CN104897105A - Linear shape measurement method and linear - Google Patents

Abstract

The invention discloses a linear shape measurement method and linear shape measurement device. In the linear shape measurement method, three sensors which are arranged at intervals along a first direction is positioned oppositely to the object to be detected; the sensor collects the height data of the surface of the object to be measured with the sampling interval being under 1mm along the first direction. According to the collected height data, the curve rate of the sampling rate on the surface of the object to be measured is solved. According to the curve rate, the linear shape of the surface of the object to be measured is resolved.

Description

Rectilinear form assay method and rectilinear form determinator

The application advocates the right of priority of No. 2014-042251st, the Japanese patent application based on application on March 5th, 2014.The full content of this Japanese publication is by reference to being applied in this instructions.

Technical field

The present invention relates to a kind of method and the determinator that measure the rectilinear form on determinand surface.

Background technology

There will be a known and utilize sequential three point method to measure the technology (patent documentation 1) of the linearity on determinand surface.In sequential three point method, by the height of 3 sensor Simultaneously test, 3 points equidistantly configured, and obtain the local bending degree (curvature) of plane according to measurement result.And with the spacing between sensor, second order numerical integration is carried out to calculated curvature, thus obtain the rectilinear form of plane.

Disclose in patent documentation 2 on 3 sensors using in sequential three point method and add the 4th sensor to obtain the method for linearity.The configuration of 3 sensor spacing, the 4th sensor is configured in the inner side of the sensor of the most end in 3 sensors, and with the sensor of this most end across less spacing δ P.In method disclosed in patent documentation 2, make the height on the Simultaneously test determinand surface of the sensor unit each moving interval δ P comprising 4 sensors.

Patent documentation 1: Japanese Unexamined Patent Publication 2003-232625 publication

Patent documentation 2: Japanese Unexamined Patent Publication 2007-333556 publication

Confirm that the repeatability with the measurement result of the machined surface of surfaceness of the middle non-specular surfaces such as sequential three point method is in the past lower.Such as, if with the rectilinear form on the same determinand surface of the length measurment of 1m, then all in the scope of several microns, produce deviation when measuring at every turn.Therefore, sequential three point method in the past cannot be applied to needs to obtain in the evaluation of the finished surface of rectilinear form with the degree of accuracy below 1 μm of degree.

Summary of the invention

The object of the present invention is to provide a kind of can measure determinand surface rectilinear form and the good rectilinear form assay method of repeatability and rectilinear form determinator.

According to a kind of viewpoint of the present invention, provide a kind of rectilinear form assay method, it has:

Make the opposing surface of 3 sensors and the determinand arranged at equal intervals along the 1st direction, and make this sensor relative to described determinand along the operation of altitude information of collecting described determinand surface while described 1st direction relative movement with the sampling interval of below 1mm;

According to described altitude information, obtain the operation of the curvature being distributed in the sampled point on described determinand surface along described 1st direction with described sampling interval; And

According to described curvature, obtain the operation of the rectilinear form on described determinand surface.

According to another viewpoint of the present invention, provide a kind of rectilinear form determinator, it has:

3 sensors, arrange at equal intervals along the 1st direction;

Travel mechanism, is the opposing surface with determinand by described sensor supporting, and makes described sensor relative to described determinand along described 1st direction relative movement; And

Treating apparatus, controls described travel mechanism and moves along described 1st direction to make described sensor, and collects the altitude information measured by described sensor,

In described treating apparatus,

Described sensor is made to collect altitude information with the sampling interval of below 1mm while described 1st direction movement,

According to described altitude information, obtain the curvature being distributed in the sampled point on described determinand surface along described 1st direction with described sampling interval,

According to described curvature, obtain the rectilinear form on described determinand surface.

The altitude information of the sampled point of being sampled with the spacing of below 1mm by use carrys out calculated line shape, compared with sequential three point method in the past, can reduce the deviation of the measurement result of the rectilinear form on the surface with surfaceness.

