JPH1139458A - Image input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To input an optical image in a short time by calculating a spectrum for observing a position of intrest with higher contrast than noninterest position and the position of interest with high S/N from spectra. SOLUTION: A printed board 142 is lit previously with white light to individually measure spectral data of materials (bonding pad and resist part) of the printed board 142, and based on the spectrum data, the optimum spectrum for observing the position of interest of an optical image with high S/N and a large difference in light intensity from the position of noninterest. Then the printed board 142 is lit up with illumination light having this optimum spectrum. Consequently, an optimum-contrast image can be obtained over the front of the printed board. The illumination light is the same over the entire area of the printed board, so the input time of the image can be shortened and the image can be inputted in the short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device, and more particularly to an image input device for inputting an optical image of an object illuminated with illumination light having an optimum spectrum.

[0002]

2. Description of the Related Art Scratches, stains, and the like on electronic parts such as printed circuit boards.
In an appearance inspection device that detects a defect such as a stain, what is necessary for oversight detection is to input a better optical image. In this case, a higher contrast is required for a better optical image. For example, Japanese Patent Application Laid-Open No. 8-219716 discloses an input image contrast processing device having an illumination device capable of illuminating with an arbitrary color. In this processing device, an image of a control object such as an electronic component illuminated by the above-described illumination device is captured by an image capturing unit, and the obtained image data is compared with a predetermined reference value. The color of the illumination light from the illumination device is changed by the illumination control device so that the contrast of the portion of interest (such as a reference mark on the electronic component) with respect to the background is increased. In this way, an image in which the contrast of the portion of interest is high with respect to the background is always obtained.

[0003]

However, in the above-mentioned Japanese Patent Application Laid-Open No. 8-219716, the image data is compared with a reference value for each image captured by the image pickup means, and based on the result, the illuminating means is used. Is controlling.
Therefore, since it is necessary to repeat the feedback control every time an image is taken, there is a problem that high-speed processing cannot be realized.

In addition, electronic parts such as printed circuit boards have a high reflectance portion such as a gold-plated bonding pad and a low reflectance portion such as a resist.
There is a problem that the luminance is too different to inspect them simultaneously. The above-mentioned Japanese Patent Application Laid-Open No. 8-219716 discloses a technique for increasing the contrast of a target portion, but does not disclose a technique for reducing a difference in light intensity between portions having different materials.

Accordingly, an object of the present invention is to provide an image in which an optical image can be input in a short time by increasing the contrast of a target region with respect to a non-target region or reducing the contrast of a plurality of different types of target regions. An input device is provided.

[0006]

According to a first aspect of the present invention, there is provided an image input apparatus for inputting an optical image of an object comprising a plurality of different types of parts. Illumination light generating means for generating illumination light for illuminating the object, an illumination optical system for guiding the illumination light to the object, and a first imaging optical system for forming an image of the illuminated object Spectral spectrum acquiring means for acquiring a spectral spectrum of an image of a target region of an object and an image of a non-target region adjacent to the target region, formed by the first imaging optical system; Based on the plurality of spectrums acquired by the acquisition unit, a spectacle for observing the non-interest part with high contrast with respect to the non-interest part and observing the non-interest part with high S / N And the spectrum calculation means for calculating,
A spectrum converting means for converting a spectrum of an optical image of the object based on the spectrum calculated by the spectrum calculating means, and a wavelength sensitivity characteristic equivalent to that of the first imaging optical system, A second imaging optical system for forming an image of the object spectrally transformed by the second imaging optical system, and image input means for inputting an optical image of the object formed by the second imaging optical system And

Further, an image input device according to a second aspect of the present invention comprises:
An image input device for inputting an optical image of an object including a plurality of different types of parts, an illumination light generating means for generating illumination light for illuminating the object, and an illumination optical system for guiding the illumination light to the object A first imaging optical system for forming an image of the illuminated object; and respective spectral spectra in the images of the plurality of different types of target portions formed by the first imaging optical system. Based on a plurality of spectral spectra acquired by the spectral spectrum acquiring unit, the target sites are observed with low contrast, and the target sites are observed with high S / N. Spectrum calculating means for calculating a spectrum for calculating the spectrum of the optical image of the object based on the spectrum calculated by the spectrum calculating means. A second converting optical system for forming an image of the object, which has the same wavelength sensitivity characteristic as that of the first image forming optical system, and is spectrally converted by the first converting optical system; And this second
Image input means for inputting an optical image of the object formed by the image forming optical system.

[0008] An image input device according to a third aspect of the present invention comprises:
In the image input device according to the first or second aspect, the spectrum calculation unit calculates light intensity obtained from each part of the object, and calculates the spectrum based on the light intensity. And the light intensity is

[0009]

(Equation 2) S (λ): transmission spectrum of the spectrum conversion means, e (λ): light source spectrum, t (λ): characteristic spectrum of the optical transmission system, k (λ): sensitivity of the image input means Spectrum, f (λ): reflection spectrum of the object.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, a first embodiment will be described. In the first embodiment, spectral spectra of images of a plurality of portions of an object are respectively acquired under illumination of white light, and the spectral spectra are processed by a statistical method. An optimum spectrum calculating means for calculating an optimum spectrum for observing a high S / N of the target site with a large difference in light intensity from the target site, and performing image input based on the calculated optimum spectrum. The present invention relates to an image input device. Here, the process of calculating the optimum spectrum is called a learning mode, and the process of inputting an image based on the calculated optimum spectrum is called an inspection mode.

