CN109283774B - Projection lens and projection system - Google Patents
Projection lens and projection system Download PDFInfo
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- CN109283774B CN109283774B CN201811332925.0A CN201811332925A CN109283774B CN 109283774 B CN109283774 B CN 109283774B CN 201811332925 A CN201811332925 A CN 201811332925A CN 109283774 B CN109283774 B CN 109283774B
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- 230000010287 polarization Effects 0.000 claims abstract description 72
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- 238000005286 illumination Methods 0.000 claims abstract description 58
- 238000003384 imaging method Methods 0.000 abstract description 14
- 238000010586 diagram Methods 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 6
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Classifications
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/142—Adjusting of projection optics
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/20—Lamp housings
- G03B21/206—Control of light source other than position or intensity
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/20—Lamp housings
- G03B21/2066—Reflectors in illumination beam
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/20—Lamp housings
- G03B21/2073—Polarisers in the lamp house
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Projection Apparatus (AREA)
- Lenses (AREA)
Abstract
The embodiment of the invention relates to the technical field of optical projection, and discloses a projection lens and a projection system. Wherein, this projection lens includes: a guide display element group for converting an illumination beam incident from a first direction into a projection beam and emitting it toward a second direction; a lens element group for receiving and transmitting the projection beam outputted from the guide display element group; a set of reflective optical elements comprising: the lens comprises a lens element group, a first polarization splitting element, a quarter wave plate and a curved surface reflecting mirror, wherein the first polarization splitting element is arranged on the light emitting side of the lens element group, the quarter wave plate and the curved surface reflecting mirror are arranged on one side of the first polarization splitting element, and the quarter wave plate is arranged between the first polarization splitting element and the curved surface reflecting mirror. In this way, the present embodiment can reduce the optical overall length of the device and ensure that the imaging quality such as a large viewing angle is satisfied.
Description
Technical Field
The embodiment of the invention relates to the technical field of optical projection, in particular to a projection lens and a projection system.
Background
In recent years, near-eye display technologies such as augmented reality technology have been rapidly developed, for example, microsoft holonens (a kind of holographic computer device not limited by cables), sony's holographic perspective technology glasses, and the like. The augmented reality near-to-eye display technology is a technology for imaging a light field in a real space and can realize interaction between a virtual world and the real world.
At present, a scheme for realizing the augmented reality technology through an optical waveguide is widely applied, and the scheme can reduce the volume and the weight of equipment and realize the directional conduction of light rays.
The inventors of the present invention found in the process of implementing the embodiments of the present invention: the current waveguide projection lens or other near-eye display device needs to meet the imaging requirements of a large viewing angle, and the conventional method is to meet the imaging quality of the large viewing angle by increasing the number of lenses and other modes, so that the optical total length of the device is increased, and the miniaturization of the lens is not facilitated.
Disclosure of Invention
The technical problem to be solved by the embodiment of the invention is to provide a projection lens and a projection system, which can reduce the optical total length of the device and ensure that the imaging quality such as a large visual angle is met. In order to solve the technical problems, one technical scheme adopted by the embodiment of the invention is as follows: a projection lens is provided, including a guide display element group for converting an illumination beam incident from a first direction into a projection beam and emitting the projection beam toward a second direction; a lens element group, the central optical axis of which coincides with the second direction, for receiving and transmitting the projection beam output by the guide display element group; a set of reflective optical elements comprising: the device comprises a lens element group, a first polarization splitting element, a quarter wave plate and a curved mirror, wherein the first polarization splitting element is arranged on the light emergent side of the lens element group; the first polarization splitting element is used for reflecting first polarized light of the projection light beam, the quarter wave plate is used for enabling the first polarized light to generate additional optical path difference, the curved mirror is used for reflecting the first polarized light output by the quarter wave plate back to the quarter wave plate, the quarter wave plate is also used for enabling the first polarized light reflected by the curved mirror to generate additional optical path difference so as to be converted into second polarized light of the projection light beam, and the first polarization splitting element is also used for transmitting the second polarized light so as to enable the second polarized light to be emitted towards a third direction.
