Systems and methods are described for content-based fused off-axis illumination
direct-to-digital holography. A method includes calculating an illumination angle
with respect to an optical axis defined by a focusing lens as a function of data
representing a Fourier analyzed spatially heterodyne hologram; reflecting a reference
beam from a reference mirror at a non-normal angle; reflecting an object beam from
an object the object beam incident upon the object at the illumination angle; focusing
the reference beam and the object beam at a focal plane of a digital recorder to
from the content-based off-axis illuminated spatially heterodyne hologram including
spatially heterodyne fringes for Fourier analysis; and digitally recording the
content based off-axis illuminated spatially heterodyne hologram including spatially
heterodyne fringes for Fourier analysis.