A glass-plastic hybrid lens

Abstract

The application discloses a glass-plastic hybrid lens, which comprises a first lens, a second lens, a diaphragm, a third lens, a fourth lens, a protective glass sheet and an imaging surface in sequence from an object side to an image side along an optical axis, wherein the first lens is a double-concave lens, the second lens is a double-convex lens, the third lens is a double-convex lens, and the fourth lens is a double-concave lens; the optical interval between the first lens and the second lens is 6.88 mm, the optical interval between the second lens and the third lens is 2.58 mm, the optical interval between the third lens and the fourth lens is 0.13 mm, and the optical interval between the fourth lens and the imaging surface is 5.68 mm; the focal length f of the lens is 3.70 mm, the focal length f1 of the first lens is -5.65 mm, the focal length f2 of the second lens is 9.20 mm, the focal length f3 of the third lens is 3.92 mm, and the focal length f4 of the fourth lens is -5.23 mm; and the technical scheme of the application improves the light throughput and temperature bearing capacity of the fixed-focus lens, so that the fixed-focus lens can shoot clear images in a relatively dark environment and in a high-low temperature environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical lens, in particular to a glass-plastic hybrid lens. BACKGROUND

[0002] With the improvement of people's safety awareness, the use of monitoring lens in people's life is also more widely, and the monitoring lens can be divided into two categories: zoom lens and fixed focus lens. The fixed focus lens refers to the lens with only one fixed focal length and no zoom function. The zoom lens refers to the lens that can change the focal length within a certain range, and the zoom lens can change the shooting range by changing the focal length without changing the shooting distance.

[0003] Compared with the zoom lens, the fixed focus lens has a larger aperture and more light quantity, so the image clarity of the fixed focus lens is higher than that of the zoom lens. On the other hand, the fixed focus lens has a fixed focal length, so the focusing speed is fast, and the image of the moving object is more clear and stable. Therefore, the fixed focus lens is often used in places where high-quality images are required.

[0004] However, the existing fixed focus lens is prone to defocus in high-temperature and low-temperature environments, which affects the imaging quality. At the same time, the light quantity of the lens needs to be increased to improve the image clarity of the monitoring lens in dark environments. SUMMARY

[0005] In order to improve the light quantity and temperature resistance of the fixed focus lens, and make the fixed focus lens shoot clear images in dark environments and high and low temperature environments, the present application provides a glass-plastic hybrid lens.

[0006] The present application provides a glass-plastic hybrid lens, which adopts the following technical scheme: the glass-plastic hybrid lens comprises, in order from the object side to the image side along the optical axis: a first lens, a second lens, a diaphragm ST, a third lens, a fourth lens, a protective glass sheet, and an imaging surface; the first lens is a double-concave lens, the second lens is a double-convex lens, the third lens is a double-convex lens, and the fourth lens is a double-concave lens.

[0007] In a specific embodiment, the optical separation between the first lens and the second lens is 6.88mm; the optical separation between the second lens and the third lens is 2.58mm; the optical separation between the third lens and the fourth lens is 0.13mm; and the optical separation between the fourth lens and the imaging surface is 5.68mm.

[0008] By adopting the technical scheme, a large light quantity and high definition of the lens can be realized by only arranging and spacing the light paths of four lenses, the number of lenses in the lens is reduced, and the lens structure is optimized.

[0009] In one specific implementation, the focal length f of the glass-plastic hybrid lens is 3.70 mm; the focal length f1 of the first lens is -5.65 mm, the focal length f2 of the second lens is 9.20 mm, the focal length f3 of the third lens is 3.92 mm, and the focal length f4 of the fourth lens is -5.23 mm.

[0010] In one specific implementation, the second lens is a spherical lens made of glass, and the first lens, the third lens, and the fourth lens are aspherical lenses made of plastic.

