CN114114614A - Short-focus projection optical system - Google Patents
Short-focus projection optical system Download PDFInfo
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- CN114114614A CN114114614A CN202111285873.8A CN202111285873A CN114114614A CN 114114614 A CN114114614 A CN 114114614A CN 202111285873 A CN202111285873 A CN 202111285873A CN 114114614 A CN114114614 A CN 114114614A
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- 230000003287 optical effect Effects 0.000 title claims abstract description 57
- 238000000034 method Methods 0.000 claims description 5
- 239000011521 glass Substances 0.000 claims description 3
- 230000001681 protective effect Effects 0.000 claims description 2
- 238000006073 displacement reaction Methods 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 238000012545 processing Methods 0.000 abstract description 5
- 238000005286 illumination Methods 0.000 abstract description 4
- 230000004075 alteration Effects 0.000 description 14
- 238000010586 diagram Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 201000009310 astigmatism Diseases 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 230000005499 meniscus Effects 0.000 description 2
- 238000004026 adhesive bonding Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000005304 optical glass Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
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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
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/22—Telecentric objectives or lens systems
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/24—Optical objectives specially designed for the purposes specified below for reproducing or copying at short object distances
-
- 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
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
Abstract
The invention discloses a short-focus projection optical system, which comprises the following components in sequence from an object side to an image side: the first lens group is a fixed group and has negative focal power; the second lens group can move along the direction of an optical axis and has negative focal power and is used for focusing different object distances; the third lens group can move along the direction of an optical axis and has negative focal power and is used for focusing different object distances; the fourth lens group is a fixed group and has positive focal power; the fifth lens group is a fixed group and has positive focal power. The invention has the advantages of ultra-short throw ratio, large aperture, high resolution, telecentric image space, low distortion and high relative illumination through the lens combination with different focal powers, realizes ultra-short focal length on the premise of avoiding using an aspheric surface reflector, and improves the processing and manufacturing feasibility.
Description
Technical Field
The invention relates to the field of optical systems, in particular to a short-focus projection optical system.
Background
At present, most of high-brightness engineering projectors on the market are short-focus and medium-focus optical systems with the projection ratio of more than 0.5, and shorter projection ratios are few and less than optical systems. In the field of laser televisions, a common ultra-short-focus optical system adopts a split-type return light path optical system, and the free-form surface reflector is difficult to process and manufacture and detect surface type accuracy, so that the product cost is high and the yield is low.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a short-focus projection optical system which is used for solving the problems of large projection ratio, complex structure, high cost and the like of a high-brightness engineering projection lens in the prior art.
A short-focus projection optical system according to an embodiment of the present invention includes, in order from an object side to an image side: the first lens group is a fixed group and has negative focal power; the second lens group can move along the direction of an optical axis and has negative focal power and is used for focusing different object distances; the third lens group can move along the direction of an optical axis and has negative focal power and is used for focusing different object distances; the fourth lens group is a fixed group and has positive focal power; the fifth lens group is a fixed group and has positive focal power.
The short-focus projection optical system provided by the embodiment of the invention at least has the following beneficial effects: the invention has the advantages of ultra-short throw ratio, large aperture, high resolution, telecentric image space, low distortion and high relative illumination by arranging the lens combinations with different focal powers, realizes ultra-short focal length on the premise of avoiding using an aspheric surface reflector, improves the feasibility of processing and manufacturing, uses the aspheric surface lens made of the organic optical glass material which accords with the existing processing technology, and further reduces the cost and improves the yield.
According to some embodiments of the present invention, the first lens group includes at least one negative lens and at least one aspheric lens; the second lens group comprises at least one negative lens; the fourth lens group includes at least one positive lens therein.
According to some embodiments of the invention, the short focus projection optical system has a focal length f of 5.3mm and an Fno of 2.1.
According to some embodiments of the invention, each lens group satisfies the following formula:
-8.0<f1/f<-12；
-2.0<f2/f<-5；
-25<f3/f<-33；
8.0<f4/f<12；
4.0<f5/f<7；
where f is the effective focal length of the optical system, f1Is the focal length of the first lens group, f2Is the focal length of the second lens group, f3Is the focal length of the third lens group, f4Is the focal length of the fourth lens group, f5Is the focal length of the fifth lens group.
According to some embodiments of the present invention, during focusing with a gradually increasing throw distance, an air space between the second lens group and the first lens group and an air space between the third lens group and the fourth lens group are continuously decreased.
According to some embodiments of the present invention, an equivalent prism set and a light valve are disposed between the seventh lens group and the image side.
