Polarizing device, light source system, and projection apparatus

Abstract

The embodiment of the present application provides a polarization device, which comprises a light waveguide, a coupling-out grating, a coupling-in grating and a half-wave plate, the light waveguide comprises a first surface and a second surface opposite to each other, and the coupling-out grating comprises a first coupling-out area and a second coupling-out area. The coupling-in grating is used for receiving incident light and transmitting light of a first polarization state, so that the light of the first polarization state is coupled out from the first coupling-out area; and the coupling-in grating is also used for deflecting light of a second polarization state, so that the light of the second polarization state is coupled out from the second coupling-out area. The half-wave plate is used for converting the light of the second polarization state coupled out from the second coupling-out area into the light of the first polarization state. In the process of being coupled into the coupling-in grating, P light components and S light components of the incident light are separated, one of which directly transmits through the light waveguide, and the other is deflected by the coupling-in grating and coupled out from the coupling-out grating, and is utilized after passing through the half-wave plate, so that the S component and the P component are simultaneously applied, and the utilization rate of the incident light can be improved. In addition, the present application also provides a light source system and a projection device.

Description

Technical Field

[0001] This application relates to the field of projection technology, specifically to a polarization device, a light source system, and a projection device. Background Technology

[0002] In related technologies, LCD display devices and silicon-based LCoS display devices both operate under polarized light. Currently, the most common method for obtaining polarized light is using a PBS prism. A PBS prism utilizes the difference in transmittance and reflectance between the s-component and p-component of incident light to decompose natural light into p-polarized and s-polarized light. However, this polarization device typically only allows the use of one type of polarized light, resulting in low light utilization efficiency.

[0003] Some polarization devices also use multiple PBS prisms bonded together, with a polarizing film coated at the bonding interface to transmit p-polarized light and reflect s-polarized light. A half-wave plate (HWP) is added to the polarization exit surface, thus converting all the incident unpolarized light into single s- or p-light, which then exits in the same direction, resulting in higher utilization of single-polarized light. However, this method requires bonding multiple PBS prisms, and to ensure high polarization conversion efficiency, the optical processing, bonding, and coating of the PBS prisms are crucial, leading to a complex manufacturing process and higher costs. Summary of the Invention

[0004] The purpose of this application is to provide a polarization device, a light source system, and a projection device to improve the above-mentioned problems.

[0005] In a first aspect, embodiments of this application provide a polarization device, including an optical waveguide, a coupling-out grating, a coupling-in grating, and a half-wave plate. The optical waveguide includes a first surface and a second surface facing away from each other. The coupling-out grating is disposed on the first surface and includes a first coupling-out region and a second coupling-out region. The coupling-in grating is disposed on the second surface and is used to receive incident light and transmit a first polarized state light in the incident light, so that the first polarized state light is coupled out from the first coupling-out region. The coupling-in grating is also used to deflect a second polarized state light in the incident light, so that the second polarized state light is coupled out from the second coupling-out region. The half-wave plate is disposed adjacent to the second coupling-out region and is used to convert the second polarized state light coupled out from the second coupling-out region into first polarized state light.

[0006] In some implementations, both the input grating and the output grating are oblique gratings.

[0007] In some implementations, the coupling grating for the T of the second polarized light -1 The T1-order transmittance of the coupling grating to the second polarized light has a higher diffraction rate. -1 Higher-order transmission has a higher diffraction rate; or

[0008] The T1 order transmittance T of the coupled grating for the second polarized light -1 The first-order transmission has a higher diffraction rate, and the coupling grating has a higher T-value for the second polarized light. -1 The T1 level transmission has a higher diffraction rate than the T1 level transmission.

[0009] In some embodiments, the coupling grating is configured to receive incident light incident perpendicular to the first surface, and the edge of the half-wave plate near the first coupling region is disposed corresponding to the edge of the incident light.

[0010] In some implementations, the thickness d of the optical waveguide is determined by tan(θ) = a / d, where θ is the diffraction angle of the coupled grating and a is the width of the incident light.

[0011] In some implementations, the diffraction angle of the coupling grating is determined in the following manner:

[0012] sin(θ)=λ / (n*Λ)

[0013] Where θ is the diffraction angle of the coupled grating, λ is the wavelength of the incident light, Λ is the grating period, and n is the refractive index of the optical waveguide.

