CN211603818U - Optical element and projection device - Google Patents

Abstract

An optical element for homogenizing a light beam includes a first portion and a second portion. The light beam passes through the first portion and the second portion in sequence. The first portion includes an anisotropic material having a first crystallographic axis, the first crystallographic axis having an axial direction different from the direction of elongation of the optical element. The light-emitting surface of the first portion comprises a first inclined surface, and the first inclined surface is inclined relative to the extending direction. The light incident surface of the second portion comprises a second inclined surface which is parallel to the first inclined surface and arranged corresponding to the first inclined surface. The utility model discloses still provide a projection arrangement who contains this optical element. The optical element and the projection device provided by the utility model can make the color or brightness of the display picture uniform.

Description

Optical element and projection device

Technical Field

The present invention relates to an optical element and a projection apparatus.

Background

The projection device is a display device for generating large-size images, and the development of the technology is continuously progressing. The projection device has an imaging principle of converting an illumination beam generated by an illumination system into an image beam by a light valve, and projecting the image beam onto a projection target (such as a screen or a wall surface) through a projection lens to form a projection image.

However, in the conventional illumination system architecture, a laser light source can be used as the light source of the illumination system, and although the laser beam is a light source with a single polarization direction, the polarization polarity of the laser beam after entering the projection apparatus is destroyed by the optical elements inside the projection apparatus, so that the polarization direction and intensity of the laser beam are unevenly scattered, and the brightness of the display screen is uneven. Particularly, when the projection apparatus is applied to the polarization stereo mode, no matter two projectors (with a polarization element with a fixed polarization state) or one projector (with a polarization element with a changeable polarization state) are used, a polarizer is required to be added outside the lens to generate the image frame required by the stereo image. Thus, the image projected from the lens and the polaroid has the phenomenon of uneven screen color or uneven brightness.

The background section is only provided to aid in understanding the present invention, and therefore the disclosure in the background section may include some known techniques which do not constitute a part of the knowledge of those skilled in the art. The disclosure in the "background" section does not represent that content or the problems which may be solved by one or more embodiments of the present invention are known or appreciated by those skilled in the art prior to the filing of the present application.

SUMMERY OF THE UTILITY MODEL

The utility model provides an optical element and projection arrangement, projection arrangement can make the look of display frame or bright dark even when polarization stereoscopic mode, lets the user observe the stereoscopic display frame of degree of consistency preferred.

Other objects and advantages of the present invention can be further understood from the technical features disclosed in the present invention.

To achieve one or a part of or all of the above or other objects, an embodiment of the present invention provides an optical element for homogenizing a light beam, the optical element including a first portion and a second portion. The light beam passes through the first portion and the second portion in sequence. The first portion includes an anisotropic material having a first crystallographic axis, the first crystallographic axis having an axial direction different from the direction of elongation of the optical element. The light-emitting surface of the first portion comprises a first inclined surface, and the first inclined surface is inclined relative to the extending direction. The light incident surface of the second portion comprises a second inclined surface which is parallel to the first inclined surface and arranged corresponding to the first inclined surface.

To achieve one or a part of or all of the above or other objectives, an embodiment of the present invention provides a projection apparatus, which includes an illumination system, a light valve and a projection lens. The lighting system comprises a light source and the optical element. The light source is used for emitting light beams. The optical element is used for homogenizing the light beam to form an illumination light beam. The light valve is disposed on the transmission path of the illumination beam to modulate the illumination beam into an image beam. The projection lens is configured on the transmission path of the image light beam.

Based on the above, the embodiments of the present invention have at least one of the following advantages or effects. In the optical element or the illumination system or the projection apparatus equipped with the optical element of the present invention, since the first portion of the optical element includes the anisotropic material having the first crystal optical axis, and the extending direction of the optical element is different from the axial direction of the first crystal optical axis, that is, the direction in which the principal ray travels is not parallel to the axial direction of the first crystal optical axis of the first portion, the first portion of the optical element can change the polarization state of the light beam when the light beam having the polarization (linear polarization) passes through the first portion of the optical element. In addition, because the first part of the optical element is provided with the inclined surface, the first part can have the continuously gradually changing thickness, so that the light beam passes through various different optical path lengths in the first part, and the light beam can have various different polarization states after passing through the first part of the optical element. Therefore, when the projection device is in a polarized stereo mode (i.e. the projection lens is additionally provided with the polarizing plate), the color or brightness of the display picture can be uniform, and a user can observe a stereo display picture with better uniformity through the polarized stereo glasses.

