Circular Variable Filters (CVF) at CI, progress and new performance

Abstract

As presented in September 2010 in Toulouse CI Systems has been developing the technology to produce Circular Variable Filters (CVF) production. These filters are used as monochromators of medium spectral resolution in radiometric and spectroradiometric instrumentation for spectroscopic and remote sensing applications in the laboratory and in the field. As mentioned then, OCLI, the original US company that developed the old CVF technology, stopped production in the ‘90’s and CI started to reconstruct the technology in 2009. The first results of CVF performance following this new work were presented in the wavelength region of 1.3 to 2.5 microns in 2010. Since then we made significant progress and completed the development of segments from the visible range up to 14.3 microns, with a spectral resolution in the range of 0.5% to 2% of the peak wavelength. The advantage of the new production method is that both the so called “tooling factor” and the peak wavelength profile along the circumference are controlled by software instead of by fixed hardware gear ratios, yielding higher design flexibility. A new CVF model in the 7.7 to 12.6 micron range with the highest spectral resolution (0.5% FWHM) ever being produced has also been developed.