Patent ID: 6819419
Filing Date: 2004-11-16
Classification: G01N

Abstract:
A method for illuminating particles contained in a medium for optical analysis, the medium being in contact with a window and subjected to a light beam that comes from a light source, through the window, and illuminates the particles to form an image of the particles; the window that is used comprising a trapezoidal prism, a longer side surface of the parallel side surfaces of which forms a surface facing the medium; the light beam being modified to provide a beam of a predetermined thickness in the direction of the window normal; the light beam being directed to pass through one of the oblique surfaces of the prism and to further travel inside the medium containing particles in the vicinity of the window surface making contact with the medium, substantially parallel to the surface, to thereby illuminate particles contained in a precisely predefined volume portion of the medium; and the image being formed by the light that is reflected back from the particles through the window, the method comprising: directing the light beam coming from the light source to pass in the vicinity of the prism with a mirror surface and a cylindrical lens, which direct the light beam to the prism and convert a shift of the light source to a change in the light beam angle.