CN104296688A - Smooth free-form surface sample measuring device and method based on differential two-photon method - Google Patents

Abstract

The device and method for measuring smooth free-form surface samples based on the differential two-photon method belong to the field of optical microscopic measurement; the device includes a femtosecond laser, a conductive fiber, a collimating objective lens, a dichroic mirror, a focusing objective lens, a coated sample, and a three-dimensional micro-displacement load. Object stage, optical filter, collecting objective lens, beam splitting prism, first pinhole, first photodetector, second pinhole and second photodetector. The invention uses a femtosecond laser to obtain parallel light through a conductive fiber and a collimating objective lens, and then focuses the light beam on a coated sample placed on a three-dimensional micro-displacement stage through a dichroic mirror and a focusing objective lens, and the focused spot nonlinearly excites fluorescence The film emits fluorescence, and after being collected by the first photodetector and the second photodetector, the two signals are differentially calculated to obtain a differential response curve, and the surface position of the coating sample is determined by the zero point of the differential response curve. The device and method of the invention are used to measure smooth free-form surfaces, and the surface topography of samples with large angles between the normal line and the direction of the optical axis can be measured.

Description

Device and method for measuring smooth free-form surface samples based on differential two-photon method

technical field

The device and method for measuring a smooth free-form surface sample based on a differential two-photon method belong to the field of optical microscopic measurement.

Background technique

For samples with a smooth free-form surface, in the area where the angle between the normal line and the optical axis direction is large, the light illuminating the sample surface cannot be completely collected due to specular reflection, or can hardly be collected, so the surface topography cannot be highly accurate. Measure, not even measure. Therefore, how to measure a sample with a smooth free-form surface with a large slope with high precision has become a difficult problem in the field of optical measurement.

The two-photon microscopic imaging device was proposed by W.Denk, J.H.Strickler and W.W.Webb (W.Denk, J.H.Strickler and W.W.Webb (1989), 'Two-photon lasers canning fluorescence microscopy', Science, 248(4951): 73～ 76), the basic idea is to use a pulsed laser to irradiate fluorescent substances in biological cells, the fluorescent substances are excited nonlinearly by the pulsed laser spot, the fluorescent substances on the focal plane emit fluorescent signals, and the fluorescent substances outside the focal plane do not emit fluorescent signals , so as to realize the tomographic imaging of biological cells. Since the measurement object in the field of industrial measurement cannot emit fluorescence, the two-photon microscopic imaging device is mainly used in the field of biological microscopic imaging, and there is no precedent for its application in the shape measurement of industrial samples. Even if the two-photon microscope is simply transplanted to the field of industrial sample shape measurement, it cannot overcome the problem of extremely weak light intensity of the collected signal caused by the specular reflection of the beam on the sample surface with a smooth free-form surface.

Differential confocal scanning measurement is one of the typical improved confocal measurement methods. The differential confocal scanning measurement includes a confocal interference microscope with high spatial resolution imaging capability (public number CN1614457A), a shaped ring beam differential confocal sensor with high spatial resolution (public number CN1529123A), three differential confocal microscopes Imaging method and device (public number CN1587898A), three-dimensional super-resolution imaging method of three-differential confocal microscope (public number CN1609590A), three-dimensional super-resolution confocal array scanning microscopic detection method and device (public number CN1632448A), three-difference shaping ring light Dynamic confocal microscope (publication number CN1588157A), differential confocal scanning detection method with high spatial resolution (publication number CN1527026A), etc. The differential confocal measurement system places two confocal detectors at the same distance from the image side The far-focus and near-focus planes, the bipolar response characteristics are obtained through the differential calculation of the intensity response, and the tracking zero point is generated, which overcomes the shortcomings of traditional confocals that can only measure relative positions. Compared with the traditional confocal microscopy technology, this technology significantly improves the signal-to-noise ratio, and the axial resolution and measurement range are twice that of the traditional confocal microscopy technology, especially the measurement at the zero point is more accurate. However, the traditional differential confocal measurement technology is still difficult to improve the signal-to-noise ratio by fully collecting the reflection signals of smooth free-curvature surface samples, so as to achieve the purpose of measuring the topography of smooth free-curvature surface samples with high precision.

