CN101929848B - Product confocal-scanning detection method with high spatial resolution - Google Patents

Abstract

The invention relates to a product confocal-scanning detection method with high spatial resolution, belonging to the technical field of detection of surface minuteness structure and biologic microscopic imaging, wherein the method comprises the steps of: multiplying the defocusing signals of a double biased detector in a differential confocal double receiving optical path to get product confocal signals; detecting and imaging the detected sample; improving the vertical and transverse resolution of a product confocal microscopical detection method by the product of the two biased signals thereby achieving the product confocal detection with high spatial resolution. The method can also improve the spatial resolution by combining with an optical super-resolution confocal detection method; meets the requirements of high spatial resolution and high precision of detection and imaging; and is applicable for the detection of surface three-dimensional minuteness structure, micro-step, line width and surface appearance, and the detection of biologic imaging with high precision.

Description

Product confocal-scanning detection method with high spatial resolution

Technical field

The invention belongs to micro-imaging and microscopic measurement technical field, a kind of method that can be used for detecting surface three dimension microtexture, little step, integrated circuit live width and surface topography and biomedical sector high resolution micro-imaging is provided especially.

Background technology

Confocal microscopy has obtained using widely at high-resolution imaging and detection range with its exclusive three-dimensional chromatography imaging capability, but owing to limited by the principle of diffraction effect, has restricted the further raising of its resolving power.For fundamentally breaking through diffraction limit, improve the resolution characteristic of confocal microscopic method, Chinese scholars has been done many researchs, and has proposed numerous non-traditional confocal microscopic imaging principle and ultra-resolution method.

In order to improve the azimuthal resolution of confocal microscopy, the C-H.Lee of Taiwan Univ. etc. proposed non-interference difference confocal microscopy theoretical (Optics Common.1997,35:232-237), it utilizes response curve hypotenuse linearity range to realize that nanoscale detects; The Tan Jiubin of Harbin Institute of Technology, Wang Fusheng and Zhao Weiqian have proposed " differential confocal formula nanoscale optical focus detection method "; Its azimuthal resolution reaches 2nm (" the 3rd both sides of the Straits and measure scientific and technological scientific seminar collection of thesis "; Lanzhou, 2000:59～63); Chinese patent " the differential confocal scanning detection method with high spatial resolution " (patent No.: ZL 200410006359.6) utilizes and realizes axial nanoscale, laterally submicron order detection between the response curve linear zone; Chinese patent " confocal microscope " (application number: 01122439.8, publication number: CN 1395127A) propose interferometric method is incorporated in traditional confocal microscopic imaging technology, is used to improve the method for azimuthal resolution; Chinese patent " double-frequency confocal step height microscope measuring device " (application number: 02120884.0, publication number: CN 1384334A) proposed a kind of double-frequency confocal step and interfered microscopic measuring method; Chinese patent " have high-space resolution imaging ability confocal interference microscope (application number: 200410096338.8, publication number: CN1614457) " etc.; 1998; American scholar T asso R.M.Sales etc. designed the azimuthal resolution that the pure phase place iris filter in two districts improves optical system (Axial superresolution with phase-only pupil filers.Optics Communications.1998,156:227-230).

But above-mentioned achievement only is confined to improve and the azimuthal resolution that improves confocal microscope system, can't improve its transverse resolution, and the raising of confocal microscope system transverse resolution improves the key of its spatial resolution just.

At present, the method and the technology that can be used for improving the transverse resolution of confocal microscopy mainly contain spatial frequency lambda limiting process, pupil filtering method and the confocal method of 4PI etc.Wherein, adopting the three-dimensional super-resolution iris filter is the main means that improve the optical detecting method spatial resolution, but it should take into account azimuthal resolution and take into account transverse resolution again, and the three-dimensional super-resolution effect is not remarkable.

Summary of the invention

The objective of the invention is in order to overcome the deficiency of above-mentioned prior art; A kind of optical detecting method with high spatial resolution is provided, realizes the high spatial resolution optical detection and the micro-imaging of three-dimensional microstructure, little step, integrated circuit live width, object surface appearance and biomedical sector are detected.

