JP2020159951A - Measuring method and device - Google Patents

Abstract

To provide a measuring method and device with which it is possible to measure the thickness of a thick measurement object and detect a difference in thickness with high accuracy, irrespective of the wavelength resolution of the measuring device.SOLUTION: The measuring method comprises the steps of: simulating the interference light obtained by irradiating a measurement object (9) with measurement light and calculating the light intensity distribution of interference light for each thickness (TH) of the measurement object; acquiring the data for thickness computation that includes the characteristic of the envelope obtained by changing the sampling interval of the light intensity distribution of interference light calculated for each thickness of the measurement object; acquiring measured data of light intensity distribution of interference light obtained by irradiating the measurement object with measurement light; and comparing the data for thickness computation obtained by simulation with the characteristic of the envelope obtained by changing the sampling interval in the measured data and calculating the thickness of the measurement object.SELECTED DRAWING: Figure 1

Description

The present invention relates to a measuring method and an apparatus, and relates to a measuring method and an apparatus for measuring the thickness of an object to be measured.

As a method of measuring the thickness of an object (film) to be measured, the thickness is measured by irradiating the film with white light and dispersing the interference light between the reflected light from the front surface of the film and the reflected light from the back surface of the film. There are known ways to do this. Patent Document 1 discloses that adjacent peak points are extracted from the intensity distribution of the interference light after spectroscopy with respect to the wavelength, and the thickness is calculated from the wave number difference between the peak points.

Japanese Unexamined Patent Publication No. 2010-121977

The wavelength is λ, the wave number is k, the refractive index of the object to be measured with respect to light of wavelength λ is n, the physical thickness of the object to be measured is TH, and the wave number difference between peak points in the intensity distribution with respect to the wavelength of the interference light is δk. Then, the optical thickness d (d = n × TH) of the object to be measured is represented by the following equation (1).

d = 1 / (2δk), k = 1 / λ ... (1)
From the equation (1), it can be seen that the value of the wavenumber difference δk becomes smaller as the thickness d of the object to be measured becomes thicker.

Assuming that the central wavelength of the interference light is λc, the relationship between the thickness d of the object to be measured and the difference δλ of the wavelengths required for decomposition is expressed by the following equation (2).

δλ≈λc ² / (2d) / 4 ... (2)
From the equation (2), it can be seen that the thicker the thickness d of the object to be measured, the smaller the difference δλ of the wavelengths required for decomposition and the higher the wavelength resolution λc / δλ required for measuring the thickness. For example, when λc = 800 nm, the difference in wavelength δλ required for decomposition when measuring a measurement object having a thickness d of 1 mm is about 0.08 nm, and when measuring an object having a thickness d of 2 mm. The wavelength difference δλ required for decomposition is about 0.04 nm. As described above, when measuring the thickness of a thick object to be measured (in one example, the thickness d is 1 mm or more), high wavelength resolution is required.

However, in general, the wavelength resolution λc / δλ of a spectroscope is limited by the performance of optical components (for example, diffraction gratings) and detectors (for example, CCD (Charge Coupled Device)) used in the spectroscope. For example, assuming that the number of grooves N per unit length of the diffraction grating, the size L, and the order of the diffracted light are m, the difference in resolution δλ is expressed by the following equation (3).

δλ = λc / mNL… (3)
In the formula (3), if N = 1000 lines / mm, L = 10 mm, m = 1, λc = 800 nm, then δλ = 0.08 nm. The value of δλ obtained by the equation (3) is only a theoretical value, and when the diffraction grating is actually incorporated in the spectroscope and used, the size of the light source and the slit and other optical components (for example, a lens) , Mirror, etc.) Since the spectral line is widened due to aberrations, etc., the actual δλ becomes larger.

In order to increase the wavelength resolution λc / δλ, it is conceivable to use a diffraction grating having a shorter groove interval or to reduce the pixel size of the detector. However, there is a limit to improving the accuracy of the detector, and there is a problem that the cost is increased.

Further, when measuring the change (difference) in the thickness d of the object to be measured, the detectable difference δd in the thickness d is determined by the change in the wavenumber difference δk between the peak points from the equation (1). The smaller the difference in thickness δd, the smaller the change in wavenumber difference δk between peak points.

