SCALES slenslit design status

We report on the design and status of the slicing unit of SCALES (Slicer Combined with an Array of Lenslets for Exoplanet Spectroscopy), which sits behind the lenslet array and produces a pseudoslit suitable for higher dispersion than is achievable with a lenslet alone. Typical lenslet-based integral field spectrographs achieve high spatial resolution (but at the expense of spectral resolution), and slicers can achieve high spatial and spectral resolution (but at the expense of field of view), and additionally require extreme care in design and fabrication to avoid introducing aberrations through the slicer and spectrograph optics that can reduce the overall performance. Our ‘slenslit’ (SLiced LENlet pseudoSLIT) combines the benefits of the lenslet array, which samples the field of view, and the slicer, which rearranges the field of view, to produce diffraction-limited, high spatial resolution spectra of exoplanets. SCALES’ diffraction-limited integral field spectrograph operates from 1 to 5 microns behind the W.M. Keck Observatory’s AO system, and coronagraphic masks unlock the high contrast needed to observe and characterize exoplanets. The SCALES slenslit opens up new parameter space heretofore untapped by rearranging a small patch of lenslets into a pseudoslit before being dispersed at moderate spectral resolution (R∼ 2500 − 7500) over the SCALES bandpass while preserving the spatial resolution offered by the Keck AO system. The slenslit is being built in collaboration with the University of Durham’s Centre for Advanced Instrumentation.