The present invention adopts the double reception light path arrangement of differential confocal microscopy and the detection of double detector product that sample is carried out scanning survey; Incident beam incides on the sample through polarization spectroscope, quarter wave plate, measurement object lens; After the sample reflection; After measuring object lens, quarter wave plate, incide polarization spectroscope once more, be divided into two-way through the polarization spectroscope beam reflected by spectroscope, the one tunnel is focused on by condenser; Pin hole is positioned at the burnt front distance M of condenser place, and detector is positioned at behind the pin hole and records the intensity curve I that reaction sample convex-concave changes ₁(v, u, u _M), another road is focused on by condenser, and it is defocused apart from the M place that another pin hole is positioned at another condenser, and another detector is positioned at behind another pin hole and records the intensity curve I that reaction sample convex-concave changes ₂(v, u-u _M), wherein, the normalization axial distance that M is corresponding is u _M, u is axial normalization optical coordinate, v is horizontal normalization optical coordinate, u _MBe the normalization axial distance, it is characterized in that:

(1) with I ₁(v, u, u _M) and I ₂(v, u ,-u _M) multiply each other and carry out normalization and handle, obtain the intensity curve I that corresponding sample convex-concave changes _MCM(v, u, u _M);

(2) according to curve I _MCM(v, u, u _M) intensity size between linear zone, or according to curve I _MCM(v, u, u _M) position of maximum of intensity, reconstruct the surface topography and the micro-scale of sample.

Wherein, optimize between its corresponding condenser focus of pin hole apart from u _M, can reduce the halfwidth of product confocal response curve, improve the spatial resolution of confocal microscopy, u _MHalfwidth and focus response intensity by product confocal axial response curve are confirmed jointly.

According to " being correlated with " thought, with two axialy offset signal multiplications that detect, can improve the azimuthal resolution and the transverse resolution of system simultaneously, reach the purpose that improves spatial resolution.

Another kind of detection method of the present invention adopts the double reception light path arrangement of differential confocal microscopy and the detection of double detector product that sample is carried out scanning survey; Incident beam incides on the sample through optical ultra-discrimination device, polarization spectroscope, quarter wave plate, measurement object lens; After the sample reflection; After measuring object lens, quarter wave plate, incide polarization spectroscope once more, be divided into two-way through the polarization spectroscope beam reflected by spectroscope, the one tunnel is focused on by condenser; Pin hole is positioned at the burnt front distance M of condenser place, and detector is positioned at behind the pin hole and records the intensity curve I that reaction sample convex-concave changes ₁(v, u, u _M), another road is focused on by another condenser, and it is defocused apart from the M place that another pin hole is positioned at another condenser, and another detector is positioned at behind another pin hole and records the intensity curve I that reaction sample convex-concave changes ₂(v, u ,-u _M), wherein, the normalization axial distance that M is corresponding is u _M, u is axial normalization optical coordinate, v is horizontal normalization optical coordinate, u _MBe the normalization axial distance, it is characterized in that:

(1) with I ₁(v, u, u _M) and I ₂(v, u ,-u _M) multiply each other and carry out normalization and handle, obtain the intensity curve I that corresponding sample convex-concave changes _MCM(v, u, u _M);

(2) parameter of optimization optical ultra-discrimination device satisfies super-resolution parameter G _rWith the designing requirement of S, make the Airy disk main lobe of product confocal microscopic system obtain sharpening, further improve the microscopical transverse resolution of product confocal, wherein G _rThe ratio of the ratio of transverse response curve halfwidth when having or not the optical ultra-discrimination device, S focus intensity when having or not the optical ultra-discrimination device;

(3) according to curve I _MCM(v, u, u _M) intensity in linear interval is big or small, or according to curve I _MCM(v, u, u _M) position of maximum of intensity, reconstruct the surface topography and the micro-scale of sample.

Wherein, when adopting the optical ultra-discrimination device to carry out transverse super-resolution, optimize between its corresponding condenser focus of pin hole apart from u _M, can reduce the halfwidth of product confocal response curve, improve the spatial resolution of confocal microscopy, u _MHalfwidth and focus response intensity by product confocal axial response curve are confirmed jointly.

The optical ultra-discrimination confocal method that improves transverse resolution is merged with the product confocal detection method that improves spatial resolution mutually, constitute optical ultra-discrimination product confocal detection method.The raising of spatial resolution can be through differential confocal light path arrangement and product survey and realize; Adopt the optical ultra-discrimination device of particular design that the mask of differential confocal microscopic system is revised; And then change wavefront; Sharpening Airy disk main lobe further improves the transverse resolution of product confocal microscopic system, finally improves the spatial resolution of product confocal microscopic system.The optical ultra-discrimination device can be the iris filter that comprises amplitude type wave filter, phase type wave filter and complex amplitude mode filter, can also be the shaping binary optical device that produces ring light.

