  Prime-Cam is a first-generation science instrument for the CCAT Observatory's
six-meter aperture Fred Young Submillimeter Telescope (FYST). FYST's
crossed-Dragone design provides high optical throughput to take advantage of
its unique site at 5600 m on Cerro Chajnantor in Chile's Atacama Desert to
reach mapping speeds over ten times greater than current and near-term
submillimeter experiments. Housing up to seven independent instrument modules
in its 1.8-meter diameter cryostat, Prime-Cam will combine broadband
polarization-sensitive modules and spectrometer modules designed for
observations in several frequency windows between 210 GHz and 850 GHz to study
a wide range of astrophysical questions from Big Bang cosmology to the
formation of stars and galaxies in the Epoch of Reionization and beyond. In
order to cover this range of frequencies and observation modes, each of the
modules contains a set of cold reimaging optics that is optimized for the
science goals of that module. These optical setups include several filters,
three or four anti-reflection-coated silicon lenses, and a Lyot stop to control
the field of view and illumination of the primary mirror, satisfy a series of
mechanical constraints, and maximize optical performance within each passband.
We summarize the design considerations and trade-offs for the optics in these
modules and provide a status update on the fabrication of the Prime-Cam
receiver and the design of its 1 K and 100 mK thermal BUSs.
