The experimental setup of X-ray Talbot-Lau interferometer is similar to that of X-ray Talbot interferometer, but it uses a multislit (what is called a source grating) in front of an X-ray source to realize an array of illuminations of incoherent sources.
The use of a source grating allows us to realize X-ray phase imaging even with a normal-focus laboratory X-ray source instead of a microfocus X-ray source and makes the measurement time much shorter. Similar to X-ray Talbot interferometer, X-rays from each slit of the source grating illuminate a grating, and as a result a self-image is generated at a distance downstream of the grating. Here we assume that the number of the slits are N. If the pitch of the source grating is determined as all the self-images generated by the N slits are constructively added, then the total intensity generated downstream of the grating is N-times larger than the intensity generated by a slit (a schematic illustration is shown in Fig. 1 where N = 2). Thus, the exposure time can be reduced to 1/N of that for a slit.
We have developed medical diagnostic devices based on the Talbot-Lau interferometer for practical use in collaboration with
- KONICA MINOLTA DEDICAL & GRAPHIC, Inc.,
- Saitama Medical University,
- National Hospital Organization Nagoya Medical Center,
- University of Hyogo.
Fig. 1 Schematic illustration of constructively added self-images generated by two slits.