Therefore, when the projection device is in a polarized stereo mode (the projection lens is additionally provided with the polarizing plate), the color or brightness of the display picture can be uniform, and a user can observe a stereo display picture with better uniformity through the polarized stereo glasses.

In order to make the aforementioned and other features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1 is a schematic diagram of a projection apparatus according to an embodiment of the present invention.

Fig. 2A is a schematic cross-sectional view of an optical element according to a first embodiment of the present invention.

Fig. 2B and 2C are schematic diagrams of the optical element of fig. 2A at different viewing angles, respectively.

Fig. 3A is a schematic cross-sectional view of an optical element according to a second embodiment of the present invention.

Fig. 3B and 3C are schematic diagrams of the optical element of fig. 3A at different viewing angles, respectively.

Fig. 4A is a schematic cross-sectional view of an optical element according to a third embodiment of the present invention.

Fig. 4B and 4C are schematic views of the optical element of fig. 4A at different viewing angles, respectively.

Fig. 5 is a schematic cross-sectional view of an optical element according to a fourth embodiment of the present invention.

Detailed Description

The foregoing and other features, aspects and utilities of the present invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings. Directional terms as referred to in the following examples, for example: up, down, left, right, front or rear, etc., are simply directions with reference to the drawings. Accordingly, the directional terminology is used for purposes of illustration and is in no way limiting.

Fig. 1 is a schematic diagram of a projection apparatus according to an embodiment of the present invention. Referring to fig. 1, a projection apparatus 200 of the present embodiment includes an illumination system 100, a light valve 210, and a projection lens 220. Illumination system 100 is configured to provide an illumination beam IB. The light valve 210 is disposed on the transmission path of the illumination beam IB to modulate the illumination beam IB into the image beam IMB. The projection lens 220 is disposed on a transmission path of the image beam IMB, and is used for converting the image beam IMB into a projection beam LP and projecting the projection beam LP onto a screen or a wall (not shown) to form an image.

In the technology applied to stereoscopic display, the projection apparatus 200 of the present embodiment can be applied as a polarized stereoscopic image projector. Specifically, when the projection apparatus 200 is in the polarized stereo mode (i.e., a polarizer is disposed outside the projection lens 220 or a polarizer is disposed inside the projection apparatus 200), the projection light beam LP provided by the projection apparatus 200 can pass through the polarizer (not shown) to generate an image frame with a polarized state, so that the user can observe a stereo display frame through polarized stereo glasses, for example, the stereo glasses worn by the user are respectively disposed with two polarization elements for a left-eye lens and a right-eye lens, and the two polarization elements correspond to the image frame with the polarized state generated by the polarizer of the projection apparatus, so that the left eye and the right eye of the user respectively receive the image frame projected by the corresponding projector, thereby achieving the effect of stereo display.

In the present embodiment, the light valve 210 may be a reflective light modulator such as a digital micro-mirror device (DMD) or a liquid-crystal-on-silicon (LCOS) panel, or may be a transmissive light modulator such as a transmissive liquid crystal panel (transmissive liquid crystal panel), an electro-optic modulator (electro-optic modulator), a magneto-optic modulator (magneto-optic modulator), or an acousto-optic modulator (AOM). The present invention is not limited to the number, type and type of the light valves 210.

In the present embodiment, the projection lens 220 is, for example, a combination of one or more optical lenses with diopter, and the optical lenses include, for example, non-planar lenses such as a biconcave lens, a biconvex lens, a meniscus lens, a convex-concave lens, a plano-convex lens, a plano-concave lens, and various combinations thereof. The present invention is not limited to the type and kind of the projection lens 220.

In the present embodiment, the illumination system 100 includes a light source 110 and an optical element 120. The light source 110 is configured to emit a light beam LB. The optical element 120 is disposed on a transmission path of the light beam LB and is configured to homogenize the light beam LB to form an illumination light beam IB. Various embodiments of the optical element 120 will be described in detail in the following fig. 2A to 5.

