Projection optical system

Abstract

The invention discloses a projection optical system. The projection optical system comprises a first positive lens, a second negative lens, a third negative lens and a fourth positive lens which are sequentially arranged from an object plane to an image plane along an optical axis; the first positive lens and the fourth positive lens are respectively provided with double convex surfaces; the second negative lens and the third negative lens are respectively provided with double concave surfaces; the image side surface of the third negative lens is glued with the object surface side of the fourth positive lens; the system has a relatively large imaging angle and relatively high resolution, is beneficial to improving the environment and temperature adaptability and improving the working performance, and can stably image in high and low temperature environments; the projection distance can be shortened, the device size is reduced, the imaging quality can be improved, and imaging is clear.

Description

Technical Field

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

[0002] Micro-LED (micro light emitting diode) is a self-luminous micro display device, the core of which is a two-dimensional array of high-density micro-sized light emitting diodes. It has many advantages such as low operating voltage, high luminous efficiency, fast response rate, wide operating temperature range, and strong ability to adapt to harsh environments. In addition, Micro-LED has high luminous brightness, each pixel can be driven individually, and the size of its light-emitting unit can be controlled to the micron level to achieve high-resolution display. Due to its excellent characteristics in brightness, life, resolution and efficiency, it has become the focus of research and is regarded as the cornerstone of the next generation of display technology. It has also become the best choice for the integration of light source and image source in ultra-micro projection display optical engine.

[0003] The monolithic Micro-LED micro-projection optical system consists of a monolithic Micro-LED display chip and a micro-projection lens. The light beam is emitted by the Micro-LED light source and projected to the near-eye display element through the micro-projection lens. The micro-projection lenses in the prior art have the defects of limited imaging angle and resolution, and unsatisfactory adaptability to the environment and temperature. Summary of the invention

[0004] The present application proposes a projection optical system that overcomes the defects of existing micro-projection lenses, such as limited imaging angle and resolution, and less than ideal adaptability to environment and temperature; it has a larger imaging angle and higher resolution, which is conducive to improving environmental and temperature adaptability and working performance, and clear imaging.

[0005] An embodiment of the present application provides a projection optical system.

[0006] The present application embodiment adopts the following technical solutions: A projection optical system comprises a first positive lens, a second negative lens, a third negative lens and a fourth positive lens which are arranged in sequence from an object plane to an image plane along an optical axis; the first positive lens and the fourth positive lens respectively have a double convex surface, the second negative lens and the third negative lens respectively have a double concave surface; the image side surface of the third negative lens is glued to the object side surface of the fourth positive lens.

[0007] Preferably, the materials of the first positive lens, the second negative lens, the third negative lens and the fourth positive lens are arranged in order: H-LAF3, H-ZF6, H-QK3L and H-ZBAF21.

[0008] Preferably, the image-side surface of the third negative lens is glued to the object-side surface of the fourth positive lens.

[0009] Preferably, the surface types of the first positive lens, the second negative lens, the third negative lens and the fourth positive lens all include standard spherical surfaces.

[0010] Preferably, the effective focal length of the projection optical system is 4.141 mm, and the total optical length is 4.563 mm.

[0011] Preferably, the radius of curvature of the object side surface of the first positive lens is 1.351mm, and the radius of curvature of the image side surface is -49.000mm; the radius of curvature of the object side surface of the second negative lens is -4.240mm, and the radius of curvature of the image side surface is 1.340mm; the radius of curvature of the object side surface of the third negative lens is -142.290mm, and the radius of curvature of the image side surface is 4.109mm; the radius of curvature of the object side surface of the fourth positive lens is 4.109mm, and the radius of curvature of the image side surface is -2.610mm.

[0012] Preferably, the thicknesses of the first positive lens, the second negative lens, the third negative lens and the fourth positive lens are 0.390 mm, 0.130 mm, 0.130 mm and 0.240 mm respectively.

[0013] Preferably, the distance between the image side surface of the first positive lens and the object side surface of the second negative lens, the distance between the image side surface of the second negative lens and the object side surface of the third negative lens, and the distance between the image side surface of the third negative lens and the object side surface of the fourth negative lens are 0.126 mm, 0.345 mm and 0.000 mm respectively.

[0014] Preferably, a stop is arranged between the second negative lens and the third negative lens.

[0015] Preferably, the distance between the image side surface of the second negative lens and the aperture and the distance between the aperture and the object side surface of the third negative lens are 0.100 mm and 0.245 mm respectively.

