A projection optical system

Abstract

The present application discloses a projection optical system. In the projection optical system, a light source is used to emit an illumination beam, and the illumination beam includes a plurality of sub-beams; a light splitting and light combining device includes a light splitting surface and a light combining surface, and the light splitting surface is used to split each sub-beam into a first sub-beam and a second sub-beam, and the first sub-beam and the second sub-beam are incident on the light combining surface after being emitted from the light splitting surface for an odd number of reflections, wherein the incident angle of any sub-beam in the illumination beam to the light splitting surface is equal or substantially equal to the incident angle of the first sub-beam and the second sub-beam corresponding to the sub-beam to the light combining surface. In this way, the light energy loss of the illumination beam during light splitting and light combining can be reduced.

Description

Technical Field

[0001] The present application relates to the field of optical technology, and in particular to a projection optical system. Background Art

[0002] In the field of mid- and low-end cinema projectors and high-end engineering projectors, users have a great demand for dual-chip optical engines. Compared with three-chip high-end projectors, dual-chip optical engines can maintain 12-bit projection grayscale while reducing costs; compared with single-chip engineering projectors, dual-chip optical engines can achieve higher brightness and grayscale. Therefore, for dual-chip optical engine systems, only by achieving higher optical efficiency can their advantages be reflected.

[0003] The inventors of the present application discovered during a long research and development process that, in the prior art, incident light in a dual-chip optical engine suffers from spectral loss during the light splitting and light combining process, and the light energy utilization rate is low. Summary of the invention

[0004] The main technical problem solved by the present application is to provide a projection optical system, which can reduce the light loss during light splitting and light combining, thereby improving the output brightness of the projection optical system.

[0005] In order to solve the above technical problems, a technical solution adopted in the present application is: the projection optical system includes: a light source, a light splitting and light combining device, a first spatial light modulator, and a second spatial light modulator; the light source is used to emit an illumination light beam, and the illumination light beam includes multiple sub-beams; the light splitting and light combining device includes a light splitting surface and a light combining surface, and the multiple sub-beams are incident on the light splitting surface at different incident angles, and the light splitting surface is used to split each of the sub-beams into a first sub-beam and a second sub-beam, the first spatial light modulator is used to modulate the first sub-beam emitted from the light splitting surface, and the second spatial light modulator is used to modulate the second sub-beam emitted from the light splitting surface, and the light combining device is used to modulate the second sub-beam emitted from the light splitting surface. The surface is used to synthesize the first sub-beam emitted after modulation by the first spatial light modulator and the second sub-beam emitted after modulation by the second spatial light modulator into an output light beam, wherein the first sub-beam and the second sub-beam are both reflected an odd number of times after being emitted from the beam-splitting surface and then incident on the light-combining surface; the difference between the incident angle of any one of the sub-beams in the illumination beam to the beam-splitting surface and the incident angle of the first sub-beam corresponding to the sub-beam to the light-combining surface is less than a preset threshold value, and the difference between the incident angle of any one of the sub-beams in the illumination beam to the beam-splitting surface and the incident angle of the second sub-beam corresponding to the sub-beam to the light-combining surface is less than the preset threshold value.

[0006] Wherein, the light splitting surface and the light combining surface are located on the same plane.

[0007] Wherein, both the first spatial light modulator and the second spatial light modulator are reflective spatial light modulators.

[0008] In which, the light splitting and light combining device includes a first guiding component and a second guiding component; the first guiding component is used to guide the first sub-beam emitted from the light splitting surface to the first spatial light modulator after M reflections, and guide the first sub-beam emitted after modulation by the first spatial light modulator to the light combining surface after N reflections, wherein M is a positive integer greater than or equal to 1, N is a positive integer greater than or equal to 1, and the sum of M and N is an even number greater than or equal to 2; the second guiding component is used to guide the second sub-beam emitted from the light splitting surface to the second spatial light modulator after X reflections, and guide the second sub-beam emitted after modulation by the second spatial light modulator to the light combining surface after Y reflections, wherein X is a positive integer greater than or equal to 1, Y is a positive integer greater than or equal to 1, and the sum of X and Y is an even number greater than or equal to 2.

[0009] Wherein, the first guiding component and the second guiding component are adjacent to each other, and the light splitting surface and the light combining surface are located on the plane where the first guiding component and the second guiding component are adjacent to each other.

[0010] Among them, the first guiding component includes a first prism and a second prism arranged adjacent to each other, and the second guiding component includes a third prism and a fourth prism arranged adjacent to each other; the surface adjacent to the first prism and the third prism is the beam-splitting surface, and the surface adjacent to the second prism and the fourth prism is the light-combining surface; the surface adjacent to the first prism and the second prism is the first surface, and the second prism also includes the second surface; the surface adjacent to the third prism and the fourth prism is the third surface, and the fourth prism also includes the fourth surface; the first sub-beam emitted from the beam-splitting surface is reflected by the first surface and then incident on the first spatial light modulator, and the first sub-beam emitted after being modulated by the first spatial light modulator is reflected by the second surface and then incident on the light-combining surface; the second sub-beam emitted from the beam-splitting surface is reflected by the third surface and then incident on the second spatial light modulator, and the second sub-beam emitted after being modulated by the second spatial light modulator is reflected by the fourth surface and then incident on the light-combining surface.