Detection technique of the present invention has following characteristics and good result:

1. compare with existing confocal technology, significantly improved the aerial image detectability of confocal microscopy;

2. utilize " being correlated with " notion, adopt the product of biasing detectable signal to handle the shortcoming of having avoided existing three-dimensional super-resolution technology can't take into account axial and transverse resolution, can significantly improve azimuthal resolution and transverse resolution simultaneously;

3. also merged the optical ultra-discrimination technology, further improved the transverse resolution of confocal microscopy, it is more remarkable to make spatial resolution improve effect.

Description of drawings

Fig. 1 is the product confocal-scanning detection method synoptic diagram with high spatial resolution;

Fig. 2 is normalized response curve I _MCM(v, u, u _M);

Fig. 3 is the product confocal-scanning detection method synoptic diagram with high spatial resolution;

Fig. 4 is the product confocal-scanning detection method sensing principle with high spatial resolution;

Fig. 5 is detector offset u _MRelation curve with the transverse response signal;

Fig. 6 is detector offset u _MRelation curve (a) axial strength normalized curve (b) axial strength curve with the axial response signal;

Fig. 7 has the product confocal-scanning detection method synoptic diagram of high spatial resolution for adopting shaping annular illuminaton;

Fig. 8 is u _M=6 o'clock ε and the horizontal relation of normalized response curve;

Fig. 9 is u _MRelation (a) the axial strength curve (b) of=6 o'clock ε and axial response curve is the normalized intensity curve axially;

Figure 10 is ε=0.50 o'clock μ _MWith the axial normalized intensity curve of relation (a) the axial strength curve (b) of axial response curve;

Figure 11 is side-play amount μ _MThe product confocal-scanning detection method axial response curve that had high spatial resolution at=5.21 o'clock;

Figure 12 is step transversal scanning comparison figure;

Wherein, 1-optical ultra-discrimination device, the 2-polarization spectroscope, the 3-1/4 wave plate, 4-measures object lens; The 5-sample, 6-spectroscope, 7, the 8-condenser, 9, the 10-pin hole, 11, the 12-detector; 13-product confocal double reception light path, 14-light source, 15-collimator and extender device, 16-spatial filtering pin hole, 17-micro-displacement work table; The 18-multiplier, 19-displacement transducer, 20-piezoelectric ceramic actuator, 21-driving power; The 22-amplification treatment circuit, 23-micro-computer processing system, 24-shaping binary optical device, 25-incident beam.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is described further.

Basic thought of the present invention is that the intensity curve that detector is measured multiplies each other and normalization is handled, and can improve the azimuthal resolution and the transverse resolution of system simultaneously, reaches the purpose that improves spatial resolution.

As shown in Figure 1, empty frame partly is a product confocal double reception light path 13, and after incident beam process polarization spectroscope 2, quarter wave plate 3 transmissions, measured object lens 4 focus on sample 5 surfaces.Through the measuring light of sample 5 surface reflections, after being reflected by polarization spectroscope 2 through quarter wave plate 3 once more, be divided into two-beam by spectroscope 6 again, and focused on by two identical condensers 7 and 8 respectively.Pin hole 9 places the defocused apart from the M place of condenser 7 focal planes with detector 11, and pin hole 10 and detector 12 place the burnt front distance M place of condenser 8 focal planes, and the optics normalization displacement corresponding apart from M is u _M

If axially the normalization optical coordinate is u, laterally the normalization optical coordinate is v.When sample 5 carried out axial and transversal scanning, detector 12 recorded scanning response curve I ₁(v, u, u _M), detector 11 records scanning response curve I ₂(v, u ,-u _M).With response curve I ₁(v, u, u _M) and I ₂(v, u ,-u _M) carry out product and carry out the normalization processing, obtain the normalized response curve I as shown in Figure 2 of this measuring method _MCM(v, u, u _M), promptly

$I_{\mathrm{mcm}}(v,u,u_M)=\frac{I_1(v,u,u_M)\×I_2(v,u,-u_M)}{I_1(\mathrm{0,0},u_M)\×I_2(\mathrm{0,0},-u_M)}---\left(1\right)$

