Large field of view optical imaging lens and optical system composed thereof

Abstract

The present invention provides a large-field optical imaging lens and an optical system composed of the same. The large-field optical imaging lens includes: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a filter arranged in sequence along the light propagation direction; wherein the first lens, the second lens and the eighth lens are meniscus lenses, the third lens and the sixth lens are double concave lenses, and the fourth lens, the fifth lens and the seventh lens are double convex lenses. Compared with traditional satellite-borne lenses, the large-field optical imaging lens provided by the present invention and the optical system composed of the same have the advantages of high resolution, small size, light weight, etc. The imaging quality of the optical system is as high as 26 million pixels, and the imaging spectrum is wide and the field of view is large. It can adapt to the harsh environment of satellite launch and orbital operation, and has the advantages of anti-impact and vibration, resistance to high temperature difference in space, strong radiation, etc. It overcomes the complexity of the space environment and meets the space use requirements of aerospace engineering.

Description

Technical Field

[0001] The present invention relates to the technical field of optical design, and in particular to an optical imaging lens with a large field of view and high resolution and an optical system composed thereof. Background Art

[0002] As the battle for space resource development intensifies, the development of high-resolution space target detection systems has become the key to competition. The core component of the detection system is the target detection lens, which is mainly used for the detection and tracking of space targets and debris. To this end, the successful development of high-resolution micro-satellite camera optical systems has played an important role in improving my country's near-Earth space target monitoring capabilities. The earliest use of CCD cameras as satellite-borne earth observation payloads was in the early 1980s. Satellite-borne cameras as earth observation instruments were truly valued and entered the practical stage after France successfully launched the Spot-1 satellite in February 1986. The HRVCCD camera on the satellite achieved great success. On November 26, 2011, the U.S. Mars rover "Curiosity" was equipped with a group of advanced detection instruments, including 17 2-megapixel CCD cameras.

[0003] my country started developing space cameras relatively late. In November 1975, the first visible spectrum space camera, “Jianbing No. 1”, was launched on the first recoverable satellite. In October 2007, Chang’e No. 1 satellite was successfully launched, carrying three optical remote sensors, CCD cameras, laser altimeters and imaging spectrometers. In August 2008, my country’s environmental disaster reduction satellite was successfully launched, with the CCD camera having a maximum MTF of 0.22 at 77lp / mm. On September 26, 2009, the camera lens of the companion satellite of the Shenzhou VII spacecraft developed by Fujian Normal University obtained a panoramic image of an in-orbit spacecraft at close range for the first time, with 1.3 million pixels. In 2010, the Xi’an Institute of Optics and Precision Mechanics of the Chinese Academy of Sciences developed a satellite-borne long-focal-length high-resolution CCD remote sensing camera with a minimum ground resolution of 0.5m. In the relevant literature published in China, the design of the optical system of a satellite-borne large-field-of-view multi-spectral high-resolution CCD camera published by Lan Liyan et al. has a full field of view of 3°, a relatively large volume of 500mm×400mm×400mm, and a system structure using 11 lenses. In the design of the optical system of a satellite-borne multi-spectral camera published by Zhang Danfeng et al., the system mass is about 5kg and the resolution is 1024×1024. It can be seen that the currently disclosed satellite-borne lenses have the disadvantages of small field of view, low imaging quality, and heavy weight. Summary of the invention

[0004] The present invention aims to solve the problems of small field of view, low imaging quality and heavy weight of existing satellite-borne lenses, and to provide a large field of view optical imaging lens and an optical system composed thereof, which have the advantages of high resolution, small size and light weight. The imaging quality of the optical system is as high as 26 million pixels, and the imaging spectrum is wide and the field of view is large. It can adapt to the harsh environment of satellite launch and orbital operation, and has the advantages of anti-shock and vibration, resistance to high temperature difference in space, strong radiation, etc. It overcomes the complexity of the space environment and meets the space use requirements of aerospace engineering.

