Optical Lenses are often categorized by their shape. Two common surface shapes are spherical and aspherical. Each offers unique characteristics that make it suitable for different use cases.

An aspherical lens is a type of lens characterized by a radius of curvature that varies from edge to center. While spherical lenses have a uniform radius of curvature at all points on the surface, aspherical lenses have a rotationally symmetric, non-spherical shape. The departure from sphericity is often so small that it is not possible to tell by eye whether a lens surface is spherical or aspherical. In some cases, however, it is clearly visible that the radius of curvature is not constant – sometimes even having an inflection or “gull wing” shape to the profile.

Manufacturing aspherical lenses can be challenging due to the complex geometry involved, but they offer enhanced functionality and can often reduce the total number of optical elements in an assembly. These features make them beneficial for a wide range of applications. 

The curvature of the aspheric lens has a major impact on the device’s performance, so it’s important to get it right. This blog will discuss the most critical considerations when designing aspherical lenses.

Design Considerations

All spherical lenses produce spherical aberration, in which light that passes through the lens farther from its center does not focus at the same distance as light that passes through the lens closer to its center. Spherical aberration causes images to be blurry if not corrected.

Adding one or more spherical lenses that produce their own offsetting spherical aberration can improve image sharpness at the cost of adding size, weight, and expense to the optical system.

A single, well-designed aspherical lens can focus light while producing zero spherical aberration. A single aspherical lens can replace two or sometimes more spherical lenses, making a smaller, lighter lens assembly with equal or better performance.  

To design an aspherical lens, an optical designer must carefully manipulate the conic constant and aspheric coefficients that determine how far the lens surface will depart from sphericity. The designer should consider how the parts will be ground and polished with CNC machinery when determining the lens’s intended shape and the tolerances on parameters such as lens profile and irregularity and on the required surface roughness.

Once the precise design has been determined, manufacturers choose and optimize techniques to produce the design while meeting all required tolerances. Factors like material properties, tool choice, and tool speeds and feed rates affect the finished properties of an optical component which in turn determine optical function and fit into the final assembly. 

Applications and Industries

Aspherical lenses can correct many of the aberrations that plague traditional spherical lenses. Aspherical lenses produce better image quality, higher resolutions, and improved efficiency in the optics, photonics, and imaging sectors. They can be found in applications including:

  • Cameras
  • Smartphones
  • Surgical equipment
  • Laser beam collimation lens
  • Military eyepieces and objective lenses
  • Network systems for optical communication
  • Pickup lenses for optical disks

Why JML?

To produce an aspherical lens that performs well in real-world applications, the designer and manufacturer must work together.  At JML Optical, the designers and the manufacturing experts all work in the same building and routinely collaborate on Design for Manufacturability and Design for Assembly. 

Our state-of-the-art CNC machinery is specifically designed to generate, grind, and polish optical lenses. The manufacturing process is designed to minimize turnaround time, document and verify quality, and maximize production volume. Our capabilities range from rapid prototyping to high-volume production.

Our services include:

  • Lens assembly optimization
  • Design performance and manufacturability assessment
  • Design assistance

If you are looking for an aspherical lens supplier that can accommodate your production needs, JML Optical is here to help. Contact us today to learn more about our offerings or to discuss your project.