ABSTRACT
After a brief review of the physical properties of electromagnetic radiation, the main basic optical designs of telescopes and cameras and some of their adaptations for use on space missions are described. Refractive (lens-based) and reflective (mirror-based) as well as instruments combining both types of optics are included along with examples of their use in space-based and other missions.
Spectrographs for the extended optical region (EOR), after direct imaging, are amongst the commonest instruments to be fed by telescopes and cameras and the basics of diffraction grating spectroscopy are described from first principles along with briefer descriptions of other types of dispersers such as the Fabry–Perot etalons and acousto-optical tunable filters. After a review of why spectroscopy is such an important tool for astrophysics, individual instruments on missions ranging Apollo 16 through Cassini, New Horizons and Juno to the James Webb space telescope and beyond are discussed in detail and related to the earlier background material.
Finally, the physical principles of EOR detectors are covered from those in current use and their likely developments to those now only of historical interest. Examples of their applications within spacecraft-borne and other instruments are then discussed in detail.