[0005] To achieve the above object, the present invention adopts the following specific technical solutions:

[0006] The wide-field optical imaging lens provided by the present invention comprises: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a filter arranged in sequence along the light propagation direction; wherein the first lens, the second lens and the eighth lens are respectively meniscus lenses, the third lens and the sixth lens are respectively double concave lenses, and the fourth lens, the fifth lens and the seventh lens are respectively double convex lenses.

[0007] Preferably, the first lens is made of SILICA, the radius of curvature of the front surface thereof is 30 mm to 40 mm, the radius of curvature of the rear surface thereof is 12 mm to 20 mm, and the thickness thereof is 3 mm to 5 mm.

[0008] Preferably, the second lens is made of H-ZBAF1, the curvature radius of the front surface thereof is 30 mm to 40 mm, the curvature radius of the rear surface thereof is 60 mm to 75 mm, the thickness thereof is 2 mm to 4 mm, and the distance between the second lens and the first lens is 11 mm to 13 mm.

[0009] Preferably, the third lens is made of TF3, the curvature radius of the front surface thereof is -20 mm to -40 mm, the curvature radius of the rear surface thereof is 20 mm to 40 mm, the thickness thereof is 2 mm to 4 mm, and the distance between the third lens and the second lens is 5 mm to 7 mm.

[0010] Preferably, the fourth lens is made of H-K9L, the curvature radius of the front surface thereof is 30 mm to 40 mm, the curvature radius of the rear surface thereof is -20 mm to -40 mm, the thickness thereof is 3 mm to 6 mm, and the distance between the fourth lens and the second lens is 1 mm to 5 mm.

[0011] Preferably, the fifth lens is made of H-F2, the curvature radius of its front surface is 20 mm to 30 mm, the curvature radius of its rear surface is -20 mm to -30 mm, its thickness is 2 mm to 4 mm, and the distance between it and the fourth lens is 8 mm to 12 mm.

[0012] Preferably, the sixth lens is made of H-FK61, the curvature radius of the front surface thereof is -20 mm to -40 mm, the curvature radius of the rear surface thereof is 40 mm to 65 mm, the thickness thereof is 2 mm to 4 mm, and the distance between the sixth lens and the fifth lens is 2 mm to 4 mm.

[0013] Preferably, the seventh lens is made of H-LAF4, the curvature radius of the front surface thereof is 100 mm to 300 mm, the curvature radius of the rear surface thereof is -30 mm to -45 mm, the thickness thereof is 4 mm to 7 mm, and the distance between the seventh lens and the sixth lens is 2 mm to 4 mm.

[0014] Preferably, the eighth lens material is H-LAK2, the curvature radius of its front surface is -10mm to -20mm, the curvature radius of its rear surface is -20mm to -40mm, its thickness is 2mm to 4mm, and the distance between it and the seventh lens is 11mm to 17mm; the filter material is H-K9L, its thickness is 2mm to 4mm, and the distance between it and the eighth lens is 1mm to 3mm.

[0015] The optical system provided by the present invention comprises the aforementioned large-field optical imaging lens and a CCD sensor for imaging the large-field optical imaging lens.

[0016] Compared with traditional satellite-borne lenses, the large-field-of-view optical imaging lens provided by the present invention and the optical system it constitutes have the advantages of high resolution, small size, and light weight. The imaging quality of the optical system is as high as 26 million pixels, and the imaging spectrum is wide and the field of view is large. It can adapt to the harsh environment of satellite launch and orbital operation, and has the advantages of resistance to impact and vibration, high temperature differences in space, and strong radiation. It overcomes the complexity of the space environment and meets the space use requirements of aerospace engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a structural diagram of a large-field optical imaging lens and an optical system thereof according to an embodiment of the present invention;

[0018] Figure 2 is a spot diagram of an optical system according to an embodiment of the present invention;

[0019] Figure 3 is a diagram of an optical transfer function of an optical system according to an embodiment of the present invention;

[0020] Figure 4 is a diagram of field curvature and distortion of an optical system according to an embodiment of the present invention.