The Light source 110 may include a Laser Diode (LD), a Light Emitting Diode (LED), or an array or group of one of the two, but the invention is not limited thereto. In the present embodiment, the light source 110 is a laser light emitting element including a laser diode. In addition, the light source 110 may include a plurality of sub-light sources, such that the light beam LB includes a plurality of sub-light beams. For example, the light source 110 may include a plurality of sub-light sources 112 and a plurality of sub-light sources 114, the plurality of sub-light sources 112 are respectively configured to emit a sub-light beam L1, and the sub-light sources 114 are configured to emit a sub-light beam L2, wherein the light beam LB includes a sub-light beam L1 and a sub-light beam L2. It should be noted that the number of sub-light sources in fig. 1 is merely an illustrative example, and the light source 110 may include more or less sub-light sources. For example, in other embodiments, the sub-light sources 114 may be omitted.

For example, the sub-light source 112 may include a Blue Laser diode Bank (Blue Laser diode Bank), the sub-light source 114 may include a Red Laser diode Bank (Red Laser diode Bank), the sub-light beam L1 includes a Blue Laser beam, and the sub-light beam L2 includes a Red Laser beam, but the invention is not limited thereto.

As shown in fig. 1, the illumination system 100 further includes a light combining component 130, an anisotropic diffusion element 140, a wavelength conversion element 150, a light combining element 162, a light combining element 164, a reflective element 172, a reflective element 174, a reflective element 176, and a filter element 180.

The light combining element 130 is disposed on the transmission path of the plurality of sub-beams L1 and is configured to combine the plurality of sub-beams L1. The light combining element 130 may have a plurality of transmissive portions and a plurality of reflective portions alternately arranged, so that the sub-light beam L1 penetrates the light combining element 130 or is reflected by the light combining element 130. Therefore, the light combining component 130 can combine the sub-light beams L1 from the sub-light sources 112 and transmit the combined light beams to the anisotropic diffusion element 140.

The anisotropic diffuser 140 is disposed on the transmission path of the sub-beam L1 from the light combiner 130 to adjust the energy intensity distribution of the light spot of the sub-beam L1, so that the energy intensity distribution of the light spot formed by the sub-beam L1 on the wavelength conversion element 150 is relatively even. For example, the anisotropic diffusion element 140 may be a wedge-shaped element with a slope, but the invention is not limited thereto, and in other embodiments, the anisotropic diffusion element may have other shapes or be not provided with the anisotropic diffusion element.

The wavelength conversion element 150 is disposed on the transmission path of the sub-beam L1 from the anisotropic diffusion element 140. The wavelength conversion element 150 may include a wavelength conversion region (not shown) and a light transmission region (not shown). The wavelength conversion region has a wavelength converting material to convert the sub-beam L1 into an excited beam L3. In the present embodiment, for example, the blue excitation beam is converted into a green beam or a yellow-green beam. The wavelength conversion region and the light transmission region can be sequentially cut into the transmission path of the sub-beam L1. When the light penetration region is cut into the transfer path of the sub-light beam L1, the sub-light beam L1 penetrates the wavelength conversion element 150, and when the wavelength conversion region is cut into the transfer path of the sub-light beam L1, the sub-light beam L1 is converted into the excited light beam L3 by the wavelength conversion region, and the excited light beam L3 can be reflected by the wavelength conversion element 150. In various embodiments, the configuration of the wavelength conversion element 150 may vary according to different types of the illumination system 100, and the present invention is not limited to the configuration and the type of the wavelength conversion element 150.

The light combining element 162 is disposed on the transmission path of the sub-light beam L1 from the anisotropic diffusion element 140, and is disposed between the anisotropic diffusion element 140 and the wavelength conversion element 150. The reflection element 172, the reflection element 174 and the light combining element 164 are disposed on the transmission path of the sub-beam L1 from the wavelength conversion element 150, so as to transmit the sub-beam L1 back to the light combining element 162. The reflection element 176 is disposed on the transmission path of the sub-beam L2 from the sub-light source 114 to transmit the sub-beam L2 to the light combining element 164. Specifically, the light combining element 162 and the light combining element 164 may be a color separation unit, such as a Dichroic Mirror (DM) or a dichroic prism, and may provide different optical effects for light beams of different colors/wavelengths. The light combining element 164 can be designed to transmit the sub-beam L2 to reflect the sub-beam L1, so as to combine the sub-beam L1 from the reflection element 174 with the sub-beam L2 from the reflection element 176 and transmit the combined light to the light combining element 162. The light combining element 162 can be designed to allow the sub-light beams L1 and L2 to penetrate and reflect the stimulated light beam L3, so as to combine the sub-light beams L1 and L2 from the light combining element 164 with the stimulated light beam L3 from the wavelength conversion element 150 and transmit the combined light beam to the filter element 180.