Patent Document 1 discloses that the maximum point of the light intensity distribution with respect to the wave number is extracted, and the displacement amount of the film is determined based on the phase of the frequency component corresponding to the spatial frequency of the maximum point. However, even when phase is used as in Patent Document 1, measurement is difficult when the phase difference is small due to the limitation of wavelength resolution.

The present invention has been made in view of such circumstances, and it is possible to measure the thickness of a thick object to be measured regardless of the wavelength resolution of the measuring device, and to detect the difference in thickness with high accuracy. It is an object of the present invention to provide a possible measuring method and apparatus.

In order to solve the above problems, in the measurement method according to the first aspect of the present invention, the interference light obtained by irradiating the measurement object with the measurement light is simulated, and the interference light is generated for each thickness of the measurement object. A step of calculating the light intensity distribution, a step of acquiring data for thickness calculation including the characteristics of the envelope obtained by changing the sampling interval of the light intensity distribution of the interference light calculated for each thickness of the object to be measured, and It is obtained by changing the sampling interval in the step of acquiring the measured data of the light intensity distribution of the interference light obtained by irradiating the measurement object with the measurement light, the thickness calculation data obtained by the simulation, and the measured data. It is provided with a step of calculating the thickness of the object to be measured by comparing it with the characteristics of the envelope.

The measurement method according to the second aspect of the present invention further includes, in the first aspect, a step of calibrating the characteristics of the envelope obtained by simulation using the measurement results of a standard having a known thickness.

In the measurement method according to the third aspect of the present invention, in the first or second aspect, an estimated value of the thickness of the object to be measured is calculated based on the measured data, and the simulation for each thickness is performed based on the estimated value. A step of selecting the thickness calculation data to be used for calculating the thickness of the object to be measured is further provided from the resulting thickness calculation data.

The measuring device according to the fourth aspect of the present invention simulates a light source that emits measurement light and interference light obtained by irradiating the measurement object with measurement light, and obtains interference light for each thickness of the measurement object. Thickness calculation to acquire data for thickness calculation including the characteristics of the envelope obtained by changing the sampling interval of the light intensity distribution of the interference light calculated for each thickness of the object to be measured and the simulation unit that calculates the light intensity distribution. Data acquisition unit, actual measurement data acquisition unit that acquires actual measurement data of the light intensity distribution of interference light obtained by irradiating the measurement object with measurement light, thickness calculation data obtained by simulation, and actual measurement data. It is provided with a calculation unit for calculating the thickness of the object to be measured by comparing it with the characteristics of the envelope obtained by changing the sampling interval.

According to the present invention, the thickness of the object to be measured is obtained by using the characteristics of the envelope obtained from the simulation result of the light intensity distribution and the measured data of the object to be measured, regardless of the wavelength resolution of the measuring device. It becomes possible to obtain the thickness of the object to be measured with high accuracy.

FIG. 1 is a schematic view of a measuring device according to an embodiment of the present invention. FIG. 2 is an enlarged view of the sensor head. FIG. 3 is a block diagram showing the configuration of the control device. FIG. 4 is a flowchart showing a simulation process in the measurement method according to the embodiment of the present invention. FIG. 5 is a diagram showing an example of a simulation result and an actual measurement result of a standard object. FIG. 6 is a table showing envelope data. FIG. 7 is a table showing the calibrated parameters. FIG. 8 is a flowchart showing a thickness calculation step in the measurement method according to the embodiment of the present invention. FIG. 9 is a graph for explaining a process of calculating an approximate value of the thickness of the object to be measured. FIG. 10 is a graph for explaining a process of calculating an approximate value of the thickness of the object to be measured. FIG. 11 is a graph for explaining a process of calculating an approximate value of the thickness of the object to be measured. FIG. 12 is a graph showing the calibrated simulation results used for calculating the thickness of the object to be measured. FIG. 13 is a graph showing the calibrated simulation result used for calculating the thickness of the object to be measured. FIG. 14 is a graph showing the calibrated simulation results used for calculating the thickness of the object to be measured. FIG. 15 is a graph for explaining the calculation of the thickness of the object to be measured. FIG. 16 is a graph for explaining the calculation of the thickness of the object to be measured.

Hereinafter, embodiments of the measurement method and the apparatus according to the present invention will be described with reference to the accompanying drawings.

