Interferometric Synthetic Aperture Microscopy (ISAM) Using Partially Coherent Light Source


Interferometric Synthetic Aperture Microscopy (ISAM) is a method of tomographic optical microscopy that brings the power of computed imaging and inverse scattering together with interferometric broadband optical imaging. ISAM provides an extended three-dimensional resolution of objects, including regions away from the focus of the objective, and quantitative estimation of the inhomogeneities in refractive index or susceptibility of an object. Using a scanned beam in regular ISAM may have disadvantages, because, for very fast phenomena, the beam may not scan fast enough. While fully coherent ISAM provides the ability to take pictures in three-dimensional volumes in a fraction of a section, it is difficult to use in highly scattering samples. By decreasing the coherence one can reduce the multiple scattering component; however, the solution for the partially coherent ISAM case is different and therefore needs a separate derivation to find the mathematical relationship between object structure and data.

This invention is full-field optical coherence tomographic microscopy with a source of varying spatial coherence.


The illumination system consists of a spatially incoherent source (e.g. filament of an incandescent light bulb), an iris to vary the apparent size of the source, and a collimation lens to collimate the source illumination. This system produces an adjustable partially coherent illumination at the source field plane.

Data is acquired by tuning the wavelength of the source over a particular bandwidth while recording the intensity of interferograms on the focal plane array. A linear solution for the inverse scattering problem for partially coherent illumination is derived by computational models.


  • Tumor analysis
  • Evaluation of surface topography
  • Fluorescent microscopy
  • Ideal for bench-top microscope-based systems


  • Extended three-dimensional resolution
  • Adjustable partially coherent illumination
  • Fixes sample scatter and optics issues
  • Less expensive as it does not require a separate reference telescope to relay the reference field