Three hard X-ray telescopes (20-70 keV) have been produced for the High Energy Focusing Telescope (HEFT), a balloon-born mission. Each focusing, Wolter-I (conic approximation) optic was calibrated in-situ using low-force surface metrology as they were being assembled and at the Danish National Space Center (DNSC) using a high-resolution 8 keV X-ray source after assembly. The first optic was also calibrated using 18-68 keV X-rays at the European Synchrotron Radiation Facility (ESRF). We have

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... fully illuminated a prototype optic using a UV source and compared the result with the above techniques. During instrument integration, a 25 keV X-ray source at a distance of 72 m was used to align the optics and confirm the expected effective area and imaging performance. The successful development of HEFT has lead to NuSTAR, a Small Explorer (SMEX) satellite mission. We discuss these pre-flight calibration methods used in the HEFT program.