CN102566048B - Astigmatism-based sample axial drift compensating method and device - Google Patents

Abstract

The invention discloses a sample axial drift compensation method and device based on astigmatism. The device includes a laser, a single-mode optical fiber, a collimating lens, a beam splitting prism, an astigmatism processor composed of two cylindrical mirrors with the same focal length and orthogonal cross-sections, a microscope objective lens, a three-dimensional nano-scanning platform, a focusing lens, an optical Attenuators, photoelectric sensing devices and computers. The method includes: forming the first astigmatic beam through the above-mentioned astigmatism processor through the collimated light beam, and then being reflected after the sample to be measured is focused, and forming the second astigmatism beam through the above-mentioned astigmatism processor again, and reflecting through the dichroic prism to obtain The monitoring beam is received by the photoelectric sensor after being focused by the focusing lens, and the relationship between the focused spot of the monitoring beam and the axial drift of the sample to be measured is calibrated and input to the computer for sample axial drift compensation. The invention has the advantages of simple structure, convenient use, high measurement sensitivity and can be used in high-precision super-resolution microscopic equipment.

Description

A sample axial drift compensation method and device based on astigmatism

technical field

The invention belongs to the field of high-precision and super-resolution microscopy, and in particular relates to a sample axial drift compensation method and device based on astigmatism.

Background technique

During the working process of the microscopic system, due to the influence of factors such as thermal drift and stress drift, the sample to be tested will inevitably drift axially over time, resulting in defocus, which will affect the imaging accuracy of the microscopic system. Especially for microscopic methods that require multiple repeated scans of the same pixel, the impact of this axial drift will be more obvious, because the axial drift will cause multiple repeated scans to not be the same pixel point. Therefore, a method that can measure and compensate the axial drift of the microscopic sample in real time will play a very important role in improving the precision of the microscopic system.

With the development of science and technology, researchers have proposed a variety of methods to measure the axial drift of the sample, among which the optical non-contact measurement method is the most widely used. Currently, optical non-contact measurement methods are mostly based on confocal systems. Although this system has good measurement accuracy, its structure is relatively complicated, which limits the scope of application of the method to a certain extent.

Contents of the invention

The invention provides a sample axial drift compensation method and device based on astigmatism, the device has a simple structure, the method is convenient to use, and has high measurement sensitivity. This method and device can be widely used in high-precision super-resolution microscopy equipment such as confocal microscopy (Confocal Microscopy), stimulated emission depletion microscopy (STED: Stimulated Emission Depletion Microscopy), to measure the axial position drift of the sample to be tested. Compensation is performed to ensure the precision of the microscope system.

A sample axial drift compensation method based on astigmatism, comprising the following steps:

(1) The laser beam emitted by the laser is collimated through a single-mode fiber and a collimating lens;

(2) The collimated light is decomposed into the first reflected light and the first transmitted light after being acted on by the dichroic prism;

(3) The first transmitted light passes through an astigmatic processor composed of two cylindrical mirrors with the same focal length and mutually orthogonal cross-sections to form a first astigmatic light beam;

(4) The first astigmatic light beam is projected onto the sample to be measured placed on the three-dimensional nano-scanning platform after being focused by a microscope objective lens, and the light beam reflected by the sample to be measured returns along the original optical path in reverse, and is determined by the microscope. After being collected by the micro-objective lens, the second astigmatic beam is formed through the astigmatism processor again;

(5) the second astigmatic light beam is decomposed into a second transmitted ray and a second reflected ray by the dichroic prism;

(6) The second reflected light is focused by the focusing lens as the monitoring beam, and then received by the photoelectric sensor after passing through the optical attenuator to obtain the characteristic parameters of the focused spot of the monitoring beam, and calibrate the characteristic parameter of the focused spot of the monitoring beam and the sample to be tested The relationship between the axial drift amount, this relationship is input into the computer as a system calibration function to complete the calibration of the system;

(7) After the system is calibrated, it is used to compensate for the axial drift of the sample: when the sample to be tested drifts axially, the computer tracks in the calibrated system according to the characteristic parameters of the monitoring beam focus spot output by the photoelectric sensor The axial drift of the corresponding sample to be tested is queried, and an instruction is issued to adjust the axial position of the three-dimensional nano-scanning platform to realize axial drift compensation of the sample to be tested.