[0011] Wherein, the light splitting and combining device further includes a fifth prism, the fifth prism is arranged adjacent to the second prism, and the fifth prism is used to guide the outgoing light beam to emerge.

[0012] In which, the light-splitting and light-combining device also includes a light-splitting component, and the light-splitting component includes the light-splitting surface. The first guiding component includes a sixth prism and a seventh prism that are adjacently arranged, and the second guiding component includes an eighth prism and a ninth prism that are adjacently arranged; the surface adjacent to the seventh prism and the ninth prism is the light-combining surface; the surface adjacent to the sixth prism and the seventh prism is the fifth surface, and the seventh prism also includes the sixth surface. The surface adjacent to the eighth prism and the ninth prism is the seventh surface, and the ninth prism also includes the eighth surface; the first sub-beam emitted from the light-splitting surface is reflected by the fifth surface and then incident on the first spatial light modulator, and the first sub-beam emitted after being modulated by the first spatial light modulator is reflected by the sixth surface and then incident on the light-combining surface; the second sub-beam emitted from the light-splitting surface is reflected by the seventh surface and then incident on the second spatial light modulator, and the second sub-beam emitted after being modulated by the second spatial light modulator is reflected by the eighth surface and then incident on the light-combining surface.

[0013] Wherein, the light splitting and combining device further includes a tenth prism, the tenth prism is arranged adjacent to the seventh prism, and the tenth prism is used to guide the outgoing light beam to emerge.

[0014] Among them, the splitting surface divides each of the sub-beams into the first sub-beam and the second sub-beam according to the wavelength characteristics; the combining surface combines the first sub-beam emitted after being modulated by the first spatial light modulator and the second sub-beam emitted after being modulated by the second spatial light modulator into the output beam according to the wavelength characteristics, and the wavelength ranges of the first sub-beam and the second sub-beam are different.

[0015] Wherein, the illumination light beam emitted by the light source is polarized light.

[0016] The electric field direction of the illumination light beam is perpendicular to or parallel to the normal plane of the light splitting surface and the light combining surface.

[0017] The beneficial effect of the embodiments of the present application is as follows: in the projection optical system, the light source emits an illumination beam, which includes multiple sub-beams, and the multiple sub-beams are incident on the splitting surface at different angles of incidence. The splitting surface splits each sub-beam into a first sub-beam and a second sub-beam to split the illumination beam, wherein the first sub-beam and the second sub-beam are both reflected an odd number of times after being emitted from the splitting surface and then incident on the light-combining surface, so that the incident angle of any sub-beam on the splitting surface is equal to or substantially equal to the incident angle of the first sub-beam and the second sub-beam corresponding to the sub-beam on the light-combining surface. In this way, the transmittance of the illumination beam at the light-combining and light-splitting points is the same or substantially the same, thereby reducing the light energy loss of the illumination beam at the light-splitting and light-combining points. When the DCI-P3 color gamut standard is met, more lasers can be added, thereby improving the output brightness of the projection optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the first embodiment of the projection optical system of the present application;

[0019] Figure 2 is a color gamut coordinate diagram of the projection optical system of the present application;

[0020] Figure 3 This is a schematic diagram of the structure of the second embodiment of the projection optical system of the present application.

[0021] Figure 4 is a schematic structural diagram of a third embodiment of the projection optical system of the present application;

[0022] Figure 5 It is a coating curve diagram of an embodiment of a light splitting surface and a light combining surface in a projection optical system of the present application. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0024] Embodiment 1

[0025] See also Figure 1 , Figure 1 The projection optical system of this embodiment includes: a light source 10 , a light splitting and combining device 30 , a first spatial light modulator 41 , and a second spatial light modulator 42 .

[0026] The light source 10 is used to emit an illumination beam, which includes a first light and a second light in sequence. Optionally, the first light includes a first primary color light and a second primary color light, for example, the first light is yellow light, the first primary color light is red light, and the second primary color light is green light; the second light includes a third primary color light, for example, the third primary color light is blue light. The combined light of the first light and the second light includes three primary colors. Among them, the light source 10 may include an excitation light source and a wavelength conversion device, the excitation light source emits excitation light, the excitation light source may be a solid light source such as a laser diode or a light emitting diode, the wavelength conversion device includes at least a first section and a second section, a wavelength conversion material layer is provided on the first section, which is used to convert the excitation light into a converted light, and the second section is a reflection layer or a transmission layer, which is used to reflect or transmit the excitation light. The first section and the second section of the wavelength conversion device are periodically arranged in sequence on the transmission path of the excitation light, so that the wavelength conversion device sequentially emits the excitation light and the converted light, optionally, the converted light is the first light, which is yellow fluorescence, and the excitation light is the second light, which is blue laser. The illumination beam includes a plurality of sub-beams. When the illumination light beam is incident on the light splitting and combining device 30, there are multiple incident angles. In the embodiment of the present invention, a small beam of light with the same incident angle is taken as a sub-beam.

