Extension to NIR and visible ranges of high resolution relative spectral response measurement using Fourier Transform Infrared Spectrometer (FTIR) of CMOS FPAs

The accurate knowledge of IR detectors specifications becomes of higher importance whatever the application. Among these specifications is the relative spectral response. Spectral response measurement of CMOS Focal Plane Arrays is now possible either thanks to a grating-based monochromator or through an FTIR spectrometer, this later solution easily leading to a 1 cm(-1) spectral resolution whatever the wavelength. Through this method, the spectrum is calculated as the Fourier Transform of the signal of the detector. A Fast Fourier Transform algorithm (FFT) is then applied which requires a sampling frequency. Sampling points are selected at most at every zero-path difference of the interferogram of an internal He-Ne laser. Consequently, the analysis of signals with higher wavenumbers the He-Ne laser, i.e. in the visible is theoretically impossible. Our paper reminds the principle of the high resolution spectral response measurement through FTIR and presents the method to pass over the sampling limitation thus extending measurements over the visible for CMOS detectors. It also explains the drawbacks of this method: the existence of a blind range and the limitations toward UV range.