The photoelectric sensing device is a high-speed charge-coupled device (CCD: Charge Couple Device) or a quadrant detector (QD: Quadrant Detector), and the quadrant detector is placed vertically.

When a CCD is used as the photoelectric sensing device, the characteristic parameter of the focused spot of the monitoring beam is the full width half maximum value of the intensity distribution curve of the focused spot formed by the monitoring beam on the CCD.

When the QD is used as the photoelectric sensing device, the QD is placed vertically, and the characteristic parameter of the focused spot of the monitoring beam is the four-quadrant output current differential value calculated according to the output current on the four quadrants of the four-quadrant detector.

The present invention also provides a sample axial drift compensation device based on astigmatism, including:

laser;

A single-mode optical fiber, a collimating lens, a beam splitting prism, an astigmatism processor, a microscopic objective lens and a three-dimensional nano-scanning platform for placing a sample to be measured are sequentially arranged on the optical axis of the outgoing light path of the laser; wherein, the The exit end face of the single-mode optical fiber is located at the focal point of the collimator lens, and the astigmatism processor is composed of two cylindrical mirrors with the same focal length and mutually orthogonal cross-sections;

A focusing lens, an optical attenuator and a photoelectric sensing device are arranged in sequence on the optical axis of the monitoring beam optical path, and the photoelectric sensing device is located at the image focus of the focusing lens; wherein, the optical axis of the monitoring beam optical path is in line with the The optical axis of the outgoing light path of the laser is vertical, and the monitoring beam is obtained by sequentially collecting the light reflected by the sample to be measured and being astigmatized by the astigmatism processor and then split by the beam splitting prism the reflected light;

And a computer connected to the three-dimensional nano-scanning platform and the photoelectric sensing device at the same time.

In the device of the present invention, the laser is used to emit a laser beam, the single-mode fiber and collimating lens are used to collimate the laser beam, the beam splitting prism is used to split light, and the astigmatism processor is used to The spot shape of the incident beam is modulated to obtain an astigmatic beam. The microscopic objective lens is used to focus and project the incident light onto the sample to be tested and to collect the beam reflected by the sample to be tested. The focusing lens is used to focus the monitoring beam On the sensing surface of the photoelectric sensing device, the optical attenuator is used for light attenuation to avoid light intensity saturation of the photoelectric sensing device, and the photoelectric sensing device is used for receiving the focused spot of the monitoring beam and outputting corresponding monitoring information according to the received signal ( monitor the characteristic parameters of the focused light spot of the light beam), the computer is used to receive the monitoring information fed back by the photoelectric sensing device and send out an adjustment control signal after analyzing and processing, and the three-dimensional nano-scanning platform is used to place the sample to be tested and send out an adjustment signal according to the computer. The adjustment control signal is used to adjust the axial position of the sample to be measured on the scanning platform.

In a preferred technical solution, in the astigmatism processor, the angle between the cross section of the first cylindrical mirror and the horizontal plane is 45°, and the angle between the cross section of the second cylindrical mirror and the horizontal plane is 135°.

In a preferred technical solution, in the astigmatism processor, the focal length of the two cylindrical mirrors is 150mm.

In a preferred technical solution, the photoelectric sensing device is a high-speed charge-coupled device (CCD) or a four-quadrant detector (QD).

Principle of the present invention is as follows:

For a cylindrical lens, its cross section (that is, the radial section) can be regarded as a spherical lens, while the longitudinal section (that is, the axial section) can be regarded as a flat plate. Therefore, when two parallel rays are incident in the cross section of the cylindrical mirror, the outgoing rays will intersect at a point on the focal line of the cylindrical mirror; and when two parallel rays are incident in the longitudinal section of the cylindrical mirror, the outgoing rays The rays will still remain parallel. Therefore, the imaging of the cylindrical mirror has astigmatism.

