Objective system and low-light-level night vision device thereof

Abstract

The embodiment of the present disclosure provides an objective lens system and a low-light-level night vision device thereof. The objective lens system comprises a lens group, the lens group comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens which are coaxially arranged in sequence from the object side to the image side along the optical axis direction of the objective lens system, the adjacent lenses of the lens group are spaced apart by a preset distance, the first lens, the second lens, the fourth lens, the fifth lens and the sixth lens are all convex lenses, and the third lens and the seventh lens are both concave lenses. The technical scheme of the present disclosure can make the weight and size of the objective lens system small through the combination of the first lens to the seventh lens, and make the low-light-level night vision device using the objective lens system can realize optical information collection in a low-illumination environment, improve the night vision capability of the low-light-level night vision device, and improve the imaging effect.

Description

Technical Field

[0001] This disclosure relates to the field of night vision device technology, and in particular to an objective lens system and its low-light night vision device. Background Technology

[0002] The human eye has a limited spectral sensitivity range and resolution, especially in low-light conditions at night, where its ability to recognize objects gradually deteriorates until it can no longer identify them. Low-light night vision devices can amplify weak light by hundreds of thousands of times, making it visible to the naked eye, and are widely used in various fields.

[0003] In related technologies, low-light night vision devices using multi-lens objective systems still suffer from problems such as small exit pupil diameter, large size, poor portability, and inconvenience in use. Summary of the Invention

[0004] This disclosure provides an objective lens system and a low-light night vision device thereof to solve or alleviate one or more technical problems in the prior art.

[0005] As a first aspect of the present disclosure, an objective lens system is provided, including a lens group. The lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged coaxially from the object side to the image side along the optical axis of the objective lens system. Adjacent lenses in the lens group are spaced apart by a preset distance. The first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens are all convex lenses, and the third lens and the seventh lens are both concave lenses.

[0006] In some possible implementations,

[0007] The first lens has a first curved surface and a second curved surface, both of which bulge toward the object side;

[0008] The second lens has a third curved surface and a fourth curved surface, both of which bulge toward the object side;

[0009] The third lens has a fifth curved surface and a sixth curved surface, the fifth curved surface protruding towards the image side and the sixth curved surface protruding towards the object side;

[0010] The fourth lens has a seventh curved surface and an eighth curved surface, the seventh curved surface protruding towards the object side and the eighth curved surface protruding towards the image side;

[0011] The fifth lens has a ninth curved surface and a tenth curved surface, the ninth curved surface protruding towards the object side and the tenth curved surface protruding towards the image side;

[0012] The sixth lens has an eleventh curved surface and a twelfth curved surface, both of which bulge toward the object side.

[0013] The seventh lens has a thirteenth curved surface and a fourteenth curved surface, the thirteenth curved surface protruding towards the image side and the fourteenth curved surface protruding towards the object side;

[0014] The first to the fourteenth curved surfaces are arranged sequentially from the object side to the image side along the optical axis of the objective lens system.

[0015] In some possible implementations, at least one of the following is satisfied:

[0016] The radius of curvature of the first surface is 25.279 mm, and the radius of curvature of the second surface is 163.439 mm.

[0017] The radius of curvature of the third surface is 22.313 mm, and the radius of curvature of the fourth surface is 3670.980 mm.

[0018] The radius of curvature of the fifth surface is 52.054 mm, and the radius of curvature of the sixth surface is 16.738 mm.

[0019] The radius of curvature of the seventh surface is 14.977 mm, and the radius of curvature of the eighth surface is 112.700 mm.

[0020] The radius of curvature of the ninth surface is 102.000 mm, and the radius of curvature of the tenth surface is 74.487 mm.

[0021] The radius of curvature of the eleventh surface is 22.727 mm, and the radius of curvature of the twelfth surface is 76.795 mm.

[0022] The radius of curvature of the thirteenth surface is 13.442 mm, and the radius of curvature of the fourteenth surface is 76.227 mm.

[0023] The deviation of the radius of curvature of each of the above surfaces is -4% to +4%.

