Optical device having polarizer and non-active retarders for spectroscopic polarimetry

Patent metadata

Field	Value
Publication number	US-9645011-B2
Application number	US-96516510-A
Country	US
Kind code	B2
Filing date	Dec 10, 2010
Priority date	Mar 28, 2005
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

In the channeled spectroscopic polarimetry, a measurement error of a parameter showing a spectropolarization characteristic of a sample is effectively removed, the error being generated by various variations in retardation of a retarder depending upon the state of the sample. With attention being focused that the retardation of the retarder may be kept constant by stabilization of an incident direction of light that transmits through the retarder, the retarder was arranged on the light source side with respect to the sample so as to effectively remove an influence relative to a measurement error, such as variations in direction of a light ray due to the sample.

First claim

What is claimed is:

1. A method for spectroscopic polarimetry, comprising the steps of:
preparing an object to be measured;
preparing a polarimetric spectroscope which includes
a projection optical system, comprising a light source, a polarizer and a plurality of non-active retarders, where
said plurality of non-active retarders includes a second retarder mechanically fixed optically downstream from the polarizer with respect to the traveling direction of light and having a principal axis oriented differently from the transmission axis of the polarizer, and a first retarder mechanically fixed further optically downstream from the second retarder and having a principal axis oriented differently from the principal axis of the second retarder, and
the light source, the polarizer and the plurality of non-active retarders are arranged such that light emitted from the light source is irradiated on the object to be measured after passing through the polarizer and the plurality of non-active retarders in this order,
an analyzer for allowing light to transmit therethrough, the light having been emitted from the projection optical system and reflected on or transmitted through the object to be measured, and
a spectrometer for obtaining the spectral intensity of the light having transmitted through the analyzer, or the light source and a light receiver for receiving the light having transmitted through the analyzer wherein the light source scans a wavelength of the light so that the light receiver obtains the spectral intensity of the light in a time domain;

obtaining the spectral intensity of the object to be measured by use of the polarimetric spectroscope; and
obtaining at least one spectropolarization parameter of the object to be measured by use of the obtained spectral intensity without mechanically moving the non-active retarders and without electro-optically modulating the non-active retarders during an entire measurement for obtaining the at least one spectropolarization parameter of the object,
wherein the step of obtaining at least one of spectropolarization parameters is a step which comprises:
obtaining, from the spectral intensity, a spectral intensity component (first spectral intensity component) which nonperiodically vibrates with wavenumber and a spectral intensity component (third spectral intensity component) which vibrates at a frequency depending upon a retardation (φ 2 (σ)) of the second retarder and not depending upon a retardation (φ 1 (σ)) of the first retarder, with wavenumber; and
obtaining at least one of spectropolarization parameters by use of each of the spectral intensity components.

2. The method for spectroscopic polarimetry according to claim 1 , wherein the step of obtaining at least one of spectropolarization parameter is a step which comprises:
obtaining the retardation (φ 2 (σ)) of the second retarder from the third spectral intensity component; and
obtaining at least one spectropolarization parameter of the object to be measured by use of the spectral intensity and the retardation (φ 2 (σ)) of the second retarder.

3. The method for spectroscopic polarimetry according to claim 1 , further comprising a step of acquiring data showing the relation between the retardation (φ 1 (σ)) of the first retarder and the retardation (φ 2 (σ)) of the second retarder, wherein the step of obtaining at least one spectropolarization parameter is a step which comprises:
obtaining the retardation (φ 1 (σ)) of the first retarder and the retardation (φ 2 (σ)) of the second retarder from the third spectral intensity component and the data showing the relation between the retardation (φ 1 (σ)) of the first retarder and the retardation (φ 2 (σ)) of the second retarder; and
obtaining at least one spectropolarization parameter of the object to be measured by use of the spectral intensity, the retardation (φ 1 (σ)) of the first retarder and the retardation (φ 2 (σ)) of the second retarder.

4. A method for spectroscopic polarimetry, comprising the steps of:
preparing an object to be measured;
preparing a polarimetric spectroscope which includes
a projection optical system, comprising a light source, a polarizer and a plurality of non-active retarders, where

said plurality of non-active retarders includes a second retarder mechanically fixed optically downstream from the polarizer with respect to the traveling direction of light and having a principal axis oriented differently from the transmission axis of the polarizer, and a first retarder mechanically fixed further optically downstream from the second retarder and having a principal axis oriented differently from the principal axis of the second retarder, and
the light source, the polarizer and the plurality of non-active retarders are arranged such that light emitted from the light source is irradiated on the object to be measured after passing through the polarizer and the plurality of non-active retarders in this order,
an analyzer for allowing light to transmit therethrough, the light having been emitted from the projection optical system and reflected on or transmitted through the object to be measured, and
a spectrometer for obtaining the spectral intensity of the light having transmitted through the analyzer, or the light source and a light receiver for receiving the light having transmitted through the analyzer wherein the light source scans a wavelength of the light so that the light receiver obtains the spectral intensity of the light in a time domain;
obtaining the spectral intensity of the object to be measured by use of the polarimetric spectroscope; and
obtaining at least one spectropolarization parameter of the object to be measured by use of the obtained spectral intensity without mechanically moving the non-active retarders and without electro-optically modulating the non-active retarders during an entire measurement for obtaining the at least one spectropolarization parameter of the object,
wherein the step of obtaining at least one spectropolarization parameter is a step which comprises:
obtaining, from the spectral intensity, at least one of a spectral intensity component (second spectral intensity component) which vibrates at a frequency depending upon a variation between the retardation (φ 1 (σ)) of the first retarder and the retardation (φ 2 (σ)) of the second retarder with wavenumber, a spectral intensity component (fourth spectral intensity component) which vibrates at a frequency depending upon the sum of the retardation (φ 1 (σ)) of the first retarder and the retardation (φ 2 (σ)) of the second retarder with wavenumber, and a spectral intensity component (fifth spectral intensity component) which vibrates at a frequency depending upon the retardation (φ 1 (σ)) of the first retarder and not depending upon the retardation (φ 2 (σ)) of the second retarder, with wavenumber; and
obtaining at least one spectropolarization of the object to be measured by use of the obtained spectral intensity component.

5. The method for spectroscopic polarimetry according to claim 4 , wherein the step of obtaining at least one spectropolarization parameter is a step which comprises:
obtaining the second spectral intensity component and the fourth spectral intensity component;
obtaining the retardation (φ 2 (σ)) of the second retarder from the second spectral intensity component and the fourth spectral intensity component; and
obtaining at least one spectropolarization parameter of the object to be measured by use of the spectral intensity and the retardation (φ 2 (σ)) of the second retarder.

6. The method for spectroscopic polarimetry according to claim 4 , further comprising a step of acquiring data showing the relation between the retardation (φ 1 (σ)) of the first retarder and the retardation (φ 2 (σ)) of t

Assignees

• Okabe Hiroshi
• Matoba Kenichi
• Oka Kazuhiko
• Omron Tateisi Electronics Co
• Nat Univ Corp Hokkaido Univ

Inventors

• Okabe Hiroshi
• Matoba Kenichi
• Oka Kazuhiko

Classifications

• G01J4/04 Primary

  Polarimeters using electric detection means (G01J4/02 takes precedence) · CPC title

• E04G21/1808

  Holders for bricklayers' lines, bricklayers' bars; Sloping braces (cord-line chalkers B44D3/38) · CPC title

• E04G21/201 Primary

  Trowels · CPC title

• G01J3/447

  Polarisation spectrometry · CPC title

• E04G21/22

  for setting building elements with mortar, e.g. bricklaying machines · CPC title