Size metrology of a pure phase object based on the laser probe beam reshaping

Michael Fromager (1) , Marc Brunel (2) , Kamel Aït-Ameur (1)

1 CIMAP - UMR 6252 - Centre de recherche sur les Ions, les MAtériaux et la Photonique
2 CORIA - Complexe de recherche interprofessionnel en aérothermochimie

We propose a simple method for determining the size of a transparent object based on the reshaping of a laser probe beam which is initially Gaussian in shape. For a given ratio between the sizes of the incident beam and of the phase object, the diffracted laser probe beam is transformed in the far-field region into a hollow beam. The detection of the intensity dip in the beam centre is made with a simple photodiode. The potential of the proposed technique for quantifying the nanoscale change of the phase object could be very useful to study the dynamics of a living cell membrane for instance.

Mots clés: Laser beam shaping; Phase object; Diffraction

Domaines: Optique / photonique

Michael Fromager, Marc Brunel, Kamel Aït-Ameur. Size metrology of a pure phase object based on the laser probe beam reshaping. Optics and Lasers in Engineering, 2014, 54, pp.88-92. ⟨10.1016/j.optlaseng.2013.10.008⟩. ⟨hal-02112748⟩