Cylindrical Lens A cylindrical lens has a cylindrical curved surface in one axis and flat in the orthogonal axis. It only refracts light in one meridian direction. Unlike spherical lenses which focus light to a point, a cylindrical lens converges or diverges incident light into a focal line. It is commonly made of optical glass or quartz and can be coated with optical films. Main types: ‑ Plano‑convex cylindrical lens (positive, converging) ‑ Biconvex cylindrical lens ‑ Plano‑concave cylindrical lens (negative, diverging) ‑ Biconcave cylindrical lens ‑ Meniscus cylindrical lens Features: Light travels straight along the cylinder axis, while being refracted in the perpendicular direction. Rotation angle is critical during assembly. Applications: laser line generation, machine vision, barcode scanning, laser‑diode beam shaping, spectrometers, astigmatism correction, light‑sheet microscopy.