First, a statistical method for determining an optimum spectrum will be described. It is assumed that the target object is composed of a plurality of types of members having different materials, but a case where the target is composed of two types will be described below for ease of explanation. Here, the portions made of two different materials are, for example, a gold-plated bonding pad portion 10 and a resist portion 11 on a printed circuit board 12 as shown in FIG. At this time, it is considered to optimize the spectrum of the illumination light so that the contrast is higher in the bonding pad section 10 than the resist section 11 and the S / N of the bonding pad section 10 is observed higher.

The transition of the spectral characteristic due to the process until the reflected light of the object illuminated by the light source light is picked up by the image input device is modeled. The set obtained by measuring the reflection spectra of the bonding pad portion 10 and the resist portion 11 in the target object a plurality of times is represented by Δf ₁
(Λ)｝, {f ₂ (λ)}, and the following spectrum is assumed.

E (λ): spectrum of the light source, t (λ): characteristic spectrum of the optical transmission system, k (λ): sensitivity spectrum of the imaging device, s (λ): transmission spectrum of the spectrum conversion means. At this time, the average intensity g _i of the observation signal of each material _captured
(I = 1, 2) is represented by the following equation.

[0014]

(Equation 3)

Where h _i is the observed spectrum and n _i
i is the additive noise independent of the signal. Also, (S)
Indicates an integration range as a wavelength region limited by the spectrum conversion means. Next, consider the image intensity b detected as the difference between the average intensities g ₁ and g ₂ of the bonding pad portion 10 and the resist portion 11.

[0016]

(Equation 4) Considering that the additive noise n _i (i = 1,2) is Gaussian noise having an average of 0 and a standard deviation σ, the following notation is used.

[0017]

(Equation 5) In this case, the noise n ₁₂ of the difference image defined by the equation (2) can be defined as follows according to the reproducibility of the Gaussian distribution.

[0018]

(Equation 6)

[0019] (5) Since the equation the denominator is the average amplitude of the noise, (4) the nature of the noise n ₁₂ defined in formula <|
n ₁₂ |> = 1.41σ. On the other hand, when the relationship of h ₁ > h ₂ holds, the numerator of equation (5) may be defined as | Δ | = Δ. According to such an assumption, equation (5) can be rewritten as follows.

[0020]

(Equation 7) <| Δ |> defined in the numerator of the equation (5) represents the contrast of the difference image. Therefore, according to the equation (6), it is considered that the improvement of the S / N is equivalent to the improvement of the contrast.

Of each spectrum included in the equation (6),
What can be changed is the transmission spectrum s of the spectrum conversion means.
(Λ) alone and the other k (λ) and t (λ) are considered to be unchangeable. Therefore, equation (6) is redefined as follows.

[0022]

(Equation 8) However, the following definition is made.

[0023]

(Equation 9) Further, only the integral term of the equation (7) is picked up.

[0024]

(Equation 10) Next, in order to facilitate the analysis, the equation (9) is converted into a discrete system.

[0025]

[Equation 11] Here, s and Δ are vectors, and the subscript t represents a transposed matrix. Equation (10) is the difference between the vector s representing the transmission spectrum of the spectrum conversion means and the average of the observed spectrum of each material.

[0026]

(Equation 12) Represents the inner product of

Here, in order to improve the contrast, consider maximizing q in the expression (9) or (10). Maximizing q is determined by S / S from equations (7) and (9).
It is nothing but maximizing N. Here, Fisher Rat defined by the following equation as an index of statistical pattern classification
Think io. For the Fisher Ratio, refer to the document “An O
ptical Set of Discriminate Vectors ”, IEEE Trans.C
omp.C-24, (1975) pp.281-289.

[0028]

(Equation 13) Equation (11) shows that the vectors {x},
A vector d that constitutes an optimal space for classifying {y}
Is an index defined in order to obtain, and each statistic is defined as follows.

[0029]

[Equation 14] Considering the definition of equation (11), Fisher Ratio R (d)
Is to find a vector d that maximizes the inner product with the average difference vector ω while considering the variance of the vectors belonging to the two classes. It is known that a vector satisfying such a condition is derived as follows.

[0030] d = αC ₂ ^-1 Δ α: normalization factor (12) Therefore, the vector d, x, and y respectively vector s, p
By substituting ₁ and p ₂ , an optimum spectrum s for improving the contrast is obtained.

[0031]

(Equation 15) When the expression (13) is substituted into the expression (10), the expected value of the maximum contrast is expressed by the following expression.

[0032] ^{_{q max = s t Δ = α}} (C 2 -1 Δ) t Δ = αΔ t C 2 -1 Δ (14) if constant independently of the wavelength dispersion of the vector p _1, p _2, In other words, if homogeneous, C ₂ becomes a unit matrix,
Equation (14) is as follows.

[0033]

(Equation 16)

From the above analysis, the optimum spectrum s for improving the contrast and S / N can be defined by C ₂ ^-1 Δ or Δ. FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention. Illumination light generation means (spectral light source) 100 for generating illumination light, spectrum conversion means 101 for converting the spectrum of illumination light, and this spectrum conversion means An illumination optical system 140 that guides illumination light whose spectrum has been converted by the means 101 to an object 142, a movable mirror 149 that switches the direction of an optical path of an optical image from the illuminated object 142, and the illuminated object Thing 142
A first imaging optical system 146 for forming an image of the target image, and an object 142 formed by the first imaging optical system 146.
And a spectral spectrum obtaining means 147 for obtaining spectral spectra of images of a plurality of portions of the object 142. Based on the obtained spectral spectra, the S / N of the target portion in the object 142 is high and the target portion is observed at the target portion. Processor 148 as spectrum calculation means for calculating an optimum spectrum for observing a large difference between the measured light intensity value and the light intensity value observed at the non-target region, and an image of the illuminated object 142. And an image input means 145 for inputting an optical image of the object 142 formed by the second imaging optical system 144. As the object 142, the bonding pad portion 10 and the resist portion 1 shown in FIG.
Target 1

