CN215895139U - Polarization beam splitter and 3D projection light modulation system - Google Patents

Abstract

The utility model is suitable for the technical field of 3D projection, and provides a polarization beam splitter and a 3D projection light modulation system. The polarization beam splitting device comprises a polarization beam splitting prism and two light path direction adjusting assemblies, wherein the polarization beam splitting prism is provided with a first polarization beam splitting film and a second polarization beam splitting film, and the first polarization beam splitting film is used for splitting a first reflected light beam and a first transmitted light beam from an incident light beam; the second polarization beam splitting film is used for splitting a second reflected beam and a second transmitted beam from the incident beam; the first polarization splitting film and the second polarization splitting film are designed to have the same optimal incident angle; one end of the first polarization light splitting film is abutted against one end of the second polarization light splitting film to form a polarization light splitting film vertex angle with an angle alpha, and half of the angle alpha is larger than the optimal incident angle. The polarization beam splitter prism can solve the color cast problem generated after projection light is incident.

Description

Polarization beam splitter and 3D projection light modulation system

Technical Field

The utility model belongs to the technical field of 3D projection, and particularly relates to a polarization beam splitter and a 3D projection light modulation system.

Background

Polarization type 3D cinema equipment has been widely used in China at present, and can be divided into two categories: the system comprises a single-light-path 3D projection light modulation system with the light effect of about 15%, a double-light-path projection light modulation system with the light effect of 28-30% and a three-light-path 3D projection light modulation system.

For the huge projection hall with a screen of about 20 meters, the width of the screen of the hall is basically equal to the projection distance due to the limitation of building structures, wherein the ratio of the projection distance to the width of the screen is called a projection ratio, and the shape of the hall is close to a square when the projection ratio is close to 1: 1. When the three-optical-path 3D projection light modulation system is applied to a cinema with a 1:1 projection ratio, light rays emitted from a projector lens enter an incidence plane of the 3D projection light modulation system at an angle of about +/-15 degrees.

A polarization beam splitter prism in a common three-optical-path 3D projection light modulation system is provided with two polarization beam splitting surfaces which are perpendicular to each other and form an angle of 45 degrees with an incident surface, K9 optical glass with the refractive index of 1.5163 is used as a material of the polarization beam splitter prism, and light is incident to the polarization beam splitting surfaces at an angle of about 45-55 degrees. Because the allowable range of the incident angle of the polarization splitting film matched with the K9 optical glass is small, when light is incident on the polarization splitting film at a slightly larger angle (for example, an incident angle exceeding 57 degrees), the transmittance of the part of light with the longer wavelength in the incident light is obviously reduced, so that the polarization degree of the transmitted P-state polarized light and the reflected S-state polarized light is greatly different when the light with different wavelengths passes through the polarization splitting film, and after being filtered by a subsequent linear polarizer, the proportion of the light with different wavelengths is different, so that the white light is colored, and the color of the projection picture is reddish.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the problem that a polarization splitting prism applied to a 3D projection system has color cast when the incident light angle is large on the basis of not changing the original polarization splitting coating process.

To solve the above technical problem, in a first aspect, the present invention provides a polarization beam splitterThe device comprises: the polarization splitting prism is provided with a first polarization splitting film and a second polarization splitting film, and the first polarization splitting film is used for splitting a first reflected light beam and a first transmitted light beam from an incident light beam; the second polarization beam splitting film is used for splitting a second reflected beam and a second transmitted beam from the incident beam; the first polarization splitting film and the second polarization splitting film are designed to have the same optimal incident angle; one end of the first polarization light splitting film is abutted against one end of the second polarization light splitting film to form a polarization light splitting film vertex angle with an angle alpha, and half of the angle alpha is larger than the optimal incident angle; a first optical path direction adjusting element for adjusting a propagation direction of the first reflected light beam; a second optical path direction adjusting element for adjusting the propagation direction of the second reflected light beam; the angle between the setting direction of the light incident surface of the first light path direction adjusting component and the central axis of the polarization beam splitter prism and the angle between the setting direction of the light incident surface of the second light path direction adjusting component and the central axis of the polarization beam splitter prism are both beta,

