CN102967928A - Method and device for generating tightly-focused light spots of column polarized vector beam - Google Patents

Abstract

The invention discloses a method and device for generating a tightly-focused light spot array of a column polarized vector beam which can be rotated freely. Based on the generation of a column polarized vector beam in the prior art, the polarized direction of the column polarized vector beam is rotated in a way that the beam passes through two half wave plates. Finally, the beam is tightly focused through a microscope objective with a high numerical aperture to obtain array-type focused light spots. Through rotating the second half wave plate, the rotation speed of the focused light spot array is easily controlled. The method provided by the invention is easy to realize, the device provided by the invention has the advantages of simple structure, adjustment easiness and low manufacturing cost. Moreover, the device has good stability and does not need other special optical elements.

Description

Production method and the device of the tight focal beam spot of a kind of post polarization vector light beam

Technical field

The present invention relates to the production method of the tight focal beam spot array of post polarization vector light beam, particularly a kind of dynamically production method and the device of the real-time tight focal beam spot array of post polarization vector light beam that can rotate arbitrarily.

Background technology

Laser optical tweezer is to use laser to capture, handle a technology controlling molecule as technological means, is an emerging front subject, is the cross discipline in conjunction with physics, biology, medical science equally.The light tweezer disturbs minimum because of its vital movement to biological particle, wholely control the cells survival environment that system relates to and almost be equal to " natural " environment, can change complete reservation to the vital movement of biological particle and realize aseptic, not damaged, dynamically control in real time, optical tweezer technology is so that the life process of biomedical molecule or cell becomes artificially controlled simultaneously, can artificially regulate the arbitrary link in its vital movement, its individual behavior is studied.

China just explicitly points out the operation of gene and protein as the frontier science and technology of country at " National Program for Medium-to Long-term Scientific and Technological Development (2006-2020) ", simultaneously some cross disciplines and new branch of science is also listed in the important directions in fundamental research field.

The principle of work of laser optical tweezer is to utilize gradient force that the distribution of light intensity spatial variations forms that particulate stably is captured in the strength of light intensity, and namely the focal position of light beam just can drive particulate to move together when laser beam moves, and realization is controlled the precision of particulate.If utilize orbital angular momentum and the spin angular momentum of photon and the transmission of the particulate that is hunted down, can also realize the rotation to particulate.Take single beam Gauss light tweezer as example, when the Gauss light field action of a branch of high concentration during in a transparent particulate, when the refractive index of particulate during greater than the refractive index of surrounding medium, it no matter is the direction of propagation at light, or in the plane perpendicular to the direction of propagation, distribution of light intensity changes the gradient force that forms meeting is pushed particle to place with a tight waist, forms the three-dimensional optical potential well.So want and to be strapped in the light field potential well, produce enough strong gradient force thereby the laser beam height must be converged particle-stabilisedly.This needs to use the microcobjective of high-NA usually, and the hot spot that light beam tightly is focused into wavelength magnitude is realized.

In recent years, post polarization vector light beam has caused that people more and more pay close attention to.The optical field distribution of this light beam and polarization state distribute and all are the post symmetry about optical axis.Wherein, two the most special classes are exactly radial polarisation light and angle polarized light, and the polarization state of this two classes light beam on xsect is respectively along radially distributing with the deflection direction.Because the polarization characteristic of post polarization vector light beam uniqueness, this class light beam have very unique tight focus characteristics after by high numerical aperture lens.For example, after radial polarisation light focuses on by high-NA is tight, can produce a hollow symmetrical transverse electric field component of circle, and a Gaussian longitudinal component along optical axis direction much better than and more much smaller than cross stream component, thereby a very little tight focal beam spot obtained.After the angle polarized light focuses on by high numerical aperture lens is tight, then only produce a hollow symmetrical pure cross stream component of circle.The tight focus characteristics of these uniquenesses has very important using value aspect laser optical tweezer.Radial polarisation light ratio linearly polarized light after for example assembling has larger gradient force, and does not have scattering force on optical axis direction; And the angle polarized light after assembling can be caught the little particulate of refractive index ratio surrounding medium.

