X-ray holographic microscopy of biological specimens with an electronic zooming tube

X-ray holographic microscopy of biological specimens has been performed using in-line holography with the following improvements: (i) an electronic zooming tube is utilized as a detector, and (ii) the object planes are restricted by a metal frame which is not transparent to X-rays at the wavelengths used in the present experiments. The latter modification is useful in computer reconstruction and serves as a reference area where there are no photons in the reconstructed images. This system can minimize the inclusion of errors when recording and reading out holograms compared with methods using an X-ray resist as a detector, or optical reconstruction methods. Two-dimensional images of human cells have been successfully obtained with the present system. Comparison of these images with optical images revealed a good coincidence in structure outlines but not in internal structure images. Holographic observation of HeLa cells at different wavelengths showed a wavelength dependence of the reconstructed images. Since the electronic zooming tube is applicable to a wide range of X-ray wavelengths and has a promising potential to improve its resolution, these results strongly suggest that the present system is a good candidate for the development and establishment of an X-ray holographic microscopy system.