A Laser-Based High Optical Density Absorption Spectrometer

As lasers become increasingly employed in military applications, demands for improved protective optical filters will escalate. To ensure adequate eye and sensor protection, it will be increasingly important to accurately quantify high optical densities over the area of laser attenuating goggles, visors and other components. A current lamp-based spectrophotometer will not be sufficient for precise measurement of optical densities up to 6 absorbance units (A.U.) with the necessary wavelength resolution. Instead, a laser-based system coupled to a custom spectrograph capable of high stray light rejection will be required. Another issue for laser attenuating materials is the need to consider polarization sensitivity, due to the intense polarization of a laser beam. We propose to develop a laser-based system capable of accurate and precise measurements to >6 A.U. over a range of 190-1680 nm with 6 A.U. over the 200 nm-1.2 um range. This spectrograph will have a resolution of <1 nm and will be capable of providing polarization specific information. The Phase II program will implement the laser source capable of the desired range and will deliver a laser-based spectrophotometer system to Brooks Air Force Base.