CN103115683B - Method of measuring monochromatic light polarization state - Google Patents

Abstract

The invention discloses a method of measuring a monochromatic light polarization state and belongs to the technical field of photoelectric detecting. The method of measuring the monochromatic light polarization state solves the problems that an existing measuring method of a light polarization state can just measure a specific wavelength and efficiency is low. The method of measuring the monochromatic light polarization state is sequentially provided with a main polarization piece and a charge coupled device (CCD) detector along a direction vertical to the direction from which a monochromatic light path is emitted so that monochromatic light goes through the main polarization piece and is emitted to a light receiving face of the CCD detector. The direction of a light shaft of the monochromatic light is taken as the direction of a Z axis of a three-dimensional coordinate system. By collection of the CCD detector, transmission light intensity is obtained after the emitted monochromatic light goes through the main polarization piece, the main polarization piece is rotated for N times so that included angles of a transmission light shaft and a Y axis are different after every rotation of the main polarization piece. Every time the main polarization piece is rotated, transmission light intensity is collected, and calculation is performed. The emitted monochromatic light polarization state is obtained according to calculation of all the included angles of the transmission light shaft and the Y axis of the main polarization state and transmission light intensity correspondingly collected and obtained by the CCD detector. The method of measuring the monochromatic light polarization state is suitable for measuring monochromatic light polarization states.

Description

Measure the method for monochromatic light polarization state

Technical field

The method that the present invention relates to measure monochromatic light polarization state, belongs to photoelectric detection technology field.

Background technology

Polarized light has a wide range of applications in science and technology and commercial production.The development that the measuring technique of polarized light is also applied along with polarized light.

What use was maximum at present is stokes parameter measuring method.Its measuring principle is that, in light path to be measured, the optical axis direction of adjusting polaroid and quarter wave plate, measures and obtain transmitted light intensity, by the calculating of output signal being tried to achieve to the Stokes Stokes parameter for the treatment of photometry.When measurement, can, by polaroid optical axis and quarter wave plate quick shaft direction in rotation light path, obtain at least 6 group light intensity values; Also can be first after incident light light splitting, every Shu Guang records light intensity after the polaroid of the different optical axises that fix and quick shaft direction and quarter wave plate combination.Because the method has been used quarter wave plate, a specific device can only be measured for the light of a certain specific wavelength, while measuring other wavelength light, need to change the quarter wave plate that its wavelength is corresponding, and this has limited the efficiency of polarized light measurement to a great extent.

Summary of the invention

The present invention existingly can only measure for the light of a certain specific wavelength the measuring method of polarisation of light state in order to solve, and inefficient problem, provides a kind of method of measuring monochromatic light polarization state.

The method of measurement monochromatic light polarization state of the present invention, it comprises the following steps:

Step 1: along arranging successively main polaroid and ccd detector perpendicular to the direction of incident monochromatic light light path, make monochromatic light be incident to the light receiving surface of ccd detector after main polaroid, wherein the direction of monochromatic light optical axis is as the Z-direction of three-dimensional system of coordinate;

Step 2: obtain the transmitted light intensity of incident monochromatic light after main polaroid by ccd detector collection;

Step 3: rotate main polaroid N time, make the each postrotational light transmission shaft of main polaroid different from the angle of Y-axis, rotate after main polaroid repeating step two at every turn; Then perform step four; Wherein N is equal to, or greater than 6 natural number;

Step 4: calculate the monochromatic polarization state of acquisition incident with angle and the corresponding transmitted light intensity obtaining that gathers of ccd detector of Y-axis according to the light transmission shaft of each main polaroid.

It is further comprising the steps of:

Step 5: the XY rotation with in surface Y direction in three-dimensional system of coordinate, then calculate and obtain the monochromatic polarization state of incident according to the method in step 4, and judge that obtaining incident monochromatic light is elliptically polarized light or partial poolarized light.

It is further comprising the steps of:

Step 6: perpendicular to the direction of monochromatic light light path, additional polaroid is set before ccd detector;

Step 7: obtain the transmitted light intensity of incident monochromatic light after additional polaroid by ccd detector collection; Then perform step three and step 4, and judge that obtaining incident monochromatic light is circularly polarized light or natural light.

The concrete grammar that calculates the monochromatic polarization state of acquisition incident in step 4 is:

The transmitted light intensity I obtaining according to ccd detector collection:

$I=E_x^2{\sin }^2\mathrm{\θ}+E_y^2{\cos }^2\mathrm{\θ}+E_x{E}_y\sin 2\mathrm{\θ}\cos \mathrm{\α}+\frac{I_0}{2}+n(E_x^2{\cos }^2\mathrm{\θ}+E_y^2{\sin }^2\mathrm{\θ}+E_x{E}_y\sin 2\mathrm{\θ}\cos \mathrm{\α}+\frac{I_0}{2}),$

$=({\sin }^2\mathrm{\θ}+n{\cos }^2\mathrm{\θ})E_x^2+({\cos }^2\mathrm{\θ}+n{\sin }^2)E_y^2+(1+n)E_x{E}_y\sin 2\mathrm{\θ}\cos \mathrm{\α}+(1+n)\frac{I_0}{2}$

Wherein E _xfor X-direction electric field intensity intensity, E _yfor Y direction electric field intensity intensity, the light transmission shaft that θ is main polaroid and the angle of Y-axis, α is E _ywith respect to E _yphasic difference, I ₀for the intensity of equivalent natural light in incident monochromatic light, the extinctivity that n is main polaroid,

The angle theta transmitted light intensity I substitution above formula that corresponding collection obtains with ccd detector by the light transmission shaft of the main polaroid of above-mentioned each acquisition with Y-axis, calculates and obtains E _x, E _y, α, I ₀, obtain the monochromatic polarization state of incident.

