A concept for a deployable normal incidence EUV mirror based on shape memory alloy sheets

Further progress toward enabling a deployable shape memory alloy normal incidence space telescope for the extreme ultraviolet

“…In order to determine if interesting EUV astronomy can be carried out with a figure error commensurate with the return-to-shape capabilities of a shape memory alloy (SMA) designed for a CuebSat or SmallSat, we carried out a preliminary proof-of-principle ray tracing study. 2 Here, we revisit the question of spot size from a typical return-to-shape 1 m diameter SMA mirror. As discussed in Ref.…”

“…Training or repeated thermomechanical actuation to the shape-set shape can stabilize the evolving microstructure and result in a precise return to the shape-set shape, e.g., to within 1 µm in our previous work. 2 Training elastically accommodates the mismatch resulting from the defects and the retained martensite, often being associated with a reduced internal stress field. The individual martensite units or variants can grow, coalesce or reorient to accommodate this mismatch elastically.…”

“…A detailed description of the surface preparation of the reflective coating of this polymer-silver coated piece (02072022) is given in. 2 The non-reflecting side was coated as follows: The thin films were grown by D.C. magnetron sputtering using an AJA ST20 sputtering source. The sputter chamber was at ground.…”