CN114415393A - Optical imaging system - Google Patents

Abstract

The embodiment of the invention relates to the field of optical imaging, and discloses an optical imaging system. The optical imaging system comprises a first light splitting element, a first optical phase modulation element, a second light splitting element, a second optical phase modulation element and a polarizer which are sequentially arranged according to the transmission direction of emergent light of an object to be imaged. The light emitted by the object to be imaged is polarized light, the first light splitting element and the second light splitting element support reflection and transmission for incident light, the first optical phase modulation element and the second optical phase modulation element are quarter-wave plates, and the polarized light transmitted by the polarizer is reflected by the second light splitting element and is reflected by the first light splitting element again. With this arrangement, it is not necessary to tilt any optical element, so that the space occupied by each optical element is small, thereby enabling the volume of the imaging apparatus to be reduced.

Description

Optical imaging system

Technical Field

The embodiment of the invention relates to the technical field of optics, in particular to an optical imaging system.

Background

The real image refers to an image which can be presented on a light screen, and in an actual implementation scene, the real image can be displayed on the light screen or can be displayed in a floating manner in the air. The imaging principle of the real image is that light rays emitted by an object to be imaged are reflected or refracted, so that the light rays emitted by the object to be imaged are converged again, and an image formed by converging the light rays is the real image of the object to be imaged.

As shown in fig. 1, a conventional real image forming apparatus includes a display source 11, a reflective polarizer 12, a retro-reflector 13 and a wave plate 14, wherein the reflective polarizer 12 receives light emitted from the display source 11, transmits a portion of the light to the other side of the reflective polarizer 12, reflects another portion of the light to the wave plate 14, the wave plate 14 processes the received light and emits the processed light to the retro-reflector 13, and the retro-reflector 13 retro-reflects the received light, such that the retro-reflected light is transmitted through the wave plate 14 and the reflective polarizer 12, and then converges on the other side of the reflective polarizer 12, so as to form a real image of an object displayed by the display source 11.

It can be seen that to ensure that the light emitted from display source 11 can be focused and imaged, reflective polarizer 12 should be at an angle to both display source 11 and retroreflective elements 13, i.e., reflective polarizer 12 should be tilted with respect to the other elements. However, the oblique placement of the reflective polarizer 12 requires a large space, which results in a relatively large volume of the real image imaging apparatus.

Disclosure of Invention

The embodiment of the invention provides an optical imaging system, which can solve the problem that the existing imaging equipment is relatively large in size.

In a first aspect, an embodiment of the present invention provides an optical imaging system, including: the device comprises a first light splitting element, a first optical phase modulation element, a second light splitting element, a second optical phase modulation element and a polarizer which are sequentially arranged according to the transmission direction of emergent light of an object to be imaged, wherein the emergent light of the object to be imaged is polarized light; the first light splitting element and the second light splitting element both support reflection and transmission for incident light; the first optical phase modulation element and the second optical phase modulation element are both quarter wave plates; the polarized light transmitted by the polarizer is reflected by the second light splitting element and is reflected by the first light splitting element again.

In some possible embodiments, when the polarization direction of the polarized light emitted by the object to be imaged is orthogonal to the polarization direction of the polarized light transmitted by the polarizer, an included angle between the optical axis of the first optical phase modulation element and the optical axis of the second optical phase modulation element is 90 ° or-90 °; when the polarization direction of the polarized light emitted by the object to be imaged is the same as the polarization direction of the polarized light transmitted by the polarizer, the included angle between the optical axis of the first optical phase modulation element and the optical axis of the second optical phase modulation element is 0 degree or 180 degrees.

In some possible embodiments, at least one of the first light splitting element and the second light splitting element has a light converging effect to converge the emergent light of the second light splitting element; alternatively, the outgoing light from the second light splitting element diverges.

In some possible embodiments, the first light splitting element includes a planar element and a curved element, and when the first light splitting element is the curved element, a convex surface of the first light splitting element faces the object to be imaged, or a convex surface of the first light splitting element faces the first optical phase modulation element.

In some possible embodiments, the reflectance of the light by the first light splitting element satisfies: 10% to 90%, or the first light splitting element has a transmittance for light satisfying: 10% to 90%; the reflectivity of the second light splitting element to light satisfies the following conditions: 10% to 90%, or the transmittance of the second light splitting element to light satisfies: 10% to 90%.

In some possible embodiments, at least one of the first light splitting element and the second light splitting element has a higher transmittance than reflectance.

In some possible embodiments, the polarizer absorbs polarized light other than a target polarization direction, which is the polarization direction of polarized light transmitted by the polarizer.

In a second aspect, an embodiment of the present invention further provides an imaging apparatus, including a display element and an optical imaging system, where the display element is used to emit light of an object to be imaged, and the optical imaging system is as described in the first aspect or any one of the possible implementation manners of the first aspect.

In some possible embodiments, the display element is implemented as any one of:

the device comprises an entity of the object to be imaged, which is irradiated by the linearly polarized light, an entity of the object to be imaged, which emits the linearly polarized light, and a display for displaying the image of the object to be imaged, wherein the linearly polarized light is emitted by the display, or the linearly polarized light is emitted by the combination of the display and a linearly polarized light processing device.

In some possible embodiments, when the imaging device performs real image, the distance from the light-emitting surface of the display element to the real image imaging plane is greater than or equal to the distance from the light-emitting surface to the polarizer.