Accompanying drawing explanation

Figure 1A is the stereographic map of the rectilinear form determinator based on embodiment, and Figure 1B is installed on the sensor of wheelhead lower end and the synoptic diagram of determinand.

Fig. 2 represents that utilization sequential three point method is in the past to measure the curve map of the result of the rectilinear form of determinand.

Fig. 3 A and Fig. 3 B is the surface of determinand and the schematic diagram of sensor unit.

Fig. 4 is the process flow diagram of the rectilinear form assay method based on embodiment.

Fig. 5 A and Fig. 5 B is the schematic diagram over time of the position relationship of determinand when representing by measuring rectilinear form based on the method for embodiment and sensor unit.

Fig. 6 is the line chart representing the initial point of sensor and the position relationship of tested fixed point.

Fig. 7 is the curve map of the example representing the curvature ρ using actual determination data to calculate.

Fig. 8 is the line chart representing the initial point of sensor and the position relationship of tested fixed point.

Fig. 9 is the curve map representing the result of being carried out 5 rectilinear form mensuration by the method based on embodiment along the same straight line on determinand surface.

Figure 10 is the line chart for illustration of the square ratio juris by carrying out calculated line shape based on the method for other embodiments.

In figure: 10-movable table, 11-worktable guide mechanism, 12-guide rail, 13-wheelhead, 14-emery wheel, 15-treating apparatus, 16-input media, 17-output unit, 20-determinand, 30-sensor unit, 31i, 31j, 31k-sensor, the tested fixed point of A, B, C-, p-transducer spacing, Δ p-sampling interval.

Embodiment

Based on the stereographic map of the rectilinear form determinator of embodiment shown in Figure 1A.This rectilinear form determinator is equipped on plane grinding apparatus.Movable table 10 is supported as can move to one direction by worktable guide mechanism (travel mechanism) 11.Define the moving direction of movable table 10 as x-axis and using the xyz orthogonal coordinate system as y-axis below vertical.

Wheelhead 13 is supported on the top of movable table 10 by guide rail 12.Wheelhead 13 can move along the z-axis direction along guide rail 12.Further, wheelhead 13 can be elevated in the y-direction relative to movable table 10.In the lower end of wheelhead 13, emery wheel 14 is installed.Emery wheel 14 has cylindrical outer shape, and is installed on wheelhead 13 with the posture that its central shaft is parallel with z-axis.

Movable table 10 maintains determinand (being ground thing) 20.Making emery wheel 14 with under the state of the surface contact of determinand 20, while emery wheel 14 is rotated, movable table 10 is moved in the x-direction, thus can the surface of grinding determinand 20.

From input media 16 to treating apparatus 15, input measures the various command value needed for rectilinear form.This command value comprises: measure the translational speed of movable table 10, the spatial frequency, mensuration commencing signal etc. of surfaceness during rectilinear form.Treating apparatus 15 calculates rectilinear form according to measurement result, and exports this result to output unit 17.

As shown in Figure 1B, in the lower end of wheelhead 13, sensor unit 30 is installed.3 sensors 31i, 31j and 31k are installed in sensor unit 30.The opposing surface of sensor 31i, 31j and 31k and determinand 20.Sensor 31i, 31j, 31k such as use the amplitude degree that can detect surfaceness, and that such as can detect the displacement of below ultra micro level has high-resolution laser displacement instrument.Sensor 31i, 31j, 31k can measure the distance of initial point to the surface of determinand 20 from each sensor 31i, 31j, 31k.Sensor 31i, 31j, 31k are calibrated, to make with zx plane as the height of the initial point of sensor 31i, 31j, 31k during benchmark is all equal.

