A projection optical system

Abstract

This application discloses a projection optical system, comprising a first positive lens, a second negative lens, a third negative lens, and a fourth positive lens arranged sequentially from the object plane along the optical axis to the image plane; the first and fourth positive lenses each have biconvex surfaces, and the second and third negative lenses each have biconcave surfaces; the image-side surface of the third negative lens is cemented to the object-side surface of the fourth positive lens; it has a large imaging angle and high resolution, which is beneficial for improving environmental and temperature adaptability and improving working performance, and can stably image in high and low temperature environments; it can shorten the projection distance, reduce the size of the device, and improve the imaging quality, making the image clear.

Description

Technical Field

[0001] This application relates to the field of optical technology, and more particularly to a projection optical system. Background Technology

[0002] Micro-LEDs (micro-light-emitting diodes) are self-emissive micro-display devices. Their core is a high-density, two-dimensional array of tiny light-emitting diodes. They offer numerous advantages, including low operating voltage, high luminous efficiency, fast response speed, wide operating temperature range, and strong adaptability to harsh environments. Furthermore, Micro-LEDs exhibit high brightness, each pixel can be individually driven, and the size of their light-emitting units can be controlled at the micrometer level, enabling high-resolution displays. Due to their superior characteristics in brightness, lifespan, resolution, and efficiency, they have become a focus of research and are considered the cornerstone of next-generation display technology. They are also the best choice for integrating light sources and image sources in ultra-micro projection display optical engines.

[0003] A monolithic Micro-LED micro-projection optical system consists of a monolithic Micro-LED display chip and a micro-projection lens. A light beam emitted from a Micro-LED light source is projected onto a near-eye display element via the micro-projection lens. Existing micro-projection lenses often suffer from limitations in imaging angle and resolution, as well as insufficient adaptability to environmental and temperature variations. Summary of the Invention

[0004] This application proposes a projection optical system that overcomes the shortcomings of existing micro-projection lenses, such as limited imaging angle and resolution, and insufficient adaptability to environment and temperature. It enables the micro-projection lens to have a larger imaging angle and higher resolution, which is beneficial to improving environmental and temperature adaptability, improving working performance, and providing clear imaging.

[0005] This application provides a projection optical system.

[0006] The embodiments of this application adopt the following technical solutions:

[0007] A projection optical system comprises a first positive lens, a second negative lens, a third negative lens, and a fourth positive lens arranged sequentially from the object plane along the optical axis to the image plane; the first positive lens and the fourth positive lens each have a biconvex surface, and the second negative lens and the third negative lens each have a biconcave surface; the image-side surface of the third negative lens is cemented to the object-side surface of the fourth positive lens.

[0008] Preferably, the materials of the first positive lens, the second negative lens, the third negative lens, and the fourth positive lens are, in order: H-LAF3, H-ZF6, H-QK3L, and H-ZBAF21.

[0009] Preferably, the image-side surface of the third negative lens is bonded to the object-side surface of the fourth positive lens.

[0010] 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.

[0011] Preferably, the effective focal length of the projection optical system is 4.141 mm, and the total optical length is 4.563 mm.

[0012] Preferably, the first positive lens has an object-side radius of curvature of 1.351 mm and an image-side radius of curvature of -49.000 mm; the second negative lens has an object-side radius of curvature of -4.240 mm and an image-side radius of curvature of 1.340 mm; the third negative lens has an object-side radius of curvature of -142.290 mm and an image-side radius of curvature of 4.109 mm; and the fourth positive lens has an object-side radius of curvature of 4.109 mm and an image-side radius of curvature of -2.610 mm.

[0013] 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.

[0014] Preferably, the distances between the image-side surface of the first positive lens and the object-side surface of the second negative lens, the distances between the image-side surface of the second negative lens and the object-side surface of the third negative lens, and the distances between the image-side surface of the third negative lens and the object-side surface of the fourth positive lens are 0.126 mm, 0.345 mm, and 0.000 mm, respectively.

