CN1434289A - Method for detecting surface defect and device thereof - Google Patents

Abstract

The method of detecting the surface detect of the invention: make the polarized light irradiate the detected surface and find the parameter of the elliptical polarization light of its reflex; make the light irradiate the same position to find its reflec strength; according to and, judge the grade and sort of the detect. The detecting equipment includes: the determining; the determining; and the equipment dividing the three-dimensional coordinate position of the and I into the predetermined range and outputting it.

Description

The detection method of surface imperfection and device thereof

(the application is to be that October 27 nineteen ninety-five, application number are 95102598.8 the applying date, and the division of the identical application of denomination of invention)

Technical field

The present invention relates to the optical detecting method and the device thereof of surface imperfection.

Background technology

As the device that detects the Surface Defects in Steel Plate such as defective on the surface of thin steel sheet with optical means, employing is light source with laser and utilizes scattering of light or the optical defect detecting device of diffraction pattern variation mostly.This detection mode is to utilize the variation by caused laser light scattering of defective or diffraction pattern to detect defective, and when forming tangible concavo-convex defective on surface of steel plate, this is a kind of effective detection method.

, if defective is not a concave-convex surface, but there are thin oxide film etc. in the maldistribution that physical parameter is inhomogeneous, smooth finish is small, part, and coating film thickness is unequal, adopts above-mentioned observation procedure just to be difficult to detect in these cases.For example on the surface of steel plate that normally is partly with 100 left and right sides oxide films, there is the thickness part of oxide film to reach unusual part about 400 .Following this unusual part is called decorative pattern shape defective.This zone will cause japanning bad etc. in next process, therefore require as defects detection and remove, but owing to covered by the smooth finish of surface of steel plate with the difference of the oxide thickness of normal part, so utilize scattering of light or diffraction method can not detect fully.

When detection does not have the defective of sensitivity to scattering and diffraction, the surface inspecting method that utilizes polarized light is arranged.The method that in the fair 5-23620 communique of spy, has proposed to be used to search the foreign matter on the semiconductor chip for example.This method is that the ψ that asks for the polarized light parameter promptly asks the amplitude ratio (tan ψ) of P polarized light and S polarized light and detects the method for defective.(so-called P polarized light is meant the component of the plane of incidence direction that is parallel to light in the catoptrical electric vector, and so-called S polarized light is meant the component perpendicular to plane of incidence direction.) but polarized light component is than constant and normal and the vicissitudinous surface imperfection in unusual part, for above-mentioned purpose, this method just can not be suitable for.

The method of measuring P, S component ratio and the phase differential of polarized light simultaneously has ellipsometry.At fair 4-78122 communique of spy and special opening the method for utilizing ellipsometry that the characteristic value of material surface is tested has been proposed in the flat 1-211937 communique., too sensitive when these methods are used for the test material surface imperfection as mentioned above, can think to be used to detect defective on the steel plate.Like this, the decorative pattern shape defective that detects on the steel plate with optical means was impossible in the past, did not also have this device.

The objective of the invention is to enlarge the existing non-detectable decorative pattern shape of the method surface imperfection of quantity, detection of the defect kind that can detect and distinguish.

Summary of the invention

In order to achieve the above object, the first, the invention provides a kind of detection method of surface flaw that constitutes by following operation:

(a) sample of surface imperfection is arranged with polarizing light irradiation, obtain the operation of elliptic polarization optical parameter (ψ, the Δ) characteristic of surface reflection in advance;

(b) sample that should check with polarizing light irradiation be examined the surface, obtain the elliptic polarization optical parameter ψ of surface reflection, the operation of Δ;

(c) operation that compares of elliptic polarization optical parameter (ψ, Δ) characteristic that will in operation (b), obtain and elliptic polarization optical parameter (ψ, the Δ) characteristic in the operation (a);

(d) according to the result who obtains in the operation (c), the operation of decision table planar defect grade.

The second, the invention provides a kind of detection method of surface flaw that constitutes by following operation:

(a) should check the surface that is examined of sample with polarizing light irradiation, obtain the operation of surface reflection elliptic polarization optical parameter (ψ, Δ);

(b) with rayed with in operation (a) with the same position of polarizing light irradiation, obtain the operation of surface reflection light intensity (I);

(c) according to the intensity of reflected light (I) that obtains in elliptic polarization optical parameter that obtains in the operation (a) (ψ, Δ) and the operation (b), the operation of decision table planar defect grade and kind.

The 3rd, the invention provides a kind of by the surface defect detection apparatus that constitutes with lower device:

(a) device of the elliptic polarization optical parameter of storage surface defective (ψ, Δ) characteristic in advance;

(b) be examined the surface, measure the device of the elliptic polarization optical parameter (ψ, Δ) of surface reflection with polarizing light irradiation;

(c) ellipsometric parameter (ψ, Δ) and elliptic polarization optical parameter (ψ, the Δ) characteristic in the memory storage of the surface reflection of relatively being measured and export the device of this comparative result.

The 4th, the invention provides a kind of by the surface defect detection apparatus that constitutes with lower device:

(a) be examined the surface with polarizing light irradiation, measure the device of the elliptic polarization optical parameter (ψ, Δ) of surface reflection;

(b) with rayed and same lip-deep position, the device of crossing with polarizing light irradiation of mensuration surface reflection light intensity (I) of being examined;

(c) by predetermined scope division and export ψ, the Δ under this reflected light that is examined the surface, the device of I three-dimensional coordinate position.

The 5th, the invention provides a kind of by the surface defect detection apparatus that constitutes with lower device:

(a) polarized light of parallel beam is incided be examined lip-deep light projecting apparatus;

(b) be separately positioned on the different light paths that is examined surface reflection, make from the reflected light incident that is examined the surface and be transformed to the optical pickup apparatus of picture signal;

(c) this optical pickup apparatus is made of with three linear array transducers that see through light that receive each analyzer three analyzers that have different orientations respectively;

(d) be used to handle signal processing apparatus from the picture signal of these three linear array transducers, this signal processing apparatus to amplitude reflectivity than tan ψ represent, the COS Δ of phase difference and be examined the intensity of reflected light I on surface ₀Calculate, generate tan ψ image, COS Δ image and I ₀Image, and according to the tan ψ image, COS Δ image and the I that are generated ₀Each pixel concentration of image is estimated character of surface.

The 6th, the invention provides a kind of by the surface defect detection apparatus that constitutes with lower device:

(a) polarized light is incided the light projecting apparatus that is examined on the surperficial whole Width;

(b) be arranged on direct reflection optical detection device on the specular light light path that is examined surface reflection;

(c) be arranged on scattered light pick-up unit on the scattered light light path that is examined surface reflection;

(d) at least a device has and incident light is separated into the optical system of three light beams and is separately positioned on the light path of three separated light beams and has the analyzer of different orientations respectively and receive the camera head that each analyzer sees through light in direct reflection optical detection device and the scattered light pick-up unit;

(e) picture signal from direct reflection optical detection device and scattered light pick-up unit is compared and to from receiving that picture signal that analyzer sees through these three imaging devices of light is handled and the elliptic polarization optical parameter that the is examined surface reflection signal processing apparatus that to be amplitude reflectivity calculate than the COS Δ of tan ψ, expression phase difference, than run ψ and COS Δ, estimate the character of surface that is examined the surface according to the comparative result of specular light and scattered light and amplitude reflectivity.

The 7th, the invention provides a kind of by the surface defect detection apparatus that constitutes with lower device:

(a) polarized light is incided the light projecting apparatus that is examined on the surperficial whole Width;

(b) scattered light that is arranged on the scattered light light path that is examined in the surface reflection receives optical pickup apparatus;

(c) this optical pickup apparatus have with incident light be separated into three light beams optical system, be separately positioned on the light path of three separated light beams and have the analyzer of different orientations respectively and receive the imaging device that each analyzer sees through light;

(d) to from receiving that picture signal that each analyzer sees through three imaging devices of light is handled and to the ellipsometric parameter that the is examined surface reflection signal processing apparatus that to be amplitude reflectivity calculate than the COS Δ of tan ψ, expression phase difference, than tan ψ and COS Δ, estimate the character of surface that is examined the surface according to the amplitude reflectivity that calculates.

The 8th, the invention provides a kind of by the surface defect detection apparatus that constitutes with lower device:

(a) polarized light is incided be examined lip-deep light projecting apparatus;

(b) make from the reflected light incident that is examined the surface and export the linear display of the prismatic glasses formula gamma camera of three kinds of different polarized light image signals;

(c) prismatic glasses formula linear array gamma camera by the beam separation with incident become three light beams beam splitter, be separately positioned on the light path of three separated light beams and its position angle by the analyzer of O, π/4, a π/4 configurations and receive the linear array transducer that each analyzer sees through light and constitute;

(d) handle from the signal processing apparatus of the polarization image signal of prismatic glasses formula linear array gamma camera output, the ellipsometric parameter that is examined surface reflection is amplitude reflectivity than the COS Δ of tan ψ, expression phase difference and is examined the intensity of reflected light I on surface ₀Calculate, according to the amplitude reflectivity that calculates than tan ψ, COS Δ and surface reflection intensity I ₀, judge that being examined the surface has free of surface defects.

The 9th, the invention provides a kind of by the surface defect detection apparatus that constitutes with lower device;

(a) will incide and be examined lip-deep light projecting apparatus along being examined light beam that the face width direction distributes;

(b) make from the reflected light incident that is examined the surface, and be transformed into the optical pickup apparatus of picture signal;

This optical pickup apparatus has to be arranged on and is examined on the surface reflection light path and has three analyzers of different orientations respectively and receive the linear array transducer that each analyzer sees through light;

(c) making output image signal standardization from each linear array transducer, planarization and according to the picture signal after the planarization, is COS Δ and the intensity of reflected light I of amplitude reflectivity than tan ψ and expression phase difference to ellipsometric parameter ₀The signal processing apparatus that calculates of relative value, according to the amplitude reflectivity that calculates than tan ψ and phase differential COS Δ and intensity of reflected light I ₀Relative value, judge that be examined the surface has or not surface abnormalities.

The tenth, the invention provides a kind of by the surface defect detection apparatus that constitutes with lower device:

(a) polarized light is incided be examined lip-deep light projecting apparatus;

(b) optical system by a plurality of reception light that receive three direction polarized lights at least with different special angles constitutes, is used for detecting and is examined the reflected light that reflected of surface and the optical pickup apparatus that is transformed into picture signal;

(c) will receive the light distribution standardization of the optical system output of light from each by the reference value of predesignating, and the changed polarity and the variable quantity of the some light distribution after the standardization compared with predetermined figure, judge the signal processing apparatus of defect kind.

The 11, the invention provides a kind of by the surface defect detection apparatus that constitutes with lower device;

(a) the polarized light light beam is incided the light projecting apparatus that is examined on the surperficial whole Width;

(b) make from the reflected light incident that is examined the surface, and be transformed into the pick-up unit of picture signal;

This pick-up unit have will be examined the reflected light on surface be separated into three light beams beam splitter, be arranged on the light path of three separated light beams and have the analyzer of different orientations respectively and receive the linear array transducer that each analyzer sees through light;

(c) signal processing apparatus of handling from the signal of this pick-up unit, this signal processing apparatus are waited to look into regional withdrawing device, parameter arithmetic unit and decision maker by defective and are constituted,

Defective is waited to look into regional withdrawing device concentration level and predetermined benchmark concentration level from the polarized light image of three groups of linear array transducers inputs is compared, the zone is waited to look into as defective in the zone of polarized light image concentration level beyond the benchmark concentration level range of measuring extracts out

The parameter arithmetic unit waits to look into the interior mensuration light intensity in zone according to the defective of extracting out, calculates elliptic polarization optical parameter and surface reflection light intensity,

Decision maker compares the grade of decision table planar defect and kind with elliptic polarization optical parameter and the surface reflection light intensity of calculating with predetermined surface imperfection characteristic.

The accompanying drawing summary

Fig. 1 is the figure of the ellipsometric parameter when having oxide film on the expression steel plate.

Fig. 2 is the coverage diagram figure of A type defective.

Fig. 3 is the coverage diagram figure of Type B defective.

Fig. 4 is the coverage diagram figure of C type defective.

Fig. 5 is that one of defect detecting device of the present invention is implemented illustration.

Fig. 6 is an illustration of the optical system of elliptic polarization optical parameter.

Fig. 7 is that one of optical system of the present invention is implemented illustration.

Fig. 8 is that one of signal processing system of the present invention is implemented illustration.

Fig. 9 is that one of conversion process of the present invention is implemented illustration.

Figure 10 is that one of defect detecting device of the present invention is implemented illustration.

Figure 11 is the optical system configuration composition of the embodiment of the invention.

Figure 12 is the block diagram of the signal processing of the expression embodiment relevant with Figure 11.

Figure 13 is the operating principle key diagram of the expression embodiment relevant with Figure 11.

Figure 14 is the image distribution performance plot of the expression embodiment action relevant with Figure 11.

Figure 15 is the optical system side view of another embodiment.

Figure 16 is the optical system vertical view of another embodiment.

Figure 17 is the optical system side view of the embodiment relevant with Figure 16.

Figure 18 is the optical system side view of another embodiment.

Figure 19 is the optical system side view of another embodiment.

Figure 20 is the optical system configurations figure of the embodiment of the invention.

Figure 21 represents the key diagram of the embodiment configuration relevant with Figure 20.

Figure 22 is the structured flowchart of the embodiment signal processing relevant with Figure 20.

Figure 23 is the optical system configurations figure of another embodiment.

Figure 24 is the optical system configurations figure of another embodiment.

Figure 25 is the optical system configurations figure of another embodiment.

Figure 26 is the optical system configurations figure of another embodiment.

Figure 27 is the optical system configurations figure of another embodiment.

Figure 28 is the optical system configurations figure of the embodiment of the invention.

Figure 29 is the configuration instruction figure of the action of the expression optical system relevant with Figure 28.

Figure 30 is the structural drawing of the linear array gamma camera of prismatic glasses formula polarized light of the embodiment relevant with Figure 28.

Figure 31 is the block diagram of the signal processing of the embodiment relevant with Figure 28.

Figure 32 is the optical system configuration composition of the embodiment of the invention.

Figure 33 is the embodiment signal processing block diagram relevant with Figure 32.

Figure 34 is the action specification figure of the expression embodiment optical system relevant with Figure 32.

Figure 35 is the image color performance diagram of the expression embodiment standardization relevant with Figure 32.

Figure 36 is the pattern figure of the expression embodiment relevant with Figure 32 through the image of standardization.

Figure 37 is tan ψ, COS Δ and the I of the expression embodiment relevant with Figure 32 ₀The pattern figure of image.

Figure 38 is the optical system vertical view of another embodiment.

Figure 39 is the optical system side view of embodiment among Figure 38.

Figure 40 is the optical system side view of another embodiment.

Figure 41 is the optical system configuration composition of embodiments of the invention.

Figure 42 is the key diagram of the optical system action of the expression embodiment relevant with Figure 41.

Figure 43 is the linear array gamma camera of the prismatic glasses formula polarized light structural drawing of the embodiment relevant with Figure 41.

Figure 44 is the signal processing block diagram of the embodiment relevant with Figure 41.

Figure 45 is the surface of intensity distribution of expression flaw indication.

Figure 46 is the reference pattern of expression defect kind, defective patterns and magnitude pattern.

Figure 47 is the graph of a relation of light quantity level and defect rank.

Figure 48 is the key diagram of the concrete example of expression kind of various defectives and grade.

Figure 49 is the optical system configurations figure of the embodiment of the invention.

Figure 50 is the configuration instruction figure of the expression embodiment relevant with Figure 49.

Figure 51 is the embodiment signal processing block diagram relevant with Figure 49.

Figure 52 is the picture specification figure of the action of the expression embodiment relevant with Figure 49.

Figure 53 is the concentration performance plot of expression double quantification level.

Figure 54 is the optical system configurations figure of embodiments of the invention.

Figure 55 is the key diagram of the optical system action of the expression embodiment relevant with Figure 54.

Figure 56 is the embodiment signal processing block diagram relevant with Figure 54.

Figure 57 is the action block diagram of the expression embodiment relevant with Figure 54.

Figure 58 is the signal strength distribution map of expression rim detection action.

Figure 59 is the key diagram of the compensating movement of expression luminance nonuniformity.

Figure 60 is the concentration performance plot of expression double quantification level.

Figure 61 is the polar character figure of the defect kind on the cold-rolled steel sheet.

Figure 62 is the polar character figure of the defect kind on the electroplating steel plate.

The concrete mode that carries out an invention

The 1st embodiment:

Elliptic polarization optical parameter (ψ, Δ) is by the reflectivity R of the S component of polarized light _SReflectivity R to the P component _PRatio P, define by (1) formula.

ρ-R _S/R _P＝tanψ·exp(jΔ)…(1)

Tan ψ represents the amplitude ratio of catoptrical P, S component in the formula, the phase differential of exp (j Δ) expression P, S component.When incident light was the linearly polarized light of 0 degree (only for the P component), the phase differential that the angle that the main shaft of the ellipse that catoptrical P, S component constitute and the plane of incidence constitute is equivalent to ψ, P, S component was equivalent to Δ.Here, the available twin shaft of quadrature arbitrarily angle of polarization degree segmented reflector light is measured each intensity of polarization light, and according to the major axes orientation and the eccentricity of ellipse, calculates ψ and Δ.In addition, the polarization of incident light state can be set arbitrarily, at this moment, revises the polarization of incident light state, obtains ψ, Δ.

Catoptrical intensity I is by the intensity I of incident light ₀With surface reflectivity R, obtain by (2) formula.

I＝I ₀·R

When adopting this optical detecting value, above-mentioned problem can solve by following detection method of surface flaw, the feature of this method is to be examined the surface with polarizing light irradiation, obtain the elliptic polarization optical parameter (ψ, Δ) of surface reflection, to comparing, make grade from the reflected light amplitude ratio ψ of the surface imperfection of trying to achieve in advance and the characteristic of phase difference.

In addition, the feature of detection method of surface flaw also is: polarizing light irradiation is examined the surface and obtains elliptic polarization optical parameter (ψ, Δ), same polarized light or other rayed are examined the same position on surface and obtain surface reflection intensity (I), according to the two condition judgement surface imperfection grade and kind of this ellipsometric parameter and this reflection strength.

Device of the present invention is a surface defect detection apparatus, it is characterized in that having the elliptic polarization optical parameter of storage surface defective (ψ, Δ) characteristic in advance device, polarizing light irradiation is being examined the device of measuring the elliptic polarization optical parameter (ψ, Δ) of surface reflection on the surface, and the device of the comparative result of the characteristic of the surface reflection measured of output and storage.

In addition, being characterized as of surface defect detection apparatus also have with polarizing light irradiation be examined on the surface and ask for the device of the ellipsometric parameter (ψ, Δ) of this surface reflection, with same polarized light or different rayed at the same position that is being examined the surface and measure the device of intensity of reflected light (I) and by predetermined division scope, output is from the device of the ψ under the reflected light that is examined the surface, Δ, I three-dimensional coordinate position.

Surface defect detection apparatus is characterised in that when determined surface is wide, adopts a plurality of two-dimentional photography elements as this catoptrical optical pickup apparatus, uses the pixel shading value that is equivalent to same reflection spot to calculate ψ, Δ and I.In addition, the light source of this polarized light is a monochromatic source, utilizes optical fiber to make this light source irradiation be examined lip-deep specialized range, shares reception from the reflected light that is examined the surface with many ellipsometers.

