Massively parallel detection

The invention provides apparatuses for detecting light from, for example, closely spaced detection sites. In one embodiment, the invention provides an apparatus for measuring the amount of light emitted from or transmitted through two or more detection sites of a first set of detection sites on a planar substrate while spatially resolving the measurements for each detection site of the first set, the apparatus comprising: for each detection site of the first set, an addressable source of a light beam directed to that detection site at a first angle; and an array detector comprising a plurality of light responsive pixels, wherein for each detection site of the first set there is at least one light responsive pixel that receives light emitted from or transmitted through that detection site at a second angle that can be the same as the first angle.