Demonstration of optical thickness measurement using multilayer cold neutron interferometer

We have measured the optical thickness of a phase object for the first time using multilayer cold neutron interferometer. The measured phase shift of 15.1 ± 1.9 wavelength agreed with the expected value of 17.4 ± 0.7 wavelength due to an about 600-μm-thick silicon plate. This demonstration reconfirmed that two paths in our new interferometer were completely separate, and showed its applicability into various precise measurements.