CN117706851A - Dual-light path common-caliber projection optical engine of dual-total internal reflection prism beam splitting - Google Patents
Dual-light path common-caliber projection optical engine of dual-total internal reflection prism beam splitting Download PDFInfo
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- CN117706851A CN117706851A CN202410167645.8A CN202410167645A CN117706851A CN 117706851 A CN117706851 A CN 117706851A CN 202410167645 A CN202410167645 A CN 202410167645A CN 117706851 A CN117706851 A CN 117706851A
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Classifications
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/005—Projectors using an electronic spatial light modulator but not peculiar thereto
- G03B21/008—Projectors using an electronic spatial light modulator but not peculiar thereto using micromirror devices
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
- G02B13/005—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having spherical lenses only
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0938—Using specific optical elements
- G02B27/095—Refractive optical elements
- G02B27/0955—Lenses
- G02B27/0961—Lens arrays
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/30—Collimators
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/142—Adjusting of projection optics
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/28—Reflectors in projection beam
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Abstract
A dual-light path common-caliber projection optical engine of dual-total internal reflection prism beam splitting belongs to the technical field of projection display and solves the problem that an off-state light beam is easy to enter a projection optical system to form stray light and reduce image contrast in the existing projection optical engine based on dual-digital micromirror device design. The optical engine includes: a projection optical system for loading the illumination incident beam with the first digital micromirror device and the second digital micromirror device of the image information; the first total internal reflection prism and the second total internal reflection prism are used for increasing the included angle between the illumination axis and the projection axis and isolating the micro-mirror on-state and off-state light beams of the digital micro-mirror device; the optical axis of the first illumination optical system and the normal line of the center of the incidence surface of the internal total reflection prism are collinear, and the illumination uniformity of the digital micro-mirror device is improved. The invention is suitable for the field of projection display.
Description
Technical Field
The invention belongs to the technical field of projection display, and particularly relates to a projection optical engine.
Background
In projection display devices, important parameters such as projection frame rate, bit depth, resolution, operating band, etc., are mainly determined by the scene generating device.
The existing visible light scene generating device mainly comprises silicon-based liquid crystal, a liquid crystal display and the like, and the infrared scene generating device mainly comprises a resistor array, infrared silicon-based liquid crystal and the like. In addition to the above, the digital micromirror device is used as a reflective scene generating device, and can be used for projection display in any wave band by changing a proper window glass material, so that the digital micromirror device is widely applied to various fields such as video and audio entertainment, digital lithography, optical semi-physical simulation and the like.
The digital micro-mirror device realizes the projection display of gray level images by a pulse width modulation technology, and usually only can project gray level images with 8-bit depth at a frame frequency of 200 fps, so that the technology of combining spatial light modulation by adopting the double digital micro-mirror device is also generated in order to break through the restriction relation between the frame frequency and the bit depth.
In order to reduce design difficulty, the existing projection optical engine designed based on the double-digital micromirror device generally directly illuminates the target surface of the digital micromirror device and avoids interference among different light paths by utilizing space three-dimensional layout, but the defects of the optical structure are quite obvious, in order to avoid interference between an illumination system and a projection system, the two must have an ultra-long back working distance, so that the integration level of the projection optical engine is obviously reduced, and the adjustment difficulty of an optical-mechanical system is greatly increased by adopting a space three-dimensional layout mode.
In addition, because the included angle between the micro-mirror on-state and off-state light beams of the digital micro-mirror device is not further increased, the off-state light beams are easy to enter the projection optical system to form stray light, and the image contrast is reduced.
Disclosure of Invention
The invention provides a light path common caliber projection optical engine of a double internal total reflection prism beam splitting, which aims to solve the problems that the existing projection optical engine based on the design of a double digital micromirror device has an ultra-long back working distance, so that the integration level of the projection optical engine is obviously reduced, the adjustment difficulty of an optical machine system is greatly increased by adopting a space three-dimensional layout mode, and the included angle between on-state and off-state light beams of a micromirror device is not further increased, off-state light beams are easy to enter the projection optical system to form stray light, and the image contrast is reduced.
