In many projection applications, the placement of the projector with respect to the viewing screen is important. The throw ratio of the projector determines how far away the projector must be placed in order to achieve a certain screen size (see Figure 7). The width of the projected image (W) with respect to the distance from the lens to the center of the screen (D) is the throw ratio (T), which is shown in Figure 7. Laser TV applications typically have ultra-short throw optical modules that allow for throw ratios of less than 0.4.