[0027] The light-splitting and light-combining device 30 is used to compensate for the optical path difference of the illumination light beam, the total reflection of the illumination light beam, the color separation, and the synthesis of the image light. The light-splitting and light-combining device 30 includes a light-splitting surface S1 and a light-combining surface S2. The incident angles of the multiple sub-beams incident on the light-splitting surface S1 are different. The light-splitting surface S1 is used to split each sub-beam into a first sub-beam and a second sub-beam. Optionally, the first sub-beam includes a first primary color light, and the second sub-beam includes a second primary color light. For example, the first sub-beam includes red light, and the second sub-beam includes green light. The first sub-beam emitted from the light-splitting surface S1 enters the first spatial light modulator 41, and the first spatial light modulator 41 is used to modulate the first sub-beam; the second sub-beam emitted from the light-splitting surface S1 enters the second spatial light modulator 42, and the second spatial light modulator 42 modulates the second sub-beam. The light combining surface S2 is used to combine the first sub-beam modulated by the first spatial light modulator 41 and the second sub-beam modulated by the second spatial light modulator 42 into an output light beam, wherein the first sub-beam and the second sub-beam are incident on the light combining surface S2 after being reflected an odd number of times after being emitted from the light splitting surface S1. The first spatial light modulator 41 and the second spatial light modulator 42 are mirror-symmetric relative to the light combining surface S2. Preferably, the light splitting surface S1 and the light combining surface S2 are located on the same plane.

[0028] Optionally, the first spatial light modulator 41 and the second spatial light modulator 42 may be reflective spatial light modulators, such as digital micromirror devices (DMD). In other alternative embodiments, the first spatial light modulator 41 and the second spatial light modulator 42 may also be reflective liquid crystal panels. The first sub-beam and the second sub-beam are respectively reflected by the first spatial light modulator 41 and the second spatial light modulator 42 and then emitted.

[0029] In one embodiment, the first sub-beam is incident on the first spatial light modulator 41 after being reflected at least once after being emitted from the beam splitting surface S1 , and the second sub-beam is incident on the second spatial light modulator 42 after being reflected at least once after being emitted from the beam splitting surface S1 .

[0030] In another embodiment, the first sub-beam carrying image information emitted after modulation by the first spatial light modulator 41 is incident on the light combining surface S2 after at least one reflection, and the second sub-beam carrying image information emitted after modulation by the second spatial light modulator 42 is incident on the light combining surface S2 after at least one reflection, and the light combining surface S2 then combines the first sub-beam and the second sub-beam into an output light beam.

[0031] In another embodiment, the first sub-beam is incident on the first spatial light modulator 41 after being emitted from the light splitting surface S1 and after being reflected at least once, and the second sub-beam is incident on the second spatial light modulator 42 after being reflected at least once. The first sub-beam carrying image information emitted after being modulated by the first spatial light modulator 41 is incident on the light combining surface S2 after being reflected at least once, and the second sub-beam carrying image information emitted after being modulated by the second spatial light modulator 42 is incident on the light combining surface S2 after being reflected at least once, and the light combining surface S2 then combines the first sub-beam and the second sub-beam into an output beam.

[0032] Since the beam splitting surface S1 and the beam combining surface S2 are usually coated devices, their light transmittance characteristics are closely related to the angles at which the light is incident on the beam splitting surface S1 and the beam combining surface S2. The difference in incident angles can easily lead to inconsistent light transmittance characteristics, resulting in a greater loss of light. In order to reduce light loss, in this embodiment, the first sub-beam and the second sub-beam are both incident on the beam combining surface S2 after being reflected an odd number of times after being emitted from the beam splitting surface S1, and the difference between the incident angle of any sub-beam in the illumination beam to the beam splitting surface S1 and the incident angle of the first sub-beam corresponding to the sub-beam to the beam combining surface S2 is less than a preset threshold, and the difference between the incident angle of any sub-beam in the illumination beam to the beam splitting surface S1 and the incident angle of the second sub-beam corresponding to the sub-beam to the beam combining surface S2 is also less than the preset threshold. The preset threshold can be 0 degrees, 0.5 degrees, 1 degree, 1.5 degrees, 2 degrees, etc., and can be set specifically according to actual needs. Preferably, the preset threshold is 0 degrees, which can be understood as that the incident angle of each sub-beam on the beam splitting surface S1 is equal to or substantially equal to the incident angles of the first sub-beam and the second sub-beam corresponding to the sub-beam on the beam combining surface S2.

[0033] It can be understood that, in the present embodiment, the plurality of sub-beams include a first edge beam b1 and a second edge beam b2, and the incident angle of the first edge beam b1 on the beam splitting surface S1 is smaller than the incident angle of the second edge beam b2 on the beam splitting surface S1, that is, the first edge beam b1 corresponds to a small incident angle on the beam splitting surface S1, and the second edge beam b2 corresponds to a large incident angle on the beam splitting surface S1. After the first edge beam b1 is split, modulated, and reflected, the incident angle of the first edge beam b1 incident on the light combining surface S2 still corresponds to a small incident angle. After the second edge beam b2 is split, modulated, and reflected, the incident angle of the second edge beam b2 incident on the light combining surface S2 still corresponds to a large incident angle.

[0034] By making the incident angles of each sub-beam in the illumination light beam equal or substantially equal at the beam-splitting surface S1 and the beam-combining surface S2, the transmittance characteristics of any sub-beam at the beam-splitting surface S1 and the beam-combining surface S2 can be made consistent, thereby reducing the loss of light energy. As a result, more lasers can be added, and a higher output brightness of the system can be achieved.