[0024] In some possible implementations, at least one of the following is satisfied:

[0025] The center-to-center distance between the second surface and the third surface is 2.847 mm;

[0026] The center distance between the fourth surface and the fifth surface is 0.982 mm;

[0027] The center distance between the sixth surface and the seventh surface is 2.334 mm;

[0028] The center distance between the eighth surface and the ninth surface is 0.772 mm;

[0029] The center-to-center distance between the tenth surface and the eleventh surface is 0.196 mm;

[0030] The center-to-center distance between the twelfth and thirteenth curved surfaces is 2.049 mm;

[0031] The deviation of the center distance between the above surfaces is -4% to +4%.

[0032] In some possible implementations, at least one of the following is satisfied:

[0033] The refractive index of the first lens is 1.74;

[0034] The refractive index of the second lens is 1.62;

[0035] The refractive index of the third lens is 1.81;

[0036] The refractive index of the fourth lens is 1.52;

[0037] The refractive index of the fifth lens is 1.75;

[0038] The refractive index of the sixth lens is 1.80;

[0039] The refractive index of the seventh lens is 1.85;

[0040] The refractive index deviation of each of the above lenses is -4% to +4%.

[0041] In some possible implementations, at least one of the following is satisfied:

[0042] The Abbe number of the first lens is 44.90;

[0043] The Abbe number of the second lens is 56.72;

[0044] The Abbe number of the third lens is 22.70;

[0045] The Abbe number of the fourth lens is 64.21;

[0046] The Abbe number of the fifth lens is 27.54;

[0047] The Abbe number of the sixth lens is 44.28;

[0048] The Abbe number of the seventh lens is 30.06;

[0049] The Abbe number deviation of each of the above lenses is -4% to +4%.

[0050] In some possible implementations, at least one of the following is satisfied:

[0051] The thickness of the first lens is 5.006 mm;

[0052] The thickness of the second lens is 5.393 mm;

[0053] The thickness of the third lens is 4.502 mm;

[0054] The thickness of the fourth lens is 5.036 mm;

[0055] The thickness of the fifth lens is 1.994 mm;

[0056] The thickness of the sixth lens is 6.007 mm;

[0057] The thickness of the seventh lens is 1.959 mm;

[0058] The thickness deviation of each of the above lenses is -4% to +4%.

[0059] In some possible implementations, the first lens through the seventh lens are all glass spherical lenses.

[0060] In some possible implementations, an image sensor is also included, which is disposed on the side of the seventh lens opposite to the sixth lens, and the photosensitive area of ​​the image sensor is greater than or equal to the image height of the lens group.

[0061] In some possible implementations, the objective lens system has a focal length of 22.5 mm, an operating wavelength of 440-900 nm, and a distance of 39.5 mm between the first lens and the image sensor.

[0062] As a second aspect of the present disclosure, the present disclosure provides a low-light night vision device, comprising an objective lens system, a display screen, and an eyepiece system. The display screen is located on the imaging side of the objective lens system; the eyepiece system is disposed on the side of the display screen opposite to the objective lens system, and the eyepiece system is used to magnify the image of the target to be imaged.

[0063] The following beneficial effects can be obtained by adopting the above technical solution in the embodiments of this disclosure: the objective lens system of the embodiments of this disclosure can reduce the weight and size of the objective lens system by combining the first lens to the seventh lens, and enable the low-light night vision device using this objective lens system to realize optical information acquisition in low-light environment, improve the night vision capability of the low-light night vision device, and improve the imaging effect.

[0064] The above overview is for illustrative purposes only and is not intended to be limiting in any way. Further aspects, embodiments, and features of this disclosure will become readily apparent from the accompanying drawings and the following detailed description, in addition to the illustrative aspects, embodiments, and features described above. Attached Figure Description

[0065] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments according to this disclosure and should not be construed as limiting the scope of this disclosure.

[0066] Figure 1 This is a schematic diagram of an objective lens system in one embodiment of the present disclosure;

[0067] Figure 2 This is a schematic diagram of a low-light night vision device in one embodiment of the present disclosure;

[0068] Figure 3 This is a modulation transfer function curve of an objective lens system in one embodiment of the present disclosure;

[0069] Figure 4 This is a dot diagram of an objective lens system in one embodiment of this disclosure;

[0070] Figure 5 This is a distortion diagram of the objective lens system in one embodiment of this disclosure.

