Large-image-plane long-focus projection lens
By employing a multi-layer anti-reflective coating design on the lens surface of the projection lens and optimizing the refractive index and Abbe number for different lenses, the problems of reflection loss and wear resistance are solved, thereby improving image quality and lens life.
Patent Information
- Application Number
- CN202520312884.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-25
- Publication Date
- 2026-02-27
- Estimated Expiration
- 2035-02-25
AI Technical Summary
Existing projection lenses have problems with reflection loss, dust, and mechanical friction, which affect image quality and lifespan.
The design employs a multi-layer anti-reflective coating, including first and second anti-reflective coatings, optimized for the refractive index and Abbe number of different lenses, and alternately uses high-refractive-index and low-refractive-index materials on the lens surface to reduce reflection loss and improve wear resistance.
It significantly reduces light reflection loss on the lens surface, improves the system's light transmittance and image quality, and extends the lens's lifespan.
Smart Images
Figure CN223955945U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field technology of lens especially is a long focus projection lens of big image surface. BACKGROUND
[0002] The long focus projection lens of big image surface is an optical lens supporting large screen and high resolution projection, which has a long focal length and a large image surface size. It is widely used in home theater, commercial demonstration, education projection and other scenes. In design, various aberrations need to be corrected, optical performance needs to be optimized, and mechanical structure stability needs to be ensured. In recent years, the projection display device technology field has made great progress. The projection device can project a large-size image picture several times larger than the device surface area with a small device. Especially in the short focus projection technology of projection display technology, it has the advantage of projecting a large picture at a short distance, and is loved by the majority of users.
[0003] In the optical projection system, the performance of the projection lens directly determines the sharpness, brightness and color restoration ability of the image. With the rapid development of projection technology, especially in the application of large image surface and long focus projection lens, users have higher and higher requirements for the quality of the projection picture. However, the existing projection lens still faces some technical problems in the design and manufacturing process, the most important of which is the reflection loss; in the optical system, light will be reflected on the lens surface, especially in the lens of high refractive index material, the reflection loss is more significant; the reflected light not only reduces the transmittance of the system, but also forms stray light, ghost and glare on the imaging surface, which seriously affects the contrast and sharpness of the image
[0004] Although the traditional single-layer anti-reflection coating can reduce the reflection loss to some extent, its effect is limited, especially in the case of wide wavelength range (such as visible light band) and large angle of incidence, the reflection loss is still high; secondly, the lens surface is easily affected by dust, fingerprints and mechanical friction during use, resulting in surface wear.
[0005] Therefore, it is necessary to study a new technical scheme to solve the above problems. UTILITY MODEL CONTENT
[0006] Therefore, the utility model discloses in view of the existing technology exists the lack, and its main purpose is to provide a big image plane long focus projection lens, through the design of first anti -reflection coating and second anti -reflection coating, so, through the arrangement multilayer anti -reflection coating of first lens, second lens, third lens, fourth lens entering surface and exit surface, adopt the design of alternative superposition front anti -reflection coating and rear anti -reflection coating, optimize for the refractive index and abbe number of different lenses, significantly reduce the reflection loss of light on the lens surface, improve the light transmittance and imaging quality of system, and the material of first front anti -reflection coating of entering surface still has higher hardness and wear resistance, can effectively resist the influence of dust, fingerprint and mechanical friction, prolong the service life of lens.
