attoFPSensor
long range, high precision, ultra compact interferometric displacement sensor
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The attoFPSensor is based on a Fabry Perot interferometer consisting of a single mode fiber and a sensing element. The compact design (6 mm long, 3 mm diameter) and the attocube-typical compatibility with extreme environments such as ultra high vacuum und very low temperature open up new possibilities and applications for interferometric measurements. From a technical point of view, the attoFPSensor has a stunning resolution of up to 30 pm (@ 100 Hz bandwidth and 75 µW laser power) even over large distances of 10 cm and more. The uniqueness of this system arises from the use of only one single fiber which is inserted into the sensor head of the high precision positioning interferometer. As the design allows for high tolerances in mirror adjustment, the time-consuming alignment procedure typical for standard interferometers can be eliminated.

The vacuum and low temperature compatibility opens up new possibilities in interferometric displacement measurements under extreme conditions.

Measure distances with a stunning picometer resolution

The attoFPSensor relies on a fiber based Fabry Perot interferometer consisting of a single-mode fiber mounted into a fiber probe and a sensing element. The space between fiber and reflecting surface is called cavity length. The reflected light is modulated in exact accordance with the cavity length.

Unlike usual Fabry Perot sensing cavities, the attoFPSensor benefits from an attocube patented technology (WO 2009/043421 A1). The laser light entering the cavity is wavelength modulated, allowing the sensor to obtain two sinusoidal alike signals in quadrature (see schematic). This extra feature not only overrules the usual Fabry- Perot blind spot limitations but also allows the sensing of displacement direction. Therefore it paves the way towards ultra high resolution displacement sensing on the overall mirror displacement range.

Moreover, by means of a special in-factory engineering technique, the fiber probe allows a tilt of over 1° on 10 cm range, thus allowing a plug-and-measure use of the sensor without the need for prior careful alignment. All these features enable easy use of the sensor for highly sensitive applications such as displacement and long range distance measurements or low noise vibrometry.

RESULTING KEY FEATURES > no blind spots > sensing of displacement direction > sub-nm resolution