[0071] Explanation of reference numerals in the attached figures:

[0072] 10. Objective lens system; 20. Eyepiece system; 30. Display screen; 40. Main control chip;

[0073] 110. First lens; 120. Second lens; 130. Third lens; 140. Fourth lens; 150. Fifth lens; 160. Sixth lens; 170. Seventh lens;

[0074] 111, First Surface; 112, Second Surface; 121, Third Surface; 122, Fourth Surface; 131, Fifth Surface; 132, Sixth Surface; 141, Seventh Surface; 142, Eighth Surface; 151, Ninth Surface; 152, Tenth Surface; 161, Eleventh Surface; 162, Twelfth Surface; 171, Thirteenth Surface; 172, Fourteenth Surface;

[0075] 200. Image sensor. Detailed Implementation

[0076] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this disclosure, and different embodiments can be combined arbitrarily without conflict. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0077] Night vision devices include active infrared night vision devices and passive infrared night vision devices. Active infrared night vision devices illuminate targets using near-infrared light sources, such as infrared LEDs, infrared lights, and infrared lasers. They employ low-light or low-light cameras to receive the infrared light reflected from the target and convert it into a video signal, displaying the image synchronously on a monitor screen. Active infrared night vision devices require their own onboard infrared radiation source for active illumination, observing by receiving the infrared light reflected from the target, resulting in poor concealment. Passive infrared night vision devices rely on receiving the infrared radiation reflected from the target itself to observe it. They detect targets based on differences in temperature and emissivity between different parts of the target, forming a visible thermal image. The drawbacks of passive infrared night vision devices are their inability to display full-color images and their higher cost, limiting their application in a wide range of equipment.

[0078] Active infrared night vision devices include two types: one is low-light night vision devices, which use very weak natural light such as moonlight, starlight, and night lights to amplify and enhance the light to achieve visibility; the other is thermal imagers, which use far-infrared sensitive detectors to detect the thermal radiation of the target itself.

[0079] Full-color low-light night vision devices can operate in low-light conditions at night by receiving natural light such as starlight, moonlight, and atmospheric glow reflected from targets. These lights are then amplified by low-light night vision detection devices to achieve a brightness suitable for human nighttime observation. Furthermore, while the human eye is only sensitive to visible light, the spectral response of low-light night vision detection devices can extend to the infrared band. By applying the photoelectric effect and photoelectronic imaging methods, they expand the visual capabilities of the human eye. Low-light night vision technology offers advantages such as low visibility and strong imaging capabilities, and has wide applications in both military and civilian fields.

[0080] A typical low-light night vision device includes an objective lens system, a low-light night vision detector, a microdisplay, an eyepiece system, a battery, a housing, and buttons. The objective lens system images the target onto the low-light night vision detector, which then performs photoelectric conversion to project the image onto the microdisplay. Finally, the human eye observes the target on the microdisplay through the magnified eyepiece system.

[0081] As the application fields of low-light night vision devices become increasingly widespread, the requirements for their adaptability in low-light environments are also becoming more stringent. This adaptability primarily depends on the objective lens system of the low-light night vision device. In related technologies, to improve the optical performance and imaging quality of the objective lens system, a combination of multiple lenses matched with an image sensor is employed. However, the objective lens systems in these technologies still suffer from problems such as small exit pupil diameter, large size, poor portability, complex structure, and heavy product weight. Furthermore, the image sensors suffer from low resolution and poor sensitivity.

[0082] To address the issues of poor imaging performance and inconvenience in the use of objective lens systems in related technologies, this disclosure provides an objective lens system.

[0083] Figure 1 This is a schematic diagram of an objective lens system provided in an embodiment of this disclosure. Figure 1 As shown in the embodiment of this disclosure, an objective lens system 10 includes a lens group. The lens group includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixth lens 160, and a seventh lens 170 arranged coaxially from the object side to the image side along the optical axis X of the objective lens system 10. Adjacent lenses in the lens group are spaced apart by a predetermined distance. The first lens 110, second lens 120, fourth lens 140, fifth lens 150, and sixth lens 160 are all convex lenses, while the third lens 130 and seventh lens 170 are both concave lenses.

[0084] In the objective lens system of this embodiment, the first lens 110 to the seventh lens 170 are arranged coaxially along the optical axis direction X, that is, the transmission direction of the incident light. The incident light enters the objective lens system 10 and passes through the first lens 110, the second lens 120, the third lens 130, the fourth lens 140, the fifth lens 150, the sixth lens 160 and the seventh lens 170 in sequence to realize the processing of light.