[0007] In order to realize the above-mentioned purpose, the utility model adopts the following technical scheme:
[0008] A big image plane long focus projection lens, including first lens, second lens, third lens, fourth lens and diaphragm, the front end of first lens, second lens, third lens, fourth lens is the entering surface, the rear end of first lens, second lens, third lens, fourth lens is the exit surface,
[0009] The entering surface of first lens is convex, and the exit surface of first lens is concave, the entering surface of second lens is concave, and the exit surface of second lens is concave, the entering surface of third lens is concave, and the exit surface of third lens is convex, the entering surface of fourth lens is concave, and the exit surface of fourth lens is convex, and the diaphragm is arranged at the rear end concave surface of second lens,
[0010] Wherein, the entering surface of first lens, second lens, third lens and fourth lens is provided with first anti -reflection coating, and the exit surface of first lens, second lens, third lens and fourth lens is provided with second anti -reflection coating,
[0011] The first anti -reflection coating includes first front anti -reflection coating and first rear anti -reflection coating, and the first rear anti -reflection coating is covered on the respective entering surface, and the first front anti -reflection coating is covered on the outer surface of first rear anti -reflection coating,
[0012] The second anti -reflection coating includes second front anti -reflection coating and second rear anti -reflection coating, and the second rear anti -reflection coating is covered on the respective exit surface, and the second front anti -reflection coating is covered on the outer surface of second rear anti -reflection coating.
[0013] As a preferred scheme, the first lens and third lens are positive lenses, and the second lens and fourth lens are negative lenses.
[0014] As a preferred solution, the first back anti-reflection coating and the second anti-reflection coating of the first lens are made of the same or different materials.
[0015] As a preferred solution, the first back anti-reflection coating of the first lens is made of titanium oxide or tantalum pentoxide; the first front anti-reflection coating of the first lens is made of magnesium fluoride or silicon dioxide; the second back anti-reflection coating of the first lens is made of titanium oxide or tantalum pentoxide; and the second front anti-reflection coating of the first lens is made of magnesium fluoride or silicon dioxide. High refractive index materials and low refractive index materials are alternately used to reduce reflection loss.
[0016] As a preferred solution, the first back anti-reflection coating and the second anti-reflection coating of the second lens are made of the same or different materials.
[0017] As a preferred solution, the first back anti-reflection coating of the second lens is made of tantalum pentoxide or silicon nitride; the first front anti-reflection coating of the second lens is made of magnesium fluoride or silicon dioxide; the second back anti-reflection coating of the second lens is made of tantalum pentoxide or silicon nitride; and the second front anti-reflection coating of the second lens is made of magnesium fluoride or silicon dioxide. High refractive index materials and low refractive index materials are alternately used to reduce reflection loss.
[0018] As a preferred solution, the first back anti-reflection coating and the third anti-reflection coating of the third lens are made of the same or different materials.
[0019] As a preferred solution, the first back anti-reflection coating of the third lens is made of titanium oxide or tantalum pentoxide; the first front anti-reflection coating of the third lens is made of magnesium fluoride or silicon dioxide; the second back anti-reflection coating of the third lens is made of titanium oxide or tantalum pentoxide; and the second front anti-reflection coating of the third lens is made of magnesium fluoride or silicon dioxide. High refractive index materials and low refractive index materials are alternately used to reduce reflection loss.
[0020] As a preferred solution, the first back anti-reflection coating and the second anti-reflection coating of the fourth lens are made of the same or different materials.
[0021] As a preferred solution, the first back anti-reflection coating of the fourth lens is made of titanium oxide or tantalum pentoxide; the first front anti-reflection coating of the fourth lens is made of aluminum oxide; the second back anti-reflection coating of the fourth lens is made of titanium oxide or tantalum pentoxide; and the second front anti-reflection coating of the fourth lens is made of aluminum oxide. Medium refractive index materials and low refractive index materials are alternately used to reduce reflection loss.
