High throughput, compact imaging spectrometer

A novel hyperspectral imaging technique based on Fourier Transform analysis applied to a low finesse scanning Fabry-Perot (F-P) interferometer has been demonstrated in the visible and NIR regions. The technique allows the realization of a lightweight and compact instrument yet having high throughput with respect to classical instruments based on dispersive means. Experiments carried out in the visible region have demonstrated hyperspectral imaging capability with a spectral resolution of 2 nm c 532 nm and an image resolution limited by the CCD (696x512 pixel). In the NIR (0,9-1,7 μm) region a spectral resolution of 8 nm c1064nm and an image resolution limited by the CCD (320x256 pixel) has been obtained. The potentiality in spectroscopic applications like remote gas sensing has been demonstrated as well as accurate thermal imaging capabilities. Unlike classical hyperspectral instruments, based on dispersive means or on tuneable band-pass filters, the efficiency of our F-P based system is very high (about 30p of the photons collected by the objective reach the CCD) allowing much faster and/or better quality hyperspectral images. In the present experiments the speed was by far limited by the acquisition speed of the CCD sensors. Furthermore the device is very compact and is placed between the objective and the CCD of a standard imaging system: in this configuration the field of view of the instrument is only limited by the same objective that in the present system is interchangeable. Because of its roughness, compactness, lightweight and luminous efficiency, the device is a good candidate for airborne or space borne hyperspectral applications.