[0011] By adopting the technical scheme, the spherical lens and the aspherical lens are combined, and the parameters of each lens are designed, which on the one hand increases the focal length f of the glass-plastic hybrid lens, improves the imaging clarity of the lens when shooting short-distance objects, and at the same time improves the light quantity of the lens, so that the lens can shoot clear images without infrared fill light in a low-intensity light environment; on the other hand, the problem of focal point drift and view distortion caused by the large expansion coefficient of the plastic aspherical lens in high and low temperature environments is overcome, so that the lens does not defocus in a temperature range of -30℃ to 80℃, the imaging quality is improved, the illumination of the lens is more uniform, the image brightness is high, the image color restoration degree is high, and high-pixel image output of the lens is realized.

[0012] In one specific implementation, the object side R1 of the first lens and the image side R2 of the first lens are both concave inward, the first lens is thin in the middle and thick at the edges, the optical power of the first lens is negative, and the bending radius of the object side R1 is smaller than that of the image side R2.

[0013] By adopting the technical scheme, the optical power of the first lens is negative, and the first lens has a diverging effect on the incoming light.

[0014] In one specific implementation, the object side R3 of the second lens and the image side R4 of the second lens are both convex outward, the second lens is thick in the middle and thin at the edges, the optical power of the second lens is positive, and the object side R3 and the image side R4 are symmetrical.

[0015] By adopting the technical scheme, the optical power of the second lens is positive, and the second lens has a converging effect on the incoming light.

[0016] In one specific implementation, the object side R6 of the third lens and the image side R7 of the third lens are both outward convex, the third lens is thick in the middle and thin at the edge, and the third lens has positive power.

[0017] By using the above technical solution, the third lens has positive power, and the third lens converges the incoming light.

[0018] In one specific implementation, the object side R8 of the fourth lens and the image side R9 of the fourth lens are both inward concave, the fourth lens is thin in the middle and thick at the edge, the fourth lens 4 has negative power, and the bending curvature of the object side R8 is greater than that of the image side R9.

[0019] By using the above technical solution, the fourth lens has negative power, and the fourth lens diverges the incoming light.

[0020] In summary, the technical solution of the present application has at least the following beneficial technical effects:

[0021] 1. By arranging the optical path, position interval and parameters of the first lens to the fourth lens, on the one hand, the focal length of the glass-plastic hybrid lens is increased, the imaging clarity of the lens when shooting short-distance objects is improved, and the light flux of the lens is increased, so that the lens can still shoot clear images in a low-light environment; on the other hand, the problem of focal point drift and view distortion caused by the large expansion coefficient of the plastic aspherical lens in high and low temperature environments is overcome, so that the lens does not become out of focus in a temperature range of -30°C to 80°C, and the imaging quality is improved.

[0022] 2. By arranging the optical path, position interval and parameters of each lens, the illumination of the lens is more uniform, the image brightness is high, the image color restoration degree is high, and high-pixel image output of the lens is realized. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the overall structure schematic diagram of the glass-plastic hybrid lens in the embodiment of the present application.

[0024] Figure 2 is the relative luminance schematic diagram of the glass-plastic hybrid lens in the embodiment of the present application.

[0025] Figure 3 is the field curvature and distortion schematic diagram of the glass-plastic hybrid lens in the embodiment of the present application.

[0026] Figure 4 is the MTF schematic diagram of the glass-plastic hybrid lens in the embodiment of the present application at -30°C.

[0027] Figure 5Fig. 2 is a schematic diagram of MTF of the glass-plastic hybrid lens in the embodiment of the present application at 80°C.

[0028] Figure 6 Fig. 3 is a schematic diagram of visible light MTF of the glass-plastic hybrid lens in the embodiment of the present application.

[0029] Legend of reference signs:

[0030] 1, first lens; 2, second lens; 3, third lens; 4, fourth lens; 5, protective glass sheet; 6, imaging surface. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present application more clear, the embodiment of the present application will be further described in detail below with reference to the drawings.

[0032] A zoom lens is a lens that can change focal length within a certain range, thereby obtaining different field angles, different image sizes and different scene ranges. The zoom lens is often applied in a camera. When people take pictures using the zoom lens, the focal length of the lens can be changed by pushing or rotating the zoom ring of the lens. Moreover, the focal length can be changed steplessly within the zoom range, i.e. any focal length within the zoom range can be used for photography, which provides conditions for the diversification of photographic composition.

