CN103399413B - Double helix light beam-based sample axial drift detection and compensation method and device - Google Patents

Abstract

The invention discloses a double helix light beam-based sample axial drift detection and compensation method. The method comprises the following steps: performing phase modulation on a collimated laser beam to obtain a double helix illuminating light beam and projecting to a sample to be detected on a three-dimensional nano scanning platform to obtain a reflected light beam; focusing the reflected light beam into a focusing spot with two intensity peak values; receiving the focusing spot by using a photoelectric induction device to obtain spot intensity distribution information; calculating an included angle between a connecting line of the two intensity peak values and the horizontal direction according to the spot intensity distribution information; establishing a calibration function by using the relation of the included angle and axial drift of the sample; when the sample to be detected drifts in axial position, obtaining the axial drift of the current sample according to the calibration function by using the included angle measured in real time and then adjusting the axial position of the three-dimensional nano scanning platform to finish correction of the axial position of the sample to be detected. The invention also discloses a double helix light beam-based sample axial drift detection and compensation device.

Description

Based on double helix light beam sample axially drift detect and compensation method and device

Technical field

The invention belongs to high precision, the micro-field of super-resolution, particularly a kind of sample based on double helix light beam axially drift detect in real time and compensation method and device.

Background technology

Due to the impact of the factor such as thermal drift, stress drift, inevitably there is position excursion in the testing sample in super-resolution microscopic system in the axial direction, thus out of focus phenomenon occurs, and affects the precision of micro-imaging.For need concerning same sample face repeatedly repeat imaging microscopic method (such as based on unimolecule location super-resolution microscopy), this impact brought of axially drifting about will be more obvious, because axially drift is not same sample face by what cause repeatedly repeating imaging.Therefore, a kind ofly can to detect the drift of the axial location of sample in real time and the method compensated has very important using value in microscopic system.

In recent years, researchists propose the bearing calibration of several samples axial location successively.Wherein, based on the method for optics with its noncontact, be most widely used advantages such as sample effects are little.But mostly the sample nose balance method at present based on optics is based on confocal system, although have good measuring accuracy, the debugging of system is all comparatively complicated with operation, thus limits the application in practice of these methods to a certain extent.

Summary of the invention

The invention provides a kind of sample based on double helix light beam axially drift detect in real time and compensation method and device, can realize for the real-time high-precision of sample axial position drift, large-range measuring correcting.This kind of method and device are convenient to build, simple to operate, can be widely used among various optical microscope system, ensure that microscopic sample is positioned at the focal plane place of microcobjective all the time.

Based on sample axially drift detection and a compensation method for double helix light beam, comprise the following steps:

1) laser beam after collimation is incident in spatial light modulator and carries out phase-modulation, obtain double helix illuminating bundle, the focal beam spot of described double helix illuminating bundle presents two intensity peak, and the line between these two intensity peak has revolving property in direction of beam propagation;

2) the double helix illuminating bundle line focus described in projects the testing sample be positioned on three-dimensional manometer scanning platform, collects obtain folded light beam through testing sample reflection and by microcobjective;

3) described folded light beam line focus obtains the focal beam spot with two intensity peak, and utilizes the focal beam spot described in the reception of optoelectronic induction device, obtains spot intensity distributed intelligence;

4) angle of line between two intensity peak and horizontal direction is calculated according to described spot intensity distributed intelligence;

5) relation of the angle described in utilization and the axial drift value of sample sets up calibration function;

6) when testing sample generation axial location drifts about, repeat step 1) ~ 4), obtain the angle measured in real time, the axial drift value of current sample is calculated according to described calibration function, and the axial location of described three-dimensional manometer scanning platform is adjusted according to the axial drift value of current sample, complete the correction of the axial location to testing sample.

