Unlike a conventional spherical lens, a "cylinder lens" has curvature along only one axis. The figure shows an example of a plano-convex cylindrical lens, which brings parallel rays to a line focus.
A primary application of cylinder lenses is “beam shaping.” A beam's "shape" refers to the brightness of the beam's cross section perpendicular to the beam's direction of travel. Cylinder lenses enable designers to adjust the focal length along each axis independently. Because of this, a pair of cylindrical lenses with different focal lengths can be as effective as a much more expensive aspheric lens.
The following are three examples for which cylinder lenses are best suited.
- Line generators:A primary application of cylinder lenses is expanding a beam of light into a two-dimensional "fan" shape. The fan creates a line when it illuminates an object. Barcode scanners and laser levels are examples of instruments that use cylinder lenses as line generators.
- Side-emitting diode laser collimators:Side-emitting diode lasers have a rectangular aperture. Because of this asymmetry, the emitted beam is astigmatic, meaning that the beam expands at different rates along the horizontal and vertical axes. Because a cylindrical lens focuses light along only one axis, such a lens can correct the mismatched focal lengths, yielding a circularly symmetric beam.
- Anamorphic illumination:When illuminating a rectangular region, It is wasteful to simply block out the unwanted light from a circular beam. A pair of crossed cylindrical lenses in sequence can create a region of rectangular illumination with less loss of light. Rectangular illumination of this type has found application in street lighting.
These examples show some instances for which cylindrical lenses can create aspheric behavior without the expense of an aspheric lens. Clever use of cylindrical lenses can significantly reduce the cost of an optical system while improving performance. Ross offers a range of difficult-to-find cylinder optics, and our optical engineers can help you make the best choices for your design. We also have the capacity to custom-fabricate cylinder lenses.
Give us a call at 1-800-880-5417 to talk to one of our engineers about your project and learn how we can help make it successful.
Optical Design Secrets: A Ten Point Checklist for Expert Optical Design
Our checklist outlines a design process that ensures that every optical system you create meets performance specifications and is delivered on time and under budget.
Download the tip sheet to learn more!