According to the above-mentioned imaging properties of the cylindrical mirror, when the Gaussian beam passes through a single cylindrical mirror, the spot of the outgoing beam will be elliptical, and the long axis of the elliptical spot is perpendicular to the cross section of the cylindrical mirror.

After the Gaussian beam passes through the astigmatism processor composed of two cylindrical mirrors with the same focal length and cross-sections orthogonal to each other, the shape of the elliptical spot of the outgoing beam will change as the outgoing beam propagates: in the first cylinder At the focal point of the image side of the surface mirror, the long axis of the elliptical spot of the outgoing beam is perpendicular to the cross section of the first cylindrical mirror; while at the focal point of the image square of the second cylindrical mirror, the long axis of the elliptical spot of the outgoing beam is perpendicular to the cross section of the second cylindrical mirror The cross-section of the mirror is vertical. Since the cross-sections of the two cylindrical mirrors are orthogonal to each other, when the outgoing beam propagates from the image focal point of the first cylindrical mirror to the image focal point of the second cylindrical mirror, the direction of the elliptical spot of the beam (the direction of the long axis of the ellipse) ) turned by 90°. During this process, the length of the beam elliptical spot in the direction perpendicular to the cross-section of the first cylindrical mirror gradually becomes shorter, and the length in the direction perpendicular to the cross-section of the second cylindrical mirror gradually becomes longer.

When the Gaussian beam sequentially passes through the astigmatism processor and the microscopic objective lens composed of two cylindrical lenses with the same focal length and orthogonal cross-sections, the shape of the elliptical spot of the outgoing beam will also change with the propagation of the outgoing beam. Change: At the focal point of the combined image side of the first cylindrical lens and the microscopic objective lens, the long axis of the elliptical spot of the outgoing beam is perpendicular to the cross section of the first cylindrical lens; while at the combination of the second cylindrical lens and the microscopic objective lens At the focal point of the image side, the long axis of the elliptical spot of the outgoing beam is perpendicular to the cross section of the second cylindrical mirror. Since the cross-sections of the two cylindrical mirrors are orthogonal to each other, when the outgoing beam propagates from the combined image focal point of the first cylindrical mirror and the microscopic objective lens to the combined image focal point of the second cylindrical mirror and the microscopic objective lens, the light beam The direction of the elliptical light spot (the direction of the long axis of the ellipse) has been rotated by 90°. During this process, the length of the beam elliptical spot in the direction perpendicular to the cross-section of the first cylindrical mirror gradually becomes shorter, and the length in the direction perpendicular to the cross-section of the second cylindrical mirror gradually becomes longer.

The area between the combined image focal point of the first cylindrical lens and the microscopic objective lens and the combined image focal point of the second cylindrical lens and the microscopic objective lens is regarded as the equivalent focal area, and the axial length of the equivalent focal area is called Equivalent depth of focus. The equivalent focal depth can be calculated according to the following formula:

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; \&prime;</span>\mathrm{<span\; class="notranslate">\; 2</span>}}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}$

Where Δ is the equivalent focal depth, f is the focal length of the two cylindrical lenses, f′ is the focal length of the microscopic objective lens, d ₁ is the distance between the two cylindrical lenses, and d ₂ is the distance between the microscopic objective lens and the second cylindrical lens Pitch.

When the sample to be measured axially drifts in the equivalent focal area, the shape of the elliptical spot formed by the first astigmatic beam focusing on the sample to be measured through the microscope objective lens will change accordingly, and the corresponding monitoring beam (by The light reflected by the sample to be measured is sequentially collected by the microscopic objective lens and astigmatized by the astigmatism processor, and then the reflected light obtained by the light splitting by the dichroic prism is the monitoring light beam) and is focused on the photoelectric sensor to form an elliptical spot. The shape will also change accordingly. Therefore, it is possible to calibrate the relationship between the characteristic parameters of the monitoring beam focusing spot and the axial drift of the sample, which can reflect the shape change of the elliptical spot formed on the photoelectric sensing device, and use it for real-time compensation of the axial drift of the sample.