[0085] It should be noted that the preset distance between adjacent lenses of lens group 100 can be the preset distance between the centers of adjacent lenses of lens group 100, or it can be the distance between the two opposite surfaces of adjacent lenses in the optical axis direction. It is understood that for two adjacent lenses, the distance between the centers of the two adjacent lenses is not the same as the distance between the two opposite surfaces of the two adjacent lenses in the optical axis direction. For example, Figure 1 In the first distance, the distance between the center of the second lens 120 and the center of the third lens 130 is the first distance, and the distance between the fourth curved surface 122 of the second lens and the fifth curved surface 131 of the third lens in the optical axis direction is the second distance. The first distance and the second distance are not the same.

[0086] This embodiment employs seven lenses with specific structures arranged sequentially from the object side to the image side. The first lens 110, the second lens 120, the fourth lens 140, the fifth lens 150, and the sixth lens 160 can be convex lenses to converge light, while the third lens 130 and the seventh lens 170 can be concave lenses to diverge light. By distributing and combining the optical power of the seven lenses, the size and weight of the objective lens system are reduced, thereby increasing the exit pupil diameter of the objective lens system 10. This allows for the correction of field curvature and distortion in the objective lens system, resulting in high-quality imaging and improved image quality. This enables low-light night vision devices using this objective lens system to acquire optical information in low-light environments, thus enhancing the night vision capability of the low-light night vision device and reducing the size and weight of the objective lens system 10.

[0087] In one embodiment, the first lens 110 has a first curved surface 111 and a second curved surface 112, both of which convex toward the object side. The second lens 120 has a third curved surface 121 and a fourth curved surface 122, both of which convex toward the object side. The third lens 130 has a fifth curved surface 131 and a sixth curved surface 132, with the fifth curved surface 131 convex toward the image side and the sixth curved surface 132 convex toward the object side. The fourth lens 140 has a seventh curved surface 141 and an eighth curved surface 142, with the seventh curved surface 141 convex toward the object side and the eighth curved surface 142 convex toward the image side. The fifth lens 150 has a ninth curved surface 151 and a tenth curved surface 152, with the ninth curved surface 151 convex toward the object side and the tenth curved surface 152 convex toward the image side. The sixth lens 160 has an eleventh curved surface 161 and a twelfth curved surface 162, both of which bulge towards the object side. The seventh lens 170 has a thirteenth curved surface 171 and a fourteenth curved surface 172, with the thirteenth curved surface 171 bulging towards the image side and the fourteenth curved surface 172 bulging towards the object side. The first curved surface 111 to the fourteenth curved surface 172 are arranged sequentially from the object side to the image side along the optical axis X of the objective lens system 10. This embodiment of the present disclosure, through the arrangement of the curved surfaces on the object side and image side of each lens, enables optical information acquisition in low-light environments.

[0088] In one embodiment, the refractive index of each lens satisfies at least one of the following conditions: the refractive index of the first lens 110 is 1.74, the refractive index of the second lens 120 is 1.62, the refractive index of the third lens 130 is 1.81, the refractive index of the fourth lens 140 is 1.52, the refractive index of the fifth lens 150 is 1.75, the refractive index of the sixth lens 160 is 1.80, and the refractive index of the seventh lens 170 is 1.85, with a deviation of -4% to +4%. For example, the deviation of the refractive index of the first lens 110 is -4% to +4%, meaning that the refractive index range of the first lens 110 is 1.74*(1-4%) to 1.74*(1+4%). Since the refractive indices of one or more of the first to seventh lenses 170 are within the aforementioned corresponding ranges, light can be refracted according to actual usage requirements.

[0089] In one embodiment, the Abbe number of each lens satisfies at least one of the following conditions: the Abbe number of the first lens 110 is 44.90, the Abbe number of the second lens 120 is 56.72, the Abbe number of the third lens 130 is 22.70, the Abbe number of the fourth lens 140 is 64.21, the Abbe number of the fifth lens 150 is 27.54, the Abbe number of the sixth lens 160 is 44.28, and the Abbe number of the seventh lens 170 is 30.06. The deviation of the Abbe number of each lens can be -4% to +4%. For example, the deviation of the Abbe number of the first lens 110 is -4% to +4%, that is, the range of the Abbe number of the first lens 110 is 44.90*(1-4%) to 44.90*(1+4%). The Abbe number of one or more of the first lens 110 to the seventh lens 170 is within the corresponding ranges mentioned above.