When considering axial resolution characteristic, v is constant and is made as c that following formula can be reduced to:

$I_{\mathrm{mcm}}(c,u,u_M)=\frac{I_1(c,u,u_M)\×I_2(c,u,-u_M)}{I_1(\mathrm{0,0},u_M)\×I_2(\mathrm{0,0},-u_M)}---\left(2\right)$

As shown in Figure 1, when the product confocal system works in out of focus when zone, adopt the hypotenuse linearity range that sample 5 is measured, as can be seen from the figure, the hypotenuse of the confocal family curve d of hypotenuse remolding sensitivity of s curve is highly sensitive, promptly azimuthal resolution is improved; When product confocal system works during in focus, adopt maximal value that sample 5 is measured, as can be seen from the figure the halfwidth of s curve is narrower than the halfwidth of confocal family curve d, and promptly azimuthal resolution is improved.As shown in Figure 1, product confocal system responses curve I _MCM(v, c, u _M) halfwidth than confocal system response curve I _CmThe halfwidth of (v, c, 0) is narrow, and promptly transverse resolution is improved.Therefore, when utilizing the product confocal system that sample is scanned, response curve I _MCM(v, u, u _M) the concavo-convex variation that reflected sample 5 of light intensity magnitude or its light intensity maximum value position in the hypotenuse linearity range; Utilize surface topography and micro-scale that this value size just can reconstruct sample 5; Azimuthal resolution and transverse resolution all are improved, and promptly spatial resolution is improved.

Embodiment 1

Improve spatial resolution as one of embodiments of the invention with product confocal micro measurement method below, the product confocal micro measurement method that the present invention is had high spatial resolution further specifies as follows:

As shown in Figure 4; Light source 14 sends the laser beam that wavelength is λ=633nm, expands bundle through collimator and extender device 15 then and is the Gaussian beam of φ 4mm, through spatial filtering pin hole 16; Make it to become pointolite; Directional light behind the expansion bundle is through polarization spectroscope 2 transmissions and reflection, and wherein the p light through polarization spectroscope 2 transmissions converges on the surface of sample 5 through quarter wave plate 3 and measurement object lens 4, and the light that reflects through sample 5 then returns along former road; Once more through becoming s light behind the quarter wave plate 3 and being reflected by polarization spectroscope 2; This reflected light is divided into two equicohesive folded light beam of bundle and transmitted light beams through spectroscope 6, and focuses on through condenser 7 and condenser 8 respectively, pin hole 9 and equidistant respectively the burnt preceding and defocused of condenser 7 and condenser 8 that place of pin hole 10; And receive its light intensity signal by detector 11 and detector 12 respectively; The light intensity signal that detector 11 and detector 12 are detected multiplies each other through multiplier 18, after amplification treatment circuit 22 amplifies, just obtains near the focus error signal of confocal sensor focus again, the corresponding sample of this signal 5 distance focal point positions size.Be the extension sensor range ability, be cemented in the object lens Z that is made up of piezoelectric ceramic actuator 20 and displacement transducer 19 in the spotting scaming system with measuring object lens 4, these object lens Z reaches 350 μ m, sweep frequency 150Hz to the range ability of spotting scaming system.Micro-computer processing system 23 is according to the output of the feedback signal controlling and driving power supply 21 of displacement transducer 19; Make piezoelectric ceramic actuator 20 do axial displacement; When sample 5 processes are measured object lens 4 focal planes; Detected product light intensity signal is through near the maximal value, and as the aiming trigger pip, near the signal sum the maximal value the when signal that this moment, displacement transducer 19 recorded triggers with aiming can reflect that just the axial location of sample 5 changes with it.

The resolution characteristic of the confocal sensor measurement of present embodiment high spatial resolution tracking mode draws according to following Theoretical Calculation.

The microscopical light intensity response function of reflection-type confocal I (v, u, u during the detector biasing _M) be:

$I(v,u,u_M)={|{\∫}_0^{1}P\left(\mathrm{\ρ}\right)e^{\frac{\mathrm{iu}{\mathrm{\ρ}}^2}{2}}{J}_0\left(\mathrm{\ρv}\right)\mathrm{\ρd\ρ}\·{\∫}_0^{1}P\left(\mathrm{\ρ}\right)e^{\frac{i(u+u_M){\mathrm{\ρ}}^2}{2}}{J}_0\left(\mathrm{\ρv}\right)\mathrm{\ρd\ρ}|}^2---\left(3\right)$

Wherein,

$\left\{\begin{array}{c}v=2\mathrm{kr}\sin \frac{{\mathrm{\α}}_0}{2}\\ u=4\mathrm{kz}{\sin }^2\frac{{\mathrm{\α}}_0}{2}\end{array}\right.---\left(4\right)$

Z is for moving axially distance, and r is a radial coordinate, u _MBe pin hole axial offset, α ₀Be the numerical aperture of objective angle.

