Wideband infrared spectrometer for characterization of transiting exoplanets with space telescopes

Abstract

This paper presents a conceptual design for a spectrometer designed specifically for characterizing transiting exoplanets with space-borne infrared telescopes. The design adopting cross-dispersion is intended to be simple, compact, highly stable, and has capability of simultaneous coverage over a wide wavelength region with high throughput. Typical wavelength coverage and spectral resolving power is 1-13 micron with a spectral resolving power of ~ a few hundred, respectively. The baseline design consists of two detectors, two prisms with a dichroic coating and microstructured grating surfaces, and three mirrors. Moving parts are not adopted. The effect of defocusing is evaluated for the case of a simple shift of the detector, and anisotropic defocusing to maintain the spectral resolving power. Variations in the design and its application to planned missions are also discussed.

Development of a Fine Grating on ZnS for a Wideband Spectral Disperser in Characterizing Exoplanets Using Space-Borne Telescopes

“…Space-borne infrared telescopes carrying a spectrometer are vital for this challenging objective. We previously presented the concept and various specialized spectrometer designs for temporary differential observations of exoplanets [1][2][3][4][5] . The fabrication of gratings on the surfaces of prisms made of infrared-transmissive material is a key technology for such spectrometers.…”

“…The fabrication of gratings on the surfaces of prisms made of infrared-transmissive material is a key technology for such spectrometers. ZnS is one such suitable material for a wideband infrared spectral disperser because its optical properties enable simultaneous wavelength coverage in the range of 1−13 µm [2] . In addition, it is well available and amenable for fabrication.…”

“…CdTe and CdZnTe are harmful materials but they enable optically wider coverage, λ = 1−33 µm [1] . A Si:As detector can cover most of this wavelength region and it makes the instrument very simple while with a combination of detectors (e.g., a Si:As detector and an InSb detector) higher efficiency can be realized [2] . Fig.…”