Reflectance characteristics of selected materials for reference targets for 106-μm laser radars

The reflective characteristics of several materials have been examined in an effort to develop a 10.6-microm reflectivity standard for field measurements with laser radars. Measurements on twelve different target materials showed that many materials have components of diffuse reflectivity, specular reflectivity, and retroreflectivity. For each material examined, both the effective Lambertian reflectivity and the beam depolarization were determined. It was also found that because of the strong retroreflection component present with many materials, the practice of estimating the effective diffuse reflectivity from measurements of total reflectivity could lead to erroneous reflectivity values for laser radar systems. One of the preferred reference targets found for 10.6-microm field measurements was canvas tarpaulin.