Because polarized light has the characteristic to the surface state sensitivity of material, therefore can measure and utilize scattered light, the non-detectable character of surface of diffraction light.On the surface that decorative pattern shape defective is arranged, during the characteristic variations relevant with reflection of light, the elliptic polarization optical parameter changes delicately., do not know to adopt which type of method can make the variation of elliptic polarization optical parameter corresponding with defective in the past.Present inventors study the relation of elliptic polarization optical parameter and surface imperfection, found that under the situation of decorative pattern shape defective, corresponding with the scope of the oxide thickness that goes out as defects detection, ψ and Δ have function characteristic and change thereupon, utilize this characteristic can judge defect part and normal part.

For the decorative pattern shape defective that foreign matter is arranged on the film, owing to be attended by concave-convex surface, so optical reflectivity also changes simultaneously with the elliptic polarization optical parameter.At this moment make the variation of the variation of elliptic polarization optical parameter and reflectivity intensity combined, just can judge defective and normal part.In addition, because the kind difference of defective is combined by catoptrical Strength Changes and elliptic polarization are changed in order to reproduce this combination, can judge the size and the kind of defective.

Ellipsometers normally utilizes a plurality of light receiving elements to ask for the device that each point is gone up on the surface., present inventors have designed the device that utilizes two-dimentional imaging apparatus.When measuring the elliptic polarization optical parameter be examined the surface on a large scale or intensity of reflected light, the surface of target object is divided into some optical systems, imaging in two-dimentional photography element.In the mensuration of elliptic polarization optical parameter or light intensity, utilize the intensity of measuring with the same position corresponding elements on determined surface to calculate the light intensity of measuring by a plurality of photography elements.By revising optical system, if obtain the intensity of reflected light of same reflection spot, then carry out scanning with single optical measurement instrument, can simplify optical system.

In addition, light source has the bigger light sources of output power such as LASER Light Source.With a LASER Light Source and several ellipsometers, when measuring large-scale ellipsometric parameter, can utilize optical fiber to make and disperse irradiation, make the exposure intensity on the each several part of the big material of width become evenly easy compensatory reflex light intensity from the light of common light source.

First embodiment of the present invention has been shown among Fig. 1.

The change shape of polarized light parameter when Fig. 1 represents to adhere on the cold-rolled steel sheet oxide film of 5nm～100nm.Fig. 1 is that general polarized light is resolved usefulness " Δ-ψ figure ", and transverse axis is the angle ψ of expression P, S polarized light amplitude ratio, and the longitudinal axis is the phase difference of P, S polarized light, and the reference numerals on the curve is represented the oxide thickness with other device mensuration.Condition determination is to be the He-Ne laser instrument of 633nm with wavelength, measure with incident angle be 70 spend, be that to have refractive index on the steel plate of 2.0+i4.0 be 3.0 oxide film in complex index.

In Fig. 1, be about 20～50nm at oxide thickness, can think the variation of ψ, but, mainly be the variation of Δ that ψ changes hardly at 0～20nm and 50～100nm.Therefore, when being 0～20nm or 50～100nm,, also just observing ψ and can not detect even to want with the membrane thickness unevenness be that defective is carried out scanning as the range of control of oxide thickness.Therefore, the present invention asks for ψ, Δ simultaneously, utilizes the large-scale oxide thickness of its relational expression evaluation.For example, ψ near 35 degree and also Δ from 100 degree to scope that 250 spend the time, use with thickness corresponding two lines from 50nm to 10nm and from 0nm to 20nm and convert.The normal range of thickness is stipulated its range of control according to the kind of steel, thickness etc., and the part that the thickness of film is runawayed detects as defective.

Second embodiment of the present invention is shown in Fig. 2 to Fig. 4.

Fig. 2 represents to detect the example of A type defective in the decorative pattern shape defective.Defective is the spectral line shape extends, and makes horizontal central authorities among this spectral line arrival figure, and shows corresponding to width position for the elliptic polarization optical parameter and the intensity of reflected light of 20nm scope wide.If the phase differential (Δ) and the intensity (I) of defect part are compared with normal part (part beyond the lateral center part), then are difficult to judge the existence of defective., amplitude ratio (ψ) can determine defective part (middle body) and zero defect part (beyond the middle body) significantly.This defective is a protective oxide layer thin excessively on the surface, this be with existing optical detection device detection less than defective.

Fig. 3 represents to detect the example of Type B defective in the decorative pattern shape defective.Can not judge the existence of defective with ψ, but to phase differential (Δ) and intensity (I) sensitivity.The Type B defective is many to be occurred when surface of steel plate smooth finish has subtle change.Its reason is caused by the roller surface local roughness.

Fig. 4 represents to detect the example of C type defective in the decorative pattern shape defective.Under the situation of this defective, all responsive to the whole parameters of ψ, Δ and I.C type defective is owing on decorative pattern shape defective attachment is arranged, and causes the apparent smooth finish defective that great changes will take place of surface of steel plate.The visual attachment that also can see also can detect with existing testing fixture.

To shown in Figure 4, with the difference of defect kind, the intensity of reflected light of following that has changes the no this variation that has as Fig. 2.Along with the difference of the kind of defective, the change shape of elliptically polarized light parameter value is also different in addition.

One of device of defect kind example is judged in next explanation.Because light intensity, ψ, Δ respectively are worth localized variation sometimes, so be difficult to try to achieve absolute value.Therefore, can measure the moving average of each parameter, and detect the variation of mean value.Make the constant of moving average consistent with the flaw size of generation.When detecting the variation more than the certain size,, estimate the variable quantity of mean value for intensity of reflected light for the absolute value of elliptically polarized light parameter evaluation angle.The absolute value of ψ, Δ and the variable quantity of reflection strength constitute three dimensions.Rule of thumb rule is carried out interval division to this three dimensions, makes each interval corresponding with the kind and the grade of defective.To have concomitant defective to divide in groups in some intervals, also available grades be represented the interval.

The elliptically polarized light parametric measurement device has various variations with the difference of optical system.Present inventors had originally designed such optical system, promptly by obtaining catoptrical 4 polarized light components, can not only know elliptic polarization optical parameter (ψ, Δ), and can know the absolute value of phasing degree Δ, and can also compensate the variation (opening flat 5-113371 communique) of incident intensity referring to the spy.Utilize the third embodiment of the invention of any one optical system formation surface defect detection apparatus of wherein design to be shown in Fig. 5.

Surface defect detection apparatus among Fig. 5 is made of following each several part: ellipsometers main body 1, calculate the elliptic polarization optical parameter arithmetic unit 3 of elliptic polarization optical parameter according to its output, store the elliptic polarization optical parameter memory storage 4 of its elliptic polarization optical parameter when using defective sample 2, the elliptic polarization optical parameter comparison means 5 that during sample 2 of operating characteristic the unknown the defect characteristics value of storage in its elliptic polarization optical parameter and the memory storage 4 is compared, and the flaw indication output unit 6 that the grade etc. of zero defect and defective is arranged according to comparative result output.

Ellipsometers main body 1 for example is made of optical system shown in Figure 6.In Fig. 6, the 10th, LASER Light Source, the 11st, polarizer, 12 expression incident lights.Incident light 12 reflects on the surface of sample 2 after becoming linearly polarized light by polarizer 11.Reflected light 13 is separated into different 4 bundle polarized light 18a, 18b, 18c, 18d by beam splitter 14,15,16 and 1/4 wavelength plate 17, and detects its light intensity I by optical receiver 19a, 19b, 19c, 19d separately ₁, I ₂, I ₃, I ₄

Elliptic polarization optical parameter arithmetic unit 3 utilizes (3) formula and (4) formula to calculate the elliptic polarization optical parameter according to these light intensity.

tanΔ＝〔σ _R(I ₁-I ₂)〕/〔σ _T(I ₃-I ₄)〕 (3)

tanψ＝〔(σ _R ²-σ _T ²)/2〕·〔{σ _R(I ₁-I ₂)} ²〕+〔{σ _T(I ₃-I ₄)} ²〕 ^1/2÷〔σ _R ²(I ₁+I ₂)-σ _T ²(I ₃+I ₄)〕 (4)

σ in the formula Chinese style _R, σ _TBeing respectively the P polarized light of no polarization beam splitter 14 and the amplitude reflectivity ratio and the amplitude transmissivity ratio of S polarized light, is the intrinsic value of this optics.

Use when being provided with the sample 2 of defective in advance its elliptically polarized light parameter characteristic of storage in elliptic polarization optical parameter memory storage 4.For example store the characteristic of oxide film shown in Figure 1.

Elliptic polarization optical parameter comparison means 5 compares with the characteristic of measuring in advance and storing after obtaining to have the elliptic polarization optical parameter of sample 2 of unknown characteristics.Wherein can use 2 dimension interval division processing of ψ, Δ etc.Export the thickness signal thus.

Whether qualified flaw indication output unit 6 preestablish thickness determinating reference, is judged to be normally when thickness is in specialized range, and when the overshoot scope, be judged to be unusually, and output alarm signal.

The 4th embodiment of the present invention is shown in Fig. 7.Fig. 7 represents to apply the present invention to the opticator in the device on the steel plate pipeline.The optical system of present embodiment has the system that asks for the elliptic polarization optical parameter, and the system that asks for intensity of reflected light.In the present embodiment, owing to the incident light intensity is evenly distributed in the each several part of sample, time to time change not, thus can in two systems, obtain catoptrical three polarized light components, and obtain catoptrical intensity (I) and elliptic polarization optical parameter (ψ, Δ) by these computings.

At first in the elliptically polarized light parameter system, after the light that sends from high briliancy light source 20 becomes polarized light by polarizing plate 23, be radiated on the surface of sample 2.Separate two cross polarization light components at 45 and-45 ° from the reflected light on surface by Wo Lante (ウ オ-ラ Application ト) prism 26, and measure intensity of polarization light on each pixel by the gamma camera B that uses the two-dimensional CCD element.Gamma camera B adopts the different piece difference imaging mode at a CCD gamma camera.This also can be divided into two gamma cameras and separate photography respectively by the change optical system.The light intensity of gamma camera B is exported to this not shown elliptic polarization optical parameter arithmetic unit, by calculating this two light intensity, just can obtain the elliptic polarization optical parameter of specimen surface each point.

Secondly the system of intensity of reflected light is measured in explanation.The light that sends from high briliancy light source 20 is radiated on the surface of sample 2 after by diffusion disk 21 intensity evenly being distributed.Reflected light from the surface reflects on the surface of unpolarized prism 25, after the process polarization angle is set at the polarizer 24 of 0 degree, enters gamma camera A27.In gamma camera A, use the two-dimensional CCD element, obtain simultaneously and measure the light intensity that each point is gone up on the surface.Under the situation of optical system shown in Figure 7, intensity of reflected light (I) can be by I=I ₂+ I ₃-2I ₁Try to achieve.I in the formula ₁Be the light intensity of trying to achieve according to the polarized light image among the gamma camera A, I ₂, I ₃Be respectively to spend the light intensity that polarized light image are tried to achieve according to the degree of 45 among the gamma camera B and-45.

The feature of the optical system among Fig. 7 is, shines big scope equably with polarized light, and can be the images of 0 degree, 45 degree ,-45 degree according to polarization angle, obtains the elliptic polarization optical parameter and the intensity of reflected light of many points on the specimen surface simultaneously.The output of elliptic polarization optical parameter compares by the figure with storage, is converted into thickness and defect kind.

Fig. 8 is the signal processing system figure that uses simultaneously in the device of intensity of reflected light and elliptically polarized light parameter detecting defective.This device is equivalent to the output of optical system among Fig. 7 is carried out the part of signal Processing.

Temporarily be stored in frame memory A31 and the B31 from the signal of gamma camera A, gamma camera B output.Frame memory B is storing the image of two polarization angle, so add up with the frame memory A that stores light intensity, can provide 3 intensity signals altogether to the same point on the specimen surface.At this moment, because difference with field-of-view angle, Δ, ψ, I produce offset in frame memory, therefore the image of 3 polarized light components of catching in 32 pairs of frame memories of position proportional chi correcting device is handled, make its with the position of trying to achieve according to the fresnel coefficient of optical system in proportion chi overlap.Then, each pixel after Δ, ψ, 33 pairs of above-mentioned coincidences of I calculation element carries out Δ, ψ, I calculate.But the equivalence plural number is penetrated rate calculation element 35 is calculated the sample each point by the Δ that calculates from reflected light, ψ, I according to the polarization of incident light state equivalent complex index.These operation results are presented on the display device 36 as surface state through after the suitable conversion process.Also can be simply compare with the past data of Δ, ψ, I image.

Fig. 9 is the example that Fig. 2 is carried out conversion process to defective shown in Figure 4.Fig. 9 a is a suitable process decision chart after intensity of reflected light I rises from normal value.When Δ, ψ are arranged in the oblique line part of figure, corresponding with the grade 1,2,3 of D type defective.Fig. 9 b is applicable to that intensity of reflected light is the situation of normal value.Corresponding to Δ, ψ value, the type of A and B and grade are distributed as the oblique line part.Equally, Fig. 9 c, Fig. 9 d are applicable to the situation after intensity of reflected light descends from normal value.At this moment without Δ, ψ value, only press the type and the grade of the difference allocated defect of light intensity.

Figure 10 represents the 5th embodiment of the present invention with the configuration arranged side by side of many radio frequency channels ellipsometers.The purposes of this device is to be that the wide cut steel plate 40 of 2000mm divides with maximum line velocity 600m/ and detects defective in the moving process at width.Light source is that wavelength is the laser instrument 41 of 800nm, with optical fiber 42 this light is directed to determined near surface.Incident light becomes the linearly polarized lights of 45 degree after by polarizing plate 43.The incident angle that arrives surface of steel plate is 65 degree.Also can replace optical fiber, make laser become the slit-shaped directional light, shine on the steel plate with parabolic mirror.Light detects according to resembling machine 44,45,46 and uses the one dimension CCD of 1024 pixels to constitute, and its lateral resolution is 0.25mm, and 1 radio frequency channel can be observed the width of the 250mm on the steel plate.

Pick up head 1～8 is equipped with image processing apparatus respectively, carries out the calculating of intensity of polarization light with the average velocity of linear velocity.In order to improve processing speed, Δ, ψ, I arithmetic unit 33 are divided into 8 groups of parallel processings.When linear velocity is slow, when perhaps resolution is low, can increases parallel processing group number and reduce the charging floor number.These signals carry out the computing of elliptic polarization optical parameter in image processing apparatus 34 after, carry out determining defects with conversion display device 36.

Conversion process among this embodiment is when defective occurring in image, according to the combination that parameter among Δ, ψ, the I changes, carries out the judgement of defect kind.The size of defective then determines according to the situation of change of 98 ° of the Δ value of the Δ among Fig. 4 for example from about 113 ° of the Δ values of normal part to defect part.In Fig. 4, the value of Δ 2～3 ° with interior variation, belong to harmless defective, but when surpassing this value, be unallowable as the quality of dispatching from the factory, therefore report to the police as the unusual part.

On the steel plate of inspected object, during oiling,, also can measure the inhomogeneous state of oil film thickness because of as the basic function that ellipsometers had.

The foregoing description shows the situation that the light source of asking for any light intensity and the light source of asking for the elliptic polarization optical parameter adopt same light source.These light sources not necessarily must be same light sources, also can and ask for independent respectively setting of polarizing light source that the elliptic polarization optical parameter is used with the ordinary light source of asking reflected light to use.

Compare by the elliptically polarized light parameter value with storage, the detection of the decorative pattern shape defective on the non-detectable in the past surface of steel plate becomes possibility.Because elliptic polarization optical parameter and intensity of reflected light are combined, so the kind of decidable defective.Owing to adopted two-dimentional photography element, therefore constituted compact optical system.In addition, under the situation that is applied to the wide cut material, the light with optical fiber direct light source makes the light uniform irradiation, and available simple modification method is measured accurately.The 2nd embodiment:

Surface defect detection apparatus of the present invention is made of light projection part, light receiving part and signal processing.Light projection part incides parallel light beam and is examined on the surface.Light receiving part is separately positioned on the different light paths that is examined surface reflection, makes from the reflected light incident that is examined the surface, and is transformed into picture signal.This light receiving part is made of with three linear array transducers that each analyzer of reception sees through light three analyzers that have different orientations respectively.The signal processing part divisional processing is from the picture signal of these three linear array transducers, calculates amplitude reflectivity than the COS Δ of tan ψ, expression phase difference be examined the intensity of reflected light I on surface ₀, generate tan ψ image, COS Δ image and I ₀Image, and according to the tan ψ image, COS Δ image and the I that are generated ₀Each pixel concentration of image is estimated character of surface.

For example, light projection part is examined on the surface from polarized light being incided by polarizer along the parallel light source that is examined face width direction formation length, and receive from the reflected light that is examined the surface, detect unusual parts such as whether being examined on the surface defectiveness.

For example, light receiving part is made of 3 circuit sensing gamma cameras and the analyzer that is arranged on each circuit sensing gamma camera sensitive surface the place ahead, 3 analyzers are respectively with different position angle configurations, be that the axis of homology for example is respectively " 0 ", " π/4 ", " π/4 " with the angle that is examined the surface formation, 3 circuit sensing gamma cameras make by the polarized light incident of each analyzer exports the image that the expression intensity of polarization light distributes.

For example, signal processing is to the polarized light parameter on each pixel of image of the expression light distribution of exporting respectively from 3 circuit sensing gamma cameras, and promptly amplitude reflectivity is than the COS Δ and the surface reflection intensity I of tan ψ and expression phase difference ₀Calculate, generate the image of polarized light parameter, i.e. tan ψ image, COS Δ image and I ₀Image, whether consistent according to the light and shade on the unusual part of tan ψ image that is generated and COS Δ image, the classification of judgement unusual part, and according to I ₀The luminance variations situation of image is judged unusual size.

Figure 11, Figure 12 represent the structure of one embodiment of the present of invention, and Figure 11 is the optical system configuration composition, and Figure 12 is the block diagram of signal processing.As shown in figure 11, optical system 101 has light projection part 102 and light receiving part 103.Light projection part 102 has parallel light source 104 and is arranged on the polarizer 105 in parallel light source 104 the place aheads.Parallel light source 104 is by constituting along being examined the plane light source that style such as steel plate 106 Widths form length, parallel beam is radiated in the scope of certain-length on the surface of steel plate 106.Polarizer 105 for example is made of 1/4 wavelength plate, and it disposes as shown in figure 13, makes the angle α of the plane of incidence formation of axis of homology P and steel plate 106 ₁Be π/4.Light receiving part 103 has 3 circuit sensing gamma camera 107a, 107b, 107c, and analyzer 108a, the 08b, the 108c that are arranged on sensitive surface the place ahead of each circuit sensing gamma camera 107a, 107b, 107c.Circuit sensing gamma camera 107a, 107b, 107c dispose along the moving direction staggered positions of steel plate 1106, detect the reflected light from steel plate 106 surfaces, and it is transformed into the polarized light image signal.Analyzer 108a, 108b, 108c for example are made of 1/4 wavelength plate, and it disposes as shown in figure 13, the angle α that the plane of incidence of the axis of homology of analyzer 108 and steel plate 106 is constituted ₂Be respectively the α of analyzer 108a ₂=0, the α of analyzer 108b ₂=π/4, the α of analyzer 108c ₂=-π/4.

Signal processing 109 has CPU111, frame memory 112a, 112b, 112c that the elliptically polarized light parametric image is used that frame memory 110a, 110b, 10c, computing that polarized light image uses use and the CPU113 that handles usefulness.Among frame memory 110a, 110b, 110c, launch respectively from the polarized light image signal of circuit sensing gamma camera 107a, 107b, 107c output by two dimensional form.Computing considers that with CPU111 circuit sensing gamma camera 107a, 107b, 107c are provided with the skew of position, from frame memory 110a, 110b, 110c, read the polarized light image signal of the same position of steel plate 106, and be amplitude reflectivity than tan ψ and the COS Δ of expression phase difference and the surface reflection intensity I of steel plate 106 the polarized light parameter on each pixel ₀Calculate, the image that generates the polarized light parameter is tan ψ image, COS Δ image and I ₀Image.By tan ψ image and COS Δ image and the I of computing with CPU111 calculating ₀Image launches in frame memory 112a, 112b, 112c.Processing according to the tan ψ image that launches and the light and shade of COS Δ image, is judged the kind of defective with CPU113 in frame memory 112a, 112b, 112c, and according to I ₀The luminance variations situation of image is judged the size of defective.