[0022] The utility model discloses an obvious advantage and beneficial effect compared with prior art, specifically speaking, from above technical scheme can know, it mainly is through the design of first anti -reflective coating and second anti -reflective coating, first anti -reflective coating includes first front anti -reflective coating and first rear anti -reflective coating, first rear anti -reflective coating covers and sets on respective entering surface, and first front anti -reflective coating covers and sets on the outer surface of first rear anti -reflective coating, second anti -reflective coating includes second front anti -reflective coating and second rear anti -reflective coating, second rear anti -reflective coating covers and sets on respective exit surface, and second front anti -reflective coating covers and sets on the outer surface of second rear anti -reflective coating, in this way, through arranging multilayer anti -reflective coating on the entering surface and exit surface of first lens, second lens, third lens, fourth lens, adopting the design of alternately superimposed front anti -reflective coating and rear anti -reflective coating, optimizing for the refractive index and abbe number of different lenses, significantly reducing the reflection loss of light on the lens surface, improve the light transmittance and imaging quality of system,
[0023] And the material of first front anti -reflective coating of entering surface also has higher hardness and wear resistance, can effectively resist the influence of dust, fingerprint and mechanical friction, prolongs the service life of lens.
[0024] In order to more clearly set forth the structural features and efficacy of the utility model, below, combining with specific embodiment and detailed description to the utility model are carried out. BRIEF DESCRIPTION OF DRAWINGS
[0025] Figure 1 It is the structure diagram of embodiment of the utility model;
[0026] Figure 2 It is the sectional view of first lens of embodiment of the utility model;
[0027] Figure 3 It is Figure 2 The local enlarged view of A in the figure;
[0028] Figure 4 It is the schematic diagram of axial chromatic aberration of embodiment of the utility model;
[0029] Figure 5 It is the schematic diagram of distortion in the preferred embodiment of the utility model;
[0030] Figure 6 It is the schematic diagram of relative luminance in the preferred embodiment of the utility model.
[0031] Brief description of drawings:
[0032] 1, first lens 2, second lens
[0033] 3, third lens 4, fourth lens
[0034] 5, aperture 11, entrance face
[0035] 12, exit face
[0036] 6, first anti-reflection coating 61, first front anti-reflection coating
[0037] 62, first back anti-reflection coating
[0038] 7, second anti-reflection coating 71, second front anti-reflection coating
[0039] 72, second back anti-reflection coating. DETAILED DESCRIPTION
[0040] Please refer to Figures 1 to 6 Fig. 1 shows the specific structure of the embodiment of the present application.
[0041] In the description of the present application, it should be noted that for the orientation words, if the orientation and position relationship indicated by the terms "up", "down", "front", "back", "left", "right" and the like is based on the orientation or position relationship shown in the drawings or normal wearing and using, it is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific protection scope of the present application.
[0042] A large image surface long-focus projection lens, comprising a first lens, a second lens, a third lens, a fourth lens and an aperture.
[0043] The front end face of the first lens, the second lens, the third lens and the fourth lens is an entrance face; the rear end face of the first lens, the second lens, the third lens and the fourth lens is an exit face; preferably, the first lens and the third lens are positive lenses; the second lens and the fourth lens are negative lenses.
[0044] The specific parameters of the large image surface long-focus projection lens are as follows:
[0045] focal length (EFL): 150mm; total length (TOTR): 156.6mm; aperture (F number): 2.8; image surface size: 56mm; distortion after projection imaging is less than 2%, and the maximum viewing angle of relative luminance is greater than 0.7.
[0046] Among them, the entrance face of the first lens, the second lens, the third lens and the fourth lens is provided with a first anti-reflection coating, and the exit face of the first lens, the second lens, the third lens and the fourth lens is provided with a second anti-reflection coating;
[0047] The first anti-reflection coating includes a first front anti-reflection coating and a first rear anti-reflection coating, the first rear anti-reflection coating is arranged on the respective entrance surface, and the first front anti-reflection coating is arranged on the outer surface of the first rear anti-reflection coating.
[0048] The second anti-reflection coating includes a second front anti-reflection coating and a second rear anti-reflection coating, the second rear anti-reflection coating is arranged on the respective exit surface, and the second front anti-reflection coating is arranged on the outer surface of the second rear anti-reflection coating.
[0049] The entrance surface of the first lens is a convex surface, and the exit surface of the first lens is a concave surface.
