[Left] Semiconductor layers are stacked using concentric metalenses as alignment marks. [Right] Light shines through these marks to project a hologram. The alignment or misalignment of the lenses dictates the hologram's appearance. Credit: Amir Arbabi Researchers at the University of Massachusetts Amherst have invented a new way to align 3D semiconductor chips by shining a laser through concentric metalenses patterned on the chips to produce a hologram. Their work, published in Nature Communicat...