As applied to thin films, a coating which appears gray to the eye and has a flat absorption curve throughout the visible spectrum. Neutral density filters decrease the intensity of light without changing the relative spectral distribution of energy.
SPHERICAL VS. ASPHERIC LENSES
HOW THEY’RE USED IN IMAGING APPLICATIONS
Optical Lenses are often categorized by their shape. Two common surface shapes are spherical and aspherical. Each offers unique characteristics that make it suitable for different use cases.