further, the cross section of the polarization splitting prism is in the shape of an isosceles trapezoid, and the polarization splitting prism comprises: the first isosceles obtuse angle triangular prism, the second isosceles obtuse angle triangular prism, the first acute angle triangular prism and the second acute angle triangular prism; the cross section of the first isosceles obtuse triangular prism and the cross section of the second isosceles obtuse triangular prism are isosceles triangles of which the vertex angles are obtuse angles, the cross section of the first acute-angle triangular prism and the cross section of the second acute-angle triangular prism are all acute-angle triangles, and the first vertex angle of the first isosceles obtuse-angle triangular prism, the second vertex angle of the second isosceles obtuse-angle triangular prism, the third vertex angle of the first acute-angle triangular prism and the fourth vertex angle of the second acute-angle triangular prism are mutually balanced; the second vertex angle is used as the vertex angle of the polarization splitting film; one side surface of the first isosceles obtuse triangular prism, which is used for forming the first top angle, is consistent in size and attached to one side surface of the first acute triangular prism, which is used for forming the third top angle, and the other side surface of the first isosceles obtuse triangular prism, which is used for forming the first top angle, is consistent in size and attached to one side surface of the second acute triangular prism, which is used for forming the fourth top angle; one side surface of the second isosceles obtuse triangular prism, which is used for forming the second vertex angle, is consistent in size with the other side surface of the first acute triangular prism, which is used for forming the third vertex angle, and the first polarization splitting film is arranged at the joint; the other side surface of the second isosceles obtuse triangular prism, which is used for forming the second vertex angle, is consistent in size with the other side surface of the second acute triangular prism, which is used for forming the fourth vertex angle, and the second polarization splitting film is arranged at the joint; said α ∈ (90 °,120 ° ].

Further, α is 100 °.

Further, the β ∈ [48 °,50 °).

Further, the sum of α and 2 β is less than 360 °.

Further, a bottom surface of the first isosceles obtuse triangular prism, which is opposite to the first vertex angle, is used as a light incident surface of the polarization splitting prism; the bottom surface of the second isosceles obtuse triangular prism, which is opposite to the second vertex angle, is used as the emergent surface of the transmitted light beam of the polarization beam splitter prism; a bottom surface of the first acute angle triangular prism, which is opposite to the third vertex angle, is used as an emergent surface of a first reflected light beam of the polarization beam splitter prism; a bottom surface of the second acute angle triangular prism, which is opposite to the fourth vertex angle, is used as an emergent surface of a second reflected light beam of the polarization beam splitter prism; the transmitted light beam has a first polarization state, the first and second reflected light beams have a second polarization state, and the first and second polarization states are orthogonal.

Furthermore, a lens group is attached to the outer side of the emergent surface of the transmitted light beam, the convex surface of the lens group faces outwards, and the plane opposite to the convex surface is attached to the emergent surface of the transmitted light beam; and a protective prism is attached to the outer side of the light incidence surface.

Further, the angle of the base angle of the second isosceles obtuse triangle is θ 1, the angle of the base angle of the first acute-angle triangular prism adjacent to the second isosceles obtuse triangle is θ 2, and the angle of the base angle of the second acute-angle triangular prism adjacent to the second isosceles obtuse triangle is θ 3, where θ 1 ═ θ 2 ═ θ 3.

In a second aspect, the present invention provides a 3D projection light modulation system comprising:

the polarization beam splitter according to the first aspect, wherein the first transmitted beam and the second transmitted beam obtained by splitting can be spliced into a transmitted beam corresponding to a complete projection image;

the light beam size adjusting component is used for adjusting the size range of the transmitted light beam obtained by the beam splitting of the polarization beam splitting device, and the size of the image projected by the transmitted light beam on the screen after adjustment is consistent with the size of the image spliced by the respective projected images of the first reflected light beam and the second reflected light beam on the screen;

at least one polarization plane rotation component, which is used for adjusting the polarization plane of the transmitted light beam, or adjusting the polarization planes of the first reflected light beam and the second reflected light beam, and the polarization planes of the three adjusted light beams are on the same plane;

the first linear polarizer, the second linear polarizer and the third linear polarizer are respectively positioned on a light path where the transmitted light beam is positioned, a light path where the first reflected light beam is positioned and a light path where the second reflected light beam is positioned, and are used for filtering the transmitted light beam to ensure that the transmitted light beam is completely changed into linearly polarized light;

and the first polarization modulator, the second polarization modulator and the third polarization modulator are respectively positioned behind the first linear polarizer, the second linear polarizer and the third linear polarizer and are used for modulating the filtered transmitted light beam, the first reflected light beam and the second reflected light beam with consistent polarization planes into left circularly polarized light and right circularly polarized light according to a frame sequence.