[0090] For example, the refractive index and Abbe number of each lens can be set according to the above embodiment. For instance, the refractive indices of the first lens 110 to the seventh lens 170 can be 1.74, 1.62, 1.81, 1.52, 1.75, 1.80, and 1.85, respectively. The Abbe numbers of the first lens 110 to the seventh lens 170 can be 44.90, 56.72, 22.70, 64.21, 27.54, 44.28, and 30.06, respectively. The optical performance of this objective lens system can meet the requirements for optical information acquisition in low-light environments. The Abbe number and refractive index of each lens can be selected and set according to actual usage requirements.

[0091] In one embodiment, the radii of curvature of the first surface 111 to the fourteenth surface 172 satisfy at least one of the following conditions: The radius of curvature of the first surface 111 is 25.279*(1±4%) mm, the radius of curvature of the second surface 112 is 163.439*(1±4%) mm, the radius of curvature of the third surface 121 is 22.313*(1±4%) mm, the radius of curvature of the fourth surface 122 is 3670.980*(1±4%) mm, the radius of curvature of the fifth surface 131 is 52.054*(1±4%) mm, the radius of curvature of the sixth surface 132 is 16.738 mm*(1±4%) mm, the radius of curvature of the seventh surface 141 is 14.977*(1±4%) mm, and the radius of curvature of the eighth surface 142 is 112.700*(1±4%) mm. The radius of curvature of surface 151 (ninth surface) is 102.000*(1±4%) mm, and the radius of curvature of surface 152 (tenth surface) is 74.487*(1±4%) mm. The radius of curvature of surface 161 (eleventh surface) is 22.727*(1±4%) mm, and the radius of curvature of surface 162 (twelfth surface) is 76.795*(1±4%) mm. The radius of curvature of surface 171 (thirteenth surface) is 13.442*(1±4%) mm, and the radius of curvature of surface 172 (fourteenth surface) is 76.227*(1±4%) mm.

[0092] It should be noted that the radius of curvature of one of the first surfaces 111 to the fourteenth surfaces 172 can be set as described above, or the radii of curvature of multiple of the first surfaces 111 to the fourteenth surfaces 172 can be set as described above. The object-side surfaces and image-side surfaces of the same lens are set according to the conditions described above.

[0093] The embodiments disclosed herein improve the night vision capability and imaging effect of the low-light night vision device using the objective lens system by setting the curvature radii of the first surface 111 to the fourteenth surface 172 according to the above conditions.

[0094] In one embodiment, the thickness of each lens satisfies at least one of the following conditions: the thickness of the first lens 110 along the optical axis X is 5.006*(1±4%) mm, the thickness of the second lens 120 along the optical axis X is 5.393*(1±4%) mm, the thickness of the third lens 130 along the optical axis X is 4.502*(1±4%) mm, the thickness of the fourth lens 140 along the optical axis X is 5.036*(1±4%) mm, the thickness of the fifth lens 150 along the optical axis X is 1.994*(1±4%) mm, the thickness of the sixth lens 160 along the optical axis X is 6.007*(1±4%) mm, and the thickness of the seventh lens 170 along the optical axis X is 1.959*(1±4%) mm.

[0095] It should be noted that the thickness of a lens is expressed as the thickness at the center of the lens's optical axis, such as... Figure 1 As shown, the thickness of the first lens 110 is a first thickness d1, which is 5.006*(1-4%) mm to 5.006*(1+4%) mm. The thickness of the lens represents the center thickness. When the lens is a convex lens, the center thickness of the lens can represent the position of the maximum thickness of the lens; when the lens is a concave lens, the center thickness of the lens can represent the position of the minimum thickness of the lens. The center thickness of all lenses can be set according to the above conditions. Therefore, the weight of the objective lens system formed by each lens is small, and optical information acquisition under low illumination can be achieved.

