CN116359549A

CN116359549A - Scanning photocurrent microscope and measuring method

Info

Publication number: CN116359549A
Application number: CN202310508755.1A
Authority: CN
Inventors: 冯海凤
Original assignee: Suzhou Scale Quantum Technology Co ltd
Current assignee: Suzhou Scale Quantum Technology Co ltd
Priority date: 2023-05-08
Filing date: 2023-05-08
Publication date: 2023-06-30

Abstract

The invention relates to a scanning photocurrent microscope and a measuring method, wherein the microscope comprises a sample placing table, a scanning mechanism, a probe position sensing mechanism, a light source, a light power meter and a camera; the scanning mechanism comprises a probe and a scanning head, the scanning head is connected with the probe, and the scanning head is provided with a piezoelectric tube; the probe position sensing mechanism comprises a laser emitter and an optical displacement sensor; the light source is positioned above the sample placing table, and the light emitted by the light source irradiates the sample from top to bottom; the surface morphology data, the surface current data and the surface photocurrent data of the sample can be measured, the light source illumination mode from top to bottom can be suitable for the opaque sample, and the light power of the sample surface is calibrated in the test process, so that quantitative photocurrent characterization is realized; the multifunctional and universal application system has the advantages of multifunction and high universality, and improves application scene applicability.

Description

Scanning photocurrent microscope and measuring method

Technical Field

The invention belongs to the field of atomic force microscopes, and particularly relates to a scanning photocurrent microscope and a measuring method.

Background

The atomic force microscope is a nanoscale high-resolution scanning probe microscope and can image the surface morphology of a material. Currently, atomic force microscopes have a mode of applying illumination radiation to a sample, but typically employ a light source that irradiates light from the bottom of the sample upwards. However, the bottom-up illumination of the light source requires that the light source be able to pass from the lower surface to the upper surface, and thus is only suitable for light-transmitting samples, and sample applicability is limited. Meanwhile, the light source irradiates from bottom to top, so that accurate irradiation intensity is difficult to obtain, and quantitative measurement cannot be performed on photoelectric response of the surface of a measured sample.

Disclosure of Invention

The invention aims to at least solve one of the technical problems in the prior art, and provides a scanning photocurrent microscope and a measuring method, which can finish the measurement of surface morphology data, surface current data and surface photocurrent data of a sample and have the advantages of multifunction and high universality.

Embodiments of a first aspect of the present invention provide a scanning photocurrent microscope and a measurement method, including:

the sample placing table is used for placing a sample to be tested;

the scanning mechanism comprises a probe and a scanning head, the scanning head is connected with the probe and used for driving the probe to move, the scanning head is provided with a piezoelectric tube, and the piezoelectric tube is used for applying bias voltage between the probe and a sample;

a probe position sensing mechanism including a laser emitter for emitting laser light to the probe and an optical displacement sensor for determining a position of a tip of the probe from the laser light reflected by the probe;

the light source is positioned above the sample placing table, and light emitted by the light source irradiates the sample from top to bottom;

the optical power meter is arranged on the sample placing table and is used for measuring the optical power of the surface of the sample;

and the camera is used for shooting images of the sample and the probe.

According to some embodiments of the first aspect of the invention, the sample placement stage comprises a table top and a three-dimensional movement mechanism connected to the table top for driving the table top to move in three dimensions.

According to some embodiments of the first aspect of the invention, the tip of the probe is tetrahedral in shape.

According to some embodiments of the first aspect of the invention, the tip of the probe is disposed obliquely with respect to the cantilever beam of the probe.

According to some embodiments of the first aspect of the invention, a most distal dimension of the probe is less than 10 nanometers.

According to some embodiments of the first aspect of the invention, the light source is a xenon lamp; the spectral range of the xenon lamp includes near ultraviolet to near infrared bands.

According to some embodiments of the first aspect of the invention, a filter is disposed between the xenon lamp and the sample placement stage.