The astigmatism-based sample axial drift compensation device of the present invention can also be used as an independent module in the measurement optical path of a high-precision super-resolution microscope to compensate the axial drift of the sample to be measured in real time.

Compared with the prior art, the present invention has the following beneficial technical effects:

(1) The device has a simple structure and is easy to operate;

(2) It has high measurement sensitivity and large measurement range;

(3) The adjustment process is fast and accurate, and will not interfere with the working optical path of the microscope.

Description of drawings

Fig. 1 is a schematic diagram of the sample axial drift compensation device based on astigmatism of the present invention;

2 is a schematic diagram of the astigmatism-based sample axial drift compensation device of the present invention when it is applied to the working optical path of a microscope as an independent module;

Fig. 3 is when the present invention adopts CCD as photoelectric induction device, the corresponding curve of measured full width at half maximum value and axial position drift of the sample to be measured;

Fig. 4 is a corresponding curve of the four-quadrant output current differential value and the axial position drift of the sample to be measured when QD is used as the photoelectric sensing device in the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the embodiments and accompanying drawings, but the present invention is not limited thereto.

A sample axial drift compensation device based on astigmatism, as shown in Figure 1, comprising: a laser 1, a single-mode fiber 2, a collimating lens 3, a beam splitting prism 4, a first cylindrical mirror 5, and a second cylindrical mirror 6. Microscopic objective lens 7, three-dimensional nano-scanning platform 8, focusing lens 9, optical attenuator 10, photoelectric sensing device 11 and computer 12.

The laser 1 emits a laser beam, and the single-mode fiber 2, collimating lens 3, beam splitter 4, first cylindrical mirror 5, second cylindrical mirror 6, microscopic objective lens 7 and three-dimensional nano-scanning platform 8 are located on the laser 1 in sequence On the optical axis of the outgoing light path, wherein, the outgoing end face of the single-mode optical fiber 2 is located at the object focus of the collimator lens 3, the angle between the cross section of the first cylindrical mirror 5 and the horizontal plane is 45°, and the second cylindrical mirror The angle between the cross section of 6 and the horizontal plane is 135°, the focal length of the first cylindrical lens 5 and the second cylindrical lens 6 are the same, and the microscopic objective lens 7 focuses the light onto the sample to be measured on the three-dimensional nano-scanning platform 8, three-dimensional The nano scanning platform 8 can adjust the axial position of the sample to be measured.

The focusing lens 9, the optical attenuator 10 and the photoelectric sensing device 11 are located on the optical axis of the optical path of the monitoring beam R2 in turn, and the photoelectric sensing device 11 is located at the focal point of the image side of the focusing lens 9; The optical axis of the outgoing light optical path is vertical, and the monitoring light beam R2 is the light reflected by the sample to be measured, which is collected by the microscopic objective lens 7 and processed by the astigmatism processor (consisting of the first cylindrical mirror 5 and the second cylindrical mirror 6) After the astigmatism, the reflected light is obtained by splitting light by the beam splitting prism 4;

The computer 12 is connected to the three-dimensional nano-scanning platform 8 and the photoelectric sensing device 11 at the same time.

In the above device, the function of the optical attenuator 10 is to prevent the photoelectric sensor 11 from being saturated with light intensity. The photoelectric sensing device 11 is a high-speed charge-coupled device (CCD) or a four-quadrant detector (QD).

Using the device shown in Figure 1 to compensate the axial drift of the sample based on astigmatism is as follows:

The laser beam emitted from the laser 1 is first introduced into the single-mode fiber 2 , and the laser beam emitted from the single-mode fiber 2 is collimated through the collimating lens 3 .