Optionally, the reflective optical element group further comprises: a converging lens; the converging lens is arranged on one side of the first polarization splitting element far away from the quarter wave plate, and is used for receiving the second polarized light output by the first polarization splitting element and converging the second polarized light so that the converged second polarized light is emitted towards the third direction.
Optionally, the reflective optical element group further comprises: and the diaphragm is arranged on the light emitting side of the converging lens.
Optionally, the setting directions of the diaphragm, the converging lens, the quarter wave plate and the curved reflector are perpendicular to the light emergent direction of the lens element group; the central optical axes of the diaphragm, the converging lens, the quarter wave plate and the curved reflector coincide and are perpendicular to the central optical axis of the lens element group.
Optionally, the quarter wave plate, the curved mirror and the first polarization splitting element are glued.
Optionally, the guiding display element group includes: a first display chip and a prism; the prism is used for receiving and transmitting the illumination light beam so as to enable the illumination light beam to be output to the first display chip; the first display chip is used for converting the illumination light beam output by the prism into the projection light beam and outputting the projection light beam to the prism; the prism is also used for reflecting the projection light beam output by the first display chip so as to enable the projection light beam to be emitted towards the second direction.
Optionally, the guiding display element group includes: a second display chip and a second polarization splitting element; the second polarization splitting element is used for receiving and transmitting part of the illumination light beam so as to enable the illumination light beam to be output to the second display chip; the second display chip is used for converting part of the illumination light beams output by the second polarization splitting element into projection light beams and outputting the projection light beams to the second polarization splitting element; the second polarization splitting element is further configured to reflect the projection beam output by the second display chip, so that the projection beam exits toward the second direction.
Optionally, the lens element group includes: a first lens, a second lens, and a third lens; the first lens, the second lens, and the third lens are sequentially arranged along a central optical axis of the lens element group in a direction from the guide display element group to the reflective optical element group; the focal lengths of the first lens, the second lens, the third lens and the projection lens satisfy: 0.8< |F 1/F|<1.3,0.5<|F2/F| <1.0; wherein F 1 is a focal length of the first lens, F 2 is a focal length of the second lens and the third lens after combination, and F is a focal length of the projection lens.
Optionally, an included angle between the first direction and the second direction is greater than 0 ° and less than or equal to 90 °, and the second direction is perpendicular to the third direction.
In order to solve the technical problems, another technical scheme adopted by the embodiment of the invention is as follows: a projection system is provided, including an illumination device and the projection lens described above, where the illumination device is configured to provide an illumination beam for the projection lens.
The embodiment of the invention has the beneficial effects that: in contrast to the situation in the prior art, the embodiment of the invention provides a projection lens, which converts an illumination beam incident along a first direction into a projection beam by guiding a display element group and emits the projection beam along a second direction, and emits the projection beam transmitted along the second direction along a third direction by reflecting an optical element group, so that the optical total length of the device can be reduced, and the imaging quality such as a large viewing angle can be ensured.
Drawings
One or more implementations are illustrated by the accompanying drawings, which are not intended to be limiting of the embodiments, wherein elements having the same reference number designation are designated by like elements, and wherein the drawings do not constitute a limitation to scale unless specifically stated otherwise.
Fig. 1 is a schematic structural diagram of a projection lens according to an embodiment of the invention;
FIG. 2 is a schematic diagram of another structure of a reflective optical element group of the projection lens of FIG. 1;
fig. 3a is a schematic structural diagram of a projection lens according to another embodiment of the present invention;
FIG. 3b is a schematic view of another structure of the lens element set of the projection lens of FIG. 3 a;
fig. 4 is a schematic structural diagram of a projection system according to an embodiment of the present invention.
Detailed Description
In order that the invention may be readily understood, a more particular description thereof will be rendered by reference to specific embodiments that are illustrated in the appended drawings. It will be understood that when an element is referred to as being "fixed" to another element, it can be directly on the other element or one or more intervening elements may be present therebetween. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present therebetween. The terms "vertical," "horizontal," "left," "right," "upper," "lower," "inner," "outer," "bottom," and the like as used in this specification are based on the orientation or positional relationship shown in the drawings, merely to facilitate description of the invention and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used in this specification includes any and all combinations of one or more of the associated listed items.
