CN114200685A - 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 optical phase modulation element, a first light splitting element, a second optical phase modulation element and a second light splitting element which are sequentially arranged according to the transmission direction of emergent light of an object to be imaged, wherein incident light of the first optical phase modulation element is polarized light, the second light splitting element transmits the polarized light of a first polarization direction and reflects the polarized light of a second polarization direction, the first polarization direction is orthogonal to the second polarization direction, the first optical phase modulation element and the second optical phase modulation element are both quarter-wave plates, the first light splitting element transmits the light from the first optical phase modulation element, and the light reflected by the second light splitting element is reflected. 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 optical phase modulation device comprises a first optical phase modulation element, a first light splitting element, a second optical phase modulation element and a second light splitting element which are sequentially arranged according to the transmission direction of emergent light of an object to be imaged; the incident light of the first optical phase modulation element is polarized light, the second light splitting element transmits the polarized light in a first polarization direction and reflects the polarized light in a second polarization direction, and the first polarization direction is orthogonal to the second polarization direction; the first optical phase modulation element and the second optical phase modulation element are both quarter wave plates; the first light splitting element transmits light from the first optical phase modulation element and reflects light reflected by the second light splitting element.

In some possible embodiments, when the incident light of the first optical phase modulation element is polarized light of the first polarization direction, an angle between an optical axis of the first optical phase modulation element and an optical axis of the second optical phase modulation element is 0 ° or 180 °; when the incident light of the first optical phase modulation element is the polarized light in the second polarization direction, 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 °.

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 first optical phase modulation element, or a convex surface of the first light splitting element faces an element of the second optical phase modulation element.

In some possible embodiments, if at least one of the first light splitting element and the second light splitting element has a light converging effect, when the convex surface of the first light splitting element faces the first optical phase modulation element, the second light splitting element is a planar element, an element with a convex surface facing the second optical phase modulation element, or an element with a concave surface facing the second optical phase modulation element, and when the second light splitting element is an element with a convex surface facing the second optical phase modulation element, the curvature of the first light splitting element is greater than that of the second light splitting element; when the first light splitting element is the planar element or the element in which the convex surface of the first light splitting element faces the second optical phase modulation element, the second light splitting element is an element in which the concave surface faces the second optical phase modulation element, and the curvature of the second light splitting element is greater than that of the first light splitting 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%.

In some possible embodiments, the optical imaging system further comprises: the polaroid is arranged in the transmission emergent direction of the second light splitting element; the polarizer transmits the polarized light of the first polarization direction.

In a second aspect, an embodiment of the present invention 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 second light splitting element.

In order to solve the problem that the volume of the existing imaging device is relatively large, the optical imaging system provided by the embodiment of the application comprises a first optical phase modulation element, a first light splitting element, a second optical phase modulation element and a second light splitting element which are sequentially arranged according to the transmission direction of emergent light of an object to be imaged. The incident light of the first optical phase modulation element is polarized light, the first optical phase modulation element and the second optical phase modulation element are quarter-wave plates, and the second light splitting element transmits the polarized light in the first polarization direction and reflects the polarized light in the second polarization direction. In addition, the first light splitting element transmits light from the first optical phase modulation element and reflects light reflected by the second light splitting element. Thus, the polarized light incident on the first optical phase modulation element is subjected to the processing by the first optical phase modulation element, the first light splitting element, and the second optical phase modulation element, and is phase-modulated, and further, the phase-modulated light is reflected by the second light splitting element and finally incident on the first light splitting element, and thereafter, the first light splitting element reflects the light again. In the process that the light ray is reflected twice by the second light splitting element and the first light splitting element, the light ray passes through the second optical phase modulation element twice, and the second optical phase modulation element is a quarter wave plate, so that when the light ray is reflected twice by the second light splitting element and the first light splitting element and then exits to the second light splitting element again, the phase delay of pi is generated, namely the polarization direction of the light ray is rotated by 90 degrees, and at the moment, the second light splitting element can transmit the polarization light with the modulated pi phase. Further, the transmitted light is made to be imaged. Therefore, in the optical imaging system provided in the embodiment of the present application, the first light splitting element supporting transmission and reflection is arranged by utilizing the polarization of light, and the polarized light emitted from the object to be imaged is subjected to phase modulation, so that the light is reflected between the first light splitting element and the second light splitting element, and then the phase of the light is modulated twice by using the second optical phase modulation element again in the light reflection and transmission process, so that the second light splitting element can transmit the light emitted by the second optical phase modulation element for the second time, and further imaging is performed. 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.

