This paper describes the principle of precise length measurements using multi-wavelength interferometry. Three different examples are given in order to demonstrate PTB’s ability in this field: 1) Measurements of absolute distances up to 10 m performed by combination of the variable wavelength interferometry with fixed wavelength interferometry using two wavelengths simultaneously, 2) a three-wa...

Over the past decade, optical interferometry has demonstrated that its combination of high resolution and high precision can make unique contributions to astrophysics. Interferometers have grown in aperture size, baseline length, number of apertures, and spectral resolution. At the same time, methods to circumvent the limitations of interferometry are being introduced. Further increases in sens...

With seismic interferometry one can retrieve the response to a virtual source inside an unknown medium, assuming there is a receiver at the position of the virtual source. In a companion paper, Broggini et al. show that for the 1D situation the requirement of having an actual receiver inside the medium can be circumvented. They show that the virtual source response can be obtained from reflecti...

Seismic interferometry can be used to construct the Green’s function between two buried receivers in the subsurface. To construct the exact Green function sources should be placed at a surface enclosing the buried receivers. In practice sources could only be placed at the surface, and spurious events are introduced in the constructed Green’s function. The origin of these spurious events are ana...

Interferometry offers an alternative to imaging of the CMB. Some systematic errors may be easier to control than in the imaging case. Adding interferometry is capable of correlating signals from a large number of antennas, more than is currently possible with traditional multiplying interferometers. Many of the technologies required for a space-based adding interferometer for CMB studies are th...

The influence of the in-plane displacement and double-aperture orientation on the slope fringe formation in double-shearing-aperture speckle interferometry is discussed in detail. The research results show that the two in-plane displacement components, one parallel to and the other perpendicular to the shearing direction, have an influence on the slope fringe formation and that the double-apert...

In this note we describe a qualitatively different approach to measure the temporal correlation functions of multiply scattered light from fluctuating dense random media. Our approach combines diffusing-wave spectroscopy with Micbelson interferometry. Among other things, the new approach should enable experimenters to perform correlation measurements on very short time scales. The method is des...

A general derivation of the multi-pion correlation function for completely chaotic source is given. Its effects on the pion multiplicity distribution, twopion interferometry are studied. A generalized multi-pion correlation function for a partially coherent source is also discussed.