The polarization light splitting device provided by the utility model does not need to change the film coating process of the polarization light splitting films, and only needs to adjust the vertex angle of the polarization light splitting film between the two polarization light splitting films, so that half of the vertex angle of the polarization light splitting film is larger than the optimal incident angle of the two polarization light splitting films, namely, the included angle between each polarization light splitting film and the horizontal direction is larger than the optimal incident angle of the polarization light splitting film, which is equivalent to enlarging the optimal incident angle of the polarization light splitting films, namely reducing the color cast condition of incident beams with the same incident angle, therefore, under the premise, the obvious color cast can be ensured not to appear by setting the specific size of the vertex angle of the polarization light splitting films. Meanwhile, the arrangement directions of the light incident surfaces of the two light path direction adjusting components are adjusted in a matched manner, so that the reflected light beams and the transmitted light beams can be well superposed on the projection surface.

Drawings

Fig. 1 is a schematic cross-sectional view of a polarization splitting prism provided in a first embodiment;

FIG. 2 is a perspective view of the isosceles obtuse triangular prism of FIG. 1;

FIG. 3 is a perspective view of the acute angle triangular prism of FIG. 1;

FIG. 4 is a schematic cross-sectional view of a modified structure of the polarizing beam splitter prism shown in FIG. 1;

FIG. 5 is a schematic cross-sectional view of a further improved structure of the polarization splitting prism shown in FIG. 1;

fig. 6 is a block diagram of a 3D projection light modulation system provided by a first embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not intended to limit the utility model.

Referring to fig. 1 and 6, the polarization beam splitter mainly includes a polarization beam splitter prism 61, a first optical path direction adjusting component 621, and a second optical path direction adjusting component 622.

The polarization splitting prism 61 has a first polarization splitting film 15 and a second polarization splitting film 16, and the first polarization splitting film 15 is used for splitting a first reflected light beam and a first transmitted light beam from an incident light beam; the second polarization splitting film 16 serves to split a second reflected light beam and a second transmitted light beam from the incident light beam. When the projection screen is finally projected, the first reflected light beam and the second reflected light beam are spliced into a complete image, the first transmitted light beam and the second transmitted light beam are spliced into a complete image, and after beam splitting, the first transmitted light beam and the second transmitted light beam are directly transmitted to the direction of the projection screen, so that the projection screen looks like a large transmitted light beam.

The first polarization splitting film 15 and the second polarization splitting film 16 are designed to have the same optimum incident angle, wherein the "optimum incident angle" means that when the light beam is incident on the polarization splitting films at this angle, the light of each wavelength in the light beam can maintain a relatively high transmittance without color cast.

One end of the first polarization splitting film 15 is abutted against one end of the second polarization splitting film 16 to form a polarization splitting film vertex angle with an angle alpha, and half of the angle alpha is larger than the optimal incident angle.

The first optical path direction adjusting component 621 is used for adjusting the propagation direction of the first reflected light beam, and the adjustment is to make the first reflected light beam propagate toward the screen.

The second optical path direction adjusting component 622 is used to adjust the propagation direction of the second reflected light beam, and the purpose of the adjustment is to make the second reflected light beam propagate toward the screen.

