Axicon Lens

An axicon lens is a special type of lens that has a flat surface and a conical surface. The conical surface has an angle called the apex angle. An axicon lens can change a laser beam into a ring-shaped beam of light or a beam with a Bessel intensity profile. A Bessel beam is a beam that does not spread out or diffract as it travels. It looks like a series of rings of light that are equal in brightness.

Some devices that use Bessel beams are:

• Light sheet fluorescence microscopy: This is a technique that uses a thin sheet of light to illuminate a slice of a biological sample and produce high-resolution images. Bessel beams can create a light sheet that has a uniform thickness and intensity over a large area and can penetrate deeper into the sample than Gaussian beams.
• Optical tweezers: These are devices that use focused laser beams to trap and manipulate microscopic particles or cells. Bessel beams can trap long thin objects, such as bacteria or DNA strands, along their entire length and move them without losing contact
• Laser glass cutting: This is a process that uses a laser beam to cut or drill glass materials. Bessel beams can create precise holes or cuts with smooth edges and minimal heat damage.
• Optical coherence tomography: This is a technique that uses low-coherence light to produce cross-sectional images of biological tissues. Bessel beams can improve the image quality and resolution by reducing the scattering and speckle effects of the tissue
• Superresolution microscopy: This is a technique that uses special methods to overcome the diffraction limit and produce images with higher resolution than conventional microscopy. Bessel beams can enhance the superresolution effect by creating smaller focal spots and reducing background noise.