Spectral interferometry method and apparatus

Spectral interferometry apparatus, comprising an interferometer adapted to be excited by an optical source, the said interferometer comprising:

• object optics arranged to transfer a beam from the optical source to a target object to produce an object beam;
• reference optics arranged to produce a reference beam;
• displacing means arranged to displace at least one of the object beam and the reference beam to produce a relatively displaced object beam and a relatively displaced reference beam;
• wherein there is an optical path difference between the relatively displaced object beam and the relatively displaced reference beam generated in the interferometer;
• and
• optical spectrum dispersing means arranged to receive the two relatively displaced beams, and to disperse their spectral content onto a reading element;
• wherein in use the combination of the displacing means and the optical spectrum dispersing means is arranged to create an intrinsic optical delay between the wavetrains of the two relatively displaced object beam and the relatively displaced reference beam which can be used with the optical path difference in the interferometer to generate a channelled spectrum for the optical path difference in the interferometer on the reading element;
• and
• wherein the object optics includes object fibre optics comprising an object fibre end arranged to transmit the object beam and the reference optics includes reference fibre optics comprising a reference fibre end arranged to transmit the reference beam and the displacing means is arranged to move the relative positions of the object fibre end and the reference fibre end in order to produce the relatively displaced object beam and the relatively displaced reference beam.

Spectral interferometry apparatus, comprising an interferometer adapted to be excited by an optical source, the said interferometer comprising:

• object optics arranged to transfer a beam from the optical source to a target object to produce an object beam;
• reference optics arranged to produce a reference beam;
• displacing means arranged to displace at least one of the object beam and the reference beam to produce a relatively displaced object beam and a relatively displaced reference beam;
• wherein there is an optical path difference between the relatively displaced object beam and the relatively displaced reference beam generated in the interferometer;
• and
• optical spectrum dispersing means arranged to receive the two relatively displaced beams, and to disperse their spectral content onto a reading element;
• wherein in use the combination of the displacing means and the optical spectrum dispersing means is arranged to create an intrinsic optical delay between the wavetrains of the two relatively displaced object beam and the relatively displaced reference beam which can be used with the optical path difference in the interferometer to generate a channelled spectrum for the optical path difference in the interferometer on the reading element;
• and
• wherein one of the object optics or the reference optics includes fibre optics comprising a fibre end arranged to transmit a respective one of the object beam or the reference beam, and the displacing means is arranged to produce the relatively displaced object beam and the relatively displaced reference beam by movement of the fibre end.

Spectral interferometry apparatus according to any one of the preceding claims, wherein the said reading element comprises:

• a photodetector array;
• a CCD linear array;
• a two dimensional array of photodetectors;
• a two dimensional CCD array;
• or a point photodetector over which the dispersed spectrum is scanned.

Spectral interferometry apparatus according to any preceding claim, further comprising:

• third beam splitting means arranged between the displacing means and the optical spectrum dispersing means, the beam splitting means being arranged to receive the relatively displaced object beam and the relatively displaced reference beam to produce a third relatively displaced object beam and a third relatively displaced reference beam;
• third displacing means arranged to adjust the relative displacement of at least one of the third relatively displaced object beam and the third relatively displaced reference beam;
• third optical spectrum dispersing means arranged to receive the third relatively displaced object beam and the third relatively displaced reference beam, and to disperse their spectral content onto a second reading element;
• wherein in use the combination of the third displacing means and the third optical spectrum dispersing means is arranged to create a third intrinsic optical delay between the wavetrains of the third relatively displaced object beam and the third relatively displaced reference beam which can be used with the optical path difference in the interferometer to generate a channelled spectrum for the optical path difference in the interferometer on the third reading element.

A spectral interferometry method, comprising:

• using an interferometer to output an object beam and a reference beam;
• reflecting, deflecting or refracting at least one of said object beam and said reference beam in order to relatively displace at least one of the object beam and the reference beam to produce a relatively displaced object beam and a relatively displaced reference beam, wherein there is an optical path difference between the relatively displaced object beam and the relatively displaced reference beam generated in the interferometer;
• dispersing the two relatively displaced beams according to their optical spectral content onto a reading element using an optical spectrum dispersing means;
• wherein the combination of reflecting, refracting or refracting said object beam and said reference beam to produce a relatively displaced object beam and a relatively displaced reference beam and dispersing the two relatively displaced beams using a optical spectrum dispersing means leads to an intrinsic optical delay between the wavetrains in the two relatively displaced beams which can be used with the optical path difference in the interferometer to generate a channelled spectrum for the optical path difference in the interferometer.

