Of or relating to the range of invisible radiation wavelengths from about750 nanometers, just longer than red in the visible spectrum, to1 millimeter, on the border of the microwave region.

• 红外线的一种波长在750毫微米（比可见光谱中的红光稍长）与1毫米（在微波波长的边缘）之间的不可见辐射的，或与其有关的