- multiple wavelength interferometry
A specific form of phase shifting interferometry – commonly referred to as multiple wavelength phase shifting interferometry – this form of interferometry utilizes two short wavelengths to synthesize a third, longer equivalent wavelength to perform precise depth / length measurements. In essence, the mechanical length of an optical part is proportional to the wavelength of light used to illuminate the object. Thus, by performing the same interferometric measurement with multiple wavelengths of light, the difference in length values can generate a very accurate length measurement. By combining multiple wavelength interferometry methods with phase-shifting techniques, very powerful interference microscopes have been produced.