What are the functions of Cylindrical Lens crystal

Cylindrical Lens crystal can converge or diverge light beams in a single axis. It has a wide range of applications in many industries and fields such as optical metrology, laser scanning, spectroscopy, laser diode output beam shaping, light sheet illumination microscopic imaging, and so on.

The collimated light source is formed into a line light source, which is the most extensive application of Cylindrical Lens crystal. A collimated light source with a radius of r0 is incident on a plano-concave cylindrical lens with a focal length of -f (the image is enlarged to show the beam radius in order to explain the principle more clearly). The beam will diverge at a half angle θ (θ = r0/f). At this time, it can also be approximately regarded as the divergence of the point light source at the focal point -f. At the distance z behind the lens, although the width of the line beam is still 2r0 (ignoring the divergence of the Gaussian spot), its length becomes L = 2(r0/f)(z+f).

When z is much larger than f, the beam expansion magnification is close to z/f, and the length of the line spot is also proportional to z. If you need to produce a very narrow line light source at z, you can introduce a plano-convex cylindrical lens with a focal length of z at the front or rear of the plano-concave Cylindrical Lens crystal, and place it orthogonally to the plano-concave Cylindrical Lens crystal , Thereby compressing the beam width.

For the collimation of the output beam of the diode, the output beam of the laser diode diverges in an asymmetrical form, and the collimation work is quite challenging. For example, for a diode light source with a divergence angle θ1 x θ2 = 10° x 40°, if only a standard Cylindrical Lens crystal is used, it can only be collimated in a single direction, and divergence or convergence will occur in the other direction. Cylindrical Lens crystal can be used to decompose the problem into two one-dimensional directions. By combining two orthogonal cylindrical mirrors, the two directions can be collimated at the same time.