In this embodiment, the included angle between the installation direction of the light incident surface of the first optical path direction adjusting element 621 and the central axis of the polarization splitting prism 61, and the included angle between the installation direction of the light incident surface of the second optical path direction adjusting element 622 and the central axis of the polarization splitting prism 61 are both β,

it can be seen that, the polarization beam splitter provided in the first embodiment of the present invention does not need to change the coating process of the polarization beam splitting films, and only needs to adjust the vertex angle of the polarization beam splitting film between the two polarization beam splitting films, so that half of the vertex angle of the polarization beam splitting film is greater than the optimal incident angles of the two polarization beam splitting films, that is, the included angle between each polarization beam splitting film and the horizontal direction is greater than the optimal incident angle of the polarization beam splitting film, which is equivalent to increasing the optimal incident angle of the polarization beam splitting film, which means reducing the color cast of an incident light beam with the same incident angle, therefore, under the premise, it can be ensured that no obvious color cast occurs by setting the specific size of the vertex angle of the polarization beam splitting film. Meanwhile, the arrangement directions of the light incident surfaces of the two light path direction adjusting components are adjusted in a matched manner, so that the reflected light beams and the transmitted light beams can be well superposed on the projection surface.

Fig. 1 is a schematic cross-sectional view of the prism, with continued reference to fig. 1, the polarization splitting prism comprising: a first isosceles obtuse triangular prism 11, a second isosceles obtuse triangular prism 12, a first acute triangular prism 13, and a second acute triangular prism 14.

The cross section of the first isosceles obtuse triangular prism 11 and the cross section of the second isosceles obtuse triangular prism 12 are isosceles triangles with obtuse vertex angles, the three-dimensional structure is shown in fig. 2, the vertex angles of the isosceles obtuse triangular prisms are formed by two adjacent side faces, and the vertex angles obtained by arbitrarily cutting the cross sections along the length direction of the triangular prisms are equal. The bottom surface and the two side surfaces of the isosceles obtuse triangular prism respectively form two base angles, wherein the bottom surface is opposite to the top angle. In the same way, the base angles at the same position obtained by arbitrarily cutting the cross section along the length direction of the isosceles obtuse angle triangular prism are equal. Two waists and two base angles of the cross section of the isosceles obtuse triangular prism are equal, and with reference to fig. 1, the first vertex angle of the first isosceles obtuse triangular prism 11 is γ 1, the opposite surface is a bottom surface, two surfaces forming the first vertex angle γ 1 are side surfaces, the second vertex angle of the second isosceles obtuse triangular prism 12 is α, the opposite surface is a bottom surface, two surfaces forming α are side surfaces, the value range of α is (90 °,120 °), for example, α may be 100 °, β ∈ [48 °,50 °), and the sum of α and 2 β is required to be less than 360 °. And the second vertex angle is the vertex angle of the polarization splitting film.

The cross section of the first acute angle triangular prism 13 and the cross section of the second acute angle triangular prism 14 are all acute angle triangles, and the three-dimensional structure is as shown in fig. 4, except that the cross section of the first acute angle triangular prism 13 and the cross section of the second acute angle triangular prism 14 are not isosceles. Referring to fig. 1, the third vertex angle of the first acute-angle triangular prism 13 is γ 2, the opposite surface is a bottom surface, the two surfaces forming the third vertex angle γ 2 are side surfaces, the fourth vertex angle of the second acute-angle triangular prism 14 is γ 4, the opposite surface is a bottom surface, and the two surfaces forming the fourth vertex angle γ 4 are side surfaces.

After the four triangular prisms are attached, the first vertex angle gamma 1, the second vertex angle alpha, the third vertex angle gamma 2 and the fourth vertex angle gamma 3 are offset, the first vertex angle gamma 1 is opposite to the second vertex angle alpha, and the third vertex angle gamma 2 is opposite to the fourth vertex angle gamma 3.

The specific attaching mode is as follows: one side surface of the first isosceles obtuse triangular prism 11, which is used for forming the first vertex angle γ 1, is consistent in size and attached to one side surface of the first acute triangular prism 13, which is used for forming the third vertex angle γ 2, and the other side surface of the first isosceles obtuse triangular prism 11, which is used for forming the first vertex angle γ 1, is consistent in size and attached to one side surface of the second acute triangular prism 14, which is used for forming the fourth vertex angle γ 3;

one side surface of the second isosceles obtuse triangular prism 12 used for forming the second vertex angle alpha is consistent in size and is attached to the other side surface of the first acute triangular prism 13 used for forming the third vertex angle gamma 2, a first polarization splitting film 15 is arranged at the attaching position, the other side surface of the second isosceles obtuse triangular prism 12 used for forming the second vertex angle alpha is consistent in size and is attached to the other side surface of the second acute triangular prism 14 used for forming the fourth vertex angle gamma 3, and a second polarization splitting film 16 is arranged at the attaching position.