A spectral interferometry method, comprising an interferometer adapted to be excited by an optical source, the said interferometer comprising object optics and reference optics, the method comprising:

• using the object optics to transfer a beam from the optical source to a target object to produce an object beam;
• using reference optics to produce a reference beam;
• using displacing means to displace at least one of the object beam and the reference beam to produce a relatively displaced object beam and a relatively displaced reference beam;
• wherein there is an optical path difference between the relatively displaced object beam and the relatively displaced reference beam generated in the interferometer;
• and
• using optical spectrum dispersing means to receive the two relatively displaced beams, and to disperse their spectral content onto a reading element;
• wherein the combination of the displacing means and the optical spectrum dispersing means is arranged to create an intrinsic optical delay between the wavetrains of the two relatively displaced object beam and the relatively displaced reference beam which can be used with the optical path difference in the interferometer to generate a channelled spectrum for the optical path difference in the interferometer on the reading element;
• and
• wherein the displacing means relatively displaces the object beam and the reference beam to produce the relatively displaced object beam and the relatively displaced reference beam using one or a combination of reflection, deflection, or refraction of at least one of the object beam and the reference beam.

A spectral interferometry method, comprising using an interferometer adapted to be excited by an optical source, the said interferometer including object optics and reference optics, the method comprising:

• using the object to transfer a beam from the optical source to a target object to produce an object beam;
• using reference optics to produce a reference beam;
• using displacing means to displace at least one of the object beam and the reference beam to produce a relatively displaced object beam and a relatively displaced reference beam;
• wherein there is an optical path difference between the relatively displaced object beam and the relatively displaced reference beam generated in the interferometer;
• and
• optical spectrum dispersing means arranged to receive the two relatively displaced beams, and to disperse their spectral content onto a reading element;
• wherein the combination of the displacing means and the optical spectrum dispersing means is arranged to create an intrinsic optical delay between the wavetrans of the two relatively displaced object beam and the relatively displaced reference beam which can be used with the optical path difference in the interferometer to generate a channelled spectrum for the optical path difference in the interferometer on the reading element;
• and
• wherein the object optics includes object fibre optics comprising an object fibre end arranged to transmit the object beam and the reference optics includes reference fibre optics comprising a reference fibre end arranged to transmit the reference beam and the displacing means moves the relative positions of the object fibre end and the reference fibre end in order to produce the relatively displaced object beam and the relatively displaced reference beam.

A spectral interferometry method, comprising using an interferometer adapted to be excited by an optical source, the said interferometer including object optics and reference optics, the method comprising:

• using object optics to transfer a beam from the optical source to a target object to produce an object beam;
• using reference optics to produce a reference beam;
• using displacing means to displace at least one of the object beam and the reference beam to produce a relatively displaced object beam and a relatively displaced reference beam;
• wherein there is an optical path difference between the relatively displaced object beam and the relatively displaced reference beam generated in the interferometer;
• and
• using optical spectrum dispersing means to receive the two relatively displaced beams, and to disperse their spectral content onto a reading element;
• wherein in use the combination of the displacing means and the optical spectrum dispersing means is arranged to create an intrinsic optical delay between the wavetrains of the two relatively displaced object beam and the relatively displaced reference beam which can be used with the optical path difference in the interferometer to generate a channelled spectrum for the optical path difference in the interferometer on the reading element;
• and
• wherein one of the object optics or the reference optics includes fibre optics comprising a fibre end arranged to transmit a respective one of the object beam or the reference beam, and the displacing means produces the relatively displaced object beam and the relatively displaced reference beam by movement of the fibre end.

Spectral interferometry apparatus, comprising an interferometer adapted to be excited by an optical source, the said interferometer comprising:

• a first optical path leading from the interferometer to a target object;
• a second optical path leading a reference light beam to displacing means;
• interface optics adapted to transfer an optical beam from the optical source to the target object along the first optical path, to transfer an optical output beam from the target object back to the interferometer along the said first optical path, and to transfer said optical output beam along a third optical path to the displacing means to produce an object beam;
• reference optics adapted to transfer the reference beam to the displacing means along the said second optical path;
• the displacing means being adapted to reflect the object beam and the reference beam in order to relatively displace the object beam and the reference beam to produce a relatively displaced object beam and a relatively displaced reference beam, wherein there is an optical path difference between the relatively displaced object beam and the relatively displaced reference beam generated in the interferometer;
• optical spectrum dispersing means adapted to receive the two relatively displaced beams, and to disperse their spectral content onto a reading element;
• wherein in use the combination of the displacing means and the optical spectrum dispersing means is arranged to create an intrinsic optical delay between the wavetrains of the two relatively displaced object beam and the relatively displaced reference beam which can be used with the optical path difference in the interferometer to generate a channelled spectrum for the optical path difference in the interferometer on the reading element;
• and
• processing means adapted to control the optical path difference between the relatively displaced object beam and the relatively displaced reference beam in the interferometer as well as the intrinsic optical path difference between the same beams.