An ideal projection optical module has perfect focus uniformity, meaning the entire image is in focus. If an optical module has focus non-uniformity problems, the image is visibly out of focus in at least one location, often the edges or corners. Utilizing optical modules with higher F/#'s improves depth of focus and results in a more uniform focus throughout the projected image. Proper alignment of the projection optics with the DMD in the optical module is crucial to prevent issues (such as boresighting). These problems can stem from variations in optical component performance or optical misalignment. To learn more regarding focus uniformity and its impact on an optical system, see the DLP Optical Design Guidelines presentation.