3 sensors 31i, 31j, 31k arrange in the x-direction at equal intervals.The spacing of the initial point of the spacing of the initial point of adjacent sensor 31i and 31j and adjacent sensor 31j and 31k is called transducer spacing.This transducer spacing is represented with p.The tested fixed point of 3 sensors 31i, 31j, 31k also arranges across transducer spacing p in the x-direction on the surface of determinand 20.Transducer spacing p is such as 100mm.By making wheelhead 13 measure relative to while determinand 20 in the x-direction relative movement, thus the rectilinear form on the surface of the determinand 20 on x direction can be measured.In addition, in fact, by making movable table 10 move in the x-direction, make determinand 20 relative to wheelhead 13 relative movement in the x-direction.Determination data is inputted to treating apparatus 15 (Figure 1A) from sensor 31i, 31j, 31k.

With reference to figure 2, problem when measuring the rectilinear form of determinand to utilizing sequential three point method is in the past described.In sequential three point method in the past, make sensor unit 30 (Figure 1B) in the x-direction according to the height being measured determinand surface while the sampling interval movement equal with transducer spacing p by sensor 31i, 31j, 31k.And the curvature of tested fixed point (sampled point) is obtained according to measurement result.By carrying out Second Order Integral with sampling interval to calculated curvature, obtain the rectilinear form on determinand surface.In order to evaluate the measurement result based on sequential three point method in the past, carrying out 5 times along the same straight line on determinand surface and having measured.

The result that shown in Fig. 2,5 times measure.Transverse axis represents the distance apart from the reference point on the straight line measured with unit " mm ", and the longitudinal axis represents the displacement of the altitude datum from determinand surface with unit " μm ".The star of Fig. 2, quadrangle, triangle, sexangle, circular mark represent the measurement result of 1st ~ the 5th respectively.According to Fig. 2, between the measurement result of 5 times, there is larger deviation.

Such as, in the measurement result (circular mark) of the 5th, from measuring the position of distance 400mm towards 600mm, surface declines about 2 μm, but in the measurement result of the 2nd time (tetragonal mark), from measuring the position of distance 400mm towards 600mm, rise about 5 μm in surface.So, because measurement result exists deviation, rectilinear form cannot be measured with pinpoint accuracy.

With reference to figure 3A and Fig. 3 B, reason measurement result being existed to deviation is described.The surface of determinand 20 shown in Fig. 3 A and the schematic diagram of sensor unit 30.The surface of determinand 20 has the shape of cycle longer percent ripple and cycle shorter surfaceness overlap.In Fig. 3 A, be represented by dotted lines the surface only considering percent ripple, represent the real surface considering surfaceness with solid line.Such as, the spatial frequency of carrying out the surfaceness on the surface of accurate grinding is tens of about cycles/mm, and the difference of height of surfaceness is in the scope of 0.1 micron to several microns.

Therefore, even if sensor unit 30 only departs from several microns in the x-direction, the height of tested fixed point A, B, C of being measured by 3 sensors 31i, 31j, 31k also can significantly be changed.Its result, causes the curvature calculated according to the altitude information that determines also significantly to change, and all inconsistent in each mensuration by carrying out the rectilinear form that second order integro assigns to obtain to curvature.Further, suppose the position consistency of tested fixed point A, B, C during each mensuration, but the altitude information measured not reflects the data of percent ripple shape itself, but be reflected in the percent ripple overlapping data having surfaceness shape in shape.The amplitude of surfaceness and the wave height value same degree of percent ripple or be more than wave height value, therefore cannot obtain only based on the curvature of rectilinear form according to the altitude information be measured to exactly.

Such as, in Fig. 3 A, the tested fixed point A based on sensor 31i is positioned at the crest of surfaceness and the roughly middle of trough, and in Fig. 3 B, tested fixed point A is positioned at the summit of the crest of surfaceness.If the height of tested fixed point A, B, C of being measured by 3 sensors 31i, 31j, 31k is inconsistent, then cause the curvature that calculates according to this altitude gauge also inconsistent.Its result, the measurement result of the rectilinear form obtained according to curvature also produces deviation.This deviation can be reduced in the embodiment below illustrated.