Contents of the invention

The purpose of the present invention is to solve the problem that the above-mentioned traditional method is difficult to measure the shape of a smooth free-form surface sample with a large slope, and proposes a device and method for measuring a smooth free-form surface sample based on a differential two-photon method. Coating a layer of fluorescent film, using the characteristics of the fluorescent film to radiate fluorescence in all directions under laser irradiation, avoids the problem that the light beam is reflected on the smooth free-form surface and the signal light is difficult to collect; at the same time, the two-photon excitation principle is used. The femtosecond pulse laser nonlinearly excites fluorescent substances to improve the tomographic imaging effect; the differential detection structure is used to perform differential operations on the collected two signals to obtain a differential response curve, and the zero point of the differential response curve is used to determine the position of the sample surface. Finally, the problem of measuring the shape of smooth free-form surface samples with large slopes is solved.

The purpose of the present invention is achieved like this:

Measurement of smooth free-form surface sample device based on differential two-photon method, including: excitation module, differential imaging module and coated sample;

The excitation module includes: a femtosecond laser, a conducting fiber, and a collimating objective lens; the conducting optical fiber and the collimating objective lens are sequentially arranged after the femtosecond laser;

The differential imaging module includes: a dichroic mirror, a focusing objective lens, a three-dimensional micro-displacement stage, a filter, a collecting objective lens, a beam splitting prism, a first pinhole, a first photodetector, a second pinhole and The second photodetector: a focusing objective lens and a three-dimensional micro-displacement stage are sequentially arranged on the reflected light path of the dichroic mirror, and a filter, a collecting objective lens, a beam splitting prism, and a first pinhole are arranged on the transmitted light path of the dichroic mirror , the first photodetector, the second pinhole and the second photodetector; the first pinhole is located at Δz behind the focal plane of the collection objective lens, and the second pinhole is located at Δz before the focal plane of the collection objective lens;

The coating sample is a sample to be tested whose surface is coated with a thin film of fluorescent substance;

The femtosecond laser in the excitation module emits excitation light, which forms parallel light after passing through the conducting fiber and the collimating objective lens, and the parallel light beam forms a focused spot on the coated sample after being reflected by the dichroic mirror and transmitted by the focusing objective lens. The focused light spot excites the fluorescent film on the surface of the coated sample to emit fluorescence; the fluorescent film at the focal plane nonlinearly excites fluorescence, and the fluorescent film above or below the focal plane does not emit fluorescence;

The fluorescence excited on the surface of the coating sample is transmitted through the focusing objective lens, dichroic mirror, filter, and collecting objective lens, and then is divided into two beams of light by the beam splitting prism, and the transmitted light is collected by the first photodetector through the first pinhole , the reflected light is collected by the second photodetector through the second pinhole.

The above-mentioned device for measuring smooth free-form surface samples based on the differential two-photon method, the surface of the coated sample is coated with a layer of fluorescent film by evaporation, the fluorescent film is easily soluble in water or organic solvents, and the thickness is not more than 1 μm.

The method for measuring a smooth free-form surface sample based on a differential two-photon method implemented on the above-mentioned device for measuring a smooth free-form surface sample based on a differential two-photon method includes the following steps:

(a) forming a fluorescent film with a thickness of no more than 1 μm on the surface of the sample by evaporation, and the fluorescent film closely fits the contour of the sample to form a coated sample;

(b) The femtosecond laser emits excitation light, which forms parallel light after passing through the conductive fiber and the collimating objective lens. The parallel beam forms a focused spot on the coated sample after being reflected by the dichroic mirror and transmitted by the focusing objective lens. The focused spot excites the coating The fluorescent film on the surface of the sample emits fluorescence; the fluorescent film at the focal plane nonlinearly excites fluorescence, and the fluorescent film above or below the focal plane does not emit fluorescence;