The invention provides a dual-light path common caliber projection optical engine of dual-internal total reflection prism beam split, which comprises: a first beam propagation system, a second beam propagation system, a barrier, and a projection optical system;
the first beam propagation system includes: a first illumination optical system, a first total internal reflection prism, and a first digital micromirror device; the second beam propagation system includes: a second illumination optical system, a second total internal reflection prism, and a second digital micromirror device; the projection optical system includes: a beam combining prism and a common caliber device;
the first illumination optical system is used for generating and emitting a first light beam and emitting the first light beam into the first total internal reflection prism;
the first total internal reflection prism is used for injecting the first light beam into the first digital micro-mirror device;
the first digital micro-mirror device is used for loading the image information of the first light beam and outputting first on-state light and first off-state light;
the second illumination optical system is used for generating and emitting a second light beam and emitting the second light beam into the second total internal reflection prism;
the second total internal reflection prism is used for injecting the second light beam into the second digital micro-mirror device;
the second digital micro-mirror device is used for loading the image information of the second light beam and outputting second on-state light and second off-state light;
the beam combining prism is used for combining the first on-state light and the second on-state light to obtain combined light;
the common aperture device is used for projecting the combined beam;
the light barrier is used for receiving the first off-state light and the second off-state light.
Further, a preferred scheme is provided: the optical axis of the first illumination optical system is collinear with the normal line of the center of the incidence surface of the first total internal reflection prism; the optical axis of the second illumination optical system is collinear with the normal line of the center of the incidence surface of the second total internal reflection prism.
Further, a preferred scheme is provided: the first total internal reflection prism and the second total internal reflection prism respectively comprise two stray light eliminating baffles for intercepting stray light.
Further, a preferred scheme is provided: the common aperture device comprises a spherical lens group, wherein the spherical lens group comprises seven spherical lenses, and the spherical lenses are respectively: the first positive lens, the first negative lens, the second positive lens, the third positive lens, the second negative lens, the fourth positive lens and the third negative lens are sequentially arranged along the light path direction.
Further, a preferred scheme is provided: the first positive lens is a meniscus positive lens, the first negative lens is a biconcave negative lens, the second positive lens is a biconvex positive lens, the third positive lens is a biconvex positive lens, the second negative lens is a meniscus negative lens, the fourth positive lens is a biconvex positive lens, and the third negative lens is a biconcave negative lens.
Further, a preferred scheme is provided: the first illumination optical system includes: the first collimating aspheric biconvex lens, the first collimating aspheric biconvex lens circular aperture, the first double-row fly-eye lens array Fang Guanglan, the first double-row fly-eye lens array, the first plano-convex lens and the first plano-convex lens aperture are sequentially arranged along the light path; the second illumination optical system includes: the second collimating aspheric biconvex lens, the second collimating aspheric biconvex lens circular aperture, the second double-row fly-eye lens array Fang Guanglan, the second double-row fly-eye lens array, the second plano-convex lens and the second plano-convex lens aperture are sequentially arranged along the light path.
Further, a preferred scheme is provided: the first collimating aspheric biconvex lens and the second collimating aspheric biconvex lens are used for collecting light beams and collimating the light beams into parallel light, and the first double-row fly-eye lens array and the second double-row fly-eye lens array are used for shaping and homogenizing the parallel light.
Further, a preferred scheme is provided: the first double-row fly-eye lens array and the square diaphragm of the first double-row fly-eye lens array rotate 45 degrees around the optical axis of the first illumination optical system; the second double-row fly-eye lens array and the second double-row fly-eye lens array square diaphragm rotate 45 degrees around the optical axis of the second illumination optical system.
Further, a preferred scheme is provided: the first illumination optical system and the first total internal reflection prism rotate 45 degrees around the normal line of the geometric center of the target surface of the first digital micro-mirror device; the second illumination optical system and the second total internal reflection prism are rotated by 45 degrees around the normal line of the geometric center of the target surface of the second digital micro-mirror device.
Further, a preferred scheme is provided: the optical engine operates in 440 nm to 656 nm and has an angle of view of 9.2 x 6.9.
Compared with the prior art, the invention has the advantages that:
the invention adopts the dual-light path common aperture optical structure to complete the design of the projection optical engine, and each light path is separated from the illumination light path and the projection light path by the internal total reflection prism, thus obviously shortening the post working distance of illumination and projection and improving the integration level of the optical engine.
In addition, the internal total reflection prism can also ensure that the micro-mirror on-state light beam of the digital micro-mirror device enters the projection optical system and the off-state light beam is far away from the projection optical system, thereby effectively improving the contrast of the projection image.
The projection optical engine can be used for supporting the modulation layers of the two digital micro-mirror devices to be optically overlapped at the projection exit pupil, thereby providing reliable assurance for the joint modulation of the two digital micro-mirrors.
In view of the reflective working characteristics of the digital micromirror device, the reflective optical structure can be used for spatial light modulation of any wave band by only changing window glass materials, so that the dual-light-path common-caliber optical structure based on the dual-total internal reflection prism is also suitable for projection display of any working wave band.
Drawings
Fig. 1 is a schematic diagram of a dual-path common-caliber projection optical engine with dual total internal reflection prism beam splitting according to an embodiment, wherein 10 is a projection optical system, and 11 is a common-caliber device; 12 is a beam combining prism, 20 is a first digital micro-mirror device, 30 is a second digital micro-mirror device, 40 is a first total internal reflection prism, 50 is a second total internal reflection prism, 60 is a first illumination optical system, and 70 is a second illumination optical system;
fig. 2 is a schematic diagram of a dual-path common-caliber projection optical engine for splitting light by using a dual-internal total reflection prism according to an embodiment, wherein 111 is a first positive lens, 112 is a first negative lens, 113 is a second positive lens, 114 is a third positive lens, 115 is a second negative lens, 116 is a fourth positive lens, 117 is a third negative lens, 401 is a first light barrier, 501 is a second light barrier, 601 is a first light emitting diode light source, 602 is a first aspheric biconvex lens, 603 is a first aspheric biconvex lens circular diaphragm, 604 is a first double-row fly-eye lens array square diaphragm, 605 is a first double-row fly-eye lens array, 606 is a first plano-convex lens, 701 is a second light emitting diode light source, 702 is a second aspheric biconvex lens, 703 is a second aspheric biconvex lens circular diaphragm, 704 is a second double-row fly-eye lens array square diaphragm, 705 is a second biconvex lens array, 706 is a second plano-convex lens;
FIG. 3 is a schematic layout diagram of a dual-path common-caliber projection optical engine with dual total internal reflection prism beam splitting according to an embodiment;
FIG. 4 is a schematic view of a dual-path common-caliber projection optical engine based on dual-total internal reflection prism beam splitting according to the first embodiment;
FIG. 5 is an illumination light path diagram of a dual-light path common aperture projection optical engine based on dual total internal reflection prism splitting according to an embodiment;
FIG. 6 is a schematic illustration showing the illuminance uniformity of an illumination optical system of a dual-path common-caliber projection optical engine based on dual-total internal reflection prism beam splitting according to the first embodiment;
FIG. 7 is a distortion curve of a dual-path common-caliber projection optical engine based on dual-total internal reflection prism splitting according to an embodiment;
fig. 8 is an optical transfer function curve of a dual-path common-caliber projection optical engine based on dual-total internal reflection prism splitting according to an embodiment.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.
Embodiment one
The present embodiment will be described with reference to fig. 1, 2, 3, 4, 5, 6, 7, and 8.
The dual-path common-caliber projection optical engine of the dual-total internal reflection prism beam splitter according to the embodiment comprises: a first beam propagation system, a second beam propagation system, a barrier, and a projection optical system;
the first beam propagation system includes: a first illumination optical system, a first total internal reflection prism, and a first digital micromirror device; the second beam propagation system includes: a second illumination optical system, a second total internal reflection prism, and a second digital micromirror device; the projection optical system includes: a beam combining prism and a common caliber device;
the first illumination optical system is used for generating and emitting a first light beam and emitting the first light beam into the first total internal reflection prism;
the first total internal reflection prism is used for injecting the first light beam into the first digital micro-mirror device;
the first digital micro-mirror device is used for loading the image information of the first light beam and outputting first on-state light and first off-state light;
the second illumination optical system is used for generating and emitting a second light beam and emitting the second light beam into the second total internal reflection prism;
the second total internal reflection prism is used for injecting the second light beam into the second digital micro-mirror device;
the second digital micro-mirror device is used for loading the image information of the second light beam and outputting second on-state light and second off-state light;
the beam combining prism is used for combining the first on-state light and the second on-state light to obtain combined light;
the common aperture device is used for projecting the combined beam;
the light barrier is used for receiving the first off-state light and the second off-state light.