[0035] Specifically, the light splitting and combining device 30 includes a first guiding component and a second guiding component. Figure 1 As shown, the first guiding component and the second guiding component are adjacent, and the light splitting surface S1 and the light combining surface S2 are located on the plane where the first guiding component and the second guiding component are adjacent, that is, in the surface where the first guiding component and the second guiding component are adjacent, a part is provided with the light splitting surface S1, and the other part is provided with the light combining surface S2.

[0036] The first guiding component is used to guide the first sub-beam emitted from the light splitting surface S1 to the first spatial light modulator 41, and then reflect the first sub-beam emitted after being modulated by the first spatial light modulator 41 to the light combining surface S2. The second guiding component is used to guide the second sub-beam emitted from the light splitting surface S1 to the second spatial light modulator 42, and then reflect the second sub-beam emitted after being modulated by the second spatial light modulator 42 to the light combining surface S2, and the optical path of each sub-beam from the light splitting surface S1 to the light combining surface S2 is equal or similar.

[0037] The incident angle of the illumination beam to the beam splitting surface S1 is related to the relative position of the light source 10 and the light splitting and combining device 30. By setting the positional relationship between the light source 10 and the light splitting and combining device 30, the incident angle of any sub-beam in the illumination beam to the beam splitting surface S1 can be controlled.

[0038] In this embodiment, the light splitting surface S1 and the light combining surface S2 are on the same plane. In order to make the incident angle of any sub-beam in the illumination light beam on the light splitting surface S1 equal or substantially equal to the incident angles of the first sub-beam and the second sub-beam corresponding to the sub-beam on the light combining surface S2, the first sub-beam and the second sub-beam are both reflected an odd number of times after being emitted from the light splitting surface and then incident on the light combining surface.

[0039] Specifically, the first guiding component needs to guide the first sub-beam emitted from the light splitting surface S1 to the first spatial light modulator 41 after M reflections, and then guide the first sub-beam carrying image information emitted after modulation by the first spatial light modulator 41 to the light combining surface S2 after N reflections. Wherein, M is a positive integer greater than or equal to 1, N is a positive integer greater than or equal to 1, and the sum of M and N is an even number greater than or equal to 2, etc.

[0040] The second guiding component needs to guide the second sub-beam emitted from the light splitting surface S1 to the second spatial light modulator 42 after X reflections, and guide the second sub-beam carrying image information emitted after modulation by the second spatial light modulator 42 to the light combining surface S2 after Y reflections. Wherein, X is a positive integer greater than or equal to 1, Y is a positive integer greater than or equal to 1, and the sum of X and Y is an even number greater than or equal to 2.

[0041] In a specific embodiment, the first guiding component includes a first prism 31 and a second prism 32 that are adjacent to each other, and the surface adjacent to the first prism 31 and the second prism 32 is a first surface f1, and the first surface f1 totally reflects the light whose incident angle is greater than the first threshold value. The second prism 32 also includes a second surface f2, and the second surface f2 totally reflects the light whose incident angle is greater than the second threshold value. Optionally, an air gap can be provided between the surfaces adjacent to the first prism 31 and the second prism 32 to enable the first surface f1 to achieve a total reflection function, or an adhesive having a refractive index lower than that of the prism can be applied between the surfaces adjacent to the first prism 31 and the second prism 32 to enable the first surface f1 to achieve a total reflection function.

[0042] The second guiding assembly includes a third prism 33 and a fourth prism 34 arranged adjacent to each other, and the surface adjacent to the third prism 33 and the fourth prism 34 is a third surface f3, and the third surface f3 totally reflects the light whose incident angle is greater than the third threshold value. The fourth prism 34 also includes a fourth surface f4, and the fourth surface f4 totally reflects the light whose incident angle is greater than the fourth threshold value. Optionally, the third surface f3 can realize the total reflection function by setting an air gap between the surfaces adjacent to the third prism 33 and the fourth prism 34, or the third surface f3 can realize the total reflection function by coating an adhesive with a refractive index lower than that of the prism between the surfaces adjacent to the third prism 33 and the fourth prism 34.

[0043] The surface where the first prism 31 and the third prism 33 are adjacent to each other is a light splitting surface S1 , and the surface where the second prism 32 and the fourth prism 34 are adjacent to each other is a light combining surface S2 .

[0044] The first prism 31 guides the illumination beam to the splitting surface S1, and the splitting surface S1 divides each sub-beam into a transmitted second sub-beam and a reflected first sub-beam. Among them, the first sub-beam is reflected by the first surface f1 and then incident on the first spatial light modulator 41. The first sub-beam emitted after modulation by the first spatial light modulator 41 is guided by the first prism 31 and the second prism 32 to the second surface f2, and then incident on the light-combining surface S2 after reflection from the second surface f2. The second sub-beam is reflected by the third surface f3 and then incident on the second spatial light modulator 42. The second sub-beam emitted after modulation by the second spatial light modulator 42 is guided by the third prism 33 and the fourth prism 34 to the fourth surface f4, and then incident on the light-combining surface S2 after reflection from the fourth surface f4. The light-combining surface S2 combines the first sub-beam and the second sub-beam into an output beam, and the output beam is emitted after being guided by the second prism 32.

