Near Infrared: 2.0 to 2.4: Wavelength (micrometres): K band: Most major optical telescopes and most dedicated infrared telescopes Source Wikipedia
Many optical telescopes, such as those at Keck Observatory, operate effectively in the near infrared as well as at visible wavelengths. Source Wikipedia
For this reason, the near infrared region of the spectrum is commonly incorporated as part of the "optical" spectrum, along with the near ultraviolet. Source Wikipedia
Infrared radiation with wavelengths just longer than visible light, known as near-infrared, behaves in a very similar way to visible light, and can be detected using similar solid state devices ... Source Wikipedia