Before the action of the surface examining device that explanation as above constitutes, at first explanation is calculated the surface reflection intensity I of amplitude reflectivity than tan ψ, COS Δ and steel plate 106 according to the light intensity that is detected by 3 circuit sensing gamma camera 107a, 107b, 107c ₀Principle.

As shown in figure 13, as establish the angle that the plane of incidence of the axis of homology A of the axis of homology P of polarizer 105 and analyzer 108 and steel plate 106 constitutes and be respectively α ₁, α ₂, then incide on the steel plate 106 the light intensity I (α after P polarized light component after the reflection and S polarized light component synthesize by analyzer 108 with any incident angle i ₁, α ₂) represent with following formula, and the amplitude reflectivity of establishing P component and S component is respectively γ _P, γ _SI(α ₁·α ₂)＝|E _ocosα ₁·r _pcosα ₂+E _osinα ₁·r _ssinα ₂| ²

＝I _oR _p〔cos ²α ₁·cos ²α ₂+ρ ²sin ²α ₁·sin ²α ₂

+ (1/2) sin 2 α ₁Sin2 α ₂The cos Δ) I in the formula _o=| E _o| ², r _p= R _pExp (i  _p), r _s= R _sExp (i  _s) ρ=r _s/ r _p=tan ψ, Δ= _s- _pHere, work as α ₁α is passed through in=π/4 o'clock ₂The light intensity I of=0 analyzer 108a ₁Become I ₁=I ₀R _P/ 2, pass through α ₂The light intensity I of the analyzer 108b of=π/4 ₂Become I ₂=I _oR _p(1+ ρ ²+ 2 ρ COS Δs)/4, pass through α ₂The light intensity I of the analyzer 108c of=-π/4 ₃Become I ₃=I ₀R _P(1+ ρ ²-2 ρ COS Δs)/4.According to these light intensity I ₁, I ₂, I ₃Can be by following various tan ψ, COS Δ and the surface reflection intensity I of obtaining respectively ₀ $\tan \mathrm{\Ψ}=\sqrt{\frac{I_1}{I_2+I_3-I_1}}$ $\cos \mathrm{\Δ}=\frac{I_2-I_3}{2I_1}\tan \mathrm{\Ψ}$

I ₀＝I ₂+I ₃-I ₁

With reference to the characteristics of signals figure among Figure 14, illustrate and use this tan ψ, COS Δ and surface reflection intensity I ₀Detect the action of the surface examining device of the defective on the steel plate 106.Penetrate the polarized light that the back is reflected at a distance of each position of certain intervals L from optical system 101 on the steel plate 106 that moves with certain speed, incide circuit sensing gamma camera 107a, 107b, 107c by analyzer 108a, 108b, 108c respectively.Promptly be separated by corresponding to the speed of steel plate 106 and the small mistiming of interval L, detect the pictures that same position is gone up on steel plate 106 surfaces.When detecting from the intensity of reflected light of steel plate 106 aspects, because the front of online sensing gamma camera 107a is provided with α with this line sensing gamma camera 107a, 107b, 107c ₂=0 analyzer 108a is so circuit sensing gamma camera 107a detects above-mentioned light intensity I ₁, owing to be provided with α in the front of circuit sensing gamma camera 107b ₂The analyzer 108b of=π/4 is so circuit sensing gamma camera 107b detects above-mentioned light intensity I ₂, owing to be provided with α in circuit sensing gamma camera 107c front ₂The analyzer 108c of=-π/4 is so circuit sensing gamma camera 107c detects above-mentioned light intensity I ₃The light intensity I that expression detects with circuit sensing gamma camera 107a, 107b, 107c ₁, I ₂, I ₃The image that distributes launches in frame memory 110a, 110b, 110c respectively.Like this, detect light intensity I with circuit sensing gamma camera 107a, 107b, 107c ₁, I ₂, I ₃The time, pass through α ₂=0 analyzer 108a incides the light intensity I of circuit sensing gamma camera 107a ₁Be approximately the light intensity I that incides circuit sensing gamma camera 107b, 107c ₂, I ₃2 times.Therefore, the sensitivity that makes line sensing gamma camera 107a is 1/2 of circuit sensing gamma camera 107b, 107c sensitivity, and just can generate with roughly the same concentration in frame memory 110a, 110b, 110c be the image of benchmark.

Computing considers that with CPU111 circuit sensing gamma camera 107a, 107b, 107c are provided with the skew of position, read out in generate among frame memory 110a, 110b, the 110c by light intensity I ₁, I ₂, I ₃The polarized light image signal of decision, and calculate expression amplitude reflectivity on each pixel successively than the COS Δ and the surface of steel plate intensity of reflected light I of tan ψ and phase difference ₀, in frame memory 112a, generate tan ψ image, in frame memory 112b, generate COS Δ image, in frame memory 112c, generate I ₀Image.When generating these images, conversion is carried out by 0～255 gray shade scale in about tan ψ=0～2 of each pixel and COS Δ=-1～1.For example, in COS Δ image, when normal partial C OS Δ=0,, then in COS Δ image, form the big image of the normal part concentration of unusual part concentration ratio as COS Δ=-1 of unusual part.Here, when calculating the surface reflection intensity I of expression amplitude reflectivity than the COS Δ and the steel 106 of tan ψ and phase difference ₀The time, the sensitivity that makes circuit sensing gamma camera 107a be circuit sensing gamma camera 107b, 107c sensitivity 1/2 after, as to establish the light intensity that detects with circuit sensing gamma camera 107a be I ₁, then tan ψ and COS Δ and I ₀By following various calculating. $\tan \mathrm{\ψ}=\sqrt{\frac{I_1}{I_2+I_3-2I_1}}$ I ₀＝I ₂+I ₃-2I ₁ $\cos \mathrm{\Δ}=\frac{I_2-I_3}{2I_1}\sqrt{\frac{I_2+I_3-2I_1}{I_1}}$

Processing is with tan ψ image, COS Δ image and the I of CPU113 to generating in frame memory 112a, 112b, 112c ₀The concentration of each pixel of image is carried out tint correction, and the concentration with normal part is that benchmark carries out standardization then, and carries out the conversion process of concentration level nature.According to this tan ψ image, COS Δ image and I ₀The variation of the concentration level nature of image, the kind and the size thereof of judgement unusual part.

For example, polarized light is incided on the steel plate 106 that the speed of dividing with 300m/ moves from light projection part 102 with the incident angles of 60 degree, make and check that line is spaced apart L=100mm, detect light intensity I with circuit sensing gamma camera 107a, 107b, 107c ₁, I ₂, I ₃And the image that launches in frame memory 110a, 110b, 110c is shown in Figure 14 (a).In addition, according to the light intensity I that generates by frame memory 110a, 110b, 110c ₁, I ₂, I ₃The polarized light image of decision is calculated tan ψ image, COS Δ image and the I that generates by computing with CPU111 ₀Image is shown in Figure 14 (b).Here, in the image shown in Figure 14 (a) and (b), intensity variation part 121 presentation surfaces shown in the drawing middle body have concavo-convex defective, decorative pattern shape defectives such as the light intensity changing unit 122 expression greasy dirts on the right.Shown in Figure 14 (b), the normal part of the concentration ratio of unusual part becomes very big in COS Δ image.Concentration with normal part is benchmark, with tan ψ image, COS Δ image and I ₀Concentration level nature after the concentration standardization of each pixel of image is shown in Figure 14 (c).Shown in Figure 14 (c), the concentration level of the tan ψ image of concavo-convex defective 121 becomes positive, the concentration level of COS Δ image becomes negative, but the part of decorative pattern shape defectives 122 such as greasy dirt, the concentration level of the concentration level of its tan ψ image and COS Δ image all is negative.Therefore, can judge the kind of defective according to the light and shade of tan ψ image and the light and shade of COS Δ image.In addition, can be according to I ₀The intensity of variation of the concentration level of image, the size of judgement defective.

The foregoing description has illustrated the situation that constitutes the light source 104 of light projection part 102 with a plane light source, but shown in the side view among Figure 15, also can adopt, 3 linear light source 104a, 104bs of separated by a distance configuration corresponding, 104c, send the polarized light that the back is reflected on steel plate 106 surfaces and receive from each linear light source 104a, 104b, 104c with corresponding circuit sensing gamma camera 107a, 107b, 107c with 3 circuit sensing gamma camera 107a, 107b, 107c.

In addition, the various embodiments described above have illustrated the situation that is staggered and dispose with respect to steel plate 106 moving directions in the position of the circuit sensing gamma camera 107a of light receiving part 103,107b, 107c, but shown in vertical view and the side view among Figure 17 among Figure 16, also circuit sensing gamma camera 107a, 107b, 107c can be arranged on same the straight line with steel plate 106 moving direction quadratures, and be positioned at sustained height, detect reflected light simultaneously from same position on the steel plate 106 with circuit sensing gamma camera 107a, 107b, 107c.And under the situation that enough spaces are arranged,, can avoid the depth of field problem on the picture by on circuit sensing gamma camera 107a, 107b, 107c, adopting long focal length lens.In addition, according to circumstances, circuit sensing gamma camera 107b, the 107c that also can make the circuit sensing gamma camera 107a both sides that are arranged on the center with certain angle towards the inboard.

The foregoing description has illustrated and has been arranged on circuit sensing gamma camera 107a, 107b, 107c on the same straight line with the moving direction quadrature of steel plate 1106 and is positioned at sustained height, but as shown in figure 18, also can change the height that is provided with of circuit sensing gamma camera 107a, 107b, 107c, detect reflected light simultaneously from the same position of steel plate 106.

In addition, the various embodiments described above have illustrated that the polarized light that sends from light projection part 102 is directly incident on the surface of steel plate 106, and with circuit sensing gamma camera 107a, 107b, 107c directly receives its catoptrical situation, but as shown in figure 19, also can make the light that sends with respect to the Surface Vertical of steel plate 106 from parallel light source 104, after catoptron 114 reflections, by polarizer 105, incident angle with regulation incides on the surface of steel plate 106, make its reflected light by analyzer 108a again, 108b, behind the 108c, with catoptron 115 reflection, and the circuit sensing gamma camera 107a that uses the surperficial quadrature with respect to steel plate 106 to be provided with, 107b, 107c receives.By such formation light projection part 102 and light receiving part 103, can reduce the space that is provided with of optical system 101, and can improve the degree of freedom of online setting.In addition, in the above-described embodiments, polarizer 105 is arranged on the rear side of catoptron 114, and analyzer 108a, 108b, 108c are arranged on the front side of catoptron 115, make polarized light not be subjected to the influence of catoptron 114,115, but also polarizer 105 can be located at the front side of catoptron 114 and analyzer 108a, 108b, 108c are located at the rear side of catoptron 115 and the influence of compensatory reflex mirror 114,115.

In addition, the various embodiments described above illustrated with circuit sensing gamma camera 107a, 107b, 107c detect respectively with steel plate 106 moving direction cross lines on the situation of image, but also can use the two-dimensional CCD gamma camera to detect the image every certain-length of steel plate 106.

As mentioned above, the present invention is incided parallel light beam to be examined on the surface, detection is by being separately positioned on the different light paths that is examined surface reflection and the light distribution of polarized light of 3 analyzers of different orientations being arranged, and the polarized light parameter of calculating on each pixel on the image that expression detects light distribution is COS Δ and the surface reflection intensity I of amplitude reflectivity than tan ψ and expression phase difference ₀, the image that generates the polarized light parameter is a tan ψ image, COS Δ image and I ₀Image, and whether consistent according to the light and shade of unusual part in the tan ψ image that is generated and the COS Δ is judged the kind of unusual part, according to I ₀The luminance variations situation of image is judged unusual degree, therefore can detect accurately with simple structure and be examined lip-deep defective or greasy dirt etc.

Can detect the defective that is examined the surface etc. apace owing to need not carry out adjustments such as polarized light angle, so On line inspection is made and the surface of the lamellar goods of conveying continuously continuously.Embodiment 3:

Surface examining device of the present invention is characterised in that: light projection part is arranged, the specular light test section, test section and signal processing diffuse, light projection part incides polarized light and is examined on the surperficial whole Width, the specular light test section is arranged on the specular light light path that is examined surface reflection, the test section that diffuses is arranged on the light path that diffuses that is examined surface reflection, on the specular light test section and the light path that diffuses, any one has the optical system that the light of incident is separated into 3 light beams at least in the specular light test section and the test section that diffuses, and be separately positioned on 3 separated beam path and the analyzer of different orientations is arranged respectively, and receive the imaging device that each analyzer sees through light, signal processing will compare from the picture signal of the specular light test section and the test section that diffuses, simultaneously to handling through the picture signal of 3 imaging devices of light from receiving analyzer, the elliptic polarization optical parameter that calculating is examined surface reflection is the COS Δ of amplitude reflectivity than tan ψ and expression phase difference, and, estimate the character of surface that is examined the surface according to specular light and the comparative result that diffuses and two elliptically polarized light parametric t an ψ and COS Δ.

The surface examining device of the 2nd invention is characterised in that: identical with the 1st invention, light projection light branch, specular light test section and the test section that diffuses are arranged, in signal processing, the picture signal from the specular light test section and the test section that diffuses is compared, be amplitude reflectivity than the COS Δ of tan ψ and expression phase difference and be examined the intensity of reflected light I on surface handling from receiving the picture signal that analyzer sees through 3 imaging devices of light, calculating the elliptic polarization optical parameter that is examined surface reflection simultaneously ₀, and according to specular light and the comparative result that diffuses and two elliptically polarized light parametric t an ψ and COS Δ and surface reflection intensity I ₀, estimate the character of surface that is examined the surface.

The surface examining device of the 3rd invention is characterised in that: have light projection part, light receiving part and signal processing, light projection part incides polarized light and is examined on the surperficial whole Width, light receiving part is arranged on the light path that diffuses that is examined surface reflection, and has the optical system that the light of incident is separated into 3 light beams, and be separately positioned on the light path of 3 separated light beams and the analyzer that has different orientations respectively, and receive the imaging device that each analyzer sees through light, signal processing is to handling through the picture signal of 3 imaging devices of light from receiving analyzer, the elliptic polarization optical parameter that calculating is examined surface reflection is the COS Δ of amplitude reflectivity than tan ψ and expression phase difference, and, estimate the character of surface that is examined the surface according to 2 elliptically polarized light parametric t an ψ that calculate and COS Δ.

The surface examining device of the 4th invention is characterised in that: identical with the 3rd invention, have light projection unit and light receiving part, in signal processing apparatus, be amplitude reflectivity than the COS Δ of tan ψ and expression phase difference and be examined the intensity of reflected light I on surface handling from receiving the picture signal that analyzer sees through 3 imaging devices of light, calculating the elliptic polarization optical parameter that is examined surface reflection ₀, and according to 2 elliptically polarized light parametric t an ψ, COS Δ and surface reflection intensity I calculating ₀, estimate the character of surface that is examined the surface.

In the present invention, the light projection unit is divided with respect to being examined surface configuration, so that polarized light is incided with certain incident angle to be examined on the surperficial whole Width, and reception is examined the specular light test section of the specular light in the surface reflection and receives the test section that diffuses that diffuses be examined in the surface reflection be configured in assigned position, and output terminal that will above-mentioned two kinds of optical detection parts branch is connected in signal processing.This specular light test section and diffuse in the test section at least any one, for example specular light test section is separated into the beam splitter of 3 light beams and 3 imaging devices and analyzer by the light with incident and constitutes.Imaging device is made of linear array gamma cameras such as for example CCD, between beam splitter and each camera respectively with different orientations configuration, that is, the angle that the axis of homology and the plane of incidence that is examined the surface are constituted for example is respectively 0, π/4 ,-π/4.3 imaging devices make the polarized light incident by each analyzer, the picture signal that output expression intensity of polarization light distributes.

Signal processing will compare with the picture signal that diffuses from the specular light of the specular light test section and the test section input that diffuses, detection is examined defectives such as lip-deep longitudinal crack, simultaneously to handling through the picture signal of 3 imaging devices of light from receiving analyzer, the elliptic polarization optical parameter that calculating is examined surface reflection is the COS Δ of amplitude reflectivity than tan ψ and expression phase difference, according to 2 elliptically polarized light parametric t an ψ, the variation of COS Δ, detection is examined the variation of character of surface, whether promptly detection is examined the surface has physical parameter inhomogeneous, there are so-called decorative pattern shape defectives such as thin oxide film or coating film thickness be inhomogeneous in the small maldistribution of smooth finish, part.

The intensity of reflected light I that signal processing is calculated above-mentioned 2 elliptically polarized light parametric t an ψ and COS Δ and is examined the surface ₀, according to 2 elliptically polarized light parametric t an ψ, COS Δ and surface reflection intensity I ₀, detect the variation that is examined character of surface, and more carefully detection has or not decorative pattern shape defective.

As catoptrical test section, be provided with and detect the light receiving part that diffuses that is examined in the surface reflection, identical with above-mentioned situation, by signal processing according to the elliptically polarized light parametric t an ψ, COS Δ that are examined surface reflection or according to elliptically polarized light parametric t an ψ, COS Δ and surface reflection intensity I ₀, detecting the variation that is examined character of surface, detection has or not concavo-convex defective accurately.

Figure 20 is the optical system configurations figure of one embodiment of the invention.As shown in the figure, optical system 201 has light projection part 202, the specular light test section 203 and the test section 204 that diffuses.Light projection part 202 for example incides polarized light on the whole Width that is examined style such as steel plate 205 with the incident angle of i=60 degree, and light projection part 202 has light source 206 and is arranged on the polarizer 207 of light source 206 fronts.Light source 206 is club shaped structure, and rayed is being examined on 205 the whole Width of surface.Polarizer 207 is made of for example 1/4 wavelength plate, and shown in the configuration instruction figure among Figure 21, its configuration is the angle α that the plane of incidence became that makes axis of homology P and steel plate 205 ₁Be π/4.Specular light test section 203 receives from the specular light of steel plate 205 with reflection angle i reflection, and it has the beam splitter 208a, the 208b that for example are made of half-reflecting mirror, 208c, the linear array gamma camera 209a, 209b, the 209c that for example are made of CCD and analyzer 210a, 210b, the 210c that is arranged on linear array gamma camera 209a, 209b, 209c sensitive surface the place ahead.Analyzer 210a, 210b, 210c are made of for example 1/4 wavelength plate, as shown in figure 21, and the angle α that the plane of incidence of the axis of homology of analyzer 210 and steel plate 205 constitutes ₂Be such configuration, the i.e. α of analyzer 210a ₂=0, the α of analyzer 210b ₂=π/4, the α of analyzer 210c ₂=-π/4.The test section that diffuses receives from steel plate 205 with the diffusing of the reflection angle reflection of for example 0 degree, and it has the analyzer 210d that diffuses with linear array gamma camera 209d and be arranged on the usefulness linear array gamma camera 209d the place ahead that diffuses.Analyzer 210d also is made of for example 1/4 wavelength plate, and its configuration is the angle α that the plane of incidence of the axis of homology and steel plate 205 is constituted ₂Be pi/2.

