Axicons for Precision Beam Shaping and Bessel Beams

Did You Know?

Unlike spherical lenses that focus to a point, an ideal refractive axicon (a conical lens) transforms a collimated Gaussian beam into an approximate Bessel beam with a long, non-diffracting focal line whose length can easily reach tens of centimeters for milliradian cone angles. The central lobe radius r0 of the Bessel beam is roughly r0 ≈ 0.61·λ/(n−1)α, so simply changing the axicon apex angle α or substrate index n provides a direct handle on line width without refocusing. A common misconception is that axicons are inherently high-loss; in practice, with proper AR coatings and alignment, throughput can rival that of conventional singlets while producing much higher depth of focus in applications like laser drilling and optical trapping.
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Frequently Asked Questions

An axicon is a conical optical element that converts an incident collimated Gaussian beam into an approximate Bessel beam with a long depth of focus. Instead of focusing light to a single point like a spherical lens, an axicon generates a narrow, quasi-nondiffracting central core surrounded by concentric rings, useful for extended line foci, drilling, and alignment applications.

What Are Axicons?

Axicons are conical optical elements designed to transform an incident beam into a non-diffracting Bessel-like beam or a ring-shaped intensity profile. Unlike spherical lenses that focus light to a point, axicons generate an extended focal line along the optical axis, making them useful for applications requiring long depth of focus and controlled beam profiles.

Typical Specifications of Axicons

On FindLight you will find axicons with a range of optical and mechanical parameters. Common specifications include:

  • Apex angle: Defines the cone geometry and determines the Bessel beam cone angle and ring radius.
  • Material: Fused silica, BK7, and UV-grade substrates for wavelength coverage from UV through NIR.
  • Coatings: AR coatings optimized for specific wavelength bands (e.g., 248 nm, 355 nm, 532 nm, 1064 nm) to minimize reflection losses.
  • Diameter and clear aperture: Sets the maximum beam size and usable numerical aperture of the axicons.
  • Surface quality and flatness: Specified as scratch-dig (e.g., 20-10, 40-20) and λ/λ4 type values for demanding laser systems.
  • Surface accuracy (cone error): Impacts Bessel beam uniformity and ring symmetry.
  • Damage threshold: Important for high-peak-power pulsed or high-average-power CW lasers.

Use Cases for Axicons

Axicons are used in laser drilling, material processing with extended depth of focus, optical trapping, microscopy, alignment systems, and metrology. They are also employed in creating hollow beams, optical vortices when combined with additional elements, and for generating long-focus beams in ophthalmic and biomedical setups.

Buyer Guidance on FindLight

When selecting axicons, compare apex angle, substrate material, wavelength-optimized coatings, and surface specifications against your laser parameters and required propagation distance. Verify input beam diameter and divergence to ensure the generated Bessel zone or ring profile matches your system geometry.

On FindLight, you can review detailed datasheets for available axicons, compare multiple products in the same view, and request quotes or technical clarification directly from suppliers with no registration required. Use the comparison and inquiry tools to specify wavelength, beam size, power level, and mechanical constraints so vendors can recommend the most appropriate axicons for your application.