X-ray micropore optic array preliminary calibration results for the lunar environment heliospheric x-ray imager

The Lunar Environment heliospheric X-ray Imager (LEXI) is a wide field-of-view soft X-ray imager built to monitor the shape and motion of Earth's magnetopause over multiple days. Set to land on the lunar surface as part of NASA's Commercial Lunar Payload Services (CLPS) program, LEXI will measure soft X-rays (0.1-2 keV) produced by the charge exchange between the solar wind and neutral atoms in the near-earth environment. LEXI focuses X-rays in its 9.1 degrees by 9.1 degrees field of view using a tiled 3 by 3 array of "lobster-eye" micropore optics (MPOs). LEXI's MPOs were first tested individually with a short range X-ray source to characterize the optics and select the best MPOs for flight. Once assembled into a flight array, the MPOs were tested in the PANTER X-ray beamline facility at multiple energies to determine the array's point spread function and effective area as a function of off-axis angle. We present preliminary calibration results of LEXI's individual MPO elements and assembled MPO array to qualify the instrument optics for flight.