In addition, the technical features mentioned in the different embodiments of the invention described below can be combined with one another as long as they do not conflict with one another.
The projection lens in the embodiment of the invention can reduce the optical total length of the device and ensure that the imaging quality such as a large visual angle is met by changing the direction of the light beam.
The projection lens in the embodiment of the invention can be applied to the projection system in the embodiment to reduce the volume of the projection system.
Specifically, a projection lens and a projection system will be explained below by way of examples.
Example 1
Fig. 1 is a schematic structural diagram of a projection lens according to an embodiment of the invention. As shown in fig. 1, projection lens 100 includes a guide display element group 110, a lens element group 120, and a reflective optical element group 130.
The lens element group 120 is disposed between the guiding display element group 110 and the reflecting optical element group 130, the guiding display element group 110 is used for converting an illumination beam incident from a first direction into a projection beam and making the projection beam emergent towards a second direction, the lens element group 120 is used for receiving and transmitting the projection beam output by the guiding display element group 110, and the reflecting optical element group 130 is used for making the projection beam emergent from a third direction, and by the above way, the direction of the beam is changed, thereby reducing the optical total length of the device.
The guiding display element group 110 may be a module composed of a display chip capable of converting an illumination beam into a projection beam and an optical element capable of changing the propagation direction of the beam.
Specifically, referring to fig. 1, the guidance display device set 110 includes: a first display chip 111 and a prism 112. The first display chip 111 may be a DMD display chip capable of digitally modulating light to convert an illumination beam into a projection beam. The first display chip 111 is used for converting the illumination beam output from the prism 112 into a projection beam and outputting the projection beam to the prism 112. Prism 112 may be a right angle triangular prism capable of transmitting and reflecting light. The prism 112 is used for receiving and transmitting the illumination beam so as to output the illumination beam to the first display chip 111; the prism 112 is further configured to reflect the projection beam output by the first display chip 111, so that the projection beam exits in the second direction.
In this embodiment, the first display chip 111 is disposed on one side of one right-angle surface (the right-angle surface is a side surface formed by right-angle edges) of the prism 112, the lens element group 120 is disposed on one side of the other right-angle surface of the prism 112, the illumination beam is incident from the first direction toward the inclined surface of the prism 112, the prism 112 transmits the illumination beam so as to output the illumination beam to the first display chip 111, the first display chip 111 converts the illumination beam output by the prism 112 into a projection beam and outputs the projection beam to the inclined surface of the prism 112, and the prism 112 reflects the projection beam so as to make the projection beam exit toward the second direction.
Wherein, the inclined surface of the prism 112 is provided with a transmissive film near the first display chip 111 to transmit the illumination beam. The inclined surface of the prism 112 is provided with a reflective film near the first display chip 111 to reflect the projection beam.
Wherein, when the illumination beam is incident on the inclined surface of the prism 112 along the first direction, the incident angle is an acute angle. When the inclined surface of the prism 112 reflects the projection beam, the reflection angle is 90 °. By the above mode, the included angle between the first direction of incidence of the illumination light beam and the second direction of emergence of the projection light beam is more than 0 DEG and less than 90 deg. And, the normal angle phi between the first direction and the working surface of the first display chip 111 is twice the deflection angle of the small mirror in the first display chip 111, and the range of the angle phi is 24-34 degrees.
The lens element group 120 may include a plurality of optical lenses for diverging and/or converging the projection beam, thereby shortening the optical total length of the projection lens 100 and securing the imaging quality of the projection lens 100. The central optical axis of the lens element group 120 coincides with the second direction, and the lens element group 120 is configured to receive and transmit the projection beam outputted from the guiding display element group 110.