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. 4D is a schematic diagram illustrating an exemplary configuration of an optical imaging system 44 provided by an embodiment of the present application;

FIG. 4E is a schematic diagram of an exemplary scene imaged in a virtual image by an optical imaging system provided in an embodiment of the present application;

fig. 5 is a schematic structural diagram of an imaging apparatus 50 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 phase-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 optical phase modulation element 31A, a first light splitting element 32A, a second optical phase modulation element 31B and a second light splitting element 32B which are sequentially arranged according to the transmission direction of emergent light of an object to be imaged. The incident light ray S1 of the first optical phase modulation element is polarized light. At least one of the first light splitting element 32A and the second light splitting element 32B has a condensing effect on the light.

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, the first light splitting element 32A transmits the light from the first optical phase modulation element 31A, and reflects the light S4 reflected by the second light splitting element 32B and modulated by the second optical phase modulation element 31B. Of course, the first light splitting element 32A also reflects part of the light from the first optical phase modulation element 31A.

For example, the first light splitting element 32A may perform partially transmitting and partially reflecting functions by means of an optical coating disposed on the surface. The optical coating film may be coated on at least one end surface of the first light splitting element 32A.

Note that the ratio of light reflected by the first light splitting element 32A and the ratio of reflected light should be 100%, based on which the reflectance of the first light splitting element 32A to light satisfies: 10% to 90%, or the transmittance of the first light splitting element 32A to light satisfies: 10% to 90%. It is to be understood that when the reflectance of the first light splitting element 32A to light is 10%, the transmittance of the first light splitting element 32A to light is 90%. Alternatively, the transmission reflectance of the first light splitting element 32A to light may be set to 40% to 60% in general, or the transmission of the first light splitting element 32A to light may be set to 40% to 60%.

In some embodiments, second beam splitting element 32B transmits polarized light of the first polarization direction and reflects polarized light of the second polarization direction. The first polarization direction and the second polarization direction are set as described above. The first optical phase modulation element 31A and the second optical phase modulation element 31B are both quarter wave plates.

In practical implementation, the light S2, S2 transmitted through the first light splitting element 32A and incident on the second optical phase modulation element 31B is modulated by the second light splitting element 31B and then converted into light S3, and S3 is reflected by the second light splitting element 32B. The reflected light ray S3 is converted into a light ray S4 by 31B, S4 is incident on the first light splitting element 32A, reflected by the first light splitting element 32A, and converted into light S5 by the second optical phase modulation element 31B, and S5 is transmitted by the second light splitting element 32B.

As can be seen, in this embodiment, S3 is reflected by the second beam splitter 32B, passes through the second optical phase modulator 31B, and is modulated and converted into S4 by the second optical phase modulator 31B for the first time. S4 reaches the first light splitting element 32A, is reflected by the first light splitting element 32A, passes through the second optical phase modulation element 31B again, is modulated and converted into S5 by the second optical phase modulation element 31B for the second time, and further, exits S5 to the second light splitting element 32B. Since the second optical phase modulation element 31B is a quarter wave plate, in the double reflection process, S3 is twice modulated by the second optical phase modulation element 31B, and the resulting S5 changes the pi phase with respect to S3, that is, the polarization direction of S5 with respect to S3 is converted by 90 °, then S5 can be transmitted by the second light splitting element, and further, imaging can be performed based on the light transmitted by the second light splitting element. Therefore, the optical imaging system provided by the embodiment of the application utilizes the polarization of light and is provided with the optical elements supporting partial reflection and partial transmission, so that the optical elements can be arranged in sequence on the basis of ensuring the imaging performance of the optical imaging system, the size of the optical imaging system is reduced, and the use feeling of a user is improved.

