First, let's understand what Infrared Radiation (IR)? Infrared is a region of the electromagnetic radiation spectrum, where the wavelength is between 700 nm to 1 mm, which is more than the wavelength of visible light and less than radio waves. The frequency of IR is in the range of 300 GHz to 400 GHz, which is higher than the frequency of microwaves, but lower than that of visible light.
IR waves are not visible to human eye unlike visible light, but can be focused, reflected, and polarized just like visible light.
IR is mostly used in wireless communication, remote controls, sensors, thermal imaging, and night vision devices, but we will focus only on IR sensors in this chapter.
IR sensors are the devices that emit or/and detect IR radiation. The working principle of any IR sensor is governed by Plank's radiation law. As per Plank's radiation law...