(c) After the fluorescence excited by the fluorescent film is collected by the first photodetector and the second photodetector, the two signals are differentially calculated to obtain a differential response curve, and the surface position of the coating sample is determined by the zero point of the differential response curve;

Two calculations can be performed on the obtained two differential signals:

① Perform differential calculation on the two signals:

I _D1 (x _s ,z _s )＝(|U _D (x _s ,z _s ,△z)| ² +c ₀ )-(|U _D (x _s ,z _s ,-△z)| ² +c ₀ )

＝|U _D (x _s ,z _s ,△z)| ² -|U _D (x _s ,z _s ,-△z)| ²

Among them, _ID1 represents the intensity response function of the system during differential calculation, U _D represents the amplitude response function of the system under double-pass illumination, x _s and z _s represent the position coordinates, △ z represents the defocus amount of the detector, c ₀ represents the signal center common mode noise;

②Calculation of anti-crosstalk for two signals:

$\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}\\ <span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}\end{array}$

Among them, I _D2 represents the strength response function of the system during anti-crosstalk calculation;

(d) The three-dimensional micro-displacement stage drives the three-dimensional movement of the coating sample to form a three-dimensional scanning image;

(e) Use water or an organic solvent to wash off the fluorescent film on the surface of the sample.

Good effect of the present invention is:

1) By coating the sample with fluorescent film, it overcomes the limitations of the traditional confocal method and other non-contact optical measurement techniques due to the specular reflection of the light beam on the surface of the smooth free-form surface sample, and measures the smooth free-form surface sample based on the differential two-photon method The device and method can realize the shape measurement of a smooth free-form surface sample with a large slope, and realize the collection of signal light reflected from the side of the sample.

2) The application of two-photon microscopy to the field of industrial measurement is conducive to improving the chromatography ability of the sample profile.

3) Equivalent focal detection on the image side is adopted, and the common mode noise or series mode noise can be effectively suppressed after the measurement results are processed.

Description of drawings

Fig. 1 is a schematic diagram of the device for measuring smooth free-form surface samples based on the differential two-photon method.

Part number description in the figure: 1. Femtosecond laser, 2. Conductive fiber, 3. Collimating objective lens, 4. Dichroic mirror, 5. Focusing objective lens, 6. Coated sample, 7. Three-dimensional micro-displacement stage, 8 , filter, 9, collecting objective lens, 10, beam splitting prism, 11, first pinhole, 12, first photodetector, 13, second pinhole, 14, second photodetector.

Detailed ways

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Specific embodiment one

This embodiment is a device embodiment.

The structure diagram of the device for measuring a smooth free-form surface sample based on the differential two-photon method in this embodiment is shown in FIG. 1 . The device includes: an excitation module, a differential imaging module and a coating sample 6;

The excitation module includes: a femtosecond laser 1, a conducting fiber 2, and a collimating objective lens 3; the conducting optical fiber 2 and the collimating objective lens 3 are sequentially arranged after the femtosecond laser 1;

The differential imaging module includes: a dichroic mirror 4, a focusing objective lens 5, a three-dimensional micro-displacement stage 7, an optical filter 8, a collecting objective lens 9, a dichroic prism 10, a first pinhole 11, a first photodetector device 12, the second pinhole 13 and the second photodetector 14; the focusing objective lens 5 and the three-dimensional micro-displacement stage 7 are sequentially arranged on the reflected light path of the dichroic mirror 4, and arranged on the transmitted light path of the dichroic mirror 4 Optical filter 8, collecting objective lens 9, dichroic prism 10, first pinhole 11, first photodetector 12, second pinhole 13 and second photodetector 14; Described first pinhole 11 is positioned at collecting objective lens 9 behind the focal plane at △z, the second pinhole 13 is located at △z before the focal plane of the collecting objective lens 9;

