the use of the nanolens 24 instead of the double-adhesive lens for achromatic can greatly reduce the weight of the system. In the relay lens group, the diffractive surface of the nanolens 24 is in the vicinity of the conjugate plane of the exit pupil, and the conjugate manner can reduce the aperture of the lens in the optical path, thereby reducing the aberration and facilitating aberration correction.

In order to reduce the cost, at least one plastic lens may be included in the relay lens assembly 2, and other lenses are made of a glass material in order to ensure good image quality.

Preferably, the shape of the aspherical surface contained in the first positive lens 21, the second positive lens 22, and the second negative lens 26 can be obtained by the following polynomial:

Where Z represents the distance of the point on the aspheric surface from the aspherical vertex in the direction of the optical axis; r represents the aspheric surface The distance from the point to the optical axis; c indicates the central curvature of the aspheric surface; k indicates the conicity; a4, a6, a8, and a10 indicate the aspherical higher order coefficient.

In some embodiments, the beam splitting assembly 3 according to the embodiment of the present invention includes a beam splitting prism 31, a reflecting lens 32, a positive lens 33 for collimating light rays, and a light splitting surface of the beam splitting prism 31. The reflective lens 32 is glued to the dichroic prism 31; the convex surface of the reflective plano-convex lens 32 is aspherical, and the convex surface of the reflective lens 32 is plated with a reflective film for reflecting incident light back to the dichroic prism 31; The positive lens 33 of the collimated light is glued to the surface of the dichroic prism 31 near the exit pupil.

After passing through the splitting lens assembly 3, the light is collimated and exits through the exit pupil 4, matching the subsequent nano-guided lenses. The use of the retroreflective lens 32 effectively reduces the projection height in the subsequent optical path by using the reflective surface, thereby reducing the aperture of the lens, and is also advantageous for reducing aberrations.

The exit pupil 4 of the embodiment of the present invention is located 5 mm behind the positive lens 33, and the exit pupil size is 4 mm. The exit pupil 4 is located outside the projection objective lens structure, and has the advantage of matching with the subsequent nano-waveguide lens, thereby effectively improving the utilization efficiency of the light energy. .

The projection objective lens of the present embodiment has aberrations, field curvatures, and distortions as shown in FIGS. 4 to 6, respectively. 4 to 6 are aberration aberration curves observed for a wavelength of 459 nm, a wavelength of 525 nm, and a wavelength of 618 nm, respectively. As seen in Figure 4, the vertical axis of the projection objective is less than 5 microns. The curves T and S in Fig. 5 are the tangential fidelity curve and the sagittal field curvature characteristic curve, respectively. It can be seen that the meridional curvature value and the sagittal field curvature value are controlled within the range of (-0.25 mm, 0.25 mm), and the curve dis is the distortion characteristic curve. As can be seen from Fig. 5, the distortion variable is controlled at (-1%, 1%). ) within the scope. It can be seen from Fig. 6 that the full field optical transfer function MTF > 40% at a spatial frequency of 601 p/mm. It can be seen that the aberration, field curvature and distortion of the projection objective can be controlled (corrected) in a small range.

Preferably, the projection objective of the projection objective is provided with a nano-waveguide lens.

The above-mentioned projection objective lens and the three-dimensional display device constructed by the same, in particular, a large field of view near-eye display device coupled with near-eye display, have the following characteristics:

1) Adding a nanolens with a diffractive surface, using the combination of a diffractive hybrid system and a mirror, increasing the degree of freedom in the optical design process can break through many limitations of the conventional optical system, improving the imaging quality and reducing the system volume and weight. It has the unparalleled advantages of traditional optical systems in terms of optimizing system center of gravity and reducing costs. The nanolens waveguide lens can be added to one piece, and two, three or even more pieces can be added as needed.

2) The use of the positive lens 33 advantageously reduces the aperture of the retroreflective lens 32 in the case of a large field of view, thereby reducing the overall optical path volume, and collimating the optical path using the beam splitting prism group 3, accurately, through the positive lens 33 After that, the emitted light becomes collimated light, and the collimation of the optical path is achieved.

3) In the dichroic prism 31, there is an intermediate image in which the display device 5 generates an image (located at a position indicated by reference numeral 6 in Fig. 2), which facilitates reduction of the overall volume of the optical path in the case of a large field of view.

4) The projection objective is placed outside the projection objective to facilitate the matching with the subsequent nano-waveguide lens, and the expansion and optimization of the image quality by utilizing the overall optical path.

The various embodiments in the present specification are described in a progressive manner, and each embodiment focuses on differences from other embodiments, and similar parts between the various embodiments may be referred to each other. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments are obvious to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, The present invention is not to be limited to the embodiments shown herein, but is to be accorded to the broadest scope of the principles and novel features disclosed herein.

Claims

A projection objective includes a beam splitting device, a relay lens group, and a beam splitting assembly, wherein the beam splitting assembly includes a positive lens in an exit pupil direction.
The projection objective according to claim 1, wherein the positive lens of the beam splitting assembly in the exit pupil direction is a plano-convex lens.
The projection objective according to claim 1, wherein the relay lens group comprises:

An aspherical lens group using aspherical aberration correction;

And/or comprising at least one nanolens provided as a diffractive surface.
The projection objective according to claim 1, wherein the exit pupil of the projection objective is located outside the positive lens.
The projection objective according to claim 3, wherein the relay lens group is sequentially disposed in the direction of light propagation: a first positive lens, a second positive lens, a first negative lens, a nano lens, and a third positive Lens, second negative lens.
The projection objective lens according to claim 5, wherein the first positive lens is a convex lens whose both faces are aspherical, and the second positive lens is a convex lens whose both faces are aspherical, The first negative lens is a lens whose both faces are concave, the third positive lens is a lens whose both faces are convex, and the second negative lens is a concave lens whose both concave surfaces are aspherical.
The projection objective according to claim 5, wherein the nanolens is a lens having a grating structure with a radius from a small to a large concentric shape on one or both sides.
The projection objective according to claim 5, wherein the diffractive surface of the nanolens is disposed near a conjugate plane of the exit pupil of the projection objective.
The projection objective according to any one of claims 1 to 8, wherein the spectroscopic component is transmitted from a light source The order of orientation includes: a dichroic prism, a reflective lens, and a positive lens for collimating light.
The projection objective according to claim 9, wherein the spectroscopic surface of the dichroic prism is a transflective surface; the reflective lens is glued to the dichroic prism; and the convex surface of the reflective lens is plated to reflect incident light back to the spectroscopic light. A reflective film of a prism; a positive lens for collimating light is glued to a face of the beam splitting prism near the exit pupil.
The projection objective according to claim 10, wherein the convex surface of the reflecting lens is aspherical.
A three-dimensional display device comprising the projection objective lens according to any one of claims 1 to 8, and image information generating means.