After the lamination, the cross section of the whole polarization splitting prism is in an isosceles trapezoid shape. The angle of the base angle of the second isosceles obtuse triangle 12 is θ 1, the angle of the base angle of the first acute-angle triangular prism 13 adjacent to the second isosceles obtuse triangle 12 is θ 2, and the angle of the base angle of the second acute-angle triangular prism 14 adjacent to the second isosceles obtuse triangle 12 is θ 3, where θ 1 is θ 2 is θ 3, that is, the first polarization splitting film 15 and the second polarization splitting film 16 correspond to the bisector of the base angle of the entire isosceles trapezoid.

The polarization beam splitter prism described above functions to split an incident unpolarized projection beam into a transmitted beam having a first polarization state, and a first reflected beam and a second reflected beam having a second polarization state, wherein the first polarization state and the second polarization state are orthogonal, for example, the first polarization state may be P-polarized light and the second polarization state may be S-polarized light. In use, the bottom surface of the first isosceles obtuse triangular prism 11 opposite to the first vertex angle γ 1 serves as an incident surface of the projection light of the polarization splitting prism, the bottom surface of the second isosceles obtuse triangular prism 12 opposite to the second vertex angle γ 2 serves as an emergent surface of the transmission light beam of the polarization splitting prism, the bottom surface of the first acute triangular prism 13 opposite to the third vertex angle γ 2 serves as an emergent surface of the first reflection light beam of the polarization splitting prism, and the bottom surface of the second acute triangular prism opposite to the fourth vertex angle γ 3 serves as an emergent surface of the second reflection light beam of the polarization splitting prism.

Further, as shown in fig. 4, a lens group 17 is attached to an outer side of an exit surface of the polarization beam splitter prism, a convex surface of the lens group 17 faces outward, and a plane opposite to the convex surface is attached to the exit surface of the transmitted beam, and the lens group 17 may be used to adjust the size of the transmitted beam.

Further, as shown in fig. 5, a protective prism 18 is attached to the outer side of the light incident surface of the first isosceles obtuse triangular prism 11, so as to facilitate the processing and installation of the entire polarization splitting prism.

Optical glue is adopted for bonding between the first isosceles obtuse triangular prism 11 and the first acute triangular prism 13, between the first isosceles obtuse triangular prism 11 and the second acute triangular prism 14, between the second isosceles obtuse triangular prism 12 and the first acute triangular prism 13, and between the second isosceles obtuse triangular prism 12 and the second acute triangular prism 14, and optical glue can be adopted for bonding the lens group 17 and the protective prism 18.

The second embodiment of the present invention also provides a 3D projection light modulation system, as shown in fig. 6, including:

the polarization beam splitter prism 61 according to the first embodiment is configured to perform polarization beam splitting on an incident beam to obtain a transmitted beam, a first reflected beam, and a second reflected beam, where the transmitted beam has a first polarization state, the first reflected beam and the second reflected beam both have a second polarization state, the first polarization state is orthogonal to the second polarization state, and the first transmitted beam can substantially propagate in a direction where the screen is located, where the transmitted beam is formed by splicing the first transmitted beam and the second transmitted beam in the first embodiment.

The first light path direction adjusting component 621 is configured to adjust a propagation direction of a first reflected light beam obtained by splitting by the polarization splitting prism to a direction in which the screen is located;

and a second optical path direction adjusting component 622, configured to adjust a propagation direction of a second reflected light beam split by the polarization splitting prism to propagate toward a direction in which the screen is located.

The first optical path direction adjusting component 621 and the second optical path direction adjusting component 622 may be implemented by using a mirror, and the reflection angle of the mirror is adjustable, so as to adjust the positions of the first reflected light beam and the second reflected light beam projecting images on the screen.