The collimated light beam is decomposed into the first transmitted light and the first reflected light after passing through the dichroic prism 4, and the first transmitted light is formed after passing through the astigmatism processor (consisting of the first cylindrical mirror 5 and the second cylindrical mirror 6). The first astigmatic beam R1.

The first astigmatic beam R1 is focused by the microscope objective lens 7 and then projected onto the sample to be measured on the three-dimensional nano-scanning platform 8. The beam reflected by the sample to be measured returns along the original optical path in reverse, and is collected by the microscope objective lens 7. , form the second astigmatic light beam through the astigmatism processor (made up of the first cylindrical lens 5 and the second cylindrical lens 6) again, and the second astigmatic light beam is decomposed into the second transmitted ray and the second light beam through the dichroic prism 4. Two reflected light rays, wherein the second reflected light beam is the monitor light beam R2.

The monitoring beam R2 is focused by the focusing lens 9, and then received by the photoelectric sensor 11 after passing through the optical attenuator 10 to obtain the characteristic parameters of the focused spot of the monitoring beam, and calibrate the characteristic parameters of the focused spot of the monitoring beam and the axial drift of the sample to be measured. The relationship is input into the computer 12 as a system calibration function to complete the calibration of the system.

After the system is calibrated, it is used to compensate the axial drift of the sample: when the sample to be tested drifts axially, the computer 12 tracks and inquires in the calibrated system according to the characteristic parameters of the focus spot of the monitoring beam output by the photoelectric sensor Corresponding to the axial drift of the sample to be measured, and based on this, an instruction is issued to adjust the axial position of the three-dimensional nano-scanning platform 8 to achieve axial drift compensation of the sample to be measured.

Specifically:

When using a CCD as the photoelectric sensing device 11, the sample to be tested is placed on the three-dimensional nano-scanning platform 8, and by adjusting the axial position of the three-dimensional nano-scanning platform 8, the intensity distribution of the focused spot formed by the monitoring beam R2 on the CCD is obtained in real time The full width at half maximum value of the curve, thereby obtaining the relationship between the full width at half maximum value of the focused spot and the axial drift of the sample to be measured, the curve is shown in Figure 3, and this relational expression is input into the computer 12 as a system calibration function to complete the calibration of the system.

After the system is calibrated, it is used to compensate the axial drift of the sample: when the sample to be measured drifts axially, the CCD transmits the full width at half maximum value of the focused spot to the computer 12, and the computer 12 tracks and inquires the corresponding sample to be tested in the calibrated system. The axial position drift of the sample is measured, and an instruction is issued to adjust the axial position of the three-dimensional nano-scanning platform 8 to realize axial drift compensation of the sample to be measured. When the full width at half maximum value of the measured focused spot is equal to the calibration value when the sample has no axial drift, the axial position drift compensation of the sample to be tested is completed.

The full width at half maximum of the focus spot mentioned above is obtained by the following method: through the center of the CCD photoelectric sensing surface, draw a straight line with an angle of 45° with the horizontal direction in the sensing face, and calculate the light intensity of each point on the straight line The full width at half maximum value of the distribution curve. Since the shape of the focused spot can be uniquely determined according to the full width at half maximum of the focused spot, the full width at half maximum of the intensity distribution curve of the focused spot formed by the monitoring beam on the photoelectric sensing device can be used as a characteristic parameter of the focused spot of the monitoring beam.

When using QDs as photo-sensing devices, place the QDs vertically. According to the detection principle of QD, the output current on the four quadrants is linearly related to the energy of the spot irradiated on each quadrant. Therefore, the shape of the elliptical spot formed by the monitoring beam can be characterized by performing a differential operation on the output current of each quadrant. , the specific formula is as follows:

Δr=I ₁ +I ₃ -I ₂ -I ₄

Among them, I ₁ , I ₂ , I ₃ , and I ₄ are the output currents of the beam on the four quadrants of the QD, respectively, and Δr is the differential value of the output current of the four quadrants, which is used as a characteristic parameter of the focused spot of the monitoring beam to characterize the shape of the focused spot.