Shown in the block diagram among Figure 22, diffusing of linear array gamma camera 209a, 209b, the 209c of specular light test section 203 and the test section 204 that diffuses all is connected in signal processing 211 with linear array gamma camera 209d.Signal processing 211 has frame memory 212a, 212b, 212c, the frame memory 212d of the usefulness that diffuses, arithmetic unit 213, tan ψ memory storage 214a, COS Δ memory storage 214b, the I that specular light is used ₀Memory storage 214c, parameter memory storage 215, parameter comparison means 216, scattered light comparison means 217 and output unit 218.Launch by each pixel respectively among frame memory 212a, 212b, 212c from the picture signal of linear array gamma camera 209a, 209b, 209c output.Among frame memory 212d, launch with the picture signal of linear array gamma camera 209d output from diffusing by each pixel.Arithmetic unit 213 is from the picture signal that frame memory 212a, 212b, 212c read the same position of steel plate 205 one by one, and the elliptic polarization optical parameter of calculating each pixel place is that amplitude reflectivity is than tan ψ and the COS Δ of expression phase difference and the surface reflection intensity I of steel plate 205 specular lights ₀, and deposit tan ψ memory storage 214a, COS Δ memory storage 214b and I respectively in ₀Among the memory storage 214c.In parameter memory storage 215, storing the character of surface of the steel plate 205 of trying to achieve in advance, the surface reflection intensity I of the pairing tan ψ of so-called decorative pattern shape defective, COS Δ and specular light such as promptly the small maldistribution of inhomogeneous, the smooth finish of physical parameter, the local thin oxide film that exists etc. or coating film thickness be inhomogeneous ₀Deng various characteristics.Parameter comparison means 216 to each pixel with tan ψ memory storage 214a, COS Δ memory storage 214b and I ₀The tan ψ that stores among the memory storage 214c, COS Δ and surface reflection intensity I ₀Compare with the characteristic of storing in advance in the parameter memory storage 215, and have or not decorative pattern shape defective and kind and size on the surface of judgement steel plate 205.Scattered light comparison means 217 is according to the surface reflection intensity I that diffuses ₀With the scattered light intensity I that stores among the frame memory 212d ₄, judge defective and sizes thereof such as having or not longitudinal crack on steel plate 205 surfaces.

Before the action of the surface examining device that explanation as above constitutes, the light intensity that detects according to 3 linear array gamma camera 209a, 209b, 209c at first is described, calculate the surface reflection intensity I of amplitude reflectivity than tan ψ, COS Δ and steel plate 205 specular lights ₀Principle.

As shown in figure 21, as establish the angle that the plane of incidence of the axis of homology A of the axis of homology P of polarizer 207 and analyzer 210 and steel plate 205 constitutes and be respectively α ₁, α ₂, then with any incident angle i incide the P polarized light component of steel plate 205 back reflections and S polarized light component by analyzer 210 the light intensity I (α after synthetic ₁, α ₂) be expressed from the next, and the amplitude reflectivity of establishing P component and S component is respectively γ _P, γ _SI(α ₁·α ₂)＝|E _ocosα ₁·r _pcosα ₂+E _osinα ₁·r _asinα ₂| ²

＝I _oR _p〔cos ²α ₁·cos ²α ₂+ρ ²sin ²α ₁·sin ²α ₂

+ (1/2) sin2 α ₁Sin2 α ₂The cos Δ) I in the formula _o=| E _o| ², r _p= R _pExp (i  _p), r _s= R _sExp (i  _s) ρ=r _s/ r _p=tan ψ, Δ= _s- _p

Here, work as α ₁α is passed through in=π/4 o'clock ₂The light intensity I of=0 analyzer 210a ₁Become I ₁=I ₀R _P/ 2, pass through α ₂The light intensity I of the analyzer 210b of=π/4 ₂Become I ₂=I ₀R _P(1+ ρ ²++ 2 ρ COS Δs)/4, α passed through ₂The light intensity I of the analyzer 210c of=-π/4 ₃Become I ₃=I ₀R ^P(1+ ρ ²-2 ρ COS Δs)/4.According to these light intensity I ₁, I ₂, I ₃With following various tan ψ, COS Δ and the surface reflection intensity I of trying to achieve ₀ $\tan \mathrm{\Ψ}=\sqrt{\frac{I_1}{I_2+I_3-I_1}}$ I ₀＝I ₂+I ₃-I ₁ $\cos \mathrm{\Δ}=\frac{I_2-I_3}{2I_1}\tan \mathrm{\Ψ}$

Secondly explanation utilizes the action of the surface examining device of above-mentioned principle.Send and the polarized light that carries out direct reflection on the surface of the steel plate 205 that moves with certain speed incides linear array gamma camera 209a, 209b, 209c after respectively by analyzer 210a, 210b, 210c from light projection part 202.With linear array gamma camera 209a, when 209b, 209c detect the light intensity of specular light, because α ₂=0 analyzer 210a is arranged on the front of linear array gamma camera 209a, so linear array gamma camera 209a detects light intensity I ₁, because α ₂The analyzer 210b of=π/4 is arranged on the front of linear array gamma camera 209b, so linear array gamma camera 209b detects light intensity I ₂, because α ₂The analyzer 210c of=-π/4 is arranged on the front of linear array gamma camera 209c, so the linear array gamma camera detects light intensity I ₃Expression light intensity I by linear array gamma camera 209a, 209b, 209c detection ₁, I ₂, I ₃The image that distributes launches in frame memory 212a, 212b, 212c respectively.Simultaneously, use the scattered light intensity I on steel plate 205 surfaces of line sensor 209d detection by diffusing ₄In frame memory 212d, launch.

Arithmetic unit 213 reads out in the light intensity I that launches among frame memory 212a～212c by each pixel ₁, I ₂, I ₃, calculate the surface reflection intensity I of amplitude reflectivity successively than tan ψ, COS Δ and specular light ₀, and deposit tan ψ memory storage 214a, COS Δ memory storage 214b and I respectively in ₀Among the memory storage 214c.Parameter comparison means 216 will be stored in tan ψ memory storage 214a, COS Δ memory storage 214b and I by each pixel ₀Tan ψ among the memory storage 214c, COS Δ and surface reflection intensity I ₀Compare with the characteristic that is stored in the parameter memory storage 215 in advance, judge on steel plate 205 surfaces to have or not decorative pattern shape defective and kind and size.On the other hand, scattered light comparison means 217 is by each pixel, with the scattered light intensity I that stores among the frame memory 212d ₄With I ₀Deposit the surface reflection intensity I of storing among the device for storing 214c ₀Compare, judge concavo-convex defective and sizes thereof such as having or not longitudinal crack on steel plate 205 surfaces.The result of determination of this parameter comparison means 216 and scattered light comparison means 217 is exported to pen recorder and display device (not shown) successively from output unit 218, so that know whether the surface of steel plate 205 is unusual.

Like this owing to when the surface of detecting steel plate 205 has or not decorative pattern shape defective and kind and size, can detect no concave-convex defective and size thereof, thus can be rapidly and the surface of detecting steel plate 205 accurately have no abnormal.For example with do not consider tan ψ, COS Δ and surface reflection intensity I ₀Situation in the past compare, the accuracy of detection of slight decorative pattern shape defective can be brought up to about 95% from about 70%, simultaneously slight concavo-convex defective also can be brought up to 99% this very high degree from original about 80%.

The foregoing description has illustrated the situation that 3 linear array gamma camera 209a, 209b, 209c are set in the specular light test section 203, but as shown in figure 23, even use the inner 3 eyeglass formula linear array gamma cameras 220 that beam splitter 208,3 analyzer 210a, 210b, 210c and 3 linear array transducer 219a, 219b, 219c are housed, the same with the foregoing description, also can detect the decorative pattern shape defective and the various defective on steel plate 205 surfaces.By making specular light test section 203 integrated, can improve the degree of freedom that the space is set like this.

The situation that analyzer 210d is arranged on the test section 204 that diffuses has been described in the above-described embodiments, even but remove analyzer 210d, the same with the foregoing description, still can detect concavo-convex defective and decorative pattern shape defective on the steel plate 205 accurately.

The various embodiments described above have illustrated one diffused and have been arranged on situation in the test section 204 that diffuses with linear array gamma camera 209d, but as shown in figure 24, the analyzer 210d that also can be pi/2 with the position angle uses linear array gamma camera 209d with diffusing, and the position angle is that the 0 analyzer 210e that spends is arranged in the test section 204 that diffuses with linear array gamma camera 209e simultaneously with diffusing, with beam splitter 221 will diffuse be separated into 2 bundles after, detect with linear array gamma camera 209e with diffusing with linear array gamma camera 209d with diffusing again.Like this by detect with the test section 204 of diffusing by the position angle be pi/2 analyzer 210d light intensity and be the light intensity of the analyzer 210e of 0 degree by the position angle, compare with the situation of the foregoing description, can improve the accuracy of detection that concavo-convex defective is gone up on steel plate 205 surfaces to a certain extent.

As shown in figure 25, also can be in the specular light test section 203 and test section 204 two parts that diffuse the inner 3 eyeglass formula linear array gamma cameras 220 that beam splitter 208 and 3 analyzer 210a, 210b, 210c and 3 linear array transducer 219a, 219b, 219c are housed of configuration.At this moment, elliptically polarized light parametric t an ψ, COS Δ and the surface reflection intensity I that can obtain specular light and diffuse ₀, and can detect the defective of all kinds accurately.

When mainly detecting the lip-deep concavo-convex defective of steel plate 205 when limiting purposes to a certain extent, as shown in figure 26,3 eyeglass formula linear array gamma cameras 220 can be configured in the test section 204 that diffuses, with the position angle is that analyzer 210d and a linear array gamma camera 209 of pi/2 is configured in the specular light test section 203, perhaps as shown in figure 27, also can only in the test section 204 that diffuses, dispose 3 eyeglass formula linear array gamma cameras 220.Utilize this structure, though the accuracy of detection of the concavo-convex little broken line of decorative pattern shape has reduction to a certain degree, owing to can obtain the elliptically polarized light parametric t an ψ, COS Δ and the surface reflection intensity I that diffuse ₀Therefore, can improve the accuracy of detection of concavo-convex defective.In addition, the 203 set position angles, specular light test section among Figure 26 are that the analyzer 210d of pi/2 preferably is used in steel plate 205 and is the occasion of oiling material, also can not save when not being the oiling material.

The situation that adopts club shaped structure as light source 206 has been described, but also available lens or parabolic mirror will be from the linearly ejaculations of the light of LASER Light Source in the various embodiments described above.

The various embodiments described above have illustrated according to catoptrical elliptically polarized light parametric t an ψ, COS Δ and surface reflection intensity I ₀, detect the situation that steel plate 205 surfaces have or not decorative pattern shape defective and concavo-convex defective, but, also can detect the character of surface of steel plate 205 according to catoptrical elliptically polarized light parametric t an ψ, COS Δ with the difference of the kind of decorative pattern shape defective.

As mentioned above, the present invention is examined on the surperficial whole Width with respect to being examined surperficial polarized light being incided with certain incident angle, reception is from being examined surperficial specular light and diffusing, specular light and the picture signal that diffuses are compared, detection is examined lip-deep concavo-convex defective, simultaneously according to specular light and at least one the picture signal of diffusing among both, calculating is examined the elliptic polarization optical parameter of surface reflection and promptly represents the COS Δ of amplitude reflectivity than tan ψ and phase difference, according to 2 elliptically polarized light parametric t an ψ, the variation of COS Δ, detection is examined and has or not decorative pattern shape defective on the surface, therefore can detect rapidly and be examined the surface and have no abnormally, and can on-line continuous ground detect the surface state of the lamellar products of this class such as steel plate.

By calculating above-mentioned 2 elliptically polarized light parametric t an ψ and COS Δ, and the intensity of reflected light I that is examined the surface ₀, and according to 2 elliptically polarized light parametric t an ψ, COS Δ and surface reflection intensity I ₀, detect the characteristic variations that is examined the surface, can have or not various decorative pattern shape defectives with higher accuracy detection.

In addition, by obtain elliptically polarized light parametric t an ψ, COS Δ according to diffusing, perhaps obtain elliptically polarized light parametric t an ψ, COS Δ and surface reflection intensity I ₀And detect the variation that is examined surperficial characteristic, can detect accurately and be examined upward irregular defective of surface.Embodiment 4:

Surface defect inspection apparatus of the present invention is characterised in that: have light projection part, the linear array gamma camera of 3 eyeglass formula polarized lights, and signal processing, light projection part incides polarized light and is examined on the surface, the linear array gamma camera of 3 eyeglass formula polarized lights has the beam splitter that the beam separation of incident is become 3 light beams, be separately positioned on the light path of 3 separated light beams and with position angle 0, π/4, the analyzer of-π/4 configurations, and receive the linear array transducer that each analyzer sees through light, the linear array gamma camera of this 3 eyeglass formula polarized light makes from the reflected light incident that is examined the surface exports 3 kinds of different polarized light image signals, signal processing is COS Δ and the intensity of reflected light I of amplitude reflectivity than tan ψ and expression phase difference to handling from the polarized light image signal of the linear array gamma camera output of 3 eyeglass formula polarized lights, calculating the elliptic polarization optical parameter that is examined surface reflection ₀, and according to the amplitude reflectivity that calculates than tan ψ and phase place COS Δ and intensity of reflected light I ₀, judge that being examined the surface has free of surface defects.

In the present invention, be that linear array gamma camera of 3 eyeglass formula polarized lights and signal processing constitute surface defect inspection apparatus by light projection part, light receiving part.Light projection part is configured to light source light beam can be incided with certain incident angle and is examined the surface for example on the whole Width of surface of steel plate of high-speed mobile, at light source be examined between the incoming position on surface and do not have polarizer.The linear array gamma camera of 3 eyeglass formula polarized lights makes from the reflected light incident that is examined the surface exports 3 kinds of different polarized light image signals, 3 linear array transducers that it has beam splitter and 3 analyzers and is made of for example CCD etc.Beam splitter has been provided with on its plane of incidence evaporation 2 reflectings surface of multilayer dielectric film with half transmitting, make the 1st reflecting surface from the reflected light incident that is examined the surface, the ratio of its transmissivity and reflectivity is 3: 1, make the 2nd reflecting surface of the light incident that sees through the 1st reflecting surface, the ratio of its transmissivity and reflectivity is 1: 1.Utilize this beam splitter that incident light is separated into 3 light beams, the light beam after the separation incides analyzer respectively.3 analyzers are respectively with different position angle configurations, promptly the angle that constitutes of the axis of homology and the plane of incidence that is examined the surface be respectively 0, π/4 ,-π/4, the different polarized light of plane of polarization incides in the linear array transducer respectively.3 linear array transducers make the polarized light incident by each analyzer, and the picture signal that the expression intensity of polarization light distributes is exported to signal processing.Like this, incide in the linear array gamma camera of one 3 eyeglass formula polarized light owing to make from the reflected light that is examined the surface, after in the linear array gamma camera of this 3 eyeglass formula polarized light, being separated into 3 different polarized lights of plane of polarization, incide respectively in 3 linear array transducers, the reflected light of same position incides in 3 linear array transducers on the surface from being examined so can make in same timing.

Signal processing is COS Δ and the intensity of reflected light I of amplitude reflectivity than tan ψ and expression phase difference to handling from the polarized light image signal of the linear array gamma camera output of 3 eyeglass formula polarized lights, calculating the elliptic polarization optical parameter that is examined surface reflection ₀, and with the amplitude reflectivity that calculates than tan ψ, phase place COS Δ and intensity of reflected light I ₀Compare with predetermined surface imperfection characteristic, judge unusual degree.

Figure 28 is the optical system configurations figure of one embodiment of the invention.As shown in the figure, optical system 301 has light projection part 302 and the linear array gamma camera 303 of 3 eyeglass formula polarized lights.Light projection part 302 incides on the surface that is examined style such as steel plate 304 polarized light with certain incident angle, it has light source 305 and is arranged on the polaroid 306 of light source 305 fronts.Light source 305 is made of the bar-shaped light-emitting device along steel plate 304 Widths elongations, with certain interval with rayed on steel plate 304 whole Widths.Polaroid 306 is made of for example 1/4 wavelength plate, shown in the configuration instruction figure of Figure 29, and the angle α that the plane of incidence of axis of homology P and steel plate 304 constitutes ₁Be π/4.The linear array gamma camera 303 of 3 eyeglass formula polarized lights has beam splitter 307,3 analyzer 308a, 308b, 308c and 3 linear array transducer 309a, 309b, 309c shown in the structural drawing of Figure 30.Beam splitter 307 is made of 3 prisms, be provided with evaporation on its plane of incidence 2 of multilayer dielectric film have blue radioparent reflecting surface, make the 1st reflecting surface 307a from the reflected light incident of steel plate 304, the ratio of its transmissivity and reflectivity is 3: 1, make the 2nd reflecting surface 307b of the light incident that sees through the 1st reflecting surface 307a, the ratio of its transmissivity and reflectivity is 1: 1, will be separated into 3 identical light beams of light quantity from the reflected light of steel plate 304.In addition, the optical path length from the plane of incidence of beam splitter 307 to 3 light beam exit facets that separated is identical.Analyzer 308a is arranged on the transmitted light light path of the 2nd reflecting surface 310b, and as shown in figure 29, its configuration is to make the position angle angle α that constitutes of the plane of incidence of the axis of homology and steel plate 304 just ₂Be 0 degree, analyzer 308b is arranged on the reflected light light path of the 2nd reflecting surface 307b, its azimuth angle alpha ₂Be configured to π/4, analyzer 308c is arranged on the catoptrical light path of the 1st reflecting surface 307a, its azimuth angle alpha ₂Be configured to-π/4.Linear array transducer 309a, 309b, 309c are made of for example ccd sensor, are configured in the rear side of analyzer 308a, 308b, 308c respectively.In addition, between beam splitter and analyzer 308a, 308b, 308c, be provided with slit 310a, 310b, 310c, be used for repeatedly reflected light or unwanted scattered light in the break beam separation vessel 307, be provided with lens group 311 in the front side of beam splitter 307.Linear array transducer 309a, 309b, 309c regulate gain, so that the identical signal of output after the identical light incident of light intensity.

Like this, because analyzer 308a～308c and linear array transducer 309a～309c are arranged on the light path of 3 light beams that incident light is separated into integratedly, so when linear array transducer 309a～309c etc. being arranged near the reflected light that detects the pipeline of steel plate 304 from steel plate 304, do not need to carry out the position adjustment of linear array transducer 309a～309c etc., can detect reflected light in same timing simultaneously from steel plate 304 same positions.In addition, because 3 groups of linear array transducer 309a～309c concentrate and are assembled in the linear array gamma camera 303 of 3 eyeglass formula polarized lights, reached miniaturization, so the linear array gamma camera 303 of 3 eyeglass formula polarized lights can be configured on the steel plate 304 catoptrical light paths simply, simultaneously allocation position can be selected arbitrarily, the configuration degree of freedom of optical system 301 can be improved.

Shown in the block diagram among Figure 31, the linear array transducer 309a～309c of the linear array gamma camera 303 of 3 eyeglass formula polarized lights is connected on the signal processing 312.Signal processing 312 has frame memory 313a, 313b, 313c, arithmetic unit 314, tan ψ memory storage 315a, COS Δ memory storage 315b, I ₀Memory storage 315c, parameter memory storage 316, parameter comparison means 317 and output unit 318.Among frame memory 313a, 313b, 313c, launch respectively by each pixel from the picture signal of linear array transducer 309a, 309b, 309c output.Arithmetic unit 314 is read the picture signal of the same position of steel plate 304 successively from frame memory 313a, 313b, 313c, the elliptic polarization optical parameter of calculating each pixel is that amplitude reflectivity is than tan ψ and the COS Δ of expression phase difference and the catoptrical surface reflection intensity I of steel plate 304 ₀, and deposit in respectively tan ψ memory storage 315a,, COS Δ memory storage 315b and I ₀Among the memory storage 315c.In parameter memory storage 316, storing the character of surface of the steel plate 304 of trying to achieve in advance, the surface reflection intensity I of so-called decorative pattern shape defective such as promptly the small maldistribution of inhomogeneous, the smooth finish of physical parameter, the local thin oxide film that exists or coating film thickness be inhomogeneous or the pairing tan ψ of concavo-convex defective, COS Δ and specular light ₀Deng various characteristics.Parameter comparison means 317 is pressed each pixel with tan ψ memory storage 315a, COS Δ memory storage 315b, I ₀Tan ψ, COS Δ and the surface reflection intensity I of storing respectively among the memory storage 315c ₀The various characteristics value of storing in advance in the same parameter memory storage 316 compares, and judges on steel plate 304 surfaces to have or not decorative pattern shape defective or concavo-convex defective and kind and size.

