In this study, we investigate the phase shift induced by Laue transmission in a perfect silicon (Si) crystal blade in detail. This 'Laue phase' was measured at two wavelengths in the vicinity of the Bragg condition within a neutron interferometer. In particular, the sensitivity of the Laue phase to the alignment of the monochromator and interferometer (rocking angle) and beam divergence has been verified. However, the influence of fundamental quantities, such as the neutron-electron scattering length on the Laue Phase is rather small. The fascinating steep phase slope of 5.5 [(220) Bragg peak] and 11.5 [(440) Bragg peak] per 0.001 arcsec deviation from the Bragg angle has been achieved. The results are analyzed using an upgraded calculation tool. Furthermore, the fabrication stages of the world's largest crystal interferometer are presented (30 x 12 cm^2). Starting from a very special design for increasing the angular resolution, the crystal orientation, cutting, fine grinding, and etching have been performed. First test measurements at the ILL show the expected interference effect. Finally, possible applications are discussed where the large area enclosed by the interfering beams can be of great value, e.g. measurements of gravity induced phase effects and high angular resolution experiments. A further interferometric experiment has been performed as well. With a vacuum chamber, we investigate the so called 'chameleon' phase. It is a candidate for dark energy. We found with our method, that the chameleon field coupling constant must be smaller than 1.9*10^7. This limit is more than one order better than the current value of 5.8*10^8.