Evaluation of a solid KRS-5 grism for infrared astronomy

We discuss the design and performance of a solid KRS-5 grism used in NSFCAM, a 1-5.5 micrometers facility IR camera at the NASA IR telescope Facility on Mauna Kea. The grism was built by Carl Zeiss, Jena-Germany, and cost 13,800 dollars. It is used with order-sorting filters in the L-, K- and H-bands, and provides a spectral resolution of R equals 280. We also discus the advantages and disadvantages of solid grisms over replica resin grisms, and illustrate the performance of the grism with some astronomical observations.