The operation of the above configuration will be described below. In order to obtain an optimal spectrum in the learning mode, first, the white light output from the illumination light generating means 100 is directly irradiated onto the object 142 (the liquid crystal filter 208 of FIG. 2 described later is in an open position). The direction of the optical path of the light reflected from the object 142 is changed using the movable mirror 149 and guided to the spectral spectrum acquisition means 147.
The spectrum in the resist unit 11 in 42 is acquired and stored in the memory in the processor 148. This is repeated several times to obtain a plurality of spectra of the resist unit 11 in order to reduce the influence of noise and the like. Similarly, a plurality of spectra from the bonding pad section 10 are acquired, and the
8 in the memory. Next, these stored resist units 1
A set of a plurality of spectra for each of the first and bonding pad portions 10 is defined as {f ₁ (λ)}, {f ₂ (λ)},
The transmission spectrum s of the spectrum conversion means 101 that maximizes q in the above equation (9) or (10) is obtained by the equation (13).

When the optimum spectrum s is obtained, the mode is shifted to the inspection mode, and an image is input based on the optimum spectrum s. That is, the movable mirror 149 is moved out of the optical path, and under the control of the processor 148, the transmission spectrum of the spectrum conversion means 101 is changed to be the same as the optimum spectrum s. Then, the illumination light whose spectrum has been converted by the spectrum conversion means 101 is applied to the object 142. The optical image from the object 142 is formed by the second imaging optical system 144 and input to the processor 148 by the image input unit 145.

The illumination light generating means 100 and the spectrum converting means 101 are configured, for example, as shown in FIG. 2 so that light having an arbitrary spectral distribution can be emitted. In this configuration, light emitted from the white light source 201 is once collimated into parallel light by the lens 202 and then collected by the lens 203. A slit 204 is provided on the focal plane of the lens 203, so that the size of incident light is appropriately adjusted. The white light passing through the slit 204 is collimated into parallel light by a concave mirror 205 and guided to a diffraction grating 206. First-order diffracted light diffracted in a specific direction according to the wavelength in the diffraction grating 206 is imaged by a concave mirror 207. A liquid crystal filter 208 is provided on the image forming surface of the concave mirror 207,
Numeral 8 allows the transmittance of light of each wavelength at the image forming position to be set arbitrarily. The liquid crystal filter 208 is operated by a liquid crystal filter driver 209 controlled by the processor 148.

The light that has passed through the liquid crystal filter 208 is condensed by a lens 210 and guided from a light incident end side connector 211 to a light guide 240 composed of an optical fiber bundle. For example, when irradiating yellow light, the concave mirror 2
When the liquid crystal filter 208 is operated from the liquid crystal filter driver 209 so that light of the blue wavelength cannot be transmitted at the imaging position of 07, green and red lights are mixed at the incident end side connector 211, and as a result, yellow light is emitted. Irradiation is performed through the light guide 240.

By the way, the optimum spectrum data calculated in the learning mode generally has a positive value and a negative value as shown in FIG. However, since the minus operation cannot be realized optically, the processor 14
8, a negative operation is realized by electric signal processing. Therefore, the appropriate spectrum data of FIG.
(B) and FIG. 3 (c), and subtracting the image of the object 142 by the spectrum light of FIG. 3 (c) from the image of the object 142 by the spectrum light of FIG. The operation is to be realized.

The processor 148 is provided with the configuration shown in FIG. CPU40
6 controls the illumination light generation means 100 so as to illuminate the object 142 with the spectrum light of FIG.
02 and temporarily stored in the memory 403-1. Next, the illumination light generating means 100 is controlled so as to illuminate the object 142 with the spectrum light shown in FIG.
02 in the memory 403-2. Memory 403
The image signals stored in -1, 403-2 are sent to a numerical operation circuit (ALU) 404. The numerical operation circuit (AL
U) 404 is a memory 4 based on the image signal of the memory 403-1.
After subtracting the image signal of 03-2, the result is stored in the memory 40.
Send to 5. The image signal stored in the memory 405 is used for a subsequent inspection or the like. Thus, a negative operation can be realized.

As described above, in the first embodiment, the printed circuit board 12 is previously illuminated with white light,
Spectroscopic data of a plurality of materials (bonding pad section 10 and resist section 11) are individually measured, and based on the spectral data, S / S
An optimum spectrum for determining a large N and a large difference from the light intensity of the non-target region is determined. The printed circuit board 12 is illuminated with the illumination light having the optimum spectrum. According to such a method, it is possible to obtain an image with an optimal contrast over the entire area of the printed circuit board 12, and it is possible to prevent erroneous detection or the like in a non-target area without a special algorithm.

Since the illumination light is the same over the entire area of the printed circuit board 12, the image input time can be reduced. Therefore, images of electronic components of the same type can be captured in a short time.

Although the first imaging optical system 146 and the second imaging optical system 144 share a part in this embodiment, they may be completely the same optical system. If a sufficient amount of light can be obtained for the image, a fixed half mirror may be used instead of the movable mirror.

Next, a modification of the first embodiment will be described with reference to FIGS. 5 (a) and 5 (b). In this modified example, the configuration for calculating the optimal spectrum and the configuration for inputting an image according to the first embodiment are configured by separate devices.

As shown in FIG. 5 (a), the optimum spectrum calculating device includes an illumination light generating means 500 and a light guide 50.
1. Illumination device 502, imaging optical system 504, spectrometer 50
5. The processor 506 performs statistical processing for determining an optimal spectrum. Reference numeral 503 denotes an object such as a printed circuit board. The image input device is shown in FIG.
As shown in (b), the illumination light generation means 510, the spectrum conversion means 511, the illumination optical system 512, and the imaging optical system 51
4. An image of the object 503 which is constituted by the imaging device 515 and the processor 516 and is illuminated with the illumination light having the determined optimum spectral distribution is captured.