Alternatively, the incident light ray S1 of the first optical phase modulation element 31A may be polarized light with the first polarization direction, or may be polarized light with the second polarization direction. Accordingly, in order to ensure that the light S3 transmitted through the first light splitting element 32A and incident on the second optical phase modulation element 31B and then emitted therefrom is polarized light of the second polarization direction reflected by the second light splitting element 32B, the first optical phase modulation element 31A and the second optical phase modulation element 31B are provided in different arrangements depending on the polarization direction of S1.

In some embodiments, when the incident light ray S1 of the first optical phase modulation element 31A is polarized light in the first polarization direction, the outgoing light ray S3 modulated by the first optical phase modulation element 31A and the second optical phase modulation element 31B in S1 should be polarized light in the second polarization direction. That is, the polarization direction of the light S3 modulated by the first optical phase modulation element 31A and the second optical phase modulation element 31B at S1 should be rotated by 90 ° with respect to S1. In this embodiment, the 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 ° or 180 °.

In other embodiments, when the incident light ray S1 of the first optical phase modulation element 31A is polarized light in the second polarization direction, the exit light S3 modulated by the first optical phase modulation element 31A and the second optical phase modulation element 31B in S1 should maintain the second polarization direction. That is, the polarization direction of the light S3 modulated by the first optical phase modulation element 31A and the second optical phase modulation element 31B at S1 is unchanged with respect to S1. In this embodiment, the 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 °.

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 described in the embodiments of the present application is used for imaging in real, and then, in this example, at least one of the first light splitting element 32A and the second light splitting element 32B has a light converging effect on light so as to converge the outgoing light of the second light splitting element. In other embodiments, the optical imaging system described in the embodiment of the present application is used to form a virtual image, and then, in this example, the emergent light of the second light splitting element 32B diverges.

In practical implementation, the first light splitting element 32A includes a planar element and a curved element, and when the first light splitting element 32A is a curved element, the convex surface of the first light splitting element 32A faces the first optical phase modulation element 31A, or the convex surface of the first light splitting element 32A faces the second optical phase modulation element 31B, such as the beam splitter shown in fig. 4A to 4C.

Alternatively, whether the first light splitting element 32A is a planar element or a curved element, the surface shapes of both end surfaces of the first light splitting element 32A may be the same or substantially the same.

In order to ensure that the light transmitted by the second light splitting element 32B has a converging effect under the action of the first light splitting element 32A and the second light splitting element 32B in the real-image scene of the optical imaging system, in some embodiments, when the convex surface of the first light splitting element 32A faces the first optical phase modulation element 31A, the second light splitting element 32B is a planar element, an element with the convex surface facing the second optical phase modulation element 31B, or an element with the concave surface facing the second optical phase modulation element 31B. And when the second light splitting element 32B is an element having a convex surface facing the second optical phase modulation element 31B, the curvature of the first light splitting element 32A is larger than that of the second light splitting element 32B, as shown in fig. 4B. In other embodiments, when the first light splitting element 32A is a planar element, or the convex surface of the first light splitting element 32A faces the element of the second optical phase modulation element 31B, the second light splitting element 32B is an element whose concave surface faces the second optical phase modulation element 31B, and the curvature of the second light splitting element 32B is greater than that of the first light splitting element 32A, as shown in fig. 4C.

Alternatively, whether second light splitting element 32B is a planar element or a curved element, the surface shapes of both end surfaces of second light splitting element 32B may be the same or substantially the same.