[0014] So that the second polarized light coupled from the second coupling region and the first polarized light coupled from the first coupling region are spliced ​​together to form a combined light.

[0015] In some implementations, the diffraction angle of the coupled grating is determined by sin(θ) = λ1 / (n*Λ), where θ is the diffraction angle of the coupled grating, λ1 is the minimum wavelength of the incident light, Λ is the grating period, and n is the refractive index of the optical waveguide.

[0016] In some implementations, the thickness d of the optical waveguide is determined in the following manner:

[0017] d*tan(θ1)=d*tan(θ0)+a

[0018] Where sin(θ0)=sin(Δθ / 2) / n, sin(θ1)=(λ1-n*sin(Δθ / 2)) / (n*Λ), λ1 is the minimum wavelength of the incident light, Λ is the grating period, n is the refractive index of the optical waveguide, Δθ is the divergence angle of the incident light, and a is the width of the incident light illuminating the coupled grating.

[0019] In some implementations, the offset of the half-wave plate 400 relative to the side of the incident light away from the half-wave plate 400 is Δx = d*tan(θ1).

[0020] In some implementations, the aperture of the half-wave plate is D = d*(tan(θ2) - tan(θ0)).

[0021] Secondly, embodiments of this application also provide a light source system, including a light source and the aforementioned polarization device, wherein the light source is used to emit incident light.

[0022] Thirdly, embodiments of this application also provide a projection device, including the aforementioned light source system.

[0023] The polarization device provided in this application separates the P-component and S-component during the coupling process of incident light through the coupling grating on two opposing surfaces of the optical waveguide. One component passes directly through the optical waveguide, while the other is deflected by the coupling grating and coupled out through the coupling grating. After passing through a half-wave plate, it is utilized, thus achieving simultaneous application of the S-component and P-component. This significantly improves the utilization rate of the incident light, and the entire polarization device has a relatively simple structure and small size.

[0024] The use of the aforementioned polarization device in light source systems and projection equipment can improve the utilization rate of incident light while reducing manufacturing costs.

[0025] These or other aspects of this application will become more apparent in the following description of the embodiments. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is the optical path diagram of grating diffraction shown in this application.

[0028] Figure 2 This is a schematic diagram of the structure of a polarization device provided in an embodiment of this application.

[0029] Figure 3 This is an optical path diagram of a polarization device provided in an application scenario according to an embodiment of this application.

[0030] Figure 4 This is an optical path diagram of a polarization device provided in this application embodiment under another application scenario.

[0031] Figure 5 This is an optical path diagram of a polarization device provided in this application embodiment in another application scenario.

[0032] Figure 6 This application provides a polarization device in an embodiment of the present application. Figure 5 The diagram shows the optical path in the application scenario.

[0033] Figure 7 This is a schematic diagram of the structure of a light source system provided in an embodiment of this application. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0035] A grating is an optical dispersive element that spatially and periodically modulates the amplitude or phase of an incident light wave. Generally, gratings possess good diffraction and beam-splitting properties; that is, when a beam of light passes through a grating, it is split into beams of different diffraction orders, each with a different diffraction angle, thus enabling the grating to perform diffraction and beam-splitting. For example... Figure 1 As shown in (a), light passing through the grating is split into three orders: 0th, +1st, and -1st. When light is incident perpendicularly to the grating plane, the diffraction angle θ of different orders can be determined by the grating equation Λsinθ=mλ, where m is the diffraction order, λ is the incident light wavelength, and Λ is the grating period. The grating period refers to the spacing between adjacent smallest unit cells of the grating, typically measured in nm. Figure 1 As shown in (b), when the incident light is incident at an angle of i, the grating equation should be modified to Λ(sini±sinθ)=mλ. When considering the spectrum on the same side as the incident light, the formula takes a positive sign; otherwise, it takes a negative sign.

[0036] Based on this, the inventors of this application have proposed a polarization device, a light source system, and a projection device in the embodiments of this application to improve the light utilization efficiency of the polarization device. The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0037] First Embodiment

[0038] like Figure 2 As shown, this embodiment provides a polarization device 20, including an optical waveguide 100, a coupling grating 200, a coupling grating 300, and a half-wave plate 400. The coupling grating 200 and the coupling grating 300 are both disposed on the optical waveguide 100 and located on two opposite surfaces of the optical waveguide 100. The half-wave plate 400 is disposed adjacent to the coupling grating 300.