Specifically:
the optical axis of the first illumination optical system is collinear with the normal line of the center of the incidence surface of the first total internal reflection prism; the optical axis of the second illumination optical system is collinear with the normal line of the center of the incidence surface of the second total internal reflection prism.
Taking the optical axis of the projection optical system as a main optical axis, wherein the normal line of the geometric center of the target surface of the first digital micro-mirror device is collinear with the projection optical axis, and the normal line of the geometric center of the target surface of the second digital micro-mirror device is perpendicular to the projection optical axis;
the optical axis of the first illumination optical system is perpendicular to the incidence surface of the first total internal reflection prism, the included angle between the optical axis of the illumination optical system which is folded by the first total internal reflection prism and the normal line of the geometric center of the target surface of the first digital micro-mirror device is 24 degrees, and the second illumination optical system, the second total internal reflection prism and the second digital micro-mirror device have the same spatial position relation.
The first total internal reflection prism and the second total internal reflection prism respectively comprise two stray light eliminating baffles for intercepting stray light;
the common aperture device comprises a spherical lens group, wherein the spherical lens group comprises seven spherical lenses, and the spherical lenses are respectively: the first positive lens, the first negative lens, the second positive lens, the third positive lens, the second negative lens, the fourth positive lens and the third negative lens are sequentially arranged along the light path direction.
The first positive lens and the first negative lens are combined to form a first double-cemented lens, the third positive lens and the second negative lens are combined to form a second double-cemented lens, and the fourth positive lens and the third negative lens are combined to form a third double-cemented lens.
The first positive lens is a meniscus positive lens, the first negative lens is a biconcave negative lens, the second positive lens is a biconvex positive lens, the third positive lens is a biconvex positive lens, the second negative lens is a meniscus negative lens, the fourth positive lens is a biconvex positive lens, and the third negative lens is a biconcave negative lens.
The first illumination optical system includes: the first collimating aspheric biconvex lens, the first collimating aspheric biconvex lens circular aperture, the first double-row fly-eye lens array Fang Guanglan, the first double-row fly-eye lens array, the first plano-convex lens and the first plano-convex lens aperture are sequentially arranged along the light path; the second illumination optical system includes: the second collimating aspheric biconvex lens, the second collimating aspheric biconvex lens circular aperture, the second double-row fly-eye lens array Fang Guanglan, the second double-row fly-eye lens array, the second plano-convex lens and the second plano-convex lens aperture are sequentially arranged along the light path.
The first collimating aspheric biconvex lens and the second collimating aspheric biconvex lens are used for collecting light beams and collimating the light beams into parallel light, and the first double-row fly-eye lens array and the second double-row fly-eye lens array are used for shaping and homogenizing the parallel light.
The collimating aspheric biconvex lens, the double-row fly-eye lens array and the plano-convex lens form a Kohler illumination optical structure.
The first double-row fly-eye lens array and the square diaphragm of the first double-row fly-eye lens array rotate 45 degrees around the optical axis of the first illumination optical system; the second double-row fly-eye lens array and the square diaphragm of the second double-row fly-eye lens array rotate 45 degrees around the optical axis of the second illumination optical system so as to ensure that rectangular light spots incident to the digital micro-mirror device coincide with the target surface of the digital micro-mirror device.
The first illumination optical system and the first total internal reflection prism rotate 45 degrees around the normal line of the geometric center of the target surface of the first digital micro-mirror device so as to ensure that the optical axis of the first illumination optical system and the normal line of the geometric center of the target surface of the first digital micro-mirror device are positioned in a plane perpendicular to the angular line of the target surface of the first digital micro-mirror device together; the second illumination optical system and the second total internal reflection prism rotate 45 degrees around the normal line of the geometric center of the target surface of the second digital micro-mirror device so as to ensure that the optical axis of the second illumination optical system and the normal line of the geometric center of the target surface of the second digital micro-mirror device are located in a plane perpendicular to the diagonal line of the target surface of the second digital micro-mirror device together.
The optical engine according to this embodiment has an operating band of 440 nm to 656 nm and an angle of view of 9.2 ° x 6.9 °.
