Method of measuring coating using two-wavelength infrared reflectance

A method of non-destructively measuring a non-scattering coating on a metallic substrate, the method comprising:

• transmitting an infrared beam into a non-scattering phosphoric acid anodize coating on a coated metallic substrate including aluminum with a scattering surface;
• collecting total reflectance of infrared energy from the coated metallic substrate;
• integrating the collected total reflectance;
• detecting a first amount of infrared energy of the collected total reflectance at a first wavelength in a first range from around 7 μm to around 8 μm and a second amount of infrared energy of the collected total reflectance at a second wavelength in a second range from around 10.5 μm to around 12 μm;
• determining a difference between the first and second amounts of infrared energy;
• and
• determining that at least a predetermined amount of the coating is coated on the substrate when the difference between the first and second amounts of infrared energy is at least a predetermined difference.

A method of non-destructively measuring a non-scattering coating on a metallic substrate, the method comprising:

• transmitting an infrared beam into a non-scattering phosphoric acid anodize coating on a metallic substrate including aluminum with a non-specular surface;
• collecting total hemispherical reflectance of infrared energy from the coated metallic substrate;
• integrating the collected total hemispherical reflectance;
• filtering at a first wavelength in a first range from around 7 μm to around 8 μm and a second wavelength relatively greater than a roughness of the non-specular surface that is longer than the first wavelength;
• detecting a first amount of infrared energy of the collected total hemispherical reflectance at the first wavelength and a second amount of infrared energy of the collected total hemispherical reflectance at the second wavelength;
• determining a difference between the first and second amounts of infrared energy;
• and
• determining that at least a predetermined amount of the coating is coated on the substrate when the difference between the first and second amounts of infrared energy is at least a predetermined difference.