An underwater optical imaging system

Abstract

The application provides an underwater optical imaging system which is composed of an optical imaging module, a photoelectric detector module, a data storage module and a display module. The optical imaging module comprises seven lenses, and the lenses are arranged in the order of a negative lens, a positive lens, a negative lens, a negative lens, a positive lens, a positive lens and a negative lens along the direction of light incidence. The focal length of the optical imaging module is 14.38 mm, the F number of the image side is 2.0, the field of view angle is 48 degrees, and the total length of the optical imaging module is 43.35 mm. The optical imaging module works in the visible light waveband, and the working wavelength range is 400 nm to 700 nm. The photoelectric detector module can adopt a CCD or CMOS detector. The image data collected by the photoelectric detector module can be stored in the data storage module synchronously, and the image data in the storage module can be displayed through the display module. The optical imaging module comprises two aspheric lenses, which significantly improves the imaging quality and ensures that the system can clearly image underwater. In the design process of the optical imaging module, all kinds of aberrations are corrected and balanced, and finally, the optical imaging module has the advantages of large F number, high imaging resolution, miniaturization, high cost performance and the like.

Description

Technical Field

[0001] This invention relates to the field of optical design technology, and in particular to an underwater optical imaging system. Background Technology

[0002] Oceans cover 71% of the Earth's surface and possess enormous resource reserves and energy potential. In recent years, my country has increasingly emphasized the development of marine resources, which necessitates high-performance underwater optical imaging systems. Furthermore, humans are also developing and utilizing inland rivers and lakes. Whether it's large-scale hydropower projects or flood control projects, regular maintenance and real-time, efficient monitoring are required, which also rely heavily on high-performance underwater optical imaging systems. Underwater optical imaging systems should be capable of acquiring high-contrast, high-resolution images and can be applied to seabed topographic imaging, underwater aquaculture, seabed resource exploration, marine development, underwater archaeology, underwater detection and search and rescue, as well as military applications such as mine detection and territorial sea defense.

[0003] Compared to land-based optical imaging systems, underwater optical imaging systems operate in a more complex medium. Because underwater optical imaging systems operate underwater, the absorption and scattering characteristics of the water medium, as well as the influence of impurities, cause significant energy loss and optical noise during light propagation. This results in low underwater visibility and poor imaging quality, making underwater resource surveys extremely difficult.

[0004] Conventional optical imaging systems suffer from reduced imaging distances due to light absorption and scattering by water, resulting in images with reduced brightness, color distortion, contrast loss, and resolution. The images contain less information and fail to meet the needs of researchers. High-performance synchronous scanning systems have extended imaging distances and have become a common detection method for large-scale exploration platforms. However, these devices are typically bulky and expensive, making them unsuitable for areas with variable environments and high flexibility requirements, such as nearshore and river engineering projects. Therefore, designing a miniaturized and portable underwater imaging optical system with high imaging resolution, high contrast, cost-effectiveness, and high performance is a pressing issue in this field. Summary of the Invention

[0005] This invention provides an underwater optical imaging system, comprising four parts: an optical imaging module, a photodetector module, a data storage module, and a display module. The optical imaging module operates in the visible light band, with a wavelength range of 400nm to 700nm. The photodetector module can employ a CCD or CMOS detector. Image data acquired by the photodetector module can be synchronously stored in the data storage module, and the image data in the storage can be displayed through the display module. The optical imaging module includes seven lenses, two of which are aspherical lenses, significantly improving image quality and ensuring clear underwater imaging. During the design process, all types of aberrations were corrected and balanced, resulting in an optical imaging module with advantages such as a large F-number, high imaging resolution, miniaturization, and high cost-effectiveness.

