Full field tomography using interference fringes casting of a non spatially-coherent extended spectrally modulated broadband light source

Abstract

A method for full field tomographic measurements using a fully non spatially-coherent extended broadband light source and a common path interferometry is described. A layered object’s is being tomographed by acquiring multiple images of the object while modulating the spectrum of the extended broadband light source. In order to overcome the non spatially-coherence of the light source, interference fringes are created by amplitude division interferometry at a focal plane of the illuminating optical system and are casted on the measured object. In addition, due to exploiting one of the object’s layers as a reference layer for the interference the need for an auxiliary reference beam is avoided and inherent Full Field “en-face” common path interferometry measurements are obtained. Another advantage is that by using spectrally modulated broadband illumination and obviating the reference beam, the requirement that the object should be used as one of the interferometer arms as in common dual beam interferometry is also avoided. This enables to relay the spectrally modulated light to illuminate the measured object which is just being imaged using a simplified imaging system while modulating the light. However, since there is no reference arm, the tomography of the object is calculated by a complex iterative algorithm where some knowledge on the object’s structure is required.