Flat Axicon Lens PBA25-633-47

Overview

This Flat Axicon Lens is a planar, polarization-dependent conical (axicon) element built as a sandwich of two N-BK7 glass substrates enclosing a liquid crystal polymer (LCP) functional layer. Within the LCP layer the fast-axis orientation of the molecules follows an equal-period gradient along the radial direction, giving a uniform half-wave (λ/2) retardation across the whole aperture. Depending on the polarization state of the incident beam it produces annular (ring) focusing or divergence; under left-handed circularly polarized light it generates a Bessel beam with non-diffracting and self-healing behavior. This unit operates at 633 nm with a deflection angle of 4.7°.

Applications

• Bessel-beam generation (non-diffracting, self-healing beams)
• Optical trapping and particle manipulation
• Laser materials processing (drilling, glass cutting) with extended focal depth
• Light-sheet and extended-depth-of-field microscopy
• Annular / ring beam shaping and polarization-controlled focusing

Construction & Performance

Unlike a conventional ground axicon, this element has a flat plate form with no three-dimensional conical tip, which simplifies mounting and integration. The conical wavefront is produced by the radial, equal-period orientation of the liquid crystal molecules, enabling micron-level fabrication precision together with large dispersion. An arrow marked on the edge indicates the beam propagation direction: the side where the arrow opens is the entrance face and the side the arrow points to is the exit face. Key specifications for this model:

• Operating Wavelength: 633 nm
• Deflection Angle: 4.7°
• Clear Aperture: Ø20 mm
• Optical Component Size: Ø25.4x3.2 mm
• Substrate Material: Liquid Crystal Polymer/N-BK7 Window Plate
• Retardance: λ/2
• Center Offset: <0.5 mm
• Surface Quality (Scratch/Dig): 40/20
• Zero-Order Efficiency: <4%
• Delay Accuracy & Uniformity: ±5 nm
• Transmittance (at working wavelength): >98%
• AR Coating: Ravg<0.5% @400-700 nm
• Operating Temperature: -20 to 80 deg C
• Half-Cone Angle: 10°

Storage & Handling

Handle the element by its edges and avoid contact with the clear aperture. Keep the optical surfaces free of dust and fingerprints; when cleaning is needed, use clean optical-grade solvents and lens tissue. Observe the edge arrow for correct orientation in the beam path. Store in the original container in a clean, dry environment within the rated operating temperature range, away from direct sunlight, condensation and corrosive vapors.