[0050] The entrance surface of the second lens is a concave surface, and the exit surface of the second lens is a concave surface.
[0051] The entrance surface of the third lens is a concave surface, and the exit surface of the third lens is a convex surface.
[0052] The entrance surface of the fourth lens is a concave surface, and the exit surface of the fourth lens is a convex surface.
[0053] The diaphragm is arranged at the rear end concave surface of the second lens, and the thickness of the diaphragm is 31.8 mm.
[0054] Preferably, the first rear anti-reflection coating of the first lens and the second anti-reflection coating are made of the same or different materials. The first rear anti-reflection coating of the first lens is made of titanium oxide or tantalum pentoxide, the first front anti-reflection coating of the first lens is made of magnesium fluoride or silicon dioxide, the second rear anti-reflection coating of the first lens is made of titanium oxide or tantalum pentoxide, and the second front anti-reflection coating of the first lens is made of magnesium fluoride or silicon dioxide. High and low refractive index materials are used alternately to reduce reflection loss. Since light is reflected when entering and leaving the lens, coating is needed on the entrance surface and the exit surface to reduce reflection loss; low refractive index film is used as the outermost layer to reduce reflection loss and improve wear resistance.
[0055] The curvature radius of the entrance surface of the first lens is 69.738 mm, and the thickness is 9.45 mm; the refractive index of the first lens is 1.74693, and the Abbe number is 50.95; the curvature radius of the exit surface of the first lens is 504.53 mm, and the thickness is 8.96 mm.
[0056] The refractive index is high, which belongs to medium-high refractive index material, and can adapt to various materials such as:
[0057] Low refractive index material: magnesium fluoride (MgF2, refractive index ~ 1.38), silicon dioxide (SiO2, refractive index 1.46);
[0058] Low refractive index material: Magnesium fluoride (MgF2, refractive index 1.38), silicon dioxide (SiO2, refractive index 1.46); high refractive index material: titanium dioxide (TiO2, refractive index 2.2-2.4), tantalum pentoxide (Ta2O5, refractive index 2.1-2.2).
[0059] Preferably, the first back anti-reflection coating and the third anti-reflection coating of the third lens are made of the same or different materials. The first back anti-reflection coating of the third lens is made of titanium oxide or tantalum pentoxide; the first front anti-reflection coating of the third lens is made of magnesium fluoride or silicon dioxide; the second back anti-reflection coating of the third lens is made of titanium oxide or tantalum pentoxide; the second front anti-reflection coating of the third lens is made of magnesium fluoride or silicon dioxide, and high refractive index materials and low refractive index materials are alternately used to reduce reflection loss.
[0060] The curvature radius of the entrance surface of the second lens is -135.938 mm, and the thickness is 8 mm; the refractive index of the second lens L2 is 1.80518, and the Abbe number is 25.46; the curvature radius of the exit surface of the second lens is -158.134 mm, and the thickness is 3.42 mm;
[0061] The refractive index is very high, which belongs to high refractive index material, and can adapt to various materials such as: high refractive index material: titanium dioxide (TiO2, refractive index 2.2-2.4), tantalum pentoxide (Ta2O5, refractive index 2.1-2.2), silicon nitride (Si3N4, refractive index 2.0-2.1); medium refractive index material: aluminum oxide (Al2O3, refractive index 1.63); low refractive index material: magnesium fluoride (MgF2, refractive index 1.38), silicon dioxide (SiO2, refractive index 1.46).
[0062] Preferably, the first back anti-reflection coating and the third anti-reflection coating of the third lens are made of the same or different materials. The first back anti-reflection coating of the third lens is made of titanium oxide or tantalum pentoxide; the first front anti-reflection coating of the third lens is made of magnesium fluoride or silicon dioxide; the second back anti-reflection coating of the third lens is made of titanium oxide or tantalum pentoxide; the second front anti-reflection coating of the third lens is made of magnesium fluoride or silicon dioxide, and high refractive index materials and low refractive index materials are alternately used to reduce reflection loss.
