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How to design the underwater television system?

Jun. 28, 2020

The camera of the underwater television system is small in size, high in resolution and easy to control. It is often used in Remote Operated Vehicles(ROV), underwater exploration, water conservancy and hydropower projects, and offshore oil engineering. CLZ Precision Optics Co., Ltd. provides you with optical components suitable for underwater television systems, including custum optical domes, optical lenses, optical windows, etc. of various sizes and materials.

The water-sealed window is best to use an optical dome. A wide-angle lens and a correction lens might be used in underwater television systems.

In order to meet the needs of narrowing the object distance and large-area observation, wide-angle lenses are often used for camera lenses of underwater televisions. For maintaining the advantages of wide-angle lenses, it is also necessary to consider the use of correction lenses that eliminate refraction. If an ordinary camera objective lens is used, and a optical parallel flat window is used for sealing and waterproofing, due to the refraction of light at the interface between water and air, the imaging beam of underwater objects transmitted through the plane window will cause focus errors, viewing angle errors, distortion and chromatic aberration.

To overcome the above defects, the following methods can be used:

The water-tight window of the underwater television system uses a glass dome, a combination of a common photographic objective lens, a far-field focus type additional lens group and a special photographic objective lens for underwater. The structure of the glass dome is relatively simple. Its uniform structure not only resists external pressure, but also has low fluid resistance. Optical domes improve defects caused by the refraction of the aqueous medium. However, the refraction cannot be corrected completely. With optical domes, the curvature of the image plane of the objective lens increases. In the optical design, it is also necessary to ensure that the spherical center of the glass dome coincides with the entrance pupil of the imaging objective.

In addition, due to the absorption and scattering of water, the imaging beam of the object will be refracted after passing through the water-sealed optical dome to the camera. The size of the deflection depends on the direction and wavelength of the light. Moreover, due to the aberration and distortion generated by the optical dome and the absorption and scattering effects of water on the light, severe distortion may occur. Therefore, it is necessary to use underwater special imaging objective lens to compensate the distortion of some images.

The far-focus type additional lens group is used as an accessory for underwater photography, which not only maintains the performance of ordinary photographic objectives, but also meets the requirements of underwater photography. The additional lens group consists of a plano concave lens (used as a waterproof window) and a positive lens to form a far-focus system, which can completely correct distortion, chromatic aberration and other aberrations, but it is difficult to meet the needs of a large underwater field of view and large aperture. Underwater special optical lens more effectively corrects aberrations and eliminates the effects of aqueous media.

How to choose optical domes suitable for underwater applications?

Optical glass domes underwater are better to be made of quartz, BK7 and other optical materials, which the transmittance performance of light, pressure resistance and corrosion resistant are excellent.

CLZ Precision Optics Co., Ltd has many years of experience in the production of optical components. Our company provides you with custom optical components that meet your optical design and applications, such as optical domes, optical lenses, optical windows, optical mirrors, optical prisms, etc. According to the needs of optical applications and design, dielectric films or metal films can be coated for custom optical components. Looking forward to your inquiry, please contact