Abstract: A Fourier transform infrared spectrometer (FTIR) includes: an infrared light source; an interferometer; a semiconductor laser for position reference of a movable mirror thereof; and a computer that performs Fourier transformation to a detected signal of an infrared interference wave from a sample to calculate a spectrum based on a memorized wavelength of the semiconductor laser and a detected value of a laser interference wave by a laser detector. The computer executes a program for calculating a spectrum of a solid reference sample, interpolating the spectrum of the reference sample in a wavenumber region of a unique peak, reading out a wavenumber of the unique peak based on a data after interpolation, and updating the wavelength of the semiconductor laser used in Fourier transformation such that the read-out value of the wavenumber falls within a specific range having an original wavenumber of the unique peak as a reference.

Abstract: An infrared spectrometer includes: an openable sealed housing that houses optical components; an infrared light source that irradiates an infrared light into the housing; a dehumidifying agent that dehumidifies an inside of the housing; a thermos-hygro sensor that detects a humidity inside the housing; and a light source control apparatus that controls power supply to the infrared light source. The light source control apparatus: starts the infrared light source while limiting power supply to the infrared light source; determines presence/absence of a risk of condensation inside the sealed housing based on detected value of humidity detected while power is supplied to the infrared light source; if the risk of condensation is present, balances a rate of increase of the detected value of humidity and a rate of decrease of humidity, and at the same time, increases power supply to the infrared light source gradually.

Abstract: A multiple-reflection apparatus and a multiple-reflection cell includes: a pair of parallel plane mirrors that multiply reflects a laser light, in zigzag, which enters at a specific angle of incidence; a right-angle double mirror having two perpendicular reflection surfaces for returning the multiple-reflection light that traveled to one end between the parallel plane mirrors; and a right-angle double mirror having two perpendicular reflection surfaces for returning the multiple-reflection light that traveled from the right-angle double mirror on one end side to the other end between the parallel plane mirrors. When the two parallel mirror surfaces configuring the parallel plane mirrors are disposed to be parallel to the z-x plane of the x-y-z axial coordinate system, the two reflection surfaces configuring the right-angle double mirror are perpendicular to the x-y plane, and the laser light entering at the angle ? of incidence crosses the x-y plane at a specific angle [[?z]].