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OED: Engineering and Design

Thursday 11th October - Theatre 3 - Ericsson Exhibition Hall

 

Chairs: Jon Maxwell and Beric Read

10:30 Introduction and welcome
10:40 Advances in adaptive optics: What can ophthalmology, microscopy and astronomy learn from each other?
Dr Karen Hampson, University of Oxford, UK
 

Adaptive optics is a technique that can compensate for aberrations. It was first developed for astronomy and military applications to remove the blurring effects of the atmosphere on light propagation. Since its first demonstration several decades ago, the technique has been applied to a number of other fields. For example, it is used in ophthalmology to compensate for the aberrations introduced by the optics of the eye. This has allowed in-vivo imaging of individual retinal cells. By compensating for aberrations introduced by refractive index inhomogeneities in a specimen, microscopes can reach higher resolutions.

Although adaptive optics has proved successful in these fields, each field still has challenges. However, what may be a challenge in one field, has been solved in another. One such example is increasing the field of view over which adaptive optics can increase resolution, a technique known as multiconjugate adaptive optics, which was originally developed in astronomy.

This talk will begin with an overview of how adaptive optics works. It will then discuss the current advances across the fields of ophthalmology, microscopy and astronomy. Finally, how the advances in each field can address the challenges in the others will be discussed.

11:00 Optical filters in Spectroscopy
Oliver Pust, Delta Optical Thin Films A/S, Denmark
 

Biochemists and chemists wishing to investigate the structure of unknown compounds often apply a technique known as spectroscopy. Spectroscopy involves submitting a sample to some form of energy in the form of radiation or light and examining how the sample interacts with that energy.

Interference filters are considerably smaller and lighter than monochromators and also offer technological benefits, in particular greatly increased potential grasp of energy ('light grasp') compared to monochromators. When properly designed, an interference filter is capable of collecting several hundred or even several thousand times the quantity of light collected by a monochromator with the same bandwidth.

Interference filters can be designed to meet the needs of spectroscopists, e.g. Continuously Variable Filters in which the wavelength of light transmitted and reflected from the optical layers changes continuously as it passes along the length of the filter.

11:20 Simulation & testing of optics for laser DEW applications
Dr Peter Rees, LumOptica Ltd
 

High-power laser systems require very high-quality optics in order to maintain beam quality and, in the case of Laser DEW systems, achieve high pointing accuracy. Coherent beam combining systems are especially demanding in this respect, typically requiring a wavefront quality on the scale of a few tens of nanometres to be maintained whilst transmitting tens of thousands of Watts of laser power.

This presentation will introduce the issues involved in designing the optics for such systems. In particular, computer modelling of the heating and consequent optical aberrations of lenses and mirrors will be presented along with experimental validation results.


KEYNOTE PRESENTATION:
11:40 Accounting for coherent effects in the ray-tracing simulation: more rigorous approach of subwavelength features in a design
Dr Maryvonne Chalony, Light Tec, France
 

The coherent effects of light arising from the near/subwavelength features are difficult to include in the RayTracing simulation of a device. The RT techniques are based on the geometric optics approximation, their primary limitation is that they fail to model subwavelength geometric features where coherent effects, such as diffraction and interference, are critical. On the other hand, rigorous electromagnetic (EM) wave optics-based techniques, such as finite-difference time-domain (FDTD) and rigorous coupled wave analysis (RCWA), solve Maxwell’s equations either directly or through some approximation.

These rigorous EM techniques can be used for modeling several optical aspects of a design including the subwavelength layered structures, nanostructured gratings, micropatterned substrates, photonic crystal and other periodic gratings, coupling to surface plasmon modes for back-reflectors, and random surface textures. However, these rigorous EM techniques have difficulty in analyzing the larger structures due to computational resource limitations.

It becomes clear that a mixed-level simulation approach is required to circumvent the limitations of the individual numerical techniques.

We will introduce the principle of the mixed-level simulation approach and demonstrate its usage through various examples (LED, surface textures...).

12:00 1000 Shades of grey - fabricating micro-optical elements using greyscale laser lithography
Andreas Ludwig, Heidelberg Instruments, Germany

   

Greyscale laser lithography is a versatile technique for the creation of microstructures in photoresist. In contrast to traditional lithography, where the photoresist is either completely exposed or unexposed, the goal of greyscale lithography is to transfer exposure intensity gradients into a resist topography. Its geometric flexibility, high speed and the possibility to scale it up to large exposure areas (e.g. 1.4 x 1.4 m²) make greyscale laser lithography a perfect technique for both fast prototyping and large-area production of 2.5-dimensional microstructures for applications like micro-optics, diffractive optical elements, computer-generated holograms, MEMS and many others.

Geometry-dependent proximity effects as well as the non-linear resist response to varying exposure intensities, however, pose major challenges to this technique.

Resolving them usually requires time-consuming iterative optimization procedures, leading to steep learning curves for anyone new to the field.  To facilitate this, software-based approaches for exposure optimization have been developed, which aim at reducing time and effort required for obtaining the desired geometry.

In this talk, the general concept and selected applications of greyscale laser lithography are presented. Both iterative and software-based approaches for exposure optimization are discussed and their respective strengths and weaknesses elucidated.

12:20 The commercial application of harsh environment optical sensors in aerospace and power generation
Ian Macafee, Oxsensis, UK
 

Optical instrumentation is finding its place in demanding applications in energy intensive and physically demanding applications. The ability to operate non-electrically, at high temperatures, at large distances, and to deliver multiple measurands with a single device – make a difference in key sensor challenges. The progressive maturing of system components and supporting technology now enable optical sensors to displace legacy electrical systems and the paper will show how this is being achieved in two high value markets – power generation and aerospace. In both cases, optical instrumentation is gaining ground due to changes in requirements and also optical systems are enabling architecture changes to be made in flight and land based systems. The alignment of key customers, changes in expected system standards and the targeted support of sector investment are all part of the adoption path for technologies such as this. Oxsensis is the optical instrumentation leaders in its chosen markets and the paper will describe progress to date and the near term next steps it is taking to support its customers.

12:40 Concluding comments
  The exhibition remains open until 4pm


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CO-LOCATED CONFERENCES

 
 

TECHNICAL PROGRAMME COMMITTEE

Dr Sean Kudesia
Optos

Jon Maxwell

Consultant

Beric Read
BJR Systems Ltd

 

CO-LOCATED EXHIBITIONS