System and method for height profile measurement of reflecting objects

An interferometric method for determining a height profile of a reflecting object with respect to a reference surface, the method comprising:

• obtaining an image of the reflecting object along a specular reflection axis, wherein said image corresponds to an intensity pattern projected on the reflecting object along a projection axis, and wherein said specular reflection axis corresponds to a direction along which a portion of said intensity pattern is specularly reflected by said reflecting object;
• calculating a reflecting object phase using said image;
• and
• determining said height profile using said reflecting object phase and a reference phase associated to the reference surface.

An interferometric method for determining a height profile of an object with respect to a reference surface, the method comprising:

• optimizing at least one of an orientation of the object, with respect to a projection axis and a detection axis, and an orientation of the detection axis, with respect to said object, to provide an optimized imaging configuration;
• wherein said optimized imaging configuration corresponds, in the case where a surface of the object is substantially reflecting, to a configuration that provides along the detection axis a specular reflection, by said surface, of at least a portion of the projected intensity pattern and wherein said optimized configuration corresponds, in the case where the surface of the object is substantially diffusing, to a configuration that does not provide along the detection axis a specular reflection by said surface of a portion of the projected intensity pattern;
• obtaining, at said optimized imaging configuration, an image of the object along said detection axis, wherein said image corresponds to an intensity pattern projected on the object along said projection axis;
• calculating an object phase using said image;
• and
• determining said height profile using said object phase and a reference phase associated to the reference surface.

An interferometric method for determining a height profile of an object with respect to a reference surface, the method comprising:

• obtaining a specular image of the object along a specular reflection axis, wherein said specular image corresponds to an intensity pattern projected on the object along a projection axis, and wherein said specular reflection axis corresponds to a direction along which a portion of said intensity pattern is specularly reflected by said object;
• obtaining a non-specular image of the object along a detection axis that is oriented differently from said specular reflection axis, wherein said non-specular image corresponds to said intensity pattern projected on the object along said projection axis;
• calculating an object phase using at least one of a portion of said specular image and a portion of said non-specular image;
• and
• determining said height profile using said object phase and a reference phase associated to the reference surface.

An interferometric system for determining a height profile of an object, the system comprising:

• a pattern projection assembly for projecting along a projection axis an intensity pattern on the object;
• a detection assembly for obtaining along a detection axis at least one image of the object, wherein said detection axis corresponds to a direction along which a portion of said intensity pattern is specularly reflected by said object;
• and
• a processor for establishing a phase of the object using said at least one image and for determining the height profile of said object using said object phase and a reference phase.