The filter element 180 is disposed between the light combining element 164 and the optical element 120, and has filters with different colors for passing the sub-beam L1, the sub-beam L2, and the excited beam L3 to generate a blue light portion, a red light portion, and a green light portion of the illumination beam LB, respectively. Specifically, in the present embodiment, the filter element 180 is a rotatable color wheel (wheel) device for generating a filtering effect on the sub-beam L1, the sub-beam L2 and the excited beam L3 in time sequence, so that the color purity of the beam passing through the filter element 180 is increased. In different embodiments, the arrangement of the color filters of the filter element 180 may be changed according to different types of the lighting system 100, the present invention is not limited to the arrangement and the type of the filter element 180, and in other light source embodiments, the filter element may not be provided. Specifically, in embodiments where light source 110 does not have sub-light sources 114, the red light portion of illumination beam LB may be provided by the red wavelength band of stimulated light beam L3.

In addition, the illumination system 100 may further optionally include one or more lenses C1 for adjusting the light beam inside the illumination system 100.

In the following paragraphs, different implementation modes of the optical element 120 of the present embodiment will be described in detail, wherein the optical element 120 may be any one of the optical elements 120a to 120d of the first to fourth embodiments.

Fig. 2A is a schematic cross-sectional view of an optical element according to a first embodiment of the present invention. Fig. 2B and fig. 2C are schematic diagrams of the optical device of fig. 2A at different viewing angles, respectively, wherein fig. 2B illustrates a light incident side of the optical device, and fig. 2C illustrates a light exiting side of the optical device. Referring to fig. 2A to 2C, the light beam LB passes through a plurality of optical elements and is transmitted to the optical element 120a, and the polarization state of the light beam is changed to be non-uniform. The optical element 120a of the present embodiment includes a first portion 122 and a second portion 124 a. The light beam LB passes through the first portion 122 and the second portion 124a in sequence. First portion 122 comprises an anisotropic (anistropic) material having a first crystal axis OA1 (indicated in fig. 2B), the axial direction of first crystal axis OA1 being different from the direction of extension ED (indicated in fig. 2A) of optical element 120 a. In the present embodiment, the extending direction ED of the optical element 120a may be the optical axis direction of the optical element 120a or the direction in which the principal ray travels. As shown in fig. 2A, the extending direction ED of the optical element 120a is, for example, the Y direction in fig. 2A. The axis of the first crystal optical axis OA1 is, for example, on the XZ plane in fig. 2A and 2B, and is, for example, about 45 degrees from the X axis, but is not limited thereto. In this embodiment, the material of the first portion 122 of the optical element 120a includes crystalline quartz, or other suitable birefringent (birefringent) crystal.

In the present embodiment, the light incident surface LI1 of the first portion 122 is perpendicular to the extending direction ED of the optical element 120 a. The light exit surface LO1 of the first portion 122 includes a first slope S1, and the first slope S1 is inclined with respect to the extending direction ED of the optical element 120 a. The light incident surface LI2 of the second portion 124a includes a second inclined surface S2, and the second inclined surface S2 is parallel to the first inclined surface S1 and is disposed corresponding to the first inclined surface S1. That is, the first portion 122 of the optical element 120a may have a continuously graded thickness. It should be noted that, in order to increase the effect of improving the polarization state uniformity of the light beam, in some embodiments, the light incident surface LI1 of the first portion 122 may include a light incident inclined surface, which is inclined with respect to the extending direction ED of the optical element 120a, but the present invention is not limited thereto.

Since the first portion 122 of the optical element 120a comprises an anisotropic material having the first crystal optical axis OA1, and the extending direction ED of the optical element 120a is different from the axial direction of the first crystal optical axis OA1, i.e. the direction of the main light beam traveling is not parallel to the axial direction of the first crystal optical axis OA1 of the first portion 122, when the light beam LB having non-uniformly distributed polarization (linear polarization) passes through the first portion 122 of the optical element 120a, the light beam LB may have a plurality of different optical path lengths inside the first portion 122 due to the continuously tapered thickness of the first portion 122 of the optical element 120a, and thus the light beam LB may have a plurality of different and uniformly distributed polarization states after passing through the first portion 122 of the optical element 120 a. In this way, when the projection apparatus 200 is in the polarized stereo mode (i.e., the polarizing plate is disposed outside the projection lens 220 or the polarizing plate is built in the projection apparatus 200), the light beam LB passing through the optical element 120a in the projection apparatus 200 sequentially penetrates through the projection lens 220 and the polarizing plate, and then an image with uniform color and brightness can be generated on the screen, so that a user can observe a stereo display image with better uniformity through the polarized stereo glasses.

