18 August 2010 High throughput illumination systems for solar simulators and photoresist exposure
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High throughput illumination systems are critical component in photolithography, solar simulators, UV curing, microscopy, and spectral analysis. A good refractive condenser system has F/# .60, or N.A .80, but it captures only 10 to 15% of energy emitted by an incandescent or gas-discharge lamp, as these sources emit light in all directions. Systems with ellipsoidal or parabolic reflectors are much more efficient, they capture up to 80% of total energy emitted by lamps. However, these reflectors have large aberrations when working with real sources of finite dimensions, resulting in poor light concentrating capability. These aberrations also increase beam divergence, collimation, and affect edge definition in flood exposure systems. The problem is aggravated by the geometry of high power Arc lamps where, for thermal considerations, the anode has a larger diameter than the cathode and absorbs and obscures part of the energy. This results in an asymmetrical energy distribution emitted by the lamp and makes efficiency of Lamp - reflector configuration dependent on orientation of lamp in the reflector. This paper presents the analysis of different configurations of Lamp - Reflector systems of different power levels and their energy distribution in the image plane. Configuration, which results in significant improvement of brightness, is derived.
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Arkady Feldman, Arkady Feldman, } "High throughput illumination systems for solar simulators and photoresist exposure", Proc. SPIE 7785, Nonimaging Optics: Efficient Design for Illumination and Solar Concentration VII, 77850H (18 August 2010); doi: 10.1117/12.859692; https://doi.org/10.1117/12.859692

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