Multiaxial single-mode beam combiner

Wallner, Oswald; Armengol, Josep Maria Perdigués

doi:10.1117/12.551072

Cited by 21 publications

(15 citation statements)

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“…Such a sum can be achieved in an elegant and simple way thanks to a single-mode fiber optics. The efficiency of this cancelling device has actually been demonstrated (e.g., Wallner et al 2004;Buisset et al 2006). To obtain A(−u, v) = A(u, v), and because the sin(πuD) function is odd, it is sufficient to make sure that Sum (e jπPΛ − e jπQΛ ) · expUV(u, v) is even.…”

Section: The Multi-axial Chessboardsmentioning

confidence: 99%

The achromatic chessboard, a new concept of a phase shifter for nulling interferometry

Pelat

Rouan

Pickel

2010

A&A

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Context. Nulling interferometry in the mid-IR using two telescopes (commonly referred to a Bracewell interferometer) is one possible way of directly detecting exoplanets in the habitable zone and their characterisation in terms of possible life signatures. A large wavelength domain is needed to simultaneously detect the infrared spectral features of a set of a bio-tracers. An achromatic phase shift of π is then required, and we previously presented a new concept for such a function that allows a simple design with only one device per beam. It is based on two cellular mirrors, called the chessboards, where each cell has a thickness that introduces, for any given central wavelength, a phase shift of (2k + 1)π or of 2kπ on the fraction of the wave it reflects. Aims. We explore a more rigorous way to establish the optimum cell pattern design to attain the best theoretical performances for planet detection over a broad wavelength range. Two possible types of interferometres are now considered: on-axis and multi-axis. Methods. We derived a rather simple iterative scheme for both designs, determining the thickness and XY position of the cells. The method confers to the chessboards a high degree of internal symmetry. Each design can be described as an iterative Bracewell interferometer characterised by an integer order. We demonstrate that their efficiencies increases with the power of that order. Results. The device acts both spatially and versus wavelengths as an optical differential operator on the 3D light distribution. Its power is best understood in the on-axis case since its effect is to push away the stellar light from the centre over a very broad range of wavelengths, leaving space for an out of phase object to appear in the cleaned central region. We explore the theoretical performances for on-axis and multi-axis designs in the parameter space, and we especially compute the rejection factor for starlight and the attenuation factor for planet light and introduce the relative nulling efficiency metric. We show that, even with some realistic piston error added, the performances could meet the Darwin space project specifications for both designs, i.e., cancellation of the starlight by a factor of 10 5 over a wavelength range of 6-17 μm.

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Section: The Multi-axial Chessboardsmentioning

confidence: 99%

The achromatic chessboard, a new concept of a phase shifter for nulling interferometry

Pelat

Rouan

Pickel

2010

A&A

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“…3. This scheme was first proposed by Wallner et al (2004) and demonstrated experimentally by Haguenauer & Serabyn (2006) and Buisset (2006). We decided to make use of this property due to the simplicity of its implementation.…”

Section: Methodsmentioning

confidence: 99%

The achromatic chessboard, a new concept of a phase shifter for nulling interferometry

Pickel¹,

Pelat²,

Rouan³

et al. 2013

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Context. To find evidence one day of life on extra solar planets, one will have to directly detect photons of the exoplanet to obtain spectra and to look for specific spectroscopic features. One possible technique is dark fringe interferometry with several telescopes in space. This type of interferometry requires an achromatic π phase shift in one arm of an interferometer. We have already presented a concept of a quasi-achromatic phase shifter that is made of two cellular mirrors in which each cell position and phase shift is specific, so that the behavior of the null depth as a function of the wavelength is flat within a broad range. Aims. We want to experimentally validate this concept of an achromatic phase shifter and measure its performance in two different cases: a transmissive mask, which is made in bulk optics that are machined with ion etching and a reflective one, which is made by using a commercial segmented deformable mirror that is properly controlled. Methods. We assembled a dedicated optical bench, nicknamed DAMNED, to assess the concept and characterize its performance in the visible and to determine the limitations of this phase shifter. We analyze its performance by comparing the experimental results with a numerical instrument model. Results. We tested several transmissive masks and a reflective one. We reached an attenuation of about 2 × 10 −3 with a white source (Δλ = 430 to 830 nm) that proved to be the actual achromatic behavior of the phase shifter, despite its modest value. Extrapolated to mid-IR, its performance would be within typical specifications of a space mission as Darwin.

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“…This filter will affect the field distribution and therefore the rejection ratio. In the case of multi-axial nulling interferometry, an efficient way to perform wavefront filtering is to focus the light from the different beams into a unique single-mode fiber (positioned at the focus of the imaging system) (Mennesson et al 2002;Wallner et al 2004). In this section, we will study the filtering capabilities of a single-mode fiber with respect to the longitudinal polarization issue.…”

Section: Longitudinal Polarization and Single-mode Fibersmentioning

confidence: 99%

The effect of the longitudinal polarization component in multi-axial nulling interferometry for exoplanet detection

Spronck¹,

Pereira²

2009

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Multiaxial single-mode beam combiner

Cited by 21 publications

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The achromatic chessboard, a new concept of a phase shifter for nulling interferometry

The achromatic chessboard, a new concept of a phase shifter for nulling interferometry

The achromatic chessboard, a new concept of a phase shifter for nulling interferometry

The effect of the longitudinal polarization component in multi-axial nulling interferometry for exoplanet detection

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