Dear friends,
I would like to know what is meant by a "non-optical device".I think that is something relates to infrared.Am I right??Can anybody make it clear for me?
Infra-red is still light, unless we are limiting this to visible light only. For most purposes, 'light' is electromagnetic radiation in the approximate wavelength range 1nm (hard UV) - 1000nm (far infrared). Beyond that range it becomes either X-rays or microwaves.
The following link shows the extended electromagnetic spectrum: