Dual beam tunable spectrometer

A dual beam tunable spectrometer comprising:

• a radiation source generating an incident radiative beam;
• an acousto-optic tunable filter receiving said incident radiative beam and generating therefrom a first-order beam;
• a first beam splitter arranged to receive said first-order beam and split said first-order beam into a reference beam and a sample beam;
• a second beam splitter arranged to receive said reference beam and convey at least part of said reference beam to a detector, said second beam splitter arranged to receive at least part of said sample beam emitted from a sample following illumination of the sample with said sample beam and to convey said part of said sample beam to said detector;
• and
• a shutter arrangement arranged to permit said detector to detect only one of said part of said reference beam and said part of said sample beam at any given time.

A dual beam tunable spectrometer comprising:

• a radiation source generating an incident radiative beam;
• an acousto-optic tunable filter receiving said incident radiative beam and generating therefrom a first-order beam;
• first conveying means for directing said incident radiative beam from said radiation source to said acousto-optic tunable filter;
• a first beam splitter arranged to receive said first-order beam and split said first-order beam into a reference beam and a sample beam;
• second conveying means for directing said first-order beam from said acousto-optic tunable filter to said first beam splitter;
• a second beam splitter arranged to receive said reference beam and convey at least part of said reference beam to a detector, said second beam splitter arranged to receive at least part of said sample beam emitted from a sample following illumination of the sample with said sample beam and to convey said part of said sample beam to said detector;
• third conveying means for directing said reference beam from said first beam splitter to said second beam splitter;
• fourth conveying means for directing said sample beam from said first beam splitter to the sample;
• fifth conveying means for directing said part of said sample beam from the sample to said second beam splitter;
• and
• a shutter arrangement including a first shutter disposed along said third conveying means to selectively permit passage therethrough of said reference beam, and a second shutter disposed along one of said fourth and fifth conveying means to selectively permit passage therethrough of said sample beam, said shutter arrangement opening said first shutter and closing said second shutter to permit said detector to detect only said part of said reference beam, said shutter arrangement closing said first shutter and opening said second shutter to permit said detector to detect only said part of said sample beam.

A dual beam tunable reflectance spectrometer comprising:

• a radiation source generating an incident radiative beam;
• an acousto-optic tunable filter receiving said incident radiative beam and generating therefrom first and second orthogonally-polarized first-order beams;
• a polarizing beam splitter arranged to convey at least part of said first first-order beam toward a detector and to direct at least part of said second first-order beam toward a sample at an incidence angle of approximately 90 degrees relative to the sample, said polarizing beam splitter further arranged to receive radiation reflected from the sample at a reflection angle of approximately 90 degrees relative to the sample and convey a randomly-polarized diffusely-reflected portion of the reflected radiation to said detector;
• first conveying means for directing said first first-order beam from said acousto-optic tunable filter into one side of said polarizing beam splitter, and second conveying means for directing said second first-order beam from said acousto-optic tunable filter into an opposite side of said polarizing beam splitter;
• and
• first and second shutters disposed along said respective first and second conveying means to selectively permit passage therethrough of said respective first and second first-order beams, said first and second shutters being operative to permit only one of said first and second first-order beams to reach said polarizing beam splitter at a given time.

A method of measuring the concentration of an analyte in a sample, comprising the steps of:

• generating an incident radiative beam with a radiation source;
• conveying the radiative beam to an acousto-optic tunable filter;
• generating a first-order beam with the acousto-optic tunable filter;
• splitting the first-order beam into a reference beam and a sample beam using a first beam splitter;
• conveying the reference beam from the first beam splitter to a second beam splitter;
• conveying a portion of the reference beam into a detector using the second beam splitter;
• cutting off conveyance of the reference beam to the second beam splitter using a shutter;
• conveying the sample beam to the sample and conveying a portion of the sample beam transmitted through or reflected from the sample to the second beam splitter;
• and
• conveying the portion of the sample beam into the detector via the second beam splitter.

A method of measuring the concentration of an analyte in a sample, comprising the steps of:

• generating an incident radiative beam with a radiation source;
• conveying the radiative beam to an acousto-optic tunable filter;
• generating first and second orthogonally-polarized first-order beams with the acousto-optic tunable filter, the first first-order beam corresponding to a reference beam and the second first-order beam corresponding to a sample beam;
• conveying the reference beam from the acousto-optic tunable filter to a polarizing beam splitter;
• conveying a portion of the reference beam into a detector using the polarizing beam splitter;
• cutting off conveyance of the reference beam to the polarizing beam splitter using a shutter;
• conveying the sample beam from the acousto-optic tunable filter to the polarizing beam splitter;
• conveying at least part of the sample beam toward the sample at an angle of approximately 90 degrees relative to the sample;
• and
• conveying a randomly-polarized diffusely-reflected portion of the sample beam to the detector via the polarizing beam splitter.