Meniscus Lenses Information

Meniscus lenses are optical lenses that produce a smaller focal point and fewer aberrations than a standard plano-convex lens. Meniscus lenses have one convex and one concave surface with each surface having its Positive meniscus N-BK7 lens diagramown radius or curvature. Applications include lasers and cameras.

Types

There are two types of meniscus lenses.

Positive Meniscus: Positive meniscus lenses have a shorter radius of curvature on the convex side and a longer radius of curvature on the concave side; the edges of these lenses are thicker than the center. A positive meniscus lens can decrease the focal length of another lens while retaining the angular resolution. Meniscus lenses are used to create a tighter beam focus.

Negative Meniscus: Negative meniscus lenses have a shorter radius of curvature on the concave side and a longer radius of curvature on the convex side; the center of the lens is thicker than its edges. This type of lens is frequently used in place of other negative lenses for high-index infrared materials. They are useful for beam-expanding application, which require minimal spherical aberration.

Configurations

Meniscus lenses are commonly made of optical glass such as BK-7 (Borosilicate Glass), crown glass, flint glass, LaSFN9, and UV grade fused silica along with non-glass materials such as sapphire, polycarbonate, and zinc selenide. Meniscus lenses are generally between 9 and 38mm in diameter and are mounted using optical mounts such as lens holders.

Specifications and Features

The following specifications determine the functionality of a meniscus lens.Positive and negative meniscus lenses diagram

  • Focal Length: The Effective Focal Length is the distance from the lens that light converges. Focal lengths are positive for a converging system and negative for a diverging system.
  • Center/Edge Thickness: The thickness of the lens at its outer edges and its center axis.
  • Surface Quality: The lens surface quality describes the appearance of the lens surface. The most common way surface quality is represented is the scratch-dig specification described by the MIL-PRF-13830B standard.

These features provide additional utility or ease-of-use.

  • Antireflective Coating: An antireflective coating has been applied to the lens.
  • Laser Rated: Lens is rated to be used with lasers. Laser rated lenses are designed to work with laser's high power output without excessive degradation.
  • Mounted: The lens comes already mounted.

Images credits:

Thorlabs IncNightlase Technologies