[0045] In this embodiment, after the first sub-beam and the second sub-beam are emitted from the light-splitting surface S1, they are both reflected three times before being incident on the light-combining surface S2. Among them, the incident angle of any sub-beam in the illumination light beam on the light-splitting surface S1 is equal to or substantially equal to the incident angle of the first sub-beam and the second sub-beam corresponding to the sub-beam on the light-combining surface S2. In this way, the transmittance curves of the illumination light beam at the light-splitting and light-combining points are substantially consistent, so that no loss of light energy can be achieved.

[0046] Furthermore, in this embodiment, the beam splitting surface S1 is disposed on the surface adjacent to the first prism 31 and the third prism 33, and is used to split the illumination beam into a first sub-beam and a second sub-beam according to the wavelength characteristics, and the wavelength ranges of the first sub-beam and the second sub-beam are different, such as the first sub-beam is red light and the second sub-beam is green light. The beam splitting surface S1 can be a beam splitter or other optical element that can split any sub-beam into a first sub-beam and a second sub-beam, such as a beam splitting coating layer.

[0047] The light combining surface S2 is disposed on the surface adjacent to the second prism 32 and the fourth prism 34, and is used to combine the modulated first sub-beam and the second sub-beam into an output light beam and then output it. The light combining surface S2 can be a wavelength combining plate or other optical element that can combine the first sub-beam outputted by the first spatial light modulator 41 and the second sub-beam outputted by the second spatial light modulator 42 into an output light beam and then output it, such as a light combining coating layer.

[0048] The first prism 31 may be a prism of any shape including the above-mentioned beam splitting surface S1 and the first surface f1, such as a prism in the shape of a quadrangular prism, a prism in the shape of a pentagonal prism, etc. In a specific embodiment, the first prism 31 is a special-shaped prism in the shape of a pentagonal prism. Specifically, the first prism includes the beam splitting surface S1, the first surface f1, the second side surface 312 parallel to the first spatial light modulator 41, the first side surface 311 perpendicular to the main optical axis c, and the third side surface (not shown in the figure) connecting the first side surface 311 and the beam splitting surface S1, wherein the first side surface 311 and the beam splitting surface S1 are arranged opposite to each other, the first surface f1 and the third side surface are arranged opposite to each other, and the angle between the first side surface 311 and the second side surface 312 is an obtuse angle.

[0049] The second prism 32 may be a prism of any shape including a first surface f1 , a second surface f2 , and a light-combining surface S2 , such as a triangular prism, a quadrangular prism, and the like.

[0050] The third prism 33 may be a prism of any shape including the light splitting surface S1 and the third surface f3, such as a triangular prism.

[0051] The fourth prism 34 may be a prism of any shape including a fourth surface f4 and a light-combining surface S2, such as a triangular prism.

[0052] Furthermore, the light splitting and combining device 30 also includes a fifth prism 35, which is arranged adjacent to the second prism 32, and the fifth prism 35 is used to guide the outgoing light beam. The fifth prism 35 includes a ninth surface adjacent to the second prism 32, and a tenth surface perpendicular to the main optical axis of the outgoing light beam. The fifth prism 35 can be a prism of any shape including the above-mentioned ninth surface and tenth surface, such as a triangular prism prism. In another embodiment of the present application, the second prism 32 and the fifth prism 35 can also be made into an integral prism.

[0053] The inventor of the present application discovered during the long-term research and development process that in the existing technology, the incident light in the dual-chip optical engine has spectral loss in the process of splitting and combining. Therefore, the colors of the separated red phosphor and green phosphor are better and close to the standard color coordinates of DCI-P3. Therefore, the number of red and green lasers added is limited, so that although the whole machine can achieve the color gamut standard of the projector, the brightness that can be achieved is limited. In a specific embodiment, after the illumination light beam emitted by the light source 10 is split and combined to achieve spectral losslessness, the colors of the separated red phosphor (red phosphor, RP) and green phosphor (green phosphor, GP) will be relatively poor, and the covered color gamut range will be smaller, such as Figure 2 As shown in the figure, x and y are chromaticity coordinates. In order to achieve the DCI-P3 color gamut standard of the movie projector, it is necessary to add more red laser (RL) and green laser (GL), and laser, especially green laser, contributes more to lumen. Therefore, the projection optical system of this embodiment can achieve higher output brightness when achieving the same standard color gamut.

[0054] Furthermore, the projection optical system also includes an optical relay system 20, which is located between the light source 10 and the light splitting and combining device 30, and can focus the illumination light beam within a predetermined range. The optical relay system 20 is used to relay the light emitted by the light source 10 to obtain an illumination light beam for incident on the light splitting and combining device 30.

[0055] Optionally, the projection optical system further includes a projection lens 50 , which is disposed opposite to the light combining surface S2 . The light combining surface S2 combines the modulated first sub-beam and the second sub-beam into an outgoing light beam, which is then emitted to the projection lens 50 .