Before the moving part of the surface examining device that explanation as above constitutes, at first explanation is calculated the surface reflection intensity I of amplitude reflectivity than the specular light of tan ψ, COS Δ and steel plate 304 according to the light intensity that is detected by 3 linear array transducer 309a, 309b, 309c ₀Principle.

As shown in figure 29, when inciding analyzer 308, as establish the angle that the plane of incidence of the axis of homology A of the axis of homology P of polaroid 306 and analyzer 308 and steel plate 304 constitutes and be respectively α from the reflected light of steel plate 304 ₁, α ₂, then with any incident angle i incide the P polarized light component of steel plate 304 back reflections and S polarized light component by analyzer 308 the light intensity I (α after synthetic ₁, α ₂) represent and the amplitude reflectivity of establishing P component and S component is respectively γ with following formula _P, γ _SI(α ₁·α ₂)＝|E _ocosα ₁·r _pcosα ₂+E _osinα ₁·r _ssinα ₂| ²

＝I _oR _p〔cos ²α ₁·cos ²α ₂+ρ ²sin ²α ₁·sin ²α ₂

+ (1/2) sin2 α ₁Sin2 α ₂The cos Δ) I in the formula _o=| E _o| ², r _p= R _pExp (i  _p), r _s= R _sExp (i  _s) ρ=r _s/ r _p=tan ψ, Δ= _s- _p

Here, work as α ₁α is passed through in=π/4 o'clock ₂The light intensity I of=0 analyzer 308a ₁Become I ₁=I ₀R _P/ 2, pass through α ₂The light intensity I of the analyzer 308b of=π/4 ₂Become I ₂=I ₀R _P(1+ ρ ²+ 2 ρ COS Δs)/4, pass through α ₂The light intensity I of the analyzer 308c of=-π/4 ₃Become I ₃=I ₀R _P(1+ ρ ²-2 ρ COS Δs)/4.According to these light intensity I ₁, I ₂, I ₃, variously can try to achieve tan ψ, COS Δ and surface reflection intensity I by following ₀ $\tan \mathrm{\Ψ}=\sqrt{\frac{I_1}{I_2+I_3-I_1}}$ I ₀＝I ₂+I ₃-I ₁ $\cos \mathrm{\Δ}=\frac{I_1-I_2}{2I_1}\tan \mathrm{\Ψ}$

In addition, as shown in figure 30, from the reflected light of steel plate 304 by behind the beam splitter 307, respectively by each analyzer 308a～308c, with linear array transducer 309a, 309b, when 309c detects, above-mentioned elliptically polarized light parametric t an ψ, COS Δ and the surface reflection intensity I of each pixel ₀Value calculate like this, i.e. the output of the linear array transducer 309a～309c of K pixel is made as I _1K, I _2K, I _3K, and the ratio of establishing the transmissivity of S polarized light component that the light that incides among linear array transducer 309b, the 309c separates by beam splitter 307 and P polarized light component is τ ₂, τ ₃, A=(τ ₂+ τ ₃), B=(1+ τ ₃ ²), then elliptically polarized light parametric t an ψ k, the COS Δ of K pixel _KAnd the surface reflection intensity I of the whole light quantities of expression K pixel _OKRespectively by following various trying to achieve. $\tan \mathrm{\&Psi;k}=\sqrt{\frac{\mathrm{\&tau;}2\&CenterDot;\mathrm{\&tau;}3\&CenterDot;A\&CenterDot;I1k}{\mathrm{\&tau;}3\&CenterDot;B\&CenterDot;I2k+\mathrm{\&tau;}2\&CenterDot;C\&CenterDot;I3k-A\&CenterDot;I1k}}$ $\cos \mathrm{\&Delta;}=\frac{{\mathrm{\&tau;}3}^2\&CenterDot;B\&CenterDot;I2k-{\mathrm{\&tau;}2}^2\&CenterDot;C\&CenterDot;I3k+({\mathrm{\&tau;}2}^2-{\mathrm{\&tau;}3}^2)\&CenterDot;I1\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="A02124788.900821.png,A02124788.900871.png"\; state="\{\{state\}\}">k</figure-callout>}}{2\&CenterDot;\mathrm{\&tau;}2\&CenterDot;\mathrm{\&tau;}3\&CenterDot;A\&CenterDot;I1k}$ $\&times;\sqrt{\frac{\mathrm{\&tau;}2\&CenterDot;\mathrm{\&tau;}3\&CenterDot;A\&CenterDot;I1k}{\mathrm{\&tau;}3\&CenterDot;B\&CenterDot;I2k+\mathrm{\&tau;}2\&CenterDot;C\&CenterDot;I3k-A\&CenterDot;I1k}}$ $I0k=\frac{\mathrm{\&tau;}3\&CenterDot;B\&CenterDot;I2k+\mathrm{\&tau;}2\&CenterDot;C\&CenterDot;I3k-A\&CenterDot;I1k}{\mathrm{\&tau;}2\&CenterDot;\mathrm{\&tau;}3\&CenterDot;A}$

Secondly the action of the surface defect inspection apparatus of above-mentioned principle is used in explanation.Throwing the polarized light that reflects on the surface of the steel plate 304 that moves with certain speed after part 302 outgoing from light is received by the linear array gamma camera 303 of 3 eyeglass formula polarized lights.After the reflected light that incides the steel plate 304 of the linear array gamma camera 303 of 3 eyeglass formula polarized lights is separated by beam splitter 307,, incide among linear array transducer 309a, 309b, the 309c by analyzer 308a, 308b, 308c.During with this linear array transducer 309a, 309b, 309c detection of reflected light intensity, linear array transducer 309a is provided with α because of the front ₂=0 analyzer 308a and detect light intensity I ₁, linear array transducer 309b is provided with α because of the front ₂The analyzer 308b of=π/4 and detect light intensity I ₂, linear array transducer 309c is provided with α because of the front ₂The analyzer 308c of=-π/4 and detect light intensity I ₃The light intensity I that expression detects with linear array transducer 309a, 309b, 309c ₁, I ₂, I ₃Picture signal, in frame memory 313a, 313b, 313c, launch respectively by each pixel.

Arithmetic unit 314 reads out in the light intensity I that launches among frame memory 313a～313c by each pixel ₁, I ₂, I ₃, and calculate amplitude reflectivity successively than tan ψ by each pixel _KWith the COS Δ _K, and surface reflection intensity I _OK, deposit tan ψ storer 315a, COS Δ storer 315b and I respectively in ₀Among the storer 315c.Parameter comparison means 317 is pressed each pixel with tan ψ memory storage 315a, COS Δ memory storage 315b and I ₀The tan ψ that stores among the memory storage 315c _K, the COS Δ _KAnd surface reflection intensity I _0KThe characteristic of storing in advance in the same parameter memory storage 316 compares, and judges that steel plate 304 surfaces have or not decorative pattern shape defective or concavo-convex defective and kind and size.The result of determination of this parameter comparison means 317 is exported to not shown memory storage or display device successively from output unit 318, and whether can know has on steel plate 304 surfaces unusually.

As mentioned above, owing to having adopted the reflected light that is examined the surface of 3 group of received incidents and exported the linear array camera of the incorporated 3 eyeglass formula polarized lights of the linear array transducer of 3 kinds of different images signals, the present invention obtains 3 kinds of different picture signals, therefore can simply the linear array gamma camera of 3 eyeglass formula polarized lights be configured on the catoptrical light path that is examined the surface, can choose wantonly simultaneously and select allocation position, can improve the configuration degree of freedom of the surface defect inspection apparatus optical system of utilizing polarized light.

In addition, 3 groups of linear array transducers are integrated, make and to detect from the reflected light that is examined surperficial same position in same timing, therefore can detect the surface imperfection that is examined the surface simultaneously accurately handling the designs simplification of the signal processing of picture signal.

Embodiment 5:

Surface examining device of the present invention is characterised in that: light projection part is arranged, light receiving part and signal processing, the polarized light light beam that light projection part distributes broad ways incides and is examined on the surface, light receiving part has and is arranged on the reflected light light path that is examined the surface and 3 analyzers that have different orientations respectively, and receive the linear array transducer that each analyzer sees through light, it makes from the reflected light incident that is examined the surface and is transformed into picture signal, signal processing makes the output image signal standardization from each linear array transducer, planarization, calculating the elliptic polarization optical parameter according to the picture signal after the planarization is the COS Δ of amplitude reflectivity than tan ψ and expression phase difference, and intensity of reflected light I ₀Relative value, and according to the amplitude reflectivity that calculates than tan ψ and phase differential COS Δ and intensity of reflected light I ₀Relative value, judge that be examined the surface has no abnormal.

In the present invention, light projection unit branch is configured to polarized light is incided on the whole Width that is examined the surface with certain incident angle with respect to being examined the surface, and the light receiving part that reception is examined surface reflection is configured in assigned position.Light receiver is arranged with the beam splitter that incident light is separated into 3 light beams, make 3 separated light beams respectively incident and output image signal 3 groups of linear array gamma cameras with ccd sensor for example and be arranged on beam splitter and each linear array gamma camera between make the analyzer that becomes the polarized light of different polarization face from the reflected light that is examined the surface.3 analyzers dispose like this, promptly each have different position angles, just the angle that constitutes of the axis of homology and the plane of incidence that is examined the surface for example be respectively 0, π/4 ,-π/4.

Signal processing makes output image signal standardization, the planarization from each linear array transducer, so that make normal part become the middle briliancy of whole briliancy grades, and is transformed into the picture signal of expression with respect to the relative variation of normal part.According to the picture signal of this expression with respect to the relative variation of normal part, calculating the elliptic polarization optical parameter is COS Δ and the intensity of reflected light I of amplitude reflectivity than tan ψ and expression phase difference ₀, calculate amplitude reflectivity than tan ψ and phase differential COS Δ and intensity of reflected light I ₀Relative value, form tan ψ, COS Δ and I ₀The relative value image.According to this relative value image detection tan ψ, COS Δ and I ₀Relative variation, thereby the surface that is examined of detecting steel plate etc. has or not surface abnormalities.

Figure 32, Figure 33 represent the structure of one embodiment of the invention, and Figure 32 is the optical system configuration composition, and Figure 33 is the signal processing block diagram.Shown in figure 32, optical system 401 has light projection part 402 and light receiving part 403.Light projection part 402 has light source 404 and is located at the polarizer 405 of light source 404 fronts.Light source 404 is made of the plane light source that forms its length along the Width that is examined style such as steel plate 406, parallel beam is radiated in the certain-length scope on steel plate 406 surfaces.Polarizer 405 is made of for example 1/4 wavelength plate, as shown in figure 34, is configured to the angle α of the plane of incidence formation of axis of homology P and steel plate 406 ₂Be π/4.Analyzer 408a, 408b, 408c that light receiving part 403 has 3 linear array gamma camera 407a, 407b, 407c and is arranged on the sensitive surface front of each linear array gamma camera 407a, 407b, 407c.Linear array gamma camera 407a, 407b, 407c have for example CCD element group, and along the moving direction of steel plate 406 stagger configuration, detect from the reflected light of steel plate 406 and be transformed into the polarized light image signal.Analyzer 408a, 408b, 408c are made of for example 1/4 wavelength plate, as shown in figure 34, and the angle α that the plane of incidence of the axis of homology of analyzer 408 and steel plate 406 constitutes ₂Be configured to the α of analyzer 408a ₂=0, the α of analyzer 408b ₂=π/4, the α of analyzer 408c ₂=-π/4.

Signal processing 409 has signal transformation part 410a, 410b, 410c, frame memory 411a, 411b, 411c, arithmetic unit 412, tan ψ memory storage 413a, COS Δ memory storage 413b, I ₀Memory storage 413c, parameter comparison means 414 and output unit 415.Signal transformation part 410a, 410b, 410c are reference level with the signal of normal part from the polarized light image signal of linear array gamma camera 407a, 407b, 407c output respectively, make from polarized light image signal normalization, the leveling of linear array gamma camera 407a, 407b, 407c output, so that the signal of normal part becomes middle the briliancy of whole briliancy grades, and become expression with respect to the normal part picture signal of variation relatively the above-mentioned image signal transformation.Among frame memory 411a, 411b, 411c, launch respectively from the picture signal of signal transformation part 410a, 410b, 410c output by each pixel.Arithmetic unit 412 is read the picture signal of the same position of steel plate 406 successively from frame memory 411a, 411b, 411c, the elliptic polarization optical parameter of calculating each pixel place is that amplitude reflectivity is than tan ψ and the COS Δ of expression phase difference and the catoptrical surface reflection intensity I of steel plate 406 ₀, deposit tan ψ memory storage 413a, COS Δ memory storage 413b and I respectively in ₀In the memory storage.Parameter comparison means 414 is according to tan ψ memory storage 413a, COS Δ memory storage 413b and I ₀The tan ψ that stores among the memory storage 413c, COS Δ and surface reflection intensity I ₀The level situation of change, judge on steel plate 406 surfaces to have or not decorative pattern shape defective or concavo-convex defective and kind thereof.

Before the action of the surface examining device that explanation as above constitutes, the light intensity that detects according to 3 linear array gamma camera 407a, 407b, 407c at first is described, calculate the surface reflection intensity I of amplitude reflectivity than tan ψ, COS Δ and steel plate 404 ₀Principle.

As shown in figure 34, when the reflected light from steel plate 406 incides on the analyzer 408, as establish the angle that the plane of incidence of the axis of homology A of the axis of homology P of polarizer 405 and analyzer 408 and steel plate 406 constitutes and be respectively α ₁, α ₂, then with incident angle i arbitrarily incide the P polarized light component of back reflection on the steel plate 406 and S polarized light component by analyzer 408 the light intensity I (α after synthetic ₁, α ₂) be expressed from the next, and the amplitude reflectivity of establishing ρ component and S component is respectively γ _ρ, γ _SI(α ₁·α ₂)＝|E _ocosα ₁·r _pcosα ₂+E _osinα ₁·r _ssinα ₂| ^·2

＝I _oR _p〔cos ²α ₁·cos ²α ₂+ρ ²sin ²α ₁·sin ²α ₂

+ (1/2) sin2 α ₁Sin2 α ₂The cos Δ) I in the formula _o=| E _o| ², r _p= R _pExp (i  _p), r _s= R _sExp (i  _s) ρ=r _s/ r _p=tan ψ, Δ= _s- _p

Here, work as α ₁α is passed through in=π/4 o'clock ₂The light intensity I of=0 analyzer 408a ₁Become I ₁=I ₀R _P/ 2, pass through α ₂The light intensity I of the inspection oscillation pickup 408b of=π/4 ₂Become I ₂=I ₀R _P(1+ ρ ²+ 2 ρ COS Δs)/4, pass through α ₂The light intensity I of the analyzer 408c of=-π/4 ₃Become I ₃=I ₀R _P(1+ ρ ²-2 ρ COS Δs)/4.According to these light intensity I ₁, I ₂, I ₃, by following various tan ψ, COS Δ and the surface reflection intensity I of obtaining respectively ₀ $\tan \mathrm{\&Psi;}=\sqrt{\frac{I_1}{I_2+I_3-I_1}}$ $\cos \mathrm{\&Delta;}=\frac{I_2-I_3}{2I_1}\tan \mathrm{\&Psi;}$

I ₀＝I ₂+I ₃-I ₁

Secondly the action of the surface examining device of above-mentioned principle is used in explanation.The polarized light that reflects on steel plate 406 surfaces of moving with certain speed after 402 outgoing of light projection part incides linear array gamma camera 407a, 407b, the 407c by analyzer 408a, 408b, 408c.During with this linear array gamma camera 407a, 407b, 407c detection of reflected light intensity, linear array gamma camera 407a is because the front is provided with α ₂=0 analyzer 408a and detect light intensity I ₁, linear array gamma camera 407b is because the front is provided with α ₂The analyzer 408b of=π/4 and detect light intensity I ₂, linear array gamma camera 407c is because the front is provided with α ₂The analyzer 408c of=-π/4 and detect light intensity I ₃In addition, for the level of the polarized light image signal that makes linear array gamma camera 407a, 407b, 407c output is identical, then make linear battle array to the gain of gamma camera 407a be linear array gamma camera 407b, 407c gain 1/2, the light intensity I in the following formula ₁Become 2 times of the light intensity that detects with linear array gamma camera 407a.

Represent light intensity I with what linear array gamma camera 407a, 407b, 407c detected ₁, I ₂, I ₃The polarized light image signal send signal transformation part 410a, 410b, 410c respectively to.Signal transformation part 410a, 410b, 410c make the expression light intensity I that is sent to the signal reference level of the image of normal part ₂, I ₂, I ₃Polarized light image signal normalization, planarization so that make the picture signal of normal part become the middle briliancy of whole briliancy grades, and be transformed into the image section of expression with respect to the relative variation of normal part.That is, shown in Figure 35 (a), make the expression light intensity I that detects by linear array gamma camera 407a, 407b, 407c ₁, I ₂, I ₃The method of polarized light image signal normalization, planarization as follows, promptly shown in Figure 35 (b), with the signal reference level of the image of normal part, make the i.e. 128 briliancy grades of middle briliancy that the picture signal of normal part becomes 255 briliancy grades, ask average luminance with the average amplitude that the broad ways of stipulating moves, make light intensity I ₁, I ₂, I ₃Standardization, planarization.Expression is deposited in respectively among frame memory 411a, 411b, the 411c corresponding to the picture signal that the normal part after this planarization changes relatively.Light intensity I before and after the standard like this ₁, I ₂, I ₃Image be shown in Figure 36 (a) and (b).Shown in Figure 36 (a), represent light intensity I with what linear array gamma camera 407a, 407b, 407 detected ₁, I ₂, I ₃Polarized light image corresponding to light intensity I ₁, I ₂, I ₃Briliancy, form deep or light different image, but shown in Figure 36 (b), the image that changes relatively after the display standardization is a benchmark with the normal part that shows same concentrations, its unusual part demonstrates bright or dark concentration change.Like this, by with normal part being the light intensity I that benchmark will use linear array gamma camera 407a, 407b, 407c to detect ₁, I ₂, I ₃Standardization can make every linear array gamma camera 407a, 407b, 407c bias free ground obtain and light intensity I ₁, I ₂, I ₃Corresponding image.

Arithmetic unit 412 reads out in the expression light intensity I that launches among frame memory 411a～411c by each pixel ₁, I ₂, I ₃The image that changes calculates amplitude reflectivity than tan ψ, COS Δ and surface reflection intensity I by each pixel relatively ₀, and as tan ψ, COS Δ and I ₀View data deposit tan ψ memory storage 413a, COS Δ memory storage 413b and I in ₀Among the memory storage 413c.By this calculation element 413b and I ₀Among the memory storage 413c.Calculate tan ψ, COS Δ and the I that obtains by this ₀Image shown in Figure 37 (a) and (b), (c), becoming with normal part is the relative value image of benchmark, for example, is the COS Δ that benchmark generates with the normal part of Δ=90 degree, the unusual part is bright or dark, with this tan ψ, COS Δ and I ₀The relative value image be presented on the not shown display device.

