CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-138661, filed on Aug. 19, 2020; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a gas analysis device.

BACKGROUND

There is a gas analysis device that irradiates light on a sample gas and performs an analysis by utilizing the absorption by the sample gas of a portion of the energy of the irradiated light. Such a gas analysis device may include a so-called multi-reflection cell. The multi-reflection cell includes a pair of opposing mirrors and multiply reflects the light that is introduced between the pair of mirrors. By providing the pair of mirrors, the optical path length can be lengthened; therefore, the distance that the introduced light acts on the sample gas can be lengthened. Therefore, the accuracy of the analysis can be increased.

However, when the pair of mirrors are simply arranged to face each other, the structure of the gas analysis device becomes complex, and downsizing is difficult. The accuracy of the analysis can be further increased if the light can resonate between the pair of mirrors. However, in order for the light to resonate, it is necessary to set the optical path length to an integer multiple of the wavelength. Therefore, it is necessary to perform nanometer-order adjustment of the distance between the pair of mirrors; and the adjustment of the optical path length is difficult.

Therefore, it is desirable to develop a more compact gas analysis device in which the optical path length is easy to adjust.

