Design of diffractive axicons for partially coherent light

Area of Science:

• Optics and Photonics
• Diffractive Optics
• Coherent Beam Shaping

Background:

• Diffractive axicons are crucial optical elements for generating Bessel beams and line segments.
• Designing axicons for partially coherent illumination presents challenges due to the loss of spatial coherence.
• Existing methods often struggle to maintain desired focal properties under reduced coherence.

Purpose of the Study:

• To propose a novel design methodology for diffractive axicons tailored for spatially partially coherent illumination.
• To develop a technique that accounts for the influence of coherence on axicon performance.
• To demonstrate the generation of uniform on-axis intensity profiles for extended focal lines.

Main Methods:

• The design procedure leverages the stationary-phase method.
• A coherence-dependent differential equation is derived for the axicon phase function.
• Boundary conditions are established to guide the phase profile design.
• The method is applied to annular-aperture axicons.

Main Results:

• The proposed method successfully designs diffractive axicons for partially coherent light.
• Annular-aperture axicons were designed to generate extended focal line segments.
• Uniform on-axis intensity was achieved along these focal lines.
• The design is shown to be dependent on the degree of spatial coherence.

Conclusions:

• The novel design method provides a robust approach for creating diffractive axicons under partial coherence.
• This technique enables precise control over focal properties, such as uniform intensity distribution.
• The findings have implications for applications requiring stable line-segment generation in non-ideal illumination conditions.