[0063] The curvature radius of the entrance surface of the third lens is 234.966 mm, and the thickness is 6.97 mm; the refractive index of the third lens L3 is 1.74693, and the Abbe number is 50.95; the curvature radius of the exit surface of the third lens is 111.8 mm, and the thickness is 30 mm; the refractive index is relatively high, which is the same as the material of the first lens.
[0064] Preferably, the first back anti-reflection coating and the third anti-reflection coating of the fourth lens are made of the same or different materials. The first back anti-reflection coating of the fourth lens is made of titanium oxide or tantalum pentoxide; the first front anti-reflection coating of the fourth lens is made of aluminum oxide; the second back anti-reflection coating of the fourth lens is made of titanium oxide or tantalum pentoxide; and the second front anti-reflection coating of the fourth lens is made of aluminum oxide. The high refractive index material and the low refractive index material are alternately used to reduce the reflection loss.
[0065] The curvature radius of the entrance surface of the fourth lens is -44.486 mm, and the thickness is 3 mm. The refractive index of the fourth lens L4 is 1.5168, and the Abbe number is 64.2. The curvature radius of the exit surface of the fourth lens is 147.71 mm, and the thickness is 55 mm. The refractive index is low, which belongs to a low refractive index material, and can adapt to various materials such as a low refractive index material: magnesium fluoride (MgF2, refractive index 1.38), silicon dioxide (SiO2, refractive index ~1.46); a medium refractive index material: aluminum oxide (Al2O3, refractive index 1.63). In this way, by arranging the multi-layer anti-reflection coating on the entrance surface and the exit surface of the first lens, the second lens, the third lens, and the fourth lens, and by using the design of alternately stacking the front anti-reflection coating and the back anti-reflection coating, the refractive index and the Abbe number of different lenses are optimized, the reflection loss of light on the lens surface is significantly reduced, and the light transmittance and the imaging quality of the system are improved. High refractive index materials (such as Ta2O5) and low refractive index materials (such as SiO2) are alternately used to minimize the reflection in a wide wavelength range (such as 400-700 nm). A large image surface long-focus projection lens includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a diaphragm 5.
[0066] The front end surface of the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4 is an entrance surface 11. The rear end surface of the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4 is an exit surface 12. Preferably, the first lens 1 and the third lens 3 are positive lenses, and the second lens 2 and the fourth lens 4 are negative lenses.
[0067] The specific parameters of the large image surface long-focus projection lens are as follows:
[0068] Focal length (EFL): 150 mm; total length (TOTR): 156.6 mm; aperture (F number): 2.8; image surface size: 56 mm; distortion after projection imaging is less than 2%, and the maximum viewing angle of relative luminance is greater than 0.7.
[0069] The first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 are provided with the first anti-reflection coating 6 on the entrance face 11, and are provided with the second anti-reflection coating 7 on the exit face 12.
[0070] The first anti-reflection coating 6 comprises a first front anti-reflection coating 61 and a first rear anti-reflection coating 62, the first rear anti-reflection coating 62 is arranged on the entrance face 11, and the first front anti-reflection coating 61 is arranged on the outer surface of the first rear anti-reflection coating 62.
[0071] The second anti-reflection coating 7 comprises a second front anti-reflection coating 71 and a second rear anti-reflection coating 72, the second rear anti-reflection coating 72 is arranged on the exit face 12, and the second front anti-reflection coating 71 is arranged on the outer surface of the second rear anti-reflection coating 72.
[0072] The entrance face 11 of the first lens 1 is a convex surface, and the exit face 12 of the first lens 1 is a concave surface.
[0073] The entrance face 11 of the second lens 2 is a concave surface, and the exit face 12 of the second lens 2 is a concave surface.
[0074] The entrance face 11 of the third lens 3 is a concave surface, and the exit face 12 of the third lens 3 is a convex surface.