It should be noted that the light emitting surface LO1 of the first portion 122 is not limited to include only the first inclined surface S1, and the light incident surface LI2 of the second portion 124a is not limited to include only the second inclined surface S2, as long as the first portion 122 of the optical element 120a has a continuously gradually changing thickness. For example, in other embodiments, the light emitting surface LO1 of the first portion 122 may include a first slope and a third slope inclined at different angles, and the corresponding light incident surface LI2 of the second portion 124a may include a second slope and a fourth slope inclined at different angles.

Further, as shown in fig. 2A to 2C, the second portion 124a of the optical element 120a includes a hollow cylinder 124HC, and an inner surface 124IS of the hollow cylinder 124HC IS a reflective surface, so that the light beam LB passing through the first portion 122 can be reflected on the inner surface 124IS of the hollow cylinder 124HC for multiple times to achieve a homogenization effect, and the hollow cylinder 124HC can be selectively assembled by four reflectors, but the invention IS not limited thereto. In the embodiment, the hollow cylinder 124HC has a light incident end 124LI and a light exit end 124LO, the first portion 122 at least partially abuts against the light incident end 124LI of the hollow cylinder 124HC (at least a portion of the first portion 122 protrudes out of the hollow cylinder 124HC), and the other portion covers an opening surrounded by the light incident end 124LI and extends into the hollow cylinder 124HC, that is, the light exit surface LO1 of the first portion 122 and the light incident surface LI2 of the second portion 124a are located inside the hollow cylinder 124HC of the second portion 124 a. Therefore, the light beam emitted from the light emitting surface LO1 of the first portion 122 can directly enter the second portion 124a, so as to reduce light leakage. It should be noted that, the light incident end 124LI of the second portion 124a refers to an end of the hollow cylinder 124HC close to the first portion 122, so that the light incident end 124LI of the second portion 124a is different from the light incident surface LI2 of the second portion 124 a.

In addition, referring to fig. 2B and fig. 2C, the optical element 120a may further optionally include a housing 126, and the housing 126 is used for accommodating and fixing the first portion 122 and the second portion 124 a. The housing 126 includes a cladding 126WP and an extension 126 EP. The cladding portion 126WP wraps the sidewalls of the first portion 122 and the second portion 124a, and the extension portion 126EP extends from the cladding portion 126WP to cover a peripheral region of the incident surface LI1 of the first portion 122. In addition, the housing 126 includes a resilient tab 126 EE. The elastic piece 126EE is connected to the cladding portion 126WP and abuts against the light emitting end 124LO of the hollow cylinder 124 HC. In addition, the wrapping portion 126WP may have an opening OP1 and/or an opening OP 2. The opening OP1 exposes a portion of the sidewall of the second portion 124 (and/or the first portion 122), and thus can be dispensed in the opening OP1 to strengthen the fixing housing 126 and the second portion 124 (and/or the first portion 122). The opening OP2 exposes a portion of the sidewall of the second portion 124 near the light exit end 124LO, and the opening OP2 may facilitate placing the first portion 122 and the second portion 124a into the housing 126.

It should be noted that, the following embodiments follow the contents of the foregoing embodiments, descriptions of the same technical contents are omitted, reference may be made to the contents of the foregoing embodiments for the same element names, and repeated descriptions of the following embodiments are omitted.

Fig. 3A is a schematic cross-sectional view of an optical element according to a second embodiment of the present invention. Fig. 3B and fig. 3C are schematic diagrams of the optical device of fig. 3A at different viewing angles, respectively, wherein fig. 3B illustrates a light incident side of the optical device, and fig. 3C illustrates a light exiting side of the optical device. Referring to fig. 3A to fig. 3C, the optical element 120b of the present embodiment is similar to the optical element 120a of the first embodiment, and the main difference in the structure is that the second portion 124b of the optical element 120b of the present embodiment is a solid cylinder.

