Carsten Deppe

Modular VCSEL solution for uniform line illumination in the kW range

High power VCSEL arrays can be used as a versatile illumination and heating source. They are widely scalable in power and offer a robust and economic solution for many new applications with moderate brightness requirements. The use of VCSEL arrays for high power laser diode applications enables multiple benefits: Full wafer level production of VCSELs including the combination with micro-optics; assembly technologies allowing large synergy with LED assembly thus profiting from the rapid development in solid state lighting; an outstanding reliability and a modular approach on all levels. A high power VCSEL array module for a very uniform line illumination is described in detail which offers >150W/cm optical output and enables less than 1% non-uniformities per mm along the line. The applied optical principle of near field imaging and massively superposing many thousand VCSELs by arrays of micro-lenses gives perfect control over the intensity distribution and is inherently robust. A specific array of parallelogram shaped VCSELs has been developed in combination with an appropriate micro-lens design and an alignment strategy. The concept uses parallel and serial connection of VCSEL arrays on sub-mounts on water coolers in order to realize a good combination of moderate operating currents and reliability. Lines of any desired length can be built from modules of 1cm length because this optical concept allows large mounting tolerances between individual modules. Therefore the concept is scalable for a wide range of applications. A demonstrator system with an optical output of 3.5kW and a line length of 20cm has been realized.

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.

26.2: Controlled Electrodes in UHP Lamps

The electrodes of short arc UHP lamps bear the brunt to combine high power densities with long life. This conflict can be resolved by a proper electrical operation of the lamp. Special drive schemes for Philips UHP lamps provide a stable arc attachment and a superior electrode durability. In this paper, we present electrode performance measurements under various conditions and discuss the underlying physical effects.

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 ...

Resonant standby mode for LLCC load resonant power converters

A solution for efficient small volume power supplies is the use of high switching frequencies combined with zero voltage switching (ZVS). One topology for this is the LLCC converter. Cost effective solutions for many applications require the implementation of integrated standby operation. Standby operation here means the maintenance of basic control functions while the rest of the device is turned off. This article shows a new approach for this function without additional active components

Invited Paper: 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 with considerable pace. Projectors as small as about one liter are nowadays able to deliver a screen flux of several thousand lumens and are, with a system efficacy of more than 10 lm/W, the most-efficient display system realized today. Because such highly efficient projectors employ microdisplays as light valves, short-arc lamps are a key component in realizing these properties. The introduction of the UHP-lamp system by Philips in 1995 can be identified as one of the key enablers for the commercial success of projection systems. The ultra-high-performance (UHP) lamp concept features outstanding arc luminance, a well-suited spectrum, long life, and excellent flux maintenance. For the first time, it combines a very-high-pressure mercury-discharge lamp having an extremely short and stable arc length with a regenerative chemical cycle that keeps the discharge walls free from blackening, leading to lifetimes of over 10,000 hours. In this review, the most important aspects of the UHP concept that enabled its success in the projection market are described, followed by a discussion of some recent additions to the UHP-product portfolio.