The phase modulation function f (ρ, φ) of described spatial light modulator is set to the phase component of several different GL basic mode compound light fields superimposed field, that is,

U(ρ,φ,z)=∑u _mn(ρ,φ,z),n=0,1,2,…,m=2n+1

f(ρ,φ)=arg[U(ρ,φ,0)]

Wherein, (ρ, φ, z) is with three coordinate components of the desirable focus of the microcobjective cylindrical coordinate that is initial point, u _mn(ρ, φ, z) is GL basic mode compound light fields, mn rank, and arg is argument of a complex number function.

Particularly, mn rank GL basic mode compound light field u _mnthe expression formula of (ρ, φ, z) is,

$u_{\mathrm{mn}}(\mathrm{\ρ},\mathrm{\φ},z)=w_0/w\left(\hat{z}\right)\exp (-\stackrel{^2}{\mathrm{\ρ}})\exp \left(i\stackrel{^2}{\mathrm{\ρ}}\hat{z}\right)\exp [-i\arctan \left(\hat{z}\right)]\·{\left(\sqrt{2}\widehat{\mathrm{\ρ}}\right)}^{\left|m\right|}{L}_n^m\left(2\stackrel{^2}{\mathrm{\ρ}}\right)$

$\·\exp \left(\mathrm{im\φ}\right)\exp [-i(2n+m)\arctan \left(\hat{z}\right)]$

Wherein, w ₀for the waist radius of laser beam, i is imaginary unit, λ is the wavelength of laser beam used, be mn rank Laguerre polynomials.

In preferred technical scheme, set compound light field is the superposition of five kinds of different GL basic mode compound light fields, and concrete (m, n) value is (1,0), (3,1), (5,2), (7,3) and (9,4).

In preferred technical scheme, described optoelectronic induction device is high-speed charge coupled device (CCD:Charge Couple Device).

Present invention also offers a kind of device for realizing said method, comprising:

Laser instrument, for sending the laser instrument of laser beam;

Spatial light modulator, for carrying out phase-modulation to described laser beam;

Three-dimensional manometer scanning platform, for placing testing sample;

Microcobjective, for the light beam of described spatial light modulator outgoing is focused to testing sample, and collects the folded light beam reflected through described testing sample;

Field lens, for focusing on described folded light beam and obtaining focal beam spot;

Optoelectronic induction device, the focal beam spot described in reception, and obtain spot intensity distributed intelligence;

And the computing machine to be connected with described three-dimensional manometer scanning platform and optoelectronic induction device.

Single-mode fiber, collimation lens and catoptron is furnished with successively between described laser instrument and spatial light modulator.The outgoing end face of described single-mode fiber is positioned at the focus in object space place of described collimation lens, and described optoelectronic induction device is positioned at the rear focus place of described field lens;

Described spatial light modulator is used for carrying out phase encoding to illuminating bundle, concrete phase modulation function f (ρ, φ) be set to the phase component of several different GL basic mode compound light fields superimposed field, the phase modulation function f (ρ, φ) of described spatial light modulator is

f(ρ,φ)=arg[U(ρ,φ,0)]

U(ρ,φ,z)=∑u _mn(ρ,φ,z),n=0,1,2,…,m=2n+1

Wherein, (ρ, φ, z) is with three coordinate components of the focus of the microcobjective cylindrical coordinate that is initial point, u _mn(ρ, φ, z) is GL basic mode compound light fields, mn rank, and arg is argument of a complex number function;

Described mn rank GL basic mode compound light field u _mn(ρ, φ, z) is:

$u_{\mathrm{mn}}(\mathrm{\ρ},\mathrm{\φ},z)=w_0/w\left(\hat{z}\right)\exp (-\stackrel{^2}{\mathrm{\ρ}})\exp \left(i\stackrel{^2}{\mathrm{\ρ}}\hat{z}\right)\exp [-i\arctan \left(\hat{z}\right)]\·{\left(\sqrt{2}\widehat{\mathrm{\ρ}}\right)}^{\left|m\right|}{L}_n^m\left(2\stackrel{^2}{\mathrm{\ρ}}\right)$

$\·\exp \left(\mathrm{im\φ}\right)\exp [-i(2n+m)\arctan \left(\hat{z}\right)]$

Wherein, w ₀for the waist radius of laser beam, i is imaginary unit, λ is the wavelength of laser beam used, be mn rank Laguerre polynomials.

