Abstract: An optical filter system includes a Fabry-Perot interference filter, and a controller that controls the Fabry-Perot interference filter. The Fabry-Perot interference filter includes a first mirror portion, a second mirror portion, a first driving electrode and a first monitor electrode provided with the first mirror portion, and a second driving electrode and a second monitor electrode provided with the second mirror portion. The controller includes a control unit that calculates an electrostatic capacitance between the first mirror portion and the second mirror portion based on an alternating voltage generated between the first monitor electrode and the second monitor electrode while an alternating current is applied between the first monitor electrode and the second monitor electrode.

Abstract: Provided is a monitor device used with a Fabry-Perot interference filter having a pair of mirror parts and a pair of driving electrodes, and having a distance between the mirror parts changed in accordance with charges stored between the driving electrodes. The monitor device includes: a current application unit that applies an AC current having a frequency higher than a resonant frequency of the mirror parts across the driving electrodes; a voltage detection unit that detects a temporal development of a voltage generated between the driving electrodes during application of the AC current; a control unit that controls the AC current across the driving electrodes, based on an evaluation of a DC component of the voltage detected by the voltage detection unit; and a monitor unit that monitors the distance between the mirror parts based on an AC component of the voltage detected by the voltage detection unit.

Abstract: An optical filter system includes a Fabry-Perot interference filter, and a controller that controls the Fabry-Perot interference filter. The Fabry-Perot interference filter includes a first mirror portion, a second mirror portion, a first driving electrode and a first monitor electrode provided with the first mirror portion, and a second driving electrode and a second monitor electrode provided with the second mirror portion. The controller includes a control unit that calculates an electrostatic capacitance between the first mirror portion and the second mirror portion based on an alternating voltage generated between the first monitor electrode and the second monitor electrode while an alternating current is applied between the first monitor electrode and the second monitor electrode.