CN102175143B - Line scanning differential confocal measuring device based on light path of pillar lens - Google Patents

Abstract

The invention relates to a line scanning differential confocal measuring device based on a cylindrical lens optical path, which belongs to the technical field of microscopic measurement. It solves the problem of low measurement efficiency when differential confocal detection technology performs three-dimensional measurement. The laser beam generated by the laser converges in the pinhole through the focusing lens, after being filtered, the beam is expanded by the collimating beam expander lens and then enters the first beam splitter through a rectangular diaphragm, and the transmitted beam of the first beam splitter enters the detection focusing cylindrical lens, Line gathering is formed on the image square focal plane of the detection focusing cylindrical lens; after the light beam reflected by the measured sample passes through the detection focusing cylindrical lens, the light beam passing through the first beam splitter enters the second beam splitter, and the light beam of the second beam splitter The transmitted light beam is linearly focused to the photosensitive surface of the first linear point detector after passing through the first collecting cylindrical lens; the reflected light beam of the second beam splitter is linearly focused to the photosensitive surface of the second linear point detector after passing through the second collecting cylindrical lens superior. The invention is suitable for differential confocal detection.

Description

Line-scanning differential confocal measurement device based on cylindrical lens optical path

technical field

The invention relates to a line-scanning differential confocal measuring device based on a cylindrical lens optical path, and belongs to the technical field of microscopic measurement.

Background technique

The basic idea of confocal microscopy imaging technology is to suppress stray light by introducing a pinhole detector and generate axial tomography capability. This technology obtains the current X-Y surface image by performing two-dimensional scanning measurement on the X-Y surface of the sample point by point. Then scan the sample in the Z direction (axial direction), and point-by-point two-dimensional scanning on the next X-Y plane, and so on, by "stacking" the obtained two-dimensional images to obtain the three-dimensional reconstructed image of the sample. Because this measurement method is very time-consuming, in order to improve the measurement efficiency of confocal detection technology, a method of using slit detection instead of point detection for confocal measurement was proposed on this basis. The method of confocal measurement with slit detection greatly improves the scanning detection speed of the X-Y surface of the sample, but because the front-end optical path of this method adopts a circularly symmetrical optical path, the light intensity distribution at the receiving end of the slit detector is not uniform, and the center The light intensity is significantly higher than at the edge of the slit, leading to eventual measurement errors.

In June 2002, Wu Kaijie, Li Gang et al. proposed the use of column The lens replaces the confocal detection technology of the circular lens. This method makes the light intensity distribution at the receiving end of the detector more uniform, and significantly increases the lateral range and improves the measurement efficiency of the confocal detection technology. However, the vertex tomography method adopted in this method makes the axial resolution of the system low and the three-dimensional measurement efficiency is low.

Differential confocal detection technology introduces differential detection into confocal microscopic detection technology. It uses two differential detection signals to improve the traditional confocal optical path. Compared with traditional confocal detection technology, differential confocal detection technology has unique zero point tracking characteristics, high axial resolution and linear range of axial response twice that of traditional confocal. When the zero-point tomography measurement method is used, the differential confocal detection technology provides much higher axial resolution than the traditional confocal apex tomography measurement method; when the axial response linear interval measurement method is used, the differential confocal detection technology It provides twice the axial range of the traditional confocal and much higher axial resolution than the traditional confocal. In addition, when the axial size of the sample is smaller than the linear range of the axial response, the three-dimensional image of the sample can be obtained by one transverse scan superficial information. Therefore, the axial dimension of the sample that can be measured by the differential confocal axial response linear interval measurement method can reach twice that of the traditional confocal linear interval measurement method, and the axial resolution has also been significantly improved. Compared with the zero-point tomography method, it has High measurement efficiency. However, when using differential confocal detection technology for three-dimensional measurement, it is still necessary to scan the X-Y plane of the sample point by point, and the measurement efficiency is still low.

