Abstract

The interferometric measurement at different, well-known optical wavelengths allows the generation of new synthetic wavelengths, which are much longer than the optical wavelengths. For two wavelengths λ₁ and λ₂, one obtains the synthetic wavelength Λ = λ₁λ₂/|λ₁–λ₂|. This method thus allows to increase the range of unambiguity for interferometry and to reduce the sensitivity of the measurement.¹ In order to obtain this new, synthetic wavelength, the different optical wavelengths (which do not interfere) have to be interrelated. Real-time electronic signal processing is mandatory for practical applications.

© 1994 IEEE