The normalization pupil function does

The horizontal resolution characteristic of this measuring method is:

When measured object is in out-of-focus appearance, two point probes are at axial skew+u respectively _MWith-u _MThe time, can get by formula (3), the transverse intensity distribution characteristic is:

$I_{\mathrm{mcm}}(v,u,u_M){|}_{u=C}=I(v,u,u_M)\·I(v,u,-u_M)$

${=|{\∫}_0^{1}P\left(\mathrm{\ρ}\right)e^{\frac{\mathrm{iu}{\mathrm{\ρ}}^2}{2}}{J}_0\left(\mathrm{\ρv}\right)\mathrm{\ρd\ρ}\·{\∫}_0^{1}P\left(\mathrm{\ρ}\right)e^{\frac{i(u+u_M){\mathrm{\ρ}}^2}{2}}{J}_0\left(\mathrm{\ρv}\right)\mathrm{\ρd\ρ}|}^2---\left(6\right)$

$\×{|{\∫}_0^{1}P\left(\mathrm{\ρ}\right)e^{\frac{\mathrm{iu}{\mathrm{\ρ}}^2}{2}}{J}_0\left(\mathrm{\ρv}\right)\mathrm{\ρd\ρ}\·{\∫}_0^{1}P\left(\mathrm{\ρ}\right)e^{\frac{i(u-u_M){\mathrm{\ρ}}^2}{2}}{J}_0\left(\mathrm{\ρv}\right)\mathrm{\ρd\ρ}|}^2$

When sample 5 was in the focal plane and is u=0, laterally resolution characteristic was with pin hole axial offset u _MChanging Pattern as shown in Figure 5.As can be seen from Figure 5, u _M＜10 o'clock, the halfwidth of light intensity was hardly with u _MChange, i.e. transverse resolution and pin hole axial offset u _MIrrelevant.

The axial resolution characteristic of this measuring method:

Get focus error signal by formula (3):

$I_{\mathrm{mcm}}(v,u,u_M){|}_{u=C}=I(v,u,u_M)\·I(v,u,-u_M)$

$={\sin c}^2\left(\frac{2u+u_M}{4\mathrm{\&pi;}}\right)\&times;{\sin c}^2\left(\frac{2u-{\mathrm{<figure-callout\; id="4"\; label="u\; M"\; filenames="HSA00000190443800011.png,HSA00000190443800012.png"\; state="\{\{state\}\}">u</figure-callout>}}_M}{4\mathrm{\&pi;}}\right)---\left(7\right)$

Corresponding relation between focus error signal and the detection range u gets the relation curve s between focus error signal and the detection range z by formula (4) again suc as formula shown in (7).

In the product confocal sensing technology, detector axial offset u _MTo directly influence sensor axis to resolution characteristic, Fig. 6 has provided axial resolution characteristic and side-play amount u _MRelation curve.As can be seen from Figure 6, u _MIncrease, it is that azimuthal resolution improves that axial halfwidth reduces, but the response intensity reduction, and the secondary lobe increase, unfavorable to the imaging detection, but the pin hole of confocal method can suppress its influence.

Adopt the method detector, should take all factors into consideration azimuthal resolution and energy loss, make its performance preferable.

Embodiment 2

Improve spatial resolution as two of embodiments of the invention with shaping circular light formula product confocal micro measurement method below, the product confocal micro measurement method that the present invention is had high spatial resolution further specifies as follows:

As shown in Figure 7, empty frame partly is the micro-double reception light path arrangement 13 of product confocal, and the optical ultra-discrimination device is a shaping binary optical device 24.Under the monochromation illumination condition, have the microscopical light intensity response function of reflection-type confocal I (v, u, the u of pupil function P (ρ) _M) be:

$I(v,u,u_M)={|{\&Integral;}_{\mathrm{\&epsiv;}}^{1}P\left(\mathrm{\&rho;}\right)e^{\frac{\mathrm{iu}{\mathrm{\&rho;}}^2}{2}}{J}_0\left(\mathrm{\&rho;v}\right)\mathrm{\&rho;d\&rho;}\&CenterDot;{\&Integral;}_{\mathrm{\&epsiv;}}^{1}P\left(\mathrm{\&rho;}\right)e^{\frac{i(u+u_M){\mathrm{\&rho;}}^2}{2}}{J}_0\left(\mathrm{\&rho;v}\right)\mathrm{\&rho;d\&rho;}|}^2---\left(\text{8}\right)$

Wherein,

$\left\{\begin{array}{c}v=2\mathrm{kr}\sin \frac{{\mathrm{\&alpha;}}_0}{2}\\ u=4\mathrm{<figure-callout\; id="2"\; label="kz\; sin"\; filenames="HSA00000190443800011.png,HSA00000190443800012.png"\; state="\{\{state\}\}">kz</figure-callout>}{\sin }^{}{}^2\frac{{\mathrm{\&alpha;}}_0}{2}\end{array}\right.---\left(9\right)$

Z is for moving axially distance, and r is a radial coordinate, and ε is a laser beam normalization radius, u _MBe pin hole axial offset, α ₀Be the numerical aperture of objective angle.

The normalization pupil function does

When utilizing the binary optical device shaping circular light, the light of core is transferred on the outer shroud, and system is the noenergy loss in energy transfer process, supposes that the amplitude on the ring is A, and then beam intensity can be expressed as after the shaping:

$I\left(r\right)=\left\{\begin{array}{cc}0& 0<r\&le;\mathrm{\&epsiv;}\\ A^2& \mathrm{\&epsiv;}<r<1\end{array}\right.---\left(11\right)$

According to law of conservation of energy,

$A=\frac{1}{\sqrt{1-{\mathrm{\&epsiv;}}^2}}---\left(12\right)$

The horizontal resolution characteristic of this measuring method is:

When sample 5 is in out-of-focus appearance, two point probes are at axial skew+u respectively _MWith-u _MThe time, can get by formula (8), the transverse intensity distribution characteristic is:

$I_{\mathrm{mcm}}(v,u,u_M){|}_{u=C}=I(v,u,u_M)\&CenterDot;I(v,u,-u_M)$

$={|{\&Integral;}_{\mathrm{\&epsiv;}}^1{P}_1\left(\mathrm{\&rho;}\right)e^{\frac{\mathrm{iu}{\mathrm{\&rho;}}^2}{2}}{J}_0\left(\mathrm{\&rho;v}\right)\mathrm{\&rho;d\&rho;}\&CenterDot;{\&Integral;}_{\mathrm{\&epsiv;}}^1{P}_1\left(\mathrm{\&rho;}\right)e^{\frac{i(u+u_M){\mathrm{\&rho;}}^2}{2}}{J}_0\left(\mathrm{\&rho;v}\right)\mathrm{\&rho;d\&rho;}|}^2---\left(\text{13}\right)$

${\&times;|{\&Integral;}_{\mathrm{\&epsiv;}}^1{P}_1\left(\mathrm{\&rho;}\right)e^{\frac{\mathrm{iu}{\mathrm{\&rho;}}^2}{2}}{J}_0\left(\mathrm{\&rho;v}\right)\mathrm{\&rho;d\&rho;}\&CenterDot;{\&Integral;}_{\mathrm{\&epsiv;}}^1{P}_1\left(\mathrm{\&rho;}\right)e^{\frac{i(u-u_M){\mathrm{\&rho;}}^2}{2}}{J}_0\left(\mathrm{\&rho;v}\right)\mathrm{\&rho;d\&rho;}|}^2$

When sample 5 was in the focal plane and is u=0, laterally resolution characteristic was as shown in Figure 8 with the Changing Pattern of ε.As can be seen from Figure 8, ε increases, and the halfwidth of light intensity is more little to be that transverse resolution is high more.