The beam size adjusting assembly, not shown in the figure, may be specifically built in the polarization beam splitter prism 61, and integrated with the lens group 17, and is configured to adjust a size range of a transmitted beam obtained by splitting by the polarization beam splitter prism, where a size of an image projected by the transmitted beam on the screen after adjustment is consistent with a size of an image obtained by splicing respective projected images of the first reflected beam and the second reflected beam on the screen. When the three beams of light are projected on the screen, the transmission beam can project a complete image, the image projected by the first reflection beam and the image projected by the second reflection beam are spliced to form a complete image, and then the sizes of the two complete images are adjusted to be consistent and the positions of the two complete images are overlapped.

And the polarization plane rotating assembly is used for adjusting the polarization plane of the transmitted light beam, or adjusting the polarization planes of the first reflected light beam and the second reflected light beam, and the adjusted polarization planes of the three light beams are on the same plane, and can be realized by adopting a TN (twisted nematic) liquid crystal box. In fig. 6, a first polarization plane rotation element 631 and a second polarization plane rotation element 632 in two reflected light paths are illustrated as examples.

The first linear polarizer 641, the second linear polarizer 642, and the third linear polarizer 643 are respectively located on the optical path where the transmitted light beam is located, the optical path where the first reflected light beam is located, and the optical path where the second reflected light beam is located, and are configured to filter the transmitted light beam, so that the transmitted light beam is completely linearly polarized, which may be implemented by using a linear polarizer.

The first polarization modulator, the second polarization modulator and the third polarization modulator are respectively positioned behind the first linear polarizer, the second linear polarizer and the third linear polarizer and are used for modulating the filtered transmission light beam, the first reflection light beam and the second reflection light beam with consistent polarization planes into left circularly polarized light and right circularly polarized light according to a frame sequence, and the method can be realized by adopting a liquid crystal modulator. The first polarization modulator, the second polarization modulator, and the third polarization modulator may be pasted together, and one pasted polarization modulator 65 is illustrated in fig. 6.

Further, the 3D projection light modulation system further comprises: and the driving circuit is used for acquiring the synchronous signal from the digital film projector, generating a driving voltage signal according to the synchronous signal and applying the driving voltage signal to the first polarization modulator, the second polarization modulator and the third polarization modulator.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the utility model, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (9)

1. A polarization splitting apparatus, comprising:

the polarization splitting prism is provided with a first polarization splitting film and a second polarization splitting film, and the first polarization splitting film is used for splitting a first reflected light beam and a first transmitted light beam from an incident light beam; the second polarization beam splitting film is used for splitting a second reflected beam and a second transmitted beam from the incident beam; the first polarization splitting film and the second polarization splitting film are designed to have the same optimal incident angle; one end of the first polarization light splitting film is abutted against one end of the second polarization light splitting film to form a polarization light splitting film vertex angle with an angle alpha, and half of the angle alpha is larger than the optimal incident angle;

a first optical path direction adjusting element for adjusting a propagation direction of the first reflected light beam;

a second optical path direction adjusting element for adjusting the propagation direction of the second reflected light beam;

the angle between the setting direction of the light incident surface of the first light path direction adjusting component and the central axis of the polarization beam splitter prism and the angle between the setting direction of the light incident surface of the second light path direction adjusting component and the central axis of the polarization beam splitter prism are both beta,

2. the polarization splitting apparatus according to claim 1, wherein the polarization splitting prism has a cross section in the shape of an isosceles trapezoid, comprising: the first isosceles obtuse angle triangular prism, the second isosceles obtuse angle triangular prism, the first acute angle triangular prism and the second acute angle triangular prism; the cross section of the first isosceles obtuse triangular prism and the cross section of the second isosceles obtuse triangular prism are isosceles triangles of which the vertex angles are obtuse angles, the cross section of the first acute-angle triangular prism and the cross section of the second acute-angle triangular prism are all acute-angle triangles, and the first vertex angle of the first isosceles obtuse-angle triangular prism, the second vertex angle of the second isosceles obtuse-angle triangular prism, the third vertex angle of the first acute-angle triangular prism and the fourth vertex angle of the second acute-angle triangular prism are mutually balanced; the second vertex angle is used as the vertex angle of the polarization splitting film;