In preferred technical scheme, set compound light field is the superposition of five kinds of different GL basic mode compound light fields, and concrete (m, n) value is (1,0), (3,1), (5,2), (7,3) and (9,4).

In preferred technical scheme, described optoelectronic induction device is high-speed charge coupled device (CCD:Charge Couple Device).

The principle of the invention is as follows:

GL mould light beam is the solution of Helmholtz equation under near-axial condition.Arbitrary spatial light field always can resolve into the superposition of the compound light field of several different GL basic modes.Double helix light beam can be produced when several specific GL basic mode superpositions.So-called double helix light beam is the one of rotary light beam, and in certain spatial dimension, the Light Energy of light beam remains unchanged, and optical field distribution situation is constant, change be only the one trend of a phase and optical field distribution.Especially, double helix light beam is after lens focus, become focal beam spot can present two intensity peak, and line has revolving property in direction of beam propagation between these two intensity peak, namely at different axial locations, between two intensity peak, line is different from the angle of horizontal direction.

Based on this characteristic of double helix light beam, the present invention utilizes spatial light modulator to carry out phase-modulation to illuminating bundle, thus forms double helix illuminating bundle.When there is drift in the axial direction in testing sample, described double helix illuminating bundle on sample face become the line of two intensity peak in focal beam spot to point to angle to change, after corresponding monitoring light beam focuses on, on optoelectronic induction device, institute becomes the line of two intensity peak in hot spot sensing angle also can change.Becoming the relation of the sensing angle of hot spot and sample axis drift value by demarcating monitoring light beam institute on optoelectronic induction device, just can realize real-time detection that sample axis is drifted about and compensation.

Relative to prior art, the present invention has following useful technique effect:

(1) apparatus structure is simple, and debugging is with easy to operate;

(2) there is higher measurement sensistivity and larger measurement range;

(3) be convenient to apply in introducing microscopic system.

Accompanying drawing explanation

Fig. 1 is the schematic diagram based on the axial drift detection of the sample of double helix light beam and compensation system in the present invention;

Fig. 2 is the phase modulation function distribution schematic diagram of spatial light modulator used in the present invention;

The intensity distribution of gained hot spot on photoelectric sensor part when Fig. 3 is the different out of focus position of sample in the present invention.

Embodiment

Describe the present invention in detail below in conjunction with embodiment and accompanying drawing, but the present invention is not limited to this.

As shown in Figure 1, a kind of sample based on double helix light beam axially drift detects and compensation system, comprising: laser instrument 1, single-mode fiber 2, collimation lens 3, catoptron 4, spatial light modulator 5, Amici prism 6, microcobjective 7, three-dimensional manometer scanning platform 8, field lens 9, optoelectronic induction device 10, computing machine 11.

Wherein, single-mode fiber 2, collimation lens 3, catoptron 4, spatial light modulator 5, Amici prism 6, microcobjective 7 and three-dimensional manometer scanning platform 8 are positioned on the optical axis of emergent light light path of laser instrument 1 successively, microcobjective 7 focus light rays at be positioned at three-dimensional manometer scanning platform 8 testing sample on.

Field lens 9 and optoelectronic induction device 10 are positioned on the optical axis of monitoring light beam light path successively, the optical axis of monitoring light beam light path is vertical with the optical axis of the illuminating bundle of laser instrument 1 outgoing, and monitoring light beam is the reflection ray of illuminating bundle after Amici prism 6 light splitting that testing sample reflects.

Computing machine 11 connects optoelectronic induction device 10 and three-dimensional manometer scanning platform 8 simultaneously.

