Displacement measurement with intracavity interferometry

We present a measuring technique for displacement and position sensing over a limited range with detection of standingwave pattern inside of a passive Fabry-Perot cavity. The concept considers locking of the laser optical frequency and the length of the Fabry-Perot cavity in resonance. Fixing the length of the cavity to e.g. a highly stable mechanical reference allows to stabilize wavelength of the laser in air and thus to eliminate especially the faster fluctuations of refractive index of air due to air flow and inhomogeneities. Sensing of the interference maxima and minima within the cavity along the beam axis has been tested and proven with a low loss photoresistive photodetector based on a thin polycrystalline silicon layer. Reduction of losses was achieved thanks to a design as an optimized set of interference layers acting as an antireflection coating. The principle is demonstrated on an experimental setup.

[1]  J. Hrabina,et al.  Suppression of Air Refractive Index Variations in , 2011 .

[2]  Josef Lazar,et al.  Refractive Index Compensation in Over-Determined Interferometric Systems , 2012, Sensors.

[3]  O. Číp,et al.  Precise length etalon controlled by stabilized frequency comb , 2008 .

[4]  L J Wang,et al.  Precision measurement of the refractive index of air with frequency combs. , 2005, Optics letters.

[5]  G. Jäger,et al.  Thin transparent pin-photodiodes for length measurements , 2004 .

[6]  O. Číp,et al.  Investigation of Short-term Amplitude and Frequency Fluctuations of Lasers for Interferometry , 2013 .

[7]  H. Stiebig,et al.  Optimization of phase-sensitive transparent detector for length measurements , 2005, IEEE Transactions on Electron Devices.

[8]  Petr Klapetek,et al.  Multidimensional interferometric tool for the local probe microscopy nanometrology , 2011 .

[9]  O. Číp,et al.  Precision metrology length standard based on femtosecond stabilized laser , 2008, SPIE Photonics Europe.

[10]  Josef Lazar,et al.  Frequency Noise Properties of Lasers for Interferometry in Nanometrology , 2013, Sensors.

[11]  P. Ciddor.  Refractive index of air: new equations for the visible and near infrared. , 1996, Applied optics.

[12]  Zehuang Lu,et al.  Application of frequency combs in the measurement of the refractive index of air , 2006 .

[13]  H. Stiebig,et al.  Standing wave detection by thin transparent n–i–p diodes of amorphous silicon , 2003 .

[14]  Josef Lazar,et al.  Purity of iodine cells and optical frequency shift of iodine-stabilized He-Ne lasers , 2007 .

[15]  K. P. Birch,et al.  An Updated Edln Equation for the Refractive Index of Air , 1993 .

[16]  S. Topcu,et al.  Heterodyne refractometer and air wavelength reference at 633 nm , 2003 .

[17]  Josef Lazar,et al.  Displacement interferometry with stabilization of wavelength in air. , 2012, Optics express.

[18]  B. Edĺen.  The Refractive Index of Air , 1966 .

[19]  K. P. Birch,et al.  LETTER TO THE EDITOR: Correction to the Updated Edln Equation for the Refractive Index of Air , 1994 .

[20]  B. Mikel,et al.  Conversion of stability of femtosecond mode-locked laser to optical cavity length , 2010, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.