Similarly, the sample to be tested is placed on the three-dimensional nano-scanning platform 8, and the axial position of the three-dimensional nano-scanning platform 8 is adjusted, and the output current on the four quadrants on the QD is recorded in real time, and the four-quadrant output current differential value Δr is calculated, so that The relationship between the four-quadrant output current differential value Δr and the axial drift of the sample to be measured is obtained, the curve is shown in Figure 4, and this relationship is input into the computer 12 as a system calibration function to complete the system calibration.

After the system is calibrated, it is used for sample axial drift compensation: when the sample to be tested has axial drift, QD will transmit the calculated four-quadrant output current differential value Δr to the computer 12, and the computer 12 will track and query in the calibrated system The corresponding axial position drift of the sample to be measured is obtained, and an instruction is issued to adjust the axial position of the three-dimensional nano-scanning platform 8 to realize axial drift compensation of the sample to be measured. When the four-quadrant output current differential value Δr is equal to the calibration value when the sample has no axial drift, the axial position drift compensation of the sample to be tested is completed.

The whole process is monitored in real time and continuously circulated, so as to complete the real-time compensation for the axial drift of the sample to be tested.

The structure inside the black frame in Figure 1 can constitute an independent sample axial drift compensation module, which can be applied to the measurement optical path of a high-precision super-resolution microscope to compensate the axial drift of the sample to be measured in real time. The specific working optical path is shown in Figure 2.

That is, the high-precision super-resolution microscope system using the sample axial drift compensation module of the present invention includes: a microscope objective lens 7, a three-dimensional nano-scanning platform 8, a computer 12, dichroic mirrors 13, 14, and a sample axis based on astigmatism To the drift compensation module 15 , the microscope focusing lens 16 and the microscope detector 17 .

The internal specific structure of the sample axial drift compensation module 15 based on astigmatism is shown in the internal structure of the black box in Figure 1, including: a laser 1, a single-mode fiber 2, a collimating lens 3, a beam splitting prism 4, and a first cylindrical surface Mirror 5, second cylindrical mirror 6, focusing lens 9, optical attenuator 10 and photoelectric sensing device 11.

The method of applying the astigmatism-based sample axial drift compensation module 15 of the present invention in a high-precision super-resolution microscope system to compensate the sample axial drift is as follows:

The first astigmatic beam R1 emitted by the sample axial drift compensation module 15 based on astigmatism is reflected by the dichroic mirror 14, and the reflected beam and the microscope working beam R3 are focused by the microscope objective lens 7 and then projected onto the sample to be tested superior. The astigmatic light beam reflected by the sample to be measured and the working light beam of the microscope form separation when passing through the dichroic mirror 14, wherein the astigmatic light beam reflected by the sample to be measured is reflected by the dichroic mirror 14, and the astigmatic light beam reflected by the sample axis based on the astigmatism The drift compensation module 15 receives and converts the monitoring light beam R2; while the working light beam of the microscope reflected by the sample to be measured passes through the dichroic mirror 14, and then passes through the dichroic mirror 13 to form the microscope imaging light beam R4 and is combined with the incident working light beam. The beam is separated, and the microscope imaging beam R4 is focused by the microscope focusing lens 16 and then received by the microscope detector 17 for microscopic imaging.

The sample axial drift compensation module 15 based on astigmatism outputs the corresponding monitoring signal according to the focused spot information formed by the monitoring beam R2 and sends it to the computer 12, which is converted into a corresponding control signal after being processed by the computer 12 for adjusting the three-dimensional nano-scanning platform The axial position of 8, so as to realize the compensation of the axial drift of the sample to be tested.

In actual operation, the whole process is monitored in real time and continuously circulated, so as to complete the real-time compensation for the axial drift of the sample to be tested.