[0006] This invention provides an underwater optical imaging system, comprising four parts: an optical imaging module, a photodetector module, a data storage module, and a display module. The optical imaging module includes a first negative lens, a first positive lens, a second negative lens, a third negative lens, a second positive lens, a third positive lens, and a fourth negative lens arranged coaxially along the incident light direction. The first negative lens is made of HZF1A_CDGM material, with a light transmittance of 24.0mm < aperture diameter < 25.0mm and a thickness of 4.5mm < 5.5mm. The first positive lens is made of NLAF2_SCHOTT material, with a light transmittance of 16.0mm < aperture diameter < 17.0mm and a thickness of 5.0mm < 6.0mm. The second negative lens is made of K7_SCHOTT material. The material of the third negative lens is ZF5_CDGM, with a light transmittance of 0.5mm < aperture diameter < 11.5mm and a thickness of 1.0mm < 2.0mm; the material of the second positive lens is SLAL56_OHARA, with a light transmittance of 9.0mm < aperture diameter < 10.0mm and a thickness of 3.5mm < 4.5mm; the material of the third positive lens is NLAF2_SCHOTT, with a light transmittance of 12.0mm < aperture diameter < 13.0mm and a thickness of 5.5mm < 6.0mm; the material of the fourth negative lens is SF4_SCHOTT, with a light transmittance of 11.0mm < aperture diameter < 11.5mm and a thickness of 3.5mm < 4.5mm.

[0007] Optionally, the first negative lens has a light-transmitting aperture of 24.6 mm and a thickness of 5.0 mm; the first positive lens has a light-transmitting aperture of 16.6 mm and a thickness of 5.5 mm; the second negative lens has a light-transmitting aperture of 11.2 mm and a thickness of 1.5 mm; the third negative lens has a light-transmitting aperture of 5.1 mm and a thickness of 1.5 mm; the second positive lens has a light-transmitting aperture of 9.6 mm and a thickness of 4.1 mm; the third positive lens has a light-transmitting aperture of 12.4 mm and a thickness of 5.7 mm; and the fourth negative lens has a light-transmitting aperture of 11.3 mm and a thickness of 4.0 mm.

[0008] Optionally, the third negative lens and the second positive lens form a cemented lens.

[0009] Optionally, the distance between the center of the light-emitting surface of the fourth negative lens and the image plane is 6.0 mm.

[0010] Optionally, the optical dimensions of the optical imaging module are φ24.6×43.35mm.

[0011] Optionally, the optical imaging module has a system focal length of 14.38 mm and an F-number of 2.0.

[0012] Optionally, the optical imaging module operates in the wavelength range of 400nm to 700nm.

[0013] Optionally, the optical imaging module has a full field of view of 48°.

[0014] As can be seen from the above technical solutions, the embodiments of the present invention have the following advantages: 1. The underwater optical imaging system has an optical imaging module operating in the wavelength range of 400nm~700nm. The optical imaging module contains 7 lenses, 5 of which are standard spherical lenses, with an optical dimension of φ24.6×43.35mm, offering advantages in miniaturization and cost-effectiveness.

[0015] 2. The underwater optical imaging system has an optical imaging module with a focal length of 14.38mm, an F number of 2.0, and a field of view of 48°. All aberrations have been corrected and balanced. The optical imaging module has advantages such as excellent image quality, high imaging resolution, and a large F number. Attached Figure Description

[0016] Figure 1 This is a diagram showing the optical path structure of the optical imaging module of the underwater optical imaging system of the present invention. Figure 2 This is a dot diagram of the optical imaging module of the underwater optical imaging system of the present invention; Figure 3This is the modulation transfer function of the optical imaging module of the underwater optical imaging system of the present invention; Figure reference numerals: 1-First negative lens; 2-First positive lens; 3-Second negative lens; STO-Aperture stop; 4-Third negative lens; 5-Second positive lens; 6-Third positive lens; 7-Fourth negative lens; IMA-Image plane. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0018] Please refer to Figure 1 The diagram below shows the optical path structure of this invention. The optical imaging module of this underwater optical imaging system includes seven lenses arranged in a negative-positive-negative-positive-positive-negative pattern. Two of these lenses are aspherical, significantly improving image quality and enabling clear underwater imaging. The seven lenses are arranged coaxially along the light incident direction: a first negative lens 1, a first positive lens 2, a second negative lens 3, a third negative lens 4, a second positive lens 5, a third positive lens 6, and a fourth negative lens 7. The first negative lens 1 is made of HZF1A_CDGM material, with a diameter of 24.0 mm < aperture diameter < 25.0 mm and a thickness of 4.5 mm < 5.5 mm. The first positive lens 2 is made of NLAF2_SCHOTT material, with a diameter of 16.0 mm < aperture diameter < 17.0 mm and a thickness of 5.0 mm < 6.0 mm. The second negative lens 3 is made of K7_SCHOTT material, with a diameter of 10.5 mm < aperture diameter < 11.5 mm and a thickness of 1.0 mm < 6.0 mm. <2.0mm; the material of the third negative lens 4 is ZF5_CDGM, 4.5mm < aperture diameter < 5.5mm, 1.0mm < thickness < 2.0mm; the material of the second positive lens 5 is SLAL56_OHARA, 9.0mm < aperture diameter < 10.0mm, 3.5mm < thickness < 4.5mm; the material of the third positive lens 6 is NLAF2_SCHOTT, 12.0mm < aperture diameter < 13.0mm, 5.5mm < thickness < 6.0mm; the material of the fourth negative lens 7 is SF4_SCHOTT, 11.0mm < aperture diameter < 11.5mm, 3.5mm < thickness < 4.5mm.

