Precise Spherical concave mirrors for the locking imaging – Optical Surfaces is a leading manufacturer of high-precision mirrors for the locking imaging. In general, the fluctuation of optical density is considered in the case of sludge photography and then conclusions are drawn about liquids and gases. The most important applications in technology are the visualization of airflow turbulence, explosion shock waves, gas leaks and the visualization of transparent thermal phenomena, such as convection.