[Measuring device configuration]
FIG. 1 is a schematic view of a measuring device 10 that measures (measures) the thickness TH of a measurement object 9 in a non-contact manner using the measurement light L. The distance D of the measurement object 9 is the distance from the measurement device 10 [end surface 19 (reference surface) described later in this embodiment] to the measurement object 9 (first surface 9a). Further, the thickness TH of the measurement object 9 is the distance (length) between the first surface 9a and the second surface 9b of the measurement object 9 in the present embodiment.

As shown in FIG. 1, the measuring device 10 includes a light source 12, a fiber circulator 13 (also referred to as an optical circulator), a sensor head 14, and optical fiber cables 15A, 15B, and 15C which are optical paths connecting these parts. A spectroscope 16, a detector 17, and a control device 18 are provided.

The light source 12 is a light source that emits white light as the measurement light L, and is, for example, a halogen lamp, a laser light source, an LED (Light Emitting Diode) light source, or the like. Here, the white light is light obtained by mixing visible light having a wavelength in the visible light region (wavelength of about 400 nm to about 720 nm), and for example, light of three colors (three primary colors) of red, green and blue is appropriate. The light may be mixed at various ratios. The light source 12 is connected to the fiber circulator 13 via an optical fiber cable 15A. The light source 12 emits (irradiates) the measurement light L to the fiber circulator 13 via the optical fiber cable 15A.

In the present embodiment, a white light source is used as the light source 12, but the present invention is not limited to this. As the light source 12, a light source capable of emitting measurement light having a constant spectral width can be used. Further, as the light source 12, for example, a wavelength sweep light source may be used. When a wavelength sweep light source is used, the spectroscope 16 can be omitted.

The fiber circulator 13 is connected to the light source 12 via the above-mentioned optical fiber cable 15A, is connected to the sensor head 14 via the optical fiber cable 15B, and is further connected to the spectroscope 16 and the detector 17 via the optical fiber cable 15C. Is connected to.

The fiber circulator 13 is, for example, a non-reciprocating and unidirectional device having three ports, and outputs the measurement light L input from the light source 12 to the optical fiber cable 15B via the optical fiber cable 15A. As a result, the measurement light L from the light source 12 is input to the sensor head 14 via the optical fiber cable 15B. Further, the fiber circulator 13 outputs the interference signal SG described later to the optical fiber cable 15C via the optical fiber cable 15B. As a result, the interference signal SG is input to the spectroscope 16 and the detector 17 via the optical fiber cable 15C.

FIG. 2 is an enlarged view of the sensor head 14. As shown in FIG. 2, the sensor head 14 is arranged at a position facing the first surface 9a of the measurement object 9. The connection structure of the optical fiber cable 15B to the sensor head 14 is not limited to the example shown in FIG. 2, and a known connection structure can be adopted.

The sensor head 14 emits the measurement light L input from the fiber circulator 13 via the optical fiber cable 15B toward the first surface 9a of the measurement object 9. As a result, a part of the measurement light L emitted from the sensor head 14 is reflected by the first surface 9a and is incident on the sensor head 14 as the first reflected light R1. Further, a part of the measurement light L transmitted from the first surface 9a through the measurement object 9 is reflected by the second surface 9b opposite to the first surface 9a, and is incident on the sensor head 14 as the second reflected light R2. .. Then, the first reflected light R1 and the second reflected light R2 are input from the sensor head 14 to the optical fiber cable 15B.

The end face 19 on the side connected to the sensor head 14 of the optical fiber cable 15B, that is, the end face 19 on the exit end side that emits the measurement light L to the sensor head 14, reflects a part of the measurement light L toward the fiber circulator 13. Acts as a reference plane. As a result, a part of the measurement light L is reflected by the end surface 19 (reference surface) toward the fiber circulator 13 to become the reference light R3. Therefore, in the optical fiber cable 15B, the first reflected light R1, the second reflected light R2, and the reference light R3 interfere with each other, and the interference signal SG (interference) between the first reflected light R1, the second reflected light R2, and the reference light R3. Light) is input to the fiber circulator 13.