An embodiment of the second aspect of the invention provides a measurement method employing a scanning photocurrent microscope as described in the first aspect of the invention; the measuring method comprises the following steps:

adjusting the positions of the laser transmitter and the optical displacement sensor;

adjusting the positions of an optical power meter and a probe so as to enable the heights of the optical power meter and the probe to be consistent, starting a light source and measuring a first optical power value on the surface of a sample through the optical power meter;

the positions of the sample and the probe are regulated so as to enable the heights of the surface of the sample and the probe to be consistent, a light source is started, and a second light power value of the surface of the sample is obtained through measurement of the light power meter, wherein the second light power value is equal to the first light power value;

under the condition that the light source is turned off, applying bias voltage between the probe and the sample through the piezoelectric tube, performing contact scanning on the sample through the probe to obtain surface morphology data of the sample, and obtaining surface current data of the sample according to current between the probe and the sample;

and under the condition that the light source is started, applying bias voltage between the probe and the sample through the piezoelectric tube, performing contact scanning on the sample through the probe, measuring to obtain a third light power value of the surface of the sample through the light power meter, and obtaining surface photocurrent data of the sample according to the third light power value.

According to some embodiments of the second aspect of the present invention, the adjusting the positions of the optical power meter and the probe so that the heights of the optical power meter and the probe are uniform includes:

moving the sample placement stage to move the optical power meter to a position directly below the probe;

focusing a camera to the cantilever beam of the probe, and moving the sample placing table until the optical power meter and the probe are simultaneously present in the field of view of the camera, so that the heights of the optical power meter and the probe are consistent.

According to some embodiments of the second invention, the adjusting the positions of the sample and the probe so that the surface of the sample and the height of the probe are uniform comprises:

moving the sample placement stage to move a sample directly below the probe;

focusing a camera to the position of the tip of the probe, and moving the sample placing table until the surface of the sample and the probe are simultaneously present in the field of view of the camera, so that the surface of the sample and the height of the probe are consistent.

The beneficial effects of the invention include: the surface appearance data, the surface current data and the surface photocurrent data of the sample can be measured; the illumination mode of the xenon lamp from top to bottom can be suitable for opaque samples, and the light power of the sample surface is allowed to be calibrated in the test process, so that quantitative photocurrent characterization is realized; the multifunctional and universal application system has the advantages of multifunction and high universality, and improves application scene applicability.

Further, additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

FIG. 1 is a schematic diagram of a scanning photocurrent microscope according to an embodiment of the present invention;

FIG. 2 is a top view of a scanning photocurrent microscope provided in an embodiment of the present invention;

fig. 3 is a step diagram of a measurement method according to an embodiment of the present invention.

Detailed Description

The conception, specific structure, and technical effects produced by the present invention will be clearly and completely described below with reference to the embodiments and the drawings to fully understand the objects, aspects, and effects of the present invention. It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other.

It should be noted that, unless otherwise specified, when a feature is referred to as being "fixed" or "connected" to another feature, it may be directly or indirectly fixed or connected to the other feature. Further, the descriptions of the upper, lower, left, right, top, bottom, etc. used in the present invention are merely with respect to the mutual positional relationship of the respective constituent elements of the present invention in the drawings.

Furthermore, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in the description presented herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any combination of one or more of the associated listed items.

It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element of the same type from another. For example, a first element could also be termed a second element, and, similarly, a second element could also be termed a first element, without departing from the scope of the present disclosure.

Referring to fig. 1 and 2, in some embodiments, a scanning photocurrent microscope according to the present invention includes: a sample placement stage 4, a scanning mechanism, a probe position sensing mechanism, a light source 9, an optical power meter 5 and a camera 7.

For the sample placement stage 4, the sample placement stage 4 is used for placing a sample 6 to be measured. Sample 6 is placed in sample 6 of sample placement platform 4 and places the region, and sample 6 of sample placement platform 4 places the region and can be provided with clip etc. sample 6 is fixed through structure such as clip, avoids sample 6 skew and influence measurement accuracy in the measurement process.

The sample placement stage 4 includes a stage surface and a three-dimensional moving mechanism. The sample 6 placement area is provided on the upper surface of the tabletop. The three-dimensional moving mechanism is connected with the table top and drives the table top to move in the three-dimensional direction.

The three-dimensional moving mechanism comprises an X-axis sliding table, a Y-axis sliding table and a Z-axis sliding table, wherein the X-axis sliding table drives the table top to reciprocate along the X-axis direction, the Y-axis sliding table drives the table top to reciprocate along the Y-axis direction, and the Z-axis sliding table drives the table top to reciprocate along the Z-axis direction; the table top can move in the three-dimensional direction through the X-axis sliding table, the Y-axis sliding table and the Z-axis sliding table, so that the table top can move more flexibly. The probe 3 can scan the surface of the sample 6 comprehensively and carefully, so that more comprehensive and more accurate surface morphology data, surface current data and surface photocurrent data can be obtained.