[0056] Different from the prior art, in the projection optical system of the present application, a light source emits an illumination beam, which includes multiple sub-beams. The incident angles of the multiple sub-beams incident on the splitting surface are different. The splitting surface S1 splits each sub-beam into a first sub-beam and a second sub-beam to split the illumination beam, wherein the first sub-beam and the second sub-beam are both reflected an odd number of times after being emitted from the splitting surface S1 and then incident on the light-combining surface S2, so that the incident angle of any sub-beam on the splitting surface S1 is equal to or substantially equal to the incident angle of the first sub-beam and the second sub-beam corresponding to the sub-beam incident on the light-combining surface S2. In this way, the transmittance of the illumination beam at the light-combining and light-splitting points is the same or substantially the same, thereby reducing the light energy loss of the illumination beam at the light-splitting and light-combining points. When the DCI-P3 color gamut standard is met, more lasers can be added, thereby improving the output brightness of the projection optical system.

[0057] Embodiment 2

[0058] See also Figure 3 , Figure 3 It is a structural schematic diagram of the second embodiment of the projection optical system of the present application. Different from the first embodiment, the light splitting and light combining device 30 in this embodiment also includes a light splitting element, the light splitting element includes a light splitting surface S1, and the surface adjacent to the first guide component and the second guide component is a light combining surface S2, wherein the light splitting element and the light combining surface are on the same plane.

[0059] In this embodiment, the beam splitter may be a dichroic plate. The beam splitter is used to split the illumination beam into a first sub-beam and a second sub-beam according to wavelength characteristics. The surface where the first guiding component and the second guiding component are adjacent is a light combining surface S2.

[0060] The first guiding component is used to guide the first sub-beam emitted from the light splitting surface S1 to the first spatial light modulator 41, and then guide the first sub-beam emitted after being modulated by the first spatial light modulator 41 to the light combining surface S2. The second guiding component is used to guide the second sub-beam emitted from the light splitting surface S1 to the second spatial light modulator 42, and then guide the second sub-beam emitted after being modulated by the second spatial light modulator 42 to the light combining surface S2.

[0061] The incident angle of the illumination beam to the beam splitter is related to the relative position of the light source 10 and the beam splitter. By setting the positional relationship between the light source 10 and the beam splitter, the incident angle of any sub-beam in the illumination beam to the beam splitter surface S1 can be controlled.

[0062] Specifically, in this embodiment, the first guiding component includes a sixth prism 36 and a seventh prism 37 that are adjacent to each other, and the surface adjacent to the sixth prism 36 and the seventh prism 37 is a fifth surface f5, and the fifth surface f5 totally reflects the light whose incident angle is greater than the fifth threshold value. The seventh prism 37 also includes a sixth surface f6, and the sixth surface f6 totally reflects the light whose incident angle is greater than the sixth threshold value. Optionally, an air gap can be provided between the surfaces adjacent to the sixth prism 36 and the seventh prism 37, so that the fifth surface f5 can achieve a total reflection function, or an air gap can be provided between the surfaces adjacent to the sixth prism 36 and the seventh prism 37, and an adhesive having a refractive index lower than that of the prism can be coated to enable the fifth surface f5 to achieve a total reflection function.

[0063] The second guiding assembly includes an eighth prism 38 and a ninth prism 39 disposed adjacent to each other, and the surface adjacent to the eighth prism 38 and the ninth prism 39 is a seventh surface f7, and the seventh surface f7 totally reflects the light whose incident angle is greater than the seventh threshold value. The ninth prism 39 also includes an eighth surface f8, and the eighth surface f8 totally reflects the light whose incident angle is greater than the eighth threshold value. Optionally, an air gap can be provided between the surfaces adjacent to the eighth prism 38 and the ninth prism 39, so that the seventh surface f7 can realize the total reflection function, and an adhesive having a refractive index lower than that of the prism can be applied between the surfaces adjacent to the eighth prism 38 and the ninth prism 39, so that the seventh surface f7 can realize the total reflection function.

[0064] The surface where the seventh prism 37 and the ninth prism 39 are adjacent to each other is the light combining surface.

[0065] The beam splitter divides each sub-beam into a transmitted second sub-beam and a reflected first sub-beam. Among them, the first sub-beam emitted from the beam splitting surface S1 is reflected by the fifth surface f5 and then incident on the first spatial light modulator 41. The first sub-beam emitted after modulation by the first spatial light modulator 41 is guided to the sixth surface f6 by the sixth prism 36 and the seventh prism 37, and then incident on the light combining surface S2 after reflection from the sixth surface f6. The second sub-beam emitted from the beam splitting surface S1 is reflected by the seventh surface f7 and then incident on the second spatial light modulator 42. The second sub-beam emitted after modulation by the second spatial light modulator 42 is guided to the eighth surface f8 by the eighth prism 38 and the ninth prism 39, and then incident on the light combining surface S2 after reflection from the eighth surface f8. The light combining surface S2 combines the first sub-beam and the second sub-beam into an output beam, and the output beam is guided by the seventh prism 37 and then emitted.

[0066] In this embodiment, the first sub-beam and the second sub-beam are both incident on the light-combining surface S2 after three reflections. Among them, the incident angle of any sub-beam in the illumination light beam on the light-splitting surface S1 is equal or substantially equal to the incident angle of the first sub-beam and the second sub-beam corresponding to the sub-beam on the light-combining surface S2. In this way, the coating characteristics of the light-splitting surface S1 and the light-combining surface S2 can be made consistent during coating, so that the transmittance curves of the illumination light beam during light splitting and light combining are substantially consistent, thereby achieving no loss of light energy.