The axial resolution characteristic of this measuring method:

Get focus error signal by formula (8):

$I_{\mathrm{mcm}}(v,u,u_M){|}_{u=C}=I(v,u,u_M)\&CenterDot;I(v,u,-u_M)$

${=\sin c}^2\left[\frac{2u+u_M}{4\mathrm{\&pi;}}\left({1-\mathrm{\&epsiv;}}^2\right)\right]\&times;{\sin c}^2\left[\frac{2u-{\mathrm{<figure-callout\; id="4"\; label="u\; M"\; filenames="HSA00000190443800011.png,HSA00000190443800012.png"\; state="\{\{state\}\}">u</figure-callout>}}_M}{4\mathrm{\&pi;}}\left({1-\mathrm{\&epsiv;}}^2\right)\right]---\left(14\right)$

Corresponding relation between focus error signal and the detection range u gets the relation curve s between focus error signal and the detection range z by formula (9) again suc as formula shown in (14).

In the ring light product confocal sensing technology, detector axial offset u _MTo directly influence sensor axis to resolution characteristic, and got by formula (14) and formula (9), the resolving power of ring light product confocal detection method response curve is by two pin hole side-play amount u _M, the decision of ring light normalization radius ε and numerical aperture of objective.

Fig. 9 has provided u _M=6, ε=0.25,0.50 and 0.75 o'clock axial resolution characteristic curve, Figure 10 has provided ε=0.5, u _MRelation curve with axial resolution characteristic.Can find out that from Fig. 9 and 10 ε increases, axially the halfwidth increase is that azimuthal resolution descends, but response intensity increases; u _MIncrease, axially to reduce be that azimuthal resolution improves to halfwidth, but response intensity reduces, and the Sidelobe Suppression that causes because of out of focus must be obvious more.

Adopt the method detector, should take all factors into consideration azimuthal resolution, transverse resolution and energy loss, make its performance best.

The main devices model and the parameter of experimental verification system of product confocal-scanning detection method that the present invention has high spatial resolution is following:

As shown in Figure 4, the measurement object lens 4 in the experiment are preferentially selected 10 * 0.25,40 * 0.65 and 60 * 0.85 flat field achromatic micro objective respectively for use; Photodetector 11 and the 12 preferential 2001 type photelectric receivers that adopt U.S. NEWFOCUS company to produce, saturation power is 10mW, the maximum adjustable gain is 10 ⁴, the minimal noise equivalent power does

Response at wavelength 632.8nm place is 0.42A/W; Pin hole 9 and 10 is preferentially selected the PH-10 type pin hole of U.S. NEWPORT company for use, and it is made up of ultra-thin Mo, and aperture size is 10 μ m, and thickness is 15.24 μ m; The driver of micro-displacement work table 17 select preferentially that U.S. NEWFOCUS company produces for use on a large scale, high stability Picomotor micro-displacement driver; The flexible hinge work bench that is equipped with scale down and is 5: 1 is formed nano level fine motion calibration system, and each driving pulse of Picomotor micro-displacement driver can make micro-displacement work table 17 obtain the feeding of 2nm; Measure the fiber object lens micropoistioning device of the axial tracking location German PI of the preferential employing company production of object lens 4; It is made up of piezoelectric ceramic actuator 20, displacement transducer 19 and axial actuating mechanism etc.; The driving resolving power is 10nm, range 300 μ m, and the loading frequency response is 100Hz.

Super-resolution performance The tested results based on the high spatial resolution product confocal sensor surveying unit of the inventive method is:

The resolution characteristic of system can be examined through the standard step that the Dimension3100 type atomic force microscope of U.S. DI company is worn.Sample 5 is selected the standard step of 100nm height for use, measures object lens 4 and selects 60 * 0.85 object lens for use, and step is placed on the objective table; Adjust step vertically through micro-adjusting mechanism; Laser accunputure is focused on the ledge surface, and the edge horizontal direction vertical with laser accunputure moves step, and micro-displacement work table 17 resolving powers are 2nm; Moving range 12 μ m; With the amount of movement of HP5528A two-frequency laser interferometer detection step, its resolving power is 0.01 μ m, and drive system is the amount of feeding fine motion step of 0.01 μ m with resolving power.

Figure 11 has provided side-play amount u _M=5.21 product confocal axial response curves.

Figure 12 has provided confocal step scanning curve and product confocal step scanning curve, and product confocal step scanning curve skip zone slope variation is bigger.

More than combine accompanying drawing specific embodiments of the invention and simulated effect to be described; But these explanations can not be understood that to have limited scope of the present invention; Protection scope of the present invention is limited the claims of enclosing, and any change of on claim of the present invention basis, carrying out all is protection scope of the present invention.