[0096] In one embodiment, the preset distance between adjacent lenses in the lens group satisfies at least one of the following conditions: the center distance between the second surface 112 and the third surface 121 is 2.847*(1±4%) mm, the center distance between the fourth surface 122 and the fifth surface 131 is 0.982*(1±4%) mm, the center distance between the sixth surface 132 and the seventh surface 141 is 2.334*(1±4%) mm, the center distance between the eighth surface 142 and the ninth surface 151 is 0.772*(1±4%) mm, the center distance between the tenth surface 152 and the eleventh surface 161 is 0.196*(1±4%) mm, and the center distance between the twelfth surface 162 and the thirteenth surface 171 is 2.049*(1±4%) mm.

[0097] The spaced interval between adjacent lenses is a preset distance, which can be expressed as the center-to-center distance between adjacent curved surfaces of the adjacent lenses. For example, the preset distance between the first lens 110 and the second lens 120 is the center-to-center distance between the second curved surface 112 and the third curved surface 121, as shown below. Figure 1 As shown, the first center distance between the second curved surface 112 and the third curved surface 121 is d2, which is 2.847*(1-4%) to 2.847*(1+4%). The center distance between adjacent lenses can all be set according to the above conditions, so that the objective lens system formed by the lens combination is smaller in size and can realize optical information acquisition under low illumination.

[0098] In one embodiment, the first lens 110, the second lens 120, the third lens 130, the fourth lens 140, the fifth lens 150, the sixth lens 160, and the seventh lens 170 are all glass spherical lenses. Each lens can be processed by grinding.

[0099] In one embodiment, the objective lens system 10 further includes an image sensor 200, which is disposed on the side of the seventh lens 170 away from the sixth lens 160. The photosensitive area of ​​the image sensor 200 is greater than or equal to the image height of the lens group, and the center distance between the image sensor 200 and the seventh lens 170 is 0.4 mm.

[0100] For example, the photosensitive area of ​​the image sensor 200 is equal to the image height of the lens group. The image sensor 200 has a response wavelength of 400-1100nm, a resolution of 1920*1080, a pixel size of 5.8um*5.8um, and a diagonal length of 12.8mm for the target surface.

[0101] The sensitivity of the image sensor 200 is 10. -5 Lux (LUX) is the sensitivity of a standard image sensor in low-light environments. The higher the sensitivity, the stronger the adaptability to the operating environment. The low-light night vision device using the objective lens system of this disclosure has greatly improved environmental adaptability, and has higher resolution and better imaging effect.

[0102] In one embodiment, the objective lens system has a focal length of 22.5 mm, an operating wavelength of 440-900 nm, and a distance of 39.5 mm between the first lens 110 and the image sensor 200. This distance is the total length d3 of the objective lens system, which is 39.5 mm, resulting in a relatively small overall size.

[0103] Figure 3 This is a modulation transfer function (MTF) curve of an objective lens system according to an embodiment of this disclosure. The MTF is a relatively objective and comprehensive method for evaluating the imaging quality of an optical system. The MTF can be represented by an MTF curve, where the horizontal axis represents the cutoff frequency and the vertical axis represents the percentage, with the MTF value ranging from 0 to 1. The smoother the MTF curve and the higher its height relative to the X-axis, the better the imaging quality of the objective lens system 10, and the clearer the system's image. (Refer to...) Figure 3 As shown, Figure 3 Different curves represent MTF for different fields of view. The upper curve represents the MTF curve of the central field of view, and the lower curve represents the MTF curve of the edge field of view. The objective lens system of this embodiment has an MTF greater than 0.3 at a spatial frequency of 86 lp / mm, which indicates that the objective lens system of this embodiment has excellent imaging quality.

[0104] Figure 4This is a dot plot of an objective lens system according to an embodiment of the present disclosure. The dot plot can reflect the geometric structure of the optical system's imaging. In image quality evaluation, the density of the dot plot can more intuitively reflect and measure the imaging quality of the objective lens system. The smaller the root mean square radius (RMS) of the dot plot, the smaller the aberrations, and the better the imaging quality of the system. (Refer to...) Figure 4 As shown, the maximum root mean square radius of the objective lens system disclosed herein is controlled within 6.239 mm, the spot size in each field of view is very small, the aberration correction is relatively good, and the imaging quality of the objective lens system is good.