[0033] A fixed-focus lens, as the name implies, is a lens without zoom function and only with a fixed focal length. The design of the fixed-focus lens is much simpler than that of the zoom lens. The fixed-focus lens has the following advantages over the zoom lens: 1. fast focusing speed and stable imaging quality; 2. the fixed-focus lens generally has a larger aperture and larger light flux than the zoom lens covering the same focal length range, which is convenient for shooting in low-illumination environment; 3. the fixed-focus lens only needs to correct and optimize the imaging of one focal length range, which can reduce the imaging distortion, and therefore the fixed-focus lens is widely used in many occasions requiring high image quality.

[0034] The present application provides a glass-plastic hybrid lens with large light flux and capable of shooting clear images in both day and night. The glass-plastic hybrid lens is a fixed-focus lens and has high imaging quality.

[0035] As shown in Fig. 1, the glass-plastic hybrid lens comprises a first lens 1, a second lens 2, a third lens 3, a fourth lens 4 and a protective glass sheet 5. Figure 1As shown, the glass-plastic hybrid lens comprises, along the optical axis from the object side to the image side, a first lens 1, a second lens 2, a diaphragm ST, a third lens 3, a fourth lens 4, a protective glass sheet 5, and an imaging surface 6. For the convenience of understanding the technical solutions, the object side and the image side of each lens and the protective glass sheet, and the diaphragm are named as follows: the object side of the first lens 1 is R1, the image side of the first lens 1 is R2, the object side of the second lens 2 is R3, the image side of the second lens 2 is R4, the surface of the diaphragm ST is R5, the object side of the third lens 3 is R6, the image side of the third lens 3 is R7, the object side of the fourth lens 4 is R8, the image side of the fourth lens 4 is R9, the object side of the protective glass sheet 5 is R10, and the image side of the protective glass sheet 5 is R11.

[0036] In particular, the first lens 1 is a double-concave lens, the second lens 2 is a double-convex lens, the third lens 3 is a double-convex lens, the fourth lens 4 is a double-concave lens, the diaphragm ST is used to control the size of the light beam entering the third lens 3, thereby controlling the size of the imaging range, the protective glass sheet 5 is used to protect the optical path system composed of each lens, and the imaging surface 6 is used to image the light passing through each lens.

[0037] In one embodiment of the present application, the object side R1 and the image side R2 of the first lens 1 are both inwardly concave, the first lens 1 is thin in the middle and thick at the edges, the optical power of the first lens 1 is negative, and the first lens 1 has a diverging effect on light rays. The curvature of the object side R1 of the first lens 1 is smaller than the curvature of the image side R2 of the first lens 1, which will be further described below:

[0038] The arc length between the midpoint and the upper or lower end point of the object side R1 of the first lens 1 is L1, and the arc length between the midpoint and the upper or lower end point of the image side R2 of the first lens 1 is L2, where L2 is greater than L1, and the difference between L2 and L1 is greater than a threshold value, which indicates that the curvature of the object side R1 of the first lens 1 is smaller than the curvature of the image side R2 of the first lens 1.

[0039] In one embodiment of the present application, the object side R3 and the image side R4 of the second lens 2 are both outwardly convex, the second lens 2 is thick in the middle and thin at the edges, the optical power of the second lens 2 is positive, and the second lens 2 has a converging effect on light rays. The object side R3 and the image side R4 of the second lens 2 are symmetrical, which will be further described below:

[0040] The length of the arc between the midpoint and the upper or lower endpoint of the object-side surface R3 of the second lens 2 is L3, and the length of the arc between the midpoint and the upper or lower endpoint of the image-side surface R4 is L4. Here, L3 is equal to L4, and the object-side surface R3 and the image-side surface R4 can be completely overlapped when folded along the symmetry axis, indicating that the object-side surface R3 and the image-side surface R4 of the second lens 2 are symmetrical.