Very many by the tight document that focuses on of high numerical aperture lens for research post polarization vector light beam.Thereby researchers are by regulating and control to reach the tight purpose that focuses on rear hot spot of regulation and control to the post polarization vector light beam of incident.Regulation and control and coherence regulate and control three kinds mutually to regulate and control the regulation and control of main amplitude, position.The main employing at high numerical aperture lens front insertion optical element realized.Concrete optical element mainly contains the frosted glass plate of annular pupil, amplitude filter, Binary photograph and rotation etc.By these control methods, can carry out shaping regulation and control to the light spot shape after the tight focusing, thereby reach different application demands, for example be focused into less hot spot so that larger gradient force to be provided, thus the more stable particulate of catching; Produce the focal beam spot of special shape, thereby catch dissimilar particulates.Further, researchers also utilize the vortex position photo, so that the post polarization vector light beam of incident is with orbital angular momentum, thereby reach the purpose that the hot spot after the focusing can stably rotate particulate.But it is also noted that, utilize this method rotation particulate, when needs are adjusted rotational speed, must make larger adjustment to light path.

Summary of the invention

The objective of the invention is to design a kind of dynamically production method and the device of the real-time tight focal beam spot array of post polarization vector light beam that can rotate arbitrarily.

To achieve these goals, the technical scheme that provides of the application is as follows:

The production method of the tight focal beam spot of a kind of post polarization vector light beam, the post polarization vector light beam that produces is passed through the first half-wave plate, the second half-wave plate and microcobjective successively, obtain focal beam spot, rotate the second half-wave plate and control the rotational speed of described focal beam spot, the definition polar coordinate system, the expression formula of described post polarization vector light beam is:

${\stackrel{\&RightArrow;}{E}}_1(r,\mathrm{\&phi;},0)=\exp (-\frac{r^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}){\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)}^{(n+1)/2}{L}_p^{n+1}\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)[\cos \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_{\mathrm{\&phi;}}-\sin \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_r]$

Wherein, r and φ be respectively under the polar coordinate system radially with angle coordinate, w ₀Be the waist radius of post polarization vector light beam, be generally a millimeter magnitude, p and n+1 are the exponent numbers of Laguerre polynomials, are integer.The incident beam wavelength generally selects visible-range, and generally in a centimetre magnitude, numerical aperture is close to 1 for objective focal length.

Preferably, in the production method of the tight focal beam spot of above-mentioned post polarization vector light beam, described the first half-wave plate and the second half-wave plate are identical half-wave plate and coaxial, and described the first half-wave plate and the second half-wave plate are close to described microcobjective and are placed

Correspondingly, the invention also discloses the generation device of the tight focal beam spot of a kind of post polarization vector light beam, it is characterized in that, comprising:

Post polarization vector optical beam generating device, the definition polar coordinate system, the expression formula of described post polarization vector light beam is:

${\stackrel{\&RightArrow;}{E}}_1(r,\mathrm{\&phi;},0)=\exp (-\frac{r^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}){\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)}^{(n+1)/2}{L}_p^{n+1}\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)[\cos \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_{\mathrm{\&phi;}}-\sin \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_r]$

Wherein, r and φ be respectively under the polar coordinate system radially with angle coordinate, w ₀Be the waist radius of post polarization vector light beam, p and n+1 are the exponent numbers of Laguerre polynomials, are integer;

Along the first half-wave plate that sets gradually on the radiation direction of described post polarization vector light beam, the second half-wave plate and microcobjective.

Preferably, in the generation device of the tight focal beam spot of above-mentioned post polarization vector light beam, described the first half-wave plate and the second half-wave plate are identical half-wave plate and coaxial, and described the first half-wave plate and the second half-wave plate are close to described microcobjective and are placed; The waist radius of described post polarization vector light beam is the millimeter magnitude; The focal length of described microcobjective is in a centimetre magnitude.

Compared with prior art, the present invention according to prior art on the basis that produces post polarization vector light beam, by allowing light beam come the polarization direction of column spinner polarization vector light beam by the method for two half-wave plates.Allow again at last this light beam tightly focus on by the high-NA microcobjective, thereby obtain the focal beam spot of array.By rotating second half-wave plate, can control easily the rotational speed of the spot array after the focusing.The inventive method realizes that easily apparatus structure is simple, is easy to adjust low cost of manufacture; Device stability is good, does not need other special optical elements.

Description of drawings

In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, the below will do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art, apparently, accompanying drawing in the following describes only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain according to these accompanying drawings other accompanying drawing.

