Ball Lenses are commonly used to improve signal quality in fiber coupling applications, or for use in endoscopy or bar code scanning applications. Ball Lenses feature short back focal lengths to minimize the distance needed from the Ball Lens to the optical fiber.
The focal length can be calculated as the following equation:

f= Rn/2(n-1),

where n is the index of refraction and R is the radius of the ball.
At present, we just can provide uncoated ball lens.