A collimator is an optical device for parallelizing light beams, such as converging lenses or concave mirrors.
Confocal microscopy is an optical imaging technique for generating high-resolution 3D images. Here, a laser scans multiple image planes, which are then assembled by a computer. Only the reflected light from the focal plane is detected through a pinhole. This allows very high resolutions to be achieved.
Corundum blasting is an abrasive process for surface treatment in which corundum is used as the blasting medium. This process is suitable for removing layers of rust, scale, and paint.