Claims (5)

1. the product confocal-scanning detection method that has high spatial resolution; Adopt the double reception light path arrangement and the detection of double detector product of differential confocal microscopy that sample is carried out scanning survey; Incident beam incides on the sample through polarization spectroscope, quarter wave plate, measurement object lens, after the sample reflection, after measuring object lens, quarter wave plate, incides polarization spectroscope once more; Be divided into two-way through the polarization spectroscope beam reflected by spectroscope; One the tunnel is focused on by condenser, and pin hole is positioned at the burnt front distance M of condenser place, and detector is positioned at behind the pin hole and records the intensity curve I of reaction sample convex-concave variation ₁(v, u, u _M), another road is focused on by another condenser, and it is defocused apart from the M place that another pin hole is positioned at said another condenser, and another detector is positioned at behind said another pin hole and records the intensity curve I that reaction sample convex-concave changes ₂(v, u ,-u _M), wherein, the normalization axial distance that M is corresponding is u _M, u is axial normalization optical coordinate, v is horizontal normalization optical coordinate, u _MBe the normalization axial distance, it is characterized in that:

(1) with I ₁(v, u, u _M) and I ₂(v, u ,-u _M) multiply each other and carry out normalization and handle, obtain the intensity curve I that corresponding sample convex-concave changes _MCM(v, u, u _M);

(2) according to curve I _MCM(v, u, u _M) intensity in linear interval is big or small, or according to curve I _MCM(v, u, u _M) position of maximum of intensity, reconstruct the surface topography and the micro-scale of sample.

2. the product confocal-scanning detection method with high spatial resolution according to claim 1 is characterized in that: optimize between its corresponding condenser focus of pin hole apart from u _M, can reduce the halfwidth of product confocal axial response curve, improve the spatial resolution of confocal microscopy, u _MHalfwidth and focus response intensity by product confocal axial response curve are confirmed jointly;

3. the product confocal-scanning detection method that has high spatial resolution; Adopt the double reception light path arrangement and the detection of double detector product of differential confocal microscopy that sample is carried out scanning survey; Incident beam incides on the sample through optical ultra-discrimination device, polarization spectroscope, quarter wave plate, measurement object lens, after the sample reflection, after measuring object lens, quarter wave plate, incides polarization spectroscope once more; Be divided into two-way through the polarization spectroscope beam reflected by spectroscope; One the tunnel is focused on by condenser, and pin hole is positioned at the burnt front distance M of condenser place, and detector is positioned at behind the pin hole and records the intensity curve I of reaction sample convex-concave variation ₁(v, u, u _M), another road is focused on by another condenser, and it is defocused apart from the M place that another pin hole is positioned at said another condenser, and another detector is positioned at behind said another pin hole and records the intensity curve I that reaction sample convex-concave changes ₂(v, u ,-u _M), wherein, u is axial normalization optical coordinate, v is horizontal normalization optical coordinate, u _MBe the normalization axial distance, the normalization axial distance that M is corresponding is u _M, it is characterized in that:

(1) with I ₁(v, u, u _M) and I ₂(v, u ,-u _M) multiply each other and carry out normalization and handle, obtain the intensity curve I that corresponding sample convex-concave changes _MCM(v, u, u _M);

(2) parameter of optimization optical ultra-discrimination device satisfies super-resolution parameter G _rWith the designing requirement of S, make the Airy disk main lobe of product confocal microscopic system obtain sharpening, further improve the microscopical transverse resolution of product confocal, wherein G _rThe ratio of the ratio of transverse response curve halfwidth when having or not the optical ultra-discrimination device, S focus intensity when having or not the optical ultra-discrimination device;

(3) according to curve I _MCM(v, u, u _M) intensity size between linear zone, or according to curve I _MCM(v, u, u _M) position of maximum of intensity, reconstruct the surface topography and the micro-scale of sample.

4. the product confocal-scanning detection method with high spatial resolution according to claim 3 is characterized in that: when adopting the optical ultra-discrimination device to carry out transverse super-resolution, optimize between its corresponding condenser focus of pin hole apart from u _M, can reduce the halfwidth of product confocal axial response curve, improve the spatial resolution of confocal microscopy, u _MHalfwidth and focus response intensity by product confocal axial response curve are confirmed jointly;

5. the product confocal-scanning detection method with high spatial resolution according to claim 3 is characterized in that: the optical ultra-discrimination device can be phase-type wave filter, amplitude type wave filter, amplitude position phase hybrid filter or ring light shaping optical device.

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