In order to solve the problem that the volume of an existing imaging device is relatively large, the optical imaging system provided by the embodiment of the application comprises a first light splitting element, a first optical phase modulation element, a second light splitting element, a second optical phase modulation element and a polarizer, wherein the first light splitting element, the first optical phase modulation element, the second light splitting element, the second optical phase modulation element and the polarizer are sequentially arranged according to the transmission direction of emergent light of an object to be imaged. The light emitted by the object to be imaged is polarized light, the first light splitting element and the second light splitting element support reflection and transmission for incident light, and the first optical phase modulation element and the second optical phase modulation element are quarter-wave plates. In this way, all the light incident on the first light splitting element is partially reflected, and the other part is transmitted and emitted to the first optical phase modulation element, and further, is modulated by the first optical phase modulation element and then enters the second light splitting element. And all the light rays incident to the second light splitting element have a part which is reflected to the first optical phase modulation element and further incident to the first light splitting element, and the other part which is transmitted to the second optical phase modulation element. This allows light to be constantly reflected between the first light splitting element and the second light splitting element. Because the light reflected between the first light splitting element and the second light splitting element passes through the first optical phase modulation element for multiple times, the light entering the second light splitting element is subjected to phase delay of different degrees, and after the light is transmitted and emitted to the second optical phase modulation element through the second light splitting element, the light is subjected to phase modulation again through the second optical phase modulation element to obtain the polarized light in the first polarization direction and the polarized light in the second polarization direction. The polarized light transmitted by the polarizer is reflected from the second light splitting element and is reflected by the first light splitting element again. Therefore, the optical imaging system provided by the embodiment of the application processes the light emitted by the object to be imaged by utilizing the polarization of light and through the mutual matching of the light splitting element supporting transmission and reflection and the optical phase modulation element, so that the polarizer transmits the emitted light to be imaged. Therefore, any optical element does not need to be obliquely arranged, so that the space occupied by each optical element is small, and the volume of the imaging device can be reduced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic structural diagram of an exemplary conventional real image imaging apparatus provided in an embodiment of the present application;

FIG. 2 is a schematic diagram of an exemplary optical phase modulated light ray transformation provided by an embodiment of the present application;

fig. 3A is a schematic diagram of an exemplary structure of an optical imaging system 30 provided in the embodiments of the present application;

fig. 3B is an exemplary structural diagram of an optical imaging system 300 provided in an embodiment of the present application;

fig. 4A is a schematic structural diagram of an optical imaging system 41 provided in an embodiment of the present application;

fig. 4B is a schematic diagram illustrating an exemplary structure of an optical imaging system 42 according to an embodiment of the present disclosure;

fig. 4C is a schematic diagram of an exemplary structure of an optical imaging system 43 according to an embodiment of the present application;

fig. 5 is a schematic diagram of an exemplary structure of an optical imaging system 51 provided in the embodiment of the present application;

fig. 6 is a schematic structural diagram of an imaging device 60 according to an embodiment of the present application.

Detailed Description

The terminology used in the following examples of the present application is for the purpose of describing alternative embodiments and is not intended to be limiting of the present application. As used in the specification of the present application and the appended claims, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well. It should also be understood that although the terms first, second, etc. may be used in the following embodiments to describe a class of objects, the objects are not limited to these terms. These terms are used to distinguish between particular objects of that class of objects. For example, the terms first, second, etc. may be used in the following embodiments to describe the light splitting element, but the light splitting element should not be limited to these terms. The following embodiments may adopt the terms first, second, etc. to describe other class objects in the same way, and are not described herein again.

The techniques involved in the embodiments of the present application are explained below.

Since polarized light, also called polarized light, is an electromagnetic wave, light waves propagate in a certain vibration direction during propagation, and the plane formed during propagation of light waves is called a vibration plane. Generally, a plane of vibration of a light wave is in one direction, for example, a direction perpendicular to the ground (hereinafter, referred to as a vertical direction) or a direction parallel to the ground (hereinafter, referred to as a horizontal direction), and therefore, such a light wave is called plane polarized light or linearly polarized light.

In an actual implementation process, if the vertical direction is the first polarization direction, the horizontal direction is the second polarization direction, and if the horizontal direction is the first polarization direction, the vertical direction is the second polarization direction, which is not limited in this application embodiment.

Optical phase modulation is a modulation method in which the phase of an optical wave is changed by changing the optical path of the optical wave. The optical phase modulating element is commonly referred to as a wave plate, which contains an optical axis that is parallel to the end faces of the wave plate. After the linearly polarized light enters the wave plate, the wave plate can decompose the linearly polarized light into first light and second light, wherein the first light and the second light are perpendicular to the optical axis, the transmission speed directions of the first light and the second light are the same, and the transmission speeds of the first light and the second light are different. Based on this, after the modulation of the wave plate, a certain amount of phase difference can be generated between the first light and the second light, so that the phase modulation of the polarized light is realized. The wave plate generally includes a half wave plate and a quarter wave plate, and the half wave plate can generate a phase difference of pi between the first light and the second light, so that the polarization direction of the modulated polarized light is phase-rotated by 90 ° with respect to the polarization direction of the polarized light before modulation. The quarter-wave plate may cause a phase difference of pi/2 to be generated between the first light and the second light, such that the polarization direction of the polarized light after modulation is rotated by 45 ° with respect to the polarization direction of the polarized light before modulation.

Wherein, the included angle between the optical axis of the quarter-wave plate and the polarization direction of the incident polarized light can be +45 degrees, -45 degrees, +135 degrees or-135 degrees. As shown in fig. 2, the polarized light in the first polarization direction or the second polarization direction may be modulated by the quarter-wave plate to emit circularly polarized light.