The interference signal SG includes a first interference signal component sg1 which is an interference signal component of the first reflected light R1 and a reference light R3, and a second interference signal component sg2 which is an interference signal component of the second reflected light R2 and the reference light R3. And a third interference signal component sg3, which is an interference signal component of the first reflected light R1 and the second reflected light R2, are included. The interference signal SG also includes noise light RN generated by unnecessary reflection by a lens (not shown) in the sensor head 14. Then, the interference signal SG is input to the spectroscope 16 and the detector 17 via the fiber circulator 13 and the optical fiber cable 15C.

Returning to FIG. 1, the spectroscope 16 is a device that disperses the interference signal SG, and includes, for example, a diffraction grating (not shown). The diffraction grating emits the interference signal SG input (incident) from the fiber circulator 13 via the optical fiber cable 15C in different directions according to its wavelength.

As the detector 17, for example, a CCD (Charge Coupled Device) type or CMOS (Complementary Metal Oxide Semiconductor) type image sensor or a silicon photodiode is used. The interference light diffracted by the diffraction grating of the spectroscope 16 is incident on an imaging lens (not shown) and is imaged at different positions of the detector 17 according to its wavelength. The detector 17 converts and amplifies the interference signal (SG) dispersed by the diffraction grating of the spectroscope 16 into an electric signal and outputs it to the control device 18.

The control device 18 is, for example, an arithmetic processing device such as a personal computer or a workstation, and controls the operation of each part of the measuring device 10 such as the light source 12 and the detector 17. Further, the control device 18 analyzes (calculates) the thickness TH of the measurement object 9 by analyzing the interference signal SG input from the detector 17.

[Control device configuration]
FIG. 3 is a block diagram showing the configuration of the control device.

As shown in FIG. 3, the control device 18 according to the present embodiment is a device that controls each part of the measuring device 10 and processes the measurement result, and is a control unit 20, a signal processing unit 22, a storage unit 24, and a storage unit 24. The input / output unit 26 is included.

The control unit 20 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The control unit 20 receives an operation input from the operator via the input / output unit 26 and controls each unit of the measuring device 10. The control unit 20 controls the emission of the measurement light L by the light source 12, the output of the interference signal SG by the detector 17, and the like. Further, the control unit 20 performs a simulation described later and a calculation of the thickness TH of the measurement object 9. The control unit 20 is an example of a simulation unit, a thickness calculation data acquisition unit, an actual measurement data acquisition unit, and a calculation unit.

The input / output unit 26 is an operation member (for example, a keyboard, a pointing device, etc.) for receiving an operation input of an operator, and a display unit (for example, a liquid crystal display, etc.) for displaying the measurement result of the measurement object 9. ) And is included.

The signal processing unit 22 acquires the interference signal SG from the detector 17 and performs signal processing to obtain the light intensity distribution and the like.

The storage unit 24 is a storage device for storing data such as measurement results of the measurement object 9. As the storage unit 24, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), or the like can be used.

[Thickness measurement method]
Next, the measurement method according to the embodiment of the present invention will be described.

When the envelope detection is performed by changing the sampling interval for the measured data (light intensity distribution) of the measurement object 9, the envelope characteristics (group phase, for example, the envelope) according to the thickness TH of the measurement object 9. The amplitude, period, etc.) are different. Therefore, in the present embodiment, a simulation is performed in advance to calculate the envelope when the sampling interval M and the thickness TH of the measurement object 9 are changed. Then, the thickness TH of the measurement target 9 is obtained by using this simulation result and the actual measurement data of the measurement target 9.

FIG. 4 is a flowchart showing a simulation process in the measurement method according to the embodiment of the present invention.

First, the control unit 20 obtains the light intensity distribution obtained from the measurement object 9 having a thickness TH (TH = 1, ..., N) by simulation (step S10). Then, the control unit 20 performs envelope detection by changing the sampling interval Δ (Δ = 1, ..., M) with respect to the simulation result of the light intensity distribution, and changes the sampling interval Δ and the thickness TH. Get envelope data. By this simulation, the relationship between the thickness TH of the object 9 to be measured and the group phase obtained from the envelope can be obtained (step S12).

Next, the control unit 20 obtains the light intensity distribution (actual measurement result of the standard product) obtained by measuring the standard product having a thickness TH (TH = 1, ..., N) using the measuring device 10. The simulation results of steps S10 and S12 are calibrated (step S14). Here, the standard material (reference piece) is a member having a known thickness, and is, for example, a glass plate-shaped or film-shaped member.

