CN108107654B - Projection optical system - Google Patents

Projection optical system Download PDF

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Publication number
CN108107654B
CN108107654B CN201810140335.1A CN201810140335A CN108107654B CN 108107654 B CN108107654 B CN 108107654B CN 201810140335 A CN201810140335 A CN 201810140335A CN 108107654 B CN108107654 B CN 108107654B
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lens
optical system
projection optical
image
optical axis
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CN108107654A (en
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黄林
陈程
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Zhejiang Sunny Optics Co Ltd
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Zhejiang Sunny Optics Co Ltd
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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
    • 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
    • G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
    • G02B13/003—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having two lenses

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Lenses (AREA)

Abstract

The application discloses a projection optical system, this projection optical system includes in order along the optical axis from image source side to imaging side: a first lens and a second lens. The first lens has positive focal power, and the near imaging side surface of the first lens is a convex surface; the second lens has negative focal power, the side face near the image source is concave, and the side face near the image forming is convex. The center thickness CT1 of the first lens on the optical axis and the center thickness CT2 of the second lens on the optical axis satisfy 0.5 < CT1/CT2 < 1.

Description

Projection optical system
Technical Field
The present application relates to a projection optical system, and more particularly, to a projection optical system including two lenses.
Background
In recent years, with the continuous progress of technology, interactive devices are gradually rising, and the application range of projection lenses is also wider and wider. Today, chip technology and intelligent algorithms are rapidly developed, and three-dimensional images with object position and depth information can be calculated by projecting images to space objects by using an optical projection lens and receiving the image signals. The specific method comprises the following steps: projecting light emitted by an infrared Laser Diode (LD) or a Vertical Cavity Surface Emitting Laser (VCSEL) towards a target object by using an optical projection lens; the projected beam after passing through an optical diffraction element (DOE) achieves a redistribution of the projected image on the target object; and receiving the image projected onto the object by using the imaging lens, and calculating a three-dimensional image containing the position and depth information of the projected object. The three-dimensional image with depth information can be further used for various depth application developments such as biological recognition.
In general, a conventional projection lens for imaging eliminates various aberrations and improves resolution by increasing the number of lenses. However, this leads to an increase in the total optical length (TTL) of the projection lens, and the lens assembly requires structural members such as a lens barrel, so that the overall volume of the lens is large, which is not beneficial to miniaturization of the lens. In addition, the conventional lens structure cannot realize borderless arrangement among lenses in the array lens.
Disclosure of Invention
The present application provides a projection optical system applicable to portable electronic products that at least solves or partially solves at least one of the above-mentioned drawbacks of the prior art.
In one aspect, the present application provides a projection optical system including, in order from an image source side to an imaging side along an optical axis: a first lens and a second lens. The first lens may have positive optical power, and its near imaging side may be convex; the second lens may have a negative power, and the near-image-source side thereof may be concave and the near-image-source side thereof may be convex. The center thickness CT1 of the first lens on the optical axis and the center thickness CT2 of the second lens on the optical axis can satisfy 0.5 < CT1/CT2 < 1.
In one embodiment, the distance TR between the image source surface of the projection optical system and the near-image-source side of the first lens and the distance TR1r4 between the near-image-source side of the first lens and the near-image-side of the second lens on the optical axis may satisfy 0.7 < TR/TR1r4 < 1.3.
In one embodiment, the distance T12 between the first lens and the second lens on the optical axis, the center thickness CT1 of the first lens on the optical axis, and the center thickness CT2 of the second lens on the optical axis may satisfy T12/(CT 1+ct 2) < 0.5.
In one embodiment, the maximum half-caliber DT11 of the near-source side of the first lens and the maximum half-caliber DT21 of the near-source side of the second lens may satisfy 0.6 < DT11/DT21 < 1.
In one embodiment, the radius of curvature R3 of the near-image-source side of the second lens and the radius of curvature R4 of the near-image-source side of the second lens may satisfy 0.3 < R3/R4 < 0.8.
In one embodiment, an on-axis distance SAG21 between an intersection of the near-image-source side of the second lens and the optical axis to a maximum effective half-caliber vertex of the near-image-source side of the second lens and an on-axis distance SAG22 between an intersection of the near-image-side of the second lens and the optical axis to a maximum effective half-caliber vertex of the near-image-side of the second lens may satisfy 0.5 < SAG21/SAG22 < 1.
In one embodiment, the radius of curvature R2 of the near imaging side of the first lens and the total effective focal length f of the projection optical system may satisfy-0.5 < R2/f < 0.
In one embodiment, the shortest wavelength of the practical application wavelength λ of the projection optical system may be 0nm to 100nm shorter than the shortest wavelength of the light source used, and the longest wavelength of the practical application wavelength λ of the projection optical system may be 0nm to 100nm longer than the longest wavelength of the light source used.
In one embodiment, the maximum half field angle HFOV of the projection optics may satisfy a TAN (HFOV) < 0.23.
