US 6,646,743 B2 · Method and device for the spectral analysis of light

Abstract

The method utilizes the physical phenomenon known as dispersion of the optical rotation. After passage of linearly polarized electromagnetic radiation through the optically active environment (rotator), with the rotating power characterized by a parameter p, and then through the analyzing polarizer, the function R(p) can be measured. For the given active medium and the relative orientation of polarization planes of the input light beam and the analyzing polarizer, R(p) has an unambiguous relation with the spectrum I(λ) of the analyzed radiation (λ stands for wavelength) and allows its unambiguous determination by special mathematical methods. In devices based on the above mentioned principle a linearly polarized collimated beam of analyzed radiation propagates through the optical rotator then passes through the analyzer and strikes a single-channel or multi-channel detector which measures R(p) as a function of the parameter p. Finally the desired spectrum is calculated from the known functional relation between the measured rotogram R(p) and I(λ).

Claims51

Dependent claims

A method for determining spectral content of electromagnetic radiation comprising:

passing linearly polarized electromagnetic radiation through a rotator, the rotator being an element exhibiting wavelength dependent dispersion of a polarization angle which rotates a polarization plane of all spectral components of the electromagnetic polarized radiation by an angle determined by both a wavelength of the polarized electromagnetic radiation and a physical and/or geometric characteristic of the rotator represented by a parameter p, the parameter p representing an extent to which the polarization plane of all spectral components is rotated, the polarized electromagnetic radiation after passing through the rotator passes through an output polarizer and impinges upon a detector which measures an intensity of at least a single point of the polarized electromagnetic radiation for plural values of the parameter p which produces a set of intensity values comprising a mathematical function of p and wavelength from which at least spectral information is mathematically extracted;
and wherein
rotation of the polarization plane of all spectral components is not the same for any ray across an extent of the polarized electromagnetic radiation incident on a surface of the rotator.

An apparatus for performing spectral analysis comprising:

a rotator comprising at least two polarization rotating elements, each element rotating incident polarized electromagnetic radiation passing through the rotating element, the rotator having two faces with a first face receiving incident polarized electromagnetic radiation with the first face and a second face outputting polarized electromagnetic radiation after passing through the rotator, at least one pair of the at least two polarization rotating elements comprising opposed faces which form a non-orthogonal angle with the polarized electromagnetic radiation passing through the rotator with relative displacement of the at least two polarization rotating elements at an angle to a direction of the incident polarized electromagnetic radiation causing the polarized electromagnetic radiation passing through the rotator to be rotated;
and
an output polarization analyzer for analyzing the electromagnetic radiation which has passed through the rotator;
and wherein
the rotator comprises two pairs of polarization rotating elements with the first face being a face of one of the pairs of elements and the second face being a face of another of the pair of elements, each of the pairs of elements having two substantially parallel faces with one face thereof receiving incident polarized electromagnetic radiation at a substantially orthogonal angle with the one face and another face thereof outputting the polarized electromagnetic radiation at a substantially orthogonal angle and a pair of parallel opposed faces which form a non-orthogonal angle with the polarized electromagnetic radiation passing through the rotator with relative movement of the polarization rotating elements causing the polarized electromagnetic radiation passing through the rotator to be rotated.

2 more elements

A rotator comprising:

at least two polarization rotating elements, each element individually rotating incident polarized electromagnetic radiation passing through the rotating element, the rotator having two faces with a first face receiving incident polarized electromagnetic radiation and a second face outputting polarized electromagnetic radiation after passing through the rotator as only a single beam of polarized electromagnetic radiation, at lease one pair of the at least two polarization rotating elements having opposed faces which form a non-orthogonal angle with the polarized electromagnetic radiation passing through the rotator with relative displacement of the at least two polarization rotating elements at an angle to a direction of the incident polarized electromagnetic radiation causing the polarized electromagnetic radiation passing through the rotator to be rotated;
and
an output which outputs rotated polarized electromagnetic radiation.

Dependencies are inferred from the claim text.

Method and device for the spectral analysis of light

Life of this patent

Method and device for the spectral analysis of light

Life of this patent

Abstract

Claims51