Fabry-perot filter, wavelength-selective infrared detector and infrared gas analyzer using the filter and detector

An infrared gas analyzer for determining concentration of a gas being measured according to output of an infrared detector, said analyzer comprising:

• a light source for emitting infrared radiation to said gas being measured;
• a wavelength selective filter for passing said infrared radiation from said light source in a wavelength selective manner;
• and
• an infrared detector for detecting infrared radiation passing through said wavelength selective filter;
• wherein said wavelength selective filter comprises a Fabry-Perot filter device comprising:
• a fixed mirror formed on a substrate;
• a movable mirror arranged opposite to said fixed mirror with a gap formed therebetween so that said movable mirror is displaced with respect to said fixed mirror by applying an external force;
• a fixed electrode formed on said fixed mirror;
• and
• a movable electrode formed on said movable mirror and arranged opposite to said fixed electrode;
• wherein
• said movable mirror is displaced by applying a potential difference across said fixed electrode and said movable electrode so that a width of said gap is varied in at least three steps, whereby at least three wavelength bands of said infrared radiation are selectively transmitted through said Fabry-Perot filter device.

A wavelength selective infrared detector comprising:

• a substrate;
• a wavelength selective filter formed on said substrate for passing infrared radiation from a light source in a wavelength selective manner;
• and
• an infrared detector formed on said substrate for detecting infrared radiation passing through said wavelength selective filter.

An infrared gas analyzer for determining concentration of a gas being measured according to output of an infrared detector, said analyzer comprising:

• a light source for emitting infrared radiation to said gas being measured;
• a wavelength selective filter for passing infrared radiation from said light source in a wavelength selective manner;
• and
• an infrared detector for detecting infrared radiation passing through said wavelength selective filter;
• wherein
• said wavelength selective filter and said infrared detector are configured using a wavelength selective infrared detector comprising:
• a substrate;
• said wavelength selective filter being formed on said substrate;
• and
• said infrared detector being formed on said substrate.

An infrared gas analyzer for determining concentration of a gas being measured according to output of an infrared detector, said analyzer comprising

• a light source for emitting infrared radiation to said gas being measured;
• a wavelength selective filter for passing infrared radiation from said light source in a wavelength selective manner;
• and
• an infrared detector for detecting infrared radiation passing through said wavelength selective filter;
• wherein
• said wavelength selective filter is formed on a first substrate;
• and
• said infrared detector is formed on a second substrate;
• wherein said first substrate and said second substrate are jointed together.

A Fabry-Perot filter device comprising:

• a fixed mirror;
• a movable mirror arranged opposite to said fixed mirror with a gap formed therebetween;
• wherein
• width of said gap is varied by displacing said movable mirror with respect to said fixed mirror;
• and wherein
• said movable mirror is formed using a multilayer optical thin film comprising at least one layer presenting tensile stress.