Defocus and numerical focusing in interference microscopy with wide time-varying spectrum of illumination field

This paper presents an analysis of the influence of illumination with wide temporal spectrum on the properties of a defocused interference signal and numerically focused imaging in interference microscopy. It is shown that the differences in defocus influence on different spectral components of a signal with wide temporal spectrum may lead to degradation of the images of defocused sample parts, in spite of the use of numerical focusing. The magnitude of these effects depends on the temporal spectrum width, the numerical aperture of the imaging system and the amount of defocus. The influence of these effects on the properties of numerically focused imaging in Fourier domain optical coherence tomography/microscopy is considered.