CN102818522A - Phase conjugate reflection bi-pass lighting confocal microscopic device - Google Patents

Abstract

The invention discloses a phase conjugate reflection bi-pass lighting confocal microscopic device, belonging to an optics measuring microtechnique. A collimation beam expander and a spectroscope are configured on a laser direct light path in sequence; a focusing objective lens and a three-dimensional micrometric displacement objective table are configured on a spectroscope reflecting light path; a collecting objective lens is configured on a spectroscope transmission light path; a collecting objective lens converging light is conducted to a photoelectric detector through conduction optical fibers; an ellipsoid reflecting lens is also configured on the spectroscope reflecting light path; a near focus of the ellipsoid reflecting lens is located on a surface of a sample put on the three-dimensional micrometric displacement objective table; and a phase conjugate reflecting lens is configured at a remote focus of the ellipsoid reflecting lens. According to the device, bi-pass lighting to a large curvature convex surface is carried out by adopting a characteristic that a reflection ray as a phase conjugate light wave of an incidence light of the phase conjugate reflecting lens can go back along an original way in combination with a characteristic that the ellipsoid reflecting lens is provided with a pair of isoplanatic image formation conjugate focuses, so that the device has a measurement ability of the large curvature convex surface and a characteristic of a high axial resolution force.

Description

Phase conjugation reflection bilateral illumination confocal microscopy device

Technical field

The invention belongs to the optical microphotograph measuring technique, relate generally to a kind of ultraprecise non-cpntact measurement device that is used for Microstructure Optics element, microstructure mechanical organ, integrated circuit component three-dimensional microstructure, little step, little groove live width, the degree of depth and surface shape measuring.

Background technology

Confocal spot scan measurement is to measure one of important technical of three-dimensional microstructure, little step, little groove live width, the degree of depth and surface configuration in micro-optic, micromechanics, the microelectronic; Its basic thought is to suppress parasitic light through introducing pinhole detector; And produced axial chromatography ability, but receiving conventional lenses imaging numerical aperture always, limits to traditional confocal technology less than 1 principle.

Bilateral illumination confocal measurement proposed (Sheppard by C.J.R.Sheppard and T.Wilson in 1980; C.J.R.and Wilson; T. (1980) ' Multiple Traversing of the Object in the Scanning Microscope ', Journal of Modem Optics, 27:5; 611-624); Its basic thought is to utilize sphere or plane mirror that the transillumination light of transmission sample is reflected back, and sample is carried out the secondary illumination, makes bilateral illumination responses function have higher resolution.Analysis shows that with respect to traditional confocal measurement bilateral illumination confocal measurement azimuthal resolution can improve 2～4 times, and spot side-lobe is also better suppressed.

The general character deficiency of the confocal measurement method that existing bilateral illumination confocal measurement method and Minsky propose is; When the bigger surface of curvature is measured; Because changing, surperficial method direction cause reflection measurement light to exceed the collecting aperture of collecting object lens; Therefore, system can't realize the measurement on deep camber surface.Meanwhile; Systemic resolution is also closely related with collection numerical aperture of objective size, and numerical aperture is big more, and azimuthal resolution is high more; And owing to receiving the principle limitation of conventional lenses imaging numerical aperture less than 1, the two all is difficult to come the further axial resolution that improves through improving numerical aperture.

Summary of the invention

The object of the invention is exactly the deficiency that receives the numerical aperture of objective restriction to above-mentioned existing confocal measurement and bilateral illumination confocal measurement axial resolution; And further improve system to deep camber nonreentrant surface measurement capability; Research and design a kind of phase conjugation reflection bilateral illumination confocal microscopy device; The characteristics of utilizing phase conjugation mirror reflects light to return as the former road, phase conjugation light wave edge of incident ray; The characteristics that cooperate ellipsoidal reflector to have a pair of isoplanatic image formation conjugate focus are carried out the bilateral illumination to the deep camber nonreentrant surface, reach the measurement that realizes deep camber nonreentrant surface sample, ellipsoidal reflector can be realized deep camber nonreentrant surface reflection ray numerical aperture is 1 collection, makes system have the purpose of deep camber nonreentrant surface measurement capability and high azimuthal resolution characteristic simultaneously.

The objective of the invention is to realize like this:

Phase conjugation reflection bilateral illumination confocal microscopy device comprises: laser instrument, collimator and extender device, spectroscope, focusing objective len, three-dimensional micrometric displacement objective table, collection object lens, conduction optical fiber, photodetector; Wherein on laser instrument direct projection light path, dispose collimator and extender device and spectroscope successively; Focusing objective len and three-dimensional micrometric displacement objective table are configured on the spectroscope reflected light path; Collecting object lens is configured on the spectroscope transmitted light path; Conduction optical fiber will be collected the object lens converging light and be transmitted to photodetector; On the spectroscope reflected light path, also dispose ellipsoidal reflector, the perifocus of described ellipsoidal reflector is positioned at and is placed on the three-dimensional micrometric displacement objective table on the sample surfaces configuration phase conjugation catoptron at ellipsoidal reflector over focus place.

