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US 6,687,012 B2Granted
Apparatus and method for measuring optical activity
AssigneeFordham University
InventorMartin Sanzari
Life of this patent
Estimating the term…
Abstract
The change in the circular birefringence of a sample is measured by passing a light beam comprised of a left circularly polarized (LCP) wave and a right circularly polarized (RCP) wave through a sample and measuring the change in the phase difference between the RCP and LCP waves.
Claims27
An apparatus for measuring the circular birefringence of a sample comprising:
- (a) a reference polarizer positioned to receive a reference beam having a right circularly polarized (RCP) wave characterized by a first frequency and a left circularly polarized (LCP) wave characterized by a second frequency, the reference polarizer producing a reference heterodyne wave, the reference heterodyne wave characterized by a reference phase, the reference phase representing the difference between the RCP wave and the LCP wave of the reference beam;
- (b) a reference detector positioned to receive the reference heterodyne wave and generate a reference signal;
- (c) a measurement polarizer positioned to receive a measurement beam exiting the sample, the measurement beam having a RCP wave characterized by the first frequency and a LCP wave characterized by the second frequency, the measurement polarizer producing a measurement heterodyne wave, the measurement heterodyne wave characterized by a measurement phase, the measurement phase representing the difference between the RCP wave and the LCP wave of the measurement beam;
- (d) a sample detector positioned to receive the measurement heterodyne wave and generate a measurement signal;
- (e) a gain/phase meter connected to the reference detector and sample detector and generating an output signal characterized by a phase difference equal to the difference between the measurement phase and the reference phase;
- and
- (f) a control program capable of execution on a processor, the control program calculating the circular birefringence of the sample based, in part, on the output signal of the gain/phase meter.
4 more elements
A method for determining the circular birefringence of a sample comprising the steps of:
- (a) generating a coherent light beam having a left circularly polarized (LCP) wave and a right circularly polarized (RCP) wave, the light beam characterized by a phase;
- (b) splitting the light beam into a measurement beam and a reference beam;
- (c) passing the measurement beam through a blank sample;
- (d) measuring a first phase difference between the measurement beam and reference beam;
- (e) replacing the blank with the sample and passing the measurement beam through the sample;
- (f) measuring a second phase difference between the measurement beam and reference beam;
- and
- (g) determining the circular birefringence of the sample based, in part, on the first and second phase difference.
5 more elements
A method for determining the circular birefringence of a sample comprising the steps of:
- (a) generating a coherent light beam having a left circularly polarized (LCP) wave and a right circularly polarized (RCP) wave, the light beam characterized by a phase;
- (b) splitting the light beam into a measurement beam and a reference beam;
- (c) passing the measurement beam through a sample;
- (d) measuring a phase difference between the measurement beam and reference beam;
- (e) repeating steps (c) and (d) at least once thereby measuring a plurality of phase differences;
- and
- (f) determining the circular birefringence of the sample based, in part, on the plurality of phase differences.
4 more elements
A method for measuring the change of the circular birefringence of a sample comprising the steps of:
- (a) propagating a beam through a sample, the beam having a first wave characterized by a first polarization state and a second wave characterized by a second polarization state that is orthogonal to the first polarization state, the beam further characterized by a phase difference between the first and second wave;
- and
- (b) measuring the change of the phase difference of the beam.
An apparatus for measuring the circular birefringence of a sample comprising:
- (a) a light beam generator generating a light beam having a right circularly polarized (RCP) wave characterized by a first frequency and a left circularly polarized (LCP) wave characterized by a second frequency;
- (b) a beam splitter positioned to receive the light beam from the beam generator and produce a measurement beam and a reference beam;
- (c) a reference polarizer positioned to receive the reference beam and produce a reference heterodyne wave, the reference heterodyne wave characterized by a reference phase, the reference phase representing the difference between the RCP wave and the LCP wave of the reference beam;
- (d) a reference detector positioned to receive the reference heterodyne wave and generate a reference signal;
- (e) a measurement polarizer positioned to receive the measurement beam exiting the sample and produce a measurement heterodyne wave, the measurement heterodyne wave characterized by a measurement phase, the measurement phase representing the difference between the RCP wave and the LCP wave of the measurement beam;
- (f) a sample detector positioned to receive the measurement heterodyne wave and generate a measurement signal;
- (g) a gain/phase meter connected to the reference detector and sample detector and generating an output signal characterized by a phase difference equal to the difference between the measurement phase and the reference phase;
- and
- (h) a processor connected to the gain/phase meter, the processor calculating the circular birefringence of the sample based, in part, on the output signal of the gain/phase meter.
6 more elements
An apparatus for measuring the circular birefringence of a sample comprising:
- (a) a light beam generator generating a light beam having a first linearly polarized (1LP) wave characterized by a first frequency and a first polarization plane and a second linearly polarized (2LP) wave characterized by a second frequency and a second polarization plane, wherein the first polarization plane is orthogonal to the second polarization plane;
- (b) a quarter-wave plate positioned to receive the light beam and convert the first and second linearly polarized waves to a right circularly polarized (RCP) wave and a left circularly polarized (LCP) wave;
- (c) a beam splitter positioned to receive the light beam from the quarter-wave plate and produce a measurement beam and a reference beam;
- (d) a reference polarizer positioned to receive the reference beam and produce a reference heterodyne wave, the reference heterodyne wave characterized by a reference phase, the reference phase representing the difference between the RCP wave and the LCP wave of the reference beam;
- (e) a reference detector positioned to receive the reference heterodyne wave and generate a reference signal;
- (f) a measurement polarizer positioned to receive the measurement beam exiting the sample and produce a measurement heterodyne wave, the measurement heterodyne wave characterized by a measurement phase, the measurement phase representing the difference between the RCP wave and the LCP wave of the measurement beam;
- (g) a sample detector positioned to receive the measurement heterodyne wave and generate a measurement signal;
- (h) a gain/phase meter connected to the reference detector and sample detector and generating an output signal characterized by a phase difference equal to the difference between the measurement phase and the reference phase;
- and
- (i) a processor connected to the gain/phase meter, the processor calculating the circular birefringence of the sample based, in part, on the output signal of the gain/phase meter.
7 more elements
Dependencies are inferred from the claim text.