Contents of the invention

The object of the present invention is to provide a line-scanning differential confocal measurement device based on a cylindrical lens optical path in order to solve the problem of low measurement efficiency when differential confocal detection technology performs three-dimensional measurement.

The present invention comprises laser device, focusing lens, pinhole and collimating beam expander lens arranged in sequence on the coaxial optical path, and it also comprises rectangular diaphragm, the first beam splitter, the second beam splitter, detection focusing cylinder lens, the first collecting a cylindrical lens, a second collecting cylindrical lens, a first linear point detector and a second linear point detector,

The laser beam generated by the laser converges on the pinhole through the focusing lens, and the point light source filtered by the pinhole is expanded by the collimator beam expander lens, and then enters the first beam splitter through the rectangular diaphragm.

The transmitted light beam transmitted by the first beam splitter enters the detection focus cylindrical lens, and forms a line focus on the image square focal plane of the detection focus cylindrical lens, which is used to focus on the object set on the image square focal plane of the detection focus cylindrical lens. Test samples for line lighting;

The light beam reflected by the measured sample is transmitted through the detection focusing cylindrical lens, and then the light beam reflected by the first beam splitter enters the second beam splitter,

The transmitted light beam of the second beam splitter is linearly focused to the photosensitive surface of the first line array point detector after passing through the first collecting column lens, and the first line array point detector is arranged at the front focus position of the first collecting column lens;

The reflected light beam of the second beam splitter is linearly focused onto the photosensitive surface of the second linear point detector after passing through the second collecting cylindrical lens, and the second linear point detector is arranged at the post-focus position of the second collecting cylindrical lens;

The defocusing amounts of the first line array point detector and the second line array point detector are equal.

The advantages of the present invention are:

One: The present invention uses a cylindrical lens to expand the differential confocal measurement optical path in one dimension to realize line scanning, and at the same time uses the linear interval measurement method of the differential confocal axial response characteristic curve to have a large axial range and high axial resolution Features, the cylindrical lens differential confocal detection technology after introducing the cylindrical lens into the differential confocal system not only has the advantages of large axial range and high axial resolution, but also can scan in the Y direction (or X direction) once Realize the measurement of the tested sample and form the rapid measurement capability of large-scale microstructure components;

Two: The present invention uses a collimating beam expander lens to expand the diameter of the laser beam, and realizes the expansion of the illumination range of the surface of the sample to be tested; the outgoing light of the collimating beam expander lens uses a rectangular diaphragm to block the edge of the beam before being split. part, so that the intensity distribution of the light beam that illuminates the sample to be tested is more uniform after passing through the detection focusing cylindrical lens, which is more conducive to the confocal detection axial measurement based on the optical line scanning of the cylindrical lens, and reduces the problem caused by the uneven distribution of the measured light intensity. measurement error;

Three: The line-array point detector is used to make the line-scanning differential confocal detection technology based on the optical path of the cylindrical lens have three-dimensional resolution; the line-array point detector can realize the detection of the corresponding point of the line focused beam on the detection surface, so that the cylindrical lens has no The resolution ability of the optical power direction, the three-dimensional surface information of the measured sample can be obtained by reconstructing the detected point signals, and the three-dimensional measurement of the cylindrical lens differential confocal measurement system is realized; in addition, compared with the linear array CCD detector, the use of linear array point detectors can realize the detection of weak signals, thereby improving the measurement accuracy.

The invention can obtain its three-dimensional shape by performing one-dimensional scanning motion on the measured sample, which greatly improves the measurement efficiency; it can be used for the detection of three-dimensional microstructures in large-scale microstructured optical components, microstructured mechanical components, and integrated circuit components. And achieve the purpose of high precision, non-contact and three-dimensional rapid detection.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the present invention; among the figure - u _M represents the amount of defocus.