[0015] Preferably, an aperture stop is provided between the second negative lens and the third negative lens.

[0016] Preferably, the distance between the image side of the second negative lens and the aperture stop, and the distance between the aperture stop and the object side of the third negative lens are 0.100 mm and 0.245 mm, respectively.

[0017] The above-described technical solutions adopted in the embodiments of this application can achieve the following beneficial effects:

[0018] The projection optical system of this application can overcome the shortcomings of existing micro-projection lenses, such as limited imaging angle and resolution, and insufficient adaptability to environment and temperature. It enables the system to have a larger imaging angle and higher resolution, which is beneficial to improving environmental and temperature adaptability and working performance. It can achieve stable imaging in high and low temperature environments. It can also shorten the projection distance, reduce the size of the device, and improve the imaging quality, resulting in clearer images. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0020] Figure 1 This is a schematic diagram of the projection optical system of this application;

[0021] Figure 2 This is a point diagram of the first field of view of the projection optical system of this application;

[0022] Figure 3 This is a diagram showing the second field of view of the projection optical system of this application;

[0023] Figure 4 A point diagram of the third field of view of the projection optical system of this application;

[0024] Figure 5 This is a point diagram of the fourth field of view of the projection optical system of this application;

[0025] Figure 6 A point diagram of the fifth field of view of the projection optical system of this application;

[0026] Figure 7 A point diagram of the sixth field of view of the projection optical system of this application;

[0027] Figure 8 This is a field curve bar diagram of the projection optical system of this application;

[0028] Figure 9 This is a distortion line diagram of the projection optical system of this application;

[0029] In the figure, the following labels are used: 1 is the first positive lens, 2 is the second negative lens, 3 is the third negative lens, 5 is the aperture stop, 6 is the image plane, and 7 is the ray. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] The technical solutions provided by the various embodiments of this application are described in detail below with reference to the accompanying drawings.

[0032] Example

[0033] 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 arranged sequentially along the optical axis from the object side to the image side. The first positive lens 1 is a positive focal lens with a convex object side and a convex image side; the second negative lens 2 is a negative focal lens with a concave object side and a concave image side; the third negative lens 3 is a negative focal lens with a concave object side and a concave image side; the fourth positive lens 4 is a positive focal lens with a convex object side and a convex image side; the image side of the third negative lens 3 is cemented to the object side of the fourth positive lens 4.

[0034] In this context, the object-side surface refers to the side facing the object plane, and the image-side surface refers to the side facing the image plane. The first positive lens 1 is a lens with positive optical power, and both its object-side and image-side surfaces are convex. The second negative lens 2 is a lens with negative optical power, and both its object-side and image-side surfaces are concave. The third negative lens 3 is a lens with negative optical power, and both its object-side and image-side surfaces are concave. The fourth positive lens 4 is a lens with positive optical power, and both its object-side and image-side surfaces are convex. The image-side surface of the third negative lens 3 and the object-side surface of the fourth positive lens 4 are cemented together to form a combined lens.

[0035] The projection optical system of this embodiment can shorten the projection distance and reduce the size of the device; it has a large imaging angle and high resolution, and can improve the imaging quality, making the image clear; it is conducive to improving environmental and temperature adaptability and improving working performance, and is conducive to stable imaging in high and low temperature environments.

[0036] Specifically, each lens body can use glass lenses, which helps to ensure strong adaptability to environment and temperature, and to ensure stable operation in high and low temperature environments, resulting in superior working performance and clearer imaging.

[0037] In some embodiments, the first positive lens 1 is made of H-LAF3, the second negative lens 2 is made of H-ZF6, the third negative lens 3 is made of H-QK3L, and the fourth positive lens 4 is made of H-ZBAF21.

[0038] In some embodiments, the effective focal length (EFFL) of the projection optical system is 4.141 mm, the entrance pupil diameter (ENPD) is 0.700 mm, and the total optical length (TOTR) is 4.563 mm.