According to some embodiments of the invention, the light valve is a 0.67 inch light valve chip with a resolution of 1920 x 1200, a pixel pitch of 7.56um, and a nyquist frequency of 67 lP/mm.
According to some embodiments of the invention, the light valve is configured to be offset from the optical axis by plus or minus 50% up or minus 22% left or right.
According to some embodiments of the invention, a protective glass is disposed between the equivalent prism group and the light valve.
According to some embodiments of the present invention, a surface of the fifth lens group facing the object side is provided with a stop.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic diagram of a system configuration according to an embodiment of the present invention;
FIG. 2 is a graph of spherical aberration, astigmatism and field curvature of the Middle terminal in accordance with the present invention;
FIG. 3 is a graph of Near end spherical aberration, astigmatism, and field curvature according to an embodiment of the present invention;
FIG. 4 is a graph of spherical aberration, astigmatism, and field curvature of the Far end in accordance with an embodiment of the present invention;
FIG. 5 is a diagram of aberration of Middle end light according to the embodiment of the present invention;
FIG. 6 is a graph of Near end ray aberration according to an embodiment of the present invention;
FIG. 7 is a diagram illustrating the aberration of the Far end light in the embodiment of the present invention;
FIG. 8 is a Middle-end MTF graph according to an embodiment of the present invention;
FIG. 9 is a Near end MTF graph according to an embodiment of the present invention;
FIG. 10 is a graph of MTF at Far end according to an embodiment of the present invention;
FIG. 11 is a graph of relative illuminance according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
Referring to fig. 1, a short-focus projection optical system according to an embodiment of the present invention includes, in order from an object side to an image side: the first lens group G1 is a fixed group and has negative focal power; a second lens group G2, movable in the optical axis direction and having negative power, for focusing at different object distances; a third lens group G3 movable in the optical axis direction and having negative power for focusing at different object distances; a fourth lens group G4, which is a fixed group and has positive focal power; the fifth lens group G5 is a fixed group and has positive focal power.
In the focusing process, the second lens group G2 and the third lens group G3 move along the optical axis direction, and the total length of the optical system (from the front surface of the first optical lens to the rear surface of the last optical lens) is always kept constant, specifically, in the focusing process with gradually increasing projection distance, the air interval between the second lens group G2 and the first lens group G1 is continuously reduced, and the air interval between the third lens group G3 and the fourth lens group G4 is continuously reduced. Through the lens combination that is provided with different focal powers, match reasonable optical material in order to balance the optical aberration of rectifying at different levels, realize ultrashort throw ratio, big light ring, high resolution, image space telecentric, low distortion, relative contrast height, realized ultrashort focal length under the prerequisite of avoiding using aspheric surface reflector, promote manufacturing feasibility.
In some embodiments of the present invention, the first lens group G1 includes at least one negative lens and at least one aspheric lens, which is favorable for increasing the field angle of the optical system and balancing the correction of the optical distortion and the off-axis aberration; the second lens group G2 comprises at least one negative lens; the fourth lens group G4 includes at least one positive lens therein.
Specifically, the first lens group G1 includes two lenses, as shown in fig. 1, a first aspheric lens on the left side and a negative meniscus lens with the concave surface facing the image side; and the second lens group G2 is composed of a negative meniscus lens with the concave surface facing the image side and a double concave lens, and the third lens group G3, the fourth lens group G4 and the fifth lens group G5 are respectively composed of 2, 3 and 10 lenses, and the specific parameters are as follows:
TABLE 1
The optical system does not contain a cemented lens, and can still maintain excellent optical performance under a long-time high-heat and high-brightness state.
In some embodiments of the invention, each lens group satisfies the following formula:
-8.0<f1/f<-12；
-2.0<f2/f<-5；
-25<f3/f<-33；
8.0<f4/f<12；
4.0<f5/f<7；
where f is the effective focal length of the optical system, f1Is the focal length, f, of the first lens group G12Is the focal length, f, of the second lens group G23Is the focal length, f, of the third lens group G34Is the focal length, f, of the fourth lens group G45Is the focal length of the fifth lens group G5.
In some embodiments of the present invention, an equivalent Prism group Prism and a light valve IMG are disposed between the seventh lens group G7 and the image side.
Further, in some embodiments of the present invention, it is preferred that the light valve IMG be a 0.67 inch light valve chip with a resolution of 1920 × 1200, a pixel pitch of 7.56um, and a Nyquist frequency of 67 lP/mm. Of course, the light modulator chip that can conform to the image height range of the optical system and to the resolution of the optical system is in the applicable range.