Fig. 1 is described to be the structural representation of the generation device of the tight focal beam spot of specific embodiment of the invention center pillar polarization vector light beam;

Fig. 2 produces the tight launching spot figure that focuses on four spot arrays in the embodiment of the invention 1;

Fig. 3 is that tight focusing four spot arrays that produce in the embodiment of the invention 1 are with the second half-wave plate anglec of rotation

The hot spot rotation diagram;

Fig. 4 produces the tight launching spot figure that focuses on six spot arrays in the embodiment of the invention 2;

Fig. 5 is that tight focusing six spot arrays that produce in the embodiment of the invention 2 are with the second half-wave plate anglec of rotation

The hot spot rotation diagram

Embodiment

The embodiment of the invention discloses a kind of dynamically production method and the device of the real-time tight focal beam spot array of post polarization vector light beam that can rotate arbitrarily, specific as follows:

(1) expression formula of the post polarization vector light beam on the primary face is:

${\stackrel{\&RightArrow;}{E}}_1(r,\mathrm{\&phi;},0)=\exp (-\frac{r^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}){\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)}^{(n+1)/2}{L}_p^{n+1}\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)[\cos \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_{\mathrm{\&phi;}}-\sin \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_r],$

Wherein, w ₀Be the waist radius of light beam, p and n+1 are the exponent numbers of Laguerre polynomials.The high-order post polarization vector light beam of this complexity can be by the patent No.: 200710191085.6 patent way produces.

(2) utilize the vector formula With The expression formula of this incident beam can be expressed as:

${\stackrel{\&RightArrow;}{E}}_1(r,\mathrm{\&phi;},0)=\exp (-\frac{r^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}){\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)}^{(n+1)/2}{L}_p^{n+1}\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)\{-\sin [(n+1)\mathrm{\&phi;}]{\stackrel{\&RightArrow;}{e}}_x+\cos [(n+1)\mathrm{\&phi;}\left]{\stackrel{\&RightArrow;}{e}}_y\right\},$ So its polarization vector can be expressed as under rectangular coordinate system $\left[\begin{array}{c}-\sin \left[(n+1)\mathrm{\&phi;}\right]\\ \cos \left[(n+1)\mathrm{\&phi;}\right]\end{array}\right].$

(3) set gradually the first half-wave plate 10 at the radiation direction along the light source that produces post polarization vector light, its fast axle overlaps with the y axle, and its Jones matrix can be expressed as $\left[\begin{array}{cc}i& 0\\ 0& -i\end{array}\right],$ So, the polarization vector of light beam becomes

$\left[\begin{array}{cc}i& 0\\ 0& -i\end{array}\right]\left[\begin{array}{c}-\sin \left[(n+1)\mathrm{\&phi;}\right]\\ \cos \left[(n+1)\mathrm{\&phi;}\right]\end{array}\right]=\left[\begin{array}{c}-i\sin \left[(n+1)\mathrm{\&phi;}\right]\\ -i\cos \left[(n+1)\mathrm{\&phi;}\right]\end{array}\right].$

(4) allow light beam by the second half-wave plate 20, its fast axle becomes angle with the x direction of principal axis again

The Jones matrix of this half-wave plate is:

Can get behind the abbreviation

So, the polarization vector of light beam becomes

As can be seen from the above equation, behind two half-wave plates, the polarization direction of the post polarization vector light beam of incident has rotated

Angle.

(5) recycling vector formula represents the light beam expression formula under cylindrical coordinates:

(6) relief light beam tightly focuses on by high-NA microcobjective 30, obtains tight focal beam spot array.According to the sine condition r=fsin θ of tight focusing, the above-mentioned light field expression formula of substitution can obtain the apodizing function on the focusing surface:

According to tight focusing formula, in conjunction with integral formula

Light field expression formula after can obtaining focusing on:

$L_p^{n+1}\left(\frac{{2f}^2{\sin }^2\mathrm{\&theta;}}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)J_n\left({\mathrm{kr}}_s\sin \mathrm{\&theta;}\right)\exp \left({\mathrm{ikz}}_s\cos \mathrm{\&theta;}\right)\mathrm{d\&theta;}$

Wherein, A is constant, and its size does not affect the relative distribution of each point light intensity.α=arcsin (NA) is the maximum convergent angle of high-NA microcobjective.r _s, φ _s, z _sIt is the cylindrical coordinates of observation point.The light distribution of focal beam spot is:

$I(r_s,{\mathrm{\&phi;}}_s,z_s)=I_r(r_s,{\mathrm{\&phi;}}_s,z_s)+I_{\mathrm{\&phi;}}(r_s,{\mathrm{\&phi;}}_s,z_s)+I_z(r_s,{\mathrm{\&phi;}}_s,z_s)$

$={\left|E_r^{\left(s\right)}(r_s,{\mathrm{\&phi;}}_s,z_s)\right|}^2+{\left|E_{\mathrm{\&phi;}}^{\left(s\right)}(r_s,{\mathrm{\&phi;}}_s,z_s)\right|}^2+{\left|E_z^{\left(s\right)}(r_s,{\mathrm{\&phi;}}_s,z_s)\right|}^2.$

As can be seen from the above equation, focal beam spot along with

Variation and rotate.When half-wave plate 2 rotations During angle, the focal beam spot rotation

Angle, namely the rotational speed of focal beam spot is half-wave plate 2 rotational speeies

Doubly.By the rotational speed of control half-wave plate 2, we are the rotary-focusing hot spot arbitrarily.

In order to make those skilled in the art person understand better technical scheme among the application, below in conjunction with the accompanying drawing in the embodiment of the present application, technical scheme in the embodiment of the present application is clearly and completely described, obviously, described embodiment only is the application's part embodiment, rather than whole embodiment.Based on the embodiment among the application, those of ordinary skills are not making the every other embodiment that obtains under the creative work prerequisite, all should belong to the scope of the application's protection.

Embodiment one: the production method of the four tight focal beam spot arrays that can rotate arbitrarily

(1) expression formula of the post polarization vector light beam of incident is:

${\stackrel{\&RightArrow;}{E}}_1(r,\mathrm{\&phi;},0)=\exp (-\frac{r^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}){\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)}^{(n+1)/2}{L}_p^{n+1}\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)[\cos \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_{\mathrm{\&phi;}}-\sin \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_r]$

Wherein, waist radius is elected w as ₀=2mm, the light beam exponent number is elected p=0 as, n=2.The wavelength of incident beam is elected λ=632.8nm as.

The surface of intensity distribution of incident beam as shown in Figure 2, arrow represents this light beam polarization direction of each point aloft among the figure.As can be seen from the figure, to be open circles symmetrical in the light distribution of the post polarization vector light beam of this incident.

(2) each optical device placement location as shown in Figure 1.Place successively the first half-wave plate 10, the second half-wave plate 20 and high-NA microcobjective 30 along the incident ray direction.The quick shaft direction of the first half-wave plate 10 overlaps with the y axle, and the angle of the quick shaft direction of the second half-wave plate 20 and x axle is

The focal length parameter of high-NA microcobjective 30 is 1cm, and its numerical aperture in free space is 0.95.

After the post polarization vector light beam of incident passed through the first half-wave plate 10 and the second half-wave plate 20 successively, its light field expression formula became:

This shows that the light distribution of this light beam does not change, but the polarization direction of space each point has rotated

Angle.

(3) relief tightly focuses on by high numerical value microcobjective by the post polarization vector light beam of two half-wave plates.Light field expression formula after the focusing is:

$L_p^{n+1}\left(\frac{{2f}^2{\sin }^2\mathrm{\&theta;}}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)J_n\left({\mathrm{kr}}_s\sin \mathrm{\&theta;}\right)\exp \left({\mathrm{ikz}}_s\cos \mathrm{\&theta;}\right)\mathrm{d\&theta;}$

Wherein, A is constant, and its size does not affect the relative distribution of each point light intensity.α=arcsin (NA) is the maximum convergent angle of high-NA microcobjective.r _s, φ _s, z _sIt is the cylindrical coordinates of observation point.The light distribution of focal beam spot is:

$I(r_s,{\mathrm{\&phi;}}_s,z_s)=I_r(r_s,{\mathrm{\&phi;}}_s,z_s)+I_{\mathrm{\&phi;}}(r_s,{\mathrm{\&phi;}}_s,z_s)+I_z(r_s,{\mathrm{\&phi;}}_s,z_s)$

$={\left|E_r^{\left(s\right)}(r_s,{\mathrm{\&phi;}}_s,z_s)\right|}^2+{\left|E_{\mathrm{\&phi;}}^{\left(s\right)}(r_s,{\mathrm{\&phi;}}_s,z_s)\right|}^2+{\left|E_z^{\left(s\right)}(r_s,{\mathrm{\&phi;}}_s,z_s)\right|}^2.$

After tight the focusing, the light distribution on the focal plane as shown in Figure 3.As can see from Figure 3, focal beam spot becomes 4 spot arrays to distribute, and spot array can rotate along with the rotation of the second half-wave plate 20.The rotational speed of focal beam spot is identical with the rotational speed of half-wave plate.