Parameter comparison means 418 is according to tan ψ memory storage 413a, COS Δ memory storage 413b and I ₀The tan ψ that stores among the memory storage 413c, COS Δ and surface reflection intensity I ₀The level situation of change, judge that steel plate 406 surfaces have or not decorative pattern shape defective or concavo-convex defective and kind thereof, export to pen recorder or display device from output unit 415.That is, as the tan ψ among Figure 36 (c), COS Δ and I ₀Image shown in, the unusual part of steel plate 406 is with the difference that is kind such as defective unusually, it is the polarity difference of benchmark with normal part, for example, the defective 421 that is caused by the snotter of steel plate 406 inside is positive polarity on tan ψ picture and COS Δ image, at I ₀Image is negative polarity.In addition, having under the situation of greasy dirt.At tan ψ image, COS Δ image and I ₀That image is respectively is positive and negative, positive polarity or all be positive polarity, can be according to tan ψ, COS Δ and I ₀Level judge the kind of unusual part.

Like this, by the picture signal that makes normal part be 255 briliancy grades middle briliancy promptly 128 briliancy grades carry out standardization, generate relative image, can make the variation of unusual part of elliptically polarized light parametric t an ψ or COS Δ obvious.The briliancy grade that is general Flame Image Process is 255, but the light intensity I that for example detects with linear array gamma camera 407c ₃The contrast factor of normal part hour is as the I among Figure 36 (a) ₃Shown in the image, it is very dark that image totally becomes.As calculating the elliptic polarization optical parameter with this view data is the absolute value of amplitude reflectivity than tan ψ or COS Δ, sometimes the variation of the unusual part of elliptically polarized light parametric t an ψ or COS Δ is not obvious, be not suitable for detecting defective, but can eliminate this situation that is not suitable for.

The various embodiments described above have illustrated the linear array gamma camera 407a in the light receiver 403,407b, 407c have been made the position situation of configuration that staggers with respect to the moving direction of steel plate 406, but shown in vertical view and the side view among Figure 39 among Figure 38, also linear array gamma camera 407a, 407b, 407c can be arranged on the same straight line with the moving direction quadrature of steel plate 406, and make it highly identical, detect reflected light simultaneously from the same position of steel plate 406.

In addition, the various embodiments described above have illustrated that the polarized light that sends from light projection unit branch is directly incident on the surface of steel plate 406, directly receive its catoptrical situation with linear array gamma camera 407a, 407b, 407c, but as shown in figure 40, also can make the light that sends from light source 404 pass through polarizer 405, incident angle with regulation incides on the surface of steel plate 406, and, use linear array gamma camera 407a, 407b, 407c reception again with respect to the Surface Vertical setting of steel plate 406 with the reflected light of catoptron 416 reflections from steel plate 406.By such formation light projection part 402 and light receiving part 403, can reduce the space that is provided with of optical system 401, and can improve the degree of freedom of online setting.At this moment, owing to lying in, problem do not make tan ψ, COS Δ and I ₀Produce absolute change but variation relatively, therefore the influence that is produced by 416 pairs of polarized lights of catoptrons such as aluminium does not have problems, and can improve the structure of optical system 401 or the degree of freedom of setting.

As mentioned above, the present invention is incided polarized light to be examined on the surface, receive its reflected light by analyzer with different orientations, measure different polarized light light distribution, make light distribution standardization, the planarization measured,, and be transformed into the picture signal of expression with respect to the relative variation of normal part so that normal part reaches the middle briliancy of whole briliancy grades, therefore can make each gamma camera of light receiving part problems such as deviation not occur, generate the image corresponding with light intensity.

In addition, owing to, calculate elliptically polarized light parametric t an ψ or COS Δ and intensity of reflected light I according to the relative image that is generated ₀, therefore can make elliptically polarized light parametric t an ψ or COS Δ and intensity of reflected light I ₀The variation of unusual part obvious, surface that can the lamellar product of online accurately detection has or not unusual part and kind thereof.

Moreover, owing to do not measure the absolute value of elliptically polarized light parameter but measure relative value, therefore can relax requirement significantly, can reduce the overall cost of device, can also easily be provided with or adjust simultaneously the severity of optical system or signal processing.Embodiment 6:

Surface examining device of the present invention is characterised in that: light projection part is arranged, light receiving part and signal processing, light projection part incides polarized light and is examined on the surface, light receiving part has the optical system of a plurality of reception light, be used for receiving at least polarized light with different special angles from 3 directions, detection is by the reflected light that is examined surface reflection and be transformed into picture signal, signal processing makes the light distribution standardization that receives the optical system output of light from each with reference value, and the figure that the changed polarity and the variable quantity of the some light distribution after the standardization are scheduled to together compares the kind of judgement defective.

In addition, above-mentioned signal processing makes the light distribution standardization that receives the optical system output of light from each with reference value, the changed polarity and the variable quantity of the some light distribution after the standardization are compared with predetermined figure, judge the kind of defective, and the light distribution of preferably exporting according to the optical system that receives light from each, calculate the variation of visual suitable light quantity, the light quantity of calculating is changed with predetermined pattern relatively, judge the grade of defective.

Polarized light is to the physical characteristics of reflecting surface, particularly to the film sensitivity.In addition, with the difference of reflecting surface physical characteristics, the direction of polarized light of intensity maximum also changes.Defective part has and the normal different character of surface of part on the metal surface, have owing to its surface physical characteristic with the different defectives that cause of material, perhaps for example because uneven and different with the morphology of normal part, thereby the defective that causes.The former can utilize polarized light to detect, and the latter can detect by the variation of reflection light quantity owing to cause the reflectivity difference.

Therefore, in the present invention, light projection unit branch is configured to, makes polarized light and incide on the whole Width that is examined the surface with certain incident angle, and the light receiving part that reception is examined surface reflection is configured in the position of regulation with respect to being examined the surface.Light receiving part the light of incident is not separated into 3 light beams for example beam splitter, make 3 separated light beams respectively after the incident 3 groups of linear array gamma cameras that for example have ccd sensor of output image signal and be arranged on beam splitter and each linear array gamma camera between be used for making from the analyzer of the reflected light that is examined the surface along different plane of polarization polarizations.3 analyzers are configured to make its position angle to have nothing in common with each other, promptly the angle that constitutes of the axis of homology and the plane of incidence that is examined the surface for example be respectively 0, π/4 ,-π/4.

Signal processing is carried out tint correction to the output image signal from each linear array gamma camera, go forward side by side column criterionization, planarization, make normal part reach the intermediate concentration of whole gray shade scales, and be transformed into the light intensity signal of expression with respect to the relative variation of normal part.Changed polarity that 3 kinds of light intensity signals that expression is changed relatively with respect to normal part distribute and variable quantity compare with the figure of being scheduled to respectively, detect the variation of polarized light.With respect to the changed polarity of normal part and the size of variable quantity, formulate the kind of its surface physical characteristic defective different according to these 3 kinds of light intensity signals with using material.

In addition, signal processing is when carrying out above-mentioned processing, light distribution according to the optical system output that receives light from each, surface reflection intensity when the variation of calculating and visual suitable light quantity is nonpolarized light, and the figure that the light quantity variation of calculating is scheduled to together compares, according to the polarity of light quantity variation and the size of variable quantity, judge for example its morphology as concavo-convex defective and the normal different defect rank of part.

Figure 41 is the optical system configurations figure of one embodiment of the invention.As shown in the figure, optical system 501 has light projection part 502 and the linear array gamma camera 503 of 3 eyeglass formula polarized lights.Light projection part 502 incides polarized light on the surface of steel plate 504 with certain incident angle, it has light source 505 and is located at the polaroid 506 of light source 505 fronts.Light source 505 is made of the bar-shaped light-emitting device that extends along the Width of steel plate 504, with certain interval with rayed on steel plate 504 whole Widths.Polaroid 506 is made of for example 1/4 wavelength plate, shown in the configuration instruction figure among Figure 42, and the angle α that the plane of incidence of its axis of homology P and steel plate 504 constitutes ₂Be configured to π/4.The linear array gamma camera 503 of 3 eyeglass formula polarized lights has beam splitter 507,3 analyzer 508a, 508b, 508c and 3 linear array transducer 509a, 509b, 509c shown in the structural drawing among Figure 43.Beam splitter 507 is made of 3 prisms, be provided with two on the plane of incidence evaporation reflecting surface with half transmitting of multilayer dielectric film, make the 1st reflecting surface 507a from the reflected light incident of steel plate 504, the ratio of its transmissivity and reflectivity is about 2: 1, make the 2nd reflecting surface 507b of the light incident that sees through the 1st reflecting surface 507a, the ratio of its transmissivity and reflectivity is 1: 1, will be separated into 3 identical light beams of light quantity from the reflected light of steel plate 504.In addition, the optical path length the exit facet from the plane of incidence of beam splitter 507 to 3 light beams that separated is identical.Analyzer 508a is arranged on the transmitted light light path of the 2nd reflecting surface 507b, and as shown in figure 42, its position angle is the angle α that the plane of incidence of the axis of homology and steel plate 504 constitutes ₂Be configured to 0 degree, analyzer 508b is arranged on the reflected light light path of the 2nd reflecting surface 507b, its azimuth angle alpha ₂Be configured to π/4, analyzer 508c is arranged on the reflected light light path of the 1st reflecting surface 507a, its azimuth angle alpha ₂Be configured to-π/4.Linear array transducer 509a, 509b, 509c are made of for example ccd sensor, are configured in the rear side of analyzer 508a, 508b, 508c respectively.Between beam splitter 507 and analyzer 508a, 508b, 508c, be provided with slit 510a, 510b, 510c, be used for repeatedly reflected light or unwanted scattered light in the break beam separation vessel 507, be provided with lens group 511 in the front side of beam splitter 507.Linear array transducer 509a, 509b, 509c gain adjustable can be exported identical signal when making the identical light incident of light intensity.

Because on the light path of 3 light beams that analyzer 508a～508c and linear array transducer 509a～509c are arranged on light with incident so integratedly after separating, so when linear array transducer 509a～509c etc. being arranged near the reflected light that detects the pipeline of steel plate 504 from steel plate 504, do not need to adjust the position of linear array transducer 509a～509 grades, simultaneously can be at the reflected light of same timing detection from the same position of steel plate 504.In addition, because concentrating, 3 groups of linear array transducer 509a～509c are assembled in the linear array gamma camera 503 of 3 eyeglass formula polarized lights and miniaturization, so the linear array gamma camera 503 of 3 eyeglass formula polarized lights can be configured on the reflected light light path of steel plate 504 simply, simultaneously allocation position can be at random selected, thereby the configuration degree of freedom of optical system 501 can be improved.

Linear array transducer 509a～509 of the linear array gamma camera 503 of 3 eyeglass formula polarized lights shown in the block diagram among Figure 44, are connected on the signal processing 512.Signal processing 512 has Signal Pretreatment part 513a, 513b, 513c, I ₁Storer 514a, I ₂Storer 514b, I ₃Storer 514c, defect parameters arithmetic section 515, graphics memory part 516, light quantity storage area 517, reference pattern storage area 518, defect kind are judged part 519, level patterns storage area 520, defect rank judgement part 521 and output 522.Signal Pretreatment part 513a～513c is to the polarized light intensity signal I from linear array transducer 509a～509c output ₁, I ₂, I ₃Inconsistent grade such as the sensitivity of broad ways etc. is carried out after tint correction etc., with the signal of normal part as reference level, carrying out standardization, is 128 gray shade scales so that the signal of normal part arrives the intermediate concentration of 255 gray shade scales, and with the light intensity signal I after the standardization ₁, I ₂, I ₃Deposit I respectively in ₁Storer 514a, I ₂Storer 514b, I ₃Among the storer 514c.515 couples of I of defect parameters arithmetic section ₁Storer 514a～I ₃The light intensity signal I that stores among the storer 514c ₁, I ₂, I ₃Distribution in the peak value of shown defect part, value with normal part is that 128 gray shade scales are benchmark, calculate the polar pattern of demonstration or plus or minus, and to calculate demonstration be the magnitude pattern of the variable quantity of benchmark with 128 gray shade scales, calculates the visual light quantity that is equivalent to of no polarized light simultaneously according to the light intensity of defect part.Graphics memory part 516 stores polar pattern and the magnitude pattern of calculating, and light quantity storage area 517 is the maximum visual suitable light quantity Imax that calculates of storage then.Storing the kind of various polar pattern and magnitude pattern and the defective corresponding in the reference pattern storage area 518 in advance with it.Defect kind judges that the polar pattern of storage in 519 pairs of graphics memory parts 516 of part and magnitude pattern compare with the various polar pattern and the magnitude pattern of storing in the reference pattern storage area 518, judge defect kind.Storing the grade reference pattern of the utmost points such as expression defective corresponding in the level patterns storage area 520 in advance with the light quantity of various defectives.Defect rank judges that part 521 compares with the maximum visual suitable charge Imax of storage in the light quantity storage area 517 with by the grade reference pattern of storing in the equal utmost point graphics memory of the defect kind part 520 of determining defects part 519 judgements, judges the grade of defective.Output 522 will judge that the defect kind of part 521 output and the grade of defective export to not shown display device or pen recorder from defect rank.

Action when secondly explanation is checked steel plate 504 surperficial with the surface examining device that as above constitutes.

Sending the polarized light that reflects on steel plate 504 surfaces of moving with certain speed the back from light projection unit branch is received by 3 eyeglass formula linear array gamma cameras 503.The reflected light that incides the steel plate 504 in the 3 eyeglass formula linear array gamma cameras 503 is separated by beam splitter 507, by inciding linear array transducer 509a～509c behind analyzer 508a, 508b, the 508c.When with this linear array transducer 509a～509c detection of reflected light intensity, because the different analyzer 508a～508c in position angle is arranged on the front of this linear array transducer 509a～509c, so linear array transducer 509a～509c detects the intensity I of different polarized lights respectively ₁, I ₂, I ₃, and send signal processing 512 to.

The Signal Pretreatment part 513a～513c of signal processing 512 is to the intensity of polarization light signal I from linear array transducer 509a～509c output ₁, I ₂, I ₂Carry out the tint correction etc. of the inconsistent grade of sensitivity of broad ways etc., so shown in the flaw indication distribution plan among Figure 45, carried out standardization, the signal of normal part becomes 128 gray shade scales, the light intensity signal I after the standardization ₁, I ₂, I ₃Deposit I respectively in ₁Storer 514a～I ₃Storer 514c.In Figure 45, (a) expression light intensity signal I ₁Distribution, (b) expression light intensity signal I ₂Distribution, (c) expression light intensity signal I ₃Distribution.515 pairs of defect parameters arithmetic sections are stored in I ₁Light intensity signal I among storer 514a～storer 514c ₁, I ₂, I ₃Distribution in the peak value of the defect part that shows, the value that calculates expression and separately normal part i.e. 128 gray shade scales is being in a ratio of and just still is being negative polar pattern, and to calculate expression be the magnitude pattern of the variable quantity of benchmark with 128 gray shade scales.In example shown in Figure 45, the light intensity signal I after the standardization ₁, I ₂, I ₃The peak value of defect part compare with 128 gray shade scales and just be, so the polar pattern that calculates is (+,+,+), be the light intensity signal I of benchmark with 128 gray shade scales ₁, I ₂, I ₃The variable quantity of defect part peak value be (+38 ,+10 ,+32).As being that benchmark carries out standardization to this variation with the maximal value, then become (1.0,0.26,0.84).To be that the standard of benchmark is for example planted (1.0,0.26,0.84) and calculated as magnitude pattern with the maximal value of this variable quantity.Then polar pattern and the magnitude pattern of calculating deposited in the graphics memory part 516.Defect parameters arithmetic section 515 is according to light intensity signal I ₁, I ₂, I ₃Distribution, use Imax=MAX[I ₂(X)+I ₃(X)-I ₁(X)] the maximum visual suitable light quantity Imax that does not have polarized light is carried out computing after, deposit in the light quantity storage area 517.For example, in example shown in Figure 45, light intensity signal I ₁, I ₂, I ₃The variable quantity of defect part peak value be (+38 ,+10 ,+32), so maximum visual suitable light quantity Imax is " 4 ".

Corresponding to the size of defective, polar pattern and the magnitude pattern corresponding with some types of defectives are determined by experiment, and as shown in figure 46, it are deposited in the reference pattern storage area 518 as reference pattern.In Figure 46, X type～W type defective shows the polar pattern corresponding with X type～various defectives of W type and the reference value of magnitude pattern by for example representing defect kind from harmful degree is low to harmful high order of degree.Corresponding to each X type～various defectives of W type, studied the correlationship of expression light quantity level and defect rank in advance, shown in the correlogram among Figure 47, and deposit in the level patterns storage area 520.

Defect kind judges that 519 pairs of parts are stored in polar pattern in the image storage section 516 and magnitude pattern (under the situation of example shown in Figure 45, be respectively polar pattern (+,+,+) and value figure (1.0,0.26,0.84)) compare with the reference pattern that is stored in the reference pattern storage area 518 shown in Figure 46, judge defect kind.For example under the situation of example shown in Figure 45, be judged to be X type defective.The example that utilizes polar pattern and magnitude pattern to judge some different A type～H type defectives by this method has been shown among Figure 48.When judging this defect kind, even (,-,-) defective B and defective C that for example polar pattern is identical also can be divided into harmful low Y type defective and high Z type defective of harmful degree of degree according to magnitude pattern, and can judge defect kind exactly.In addition, according to the state of defective, shown in defective G,,, just can accurately judge the kind of defective by utilizing the amplitude pattern simultaneously even a symbol difference is arranged in 3 symbols in the polar pattern or be " 0 ".Owing to adopt polar pattern and magnitude pattern to judge defect kind,, can judge defect kind at short notice accurately so can simplify the processing of judging that defect kind carried out.

On the other hand, defect rank judges that part 521 will be stored in the maximum visual suitable light quantity Imax in the light quantity storage area 517 and be judged that by defect kind the defect kind of part 519 judgements compares with the corresponding correlogram of light quantity level and defect rank of representing with X type～various defectives of W type that is stored in the grade level graphics memory part 520, judges the grade of defective.As shown in figure 47, under the situation of X type defective, when maximum visual suitable light quantity Imax was " 4 ", the grade of judgement defective is B very, and under the situation of Y type defective, when maximum visual suitable light quantity Imax was " 37 ", judgement defective etc. are C very.Owing to judge the grade of defective, go up the non-concavo-convex decorative pattern shape defective that produces so can not only judge steel plate 504 surfaces accurately, and can judge the size of concavo-convex defective accurately like this according to visual suitable light quantity Imax of maximum and defect kind.Defect rank judges that part 521 will send output to by the defect kind of defect kind detection unit 519 judgements and the defect rank of judgement.Output 522 will judge that the defect kind and the defect rank of part 521 output export to display device or pen recorder from defect rank.

As mentioned above, the present invention is incided polarized light to be examined on the surface with certain incident angle, detecting its catoptrical a plurality of different intensity of polarization light distributes, make the light distribution standardization of detection, calculate changed polarity and the variable quantity of the different polarization light intensity signal of defect part with respect to normal part, the changed polarity and the variable quantity of calculating compared with predetermined figure respectively, judge defect kind, so processing is simple and can judge defect kind rapidly.

In addition, light distribution according to the optical system output that receives light from each, surface reflection light intensity when the variation of calculating visual suitable light quantity does not promptly have polarized light, change according to the light quantity of calculating, judge the grade of defective, therefore can handle and judge accurately the non-concavo-convex decorative pattern shape defective and the size of concavo-convex defective simply.

Moreover, owing to handle kind and the grade simply and promptly judge defective, structure that therefore can simplification device itself, the lip-deep unusual part of the lamellar goods that the while can online accurately detection high-speed mobile.