The operation of FIGS. 5A and 5B is almost the same as that of the first embodiment. That is, the optimum spectrum calculating device measures the spectrum data of each material constituting the object 503, and determines the optimum spectrum from these data based on the above-described principle. However, when calculating the optimum spectrum, the processor 506 has a function for correcting the difference in the wavelength transfer characteristics between the optimum spectrum calculation device and the image input device. In the image input device, the processor 516 controls the spectrum conversion means 511 to output an optimum spectrum and illuminate the object 503. The optical image from the object 503 is formed by the imaging optical system 514 and input to the processor 516 by the imaging device 515.

By doing so, it is not necessary to make the spectrum of the spectrum conversion means 511 of the image input device variable, so that the configuration can be simplified. When the type of the object 503 changes, the optimum spectrum distribution for the object 503 may be determined again by the optimum spectrum calculating device, and the transmission spectrum of the spectrum converting means 511 of the image input device may be changed.

FIG. 6 shows the spectrum conversion means 101 described above.
It is a figure which shows another specific structure of. White light source 620a
Is collimated into parallel light by the lens 621a and guided to the ND filter 622a. After the brightness of the parallel light is appropriately adjusted by the ND filter 622a, only the desired blue component is transmitted by the bandpass color filter 623a. The parallel light transmitted through the bandpass color filter 623a is reflected only by the blue component by the dichroic mirror 625 that reflects only the blue component, and is guided to the lens 626.

The white light emitted from the white light source 620b is collimated into parallel light by the lens 621b, and is guided to the ND filter 622b. After the brightness of the parallel light is appropriately adjusted by the ND filter 622b, only a desired red component is transmitted by the bandpass color filter 623b. The parallel light transmitted through the band-pass color filter 623b is converted into dichroic mirrors 624 and 62.
5 and passes straight to the lens 626.

The white light emitted from the white light source 620c is collimated into parallel light by the lens 621c, and is guided to the ND filter 622c. After the brightness of the parallel light is appropriately adjusted by the ND filter 622c, only the desired green component is transmitted by the bandpass color filter 623c. The parallel light transmitted through the bandpass color filter 623c is reflected by a dichroic mirror 624 that reflects light having a shorter wavelength than red, passes through a dichroic mirror 625, and is guided to the lens 626.

In this way, the parallel light from the light sources 620a, 620b, 620c enters the lens 626 with a predetermined spectrum. The superimposed parallel light is condensed by the lens 626 and guided to the light guide 640 composed of an optical fiber bundle via the incident end side connector 627. Note that the ND filter 622a,
The b and c and the band-pass color filters 623a, 623b and 623c may be detachably arranged, or may be replaced by attaching a filter having different characteristics to the turret and rotating the turret.

FIG. 7 is a diagram showing another configuration of the spectrum conversion means 101. The white light emitted from the white light source 730a is collimated into parallel light by the lens 731a, passes through the band-pass color filter 732a, and passes through the lens 733a.
And is guided to the light guide 734a. The white light emitted from the white light source 730b is collimated into parallel light by the lens 731b, and is output to the band-pass color filter 73.
2b, is condensed by a lens 733b, and guided to a light guide 734b. The white light emitted from the white light source 730c is collimated into parallel light by the lens 731b, passes through the band-pass color filter 732c, and passes through the lens 731b.
The light is condensed by 33c and guided to the light guide 734c. Each of the white light sources 7 is
Light emitted from 30a, 30b and 30c is incident with a predetermined spectrum. In the incident end side connector 735, light having a predetermined spectrum is mixed and guided by a light guide 740 to a lighting device (not shown). Note that the bandpass color filters 732a, 732b, 732c may be removably disposed, or those having different characteristics may be mounted on the turret.
It may be exchangeable by rotating.

Hereinafter, a second embodiment of the present invention will be described.
The second embodiment relates to an optimum spectrum calculating means for observing a difference in light intensity at a plurality of portions having different reflection spectra as small as possible, and an image input apparatus using the same.

As in the first embodiment, it is assumed that the target object is composed of a gold-plated bonding pad section 10 and a translucent resist section 11 on a printed circuit board 12 (FIG. 13). Each of the bonding pad section 10 and the resist section 11 has a defect, and both of these defects must be detected. To perform this in as short a time as possible, the bonding pad portion 10 and the resist portion 11 must be inspected simultaneously. However, the reflectance between the bonding pad portion 10 having a metallic luster and the translucent resist portion 11 is greatly different, and it is usually difficult to observe them simultaneously with both S / N being high.

Therefore, in the second embodiment, based on the principle described below, an optimum spectrum for minimizing the difference in light intensity between a plurality of target portions is calculated, and the spectrum of the optical image is converted based on the calculated spectrum. Thus, an image having a small difference in light intensity between the bonding pad section 10 and the resist section 11 is obtained. According to the same definition as in the first embodiment, the observed spectrum h _i of the material i (i = 1,2) is represented by the following formula.

[0056]

[Equation 17] Here, (S) indicates a predetermined wavelength range. Expressed in discrete data observations spectrum h _i to facilitate analysis (17) is expressed by the following equation.

H _i = s ^t g _i (17) where s and g are vectors, and t represents a transposed matrix. In the second embodiment, the purpose is to minimize the difference between the observation light intensities h ₁ and h ₂ from two types of members made of different materials. Therefore, the problem in this embodiment is expressed by the following equation. Can be.

[0058]

(Equation 18) Objective: ε ² = | h ₁ −h ₂ | ² → min (19) This equation (19) is developed as follows.