[0075] The entrance face 11 of the fourth lens 4 is a concave surface, and the exit face 12 of the fourth lens 4 is a convex surface.
[0076] The diaphragm 5 is arranged on the rear end concave surface of the second lens 2, and the thickness of the diaphragm 5 is 31.8mm.
[0077] Preferably, the first rear anti-reflection coating 62 of the first lens 1 and the second anti-reflection coating 7 are made of the same or different materials. The first rear anti-reflection coating 62 of the first lens 1 is made of titanium oxide or tantalum pentoxide, the first front anti-reflection coating 61 of the first lens 1 is made of magnesium fluoride or silicon dioxide, the second rear anti-reflection coating 72 of the first lens 1 is made of titanium oxide or tantalum pentoxide, and the second front anti-reflection coating 71 of the first lens 1 is made of magnesium fluoride or silicon dioxide. High and low refractive index materials are alternately used to reduce reflection loss. Since light is reflected when entering and leaving the lens, coating is needed on the entrance face 11 and the exit face 12 to reduce reflection loss. Low refractive index film is used as the outermost layer to reduce reflection loss and improve wear resistance.
[0078] The curvature radius of the entrance face 11 of the first lens 1 is 69.738 mm, and the thickness is 9.45 mm; the refractive index of the first lens 1 is 1.74693, and the Abbe number is 50.95; the curvature radius of the exit face 12 of the first lens 1 is 504.53 mm, and the thickness is 8.96 mm;
[0079] The refractive index is high, which belongs to a medium-high refractive index material, and can adapt to various materials such as:
[0080] Low refractive index material: magnesium fluoride (MgF2, refractive index ~1.38), silicon dioxide (SiO2, refractive index 1.46);
[0081] Medium refractive index material: aluminum oxide (Al2O3, refractive index 1.63); high refractive index material: titanium dioxide (TiO2, refractive index 2.2-2.4), tantalum pentoxide (Ta2O5, refractive index 2.1-2.2).
[0082] Preferably, the materials of the first rear anti-reflection coating 62 and the second anti-reflection coating 7 of the second lens 2 are the same or different. The first rear anti-reflection coating 62 of the second lens 2 is made of tantalum pentoxide or silicon nitride; the first front anti-reflection coating 61 of the second lens 2 is made of magnesium fluoride or silicon dioxide; the second rear anti-reflection coating 72 of the second lens 2 is made of tantalum pentoxide or silicon nitride; the second front anti-reflection coating 71 of the second lens 2 is made of magnesium fluoride or silicon dioxide, and high refractive index material and low refractive index material are alternately used to reduce reflection loss.
[0083] The curvature radius of the entrance face 11 of the second lens 2 is -135.938 mm, and the thickness is 8 mm; the refractive index of the second lens 2 L2 is 1.80518, and the Abbe number is 25.46; the curvature radius of the exit face 12 of the second lens 2 is -158.134 mm, and the thickness is 3.42 mm;
[0084] The refractive index is very high, which belongs to a high refractive index material, and can adapt to various materials such as: high refractive index material: titanium dioxide (TiO2, refractive index 2.2-2.4), tantalum pentoxide (Ta2O5, refractive index 2.1-2.2), silicon nitride (Si3N4, refractive index 2.0-2.1); medium refractive index material: aluminum oxide (Al2O3, refractive index 1.63); low refractive index material: magnesium fluoride (MgF2, refractive index 1.38), silicon dioxide (SiO2, refractive index 1.46).
[0085] Preferably, the first back anti-reflection coating 62 and the third anti-reflection coating of the third lens 3 are made of the same or different materials. The first back anti-reflection coating 62 of the third lens 3 is made of titanium oxide or tantalum pentoxide; the first front anti-reflection coating 61 of the third lens 3 is made of magnesium fluoride or silicon dioxide; the second back anti-reflection coating 72 of the third lens 3 is made of titanium oxide or tantalum pentoxide; and the second front anti-reflection coating 71 of the third lens 3 is made of magnesium fluoride or silicon dioxide. High and low refractive index materials are alternately used to reduce reflection loss.