Specifically, the lens element group 120 includes a first lens 121, a second lens 122, and a third lens 123. The first lens 121, the second lens 122 and the third lens 123 may be made of glass or plastic materials, the light incident surfaces of the first lens 121, the second lens 122 and the third lens 123 may be spherical or aspherical, and the light emergent surfaces of the first lens 121, the second lens 122 and the third lens 123 may be spherical or aspherical. The first lens 121, the second lens 122, and the third lens 123 are sequentially arranged along the central optical axis of the lens element group 120 in a direction from the guide display element group 110 to the reflective optical element group 130, and the central optical axes of the first lens 121, the second lens 122, and the third lens 123 coincide such that the projection light beam exiting the guide display element group 110 sequentially passes through the first lens 121, the second lens 122, and the third lens 123 in the second direction.
Wherein the focal lengths of the first lens 121, the second lens 122, and the third lens 123 and the projection lens 100 satisfy: 0.8< |F 1/F|<1.3,0.5<|F2/F| <1.0; wherein F 1 is the focal length of the first lens 121, F 2 is the focal length of the second lens 122 and the third lens 133, and F is the focal length of the projection lens 100. For example, F 1、F2, F meets 0.81< |F 1/F|<1.2,0.6<|F2/F| <0.9; for another example, F 1、F2, F satisfies 0.82< |F 1/F|<1.1,0.51<|F2/F| <0.9. By the above mode, the optical total length of the projection lens 100 can be advantageously shortened, miniaturization of the module is realized, and the imaging quality of the projection lens 100 is ensured.
The reflective optical element group 130 is disposed on a side of the lens element group 120 away from the guiding display element group 110, and the reflective optical element group 130 makes the projection beam output by the lens element group 120 exit from the third direction to change the direction of the beam, thereby reducing the total optical length of the projection lens 100. Wherein the third direction is perpendicular to the second direction.
Specifically, referring back to fig. 1, the reflective optical element group 130 includes: a first polarization splitting element 131, a quarter-wave plate 132, a curved mirror 133, a converging lens 134, and a diaphragm 135. The first polarization splitting element 131 is disposed on the light emitting side of the lens element group 120 (i.e., the side of the third lens 123 away from the guiding display element group 110), the quarter-wave plate 132 and the curved mirror 133 are disposed on the side of the first polarization splitting element 131, the quarter-wave plate 132 is disposed between the first polarization splitting element 131 and the curved mirror 133, the converging lens 134 is disposed on the side of the first polarization splitting element 131 away from the quarter-wave plate 132, and the diaphragm 135 is disposed on the light emitting side of the converging lens 134 (i.e., the side of the converging lens 134 away from the first polarization splitting element 131).
Wherein, the setting direction of the diaphragm 135, the converging lens 134, the quarter wave plate 132 and the curved mirror 133 is perpendicular to the light emitting direction of the lens element group 120; the central optical axes of the stop 135, the converging lens 134, the quarter wave plate 132, and the curved mirror 133 coincide and are perpendicular to the central optical axis of the lens element group 120.
The quarter wave plate 132, the curved mirror 133 and the first polarization splitting element 131 are glued, so that the structure of the projection lens 100 is more compact, and the width of the projection lens 100 is reduced. Specifically, one side of the quarter-wave plate 132 is glued to the first polarization splitting element 131, and the other side of the quarter-wave plate 132 is glued to the edge of the concave surface of the curved mirror 133.
The light incident surface of the first polarization splitting element 131 and the light emergent surface of the third lens 123 may be connected without a gap, or glued, so as to further reduce the length and size of the lens on the premise of meeting the requirement of the optical path.
Referring to fig. 1 again, the first polarization splitting element 131 is a polarization splitting prism, which is formed by gluing a pair of high-precision right-angle prisms, wherein a polarizing splitting film is plated on an inclined plane of one prism, so that the polarization splitting prism can split an incident unpolarized natural light beam into two perpendicular linearly polarized light beams, one of the linearly polarized light beams completely passes through, the other polarized light beam is reflected at an angle of 45 °, and the emergent directions of the two linearly polarized light beams are 90 °. In this embodiment, the first polarization splitting element 131 is configured to split the projection beam into a first polarized light and a second polarized light, and transmit the second polarized light of the projection beam, so that the second polarized light exits along the second direction, and reflect the first polarized light of the projection beam, so that the first polarized light enters the quarter wave plate 132; the first polarization splitting element 131 is further configured to transmit the second polarized light, so that the second polarized light exits toward the third direction.
