FPSensor
long range, high precision, ultra compact interferometric displacement sensor
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The FPSensor 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 +/- 0.4° on 10 cm range, thus allowing a plug-and-measure application 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 large range distance measurements or low noise vibrometry.

Finally, due to its material composition and manufacturing precision, the attoFPSensor can be used in all kind of extreme conditions such as low temperature, high magnetic field, high electric field, and ultra high vacuum.

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

Metrology has thrived at the interface between science and manufacturing and is one of the key components to satisfy the demand of modern industry to meet international quality standards and to provide traceable measurements for scientists around the world.

While laser interferometry has long been used as a standard metrology tool, there has been a technologic gap in the availability of ultra-precise miniaturized displacement sensors for the operation in harsh environments, ranging from space and aerospace applications to the operation in nuclear power plants and research labs.

attocube has closed this gap by engineering a single-fiber based sensor, smaller in size than any other interferometer on the market while offering a performance superior to most industrial sensors currently available. Based on an attocube patented technology, the attoFPSensor allows accurate displacement measurements with an accuracy of ±0.5 ppm and a resolution of up to 30 pm.

Truly miniature and non-invasive
Due to its material composition, its manufacturing precision, and miniature size, the attoFPSensor can be used in all kind of extreme conditions such as low or high temperature, high magnetic field, high electric field, or ultra high vacuum. Due to the single fiber-based design, the measurement head generates no heat, creates no strain due to excessive wire connections, and is truly non-invasive.

Multiple axes
In addition to these benefits, the attoFPSensor can be equipped with either one or three axes. Due to a proprietary technique, each axis allows a tilt of over ±0.4°, enabling plug-and-measure applicability of the sensor without the need for painstaking alignment.

Accurate
All measurements performed with the attoFP-Sensor can be traced to international length standards and are therefore truly accurate. An internal wavelength reference cell (enhanced stability option) enables tracing of measurements to standards of NIST, PTB, NIM, NRLM, and other national standards organisations worldwide.

Ultra fast
With sampling rates of up to 10 MHz, the attoFPSensor can cope with displacement feedrates as high as 1 m/s without impairing accuracy or repeatability. The high sampling rate makes the sensor also ideally suited for high-frequency, low-noise vibrometry measurements in the MHz range.

Extremely stable
Available in different configurations, the stability and repeatability of the attoFPSensor is up to 50 billionth of the sensor-sample separation, equal to 50 nm at 1 m axis length.
Parallel beam optics and a macroscopic beam diameter of 1 mm make the attoFPSensor extremely robust against environmental influences such as the presence of dust, which typically represents a serious issue for focussed beam interferometers.