In some embodiments of the present invention, the light valve IMG is configured to offset an optical axis, so that a projection image can be shifted up and down, left and right, and the offset shift supports up and down ± 50% and up and down ± 22%, so as to realize a short-focus projection lens with a projection ratio TR of 0.35, an optical distortion of less than 1.3%, and a relative illumination of 80%.
In some embodiments of the present invention, a protection glass is disposed between the equivalent Prism group Prism and the light valve IMG, so as to protect the light valve IMG from being directly damaged by an external force.
In some embodiments of the present invention, a surface of the fifth lens group G5 facing the object side is provided with a stop STO for limiting a beam aperture.
In the embodiment, the total lens length is kept unchanged in the zooming process. The following table is the focusing interval data of the present embodiment:
| Thickness | Near | Middle | Far |
| D0 | 500 | 754 | 1600 |
| D1 | 17.011 | 16.512 | 16.087 |
| D2 | 8.629 | 10.042 | 11.260 |
| D3 | 18.231 | 17.317 | 16.525 |
TABLE 2
The embodiment of the invention adopts a pure transmission type short-focus projection optical system, uses optical elements with perfect processing technology on the premise of realizing ultrashort projection ratio, and greatly improves the processing and manufacturing feasibility.
Fig. 2 to 11 are optical evaluation diagrams of the embodiment of the present invention. Wherein, fig. 2, fig. 3 and fig. 4 are spherical aberration astigmatic field curvature graphs under different projection object distances implemented by the invention, the visible red and green light axial chromatic aberration is corrected, the secondary spectrum is smaller, the optical distortion is less than 1.3%, and the picture distortion degree is small. Fig. 5, 6 and 7 are light aberration diagrams of different projection object distances according to embodiments of the present invention, in which the aberration balance is well corrected and the chromatic aberration of magnification is in a controllable range. FIGS. 8, 9, and 10 are MTF graphs at different projection object distances, and at a shorter object distance, the modulation transfer function of the MTF full field of view at the Nyquist frequency is greater than 0.6, and the performance is excellent; under a long object distance, the direction of the sagittal of the MTF marginal field is slightly reduced, but the light valve can be biased and displaced, and when the light valve is displaced to the marginal field, the light valve is slightly focused, and the marginal field can also reach better performance. Fig. 11 shows relative illuminance of the projection display optical system according to the embodiment of the present invention, where the quality of the relative illuminance directly affects the use experience, and the total field of view of the relative illuminance is greater than 80%, so that the illumination uniformity is excellent.
Further, the aspherical lens curve driving equation of the above embodiment is as follows:
where c is an aspherical curvature, r is a radial coordinate, k is a conic coefficient of a conic surface, and AR1 to AR30 are aspherical coefficients of respective orders. Specific aspheric parameters are as follows:
TABLE 3
Remarks are as follows: the coefficients of the aspheric surfaces of other orders not given are all 0.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents, e.g., the gluing of small air-spaced positive and negative lenses with small differences in radii of curvature, should be considered as a proper extension of this patent, which is within the scope of protection of this patent.
Claims (10)
1. A short-focus projection optical system is characterized in that,
the method comprises the following steps of sequentially arranging from an object side to an image side: a first lens group (G1) which is a fixed group and has negative focal power; a second lens group (G2) movable in the optical axis direction and having negative power for focusing different object distances; a third lens group (G3) movable in the optical axis direction and having negative power for focusing at different object distances; a fourth lens group (G4) which is a fixed group and has positive focal power; and a fifth lens group (G5) which is a fixed group and has positive focal power.
2. A short focus projection optical system according to claim 1, characterized in that: the first lens group (G1) comprises at least one negative lens and at least one aspheric lens; the second lens group (G2) comprises at least one negative lens; the fourth lens group (G4) includes at least one positive lens therein.
3. A short focus projection optical system according to claim 1, characterized in that: the focal length f of the short-focus projection optical system is 5.3mm, and Fno is 2.1.
4. A short focus projection optical system according to claim 1, characterized in that: each lens group satisfies the following formula:
-8.0<f1/f<-12；
-2.0<f2/f<-5；
-25<f3/f<-33；
8.0<f4/f<12；
4.0<f5/f<7；
where f is the effective focal length of the optical system, f1Is the focal length of the first lens group (G1), f2Is the focal length, f, of the second lens group (G2)3Is the focal length of the third lens group (G3), f4Is the focal length, f, of the fourth lens group (G4)5Is the focal length of the fifth lens group (G5).
