Efficient Mirrorlet Array Based Integral Field Spectrometer (IFS) for HWO

Habitable World Observatory (HWO) is a NASA strategic mission recommended by 2020 astronomical decadal survey. Integral field spectrometers play an important role to verify if the observed exoplanet is habitable. The traditional lenslet array based IFS has the advantage of simplicity and compactness. However, it does not use detector pixels efficiently in order to prevent wavelength crosstalk among adjacent spectra. The efficient lenslet/mirrorlet IFS combines the advantages from both lenslet based and imager slicer based IFSes—keeping lenslet IFS’s simplicity and compactness, and adding slicer IFS’s detector efficiency. This paper discusses the principle of efficient lenslet/mirrorlet IFS, design philosophy, and efficient spectral trace layout ideals. It uses HWO NIR IFS requirement as an example to provide an efficiency mirrorlet IFS optical design. The high detector efficiency not only reduces needed detector pixel numbers, but also reduces the high communication rate demanding for such a large multiple instrument mission.