PicoMove:

A PIC Interferometer for picometric displacement/vibration measurements

Principle:

An interferences area is created thanks to a Michelson-like interferometer. Two Pi/2-phase shifted optical ports allow determining both amplitude and direction of the mirror displacement.

Optical integration:

All the optical functions are monolithically integrated on a compact glass chip thanks to Teem Photonics proprietary ion-exchange technology.

The optical chip integrates two power splitters, two tap couplers, and a 2x2 multimode interferometer. All these functions are linked via singlemode waveguides.

The multimode interferometer has been designed to create a perfect Pi/2 phase difference between two output waveguides in order to maximise the sensitivity of the displacement measurement. Taps allow evaluating optical powers in both input-arm and measurement-arm. The splitters coupling-ratios have been selected to optimise the interferometer contrast.

Packaging and optical ports:

 

The optical ports are:

• One fibered input* (PM) for laser injection,
• One collimated beam** to be reflected on the moving object (measurement arm),
• Four fibered outputs*: two pi/2-phase shifted measurement ports to determine both amplitude and direction of the mirror displacement and two reference ports to optimize the interferences contrast.

* These ports are reliably fibered to the glass chip with fibres array units

** The collimated beam is obtained thanks to a selfoc lens

Our interferometer chip is protected in a compact package with dimensions as small as 59 x 26 x 8.5 mm. This package is standard made of aluminium-alloy, or made of INVAR^TM for thermally sensitive applications.

Performances:

Detection system:

The optical sensor can be remotely installed thanks to low loss optical fibres. The detection system is available in two options. The first integrates four low-noise photodetectors and their pre-amplifiers. The second integrates the photodetectors and the amplifiers with the laser source, the digital acquisition board and the associated software. USB link allows for connexion to a computer.

Applications:

 

•    Optical transducer for vibration measurement (seismometer, geophone, sound meter…)
•    Sub-nanometer displacements sensor (AFM cantilever sensing, nanopositioner stage…)

If you need more information or more detailed assistance, please contact us.

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