[0039] Specifically, the optical waveguide 100 includes a first surface 110 and a second surface 120 facing away from each other. The first surface 110 and the second surface 120 are substantially parallel to each other. The optical waveguide 100 can provide a means for propagating light. A coupling grating 200 is disposed on the second surface 120, and a coupling grating 300 is disposed on the first surface 110. Incident light is incident towards the coupling grating 200, and the incident light includes light in a first polarization state (e.g., light with a first polarization state). Figure 2 Light rays in the horizontal polarization direction (indicated by arrows) and light in the second polarization state (such as...) Figure 2 A ray of light perpendicular to the plane of the paper is represented as a dot.

[0040] To improve the diffraction efficiency of the coupling grating 200 for the second polarized light, the coupling grating 200 can be a slanted grating. The coupling grating 200 receives the incident light, transmits the first polarized light in the incident light, and deflects the second polarized light in the incident light, thus separating the first and second polarized light and causing them to exit along different paths. The first polarized light can be either S-polarized or P-polarized, and correspondingly, the second polarized light can be either P-polarized or S-polarized; no specific limitation is made here.

[0041] like Figure 2 As shown, this example uses P-polarized light as the first polarization state and S-polarized light as the second polarization state. When the incident light is incident on the coupling grating 200, since the P and S components of the incident light have different diffraction directions at their high diffraction efficiency orders after passing through the coupling grating 200, the first and second polarization states can be separated. At this time, the transmission T0 order diffraction efficiency of the first polarization state light is relatively high, and it still passes through the optical waveguide 100 along the original incident path. The transmission T1 order and transmission T2 order diffraction efficiency of the second polarization state light are relatively high. -1 The first-order diffraction efficiency is relatively high, therefore the second polarized light mainly follows T1 or T2. -1 The light propagates along a path and is deflected relative to the original incident light direction.

[0042] It should be noted that by adjusting parameters such as the grating tilt angle, thickness, duty cycle, and refractive index of the coupling grating 200, the T0-order diffraction efficiency of the coupling grating 200 for P-polarized light (i.e., the first polarization state light) can be improved, and the T1-order or T2-order transmission efficiency for S-polarized light (i.e., the second polarization state light) can be improved. -1 The stage has high diffraction efficiency. For this scheme, the coupled grating 200 transmits S-polarized light through the T1 stage or transmits it through the T stage. -1 High diffraction efficiency is feasible for all stages. The coupling grating 200 can be a surface relief grating, which can be fabricated using processes such as etching / nanoimprinting.

[0043] The coupling grating 300 includes a first coupling region and a second coupling region. The first coupling region and the second coupling region can be adjacent regions. Light of the first polarization state is coupled out from the first coupling region after being guided by the optical waveguide 100, and light of the second polarization state is coupled out from the second coupling region after being guided by the optical waveguide 100.

[0044] The output grating 300 can adopt the same structure and fabrication process as the input grating 200. Thus, because the T0-order diffraction efficiency of the first polarized light is high, it mainly exits along the original path. Therefore, the output grating 300 can be configured such that the T0-order diffraction efficiency of the P-polarized light (i.e., the first polarized light) is high. After propagation through the optical waveguide 100, the direction of the first polarized light remains unchanged when it reaches the first output region of the output grating 300. When passing through the first coupling region, it can maintain a high transmission T0-order diffraction efficiency. Therefore, the first polarized light maintains the same propagation direction as the incident light when passing through the output grating 300. The second polarized light, due to its high transmission T1-order and T2-order diffraction efficiency, continues to propagate along the original path. -1 The second polarization light has a higher diffraction efficiency, so its propagation direction in the optical waveguide 100 is tilted relative to the second surface 120. When the second polarization light is incident on the coupling grating 300, it is coupled out from the second coupling region after being diffracted by the coupling grating 300.

