An IR and/or UV machine-readable optical security device ( e.g ., micro-optic security thread) that is made up of at least one IR~absorbing component with a characteristic IR signature detectable at two or more IR-wavelengths, at Ieast one UV- absorbing component with a characteristic UV signature detectable at two or more UV- wavelengths, at least one IR-absorbing component that absorbs IR light and emits light at a different invisible wavelength, at least one UV-absorbing component that absorbs UV light and emits light at a different invisible wavelength, or a combination thereof, Is provided. The IR and UV machine-readable features do not interfere with the optical effects projected by the optical material.