[0016] At least one of the above technical solutions adopted in the embodiments of the present application can achieve the following beneficial effects: The projection optical system of the present application can overcome the defects of existing micro-projection lenses, such as limited imaging angle and resolution, and less than ideal adaptability to environment and temperature; it has a larger imaging angle and higher resolution, which is conducive to improving environmental and temperature adaptability and improving working performance, and can stably form images in high and low temperature environments; it can shorten the projection distance, reduce the size of the device, and can improve the imaging quality, making the imaging clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 It is a structural schematic diagram of the projection optical system of the present application; Figure 2 A first field of view point diagram of the projection optical system of the present application; Figure 3 A second field of view point diagram of the projection optical system of the present application; Figure 4 A third field of view point diagram of the projection optical system of the present application; Figure 5 A fourth field of view point diagram of the projection optical system of the present application; Figure 6 A fifth field of view point diagram of the projection optical system of the present application; Figure 7 is a sixth field of view point diagram of the projection optical system of the present application; Figure 8 A bar graph of the field curve of the projection optical system of the present application; Fig. 9 A line diagram of the distortion of the projection optical system of the present application; Reference numerals in the figure: 1 is the first positive lens, 2 is the second negative lens, 3 is the third negative lens, 5 is the aperture, 6 is the image plane, and 7 is the light. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in combination with the specific embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0019] The technical solutions provided by various embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0020] Example Please refer to Figure 1This embodiment provides a projection optical system, comprising a first positive lens 1, a second negative lens 2, a third negative lens 3 and a fourth positive lens 4, which are arranged in sequence from the object side to the image side along the optical axis. The first positive lens 1 is a positive focus lens, whose object side surface is convex and whose image side surface is convex; the second negative lens 2 is a negative focus lens, whose object side surface is concave and whose image side surface is concave; the third negative lens 3 is a negative focus lens, whose object side surface is concave and whose image side surface is concave; the fourth positive lens 4 is a positive focus lens, whose object side surface is convex and whose image side surface is convex; the image side surface of the third negative lens 3 is glued to the object side of the fourth positive lens 4.

[0021] Among them, the object side refers to the side facing the object plane, and the image side refers to the side facing the image plane 6. The first positive lens 1 is a lens with positive optical power, and its object side is convex, and its image side is convex; the second negative lens 2 is a lens with negative optical power, and its object side is concave, and its image side is concave; the third negative lens 3 is a lens with negative optical power, and its object side is concave, and its image side is concave; the fourth positive lens 4 is a lens with positive optical power, and its object side is convex, and its image side is convex. The image side of the third negative lens 3 and the object side of the fourth positive lens 4 are connected by gluing to form a combined lens.

[0022] The projection optical system of this embodiment can shorten the projection distance and reduce the size of the device; it has a larger imaging angle and a higher resolution, and can improve the imaging quality to make the imaging clear; it is beneficial to improve the environmental and temperature adaptability and improve the working performance, and is conducive to stable imaging in high and low temperature environments.

[0023] Specifically, each lens body can use a glass lens, which is conducive to ensuring strong adaptability to the environment and temperature, and ensuring stable operation in high and low temperature environments, so that the working performance is superior and the imaging is clearer.

[0024] In some embodiments, the material of the first positive lens 1 is H-LAF3, the material of the second negative lens 2 is H-ZF6, the material of the third negative lens 3 is H-QK3L, and the material of the fourth positive lens 4 is H-ZBAF21.

[0025] In some embodiments, the projection optical system has an effective focal length (EFFL) of 4.141 mm, an entrance pupil diameter (ENPD) of 0.700 mm, and a total optical length (TOTR) of 4.563 mm.

[0026] The effective focal length refers to the distance from the optical rear principal point of the projection optical system to its focus, and refers to the distance required to focus the parallel light 7 into one point in the projection optical system.

[0027] The total optical length refers to the distance between the intersection of the object side surface of the first positive lens 1 and the optical axis and the image plane 6 of the projection optical system.

[0028] The entrance pupil diameter refers to the maximum incident light beam diameter of a beam of light 7 parallel to the optical axis of the projection optical system, which can enter from the front of the projection optical system and pass through the projection optical system.

[0029] In some embodiments, the object side surface curvature radius of the first positive lens 1 is 1.351 mm, and the image side surface curvature radius of the first positive lens 1 is -49.000 mm; the object side surface curvature radius of the second negative lens 2 is -4.240 mm, and the image side surface curvature radius of the second negative lens 2 is 1.340 mm; the object side surface curvature radius of the third negative lens 3 is -142.290 mm, and the image side surface curvature radius of the third negative lens 3 is 4.109 mm; the object side surface curvature radius of the fourth positive lens 4 is 4.109 mm, and the image side surface curvature radius of the fourth positive lens 4 is -2.610 mm.

[0030] In some embodiments, an aperture 5 is provided between the second negative lens 2 and the third negative lens 3. The distance along the optical axis from the object side of the first positive lens 1 to its image side is 0.390 mm; the distance along the optical axis from the image side of the first positive lens 1 to the object side of the second negative lens 2 is 0.126 mm; the distance along the optical axis from the image side of the second negative lens 2 to its image side is 0.130 mm; the distance along the optical axis from the image side of the second negative lens 2 to the aperture surface is 0.100 mm; the distance along the optical axis from the aperture surface to the object side of the third negative lens 3 is 0.245 mm; the distance along the optical axis from the object side of the third negative lens 3 to its image side is 0.130 mm; the distance along the optical axis from the image side of the third negative lens 3 to the object side of the fourth positive lens 4 is 0.000 mm; the distance along the optical axis from the object side of the fourth positive lens 4 to its image side is 0.240 mm; the distance along the optical axis from the image side of the fourth positive lens 4 to the image plane 6 is 3.202 mm.

[0031] like Figures 2 to 7 As shown in Table 1, the projection optical system of this embodiment has reached the diffraction limit in each field of view.

[0032] Table 1. Figures 2 to 7 The various point diagrams are explained as follows:

[0033] Figures 2 to 7 In the figure, the horizontal axis represents the field of view. For example, the image height radius of the first field of view is 0.000 mm, that is, the first field of view is the central field of view; the image height radius of the second field of view is 0.300 mm; and the black circle represents the Airy disk diameter.

[0034] like Figure 8 As shown, in the projection optical system of this embodiment, the field curvature has little influence on the optical system.

[0035] Figure 8 In the figure, the legend corresponds to the wavelength: 0.625 μm; The horizontal axis represents the field curvature, unit: mm; the vertical axis represents the field of view, unit: °; the maximum field of view is 21.683°; Sagittal field curvature: 0.0394mm, Meridian field curvature: 0.0074mm.

[0036] like Fig. 9 As shown, the projection optical system of this embodiment has a maximum field of view distortion of less than 1%, which meets the actual imaging requirements.

[0037] Fig. 9 The legend corresponds to the wavelength: 0.625 μm.

[0038] The horizontal axis represents distortion, unit: %; the vertical axis represents field of view, unit: °; Maximum field of view: 21.683°; maximum distortion: 0.7631%.

[0039] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of further restrictions, the elements defined by the sentence "comprises..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0040] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "a", "an", "said" and "the" used may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when an element is "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0041] Those skilled in the art will understand that unless otherwise defined, all terms (including technical, technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs.

[0042] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A projection optical system, characterized in that: It comprises a first positive lens (1), a second negative lens (2), a third negative lens (3) and a fourth positive lens (4) which are arranged in sequence from the object plane to the image plane (6) along the optical axis; The first positive lens (1) and the fourth positive lens (4) respectively have a double convex surface, and the second negative lens (2) and the third negative lens (3) respectively have a double concave surface; the image side surface of the third negative lens (3) is glued to the object side surface of the fourth positive lens (4).

2. The projection optical system according to claim 1, characterized in that: The materials of the first positive lens (1), the second negative lens (2), the third negative lens (3) and the fourth positive lens (4) are, in order: H-LAF3, H-ZF6, H-QK3L and H-ZBAF21.

3. The projection optical system according to claim 1, characterized in that: The image side surface of the third negative lens (3) is glued to the object side surface of the fourth positive lens (4).

4. The projection optical system according to claim 1, characterized in that: The surface types of the first positive lens (1), the second negative lens (2), the third negative lens (3) and the fourth positive lens (4) all include standard spherical surfaces.

5. The projection optical system according to any one of claims 1 to 4, characterized in that: The effective focal length of the projection optical system is 4.141 mm, the entrance pupil diameter is 0.700 mm, and the total optical length is 4.563 mm.

6. The projection optical system according to claim 5, characterized in that: The radius of curvature of the object side surface of the first positive lens (1) is 1.351 mm, and the radius of curvature of the image side surface is -49.000 mm; The curvature radius of the object side surface of the second negative lens (2) is -4.240 mm, and the curvature radius of the image side surface is 1.340 mm; The object side surface of the third negative lens (3) has a curvature radius of -142.290 mm, and the image side surface has a curvature radius of 4.109 mm; The curvature radius of the object side surface of the fourth positive lens (4) is 4.109 mm, and the curvature radius of the image side surface is -2.610 mm.

7. The projection optical system according to claim 6, characterized in that: The thicknesses of the first positive lens (1), the second negative lens (2), the third negative lens (3) and the fourth positive lens (4) are 0.390 mm, 0.130 mm, 0.130 mm and 0.240 mm respectively.

8. The projection optical system according to claim 7, characterized in that: The distance between the image side surface of the first positive lens (1) and the object side surface of the second negative lens (2), the distance between the image side surface of the second negative lens (2) and the object side surface of the third negative lens (3), and the distance between the image side surface of the third negative lens (3) and the object side surface of the fourth negative lens (4) are 0.126 mm, 0.345 mm and 0.000 mm respectively.

9. The projection optical system according to claim 8, characterized in that: A stop (5) is provided between the second negative lens (2) and the third negative lens (3).

10. The projection optical system according to claim 9, characterized in that: The distance between the image side surface of the second negative lens (2) and the aperture (5) and the distance between the aperture (5) and the object side surface of the third negative lens (3) are 0.100 mm and 0.245 mm respectively.

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