Embodiment 7:

Surface inspection of the present invention is characterised in that: have light projection part, test section and signal processing, filling the projection part incides light beam on the whole Width that is examined the surface, the test section has and will be separated into the beam splitter of 3 light beams from the reflected light that is examined the surface, be separately positioned on the light path of 3 separated light beams and the analyzer of different orientations is arranged respectively, and receive the linear array transducer that each analyzer sees through light, this part makes from the reflected light incident that is examined the surface, and be transformed into picture signal, signal processing has defective and waits to look into zone extraction part, parameter arithmetic section and judgement part, defective is waited to look into the zone and is extracted part out and will compare from the concentration level and the predetermined benchmark concentration level of the polarized light image of 3 groups of linear array transducers inputs, the concentration level of the polarized light image measured is exceeded zone beyond the benchmark concentration level range to be waited to look into the zone as defective and extracts out, the parameter arithmetic section waits to look into the interior mensuration light intensity in zone according to the defective of extracting out, calculate elliptic polarization optical parameter and surface reflection light intensity, judge that part compares the grade of decision table planar defect and kind with the elliptic polarization optical parameter calculated and surface reflection strength characteristics with the characteristic of predetermined surface imperfection.

In the present invention, constitute surface examining device by light projection part, light receiving part and signal processing.Light projection part is configured to make light beam to incide on the whole Width that is examined the surface with certain incident angle light source, and polarizer is arranged on light source and is examined between the plane of incidence on surface.Light receiving part is made of 3 groups of linear array transducers and the analyzer that is arranged on the sensitive surface front of each linear array transducer, 3 groups of analyzers are configured to make its position angle to have nothing in common with each other, be that the axis of homology for example is respectively " 0 ", " π/4 ", " π/4 " with the angle that the plane of incidence that is examined the surface constitutes, 3 groups of linear array transducers make the polarized light incident by each analyzer, and will represent that the image that intensity of polarization light distributes exports to signal processing.

Signal processing part is arranged with defective and waits to look into zone extraction part, parameter arithmetic section and judge part.The benchmark concentration level that expression is examined surperficial normal condition is stored in defective in advance and waits to look into the zone and extract out in the part.And concentration level and the benchmark concentration level from the polarized light image of 3 groups of linear array transducers input compared, the zone that the concentration level of the polarized light image measured is exceeded the benchmark concentration level range is waited to look into the zone as defective and is extracted out.Wait to look into the interior mensuration light intensity in zone according to the defective of this extraction, calculate elliptically polarized light parametric t an ψ, COS Δ and surface reflection intensity I by the parameter arithmetic section ₀Thereby, can limit calculation process image-region, shorten the calculation process time.In addition,, descend, improve the accuracy of detection of defective so can prevent the signal level of defect part owing to before the parameter arithmetic section carries out computing, determined defective zone to be looked into.Judge that part compares the elliptic polarization optical parameter calculated and the characteristic of surface reflection light intensity with predetermined character of surface, judge unusual degree.

Figure 49 is the optical system configurations figure of one embodiment of the invention.As shown in the figure, optical system 601 has light projection part 602 and reflected light test section 603.Light projection part 602 with polarized light with certain incident angle to the whole Width that is examined style such as steel plate 604, the polaroid 608 that it has light source 605, is located at the fibre bundle 606 of light source 605 fronts, is located at the lens combination 607 of fibre bundle 606 front ends and is located at lens combination 607 fronts.Light projection part 602 also can use the bar-shaped light source that prolongs along the Width of steel plate 604 to save fibre bundle 606 and lens combination 607 as light source 605.Polaroid 608 is made of for example 1/4 wavelength plate, shown in the configuration instruction figure among Figure 50, and the angle α that the plane of incidence of its axis of homology P and steel plate 604 constitutes ₂Be π/4.Reflected light test section 603 receives from the specular light of steel plate 604 with reflection angle i reflection, along the specular light of steel plate 604, arrange along the Width of steel plate 604 linear array gamma camera 610a, 610b, the 610c that beam splitter 609a, 609b is housed, is made of for example CCD and the analyzer 611a, the 611b that are located at linear array gamma camera 610a, 610b, 610c sensitive surface front, the camera 612 of 611c are set with reflection angle i reflection.Analyzer 611a, 611b, 611c are made of for example 1/4 wavelength plate, as shown in figure 50, and the angle α that the plane of incidence of the axis of homology of analyzer and steel plate 604 constitutes ₂Dispose like this, i.e. the α of analyzer 611a ₂=0, the α of analyzer 611b ₂=π/4, the α of analyzer 611c ₂=-π/4.

The linear array gamma camera 610a of reflected light test section 603,610b, 610c shown in the block diagram among Figure 51, are connected on the signal processing 613.Signal processing 613 have many-valued frame memory 614a, 614b, 614c, double quantification processing section 615, diadic storer 616a, 616b, 616c, " or " processing section 617, diadic storer 618, defective wait to look into the zone and extract part 619, parameter arithmetic section 620, tan ψ storage area 621a, COS Δ storage area 621b, I out ₀Storage area 621c and judgement part 620.Represent respectively from the intensity of reflected light I of linear array gamma camera 610a, 610b, 610c output at many-valued frame memory 614a, 614b, 614c ₁, I ₂, I ₃Picture signal launch by each pixel, form polarized light image.Double quantification processing section 615 makes the polarized light image double quantification that is stored among many-valued frame memory 614a, 614b, the 614c, and deposits among diadic storer 616a, 616b, the 616c." or " 617 pairs of processing sections each pixel of being stored in the diadic image among diadic storer 616a, 616b, the 616c carry out " or " handle, and deposit in the diadic storer 6118.Defective is waited to look into the zone and is extracted part 619 out according to each image color that is stored in the diadic image in the diadic storer 618, determines that defective waits to look into the position in zone.Parameter arithmetic section 620 is defined as the light intensity I that defective waits to look into regional location according to expression ₁, I ₂, I ₃Picture signal, the elliptic polarization optical parameter of calculating each pixel is an amplitude reflectivity than tan ψ and the COS of expression phase difference and the catoptrical surface reflection intensity I of steel plate 604 ₀, and deposit tan ψ storage area 621a, COS Δ storage area 612b and I in ₀Among the storage area 621c.Judge the character of surface of storing the steel plate 604 of trying to achieve in advance in the part 6222, promptly there be tan ψ, COS Δ and the surface reflection intensity I of so-called decorative pattern shape defectives such as thin oxide film etc. or coating film thickness be inhomogeneous or concavo-convex defective correspondence in inhomogeneous, the small maldistribution of smooth finish of physical parameter, part ₀Various characteristics, and with tan ψ storage area 621a, COS Δ storage area 621b and I ₀The tan ψ that stores among the storage area 621c, COS Δ and surface reflection intensity I ₀Characteristic with storage in advance compares by each pixel, judges and export steel plate 604 surfaces to have or not decorative pattern shape defective or concavo-convex defective and kind and size.

Before the action of the surface examining device that explanation as above constitutes, the light intensity that detects according to 3 linear array gamma camera 610a, 610b, 610c at first is described, calculate the surface reflection intensity I of amplitude reflectivity than tan ψ, COD Δ and steel plate 604 ₀Principle.

As shown in figure 50, establish the angle that the plane of incidence of the axis of homology A of the axis of homology P of polaroid 608 and analyzer 611 and steel plate 604 constitutes and be respectively α ₁, α ₂, then with any incident angle i incide on the steel plate 604 P polarized light component after the reflection and S polarized light component by analyzer 611 the light intensity I (α after synthetic ₁, α ₂) represent with following formula, and the amplitude reflectivity of establishing P component and S component is respectively γ _P, γ _SI(α ₁·α ₂)＝|E _ocosα ₁·r _pcosα ₂+E _osinα ₁·r _ssinα ₂| ²

＝I _oR _p〔cos ²α ₁·cos ²α ₂+ρ ²sin ²α ₁·sin ²α ₂

+ (1/2) sin2 α ₁Sin2 α ₂The cos Δ) I in the formula _o=| E _o| ², r _p= R _pExp (i  _p), r _s= R _sExp (i  _s) ρ=r _s/ r _p=tan ψ, Δ= _s- _p

Here work as α ₁α is passed through in=π/4 o'clock ₂The light intensity I of=0 analyzer 611a ₁Become I ₁=I ₀R _P/ 2, pass through α ₂The light intensity I of the analyzer 611b of=π/4 ₂Become I ₂=I ₀R _P(1+ ρ ²+ 2 ρ COS Δs)/4, pass through α ₂The light intensity I of the analyzer 611c of=-π/4 ₃Become I ₃=I ₀R _P(1+ ρ ²-2 ρ COS Δs)/4.According to these light intensity I ₁, I ₂, I ₃By following various tan ψ, COS Δ and the surface light reflection strength I of trying to achieve respectively ₀ $\tan \mathrm{\&Psi;}=\sqrt{\frac{I_1}{I_2+I_3-I_1}}$ $\cos \mathrm{\&Delta;}=\frac{I_2-I_3}{2I_1}\tan \mathrm{\&Psi;}$

I ₀＝I ₂+I ₃-I ₁

Secondly the action of the surface examining device of above-mentioned principle is used in explanation.The polarized light that after the light projection unit is divided outgoing, reflects on steel plate 604 surfaces of moving with certain speed separated by beam splitter 609a, 609b and by analyzer 611a, 611b, 611c after incide linear array gamma camera and 610a, 610b, the 610c.During with this linear array gamma camera 610a, 610b, 610c detection of reflected light intensity, because α ₂=0 analyzer 611a is located at the front of linear array gamma camera 610a, so linear array gamma camera 610a detects light intensity I ₁, because α ₂The analyzer 610b of=π/4 is located at the front of linear array gamma camera 610b, detects light intensity I so linear array videotapes with 610b ₂, because α ₂The analyzer of=-π/4 is located at the front of linear array gamma camera 610c, so linear array gamma camera 610c detects light intensity I ₃Represent light intensity I with what linear array gamma camera 610a, 610b, 610c detected ₁, I ₀, I ₃Picture signal in many-valued frame memory 612a, 612b, 612c, launch respectively, shown in the picture specification figure among Figure 52 (a), form I ₁Polarized light image 624a, I ₂Polarized light image 624b and I ₃Polarized light image 624a.Here, linear array gamma camera 610a, 610b, 610c adjust optical position makes the visual field identical with angle, thereby the light intensity I that detects in same timing ₁, I ₂, I ₃It is the light intensity of the same position reflection of steel plate 604.When can not be when same timing detects the reflected light of same position with linear array gamma camera 610a, 610b, 610c, delay circuit etc. is located at the output terminal of linear array gamma camera 610a, 610b, 610c, make that the detection position is consistent with the time to get final product.

Many-valued frame memory 612a, 612b, 612c are made of for example vertical 200 lines of horizontal 1024 pixel X, in same timing the data on the line in 1024 pixels are sampled, and should sample and store successively till 200 lines, form I ₁Polarization fills image 624a, I ₂Polarized light image 624b and I ₃Polarized light image 624c.Double quantification processing section 625 utilizes surface smoothness or the predefined double quantification level of oil surface state of pressing steel plate 604, shown in Figure 52 (b), to I ₁Polarized light image 624a, I ₂Polarized light image 624b and I ₃Polarized light image 624c carries out double quantification to be handled, and double quantification image 625a, 625b, 625c are deposited in respectively among double quantification storer 618a, 618b, the 618c.Carry out this double quantification double quantification level when handling and be according to the surface smoothness of steel plate 604 or the decision of oil surface state, but also can try to achieve automatically, and be set at noise level according to the peak value or the deviation of the data of measuring.In addition, because difference with defect kind, for normal part, be high level sometimes, be low level sometimes, therefore shown in Figure 53, normal level is set positive and negative two kinds of double quantification level 626a, 626b, carry out double quantification and handle, shown in Figure 52, for example make defect part 627a, 627b for white, make normal part 628 for black.

This double quantification image 625a, 625b, 625c are I ₁, I ₂, I ₃3 images, shown in Figure 52 (b) because defective 627a, 627b can unify to detect and unrestricted as exceptional value in 3 images, therefore shown in Figure 52, with " or " handling part 617 presses each pixel to I ₁, I ₂, I ₃The diadic image carry out " or " handle, and will " or " handle image 629 and deposit diadic storer 618 in.Defective wait to look into the zone extract out part 619 obtain show be stored in the diadic storer 618 " or " position of handling the white portion of defect part 627a, 627b in the image 629, shown in Figure 52 (d), 2 somes P in the upper right corner for example among regional 630a, the 630b is waited to look into as defective in the bounding rectangle zone of white portion ₁, P ₃The P in the point and the lower left corner ₂, P ₄The coordinate of point determines that defective waits to look into regional 630a, 630b, sends parameter arithmetic section 620 to.Parameter arithmetic section 620 is read with the defective that sends from many-valued frame memory 612a, 612b, 612c and is waited to look into the corresponding light intensity I of each pixel regional 630a, the 630b ₁, I ₂, I ₃, calculating the elliptic polarization optical parameter by each pixel is the intensity of reflected light I of amplitude reflectivity than tan ψ, phase place COS Δ and steel plate 604 surfaces ₀, and deposit result of calculation in tan ψ storage area 621a, COS Δ storage area 621b and I successively ₀Among the storage area 621c.Because only each pixel that defective is waited to look among regional 630a, the 630b calculates elliptic polarization optical parameter etc.,, can shorten computing time significantly so compare when Zone Full to image calculates.

Judge that part 622 is with tan ψ storage area 621a, COS Δ storage area 621b and I ₀The ton ψ that stores among the storage area 621c, COS Δ and surface reflection intensity I ₀Character of surface with the steel plate 604 that each pixel is tried to achieve in advance compares, and by combination, sees that variation has taken place which parameter, judges the kind of defective and treats level, exports to not shown display device or pen recorder.In addition, oil film is inhomogeneous to be extracted out as the high defective of concentration scale in polarized light image, but by tan ψ, COS Δ and surface reflection light intensity grave I ₀Combination is not as with surface imperfection when suitable, not as determining defects.

By kind and grade from judgement part 622 output defectives, definite simultaneously and output is waited to look into regional defective of extracting part 619 extractions out by defective and is waited to look into regional 630a, the coordinate of 630b can also detect the size of defective, and can detect the state of defective more accurately.

Like this when detecting the surface imperfection of steel plate 604, usually, the surface imperfection size of steel plate 604 be wide 5mm, below the long 200mm, the generation frequency be vertical tens of Mi Neiyue appearance once.Therefore, as mentioned above, when the size of many-valued frame memory 614a～614c constitute 200 lines of for example horizontal 1024 pixels * vertical the time, as the resolution of establishing 1 pixel is horizontal 0.5mm * vertical 5mm, the width that the size of then many-valued frame memory 614a～614c is equivalent to steel plate 604 is 500mm, length is 1.0m, therefore the number of picture elements of the surface imperfection in 1 image is about horizontal 10 pixels * vertical 40 pixels, compare during with whole pixel of computed image the computing time of calculating elliptic polarization optical parameter etc., is below 1/500.Even therefore do not use special arithmetic unit, there are operation time tens of milliseconds just much of that, when for example even steel plate 604 per minutes move hundreds of meters, the time that forms the image of 200 lines is 100 milliseconds, the defective on the steel plate 604 that therefore can online reliably detection moves.

As mentioned above, the present invention compares the concentration level and the benchmark concentration level that are examined surperficial polarized light image from 3 groups of linear array transducer inputs, the concentration level of the polarized light image measured is exceeded zone beyond the benchmark concentration level range to be waited to look into the zone as defective and extracts out, wait to look into the interior mensuration light intensity in zone according to the defective of extracting out, calculate judgement and be examined elliptic polarization optical parameter and the surface reflection light intensity that surface imperfection is used, owing to limit the pixel area of calculation process, so compare during with whole pixel of calculating polarized light image, can shorten the calculation process time significantly.Therefore, the sheet-like material surface imperfection such as steel plate that can move with the online accurately detection of light beam.

In addition,, therefore can make the device overall simplification, reduce installation cost because the overall process ability of device not quite also can be competent at.

Embodiment 8:

Surface examining device of the present invention is characterised in that: have light projection part, light receiving part and signal processing, light projection part incides light beam on the whole Width of detected surface, light receiving part has and will be separated into the beam splitter of 3 light beams from the reflected light that is examined the surface, be located on the light path of 3 separated light beams respectively and the analyzer that has different orientations respectively, and receive the linear array transducer that each analyzer sees through light, this part makes from the reflected light incident that is examined the surface, and being transformed into picture signal, signal processing has the parameter arithmetic section, defective is waited to look into the zone and is proposed part, characteristic quantity arithmetic section and determining defects part; The parameter arithmetic section is calculated elliptic polarization optical parameter and surface reflection intensity according to the light intensity of the polarized light image of importing from linear array transducer, defective is waited to look into the zone and is extracted part out and the image color level of elliptic polarization optical parameter and surface reflection light intensity is exceeded zone beyond the benchmark concentration level range that is equivalent to the matrix surface level wait to look into the zone as defective and extract out, the characteristic quantity arithmetic section is calculated defective that expression extracts out and is waited to look into the maximal value of elliptic polarization optical parameter in the zone and surface reflection light intensity grave and the mean value polarity with respect to the size of normal part, and calculate defect characteristic amount by the combinations of polarities decision of elliptic polarization optical parameter of being calculated and surface reflection light intensity, the determining defects part is according to the kind of the defect characteristic amount decision table planar defect that calculates.

Defective is waited to look into the interior elliptic polarization optical parameter in zone to above-mentioned characteristic quantity arithmetic section and the defect characteristic amount that combinations of polarities determined of surface reflection light intensity is carried out computing, simultaneously defective is waited to look into the defect characteristic amount that the light intensity combination of polarized light image different in the zone determined and carry out computing, determining defects part basis is by the defect characteristic amount of the combinations of polarities decision of elliptic polarization optical parameter that calculates and surface reflection light intensity and the defect characteristic amount that is determined by light intensity, the kind of decision table planar defect and grade.

In the present invention, constitute surface examining device by light projection part and light receiving part.Light projection part is configured to light source light beam is incided with certain incident angle on the whole Width that is examined the surface, and at light source be examined between the plane of incidence on surface and be provided with polarizer, the polarization angle that polarized light is certain incides and is examined on the surface.Light receiving part is made of 3 groups of linear array transducers and the analyzer that is located at the sensitive surface front of each linear array transducer, 3 groups of analyzers have different position angles respectively, be that the axis of homology for example is configured to " 0 ", " π/4 ", " π/4 " respectively with the angle that the plane of incidence that is examined the surface constitutes, 3 groups of linear array transducers make the polarized light incident by each analyzer, and will represent that the image that intensity of polarization light distributes outputs to signal processing.

Being provided with parameter arithmetic section, defective in the signal processing waits to look into the zone and extracts part, characteristic quantity arithmetic section and determining defects part out.The parameter arithmetic section is calculated elliptically polarized light parametric t an ψ, COS Δ and surface reflection intensity I according to the light intensity of the polarized light image of importing from 3 groups of linear array transducers ₀, form tan ψ image, COS Δ image and I ₀Image.Wait to look into the zone in defective and extract out and storing the benchmark concentration level that expression is examined the normal condition of face in the part in advance, perhaps automatically obtain according to the peak value of determination data or deviation etc.And with the image and the I of 3 groups of tan ψ images, COS Δ ₀The concentration level of image compares with the benchmark concentration level, with tan ψ image, COS Δ image and I ₀The zone extraction is waited to look into as defective in the zone that the concentration level of image exceeds beyond the benchmark concentration level range.The defective of taking out this extraction by the characteristic quantity arithmetic section waits to look into elliptically polarized light parametric t an ψ, COS Δ and the surface reflection intensity I of each pixel in the zone ₀And calculate expression maximal value or mean value polarity and variable quantity, and calculate defect characteristic amount by the combinations of polarities decision of elliptic polarization optical parameter of calculating and surface reflection light intensity with respect to the size of normal part.Determining defects part basis is by elliptically polarized light parametric t an ψ, COS Δ and the surface reflection intensity I calculated ₀The defect characteristic amount of combinations of polarities decision, the kind of decision table planar defect.

