The Innoslab amplifier comprises a diode-laser partially end-pumped thin slab crystal and a folded single-pass optical amplification path. While this configuration differs in many respects from other slab amplifiers, it shares characteristics with partially end-pumped rod amplifiers. It combines outstanding thermal management, efficiency, and beam quality in the 100 W to 1 kW power range. In this paper, we review amplifiers for a wide range of operation regimes and laser materials.
More and more lighting applications require the design of dedicated optics to achieve a given radiant intensity or irradiance distribution. Freeform optics has the advantage of providing such a functionality with a compact design. It was previously demonstrated in [Bäuerle et al., Opt. Exp. 20, 14477-14485 (2012)] that the up-front computation of the light path through the optical system (ray mapping) provides a satisfactory approximation to the problem, and allows the design of multiple freeform surfaces in transmission or in reflection. This article presents one natural extension of this work by introducing an efficient optimization procedure based on the physics of the system. The procedure allows the design of multiple freeform surfaces and can render high resolution irradiance patterns, as demonstrated by several examples, in particular by a lens made of two freeform surfaces projecting a high resolution logo (530 × 160 pixels).
The design of freeform lenses and reflectors allows to achieve non-radially symmetric irradiance distributions whilst keeping the optical system compact. In the case of a point-like source, such as an LED, it is often desired to capture a wide angle of source light in order to increase optical efficiency. This generally results in strongly curved optics, requiring both lens surfaces to contribute to the total ray refraction, and thereby minimising Fresnel losses. In this article, we report on a new design algorithm for multiple freeform optical surfaces based on the theory of optimal mass transport that adresses these requirements and give an example of its application to a problem in general lighting.
LED lighting has been a strongly growing field for the last decade. The outstanding features of LED, like compactness and low operating temperature take the control of light distributions to a new level. Key for this is the development of sophisticated optical elements that distribute the light as intended. The optics design method known as tailoring relies on the point source assumption. This assumption holds as long as the optical element is large compared to the LED chip. With chip sizes of 1 mm² this is of no concern if each chip is endowed with its own optic. To increase the power of a luminaire, LED chips are arranged to form light engines that reach several cm in diameter. In order to save costs and space it is often desirable to use a single optical element for the light engine. At the same time the scale of the optics must not be increased in order to trivially keep the point source assumption valid. For such design tasks point source algorithms are of limited usefulness. New methods that take into account the extent of the light source have to be developed. We present two such extended source methods. The first method iteratively adapts the target light distribution that is fed into a points source method while the second method employs a full phase space description of the optical system.
This article puts forward an interactionist discourse approach for studying the course of local political protest. We argue that how local policy-makers engage with the (anticipated) demands of citizens and mediate national policy produces distinct framing and feeling rules about potentially controversial issues. These framing and feeling rules open up or close down opportunities for citizen concerns to develop into collective action and policy change. Our contribution refines cultural approaches to social movement theory, focusing on local interactions in the formation of discourse, and allows us to better understand within-country variation in the course of contentious collective action. We develop our argument through a comparison of sixteen cases of installing mobile phone cell sites in the Netherlands. We show that the interaction between municipalities and citizens establishes a specific framing of the issue, of the role of citizens in decision-making and of the rules concerning what citizens may legitimately feel about mobile phone masts being erected in their neighbourhoods. This gives rise to four typical patterns of engagement between municipalities and citizens.
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