Patent ID: 7759631

Claim:
A raster scanning microscope, adapted for sensing the position and/or movement of a micromechanical cantilever immersed in a fluid, said microscope comprising: a source for generating a first beam of radiation incident on said cantilever, a receiver for receiving a second beam of radiation reflected from said cantilever, and a first transparent optical element between said fluid and said source and/or said receiver, said first transparent optical element being in contact with said fluid and allowing said first and/or second beam to pass from said source through said fluid onto said cantilever and being reflected therefrom onto said receiver, said first transparent optical element including, at its inner side and contacting said fluid, an inner curved surface whose center of curvature is located at a desired focal point of said first beam of radiation, so that, independent of the index of refraction of said fluid, said first beam remains focused on said cantilever and said second beam remains focused on said receiver, and said first transparent optical element being horizontally inclined so that the tangent to the curvature at one edge of the inner curved surface is at least horizontal, thus avoiding the trapping of gas bubbles at said inner curved surface.