CN105466358A - Chromatography microscopic measurement method for parallel optical lines - Google Patents

Abstract

The invention discloses a chromatography microscopic measurement method for parallel optical lines, and belongs to the technical field of optical microscopic imaging and precise measurement. The method comprises the steps: firstly calculating and obtaining a microscopic chromatography image field of a standard plane reflector through employing a formula shown in the description, wherein I1, I2 and I3 are respectively three structured light modulation fields; drawing an axial chromatography response intensity curve corresponding to the central point of the obtained microscopic chromatography image field; secondly cutting a single-side linear section of the curve, building a theoretical correlation mode of an intensity field and a sample surface height, obtaining a measurement calibration linear curve, and forming a height-intensity look-up table; and finally replacing the standard plane reflector with an actual to-be-measured sample, obtaining the surface height values of all points in a single scanning microscopic image field according to the height-intensity look-up table, and achieving the chromatography detection of the surface topography three-dimensional structure of the surface of the sample in a certain axial range. The method can be used for the non-axial mechanical scanning and parallel and three-dimensional chromatography quick detection.

Description

A kind of parallel optical line chromatography microscopic measuring method

Technical field:

The invention belongs to optical microphotograph imaging and Technology of Precision Measurement field, particularly relate to a kind of parallel optical line chromatography microscopic measuring method.

Background technology:

Optical microphotograph measurement mechanism human knowledge and understand microcosmic Scientific World process in serve important impetus, middle and later periods the 1950's, Harvard University post-doctor M.Minsky has invented a kind of brand-new optical microscopy device, i.e. confocal microscope, which employs an illumination and point detects and introduces point by point scanning structure to realize sample interior three-dimensional structure three-dimensional imaging.1997, Regius professor M.A.A.Neil and T.Wilson etc. study for a long period of time on the basis of exploration in confocal microscopy field, propose Structured Illumination microtechnic (see document M.Neil, R.Juskaitis, T.Wilson.Methodofobtainingopticalsectioningbyusingstruct uredlightinaconventionalmicroscope.OpticsLetters, 1997, 22 (24): 1905-1907), this is that one carries out very little change just attainable parallel optical chromatography microtechnic in ordinary optical microscope system-based, comprise the illumination of common white radiant, without (confocal) physical pin, non-point by point scanning etc., modulated by optical stripe, the steps such as demodulation realize optical tomography, and prove its axial optics chromatography and common simple scan confocal microscope similar.

Current Structured Illumination microtechnic generally drives one dimension physical grating to produce mechanical step-scan phase shift by micro-displacement work table, cosine intensity fringes is projected to testing sample space, utilizes the grating fringe of different initial phase to modulate sample surface morphology or inner structure; Utilize CCD to detect respectively to carry the modulation light field of object structures information, general gather 3 width images after, by mathematical operation process, from detection light field, common wide field picture and optical chromatography picture are isolated in demodulation.

To sum up, existing micrometering technology generally uses mechanical step-scan, not only reduces measurement efficiency, also affects measuring accuracy, and the problems referred to above limit the range of application of Structured Illumination microtechnic.The present invention utilizes the micro-microtechnic basic device of Structured Illumination to realize single sweep operation line laminar analysis measurement.

Summary of the invention:

The object of the invention is the mechanical step-scan process in order to overcome testing sample, finally realize noncontact, Non-scanning mode, the three-dimensional chromatography micro-imaging of wide field parallel optical and measurement, provide a kind of parallel optical line chromatography microscopic measuring method, single sweep operation just can realize the three-dimensional chromatography of sample surface morphology in certain axial range ability and detect.

For achieving the above object, the present invention adopts following technical scheme to realize:

A kind of parallel optical line chromatography microscopic measuring method, comprises the following steps:

1) selection standard plane mirror is canonical measure sample;

2) utilize one dimension Z-direction piezoelectric ceramics precision displacement table along axle step-scan plane mirror, at each axial location, perform step 3) and 4);

3) utilize precision stepper motor to move one dimension transmission grating along X-direction, gather I respectively ₁, I ₂and I ₃three width structured lights modulation image fields, the image field of three width structured lights modulation image fields respectively in corresponding parallel optical line chromatography micro-measurement apparatus behind structured light phase shift 0,2 π/3 and 4 π/3;

4) based on step 3) the three width image fields that obtain, by expression formula $I_{\sec t}=\frac{\sqrt{2}}{3}\sqrt{{(I_2-I_1)}^2+{(I_3-I_1)}^2+{(I_3-I_2)}^2}$ Calculate micro tomography image field I _sect;

5) often perform step 3) once, adopt step 4) described in expression formula I _sectcalculate micro tomography image field, and draw axial chromatography response intensity curve corresponding to central point in above-mentioned image field;

6) step 5 is intercepted) single-sided linear of described curve is interval, set up the theoretical correlation model of intensity field and sample surfaces height, obtain Measurement and calibration linearity curve, height of formation---intensity lookup tables;

7) standard of replacement plane mirror is actual testing sample, repeat step 2) and 3), according to step 6) gained height---intensity lookup tables, obtain institute's surface elevation value a little in image field, realize the detection that single sweep operation just can complete sample surface morphology solid chromatography structure in axial range ability.

