The Space Infrared Interferometric Telescope (SPIRIT): optical system design considerations

Abstract

The Space Infrared Interferometric Telescope (SPIRIT) was designed to accomplish three scientific objectives: (1) learn how planetary systems form from protostellar disks and how they acquire their inhomogeneous chemical composition;(2) characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets of different types form; and (3) learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. SPIRIT will accomplish these objectives through infrared observations with a two aperture interferometric instrument. This paper gives an overview into the optical system design, including the design form, the metrology systems used for control, stray light, and optical testing.

An optical model of the wide-field imaging interferometry testbed

“…The Wide-Field Imaging Interferometry Testbed (WIIT) 1,2 is functionally equivalent to a far-IR spatial and spectral interferometer, such as the Space Infrared Interferometric Telescope (SPIRIT) [3][4][5][6][7][8] or the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS). 9 In an earlier paper 10 we described the WIIT optical system model and presented an initial set of computational results.…”

System engineering the Space Infrared Interferometric Telescope (SPIRIT)

“…The length and diameter of the thermal baffles, both on the combiner and collector, were a major thermallstructural system trade; longer tubes perform better but require more mass, cooling power, and sunshield coverage. The incoming beams are compressed further to allow smaller optics in the delay line; again the degree of compression is an important trade covered in Wilson et al (2007) [ ' I . A shutter with a calibration lamp array is placed in each leg and used in instrument alignment and calibration.…”

“…The beam is collimated after leaving the secondary; the (de) magnification is 10, making for an -10cm SM and CSM. The degree of beam compression is an important trade discussed in Wilson et al (2007) 12]. An optics bench provides the near zero CTE, structural connection for the three telescope optics.…”

“…The scientific objectives, measurement requirements, and an overview of the design concept are described by . [11 Wilson et al (2007) 12] describes the optics and stray light trades. Budinoff et al (2007) 13] describes the SPIRIT mechanical design and mechanisms and explains how the mechanical design will meet instrument stability, thermal and packaging requirements.…”

The Space Infrared Interferometric Telescope (SPIRIT): the mission design solution space and the art of the possible

“…[1] Hyde et al (2007) [2] summarize system level trades and describe the design concept in greater detail, including the error budget for key design parameters and model-based estimates of the system performance. A paper by Wilson et al (2007) [3] focuses on the trades that influence optical system design choices, stray light control, metrology, and optical system performance verification. Budinoff et al (2007) [4] describe the SPIRIT mechanical design and mechanisms and explain how the mechanical design will meet instrument stability, thermal and packaging requirements.…”