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Optical domes for underwater photography

Jun. 12, 2020

Underwater photography is an indispensable method for marine research and development, and the production of films. However, due to the characteristics of light in the water and the particularity of the operating environment, glass domes are more and more widely used in underwater optical systems. CLZ Precision Optics Co., Ltd. is a professional manufacturer of optical glass domes. We can produce and custom glass domes for your applications.

Compared with flat optical windows, what are the advantages of glass domes?

If a optical flat parallel transparent window is used to seal and waterproof, the angle of view of the objective lens becomes smaller (the focal length increases). The magnification decreases and the aberration also changes. The chromatic aberration and distortion increase significantly, which affects the imaging quality and produce images. The clarity is reduced. Glass domes can improve some defects caused by the refraction of the water medium and increase the curvature of the image plane of the objective lens.

How to select optical materials suitable for underwater environment?

v High pressure resistance: Underwater optical systems must resist a certain hydrostatic pressure during operation. So that the system can resist the hydrostatic pressure of the working environment without damage during operation.

v Corrosion resistance: due to elements in water, temperature, oxygen content, salt content and other factors, underwater environment corrodes the material.

Therefore, the selection of optical materials for use in the underwater environment requires consideration of pressure resistance and corrosion resistance, such as BK7, quartz, sapphire, etc.

How effects the underwater environment the imaging?

1. Water scatters light

Substances and microorganisms suspended in the water cause the water to scatter light. The light encountered obstacles in the transmission process, which caused the attenuation of the light, changed the imaging distance, made it difficult to take images, and affected the quality of imaging. Under water, the object distance of the lens is about 75% of the original object distance.

2. The absorption of light in water

The absorption of light by water can attenuate the intensity of light by 4% per meter.

3. The difference of refractive index in water and air

The light of the underwater target refracts, when passing through the water-interface of glass window-air, which brings disadvantageous factors such as focus error, viewing angle deviation, distortion and chromatic aberration to the underwater optical imaging system. Due to various factors such as water depth and salt content, the refractive index of water changes, which affects the imaging quality.

4. The change of temperature

Due to the large temperature difference between the water surface and the water, the water in the underwater system is easily condensed to form water vapor, which affects the imaging quality.

Optical glass domes are wear resisting and scratch resistant. The optical glass used is overpressure resistant and corrosion resistant. The structure of optical domes effectively corrects the imaging effect. The shape of the glass dome increases the width of the field of view and reduces internal reflection. It helps to correct the aberrations generated when the light passes through the two media. Glass domes also obtain images that cannot be captured by glass windows.

With years of production experience, CLZ Precision Optics Co., Ltd. provides you with glass domes. The material can be BK7, quartz, sapphire and other optical materials suitable for underwater environments. Aluminum coating and other optical coatings can be applied to the inside and outside of the glass domes to reduce aberrations. In addition, we also provide spherical lenses, such as plano-concave lenses, plano-convex lenses, biconcave lenses, biconvex lenses and achromatic lenses, which are used in conjunction with optical domes. If you have any questions or needs, please contact