Beneficial effect of the present invention is: a kind of parallel optical line chromatography microscopic measuring method provided by the invention, based on the wide field line chromatographic theory measurement model that diffraction optics and Fourier optics theory are set up, achieve and shaftlessly to detect fast to mechanical scanning, parallel, three-dimensional chromatography, overcome the mechanical step-scan problem of axis of testing sample, best axial resolution can reach several nanometer scale (corresponding large-numerical aperture micro objective situation).The present invention can be used for shaftlessly detecting fast to mechanical scanning, parallel, three-dimensional chromatography, in the noncontact of the micro-nano device 3 d surface topographies such as micromechanics, microelectronics, micro-optic, high resolving power, flash chromatography imaging and measurement, provide a brand-new effective measuring method.

The present invention and existing non-interfering difference confocal measuring technique are (see document Chau-HwangLee, JyhpyngWang.Noninterferometricdifferentialconfocalmicros copywith2-nmdepthresolution.OpticsCommunications, 1997,135:233-237) existence is obviously distinguished, the present invention adopts Structured Illumination fringe-adjusted demodulation techniques, it is a kind of parallel type chromatography method, and prior art adopts common cofocus scanning measurement mechanism, be a kind of spot scan formula chromatography method, thus must carry out horizontal two-dimentional machinery scanning.

Accompanying drawing illustrates:

Fig. 1 is Structured Illumination parallel optical line chromatography micro-measurement apparatus structural representation.

Wherein: 1-illumination of incoherent light light source, 2-narrow band pass filter, 3-stepper motor, 4-one dimension transmission grating, the 5-the first pipe mirror, 6-spectroscope, 7-microcobjective, 8-object under test, 9-PZT, the 10-the second pipe mirror, 11-CCD.

Fig. 2 is Structured Illumination micro imaging system axial chromatography response theory calculated curve.

Embodiment:

Below in conjunction with drawings and Examples, the present invention is further detailed.

As shown in Figure 1, parallel optical line chromatography micro-measurement apparatus, comprises illumination of incoherent light light source 1, narrow band pass filter 2, stepper motor 3, one dimension transmission grating 4, first pipe mirror 5, spectroscope 6, microcobjective 7, one dimension PZT9, the second pipe mirror 10 and CCD11; Wherein, the light sent by illumination of incoherent light light source 1 after narrow band pass filter 2, one dimension transmission grating 4, first pipe mirror 5, is reflected by spectroscope 6 successively, focuses on object under test 8 surface be placed on one dimension PZT9, form Structured Illumination through microcobjective 7; Illuminating bundle reflects by object under test 8, and successively after microcobjective 7, spectroscope 6, second pipe mirror 10, illuminating bundle focuses on the focal plane place of CCD11; Described stepper motor 3, for controlling one dimension transmission grating 4 transverse shifting, to complete three step phase shifts of one dimension transmission grating 4, is respectively 0,2 π/3 and 4 π/3, by CCD11 corresponding collection I ₁, I ₂and I ₃three width image fields; Described one dimension PZT9 moves at vertical direction for controlling object under test 8.

A kind of parallel optical line of the present invention chromatography microscopic measuring method, one dimension transmission grating 4 is utilized to modulate incident quasi-parallel light beam, form stripe grating structured illumination, then through noncoherence optics imaging filtering system by the imaging of grating fringe epitome to the focal plane place of microcobjective 7, produce cosine intensity distributions illumination striped through spatial filtering, sample surface morphology is modulated; The reflection sent by object under test 8 surface or scattered light carry out light intensity detection by infinity imaging system and the CCD11 that is positioned at the second pipe mirror 10 focal plane position, gather image field I ₁; By the lateral attitude of the straight stripe grating of stepper motor 3 portable lighting, 1/3 and 2/3 displacement of moving grating cycle d, utilizes CCD11 to gather image field I respectively respectively ₂and I ₃; Theoretical according to Structured Illumination microscopy tomography, have

$\left\{\begin{array}{c}{I}_{conv}=\frac{I_1+I_2+I_3}{3}\\ I_{\sec t}=\frac{\sqrt{2}}{3}\sqrt{{(I_2-I_1)}^2+{(I_3-I_1)}^2+{(I_3-I_2)}^2}\end{array}\right.---\left(1\right)$

According to formula (1), by image field I ₁, I ₂and I ₃mathematical operation separablely obtain ordinary optical image field I _convwith optical chromatography image field I _sect.

