Light behaves like a wave; as wavelength changes, we feel different colors. For example, the tree appears green to our eyes because they mostly reflect green wavelengths. Many things change when wavelength changes, such as the infrared images captured in visible lights to long infrared rays that have long wavelengths. Infrared images look different From visible light images. Long infrared images capture images through thermal radiation, unlike visible images that capture the reflected light.
Use of SWIR imaging
On the other hand, short infrared images look somewhat the same as visible light images. Short wavelength infrared is known as SWIR. The SWIR images like water and sugar look different from the images under visible lights. SWIR image Sensors can be used for many applications. These image sensors can capture both visible and short wavelength infrared bands.
There are many SWIR imaging applications, including water visualization, foreign material visualization, transmission observation, and temperature observation. In SWIR images, wet areas look dark. As we know that water absorbs light at wavelength 1450 nanometers reflection is less in those areas due to which light reaches near image sensors.
Using SWIR sensors, oil and water can be easily distinguished. Material looking similarly in visible lights can be distinguished in the SWIR image sensor due to differences in reflectivity, which helps inspect foreign materials.