Embodiment two: the production method of the six tight focal beam spot arrays that can rotate arbitrarily

(1) expression formula of the post polarization vector light beam of incident is:

${\stackrel{\&RightArrow;}{E}}_1(r,\mathrm{\&phi;},0)=\exp (-\frac{r^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}){\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)}^{(n+1)/2}{L}_p^{n+1}\left(\frac{{2r}^2}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)[\cos \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_{\mathrm{\&phi;}}-\sin \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_r]$

Wherein, waist radius is elected w as ₀=2mm, the light beam exponent number is elected p=0 as, n=3.The wavelength of incident beam is elected λ=632.8nm as.

The surface of intensity distribution of incident beam as shown in Figure 4, arrow represents this light beam polarization direction of each point aloft among the figure.As can be seen from Figure 4, light distribution and Fig. 2 of the post polarization vector light beam of this incident are similar, but the polarisation distribution of space each point is different.

(2) each optical device placement location as shown in Figure 1.Place successively the first half-wave plate 10, the second half-wave plate 20 and high-NA microcobjective 30 along the incident ray direction.The quick shaft direction of the first half-wave plate 10 overlaps with the y axle, and the angle of the quick shaft direction of the second half-wave plate 20 and x axle is

The focal length parameter of high-NA microcobjective is 1cm, and its numerical aperture in free space is 0.95.

After the post polarization vector light beam of incident passed through the first half-wave plate 10 and the second half-wave plate 20 successively, its light field expression formula became:

This shows that the light distribution of this light beam does not change, but the polarization direction of space each point has rotated

Angle.

(3) relief tightly focuses on by high numerical value microcobjective by the post polarization vector light beam of two half-wave plates.Light field expression formula after the focusing is:

$L_p^{n+1}\left(\frac{{2f}^2{\sin }^2\mathrm{\&theta;}}{{\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="HDA00002575055500021.png"\; state="\{\{state\}\}">w</figure-callout>}}_0^2}\right)J_n\left({\mathrm{kr}}_s\sin \mathrm{\&theta;}\right)\exp \left({\mathrm{ikz}}_s\cos \mathrm{\&theta;}\right)\mathrm{d\&theta;}$

Wherein, A is constant, and its size does not affect the relative distribution of each point light intensity.α=arcsin (NA) is the maximum convergent angle of high-NA microcobjective.r _s, φ _s, z _sIt is the cylindrical coordinates of observation point.The light distribution of focal beam spot is:

$I(r_s,{\mathrm{\&phi;}}_s,z_s)=I_r(r_s,{\mathrm{\&phi;}}_s,z_s)+I_{\mathrm{\&phi;}}(r_s,{\mathrm{\&phi;}}_s,z_s)+I_z(r_s,{\mathrm{\&phi;}}_s,z_s)$

$={\left|E_r^{\left(s\right)}(r_s,{\mathrm{\&phi;}}_s,z_s)\right|}^2+{\left|E_{\mathrm{\&phi;}}^{\left(s\right)}(r_s,{\mathrm{\&phi;}}_s,z_s)\right|}^2+{\left|E_z^{\left(s\right)}(r_s,{\mathrm{\&phi;}}_s,z_s)\right|}^2.$

After tight the focusing, the light distribution on the focal plane as shown in Figure 5.As can see from Figure 5, focal beam spot becomes 6 spot arrays to distribute, and spot array can rotate along with the rotation of the second half-wave plate 20.The rotational speed of focal beam spot be half-wave plate rotational speed 2/3.

In sum, the present invention according to prior art on the basis that produces post polarization vector light beam, by allowing light beam come the polarization direction of column spinner polarization vector light beam by the method for two half-wave plates.Allow again at last this light beam tightly focus on by the high-NA microcobjective, thereby obtain the focal beam spot of array.By rotating second half-wave plate, can control easily the rotational speed of the spot array after the focusing.The inventive method realizes that easily apparatus structure is simple, is easy to adjust low cost of manufacture; Device stability is good, does not need other special optical elements.