[0041] In one embodiment of the present application, the object-side surface R6 and image-side surface R7 of the third lens element 3 are both convex. The third lens element 3 is thicker in the middle and thinner at the edges. The third lens element 3 has positive optical power and has a converging effect on light. The following further explains the concept of "thicker in the middle and thinner at the edges":

[0042] The distance between the midpoint of the object-side surface R6 of the third lens 3 and the midpoint of the image-side surface R7 is d6. Take point a near the upper endpoint of object-side surface R6, point b near the lower endpoint of object-side surface R6, point a' near the upper endpoint of image-side surface R7, and point b' near the lower endpoint of image-side surface R7. The distance between a and a' is d7, and the distance between b and b' is d7'. Here, d6 is greater than d7 and d7', and the difference between d6 and d7 and the difference between d6 and d7' are both greater than a threshold value. This indicates that the third lens 3 is thick in the middle and thin at the edges.

[0043] In one embodiment of the present application, both the object-side surface R8 and the image-side surface R9 of the fourth lens element 4 are concave inward. The fourth lens element 4 is thin in the middle and thick at the edges. The optical power of the fourth lens element 4 is negative, which has a diverging effect on light. The curvature of the object-side surface R8 of the fourth lens element 4 is greater than the curvature of the image-side surface R9. The following further explains the "thickness of the fourth lens element 4 in the middle and thin at the edges" and the "curvature of the object-side surface R8 of the fourth lens element 4 is greater than the curvature of the image-side surface R9":

[0044] The distance between the midpoint of object-side surface R8 and the midpoint of image-side surface R9 of fourth lens element 4 is d8. Point c on object-side surface R8, near the upper endpoint, point d on object-side surface R8, near the lower endpoint, point c' on image-side surface R9, near the upper endpoint, and point d' on image-side surface R9, near the lower endpoint, are taken. The distance between c and c' is d9, and the distance between d and d' is d9'. If d8 is smaller than both d9 and d9', and the differences between d8 and d9 and between d8 and d9' are both greater than a threshold, this indicates that the lens is thin in the middle and thick at the edges.

[0045] The length of the arc between the midpoint and the upper or lower endpoint of the object-side surface R8 of the fourth lens element 4 is L8, and the length of the arc between the midpoint and the upper or lower endpoint of the image-side surface R9 is L9. Where L8 is greater than L9, and the difference between L8 and L9 is greater than a threshold value, it indicates that the curvature of the object-side surface R8 of the fourth lens element 4 is greater than the curvature of the image-side surface R9.

[0046] In one embodiment of the present application, the protective glass sheet 5 is a glass sheet with uniform thickness, and the object side R10 and the image side R11 are left-right symmetrical about the symmetry axis. The "protective glass sheet 5 with uniform thickness, and the object side R10 and the image side R11 are left-right symmetrical about the symmetry axis" are further described as follows:

[0047] The midpoint of the object side R10 of the protective glass sheet 5 and the midpoint of the image side R11 are at a distance d10. A point e is taken at the upper end point of the object side R10, a point f is taken at the lower end point of the object side R10, a point e' is taken at the upper end point of the image side R11, and a point f' is taken at the lower end point of the image side R11. The distance between e and e' is d11, and the distance between f and f' is d11'. Wherein, d10 is equal to d11 and d11', and the object side R10 and the image side R11 are folded along the symmetry axis and can completely coincide on the left and right, which indicates that the protective glass sheet 5 has uniform thickness, and the object side R10 and the image side R11 are left-right symmetrical about the symmetry axis.

[0048] Further, the optical interval between the first lens 1 and the second lens 2 is 6.88mm; the optical interval between the second lens 2 and the third lens 3 is 2.58mm; the optical interval between the third lens 3 and the fourth lens 4 is 0.13mm; and the optical interval between the fourth lens 4 and the imaging surface 6 is 5.68mm.

[0049] The first lens 1, the third lens 3, and the fourth lens 4 are aspherical lenses made of plastic material, and the second lens 2 is a spherical lens made of glass material. If a single spherical lens is used, the lens aberration and deformation will be increased, and obvious image blurring, distorted view, narrow field of view, and other adverse phenomena will occur. In the present lens, multiple aspherical lenses are used to correct the image and solve the problem of distorted view to some extent.

