It has been well established that X-ray films are best read at high peak brightness (2000-4000 nits), yet current LCD and CRT displays used in radiology have peak brightness of only 500-700 nit typically. We have developed super-bright LCD displays that for the first time approach light box brightness levels while maintaining good viewing angle characteristics and uniformity. We provide characterization of a new monochrome model with 2000 nit peak brightness and a new color model with 500 nit peak brightness. To investigate the effect of the increased brightness on search performance, a small observer study was performed. Eight radiologists and residents were asked to search for low-contrast artefacts (15 mm ovals) superimposed on a mammogram. Four different LCD displays were used, with peak brightnesses from 200 to 2000 nit. For low-contrast artefacts, search performance was markedly improved at the highest brightness.
A laser-generated water plasma source has been built, operating around-the-clock. We characterized this source looking at several aspects that are important for a possible EUV source to be used in a next-generation lithographic tool. We characterized the source spectrally, measured the size of the source, the angular dependence of the EUV emission and the temporal dependence of the EUV pulses. We also investigated the level of debris produced by the source and the contamination of EUV optics by the water plasma. Finally, this laser-generated water plasma has been successfully used in a shearing interferometer, in which the imaging equality of EUV optics can be assessed accurately at-wavelength.
In order to assess the imaging quality of EUV optics, extensive metrology needs to be performed. Mirror substrates are commonly investigated with AFM, while optical probes and visible light interferometry are used to probe respectively high-, mid- and low spatial frequencies. Coatings on flat substrates are usually investigated using Cu-K(alpha) , i.e. X- ray reflectometry at grazing incidence. EUV-reflectometry can be performed on curved optics as well. Assembled EUV imaging systems have been evaluated by both visible-light and EUV interferometry. Most EUV interferometry has been performed with a point-diffraction interferometer, requiring the laser- like spatial coherence of a synchrotron. Early demonstrations indicated that the compact laser plasma source proposed for EUV lithographic tools could also be used. We have continued in this direction, and have demonstrated by means of computer simulation and experiments with visible light that an absolute accuracy of better than 10 milliwaves, i.e. 0.13 nm when using EUV, can be achieved by a shearing interferometer. This contribution describes the realization and first results of such an interferometer, employing a laser plasma as a EUV light source. The same scheme could however be used for all EUV sources proposed for EUV lithography.
Although EUV-optics can be very accurately tested interferometrically employing a synchrotron, testing with a laser-induced or pinch plasma is attractive because of the lower cost of such sources. Within Philips Research a project has started to build an interferometer employing a laser plasma source and a Ronchi-test which is modified in such a way that two-beam interferograms are obtained. We analyze the accuracy, the vibration and drift sensitivity and the dynamic range of the interferometer for three different combinations of entrance and exit grating by means of computer-generated interferograms. The results are compared with an optical experiment, in which the relevant parameters of the interferometer have been scaled up so that visible light can be used.
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