The phase conjugation catoptron that said device has ellipsoidal reflector and places its over focus place, its effect are will to be returned along former road through the light that ellipsoidal reflector is assembled by the phase conjugation catoptron, and deep camber nonreentrant surface sample is carried out the secondary illumination.Its unique optical properties changes the ray trajectory of traditional ellipsoid bilateral illumination, makes device be applicable to the measurement of deep camber nonreentrant surface.Bilateral illumination responses function has higher azimuthal resolution with respect to traditional confocal system response function simultaneously, and realizes that numerical aperture is 1 secondary illumination.

Said device has ellipsoidal reflector; Its effect is to utilize it to have a pair of isoplanatic image formation conjugate focus; Sample places its perifocus; Can realize to sample diffuse light numerical aperture being 1 collection, and the light that is reflected by over focus assembled sample is carried out numerical aperture is 1 secondary illumination, improve the system axial resolving power through increasing numerical aperture of objective.For deep camber nonreentrant surface sample, illuminating bundle is under the situation of sample surfaces generation wide-angle deflection, and is different with the conventional lenses micro-measurement apparatus especially, and it is 1 collection that ellipsoidal reflector can carry out numerical aperture to reflection ray, and converges at the over focus place.

Said device has the phase conjugation catoptron, and its effect is that incident ray is returned by former road with its phase conjugation light wave, realizes the secondary illumination of sample, makes device have deep camber nonreentrant surface measurement capability.

Good result of the present invention is:

1) adopts phase conjugation catoptron and ellipsoidal reflector to realize the bilateral illumination, make device have the detectivity of deep camber nonreentrant surface.

2) phase conjugation reflection bilateral illumination confocal microscopy device can realize that numerical aperture is 1 secondary illumination and detection, helps improving measurement resolution.

3) set up the high-order response function that is different from tradition confocal and bilateral illumination confocal system, helped improving the spot scan resolving power.

Description of drawings

Fig. 1 is a phase conjugation reflection bilateral illumination confocal microscopy apparatus structure synoptic diagram.

Fig. 2 is that phase conjugation reflection bilateral illumination confocal microscopy device ellipsoidal reflector point spread function is analyzed coordinate definition figure.

Fig. 3 is a phase conjugation reflection bilateral illumination confocal microscopy device phase conjugation mirror reflects schematic diagram.

Fig. 4 is that phase conjugation reflection bilateral illumination confocal microscopy assembly axis is to response curve.

Fig. 5 is a phase conjugation reflection bilateral illumination confocal microscopy device lateral response curve.

Piece number explanation among the figure: 1, laser instrument, 2, collimator and extender device, 3, spectroscope, 4, focusing objective len, 5, three-dimensional micrometric displacement objective table, 6, ellipsoidal reflector, 7, phase conjugation catoptron, 8, collection object lens, 9, conduction optical fiber, 10, photodetector.

Embodiment

Below in conjunction with accompanying drawing the embodiment of the invention is described in detail.

Phase conjugation reflection bilateral illumination confocal microscopy device comprises: laser instrument 1, collimator and extender device 2, spectroscope 3, focusing objective len 4, three-dimensional micrometric displacement objective table 5, collection object lens 8, conduction optical fiber 9, photodetector 10; Wherein on laser instrument 1 direct projection light path, dispose collimator and extender device 2 and spectroscope 3 successively; Focusing objective len 4 is configured on spectroscope 3 reflected light paths with three-dimensional micrometric displacement objective table 5; Collecting object lens 8 is configured on spectroscope 3 transmitted light paths; Conduction optical fiber 9 will be collected object lens 8 converging lights and be transmitted to photodetector 10; On spectroscope 3 reflected light paths, also dispose ellipsoidal reflector 6, the perifocus of described ellipsoidal reflector 6 is positioned at and is placed on the three-dimensional micrometric displacement objective table 5 on the sample surfaces, at ellipsoidal reflector 6 over focus place configuration phase conjugation catoptrons 7.

Measure when using:

The first, laser instrument 1 sends linearly polarized light beam, through becoming the approximate ideal plane wave behind the collimator and extender device 2; Collect by focusing objective len 4 through spectroscope 3 mirror based fiber opticas.

The second, measuring light is in deep camber nonreentrant surface sample surfaces generation wide-angle deflection; Pass through ellipsoidal reflector 6 again, converge at phase conjugation catoptron 7.