For the scanning mechanism, the scanning mechanism includes a probe 3 and a scanning head, which is connected to the probe 3.

The probe 3 includes a tip 31 portion and a cantilever beam 32 portion. The tip 31 of the probe 3 has a tetrahedral shape. The tip 31 of the probe 3 is arranged obliquely with respect to the cantilever beam 32 of the probe 3. The most distal dimension of the probe 3 is less than 10 nanometers.

The size of the most tip of the probe 3 is smaller than 10 nanometers, so that the light can be effectively ensured to pass, and the influence of the probe 3 on the light irradiated to the surface of the sample 6 by the xenon lamp is reduced as much as possible; so that the light emitted from the xenon lamp can be irradiated to the surface of the sample 6 through the minute probe 3.

The microscope is used for researching the surface structure and the property of a substance by detecting extremely weak interatomic interaction force between the surface of a sample 6 to be detected and a miniature force sensitive element. A pair of cantilever beams 32 extremely sensitive to weak forces are fixed at one end and a tiny needle tip 31 at the other end is brought close to the sample 6. The tiny needle tip 31 will then interact with the sample 6 and the force will cause the cantilever beam 32 to deform or change state of motion. When the sample 6 is scanned, the sensor is used to detect the deformation or the change of the motion state of the cantilever beam 32, so that the acting force distribution information can be obtained, and the surface topography structure information of the sample 6 can be obtained with the nanometer resolution.

The scanning head drives the probe 3 to move, and the scanning head is provided with a piezoelectric tube 2, and the piezoelectric tube 2 is used for applying bias voltage between the probe 3 and the sample 6.

Specifically, the piezoelectric tube 2 is a piezoelectric ceramic tube. The piezoelectric ceramic is an information functional ceramic material capable of mutually converting mechanical energy and electric energy, namely a piezoelectric effect, and has dielectric property, elasticity and the like besides piezoelectric property. The piezoelectric ceramic is manufactured by using the piezoelectric effect which is the bound electric charges with opposite signs on the surfaces of two ends of the material and is sensitive because the material is polarized by causing the relative displacement of the positive and negative electric charge centers inside the material under the action of mechanical stress.

Piezoelectric ceramics are a class of electronic ceramic materials with piezoelectric properties. After the piezoelectric ceramic is sintered and the end face is coated with an electrode, the piezoelectric ceramic is subjected to polarization treatment under a strong direct current field, so that respective polarization vectors which are originally in disordered orientation are preferentially oriented along the direction of the electric field. After the electric field is canceled, the piezoelectric ceramic subjected to polarization treatment can keep certain macroscopic residual polarization intensity, so that the ceramic has certain piezoelectric properties.

A stable bias voltage is applied between the probe 3 and the sample 6 through the piezoelectric ceramic tube, so that the formed surface current diagram of the sample 6 is more accurate.

For the probe position sensing mechanism, the probe position sensing mechanism includes a laser emitter 1 for emitting laser light to the probe 3 and an optical displacement sensor 8 for determining the position of the tip 31 of the probe 3 from the laser light reflected by the probe 3.

Specifically, the laser emitter 1 can emit laser light having a wavelength of 635 nm. The optical displacement sensor 8 employs a four-quadrant position sensitive detector.

One end of a cantilever beam 32 extremely sensitive to weak force is fixed, the other end is provided with a tiny needle tip 31, the needle tip 31 is lightly contacted with the surface of the sample 6, and the cantilever beam 32 with the needle tip 31 moves in a fluctuation manner in the direction perpendicular to the surface of the sample 6 by controlling the constant force during scanning due to extremely weak repulsive force between the atoms at the tip end of the needle tip 31 and the atoms on the surface of the sample 6. By using an optical detection method, the position change of the cantilever beam 32 corresponding to each scanning point can be measured, so that the information of the surface morphology of the sample 6 can be obtained.

