Patent ID: 7327457

Claim:
An apparatus for characterizing optical properties of a sample, comprising: a) a light source for generating a broadband beam; b) at least a first set of components defining a first light path, said components including at least a first component pair of a first planar mirror and a first parabolic mirror with a first focal length and a second component pair of a second planar mirror and a second parabolic mirror with a second focal length, wherein said broadband beam illuminates said first planar mirror and said first parabolic mirror in said first component pair and said second planar mirror and said second parabolic mirror in said second component pair at angles substantially near normal to said first planar mirror and said first parabolic mirror in said first component pair and said second planar mirror and said second parabolic mirror in said second component pair; wherein said first set of components is disposed between said source and said sample on said first light path; c) an element onto which said broadband beam is illuminated, wherein said broadband beam illuminates said element at angles substantially near normal to said element; and d) a means of mechanically displacing said second component pair without altering a position of said second parabolic mirror relative to said second planar mirror, whereby a focus position of said broadband beam can be altered without moving said first component pair.