Subnanometric Michelson interferometry for seismological applications

Prototype of interferometric absolute motion sensor

“…Several methods are reported in the literature to demodulate the signals and extract the phase. In [32], the sine and cosine components are normalized, using the signal from a third photodiode. In some other techniques, the signals are derived and recombined to extract the phase.…”

Highly compact and easy-to-use optical chip interferometer with picometric performances

“…The setup has been partially described in Ref. 16 where a first version has been built and tested. This prototype, made with macroscopic optical components, demonstrates very good noise results as low as 100 fm Hz −1/2 @ 8 Hz.…”

Integrated waveguide interferometer with picometric performances

“…Its purpose was to obtain a very low noise level and a high dynamic, especially for low frequencies. The first setup has been described in [12] where a first prototype has been built and evaluated. This prototype, made with macroscopic optical components, demonstrates very good results as low as 100 fm.Hz -1/2 at 8 Hz.…”

“…Several couplers separate the beam for the two references arms and the two measurements arms (sine-cosine outputs). Details of the principle with free beams and optical components can be found in [12]. At the output, a collimating Grin lens ensures a useful range of several centimeters.…”

“…The contrast can be enhanced by suppressing the offsets with the two reference signals; it enhances the signal to noise ratio by suppressing the amplitude noise of the laser source or amplitude fluctuations due to the retro-injection perturbations caused by vibrations. By the way, the interference fringes are easily obtained with the Lissajous curve estimation [12] and finally, the output expression of the displacement is a classical one:…”