What are the applications of rod lenses?
Laser technology: for focusing or collimating laser beams.
Fiber optic communication: coupling optical signals in optical fibers.
Imaging systems: for imaging in devices such as endoscopes.
Sensors: for light transmission and focusing in optical sensors.

How do you distinguish between a cylindrical lens and a spherical lens?
Cylindrical Lens
Characteristics: curvature in one direction (usually cylindrical) and flat in the other.
Function: focuses or diverges light in one direction only.
Applications: laser shaping, optical scanning, linear light source focusing, etc.

Spherical Lens
Characteristics: curvature in both directions, spherical surface.
Function: focuses or disperses light uniformly in all directions.
Applications: imaging systems, microscopes, telescopes, etc.

Highly Recommended Rod Lenses from Yutai Optics:
Optical Rod Lenses
Infrared Rod Lens
UV Fused Silica Rod Lens
Sapphire Optical Rod Lens