Utilize scalar diffraction theory, under obtaining incoherent illumination condition, axial chromatography response I (u) of Structured Illumination micro imaging system normalization is approximately

$I\left(u\right)=\left|\frac{2J_1\left(wu\right)}{wu}\right|---\left(2\right)$

In formula, J ₁() is first kind first-order bessel function; Parameter w is

w＝2υ _ω(1-υ _ω/2)(3)

In formula, υ _ω=λ M ω/sin α is normalization spatial frequency; ω=1/d is the real space frequency (d is screen periods) of one dimension illumination grating fringe; λ is lighting source centre wavelength; M is the epitome multiple of Structured Illumination system; NA=sin α is microcobjective numerical aperture; Normalization axial displacement optical coordinate u is

$u=\frac{8\mathrm{\π}}{\mathrm{\λ}}z{\sin }^2\left(\frac{\mathrm{\α}}{2}\right)---\left(4\right)$

In formula, z is axial displacement true coordinate.

Based on formula (1) to formula (4), the concrete measuring process of a kind of parallel optical line chromatography microscopic measuring method of the present invention is:

1) selection standard plane mirror is canonical measure sample;

2) utilize one dimension Z-direction piezoelectric ceramics precision displacement table along axle step-scan plane mirror, at each axial location, perform step 3) and 4);

3) utilize precision stepper motor to move one dimension transmission grating along X-direction, gather I respectively ₁, I ₂and I ₃three width structured lights modulation image fields, the image field of three width structured lights modulation image fields respectively in corresponding parallel optical line chromatography micro-measurement apparatus behind structured light phase shift 0,2 π/3 and 4 π/3, calculates micro tomography image field I by formula (1) _sect;

4) often step 3 is performed) once, adopt formula (1) to calculate micro tomography image field, and draw axial chromatography response intensity curve corresponding to central point in above-mentioned image field;

5) step 4 is intercepted) single-sided linear of described curve is interval, set up the theoretical correlation model of intensity field and sample surfaces height, obtain Measurement and calibration linearity curve, height of formation---intensity lookup tables;

6) standard of replacement plane mirror is actual testing sample, repeat step 2) and 3), according to step 5) gained height---intensity lookup tables, obtain institute's surface elevation value a little in image field, realize the detection that single sweep operation just can complete sample surface morphology solid chromatography structure in certain axial range ability.

Embodiment:

That the axial chromatography response curve of Structured Illumination micro imaging system is with normalization spatial frequency υ shown in Fig. 2 _ωchanging Pattern, work as υ _ωwhen=1, ω=(sin α/λ)/M, axial chromatography response curve is the narrowest, corresponding best axial resolution, i.e. I (u)=| 2J ₁u ()/u|, responds I with the confocal axial chromatography of ideal _conf(u)=sinc ²[u/ (2 π)] compares (in figure shown in dotted line), and its full width at half maximum (FWHM) is narrower.Between the linear zone intercepting above-mentioned curve (as shown in Fig. 2 dotted line frame), set up the theoretical correlation model of intensity field and sample surfaces height, the detection that single sweep operation just can complete the three-dimensional chromatography structure of sample surface morphology in certain axial range ability can be realized.

According to theoretical analysis of the present invention, design optical system parameter is as shown in table 1, adopt wavelength X=532nm, axial chromatography resolution utilizes the full width at half maximum (FWHM) of axial response curve to estimate, and lateral resolution utilizes Rayleigh criterion 0.61 λ/NA to estimate, due to not through grating rotating frequency modulation (PFM), therefore lateral resolution does not improve.

Table 1 Structured Illumination micro imaging system parameter

Below by reference to the accompanying drawings the specific embodiment of the present invention is described; but these explanations can not be understood to limit scope of the present invention; protection scope of the present invention is limited by the claims of enclosing, and any change on the claims in the present invention basis is all protection scope of the present invention.

Claims (1)

1. a parallel optical line chromatography microscopic measuring method, is characterized in that, comprise the following steps:

1) selection standard plane mirror is canonical measure sample;

2) utilize one dimension Z-direction piezoelectric ceramics precision displacement table along axle step-scan plane mirror, at each axial location, perform step 3) and 4);

3) utilize precision stepper motor to move one dimension transmission grating along X-direction, gather I respectively ₁, I ₂and I ₃three width structured lights modulation image fields, the image field of three width structured lights modulation image fields respectively in corresponding parallel optical line chromatography micro-measurement apparatus behind structured light phase shift 0,2 π/3 and 4 π/3;

4) based on step 3) the three width image fields that obtain, by expression formula $I_{\sec t}=\frac{\sqrt{2}}{3}\sqrt{{(I_2-I_1)}^2+{(I_3-I_1)}^2+{(I_3-I_2)}^2}$ Calculate micro tomography image field I _sect;

5) often perform step 3) once, adopt step 4) described in expression formula I _sectcalculate micro tomography image field, and draw axial chromatography response intensity curve corresponding to central point in above-mentioned image field;

6) step 5 is intercepted) single-sided linear of described curve is interval, set up the theoretical correlation model of intensity field and sample surfaces height, obtain Measurement and calibration linearity curve, height of formation---intensity lookup tables;

7) standard of replacement plane mirror is actual testing sample, repeat step 2) and 3), according to step 6) gained height---intensity lookup tables, obtain institute's surface elevation value a little in image field, realize the detection that single sweep operation just can complete sample surface morphology solid chromatography structure in axial range ability.