Biconvex Symmetrical elements with positive focal lengths.
Plano-Convex One spherical and one flat surface, for simple imaging in non-critical applications.
Achromatic Doublets consisting of one crown and one flint element cemented together, minimize chromatic aberrations.
Cylindrical Focus light to a line that lies parallel to the cylindrical axis. Sometimes used to correct astigmatism.
Aspherical Provides maximum energy throughput over a limited path length. Not for imaging, they are ideal for collecting and/or focusing as much light as possible.
Lenses