Unleashing the Power of Cylindrical Lenses: Applications and Design Considerations

A cylindrical lens is a type of lens with different radii along the X - axis and Y - axis. Therefore, the shape of the lens is cylindrical or semi - cylindrical, and there is image magnification only along a single optical axis. Cylindrical lenses are commonly used as laser line generators to adjust the image height, or to correct astigmatism in imaging systems.

Creating a Laser Line Generator

When using a cylindrical lens as a laser line generator, it is crucial to calculate the effective focal length (EFL) required for the application. To do this, first calculate the fan - angle (θ) using the given working distance (L) (in centimeters) and the desired line length (x):

The fan angle can also be used to determine the line length at a given working distance

Then, the effective focal length (EFL) can be calculated using the input beam radius (d2) and the following formula.

Generating a Circular Beam

Typically, laser diodes emit elliptical beams, which may not be suitable for applications requiring a parallel, circular laser source. A common method to convert an elliptical beam into a circular one is to use two cylindrical lenses. The first lens magnifies the short - axis of the laser diode, while the second lens collimates the beam. The curved surface of the lens and the short - axis of the laser diode should be oriented in such a way that the short - axis can be magnified.

For example, to convert an elliptical beam with a major axis of 4.0 mm and a minor axis of 1.0 mm into a circular beam with a diameter of 4.0 mm, the minor axis must be magnified by a factor of 4. The magnification (Mag) of the two - lens setup can be calculated by dividing the focal length of the second lens (f2) by the focal length of the first lens (f1).