In one embodiment, the object numerical aperture NA of the projection optical system may satisfy NA.gtoreq.0.18.
In one embodiment, the maximum angle of incidence CRAmax of the chief ray of the projection optical system satisfies CRAmax < 10 °.
In another aspect, the present application also provides a projection optical system including, in order from an image source side to an imaging side along an optical axis: a first lens and a second lens. The first lens may have positive optical power, and its near imaging side may be convex; the second lens may have a negative power, and the near-image-source side thereof may be concave and the near-image-source side thereof may be convex. The distance T12 between the first lens and the second lens on the optical axis, the center thickness CT1 of the first lens on the optical axis and the center thickness CT2 of the second lens on the optical axis can satisfy T12/(CT1+CT2) < 0.5.
The projection optical system has the beneficial effects of miniaturization, high imaging quality and the like by reasonably distributing the focal power, the surface shape, the center thickness of each lens, the axial spacing between each lens and the like of a plurality of (for example, two) lenses. Meanwhile, the projection optical system configured as described above is suitable for a single wavelength band.
Drawings
Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, taken in conjunction with the accompanying drawings. In the drawings:
fig. 1 shows a schematic configuration diagram of a projection optical system according to embodiment 1 of the present application;
fig. 2 shows a distortion curve of the projection optical system of embodiment 1;
fig. 3 shows a schematic configuration diagram of a projection optical system according to embodiment 2 of the present application;
fig. 4 shows a distortion curve of the projection optical system of embodiment 2;
fig. 5 shows a schematic structural view of a projection optical system according to embodiment 3 of the present application;
fig. 6 shows a distortion curve of the projection optical system of embodiment 3;
fig. 7 shows a schematic configuration diagram of a projection optical system according to embodiment 4 of the present application;
fig. 8 shows a distortion curve of the projection optical system of example 4.
Detailed Description
For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed description are merely illustrative of exemplary embodiments of the application and are not intended to limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.
It should be noted that in this specification, the expressions first, second, etc. are only used to distinguish one feature from another feature, and do not represent any limitation of the feature. Accordingly, a first lens discussed below may also be referred to as a second lens, and a second lens may also be referred to as a first lens, without departing from the teachings of the present application.
In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for convenience of explanation. In particular, the spherical or aspherical shape shown in the drawings is shown by way of example. That is, the shape of the spherical or aspherical surface is not limited to the shape of the spherical or aspherical surface shown in the drawings. The figures are merely examples and are not drawn to scale.
Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, then the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens near the image source side is referred to as the near-image source side, and the surface of each lens near the image side is referred to as the near-image side.
It will be further understood that the terms "comprises," "comprising," "includes," "including," "having," "containing," and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Furthermore, when a statement such as "at least one of the following" appears after a list of features that are listed, the entire listed feature is modified instead of modifying a separate element in the list. Furthermore, when describing embodiments of the present application, use of "may" means "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
The features, principles, and other aspects of the present application are described in detail below.
The projection optical system according to an exemplary embodiment of the present application may include, for example, two lenses having optical power, i.e., a first lens and a second lens. The two lenses are sequentially arranged from the image source side to the image side along the optical axis.
In an exemplary embodiment, the first lens may have positive optical power, and its near imaging side may be convex; the second lens may have a negative power, and the near-image-source side thereof may be concave and the near-image-source side thereof may be convex. The first lens has positive power and the second lens has negative power, contributing to shortening the overall length of the projection optical system. The near imaging side of the first lens is convex, which is beneficial to reducing spherical aberration and sensitivity of system tolerance. The side face of the second lens, close to the image source, is concave, and the side face, close to the image, is convex, so that astigmatism of a projection optical system is reduced, and projection imaging quality is improved.
In an exemplary embodiment, the projection optical system of the present application may satisfy the conditional expression 0.5 < CT1/CT2 < 1, where CT1 is a central thickness of the first lens on the optical axis, and CT2 is a central thickness of the second lens on the optical axis. More specifically, CT1 and CT2 may further satisfy 0.55 < CT1/CT2 < 0.85, for example, 0.60.ltoreq.CT 1/CT 2.ltoreq.0.83. The center thickness of the first lens and the second lens is reasonably distributed, so that the lens can be ensured to have shorter total length. Further, by reasonably distributing the center thicknesses of the first lens and the second lens and combining the reasonable configuration of the surface type and the optical power, the lens can be applied to infrared narrow wave bands and can be applied to a speckle projection system.
The wavelength range of the practical application wavelength λ of the projection optical system of the present application has a float of ±100nm based on the wavelength range of the use light source. Specifically, the shortest wavelength of the practical application wavelength λ of the projection optical system may be about 0nm to 100nm shorter than the shortest wavelength of the light source used, and the longest wavelength of the practical application wavelength λ may be about 0nm to 100nm longer than the longest wavelength of the light source used. The projection optical system of the present application may be applied to any monochromatic light source band, for example, the projection optical system of the present application may be applied to an infrared single wavelength band. The monochromatic light source is beneficial to reducing chromatic aberration, stray light and the like caused by wide wavelength, and improving the imaging quality of the projection optical system; at the same time, the projection optical system can be made to meet the requirement of light interface matching of an optical diffraction element (DOE).
