Spectroscopic analysis apparatus, spectroscopic analysis method, steel strip production method, and steel strip quality assurance method

A spectroscopic analysis apparatus comprising:

• a light projecting device configured to project infrared light to a measurement target object;
• a light receiving device configured to receive, as reflected light, the infrared light reflected by a surface of the measurement target object;
• and
• an output device configured to calculate either or both of a composition and a composition ratio of the surface of the measurement target object using the reflected light received by the light receiving device, wherein
• the light receiving device includes:
• a separator configured to separate the reflected light into s-polarized light and p-polarized light;
• a detector for s-polarized light configured to detect s-polarized light obtained through the separation by the separator and output an electric signal indicating an intensity of the s-polarized light to the output device;
• and
• a detector for p-polarized light configured to detect p-polarized light obtained through the separation by the separator and output an electric signal indicating an intensity of the p-polarized light to the output device;
• and
• the output device is configured to:
• calculate an absorbance based on a ratio between the intensities of the s-polarized light and the p-polarized light using the electric signals output from the detector for s-polarized light and the detector for p-polarized light;
• and
• calculate either or both of the composition and the composition ratio of the surface of the measurement target object using an intensity of the absorbance at any desired wavenumber.