[0021] The reference numerals include: a first lens 1 , a second lens 2 , a third lens 3 , a fourth lens 4 , a fifth lens 5 , a sixth lens 6 , a seventh lens 7 , an eighth lens 8 , a filter 9 , a mechanical aperture 10 , and a CCD sensor 11 . DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0023] The present invention requires the design of a large field of view, high resolution optical imaging lens and its optical system, which can clearly image in the spectral range of 430nm to 700nm. The focal length is 46mm and the entrance pupil diameter is 、 The field of view angle is 40°, and the relative illumination of the edge field of view is 0.86. The full field of view MTF is ≥0.65@55lp / mm or ≥0.38@110lp / mm, the distortion is better than -1.0%, and the radiation resistance is ≥5krad. The lens mass is 576g, and the dimensions are Φ52mm×100mm. Through the simulation and optimization of temperature adaptability, the large field of view optical imaging lens was tested in a thermal vacuum environment of 15℃~25℃ and can work normally.

[0024] Due to the harsh space environment, the optical system should meet the requirements of shock and vibration resistance, high temperature difference resistance in space, strong radiation, etc., and it needs to be small in size and light in weight. According to the above conditions, the performance technical indicators of the optical system are as follows:

[0025] The entrance pupil diameter is , design wavelength is 430nm~700nm (clear imaging can be achieved within the spectrum range of 430nm~700nm), reference wavelength is 550nm, field of view angle is 40°, relative illumination of edge field of view is 0.86, focal length is 46mm, distortion is less than 1%, MTF ≥ 0.3@110lp / mm, radiation resistance ≥ 5krad, temperature range is 20℃±5℃.

[0026] The difficulty in designing the optical system is that the imaging band of 430nm to 700nm belongs to the near-ultraviolet to near-infrared band. To design a high-quality optical imaging lens in this band, it is necessary to perform apochromatic design to balance various aberrations in the optical system and ultimately meet the design requirements. In addition, the optical system must meet the requirements of low-load miniaturization, which makes the design of the optical system more difficult.

[0027] In order to ensure the realization of the above theoretical design values, the optical parts in the optical system need to have sufficiently high precision, such as lens thickness, radius of curvature, surface accuracy, etc., and during the assembly process, the optical spacing between lenses must be adjusted, and assembly errors such as tilt and eccentricity must be controlled to ensure that the lens full field of view MTF ≥ 0.3@110lp / mm.

[0028] In order to reduce the damage of space radiation to the imaging system, the use of radiation-resistant quartz glass as the first lens can greatly reduce the impact of space radiation and ensure the service life of the optical system in the camera. Due to the drastic changes in the temperature of the space environment, it is necessary to control the temperature of the entire camera and design the optical system to eliminate the heat difference within the temperature range, that is, to design the lens to be athermal.

[0029] The wide-field optical imaging lens and the optical system formed by the lens are described in detail below.

[0030] Figure 1 The structure of a large-field optical imaging lens and an optical system formed by the lens is shown in one embodiment of the present invention.

[0031] like Figure 1 As shown, the optical imaging lens with a large field of view provided by the embodiment of the present invention comprises: a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8 and a filter 9 which are sequentially arranged along the light propagation direction; wherein the first lens 1, the second lens 2 and the eighth lens 8 are meniscus lenses respectively, the third lens 3 and the sixth lens 6 are double concave lenses respectively, and the fourth lens 4, the fifth lens 5 and the seventh lens 7 are double convex lenses respectively. The first lens 1 is used to reduce the system spherical aberration, the second lens 2 is used to adjust the system spherical aberration, the third lens 3 is used to reduce the system chromatic aberration, the fourth lens 4 is used to reduce the system coma and astigmatism, the fifth lens 5 is used to balance the system coma and astigmatism, the sixth lens 6 is used to reduce the system chromatic aberration, the seventh lens 7 is used to balance the system chromatic aberration, and the eighth lens 8 is used to reduce the system field curvature and distortion.