5. A short focus projection optical system according to claim 1, characterized in that: during focusing with a gradually increasing throw distance, the air space between the second lens group (G2) and the first lens group (G1) is continuously reduced, and the air space between the third lens group (G3) and the fourth lens group (G4) is continuously reduced.
6. A short focus projection optical system according to claim 1, characterized in that: an equivalent Prism group (Prism) and a light valve (IMG) are arranged between the seventh lens group (G7) and the image side.
7. The short-focus projection optical system according to claim 6, characterized in that: the light valve (IMG) is a 0.67 inch light valve chip with a resolution of 1920 x 1200, a pixel pitch of 7.56um, and a Nyquist frequency of 67 lP/mm.
8. The short-focus projection optical system according to claim 6, characterized in that: the light valve (IMG) is used for carrying out offset placement on an optical axis, and the offset displacement supports up and down +/-50% and left and right +/-22%.
9. The short-focus projection optical system according to claim 6, characterized in that: and protective glass is arranged between the equivalent Prism group (Prism) and the light valve (IMG).
10. A short focus projection optical system according to claim 1, characterized in that: a diaphragm (STO) is arranged on one surface of the fifth lens group (G5) facing the object side.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111285873.8A CN114114614B (en) | 2021-11-01 | 2021-11-01 | Short-focus projection optical system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111285873.8A CN114114614B (en) | 2021-11-01 | 2021-11-01 | Short-focus projection optical system |
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Citations (10)
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|---|---|---|---|---|
| JPH02136812A (en) * | 1988-11-18 | 1990-05-25 | Canon Inc | Rear focusing type zoom lens |
| JPH03225308A (en) * | 1990-01-31 | 1991-10-04 | Canon Inc | Rear focus zoom lens |
| JPH07253542A (en) * | 1994-03-15 | 1995-10-03 | Canon Inc | Zoom lens |
| JPH09243918A (en) * | 1996-03-06 | 1997-09-19 | Minolta Co Ltd | Zoom lens |
| CN101071197A (en) * | 2006-05-10 | 2007-11-14 | 富士能株式会社 | Projection zoom lens and projection-type display device |
| JP2009251117A (en) * | 2008-04-02 | 2009-10-29 | Panasonic Corp | Zoom lens system, interchangeable lens device and camera system |
| CN210270355U (en) * | 2018-12-14 | 2020-04-07 | 南阳利达光电有限公司 | Zoom monitoring lens |
| CN111694138A (en) * | 2020-07-15 | 2020-09-22 | 北创光电科技(邵阳)有限公司 | Long-focus continuous zooming projection objective |
| CN112363299A (en) * | 2020-11-16 | 2021-02-12 | 中山联合光电研究院有限公司 | Ultrashort burnt projection optical lens and ultrashort burnt projection optical system |
| CN113109926A (en) * | 2021-04-22 | 2021-07-13 | 湖南长步道光学科技有限公司 | Low-distortion optical system and lens |
-
2021
- 2021-11-01 CN CN202111285873.8A patent/CN114114614B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02136812A (en) * | 1988-11-18 | 1990-05-25 | Canon Inc | Rear focusing type zoom lens |
| JPH03225308A (en) * | 1990-01-31 | 1991-10-04 | Canon Inc | Rear focus zoom lens |
| JPH07253542A (en) * | 1994-03-15 | 1995-10-03 | Canon Inc | Zoom lens |
| JPH09243918A (en) * | 1996-03-06 | 1997-09-19 | Minolta Co Ltd | Zoom lens |
| CN101071197A (en) * | 2006-05-10 | 2007-11-14 | 富士能株式会社 | Projection zoom lens and projection-type display device |
| JP2009251117A (en) * | 2008-04-02 | 2009-10-29 | Panasonic Corp | Zoom lens system, interchangeable lens device and camera system |
| CN210270355U (en) * | 2018-12-14 | 2020-04-07 | 南阳利达光电有限公司 | Zoom monitoring lens |
| CN111694138A (en) * | 2020-07-15 | 2020-09-22 | 北创光电科技(邵阳)有限公司 | Long-focus continuous zooming projection objective |
| CN112363299A (en) * | 2020-11-16 | 2021-02-12 | 中山联合光电研究院有限公司 | Ultrashort burnt projection optical lens and ultrashort burnt projection optical system |
| CN113109926A (en) * | 2021-04-22 | 2021-07-13 | 湖南长步道光学科技有限公司 | Low-distortion optical system and lens |
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| CN114114614B (en) | 2024-06-28 |
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