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Efficient photonic reformatting of celestial light for diffraction-limited spectroscopy.
- Source :
- Monthly Notices of the Royal Astronomical Society; 2/1/2017, Vol. 464 Issue 4, p4950-4957, 8p
- Publication Year :
- 2017
-
Abstract
- The spectral resolution of a dispersive astronomical spectrograph is limited by the trade-off between throughput and the width of the entrance slit. Photonic guided wave transitions have been proposed as a route to bypass this trade-off, by enabling the efficient reformatting of incoherent seeing-limited light collected by the telescope into a linear array of single modes: a pseudo-slit which is highly multimode in one axis but diffraction-limited in the dispersion axis of the spectrograph. It is anticipated that the size of a single-object spectrograph fed with light in this manner would be essentially independent of the telescope aperture size. A further anticipated benefit is that such spectrographs would be free of 'modal noise', a phenomenon that occurs in high-resolution multimode fibre-fed spectrographs due to the coherent nature of the telescope point spread function (PSF). We seek to address these aspects by integrating a multicore fibre photonic lantern with an ultrafast laser inscribed three-dimensional waveguide interconnect to spatially reformat the modes within the PSF into a diffraction-limited pseudo-slit. Using the CANARY adaptive optics (AO) demonstrator on the William Herschel Telescope, and 1530 ± 80 nm stellar light, the device exhibits a transmission of 47-53 per cent depending upon the mode of AO correction applied. We also show the advantage of using AO to couple light into such a device by sampling only the core of the CANARY PSF. This result underscores the possibility that a fully optimized guided-wave device can be used with AO to provide efficient spectroscopy at high spectral resolution. [ABSTRACT FROM AUTHOR]
- Subjects :
- PHOTONICS
SPECTROGRAPHS
THEORY of wave motion
DIFFRACTION gratings
ADAPTIVE optics
Subjects
Details
- Language :
- English
- ISSN :
- 00358711
- Volume :
- 464
- Issue :
- 4
- Database :
- Complementary Index
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Publication Type :
- Academic Journal
- Accession number :
- 120347606
- Full Text :
- https://doi.org/10.1093/mnras/stw2558