Splitting means splitting an incident light into at least two light beams. The light splitting mode may include emitting a part of the incident light, and performing other processing on another part of the incident light, the other processing including, for example, reflection or absorption; alternatively, the light splitting device transmits only one type of light, while reflecting or absorbing other types of light.

The embodiment of the application provides an optical imaging system, and each optical element is arranged and set in sequence according to the transmission direction of emergent light of an object to be imaged. Through the polarisation characteristic of utilizing light, the optical element who arranges in order in this application embodiment still can realize the reflection and the transmission of light, and then makes the light formation of optical imaging system outgoing wait to form a real image or the virtual image of object, need not to incline and places arbitrary optical element for the space that each optical element occupy is less, thereby can reduce corresponding imaging device's volume.

The technical solutions of the embodiments of the present application are described below with reference to examples.

Referring to fig. 3A, fig. 3A shows an optical imaging system 30 (hereinafter referred to as system 30) according to an embodiment of the present application, where the system 30 is used for imaging, and includes: the optical imaging device comprises a first light splitting element 301, a first optical phase modulation element 302, a second light splitting element 303, a second optical phase modulation element 304 and a polarizer 305 which are sequentially arranged according to the transmission direction of emergent light of an object to be imaged.

It is to be understood that the configuration illustrated in fig. 3A does not constitute a specific limitation on the optical imaging system 30. In other embodiments of the present application, the optical imaging system 30 may include more or fewer optical elements than shown, or different combinations or different deployments of various optical elements.

In some embodiments, both the first light splitting element 301 and the second light splitting element 303 support reflection and transmission for incident light. For example, for light incident on the object to be imaged, the first light splitting element 301 transmits a part of the light to the first optical phase modulation element 302, and reflects another part of the light. For the light incident from the first optical phase modulation element 302, the second beam splitter 303 reflects a portion of the light to the first optical phase modulation element 302 and transmits a portion of the light to the second optical phase modulation element 304. And the light reflected by the second light splitting element 303 and incident on the first light splitting element 301 again through the first optical phase modulation element 302, a part of the light is reflected again by the first light splitting element 301, and the other part of the light is transmitted through the first light splitting element 301. Thus, in theory, before the light energy is completely consumed, the first light splitting element 301 and the second light splitting element 303 reflect part of the light towards the opposite end.

For example, the first light splitting element 301 and the second light splitting element 303 may be optically coated on the surfaces thereof to achieve partially transmitting and partially reflecting functions. The optical coating may be coated on at least one end surface of the corresponding light splitting element.

It is to be noted that, without considering the absorption of light, the sum of the proportion of light reflected by the first light splitting element 301 and the proportion of light reflected should be 100%, based on which the reflectance of the first light splitting element 301 to light satisfies: 10% to 90%, or the transmittance of the first light splitting element 301 to light satisfies: 10% to 90%. It is to be understood that when the reflectance of the first light splitting element 301 to light is 10%, the transmittance of the first light splitting element 301 to light is 90%. Alternatively, the reflectance of the first light splitting element 301 to light may be set to 20% to 80% in general, or the transmittance of the first light splitting element 301 to light may be set to 20% to 80%. Similarly, the sum of the proportion of light reflected by the second light splitting element 303 and the proportion of reflected light should also be 100%, based on which the reflectance of light by the second light splitting element 303 satisfies: 10% to 90%, or the transmittance of the second light splitting element 303 to light satisfies: 10% to 90%. Alternatively, the reflectance of light by the second light splitting element 303 may be set to 20% to 80%, or the transmittance of light by the first light splitting element 301 may be set to 20% to 80%.

It is noted that in some embodiments, at least one of the first light splitting element 301 and the second light splitting element 303 may be configured to have a higher transmittance than reflectance. For example, the transmittance of the first light splitting element 301 is about 60%, and the reflectance of the first light splitting element 301 is about 40%; for another example, the transmittance of the second light splitting element 303 is about 70%, and the reflectance of the second light splitting element 303 is about 30%. With this arrangement, less disturbance in the light emitted from the polarizer 305 for image formation can be ensured, and the image formation effect can be optimized.

In some embodiments, the light ray S1 exiting the object to be imaged is polarized light, and the first optical phase modulation element 302 and the second optical phase modulation element 304 are both quarter wave plates. Based on this, in an actual implementation scenario, after the light ray S1 emitted from the object to be imaged enters the first light splitting element 301, the first light splitting element 301 transmits a part of the light ray S1-1 to the first optical phase modulation element 302, and reflects another part of the light ray S1 (not shown in fig. 3A). The light ray S1-1 is modulated by the first optical phase modulation element 302 and then converted into a light ray S2. After the light ray S2 enters the second light splitting element 303, the second light splitting element 303 reflects a portion of the light ray S2-1 of the light ray S2 to the first optical phase modulation element 302, and transmits a portion of the light ray S2-2 of the light ray S2 to the second optical phase modulation element 304. The light ray S2-1 is modulated by the first optical phase modulation element 302 and then converted into a light ray S3. After the light ray S3 enters the first light splitting element 301, a part of the light ray S3-1 is reflected by the first light splitting element 301 again and enters the first optical phase modulation element 302, and is further modulated and converted into the light ray S4 by the first optical phase modulation element 302. After the light ray S4 enters the second light splitting element 303, the second light splitting element 303 reflects a part of the light ray S4-2 (not shown in fig. 3A) of the light ray S4 to the first optical phase modulation element 302, and transmits a part of the light ray S4-1 of the light ray S4 to the second optical phase modulation element 304. The second optical phase modulation element 304 modulates the light transmitted from the second light splitting element 303, and then, the modulated light enters the polarizer 305. The light transmitted by the polarizer 305 may be imaged.

