Stress-balancing in piezoelectric adjustable x-ray optics

Nathan L. Bishop, Vladimir Kradinov, Paul B. Reid, Thomas N. Jackson, Casey Deroo, Susan Trolier-Mckinstry

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Next-generation x-ray observatories require lightweight, high throughput optics that maintain a <0.5 arcsec resolution to probe the physics of black holes and gain understanding of the early universe. One potential type of x-ray mirror consists of a 400-μm thick curved Corning EAGLE XG® glass substrate with a Cr/Ir x-ray mirror coating deposited on the front (concave) side and an array of radio frequency sputtered Pb0.995 (Zr0.52Ti0.48)0.99Nb0.01O3 piezoelectric thin film actuators on the back (convex) side to enable correction of figure errors. A stress-balancing process was developed to correct the figure distortion arising from thin film stresses in the actuator layers. Compressively stressed SiO2 films were deposited on the convex side of the mirror to balance the tensile integrated stress of the actuator array while also matching the film thickness distribution. Finite-element methods were used to assess the impact of film thickness distributions on the convex and concave substrate surfaces. The resulting models show peak-To-valley figure errors of 105 nm, well within the 1-μm peak-To-valley dynamic range of the piezoelectric adjusters. In contrast, when stress compensation was done with an iridium mirror film deposited on the front side, the mismatched thickness distribution results in peak-To-valley figure errors over 3 μm.

Original languageEnglish (US)
Article number029004
JournalJournal of Astronomical Telescopes, Instruments, and Systems
Volume8
Issue number2
DOIs
StatePublished - Apr 1 2022

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Control and Systems Engineering
  • Instrumentation
  • Astronomy and Astrophysics
  • Mechanical Engineering
  • Space and Planetary Science

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