Plano-convex lenses are useful for a wide range of applications. These lenses are manufactured from BK7A grade A (or customer design) optical glass and are supplied uncoated. Anti-reflection coatings are available as listed earlier in this section. To order an anti-reflection coated lens simply append the wavelength in nanometers to the product number. These lenses may also be used as mirror blanks if a convex surface mirror is required. When used to focus a collimated beam, the light should be incident on the curved surface of the lens. These plano-convex lenses may be combined with other lenses to form compex imaging systems.