Optical proximity correction

In general, laser writers offer some unique advantages. With multiple laser beams (up to 32 in some systems), these systems are capable of high throughput and are therefore considerably faster than their electron-beam-writer counterparts. They are also more accurate than electron-beam writers because they are more stable, a consequence of the facts that electrons are very sensitive to magnetic fields and also tend to scatter. The very small effective address unit is useful for fine adjustment of line widths on the mask, which makes it easier to implement optical proximity correction schemes in these masks than in masks produced from other mask writers. Furthermore, laser writers operating at 364-nm and... 

A major difficulty encountered with atomic absorption techniques is the presence of incompletely absorbed background emission from the source and scattered light from the optical system. As the background becomes more intense relative to the absorption of the analyte, the precision of the measurement decreases dramatically. For this reason, several background correction techniques have been implemented. A commonly used method is the method of proximity, which was discussed in relation to inductively coupled plasma spectroscopy. 

The adaptive optics correction depends on having a bright point source near the field of view to provide the information on the atmospheric distortion to the system. This source can be a bright astronomical source or an artificial point source created by a laser beam. The requirement for proximity is such that the measurement of the... 

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