To those skilled in the art, obviously the invention is not restricted to the details of above-mentioned example embodiment, and in the situation that does not deviate from spirit of the present invention or essential characteristic, can realize the present invention with other concrete form.Therefore, no matter from which point, all should regard embodiment as exemplary, and be nonrestrictive, scope of the present invention is limited by claims rather than above-mentioned explanation, therefore is intended to include in the present invention dropping on the implication that is equal to important document of claim and all changes in the scope.Any Reference numeral in the claim should be considered as limit related claim.

In addition, be to be understood that, although this instructions is described according to embodiment, but be not that each embodiment only comprises an independently technical scheme, this narrating mode of instructions only is for clarity sake, those skilled in the art should make instructions as a whole, and the technical scheme among each embodiment also can through appropriate combination, form other embodiments that it will be appreciated by those skilled in the art that.

Claims (8)

1. the production method of the tight focal beam spot of post polarization vector light beam, it is characterized in that: the post polarization vector light beam that produces is passed through the first half-wave plate, the second half-wave plate and microcobjective successively, obtain focal beam spot, rotate the second half-wave plate and control the rotational speed of described focal beam spot, the definition polar coordinate system, the expression formula of described post polarization vector light beam is:

${\stackrel{\&RightArrow;}{E}}_1(r,\mathrm{\&phi;},0)=\exp (-\frac{r^2}{w_0^2}){\left(\frac{{2r}^2}{w_0^2}\right)}^{(n+1)/2}{L}_p^{n+1}\left(\frac{{2r}^2}{w_0^2}\right)[\cos \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_{\mathrm{\&phi;}}-\sin \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_r]$

Wherein, r and φ be respectively under the polar coordinate system radially with angle coordinate, w ₀Be the waist radius of post polarization vector light beam, p and n+1 are the exponent numbers of Laguerre polynomials, are integer.

2. the production method of the tight focal beam spot of post polarization vector light beam according to claim 1, it is characterized in that: described the first half-wave plate and the second half-wave plate are identical half-wave plate and coaxial, and described the first half-wave plate and the second half-wave plate are close to described microcobjective and are placed.

3. the production method of the tight focal beam spot of post polarization vector light beam according to claim 1 is characterized in that: the waist radius of described post polarization vector light beam is a millimeter magnitude.

4. the production method of the tight focal beam spot of post polarization vector light beam according to claim 1, it is characterized in that: the focal length of described microcobjective is in a centimetre magnitude.

5. the generation device of the tight focal beam spot of post polarization vector light beam is characterized in that, comprising:

Post polarization vector optical beam generating device, the definition polar coordinate system, the expression formula of described post polarization vector light beam is:

${\stackrel{\&RightArrow;}{E}}_1(r,\mathrm{\&phi;},0)=\exp (-\frac{r^2}{w_0^2}){\left(\frac{{2r}^2}{w_0^2}\right)}^{(n+1)/2}{L}_p^{n+1}\left(\frac{{2r}^2}{w_0^2}\right)[\cos \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_{\mathrm{\&phi;}}-\sin \left(\mathrm{n\&phi;}\right){\stackrel{\&RightArrow;}{e}}_r]$

Wherein, r and φ be respectively under the polar coordinate system radially with angle coordinate, w ₀Be the waist radius of post polarization vector light beam, p and n+1 are the exponent numbers of Laguerre polynomials, are integer;

Along the first half-wave plate that sets gradually on the radiation direction of described post polarization vector light beam, the second half-wave plate and microcobjective.

6. the generation device of the tight focal beam spot of post polarization vector light beam according to claim 5, it is characterized in that: described the first half-wave plate and the second half-wave plate are identical half-wave plate and coaxial, and described the first half-wave plate and the second half-wave plate are close to described microcobjective and are placed.

7. the generation device of the tight focal beam spot of post polarization vector light beam according to claim 5 is characterized in that: the waist radius of described post polarization vector light beam is a millimeter magnitude.

8. the generation device of the tight focal beam spot of post polarization vector light beam according to claim 5, it is characterized in that: the focal length of described microcobjective is in a centimetre magnitude.

Images