Wherein said ellipsoidal reflector 6 is different from the conventional lenses model, then need carry out theoretical derivation from the optical diffraction theory, and is as shown in Figure 2, and for ellipsoidal reflector 6, its geometric expression formula is z ²/ a ²+ y ²/ b ²+ x ²/ b ²Response function did in=1 o'clock

Wherein,

O denotation coordination initial point;

P ₁The ellipsoid over focus at expression phase conjugation catoptron 7 places, coordinate is (x ₁, y ₁, z ₁);

P ₂The ellipsoid perifocus at expression sample place, coordinate is (x ₂, y ₂, z ₂);

M representes P ₁To P ₂The reflection spot of ray trajectory on ellipsoidal reflector;

N representes the ellipsoid unit normal vector at M point place;

r _P1MExpression P ₁The distance that point is ordered to M;

r _MP2Expression M point is to P ₂The distance of point;

U _P2Expression P ₂The light wave function at some place;

U _MThe light wave function at expression M point place;

S ₀The ellipsoid at expression ellipsoidal reflector 6 places;

S representes ellipsoidal reflector 6;

Consider generalized case, h _P1-p2The expression p1 to p2 order point spread function, abbreviation obtains

$h_{p1-p2}(\mathrm{0,0,0},x_2,{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="HSA00000751913500011.png"\; state="\{\{state\}\}">y</figure-callout>}}_2=0,z_2)=\underset{-{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSA00000751913500011.png"\; state="\{\{state\}\}">b</figure-callout>}}^2/a}{\overset{{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HSA00000751913500011.png"\; state="\{\{state\}\}">b</figure-callout>}}^2/a}{\&Integral;}}\underset{c}{\overset{c+z_{\mathrm{sol}}}{\&Integral;}}\frac{\exp [-\mathrm{jk}(r_{P1M}+r_{\mathrm{MP}2})]}{r_{P1\mathrm{<figure-callout\; id="2"\; label="M\; r\; MP"\; filenames="HSA00000751913500011.png"\; state="\{\{state\}\}">M</figure-callout>}}{r}_{\mathrm{MP}}{2}_{}}\cos \left(\frac{\&angle;P_1\mathrm{<figure-callout\; id="2"\; label="M\; P"\; filenames="HSA00000751913500011.png"\; state="\{\{state\}\}">M</figure-callout>}{P}_{}{}_2}{2}\right)\mathrm{dxdz}---\left(2\right)$

Limit of integration is the space curved surface that all light reflection spot M constitute in the formula.

Three, light beam reflects and will return along former road through phase conjugation catoptron 7, realizes the secondary illumination to sample.The principle of work of wherein said phase conjugation catoptron 7 is different with the common plane mirror, and is as shown in Figure 3

Frequency is ω _sMonochromatic optical wave incide phase conjugation catoptron 7 along the z direction of principal axis, its electric field expression does

$E_s(r,t)=E_s\left(r\right)e^{-j({\mathrm{\&omega;}}_{s}t-k_{s}z)}---\left(3\right)$

Then it will reflect away with its reverse phase conjugate wave in time reversal each other aspect three of amplitude, phase place and the polarization states, and its electric field expression formula does

${\&CenterDot;E}_p(r,t)=E_s^{*}\left(r\right)e^{-j({\mathrm{\&omega;}}_{s}t-k_{s}z)}---\left(4\right)$

It is different from plane mirror, will return by former road, and is as shown in Figure 3, sample is carried out the secondary illumination, thereby this device is applicable to the measurement of deep camber nonreentrant surface; Bilateral illumination responses function has higher axial resolution with respect to traditional confocal system response function simultaneously, and realizes that numerical aperture is 1 secondary illumination.

Four, pass through focusing objective len 4 again by spectroscope 3 transmissions, assemble through collecting object lens 8,9 transmission are received by photodetector 10 through conduction optical fiber.

Five, response signal corresponding diagram 3, the Fig. 4 that is received by photodetector 10 obtains sample surfaces face shape result, and to get focusing objective len 4 numerical apertures respectively be 0.1 and 0.65 to curve among the figure.

Claims (1)

1. a phase conjugation reflection bilateral illumination confocal microscopy device comprises: laser instrument (1), collimator and extender device (2), spectroscope (3), focusing objective len (4), three-dimensional micrometric displacement objective table (5), collection object lens (8), conduction optical fiber (9), photodetector (10); Wherein on laser instrument (1) direct projection light path, dispose collimator and extender device (2) and spectroscope (3) successively; Focusing objective len (4) and three-dimensional micrometric displacement objective table (5) are configured on spectroscope (3) reflected light path; Collecting object lens (8) is configured on spectroscope (3) transmitted light path; Conduction optical fiber (9) will be collected object lens (8) converging light and be transmitted to photodetector (10); It is characterized in that on spectroscope (3) reflected light path, also disposing ellipsoidal reflector (6), the perifocus of described ellipsoidal reflector (6) is positioned at and is placed on the last sample surfaces of three-dimensional micrometric displacement objective table (5), at ellipsoidal reflector (6) over focus place configuration phase conjugation catoptron (7).

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