The light modulated by the second optical phase modulation element 304 is linearly polarized light, and since the light incident on the second optical phase modulation element 304 is modulated by the first optical phase modulation element 302 for different times, the phases of the respective light delayed by the light S1 are different, so that the linearly polarized light emitted by the second optical phase modulation element 304 includes polarized light in the first polarization direction and polarized light in the second polarization direction.

Illustratively, the light ray S1 is polarized light of a first polarization direction, and correspondingly, the light ray S1-1 is also polarized light of the first polarization direction. The light ray S2 modulated by the quarter-wave plate first optical phase modulation element 302 has a phase retardation of pi/2 with respect to the light ray S1-1, and the light ray S2 is circularly polarized light.

On the one hand, for the partial light ray S2-1 of the light ray S2, the light ray S3 obtained after being modulated by the first optical phase modulation element 302 generates a phase retardation of pi relative to the light ray S1-1, and the polarization directions of the corresponding light ray S3 and light ray S3-1 generate a rotation of 90 ° relative to the light ray S1-1, that is, the light ray S3 and light ray S3-1 are polarized light in the second polarization direction. Similarly, the light ray S4 and the light ray S4-1 generate a phase retardation of π/2 with respect to the light ray S3-1, and the light ray S4 and the light ray S4-1 are circularly polarized light. The circularly polarized light S4-1 is modulated by the second optical phase modulator 304 and then converted into linearly polarized light S5 again. On the other hand, a partial light ray S2-2 of the light ray S2 is modulated by the second optical phase modulation element 304 and converted into linearly polarized light S6.

Since the light ray S5 is a light ray S3-1 obtained by sequentially modulating the phase by the first optical phase modulation element 302 and the second optical phase modulation element 304, the light ray S6 is a light ray S1-1 obtained by sequentially modulating the phase by the first optical phase modulation element 302 and the second optical phase modulation element 304, and the light ray S1-1 is orthogonal to the polarization direction of the light ray S3-1, the light ray S5 is orthogonal to the polarization direction of the light ray S6.

As can be seen from the foregoing description of the light transmission process between the first light splitting element 301 and the second light splitting element 303, another part of the light S4 is still reflected by the second light splitting element 303 (not shown in fig. 3A), and the reflected part of the light S4 is modulated by the first optical phase modulating element 302 and then converted into polarized light of the first polarization direction. For the transmission path of the light reflected by the first light splitting element 301 in the converted polarized light and the properties of the light processed by the first optical phase modulation element 302, the second light splitting element 303 and the second optical phase modulation element 304, reference may be made to the foregoing description of the light S1-1, which is not repeated herein.

In some embodiments, polarizer 305, for example, transmits polarized light of one polarization and absorbs polarized light of another polarization. Alternatively, the polarized light transmitted by the polarizer 305 is reflected by the second light splitting element 303 and reflected by the first light splitting element 301 again, for example, the light ray S5 of the light ray S4-1 modulated by the second optical phase modulation element 304 is transmitted and emitted through the polarizer 305, and the light ray S6 of the light ray S2-2 modulated by the second optical phase modulation element 304 is absorbed by the polarizer 305. Therefore, the optical path of the emergent light of the optical imaging system can meet the imaging requirement, and the emergent light of the optical imaging system can be imaged.

It should be understood that, according to the above description of the light transmission process, if the light ray S5 is configured to be transmitted and emitted through the polarizer 305, in an actual implementation scenario, the light reflected by the second light splitting element 303 for the odd number times and reflected by the first light splitting element 301 again can be transmitted and emitted through the polarizer 305 after being modulated by the second optical phase modulation element 304, and the light reflected by the second light splitting element 303 for the even number times and reflected by the first light splitting element 301 again can be absorbed by the polarizer 305 after being modulated by the second optical phase modulation element 304.

Therefore, the optical imaging system provided by the embodiment of the application processes the light emitted by the object to be imaged by utilizing the polarization of light and through the mutual matching of the light splitting element supporting transmission and reflection and the optical phase modulation element, so that the polarizer transmits the emitted light to be imaged. Therefore, any optical element does not need to be obliquely arranged, so that the space occupied by each optical element is smaller, the size of the imaging device can be reduced, and the use feeling of a user is improved.

Optionally, the light S1 emitted from the object to be imaged may be polarized light in the first polarization direction or may be polarized light in the second polarization direction, and the polarized light transmitted by the polarizer 305 may be polarized light in the first polarization direction or may be polarized light in the second polarization direction. Based on this, in order to ensure that the polarized light S5 is transmitted and emitted through the polarizer 305, the arrangement of the first optical phase modulation element 302 and the second optical phase modulation element 304 differs depending on the relationship between the polarization direction of S1 and the polarization direction of S5.

In some embodiments, when the polarization direction of the light ray S1 exiting the object to be imaged is orthogonal to the polarization direction of the light ray S5 transmitted by the polarizer 305, then the polarization direction of the light ray S5 should be rotated by 90 ° or-90 ° with respect to the light ray S1 after the transmission and processing of the light ray S1 according to the optical path S1-1, S2, S2-1, S3, S3-1, S4, S4-1 to S5. In view of this, in the present embodiment, the angle between the optical axis of the first optical phase modulation element 302 and the optical axis of the second optical phase modulation element 304 is 90 ° or-90 °.