In some embodiments, the second portion 124b of the optical element 120b is made of an isotropic (isotropic) material, such as fused silica, or other suitable light transmissive material. Therefore, the second portion 124b does not have a crystal optical axis.

In other embodiments, second portion 124B of optical element 120B comprises an anisotropic material, such as crystalline quartz, or other suitable birefringent crystal, having a second crystal optic axis OA2 (shown in dashed lines in fig. 3B), and the second crystal optic axis OA2 has an axial direction that is different from the axial direction of first crystal optic axis OA 1. Here, an acute angle sandwiched between the first crystal optical axis OA1 and the second crystal optical axis OA2 may fall in a range of 40 degrees to 50 degrees. For example, the axial direction of the second crystal optical axis OA2 is, for example, also on the XZ plane in the figure, and is, for example, 45 degrees from the first crystal optical axis OA1, but is not limited thereto.

In the present embodiment, the light incident surface LI1 of the first portion 122 of the optical element 120b is perpendicular to the extending direction ED of the optical element 120 b. The light exit surface LO1 of the first portion 122 of the optical element 120b includes a first slope S1, and the first slope S1 is inclined with respect to the extending direction ED of the optical element 120 b. The light incident surface LI2 of the second portion 124a of the optical element 120b includes a second inclined surface S2, and the second inclined surface S2 is parallel to the first inclined surface S1 and is disposed corresponding to the first inclined surface S1. That is, the first portion 122 of the optical element 120b may have a continuously graded thickness. The first portion 122 and the second portion 124b of the optical element 120b are secured together by a housing 126. The first inclined surface S1 (the light emitting surface LO1) of the first portion 122 may be spaced apart from the second inclined surface S2 (the light incident surface LI2) of the second portion 124a, or the first inclined surface S1 (the light emitting surface LO1) of the first portion 122 may be in direct contact with the light incident surface LI2 (the second inclined surface S2) of the second portion 124 a.

Fig. 4A is a schematic cross-sectional view of an optical element according to a third embodiment of the present invention. Fig. 4B and 4C are schematic diagrams of the optical device of fig. 4A at different viewing angles, respectively, wherein fig. 4B illustrates a light incident side of the optical device, and fig. 4C illustrates a light exiting side of the optical device. Referring to fig. 4A to 4C, the optical element 120C of the present embodiment is similar to the optical element 120b of the second embodiment, and the main difference in the structure is that the optical element 120C of the present embodiment further includes a third portion 128. Specifically, the optical element 120c of the present embodiment includes a first portion 122, a second portion 124c, and a third portion 128, and the second portion 124c is a solid cylinder. The second portion 124b of the optical element 120c is located between the first portion 122 and the third portion 128. The light beam LB passes through the first portion 122, the second portion 124c, and the third portion 128 in this order.

In some embodiments, the second portion 124c of the optical element 120c is made of an isotropic material, such as fused silica, or other suitable light transmissive material. Therefore, the second portion 124c does not have a crystal optical axis.

In other embodiments, second portion 124c of optical element 120c comprises an anisotropic material, such as crystalline quartz, or other suitable birefringent crystal, having a second crystal optic axis OA2 (shown in dashed lines in fig. 4B), and the second crystal optic axis OA2 has an axial direction that is different from the axial direction of first crystal optic axis OA 1. Here, an acute angle sandwiched between the first crystal optical axis OA1 and the second crystal optical axis OA2 may fall in a range of 40 degrees to 50 degrees. For example, the axial direction of the second crystal optical axis OA2 is, for example, also on the XZ plane in the figure, and is, for example, 45 degrees from the first crystal optical axis OA1, but is not limited thereto.

In the present embodiment, the third portion 128 includes a hollow cylinder 128HC, the hollow cylinder 128HC has a light incident end 128LI and a light emitting end 128LO, and an inner surface 128IS of the hollow cylinder 128HC IS a reflective surface. The light emitting surface LO2 of the second portion 124c is, for example, perpendicular to the extending direction ED of the optical element 120c, and the second portion 124c abuts against the light incident end 128LI of the hollow cylinder 128 HC.