[0059]

[Equation 19] However, the Λ ² = ΔΔ ^t. (20), (2)
In equation (1), Δ is a vector.

The problem of finding the vector s that minimizes the expression (21) under the condition (18) can be solved by applying, for example, the Beale method to a quadratic programming problem.

The configuration of the second embodiment is completely the same as that of the first embodiment, so that the illustration is omitted. However, since the spectral distribution of the light source is all positive according to the condition shown in equation (18),
The configuration for the minus operation as shown in FIG. 4 is not required as the configuration of the processor 148.

The operation of the second embodiment will be described below. In FIG. 1, first, white light from the illumination light generation unit 100 is applied to the object 142, and reflected light from the illuminated object 142 is transmitted by the movable mirror 149 through the first imaging optical system 146. The spectrum is guided to the spectral spectrum acquiring means 147, and the spectral spectrum of the resist unit 11 constituting the object 142 is measured and stored in a memory inside the processor 148. This is repeated several times to obtain a plurality of spectra of the resist unit 11. Similarly, a plurality of spectra from the bonding pad section 10 are acquired, and the
8 in the memory. Next, a set of a plurality of spectra of each of the stored resist portion 11 and bonding pad portion 10 is defined as {f ₁ (λ)}, {f ₂ (λ)}, and under the condition of Expression (18), 21) An optimum spectrum s that minimizes ε ^{2 in the} equation is obtained by applying the Beale method.

When the optimum spectrum s is obtained in this manner, the movable mirror 149 is moved to a position deviated from the optical path, and under the control of the processor 148, the transmission spectrum of the spectrum conversion means 101 and the optimum spectrum s are obtained. The spectrum of the illumination light is converted so as to be the same, and the object 142 is irradiated. The optical image from the object 142 is formed by the second imaging optical system 144 and input to the processor 148 by the image input unit 145.

According to the above-described second embodiment, even if the object is made of a member made of a different material, it can be observed with a small difference in the light intensity at a plurality of sites of interest, so that the entire object can be inspected simultaneously. it can. As a result, the inspection time for one object can be significantly reduced.

Hereinafter, a third embodiment of the present invention will be described.
The third embodiment has an appropriate center wavelength and bandwidth (bandwidth).
The present invention relates to an image input device provided with one color filter having a white light source and an illumination light source having a white light source.

The overall configuration of the third embodiment is almost the same as the configuration of the first embodiment shown in FIG. However, the internal configuration of the spectrum conversion means 101 and the internal configuration of the processor 148 are different.

FIG. 8 is a diagram showing the internal configuration of the spectrum conversion means 101 according to the third embodiment of the present invention. The white light output from the light source 850 is collimated by the lens 851, and then converted into a predetermined spectrum light by the bandpass color filter 852. The spectral light that has passed through the bandpass color filter 852 is
The light is condensed on the incident end side connector 854 by the light 53 and guided to the light guide 840. The spectrum light is guided by the light guide 840 to a lighting device (not shown).

In this embodiment, the bandpass color filter 8
Since the object 142 is illuminated by changing the spectrum of the illuminating light using only one 52, the configuration of the processor 148 does not require the configuration for the minus operation as shown in FIG.

The operation of the above configuration will be described below. By irradiating the spectrum light by the bandpass color filter 852 to the object 142 composed of a plurality of members made of different materials, the difference between the light intensity of the target region and the light intensity of the non-target region increases, or The effect of reducing the difference in light intensity at the site of interest is obtained.

Hereinafter, one band pass color filter 852
Means for achieving the above-described object when the method is used will be described. According to the same definition as in the first embodiment, the light intensity observed in the materials 1 and 2 is represented by the following equation.

[0071]

(Equation 20)

Here, the luminance values obtained by irradiating the spectrum light by the bandpass color filter 852 having the center wavelength λ _p and the half width λ _h are represented by h ₁ (λ _p , λ _h ) and h ₁ , respectively.
₂ (λ _p , λ _h ). At this time, the observed intensity ratio γ of the material 2 to the material 1 is defined by the following equation.

[0073]

(Equation 21) As an index for simultaneously evaluating the observed intensity ratio of the material 2 to the material 1 and the absolute strength of the material, that is, S / N, an index C
(Λ _p , λ _h ) is defined by the following equation.

[0074]

(Equation 22)

In order to observe the material 2 with a good contrast to the material 1, the observed intensity ratio γ in the equation (24) is as small as possible 1 and the half-width λ _h and the center wavelength λ at which the absolute intensity of the material 2 increases. Just find _p .

In order to make the difference between the light intensities of the materials 1 and 2 as small as possible, the half-width λ _{h at which} the observed intensity ratio γ in the expression (24) is as close to 1 as possible and the index C in the expression (25) is large. And find the center wavelength λ _p .

Hereinafter, a specific description will be given with reference to the drawings. FIG.
The resist portion 11 shown in FIG. 3 is treated as material 1 and the bonding pad portion 10 is treated as material 2. Bonding pad part 1
10 and 11 show the observation intensity ratio γ and the index C when the reflection spectrum of the resist unit 11 is as shown in FIG. However, Figure 10 represents the change in the characteristic with respect to the center wavelength lambda _p of the observation intensity ratio γ due to a change of the half value width lambda _h bandpass color filter 852, FIG. 11 is change of the half value width lambda _h bandpass color filter 852 It represents the change in the characteristic with respect to the center wavelength lambda _p index C due to. FIG.
2 shows the observation light intensity spectrum of the bonding pad portion 10 due to a change of the half value width lambda _h bandpass color filter 852. In the third embodiment, these figures are comprehensively determined, and a band-pass color filter 85 for obtaining a desired effect is obtained.
2 are estimated.