[0086] The curvature radius of the entrance face 11 of the third lens 3 is 234.966 mm, and the thickness is 6.97 mm; the refractive index of the third lens 3L3 is 1.74693, and the Abbe number is 50.95; the curvature radius of the exit face 12 of the third lens 3 is 111.8 mm, and the thickness is 30 mm; and the refractive index is higher, which is the same as the material of the first lens 1.
[0087] Preferably, the first back anti-reflection coating 62 and the second anti-reflection coating of the fourth lens 4 are made of the same or different materials. The first back anti-reflection coating 62 of the fourth lens 4 is made of titanium oxide or tantalum pentoxide;
[0088] The first front anti-reflection coating 61 of the fourth lens 4 is made of aluminum oxide; the second back anti-reflection coating 72 of the fourth lens 4 is made of titanium oxide or tantalum pentoxide; and the second front anti-reflection coating 71 of the fourth lens 4 is made of aluminum oxide. Medium and low refractive index materials are alternately used to reduce reflection loss.
[0089] The curvature radius of the entrance face 11 of the fourth lens is -44.486 mm, and the thickness is 3 mm; the refractive index of the fourth lens 4L4 is 1.5168, and the Abbe number is 64.2; the curvature radius of the exit face 12 of the fourth lens 4 is 147.71 mm, and the thickness is 55 mm; and the refractive index is lower, which belongs to low refractive index materials, which can adapt to various materials such as low refractive index materials: magnesium fluoride (MgF2, refractive index 1.38), silicon dioxide (SiO2, refractive index ~1.46); medium refractive index materials: aluminum oxide (Al2O3, refractive index 1.63). In this way, by arranging multiple anti-reflection coatings on the entrance face 11 and the exit face 12 of the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4, and using the design of alternately stacking front anti-reflection coatings and back anti-reflection coatings, the refractive index and Abbe number of different lenses are optimized, the reflection loss of light on the lens surface is significantly reduced, the light transmittance and imaging quality of the system are improved, and high refractive index materials (such as Ta2O5) and low refractive index materials (such as SiO2) are alternately used to minimize reflection in a wide wavelength range (such as 400-700 nm).
[0090] The utility model discloses a design emphasis lies in, it mainly is through the design of first anti -reflective coating and second anti -reflective coating, first anti -reflective coating includes and first back anti -reflective coating and first front anti -reflective coating, first back anti -reflective coating covers and sets up on respective entering surface, and first front anti -reflective coating covers and sets up on the outer surface of first back anti -reflective coating, second anti -reflective coating includes and second back anti -reflective coating and second front anti -reflective coating, second back anti -reflective coating covers and sets up on respective exit surface, and second front anti -reflective coating covers and sets up on the outer surface of second back anti -reflective coating, thus, through arranging multilayer anti -reflective coating on the entering surface and exit surface of first lens, second lens, third lens, fourth lens, adopts the design of alternately superimposed front anti -reflective coating and back anti -reflective coating, and the refractive index and abbe number of different lenses are optimized, and the reflection loss of light on the lens surface is reduced significantly, and the light transmittance and imaging quality of system are improved.
[0091] And the material of first front anti -reflective coating of entering surface also has higher hardness and wear resistance, can effectively resist the influence of dust, fingerprint and mechanical friction, prolongs the service life of lens.
[0092] The above, only is the preferred embodiment of the utility model, and does not restrict the technical range of the utility model in any respect, so any slight modification, equivalent change and modification of the above embodiment according to the technical essence of the utility model still belong to the range of the technical scheme of the utility model.