Claims (7)

1. the axial drift compensation method of the sample based on astigmatism is characterized in that, may further comprise the steps:

(1) laser beam that is sent by laser instrument collimates through single-mode fiber and collimation lens;

(2) through after the effect of Amici prism of the process of the light behind the collimation, be decomposed into first reflection ray and first transmitted ray;

(3) described first transmitted ray is through forming first astigmatic pencil by two astigmatism processors that cylindrical mirror constituted that focal length is identical and xsect is mutually orthogonal;

(4) described first astigmatic pencil projects on the testing sample that places on the three-dimensional manometer scanning platform after focusing on by microcobjective, light beam after the testing sample reflection returns along original optical path is reverse, after described microcobjective collection, form second astigmatic pencil through described astigmatism processor once more;

(5) second astigmatic pencils are decomposed into second transmitted ray and second reflection ray through described Amici prism;

(6) described second reflection ray is as monitoring light beam line focus lens focus, receive by the optoelectronic induction device through behind the optical attenuator again, obtain the characteristic parameter of monitoring light beam focal beam spot, the relation of the characteristic parameter of demarcation monitoring light beam focal beam spot and the axial drift value of testing sample, this relational expression as system calibrating function input computing machine, is finished the demarcation of system;

(7) system calibrating good after, be used for the axial drift compensation of sample: when axially drift takes place testing sample, computing machine according to by the characteristic parameter of the monitoring light beam focal beam spot of described optoelectronic induction device output in demarcating good system tracking enquiry to the axial drift value of corresponding testing sample, and send the axial location that the three-dimensional manometer scanning platform is adjusted in instruction in view of the above, realize axial drift compensation to testing sample.

2. the axial drift compensation method of the sample based on astigmatism as claimed in claim 1, it is characterized in that, described optoelectronic induction device is high-speed charge coupled device, the characteristic parameter of described monitoring light beam focal beam spot by monitoring light beam on described optoelectronic induction device the full width at half maximum value of one-tenth focal beam spot strength distribution curve.

3. the axial drift compensation method of the sample based on astigmatism as claimed in claim 1, it is characterized in that, described optoelectronic induction device is the vertical 4 quadrant detector of placing, the four-quadrant output current difference value of the characteristic parameter of described monitoring light beam focal beam spot for calculating according to the output current on the 4 quadrant detector four-quadrant.

4. the axial drift compensation device of the sample based on astigmatism is characterized in that, comprising:

Laser instrument;

Single-mode fiber, collimation lens, Amici prism, astigmatism processor, microcobjective that on the optical axis of the emergent light light path of described laser instrument, sets gradually and the three-dimensional manometer scanning platform that is used to place testing sample; Wherein, the outgoing end face of described single-mode fiber is positioned at the focus in object space place of collimation lens, and two cylindrical mirrors that described astigmatism processor is identical by focal length and xsect is mutually orthogonal constitute;

The condenser lens that on the optical axis of monitoring light beam light path, sets gradually, optical attenuator and optoelectronic induction device, described optoelectronic induction device is positioned at the rear focus place of described condenser lens; Wherein, the optical axis of described monitoring light beam light path is vertical with the optical axis of the emergent light light path of described laser instrument, and described monitoring light beam is for being collected by described microcobjective successively by the light of testing sample reflection and described astigmatism processor carries out the reflection ray that obtained by described Amici prism beam split again behind the astigmatism;

And while and described three-dimensional manometer scanning platform and optoelectronic induction device homogeneous phase computing machine even.

5. the axial drift compensation device of the sample based on astigmatism as claimed in claim 4 is characterized in that, in the described astigmatism processor, the angle of the first cylindrical mirror xsect and surface level is 45 °, and the angle of the second cylindrical mirror xsect and surface level is 135 °.

6. as claim 4 or the axial drift compensation device of 5 described samples, it is characterized in that in the described astigmatism processor, two cylindrical mirror focal lengths are 150mm based on astigmatism.

7. the axial drift compensation device of the sample based on astigmatism as claimed in claim 4 is characterized in that described optoelectronic induction device is high-speed charge coupled device or 4 quadrant detector.

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