Nonspecularly reflected light

Surface Finish. As well as influencing the rate of metal removal, electrolytes also affect the quality of surface finish obtained in ECM. Depending on the metal being machined, some electrolytes leave an etched finish. This finish results from the nonspecular reflection of light from crystal faces electrochemicaHy dissolved at different rates. Sodium chloride electrolyte tends to produce a kind of etched, matte finish when used for steels and nickel aHoys. A typical surface roughness average, Ra is about 1 ]lni. 

The kind of information provided by reflectance-based optical data depends on whether the measurement is specular or nonspecu-lar and on the spectral range involved. Nonspecular (scattered light) data carry Information about macroscopic, spatially resolvable extrinsic features such as pits, scratches, or particulate contamination. The characteristic dimensions of these features must be of the order of or larger than the Rayleigh length 1 - 0.6IX, where X is the wavelength of light. 

Haze affects gloss. When light enters a hazy film, it is scattered to some degree, causing some diffuse reflection. The contrast between the fractions of light reflected at specular and nonspecular angles is reduced. 

Illumination, Diffuse n Nonspecular illumination or nondirect incident light source projected onto the object of observation. Indirect or reflected rays of light are often used as diffuse sources. Also, a scattering lens over a light source will diffuse the rays to reduce specular light. 

---