In the present embodiment, the first portion 122, the second portion 124c and the third portion 128 of the optical element 120b are fixed together by the housing 126. The light incident surface LI1 of the first portion 122 of the optical element 120c is perpendicular to the extending direction ED of the optical element 120 c. The light exit surface LO1 of the first portion 122 of the optical element 120c includes a first slope S1, and the first slope S1 is inclined with respect to the extending direction ED of the optical element 120 c. The light incident surface LI2 of the second portion 124c of the optical element 120c includes a second inclined surface S2, and the second inclined surface S2 is parallel to the first inclined surface S1 and is disposed corresponding to the first inclined surface S1. That is, the first portion 122 of the optical element 120c may have a continuously graded thickness. The light emitting surface LO1 of the first portion 122 may be spaced apart from the light incident surface LI2 of the second portion 124c, or the light emitting surface LO1 of the first portion 122 may be in direct contact with the light incident surface LI2 of the second portion 124 c. The cladding 126WP of the housing 126 cladds the sidewalls of the first, second, and third portions 122, 124c, 128. The elastic piece 126EE of the housing 126 abuts against the light-emitting end 128LO of the hollow cylinder 128 HC. In addition, the opening OP1 of the covering portion 126WP exposes a portion of the sidewall of the first portion 122, the second portion 124c and/or the third portion 128, so that the adhesive can be dispensed in the opening OP1 to strengthen the fixing of the casing 126 and the first portion 122, the second portion 124c and/or the third portion 128. The opening OP2 exposes a portion of the sidewall of the third portion 128 near the light exit end 128LO, and the opening OP2 may facilitate placing the first portion 122, the second portion 124c, and the third portion 128 into the housing 126.

Fig. 5 is a schematic cross-sectional view of an optical element according to a fourth embodiment of the present invention. Referring to fig. 5, an optical element 120d of the present embodiment is similar to the optical element 120b of the second embodiment, and the main difference in the structure is that the first portion 122 and the second portion 124d of the optical element 120d of the present embodiment comprise the same material, and for the sake of manufacturing convenience, they can be manufactured in an integral molding manner. That is, the first portion 122 and the second portion 124d of the optical element 120d are bonded together (e.g., the first inclined surface S1 and the second inclined surface S2 of the second embodiment are bonded together), and both comprise an anisotropic material having a first crystal optical axis OA 1. In the present embodiment, the incident light beam may undergo total internal reflection (total internal reflection) multiple times inside the optical element 120d to achieve the effect of homogenization. In the present embodiment, the maximum length ML of the optical element 120d in the extending direction ED is greater than 25mm, and more preferably greater than 40 mm.

Furthermore, in some embodiments, the light incident surface LI1 of the first portion 122 includes a light incident slope S3, and the light incident slope S3 is inclined with respect to the extending direction ED of the optical element 120 d. The entrance slope S3 helps to improve the polarization state uniformity. The acute angle θ between the incident light slope S3 and the extending direction ED is, for example, less than about 90 degrees and greater than or equal to about 80 degrees, such as 88 degrees, but not limited thereto, as long as the total internal reflection of the light beam in the optical element 120d is not disabled.

In summary, the embodiments of the present invention have at least one of the following advantages or effects. In the optical element or the projection apparatus equipped with the optical element according to the embodiment of the present invention, since the first portion of the optical element includes the anisotropic material having the first crystal optical axis, and the extending direction of the optical element is different from the axial direction of the first crystal optical axis, that is, the direction in which the principal ray travels is not parallel to the axial direction of the first crystal optical axis of the first portion, the first portion of the optical element may change the polarization state of the light beam when the light beam having the polarization (linear polarization) passes through the first portion of the optical element. In addition, since the first portion of the optical element may have a continuously graded thickness, the light beam may have a plurality of different polarization states after passing through the first portion of the optical element by passing through the plurality of different optical path lengths within the first portion. Therefore, when the projection device is in a polarized stereo mode (i.e. the projection lens is additionally provided with the polarizing plate), the color or brightness of the display picture can be uniform, and a user can observe a stereo display picture with better uniformity through the polarized stereo glasses.

However, the above description is only a preferred embodiment of the present invention, and the scope of the present invention should not be limited thereto, that is, all the simple equivalent changes and modifications made according to the claims and the contents of the present invention should be covered by the present invention. Moreover, it is not necessary for any embodiment or claim of the invention to address all of the objects, advantages, or features disclosed herein. Furthermore, the abstract and the utility model name are only used for assisting the retrieval of patent documents and are not used for limiting the scope of rights of the utility model. Furthermore, the terms "first", "second", and the like, as used herein or in the appended claims, are used merely to name elements (elements) or to distinguish between different embodiments or ranges, and are not intended to limit upper or lower limits on the number of elements.

