Component Designs for SOAR's Spartan IR Camera

Students and faculty from Michigan State University, in partnership with three other groups, are currently conducting research in a joint effort to construct a 4-meter telescope on a mountaintop in the Chilean Andes by the year 2002. The SOAR (SOuthern Astrophysical Research) project will take advantage of the telescope's size to observe the unique astronomic phenomena of the Southern Hemisphere in greater detail than ever before. Michigan State is responsible for building the Spartan IR Camera, an instrument that will be used for making observations at infrared wavelengths. This report is a compilation of five self-sufficient and informal papers describing original design concepts for several components of the Spartan IR Camera. The first paper addresses the 200 mm diameter silica window to be used as an optical barrier between the outside atmosphere and vacuum conditions inside the instrument. This 15 psi pressure gradient will cause the window to bend that is modeled by a fourth-order polynomial equation. The second paper illustrates the effects of gravity on the 11 individual optical elements that will be mounted on the optical bench of the IR Camera. The final three papers describe three independent design ideas for the two primary camera structures: the optical bench and liquid nitrogen reservoir. The structural limitations on these structures include: 1) they must both fit inside a space 1m x .75m x .75m and 2) have a combined mass as far below the maximum limit of 120 kg as possible. Additional criteria state that the reservoir must hold at least 40 lbs (18.2 kg) of liquid nitrogen and there must not be any greater than a 5 arcsecond angular deflection anywhere on the top surface of the optical bench. Each of the three designs (labeled A through C) complies with the criteria, but they each have certain advantages and disadvantages with regards to total mass, manufacturing difficulty, etc.