The technical principle of the optical engine is that the optical engine is a double-optical-path common-caliber projection optical engine designed based on a double-internal-total-reflection prism, and comprises a projection optical system, a first digital micro-mirror device, a second digital micro-mirror device, a first illumination optical system, a second illumination optical system, a first total-internal-reflection prism and a second total-internal-reflection prism, wherein the total-internal-reflection prism comprises two stray light eliminating baffles for intercepting stray light, and the projection optical system comprises a cube prism for combining two paths of light beams loaded with image information and a common-caliber part comprising seven spherical lenses.
Specifically: the digital micromirror device according to this embodiment is composed of a micromirror array, when light is incident on a micromirror in an on state, the outgoing beam corresponds to the on state light, and when the beam is incident on a micromirror in an off state, the outgoing beam corresponds to the off state light, and this process is so-called spatial light modulation, which can also be understood as loading the incident light with image information; through spatial light modulation of the digital micromirror device, emergent light enters the total internal reflection prism again, on-state light in the emergent light enters the beam combining prism, and off-state light in the emergent light is intercepted by the light barrier.
The spherical lens group reasonably distributes focal power through seven spherical lenses, and completes aberration correction of the whole projection optical system.
Firstly, a modulation layer which can be used for supporting two digital micro-mirror devices is optically overlapped at a projection exit pupil, so that reliable guarantee is provided for the joint spatial light modulation of the two digital micro-mirrors; secondly, each light path is separated from an illumination light path and a projection light path by an internal total reflection prism, so that the rear working distance of illumination and projection can be obviously shortened, and the integration level of an optical engine is improved; and the internal total reflection prism can also ensure that the micro-mirror on-state light beam of the digital micro-mirror device enters the projection optical system and the off-state light beam is far away from the projection optical system, so that the contrast of the projection image is effectively improved. In view of the reflective working characteristics of the digital micromirror device, the reflective working characteristics can be used for spatial light modulation of any wavelength band by only changing window glass materials, so that the dual-light-path common-caliber optical structure based on the dual-total internal reflection prism provided by the embodiment is also suitable for projection display of any working wavelength band.
As shown in fig. 1, the dual-light path common aperture projection optical engine based on dual total internal reflection prism beam splitting includes: the projection optical system 10, the first and second digital micromirror devices 20 and 30, the first and second total internal reflection prisms 40 and 50, the first and second illumination optical systems 60 and 70, wherein the total internal reflection prisms include a light barrier. The first digital micromirror device 20 and the second digital micromirror device 30 need to have the same model and are subjected to synchronous control and registration operations to ensure that the projected images of the two digital micromirrors can be superimposed at the projection exit pupil. In particular, the incident light beams of the first illumination optical system 60 and the second illumination system 70 are respectively incident to the target surface of the first digital micromirror device 20 and the target surface of the second digital micromirror device 30 through the first total internal reflection prism 40 and the second total internal reflection prism 50, and in this embodiment, the target surfaces are photosensitive surfaces of the digital micromirror devices. The first digital micromirror device 20 and the second digital micromirror device 30 respectively perform spatial light modulation on the incident light beams, the micromirror on-state light beams modulated by the first digital micromirror device 20 are transmitted by the beam combining prism 12, the micromirror on-state light beams modulated by the second digital micromirror device 30 are reflected by the beam combining prism 12, and the combined light beams enter the common aperture device 11 of the projection optical system 10.