In other embodiments, when the polarization direction of the light ray S1 exiting the object to be imaged is the same as the polarization direction of the light ray S5 transmitted by the polarizer 305, the polarization direction of the light ray S5 should be rotated by 0 ° or 180 ° with respect to the light ray S1 after the transmission and processing of the light ray S1 along the optical path S1-1, S2, S2-1, S3, S3-1, S4, S4-1 to S5. In this embodiment, the angle between the optical axis of the first optical phase modulation element 302 and the optical axis of the second optical phase modulation element 304 is 0 ° or 180 °.

Therefore, by adopting the implementation mode, the distance between each optical device can be reduced on the basis of the optical path required by imaging by utilizing the polarization of light, so that the optical elements can be arranged in sequence on the basis of ensuring the imaging performance of the optical imaging system, and further, the volume of the optical imaging system is reduced.

In some embodiments, the optical imaging system according to the embodiments of the present application is used for real-image imaging, and the principle of real-image imaging is that light emitted from the optical imaging system is focused and imaged (as shown in fig. 3A and any one of fig. 4A to 4C). Based on this, if the optical imaging system according to the embodiment of the present application is used for real image formation, at least one of the first light splitting element 301 and the second light splitting element 303 has a light converging effect to converge the emergent light from the polarizer 305. In other embodiments, as shown in the optical imaging system 300 shown in fig. 3B, the optical imaging system according to the embodiment of the present application is used to form a virtual image, and the principle of forming the virtual image is that light emitted from the optical imaging system diverges, and a virtual image of an object to be imaged is formed by converging at a convergence point of opposite extension lines of the divergent light. Based on this, if the optical imaging system described in the embodiment of the present application is used for forming a virtual image, the outgoing light of the second light splitting element 303 diverges.

An example of a possible optical imaging system 30 is described below, using the optical imaging system for real imaging as an example.

In practical implementation scenarios, the first light splitting element 301 in the optical imaging system 30 may include a planar element and a curved element, and when the first light splitting element 301 is a curved element, a convex surface of the first light splitting element 301 faces the object to be imaged, or a convex surface of the first light splitting element 301 faces the first optical phase modulation element 302, such as the first beam splitter shown in fig. 4A to 4C.

Alternatively, whether the first light splitting element 301 is a planar element or a curved element, the surface shapes of both end surfaces of the first light splitting element 301 may be the same or substantially the same.

In order to ensure that the light rays transmitted by the second light splitting element 303 have a converging effect under the action of the first light splitting element 301 and the second light splitting element 303 in the real-image scene of the optical imaging system, in some embodiments, when the convex surface of the first light splitting element 301 faces the object to be imaged, the second light splitting element 303 is a planar element (as shown in fig. 4A), an element with a convex surface facing the first optical phase modulation element 302 (as shown in fig. 4B), or an element with a concave surface facing the first optical phase modulation element 302. And when the second light splitting element 303 is an element with a convex surface facing the first optical phase modulation element 302, the curvature of the first light splitting element 301 is larger than that of the second light splitting element 303. In other embodiments, when the first light splitting element 301 is a planar element, or the convex surface of the first light splitting element 301 faces the element of the first optical phase modulation element 302, the second light splitting element 303 is an element whose concave surface faces the first optical phase modulation element 302, and the curvature of the second light splitting element 303 is greater than that of the first light splitting element 301, as shown in fig. 4C.

Alternatively, whether the second light splitting element 303 is a planar element or a curved element, the surface shapes of the two end surfaces of the second light splitting element 303 may be the same or substantially the same.

Therefore, the optical imaging system provided by the embodiment of the application utilizes the polarization of light, the first light splitting element and the second light splitting element which support transmission and reflection are arranged, and the light emitted by an object to be imaged is processed through mutual matching with the optical phase modulation element, so that the polaroid can be used for imaging after being transmitted and emitted. According to the arrangement, the optical elements are sequentially arranged in the transmission direction of emergent light of the object to be imaged, light can still be reflected and transmitted, any optical element does not need to be obliquely arranged, the occupied space of each optical element is smaller, and the size of the imaging device can be reduced.

The optical imaging system of the embodiments of the present application will be described below with reference to several exemplary optical imaging systems for imaging real images.

As shown in fig. 4A, fig. 4A illustrates an optical imaging system 41 (hereinafter, referred to as system 41), in this example, a first optical phase modulation element 302 and a second optical phase modulation element 304 are implemented as wave plates, for example, and a first light splitting element 301 and a second light splitting element 303 are implemented as beam splitters, for example. Accordingly, the system 41 comprises: the first beam splitter 411, the first wave plate 412, the second beam splitter 413, the second wave plate 414, and the polarizer 415 are sequentially arranged along the transmission direction of the incident light O1. The first beam splitter 411 is a curved mirror with a convex surface facing the direction of the object to be imaged, and the second beam splitter 413 is a plane mirror. For example, in an ideal state, the reflectance of the first beam splitter 411 to light is, for example, 40%, the transmittance of the first beam splitter 411 to light is, for example, 60%, and the reflectance and the transmittance of the second beam splitter 413 to light are, for example, 50%.

Alternatively, the distance between the first spectroscope 411 and the second spectroscope 413 may be set according to the curvature of the first spectroscope 411 so as to satisfy the gaussian imaging rule. The distance between the first wave plate 412 and the first beam splitter may be 0 or the distance between the first wave plate 412, the second beam splitter 413, the second wave plate 414, and the polarizer 415 may be 0.