[0032] In a specific embodiment of the present invention, a mechanical diaphragm 10 is disposed between the fourth lens 4 and the fifth lens 5 . The mechanical diaphragm 10 serves as an aperture diaphragm for limiting the light beam incident on the fifth lens 5 .

[0033] In another specific embodiment of the present invention, the first lens material is SILICA, the radius of curvature of the front surface is 30mm-40mm, the radius of curvature of the rear surface is 12mm-20mm, and the thickness is 3mm-5mm. The second lens material is H-ZBAF1, the radius of curvature of the front surface is 30mm-40mm, the radius of curvature of the rear surface is 60mm-75mm, the thickness is 2mm-4mm, and the distance from the first lens is 11mm-13mm. The third lens material is TF3, the radius of curvature of the front surface is -20mm--40mm, the radius of curvature of the rear surface is 20mm-40mm, the thickness is 2mm-4mm, and the distance from the second lens is 5mm-7mm. The fourth lens is made of H-K9L, the radius of curvature of its front surface is 30mm to 40mm, the radius of curvature of its rear surface is -20mm to -40mm, the thickness is 3mm to 6mm, and the distance between it and the second lens is 1mm to 5mm. The fifth lens is made of H-F2, the radius of curvature of its front surface is 20mm to 30mm, the radius of curvature of its rear surface is -20mm to -30mm, the thickness is 2mm to 4mm, and the distance between it and the fourth lens is 8mm to 12mm. The sixth lens is made of H-FK61, the radius of curvature of its front surface is -20mm to -40mm, the radius of curvature of its rear surface is 40mm to 65mm, the thickness is 2mm to 4mm, and the distance between it and the fifth lens is 2mm to 4mm. The seventh lens is made of H-LAF4, with a front surface curvature radius of 100mm to 300mm, a rear surface curvature radius of -30mm to -45mm, a thickness of 4mm to 7mm, and a spacing of 2mm to 4mm from the sixth lens. The eighth lens is made of H-LAK2, with a front surface curvature radius of -10mm to -20mm, a rear surface curvature radius of -20mm to -40mm, a thickness of 2mm to 4mm, and a spacing of 11mm to 17mm from the seventh lens. The filter is made of H-K9L, with a thickness of 2mm to 4mm, and a spacing of 1mm to 3mm from the eighth lens.

[0034] The optical system of the embodiment provided by the present invention comprises the aforementioned large-field optical imaging lens and a CCD sensor 11 for imaging the large-field optical imaging lens. The distance between the filter 9 and the CCD sensor 11 is 16.2 mm.

[0035] In the selection of lens materials, quartz glass is used as the anti-radiation protection material, which can effectively protect the CCD imaging sensor from damage by space radiation and ensure the effective life of the optical system. By using low dispersion and special dispersion materials, the optical system can achieve high-quality imaging in the 430nm to 700nm spectrum range. The parameters of each optical element in the final optical system (radius, thickness, material, etc.) are shown in Tables 1 to 5:

[0036] Table 1 Parameters of optical components in the optical system

[0037]

[0038] Table 2 Parameters of optical components in the optical system

[0039]

[0040] Table 3 Parameters of optical components in the optical system

[0041]

[0042] The above-mentioned large field of view optical imaging lens and CCD detector 11 constitute the optical system of an embodiment of the present invention. The light emitted by the imaging object passes through the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the eighth lens 8 and the filter 9 in sequence and is imaged on the image plane of the CCD detector 11.

[0043] Figure 2 is a spot diagram of an optical system according to one embodiment of the present invention.

[0044] like Figure 2 As shown in the figure, FIELD represents the imaging field, and RMS RADIUS represents the root mean square radius of the image plane diffuse spot. Figure 2 It can be seen that the RMS diameter of the central field point diagram at the image plane of the optical system of the present invention is <5.1 μm, and the RMS diameter of the edge field point diagram is <10.2 μm.

[0045] Figure 3 is a diagram of an optical transfer function constituting an optical system according to an embodiment of the present invention.

