Cast light to make the designated illuminated illumination is higher than the surrounding lighting, also known as spotlight. Often it is aimed at any direction and has a structure that is not affected by climatic conditions. Mainly used for large-scale workplace mine, building contours, stadiums, overpasses, monuments, parks and flower beds. Therefore, almost all of the outdoor use of large area lighting can be seen as cast light. The angle of the exit light of the spotlight is wide and narrow, and the range is between 0 ° and 180 °, where the beam is particularly narrow and called the searchlight.