Abstract-Terahertz adaptive optics with a deformable mirror

Mathilde Brossard, Jean-François Sauvage, Mathias Perrin, and Emmanuel Abraham

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-7-1594&origin=search

We report on the wavefront correction of a terahertz (THz) beam using adaptive optics, which requires both a wavefront sensor that is able to sense the optical aberrations, as well as a wavefront corrector. The wavefront sensor relies on a direct 2D electro-optic imaging system composed of a ZnTe crystal and a CMOS camera. By measuring the phase variation of the THz electric field in the crystal, we were able to minimize the geometrical aberrations of the beam, thanks to the action of a deformable mirror. This phase control will open the route to THz adaptive optics in order to optimize the THz beam quality for both practical and fundamental applications.

© 2018 Optical Society of America

Abstract- Interferometric Terahertz Wavefront Analysis

 Emmanuel Abraham,  Takayuki Ogawa,  Mathilde Brossard,   Takeshi Yasu

http://ieeexplore.ieee.org/document/7781635/

Wavefront characterization of terahertz beams is useful for various applications such as terahertz spectroscopy and imaging. In this paper, we report on the aberration measurement of a terahertz beam issued from a quantum cascade laser. By using a terahertz camera and a two-wave noncommon path interferometer, we measured the wavefront distortions. As an example, we evaluated the Zernike coefficients giving the aberrations of spherical wavefronts induced by a converging lens. Associated with a deformable mirror, the sensor will open the route to terahertz adaptive optics.

Abstract-Development of a wavefront sensor for terahertz pulses

Emmanuel Abraham, Harsono Cahyadi, Mathilde Brossard, Jérôme Degert, Eric Freysz, and Takeshi Yasui
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-5-5203

Wavefront characterization of terahertz pulses is essential to optimize far-field intensity distribution of time-domain (imaging) spectrometers or increase the peak power of intense terahertz sources. In this paper, we report on the wavefront measurement of terahertz pulses using a Hartmann sensor associated with a 2D electro-optic imaging system composed of a ZnTe crystal and a CMOS camera. We quantitatively determined the deformations of planar and converging spherical wavefronts using the modal Zernike reconstruction least-squares method. Associated with deformable mirrors, the sensor will also open the route to terahertz adaptive optics.

© 2016 Optical Society of America

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