The most uniform light source available would be an integrating sphere, but these come with considerable size and expense. After considering how the light source uniformity impacts their results, most lab & manufacturing tests use LED or fluorescent lightboxes with flat-panel diffusers. Some customers choose a larger lightbox because that leads to greater uniformity within the central image plane area. We have performed a study of lightbox uniformity to see how different models compare.
To perform tests with a transmissive chart setup, devices with built-in light sources will need to have that light source disabled. (more…)