A uniform diffraction grating, such as a window screen, does not inherently focus objects like bricks on a building for a nearsighted observer. The observed improvement in focus may be attributed to Moiré patterns or the pinhole effect, which can enhance clarity when viewing distant objects through fine mesh. The pinhole effect can counteract refractive errors by allowing light rays to enter through small apertures. The discussion highlights the role of multiple apertures in creating interference patterns without significant light loss. Overall, the interaction of light with the grating can create visual effects that may seem like focusing but are fundamentally different.