Alternatively, when the first polarization splitting element 131 is a polarization splitting prism, the external working surface of the polarization splitting prism may be a plane or a curved surface, and when the working surface is a curved surface, convergence compensation may be further performed on the light beam.
Alternatively, in other embodiments, as shown in fig. 2, the first polarization splitting element 131 may also be a polarizer disposed at an angle of 45 ° to the second direction, and capable of splitting an incident unpolarized natural light beam into two perpendicular linearly polarized light beams, one of which passes completely and the other of which is masked. The polarizing plate may be a polarizer or other crystal as long as it can convert natural light into polarized light. In this embodiment, the first polarization splitting element 131 is configured to split the projection beam into a first polarized light and a second polarized light, shield the second polarized light of the projection beam, and reflect the first polarized light of the projection beam so that the first polarized light is incident on the quarter wave plate 132; the first polarization splitting element 131 is further configured to transmit the second polarized light, so that the second polarized light exits toward the third direction.
It should be noted that, the first polarized light of the projection beam may be longitudinal light or transverse light, and the second polarized light of the projection beam may be longitudinal light or transverse light, which may be selected according to practical situations. When the first polarized light of the projection beam is longitudinal light, the second polarized light of the projection beam is transverse light; when the first polarized light of the projection beam is transverse light, the second polarized light of the projection beam is longitudinal light.
The quarter wave plate 132 is a birefringent single crystal plate with a certain thickness, and can generate lambda/4 additional optical path difference for the passing light. In this embodiment, the quarter wave plate 132 is used to generate an additional optical path difference for the first polarized light reflected by the first polarization splitting element 131, and the quarter wave plate 132 is also used to generate an additional optical path difference for the first polarized light reflected by the curved mirror 133, so as to convert the first polarized light into the second polarized light of the projection beam. For example, if the first polarized light is transverse light, the first polarized light is converted into second polarized light (i.e., longitudinal light) after passing through the quarter wave plate 132 twice. Alternatively, when the angle between the incident vibration plane of the first polarized light incident on the quarter wave plate 132 and the optical axis of the quarter wave plate 132 is 45 °, the first polarized light passes through the quarter wave plate 132 for the first time and becomes circularly polarized light, and the first polarized light passes through the quarter wave plate 132 again and becomes linearly polarized light from circularly polarized light, so that the polarization state of the first polarized light can be changed as required.
The curved mirror 133 is configured to reflect the first polarized light output by the quarter wave plate 132 back to the quarter wave plate 132, so that the first polarized light passes through the quarter wave plate 132 again. By providing the curved mirror 133, the beam direction is changed, thereby reducing the optical total length of the device, and increasing the angle of view, and ensuring the imaging quality.
Alternatively, in some other embodiments, curved mirror 133 may be replaced with a curved reflective prism.
Wherein the focal length of the converging lens 134 is positive, the converging lens 134 is located between the first polarization splitting element 131 and the diaphragm 135. In the present embodiment, the converging lens 134 is configured to receive the second polarized light output by the first polarization splitting element 131, and converge the second polarized light so as to be emitted in the third direction. Wherein the second direction is perpendicular to the third direction.
The aperture 135 is a field aperture, and can limit the size of a field (imaging range). In the present embodiment, the diaphragm 135 is used to adjust the field size of the image of the second polarized light output from the condenser lens 134.
Alternatively, in some other embodiments, the converging lens 134 may be omitted when the converging beam is not required.
Alternatively, in some other embodiments, the diaphragm 135 may be omitted when the field of view size does not need to be adjusted.