Fig. 2 is the structural representation of described linear array point detector;

Fig. 3 is the left view of the tested sample in Fig. 1, and arrow y represents the movement direction of the tested sample;

Fig. 4 is the equivalent optical path figure of device of the present invention;

Fig. 5 is a schematic diagram of the diffraction spot of the ideal plane wave incident on the detection focusing cylindrical lens through the rectangular aperture;

Fig. 6 is a comparative graph of lateral response characteristics between the cylindrical lens confocal of the present invention and the traditional circular lens confocal;

Fig. 7 is a graph comparing the axial response characteristics of the cylindrical lens confocal of the present invention and the traditional circular lens confocal;

Fig. 8 is an axial differential response characteristic curve diagram of the device of the present invention.

Detailed ways

Specific Embodiment 1: The present embodiment will be described below in conjunction with FIG. 1 to FIG. 3 ,

This embodiment includes a laser 1, a focusing lens 2, a pinhole 3, and a collimating beam expander lens 4 arranged in sequence on the coaxial optical path, and it also includes a rectangular diaphragm 5, a first beam splitter 6-1, and a second beam splitter 6-2. Detection focusing cylindrical lens 7, first collecting cylindrical lens 8-1, second collecting cylindrical lens 8-2, first linear array point detector 9-1 and second linear array point detector 9-2,

The laser beam generated by the laser 1 converges on the pinhole 3 through the focusing lens 2, and the point light source filtered by the pinhole 3 is expanded by the collimating beam expander lens 4, and then enters the first beam splitter 6- 1,

The transmitted light beam transmitted by the first beam splitter 6-1 is incident on the detection focusing cylindrical lens 7, and forms a line focus on the image square focal plane of the detection focusing cylindrical lens 7, which is used to image the image set on the detection focusing cylindrical lens 7. Line illumination is performed on the tested sample 10 on the square focal plane;

The light beam reflected by the sample 10 to be tested is transmitted through the detection focusing cylindrical lens 7, and then the light beam reflected by the first beam splitter 6-1 enters the second beam splitter 6-2,

The transmitted light beam of the second beam splitter 6-2 is linearly focused to the photosensitive surface of the first linear point detector 9-1 after passing through the first collecting cylindrical lens 8-1, and the first linear point detector 9-1 is arranged on The front-focus position of the first collecting cylinder lens 8-1;

The reflected beam of the second beam splitter 6-2 is linearly focused to the photosensitive surface of the second line array point detector 9-2 after passing through the second collecting cylinder lens 8-2, and the second line array point detector 9-2 is arranged on the second line array point detector 9-2. Collect the post-focus position of the cylindrical lens 8-2;

The defocusing amounts of the first linear point detector 9-1 and the second linear point detector 9-2 are equal.

In this embodiment, the rectangular diaphragm 5, the detecting focusing cylindrical lens 7, the first collecting cylindrical lens 8-1, the first linear point detector 9-1, the second collecting cylindrical lens 8-2 and the second linear point detecting Device 9-2 constitutes the optical path of cylindrical lens line scanning differential confocal measurement, which realizes the one-dimensional expansion of differential confocal microscopic measurement technology, and at the same time maintains the advantages of large axial range and high axial resolution of differential confocal measurement technology. Advantages; wherein the detection focusing cylindrical lens 7 is located on the transmitted light path of the first beam splitter 6-1, and before the measured sample 10; the first collecting cylindrical lens 8-1 and the first linear array point detector 9-1 are located in sequence On the transmitted light path of the second beam splitter 6-2, the second collecting cylindrical lens 8-2 and the second linear point detector 9-2 are sequentially located on the reflected light path of the second beam splitter 6-2.

In this embodiment, the traditional differential confocal measurement system is expanded one-dimensionally by using the wide beam shaped by the rectangular aperture 5 and three cylindrical lenses, and a line scan is formed on the measured surface of the measured sample 10, thereby simultaneously obtaining Large axial range, high axial resolution and large lateral range; use linear array point detectors to receive the light intensity of the detection surface, so that the cylindrical lens has no resolution ability in the direction of the optical power, and realize the measurement of the measured surface of the sample 10 3D imaging. Using the linear area measurement method of the cylindrical lens differential confocal axial response curve, the sample 10 to be tested is scanned in the Y direction or the X direction to obtain the three-dimensional information of the surface of the corresponding area of the sample 10 under test, with continuous point parallel Scanning ability, combined with the high precision and large range characteristics of differential confocal measurement technology, can realize fast scanning measurement of the measured sample.

