Molded Plastic Aspheres

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The shaded region represents the recommended wavelength range for the uncoated acrylic. This data was measured using a 2 mm thick sample.

Zemax Files
Click on the red Document icon next to the item numbers below to access the Zemax file download. Our entire Zemax Catalog is also available.

Features

• Ø3 mm and Ø6 mm Sizes
• Focal Lengths Available from 3.00 mm to 24.00 mm
• Numerical Apertures Available from 0.10 to 0.38
• Available Uncoated or with an AR Coating for 400 - 700 nm or 650 - 1050 nm
• Substrate: Acrylic
• Excellent for use in OEM Applications
• Volume Pricing is Available by Contacting Technical Support

Aspheric lenses are designed to eliminate spherical aberration, which allows for the spot size and collimation of a monochromatic beam of light to approach the diffraction limit. The Molded Plastic Aspheric Lenses offered here are available uncoated or with an antireflection coating deposited on both sides for either the 400 - 700 nm or 650 - 1050 nm range. In addition, these aspheres are fabricated from acrylic, which is half as dense as N-BK7, making them ideal for weight-sensitive applications.

In laser diode systems, difficulties with aberration correction are compounded by the beam's high divergence angle. Since individual spherical lenses can refract light at only small angles before spherical aberration is introduced, three or four optical elements are often required to collimate laser diode light. In contrast, a single aspheric lens collimates without introducing spherical aberration. When used to collimate light, the lens should be oriented so that the side with a larger radius of curvature (i.e., the flatter surface) faces the point source.

Conversely, when coupling into fiber, it is often necessary to focus the laser light to a near-diffraction-limited spot. With single spherical elements, spherical aberration, rather than the diffraction limit, serves as the limiting factor to achieving a small spot size. The diffraction-limiting design of these aspheric lenses helps to minimize spherical aberration, allowing the focal spot size to approach the diffraction limit. For focusing applications, the lens should be oriented so that the side with a smaller radius of curvature (i.e., the more curved surface) faces the source.

To mount the Ø3 mm or Ø6 mm aspheres sold on this page, we recommend the LMR05(/M) fixed lens mount along with either the LMRA3 mounting adapter for Ø3 mm optics, or the LMRA6 mounting adapter for Ø6 mm optics.

These high-performance multilayer AR coatings have an average reflectance of less than 0.5% (per surface) across the specified wavelength ranges and provide good performance for angles of incidence (AOI) between 0° and 30° (0.5 NA). For optics intended to be used at large incident angles, consider using a custom coating optimized at a 45° angle of incidence; this custom coating is effective from 25° to 52°. The plot shown below indicates the performance of the standard coatings in this family as a function of wavelength. Broadband coatings have a typical absorption of 0.25%, which is not shown in the reflectivity plots.

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Figure 2. Lens with a rough gate vestige along its entire length (left) and along part of its length (right).

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Figure 1. Lens with a flat gate vestige along its entire length (left) and along part of its length (right).

The appearance of these lenses is expected to vary slightly from unit to unit. Due to the degating process during manufacturing, some lenses possess a gate vestige that keeps their outer diameter from being fully round. The gate vestige can be a flat cut (see Figure 1) or a rough notch (see Figure 2), extending entirely or partly along the length of the lens.

The maximum cut of the gate vestige is specified as 0.38 mm into the lens diameter (click on the red Docs icon () for more information). The gate vestige results in cosmetic differences and will not affect the specifications or performance of the lens.