The development of a wide-field infrared spectroscopic imaging apparatus using a bolometer camera and feasibility test for forensic examination

When the spectroscopic imaging of a 40-μm-thick polystyrene film was obtained in transmission mode via the developed apparatus, very clear spectra were recorded. In reflection mode, the spectroscopic imaging of writing pen inks on a 10 cm × 10 cm aluminum plate could also be obtained. The developed apparatus could record spectra of 240 × 320 = 76,800 points with a wavelength resolution of approximately 5 cm−1 in ca. 1 min. Considering the time required for the analysis of the interferogram, the total time was ca. 2 min. By changing the projection magnification, the size of the area to be examined could be easily modified. The measurement time was constant regardless of the size of the area. As the developed apparatus is very compact and portable, in situ observation of crime material will be possible.