Patent ID: 8300993

Claim:
Apparatus for illuminating a sample for analysis, the apparatus comprising: a light source for providing a light beam along a propagation vector, the light beam having a beam diameter; a planar waveguide oriented such that the propagation vector is perpendicular to the normal vector of the planar waveguide and the light beam is offset from the planar waveguide in a direction parallel to the normal vector of the planar waveguide; and a refractive volume for optically coupling the light beam to the planar waveguide, the refractive volume positioned proximate to the planar waveguide; wherein the refractive volume is configured for refracting the light beam such that the light beam strikes a planar surface of the planar waveguide at a non-zero internal propagation angle relative to an optical axis of the planar waveguide for all light within the beam diameter, and wherein an internal propagation angle of the light beam in the planar waveguide is tuned by a relative translation of the light source in a direction parallel to the normal vector of the planar waveguide.