Illustratively, the incident light O1 is an outgoing light ray of an object to be imaged, and the incident light O1 is, for example, vertically polarized light. For the incident light O1, the first beam splitter 411 transmits a part of the light to the first wave plate 412, and the part of the light is modulated by the first wave plate 412 and then converted into circularly polarized light O2. After the circularly polarized light O2 enters the second beam splitter 413, a part of the light is reflected by the second beam splitter 413 to the first wave plate 412 again, and the part of the light is modulated by the first wave plate 412 and then converted into horizontally polarized light O3. After the O3 enters the first beam splitter 411, part of the light of the O3 is reflected to the first wave plate 412 and is modulated and converted into circularly polarized light O4 by the first wave plate 412. Part of the light transmitted and emitted by the circularly polarized light O4 through the second beam splitter 413 is modulated by the second wave plate 414 and then converted into polarized light O5, and O5 can be transmitted and emitted through the polarizer 415 for imaging.

It should be understood that the corresponding optical path of O1 in system 41 is not limited to the above description, but also includes other optical paths of light. The optical path and the property of light at each stage of the O1 in the system 41 can be described with reference to the embodiment shown in fig. 3A, and are not described herein again.

Referring to fig. 4A again, the convex surface of the first beam splitter 411 faces the object to be imaged, so the light reflected by the first beam splitter 411 and emitted to the first wave plate 412 is converged, so that the light emitted by the polarizer 415 can be converged into a real image.

Illustratively, the polarizer 415 transmits vertically polarized light and absorbs horizontally polarized light, for example, and then it should be ensured that the polarization direction of O5 is vertically, i.e., it should be ensured that the polarization direction of O3 is converted from the horizontal direction to the vertical direction after being phase-modulated by the first wave plate 412 and the second wave plate 414. The angle of the optical axis of the first wave plate 412 to the vertical is, for example, 45 °, then the angle of the optical axis of the second wave plate 414 to the vertical may be 45 ° or-135 °. Of course, according to the description of the above embodiments, in this implementation scheme, it is only necessary to ensure that the included angle between the optical axis of the first wave plate 412 and the optical axis of the second wave plate 414 is 0 ° or 180 °. For example, when the angle of the optical axis of the first wave plate 412 is 135 ° from the vertical direction, the angle of the optical axis of the second wave plate 414 from the vertical direction may be 135 ° or-45 °. This is not exemplified here.

In other embodiments, the polarizer 415 transmits horizontally polarized light and absorbs vertically polarized light, for example, and it is ensured that the polarization direction of the O5 is horizontal, i.e., it is ensured that the polarization direction of the O3 is still horizontal after the phase modulation of the first wave plate 412 and the second wave plate 414. The angle of the optical axis of the first wave plate 412 to the vertical is, for example, 45 °, then the angle of the optical axis of the second wave plate 414 to the vertical may be-45 ° or 135 °. Of course, according to the above description of the embodiments, in this implementation, it is sufficient to ensure that the optical axis of the first wave plate 412 and the optical axis of the second wave plate 414 form an angle of 90 ° or a combination of-90 °. For example, when the angle of the optical axis of the first wave plate 412 is 135 ° from the vertical direction, the angle of the optical axis of the second wave plate 414 may be 45 ° or-135 ° from the vertical direction. This is not exemplified here.

In other embodiments, incident light O1 may be horizontally polarized light, and in this implementation scenario, polarizer 415 may transmit horizontally polarized light and absorb vertically polarized light, or may transmit vertically polarized light and absorb horizontally polarized light. When the polarizer 415 absorbs the horizontally polarized light, the angle between the optical axis of the first wave plate 412 and the optical axis of the second wave plate 414 is 90 ° or-90 °, for example, the angle between the optical axis of the first wave plate 412 and the horizontal direction is 135 °, and the angle between the optical axis of the second wave plate 414 and the horizontal direction may be 45 ° or-135 °. When the polarizer 415 absorbs the polarized light in the vertical direction, the angle between the optical axis of the first wave plate 412 and the optical axis of the second wave plate 414 is 0 ° or 180 °, for example, the angle between the optical axis of the first wave plate 412 and the horizontal direction is 45 °, and the angle between the optical axis of the second wave plate 414 and the horizontal direction may be 45 ° or-135 °.

It is to be understood that the above description related to fig. 4A is an exemplary implementation of the optical imaging system of the present application, and does not constitute a limitation on the optical imaging system of the present application. In other embodiments, at least one of the first beam splitter and the second beam splitter in the optical imaging system may also be an optical element with other shapes, for example, if the first beam splitter is kept unchanged as shown in fig. 4A, the second beam splitter may also be another arbitrary curved mirror as shown in fig. 4B.

Fig. 4B illustrates an optical imaging system 42 (hereinafter system 42), system 42 comprising: a first beam splitter 421, a first wave plate 422, a second beam splitter 423, a second wave plate 424, and a polarizer 425, which are sequentially arranged along a transmission direction of incident light. The functions and optical paths of the optical elements in the system 42 can be referred to the description of the system 41, and are not described herein. In the system 42, the first beam splitter 421 is a curved mirror with a convex surface facing the direction of the object to be imaged, and the second beam splitter 423 is convex surface facing the first wave plate 422.

It is noted that, according to the principles of real image imaging, the light transmitted by polarizer 425 should be converged. In the system 42, the light reflected by the first beam splitter 421 and emitted toward the first wave plate 422 is focused, and the light reflected by the second beam splitter 423 and emitted toward the first wave plate 422 is diffused. Based on this, in order to ensure that the light transmitted by the polarizer 425 converges, the curvature of the first beam splitter 421 should be larger than the curvature of the second beam splitter 423, and the relationship between the curvature of the first beam splitter 421 and the curvature of the second beam splitter 423 can be determined according to the position requirement of the actual imaging.

Further, optionally, when the first beam splitter is shown as the first beam splitter 411 in the system 41, or as the first beam splitter 421 in the system 42, the second beam splitter in other exemplary optical imaging systems may also be implemented as an optical element with a concave surface facing the first wave plate.