Therefore, in the optical imaging system provided in the embodiment of the present application, the polarization of light is utilized, the first light splitting element supporting transmission and reflection is arranged, the phase modulation is performed on the polarized light emitted from the object to be imaged, so that the light is reflected between the first light splitting element and the second light splitting element, and then the phase of the light is modulated twice by using the second optical phase modulation element again in the light reflection transmission process, so that the second light splitting element can transmit the light emitted by the second optical phase modulation element for the second time, and further imaging is performed. 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.

It should be noted that, depending on the material, the second light splitting element 32B in the system 30 may transmit part of the polarized light with the second polarization direction (the second light splitting element 32B should reflect all of the polarized light with the second polarization direction), so that the light band converged by the second light splitting element 32B interferes, and the imaging effect of the real image is not good. Based on this, on the basis of the system 30, the embodiment of the present application further provides an optical imaging system 300.

Referring to fig. 3B, fig. 3B illustrates an optical imaging system 300 (hereinafter system 300), the system 300 comprising: the optical imaging device comprises a first optical phase modulation element, a first light splitting element, a second optical phase modulation element, a second light splitting element and a polarizer 301 which are sequentially arranged according to the transmission direction of emergent light of an object to be imaged. In this embodiment, the first optical phase modulation element, the first light splitting element, the second optical phase modulation element, and the second light splitting element are all as described in the embodiment illustrated in fig. 3A, and are not described herein again.

The polarizer 301 transmits polarized light of the first polarization direction and does not transmit polarized light of the second polarization direction. Illustratively, the polarizer 301, such as the second polarization direction, may absorb polarized light of the second polarization direction.

As can be seen, the system 300 can filter part of the interference light transmitted by the second light splitting element by arranging the polarizer in the transmission and emission direction of the second light splitting element, so as to ensure the imaging quality.

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 a system 41), in this example, the first optical phase modulation element 31A and the second optical phase modulation element 31B are implemented as wave plates, for example, the first light splitting element 32A is implemented as a beam splitter, for example, and the second light splitting element 32B is implemented as a polarization beam splitter, for example. Accordingly, the system 41 comprises: the first wave plate 411, the beam splitter 412, the second wave plate 413, and the polarization splitting plate 414 are sequentially arranged along the transmission direction of the incident light O1. The beam splitter 412 is a curved mirror with its convex surface facing the direction of the first wave plate 411.

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. The polarization splitter 414 reflects horizontally polarized light and transmits vertically polarized light, for example. The angle between the optical axis of the first wave plate 411 and the vertical direction is 45 °, for example, and the angle between the optical axis of the second wave plate 413 and the vertical direction is 135 °, for example. The beam splitter 412 has a reflectance and a transmittance of 50% for light, for example.

In practical implementation, the distance between the first wave plate 411 and the beam splitter 412 may be 0, or may be set according to the curvature of the beam splitter 412. The distance between the beam splitter 412 and the polarization beam splitter 414 can be set according to the depth of the curved surface of the beam splitter 412, so as to satisfy the gaussian imaging rule. The distance between the second wave plate 413 and the polarization splitting plate 414 may be 0.

Referring again to fig. 4A, the first wave plate 411 performs phase modulation on the incident linearly polarized light O1, resulting in circularly polarized light O2. When the circularly polarized light O2 passes through the beam splitter 412, 50% of the light energy is transmitted to the second wave plate 413. The second wave plate 413 phase-modulates the incident partially circularly polarized light O2 to obtain linearly polarized light O3. Since the included angle between the optical axis of the first wave plate 411 and the optical axis of the second wave plate 413 is 0 ° or 180 ° in this example, and the first wave plate 411 and the second wave plate 413 are both quarter wave plates, the polarization direction of the light obtained by modulating the vertically linearly polarized light O1 by the first wave plate 411 and the second wave plate 413 is rotated by 90 °, that is, the linearly polarized light O3 is horizontally linearly polarized light. Further, after the linearly polarized light O3 in the horizontal direction is incident on the polarization splitting plate 414, the polarization splitting plate 414 reflects O3 to the second wave plate 413. The second wave plate 413 modulates the linearly polarized light O3 into circularly polarized light O4, and exits to the beam splitter 412. The beam splitter 412 reflects the circularly polarized light O4 to the second wave plate 413 again, and the second wave plate 413 performs phase modulation on the circularly polarized light O4 and emits linearly polarized light O5 to the polarization splitting plate 414. That is, the linearly polarized light O3 is reflected by the polarization splitting plate 414 and the beam splitter 412 and passes through the second wave plate 413 twice, and therefore, the polarization direction of the linearly polarized light O5 is rotated by 90 ° compared with the polarization direction of the linearly polarized light O3, and the linearly polarized light O5 is vertically polarized light. Further, the linearly polarized light O5 is transmitted through the polarization splitter 414 and focused for imaging.

