Observations at infrared,submillimeter wavelengths will be essential for addressing many of the key questions in astrophysics.Because of the very wide wavelength coverage,a variety of detector types will be required to satisfy these needs.They include direct hybrid arrays of InSb and HgCdTe photodiodes from 1 to 5μm,and of Si∶As Impurity Band Conduction detectors from 5 to 28μm;a number of approaches to photoconductive detector arrays in the far infrared;and bolometer arrays or superconducting devices in the far infrared through mm-wave spectral range.The underlying principles behind these approaches and the application of these principles are discussed.