[0050] In the present application, the aspherical lenses, i.e., the first lens 1, the third lens 3, and the fourth lens 4, all satisfy the following formula:

[0051]

[0052] Wherein, z is the sag, c is the curvature, h is the vertical distance of any point on the lens surface to the optical axis, k is the conic quadratic curve coefficient, A4, A6, A8, A 10 , A 12 , and A 14 are high-order coefficients of the aspherical surface.

[0053] Embodiment one: The parameter design of each lens and the corresponding indicators achieved are as follows:

[0054] The parameters of the object side R1 and the image side R2 of the first lens 1, the object side R6 and the image side R7 of the third lens 3, and the object side R8 and the image side R9 of the fourth lens 4 are shown in Table 1:

[0055] Surface K A4 A6 A8 A10 A12 A14 R1 -2578.491 -1.55E-04 -1.13E-05 -4.87E-07 1.43E-07 1.81E-09 -1.53E-10 R2 -0.5852 2.19E-03 -3.71E-05 1.46E-05 -1.38E-06 -3.12E-07 5.97E-08 R6 0.3413942 1.29E-04 9.15E-05 -9.85E-05 2.34E-05 -2.94E-06 4.19E-10 R7 -0.2713547 1.20E-02 -8.16E-04 2.18E-04 -5.36E-04 5.88E-06 -2.01E-09 R8 -3.651027 1.16E-03 1.06E-02 -3.09E-04 2.16E-05 3.91E-07 2.27E-07 R9 -34.14335 1.06E-02 2.37E-04 -1.27E-04 5.51E-06 1.96E-06 -8.71E-08

[0056] Table 1

[0057] The parameters of the object side R1 and the image side R2 of the first lens 1, the object side R3 and the image side R4 of the second lens 2, the object side R5 of the diaphragm ST, the object side R6 and the image side R7 of the third lens 3, the object side R8 and the image side R9 of the fourth lens 4, and the object side R10 and the image side R11 of the protective glass sheet 5 are shown in Table 2:

[0058]

[0059]

[0060] Table 2

[0061] According to Table 2, the focal length f1 of the first lens 1 is -5.65 mm, the focal length f2 of the second lens 2 is 9.20 mm, the focal length f3 of the third lens 3 is 3.92 mm, and the focal length f4 of the fourth lens 4 is -5.23 mm.

[0062] Through the above parameter design, the glass-plastic hybrid lens in the application achieves the following indicators, as shown in Table 3:

[0063] Focal length 3.70mm Aperture F1.6 System total length 22.50mm Image surface specification 1 / 2.7" Resolution 5Mega Pixel Field angle of view 110°*92°*50° Relative luminance 59.64％ Distortion -38.44％ Operating temperature -30℃～+80℃

[0064] Table 3

[0065] In the above table, the focal length is a way of measuring the convergence or divergence of light in an optical system. When light parallel to the principal axis passes through multiple lenses in the lens, it converges to a point, which is called the focal point. The distance from the focal point to the center of the lens is called the focal length. The wider the field of view of the lens, the shorter the focal length. For the same imaging area, the shorter the focal length, the larger the angle of view, that is, the optical system with a short focal length has better light gathering ability than the optical system with a long focal length.

[0066] According to Table 3, the focal length of the glass-plastic hybrid lens in the application is 3.70 mm, and the imaging clarity is high when shooting short-distance objects.

[0067] Aperture: The calculation formula of the aperture is: F=f / D, F is the aperture value, f is the focal length of the lens, and D is the light aperture of the lens. In the case of the same focal length, the larger the light aperture, the smaller the aperture value, the more light the lens accepts, and the shallower the depth of field.

[0068] According to Table 3, the glass-plastic hybrid lens aperture of the present application is F1.6, and the light throughput of the lens is large, so that infrared light compensation is not needed in a low light intensity environment, and the lens can be used to shoot clear images in both day and night.

[0069] Total length of system: refers to the distance from the first lens in the lens to the image plane.

[0070] According to Table 3, the total length of the system of the glass-plastic hybrid lens of the present application is 22.50mm, and the length of the lens is relatively short, so that the volume of the lens can be smaller.

