Can a thermal imager work under the water?

Yes, a thermal camera can work under the water to a certain extent. However, there are several factors that need to be considered when using a holding thermal imager or a thermal camera phone underwater.

Firstly, it is important to note that thermal cameras primarily detect and measure the infrared radiation emitted by objects. This radiation is converted into an image that represents the temperature variations in the scene. Unlike visible light, infrared radiation can penetrate certain materials, including water, to some degree.

When it comes to using a thermal camera underwater, there are a few key considerations. The ability of a thermal camera to function underwater depends on the wavelength of the infrared radiation it detects and the transparency of water to that specific wavelength. Water has different levels of transparency to different wavelengths of light, including infrared.

In general, shorter wavelengths of infrared radiation are absorbed more quickly by water compared to longer wavelengths. This means that thermal cameras operating in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) ranges are more suitable for underwater use than those operating in the short-wave infrared (SWIR) range.

MWIR and LWIR thermal cameras can capture images underwater because water is relatively transparent to their wavelengths. However, as the depth increases, the amount of light reaching the camera decreases due to absorption and scattering by water molecules. This can result in reduced image quality and limited visibility.

Another factor to consider is the refractive index of water. When light passes from one medium to another with a different refractive index, it changes direction. This phenomenon is known as refraction. Refraction can cause distortion and blurring in images captured by a thermal camera underwater.

To mitigate these issues, specialized underwater thermal cameras are often used. These cameras are designed with features such as anti-reflection coatings on lenses and optimized sensor sensitivity for underwater conditions. They may also incorporate additional features like depth ratings and waterproof housings to protect against water damage.

It is worth noting that the performance of a thermal camera underwater can vary depending on factors such as water temperature, clarity, and the presence of suspended particles or marine life. These factors can affect the transmission of infrared radiation through water and impact the camera’s ability to detect and capture thermal images accurately.

In summary, while thermal cameras can work to some extent underwater, their performance is influenced by various factors such as the wavelength of infrared radiation, water transparency, depth, and the presence of refractive effects. Specialized underwater thermal cameras are designed to overcome these challenges and provide usable thermal imaging capabilities in underwater environments.