The State-of-the-Art of Image Slicers: Best Performance and Characteristics Obtained in Glass and Metal

Image slicer technology is in high demand for the largest night-time and solar telescopes, as well as for space applications. The science cases that define the design and development for current instrumentation, and the next generation of instruments, require pushing image slicer technology beyond current limitations. The need for narrower slicer mirrors to achieve higher resolution, better surface roughness to reduce stray light, and innovative ideas for highly efficient Integral Field Spectrographs led two projects developed in the UK by a consortium between Durham University and University College London: MINOS and LUCES. MINOS has produced a prototype of slicer mirrors with the best results ever achieved in glass: a surface roughness of 0.2nm RMS in the thinnest glass slicers with a width of 70 microns on a spherical substrate, while LUCES investigates the best performance for metallic slicers using diamond machining producing nine demonstrators to determine the thinnest slicer width possible and the material that offers the best surface roughness. This communication presents the best performance currently achievable for glass and metallic image slicers.