2020PASP..132a2001B

Hard X-ray and low-energy gamma-ray coded-aperture imaging (CAI) instruments have been highly successful as high-energy surveyors and transient-source discoverers and trackers over the past decades. Albeit having relatively low sensitivity as compared with focusing instruments, coded-aperture telescopes still represent a very good choice for simultaneous, high cadence spectral measurements of individual point sources in large source fields. Here, I present a review of the fundamentals of CAI instruments in high-energy astrophysics, with an emphasis on the fundamental aspects of the technique, coded-mask instrument characteristics, and properties of the reconstructed images.