[0045] To ensure that the second polarized light, after diffraction by the coupling grating 300, exits the second coupling region in a manner approximately perpendicular to the first surface 110, the coupling grating 300 is also configured as a slanted grating. Furthermore, the coupling grating 300 is set such that when the transmission efficiency T1 of the coupling grating 200 for the second polarized light is high, the transmission efficiency T1 of the coupling grating 300 for the second polarized light is also high. -1 High efficiency; or, it can make the transmission T of the second polarized light coupled into the grating 200 more efficient. -1 When the efficiency is high, the transmission efficiency T1 of the coupling grating 300 for the second polarized light is also high. This ensures that after diffraction by the coupling grating 300, the second polarized light can exit perpendicularly to the first surface 110. In this way, the first polarized light and the second polarized light can remain parallel and exit in the same direction when they exit the coupling grating 300.

[0046] A half-wave plate 400 is disposed adjacent to the second coupling region and is used to convert the second polarized light coupled from the second coupling region into the first polarized light. This allows the second polarized light in the incident light to be converted into the first polarized light for utilization. Since the first polarized light and the second polarized light are coupled from different regions of the coupling grating 300, the half-wave plate 400 only converts the second polarized light into the first polarized light and does not affect the first polarized light. The first polarized light formed after conversion by the half-wave plate 400 is emitted together with the first polarized light that directly passes through the first coupling region, and both can be used. Therefore, the polarization device 20 provided in this embodiment can improve the utilization rate of the incident light and reduce costs.

[0047] Furthermore, in order to combine the first polarized light that directly passes through the first coupling region and the first polarized light that is converted by the half-wave plate 400, the edge of the half-wave plate 400 near the first coupling region is set to correspond to the edge of the incident light. This ensures that the first polarized light that propagates in the original incident light outgoing direction will not enter the half-wave plate 400.

[0048] Furthermore, the width 'a' of the incident beam, the thickness 'd' of the optical waveguide 100, and the diffraction angle 'θ' of the coupling grating 200 can be rationally designed, where the thickness 'd' of the optical waveguide 100 refers to the distance between the first surface 110 and the second surface 120. In one embodiment, such as... Figure 3 As shown, taking incident light that is completely perpendicular to the second surface 120 and incident on the coupling grating 200 as an example, the optical path is analyzed. The beam width a of the incident light, the thickness d of the optical waveguide 100, and the diffraction angle θ of the coupling grating 200 should satisfy the relationship tan(θ)=a / d. Therefore, d can be determined in the above way. When the beam width of the incident light is clear, the design parameters of the optical waveguide 100 can be determined. At the same time, the diffraction angle of the coupling grating 200 is determined in the following way:

[0049] sin(θ)=λ / (n*Λ)

[0050] Where θ is the diffraction angle of the coupling grating 200, λ is the wavelength of the incident light, Λ is the grating period, and n is the refractive index of the optical waveguide 100. By reasonably controlling the thickness of the optical waveguide 100 and parameters such as the grating period and diffraction angle, the first polarized light directly passing through the first coupling region and the first polarized light formed after conversion by the half-wave plate 400 can be combined into a single beam.

[0051] In another implementation, such as Figure 4As shown, the wavelength of the incident light is not completely fixed, but exists within a certain wavelength range. Assuming the wavelength range of the incident light is λ1 to λ2, the minimum diffraction angle after the beam passes through the coupling grating 200 is θ1 = arcsin(λ1 / (n*Λ)), and the maximum diffraction angle is θ2 = arcsin(λ2 / (n*Λ)). To ensure that the two beams split by the incident light after passing through the optical waveguide 100 can be precisely joined into one beam, the T-wave angle of the S-polarized light after the λ1 light beam diffracts through the coupling grating 200 needs to be... -1 The rightmost ray of the T0 order of the P-polarized light intersects exactly on the exit surface (i.e., the first surface 110). Therefore, the width a of the incident beam, the thickness d of the optical waveguide 100, and the diffraction angle θ of the coupling grating 200 should satisfy: sin(θ)=λ1 / (n*Λ), tan(θ1)=a / d. From the above, the thickness d of the optical waveguide 100 can be determined. By reasonably controlling the thickness of the optical waveguide 100 and parameters such as the grating period and diffraction angle, even when the wavelength of the incident light fluctuates, the first polarized light directly passing through the first coupling region and the first polarized light formed after conversion by the half-wave plate 400 can combine to form a single beam.

