LASER COMPONENTS has a large assortment of high quality lenses for laser applications. The house norm for optics with a diameter of 1.0" features a surface quality of 5/4x0.025 (scratch-dig 10^-5) and a surface figure of l/10 (i.e. 3/0.2) where l = 546 nm.

Single lenses are available with concave and convex radii as well as combinations thereof. You can choose from several thousand radii. Many lenses are inexpensive and available right away because they are in stock. Custom designs are available upon request.

The inexpensive plano-convex and plano-concave lenses are often used in laser applications. Compared to lenses with two curved surfaces, lenses with the same focal length have a higher spherical aberration. When used in laser applications, experience has shown that aberrations can be neglected on account of the small beam diameter. Therefore, the quality of plano-concave and plano-convex lenses is adequate.

Because of its excellent transmission characteristics, sapphire can be used for lenses and windows in the spectral range from UV to IR at wavelengths of up to 5 µm. The extraordinary hardness of the material makes sapphire perfect for applications in which break-proof and scratch resistant material is required. In laser technology, these lenses are often used in Er:YAG lasers that emit at 2.94 µm.

LASER COMPONENTS offers sapphire lenses of all common types in high power laser quality. New developments in processing can ensure excellent lens features that were unachievable with sapphire until now. The quality of polishing and surface figure almost matches that of fused silica lenses. The values for absorption and scattering are minimal; thus, the damage threshold of the lenses has improved considerably.

Biconconvex and biconcave lenses are used if a short focal length has to be achieved with a large lens diameter. The refractive power of the lens is achieved by the two radii of curvature rcc and rcx (see also the drawings).

Because both sides of the lens are curved, a single curvature is not as strong as in plano-concave/plano-convex lenses of the same focal length. The aberrations of the biconcave/biconvex lenses are therefore smaller, which is crucial for some applications.

Best form lenses are positive lenses with minimized spherical aberrations. They are used if the highest demands are made of the spot image.

The spherical aberration is clearly defined by the diameter of the incident beam and its wavelength. If these values are known, then the radii of curvature of the lens can be designed to create as low an aberration as possible.

Best form lenses generally have better imaging qualities than conventional positive lenses, even if they are used with other beam diameters or wavelengths than specified.

To reduce spherical aberrations, in particular at numerical apertures NA ≤ 1, aspherical lenses are mostly used.

Instead of a multiple-lens system, which corrects aberrations, a single aspherical lens is used. The advantages are apparent: power losses at the individual lens surfaces are reduced and time-consuming, costly adjustment is no longer required. Aspherical lenses are also used for collimating high-power laser diodes.

Technological Advance

The surface roughness achieved for spherical and plane surfaces can now be achieved in aspherical substrates as well. Therefore, these lenses can also be used in high power lasers.

Cylindrical lenses are used to create lines or for beam expansion in one direction. Their optical properties and aberrations correspond to those of spherical optics.

LASER COMPONENTS offers plano-concave and plano-convex cylindrical lenses in rectangular, square, and round form. Rectangular and square cylindrical lenses possess a clearly defined optical axis. Round cylindrical lenses are a bit more difficult to adjust, but can be integrated into standard lens mounts.

The product range of manufactured lenses comprises the following radii:

• Plano-convex lenses: rcx 1 mm to ∞
• Plano-concave lenses: rcc - 3 mm to ∞