Papers by Florian B Soulard
By pre-seeding the phase distribution of a point-oriented CGH, controlled-width line patterns are... more By pre-seeding the phase distribution of a point-oriented CGH, controlled-width line patterns are generated with high contrast (>0.6) for precision imaging applications such as photolithography. The approach is extensible to binary phase CGH and 3-D line patterns.
Digital Holography and Three-Dimensional Imaging, Jul 20, 2014
This review summarises the work of the Durham-Sheffield, UK team working on Holographic Lithograp... more This review summarises the work of the Durham-Sheffield, UK team working on Holographic Lithography over the last decade. It collates progress in 3D resolution and overall scale of the substrate wiring patterns designed and considers a range of approaches and applications.
International Conference in Digital Holography and Three-Dimensional Imaging, Apr 21, 2013
Holograms of 3D images are combined with noise suppression and off-axis projection to image arbit... more Holograms of 3D images are combined with noise suppression and off-axis projection to image arbitrary patterns onto a vertically oriented plane. This has important applications in microfabrication, for instance writing on the edges of silicon chips.
Journal of Micromechanics and Microengineering, Mar 28, 2013
We describe the novel fabrication of a 3D electrical small antenna and its subsequent characteriz... more We describe the novel fabrication of a 3D electrical small antenna and its subsequent characterization. The patterning of meander lines conformed onto a hemispherical substrate is achieved by 3D holographic photolithography, which uses time-division multiplexing of a series of iteratively optimized computer-generated holograms. The meander lines have a line width of 100 µm and line separation of 400 µm, with a line pitch of 500 µm and a total meander length of 145 mm. The working frequency is found to be 2.06 GHz, with an efficiency of 46%. This work demonstrates a new method for the fabrication of 3D conformal antennas.
International Conference in Digital Holography and Three-Dimensional Imaging, Apr 28, 2012
The two-dimensional demodulation of a hologram using the 2D Hilbert transform requires the suppre... more The two-dimensional demodulation of a hologram using the 2D Hilbert transform requires the suppression of the background illumination beforehand. We propose an iterative algorithm based on a spiral phase function for this purpose.
International Conference in Digital Holography and Three-Dimensional Imaging, Apr 28, 2012
A 3D substrate is lithographically patterned using a set of holograms generated by a multi-plane ... more A 3D substrate is lithographically patterned using a set of holograms generated by a multi-plane iterative algorithm. The substrate is exposed to multiple phase-only holograms over the duration of an exposure, thus averaging noise.
Journal of Micromechanics and Microengineering, Jul 26, 2011
We describe the patterning of multiple 10 µm wide conductive tracks down the vertical sidewall of... more We describe the patterning of multiple 10 µm wide conductive tracks down the vertical sidewall of a 500 µm thick silicon die. A novel photolithographic technique is used, which utilizes a computer-generated hologram mask in conjunction with a diffraction grating. 3D holographic photolithography is a powerful method for eliminating the troublesome diffractive line broadening that is usually encountered when patterning non-planar substrates. When used in conjunction with a diffraction grating, it creates the possibility to pattern fine features onto vertical surfaces—an achievement outside the normal realm of photolithography. The technique has many potential applications in MEMS, microsystem integration and packaging.
Optics Letters, Vol. 36, Issue 13, pp. 2495-2497, Jun 23, 2011
We have applied an iterative algorithm for hologram design with multiple output image planes arra... more We have applied an iterative algorithm for hologram design with multiple output image planes arranged in close proximity to create continuous patterns within an imaging volume. These holograms have been designed for photolithography on three-dimensional surfaces. The influence of simulated image plane separation on the final image, and its suitability for lithography, is assessed. Results are presented and the most suitable case is demonstrated experimentally.
International Conference in Digital Holography and Three-Dimensional Imaging, May 9, 2011
A method is presented for recording horizontal and vertical surfaces in a single process with a s... more A method is presented for recording horizontal and vertical surfaces in a single process with a standard DHM set-up. The purpose is to avoid rotating the sample, which would require new alignment and calibration procedures.
Second UK URSI Festival of Radio Science, Jan 12, 2011
Nearly all antenna structures fabricated for high volume markets are confined, where possible, to... more Nearly all antenna structures fabricated for high volume markets are confined, where possible, to essentially planar geometries. This is driven by the need to minimise fabrication and packaging costs. For certain applications considerable performance gains can however be achieved by utilising the third dimension. A well known example is the helical spiral structure, which has been manufactured by Sarantel for high-performance GPS receivers. Due to the complex geometry, fabrication of these antennas is slow and cumbersome in comparison to planar structures since conventional photolithography fabrication methods are inherently incompatible with non-planar substrates owing to diffraction effects that degrade the resulting pattern. Instead, helical antennas are constructed directly by scanning a laser beam across a rotating substrate. We describe a novel 3-D photolithographic method that enables non-planar antenna structures to be fabricated by a single photolithography exposure, thus regaining the potential for mass-production. We demonstrate the approach by fabricating a bi-conical spiral antenna structure representative of a wideband antenna for the frequency range 6–47 GHz.
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Papers by Florian B Soulard