Views: 3 Author: Site Editor Publish Time: 2022-12-29 Origin: Site
1. Refraction of water and selection of optical system
Since the refraction of water is greater than that of air, the viewing angle of a TV camera is 1/4 narrower in water than in air. for three-quarters of the air. In order to observe the subject in a wider range, the camera of the underwater TV must choose a wide-angle lens. In addition, the lens requires as high transmittance as possible.
2. Sensitivity and camera selection
Due to the lack of brightness in the water, it is possible to compensate with artificial lighting. However, it is also very important to improve the sensitivity of the camera itself, so the selection of the camera needs to be considered. In the past, light-guided camera tubes that were easy to adjust were generally used. But it has deficiencies in image retention and sensitivity. At present, CCD cameras are mostly used. Because of their small size, lightweight, low power consumption, good reliability, no burn phenomenon, shock resistance, and wide spectral response, they are being widely used. And because there are many types, you can also choose a high-sensitivity CCD camera.
3. Consideration of video signal transmission mode (downhole camera)
The maneuverability of underwater cameras is much worse than that on land, so the transmission of video signals must be considered in many ways. The transmission of image signals usually uses coaxial cables. The bandwidth of image signals of TV cameras usually ranges from DC to several megahertz. When used at a depth of several kilometers, the high-frequency level of the signal sent by the camera should be increased. The method of high-frequency compensation is also adopted at the receiving end. No matter how deep the depth is, frequency modulation or pulse code modulation should be considered to prevent the signal from deteriorating during transmission.