Claims
1. A large image surface long focus projection lens characterized by: The application relates to a lens, which comprises a first lens, a second lens, a third lens, a fourth lens and a diaphragm; the front end face of the first lens, the second lens, the third lens and the fourth lens is an entrance face; and the rear end face of the first lens, the second lens, the third lens and the fourth lens is an exit face. The entrance face of the first lens is a convex face, the exit face of the first lens is a concave face, the entrance face of the second lens is a concave face, the exit face of the second lens is a concave face, the entrance face of the third lens is a concave face, the exit face of the third lens is a convex face, the entrance face of the fourth lens is a concave face, and the exit face of the fourth lens is a convex face; and the diaphragm is arranged at the rear end concave face of the second lens. The entrance face of the first lens, the second lens, the third lens and the fourth lens is provided with a first anti-reflection coating, and the exit face of the first lens, the second lens, the third lens and the fourth lens is provided with a second anti-reflection coating. The first anti-reflection coating comprises a first front anti-reflection coating and a first rear anti-reflection coating, the first rear anti-reflection coating is arranged on the respective entrance face, and the first front anti-reflection coating is arranged on the outer surface of the first rear anti-reflection coating. The second anti-reflection coating comprises a second front anti-reflection coating and a second rear anti-reflection coating, the second rear anti-reflection coating is arranged on the respective exit face, and the second front anti-reflection coating is arranged on the outer surface of the second rear anti-reflection coating.
2. The large- image surface long focus projection lens according to claim 1, characterized in that: The first lens and the third lens are positive lenses, and the second lens and the fourth lens are negative lenses.
3. The large- image surface long focus projection lens according to claim 1, characterized in that: The material of the first rear anti-reflection coating of the first lens and the second anti-reflection coating is the same or different.
4. The large-imaging-area long-focus projection lens according to claim 3, characterized in that: The first rear anti-reflection coating of the first lens is made of titanium oxide or diptassium tantalate, the first front anti-reflection coating of the first lens is made of magnesium fluoride or silicon dioxide, the second rear anti-reflection coating of the first lens is made of titanium oxide or diptassium tantalate, and the second front anti-reflection coating of the first lens is made of magnesium fluoride or silicon dioxide.
5. The large- image surface long focus projection lens according to claim 1, wherein: The material of the first rear anti-reflection coating of the second lens and the second anti-reflection coating is the same or different.
6. The large- image surface long focus projection lens according to claim 5, characterized in that: The first rear anti-reflection coating of the second lens is made of diptassium tantalate or silicon nitride, the first front anti-reflection coating of the second lens is made of magnesium fluoride or silicon dioxide, the second rear anti-reflection coating of the second lens is made of diptassium tantalate or silicon nitride, and the second front anti-reflection coating of the second lens is made of magnesium fluoride or silicon dioxide.
7. The large- image surface long focus projection lens according to claim 1, wherein: The material of the first rear anti-reflection coating of the third lens and the third anti-reflection coating is the same or different.
8. The large- image surface long focus projection lens according to claim 7, characterized in that: The first rear anti-reflection coating of the third lens is made of titanium oxide or diptassium tantalate, the first front anti-reflection coating of the third lens is made of magnesium fluoride or silicon dioxide, the second rear anti-reflection coating of the third lens is made of titanium oxide or diptassium tantalate, and the second front anti-reflection coating of the third lens is made of magnesium fluoride or silicon dioxide.
9. The large- image surface long focus projection lens according to claim 1, wherein: The material of the first rear anti-reflection coating of the fourth lens and the second anti-reflection coating is the same or different.
10. The large- image surface long focus projection lens according to claim 9, characterized in that: The first back anti-reflection coating of the fourth lens is made of titanium oxide or tantalum pentoxide; the first front anti-reflection coating of the fourth lens is made of aluminum oxide; the second back anti-reflection coating of the fourth lens is made of titanium oxide or tantalum pentoxide; and the second front anti-reflection coating of the fourth lens is made of aluminum oxide.