ALOHA/CHARA at 1.55 μm: sensitivity improvement and on-sky ability to detect astronomical sources in H band

The interferometric concept named ALOHA (Astronomical Light Optical Hybrid Analysis) offers an alternative for high resolution imaging in the mid-infrared domain by shifting the astronomical light to shorter wavelength where optical guided components from telecommunications are available and efficient. A prototype with two arms converting a signal from 1.55 μm to 630 nm is used to validate the concept in laboratory and on-sky. Thanks to collaboration with the CHARA team, photometric tests were achieved with a single arm of the interferometer and have allowed to predict instrument performance in its interferometric configuration in order to obtain first fringes in H band.

[1]  Christine Silberhorn,et al.  ALOHA @3,39 μm: implementation of the up-conversion interferometer in the L band , 2016, Astronomical Telescopes + Instrumentation.

[2]  Rafael Millan-Gabet,et al.  Jouvence of Fluor: Upgrades of a Fiber Beam Combiner at the CHARA Array , 2013 .

[3]  C. C. Wang,et al.  Nonlinear optics. , 1966, Applied optics.

[4]  Jean-Thomas Gomes,et al.  ALOHA project: how nonlinear optics can boost interferometry to propose a new generation of instrument for high-resolution imaging , 2016, Astronomical Telescopes + Instrumentation.

[5]  Christine Silberhorn,et al.  In-lab ALOHA mid-infrared up-conversion interferometer with high fringe contrast @λ = 3.39 μm , 2016 .

[6]  M. Fejer,et al.  Quasi-phase-matched second harmonic generation: tuning and tolerances , 1992 .

[7]  Phase closure retrieval in an infrared-to-visible upconversion interferometer for high resolution astronomical imaging. , 2011, Optics express.

[8]  B. Wirnitzer.  Bispectral analysis at low light levels and astronomical speckle masking , 1985 .

[9]  A. Greenaway,et al.  Estimation of spatial power spectra in speckle interferometry , 1979 .

[10]  F. Reynaud,et al.  Linear optical path modulation with lambda /200 accuracy using a fibre stretcher , 1993 .

[11]  Effect of spectral sampling on the temporal coherence analysis of a broadband source in a SFG interferometer. , 2015, Optics express.

[12]  N. Scott,et al.  ALOHA 1.55μm Implementation on the CHARA Telescope Array: On-Sky Sensitivity Tests , 2016 .

[13]  J. W. Goodman,et al.  Photon Limited Images and Their Restoration , 1976 .

[14]  M M Fejer,et al.  Influence of domain disorder on parametric noise in quasi-phase-matched quantum frequency converters. , 2010, Optics letters.

[15]  Laurent Delage,et al.  Contrast and phase closure acquisitions in photon counting regime using a frequency upconversion interferometer for high angular resolution imaging , 2013 .