In an exemplary embodiment, the projection optical system of the present application may satisfy the conditional expression TAN (HFOV) < 0.23, where HFOV is the maximum half field angle of the projection optical system. More specifically, HFOV's may further satisfy TAN (HFOV) < 0.20, for example, 0.16 TAN (HFOV) 0.18. Satisfies the condition TAN (HFOV) less than 0.23, is beneficial to reducing the divergence angle of the projection beam and increasing the depth of field of the projection; the front depth of field surface and the rear depth of field surface of the projection side are flattened; and also facilitates algorithmic processing to obtain more accurate depth information.
In an exemplary embodiment, the projection optical system of the present application may satisfy the conditional expression 0.7 < TR/TR1r4 < 1.3, where TR is a distance on the optical axis from an image source surface of the projection optical system (for example, may be an infrared Laser Diode (LD) or a light emitting surface of a vertical cavity surface emitting laser VCSEL) to a near-image source side of the first lens, and TR1r4 is a distance on the optical axis from the near-image source side of the first lens to a near-image side of the second lens. More specifically, TR and Tr1r4 may further satisfy 0.76.ltoreq.TR/Tr 1r 4.ltoreq.1.20. The lens meets the condition that TR/Tr1r4 is smaller than 1.3 and 0.7, can ensure the large field angle of the lens, and is beneficial to meeting the assembly requirement and being beneficial to assembly.
In an exemplary embodiment, the projection optical system of the present application may satisfy the conditional expression na+.0.18, where NA is the object numerical aperture of the projection optical system. More specifically, NA may further satisfy 0.18.ltoreq.NA.ltoreq.0.20. The NA meeting the condition is more than or equal to 0.18, and the projection optical system has larger numerical aperture, thereby being beneficial to increasing the light source receiving capacity of the lens and improving the projection energy efficiency, and further obtaining the projection image with higher brightness.
In an exemplary embodiment, the projection optical system of the present application may satisfy the conditional expression CRAmax < 10 °, wherein CRAmax is a maximum incidence angle of a chief ray of the projection optical system. More specifically, CRAMax may further satisfy 0.ltoreq.CRAMax.ltoreq.9.51. The condition CRamax is smaller than 10 degrees, so that the light cone angle of the off-axis light source can be better matched, the off-axis light inlet quantity of the optical system is increased, and the brightness of the projection image is improved.
In an exemplary embodiment, the projection optical system of the present application may satisfy the conditional expression 0.6 < DT11/DT21 < 1, where DT11 is the maximum half-caliber of the near-image-source side of the first lens and DT21 is the maximum half-caliber of the near-image-source side of the second lens. More specifically, DT11 and DT21 may further satisfy 0.72. Ltoreq.DT 11/DT 21. Ltoreq.0.96. Satisfies the condition that DT11/DT21 is less than 1 and 0.6, is favorable to reducing the size influence of the image source on the image side, and improves the projection performance.
In an exemplary embodiment, the projection optical system of the present application may satisfy the conditional expression 0.5 < SAG21/SAG22 < 1, where SAG21 is an on-axis distance between an intersection point of the near-image-source side surface of the second lens and the optical axis to a maximum effective half-caliber vertex of the near-image-source side surface of the second lens, and SAG22 is an on-axis distance between an intersection point of the near-image-source side surface of the second lens and the optical axis to a maximum effective half-caliber vertex of the near-image-source side surface of the second lens. More specifically, SAG21 and SAG22 may further satisfy 0.5 < SAG21/SAG22 < 0.9, e.g., 0.53.ltoreq.SAG 21/SAG 22.ltoreq.0.84. The condition that SAG21/SAG22 is smaller than 0.5 and smaller than 1 is satisfied, the system spherical aberration can be effectively eliminated, and the high-definition image can be obtained.
In an exemplary embodiment, the projection optical system of the present application may satisfy the condition T12/(CT 1+ct2) < 0.5, where T12 is a distance between the first lens and the second lens on the optical axis, CT1 is a center thickness of the first lens on the optical axis, and CT2 is a center thickness of the second lens on the optical axis. More specifically, T12, CT1, and CT2 may further satisfy 0 < T12/(CT1+CT2) < 0.4, for example, 0.10.ltoreq.T12/(CT1+CT2). Ltoreq.0.34. The thickness and the spacing of each lens are reasonably distributed, so that the miniaturization of the projection optical system is facilitated.
In an exemplary embodiment, the projection optical system of the present application may satisfy the conditional expression 0.3 < R3/R4 < 0.8, where R3 is a radius of curvature of the near-image-source side of the second lens and R4 is a radius of curvature of the near-image-source side of the second lens. More specifically, R3 and R4 may further satisfy 0.4 < R3/R4 < 0.7, for example, 0.48.ltoreq.R3/R4.ltoreq.0.68. The curvature radiuses of the side face close to the image source and the side face close to the image forming of the second lens are reasonably arranged, so that the processing and manufacturing of the second lens are facilitated; at the same time, an increase in tolerance sensitivity due to too small a radius of curvature can be avoided.
