LENSES

These are the lenses of the simplest shape: flat on the one side, spherical on the other side. These lenses are widely used in telescopes, microscopes, collimators, optical transmitters, spoils and many other optical systems.

All the biconvex lenses are symmetrical, with the same radius of curvature on both sides. They are recommended for virtual imaging of real objects. Since both sides of the lens have influence on its power, it has a shorter focal length than plano-convex lens of equal diameter and surface radius.

These lenses are thicker at the edge than in the centre and flat on one side. Plano-concave lenses are used in beam expansion systems and for increasing the focal length of optical systems.

Cylindrical lenses change the light beam only in one direction. There are plano-convex lenses of positive focal length and a plano-concave ones with negative values of focal lengths.

Achromat doublets are permanently coupled two lenses - focusing and dispersing - made of different types of glass and having different  dispersion coefficients. This allows chromatic aberration correction for the light of two specific wavelengths and a substantial improvement for the other wavelengths.