摘要 |
[Problem] To provide a diagnostic method for a film thickness sensor, said diagnostic method making it possible to correctly determine a service life of a crystal oscillator, and to provide a film thickness monitor. [Solution] According to one embodiment of the present invention, a diagnostic method for a film thickness sensor is a diagnostic method for a film thickness sensor (14) having a crystal oscillator (20). In the method, the crystal oscillator (20) mounted on a sensor head is oscillated, fluctuation range of change rates of oscillation frequencies of the crystal oscillator (20) is measured, and when the fluctuation range exceeds a predetermined value, it is determined that the crystal oscillator (20) cannot be used. |