The coating sample 6 is a sample to be tested whose surface is coated with a thin film of fluorescent substance;

In the above-mentioned device for measuring smooth free-form surface samples based on the differential two-photon method, the coating sample 6 is coated with a layer of fluorescent film by evaporation, and the fluorescent film is easily soluble in water or organic solvents, and the thickness is not more than 1 μm;

When measuring using:

The femtosecond laser 1 in the excitation module emits excitation light, which forms parallel light after passing through the conductive fiber 2 and the collimating objective lens 3, and the parallel beam forms a focused spot on the coated sample 6 after being reflected by the dichroic mirror 4 and transmitted by the focusing objective lens 5. The focused spot excites the fluorescent film on the surface of the coated sample 6 to emit fluorescence; the fluorescent film at the focal plane nonlinearly excites fluorescence, and the fluorescent film above or below the focal plane does not emit fluorescence;

The fluorescence excited on the surface of the coating sample 6 passes through the focusing objective lens 5, the dichroic mirror 4, the optical filter 8, and the collecting objective lens 9, and then is divided into two beams of light by the beam splitter 10, and the transmitted light passes through the first pinhole 11 and is transmitted by the first pinhole 11. The photodetector 12 collects, and the reflected light passes through the second pinhole 13 and is collected by the second photodetector 14 .

Specific embodiment two

This embodiment is an embodiment of the method implemented on the device described in the first specific embodiment.

The method for measuring a smooth free-form surface sample based on the differential two-photon method of this embodiment includes the following steps:

(a) The fluorescent material rhodamine B, which is easily soluble in water, is plated on the surface of the sample by evaporation to form a fluorescent film with a thickness of no more than 1 μm. The fluorescent film closely fits the contour of the sample to form a coated sample 6;

(b) The femtosecond laser 1 emits excitation light, which forms parallel light after passing through the conducting fiber 2 and the collimating objective lens 3, and the parallel light beam is reflected by the dichroic mirror 4 and transmitted by the focusing objective lens 5 to form a focused spot on the coated sample 6, so The above focused spot excites the fluorescent film on the surface of the coating sample 6 to emit fluorescence; the fluorescent film at the focal plane nonlinearly excites fluorescence, and the fluorescent film above or below the focal plane does not emit fluorescence;

(c) After the fluorescence excited by the fluorescent film is collected by the first photodetector 12 and the second photodetector 14, the two signals are differentially calculated to obtain a differential response curve, and the surface position of the coated sample is determined by the zero point of the differential response curve ;

Two calculations can be performed on the obtained two differential signals:

① Perform differential calculation on the two signals:

I _D1 (x _s ,z _s )＝(|U _D (x _s ,z _s ,△z)| ² +c ₀ )-(|U _D (x _s ,z _s ,-△z)| ² +c ₀ )

＝|U _D (x _s ,z _s ,△z)| ² -|U _D (x _s ,z _s ,-△z)| ²

Among them, _ID1 represents the intensity response function of the system during differential calculation, U _D represents the amplitude response function of the system under double-pass illumination, x _s and z _s represent the position coordinates, △ z represents the defocus amount of the detector, c ₀ represents the signal center common mode noise;

②Calculation of anti-crosstalk for two signals:

$\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}\\ <span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}\end{array}$

Among them, I _D2 represents the strength response function of the system during anti-crosstalk calculation;

(d) The three-dimensional micro-displacement stage 7 drives the coating sample 6 to move three-dimensionally, forming a three-dimensional scanning image;

(e) Use water or an organic solvent to wash off the rhodamine B fluorescent film on the surface of the sample.

