Apparatus and method(s) for reducing the effects of coherent artifacts in an interferometer

An interferometric apparatus having an optical axis, said interferometric apparatus comprising:

• means for locating an object to be measured along the optical axis;
• an optical arrangement adapted to at least in part cooperate with an object to form an interferometer and facilitate the generation of interfering wavefronts in which phase information about the object is encoded;
• and
• means for directing radiation onto the object to be measured from at least two different locations that are distant from said optical axis to generate interfering wavefronts corresponding to each of said locations where each wavefront contains substantially identical phase information about the object from said interferometer,
• wherein said means for directing radiation comprises a point source and an arrangement for optically rotating said point source around said optical axis at a predetermined rate such that radiation emanating from said point source appears to be originating from said two different locations, said arrangement comprising a pair of serially arranged acousto-optic modulators.

An interferometric apparatus having an optical axis, said interferometric apparatus comprising:

• means for locating an object to be measured along the optical axis;
• an optical arrangement adapted to at least in part cooperate with an object to form an interferometer and facilitate the generation of interfering wavefronts in which phase information about the object is encoded;
• and
• means for directing radiation onto the object to be measured from at least two different locations that are distant from said optical axis to generate interfering wavefronts corresponding to each of said locations where each wavefront contains substantially identical phase information about the object from said interferometer,
• wherein said means for directing radiation comprises a point source and an arrangement for optically rotating said point source around said optical axis at a predetermined rate such that radiation emanating from said point source appears to be originating from said two different locations, said arrangement comprising a pair of serially arranged electro-optic modulators.

An interferometric apparatus having an optical axis, said interferometric apparatus comprising:

• means for locating an object to be measured along the optical axis;
• an optical arrangement adapted to at least in part cooperate with an object to form an interferometer and facilitate the generation of interfering wavefronts in which phase information about the object is encoded;
• and
• means for directing radiation onto the object to be measured from at least two different locations that are distant from said optical axis to generate interfering wavefronts corresponding to each of said locations where each wavefront contains substantially identical phase information about the object from said interferometer,
• wherein said means for directing radiation comprises a point source and a fiber face plate having an input end for accepting radiation from said point source and an output end arranged so that radiation emanating from said point source appears to be originating from said two different locations.

An interferometric apparatus having an optical axis, said interferometric apparatus comprising:

• means for locating an object to be measured along the optical axis;
• an optical arrangement adapted to at least in part cooperate with an object to form an interferometer and facilitate the generation of interfering wavefronts in which phase information about the object is encoded;
• and
• means for directing radiation onto the object to be measured from at least two different locations that are distant from said optical axis to generate interfering wavefronts corresponding to each of said locations where each wavefront contains substantially identical phase information about the object from said interferometer,
• wherein said means for directing radiation toward an object comprises means for assuring that radiation emanating from said two locations is substantially mutually incoherent with respect to one another.

An interferometric method for use with an interferometer having an optical axis, said interferometric method comprising the steps of:

• locating an object to be measured along the optical axis;
• providing an optical arrangement adapted to at least in part cooperate with an object to form an interferometer and facilitate the generation of interfering wavefronts in which phase information about the object is encoded;
• and
• directing radiation onto the object to be measured from at least two different locations that are distant from said optical axis to generate interfering wavefronts corresponding to each of said locations where each wavefront contains substantially identical phase information about the object from said interferometer,
• wherein said radiation directing step comprises forming at least one thin ring of illumination all points of which are distant from said optical axis such that said two locations are encompassed by said thin ring of illumination, said thin ring of illumination being formed by directing light onto a holographic diffuser element.

An interferometric method for use with an interferometer having an optical axis, said interferometric method comprising:

• locating an object to be measured along the optical axis;
• providing an optical arrangement adapted to at least in part cooperate with an object to form an interferometer and facilitate the generation of interfering wavefronts in which phase information about the object is encoded;
• and
• directing radiation onto the object to be measured from at least two different locations that are distant from said optical axis to generate interfering wavefronts corresponding to each of said locations where each wavefront contains substantially identical phase information about the object from said interferometer,
• wherein said step of directing radiation toward an object comprises the further step of assuring that radiation emanating from said two locations is substantially mutually incoherent with respect to one another.