In an exemplary embodiment, the projection optical system of the present application may satisfy the conditional expression-0.5 < R2/f < 0, where R2 is a radius of curvature of the near imaging side of the first lens, and f is a total effective focal length of the projection optical system. More specifically, R2 and f may further satisfy-0.4 < R2/f < -0.2, for example, -0.30.ltoreq.R2/f.ltoreq.0.23. Satisfies the condition that R2/f is less than 0 and 0, is favorable for reducing astigmatism of a projection optical system and improving projection imaging quality.
In an exemplary embodiment, the projection optical system may further include at least one aperture to improve the imaging quality of the lens. Alternatively, a diaphragm may be provided between the second lens and the imaging side.
The projection optical system can be applied to the field of depth detection as a speckle projection lens. When the projection optical system is used for carrying out depth detection on a target object in space, light rays emitted by an infrared Laser Diode (LD) or a Vertical Cavity Surface Emitting Laser (VCSEL) are firstly amplified by spots of the projection optical system, then pass through an optical diffraction element (DOE), and then are projected towards the direction of the target object. After passing through an optical diffraction element (DOE), the projection beam may achieve a redistribution of the projected image on the target object. Then, the image information projected onto the target object is captured by an arbitrary known imaging lens, and a three-dimensional image having the target object position depth information can be calculated. Projection optics according to the present application can be used in conjunction with optical diffraction elements (DOEs) to accurately achieve a redistribution of the projection beam on the target object.
In an embodiment of the present application, at least one of the mirrors of each lens is an aspherical mirror. The aspherical lens is characterized in that: the curvature varies continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better radius of curvature characteristic, and has advantages of improving distortion aberration and improving astigmatic aberration. By adopting the aspherical lens, aberration occurring at the time of imaging can be eliminated as much as possible, thereby improving imaging quality.
However, those skilled in the art will appreciate that the number of lenses making up a projection lens can be varied to achieve the various results and advantages described in this specification without departing from the technical solutions claimed herein. For example, although two lenses are described as an example in the embodiment, the projection lens is not limited to including two lenses. The projection lens may also include other numbers of lenses, if desired.
Specific examples of the projection optical system applicable to the above-described embodiments are further described below with reference to the drawings.
Example 1
A projection optical system according to embodiment 1 of the present application is described below with reference to fig. 1 and 2. Fig. 1 shows a schematic configuration diagram of a projection optical system according to embodiment 1 of the present application.
As shown in fig. 1, the projection optical system according to the exemplary embodiment of the present application includes, in order from an image source side to an imaging side along an optical axis: a first lens E1, a second lens E2 and a stop STO.
The first lens E1 has positive power, and its near-image-source side surface S1 is convex and its near-image-forming side surface S2 is convex. The second lens E2 has negative focal power, and has a concave near-image-source side S3 and a convex near-image-source side S4. The light from the image source surface OBJ passes through the surfaces S1 to S4 in sequence, and then passes through, for example, an optical diffraction element DOE (not shown), and is projected onto a target object in space.
The practical application wavelength λ of the projection lens of the present embodiment is floating based on the wavelength range using the light source, and the shortest wavelength of the practical application wavelength λ is about 0nm to 100nm shorter than the shortest wavelength using the light source, and the longest wavelength of the practical application wavelength λ is about 0nm to 100nm longer than the longest wavelength using the light source. The light source used in the projection lens of this embodiment may be any monochromatic light source band, for example, an infrared single wavelength band.
Table 1 shows the surface types, the radii of curvature, the thicknesses, the materials, and the cone coefficients of the respective lenses of the projection optical system of example 1, in which the units of the radii of curvature and the thicknesses are millimeters (mm).
TABLE 1
As can be seen from table 1, the near-image-source side surface S1 and the near-image-forming side surface S2 of the first lens E1 and the near-image-source side surface S3 and the near-image-forming side surface S4 of the second lens E2 are aspheric. In the present embodiment, the surface shape x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:
wherein x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at the position with the height h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c=1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 1 above); k is the conic coefficient (given in table 1); ai is the correction coefficient of the aspherical i-th order. Table 2 below shows the higher order coefficients A that can be used for each of the aspherical mirror surfaces S1-S4 in example 1 4 、A 6 、A 8 、A 10 、A 12 、A 14 And A 16 。
Face number A4 A6 A8 A10 A12 A14 A16
S1 -1.1502E-01 1.3757E-01 1.0181E+00 -6.6556E+00 1.7599E+01 -2.2283E+01 1.0967E+01
S2 5.1523E-02 4.5645E-01 -1.0320E+00 1.7345E-01 2.6053E+00 -4.5553E+00 2.7894E+00
S3 3.3156E-01 6.6835E-01 -2.8345E+00 6.2188E+00 -9.0595E+00 8.1095E+00 -2.0576E+00
S4 2.2807E-02 -9.5980E-03 2.2493E-02 -1.1426E-01 1.7499E-01 -1.1895E-01 3.2763E-02
TABLE 2
Table 3 shows the total effective focal length f of the projection optical system, the effective focal lengths f1 and f2 of the respective lenses, the object numerical aperture NA of the projection optical system, and the maximum incidence angle CRAmax of the principal ray in embodiment 1.
