To map the large-scale gravitational distortions our group is actively involved in three different programs :
 the VLT-Descart ESO key program : this program started in 1999. The survey covers 60 uncorrelated VLT/FORS fields in only I band. The total field of view is 0.65 square degrees.
 the VIRMOS-Descart CFHT survey : started by January 1999. It is based on CFH12K data covering 4 uncorrelated patches of 4 square-degree each in B,V, R and I bands.
 the CFHTLS Cosmic Shear Survey : started by February 2003 at CFHT with the new Megacam camera. It consists in 3 uncorrelated patches of about 7x7 square degrees each that will be observed in u', g', r', i' and z' bands. The total field of view is 10 times larger than the VIRMOS-Descart survey (170 square-degree instead of 16).

Introduction to cosmological weak lensing can be found in :
 Munshi, D., Valageas, P., van Waerbeke, L., Heavens, A. "Cosmology with Weak Lensing Surveys" astro-ph/0612667- Review paper submitted to Physics Reports.
 Lewis, A., Challinor, A. "Weak Gravitational Lensing of the CMB" astro-ph/0601594- Review paper submitted to Physics Reports.
 Schneider, P. "Weak Gravitational Lensing" astro-ph/0509252- Lecture Notes of the 33rd Saas-Fee Advanced Course, G. Meylan, P. Jetzer & P. North (eds.).
 van Waerbeke L., Mellier Y., "Gravitational Lensing by Large Scale Structures: A Review", astro-ph/0305089 published in the Aussois's Winter School Jan. 03 ;
 Mellier Y., "Probing the Universe with Weak Lensing", astro-ph/9812172 published in Annual Review of Astronomy and Astrophysics ;
 Bartelmann M., Schneider P., "Weak Gravitational Lensing", astro-ph/9912508 published in Physics Reports ;
 Bernardeau F., Colombi S., Gaztanaga E., Scoccimarro R., "Large-Scale Structure of the Universe and Cosmological Perturbation Theory", astro-ph/0112551 published in Physics Reports ;
 Cooray A., Sheth R., "Halo Models of Large Scale Structure", astro-ph/0206508 published in Physics Reports.
 Peebles P.J.E, Ratra B., "The Cosmological Constant and Dark Energy", astro-ph/0207347 published in Review of Modern Physics.
 Schneider P., "Gravitational lensing as a probe of structure", astro-ph/0306465 in XIV Canary Islands Winter School of Astrophysics "Dark Matter and Dark Energy in the Universe" Tenerife.
 Refregier A., "Weak Gravitational Lensing by Large-Scale Structure", astro-ph/0307212 published in Annual Review of Astronomy and Astrophysics ;