Wherein, the outgoing end face of single-mode fiber 2 is positioned at the focus in object space place of collimation lens 3, and optoelectronic induction device 10 is positioned at the rear focus place of monitoring light beam condenser lens 11.

Wherein, the phase modulation function f (ρ, φ) of spatial light modulator 5 is set to the phase component of five kinds of different GL basic mode compound light fields superimposed fields, that is,

U(ρ,φ,z)=∑u _mn(ρ,φ,z);(m,n)=(1,0),(3,1),(5,2),(7,3),(9,4)

f(ρ,φ)=arg[U(ρ,φ,0)]

Wherein, (ρ, φ, z) is with three coordinate components of the desirable focus of the microcobjective cylindrical coordinate that is initial point, u _mn(ρ, φ, z) is GL basic mode compound light fields, mn rank, and arg is argument of a complex number function.

Particularly, mn rank GL basic mode compound light field u _mnthe expression formula of (ρ, φ, z) is,

$u_{\mathrm{mn}}(\mathrm{\ρ},\mathrm{\φ},z)=w_0/w\left(\hat{z}\right)\exp (-\stackrel{^2}{\mathrm{\ρ}})\exp \left(i\stackrel{^2}{\mathrm{\ρ}}\hat{z}\right)\exp [-i\arctan \left(\hat{z}\right)]\·{\left(\sqrt{2}\widehat{\mathrm{\ρ}}\right)}^{\left|m\right|}{L}_n^m\left(2\stackrel{^2}{\mathrm{\ρ}}\right)$ $\·\exp \left(\mathrm{im\φ}\right)\exp [-i(2n+m)\arctan \left(\hat{z}\right)]$

Wherein, w ₀for the waist radius of laser beam used, i is imaginary unit, λ is the wavelength of laser beam used, be mn rank Laguerre polynomials.

In said apparatus, optoelectronic induction device is high-speed charge coupled device (CCD:Charge Couple Device).

Adopt the device shown in Fig. 1, its course of work is:

From the illuminating bundle that laser instrument 1 sends, be first imported into single-mode fiber 2, from the illuminating bundle of single-mode fiber 2 outgoing, complete collimation through collimation lens 3.

Illuminating bundle after collimation, after catoptron 4 reflects, incides in spatial light modulator 5 and accepts phase-modulation, forms double helix illuminating bundle; The phase modulation function distribution of spatial light modulator 5 as shown in Figure 2.

Double helix illuminating bundle through Amici prism 6, after to focus on through microcobjective 7 and project on the testing sample that is positioned on three-dimensional manometer scanning platform 8.

Through testing sample reflection illuminating bundle through microcobjective 7 collect after, reflect as monitoring light beam through Amici prism 6.

After monitoring light beam is focused on by field lens 9, form double helix focal beam spot and received by optoelectronic induction device 10, and spot intensity distributed intelligence is sent to computing machine 11.

Computing machine 11 points to the angle of horizontal direction according to the hot spot that obtained spot intensity distributed intelligence calculates double helix hot spot that (double helix focal beam spot has two intensity peak, line between two intensity peak and the angle of horizontal direction, the hot spot being double helix hot spot points to the angle with horizontal direction), and demarcate the relation of this angle (pointing to angle also referred to as focal beam spot) and the axial drift value of sample, using the calibration function of this relational expression as system.

When testing sample generation axial location drifts about, computing machine 11 according to measured monitoring light beam focal beam spot point to angle in the system of having demarcated tracking enquiry to the axial location drift value of corresponding testing sample, and send the axial location of instruction adjustment three-dimensional manometer scanning platform 8 accordingly, realize the correction of the axial location to testing sample.

Specifically:

The present embodiment adopts CCD as optoelectronic induction device 10, and now according to the intensity distributions of focal beam spot on CCD, the focal beam spot that can calculate monitoring light beam points to angle.Testing sample is placed on three-dimensional manometer scanning platform 8, by the axial location of adjustment three-dimensional manometer scanning platform 8, and the intensity distributions of monitoring light beam focal beam spot on real time record CCD, calculate monitoring light beam focal beam spot and point to angle, thus obtain the relation that hot spot points to the axial location drift value of angle and testing sample, using this relational expression as system calibrating function input computing machine 11, the demarcation of completion system.