[0019] In one embodiment, the first negative lens 1 has a light-transmitting aperture of 24.6 mm and a thickness of 5.0 mm; the first positive lens 2 has a light-transmitting aperture of 16.6 mm and a thickness of 5.5 mm; the second negative lens 3 has a light-transmitting aperture of 11.2 mm and a thickness of 1.5 mm; the third negative lens 4 has a light-transmitting aperture of 5.1 mm and a thickness of 1.5 mm; the second positive lens 5 has a light-transmitting aperture of 9.6 mm and a thickness of 4.1 mm; the third positive lens 6 has a light-transmitting aperture of 12.4 mm and a thickness of 5.7 mm; and the fourth negative lens 7 has a light-transmitting aperture of 11.3 mm and a thickness of 4.0 mm. This results in an underwater optical imaging system with a system focal length of 14.38 mm, an F-number of 2.0, a full field of view of 48°, and dimensions of φ24.6 × 43.35 mm. The system offers advantages such as excellent image quality, high resolution, and high cost-effectiveness.

[0020] In one embodiment, the third negative lens 4 and the second positive lens 5 form a cemented lens, and the system achieves good chromatic aberration correction through the combination of the optical materials of the two lenses.

[0021] In one embodiment, the optical imaging module of the underwater optical imaging system has a working wavelength range of 400nm~700nm, a focal length of 14.38mm, an F number of 2.0, a field of view of 48°, and a total optical length of 43.35mm. During the design process, all aberrations were corrected and balanced, giving it advantages such as excellent image quality, high resolution, and high cost performance.

[0022] In this embodiment of the invention, the optical imaging module of the underwater optical imaging system includes seven lenses, two of which are aspherical lenses, which significantly improves the imaging quality and enables clear imaging underwater.

[0023] Please refer to Figure 2 The figure shows a dot plot of the optical imaging module of the underwater optical imaging system of the present invention. It can be seen from the figure that the RMS of the imaging blur spot corresponding to each field of view is less than 14μm, indicating that the imaging quality of the lens is good.

[0024] Please refer to Figure 3 , where MTF is the optical modulation transfer function of the optical imaging module of the underwater optical imaging system of the present invention. As can be seen from the figure, the MTF of each field of view is higher than 0.2 in the spatial frequency range of 120 cycles / mm, indicating that the underwater optical imaging system has good imaging quality.

[0025] The following shows the lens data of the optical imaging module of the underwater optical imaging system. Table 1 shows the relevant optical parameters of each glass lens in the optical imaging module of the underwater optical imaging system.

[0026] Table 1 The aspherical surface formula used in this embodiment of the invention is as follows: Where z is the sag of the aspherical surface at a position of radius r along the optical axis, from the vertex of the aspherical surface; c is the paraxial curvature of the aspherical surface; and k is the conic coefficient. i is the correction coefficient of the i-th order for the aspherical surface.

[0027] Table 2 shows the coefficients of higher-order terms for each aspherical surface in this embodiment.

[0028] Table 2 The underwater optical imaging system of this invention features an optical imaging module with a focal length of 14.38mm, an F-number of 2.0, a field of view of 48°, a total optical length of 43.35mm, and a wavelength range of 400nm~700nm. It comprises seven lenses, including two aspherical lenses, significantly improving image quality and enabling clear underwater imaging. All aberrations were corrected and balanced during the design process, resulting in an optical imaging module with advantages such as a large F-number, high imaging resolution, miniaturization, and high cost-effectiveness.

