Patent ID: 8497990

Claim:
An optical filter comprising: a first variable wavelength bandpass filter; a second variable wavelength bandpass filter; a driver that drives each of the first and second variable wavelength bandpass filters; and a controller that variably controls a spectral band of each of the first and second variable wavelength bandpass filters, wherein the first variable wavelength bandpass filter extracts light of a first wavelength band located in a desired wavelength band and has at least the following spectral bands: a first spectral band having a central wavelength equal to a first wavelength in the first wavelength band and a second spectral band having a central wavelength equal to a second wavelength in the first wavelength band, the second variable wavelength bandpass filter extracts light of a second wavelength band located in the desired wavelength band and adjacent to the first wavelength band and has at least the following spectral bands: a third spectral band having a central wavelength equal to a third wavelength in the second wavelength band and a fourth spectral band having a central wavelength equal to a fourth wavelength in the second wavelength band, the driver drives the first and second variable wavelength bandpass filters concurrently, the period during which the first variable wavelength bandpass filter extracts the light of the first spectral band overlaps with at least part of the period during which the second variable wavelength bandpass filter extracts the light of the third spectral band, and the period during which the first variable wavelength bandpass filter extracts the light of the second spectral band overlaps with at least part of the period during which the second variable wavelength bandpass filter extracts the light of the fourth spectral band.