Advantage of the present invention: a main polaroid and ccd detector are only used in the realization of the inventive method, and embodiment is simple, workable, is extremely applicable to carrying out in laboratory the measuring polarization state of simple high-precision; It can measure the polarization state of any wavelength incident light the distribution that can measure incident light polarization state.

In people's traditional understanding, polaroid can only be distinguished linearly polarized light and elliptically polarized light.The present invention has overcome technology prejudice, has realized and has used the measurement of polaroid to various polarized light polarization states.

Brief description of the drawings

Fig. 1 is the measuring principle figure of the method for measurement monochromatic light polarization state of the present invention;

Fig. 2 is the optical axis rotation schematic diagram of main polaroid; E in figure _x', E _y' be the XY rotation with in surface Y-axis in three-dimensional system of coordinate after, with E _x, E _ycorresponding variable;

Fig. 3 is the matching schematic diagram of the incident monochromatic light polarization state polarization state curve theoretical with it of experiment measuring acquisition, and wherein curve is the monochromatic theoretical polarization state curve of incident, and trigpoint is experiment measuring point.

Embodiment

Embodiment one: below in conjunction with Fig. 1 and Fig. 2, present embodiment is described, measures the method for monochromatic light polarization state described in present embodiment, it comprises the following steps:

Step 1: along arranging successively main polaroid 1 and ccd detector 2 perpendicular to the direction of incident monochromatic light light path, make monochromatic light be incident to the light receiving surface of ccd detector 2 after main polaroid 1, wherein the direction of monochromatic light optical axis is as the Z-direction of three-dimensional system of coordinate;

Step 2: gather and obtain the transmitted light intensity of incident monochromatic light after main polaroid 1 by ccd detector 2;

Step 3: rotate main polaroid 1N time, make the each postrotational light transmission shaft of main polaroid 1 different from the angle of Y-axis, rotate after main polaroid 1 repeating step two at every turn; Then perform step four; Wherein N is equal to, or greater than 6 natural number;

Step 4: calculate the monochromatic polarization state of acquisition incident with angle and the corresponding transmitted light intensity obtaining that gathers of ccd detector 2 of Y-axis according to the light transmission shaft of each main polaroid 1.

Embodiment two: present embodiment is that present embodiment is further comprising the steps of to the further illustrating of embodiment one:

Step 5: the XY rotation with in surface Y direction in three-dimensional system of coordinate, then calculate and obtain the monochromatic polarization state of incident according to the method in step 4, and judge that obtaining incident monochromatic light is elliptically polarized light or partial poolarized light.

Present embodiment cannot be distinguished elliptically polarized light and partial polarization light time at embodiment one, be cos α=0 o'clock, the step of carrying out, it is by rotation three-dimensional system of coordinate, the light transmission shaft of main polaroid 1 and the angle theta of Y-axis are changed, recalculate and can solve the monochromatic polarization state of incident.

Embodiment three: present embodiment is that present embodiment is further comprising the steps of to the further illustrating of embodiment two:

Step 6: perpendicular to the direction of monochromatic light light path, additional polaroid 3 is set before ccd detector 2;

Step 7: gather and obtain the transmitted light intensity of incident monochromatic light after additional polaroid 3 by ccd detector 2; Then perform step three and step 4, and judge that obtaining incident monochromatic light is circularly polarized light or natural light.

Described in present embodiment, additional 3 of polaroids just can be used in the time cannot distinguishing circularly polarized light and natural light, and the not corresponding specific wavelength of this additional polaroid 3, is any one polaroid.

Embodiment four: below in conjunction with Fig. 1 to Fig. 3, present embodiment is described, present embodiment is to the further illustrating of embodiment one, two or three, in step 4, calculate the concrete grammar that obtains the monochromatic polarization state of incident described in present embodiment and be:

Gather according to ccd detector 2 the transmitted light intensity I obtaining:

$I=E_x^2{\sin }^2\mathrm{\θ}+E_y^2{\cos }^2\mathrm{\θ}+E_x{E}_y\sin 2\mathrm{\θ}\cos \mathrm{\α}+\frac{I_0}{2}+n(E_x^2{\cos }^2\mathrm{\θ}+E_y^2{\sin }^2\mathrm{\θ}+E_x{E}_y\sin 2\mathrm{\θ}\cos \mathrm{\α}+\frac{I_0}{2}),$