With reference to figure 4 ~ Fig. 7, be described based on the rectilinear form determinator of embodiment and rectilinear form assay method.Based on the process flow diagram of the rectilinear form assay method of embodiment shown in Fig. 4.

In step sl, to the collection condition of rectilinear form determinator input altitude information.This input is undertaken by input media 16 (Fig. 1).The collection condition of altitude information comprises: the maximum spatial frequency Fmax of the surfaceness of scan velocity V, determinand 20 and transducer spacing p.In addition, transducer spacing p can be pre-stored within treating apparatus 15.

In step s 2, sample frequency Fs is determined.The determination of sample frequency Fs can be undertaken by treating apparatus 15 (Fig. 1), also can determine sample frequency Fs by operator.When determining sample frequency Fs by operator, input determined sample frequency Fs from input media 16 (Fig. 1).

The mode of sample frequency Fs Fs >=2 as to satisfy the inequality × V × Fmax is determined.Below, the physical significance of this inequality is described.Above-mentioned inequality can be rewritten as V/Fs≤1/ (2 × Fmax).The V/Fs on the left side equals the sampling interval (hereinafter referred to as sampling interval Δ p) collected on the x direction of altitude information.1/ (2 × Fmax) on the right equals 1/2 of the minimum period Pmin of surfaceness.That is, above-mentioned inequality represents that sampling interval Δ p is less than 1/2 of the minimum period Pmin of surfaceness.

In step s3, sensor 31i, 31j, 31k is made relative to determinand 20 in the x-direction to collect altitude information according to sample frequency Fs while scan velocity V relative movement.In addition, as illustrated in figures ia and ib, in fact make sensor 31i, 31j, 31k static, determinand 20 is moved in the x-direction.

The position relationship of the determinand 20 when measuring altitude information shown in Fig. 5 A and Fig. 5 B in step s3 and sensor unit 30 over time.Under the state shown in Fig. 5 A, collect altitude information a, b, c respectively by sensor 31i, 31j, 31k.At this, altitude information a, b, c represent the distance of initial point to tested fixed point A, B, C of determinand 20 from sensor 31i, 31j, 31k respectively.

As shown in Figure 5 B, when sensor unit 30 only moves sampling interval Δ p in the x-direction relative to determinand 20, collect altitude information a, b, c.The sampling interval Δ p corresponding with the sample frequency Fs determined in step S2 (Fig. 4) is less than 1/2 of the minimum period Pmin of surfaceness.By collecting altitude information a, b, c according to sample frequency Fs, collect in the x-direction with the altitude information of multiple tested fixed point A, B, C of sampling interval Δ p arrangement.By sampling interval Δ p being set to less than 1/2 of the minimum period Pmin of surfaceness, the aliasing with sampling can be avoided.

In step S4 (Fig. 4), perform and remove the low-pass filtering treatment with the waveform component of the wavelength of 2 times that are less than transducer spacing p relative to collected altitude information a, b, c.This low-pass filtering treatment is performed by treating apparatus 15 (Figure 1A).

In step s 5, according to altitude information a, b, c after low-pass filtering treatment, calculate on the surface of determinand 20 in the x-direction with the curvature ρ of the sampled point of sampling interval Δ p distribution.

With reference to figure 6, the method for obtaining of curvature ρ is described.Fig. 6 represents the position relationship of initial point D, E, F of sensor 31i, 31j, 31k and tested fixed point A, B, C.The length of line segment DA is equivalent to altitude information a, and the length of line segment EB is equivalent to altitude information b, and the length of line segment FC is equivalent to altitude information c.The length of line segment DE and the length of line segment EF are equivalent to transducer spacing p.Represent the radius of the circumference by 3 tested fixed point A, B, C with r, represent the center of this circumference with O.

