Aspheric Lenses Collimators  With a fixed focal length is used because non-spherical lenses have a design that corrects for chromatic aberration and have good collimation of the light beam, resulting in a Gaussian distribution of energy in the output optical beam. The lens is double-sided coated with anti-reflection films to minimize surface reflection. However, the effective focal length (EFL) of aspheric lenses is closely related to wavelength, resulting in chromatic aberration. The relative position of the lens and optical fiber is precisely adjusted to ensure that the angle of the output light is within 0.5°, and standard manufacturing processes are used to ensure product stability, consistency, and good compatibility.