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Deep Broad-Band Infrared Nulling Using A Single-Mode Fiber Beam Combiner and Baseline RotationThe basic advantage of single-mode fibers for deep nulling applications resides in their spatial filtering ability, and has now long been known. However, and as suggested more recently, a single-mode fiber can also be used for direct coherent recombination of spatially separated beams, i.e. in a 'multi-axial' nulling scheme. After the first successful demonstration of deep (<2e-6) visible LASER nulls using this technique (Haguenauer & Serabyn, Applied Optics 2006), we decided to work on an infrared extension for ground based astronomical observations, e.g. using two or more off-axis sub-apertures of a large ground based telescope. In preparation for such a system, we built and tested a laboratory infrared fiber nuller working in a wavelength regime where atmospheric turbulence can be efficiently corrected, over a pass band (approx.1.5 to 1.8 micron) broad enough to provide reasonable sensitivity. In addition, since no snapshot images are readily accessible with a (single) fiber nuller, we also tested baseline rotation as an approach to detect off-axis companions while keeping a central null. This modulation technique is identical to the baseline rotation envisioned for the TPF-I space mission. Within this context, we report here on early laboratory results showing deep stable broad-band dual polarization infrared nulls <5e-4 (currently limited by detector noise), and visible LASER nulls better than 3e-4 over a 360 degree rotation of the baseline. While further work will take place in the laboratory to achieve deeper stable broad-band nulls and test off-axis sources detection through rotation, the emphasis will be put on bringing such a system to a telescope as soon as possible. Detection capability at the 500:1 contrast ratio in the K band (~2.2 microns) seem readily accessible within 50-100 mas of the optical axis, even with a first generation system mounted on a >5m AO equipped telescope such as the Palomar Hale 200 inch, the Keck, Subaru or Gemini telescopes.
Document ID
20060050170
Acquisition Source
Jet Propulsion Laboratory
Document Type
Preprint (Draft being sent to journal)
External Source(s)
Authors
Mennesson, Bertrand
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Haguenauer, P.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Serabyn, E.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Liewer, K.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2006
Subject Category
Optics
Meeting Information
Meeting: SPIE Conference on Astronomical Telescopes and Instrumentation
Location: Orlando, FL
Country: United States
Start Date: May 24, 2006
End Date: May 30, 2006
Sponsors: International Society for Optical Engineering
Distribution Limits
Public
Copyright
Other
Keywords
single mode fibers
Interferometry
Nulling
Infrared
High Contrast Imaging

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