When testing sample generation axial location drifts about, CCD sends the focal beam spot intensity distributions of monitoring light beam to computing machine 11, after computing machine 11 calculates corresponding hot spot sensing angle, in the system of having demarcated, tracking enquiry is to the axial location drift value of corresponding testing sample, and send the axial location of instruction adjustment three-dimensional manometer scanning platform 8 accordingly, the correction of testing sample axial location can be realized.

In order to check the actual effect of said apparatus and method further, under the present embodiment describes the axially different position excursion amount of testing sample respectively, the light distribution situation of corresponding monitoring light beam focal beam spot, specifically as shown in Figure 3, wherein z ₀for the Rayleigh range of laser beam used.In figure 3, a figure is z=-2.5z ₀the surface of intensity distribution of the focal beam spot formed, b figure is z=-z ₀the surface of intensity distribution of the focal beam spot formed, c figure is the surface of intensity distribution of the focal beam spot that z=0 is formed, and d figure is z=z ₀the surface of intensity distribution of the focal beam spot formed, e figure is z=2.5z ₀the surface of intensity distribution of the focal beam spot formed, it can thus be appreciated that, by measuring the light distribution of monitoring light beam focal beam spot, real-time detection and compensation that testing sample is axially drifted about can be completed simply and effectively.

Claims (10)

1., based on sample axially drift detection and a compensation method for double helix light beam, it is characterized in that, comprise the following steps:

1) laser beam after collimation is incident in spatial light modulator and carries out phase-modulation, obtain double helix illuminating bundle, the focal beam spot of described double helix illuminating bundle presents two intensity peak, and the line between these two intensity peak has revolving property in direction of beam propagation, namely at different axial locations, between two intensity peak, line is different from the angle of horizontal direction;

2) the double helix illuminating bundle line focus described in projects the testing sample be positioned on three-dimensional manometer scanning platform, collects obtain folded light beam through testing sample reflection and by microcobjective;

3) described folded light beam line focus obtains the focal beam spot with two intensity peak, and utilizes the focal beam spot described in the reception of optoelectronic induction device, obtains spot intensity distributed intelligence;

4) angle of line between two intensity peak and horizontal direction is calculated according to described spot intensity distributed intelligence;

5) relation of the angle described in utilization and the axial drift value of sample sets up calibration function;

6) when testing sample generation axial location drifts about, repeat step 1) ~ 4), obtain the angle measured in real time, the axial drift value of current sample is calculated according to described calibration function, and the axial location of described three-dimensional manometer scanning platform is adjusted according to the axial drift value of current sample, complete the correction of the axial location to testing sample.

2., as claimed in claim 1 based on sample axially drift detection and the compensation method of double helix light beam, it is characterized in that, the phase modulation function f (ρ, φ) of described spatial light modulator is

f(ρ,φ)＝arg[U(ρ,φ,0)]

U(ρ,φ,z)＝Σu _mn(ρ,φ,z),n＝0,1,2,…,m＝2n+1

Wherein, (ρ, φ, z) is with three coordinate components of the focus of the microcobjective cylindrical coordinate that is initial point, u _mn(ρ, φ, z) is GL basic mode compound light fields, mn rank, and arg is argument of a complex number function.

