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Bociort, F. (author), van Grol, P. (author)Understanding the structure of the design space in optical system optimization is difficult, because common human intuition fails when it encounters the challenge of high dimensionality, resulting from the many optimization parameters of lens systems. However, a deep mathematical idea, that critical points structure the properties of the space...conference paper 2012
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Bociort, F. (author), Van Grol, P. (author)In this paper we describe new properties of the design landscape that could lead in the future to a new way to determine good starting points for subsequent local optimization. While in optimization the focus is usually only on local minima, here we show that points selected in the vicinity of other types of critical points (i.e. points where...conference paper 2010
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Bociort, F. (author), Van Grol, P. (author)In this paper we describe new properties of the design landscape that could lead in the future to a new way to determine good starting points for subsequent local optimization. While in optimization the focus is usually only on local minima, here we show that points selected in the vicinity of other types of critical points (i.e. points where...conference paper 2010
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Van Grol, P. (author), Bociort, F. (author), Van Turnhout, M. (author)Contrary to the frequent tacit assumption that the local minima of a merit function are points scattered more or less randomly over the design landscape, we have found that, at least for simple imaging systems (doublets with three and triplets with five variables) all design shapes we have observed thus far form a strictly ordered set of points,...conference paper 2009
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- Bociort, F. (author), Van Turnhout, M. (author) journal article 2009
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Van Turnhout, M. (author)A major problem in optical system design is that the optical merit function landscape is usually very complicated, especially for complex design problems where many minima are present. Finding good new local minima is then a difficult task. We show however that a certain degree of order is present in the optical design space, which is best...doctoral thesis 2009
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- Marinescu, O. (author), Bociort, F. (author) journal article 2008
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- Marinescu, O. (author), Bociort, F. (author) journal article 2008
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Van Turnhout, M. (author), Bociort, F. (author)Local optimization algorithms, when they are optimized only for speed, have in certain situations an unpredictable behavior: starting points very close to each other lead after optimization to different minima. In these cases, the sets of points, which, when chosen as starting points for local optimization, lead to the same minimum (the so...conference paper 2007
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Bociort, F. (author), Van Turnhout, M. (author), Marinescu, O. (author)Saddle-point construction (SPC) is a new method to insert lenses into an existing design. With SPC, by inserting and extracting lenses new system shapes can be obtained very rapidly, and we believe that, if added to the optical designer’s arsenal, this new tool can significantly increase design productivity in certain situations. Despite the...conference paper 2007
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Bociort, F. (author), Van Turnhout, M. (author)In present-day optical system design, it is tacitly assumed that local minima are points in the merit function landscapewithout relationships between them. We will show however that there is a certain degree of order in the design landscapeand that this order is best observed when we change the dimensionality of the optimization problem and when...conference paper 2006
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Marinescu, O. (author), Bociort, F. (author)Optical designers often insert or split lenses in existing designs. Here, we present, with examples from Deep and Extreme UV lithography, an alternative method that consists of constructing saddle points and obtaining new local minima from them. The method is remarkable simple and can therefore be easily integrated with the traditional design...conference paper 2006
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Marinescu, O. (author), Bociort, F. (author)The multidimensional merit function space of complex optical systems contains a large number of local minima that are connected via links that contain saddle points. In this work, we illustrate a method to construct such saddle points with examples of deep UV objectives and extreme UV mirror systems for lithography. The central idea of our...conference paper 2005
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Bociort, F. (author), Van Turnhout, M. (author)Finding multiple local minima in the merit function landscape of optical system optimization is a difficult task, especially for complex designs that have a large number of variables. We discuss here a method that enables a rapid generation of new local minima for optical systems of arbitrary complexity. We have recently shown that saddle points...conference paper 2005
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Marinescu, O. (author), Bociort, F. (author)The merit function space of mirror systems for EUV lithography is studied. Local minima situated in a multidimensional merit function space are connected via links that contain saddle points and form a network. In this work we present the first networks for EUV lithographic objectives and discuss how these networks change when control parameters...conference paper 2005
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Serebriakov, A. (author), Bociort, F. (author), Braat, J. (author)In the year 2001 it was reported that the birefringence induced by spatial dispersion (BISD), sometimes also called intrinsic birefringence, had been measured and calculated for fluorides CaF2 and BaF2 in the deep UV range. It was also shown that the magnitude of the BISD in these cubic crystals is sufficiently large to cause serious problems...conference paper 2005
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Bociort, F. (author), Serebriakov, A. (author), Van Turnhout, M. (author)The merit function landscape of systems of thin lenses in contact, which are perhaps the simplest possible types of optical systems, shows remarkable regularities. It is easier to understand how the optimization parameter space of these simple systems is divided into basins of attraction for the various local minima if one focuses on the (Morse...conference paper 2004
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van Driel, E. (author), Bociort, F. (author), Serebriakov, A. (author)We have shown recently that, when certain quite general conditions are satisfied, the set of local minima in the optical merit function space forms a network where they are all connected through optimization paths generated from saddle points having a Morse index of 1. A new global optimization method, that makes use of this linking network to...conference paper 2004
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Serebriakov, A. (author), Maksimov, E. (author), Bociort, F. (author), Braat, J. (author)The subject of birefringence induced by spatial dispersion (BISD), also called intrinsic birefringence, recently became an important issue for 157-nm lithography. For the deep UV range, because of intrinsic absorption, only crystalline materials can be used as optical materials for lens manufacturing. The physical properties of crystals are...conference paper 2004