It is understood that the above description about the optical path of fig. 4A is an alternative implementation of the embodiment of the present application, and it is sufficient to ensure that the angle between the optical axis of the first wave plate 411 and the optical axis of the second wave plate 413 is 0 ° or 180 °. For example, the angle between the optical axis of the first wave plate 411 and the vertical direction may also be-45 °, and the angle between the optical axis of the second wave plate 413 and the vertical direction may be-135 °; for another example, the angle between the optical axis of the first wave plate 411 and the vertical direction is 135 °, and the angle between the optical axis of the second wave plate 413 and the vertical direction is 45 °, for example, which is not illustrated here.

In other embodiments, incident light O1 may be horizontally polarized light. Then, in this embodiment, the angles between the optical axis of the first wave plate 411 and the optical axis of the second wave plate 413 and the horizontal direction are, for example, 45 °. With reference to fig. 4A, the linearly polarized light O3 obtained by modulating the incident light O1 with the first wave plate 411 and the second wave plate 413 has a polarization direction that is unchanged and remains horizontally polarized. Further, the propagation process after the linearly polarized light O3 is incident on the polarization beam splitter 414 and the polarization state conversion process are the same as those described above, and will not be described herein again. It should be understood that in this example, it is sufficient to ensure that the optical axis of the first wave plate 411 and the optical axis of the second wave plate 413 form an angle of 90 ° or-90 °, which is not illustrated here.

In other embodiments, the polarization splitter 414 may reflect vertically polarized light and transmit horizontally polarized light. Based on this, if the incident light O1 is polarized in the vertical direction, then the polarization direction of O3 should be kept unchanged with respect to O1, and then the included angle between the optical axis of the first wave plate 411 and the optical axis of the second wave plate 413 in the corresponding optical imaging system is 90 ° or-90 °. If the incident light O1 is horizontally polarized light, the polarization direction of O3 should be rotated by 90 ° with respect to the polarization direction of O1, and the angle between the optical axis of the first wave plate 411 and the optical axis of the second wave plate 413 in the corresponding optical imaging system is 0 ° or 180 °, which is not described herein again.

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 beam splitter and the polarization splitter in the optical imaging system may be an optical element with other shapes, for example, if the beam splitter 412 in fig. 4A remains the same, the polarization splitter may be another arbitrary curved mirror, as shown in fig. 4B.

Fig. 4B illustrates an optical imaging system 42 (hereinafter system 42), system 42 comprising: the first wave plate, the spectroscope, the second wave plate and the polarization beam splitting plate 420 are sequentially arranged along the transmission direction of the 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. The polarization splitter 420 in the system 42 has a convex surface facing the second waveplate.

It should be noted that, according to the principle of real image imaging, the light transmitted by the polarization beam splitter 420 should be converged. In the system 42, the light beam reflected by the beam splitter in the outgoing direction has a converging effect, and the light beam reflected by the polarization beam splitter 420 has a scattering effect, so as to ensure the light beam to converge, the curvature of the beam splitter should be larger than that of the polarization beam splitter 420. The relationship between the curvature of the spectroscope and the curvature of the polarization beam splitter 420 can be determined according to the position requirement of actual imaging and the like.

Further, optionally, when the beam splitter 412 is in the scene as shown in system 41, the polarization beam splitter in other optical imaging systems can also be implemented as an optical element with a concave surface facing the second wave plate.

