Circular grating, a.k.a flat axicon, is a space-variant retarder that transforms Gaussian beam into a Bessel-Gauss beam.

Circular grating | flat axicon is leading for its high damage threshold, compared to comparative devices. It has laser irradiation resistance similar to uncoated fused silica substrates.

The structure of the element is unique due to formation birefringent nanograting’s inside a bulk of fused silica glass, sensitive to the incident polarization.

Circular grating can generate both – positive and negative Bessel-Gauss zones, separately with LHCP and RHCP polarizations, as well as positive and negative zones simultaneously with linear polarization. The working regime depends only on incident polarization.

• Positive Bessel-Gauss zone
• Negative Bessel-Gauss zone
• Positive and negative Bessel-Gauss Zone
• Fast axis distribution across the element

Technical features

• Material: UVFS, IRFS
• Wavelength range: 330 nm to 2000 nm
• Min Apex angle: 176-179.9° @1030 nm
• Diffraction efficiency: up to 95%
• Element size: up to 15 mm
• Coating (optional): AR/AR coating
• Uncertainty of diameter of cone tip – ~20 µm
• LIDT | High damage threshold: 63 J/cm2 @1064 nm, 10ns; 2 J/cm2 @1030 nm, 212fs
• Transmission (no AR coating): 85% @343 nm, 92% @515 nm, 94% @1030 nm