Invisible material refers to a material that can reduce or eliminate the reflection of light on the surface of an object, making it invisible or reducing its visibility. The principles of commonly used stealth materials currently include the following:

The principle of refractive index control: By utilizing the difference between the refractive index of the material and the refractive index of the surrounding medium, the angle of reflection of light passing through the material changes, thereby achieving the effect of hiding objects.

Absorption principle: By utilizing the characteristics of specific materials absorbing light of a specific wavelength, the light on the surface of the object is completely absorbed, making the surface appear black or similar to the color of the surrounding environment, thereby avoiding the brightness caused by reflection and achieving a certain degree of stealth effect.

Metamaterial principle: By utilizing the physical properties of metamaterials, the material exhibits a negative refractive index at certain wavelengths or a transmittance of -1 to electromagnetic waves, thereby eliminating light reflection and achieving stealth effects.

A common type of nanomaterial that can be used to manufacture stealth materials is carbon nanotubes (CNTs). Carbon nanotubes are tubular structures composed of carbon atoms, with strong conductivity and thermal conductivity, as well as high strength and toughness, exhibiting excellent mechanical and electrical properties. By utilizing the conductivity and optical properties of carbon nanotubes, stealth materials can be made to have a certain shielding and absorption effect on certain specific frequencies of light, thereby achieving stealth effects. In addition, there are other types of nanomaterials that can also be used to manufacture stealth materials, such as nanometals, gold nanoparticles, etc., but they need to be selected based on specific applications.