Alternatively, the beam splitter in the optical imaging system may 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 wave plate, a beam splitter 431, a second wave plate, and a polarization splitting plate 432, 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 description of the foregoing embodiments, and are not repeated here. In system 43, the concave surface of the beam splitter 431 faces the first wave plate, and the concave surface of the polarization beam splitter 420 faces the second wave plate.

It should be noted that in the system 43, the beam splitter 431 reflects the light in the emergent direction to have a scattering effect, and the polarization beam splitter 432 transmits the light in the emergent direction to have a converging effect. Based on this, in order to ensure that the light transmitted by the polarization splitter 432 can be converged into a real image, the curvature of the polarization splitter 432 in the system 43 should be greater than that of the beam splitter 431, and the amount of the greater curvature can be flexibly set according to actual requirements, which is not limited herein.

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

It is understood that fig. 4A to 4C described above are exemplary implementations of the optical imaging system of the present application, and do not constitute a limitation on the optical imaging system of the present application. In other embodiments, other optical elements may be included in the optical imaging system, as shown in fig. 4D.

Fig. 4D illustrates an optical imaging system 44 (hereinafter system 44), system 44 comprising: the first wave plate, the spectroscope, the second wave plate, the polarization beam splitter and the polarizer 440 are sequentially arranged along the transmission direction of the incident light. The functions and optical paths of the first wave plate, the beam splitter, the second wave plate and the polarization beam splitter in the system 44 can be referred to the description of the system 41, and are not described herein again.

Alternatively, in system 44, the polarization beam splitter transmits vertically polarized light, and polarizer 440 also transmits vertically polarized light and may absorb horizontally polarized light. Similarly, the polarization splitter transmits horizontally polarized light, and then the polarizer 440 also transmits horizontally polarized light and can absorb vertically polarized light. Therefore, the effect of removing the interference light can be achieved, and the real-image imaging effect obtained by convergence is better.

It is to be understood that, although fig. 3A to 4D are described by taking an imaging in real time as an example, in practical implementations, the optical imaging system of the embodiment of the present application may also be used to form a virtual image, for example, as shown in the scene illustrated in fig. 4E.

Fig. 4E is a schematic view of an exemplary scene in which the optical imaging system provided in the embodiment of the present application forms a virtual image, in this example, the optical elements included in the optical imaging system and the positional relationship of each optical element are similar to those in fig. 4A, and a propagation path of the optical path between each optical element is also similar to that in fig. 4A, which is not repeated here. In the scene illustrated in fig. 4E, the light transmitted by the polarization splitter 450 is scattered, and the convergence of the backward extended lines of the scattered light becomes a virtual image of the object to be imaged.

In summary, the optical imaging system provided in the embodiment of the present application includes a first optical phase modulation element, a first light splitting element, a second optical phase modulation element, and a second light splitting element, which are sequentially arranged according to a transmission direction of an emergent light of an object to be imaged. The incident light of the first optical phase modulation element is polarized light, the first optical phase modulation element and the second optical phase modulation element are quarter-wave plates, and the second light splitting element transmits the polarized light in the first polarization direction and reflects the polarized light in the second polarization direction. In addition, the first light splitting element transmits light from the first optical phase modulation element and reflects light reflected by the second light splitting element. Thus, the polarized light incident on the first optical phase modulation element is subjected to the processing by the first optical phase modulation element, the first light splitting element, and the second optical phase modulation element, and is phase-modulated, and further, the phase-modulated light is reflected by the second light splitting element and finally incident on the first light splitting element, and thereafter, the first light splitting element reflects the light again. In the process that the light ray is reflected twice by the second light splitting element and the first light splitting element, the light ray passes through the second optical phase modulation element twice, and the second optical phase modulation element is a quarter wave plate, so that when the light ray is reflected twice by the second light splitting element and the first light splitting element and then exits to the second light splitting element again, the phase delay of pi is generated, namely the polarization direction of the light ray is rotated by 90 degrees, and at the moment, the second light splitting element can transmit the polarization light with the modulated pi phase. Further, the transmitted light is made to be imaged. Therefore, in the optical imaging system provided in the embodiment of the present application, the first light splitting element supporting transmission and reflection is arranged by utilizing the polarization of light, and the polarized light emitted from the object to be imaged is subjected to phase modulation, so that the light is reflected between the first light splitting element and the second light splitting element, and then the phase of the light is modulated twice by using the second optical phase modulation element again in the light reflection and transmission process, so that the second light splitting element can transmit the light emitted by the second optical phase modulation element for the second time, and further imaging is performed. 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.

For example, the material of the first wave plate and the second wave plate in the systems 41 to 44 may be quartz, calcite, mica, or other crystal supporting birefringence, or may be an optical material with a special microstructure surface.

The spectroscope may be made of glass-based transparent material or plastic-based transparent material.

When the polarization beam splitter is a planar element, the material of the polarization beam splitter may be a microstructure surface material, such as a metal wire grid polarizer, or a material prepared in a manner of supporting optical coating, such as a reflective polarizer (DBEF) or a Polarization Beam Splitter (PBS). When the polarization splitter is a curved surface device, the microstructure surface may be attached to the curved surface during the manufacturing process, for example, the metal wire grid polarization film is attached to the curved surface, or the polarization splitter may be manufactured by optically coating the curved surface, for example, coating a film capable of achieving polarization splitting effect on the curved surface, or attaching a reflective polarizer (DBEF) to the curved surface.

Referring to fig. 5, corresponding to the above, fig. 5 illustrates an imaging apparatus 50, the imaging apparatus 50 comprising a display element 51 and an optical imaging system 52, the optical imaging system 52 being as shown in any of the systems 30 to 44, the display element 51 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 52 is linearly polarized light, and based on this, the display element 51 can be implemented as any of the following: 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 52. 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 52.

In some embodiments, if the imaging device 50 is used for imaging a real image, the distance from the light-emitting surface of the display element 51 to the imaging plane of the real image is greater than or equal to the distance from the light-emitting surface to the second beam splitting element, so as to ensure that the real image is imaged outside the imaging device 50.

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

the incident light of the first optical phase modulation element is polarized light, the second light splitting element transmits the polarized light in a first polarization direction and reflects the polarized light in a second polarization direction, and the first polarization direction is orthogonal to the second polarization direction;

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

the first light splitting element transmits light from the first optical phase modulation element and reflects light reflected by the second light splitting element.

2. The optical imaging system of claim 1,

when the incident light of the first optical phase modulation element is polarized light in the first polarization direction, an included angle between an optical axis of the first optical phase modulation element and an optical axis of the second optical phase modulation element is 0 degree or 180 degrees;

when the incident light of the first optical phase modulation element is the polarized light in the second polarization direction, 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 °.

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 first optical phase modulation element, or a convex surface of the first light splitting element faces the second optical phase modulation element.

5. The optical imaging system of claim 3, wherein if at least one of the first beam splitting element and the second beam splitting element focuses light,

when the convex surface of the first light splitting element faces the first optical phase modulation element, the second light splitting element is a planar element, an element having a convex surface facing the second optical phase modulation element, or an element having a concave surface facing the second optical phase modulation element,

when the second light splitting element is an element having a convex surface facing the second optical phase modulation element, the curvature of the first light splitting element is larger than that of the second light splitting element;

when the first light splitting element is the planar element or the element in which the convex surface of the first light splitting element faces the second optical phase modulation element, the second light splitting element is an element in which the concave surface faces the second optical phase modulation element, and the curvature of the second light splitting element is greater than that of the first light splitting element.

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

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%.

7. The optical imaging system of any one of claims 1 to 5, further comprising: a polarizer,

the polaroid is arranged in the transmission emergent direction of the second light splitting element;

the polarizer transmits the polarized light of the first polarization direction.

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 according to claim 8, 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 images in real, 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 second light splitting element.

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