$=({\sin }^2\mathrm{\θ}+n{\cos }^2\mathrm{\θ})E_x^2+({\cos }^2\mathrm{\θ}+n{\sin }^2)E_y^2+(1+n)E_x{E}_y\sin 2\mathrm{\θ}\cos \mathrm{\α}+(1+n)\frac{I_0}{2}$

Wherein E _xfor X-direction electric field intensity intensity, E _yfor Y direction electric field intensity intensity, θ is the light transmission shaft of main polaroid 1 and the angle of Y-axis, and α is E _ywith respect to E _xphasic difference, I ₀for the intensity of equivalent natural light in incident monochromatic light, n is the extinctivity of main polaroid 1,

By the light transmission shaft of main polaroid 1 of above-mentioned each acquisition and the angle theta of the Y-axis transmitted light intensity I substitution above formula that corresponding collection obtains with ccd detector 2, calculate and obtain E _x, E _y, α, I ₀, obtain the monochromatic polarization state of incident.

Step 6 and step 7 are just can use in the time cannot distinguishing circularly polarized light and natural light, and this result cannot differentiation state embodying is E _x=E _y.

In present embodiment, if calculate respectively the polarization state of the incident light of each sensing point on ccd detector 2, the polarization state that can measure incident light xsect distributes.

As shown in Figure 3, adopt the inventive method higher to the measuring accuracy of monochromatic light polarization state, better with the fitting effect of theoretical polarization state curve.The inventive method has proposed only to apply the method for polaroid measurement polarisation of light state first, has proposed first rotary reference coordinate system and has reappraised polarisation of light state.

Claims (3)

1. a method of measuring monochromatic light polarization state, is characterized in that, it comprises the following steps:

Step 1: along arranging successively main polaroid (1) and ccd detector (2) perpendicular to the direction of incident monochromatic light light path, make monochromatic light after main polaroid (1), be incident to the light receiving surface of ccd detector (2), wherein the direction of monochromatic light optical axis is as the Z-direction of three-dimensional system of coordinate;

Step 2: obtain the transmitted light intensity of incident monochromatic light after main polaroid (1) by ccd detector (2) collection;

Step 3: rotate main polaroid (1) N time, make the each postrotational light transmission shaft of main polaroid (1) different from the angle of Y-axis, rotate after main polaroid (1) repeating step two at every turn; Then perform step four; Wherein N is equal to, or greater than 6 natural number;

Step 4: calculate the monochromatic polarization state of acquisition incident with angle and the corresponding transmitted light intensity obtaining that gathers of ccd detector (2) of Y-axis according to the light transmission shaft of each main polaroid (1);

The concrete grammar that calculates the monochromatic polarization state of acquisition incident in step 4 is:

The transmitted light intensity I obtaining according to ccd detector (2) collection:

$\begin{array}{c}I=E_x^2{\sin }^2\mathrm{\θ}+E_y^2{\cos }^2\mathrm{\θ}+E_x{E}_y\sin 2\mathrm{\θ}\cos \mathrm{\α}+\frac{I_0}{2}+n(E_x^2{\cos }^2\mathrm{\θ}+E_y^2{\sin }^2\mathrm{\θ}+E_x{E}_y\mathrm{isn}2\mathrm{\θ}\cos \mathrm{\α}+\frac{I_0}{2}),\\ =({\sin }^2\mathrm{\θ}+n{\cos }^2\mathrm{\θ})E_x^2+({\cos }^2\mathrm{\θ}+n{\sin }^2\mathrm{\θ})E_y^2+(1+n)E_x{E}_y\sin 2\mathrm{\θ}\cos \mathrm{\α}+(1+n)\frac{I_0}{2}\end{array}$

Wherein E _xfor X-direction electric field intensity intensity, E _yfor Y direction electric field intensity intensity, θ is the light transmission shaft of main polaroid (1) and the angle of Y-axis, and α is E _ywith respect to E _xphasic difference, I ₀for the intensity of equivalent natural light in incident monochromatic light, n is the extinctivity of main polaroid (1),

By the light transmission shaft of main polaroid (1) of above-mentioned each acquisition and the angle theta of the Y-axis transmitted light intensity I substitution above formula that corresponding collection obtains with ccd detector (2), calculate and obtain Ex, Ey, α, I ₀, obtain the monochromatic polarization state of incident.

2. the method for measurement monochromatic light polarization state according to claim 1, is characterized in that, it is further comprising the steps of:

Step 5: the XY rotation with in surface Y direction in three-dimensional system of coordinate, then calculate and obtain the monochromatic polarization state of incident according to the method in step 4, and judge that obtaining incident monochromatic light is elliptically polarized light or partial poolarized light.

3. the method for measurement monochromatic light polarization state according to claim 2, is characterized in that, it is further comprising the steps of:

Step 6: additional polaroid (3) is set in the front direction perpendicular to monochromatic light light path of ccd detector (2);

Step 7: obtain the transmitted light intensity of incident monochromatic light after additional polaroid (3) by ccd detector (2) collection; Then perform step three and step 4, and judge that obtaining incident monochromatic light is circularly polarized light or natural light.