[0029] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An underwater optical imaging system, comprising four parts: an optical imaging module, a photodetector module, a data storage module, and a display module, wherein the optical imaging module is characterized in that it consists of a first negative lens, a first positive lens, a second negative lens, a third negative lens, a second positive lens, a third positive lens, and a fourth negative lens arranged coaxially along the incident direction of light. The first negative lens is made of HZF1A_CDGM material, with a light transmission diameter of 24.0mm < aperture diameter < 25.0mm; The first positive lens is made of NLAF2_SCHOTT material, with a light transmission diameter of 16.0mm < aperture diameter < 17.0mm; The material of the second negative lens is K7_SCHOTT, with a light transmission diameter of 10.5mm < aperture diameter < 11.5mm; The material of the third negative lens is ZF5_CDGM, with a light transmission diameter of 4.5mm < aperture diameter < 5.5mm; The material of the second positive lens is SLAL56_OHARA, with a light transmission diameter of 9.0mm < aperture diameter < 10.0mm; The material of the third positive lens is NLAF2_SCHOTT, with a light transmission diameter of 12.0mm < aperture diameter < 13.0mm; The fourth negative lens is made of SF4_SCHOTT, with a light transmission diameter of 11.0 mm < aperture diameter < 11.5 mm; The object-side radius of curvature of the first negative lens is 17 mm, the image-side radius of curvature is 10.464 mm, the lens thickness is 5 mm, the refractive index is 1.648, and the dispersion coefficient is 33.9; the distance between the first negative lens and the first positive lens is 5.5 mm. The first positive lens has an object-side radius of curvature of 11.5046 mm, an image-side radius of curvature of 63.9217 mm, a lens thickness of 5.4643 mm, a refractive index of 1.744, and a dispersion coefficient of 44.9; the distance between the first positive lens and the second negative lens is 0.1000 mm. The second negative lens has an object-side radius of curvature of 5.5076 mm, an image-side radius of curvature of 3.2514 mm, a lens thickness of 1.5 mm, a refractive index of 1.511, and a dispersion coefficient of 60.4; the distance between the second and third negative lenses is 4.3093 mm. The third negative lens has an object-side radius of curvature of -19.119 mm, an image-side radius of curvature of 8.1381 mm, a lens thickness of 1.5 mm, a refractive index of 1.74, and a dispersion coefficient of 28.

2. The second positive lens has an object-side radius of curvature of 8.1381 mm, an image-side radius of curvature of -12.9412 mm, a lens thickness of 4.098 mm, a refractive index of 1.678, and a dispersion coefficient of 50.7; among which, The third negative lens and the second positive lens form a cemented lens; the distance between the second positive lens and the third positive lens is 0.1000mm; The object-side radius of curvature of the third positive lens is 14.5628 mm, the image-side radius of curvature is -13.7078 mm, the lens thickness is 5.7319 mm, the refractive index is 1.744, the dispersion coefficient is 44.9, and the distance between the third positive lens and the fourth negative lens is 0.1000 mm. The fourth negative lens has an object-side radius of curvature of 52.2414 mm, an image-side radius of curvature of 11.9892 mm, a lens thickness of 3.9462 mm, a refractive index of 1.755, and a dispersion coefficient of 27.

6.

2. The underwater optical imaging system as described in claim 1, wherein the optical imaging module is characterized in that: The aperture of the first negative lens is 24.6 mm; The aperture of the first positive lens is 16.6 mm; The aperture of the second negative lens is 11.2 mm; The aperture of the third negative lens is 5.1 mm; The aperture of the second positive lens is 9.6 mm; The aperture of the third positive lens is 12.4 mm; The aperture of the fourth negative lens is 11.3 mm.

3. The underwater optical imaging system as described in claim 1, wherein the optical imaging module is characterized in that the distance between the center of the light emitting surface of the fourth negative lens and the image plane is 6.0 mm.

4. The underwater optical imaging system as described in claim 1, wherein the optical imaging module is characterized in that: the optical dimensions of the optical imaging module are φ24.6×43.35mm.

5. The underwater optical imaging system as described in claim 1, wherein the optical imaging module is characterized in that: the system focal length of the optical imaging module is 14.38 mm and the F number is 2.

0.

6. The underwater optical imaging system as described in claim 1, wherein the optical imaging module is characterized in that: the working wavelength range of the optical imaging module is 400nm~700nm.

7. The underwater optical imaging system as described in claim 1, wherein the optical imaging module is characterized in that: the full field of view of the optical imaging module is 48°.

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