Parameters (parameters) f(mm) f1(mm) f2(mm) NA CRAmax(°)
Numerical value 2.79 1.56 -12.76 0.20 0.00
TABLE 3 Table 3
The projection optical system in embodiment 1 satisfies:
CT1/CT2 = 0.60, wherein CT1 is the center thickness of the first lens element E1 on the optical axis, and CT2 is the center thickness of the second lens element E2 on the optical axis;
TR/TR1 r4=0.76, where TR is the distance on the optical axis between the image source surface OBJ and the near-image-source side surface S1 of the first lens E1, and TR1r4 is the distance on the axis between the near-image-source side surface S1 of the first lens E1 and the near-image-source side surface S4 of the second lens E2;
DT11/DT 21=0.96, where DT11 is the maximum half-caliber of the near-source side surface S1 of the first lens element E1, and DT21 is the maximum half-caliber of the near-source side surface S3 of the second lens element E2;
SAG 21/sag22=0.84, wherein SAG21 is an on-axis distance between an intersection point of the near-image-source side surface S3 of the second lens E2 and the optical axis and a maximum effective half-caliber vertex of the near-image-source side surface S3 of the second lens E2, and SAG22 is an on-axis distance between an intersection point of the near-image side surface S4 of the second lens E2 and the optical axis and a maximum effective half-caliber vertex of the near-image side surface S4 of the second lens E2;
T12/(CT 1+ CT 2) =0.12, wherein T12 is the distance between the first lens element E1 and the second lens element E2 on the optical axis, CT1 is the center thickness of the first lens element E1 on the optical axis, and CT2 is the center thickness of the second lens element E2 on the optical axis;
r3/r4=0.57, where R3 is a radius of curvature of the near-image-source side surface S3 of the second lens E2, and R4 is a radius of curvature of the near-image-source side surface S4 of the second lens E2;
r2/f= -0.30, where R2 is the radius of curvature of the near imaging side S2 of the first lens E1 and f is the total effective focal length of the projection optical system.
Fig. 2 shows a distortion curve of the projection optical system of embodiment 1, which represents distortion magnitude values at different viewing angles. As can be seen from fig. 2, the projection optical system provided in embodiment 1 can achieve good imaging quality.
Example 2
A projection optical system according to embodiment 2 of the present application is described below with reference to fig. 3 and 4. In this embodiment and the following embodiments, descriptions of portions similar to embodiment 1 will be omitted for brevity. Fig. 3 shows a schematic configuration diagram of a projection optical system according to embodiment 2 of the present application.
As shown in fig. 3, the projection optical system according to the exemplary embodiment of the present application sequentially includes, along the optical axis from the image source side to the image forming side: a first lens E1, a second lens E2 and a stop STO.
The first lens E1 has positive power, and has a concave near-image-source side surface S1 and a convex near-image-source side surface S2. The second lens E2 has negative focal power, and has a concave near-image-source side S3 and a convex near-image-source side S4. The light from the image source surface OBJ passes through the surfaces S1 to S4 in sequence, and then passes through, for example, an optical diffraction element DOE (not shown), and is projected onto a target object in space.
The practical application wavelength λ of the projection lens of the present embodiment is floating based on the wavelength range using the light source, and the shortest wavelength of the practical application wavelength λ is about 0nm to 100nm shorter than the shortest wavelength using the light source, and the longest wavelength of the practical application wavelength λ is about 0nm to 100nm longer than the longest wavelength using the light source. The light source used in the projection lens of this embodiment may be any monochromatic light source band, for example, an infrared single wavelength band.
Table 4 shows the surface types, the radii of curvature, the thicknesses, the materials, and the cone coefficients of the respective lenses of the projection optical system of example 2, in which the units of the radii of curvature and the thicknesses are millimeters (mm).
TABLE 4 Table 4
As can be seen from table 4, in embodiment 2, the near-image-source side surface S1 and the near-image-forming side surface S2 of the first lens E1 and the near-image-source side surface S3 and the near-image-forming side surface S4 of the second lens E2 are aspherical surfaces. Table 5 shows the higher order coefficients that can be used for each of the aspherical mirror surfaces in example 2, wherein each of the aspherical surface types can be defined by the formula (1) given in example 1 above.
