Abstract
Distinction between spatial and temporal coherence characteristics of the interferogram from low-coherence microscopic systems is investigated. It is shown that the coherence region is determined by the temporal coherence only when the path length difference is scanned in a region where the reference and sample beams are collimated, that is, containing a single spatial frequency. Spatial coherence has an effect when the path length scan is performed with a non-collimated beam, such as a defocus scan of a lens where the focal depth of the lens mainly determines the coherence region. In the latter case, the fringe size for a monochromatic light is smaller than half the wavelength by a factor determined by the spatial coherence. A new analytic relation is derived for the fringe size showing that it has better validity than the Ingelstam relation in the high NA region.
Original language | English |
---|---|
Article number | 004 |
Pages (from-to) | 952-958 |
Number of pages | 7 |
Journal | Journal of Optics A: Pure and Applied Optics |
Volume | 8 |
Issue number | 11 |
DOIs | |
State | Published - 1 Nov 2006 |
Keywords
- Coherence
- Interference microscopy
- Optical coherence tomography
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics