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Select aspheres are available in bulk at a discounted price. These items come prepackaged in capsules as shown here.

Features

• Material: Optical-Grade Plastic
• Outer Diameters of 5.20 mm, 6.28 mm, and 7.40 mm Available
• Effective Focal Lengths from 3.30 mm to 18.15 mm
• Individual and Packaged Options Available

Our Plastic Aspheric Lenses, which are available uncoated or with an antireflection coating for the 400 - 700 nm range, utilize molding technology to produce all-plastic optics. Designed by Philips for high-volume applications at affordable prices, these optics are ideal for low-power applications requiring lightweight components. The surface of the aspheric lens is designed to eliminate spherical aberration, which allows for the spot size and collimation of a monochromatic beam of light to approach the diffraction limit. All our plastic aspheric lenses are available individually. Select lenses are also offered in packages of 25, 50, or 100 pieces at a discount of 16%, 33%, and 50%, respectively, over the individual lens price.

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, multiple elements are often required to collimate laser diode light. In contrast, a single aspheric lens collimates without introducing spherical aberration. When used to collimate or focus 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 diffraction limit, serves as the limiting factor to achieving such 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.

All of the plastic aspheric lenses on this page are corrected for the presence of a window, like the window in TO-type laser packages. Please see the Specs tab for details. Additionally, the side of each lens has a flat indent that provides a reference location.

• Measured as Shown in the Diagram Below
• Measured at the Design Wavelength
• As Labeled in the Diagram Below

Please note the effective focal length is determined from the back principal plane, which does not coincide with the flat surface of the lens.

The graph shows a plot of the intensity distribution of a Gaussian beam with common methods of defining the beam diameter. For Gaussian calculations the 1/e² diameter is used. The intensity of a Gaussian beam is given by:

Where I(r) is the radial intensity of the beam, I_o is the on-axis intensity, r is the radial distance, and ω is the radius of the beam where I(r) falls to 1/e². To focus collimated laser light into a single mode fiber, the 1/e² radius at the beam waist (focal point of the beam) should be equal to half the mode field diameter of the fiber. For a M² = 1 beam, select a lens with a focal length, f, determined using:

where λ is the wavelength of the light, D is the 1/e² diameter of the beam incident on the lens, and ω_o is the radius at the beam waist.