Rotationally tunable multi-focal diffractive moiré lenses.

Area of Science:

• Optics and Photonics
• Diffractive Optics
• Metamaterials

Background:

• Diffractive optical elements (DOEs) are crucial for manipulating light wavefronts.
• Multi-focal lenses offer advanced optical functionalities but often lack tunability.
• Moiré patterns generated by overlapping diffractive structures present unique optical properties.

Purpose of the Study:

• To demonstrate a novel multi-focal moiré zone plate with tunable optical power.
• To investigate the generation of an array of equal intensity focal spots.
• To control the axial distance between focal spots via rotational adjustment.

Main Methods:

• Cascading multi-value phase diffractive optical elements to create a moiré zone plate.
• Utilizing mutual rotation of diffractive elements to tune optical properties.
• Employing numerical simulations and experimental verification to analyze focal spot generation and spacing.

Main Results:

• Successfully formed a multi-focal moiré zone plate with tunable optical power in each diffraction order.
• Generated an array of focal spots with equal intensity and adjustable axial distances.
• Demonstrated that mutual rotation precisely controls the spacing between uniform focal spots.

Conclusions:

• The proposed cascaded diffractive optical element approach enables a rotationally tunable multi-focal moiré zone plate.
• This tunable optical element provides precise control over the generation and spacing of multiple focal spots.
• The findings have potential applications in optical trapping, microscopy, and beam shaping.