In this embodiment, the working process of the projection lens 100 is approximately as follows: the illumination beam incident from the first direction is transmitted to the first display chip 111 through the prism 112, the first display chip 111 converts the illumination beam into a projection beam and outputs the projection beam onto the inclined plane reflection surface of the prism 112, the prism 112 reflects the projection beam so that the projection beam enters the lens element group 120 in the second direction, the lens element group 120 transmits the processed projection beam, the first polarization splitting element 131 receives the projection beam output by the lens element group 120, splits the projection beam into first polarized light and second polarized light, transmits the second polarized light, reflects the first polarized light, the quarter wave plate 132 causes the first polarized light reflected by the first polarization splitting element 131 to generate an additional optical path difference and outputs the additional optical path difference to the curved mirror 133, the curved mirror 133 reflects the first polarized light back to the quarter wave plate 132, the first polarized light again passes through the quarter wave plate 132 and is converted into the second polarized light, the second polarized light is incident to the converging lens 134, the converging lens 134 converges the second polarized light, and the converged second polarized light passes through the diaphragm and then exits 135 in the third direction. In the above manner, the propagation direction of the projection beam propagating in the second direction is changed to be emitted in the third direction, thereby reducing the optical total length of the device.
In the present embodiment, the projection lens 100 converts an illumination beam incident in a first direction into a projection beam by guiding the display element group 110 and emits the projection beam in a second direction, and emits the projection beam transmitted in the second direction in a third direction by the reflection optical element group 130, so that the optical total length of the device can be reduced and the satisfaction of imaging quality such as a large viewing angle can be ensured.
Example two
Fig. 3a is a schematic structural diagram of a projection lens according to another embodiment of the invention. As shown in fig. 3a, the difference from the first embodiment is that the guide display element group 110 includes: a second display chip 113 and a second polarization splitting element 114.
The second display chip 113 is an LCOS display chip, and the second display chip 113 is configured to convert a part of the illumination beam output by the second polarization beam splitter 114 into first polarized light of the projection beam, and output the first polarized light to the second polarization beam splitter 114.
The second polarization splitting element 114 is a polarization splitting prism, which is formed by gluing a pair of high-precision right-angle prisms, wherein a polarizing splitting film is plated on the inclined surface of one prism, so that the polarization splitting prism can split an incident unpolarized natural light beam into two perpendicular linearly polarized light beams, one polarized light beam completely passes through, and the other polarized light beam is reflected. The second polarization splitting element 114 is configured to receive and transmit a portion of the illumination beam, so as to output the illumination beam to the second display chip 113; the second polarization splitting element 114 is further configured to reflect the projection beam output by the second display chip 113, so that the projection beam exits in the second direction.
The illumination beam is incident to the polarization beam splitter prism along the first direction, and the included angle between the illumination beam and the light splitting surface of the polarization beam splitter prism is 45 degrees, so that the included angle between the first direction in which the illumination beam is incident and the second direction in which the projection beam is emergent is equal to 90 degrees, and the direction of the projection beam output by the projection lens 100 is parallel and opposite to the direction of the incident illumination beam (i.e., the first direction is parallel and opposite to the third direction).
Alternatively, as shown in fig. 3b, the second polarization splitting element 114 may also be a polarizer disposed at an angle of 45 ° to the second direction, and capable of splitting an incident unpolarized natural light beam into two perpendicular linearly polarized light beams, one of which passes completely and the other of which is masked.
In this embodiment, the working process of the projection lens 100 is approximately as follows: after the illumination beam incident from the first direction passes through the second polarization splitting element 114, part of the polarized light of the illumination beam is transmitted to the second display chip 113, another part of the polarized light of the illumination beam is reflected, the second display chip 113 converts part of the illumination beam into a projection beam and outputs the projection beam onto the polarization splitting surface of the second polarization splitting element 114, the second polarization splitting element 114 reflects the projection beam so that the projection beam enters the lens element group 120 in the second direction, the lens element group 120 transmits the processed projection beam, the first polarization splitting element 131 receives the projection beam output by the lens element group 120, splits the projection beam into the first polarized light and the second polarized light, and transmits the second polarized light, reflects the first polarized light, the quarter wave plate 132 causes the first polarized light reflected by the first polarization splitting element 131 to generate an additional optical path difference and output to the curved mirror 133, the curved mirror 133 reflects the first polarized light back to the quarter wave plate 132, the first polarized light passes through the quarter wave plate 132 again and is converted into the second polarized light, the second polarized light is incident on the converging lens element group 120, the converging lens 134, the second polarized light is converged lens 135, and the third polarized light passes through the third polarization stop after the converging lens 135. In the above manner, the propagation direction of the projection beam propagating in the second direction is changed to be emitted in the third direction, thereby reducing the optical total length of the device.
