Dia.25.4mm BAF10 and SF6HT glass cemented doulet lens

Cemented doublet is glued by more than two spherical lenses, it’s also call achroamtic lens.
An achromatic lens can be defined as a lens which is made by a combination of two different types of lenses carrying different focal powers in a manner such that the images formed by the light of both the combined lenses are free from chromatic aberration or achromatism. 

• Normal size in item list be suggested for your choice 
• MgF2,VIS-NIR coating available
• Low cost, cemented design

Most commonly used and the earliest example of an achromatic lens is the achromatic doublet. An achromatic doublet is made from a pair of glasses, of which one is typically a concave and another is convex. The concave element of the doublet is composed of flint glass (with higher dispersion); the convex element, however, is made up of crown glass (with low dispersion). These two elements are placed (cemented) next to each other in such a manner that the chromatic aberration of the one element is balanced by the chromatic aberration of another. There are various types of achromatic lenses, which differ in the type of lens elements and optical properties.

Cemented doulet as picture show is cemented by a diameter 25.4mm concave spherical lens and double convex lens, used for laser apparatus.