Specific embodiment two: the present embodiment is described below in conjunction with Fig. 1,

This embodiment is a further description of Embodiment 1, and the pinhole 3 is arranged at the focal point of the image side of the focusing lens 2 . Others are the same as the first embodiment.

Specific implementation mode three: the present implementation mode will be described below in conjunction with FIG. 1 ,

This embodiment is a further description of Embodiment 1 or 2. The focus on the image side of the focusing lens 2 coincides with the focus on the object side of the collimator and beam expander lens 4 . Others are the same as the first or second embodiment.

Specific embodiment four: the present embodiment is described below in conjunction with Fig. 1,

This embodiment is a further description of Embodiment 1. The diagonal length of the rectangular aperture 5 is smaller than the spot diameter of the beam expanded by the collimator beam expander lens 4, and larger than the beam expanded by the collimator beam expander lens 4. The spot radius of the beam after. Others are the same as the first embodiment.

Specific embodiment five: the present embodiment is described below in conjunction with Fig. 1,

This embodiment is a further description of Embodiment 1, and the detection focusing cylindrical lens 7 is a plano-convex cylindrical lens. Others are the same as the first embodiment.

Specific embodiment six: the present embodiment is described below in conjunction with Fig. 1,

This embodiment is a further description of Embodiment 1. The first collecting cylindrical lens 8-1 and the second collecting cylindrical lens 8-2 are plano-convex cylindrical lenses with the same technical parameters. Others are the same as the first embodiment.

Embodiment 7: This embodiment is a further description of Embodiment 1. The technical parameters of the first linear point detector 9-1 and the second linear point detector 9-2 are the same. Others are the same as the first embodiment.

Embodiment 8: The present embodiment will be described below in conjunction with FIG. 2 to FIG. 8 ,

This embodiment is a further description of Embodiment 1 or 7. Both the first linear array point detector 9-1 and the second linear array point detector 9-2 are linear array light intensity detectors composed of a group of single-mode optical fibers. The point detection terminal and the corresponding photoelectric receiver are composed. Others are the same as the first or seventh embodiment.

The composition of the first linear point detector 9-1 and the second linear point detector 9-2 is as follows: one end of a group of single-mode optical fibers is closely arranged in a straight line, and the other end of each single-mode optical fiber is connected to the corresponding connected to the photoelectric receiver.

The working process of the device of the present invention is as follows:

The laser beam generated by the laser 1 is converged on the image focus of the focus lens 2 through the focus lens 2, and the pinhole 3 located at the image focus of the focus lens 2 shapes the beam to form an approximate ideal point light source.

The object space focus of the collimating beam expander lens 4 coincides with the image space focus of the focusing lens 2, and the point light source filtered by the pinhole 3 passes through the collimating beam expander lens 4 to form an approximate ideal plane wave, and the beam is blocked by the rectangular diaphragm 5 A rectangular plane wave with a more uniform light intensity distribution is obtained after the edge part of the wave.

The nearly ideal plane wave with a more uniform light intensity distribution obtained through the rectangular diaphragm 5 passes through the first beam splitter 6-1, passes through the detection focusing cylindrical lens 7, and the measured sample on the image square focal plane of the detection focusing cylindrical lens 7 Line focus is formed at 10 places.

Reflected by the measured sample 10, then reflected by the detection focusing cylindrical lens 7, the first beam splitter 6-1, and transmitted by the second beam splitter 6-2, a line focus is formed by the first collecting cylindrical lens 8-1; After being reflected by the sample 10, after being reflected by the detecting focusing cylindrical lens 7, the first beam splitter 6-1, and the second beam splitting mirror 6-2, a line focus is formed by the second collecting cylindrical lens 8-2.