It can be understood that the implementation manner of the first beam splitter in fig. 4A and 4B is only one optional manner of the embodiment of the present application, and the technical solution of the embodiment of the present application is not limited. In other implementations, the first beam splitter in the optical imaging system may also be implemented as an optical element of other shapes.

As shown in fig. 4C, fig. 4C illustrates an optical imaging system 43 (hereinafter referred to as system 43), the system 43 comprising: a first beam splitter 431, a first wave plate 432, a second beam splitter 433, a second wave plate 434, and a polarizer 435, which are sequentially arranged along a transmission direction of incident light. The functions and optical paths of the optical elements in the system 43 can be referred to the descriptions of the foregoing embodiments, and are not repeated here. The convex surface of the first beam splitter 431 and the convex surface of the second beam splitter 433 in the system 43 face the first wave plate 432 and the second wave plate 434, respectively.

In the system 43, the light emitted from the first beam splitter 431 to the first wave plate 432 is diverged, reflected from the second beam splitter 433, reflected by the first beam splitter 431, and then transmitted by the second beam splitter 433 to be converged. Based on this, in order to ensure that the light transmitted by the polarizer 435 can be converged into a real image, the curvature of the second beam splitter 433 in the system 43 should be larger than that of the first beam splitter 431, and the amount of the larger curvature can be flexibly set according to practical requirements, and is not limited herein.

Alternatively, the first beam splitter 431 in the system 43 may be replaced by a planar optical element, which will not be described herein.

It is to be understood that fig. 4A to 4C described above are each an exemplary description of imaging the optical imaging system in real time. In a scene in which the optical imaging system forms a virtual image, by setting a combination of different surface types and curvatures of the first light splitting element and the second light splitting element, divergence of light transmitted and emitted by the second light splitting element should be ensured.

Fig. 5 illustrates an optical imaging system 51 (hereinafter system 51), system 51 being used for virtual imaging. The system 51 comprises: a first beam splitter 511, a first wave plate 512, a second beam splitter 513, a second wave plate 514, and a polarizer 515, which are sequentially arranged along a transmission direction of incident light. The first beam splitter 511 is a flat mirror, and the second beam splitter 513 is a curved mirror with a convex surface facing the second waveplate 514. The functions and optical paths of the optical elements in the system 51 can be referred to the description of the foregoing embodiments, and are not repeated here.

In the system 51, the light reflected by the first beam splitter 511 and transmitted in the emergent direction through the first wave plate 512 and the second beam splitter 513 is dispersed, so that the light transmitted by the polarizer 515 is ensured to be dispersed, and the reverse extension lines of the light transmitted by the polarizer 515 can be converged into a virtual image.

It is to be understood that fig. 5 is only an exemplary implementation of the optical imaging system of the present application in virtual image, and does not constitute a limitation of the optical imaging system of the present application. In other embodiments, at least one of the first beam splitter and the second beam splitter in the optical imaging system may also be an optical element with other shapes, and will not be described in detail herein.

In addition, fig. 3A to fig. 5 are exemplary descriptions, and in practical implementation, the polarizer provided in the optical imaging system may be a polarizing device with a compensation function, so that the problem of light leakage of the optical imaging system in a large-viewing-angle scene can be improved. In addition, other optical elements may also be included in the optical imaging system. For example, the optical imaging system further includes a new polarizer disposed in the emergent direction of the polarizer, and if the polarizer transmits polarized light in the vertical direction, the new polarizer also transmits polarized light in the vertical direction and can absorb polarized light in the horizontal direction. Similarly, if the polarizer transmits horizontally polarized light, the new polarizer also transmits horizontally polarized light and can absorb vertically polarized light. Therefore, the effect of removing the interference light can be achieved, and the imaging effect is better. For another example, an AG (anti-glare) treatment may be performed on the surface of the outermost device of the optical imaging system to reduce the reflection on the surface of the optical imaging system.

In summary, the optical imaging system provided in the embodiment of the present application includes a first light splitting element, a first optical phase modulation element, a second light splitting element, a second optical phase modulation element, and a polarizer, which are sequentially arranged according to a transmission direction of an emergent light of an object to be imaged. The light emitted by the object to be imaged is polarized light, the first light splitting element and the second light splitting element support reflection and transmission for incident light, and the first optical phase modulation element and the second optical phase modulation element are quarter-wave plates. In this way, all the light incident on the first light splitting element is partially reflected, and the other part is transmitted and emitted to the first optical phase modulation element, and further, is modulated by the first optical phase modulation element and then enters the second light splitting element. And all the light rays incident to the second light splitting element have a part which is reflected to the first optical phase modulation element and further incident to the first light splitting element, and the other part which is transmitted to the second optical phase modulation element. Thus, light rays are continuously reflected between the first light splitting element and the second light splitting element. Because the light reflected between the first light splitting element and the second light splitting element passes through the first optical phase modulation element for multiple times, the light entering the second light splitting element is subjected to phase delay of different degrees, and after the light is transmitted and emitted to the second optical phase modulation element through the second light splitting element, the light is subjected to phase modulation again through the second optical phase modulation element to obtain the polarized light in the first polarization direction and the polarized light in the second polarization direction. The polarized light transmitted by the polarizer is reflected from the second light splitting element and is reflected by the first light splitting element again. Therefore, the optical imaging system provided by the embodiment of the application processes the light emitted by the object to be imaged by utilizing the polarization of light and through the mutual matching of the light splitting element supporting transmission and reflection and the optical phase modulation element, so that the polarizer transmits the emitted light to be imaged. Therefore, any optical element does not need to be obliquely arranged, so that the space occupied by each optical element is small, and the volume of the imaging device can be reduced.

