OBSERVATIONS OF DARK SIDE OF THE UNIVERSE BY GRAVITATIONAL LENSING

It is now widely recognized that strong and weak gravitational lensing both play important roles in the observational cosmology. We shall here report our proposal and recent observation on the determination of the dark energy using strong gravitational lensing, and our recent analysis of weak shear field around Cl1604+4304 where we found mass concentration with no optical counterparts. Our recent weak shear observation by Subaru/S-Cam is also briefly mentioned.