Finally, differential processing is performed on the plasma defocus signal detected by the first linear point detector 9-1 and the second linear point detector 9-2, and the height of the measured sample is calculated by using the linear interval of the differential curve; Because each point detection end of the first linear point detector 9-1 and the second linear point detector 9-2 has definite spatial position information, the transverse coordinates of the tested sample 10 can be obtained, thereby obtaining the measured sample's three-dimensional structure.

Device of the present invention can be divided into following five parts:

The first part: the diameter of the incident beam is expanded by using the collimating beam expander lens 4, which can be expanded to 2-3cm, which directly expands the lateral range of the detection device. The outgoing light of the collimating beam expander lens 4 uses rectangular light before splitting The diaphragm 5 blocks the edge of the light beam to make the intensity distribution of the illumination beam more uniform, which is beneficial to the axial measurement of the confocal detection and reduces the measurement error caused by the uneven distribution of the measured light intensity;

The second part: Line illumination is performed on the sample 10 under test through the line focus spot formed by the detection focusing cylindrical lens 7, so that the confocal measurement technology changes from point illumination to line illumination, and the area information of the line focus spot area on the surface of the test sample 10 can be obtained at the same time ;

The third part: the first collecting cylinder lens 8-1, the first linear array point detector 9-1 arranged in sequence on the transmission light path of the second beam splitter 6-2, and the reflection light path of the second beam splitter 6-2 in sequence The configuration of the second collecting cylindrical lens 8-2 and the second linear array point detector 9-2 realizes the linear expansion of the differential confocal measurement optical path by using the cylindrical lens, so that the measuring device has a large axial range and a high axis The characteristics of directional resolution, and can simultaneously obtain the surface information of the 10-line focused spot area of the tested sample;

The fourth part: use the first linear array point detector 9-1 and the second linear array point detector 9-2 as the detection part of the device of the present invention.

Part V: The differential confocal axial response linear interval measurement method is adopted to make the measured sample 10 perform one-dimensional uniform scanning motion, and the three-dimensional surface information can be obtained through this measuring device, which greatly improves the confocal microscopic detection technology. Measurement efficiency, realizing fast measurement.

The theoretical analysis results of the device of the present invention based on Fresnel diffraction are given below, and compared with the lateral response characteristics and axial response characteristics of the traditional circular lens differential confocal, the feasibility and superiority of the present invention are illustrated.

为：The analysis process is based on Figure 3, in which S is a point light source, lens L _2i is a collimating beam expander lens 4, t ₀ is the transmittance function of the imaging sample, and P ₁ is the pupil of L _1i and L _1c function, L _1i and L _1c are the same detection focusing cylindrical lens in the actual optical path, P ₂ is the pupil function of L _2c , L _2c is the detection focusing cylindrical lens, f ₁ is the focal length of L _1i and L _1c , f ₂ is L The focal length of _2c , D2 is a linear array point detector. Complex amplitude distribution on the detection surface when the detector is at the back defocus position Δz ₂

for:

$u_{{\mathrm{\Δz}}_2}(x_i,{\mathrm{the\; y}}_i)=C\·{\∫\∫h}_1(\mathrm{\ξ},\mathrm{\η})t_0(\mathrm{\ξ}-x_{\mathrm{the\; s}},\mathrm{\η}-{\mathrm{the\; y}}_{\mathrm{the\; s}})\&Center\; Dot;{\∫\∫P}_2(x_2,{\mathrm{the\; y}}_2)\·,$ (Formula 1)

$\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; jk</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="HDA0000047375490000011.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; jk</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="HDA0000047375490000011.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="0"\; label="d"\; filenames="HDA0000047375490000022.png,HDA0000047375490000041.png"\; state="\{\{state\}\}">d</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="y"\; filenames="HDA0000047375490000011.png"\; state="\{\{state\}\}">y</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \&Center\; Dot;</span>$