[0052] In another implementation, please refer to [the relevant documentation]. Figure 5 and Figure 6 If the incident light is not perfectly collimated and incident on the second surface 120, but has a certain divergence angle Δθ and is symmetrically distributed left and right, and the wavelength range of the beam is λ1~λ2, then the λ1 ray in the incident light needs to be coupled into the grating 200S polarized light T. -1 The rightmost ray of the T0 order and the leftmost ray of the T0 order polarized light intersect exactly on the exit surface (i.e., the first surface 110). At this point, the incident angle of the light is Δθ / 2. Based on the law of refraction and the grating equation, the angles of incidence of the leftmost ray of the T0 order and the leftmost ray of the T0 order can be calculated. -1 The deflection angles θ0 and θ1 of the rightmost light ray.

[0053] d*tan(θ1)=d*tan(θ0)+a,

[0054] Among them, sin(θ0)=sin(Δθ / 2) / n, sin(θ1)=(λ1-n*sin(Δθ / 2)) / (n*Λ).

[0055] In addition, the offset Δx of the half-wave plate 400's position and the aperture D of the half-wave plate 400 also need to be considered. Δx refers to the offset of the half-wave plate 400 relative to the side of the incident light furthest from the half-wave plate 400. Figure 6 As shown, this represents the offset of the half-wave plate 40° relative to the rightmost side of the incident light. To ensure that only T... -1When light of the second polarization state is converted to light of the first polarization state, the half-wave plate 40° should be placed precisely on the λ1 ray T. -1 Δx can be calculated from the exit position of the rightmost ray of the order.

[0056] Simultaneously, to ensure maximum polarization conversion efficiency, the T polarization of the S-polarized light in the incident light, λ2 ray, is also required. -1 The second polarized light on the far left of the stage can be converted into the first polarized light through the half-wave plate 40°, and Δx must satisfy:

[0057] Δx = d*tan(θ1)

[0058] D = d*(tan(θ2) - tan(θ0))

[0059] sin(θ2)=(λ2+n*sin(Δθ / 2)) / (n*Λ)

[0060] In a more specific embodiment, assuming the incident light wavelength λ is 525±7nm, the beam divergence angle Δθ is 10°, the waveguide refractive index n is 1.71, the grating period Λ of the coupling grating 200 is approximately 430nm, and the spot size a incident on the coupling grating 200 varies with the distance from the light source 30 to the coupling grating 200, assuming its range is 1–5mm. Then, according to the aforementioned formula, d is 1.06–5.3mm, D is 1.06–5.3mm, and Δx is 1.05–5.24mm.

[0061] It should be noted that the above are only some of the embodiments. In other embodiments, the aperture of the half-wave plate 400 can also be set to be larger. In this case, it is only necessary to ensure that the edge of the half-wave plate 400 near the first coupling region corresponds to the edge of the incident light.

[0062] The polarization device 20 provided in the above embodiment can not only convert the second polarized light into the first polarized light, improving the utilization rate of the incident light, but also allow the converted first polarized light and the first polarized light directly transmitted through the coupling grating 300 to be combined and emitted as a beam of light, which is beneficial for the subsequent utilization of the formed first polarized light.

[0063] It is understandable that, although in the above embodiments, only the T of the second polarized light coupled into the grating 200 is considered. -1 The case of high diffraction efficiency for the T1 order of the second polarized light has been introduced. However, it should be understood that by adjusting the tilt angle and tilt direction of the coupling grating 200, it is also feasible for the coupling grating 200 to have high diffraction efficiency for the T1 order of the second polarized light. In this case, correspondingly, by changing the tilt angle and tilt direction of the coupling grating 300, the T1 order of the coupling grating 300 can achieve high diffraction efficiency for the second polarized light. -1 The stage only needs to have high diffraction efficiency.

