High Resolving Power Volume Diffractive Gratings for 400-2700 nm Spectral Range, Phase II

The main purpose of this NASA SBIR Phase II proposal is development of a novel type of high resolving power diffraction gratings based on volume Bragg gratings technology. The key innovation, which was used for creation of these gratings, is based on patented technology of production of high efficiency volume diffractive elements in photo-thermo-refractive (PTR) glass on which OptiGrate has an exclusive license from the University of Central Florida. The significance of the innovation is that volume diffractive gratings in PTR glass have diffraction efficiency more than 95% and resolving power up to 20,000 in spectral range from 400 to 2700 nm. These gratings have 25 mm-long standard aperture with possibility to increase it up to 50 mm with the spectral resolution less than 50 pm. This, to the best of our knowledge, exceeds parameters of all comparable gratings worldwide. Moreover, as a result of Phase I project performance, a combination of high resolution Bragg grating with Fabri-Perot etalon provides additional increasing of spectral selectivity and enables the further increasing of spectral resolution power. This approach will be used for development of narrow band filters for detection of O2 (766 nm), H2O (935 nm), CO2 (1571 nm) and CH4 (1650 nm) with spectral width well below 1 nm (100 -- 200 pm), aperture 25 mm, throughput exceeding 90% in both reflecting and transmitting geometries. An additional task in Phase II would be a development of a scanning technology within a narrow line about 100 pm with resolution in the range from 1 to 10 pm. Aperture 25 mm, selected radiation should be focused to a photoreceiver of about 200 um. More »