FIG. 5 is a diagram showing an example of a simulation result and an actual measurement result of a standard object. The horizontal axis of each graph in FIG. 5 is the wavelength (μm), and the vertical axis is the amplitude (normalized value). FIG. 5 shows data of thickness N and sampling intervals of 0.04 nm, 0.06 nm, and 0.08 nm as examples of simulation results and actual measurement results.

In step S14, the control unit 20 compares the simulation result of each thickness TH (TH = 1, ..., N) with the measurement result of the standard object having the same thickness, performs a conversion that brings the two closer to each other, and calibrates the envelope. Find line data. In step S14, for example, the control unit 20 brings the approximate curve of the simulation result of each thickness TH (TH = 1, ..., N) closer to or matches the approximate curve of the measurement result of the standard object having the same thickness. Then, the control unit 20 obtains the calibrated parameter from the calibrated envelope data. Here, as parameters, for example, the envelope amplitude, the point at which the maximum value and the minimum value are taken, the inflection point, and the like are obtained.

FIG. 6 is a table showing envelope data, and FIG. 7 is a table showing calibrated parameters.

In steps S10 and S12, envelope data (envelopes 11, ..., MN) for each sampling interval Δ (Δ = 1, ..., M) and thickness TH (TH = 1, ..., N) are obtained. Then, in step S14, the sampling interval Δ (Δ = 1, ..., M) and the parameters (parameters 11, ..., MN) for each thickness TH (TH = 1, ..., N) are obtained.

The calibrated simulation result (including the calibrated parameter) is stored in the storage unit 24 (step S16). The calibrated simulation result may include calibrated envelope data. Here, the calibrated simulation result is an example of the thickness calculation data.

FIG. 8 is a flowchart showing a thickness calculation step in the measurement method according to the embodiment of the present invention.

First, the control unit 20 acquires the light intensity distribution (actual measurement data of the measurement object 9) obtained by measuring the measurement object 9 using the measurement device 10 (step S20). Then, the control unit 20 calculates the approximate value TH ₀ of the thickness of the measurement object 9 (step S22).

9 to 11 are graphs for explaining the process of calculating the approximate value of the thickness of the object to be measured. FIG. 9 shows the light intensity distribution obtained from the measurement object 9, and FIG. 10 shows the horizontal axis of FIG. 9 converted into a wave number. FIG. 11 shows an FFT (Fast Fourier Transform) applied to the relationship between the wave number and the amplitude of FIG.

In the examples of FIGS. 9 to 11, the wavelength used is 0.80 μm to 0.85 μm, and the wave number range is 0.073529. In FIG. 11, since the peak appears at the position of 291.205 Hz, the wave number difference δk is δk = 0.073529 / 291.205 = 2.52501 × 10 ^-4 (μm ^-1 ). As a result, the approximate thickness TH ₀ becomes TH ₀ = 1 / (2δk) = 1980.194 (μm).

Next, the control unit 20 selects the calibrated simulation result to be used for the calculation of the thickness TH based on the approximate value TH ₀ of the thickness TH of the measurement object 9 (step S24). In step S24, a calibrated simulation result corresponding to a thickness close to the estimated thickness TH ₀ obtained in step S22 (for example, TH ₀ ± ΔD) is selected. In the present embodiment, it is assumed that ΔD is about 0.10 μm and the calibrated simulation result when the thickness TH is 1980.00 μm to 1980.30 μm is selected.

12 to 14 are graphs showing the calibrated simulation results used for calculating the thickness of the object to be measured.

12 to 14 show the calibrated simulation results when the thickness TH is from 1980.00 μm to 1980.30 μm in increments of 0.05 μm. The solid lines in FIGS. 12 to 14 are actual measurement data. The sampling intervals Δ in FIGS. 12 to 14 are 0.04 nm, 0.06 nm, and 0.08 nm, respectively.

Next, the control unit 20 compares the calibrated simulation result with the characteristic of the envelope obtained by changing the sampling interval Δ in the measured data (step S26), and based on the comparison result, the measurement object 9 The thickness TH of the above is calculated (step S28). The result of this calculation is stored in the storage unit 24.

