Design and fabrication of an active polynomial grating for soft-X-ray monochromators and spectrometers

Shean-Jen Chen*, C. T. Chen, S. Y. Perng, C. K. Kuan, T. C. Tseng, D. J. Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


An active polynomial grating has been designed for use in synchrotron radiation soft-X-ray monochromators and spectrometers. The grating can be dynamically adjusted to obtain the third-order-polynomial surface needed to eliminate the defocus and coma aberrations at any photon energy. Ray-tracing results confirm that a monochromator or spectrometer based on this active grating has nearly no aberration limit to the overall spectral resolution in the entire soft-X-ray region. The grating substrate is made of a precisely milled 17-4 PH stainless steel parallel plate, which is joined to a flexure-hinge bender shaped by wire electrical discharge machining. The substrate is grounded into a concave cylindrical shape with a nominal radius and then polished to achieve a roughness of 0.45 nm and a slope error of 1.2 μrad rms. The long trace profiler measurements show that the active grating can reach the desired third-order polynomial with a high degree of figure accuracy.

Original languageEnglish
Pages (from-to)298-301
Number of pages4
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
StatePublished - 21 Jul 2001


  • Active gratings
  • Adaptive optics
  • CEM
  • Monochromator
  • Soft X-ray beamline
  • Spectrometer

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