Face number A4 A6 A8 A10 A12 A14 A16
S1 -4.7608E-01 -1.4249E-01 1.9713E+00 -4.9437E+00 1.2902E+01 -1.9901E+01 1.1579E+01
S2 4.2934E-02 -8.5392E-02 8.0723E-01 -2.2377E+00 5.6766E+00 -6.5720E+00 2.8407E+00
S3 2.8902E-02 4.1351E-01 -6.2646E-01 2.1782E-01 2.6001E-01 -2.2879E-01 5.0034E-02
S4 7.9494E-02 -1.1319E-02 2.2816E-02 -1.1540E-01 1.3306E-01 -6.7638E-02 1.3776E-02
TABLE 5
Table 6 shows the total effective focal length f of the projection optical system, the effective focal lengths f1 and f2 of the respective lenses, the object numerical aperture NA of the projection optical system, and the maximum incidence angle CRAmax of the principal ray in embodiment 2.
Parameters (parameters) f(mm) f1(mm) f2(mm) NA CRAmax(°)
Numerical value 2.97 1.94 -15.32 0.20 0.00
TABLE 6
Fig. 4 shows a distortion curve of the projection optical system of embodiment 2, which represents distortion magnitude values at different viewing angles. As can be seen from fig. 4, the projection optical system provided in embodiment 2 can achieve good imaging quality.
Example 3
A projection optical system according to embodiment 3 of the present application is described below with reference to fig. 5 and 6. Fig. 5 shows a schematic configuration diagram of a projection optical system according to embodiment 3 of the present application.
As shown in fig. 5, the projection optical system according to the exemplary embodiment of the present application includes, in order from an image source side to an imaging side along an optical axis: a first lens E1, a second lens E2 and a stop STO.
The first lens E1 has positive power, and has a concave near-image-source side surface S1 and a convex near-image-source side surface S2. The second lens E2 has negative focal power, and has a concave near-image-source side S3 and a convex near-image-source side S4. The light from the image source surface OBJ passes through the surfaces S1 to S4 in sequence, and then passes through, for example, an optical diffraction element DOE (not shown), and is projected onto a target object in space.
The practical application wavelength λ of the projection lens of the present embodiment is floating based on the wavelength range using the light source, and the shortest wavelength of the practical application wavelength λ is about 0nm to 100nm shorter than the shortest wavelength using the light source, and the longest wavelength of the practical application wavelength λ is about 0nm to 100nm longer than the longest wavelength using the light source. The light source used in the projection lens of this embodiment may be any monochromatic light source band, for example, an infrared single wavelength band.
Table 7 shows the surface types, the radii of curvature, the thicknesses, the materials, and the cone coefficients of the respective lenses of the projection optical system of example 3, in which the units of the radii of curvature and the thicknesses are millimeters (mm).
TABLE 7
As can be seen from table 7, in example 3, the near-image-source side surface S1 and the near-image-forming side surface S2 of the first lens E1 and the near-image-source side surface S3 and the near-image-forming side surface S4 of the second lens E2 are aspherical surfaces. Table 8 shows the higher order coefficients that can be used for each of the aspherical mirror surfaces in example 3, wherein each of the aspherical surface types can be defined by the formula (1) given in example 1 above.
Face number A4 A6 A8 A10 A12 A14 A16
S1 -2.5098E-01 2.4397E-01 -1.2270E+00 6.9646E+00 -1.5365E+01 1.5031E+01 -5.5169E+00
S2 3.1574E-01 -5.1571E-01 7.5735E-01 4.8387E-01 -1.9047E+00 1.9615E+00 -6.7456E-01
S3 9.4578E-01 -1.3546E+00 3.7131E+00 -7.1166E+00 8.8522E+00 -6.0079E+00 1.7729E+00
S4 6.2268E-02 -5.7158E-02 9.5985E-02 -1.6408E-01 1.5495E-01 -7.4764E-02 1.4416E-02
TABLE 8
Table 9 shows the total effective focal length f of the projection optical system, the effective focal lengths f1 and f2 of the respective lenses, the object numerical aperture NA of the projection optical system, and the maximum incidence angle CRAmax of the principal ray in embodiment 3.
Parameters (parameters) f(mm) f1(mm) f2(mm) NA CRAmax(°)
Numerical value 2.90 1.38 -5.45 0.18 9.51
TABLE 9
Fig. 6 shows a distortion curve of the projection optical system of embodiment 3, which represents distortion magnitude values at different angles of view. As can be seen from fig. 6, the projection optical system provided in embodiment 3 can achieve good imaging quality.
Example 4
A projection optical system according to embodiment 4 of the present application is described below with reference to fig. 7 and 8. Fig. 7 shows a schematic configuration diagram of a projection optical system according to embodiment 4 of the present application.
As shown in fig. 7, the projection optical system according to the exemplary embodiment of the present application includes, in order from an image source side to an imaging side along an optical axis: a first lens E1, a second lens E2 and a stop STO.
The first lens E1 has positive power, and has a concave near-image-source side surface S1 and a convex near-image-source side surface S2. The second lens E2 has negative focal power, and has a concave near-image-source side S3 and a convex near-image-source side S4. The light from the image source surface OBJ passes through the surfaces S1 to S4 in sequence, and then passes through, for example, an optical diffraction element DOE (not shown), and is projected onto a target object in space.