In order to observe the bonding pad portion 10 with good contrast with respect to the resist portion 11, the central wavelength and the half-value width at which the observation intensity ratio γ is as small as 1 and the absolute intensity of the bonding pad portion 10 is large. What is necessary is just to use the filter which has. In the example shown in FIG.
From FIG. 12 and FIG. 12, it can be estimated that a filter having a center wavelength λ ₄ and a half value width of 40 nm is suitable.

In order to minimize the difference between the light intensity at the resist portion 11 and the light intensity at the bonding pad portion 10 as much as possible, the central wavelength and half width at which the observed intensity ratio γ is as close to 1 as possible and the index C is as large as possible are determined. What is necessary is just to use the filter which has. Specifically, it can be estimated from FIGS. 10 and 11 that a filter having a center wavelength λ ₅ and a half-value width of 60 nm is suitable.

In the third embodiment, the processor 148 as the spectrum calculating means measures the spectrum data of the bonding pad 10 and the resist 11 of the object 142 and, based on the above-described method, determines the light intensity of the target portion and the light intensity. The characteristic of the band-pass color filter 852 that maximizes the difference between the light intensity of the non-attention part and the light intensity of the plurality of attention parts is calculated, and the band-pass color having the calculated center wavelength and half-value width is calculated. The filter 852 is set at the position shown in FIG. 8 to illuminate the object 142 with the light beam from the light source 850 to obtain a desired optical image.

According to the third embodiment, it is possible to provide an optical inspection apparatus which can obtain the same effects as those of the first and second embodiments without having to make the spectrum conversion means complicated. Note that the present invention is not limited to the configuration of the above-described embodiment. For example, in the above-described embodiment, the color of the illumination light from the illumination light source is changed. Is provided with a color conversion element such as a color filter,
The color filters may be replaced based on the calculated appropriate spectral distribution. Alternatively, the input image may be determined on the spot, and if it is not necessary to store the input image in the storage device, the image sensor may be omitted and the image may be directly observed.

Further, an invention having the following configuration is derived from the above-described specific embodiment, and the operation, effect, and corresponding embodiment of each configuration are as follows. (1) In an image input device for inputting an optical image of an object composed of a plurality of different types of parts, illumination light generating means for generating illumination light for illuminating the object, and guiding the illumination light to the object. An illumination optical system, a first imaging optical system that forms an image of the illuminated object, an image of a site of interest of the object formed by the first imaging optical system, A spectral spectrum obtaining unit that obtains each spectral spectrum in an image of the non-attention part adjacent to the part, and the attention part with respect to the non-attention part based on a plurality of spectral spectra obtained by the spectral spectrum obtaining means. Spectrum calculating means for calculating a spectrum for observing with high contrast and for observing the site of interest with high S / N, and the spectrum calculated by the spectrum calculating means. A spectral conversion unit that converts a spectrum of an optical image of the object based on the vector, and a wavelength sensitivity characteristic equivalent to that of the first imaging optical system, and the spectrum conversion unit converts the spectrum of the object. A second imaging optical system for forming an image,
Image input means for inputting an optical image of the object formed by the image forming optical system. (1) ′ Before the illumination light from the illumination light generation means is applied to the object, the spectrum conversion means converts the spectrum of the illumination light based on the optimal spectrum, and the spectrum is converted. The image input device according to the configuration (1), wherein the illumination light is applied to the object. (Function) A spectral spectrum is acquired by a spectral spectrum acquiring means and a non-interesting part adjacent to the part of interest, and based on each spectral spectrum of both parts, the part of interest is observed with high contrast with respect to the non-interesting part. Calculate a spectrum for the target site to be observed at a high S / N. The spectrum of the optical image of the input object is converted based on the spectrum, and the optical image is input by the image input device. For example, before the illumination light from the illumination light generating means is applied to the object, the spectrum conversion means converts the spectrum of the illumination light, and the spectrum-converted illumination light is applied to the object. (Effect) It is possible to provide an image input device that inputs an optical image of a site of interest with high contrast and high S / N. (Corresponding Embodiment) This configuration corresponds to at least the first and third embodiments described above. (2) In an image input device for inputting an optical image of an object including a plurality of different types of parts, illumination light generating means for generating illumination light for illuminating the object, and guiding the illumination light to the object. An illumination optical system, a first imaging optical system that forms an image of the illuminated object, and an image of the plurality of different types of target sites formed by the first imaging optical system. Based on the spectral spectrum acquiring means for acquiring each spectral spectrum, and the plurality of spectral spectra acquired by the spectral spectrum acquiring means, the target sites are observed with low contrast, and the target sites have high S / N ratios. A spectrum calculating means for calculating a spectrum to be observed in the apparatus, and a spectrum of an optical image of the object based on the spectrum calculated by the spectrum calculating means. And a second imaging unit for forming an image of the object, which has the same wavelength sensitivity characteristic as the first imaging optical system and is spectrally converted by the spectrum conversion unit. An image input apparatus comprising: an optical system; and image input means for inputting an optical image of the object formed by the second image forming optical system. (Function) A spectral spectrum is obtained at a target portion of an object by a spectral spectrum obtaining means, and different types of target portions are observed with low contrast and high S / N based on the respective spectral spectra of the plurality of portions. To calculate the spectrum. Then, based on this spectrum, the spectrum of the input optical image of the object is converted, and the optical image is input by the image input device. (Effect) An object input based on a spectrum for observing a high contrast S / N between different types of attention parts and a high S / N of the attention part calculated based on the spectral spectrum of the attention part of the object. Since the spectrum of the optical image is converted, it is possible to obtain an optical image having low contrast between different types of target regions and a high S / N of the target region. (Corresponding Embodiment) This configuration corresponds to at least the second and third embodiments described above. (3) The spectrum calculation means calculates light intensity obtained from each part of the object, calculates the spectrum based on the light intensity, and the light intensity is:

[0083]

(Equation 23) S (λ): transmission spectrum of the spectrum conversion means, e (λ): light source spectrum, t (λ): characteristic spectrum of the optical transmission system, k (λ): sensitivity of the image input means Spectrum, f (λ): reflection spectrum of the object, The image input device according to the configuration (1) or (2), (Action) Calculate the light intensity obtained from each part of the object,
Based on this light intensity, the spectrum in which the light intensity difference between the target portion and the non-target portion is large and the target portion is observed at a high S / N, or the light intensity difference between different types of target portions is small, and the target portion is small. Calculate the spectrum observed at high S / N. (Effect) It is possible to provide an image input device for inputting an optical image of a site of interest with desired contrast and high S / N. (Corresponding Embodiment) This configuration corresponds to at least the first to third embodiments described above. (4) The spectrum converting means is constituted by a band-pass color filter, and the spectrum calculating means is configured to convert a light intensity value indicating a target part and a non-target part with respect to an object constituted by a member different for each part. Calculating a center wavelength and a half-value width of the bandpass color filter based on an index value defined by a ratio of the light intensity values shown and a product of the ratio of the light intensity values and the light intensity value indicating the target portion. The image input device according to the configuration (1), wherein: (Function) The spectrum converting means is constituted by a band-pass color filter, and the spectrum calculating means is configured such that a light intensity value indicating a target part and a light intensity value indicating a non-target part are obtained for an object constituted by different members for each part. , And a center wavelength and a half-value width of the bandpass color filter are calculated based on an index value defined by a ratio of the light intensity value and a product of the light intensity value indicating the target portion. (Effect) Since the spectrum conversion means is constituted by a band-pass color filter, the device configuration is simplified. (Corresponding Embodiment) This configuration corresponds to at least the third embodiment described above. (5) The image input device according to any one of the configurations (1) to (4), wherein the spectrum conversion unit is installed in an optical path from the illumination light generation unit to the object. . (Function) A spectral conversion unit is provided in an optical path from the illumination light generation unit to the object to perform color conversion. (Corresponding Embodiment) This configuration corresponds to at least the first, second, and third embodiments. (6) The image input device according to any one of the constitutions (1) to (4), wherein the spectrum conversion unit is provided in an optical path from the object to the image input unit. (Operation) A spectral conversion unit is provided in an optical path from an object to an image input unit to perform color conversion. (Corresponding Embodiment) This configuration corresponds to at least the first, second, and third embodiments. (7) In a spectrum calculation device that calculates a spectrum suitable for observing an optical image of an object including a plurality of different types of portions, an illumination light generating unit that generates illumination light for illuminating the object, and the illumination light An illumination optical system for guiding the object to the object, an imaging optical system for forming an image of the illuminated object, an image of a target portion of the object formed by the imaging optical system, and A spectral spectrum obtaining unit that obtains each spectral spectrum in an image of the non-target region adjacent to the region, and the target region is higher than the non-target region based on the plurality of spectral spectra obtained by the spectral spectrum obtaining unit. Spectrum calculating means for calculating a spectrum for observing in contrast and for observing the target portion with high S / N. Torque calculation device. (Operation) The spectral spectrum obtaining means obtains each spectral spectrum in the image of the target part and the non-target part of the object, and based on each spectral spectrum, the spectrum calculating means sets the target part with respect to the non-target part. Observed with high contrast and high S / N at the site of interest
Calculate the spectrum to be observed in. (Effect) A spectrum suitable for observation of an object is calculated, and this spectrum is calculated so that a part of interest has a high contrast with respect to a non-part of interest of the object, and the part of interest has a high S / N. It can be used when inputting a perfect image. (Corresponding Embodiment) This configuration corresponds to at least the first and third embodiments described above. (8) In an image input device for inputting an optical image of an object, an illumination light generating means for generating illumination light for illuminating the object, an illumination optical system for guiding the illumination light to the object,
Spectral conversion means for converting the spectrum of the optical image of the object, an imaging optical system for forming an image of the object spectrally converted by the spectrum conversion means, and an image formed by the imaging optical system Image input means for inputting the image of the target object obtained by the processing, wherein the spectrum conversion means calculates the target object calculated from a spectral spectrum image of a target part of the target object and a non-target part adjacent to the target part. The spectrum of the optical image of the object is converted based on the spectrum for observing the target area with high contrast with respect to the non-target area of the object and observing the target area with high S / N. Image input device. (Operation) From the spectral spectra of the target region and the non-target region of the object, the target region is observed with high contrast relative to the non-target region of the target object, and the S / N is higher than the target region.
The spectrum to be observed is calculated in advance, and the spectrum of the optical image of the object is converted based on the spectrum, and the optical image is input by the image input device. (Effect) Since a part for learning a spectrum suitable for obtaining an optical image of a target object well is provided outside the image input device,
The configuration of the image input device does not become complicated. (Corresponding Embodiment) This configuration corresponds to at least the first and third embodiments described above. (9) A spectrum calculation device that calculates a spectrum suitable for observing an optical image of an object composed of a plurality of different types of parts, and a spectrum of the object that is converted based on the calculated spectrum. An image input system comprising an image input device for inputting an optical image of the object, wherein the spectrum calculation device generates illumination light for illuminating the object, and the illumination light is transmitted to the object. An illumination optical system for guiding, an imaging optical system for forming an image of the illuminated object, an image of a target portion of the object formed by the imaging optical system, and a non-adjacent image adjacent to the target portion. Based on the spectral spectrum acquiring means for acquiring each spectral spectrum in the image of the region of interest, and the plurality of spectral spectra acquired by the spectral spectrum acquiring means, for the non-attention region Spectrum calculating means for calculating a spectrum for observing the target area with high contrast and observing the target area with high S / N, wherein the image input device illuminates the object. A second illumination light generating means for generating light, a second illumination optical system for guiding the illumination light to the object, and a spectrum of the object based on the spectrum calculated by the spectrum calculation means. Spectrum converting means for converting, a second image forming optical system for forming an image of the object spectrally converted by the spectrum converting means, and the image formed by the second image forming optical system. An image input system, comprising: image input means for inputting an optical image of an object. (Operation) The spectral spectrum obtaining means of the spectrum calculating apparatus obtains each spectral spectrum in the image of the target part of the object and the image of the non-target part adjacent to the target part, and the spectrum calculating means obtains each of the obtained spectral spectra. Based on the above, a spectrum is calculated so that the target region is observed with high contrast with respect to the non-target region of the object, and the target region is observed with high S / N.