Represent the intersection point of line segment EB and line segment AC with G, represent the intersection point of line segment BO and line segment AC with H.The length g of line segment BG represents as follows:

g＝b-(a+c)/2…（1)。

Length g represents the degree of crook on the surface of tested fixed point A to tested fixed point C from determinand 20.Length g also can be described as the altitude information of the surface elevation representing determinand 20.

The angle that line segment EB and line segment BO is is very little.Therefore, it is possible to the length regarding the length of line segment GB and line segment HB as is almost equal, the length of line segment GC and the length of line segment HC almost equal.Therefore, it is possible to regard the length of line segment HB as and g almost equal, length and the p of line segment HC are almost equal.Length and the r-g of line segment OH are almost equal.If apply Pythagorean theorem in right-angle triangle OHC, then following formula is set up.

r ²＝(r-g) ²+p ²…(2)

Because curvature ρ is defined as ρ=1/r, therefore obtain following formula from this definition and formula (2).

ρ＝1/r＝2g/(g ²+p ²)…(3)

If the g on the right of formula (3) substitutes into formula (1), then can calculate the curvature ρ of tested fixed point B.P is about 100mm, and therefore g is micron order.Be sufficiently more than g (p > > g) owing to can be assumed to p, therefore formula (3) is almost identical with following formula.

ρ＝2g/p ²…(4)

Positive curvature ρ represents the curvature protruded down, and negative curvature ρ represents the curvature protruded upward.Curvature ρ is obtained in each measuring multiple sampled points that line arranges with sampling interval Δ p.Thus, distribution ρ (x) of the curvature ρ on x direction is calculated.

One example of the curvature ρ using actual determination data to calculate shown in Fig. 7.Transverse axis represents determinand 20 position in the x direction with unit " mm ", and the longitudinal axis is with unit " mm ^-1" represent curvature.The curvature ρ calculated compared with altitude information a, b, the c before fine line represents according to the low-pass filtering treatment of carrying out step S4 of Fig. 7, represents the curvature ρ calculated according to altitude information a, b, c of having carried out low-pass filtering treatment compared with heavy line.

It can thus be appreciated that the curvature ρ using altitude information a, b, c before enforcement low-pass filtering treatment to calculate is subject to the impact of surfaceness, and deviation is larger.By implementing low-pass filtering treatment, the impact of surfaceness can be got rid of, obtain the curvature based on surface waviness.In addition, altitude information g can be calculated according to measured altitude information a, b, c, and implement low-pass filtering treatment to the altitude information g calculated, thus replacement is to measured altitude information a, b, c enforcement low-pass filtering treatment and according to formula (1) computed altitude data g.

In step S6 (Fig. 4), using the integration spacing of sampling interval Δ p as numerical integration, for sampling interval, Second Order Integral is carried out to distribution ρ (x) of curvature, obtain rectilinear form thus.Below, with reference to figure 8, the method for specifically obtaining of the rectilinear form based on Second Order Integral is described.

The position relationship of initial point D, E, F of sensor shown in Fig. 8 31i, 31j, 31k and tested fixed point A, B, C.Respectively with the degree of tilt dy of following formula table timberline section AB ₁/ dx ₁and the degree of tilt dy of line segment BC ₂/ dx ₂.

[formula 1]

$\frac{{\mathrm{dy}}_1}{{\mathrm{dx}}_1}=\frac{b-a}{p}$

$\frac{{\mathrm{dy}}_2}{{\mathrm{dx}}_2}=\frac{c-b}{p}...\left(5\right)$

The second derivative d of tested fixed point B is shown with following formula table ²y/dx ².

[formula 2]

$\frac{d^{2}y}{{\mathrm{dx}}^2}=\frac{\frac{{\mathrm{dy}}_2}{{\mathrm{dx}}_2}-\frac{{\mathrm{dy}}_1}{{\mathrm{dx}}_1}}{p}=\frac{\frac{c-b}{p}-\frac{b-a}{p}}{p}=\frac{(a+c)-2b}{p^2}=\frac{2g}{p^2}...\left(6\right)$

This second derivative is equal with the curvature ρ obtained according to formula (4).It can thus be appreciated that, by carrying out Second Order Integral to distribution ρ (x) of curvature, can rectilinear form y (x) be obtained.

