Guenther Hans Derra

UHP lamp systems for projection applications

Projection systems have found widespread use in conference rooms and other professional applications during the last decade and are now entering the home TV market at a considerable pace. Projectors as small as about one litre are able to deliver several thousand screen lumens and are, with a system efficacy of over 10 lm W −1 , the most efficient display systems realized today. Short arc lamps are a key component for projection systems of the highest efficiency for small-size projection displays. The introduction of the ultra high performance (UHP) lamp system by Philips in 1995 can be identified as one of the key enablers of the commercial success of projection systems. The UHP lamp concept features outstanding arc luminance, a well suited spectrum, long life and excellent lumen maintenance. For the first time it combines a very high pressure mercury discharge lamp with extremely short and stable arc gap with a regenerative chemical cycle keeping the discharge walls free from blackening, leading to lifetimes of over 10 000 h. Since the introduction of the UHP lamp system, many important new technology improvements have been realized: burner designs for higher lamp power, advanced ignition systems, miniaturized electronic drivers and innovative reflector concepts. These achievements enabled the impressive increase of projector light output, a remarkable reduction in projector size and even higher optical efficiency in projection systems during the last years. In this paper the concept of the UHP lamp system is described, followed by a discussion of the technological evolution the UHP lamp has undergone so far. Last, but not least, the important improvements of the UHP lamp system including the electronic driver and the reflector are discussed. (Some figures in this article are in colour only in the electronic version)

Physical properties of the HCT EUV source

The paper describes the physical properties and recent technical advances of the hollow cathode triggered pinch device (HCT) for the generation of EUV radiation. In previous publications we have demonstrated continuous operation of the untriggered device at 1 kHz in pure Xe. The newer generations operate with a triggering facility which allows a wider parameter space under which stable operation is possible. Repetition frequencies of up to 4 kHz could be demonstrated. Many of the experiments are performed in repetitive bursts of variable lengths and spacing. This allows also to demonstrate that there is only little transient behavior upon switching on and off the source. Conversion efficiencies into the 2 percent frequency band around 13.5 nm are about 0.4 percent in 2p, comparable to the values reported from other groups. Another important parameter is the size of the light emitting region. Here we have studied the influence of electrode geometry and flow properties on the size, to find a best match to the requirements of the collection optics. A major problem for the design of a complete wafer illumination system is the out-of-band portion of the radiation. Especially the DUV fraction of the source spectrum is a concern because it is also reflected to some extend by the Mo-Si multilayer mirrors. We show that the source has a low overall non-EUV part of the emission. In particular, it is demonstrated that there is very little DUV coming out of the usable source volume, well below the specified level.

UHP lamps for projection

UHP lamps are now standard equipment in highly efficient projection systems. These systems are moving toward smaller displays, brighter screens, and ultra-compactness. Consequently, a range of UHP lamps has been developed to fulfil these ever-increasing demands. This paper describes the basic principles of UHP lamps and reviews the major achievements made over the last several years, which include reduction in arc size, arc stabilization, and ignition voltage reduction.

High-power VCSEL systems and applications

Easy system design, compactness and a uniform power distribution define the basic advantages of high power VCSEL systems. Full addressability in space and time add new dimensions for optimization and enable “digital photonic production”. Many thermal processes benefit from the improved control i.e. heat is applied exactly where and when it is needed. The compact VCSEL systems can be integrated into most manufacturing equipment, replacing batch processes using large furnaces and reducing energy consumption. This paper will present how recent technological development of high power VCSEL systems will extend efficiency and flexibility of thermal processes and replace not only laser systems, lamps and furnaces but enable new ways of production. High power VCSEL systems are made from many VCSEL chips, each comprising thousands of low power VCSELs. Systems scalable in power from watts to multiple ten kilowatts and with various form factors utilize a common modular building block concept. Designs for reliable high power VCSEL arrays and systems can be developed and tested on each building block level and benefit from the low power density and excellent reliability of the VCSELs. Furthermore advanced assembly concepts aim to reduce the number of individual processes and components and make the whole system even more simple and reliable.

Status of Philips' extreme UV source

The paper describes progress of the Philips’ hollow cathode triggered (HCT) gas discharge EUV source. The program has been focussed on three major areas: (1) Studying the basic physics of ignition, pinch formation and EUV generation. The paper reports on progress in this area and particularly describes the underlying atomic physics both for Xe and Sn. (2) Discharge based on Sn. Results on overall efficiency more than 5 times the Xe efficiency are reported as well as high frequency operation up to 6.5 kHz. This system shows all the necessary ingredients for scaling to production power levels. (3) Integration of the Xe source in an alpha tool. Results on integration issues like electrode life time, collector life time and dose control will be presented.

VCSEL arrays expanding the range of high-power laser systems and applications

Thermal treatment may be by far the most frequent process used in manufacturing, but only at a few places lasers could make an inroad. For thermal treatment homogeneous illumination of large areas at a lower brightness, and accurate temporal as well as spatial control of the power is required. This is complicated for conventional high-power lasers, while VCSEL arrays inherently have these capabilities.Because of their fast switching capability and low power dissipation, vertical-cavity surface emitting laser-diodes (VCSELs) have been widely used for datacom and sensing applications. By forming large-area arrays with hundreds of VCSELs per mm2, their use can be further expanded to high-power applications. In this way power densities of several W/mm2 are achieved, making VCEL arrays an ideal solution for many heating applications, ranging from melting and welding of plastics and laminates to curing, drying and sintering of coatings.A turn-key system concept has been developed allowing fast and easy configuring systems to the specifications of the applications. The compact and robust system can be built directly into the manufacturing equipment, thus making expensive fibers and homogenizing optics superfluous. These systems are now finding their first inroads into industrial applications and have been designed-in into commercially available production machines.Thermal treatment may be by far the most frequent process used in manufacturing, but only at a few places lasers could make an inroad. For thermal treatment homogeneous illumination of large areas at a lower brightness, and accurate temporal as well as spatial control of the power is required. This is complicated for conventional high-power lasers, while VCSEL arrays inherently have these capabilities.Because of their fast switching capability and low power dissipation, vertical-cavity surface emitting laser-diodes (VCSELs) have been widely used for datacom and sensing applications. By forming large-area arrays with hundreds of VCSELs per mm2, their use can be further expanded to high-power applications. In this way power densities of several W/mm2 are achieved, making VCEL arrays an ideal solution for many heating applications, ranging from melting and welding of plastics and laminates to curing, drying and sintering of coatings.A turn-key system concept has been developed allowing fast and easy configur...

Vertical-cavity surface emitting laser-diodes arrays expanding the range of high-power laser systems and applications

Thermal treatment may be by far the most frequent process used in manufacturing, but only at a few places lasers could make an inroad. For thermal treatment, homogeneous illumination of large areas at a lower brightness, and accurate temporal as well as spatial control of the power is required. This is complicated for conventional high-power lasers, while vertical-cavity surface emitting laser-diode (VCSEL) arrays inherently have these capabilities. Because of their fast switching capability and low power dissipation, VCSELs have been widely used for datacom and sensing applications. By forming large-area arrays with hundreds of VCSELs per mm2, their use can be further expanded to high-power applications. In this way, power densities of several W/mm2 are achieved, making the VCEL arrays an ideal solution for many heating applications, ranging from melting and welding of plastics and laminates to curing, drying, and sintering of coatings. A turn-key system concept has been developed allowing fast and easy ...