Measuring system which applies flexible mechanical structure for measuring force or mass

Abstract

The present invention relates to a measuring system (10) for measuring force and / or mass. The measuring system (10) comprises a measuring chamber (1) comprising at least one flexible mechanical structure (8) vibrating at at least one resonant frequency fr(1, …, n); an excitation laser device (13) configured to inject an excitation / calibration monochromatic laser beam (11) of wavelength l1 and intensity frequency f1; a measurement laser device (14) configured to inject a measurement monochromatic laser beam (12) of wavelength l2; a piezoelectric element (3) together with a magnetic spring for locking the phase difference between two mutually perpendicular polarization parts of the measurement laser beam (12); and two photodiodes (16) generating a current signal containing information about the difference in optical paths of the two parts of the measurement laser beam (12) and information about the displacements / oscillations of the flexible mechanical structure (8).From the frequency spectrum of the displacement, it is possible to obtain information about the natural frequencies of oscillation fr(1, …, n). Information about the external influence on the flexible mechanical structure (8) can be obtained from the amplitude of the displacement at the excitation frequency or from the change in at least one natural mechanical frequency fr(1, …, n) of the flexible mechanical structure (8) depending on the intensity of the external influence. The displacement is read out interferometrically using the optical homodyne technique.The present invention relates to a measuring system (10) for measuring force and / or mass and a method for measuring small forces or masses by means of a measuring system (10).The measuring system (10) comprises a measuring chamber (1) comprising at least one flexible mechanical structure (8) vibrating at minimum one resonant frequency fr (1,…, n); an excitation laser device (13) configured to inject an excitation / calibration monochromatic laser beam (11) of wavelength l1 of frequency f1; a measuring laser device (14) configured to inject a measuring monochromatic laser beam (12) of wavelength l2; a piezoelectric element (3) together with a magnetic spring for locking the phase difference between two parts of mutually perpendicular polarizations of the measuring laser beam (12); and two photodiodes (16) that generate a current signal containing information about the difference of optical paths of the two parts of the measuring laser beam (12) and information about the shifts / vibrations of the flexible mechanical structure (8). From the frequency spectrum of the shift, it is possible to obtain information on the natural frequencies of oscillation fr (1,…, n).Information on the external influence on the flexible mechanical structure (8) can be obtained from the amplitude of the shift on the excitation frequency or from the change of at least one natural mechanical frequency fr (1,…, n) of the flexible mechanical structure (8) depending on the intensity of external influence. The shift reading is interferometric using the optical homodyne technique.