Prompt gap varying optical filter, analytical instrument, optical device, and characteristic measurement method

An optical filter comprising:

• a first reflecting film that reflects a light beam and that transmits a light beam with a specific wavelength;
• a second reflecting film that is disposed so as to be opposed to the first reflecting film via a gap, that reflects a light beam and that transmits a light beam with a specific wavelength;
• a first electrode;
• a second electrode disposed so as to be opposed to the first electrode;
• and
• a voltage controller that controls an electrical potential between the first electrode and the second electrode,
• wherein when switching a wavelength of a light beam to be dispersed by switching the electrical potential between the first electrode and the second electrode, and measuring an intensity of the light beam dispersed,
• the voltage controller switches the electrical potential from a first electrical potential to a second electrical potential larger than the first electrical potential to thereby control the gap,
• a time period during which the second electrical potential is set is longer than a time period during which the first electrical potential is set,
• the voltage controller sets the electrical potential between the first electrode and the second electrode to a third electrical potential larger than the second electrical potential, and switches the electrical potential from the second electrical potential to the third electrical potential, and
• an absolute value of a difference between the second electrical potential and the third electrical potential is smaller than an absolute value of a difference between the first electrical potential and the second electrical potential.

A characteristic measurement method that measures a characteristic of a measurement object, comprising:

• (a) providing an etalon including a first substrate, a second substrate opposed to the first substrate, a first reflecting film provided to the first substrate, a second reflecting film provided to the second substrate and opposed to the first reflecting film, a first electrode provided to the first substrate, and a second electrode provided to the second substrate and opposed to the first electrode, and an optical filter device including a voltage controller that sets an electrical potential between the first electrode and the second electrode to one of a first electrical potential and a second electrical potential larger than the first electrical potential, a light receiver that receives a light beam transmitted through the etalon, and an intensity detector that measures an intensity of the light received by the light receiver;
• (b) irradiating the measurement object with a light beam;
• (c) setting, by the voltage controller, the first electrical potential, and separating a first light beam from the light beam entering the etalon after being one of transmitted through and reflected by the measuring object;
• (d) receiving the first light beam by the light receiver and measuring, by the intensity detector, a first received light intensity of the first light beam received;
• (e) setting, by the voltage controller, the second electrical potential instead of the first electrical potential, and separating a second light beam from the light beam entering the etalon after being one of transmitted through and reflected by the measuring object;
• (f) receiving the second light beam by the light receiver and measuring, by the intensity detector, a second received light intensity of the second light beam received;
• (g) setting, by the voltage controller, the electrical potential between the first electrode and the second electrode to a third electrical potential larger than the second electrical potential, and separating a third light beam from the light beam entering the etalon after being one of transmitted through and reflected by the measuring object after step (f);
• and
• (h) receiving the third light beam by the light receiver and measuring, by the intensity detector, a third received light intensity of the third light beam received, wherein
• a time period during which the second electrical potential is set in step (e) is longer than a time period during which the first electrical potential is set in step (c), and
• an absolute value of a difference between the second electrical potential and the third electrical potential is smaller than an absolute value of a difference between the first electrical potential and the second electrical potential.

An optical filter comprising:

• a first reflecting film that partially reflects light input to the first reflecting film and that partially transmits the light;
• a second reflecting film that is located opposite to the first reflecting film via a gap, that partially reflects the light input to the first reflecting film and that partially transmits the light;
• a first electrode;
• a second electrode that is located opposite to the first electrode;
• and
• a voltage controller that controls an electrical potential between the first electrode and a second electrode, wherein
• the voltage controller switches the electrical potential from a first electrical potential to a second electrical potential and switches the electrical potential from the second electrical potential to a third electrical potential, based on Formulas below, to thereby control the gap:
• V1<V2<V3;
• V2−V1>V3−V2;
• and
• T1<T2<T3;
• where V1 represents the first electrical potential, V2 represents the second electrical potential, V3 represents the third electrical potential, T1 is a time period during which the first electrical potential is set, T2 is a time period during which the second electrical potential is set, and T3 is a time period during which the third electrical potential is set.