[0039] The effective focal length refers to the distance from the optical rear principal point to the focal point of the projection optical system, which is the distance required for the projection optical system to focus parallel light rays 7 into a single point.

[0040] The total optical length refers to the distance between the object side surface of the first positive lens 1 of the projection optical system and the intersection of the optical axis and the image plane 6.

[0041] The entrance pupil diameter refers to the largest incident beam diameter of a ray 7 parallel to the optical axis of the projection optical system that can enter from the front of the projection optical system and pass through it.

[0042] In some embodiments, the object-side radius of curvature of the first positive lens 1 is 1.351 mm, and the image-side radius of curvature of the first positive lens 1 is -49.000 mm; the object-side radius of curvature of the second negative lens 2 is -4.240 mm, and the image-side radius of curvature of the second negative lens 2 is 1.340 mm; the object-side radius of curvature of the third negative lens 3 is -142.290 mm, and the image-side radius of curvature of the third negative lens 3 is 4.109 mm; the object-side radius of curvature of the fourth positive lens 4 is 4.109 mm, and the image-side radius of curvature of the fourth positive lens 4 is -2.610 mm.

[0043] In some embodiments, an aperture stop 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 stop is 0.100 mm; the distance along the optical axis from the aperture stop 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; and 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.

[0044] 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.

[0045] Table 1. (Regarding...) Figures 2 to 7 The points are illustrated below:

[0046]

[0047] Figures 2 to 7 In the diagram, the horizontal axis represents the field of view. For example, the image height radius of the first field of view is 0.000 mm, meaning 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 diameter of the Airy disk.

[0048] like Figure 8 As shown, in this embodiment of the projection optical system, field curvature has a relatively small impact on the optical system.

[0049] Figure 8 In the diagram, the legend corresponds to a wavelength of 0.625 μm;

[0050] The horizontal axis represents field curvature, in mm; the vertical axis represents the field of view, in °; the maximum field of view is 21.683°.

[0051] Sagittal field curvature: 0.0394 mm, Meridional field curvature: 0.0074 mm.

[0052] like Figure 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.

[0053] Figure 9 In the diagram, the legend corresponds to a wavelength of 0.625 μm.

[0054] The horizontal axis represents distortion, in %; the vertical axis represents the field of view, in °.

[0055] Maximum field of view: 21.683°; Maximum distortion: 0.7631%.

[0056] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0057] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated 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” as used herein includes all or any units and all combinations of one or more associated listed items.

[0058] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical, terminological, and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0059] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A projection optical system, characterized in that, It consists of a first positive lens (1), a second negative lens (2), a third negative lens (3) and a fourth positive lens (4) arranged sequentially from the object plane along the optical axis to the image plane (6); The first positive lens (1) and the fourth positive lens (4) each have a biconvex surface, and the second negative lens (2) and the third negative lens (3) each have a biconcave surface; the image side of the third negative lens (3) is cemented to the object side of the fourth positive lens (4); The object-side radius of curvature of the first positive lens (1) is 1.351 mm, and the image-side radius of curvature is -49.000 mm. The object-side radius of curvature of the second negative lens (2) is -4.240 mm, and the image-side radius of curvature is 1.340 mm. The object-side radius of curvature of the third negative lens (3) is -142.290 mm, and the image-side radius of curvature is 4.109 mm. The object-side radius of curvature of the fourth positive lens (4) is 4.109 mm, and the image-side radius of curvature is -2.610 mm. 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.

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 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.

4. The projection optical system according to any one of claims 1-3, 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.

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

6. The projection optical system according to claim 5, characterized in that, An aperture stop (5) is provided between the second negative lens (2) and the third negative lens (3).

7. The projection optical system according to claim 6, characterized in that, The distance between the image side of the second negative lens (2) and the aperture (5) and the distance between the aperture (5) and the object side of the third negative lens (3) are 0.100 mm and 0.245 mm, respectively.

Images