[0064] This embodiment also provides a projection device, which includes a light source system 10 for generating polarized light. For details, please refer to [link to relevant documentation]. Figure 7 The light source system 10 includes a light source 30 and the aforementioned polarization device 20. The light source 30 can be, for example, a laser light source 30, such as a blue laser light source, a red laser light source, a yellow laser light source, etc. The structure of the polarization device 20 can be referred to the above description and will not be repeated here. The light source 30 emits incident light, which is incident on the coupling grating 200 of the polarization device 20. The coupling grating 200 deflects the second polarization state light in the incident light and separates it from the first polarization state light. The first polarization state light passes directly through the optical waveguide 100 and through the first coupling region. The second polarization state light is coupled out from the second coupling region and converted into the first polarization state light by the half-wave plate 400, forming polarized light with only one polarization state, which enters the subsequent components of the projection device. The subsequent components can be, for example, an optical engine, a lens, etc., which will not be described in detail here.

[0065] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A polarization device, characterized by, The application relates to a polarization device, comprising: an optical waveguide comprising a first surface and a second surface opposite to each other; a coupling-out grating arranged on the first surface, the coupling-out grating comprising a first coupling-out area and a second coupling-out area; a coupling-in grating arranged on the second surface, the coupling-in grating being configured to receive incident light and transmit light of a first polarization state in the incident light to be coupled out from the first coupling-out area, and to deflect light of a second polarization state in the incident light to be coupled out from the second coupling-out area; a half-wave plate arranged adjacent to the second coupling-out area and configured to convert the light of the second polarization state coupled out from the second coupling-out area into the light of the first polarization state.

2. The polarizing device of claim 1, wherein The coupling-in grating and the coupling-out grating are both slanted gratings.

3. The polarizing device of claim 2, wherein T1 order transmission of the second polarization state light is higher than T0 order transmission of the second polarization state light -1 T1 order transmission has a higher diffraction rate, and T1 order transmission of the second polarization state light by the out-coupling grating is higher than T0 order transmission of the second polarization state light by the out-coupling grating -1 T1 order transmission has a higher diffraction rate; or The in-coupling grating has a T1 order transmission ratio T -1 The out-coupling grating has a T1 order transmission ratio T -1 The out-coupling grating has a T1 order transmission ratio T 4. A polarizing device according to any one of claims 1-3, characterized in that The coupling-in grating is configured to receive the incident light incident perpendicularly to the first surface, and an edge of the half-wave plate close to the first coupling-out area is arranged corresponding to an edge of the incident light.

5. The polarizing device of claim 4, wherein A thickness d of the optical waveguide is determined by tan (theta) = a / d, wherein theta is a diffraction angle of the coupling-in grating, and a is a width of the incident light.

6. The polarizing device of claim 5, wherein The diffraction angle of the coupling-in grating is determined by sin (theta) = lambda / (n*Lambda), wherein theta is the diffraction angle of the coupling-in grating, lambda is a wavelength of the incident light, Lambda is a grating period, and n is a refractive index of the optical waveguide. The light of the second polarization state coupled out from the second coupling-out area and the light of the first polarization state coupled out from the first coupling-out area are spliced to form combined light. The diffraction angle of the coupling-in grating is determined by sin (theta) = lambda1 / (n*Lambda), wherein theta is the diffraction angle of the coupling-in grating, lambda1 is a minimum wavelength of the incident light, Lambda is the grating period, and n is the refractive index of the optical waveguide. The thickness d of the optical waveguide is determined by d*tan (theta1) = d*tan (theta0) + a, wherein sin (theta0) = sin (Delta theta / 2) / n, sin (theta1) = (lambda1-n*sin (Delta theta / 2)) / (n*Lambda), lambda1 is the minimum wavelength of the incident light, Lambda is the grating period, n is the refractive index of the optical waveguide, Delta theta is a divergence angle of the incident light, and a is a width of the incident light irradiated on the coupling-in grating.

7. The polarizing device of claim 5, wherein An offset of the half-wave plate 400 relative to a side of the incident light far away from the half-wave plate 400 is Delta x = d*tan (theta1).

8. The polarizing device of claim 4, wherein, An optical aperture D of the half-wave plate is D = d*(tan (theta2)-tan (theta0)). The application relates to a light source system, comprising: a light source configured to emit incident light; and 9. The polarizing device of claim 8, wherein, a polarization device according to any one of claims 1-10.

10. A polarizing device according to claim 8 or 9, characterized in that The application relates to a light source system according to claim 11.

11. A light source system, characterized by ​ ​ ​ 12. A projection apparatus, characterized by comprising: ​

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