As shown in fig. 2, the common aperture device 11 of the projection optical system 10 includes a lens 111-a lens 117, 7 lenses in total, and all optical surfaces of the lenses are spherical; the beam combining prism 12 is used for combining the on-state light beam of the first digital micro-mirror 20 and the on-state light beam of the second digital micro-mirror 30 to the common aperture device 11; the first total internal reflection prism 40 can ensure that the on-state light beam of the first digital micromirror 20 can be incident on the transmission surface of the beam combining prism 12, and the off-state light beam can be incident on the light barrier 401; similarly, the second total internal reflection prism 50 can ensure that the on-state light beam of the first digital micromirror 30 can be incident on the reflective surface of the beam combining prism 12, and the off-state light beam can be incident on the light barrier 501; the light barrier should be covered with a coating for absorbing stray light generally, so as to ensure that the light beam incident on the surface of the light barrier cannot enter the projection optical system 10 to form stray light; the total internal reflection prism 40 and the total internal reflection prism 50 can separate the optical axes of the illumination optical system 60 and the illumination optical system 70 by a larger angle relative to the optical axis of the projection optical system 10, so that the interference between optical machine structural members can be avoided even if the rear working distance of the illumination optical system and the projection optical system is shorter, and the integration level of the projection optical engine can be effectively improved; the exit pupil of the illumination optical system is arranged on the target surface of the digital micro-mirror device and coincides with the entrance pupil of the projection optical system; the illumination optical system 70 and the total internal reflection prism 50 rotate 45 degrees around the normal line of the geometric center of the digital micro-mirror 30 together, so that the illumination light beam can be incident along the plane perpendicular to the diagonal line of the digital micro-mirror device 30, and the double-row fly-eye lens 705 and the rectangular diaphragm 704 thereof rotate 45 degrees around the optical axis of the illumination optical system 70, so that the rectangular light spot incident to the digital micro-mirror device 30 can coincide with the target surface of the digital micro-mirror device 30; similarly, illumination optics 60, together with total internal reflection prism 40, are rotated 45 ° about the geometric center normal of digital micromirror 20, and double fly-eye lens 605, together with its rectangular stop 604, are rotated 45 ° about the optical axis of illumination optics 60.
As shown in fig. 3, in practical application, the optical axis of the projection optical system 10 is taken as a main optical axis, and the main optical axis, the normal line of the beam combining surface of the beam combining prism 12, the normal line of the geometric center of the target surface of the first digital micromirror device 20, and the normal line of the geometric center of the target surface of the second digital micromirror device 30 are coplanar; the included angle between the beam combining surface of the beam combining prism 12 and the main optical axis is 45 degrees, the normal line of the geometric center of the target surface of the first digital micro-mirror device 20 is collinear with the main optical axis, and the normal line of the geometric center of the target surface of the second digital micro-mirror device 30 is perpendicular to the main optical axis; the optical axis of the first illumination optical system 60 is perpendicular to the incident surface of the first total internal reflection prism, and the included angle between the optical axis of the illumination optical system 60 and the normal line of the total internal reflection surface of the first total internal reflection prism 50 is larger than the critical angle in order to ensure that the light beam incident on the total internal reflection surface of the first total internal reflection prism 30 can be totally emitted; similarly, the optical axis of the second illumination optical system 70 is perpendicular to the incident surface of the second total internal reflection prism, the included angle between the optical axis of the illumination optical system 70 and the normal line of the total internal reflection surface of the second total internal reflection prism 50 is 8.3 degrees, and the included angle between the optical axis of the illumination optical system 70 and the normal line of the total internal reflection surface of the second total internal reflection prism is larger than the critical angle; the micromirror of the digital micromirror device can turn over + -12 degrees around the diagonal, so as to ensure that the on-state light beam in the turning over +12 degrees can exit along the normal line of the geometric center of the target surface of the digital micromirror device, and the included angle between the optical axis of the illumination optical system after being turned over by the internal total reflection prism and the normal line of the geometric center of the target surface of the digital micromirror device is 24 degrees. The layout described in this embodiment can be applied to any band projection optical engine design.
Referring to fig. 2 and 4, in the projection optical system 10 of the present embodiment, the common aperture device 11 is provided with a first positive lens 111, a first negative lens 112, a second positive lens 113, a third positive lens 114, a second negative lens 115, a fourth positive lens 116, and a third negative lens 117 in this order from left to right along the optical axis of the projection optical system, and all lens surfaces are spherical.
The first positive lens 111 is a meniscus lens, and may be a spherical lens made of H-ZBAF20 material; the first negative lens 112 is a biconcave lens, which can be a spherical mirror made of H-LAF4 material; the second positive lens 113 is a biconvex lens, and can be a spherical mirror made of H-ZF6 material; the third positive lens 114 is a biconvex lens, and can be a spherical lens made of H-FK61 material; the second negative lens 115 is a meniscus lens, which may be a spherical mirror made of H-ZF1 material; the fourth positive lens 116 is a biconvex lens, and can be a spherical mirror made of H-FK61 material; the third negative lens 117 is a biconcave lens, and may be a spherical mirror made of H-ZF4 material.
In addition, the first positive lens 111 and the first negative lens 112 are combined into a first doublet lens, the third positive lens 114 and the second negative lens 115 are combined into a second doublet lens, and the fourth positive lens 116 and the third negative lens 117 are combined into a third doublet lens. The beam combining prism 12 is a cube of size 50.8 mm ×50.8 mm ×50.8 mm made of N-BK7 material.
