| 摘要 |
At least one temporary visible reference line is projected onto a target surface, as for example, an athletic field, by several laser sources. A first laser source emits optical energy-at a wavelength of between 380 nm and 750 nm-along at least a first selectable path upon the target surface so as to form a temporary line thereon. A second laser source disposed at a second elevated, stationary location relative to the target surface different from the first stationary location emits optical energy along at least a second selectable path upon the target surface so as to form a temporary line thereon. In some instances, each laser light source may be capable of traversing the entire width of the target surface, in which case each laser source covers a discrete region. In other cases, respective laser sources arranged on opposite laterals sides of the target surface can be included so that segments contiguous with those projected by a corresponding one of the first and second laser sources can be generated to form a temporary line that does traverse the entire width of the target surface.
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