The laser beam emitted from the laser is focused on the back surface of the cantilever beam 32 through an optical system, and reflected from the cantilever beam 32 to the optical displacement sensor 8 constituted by a photodiode. When the sample 6 is scanned, due to the interaction force between the atoms on the surface of the sample 6 and the atoms at the tip of the needle tip 31, the cantilever beam 32 and the needle tip 31 bend and undulate along with the surface topography of the sample 6, and the reflected light beam also deflects along with the bending and undulation, so that the position change of the needle tip 31 can be determined by detecting the change of the light spot position through the optical displacement sensor 8, and further the surface topography data of the sample 6 can be obtained.

In the whole process of system detection imaging, the distance between the probe 3 and the sample 6 is always kept at the nanometer level, and the information on the surface of the sample 6 cannot be obtained when the distance is too large, so that the probe 3 and the sample 6 to be detected can be damaged when the distance is too small. The strength of the interaction between the probe 3 and the sample 6 can be obtained by the probe 3 in the working process through the feedback loop, so that the bias voltage applied to the sample 6-scanning mechanism in the vertical direction is changed, the sample 6 is enabled to stretch and retract, the distance between the probe 3 and the sample 6 to be measured is regulated, and the strength of the interaction between the probe 3 and the sample 6 is controlled in turn, so that the feedback control is realized.

For the light source 9, the light source 9 is a xenon lamp; the xenon lamp is positioned above the sample placing table 4, and light emitted by the xenon lamp irradiates the sample 6 from top to bottom. In this embodiment, the light from the xenon lamp is directed to sample 6 from top to bottom. If the light emitted from the xenon lamp irradiates the sample 6 from bottom to top, the light source 9 needs to be able to transmit from the lower surface of the sample 6 to the upper surface of the sample 6, and the light emitted from the xenon lamp irradiates the sample 6 from bottom to top only applies to the transparent sample 6. Compared with the mode that light emitted by the xenon lamp irradiates the sample 6 from bottom to top, the light emitted by the xenon lamp irradiates the sample 6 from top to bottom, so that the light-tight sample 6 can be suitable for application scenes, and the applicability of the application scenes is improved.

Specifically, the spectral range of xenon lamps includes the near ultraviolet to near infrared band. The wide spectrum range of the xenon lamp can enable the microscope to be suitable for measurement of more kinds of samples 6, and application scene applicability is improved.

A filter is provided between the xenon lamp and the sample placing stage 4; the filter plate clamp clamps and fixes the filter plate, and the filter plate can be stably fixed through the filter plate clamp, so that the vibration and the offset of the filter plate are avoided. Meanwhile, the filter is clamped by the filter clamp, so that the filter can be replaced conveniently.

On the other hand, the filter is placed by the filter automatic replacement mechanism, and the filter automatic replacement mechanism is provided with a plurality of accommodating grooves, each accommodating groove accommodates one filter, and the filters in each accommodating groove can filter light with different wavelengths. The holding tank still is equipped with the telescopic link, can release the wave filter in the holding tank outside the holding tank through the telescopic link, also can withdraw the wave filter to the holding tank through the telescopic link.

The filter plate can realize the function of passing light with specific wavelength. For example, when light of a near ultraviolet band needs to be screened is irradiated onto the sample 6, a filter sheet which can only pass through the light of the near ultraviolet band is fixed on a filter sheet clamping sheet, the light of the xenon lamp can be filtered through the filter sheet, so that the near ultraviolet band in the light of the xenon lamp is passed through the filter sheet, the rest bands in the light of the xenon lamp are filtered by the filter sheet, and the light of the near ultraviolet band passing through the filter sheet is irradiated onto the sample 6, so that the filtering function is realized.

Automatically adjusting the light intensity of the xenon lamp through a controller, automatically replacing filter plates for filtering light with different wavelengths through a filter plate automatic replacement mechanism, measuring the light power of the surface of a sample 6 under different light intensities and wavelengths through a light power meter 5, and determining the current light intensity and wavelength as a candidate scheme when the measured light power is larger than a preset threshold value; the measurement is more automatic and convenient by automatically configuring the light intensity and the wavelength of the combined xenon lamp.

For the optical power meter 5, the optical power meter 5 is provided at the sample placement stage 4, and the optical power meter 5 is used to measure the optical power of the surface of the sample 6. The optical power meter 5 is specifically a diode optical power meter 5, and adopts a mirror design.