$\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; \{</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; jk</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f"\; filenames="HDA0000047375490000011.png"\; state="\{\{state\}\}">f</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \}</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="d\; x"\; filenames="HDA0000047375490000011.png"\; state="\{\{state\}\}">d</figure-callout></span><figure-callout\; id="2"\; label="d\; x"\; filenames="HDA0000047375490000011.png"\; state="\{\{state\}\}">\; </figure-callout>}{\mathrm{<span\; class="notranslate">\; </span>}}_{}{\mathrm{<span\; class="notranslate">x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="dy"\; filenames="HDA0000047375490000011.png"\; state="\{\{state\}\}">dy</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; d\&xi;d\&eta;</span>}$

Where C is a constant; Δz ₁ is the focal plane distance of the measured surface offset, (x _s , y _s ) is the offset of the measured sample on the measured surface; k is the wave number, k=2π/λ; d ₀ is the column The distance between lens L _1c and L _2c ; (ξ, η) is the measured surface coordinates, (x ₂ , y ₂ ) is the surface coordinates of cylindrical lens L _1c ; h ₁ (ξ, η) is the collection cylindrical lens L _1i pupil function.

$h_1(\mathrm{\&xi;},\mathrm{\&eta;})=\&Integral;\&Integral;P_1(x_1,{\mathrm{the\; y}}_1)\exp (-\frac{\mathrm{jk}{\mathrm{\&Delta;z}}_1}{{{2f}_1}^2}{x_1}^2)\exp \left(\frac{\mathrm{jk}}{2f_1}{{\mathrm{the\; y}}_1}^2\right)\exp [-\frac{\mathrm{jk}}{f_1}(x_1\mathrm{\&xi;}+{\mathrm{the\; y}}_1\mathrm{\&eta;}){\mathrm{dx}}_1{\mathrm{dy}}_1,$ formula two

u为系统的轴向无量纲位移，definition

u is the axial dimensionless displacement of the system,

v为系统的横向无量纲位移，

v is the lateral dimensionless displacement of the system,

u _d is the axial dimensionless defocus amount of the linear array point detector D2,

In the above formula, D ₁ and L ₁ are the width and length of cylindrical lenses L _1i and L _1c respectively, and D ₂ is the width of cylindrical lens L _2c .

Then the detected normalized light intensity is:

I(u+u _d , v)＝|h ₁ (u, v)| ² |h ₂ (u+u _d , v)| ² , Formula 3

where h ₁ (u, v) and h ₂ (u+ud, v) are defined according to formula 4,

$h(u,v)=\mathrm{D.}{\&Integral;}_{-\frac{1}{2}}^{\frac{1}{2}}\exp \left({-\mathrm{jux}}^2\right)\exp (-\mathrm{jvx})\mathrm{dx},$ formula four

where D is the width of the cylindrical lens.

It should be noted that the y-direction of an ideal cylindrical lens has no optical power, so the horizontally normalized coordinates of the cylindrical lens correspond to the actual coordinates in the x-direction with optical power. Formula 3 shows that the improved confocal method used in the device is consistent with The axial response characteristic function of traditional confocal I(u, v)=|h(u, v)| ² |h(u+u _d , v)| ² has the same form, the difference is that the pupil function leads to difference in the end result.

The axial response characteristics after introducing the differential detection technology are:

I=I(u+u _d , v)-I(uu _d , v), Formula 5

Equation 5 is the axial response characteristic function of the device.

Among them, I(uu _d , v) is defined according to formula three. When the axial dimensionless defocus amount u _d =25, the response characteristic curves are shown in Fig. 5 to Fig. 7 .

It can be seen from Figure 5 and Figure 6 of the description that the confocal cylindrical lens and the confocal circular lens have similar properties, and the difference in pupil function makes the axial and lateral resolution of the confocal cylindrical lens smaller than that of the confocal circular lens , while the axial and lateral ranges are larger than the confocal of the circular lens. The above results show that the detail resolution ability of the cylindrical lens confocal is weaker than that of the circular lens confocal, and the sample microstructure size that can be measured is larger than that of the circular lens confocal.