Then, the method for curvature ρ (x) being carried out to second order numerical integration is described.When sampled point marks the sequence number i from 1, following recursion formula can be obtained.

[formula 3]

$\frac{\mathrm{dy}}{\mathrm{dx}}\left(i\right)=\frac{\mathrm{dy}}{\mathrm{dx}}(i-1)+\frac{\frac{d^{2}y}{{\mathrm{dx}}^2}(i-1)+\frac{d^{2}y}{{\mathrm{dx}}^2}\left(i\right)}{2}\×\mathrm{\Δp}$

$y\left(i\right)=y(i-1)+\frac{\frac{\mathrm{dy}}{\mathrm{dx}}(i-1)+\frac{\mathrm{dy}}{\mathrm{dx}}\left(i\right)}{2}\×\mathrm{\Δp}$

x(i)＝i×Δp…(7)

Second derivative d ²y/dx ²and d (i-1) ²y/dx ²i () is identical with the curvature ρ (i-1) obtained according to formula (4) and ρ (i).Therefore, it is possible to obtain rectilinear form y (i) from above-mentioned recursion formula.

In step S7 (Fig. 4), the degree of tilt of rectilinear form is corrected.According to above-mentioned recursion formula, if as initial value setting arbitrary value (such as " 0 ") of the dy/dx (degree of tilt) during i=1, and calculate according to recursion formula, then produce the mean pitch of rectilinear form y (i) sometimes.In the step s 7, carry out degree of tilt correction, become " 0 " to make the mean pitch of such as rectilinear form y (i).

Result by carrying out along the same straight line on the surface of determinand measuring for 5 times based on the method for embodiment shown in Fig. 9.Transverse axis represents the distance apart from the reference point on the straight line measured with unit " mm ", and the longitudinal axis represents the displacement of the altitude datum from determinand surface with unit " μm ".The measurement result of 5 times is roughly overlapping.If compare Fig. 2 and Fig. 9, then known by the rectilinear form assay method of application based on embodiment, the deviation of measurement result significantly reduces.So, by application based on the linearity assay method of embodiment, the higher and mensuration that degree of accuracy is higher of repeatability can be carried out.

In the above-described embodiments, in step S4 (Fig. 4), perform low-pass filtering treatment, but also can omit low-pass filtering treatment.Integral operation has the character that the radio-frequency component of original waveform is decayed.Therefore, though the curvature of the Second Order Integral object as step S6 (Fig. 4) as the waveform before the low-pass filtering treatment of Fig. 7 in comparatively short period drastic change of having to go to the toilet move, by carrying out Second Order Integral, radio-frequency component also can be decayed.Therefore, even if omit low-pass filtering treatment, in fact also can obtain and the rectilinear form the come to the same thing curvature based on the altitude information after low-pass filtering treatment being carried out to Second Order Integral.

Further, in the above-described embodiments, in step S6 (Fig. 4), Second Order Integral has been carried out to curvature ρ (x), but also can obtain moving average to curvature ρ (x), and Second Order Integral has been carried out to this moving average.Such as, when sampling interval Δ p is 1mm, the moving average of curvature ρ (x) can be obtained by length 10mm, and Second Order Integral is carried out to this moving average.In this Second Order Integral, integration spacing is set to 10 times of Δ p, i.e. 10mm.

In the above-described embodiments, in step s 2, sampling interval Δ p is set to less than 1/2 of the minimum period Pmin of surfaceness, but by sampling interval Δ p is set to below 1mm, compared with the sequential three point method in the past equal with transducer spacing p with sampling interval Δ p, the higher mensuration of degree of accuracy can be carried out.