The practical application wavelength λ of the projection lens of the present embodiment is floating based on the wavelength range using the light source, and the shortest wavelength of the practical application wavelength λ is about 0nm to 100nm shorter than the shortest wavelength using the light source, and the longest wavelength of the practical application wavelength λ is about 0nm to 100nm longer than the longest wavelength using the light source. The light source used in the projection lens of this embodiment may be any monochromatic light source band, for example, an infrared single wavelength band.
Table 10 shows the surface types, the radii of curvature, the thicknesses, the materials, and the cone coefficients of the respective lenses of the projection optical system of example 4, in which the units of the radii of curvature and the thicknesses are millimeters (mm).
Table 10
As can be seen from table 10, in example 4, the near-image-source side surface S1 and the near-image-forming side surface S2 of the first lens E1 and the near-image-source side surface S3 and the near-image-forming side surface S4 of the second lens E2 are aspherical surfaces. Table 11 shows the higher order coefficients that can be used for each of the aspherical mirror surfaces in example 4, wherein each of the aspherical surface types can be defined by the formula (1) given in example 1 above.
Face number A4 A6 A8 A10 A12 A14 A16
S1 -2.1138E-01 -1.1885E-01 -2.4495E-01 9.9349E-01 -2.0730E-01 -2.1751E+00 1.8881E+00
S2 3.3318E-01 -7.0304E-01 1.0383E+00 -2.5415E-01 -1.7032E+00 2.9514E+00 -1.4844E+00
S3 9.9918E-01 -1.5561E+00 4.2884E+00 -8.0178E+00 9.7811E+00 -6.4954E+00 1.8045E+00
S4 6.5903E-02 -6.1438E-02 8.6636E-02 -1.2363E-01 1.0021E-01 -3.8877E-02 5.2154E-03
TABLE 11
Table 12 shows the total effective focal length f of the projection optical system, the effective focal lengths f1 and f2 of the respective lenses, the object numerical aperture NA of the projection optical system, and the maximum incidence angle CRAmax of the principal ray in example 4.
Parameters (parameters) f(mm) f1(mm) f2(mm) NA CRAmax(°)
Numerical value 3.02 1.25 -3.93 0.18 9.36
Table 12
Fig. 8 shows a distortion curve of the projection optical system of embodiment 4, which represents distortion magnitude values at different angles of view. As can be seen from fig. 8, the projection optical system provided in embodiment 4 can achieve good imaging quality.
In summary, examples 1 to 4 satisfy the relationships shown in table 13, respectively.
Conditional\embodiment 1 2 3 4
CT1/CT2 0.60 0.75 0.83 0.76
TAN(HFOV) 0.18 0.17 0.17 0.16
TR/Tr1r4 0.76 1.20 0.86 1.00
NA 0.20 0.20 0.18 0.18
CRAmax(°) 0.00 0.00 9.51 9.36
DT11/DT21 0.96 0.72 0.80 0.79
SAG21/SAG22 0.84 0.53 0.62 0.69
T12/(CT1+CT2) 0.12 0.34 0.14 0.10
R3/R4 0.57 0.68 0.52 0.48
R2/f -0.30 -0.24 -0.23 -0.23
TABLE 13
The foregoing description is only of the preferred embodiments of the present application and is presented as a description of the principles of the technology being utilized. It will be appreciated by persons skilled in the art that the scope of the invention referred to in this application is not limited to the specific combinations of features described above, but it is intended to cover other embodiments in which any combination of features described above or equivalents thereof is possible without departing from the spirit of the invention. Such as the above-described features and technical features having similar functions (but not limited to) disclosed in the present application are replaced with each other.

Claims (21)

1. The projection optical system sequentially includes, from an image source side to an image forming side along an optical axis: a first lens and a second lens, characterized in that,
the first lens has positive focal power, and the near imaging side surface of the first lens is a convex surface;
the second lens has negative focal power, the side face close to the image source is concave, and the side face close to the image is convex;
the number of lenses having optical power in the projection optical system is two;
at least one of the mirror surfaces of each lens in the projection optical system is an aspheric mirror surface;
the center thickness CT1 of the first lens on the optical axis and the center thickness CT2 of the second lens on the optical axis meet 0.5 < CT1/CT2 < 1.
2. The projection optical system according to claim 1, wherein a distance TR on the optical axis from an image source surface of the projection optical system to a near-image source side surface of the first lens and a distance TR1r4 on the optical axis from a near-image source side surface of the first lens to a near-image side surface of the second lens satisfy 0.7 < TR/TR1r4 < 1.3.
3. The projection optical system according to claim 2, wherein a separation distance T12 of the first lens and the second lens on the optical axis, a center thickness CT1 of the first lens on the optical axis, and a center thickness CT2 of the second lens on the optical axis satisfy T12/(CT 1+ct 2) < 0.5.