In the present embodiment, the projection lens 100 converts an illumination beam incident in a first direction into a projection beam by guiding the display element group 110 and emits the projection beam in a second direction, and emits the projection beam transmitted in the second direction in a third direction by the reflection optical element group 130, so that the optical total length of the device can be reduced and the satisfaction of imaging quality such as a large viewing angle can be ensured.
Example III
Fig. 4 is a schematic structural diagram of a projection system according to an embodiment of the invention. As shown in fig. 4, the projection system 200 includes an illumination device 210 and the projection lens 100 in the first or second embodiment. The illumination device 210 is used to provide an illumination beam for the projection lens 100.
In this embodiment, an implementation is taken as an example for illustration.
The illumination device 210 may be a laser light source, such as a fiber coupled laser light source, a diode laser light source, or a solid state laser light source, among others. The illumination device 210 may include a red laser light source, a green laser light source, and a blue laser light source, and by using the three primary color lasers, the illumination device 210 can make the projection lens 100 most truly reproduce the color rich and gorgeous in the objective world, and provide more shocking expressive force.
The relative position of the illumination device 210 and the projection lens 100 may be determined by the incident direction (i.e., the first direction) of the illumination beam, for example, if the first direction and the second direction form an acute angle, the illumination device 210 is disposed on the inclined surface side of the prism 112.
In the present embodiment, the projection system 200 is advantageous for miniaturization of the lens by providing the projection lens 100 with a smaller total optical length, so that the device size of the entire projection system 200 is smaller without affecting the imaging quality.
It should be noted that while the present invention has been illustrated in the drawings and described in the specification in connection with the preferred embodiments thereof, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but are provided to provide a more thorough understanding of the present invention. The above-described features are continuously combined with each other to form various embodiments not listed above, and are considered to be the scope of the present invention described in the specification; further, modifications and variations of the present invention may be apparent to those skilled in the art in light of the foregoing teachings, and all such modifications and variations are intended to be included within the scope of this invention as defined in the appended claims.
Claims (9)
1. A projection lens, comprising:
A guide display element group for converting an illumination beam incident from a first direction into a projection beam and emitting the projection beam toward a second direction;
A lens element group, the central optical axis of which coincides with the second direction, for receiving and transmitting the projection beam output by the guide display element group;
A set of reflective optical elements comprising: the device comprises a lens element group, a first polarization splitting element, a quarter wave plate and a curved mirror, wherein the first polarization splitting element is arranged on the light emergent side of the lens element group; the first polarization splitting element is used for reflecting first polarized light of the projection light beam, the quarter wave plate is used for enabling the first polarized light to generate additional optical path difference, the curved mirror is used for reflecting the first polarized light output by the quarter wave plate back to the quarter wave plate, the quarter wave plate is also used for enabling the first polarized light reflected by the curved mirror to generate additional optical path difference so as to be converted into second polarized light of the projection light beam, and the first polarization splitting element is also used for transmitting the second polarized light so as to enable the second polarized light to be emitted towards a third direction;
The guiding display element group comprises a first display chip or a second display chip, wherein the first display chip is a DMD display chip, and the second display chip is an LCOS display chip;
The lens element group includes: a first lens, a second lens, and a third lens; the first lens, the second lens, and the third lens are sequentially arranged along a central optical axis of the lens element group in a direction from the guide display element group to the reflective optical element group, and focal lengths of the first lens, the second lens, the third lens, and the projection lens satisfy:
0.8<|F1/F|<1.3，
0.5<|F2/F|<1.0；
Wherein F 1 is a focal length of the first lens, F 2 is a focal length of the second lens and the third lens after combination, and F is a focal length of the projection lens.
2. The projection lens of claim 1 wherein the set of reflective optical elements further comprises: a converging lens;
The converging lens is arranged on one side of the first polarization splitting element far away from the quarter wave plate, and is used for receiving the second polarized light output by the first polarization splitting element and converging the second polarized light so that the converged second polarized light is emitted towards the third direction.
