A diffractive optical element efficiently converts an input light beam into an output light beam having a specified cross-sectional shape. The diffractive optical element includes a plurality of partial optical elements. The plurality of partial optical elements convert the input light beam to respective partial light beams, each of which has a shape that does not correspond to the specified cross-sectional shape. The sum of the partial light beams matches the shape of the output light beam (i.e., having the specified cross-sectional shape).

Diffractive optical element, method of fabricating the element, illumination device provided with the element, projection exposure apparatus, exposure method, optical homogenizer, and method of fabricating the optical homogenizer

Multi-Aperture Beam Integration Systems

In this paper I discuss the subject of warm dense matter (WDM), which, apart from being of academic interest and relevant to inertial fusion capsules, is a subject of importance to those who wish to understand the formation and structure of planetary interiors and other astrophysical bodies. I broadly outline some key properties of WDM and go on to discuss various methods of generating samples in the laboratory using large laser facilities and outline some common techniques of diagnosis. It is not intended as a comprehensive review but rather a brief outline for scientists new to the field and those with an interest but not working in the field directly.

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Generation and characterisation of warm dense matter with intense lasers

A novel diffractive optical element, named phase zone photon sieve (PZPS), is presented. There are three kinds of phase plates in PZPSs: PZPS1, PZPS2, and PZPS3. Each of the PZPSs has its own structure and is made on quartz substrate by etching. The three PZPSs have stronger diffraction peak intensity than a photon sieve (PS) when the margin pinhole and zone line width are kept the same. The PZPS3 can produce a smaller central diffractive spot than the ordinary PS with the same number of zones on the Fresnel zone plate. We have given the design method for and the simulation of PZPS and PS. PZPS has potential applications in optical maskless lithography.

http://iopscience.iop.org/article/10.1088/1674-1056/18/1/029/pdf

Phase zone photon sieve

Tandem microlens arrays are commonly used in many applications for the beam shaping of an arbitrary input intensity distribution into a top hat. Because of the periodic structure of the regular arrays, the output intensity distribution is modulated by equidistantly located sharp intensity peaks, which reduces the homogeneity of the beam. A new concept is proposed in this paper for tandem microlens arrays incorporating a center off-axis microlens array for the generation of an intensity far-field distribution with improved homogeneity under coherent illumination with the envelope of a top hat. The geometric centers of the sub-apertures are randomly offset by the light axis of the sub-lens in the array to break the periodicity. The influences of the various off-axis amounts on the homogeneity are discussed. The center off-axis microlens array has been fabricated, and the corresponding laser beam homogenizing experiment has been carried out. The results verify that a high homogeneity output intensity distribution can be achieved based on the presented method.

Center Off-Axis Tandem Microlens Arrays for Beam Homogenization

Binary-phase optics have been used by a number of high-power laser laboratories in order to achieve relatively smooth focal spots. However, the intensity envelopes have in general been of a sinc form rather than `top-hat.' This paper presents work on the production of uniform `top-hat' intensity focal spot profiles obtained from Fresnel binary phase zone plate (PZP) arrays of various designs. Phase plates are used to generate large area smooth focal spots and both theoretical and experimental focal spots are presented. These demonstrate the flexibility of this technique which provides a simple method of generating both uniform `top-hat' intensity profiles and spatially shaped foci, for use with high-power lasers.

Stanley A. Edwards

Papers

Binary-phase Fresnel zone plate arrays for high-power laser beam smoothing