  We present spatial coherence measurements of extreme-ultraviolet light
generated using the process of high-harmonic upconversion of a femtosecond
laser. Using a phase-matched hollow-fiber geometry, the generated beam is found
to exhibit essentially full spatial coherence. The coherence of this laser-like
EUV source is demonstrated by recording Gabor holograms of small objects. This
work demonstrates the capability to do EUV holography using a tabletop
experimental setup. Such an EUV source, with low divergence and high spatial
coherence, can be used for experiments such as high-precision metrology,
inspection of optical components for EUV lithography (1), and for microscopy
and holography (2) with nanometer resolution. Furthermore, the short time
duration of the EUV radiation (a few femtoseconds) will enable EUV microscopy
and holography to be performed with ultrahigh time resolution.
