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Proceedings ArticleDOI

Multi-functional diffractive optical elements

25 Sep 2014-Proceedings of SPIE (International Society for Optics and Photonics)-Vol. 9194, pp 106-114
TL;DR: In this article, two different techniques of fabrication of composite elements are studied and a comparison of the beams generated in both cases is presented, and two different methods of composite element fabrication are compared.
Abstract: Diffractive optics has traditionally been used to transform a parallel beam of light into a pattern with a desired phase and intensity distribution. One of the advantages of using diffractive optics is the fact that multiple functions can be integrated into one element. Although, in theory several functions can be combined, the efficiency reduces with each added function. Also, depending on the nature of each function, feature sizes could get finer. Optical lithography with its 1 μm limit becomes inadequate for fabrication and sophisticated tools such as e-beam lithography and focused ion beam milling are required. In this paper, two different techniques of fabrication of composite elements are studied. A comparison of the beams generated in both cases is presented.
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Proceedings ArticleDOI
19 Feb 2015
TL;DR: In this paper, a toric Fresnel zone lens and composite elements were fabricated using electron beam direct writing for the generation of focused ring patterns, with the toric lens out-performing the other elements in several areas such as efficiency, focal depth, and ring thickness.
Abstract: Focused ring patterns are used for many applications like corneal surgery, micro drilling, optical trapping, etc. The generation of focused ring patterns in the earlier reported cases employed many refractive optical components with different functions. As a result the optics configurations of the ring pattern generation systems are bulkier. In diffractive optics, it is possible to alter a function of an element and also integrate multiple functions in a single element. In this paper, we present the design, fabrication and evaluation of single and composite diffractive optical elements for the generation of focused ring patterns. A diffractive toric Fresnel zone lens was designed for parallel beam illumination. This element is compared with other composite diffractive elements capable of generating focused ring patterns. The toric Fresnel zone lens and composite elements were fabricated using electron beam direct writing. The fabricated elements were found to exhibit interesting properties, with the toric lens out-performing the other elements in several areas such as efficiency, focal depth, and ring thickness.

3 citations


Cites background or methods from "Multi-functional diffractive optica..."

  • ...In the earlier descriptions [6-8], 1/e(2) thickness of the focused ring was considered....

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  • ...Two schemes for combining the functions of an axicon and an FZL have been studied earlier [5-8]....

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  • ...In this case, the functions of the two elements are combined by shifting the location of zones of an FZL with respect to the phase value of a refractive axicon [8, 9]....

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  • ...The performances of the rf-FZL and conical FZL have been reported earlier [8]....

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Proceedings ArticleDOI
TL;DR: In this article, a multifunctional Diffractive Optical Element (DOE) containing the functions of a SPP, axicon and a Fresnel Zone Lens (FZL) was proposed to generate higher efficiency higher order Bessel-like beams with a reduced focal depth.
Abstract: Higher Order Bessel Beams (HOBBs) have many useful applications in optical trapping experiments. The generation of HOBBs is achieved by illuminating an axicon by a Laguerre-Gaussian beam generated by a spiral phase plate. It can also be generated by a Holographic Optical Element (HOE) containing the functions of the Spiral Phase Plate (SPP) and an axicon. However the HOBB’s large focal depth reduces the intensity at each plane. In this paper, we propose a multifunctional Diffractive Optical Element (DOE) containing the functions of a SPP, axicon and a Fresnel Zone Lens (FZL) to generate higher efficiency higher order Bessel-like-beams with a reduced focal depth. The functions of a SPP and a FZL were combined by shifting the location of zones of FZL in a spiral fashion. The resulting element is combined with an axicon by modulo-2π phase addition technique. The final composite element contains the functions of SPP, FZL and axicon. The elements were designed with different topological charges and fabricated using electron beam direct writing. The elements were tested and the generation of a higher order Bessel-like-beams is confirmed. Besides, the elements also generated high quality donut beams at two planes equidistant from the focal plane of the FZL.