[0046] like Figure 3As shown, the abscissa represents the transfer function value, and the ordinate represents the line pair value per millimeter. In the figure, the curve TSDIFF.LIMT is the diffraction limit transfer function curve of the optical system, the curve TS 0.00 DEG is the on-axis field transfer function curve, the T curve in the curve TS4.00 DEG is the 4° field meridian transfer function curve, the S curve in the curve TS 4.00 DEG is the 4° field sagittal transfer function curve, the T curve in the curve TS 8.00 DEG is the 8° field meridian transfer function curve, the S curve in the curve TS 8.00 DEG is the 8° field sagittal transfer function curve, the T curve in the curve TS 12.00 DEG is the 12° field meridian transfer function curve, the S curve in the curve TS 12.00 DEG is the 12° field sagittal transfer function curve, the T curve in the curve TS 16.00 DEG is the 16° field meridian transfer function curve, the S curve in the curve TS 16.00 DEG is the 16° field sagittal transfer function curve, and the curve TS 20.00 The T curve in DEG is the meridian transfer function curve of 20° field of view, and the curve TS 20.00 in DEG is the sagittal transfer function curve of 20° field of view. Figure 3 It can be seen that the optical system has the advantage of high transfer function at the image plane, and the full field MTF is > 0.38@110lp / mm.

[0047] Figure 4 is a diagram of field curvature and distortion of an optical system according to an embodiment of the present invention.

[0048] like Figure 4 As shown in the figure, the left half is the field curvature value curve of the optical system, the horizontal axis is the field curvature value, the unit is millimeter, and the vertical axis is the normalized field of view. The right half is the distortion value curve of the optical system, the horizontal axis is the percentage of the distortion value, and the vertical axis is the normalized field of view. Figure 4 It can be seen that the optical system of the present invention has the advantage of low distortion, and the distortion in the whole field of view is better than -1.0%.

[0049] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0050] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

[0051] The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A large field of view optical imaging lens, characterized in that: include: A first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a filter are sequentially arranged along the light propagation direction; wherein the first lens, the second lens and the eighth lens are meniscus lenses, the third lens and the sixth lens are double concave lenses, and the fourth lens, the fifth lens and the seventh lens are double convex lenses; the first lens material is SILICA, the curvature radius of its front surface is 30mm-40mm, the curvature radius of its rear surface is 12mm-20mm, and the thickness is 3mm-5mm; the second lens material is H-ZBAF1, the curvature radius of its front surface is 30mm-40mm, the curvature radius of its rear surface is 60mm-75mm, the thickness is 2mm-4mm, and the distance between the first lens and the second lens is 11mm-13mm.

2. The wide field of view optical imaging lens according to claim 1, characterized in that: The third lens is made of TF3, the radius of curvature of its front surface is -20mm to -40mm, the radius of curvature of its rear surface is 20mm to 40mm, its thickness is 2mm to 4mm, and the distance between it and the second lens is 5mm to 7mm.

3. The wide field of view optical imaging lens according to claim 1, characterized in that: The fourth lens is made of H-K9L, the radius of curvature of its front surface is 30mm to 40mm, the radius of curvature of its rear surface is -20mm to -40mm, its thickness is 3mm to 6mm, and the distance between it and the third lens is 1mm to 5mm.

4. The wide field of view optical imaging lens according to claim 1, characterized in that: The sixth lens is made of H-FK61, the radius of curvature of the front surface is -20mm to -40mm, the radius of curvature of the rear surface is 40mm to 65mm, the thickness is 2mm to 4mm, and the distance between the sixth lens and the fifth lens is 2mm to 4mm.

5. The wide field of view optical imaging lens according to claim 1, characterized in that: The seventh lens is made of H-LAF4, the radius of curvature of the front surface is 100mm to 300mm, the radius of curvature of the rear surface is -30mm to -45mm, the thickness is 4mm to 7mm, and the distance between the seventh lens and the sixth lens is 2mm to 4mm.

6. An optical system, characterized in that: It comprises a large-field-of-view optical imaging lens as claimed in any one of claims 1 to 5 and a CCD sensor for imaging the large-field-of-view optical imaging lens.

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