Axicon Lens
Axicon lens, also known as a rotationally symmetric prism, is a lens that features one conical surface and one plano surface. They are commonly used to create a beam with a Bessel intensity profile or a conical, non-diverging beam. When converting a collimated beam into a ring, the plano side of the axicon should face the collimated source. Axicons may be considered as specialty lenses (conical lenses); after all, their outer shape and the typical way of mounting is similar as for lenses. Alternatively, axicons are called conical prisms. Just as other lenses, axicons are available in uncoated forms, but are often delivered with anti-reflection coatings certain spectral regions. They can be made from various optical materials; mostly, one uses common optical glasses such as fused silica.
Applications
- The unique properties of Bessel beams allow for axicon applications in a range of fields. Axicons can aid improvements in medical applications such as laser corneal surgery, in which the ring-shaped beam provides increased capability in smoothing and vaporizing the corneal tissue. With the use of a negative and positive axicon, ring diameter can be adjusted to fit the patient's and surgeon's needs by manipulating the distance between the two axicons.
- Axicons are also beneficial in optical trapping, the use of a laser to create attractive and repulsive forces to manipulate microparticles and cells.2,3 The Bessel beam region within the DOF can trap particles on planar surfaces like a microscope slide without focal drift.2 The ring generated just beyond the DOF can also be used to isolate trapped objects.
- High-power Bessel beams, such as those formed by reflective axicons, are ideal for laser materials processing applications such as nano-channel drilling in glass.