3. The projection lens of claim 2 wherein the set of reflective optical elements further comprises: and the diaphragm is arranged on the light emitting side of the converging lens.
4. A projection lens according to claim 3, wherein,
The setting directions of the diaphragm, the converging lens, the quarter wave plate and the curved reflector are perpendicular to the light emergent direction of the lens element group;
the central optical axes of the diaphragm, the converging lens, the quarter wave plate and the curved reflector coincide and are perpendicular to the central optical axis of the lens element group.
5. The projection lens of claim 1 wherein the quarter wave plate, the curved mirror and the first polarization splitting element are glued.
6. The projection lens of claim 1 wherein the set of guide display elements comprises: the first display chip and the prism;
The prism is used for receiving and transmitting the illumination light beam so as to enable the illumination light beam to be output to the first display chip;
The first display chip is used for converting the illumination light beam output by the prism into the projection light beam and outputting the projection light beam to the prism;
the prism is also used for reflecting the projection light beam output by the first display chip so as to enable the projection light beam to be emitted towards the second direction.
7. The projection lens of claim 1 wherein the set of guide display elements comprises: the second display chip and the second polarization beam splitting element;
the second polarization splitting element is used for receiving and transmitting part of the illumination light beam so as to enable the illumination light beam to be output to the second display chip;
The second display chip is used for converting part of the illumination light beams output by the second polarization splitting element into projection light beams and outputting the projection light beams to the second polarization splitting element;
the second polarization splitting element is further configured to reflect the projection beam output by the second display chip, so that the projection beam exits toward the second direction.
8. The projection lens of any of claims 1-7 wherein,
The included angle between the first direction and the second direction is larger than 0 degrees and smaller than or equal to 90 degrees, and the second direction is perpendicular to the third direction.
9. A projection system comprising an illumination device for providing an illumination beam to the projection lens and the projection lens of any of claims 1-7.
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| US20210021743A1 (en) * | 2019-07-19 | 2021-01-21 | Htc Corporation | Handheld electronic device and head mounted electronic device |
| CN110618537B (en) * | 2019-09-02 | 2021-10-01 | 深圳技术大学 | Coated lens device and three-dimensional reconstruction imaging system applying same |
| CN110879473B (en) * | 2019-11-27 | 2021-11-30 | 歌尔光学科技有限公司 | Projection lens assembly and head-mounted display device |
| CN111175981B (en) * | 2020-02-18 | 2022-08-09 | 京东方科技集团股份有限公司 | Head-mounted display device |
| CN113721414A (en) * | 2020-05-25 | 2021-11-30 | 深圳光峰科技股份有限公司 | Prism assembly, light-emitting device and projection system |
| CN111694211B (en) * | 2020-07-29 | 2024-10-15 | 杭州光粒科技有限公司 | Projection system and AR display device |
| CN114167575A (en) * | 2020-08-19 | 2022-03-11 | 华为技术有限公司 | Lens module, camera module and terminal |
| CN114690524A (en) * | 2022-03-30 | 2022-07-01 | 青岛海信激光显示股份有限公司 | Optical illumination system and laser projection equipment |
| CN114967311B (en) * | 2022-04-28 | 2023-10-20 | 歌尔光学科技有限公司 | Projection system and electronic equipment |
| CN117170166A (en) * | 2022-05-26 | 2023-12-05 | 宁波舜宇光电信息有限公司 | Miniature projection module and head-mounted display equipment |
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| CN209167777U (en) * | 2018-11-09 | 2019-07-26 | 广景视睿科技（深圳）有限公司 | A kind of projection lens and optical projection system |
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| WO2014064743A1 (en) * | 2012-10-22 | 2014-05-01 | Ｎｅｃディスプレイソリューションズ株式会社 | Projector |
| CN105988194B (en) * | 2015-01-30 | 2019-03-15 | 信泰光学(深圳)有限公司 | Projection lens |
| JP7019961B2 (en) * | 2017-04-20 | 2022-02-16 | コニカミノルタ株式会社 | Projection optics and projection equipment |
| CN108319002A (en) * | 2018-04-12 | 2018-07-24 | 北京数科技有限公司 | A kind of camera lens |
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