Specific parameters concerning the optical elements in the projection optical system are shown in table 1.
TABLE 1 specific parameters of optical elements in projection optical systems
In the optimization process, the projection optical system 10 further comprises a beam combining prism 12, two total internal reflection prisms which are unfolded into parallel plates and window glass of two digital micromirror devices, and all the parts are used as a whole to perform optimization design together. Since the size and material of the beam combining prism 12, the size and material of the parallel plates of the total internal reflection prism and the window glass size and material of the dmd are all determined, the aberration of the projection optical system 10 can only be balanced by reasonably distributing the parameters of the lenses of the common aperture portion 11 and the air space between the optical elements. In addition, the light beam loaded with the image information after being combined by the beam combining prism 12 is collimated by the common aperture device 11, and finally is emitted as parallel light.
As shown in fig. 2, in the present embodiment, the first illumination optical system 60 includes a first light emitting diode light source 601, a first aspherical biconvex lens 602, a first aspherical biconvex lens round stop 603, a first double-row fly-eye lens array square stop 604, a first double-row fly-eye lens array 605, and a first plano-convex lens 606, which are arranged in order from the light beam propagation direction along the optical axis. Wherein the effective radiation size diameter of the first led light source 601 is 3.5 mm, and the beam divergence angle is 125 °; the double-row fly-eye lens array 605 is formed by combining two single-row fly-eye lens arrays made of B270 materials back to back, the size of the sub-lenses is 3 mm multiplied by 4 mm, and the focal length of the sub-lenses is 38.1 mm.
As shown in fig. 5, the first illumination optical system 60 is an optical design in which the first total internal reflection prism 40 is unfolded into a parallel plate and is a part of the illumination optical system; the first aspheric biconvex lens 602 is used for collecting the light beam emitted by the first light emitting diode light source 601 and collimating the light beam into parallel light, and the first double-row fly-eye lens array 605 is used for shaping and homogenizing the incident parallel light; the first aspheric biconvex lens 602, the first double-row fly-eye lens array 605, the first plano-convex lens 606 and the parallel flat plate unfolded by the first total internal reflection prism 40 together form a Kohler illumination optical structure, and the light beam from the light-emitting diode light source 601 finally enters the target surface of the first digital micro-mirror device 20 as parallel light and forms a rectangular light spot matched with the target surface. The first aspheric biconvex lens round diaphragm 603, the first double-row fly-eye lens array square diaphragm 604 and other diaphragms function to limit the illumination beam range and improve the illumination uniformity. The second illumination optical system 70 is identical to the first illumination optical system 60, and specific parameters of the optical elements in the illumination optical system are shown in table 2.
TABLE 2 specific parameters of optical elements in illumination optical systems
Wherein, the 4 th order aspheric coefficient of the surface S30 (S37) is 3.4036e-006,6 th order aspheric coefficient is 6.8363e-009,8 th order aspheric coefficient and is-1.9656 e-011.
As shown in fig. 6, the target surface of the digital micromirror device was divided into 15×11 regions, and the illuminance value of each region was simulated and analyzed, and the result showed that the illuminance average value of the illumination optical system of the dual-path common-caliber projection optical engine based on the dual-total internal reflection prism beam splitting was 0.0012533W/mm 2, and the relevant standard deviation was 4.8009E-5, indicating that the illumination uniformity was good.
As shown in fig. 7, the distortion of the dual-path common-caliber projection optical engine of the dual-total internal reflection prism beam splitting described in this embodiment is less than 0.8%, which means that the distortion of the projection optical system is small.
As shown in fig. 8, the optical modulation transfer function curves of the dual-light path common aperture projection optical engine of the dual-total internal reflection prism beam split according to the present embodiment are all greater than 0.6 at the position of 40C/mm, which indicates that the aberration is well corrected, and the imaging quality is good.