3., as claimed in claim 2 based on sample axially drift detection and the compensation method of double helix light beam, it is characterized in that, described mn rank GL basic mode compound light field u _mn(ρ, φ, z) is:

$\begin{array}{c}{u}_{\mathrm{mn}}(\mathrm{\ρ},\mathrm{\φ},z)=w_0/w\left(\hat{z}\right)\exp (-{\widehat{\mathrm{\ρ}}}^2)\exp \left(i{\widehat{\mathrm{\ρ}}}^2\hat{z}\right)\exp [-i\arctan \left(\hat{z}\right)]\·{\left(\sqrt{2}\widehat{\mathrm{\ρ}}\right)}^{\left|m\right|}{L}_n^m\left(2{\widehat{\mathrm{\ρ}}}^2\right)\\ \·\exp \left(\mathrm{im\φ}\right)\exp [-i(2n+m)\arctan \left(\hat{z}\right)]\end{array}$

Wherein, w ₀for the waist radius of laser beam, i is imaginary unit, λ is the wavelength of laser beam used, be mn rank Laguerre polynomials.

4., as claimed in claim 3 based on sample axially drift detection and the compensation method of double helix light beam, it is characterized in that, described (m, n) value is (1,0), (3,1), (5,2), (7,3) and (9,4).

5., as claimed in claim 1 based on sample axially drift detection and the compensation method of double helix light beam, it is characterized in that, described optoelectronic induction device is high-speed charge coupled device.

6., for realizing a device for the axial drift detection of sample as described in any one of Claims 1 to 5 and compensation method, it is characterized in that, comprise:

Laser instrument, for sending the laser instrument of laser beam;

Spatial light modulator, for carrying out phase-modulation to described laser beam;

Three-dimensional manometer scanning platform, for placing testing sample;

Microcobjective, for the light beam of described spatial light modulator outgoing is focused to testing sample, and collects the folded light beam of launching through described testing sample;

Field lens, for focusing on described folded light beam and obtaining focal beam spot;

Optoelectronic induction device, the focal beam spot described in reception, and obtain spot intensity distributed intelligence;

And the computing machine to be connected with described three-dimensional manometer scanning platform and optoelectronic induction device.

7. device as claimed in claim 6, is characterized in that, be furnished with single-mode fiber, collimation lens and catoptron successively between described laser instrument and spatial light modulator.

8. device as claimed in claim 6, it is characterized in that, the phase modulation function f (ρ, φ) of described spatial light modulator is

f(ρ,φ)＝arg[U(ρ,φ,0)]

U(ρ,φ,z)＝Σu _mn(ρ,φ,z),n＝0,1,2,…,m＝2n+1

Wherein, (ρ, φ, z) is with three coordinate components of the focus of the microcobjective cylindrical coordinate that is initial point, u _mn(ρ, φ, z) is GL basic mode compound light fields, mn rank, and arg is argument of a complex number function;

Described mn rank GL basic mode compound light field u _mn(ρ, φ, z) is:

$\begin{array}{c}{u}_{\mathrm{mn}}(\mathrm{\ρ},\mathrm{\φ},z)=w_0/w\left(\hat{z}\right)\exp (-{\widehat{\mathrm{\ρ}}}^2)\exp \left(i{\widehat{\mathrm{\ρ}}}^2\hat{z}\right)\exp [-i\arctan \left(\hat{z}\right)]\·{\left(\sqrt{2}\widehat{\mathrm{\ρ}}\right)}^{\left|m\right|}{L}_n^m\left(2{\widehat{\mathrm{\ρ}}}^2\right)\\ \·\exp \left(\mathrm{im\φ}\right)\exp [-i(2n+m)\arctan \left(\hat{z}\right)]\end{array}$

Wherein, w ₀for the waist radius of laser beam, i is imaginary unit, λ is the wavelength of laser beam used, $w\left(\hat{z}\right)=w_0{(1+{\hat{z}}^2)}^{1/2},$ $\widehat{\mathrm{\ρ}}=\mathrm{\ρ}/w\left(\hat{z}\right),$ be mn rank Laguerre polynomials.

9. device as claimed in claim 8, it is characterized in that, described (m, n) value is (1,0), (3,1), (5,2), (7,3) and (9,4).

10. device as claimed in claim 6, it is characterized in that, described optoelectronic induction device is high-speed charge coupled device.