Like this owing to detect with the sensitive elliptically polarized light parametric t an ψ that changes of the feature that is examined the surface and COS Δ judging having or not of defective, thus can also detect with scattered light or diffraction the variation of non-detectable surface physical characteristic.In addition, wait to look into the zone again according to elliptically polarized light parametric t an ψ, COS Δ and surface reflection intensity I owing to determined defective ₀Combinations of polarities and variable quantity, judge and the kind of defective, to improve the accuracy of detection of defective simultaneously so can judge the kind of defective simply.

In addition, judge the kind time-like of defective, owing to wait to look into elliptically polarized light parametric t an ψ, the COS Δ in the zone and face intensity of reflected light I is arranged according to defective ₀The combination of change in polarity of combination of change in polarity and the mensuration light intensity of defect part, the defective that decision polarity can change is so can more carefully judge the kind and the grade of defective.

Figure 54 is the optical system configurations figure of one embodiment of the invention.As shown in the figure, optical system 701 has light projection part 702 and light receiving part 703.Light projection part 702 incides polarized light on the whole Width that is examined style such as steel plate 704 polarizer 708 that it has light source 705, is located at the fibre bundle 706 of light source 705 fronts, is located at the lens combination 707 of fibre bundle 706 front ends and is located at lens 707 fronts with certain incident angle.Light projection part 702 also can adopt bar-shaped light source along the Width elongation of steel plate 704 as light source, and fibre bundle 706 and lens combination 707 are saved.Polarizer 708 is made of polaroid or polarizing filter, shown in Figure 55, and the angle α that the plane of incidence of its axis of homology P and steel plate 704 constitutes ₂Be configured to π/4.Light receiving part 703 receives from the specular light of steel plate 704 with reflection angle θ reflection, arranges to be provided with along steel plate 704 Widths beam splitter 709a, 709b, the linear array gamma camera 710a, 710b, the 710c that for example are made of CCD and the analyzer 711a, the 711b that are located at linear array gamma camera 710a, 710b, 710c sensitive surface front, the camera 712 of 711c are housed.Analyzer 711a, 711b, 711c are made of for example polaroid or polarizing filter, shown in Figure 55, and the angle α that the plane of incidence of the axis of homology of analyzer 711 and steel plate 704 constitutes ₂Dispose like this, i.e. the α of analyzer 711a ₂=0, the α of analyzer 711b ₂=π/4, the α of analyzer 711c ₂=-π/4.Linear array gamma camera 710a～710c represents steel plate 704 intensity of reflected light I with certain cycle as a line signal output ₁, I ₂, I ₃Picture signal.

The linear array gamma camera 710a of light receiving part 703,710b, 710c are connected on the signal processing 713, shown in the block diagram among Figure 56.Signal processing 713 have preprocessing part 714a, 714b, 714c, frame memory 715a, 715b, 715c, parameter arithmetic section 716, storer 717, rim detection part 718, luminance nonuniformity repay part 719, double quantification processing section 720, storer 721, " or " processing section 722, diadic storer 723, defective wait to look into the zone and extract part 724, characteristic quantity arithmetic section 725 and determining defects part 726 out.

Preprocessing part 714a～714c is to the expression intensity of reflected light I from linear array gamma camera 710a～710c output ₁, I ₂, I ₃Picture signal carry out the addition average calculating operation, detect the line amount of movement of steel plate 704 simultaneously, and the signal after average sends the frame memory 715a～715c of each bar circuit to addition.Frame memory 715a～715c is made of for example vertical 200 lines of horizontal 1024 pixel X., store successively only to the data sampling of a line of 1025 pixels in same timing, form 2 D polarized image up to 200 lines.Parameter arithmetic section 716 is according to the light intensity I that is stored in each pixel of expression polarized light image in frame memory 715a～715 ₁, I ₂, I ₃Picture signal, calculating the elliptic polarization optical parameter is that amplitude reflectivity is than tan ψ and the COS Δ of expression phase differential and the surface reflection intensity I of steel plate 706 ₀, as tan ψ view data, Δ view data and I ₀View data deposits in the storer 717.Rim detection part 718 detects tan ψ image, Δ image and I ₀The marginal portion of the steel plate 704 in the image.719 pairs of luminance nonuniformity compensated part are compensated by the intensity inequality of light source 705 or the uneven Width light intensity inequality that produces of steel plate reflectivity and the sensitivity inequality that accompanies with it.Double quantification processing section 720 couples of tan ψ image, Δ image and I ₀Image carries out diadic than processing, and deposits in respectively in the storer 721." or " 722 pairs of processing sections are stored in tan ψ, Δ, the I in the storer 721 ₀Each pixel of diadic image carry out " or " deposit in the diadic storer 723 after handling.Defective is waited to look into the zone and is extracted part 724 out according to each the pixel concentration that is stored in the diadic image in the diadic storer 723, determines that defective waits to look into the position in zone.Characteristic quantity arithmetic section 725 taking-up defectives wait to look into tan ψ, Δ, the I in the zone ₀, calculate maximal value or mean value, make characteristic quantity obvious.Determining defects part 726 waits to look into tan ψ, Δ, I in the zone according to the expression defective ₀Maximal value or mean value compare the comparatively polarity and the variable quantity of positive region negative region with normal part, judge unusual degree.

Before the action of the surface examining device that explanation as above constitutes, at first explanation is calculated the surface reflection intensity I of amplitude reflectivity than tan ψ, COS Δ and steel plate 704 according to the light intensity that is detected by 3 linear array gamma camera 710a, 710b, 710c ₀Principle.

Shown in Figure 55, as establish the angle that the plane of incidence of the axis of homology A of the axis of homology P of polarizer 708 and analyzer 711 and steel plate 704 constitutes and be respectively α ₁, α ₂, then with any incident angle θ incide the P polarized light component of steel plate 704 back reflections and S polarized light component by analyzer 711 the light intensity I (α after synthetic ₁, α ₂) represent with following formula, and the amplitude reflectivity of establishing P component and S component is respectively γ _P, γ _SI(α ₁·α ₂)＝|E _ocosα ₁·r _pcos _α2+E _osinα ₁·r _ssinα ₂| ²

＝2I _o〔ρ ²cos ²α ₁·cos ²α ₂+sin ²α ₁·sin ²α ₂

+(1/2)ρsin2α ₁·sin2α ₂·cosΔ〕

I in the formula _o=| E _o| ²R _s/ 2, $r_p={\sqrt{R}}_p\&CenterDot;\exp \left(i{\mathrm{\&phi;}}_p\right),$ $r_s={\sqrt{R}}_s\&CenterDot;\exp \left(i{\mathrm{\&phi;}}_s\right),$ $\mathrm{\&rho;}={\sqrt{R}}_P,/\sqrt{R_S}=\tan \mathrm{\&Psi;},$ Δ＝ _P- _S

Here, work as α ₁α is passed through in=π/4 o'clock ₂The light intensity I of=0 analyzer 711a ₁Become I ₁=I ₀ρ ², pass through α ₂The light intensity I of the analyzer 711b of=π/4 ₂Become I ₂=I ₀(1+ ρ ²+ 2 ρ COS Δs)/2, pass through α ₂The light intensity I of the analyzer of=-π/4 ₃Become I ₃=I ₀(1+ ρ ²-2 ρ COS Δs)/2.According to these light intensity I ₁, I ₂, I ₃, by following various tan ψ, COS Δ and the surface reflection intensity I of trying to achieve ₀ $\tan \mathrm{\&Psi;}=\sqrt{\frac{I_1}{I_2+I_3-I_1}}$ $\cos \mathrm{\&Delta;}=\frac{I_2-I_3}{2I_1}\tan \mathrm{\&Psi;}$

I _o=I ₂+ I ₃-I ₁But, light intensity I ₁, I ₂, I ₃With the system of selection difference of amplifier gain of gamma camera etc., also be constant times sometimes.

Secondly the action of the surface examining device of above-mentioned principle is used in explanation.Separated by beam splitter 709a, 709b from the polarized light that reflects on steel plate 704 surfaces of moving after the light projection unit is divided outgoing, by inciding linear array gamma camera 710a, 710b, 710c behind analyzer 711a, 711b, the 711c with certain speed.During with this linear array gamma camera 710a, 710b, 710c detection of reflected light intensity, owing to be provided with α in the front of linear array gamma camera 710a ₂=0 analyzer 711a is so linear array gamma camera 710a detects light intensity I ₂Owing to be provided with α in the front of linear array gamma camera 710b ₂The analyzer 711b of=π/4 is so linear array gamma camera 710b detects light intensity I ₂Owing to be provided with α in linear array gamma camera 710c front ₂The analyzer 711c of=-π/4 is so linear array gamma camera 710c detects light intensity I ₃Represent light intensity I with what linear array gamma camera 710a, 710b, 710c detected ₁, I ₂, I ₃Picture signal carry out pre-service by preprocessing part 714a～714c respectively after, in frame memory 715a～715c, launch, shown in the picture specification figure among Figure 57 it (a), form I respectively ₁Polarized light image 726a, I ₂Polarized light image 726b, I ₃Polarized light image 726c.Here, linear array gamma camera 710a, 710b, 710c reach same field of view by the adjustment of its optical position and angle, thereby the light intensity I that detects in same timing ₁, I ₂, I ₃It is the light intensity of light of the same position reflection of steel plate 704.In addition, as can not when same timing detects the reflected light of same position, can delay circuit etc. being set, make the detection position consistent with timing at the output terminal of linear array gamma camera 710a, 710b, 710c with linear array gamma camera 710a, 710b, 710c.

Parameter arithmetic section 716 is according to the light intensity I that is stored in each pixel of expression polarized light image 731a～731c among frame memory 715a～715c ₁, I ₂, I ₃Picture signal, calculating the elliptic polarization optical parameter is that amplitude reflectivity is than tan ψ, the COS Δ of expression phase difference and the surface reflection intensity I of steel plate 704 ₀, as tan view data, COS Δ view data and I ₀View data deposits in the storer 717.Shown in Figure 58, because the tan ψ image, COS Δ image and the I that in storer 717, launch ₀In the zone of the steel plate 704 in the image, the signal level height, in the background area that is not steel plate 704, signal level is low, so rim detection part 718 is defined as the marginal portion of steel plate 704 with signal level point jumpy, and is defined as the signal Processing zone.Shown in Figure 59 (a), the tan ψ in this signal Processing zone, COS Δ and I ₀The signal intensity broad ways of 1 line very big inequality is arranged.Therefore to be repaid part 719 be the center with the reference point to luminance nonuniformity, and the tens of points of signal broad ways move left and right of 1 line are averaged, and shown in Figure 59 (b), makes signal tan ψ m, COS Δ m after the moving average, Iom.And shown in Figure 59 (c), according to signal tan ψ, COS Δ, the I before the moving average ₀With the promptly normal reference level C partly of signal tan ψ, COS Δ m, Iom and expression matrix surface after the moving average, calculate compensating signal tan ψ c, COS Δ c, the Ioc of each pixel by following formula.A is a constant in the following formula. $\tan \mathrm{\&Psi;c}=\frac{\tan \mathrm{\&Psi;}-\tan \mathrm{\&Psi;m}}{\tan \mathrm{\&Psi;}}-C$ $\cos \mathrm{\&Delta;c}=\frac{\cos \mathrm{\&Delta;}-\cos \mathrm{\&Delta;m}}{\cos \mathrm{\&Delta;}}-C$ $I_{o}c=\frac{I_o-I_{o}m}{I_o}-C$

Shown in Figure 59 (c), in the signal after this luminance nonuniformity compensation, look the signal level of defective 733a bright than the reference level C height of normal part 734 with respect to the promptly normal part of the matrix surface of steel plate 704, look that with respect to normal part the signal level of dark defective 733b is lower than reference level C.Carry out double quantification by the image after 725 pairs of these compensation in double quantification processing section and handle, with tan ψ, COS Δ and I ₀The double quantification image deposit in respectively in the storer 721.Carry out of surface smoothness or the oil surface state decision of this double quantification double quantification level when handling, but also can try to achieve automatically, be set at noise level according to the peak value of the data of measuring or deviation etc. by pairing steel plate 704.In addition, because defective is along with the difference of kind, sometimes be high level, be low level sometimes with respect to the level of normal part, therefore shown in Figure 60, can be with respect to normal level, set positive and negative two kinds of double quantification level 735a, 735b, carrying out double quantification handles, work as signal level in positive double quantification processing and set normal part, is white and set normal part when signal level is beyond positive double quantification level 735a and negative double quantification level 735b, is black in the time of in the scope of double quantification level 735a, 735b.

This diadic has tan ψ c, COS Δ c, Ioc3 kind image than image, and for example, shown in Figure 57 (b), defective 733a, 733b are general for 3 kinds of images, can be used as that exceptional value detects and unrestricted.Therefore " or " 722 pairs of the processing sections diadic image that is stored in tan ψ c, COS Δ c in the storer 721 and Ioc by each look like to carry out " or " handle, and will " or " handle image and deposit in the diadic storer 723.Defective wait to look into the zone extract out part 724 obtain expression be stored in the diadic storer 723 " or " position of handling the white portion of image 736 defect part 733a, 733b, shown in Figure 57 (d), the rectangular region that white portion is external is waited to look into regional 737a, 737b as defective and is extracted out, waits to look into two somes P in the upper right corner for example among regional 737a, the 737b according to defective ₁, P ₃The P in the point and the lower left corner ₂, P ₄The coordinate of point is determined that defective waits to look into regional 737a, 737b, and is sent characteristic quantity arithmetic section 725 to.Characteristic quantity arithmetic section 725 takes out tan ψ c, COS Δ c and the Ioc that defective waits to look into each pixel among regional 737a, the 737b, maximizing or mean value, and obtain maximal value or the mean value that the expression defective waits to look into tan ψ, COS Δ and Ioc among regional 737a, the 737b and compare with the reference level of normal part in the positive region or the polarity of negative region, calculate defect characteristic amount Epp such as polar pattern with for example Epp=9 Δ p+34p+Ip.Here, ψ p represents the polarity of tan ψ p, and Δ p represents the polarity of COS Δ c, I _PThe polarity of representing Ioc, available numeric representation, for example polarity is timing, with " 2 " expression, uses " 1 " expression when identical with normal part, represents with " 0 " when polarity is negative.

Determining defects part 726 uses the defective that sends to wait to look into the defect characteristic amount Epp of regional 737a, 737b, judges the kind of defective.For example result and the defect characteristic amount E to the change in polarity research of the different defect kind S on the cold-rolled steel sheet, T, U, the pairing tan ψ of V, W c, COS Δ c, Ioc is shown in Figure 61, and the result and the defect characteristic amount E of the change in polarity research of the different pairing tan ψ of defect kind S, X, Y, V, the W c on the coated steel plate, COS Δ c, Ioc is shown in Figure 62.Therefore determining defects part 726 is judged the kind of defective according to the defect characteristic amount E of these defect kinds and the defect characteristic amount Epp that is calculated by characteristic quantity arithmetic section 725.That is, shown in Figure 61, Figure 62, when 1 of the polarity by tan ψ c, COS Δ c, Ioc or 2 combinations can not be judged defect kind,, just can distinguish the kind of defective more significantly by 3 combinations of polarities of tan ψ c, COS Δ c, Ioc.Therefore, for example under the situation of cold-rolled steel sheet, when defect characteristic amount Epp is " 0 ", judge that defective is the T type; Defect characteristic is Epp when being " 1 ", and the judgement defective is a V-type; When defect characteristic amount Epp is " 12 ", judge that defective is the W type; When defect characteristic amount Epp is " 18 ", judge that defective is the S type; When defect characteristic amount Epp is " 24 ", judge that defective is the U type.

Even this defect kind is with a kind of defective S type for example, the overlooker when carrying out visual judgement, also will be again with exhaustive divisions such as the length of defective and width.Therefore, characteristic quantity arithmetic section 725 is obtained defective and is waited to look into light intensity I among regional 737a, the 737b when calculating defective and waiting to look into the defect characteristic amount EPP of polar pattern of the tan ψ c of each pixel among regional 737a, the 737b, COS Δ c, Ioc ₁, I ₂, I ₃Change in polarity with respect to normal part, according to this change in polarity, with above-mentioned the same, obtain the defect characteristic amount Ipp of polar pattern of expression light intensity, distinguish defect kind in detail with the defect characteristic amount Ipp of the light intensity of defect part again with the defect characteristic amount Epp judgement of tan ψ c, COS Δ c, Ioc.Like this, can not only know the kind of defective, and can also know its grade, therefore can judge defective more reliably.By such judgement defect kind and grade, the same during with visual judgement with the overlooker, can judge defective accurately.

The foregoing description has illustrated the situation of directly calculating tan ψ, COS Δ and Io according to polarized light image, but also can be by detecting defective zone to be looked into, only calculate defective and wait to look into zone interior tan ψ, COS Δ and Io, perhaps wait to look into the interior representative value in zone for example maximal value or mean value, calculate tan ψ, COS Δ and Io according to defective.

In addition, the foregoing description has illustrated use one-dimensional linear sensor array 710a～710c, detects the catoptrical situation from steel plate 704, but also can utilize the reflected light of two-dimentional gamma camera detection from steel plate 704.

As mentioned above, the present invention extracts defective zone to be looked into out from 3 kinds of different polarized light image, calculates elliptically polarized light parametric t an ψ, COS Δ and surface reflection intensity I that the expression defective waits to look into each pixel in the zone ₀Maximal value or mean value with respect to the polarity of the size of normal part, elliptically polarized light parametric t an ψ, COS Δ and the surface reflection intensity I calculated according to expression ₀The defect characteristic amount of change in polarity combination, judge the kind of defective, therefore can detect with scattered light or diffraction the variation of non-detectable surface physical characteristic, can improve the accuracy of detection of defective.

In addition, judge the kind time-like of defective, wait to look into the elliptically polarized light parametric t an ψ in the zone, the surface reflection intensity I of COS Δ except carrying out defective ₀The combination of change in polarity outside, also carry out 3 kinds of combinations of measuring the change in polarity of light intensity of defect part, by judging defective, can more carefully judge the kind and the grade of defective by these combination decisions.

Claims (5)

1. surface detection apparatus comprises:

Polarized light is incided be examined lip-deep light projecting apparatus;

Have the optical system of the some reception light that receive at least 3 direction polarized lights, detect the optical pickup apparatus that is transformed into picture signal behind the reflected light that is examined surface reflection with different special angles; And

Picture signal after conversion is calculated predetermined defect characteristic amount, and the defect characteristic amount of calculating compares with predetermined figure, judges the signal processing apparatus of defect kind.

2. surface detection apparatus according to claim 1 is characterized in that: said signal processing device as the defect characteristic amount, is judged defect kind with the changed polarity of light distribution and variable quantity.

3. according to the surface detection apparatus of claim 1, it is characterized in that: said signal processing device calculating and visual suitable light quantity are judged the grade of defective as the defect characteristic amount.

4. according to the surface detection apparatus of claim 1, it is characterized in that: said signal processing device is calculated the defect characteristic amount after the light distribution of the optical system output that receives light is carried out standardization by predetermined reference value from each.

5. a surface inspecting method comprises the following steps:

Reception is from the polarized light of the different angles of catoptrical at least 3 directions of being examined surface reflection,

According to being subjected to light signal to calculate predetermined defect characteristic amount; And

Defect characteristic amount of calculating and the figure of being scheduled to are compared, judge the kind of defective or the kind and the grade of defective.

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