Measuring device and method for measuring parameters of a piezoelectric crystal onto which a thin film of material is deposited as well as thin-film deposition systems with such a device and a method for controlling such systems

A measuring device for measuring one or more parameters of a piezoelectric crystal onto which a thin film of material is deposited, comprising:

• said piezoelectric crystal with two spaced-apart electrodes, onto which crystal said film of material is deposited,;
• a frequency generator adapted to generate an oscillator signal at a specified output frequency;
• a measuring amplifier adapted to apply said oscillator signal as a drive signal to one of said electrodes of said crystal and to provide a crystal output signal in response to said drive signal;
• a quadrature demodulator adapted to down convert said crystal output signal and to provide an in-phase output signal and a quadrature output signal;
• a computation unit adapted to determine one or more parameters of said crystal based on said in-phase output signal and said quadrature output signal when said film of material is deposited on said crystal, based on said in-phase output signal and said quadrature output signal;
• and
• a compensation unit adapted to numerically compensate an effect of a parallel admittance.