[0071] Image plane specification: the common specifications on the market mainly include 2 / 3 inch, 1 / 1.8 inch, 1 / 2.7 inch and 1 / 3.2 inch. The larger the specification size of the photosensitive element is, the larger the photosensitive area is, and the better the imaging effect is. However, with the increase of the specification size of the photosensitive element, the volume and weight of the photosensitive element are larger, and the cost is higher.

[0072] According to Table 3, the image plane specification of the glass-plastic hybrid lens of the present application is 1 / 2.7 inch, which is moderate, and the imaging effect is ensured while avoiding the volume and weight of the lens being too large.

[0073] Resolution: the resolution of an image determines the degree of detail of the image. The higher the resolution of an image is, the more pixels the image contains, that is, the larger the amount of information of the image is, and the clearer the image is. The resolution of a monitoring lens is generally 1 million pixels, 1.3 million pixels, 2 million pixels, 5 million pixels, and the resolution of a lens used in some environments with high imaging quality requirements is as high as 8 million pixels.

[0074] According to Table 3, the resolution of the glass-plastic hybrid lens of the present application is 5 Mega Pixel, that is, 5 million pixels, and the imaging quality is relatively high.

[0075] Field of view: the angle formed by the two edges of the maximum range of the image of the target to be shot through the lens with the lens as the vertex is called the field of view. The size of the field of view determines the range of the field of view of the lens. The larger the field of view is, the wider the field of view is. For a lens, different focal lengths correspond to different fields of view. The larger the focal length of the lens is, the smaller the field of view is, and the wider the field of view range is. The smaller the focal length of the lens is, the larger the field of view is, and the closer the field of view range is. The field of view can be divided into horizontal field of view, vertical field of view and diagonal field of view. The determining factors of the horizontal field of view are the focal length and the width of the imaging area. The determining factors of the vertical field of view are the focal length and the height of the imaging area. The determining factors of the diagonal field of view are the focal length and the width and height of the imaging area. Assuming that the width of the imaging area is W, the height of the imaging area is H, and the focal length of the lens is f, the calculation formulas of the above-mentioned fields of view are as follows:

[0076]

[0077]

[0078]

[0079] According to Table 3, the field angle of the glass-plastic hybrid lens of the application is 110°*92°*50°, that is, the diagonal field angle of the lens is 110°, the horizontal field angle is 92°, and the vertical field angle is 50°, and the field of view range of the lens is relatively wide.

[0080] Relative luminance: the brightness of an object or illuminated surface as perceived by an observer is called luminance, and the relative luminance is the ratio of the center luminance to the peripheral luminance. If the relative luminance is too low, the center of the image is brighter, while the surrounding is darker, which is called vignetting, and too low relative luminance will also cause color distortion.

[0081] According to Table 3, the relative luminance of the glass-plastic hybrid lens of the application is 59.64%, Figure 2 is a schematic diagram of the relative luminance of the glass-plastic hybrid lens, combined with Figure 2 It can be seen that when the field angle is 55.3°, the relative luminance is more than 60%, the imaging brightness of the lens is relatively high and uniform, and the color reproduction degree is high.

[0082] Distortion: distortion is the difference between the height of the intersection point of the off-axis point and the principal ray on the image plane and the height of the ideal image plane. The distortion is different at different fields of view. The change of distortion is not linear, and only the deformation of the image does not affect the sharpness of the image. Distortion can be divided into pincushion distortion and barrel distortion. The deformation of the diagonal line outward (the distortion value is positive) is called pincushion distortion, and vice versa. The deformation of the diagonal line inward (the distortion value is negative) is called barrel distortion. The calculation formula of distortion is: distortion=(actual image height-ideal image height) / ideal image height*100%.

[0083] According to Table 3, the distortion of the glass-plastic hybrid lens of the application is-38.44%, Figure 3 is a schematic diagram of the field curvature and distortion of the glass-plastic hybrid lens, combined with Figure 3 It can be seen that the aberration of the lens is controlled between-0.05 mm and 0.13 mm, the edge distortion of the lens is about 38%, the distortion is small, and the imaging quality is high.