Claims (3)

1. A device for measuring a smooth free-form surface sample based on a differential two-photon method, characterized in that it includes: an excitation module, a differential imaging module and a coated sample (6); The excitation module includes: a femtosecond laser (1), a conducting fiber (2), and a collimating objective lens (3); the conducting optical fiber (2) and the collimating objective lens (3) are sequentially arranged after the femtosecond laser (1); The differential imaging module includes: a dichroic mirror (4), a focusing objective lens (5), a three-dimensional micro-displacement stage (7), an optical filter (8), a collecting objective lens (9), a beam splitting prism (10 ), the first pinhole (11), the first photodetector (12), the second pinhole (13) and the second photodetector (14); sequentially arranged on the reflected light path of the dichroic mirror (4) Focusing objective lens (5) and three-dimensional micro-displacement stage (7), on the transmission light path of dichroic mirror (4), arrange optical filter (8), collecting objective lens (9), dichroic prism (10), first needle Holes (11), first photodetectors (12), second pinholes (13) and second photodetectors (14); the first pinholes (11) are located behind the focal plane of the collecting objective lens (9) At Δz, the second pinhole (13) is located at Δz before the focal plane of the collecting objective lens (9); The coating sample (6) is a sample to be tested whose surface is coated with a thin film of fluorescent substance; The femtosecond laser (1) in the excitation module emits excitation light, forms parallel light after passing through the conduction fiber (2) and the collimating objective lens (3), and the parallel light beam is reflected by the dichroic mirror (4) and focused on the objective lens ( 5) After transmission, a focused spot is formed on the coated sample (6), and the focused spot excites the fluorescent film on the surface of the coated sample (6) to emit fluorescence; the fluorescent film at the focal plane non-linearly excites fluorescence, above the focal plane or The following fluorescent films do not emit fluorescence; Fluorescence excited on the surface of the coating sample (6) is transmitted through the focusing objective lens (5), dichroic mirror (4), filter (8) and collecting objective lens (9) and then divided by the dichroic prism (10). There are two beams of light, one beam of light is collected by the first photodetector (12) through the first pinhole (11), and the other beam of light is collected by the second photodetector (14) through the second pinhole (13). 2. The device for measuring a smooth free-form surface sample based on a differential two-photon method according to claim 1, wherein the surface of the coated sample (6) is coated with a layer of fluorescent film by evaporation, and the The fluorescent film is easily soluble in water or organic solvents, and the thickness does not exceed 1 μm. 3. The method for measuring a smooth free-form surface sample based on a differential two-photon method, is characterized in that, comprising the following steps: (a) forming a fluorescent film with a thickness of no more than 1 μm on the surface of the sample by evaporation, the fluorescent film closely fits the contour of the sample to form a coated sample (6); (b) The femtosecond laser (1) emits excitation light, which forms parallel light after passing through the conducting fiber (2) and collimating objective lens (3), and the parallel light beam is reflected by the dichroic mirror (4) and transmitted by the focusing objective lens (5) A focused spot is formed on the coated sample (6), and the focused spot excites the fluorescent film on the surface of the coated sample (6) to emit fluorescence; the fluorescent film at the focal plane nonlinearly excites fluorescence, and the fluorescent film above or below the focal plane Does not fluoresce; (c) After the fluorescence excited by the fluorescent film is collected by the first photodetector (12) and the second photodetector (14), the two signals are differentially calculated to obtain a differential response curve, which is determined by the zero point of the differential response curve Surface position of coating sample; Two calculations can be performed on the obtained two differential signals: ① Perform differential calculation on the two signals: $\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>\\ <span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}$ Among them, _ID1 represents the intensity response function of the system during differential calculation, U _D represents the amplitude response function of the system under double-pass illumination, x _s and z _s represent the position coordinates, △ z represents the defocus amount of the detector, c ₀ represents the signal center common mode noise; ②Calculation of anti-crosstalk for two signals: $\begin{array}{c}{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}\\ <span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}\end{array}$ Among them, I _D2 represents the strength response function of the system during anti-crosstalk calculation; (d) The three-dimensional micro-displacement stage (7) drives the coating sample (6) to move three-dimensionally to form a three-dimensional scanning image; (e) Use water or an organic solvent to wash off the fluorescent film on the surface of the sample.