It can be seen from FIG. 7 that the measurement range of the linear zone of the device of the present invention is about twice that of the traditional cylindrical lens confocal response curve, and the axial measurement resolution is much higher than that of the traditional cylindrical lens confocal technology. The above results show that the device of the present invention has the characteristics of large range and high axial measurement resolution.

The above theoretically expounds the feasibility and superiority of replacing the circular lens (collecting objective lens and detection focusing lens) in the existing confocal detection device with a cylindrical lens to form the device of the present invention.

The present invention is not limited to the above-mentioned embodiments, and may also be a reasonable combination of the technical features described in the above-mentioned embodiments.

Claims (8)

1. line sweep differential confocal measuring device based on post lens light path; It is included in the laser instrument (1) that sets gradually on the coaxial light path; Condenser lens (2); Pin hole (3) and collimator and extender lens (4); It is characterized in that: said line sweep differential confocal measuring device based on post lens light path also comprises rectangular aperture (5); First spectroscope (6-1); Second spectroscope (6-2); Survey focal lens (7); First collects post lens (8-1); Second collects post lens (8-2); The first linear array point probe (9-1) and the second linear array point probe (9-2)

The laser beam that laser instrument (1) produces converges at pin hole (3) through condenser lens (2), after the filtered pointolite of pin hole (3) expands bundle through collimator and extender lens (4), is incident to first spectroscope (6-1) through rectangular aperture (5) again,

Transmitted light beam after first spectroscope (6-1) transmission is incident to surveys focal lens (7); And on the focal plane, picture side of surveying focal lens (7), form the line gathering, be used for the tested sample (10) that is arranged on the focal plane, picture side of surveying focal lens (7) is carried out the line illumination;

Through after surveying focal lens (7) transmission, be incident to second spectroscope (6-2) through first spectroscope (6-1) beam reflected by the light beam after tested sample (10) reflection again,

The transmitted light beam of second spectroscope (6-2) is collected on the photosurface of post lens (8-1) back line focus to the first linear array point probes (9-1) through first, and the first linear array point probe (9-1) is arranged at the burnt front position of the first collection post lens (8-1);

The folded light beam of second spectroscope (6-2) is collected on the photosurface of post lens (8-2) back line focus to the second linear array point probes (9-2) through second, and the second linear array point probe (9-2) is arranged at the defocused position of the second collection post lens (8-2);

The defocusing amount of the first linear array point probe (9-1) and the second linear array point probe (9-2) equates.

2. the line sweep differential confocal measuring device based on post lens light path according to claim 1 is characterized in that: said pin hole (3) is arranged on the rear focus place of condenser lens (2).

3. the line sweep differential confocal measuring device based on post lens light path according to claim 1 and 2 is characterized in that: the rear focus of said condenser lens (2) overlaps with the focus in object space of collimator and extender lens (4).

4. the line sweep differential confocal measuring device based on post lens light path according to claim 1; It is characterized in that: the catercorner length of said rectangular aperture (5) is less than the spot diameter of the light beam after expanding bundle through collimator and extender lens (4), greater than the spot radius of the light beam after expanding bundle through collimator and extender lens (4).

5. the line sweep differential confocal measuring device based on post lens light path according to claim 1 is characterized in that: said detection focal lens (7) is plano-convex post lens.

6. the line sweep differential confocal measuring device based on post lens light path according to claim 1 is characterized in that: it is the identical plano-convex post lens of technical parameter that the first collection post lens (8-1) and second are collected post lens (8-2).

7. the line sweep differential confocal measuring device based on post lens light path according to claim 1 is characterized in that: the said first linear array point probe (9-1) is identical with the technical parameter of the second linear array point probe (9-2).

8. according to claim 1 or 7 described line sweep differential confocal measuring devices based on post lens light path, it is characterized in that: the said first linear array point probe (9-1) and the second linear array point probe (9-2) all constitute for linear array light intensity point end of probe and the corresponding photelectric receiver that is made up of one group of single-mode fiber.

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