Several methods have been suggested for elliminating the twin image in in-line holography, including Franhofer holography as used in our previous work, integration over focus, integration over wavelength, integration over lateral source position and recursion methods such as Gerchberg-Saxton or Fienup (see for all refs.). Fraunhofer holography requires the Fresnel number N =, with d the object size. The integration methods depend on the fact that the real and virtual images have different dependencies on some parameter such as focus, and have proved powerful in photoemission holographic diffraction. Here we apply focus integration and recursion to low voltage, point-projection images of carbon films, and discuss the effects of inhomogeneities in the electric field which arise when the tip is very close to a fibre-shaped sample such as DNA. by embedding biomolecules in solid Xenon at 55K, and using a beam energy of about 9 volts (less than the Xenon bandgap minus the electron affinity), radiation damage to the molecule may be minimized, while the molecule is gently supported by an almost electron transparent medium.