Then, other embodiments are described.In the embodiment below illustrated, application complex vector method.

As shown in Figure 10, the rectilinear form on determinand 20 surface can be represented with the connection of small unit vector x (i).Wherein, i is the integer of more than 0.The angle that vector x (i-1) and x (i) are is represented with Δ θ (i-1).The radius-of-curvature of the position of vector x (i-1) is represented with r (i-1).The length Δ s (i-1) that radius is r (i-1), central angle is the circular arc of Δ θ (i-1) can be gone out by following formulae discovery.

Δs(i-1)＝r(i-1)×Δθ(i-1)…(8)

The angle delta θ (i-1) being due to vector x (i-1) and vector x (i) is small, and therefore following approximate formula is set up.

Δs(i-1)＝|x(i)|…(9)

Wherein, | x (i) | represent the length of vector x (i).Small unit vector x (i) (i=0,1,2,3 ...) consistent length.

Following formula is obtained from formula (8) and formula (9).

Δθ(i-1)＝|x(i)|/r(i-1)…(10)

Length and the sampling interval Δ p of vector x (i) are almost equal.Radius-of-curvature r (i-1) can calculate according to above-mentioned formula (3).Therefore, it is possible to obtain the angle delta θ (i-1) that vector x (i-1) and x (i) be.

Vector x (i) is equal with making the vector of vector x (i-1) only anglec of rotation Δ θ (i-1).Therefore, it is possible to represent vector x (i) with following formula.

[formula 4]

By the vector of the small unit vector x (i) till obtaining i=0 to i=n, the terminal point coordinate of the n-th small unit vector x (n) can be obtained.By obtaining the terminal point coordinate of each small vector x (i), rectilinear form can be determined.

Above, embodiment is used to describe the present invention, but the present invention be limited to this.Such as, can carry out various change, improvement, combination etc., this it will be apparent to those skilled in the art that.

Claims (6)

1. a rectilinear form assay method, it has:

Make the opposing surface of 3 sensors and the determinand arranged at equal intervals along the 1st direction, and make this sensor relative to described determinand along the operation of altitude information of collecting described determinand surface while described 1st direction relative movement with the sampling interval of below 1mm;

According to described altitude information, obtain the operation of the curvature being distributed in the sampled point on described determinand surface along described 1st direction with described sampling interval; And

According to described curvature, obtain the operation of the rectilinear form on described determinand surface.

2. rectilinear form assay method according to claim 1, wherein,

By carrying out Second Order Integral to the moving average of described curvature or described curvature, obtain the rectilinear form on described determinand surface.

3. rectilinear form assay method according to claim 1 and 2, wherein,

Described sampling interval is set to less than 1/2 of the cycle of the maximum spatial frequency of the surfaceness being equivalent to described determinand surface.

4. a rectilinear form determinator, it has:

3 sensors, arrange at equal intervals along the 1st direction;

Travel mechanism, is the opposing surface with determinand by described sensor supporting, and makes described sensor relative to described determinand along described 1st direction relative movement; And

Treating apparatus, controls described travel mechanism and moves along described 1st direction to make described sensor, and collects the altitude information measured by described sensor,

In described treating apparatus,

Described sensor is made to collect altitude information with the sampling interval of below 1mm while described 1st direction movement,

According to described altitude information, obtain the curvature being distributed in the sampled point on described determinand surface along described 1st direction with described sampling interval,

According to described curvature, obtain the rectilinear form on described determinand surface.

5. rectilinear form determinator according to claim 4, wherein,

Described treating apparatus, by carrying out Second Order Integral to the moving average of described curvature or described curvature, obtains the rectilinear form on described determinand surface.

6. the rectilinear form determinator according to claim 4 or 5, wherein,

Described sampling interval is set to less than 1/2 of the cycle of the maximum spatial frequency of the surfaceness being equivalent to described determinand surface.