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The Difference Between Collimating Lens and Beam Expanding Lens and Focusing Lens

Ⅰ. A collimation lens and a beam expander are different


The collimation lens is for point light sources, which are more commonly observed in everyday life, such as match head ignition, an old torch bulb, and the energy fiber from a laser. The collimation lens is the laser that emerges from the energy transmission fiber in the industrial laser sector. In beam delivery systems, collimation lenses for CO2 lasers and infrared optics, as well as reflecting and transmissive collimation lenses, are employed to keep the beam collimated between the laser resonance cavity and the focusing optics. Copper complete reflectors are used in reflective collimation lenses, whereas zinc selenide lenses are used in transmission collimation lenses.


The diameter of the laser beam and the divergence angle, which is the angle at which the light wave spreads throughout its spatial propagation, may both be changed with beam expanders. Due to diffraction effects, even ideal light with no anomalies might experience some beam divergence. For a given beam diameter, the far-field divergence of a beam determines the optimal collimation effect. It also demonstrates that achieving zero beam divergence or the best collimation is unattainable since an infinite beam diameter is required.


Both the beam expander and the collimation lens may help improve laser focus, and they both have similarities and distinctions when it comes to collimation.


Ⅱ. A collimation lens and a focusing lens are two different types


The collimation lens is used to compress the laser's dispersion angle to accomplish parallel light transmission. Its construction and application are similar to those of a focusing lens, and it may be a single piece, multi-piece composite type, or aspheric depending on the demands. The aspheric lens, followed by the multi-piece compound, is the most effective.


The collimation lens' job is to compress the divergence angle so that parallel laser transmission can be achieved. Collimation lens characteristics include: first, high laser transmission rate, high damage threshold, can be used with a 10000W laser; second, good collimation effect, less than 1/10 wavelength; and third, high laser transmission rate, high damage threshold, can be used with a 10000W laser.


Spherical focusing mirrors are used as focusing mirrors in fiber laser optical systems; the base material is fused quartz, and both sides are coated with transmission-enhancing film; we usually recommend using a two-piece combined spherical mirror lens to reduce spherical aberration as much as possible. With a fused silica base material and a double-sided transparency enhancement coating, aspheric lenses are utilized as focusing mirrors in fiber optic laser systems. Because aspheric applications do not produce spherical aberrations in the transmitted wavefront and offer the best diffraction performance, single aspheric lenses can replace traditional multi-piece spherical lenses.

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