For the camera 7, the camera 7 is used to take images of the sample 6 and the probe 3. The camera 7, in particular an electronic camera 7, is capable of taking images of the sample 6 and the probe 3 to magnify and observe the position of the sample 6 and the needle tip 31.

The scanning photocurrent microscope can be used to measure the surface topography data, the surface current data, and the surface photocurrent data of the sample 6.

The measurement method with reference to fig. 3 is specifically as follows:

step S100, adjusting the positions of the laser transmitter 1 and the optical displacement sensor 8;

step S200, adjusting the positions of the optical power meter 5 and the probe 3 so that the heights of the optical power meter 5 and the probe 3 are consistent, starting a xenon lamp and measuring a first optical power value on the surface of the sample 6 through the optical power meter 5;

step S300, adjusting the positions of the sample 6 and the probe 3 so as to enable the heights of the surface of the sample 6 and the probe 3 to be consistent, starting a xenon lamp, and measuring by an optical power meter 5 to obtain a second optical power value of the surface of the sample 6;

step S400, under the condition that the xenon lamp is turned off, applying bias voltage between the probe 3 and the sample 6 through the piezoelectric tube 2, and performing contact scanning on the sample 6 through the probe 3 to obtain surface morphology data of the sample 6;

step S500, according to the current between the probe 3 and the sample 6, obtaining the surface current data of the sample 6;

in step S600, when the xenon lamp is turned on, a bias voltage is applied between the probe 3 and the sample 6 through the piezoelectric tube 2, the sample 6 is scanned by the probe 3 in a contact manner, a third optical power value of the surface of the sample 6 is measured by the optical power meter 5, and surface photocurrent data of the sample 6 is obtained according to the third optical power value.

For step S100, the positions of the laser emitter 1 and the optical displacement sensor 8 are adjusted; adjusting the position of the laser transmitter 1 so that the laser light emitted from the laser transmitter 1 can be irradiated on the cantilever beam 32; adjusting the position of the optical displacement sensor 8 so that the laser light reflected by the cantilever beam 32 can be sensed by the optical displacement sensor 8; and finishing the initialization step of the measurement.

For step S200, in which, for adjusting the positions of the sample 6 and the probe 3 so that the surface of the sample 6 and the height of the probe 3 coincide, specifically: the table top of the sample placing table 4 is moved by the three-dimensional moving mechanism, so that the optical power meter 5 is moved to the position right below the probe 3; the camera 7 is focused to the position of the cantilever beam 32 of the probe 3 and the sample placement stage 4 is moved until the optical power meter 5 and the probe 3 are simultaneously present in the field of view of the camera 7, at which point the heights of the optical power meter 5 and the probe 3 coincide.

And starting the xenon lamp, measuring the optical power of the surface of the sample 6 by the optical power meter 5 after the xenon lamp is stable under the condition that the heights of the optical power meter 5 and the probe 3 are consistent, obtaining a first optical power value, and taking the first optical power value as a calibrated optical power value.

For step S300, in which, for adjusting the positions of the sample 6 and the probe 3 so that the surface of the sample 6 and the height of the probe 3 coincide, specifically: moving the table top of the sample placing table 4 through the three-dimensional moving mechanism to enable the sample 6 to move to the position right below the probe 3; the camera 7 is focused to the position of the tip 31 of the probe 3 and the sample placement stage 4 is moved until the surface of the sample 6 and the probe 3 are simultaneously present in the field of view of the camera 7 and the surface of the sample 6 and the probe 3 are in agreement.

And starting the xenon lamp, and measuring the optical power of the surface of the sample 6 under the condition that the surface of the sample 6 is consistent with the height of the probe 3 through the optical power meter 5 after the xenon lamp is stable, so as to obtain a second optical power value. And if the second optical power value is equal to the first optical power value, passing. Otherwise, the intensity of the xenon lamp is regulated until the second optical power value is equal to the calibrated first optical power value.

The top-down illumination mode of the xenon lamp allows the calibration of the optical power of the surface of the sample 6 in the test process, so that quantitative photocurrent characterization is realized.