15 and 16 are graphs for explaining the calculation of the thickness of the object to be measured. FIG. 15 compares the calibrated simulation results with a thickness of 1980.00 μm to 1980.05 μm in 0.01 μm increments with the measured data, and FIG. 16 shows 0.01 μm with a thickness of 1980.020 μm to 1980.025 μm. This is a comparison between the calibrated simulation results in increments and the measured data. The sampling interval Δ in FIGS. 15 and 16 is 0.08 nm.

As shown in FIG. 16, in this example, the measured data is in good agreement with the calibrated simulation result of 1980.23 μm. As a result, the thickness TH of the object 9 to be measured is determined to be 1980.23 μm. According to this example, it can be seen that the thickness on the order of 0.01 μm can be calculated for the measurement object 9 having a thickness of about 2 mm by using the characteristic of the envelope for each sampling interval Δ.

In steps S24 and S26, if there is no parameter corresponding to the approximate value TH ₀ or the thickness TH corresponding to the measured data, it may be obtained by interpolation (for example, linear interpolation) from the calibrated parameter shown in FIG. Good. For example, the data shown in FIG. 16 having a thickness of 1980.020 μm to 1980.025 μm in 0.01 μm increments may be obtained by interpolation from the calibrated simulation results (parameters) of 1980.0 μm and 1980.1 μm.

According to the present embodiment, the wavelength of the measuring device 10 is obtained by obtaining the thickness TH of the measuring object 9 by using the characteristics of the envelope obtained from the simulation result of the light intensity distribution and the measured data of the measuring object 9. Regardless of the resolution, the thickness TH of the measurement object 9 can be obtained with high accuracy.

In the present embodiment, the simulation result is calibrated, but the characteristic of the envelope (relationship between the thickness TH of the measurement object 9 and the group phase) acquired in step S12 is obtained by omitting the calibration of the simulation result. You may use it to calculate the thickness TH. That is, any of the simulation results before and after calibration may be used as the thickness calculation data.

Further, in the present embodiment, the calibrated simulation result used for the calculation of the thickness TH is selected based on the approximate value TH ₀ of the thickness TH of the object 9 to be measured, but the measured data and all the calibrated simulations are selected. When comparing the results, it is possible to omit the steps of calculating the approximate value TH ₀ and selecting the calibrated simulation results (steps S22 and S24).

9 ... Measurement object, 10 ... Measuring device, 12 ... Light source, 13 ... Fiber circulator, 14 ... Sensor head, 16 ... Spectrometer, 17 ... Detector, 18 ... Control device, 19 ... End face, 20 ... Control unit, 22 ... Signal processing unit, 24 ... Storage unit, 26 ... Input / output unit

Claims (4)

A step of simulating the interference light obtained by irradiating the measurement object with the measurement light and calculating the light intensity distribution of the interference light for each thickness of the measurement object.
A step of acquiring thickness calculation data including the characteristics of the envelope obtained by changing the sampling interval of the light intensity distribution of the interference light calculated for each thickness of the measurement object, and
A step of acquiring actual measurement data of the light intensity distribution of the interference light obtained by irradiating the measurement object with the measurement light, and
A step of calculating the thickness of the object to be measured by comparing the thickness calculation data obtained by the simulation with the characteristics of the envelope obtained by changing the sampling interval in the measured data.
A measurement method comprising. The measuring method according to claim 1, further comprising a step of calibrating the characteristics of the envelope obtained by the simulation using the measurement result of a standard having a known thickness. An approximate value of the thickness of the object to be measured is calculated based on the measured data, and the object to be measured is selected from the thickness calculation data obtained as a result of simulation for each thickness based on the estimated value. The measuring method according to claim 1 or 2, further comprising a step of selecting thickness calculation data to be used for thickness calculation. A light source that emits measurement light and
A simulation unit that simulates the interference light obtained by irradiating the measurement object with the measurement light and calculates the light intensity distribution of the interference light for each thickness of the measurement object.
A thickness calculation data acquisition unit that acquires thickness calculation data including envelope characteristics obtained by changing the sampling interval of the light intensity distribution of the interference light calculated for each thickness of the measurement object.
An actual measurement data acquisition unit that acquires actual measurement data of the light intensity distribution of the interference light obtained by irradiating the measurement object with the measurement light, and
A calculation unit that calculates the thickness of the object to be measured by comparing the thickness calculation data obtained by the simulation with the envelope characteristics obtained by changing the sampling interval in the measured data.
A measuring device provided with.