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Moiré Diffractive Optical Elements

We have invented a novel type of varifocal lenses, the moiré diffractive optical elements (MDOEs).  They are pairs of diffractive optical elements which can act as tunable Fresnel lenses, axicons or other optical elements upon mutual rotation.

  • Bernet, S., & Ritsch-Marte, M. (2008). Adjustable refractive power from diffractive moiré elements. Applied optics, 47(21), 3722-3730.
  • Bernet, S., Harm, W., & Ritsch-Marte, M. (2013). Demonstration of focus-tunable diffractive Moiré-lenses. Optics express, 21(6), 6955-6966.
Fig. 1: : Basic principle (drawings not to scale): Two specially designed diffractive optical elements (DOEs) are placed very closely behind each other. A rotation of one element around the central axis leads to a Moiré pattern which determines the overall optical performance of the joint DOE.

Two specially designed diffractive optical elements (DOEs) are placed very closely behind each other. A rotation of one element around the central axis leads to a Moiré pattern which determines the optical properties of the joint DOE.

Optical elements with properties that are continuously adjustable by a mutual rotation include:

  • varifocal diffractive lenses
  • flat zoom lenses
  • axicons with a variable refractive power (for applications as beam couplers in fiber optics),
  • continuous phase shifters (for applications in interferometers or frequency sideband generation),
  • spiral phase plates with a variable helical index (for holographic optical tweezers to produce doughnut beams or for spiral phase contrast in optical microscopy).