Angular Misalignment Measurements For An Off-Plane Reflection Grating Module
Creators: name: Grell, Gabriel
name: Smith, R.
name: DeRoo, C.
name: Allured, R.
name: Hertz, E.
name: Kolodziejczak, J.
name: Gaskin, J.
name: O'Dell, S.
name: McEntaffer, R.
name: Miles, D.
Publisher: name: Zenodo
Year: 2016
Subjects: subject: reflection gratings
subject: http://astrothesaurus.org/uat/1554

description: We present an analysis of an alignment technique used for an off-plane reflection grating system that, if proven to be feasible, would ideally be utilized for future astronomical x-ray spectrometers. The use of reflection gratings allows for the production of both high throughput and spectral resolution. As such, they are a candidate grating technology for future soft X-ray spectroscopy missions. To be viable for these missions, however, a low-cost optical technique for co-aligning multiple gratings into a module for use in a spectrograph must be demonstrated. The off-plane grating module was built to contain fifteen gratings with proper relative alignment to one another for a converging X-ray beam. The module was coupled with a silicon pore optic mirror to produce a spectrum of reflected and diffracted light onto a CCD camera at the focal plane. The alignment performance of the module’s grating system was assessed both before and after a series of vibrational and thermal tests were conducted at the NASA Marshall Space Flight Center. Data reduction was done in order to identify the number and position of photon events from the diffraction spots for each grating, and raytracing analysis was conducted in order to calculate the induced grating-to-grating angular misalignments. Finally, these measurements were compared to theoretical alignment tolerances derived using analytical techniques. The grating system yielded misalignments within a factor of 2-3 of the analytical tolerances, which is very encouraging for a first attempt. Further refinement and troubleshooting is required to see whether or not this alignment technique can be used in the future.
description: Astro 98
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