[0067] Furthermore, in this embodiment, the light combining surface S2 is disposed on the surface adjacent to the seventh prism 37 and the eighth prism 38, and is used to combine the modulated first sub-beam and the second sub-beam into an output light beam and then output it. The light combining surface S2 can be a wavelength light combining plate or other optical element that can combine the first sub-beam outputted by the first spatial light modulator 41 and the second sub-beam outputted by the second spatial light modulator 42 into an output light beam and then output it, such as a light combining coating layer.

[0068] The sixth prism 36 may be a prism of any shape including the fifth surface f5, such as a triangular prism.

[0069] The seventh prism 37 may be a prism of any shape including a fifth surface f5, a sixth surface f6 and a light-combining surface S2, such as a triangular prism, a quadrangular prism, etc.

[0070] The eighth prism 38 may be a prism of any shape including a seventh surface f7, such as a triangular prism.

[0071] The ninth prism 39 may be a prism of any shape including the eighth surface f8 and the light-combining surface S2, such as a triangular prism.

[0072] Furthermore, in the present embodiment, the light splitting and combining device 30 also includes a tenth prism 310, which is disposed adjacent to the seventh prism 37, and the tenth prism 310 is used to guide the outgoing light beam. The tenth prism 310 includes an eleventh surface adjacent to the seventh prism 37, and a twelfth surface perpendicular to the main optical axis of the outgoing light beam. The fifth prism 35 can be a prism of any shape including the eleventh surface and the twelfth surface, such as a triangular prism prism. In another embodiment of the present application, the seventh prism 37 and the tenth prism 310 can also be made into an integral prism.

[0073] For other structures in the projection optical system of this embodiment, please refer to the drawings and text descriptions in the above-mentioned embodiment 1, and will not be described in detail here.

[0074] In this embodiment, the light splitting surface S1 in the light splitting element is used to split the illumination light beam, and in this embodiment, the incident angle of any sub-beam to the light splitting surface S1 and the incident angle of the first sub-beam and the second sub-beam corresponding to the sub-beam to the light combining surface S2 are equal or substantially equal. Therefore, the transmittance curves of the illumination light beam at the light splitting and light combining points can be substantially consistent, thereby reducing the light energy loss after light splitting and light combining.

[0075] Embodiment 3

[0076] See also Figure 4 , Figure 4 1 is a schematic diagram of the structure of the third embodiment of the projection optical system of the present application. On the basis of the first embodiment, the light source 10 in this embodiment can be set as a polarized illumination light source, and the illumination light beam emitted by the light source 10 is polarized light. Preferably, the illumination light beam is linearly polarized light. The projection optical system of this embodiment can also achieve lossless light effect when splitting and combining polarized illumination light.

[0077] In dielectric materials, since the transmittance of the two polarization states of S light and P light is different, the transmittance curves of the dielectric film layer for S light and P light are different. Even if the incident angle remains the same, the transmittance curves are separated from each other. Figure 5 As shown, P25 is the transmittance curve when the incident angle of P light is 25 degrees, and S25 is the transmittance curve when the incident angle of S light is 25 degrees; P13 is the transmittance curve when the incident angle of P light is 13 degrees, and S13 is the transmittance curve when the incident angle of S light is 13 degrees; P1 is the transmittance curve when the incident angle of P light is 1 degree, and S1 is the transmittance curve when the incident angle of S light is 1 degree. It can be seen from the figure that when the incident angle is the same, the transmittance curves of P light and S light are still separated, but as the incident angle decreases, the separation of the transmittance curves of P light and S light decreases.

[0078] In this embodiment, under the condition that the light source 10 adopts a polarized illumination light source 10, the polarized illumination light beam emitted by it is transmitted, split, totally reflected and combined in the same plane (perpendicular or parallel to the electric field direction) in the light splitting and combining device 30, and the electric field direction of the illumination light beam emitted by the polarized illumination light source is perpendicular or parallel to the direction of the normal plane of the light splitting surface S1 and the light combining surface S2, so its polarization state does not change during light splitting and light combining. When the light splitting and light combining device 30 is used for light splitting and light combining, its polarization state and incident angle can be kept consistent, so lossless light splitting and light combining of polarized illumination light can be achieved.

[0079] For other specific structures in the projection optical system, please refer to the drawings and text descriptions in the above-mentioned embodiment 1, which will not be described in detail here.

[0080] In this embodiment, a polarized illumination light source is used, which can achieve lossless light splitting and light combining and higher 3D efficiency.