[0084] Working temperature: surveillance cameras are not only used in daily life, but also need to be used in many harsh environments for monitoring, such as some high-altitude and cold areas, or high-temperature places such as industrial furnaces. The working temperature of ordinary cameras is-20℃~+45℃. If the environmental temperature exceeds the bearing range of the camera, the lens in the lens will swell and deform, causing extrusion or damage,

[0085] According to Table 3, the working temperature of the glass-plastic hybrid lens of the application is-30℃~+80℃,Figure 4 Fig. 6 is a schematic diagram of the MTF of the glass-plastic hybrid lens at -30°C, Figure 5 Fig. 7 is a schematic diagram of the MTF of the glass-plastic hybrid lens at 80°C, Figure 6 Fig. 8 is a schematic diagram of the visible light MTF of the glass-plastic hybrid lens, from which it can be seen that the MTF curve is relatively stable at -30°C and at 80°C, the temperature range that the lens can withstand is relatively large, the imaging difference at each part of the lens is small, and the resolution and definition are high. Figure 4 Figure 5 Figure 6

[0086] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, and therefore: any equivalent changes made in the structure, shape, principle, etc. of the present application should be encompassed within the protection scope of the present application.​​​

Claims

1. A glass-plastic hybrid lens, characterized in that: The glass-plastic hybrid lens comprises, in order from the object side to the image side along the optical axis: a first lens (1), a second lens (2), an aperture ST, a third lens (3), a fourth lens (4), a protective glass sheet (5), and an imaging surface (6); the first lens (1) is a biconcave lens, the second lens (2) is a biconvex lens, the third lens (3) is a biconvex lens, and the fourth lens (4) is a biconcave lens; The optical distance between the first lens (1) and the second lens (2) is 6.88 mm; the optical distance between the second lens (2) and the third lens (3) is 2.58 mm; the optical distance between the third lens (3) and the fourth lens (4) is 0.13 mm; and the optical distance between the fourth lens (4) and the imaging surface (6) is 5.68 mm. The focal length f of the glass-plastic hybrid lens is 3.70 mm; the focal length f1 of the first lens (1) is -5.65 mm, the focal length f2 of the second lens (2) is 9.20 mm, the focal length f3 of the third lens (3) is 3.92 mm, and the focal length f4 of the fourth lens (4) is -5.23 mm; The object side surface R6 of the third lens (3) and the image side surface R7 of the third lens (3) are both convex outwards, the third lens (3) is thick in the middle and thin at the edge, and the optical power of the third lens (3) is positive; The object side surface R8 of the fourth lens (4) and the image side surface R9 of the fourth lens (4) are both concave inwards, the fourth lens (4) is thin in the middle and thick at the edge, the optical power of the fourth lens 4 is negative, and the curvature of the object side surface R8 is greater than the curvature of the image side surface R9; The third lens (3) is thick in the middle and thin at the edges, specifically: the distance between the midpoint of the object side surface R6 of the third lens (3) and the midpoint of the image side surface R7 is d6, a point a close to the upper end point of the object side surface R6, a point b close to the lower end point of the object side surface R6, a point a' close to the upper end point of the image side surface R7, and a point b' close to the lower end point of the image side surface R7 are taken, the distance between a and a' is d7, and the distance between b and b' is d7', wherein d6 is greater than d7 and d7', and the difference between d6 and d7 and the difference between d6 and d7' are both greater than a threshold value.

2. The glass-plastic hybrid lens according to claim 1, characterized in that: The second lens (2) is a spherical lens made of glass; the first lens (1), the third lens (3), and the fourth lens (4) are aspherical lenses made of plastic.

3. The glass-plastic hybrid lens according to claim 1, characterized in that: The object side surface R1 of the first lens (1) and the image side surface R2 of the first lens (1) are both concave inwards, the first lens (1) is thin in the middle and thick at the edge, the optical power of the first lens (1) is negative, and the curvature of the object side surface R1 is smaller than the curvature of the image side surface R2.

4. The glass-plastic hybrid lens according to claim 1, characterized in that: The object side surface R3 of the second lens (2) and the image side surface R4 of the second lens (2) are both convex outwards, the second lens (2) is thick in the middle and thin at the edge, the optical power of the second lens (2) is positive, and the object side surface R3 and the image side surface R4 are symmetrical.

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