Claims (10)
1. A dual-path co-aperture projection optical engine for splitting light by a dual-total internal reflection prism, comprising: a first beam propagation system, a second beam propagation system, a barrier, and a projection optical system;
the first beam propagation system includes: a first illumination optical system, a first total internal reflection prism, and a first digital micromirror device; the second beam propagation system includes: a second illumination optical system, a second total internal reflection prism, and a second digital micromirror device; the projection optical system includes: a beam combining prism and a common caliber device;
the first illumination optical system is used for generating and emitting a first light beam and emitting the first light beam into the first total internal reflection prism;
the first total internal reflection prism is used for injecting the first light beam into the first digital micro-mirror device;
the first digital micro-mirror device is used for loading the image information of the first light beam and outputting first on-state light and first off-state light;
the second illumination optical system is used for generating and emitting a second light beam and emitting the second light beam into the second total internal reflection prism;
the second total internal reflection prism is used for injecting the second light beam into the second digital micro-mirror device;
the second digital micro-mirror device is used for loading the image information of the second light beam and outputting second on-state light and second off-state light;
the beam combining prism is used for combining the first on-state light and the second on-state light to obtain combined light;
the common aperture device is used for projecting the combined beam;
the light barrier is used for receiving the first off-state light and the second off-state light.
2. The dual path common aperture projection optical engine of claim 1 wherein the optical axis of said first illumination optical system is collinear with the center normal of the entrance face of said first total internal reflection prism; the optical axis of the second illumination optical system is collinear with the normal line of the center of the incidence surface of the second total internal reflection prism.
3. The dual-path common-caliber projection optical engine for splitting light by a dual-total internal reflection prism as claimed in claim 1, wherein the first total internal reflection prism and the second total internal reflection prism respectively comprise two stray light eliminating baffles for intercepting stray light.
4. The dual optical path common aperture projection optical engine of claim 1, wherein the common aperture device comprises a spherical lens group comprising seven spherical lenses, respectively: the first positive lens, the first negative lens, the second positive lens, the third positive lens, the second negative lens, the fourth positive lens and the third negative lens are sequentially arranged along the light path direction.
5. The dual optical path common aperture projection optical engine of claim 4, wherein the first positive lens is a meniscus positive lens, the first negative lens is a biconcave negative lens, the second positive lens is a biconvex positive lens, the third positive lens is a biconvex positive lens, the second negative lens is a meniscus negative lens, the fourth positive lens is a biconvex positive lens, and the third negative lens is a biconcave negative lens.
6. The dual path co-aperture projection optical engine of claim 1 wherein said first illumination optical system comprises: the first collimating aspheric biconvex lens, the first collimating aspheric biconvex lens circular aperture, the first double-row fly-eye lens array Fang Guanglan, the first double-row fly-eye lens array, the first plano-convex lens and the first plano-convex lens aperture are sequentially arranged along the light path; the second illumination optical system includes: the second collimating aspheric biconvex lens, the second collimating aspheric biconvex lens circular aperture, the second double-row fly-eye lens array Fang Guanglan, the second double-row fly-eye lens array, the second plano-convex lens and the second plano-convex lens aperture are sequentially arranged along the light path.
7. The dual optical path common aperture projection optical engine of claim 6, wherein said first collimating aspheric biconvex lens and said second collimating aspheric biconvex lens are configured to collect and collimate light beams into parallel light, and wherein said first double-row fly-eye lens array and said second double-row fly-eye lens array are configured to shape and homogenize the parallel light.
8. The dual optical path common aperture projection optical engine of claim 6, wherein said first double-row fly-eye lens array and said first double-row fly-eye lens array square aperture rotate 45 ° around the optical axis of said first illumination optical system; the second double-row fly-eye lens array and the second double-row fly-eye lens array square diaphragm rotate 45 degrees around the optical axis of the second illumination optical system.
9. The dual optical path common aperture projection optical engine of claim 1 wherein said first illumination optical system and said first total internal reflection prism rotate 45 ° about a target surface geometric center normal of said first digital micromirror device; the second illumination optical system and the second total internal reflection prism are rotated by 45 degrees around the normal line of the geometric center of the target surface of the second digital micro-mirror device.
10. The dual path co-aperture projection optical engine of claim 1 wherein the optical engine has an operating band of 440 nm to 656 nm and an angle of view of 9.2 ° x 6.9 °.
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| US20050280779A1 (en) * | 2004-06-07 | 2005-12-22 | Fujinon Corporation | Projecting display apparatus |
| JP2017015927A (en) * | 2015-07-01 | 2017-01-19 | 株式会社リコー | Image display unit |
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