[0081] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A projection optical system, characterized in that: The projection optical system comprises: a light source, a light splitting and combining device, a first spatial light modulator, and a second spatial light modulator; The light source is used to emit an illumination beam, and the illumination beam includes a plurality of sub-beams; The light-splitting and light-combining device comprises a light-splitting surface and a light-combining surface, the incident angles of the plurality of sub-beams incident on the light-splitting surface are different, the light-splitting surface is used to split each of the sub-beams into a first sub-beam and a second sub-beam, the first spatial light modulator is used to modulate the first sub-beam emitted from the light-splitting surface, the second spatial light modulator is used to modulate the second sub-beam emitted from the light-splitting surface, and the light-combining surface is used to combine the first sub-beam emitted after being modulated by the first spatial light modulator and the second sub-beam emitted after being modulated by the second spatial light modulator into an output light beam, wherein the first sub-beam and the second sub-beam are incident on the light-combining surface after being reflected an odd number of times after being emitted from the light-splitting surface; The incident angle of any one of the sub-beams in the illumination beam to the beam splitting surface and the incident angle of the first sub-beam corresponding to the sub-beam to the light combining surface are basically equal, and the incident angle of any one of the sub-beams in the illumination beam to the beam splitting surface and the incident angle of the second sub-beam corresponding to the sub-beam to the light combining surface are basically equal.

2. The projection optical system according to claim 1, characterized in that: The light splitting surface and the light combining surface are located on the same plane.

3. The projection optical system according to claim 1, characterized in that: The first spatial light modulator and the second spatial light modulator are both reflective spatial light modulators.

4. The projection optical system according to claim 3, characterized in that: The light splitting and combining device comprises a first guiding component and a second guiding component; The first guiding component is used to guide the first sub-beam emitted from the light splitting surface to the first spatial light modulator after M reflections, and guide the first sub-beam emitted after being modulated by the first spatial light modulator to the light combining surface after N reflections, wherein M is a positive integer greater than or equal to 1, N is a positive integer greater than or equal to 1, and the sum of M and N is an even number greater than or equal to 2; The second guiding component is used to guide the second sub-beam emitted from the splitting surface to the second spatial light modulator after X reflections, and to guide the second sub-beam emitted after modulation by the second spatial light modulator to the light combining surface after Y reflections, wherein X is a positive integer greater than or equal to 1, Y is a positive integer greater than or equal to 1, and the sum of X and Y is an even number greater than or equal to 2.

5. The projection optical system according to claim 4, characterized in that: The first guiding component and the second guiding component are adjacent to each other, and the light splitting surface and the light combining surface are located on a plane where the first guiding component and the second guiding component are adjacent to each other.

6. The projection optical system according to claim 5, characterized in that: The first guiding component includes a first prism and a second prism disposed adjacent to each other, and the second guiding component includes a third prism and a fourth prism disposed adjacent to each other; the surface where the first prism and the third prism are adjacent to each other is the light splitting surface, and the surface where the second prism and the fourth prism are adjacent to each other is the light combining surface; The surface where the first prism and the second prism are adjacent is the first surface, and the second prism also includes a second surface; the surface where the third prism and the fourth prism are adjacent is the third surface, and the fourth prism also includes a fourth surface; The first sub-beam emitted from the light splitting surface is reflected by the first surface and then incident on the first spatial light modulator, and the first sub-beam emitted after being modulated by the first spatial light modulator is reflected by the second surface and then incident on the light combining surface; The second sub-beam emitted from the beam splitting surface is reflected by the third surface and then incident on the second spatial light modulator. The second sub-beam emitted after being modulated by the second spatial light modulator is reflected by the fourth surface and then incident on the light combining surface.

7. The projection optical system according to claim 6, characterized in that: The light splitting and combining device further includes a fifth prism, which is disposed adjacent to the second prism and is used to guide the outgoing light beam to emerge.

8. The projection optical system according to claim 5, characterized in that: The light splitting and combining device further comprises a light splitting element, the light splitting element comprises the light splitting surface, the first guiding component comprises a sixth prism and a seventh prism which are arranged adjacent to each other, and the second guiding component comprises an eighth prism and a ninth prism which are arranged adjacent to each other; the surface where the seventh prism and the ninth prism are adjacent to each other is the light combining surface; The surface where the sixth prism and the seventh prism are adjacent is the fifth surface, the seventh prism further includes the sixth surface, the surface where the eighth prism and the ninth prism are adjacent is the seventh surface, and the ninth prism further includes the eighth surface; The first sub-beam emitted from the light-splitting surface is reflected by the fifth surface and then incident on the first spatial light modulator, and the first sub-beam emitted after being modulated by the first spatial light modulator is reflected by the sixth surface and then incident on the light-combining surface; The second sub-beam emitted from the beam splitting surface is reflected by the seventh surface and then incident on the second spatial light modulator. The second sub-beam emitted after being modulated by the second spatial light modulator is reflected by the eighth surface and then incident on the light combining surface.

9. The projection optical system according to claim 8, characterized in that: The light splitting and combining device further includes a tenth prism, which is disposed adjacent to the seventh prism and is used to guide the outgoing light beam to emerge.

10. The projection optical system according to claim 1, characterized in that: The beam splitting surface splits each of the sub-beams into the first sub-beam and the second sub-beam according to wavelength characteristics; The light combining surface combines the first sub-beam modulated by the first spatial light modulator and the second sub-beam modulated by the second spatial light modulator into the output light beam according to the wavelength characteristic, and the first sub-beam and the second sub-beam have different wavelength ranges.

11. The projection optical system according to claim 1, characterized in that: The illumination light beam emitted by the light source is polarized light.

12. The projection optical system according to claim 11, characterized in that: The electric field direction of the illumination light beam is perpendicular to or parallel to the normal planes of the light splitting surface and the light combining surface.

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