Direct Measurement of the Photon's Spatial Wave Function

We overview recent progress in the tomography of structured light fields, with an emphasis on the method of direct measurement. Direct measurement provides a scalable and easy- to-implement approach for characterizing the transverse structure of single photons. This protocol is particularly attractive in light of the emerging role of high-dimensional optical states as a resource for encoding quantum information. We present a summary of various implementations of this technique that aim to characterize the spatial degree of freedom of the optical field.