Nitrogen (N2) is a diatomic gas that makes up approximately 78% of the Earth's atmosphere by volume. It is a colorless, odorless, and tasteless gas that is largely inert under standard conditions, resulting in its use as an unreactive blanket in many industrial applications. In the context of optics, nitrogen is commonly used as a purge gas to displace air and prevent condensation or contamination in high-power laser systems, optical instruments, and other sensitive equipment. Liquid nitrogen, which is nitrogen in its cryogenic liquid state, is employed as a coolant for infrared detectors and other electronic components. Its transparency in the visible and infrared regions makes it an ideal medium for certain optical experiments and applications.