For step S400, in the case of turning off the xenon lamp, a bias voltage is applied between the probe 3 and the sample 6 through the piezoelectric tube 2, and the sample 6 is scanned by contact through the probe 3; the tip 31 of the probe 3 is in proximity to the sample 6. At this point the needle tip 31 will interact with the sample 6 and the force will cause the movement of the cantilever beam 32 to change; the movement state of the cantilever beam 32 is changed by irradiating the cantilever beam 32 with laser, so that the light reflected by the cantilever beam 32 to the optical displacement sensor 8 moves, and the movement information of the reflected light is recorded by the optical displacement sensor 8. The motion information of the reflected light is analyzed to obtain force distribution information, thereby obtaining surface topography data of the sample 6 with a resolution of nanometer scale.

It will be appreciated that the surface topography data may be represented in the form of text, numbers, or charts.

For step S500, after stable surface topography data is obtained, a bias voltage is applied between the probe 3 and the sample 6 through the piezoelectric tube 2, a current between the probe 3 and the sample 6 can be detected by the current sensor, and surface current data of the sample 6 can be obtained from the current between the probe 3 and the sample 6.

The surface current data of sample 6 corresponds to the surface topography data of sample 6. That is, the current value at the x position in the surface current data corresponds to the x position of the surface topography data, and the current value at the y position in the surface current data corresponds to the y position of the surface topography data.

It will be appreciated that the surface current data may be represented in the form of text, numbers, or charts.

In step S600, when the piezoelectric tube 2 is turned off and turned on, a bias voltage is applied between the probe 3 and the sample 6, the sample 6 is scanned by the probe 3 in a contact manner, a photocurrent is generated on the surface of the sample 6 due to the illumination of the xenon lamp and the bias voltage, the photocurrent on the surface of the sample 6 can be detected by the photocurrent sensor, and the surface photocurrent data of the sample 6 can be obtained from the photocurrent on the surface of the sample 6.

The surface photocurrent data of the sample 6 corresponds to the surface topography data of the sample 6. That is, the photoelectric value at the x position in the surface photocurrent data corresponds to the x position in the surface topography data, and the photoelectric value at the y position in the surface photocurrent data corresponds to the y position in the surface topography data.

It will be appreciated that the surface photocurrent data may be represented in the form of text, numbers, or charts.

By the scanning photocurrent microscope and the measuring method, the surface morphology data, the surface current data and the surface photocurrent data of the sample 6 can be measured, the multifunctional scanning photocurrent microscope and the measuring method have the advantage of multifunction, and the applicability of application scenes is improved.

The present invention is not limited to the above embodiments, but can be modified, equivalent, improved, etc. by the same means to achieve the technical effects of the present invention, which are included in the spirit and principle of the present disclosure. Are intended to fall within the scope of the present invention. Various modifications and variations are possible in the technical solution and/or in the embodiments within the scope of the invention.

Claims

1. A scanning photocurrent microscope is characterized by comprising

The sample placing table is used for placing a sample to be tested;

and the camera is used for shooting images of the sample and the probe.

2. A scanning photocurrent microscope according to claim 1 wherein the sample placement stage comprises a tabletop and a three-dimensional movement mechanism coupled to the tabletop for driving the tabletop to move in three dimensions.

3. A scanning photocurrent microscope as claimed in claim 1 wherein the tip of the probe is tetrahedrally shaped.

4. A scanning photocurrent microscope as claimed in claim 1, wherein the tip of the probe is disposed obliquely to the cantilever of the probe.

5. A scanning photocurrent microscope as claimed in claim 1, wherein the most tip of the probe is less than 10 nm in size.

6. A scanning photocurrent microscope as claimed in claim 1 wherein the light source is a xenon lamp; the spectral range of the xenon lamp includes near ultraviolet to near infrared bands.

7. The scanning photocurrent microscope of claim 6, wherein a filter is disposed between the xenon lamp and the sample placement stage.

8. A measuring method, characterized in that a scanning photocurrent microscope as claimed in any of claims 1 to 7 is used; the measuring method comprises the following steps:

9. A method of measuring according to claim 8, wherein said adjusting the positions of the optical power meter and the probe so that the heights of the optical power meter and the probe coincide comprises:

10. A method of measuring according to claim 8, wherein said adjusting the positions of the sample and the probe so that the surface of the sample and the height of the probe coincide comprises:

moving the sample placement stage to move a sample directly below the probe;