[0105] Figure 5 This is a distortion diagram of the objective lens system in one embodiment of this disclosure. Figure 5 The left side represents the field curvature curve, with the horizontal axis representing the offset and the vertical axis representing the field of view. The field curvature curve shows the distance from the current focal plane or image plane to the paraxial focal plane, as a function of the field of view coordinates. The meridional field curvature is the distance from the currently determined focal plane to the paraxial focal plane, measured along the Z-axis, and is measured on the meridional (YZ plane). The sagittal field curvature measures the distance on a plane perpendicular to the meridional plane. Figure 5 The baseline on the left is on the optical axis, and the top of the curve represents the angle or height of the maximum field of view. Figure 5 The right side of the graph represents the distortion curve, with the horizontal axis representing the percentage and the vertical axis representing the image height. Lens distortion is actually a general term for the inherent perspective distortion of optical lenses. It is distortion caused by perspective and is detrimental to the image quality of photographs. Since this is an inherent characteristic of lenses, it cannot be eliminated, only improved. Figure 5 As can be seen, the distortion of the objective lens system disclosed herein is 1%, which can effectively reduce the distortion of the image so that the human eye cannot perceive the image deformation.

[0106] Figure 2 This is a schematic diagram of a low-light night vision device according to an embodiment of the present disclosure. As a second aspect of the present disclosure, an embodiment provides a low-light night vision device, including an objective lens system 10, a display screen 30, and an eyepiece system 20, as described in the first aspect. The objective lens system 10 is used to acquire light emitted from a target to be imaged, and the display screen 30 is located on the imaging side of the objective lens system 10. The eyepiece system 20 is disposed on the side of the display screen 30 opposite to the objective lens system 10, and the eyepiece system 20 can be used to magnify the image. The low-light night vision device may further include a main control chip 40, which is disposed between the objective lens system 10 and the display screen 30.

[0107] In one disclosed embodiment, the optical parameters of the objective lens system 10 are: an objective lens aperture F-number of 1.2, a focal length of f = 22.5 mm, and a field of view of 31.4°. The optical parameters of the eyepiece system 20 are: a magnification of 13.9, a field of view of 30°, an exit pupil diameter of 7 mm, and an exit pupil distance of 20 mm.

[0108] The low-light night vision device of this disclosure, by employing the objective lens system of the above-disclosed embodiment, achieves a field of view of 31.4°, a focal length of 22.5mm, distortion of less than 1%, a working wavelength of 440-900nm, a total optical length of 39.5mm, an image sensor resolution of 1920*1080, a pixel size of 5.8um*5.8um, and a sensitivity of 10. -5 Lux can achieve high performance in low-light environments, such as 10 -2 Optical information acquisition in lux environments enhances the night vision capability of the entire low-light night vision device and improves imaging performance.

[0109] Other components of the objective lens system and its low-light night vision device in the above embodiments can be adopted from various technical solutions that are now and will be known to those skilled in the art, and will not be described in detail here.

[0110] In the description of this specification, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0111] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "multiple" means two or more, unless otherwise explicitly specified.

[0112] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0113] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0114] The foregoing disclosure provides many different implementations or examples for carrying out different structures of this disclosure. To simplify this disclosure, the components and arrangements of specific examples are described above. Of course, these are merely examples and are not intended to limit this disclosure. Furthermore, reference numerals and / or reference letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed.

[0115] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this disclosure, and these should all be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. An objective lens system, characterized in that, include The lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged coaxially from the object side to the image side along the optical axis of the objective lens system. Adjacent lenses in the lens group are spaced apart by a preset distance. The first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens are all convex lenses, and the third lens and the seventh lens are both concave lenses. The first lens has a first curved surface and a second curved surface, both of which protrude toward the object side. The second lens has a third curved surface and a fourth curved surface, both of which bulge toward the object side; The third lens has a fifth curved surface and a sixth curved surface, the fifth curved surface protruding towards the image side and the sixth curved surface protruding towards the object side; The fourth lens has a seventh curved surface and an eighth curved surface, the seventh curved surface protruding towards the object side and the eighth curved surface protruding towards the image side; The fifth lens has a ninth curved surface and a tenth curved surface, the ninth curved surface protruding towards the object side and the tenth curved surface protruding towards the image side; The sixth lens has an eleventh curved surface and a twelfth curved surface, both of which bulge toward the object side. The seventh lens has a thirteenth curved surface and a fourteenth curved surface, the thirteenth curved surface protruding towards the image side and the fourteenth curved surface protruding towards the object side; The first to the fourteenth curved surfaces are arranged sequentially from the object side to the image side along the optical axis of the objective lens system.