Description of reference numerals:

100 illumination system

110 light source

112. 114 sub-light source

120. 120a, 120b, 120c, 120d optical element

122 first part

124a, 124b, 124c, 124d the second portion

124HC and 128HC hollow column

124IS, 128IS inner surface

124LI, 128LI light-in end

124LO, 128LO light-out end

126 casing

126EE spring plate

126EP extension

126WP a coating part

128 part III

130 light-combining component

140 anisotropic diffusion element

150 wavelength conversion element

162. 164 light-combining element

172. 174, 176 reflective element

180 filter element

200 projection device

210 light valve

220 projection lens

C1 lens

ED the extension direction

IB illuminating beam

IMB image beam

LB beam

LI1 and LI2 light incident surfaces

LO1 and LO2

LP projection light beam

L1, L2 sub-beams

L3 stimulated light Beam

Maximum length of ML

OA1 first Crystal optical axis

OA2 second Crystal optical Axis

OP1, OP2 openings

S1 first inclined plane

S2 second inclined plane

S3 incident light inclined plane

Theta is an acute angle.

Claims (11)

1. An optical element for homogenizing a light beam, the optical element comprising a first portion and a second portion, wherein:

the light beam sequentially passes through the first portion and the second portion, the first portion comprises an anisotropic material with a first crystal optical axis, the axial direction of the first crystal optical axis is different from the extending direction of the optical element, the light emitting surface of the first portion comprises a first inclined surface, the first inclined surface is inclined relative to the extending direction, the light incident surface of the second portion comprises a second inclined surface, and the second inclined surface is parallel to the first inclined surface and is correspondingly arranged with the first inclined surface.

2. An optical element as recited in claim 1, further comprising a housing to house said first portion and said second portion.

3. The optical device according to claim 2, wherein the housing includes an extension portion covering a peripheral region of the light incident surface of the first portion.

4. The optical element of claim 1, wherein the light entrance surface of the first portion comprises a light entrance slope that is inclined with respect to the extending direction of the optical element.

5. An optical element according to claim 1, wherein the first portion is made of an anisotropic material, the second portion comprises a hollow cylinder, and an inner surface of the hollow cylinder is a reflective surface.

6. An optical element according to claim 5, wherein the hollow cylinder has a light entrance end and a light exit end, and the first portion at least partially abuts against the light entrance end of the hollow cylinder.

7. The optical element according to claim 1, further comprising a third portion, wherein the light beam passes through the first portion, the second portion and the third portion in sequence, the second portion is a solid cylinder, the third portion comprises a hollow cylinder having a light-entering end and a light-exiting end, and an inner surface of the hollow cylinder is a reflective surface, wherein the second portion abuts against the light-entering end of the hollow cylinder.

8. The optical element of claim 1, wherein the first portion and the second portion comprise the same material and are integrally formed, the maximum length of the optical element in the extending direction is greater than 25mm, and the light incident surface of the first portion comprises a light incident slope inclined with respect to the extending direction of the optical element.

9. An optical element as recited in claim 1, wherein said second portion is made of an isotropic material.

10. The optical element according to claim 1, wherein the second portion comprises an anisotropic material having a second crystallographic axis, and an axial direction of the first crystallographic axis is different from an axial direction of the second crystallographic axis.

11. A projection apparatus, comprising an illumination system, a light valve, and a projection lens, wherein:

the illumination system is used for forming an illumination beam and comprises a light source and an optical element, wherein:

the light source is used for emitting light beams; and

the optical element is configured on a transmission path of the light beam and is used for homogenizing the light beam to form the illumination light beam, wherein the optical element comprises a first part and a second part, wherein:

the light beam sequentially passes through the first part and the second part, the first part comprises an anisotropic material with a first crystal optical axis, the axial direction of the first crystal optical axis is different from the extending direction of the optical element, the light emitting surface of the first part comprises a first inclined surface, the first inclined surface is inclined relative to the extending direction, the light incident surface of the second part comprises a second inclined surface, and the second inclined surface is parallel to the first inclined surface and is arranged corresponding to the first inclined surface;

the light valve is configured on the transmission path of the illumination light beam to modulate the illumination light beam into an image light beam; and

the projection lens is configured on the transmission path of the image light beam.

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