Referring to fig. 6, corresponding to the above, fig. 6 illustrates an imaging device 60, the imaging device 60 comprising a display element 61 and an optical imaging system 62, the optical imaging system 62 being as shown in any of the systems 30 to 51, the display element 61 being for emitting light of an object to be imaged.

According to the description of the above embodiment, the incident light of the optical imaging system 62 is linearly polarized light, based on which the display element 61 can be implemented as any of: the imaging device comprises a solid body of an object to be imaged, which is irradiated by linearly polarized light, a solid body of the object to be imaged, which emits the linearly polarized light, a display and the like, which display an image of the object to be imaged.

For example, if the light emitted from the display is linearly polarized light, the light emitted from the display may be used as the incident light of the optical imaging system 62. If the light emitted from the display is not linearly polarized light, a linearly polarized light processing device may be disposed in the direction of the light emitted from the display, and the light emitted from the linearly polarized light processing device may be used as the incident light of the optical imaging system 62.

Optionally, privacy films may be placed on the display surface, in the backlight of the display, or on the outermost optics of the optical imaging system 62 to limit the exit angle of the light. The peep-proof film is an optical material with a similar shutter structure, and can limit the divergence angle of light within a certain range.

In addition, when the display is an LCD (Li qu i d crystal l Di sp l ay, liquid crystal display), since the backlight of the LCD is composed of an array of LED (light-emitting diode) lamp beads, the divergence angle of the LED lamp beads is 180 degrees. In order to limit the divergence angle of the light of the LED lamp bead and improve the light energy utilization rate, an optical lens can be added on the LED lamp bead to limit the divergence angle of the LED lamp bead.

In some embodiments, if the imaging device 60 is used for real image formation, the distance from the light-emitting surface of the display element 61 to the imaging plane of the real image is greater than or equal to the distance from the light-emitting surface to the polarizer, so as to ensure that the real image is formed outside the imaging device 60.

According to the foregoing description of the optical imaging system, since the optical elements in the optical imaging system are sequentially arranged, it is not necessary to tilt any optical element, so that the space occupied by each optical element is small, and the volume of the imaging apparatus can be reduced.

All parts of the specification are described in a progressive mode, the same and similar parts among all the embodiments can be referred to each other, the emphasis of each embodiment is different from other embodiments, and relevant points can be referred to the description of the method embodiment parts.

While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims (10)

1. An optical imaging system, characterized in that the system comprises:

the device comprises a first light splitting element, a first optical phase modulation element, a second light splitting element, a second optical phase modulation element and a polarizer which are sequentially arranged according to the transmission direction of emergent light of an object to be imaged, wherein the emergent light of the object to be imaged is polarized light;

the first light splitting element and the second light splitting element both support reflection and transmission for incident light;

the first optical phase modulation element and the second optical phase modulation element are both quarter wave plates;

the polarized light transmitted by the polarizer is reflected by the second light splitting element and is reflected by the first light splitting element again.

2. The optical imaging system of claim 1,

when the polarization direction of the polarized light emitted by the object to be imaged is orthogonal to the polarization direction of the polarized light transmitted by the polarizer, the included angle between the optical axis of the first optical phase modulation element and the optical axis of the second optical phase modulation element is 90 degrees or-90 degrees;

when the polarization direction of the polarized light emitted by the object to be imaged is the same as the polarization direction of the polarized light transmitted by the polarizer, the included angle between the optical axis of the first optical phase modulation element and the optical axis of the second optical phase modulation element is 0 degree or 180 degrees.

3. The optical imaging system of claim 1,

at least one of the first light splitting element and the second light splitting element has a light converging effect so as to converge emergent light of the second light splitting element; alternatively, the first and second electrodes may be,

the emergent light of the second light splitting element is diverged.

4. The optical imaging system of claim 1,

the first light splitting element includes a planar element and a curved element,

when the first light splitting element is the curved surface element, a convex surface of the first light splitting element faces the object to be imaged, or a convex surface of the first light splitting element faces the first optical phase modulation element.

5. The optical imaging system of any one of claims 1 to 4,

the reflectivity of the first light splitting element to light satisfies the following conditions: 10% to 90%, or the first light splitting element has a transmittance for light satisfying: 10% to 90%;

the reflectivity of the second light splitting element to light satisfies the following conditions: 10% to 90%, or the transmittance of the second light splitting element to light satisfies: 10% to 90%.

6. The optical imaging system of claim 5, wherein at least one of the first and second light splitting elements has a higher transmittance than reflectance.

7. The optical imaging system of claim 1 or 2, wherein the polarizer absorbs polarized light other than a target polarization direction, the target polarization direction being a polarization direction of polarized light transmitted by the polarizer.

8. An imaging apparatus comprising a display element for emitting light of an object to be imaged and an optical imaging system according to any one of claims 1 to 7.

9. The imaging apparatus of claim 7, wherein the display element is implemented as any one of:

the device comprises an entity of the object to be imaged, which is irradiated by the linearly polarized light, an entity of the object to be imaged, which emits the linearly polarized light, and a display for displaying the image of the object to be imaged, wherein the linearly polarized light is emitted by the display, or the linearly polarized light is emitted by the combination of the display and a linearly polarized light processing device.

10. The imaging apparatus according to claim 8 or 9, wherein when the imaging apparatus performs real image, a distance from the light exit surface of the display element to the real image imaging plane is greater than or equal to a distance from the light exit surface to the polarizer.

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