one side surface of the first isosceles obtuse triangular prism, which is used for forming the first top angle, is consistent in size and attached to one side surface of the first acute triangular prism, which is used for forming the third top angle, and the other side surface of the first isosceles obtuse triangular prism, which is used for forming the first top angle, is consistent in size and attached to one side surface of the second acute triangular prism, which is used for forming the fourth top angle;

one side surface of the second isosceles obtuse triangular prism, which is used for forming the second vertex angle, is consistent in size with the other side surface of the first acute triangular prism, which is used for forming the third vertex angle, and the first polarization splitting film is arranged at the joint;

the other side surface of the second isosceles obtuse triangular prism, which is used for forming the second vertex angle, is consistent in size with the other side surface of the second acute triangular prism, which is used for forming the fourth vertex angle, and the second polarization splitting film is arranged at the joint;

said α ∈ (90 °,120 ° ].

3. The polarization beam splitter apparatus of claim 2 wherein α is 100 °.

4. A polarization splitting device according to claim 2 or 3, wherein β e [48 °,50 °).

5. A polarization splitting device according to claim 2 or 3, wherein the sum of α and 2 β is less than 360 °.

6. The polarization beam splitter apparatus according to claim 2, wherein a bottom surface of the first isosceles obtuse triangular prism opposite to the first vertex angle serves as a light incident surface of the polarization beam splitter prism;

the bottom surface of the second isosceles obtuse triangular prism, which is opposite to the second vertex angle, is used as the emergent surface of the transmitted light beam of the polarization beam splitter prism;

a bottom surface of the first acute angle triangular prism, which is opposite to the third vertex angle, is used as an emergent surface of a first reflected light beam of the polarization beam splitter prism;

a bottom surface of the second acute angle triangular prism, which is opposite to the fourth vertex angle, is used as an emergent surface of a second reflected light beam of the polarization beam splitter prism;

the transmitted light beam has a first polarization state, the first and second reflected light beams have a second polarization state, and the first and second polarization states are orthogonal.

7. The polarization beam splitter as claimed in claim 6, wherein a lens group is attached to an outer side of the exit surface of the transmitted beam, a convex surface of the lens group is outward, and a plane opposite to the convex surface is attached to the exit surface of the transmitted beam; and a protective prism is attached to the outer side of the light incidence surface.

8. The polarization beam splitter of claim 2 wherein the base angle of the second isosceles obtuse triangle is θ 1, the base angle of the first acute triangular prism adjacent to the second isosceles obtuse triangle is θ 2, and the base angle of the second acute triangular prism adjacent to the second isosceles obtuse triangle is θ 3, wherein θ 1 ═ θ 2 ═ θ 3.

9. A 3D projection light modulation system, comprising:

the polarization beam splitter according to any one of claims 1 to 8, wherein the split first transmitted beam and the split second transmitted beam can be spliced into a transmitted beam corresponding to a complete projection image;

the light beam size adjusting component is used for adjusting the size range of the transmitted light beam obtained by the beam splitting of the polarization beam splitting device, and the size of the image projected by the transmitted light beam on the screen after adjustment is consistent with the size of the image spliced by the respective projected images of the first reflected light beam and the second reflected light beam on the screen;

at least one polarization plane rotation component, which is used for adjusting the polarization plane of the transmitted light beam, or adjusting the polarization planes of the first reflected light beam and the second reflected light beam, and the polarization planes of the three adjusted light beams are on the same plane;

the first linear polarizer, the second linear polarizer and the third linear polarizer are respectively positioned on a light path where the transmitted light beam is positioned, a light path where the first reflected light beam is positioned and a light path where the second reflected light beam is positioned, and are used for filtering the transmitted light beam to ensure that the transmitted light beam is completely changed into linearly polarized light;

and the first polarization modulator, the second polarization modulator and the third polarization modulator are respectively positioned behind the first linear polarizer, the second linear polarizer and the third linear polarizer and are used for modulating the filtered transmitted light beam, the first reflected light beam and the second reflected light beam with consistent polarization planes into left circularly polarized light and right circularly polarized light according to a frame sequence.

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