4. Projection optical system according to claim 1, characterized in that the maximum half-caliber DT11 of the near-image-source side of the first lens and the maximum half-caliber DT21 of the near-image-source side of the second lens satisfy 0.6 < DT11/DT21 < 1.
5. Projection optical system according to claim 1, characterized in that the radius of curvature R3 of the near-image-source side of the second lens and the radius of curvature R4 of the near-image-source side of the second lens satisfy 0.3 < R3/R4 < 0.8.
6. The projection optical system according to claim 5, wherein an on-axis distance SAG21 between an intersection of a near-image-source side of the second lens and the optical axis to a maximum effective half-caliber vertex of the near-image-source side of the second lens and an on-axis distance SAG22 between an intersection of a near-image-forming side of the second lens and the optical axis to a maximum effective half-caliber vertex of the near-image-forming side of the second lens satisfy 0.5 < SAG21/SAG22 < 1.
7. Projection optical system according to claim 1, characterized in that the radius of curvature R2 of the near imaging side of the first lens and the total effective focal length f of the projection optical system satisfy-0.5 < R2/f < 0.
8. Projection optical system according to any one of claims 1 to 7, characterized in that the shortest wavelength of the actual application wavelength λ of the projection optical system is 0nm-100nm shorter than the shortest wavelength of the light source used, and the longest wavelength of the actual application wavelength λ of the projection optical system is 0nm-100nm longer than the longest wavelength of the light source used.
9. Projection optical system according to any one of claims 1 to 7, characterized in that the maximum half field angle HFOV of the projection optical system satisfies TAN (HFOV) < 0.23.
10. Projection optical system according to one of claims 1 to 7, characterized in that the object-side numerical aperture NA of the projection optical system satisfies NA > 0.18.
11. Projection optical system according to one of claims 1 to 7, characterized in that the maximum angle of incidence CRAmax of the chief ray of the projection optical system satisfies CRAmax < 10 °.
12. The projection optical system sequentially includes, from an image source side to an image forming side along an optical axis: a first lens and a second lens, characterized in that,
the first lens has positive focal power, and the near imaging side surface of the first lens is a convex surface;
the second lens has negative focal power, the side face close to the image source is concave, and the side face close to the image is convex;
the number of lenses having optical power in the projection optical system is two;
at least one of the mirror surfaces of each lens in the projection optical system is an aspheric mirror surface;
the central thickness CT1 of the first lens on the optical axis and the central thickness CT2 of the second lens on the optical axis meet 0.5 < CT1/CT2 < 1; and
the interval distance T12 between the first lens and the second lens on the optical axis, the center thickness CT1 of the first lens on the optical axis and the center thickness CT2 of the second lens on the optical axis satisfy T12/(CT 1+ CT 2) < 0.5.
13. The projection optical system according to claim 12, characterized in that the radius of curvature R3 of the near-image-source side of the second lens and the radius of curvature R4 of the near-image-source side of the second lens satisfy 0.3 < R3/R4 < 0.8.
14. Projection optical system according to claim 12 or 13, characterized in that an on-axis distance SAG21 between the intersection of the near-image-source side of the second lens and the optical axis to the maximum effective half-bore vertex of the near-image-source side of the second lens and an on-axis distance SAG22 between the intersection of the near-image side of the second lens and the optical axis to the maximum effective half-bore vertex of the near-image side of the second lens satisfy 0.5 < SAG21/SAG22 < 1.
15. Projection optical system according to claim 12, characterized in that the radius of curvature R2 of the near imaging side of the first lens and the total effective focal length f of the projection optical system satisfy-0.5 < R2/f < 0.
16. The projection optical system according to claim 15, wherein a distance TR on the optical axis from an image source surface of the projection optical system to a near-image source side of the first lens and a distance TR1r4 on the optical axis from a near-image source side of the first lens to a near-image side of the second lens satisfy 0.7 < TR/TR1r4 < 1.3.
17. The projection optical system according to claim 12, wherein a maximum half-caliber DT11 of the near-image-source side of the first lens and a maximum half-caliber DT21 of the near-image-source side of the second lens satisfy 0.6 < DT11/DT21 < 1.
18. The projection optical system according to claim 17, characterized in that the maximum half field angle HFOV of the projection optical system satisfies TAN (HFOV) < 0.23.
19. The projection optical system according to claim 18, characterized in that an object-side numerical aperture NA of the projection optical system satisfies NA > 0.18.
20. Projection optical system according to claim 18, characterized in that the maximum angle of incidence CRAmax of the chief ray of the projection optical system satisfies CRAmax < 10 °.
21. The projection optical system according to claim 12, characterized in that the shortest wavelength of the actual application wavelength λ of the projection optical system is 0nm-100nm shorter than the shortest wavelength of the light source used, and the longest wavelength of the actual application wavelength λ of the projection optical system is 0nm-100nm longer than the longest wavelength of the light source used.
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CN201083875Y (en) * 2007-09-07 2008-07-09 浙江舜宇光学有限公司 Micro-optical lens
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