2. The objective lens system according to claim 1, characterized in that, Satisfy at least one of the following: The radius of curvature of the first surface is 25.279 mm, and the radius of curvature of the second surface is 163.439 mm. The radius of curvature of the third surface is 22.313 mm, and the radius of curvature of the fourth surface is 3670.980 mm. The radius of curvature of the fifth surface is 52.054 mm, and the radius of curvature of the sixth surface is 16.738 mm. The radius of curvature of the seventh surface is 14.977 mm, and the radius of curvature of the eighth surface is 112.700 mm. The radius of curvature of the ninth surface is 102.000 mm, and the radius of curvature of the tenth surface is 74.487 mm. The radius of curvature of the eleventh surface is 22.727 mm, and the radius of curvature of the twelfth surface is 76.795 mm. The radius of curvature of the thirteenth surface is 13.442 mm, and the radius of curvature of the fourteenth surface is 76.227 mm. The deviation of the radius of curvature of each of the above surfaces is -4% to +4%.

3. The objective lens system according to claim 1, characterized in that, Satisfy at least one of the following: The center-to-center distance between the second surface and the third surface is 2.847 mm; The center distance between the fourth surface and the fifth surface is 0.982 mm; The center distance between the sixth surface and the seventh surface is 2.334 mm; The center distance between the eighth surface and the ninth surface is 0.772 mm; The center-to-center distance between the tenth surface and the eleventh surface is 0.196 mm; The center-to-center distance between the twelfth and thirteenth curved surfaces is 2.049 mm; The deviation of the center distance between the above surfaces is -4% to +4%.

4. The objective lens system according to any one of claims 1 to 3, characterized in that, Satisfy at least one of the following: The refractive index of the first lens is 1.74; The refractive index of the second lens is 1.62; The refractive index of the third lens is 1.81; The refractive index of the fourth lens is 1.52; The refractive index of the fifth lens is 1.75; The refractive index of the sixth lens is 1.80; The refractive index of the seventh lens is 1.85; The refractive index deviation of each of the above lenses is -4% to +4%.

5. The objective lens system according to any one of claims 1 to 3, characterized in that, Satisfy at least one of the following: The Abbe number of the first lens is 44.90; The Abbe number of the second lens is 56.72; The Abbe number of the third lens is 22.70; The Abbe number of the fourth lens is 64.21; The Abbe number of the fifth lens is 27.54; The Abbe number of the sixth lens is 44.28; The Abbe number of the seventh lens is 30.06; The Abbe number deviation of each of the above lenses is -4% to +4%.

6. The objective lens system according to any one of claims 1 to 3, characterized in that, Satisfy at least one of the following: The thickness of the first lens is 5.006 mm; The thickness of the second lens is 5.393 mm; The thickness of the third lens is 4.502 mm; The thickness of the fourth lens is 5.036 mm; The thickness of the fifth lens is 1.994 mm; The thickness of the sixth lens is 6.007 mm; The thickness of the seventh lens is 1.959 mm; The thickness deviation of each of the above lenses is -4% to +4%.

7. The objective lens system according to any one of claims 1 to 3, characterized in that, The first lens through the seventh lens are all glass spherical lenses.

8. The objective lens system according to any one of claims 1 to 3, characterized in that, It also includes an image sensor, which is disposed on the side of the seventh lens away from the sixth lens, and the photosensitive area of ​​the image sensor is greater than or equal to the image height of the lens group.

9. The objective lens system according to claim 8, characterized in that, The objective lens system has a focal length of 22.5 mm and an operating wavelength of 440-900 nm. The distance between the first lens and the image sensor is 39.5 mm.

10. A low-light night vision device, characterized in that, include The objective lens system as described in any one of claims 1 to 9; The display screen is located on the imaging side of the objective lens system; An eyepiece system is disposed on the side of the display screen opposite to the objective lens system, and the eyepiece system is used to magnify the image of the target to be imaged.

Images