Real time birefringent imaging spectrometer based on differential structure

Patent metadata

Field	Value
Publication number	US-9846080-B2
Application number	US-201515119489-A
Country	US
Kind code	B2
Filing date	Feb 11, 2015
Priority date	Feb 18, 2014
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

A real-time birefringent imaging spectrometer based on differential structure is provided. A polarization beam splitter to add an imaging branch is set. Meanwhile, the structure alters the conventional optical structure to the differential structure by setting another polarization beam splitter. Taking the difference between these two interferogram obtained by two branches of differential structure as the final interferogram and performing the required post-processing calculations produces the spectrum at each pixel. Common-mode error is intensively restrained due to the differential structure, and 50% of the optical loss is avoided because of casting off the analyzer; a high spatial resolution, high spectral resolution image is acquired by combining the high spatial resolution, colorful image with the low spatial resolution, high spectral resolution image.

First claim

What is claimed is:

1. A real-time birefringent imaging spectrometer based on differential structure, which comprises:
a object lens ( 1 ) provided to image the object;
a field stop ( 2 ) provided to limit the field of view;
a collimator lens ( 3 ) provided to collimate the objective light;
a lenslet array ( 4 ) provided to incorporate image replication;
a first polarizing beam splitter ( 51 ) provided to split the objective light into two orthogonally polarized components;
an imaging branch to receive the light reflected by said the first polarizing beam splitter ( 51 );
a spectral branch to receive the light transmitted by said the first polarizing beam splitter ( 51 ) via the lenslet array ( 4 );
a second polarizing beam splitter ( 71 ) provided to split the light transmitted by said spectral branch into two orthogonally polarized components;
a transmitted spectral branch to receive one of output lights from said second polarizing beam splitter ( 71 );
a reflected spectral branch to receive another of output lights from said second polarizing beam splitter ( 71 ).

2. The real-time birefringent imaging spectrometer based on differential structure claimed in claim 1 , wherein
an imaging branch comprising: an eye lens ( 52 ) provided to focus the light reflected by said the first polarizing beam splitter ( 51 ), and
a CCD of the imaging branch ( 53 ) provided to detect the light focused by said eye lens ( 52 );
a first half-wave plate ( 61 ) provided to change the polarization of the light transmitted by said the first polarizing beam splitter ( 51 ),
a first Nomarski prism ( 62 ) provided to split the light transmitted by said the first half-wave plate ( 61 ) into two orthogonally polarized components with an optical path difference,
a second half-wave plate ( 63 ) provided to change the polarization of the components split by said the first Nomarski prism ( 62 ),
a second Nomarski prism ( 64 ) provided to compensate the localization plane to be perpendicular to optical axis, and
a third half-wave plate ( 65 ) provided to change the polarization of the light transmitted by said the second Nomarski prism ( 64 );
a transmitted spectral branch comprising: a eye lens of transmitted spectral branch ( 72 ) provided to focus the light transmitted by said the second polarizing beam splitter ( 71 ), and
a CCD of transmitted spectral branch ( 73 ) provided to detect the light focused by said the eye lens of transmitted spectral branch ( 72 ); and
a reflected spectral branch comprising an eye lens of reflected spectral branch ( 74 ) provided to focus the light reflected by said the second polarizing beam splitter ( 71 ), and
a CCD of reflected spectral branch ( 75 ) provided to detect the light focused by said the eye lens of reflected spectral branch ( 74 ).

3. A real-time imaging spectral method based on the system claimed in claim 1 , which comprise the steps of:
(a) dividing the objective light into two orthogonally polarized components by a polarizing beam splitter;
(b) focusing the component reflected by the polarizing beam splitter onto a CCD and acquiring a high spatial resolution, colorful image of object;
(c) dividing the light transmitted by the polarizing beam splitter into two orthogonally polarized components by another polarizing beam splitter;
(d) focusing these two components onto two CCDs respectively and acquiring two sets of M×N sub-images of object;
(e) taking the difference of these two sets of M×N sub-images of object as the final sub-images;
(f) arranging the sub-images by values of optical path difference sequentially, so each sub-image samples a different “slice” of the 3D interferogram cube;
(g) performing the required preprocessing calculations;
(h) taking Fourier Transform of data on the optical path difference dimension at each spatial location, and therefore acquiring a low spatial resolution, high spectral resolution image;
(i) acquiring a high spatial resolution, high spectral resolution image by combining the high spatial resolution, colorful image with the low spatial resolution, high spectral resolution image by an appropriate interpolation.

4. A real-time imaging spectral method based on the system claimed in claim 2 , which comprise the steps of:
(a) dividing the objective light into two orthogonally polarized components by a polarizing beam splitter;
(b) focusing the component reflected by the polarizing beam splitter onto a CCD and acquiring a high spatial resolution, colorful image of object;
(c) dividing the light transmitted by the polarizing beam splitter into two orthogonally polarized components by another polarizing beam splitter;
(d) focusing these two components onto two CCDs respectively and acquiring two sets of M×N sub-images of object;
(e) taking the difference of these two sets of M×N sub-images of object as the final sub-images;
(f) arranging the sub-images by values of optical path difference sequentially, so each sub-image samples a different “slice” of the 3D interferogram cube;
(g) performing the required preprocessing calculations;
(h) taking Fourier Transform of data on the optical path difference dimension at each spatial location, and therefore acquiring a low spatial resolution, high spectral resolution image;
(i) acquiring a high spatial resolution, high spectral resolution image by combining the high spatial resolution, colorful image with the low spatial resolution, high spectral resolution image by an appropriate interpolation.

Assignees

• Harbin Inst Technology

Inventors

• Jin Peng
• Zhu Shuaishuai
• Zhang Yu
• Lin Jie

Classifications

• G01J3/453 Primary

  by correlation of the amplitudes · CPC title

• G01J3/447

  Polarisation spectrometry · CPC title

• G01J3/2823

  Imaging spectrometer · CPC title

• G01J3/0208

  using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction · CPC title