Then, the image input device, by the spectrum conversion means,
Based on the spectrum calculated by the spectrum calculation means, the spectrum of the object is converted and an optical image is input. (Effect) It is possible to provide an image input system for inputting an optical image of a target portion in a short time with high contrast and high S / N. (Corresponding Embodiment) This configuration corresponds to at least the first and third embodiments described above. (10) In a spectrum calculation device that calculates a spectrum suitable for observing an optical image of an object including a plurality of different types of attention parts, an illumination light generating unit that generates illumination light for illuminating the object, and the illumination An illumination optical system for guiding light to the object; and a first image forming an image of the illuminated object.
Imaging spectral system, spectral spectrum acquiring means for acquiring each spectral spectrum in the image of the plurality of different portions of interest formed by the first imaging optical system, and spectral spectrum acquiring means Based on the plurality of spectral spectra obtained, the sites of interest are observed with low contrast, and the sites of interest have high S / S ratios.
A spectrum calculating means for calculating a spectrum to be observed in N. (Effect) A spectrum suitable for observation of an object can be calculated,
This spectrum can be used when inputting an image in which the parts of interest have a low contrast and each of the parts of interest has a high S / N. (Corresponding Embodiment) This configuration corresponds to at least the second and third embodiments described above. (11) In an image input device for inputting an optical image of an object including a plurality of different types of attention parts, illumination light generating means for generating illumination light for illuminating the object, and applying the illumination light to the object. An illumination optical system for guiding, a spectrum converting means for converting a spectrum of an optical image of the object, an image forming optical system for forming an image of the object spectrally converted by the spectrum converting means, Image input means for inputting an optical image of the object formed by an image optical system, wherein the spectrum conversion means is observed at a low contrast between the target parts from the spectral spectra of the plurality of target parts, In addition, the image input apparatus converts the spectrum of the optical image of the object based on the spectrum for observing each of the target portions with high S / N. (Effect) Since a part for learning a spectrum suitable for obtaining a good optical image of the object is provided outside the image input device,
The configuration of the image input device does not become complicated. (Corresponding Embodiment) This configuration corresponds to at least the second and third embodiments described above. (12) a spectrum calculation device that calculates a spectrum suitable for observing an optical image of an object including a plurality of different types of attention sites, and converts the spectrum of the object based on the calculated spectrum to obtain the object. In an image input system comprising an image input device for inputting an optical image of an object, the spectrum calculation device guides the illumination light to the object by illuminating light generating means for generating illumination light for illuminating the object. An illumination optical system, a first imaging optical system that forms an image of the illuminated object, and an image of the plurality of different types of target sites formed by the first imaging optical system. A spectral spectrum acquiring unit for acquiring each spectral spectrum, and a contrast region where the target region is low based on the plurality of spectral spectra acquired by the spectral spectrum acquiring unit. And a spectrum calculating means for calculating a spectrum for observing the target area with a high S / N ratio, and the image input device generates illumination light for illuminating the object. Illumination light generating means, an illumination optical system for guiding the illumination light to the object,
Based on the spectrum calculated by the spectrum calculation means, a spectrum conversion means for converting a spectrum of the optical image of the object, and an image of the object subjected to spectrum conversion by the spectrum conversion means. An image input system comprising: an image forming optical system; and image input means for inputting an optical image of the object formed by the image forming optical system. (Effect) It is possible to provide an image input system in which an attention portion has a low contrast and an optical image in which each attention portion has a high S / N in a short time. (Corresponding Embodiment) This configuration corresponds to at least the second and third embodiments described above. (13) In an image input device for inputting an optical image of an inspection object composed of a plurality of different types of parts, illumination light for generating illumination light for illuminating a learning object having the same structure as the inspection object. Generating means, an illumination optical system for guiding the illumination light to the learning object, a first imaging optical system for imaging the illuminated image of the learning object, and a first imaging optical system A spectral spectrum acquiring unit for acquiring each spectral spectrum in the image of the target region of the learning target object and an image of a non-target region adjacent to the target region, formed by the system, and the spectral spectrum acquiring unit. A spectrum for calculating the spectrum for observing the target region with high contrast with respect to the non-target region based on the plurality of spectral spectra, and for observing the target region with high S / N. And torque calculating means, based on the spectrum calculated by the spectrum calculating means,
A spectrum conversion unit that converts a spectrum of an optical image of the inspection target, and an image of the inspection target that has the same wavelength sensitivity characteristic as the first imaging optical system and is spectrally converted by the spectrum conversion unit. A second imaging optical system for imaging the object, and image input means for inputting an optical image of the inspection object formed by the second imaging optical system. Image input device. (Effect) It is possible to provide an image input device that prepares a spectrum suitable for observation of an inspection target object by a learning operation and uses the spectrum to input an optical image of a target portion with high contrast and high S / N in a short time. (Corresponding Embodiment) This configuration corresponds to at least the first and third embodiments described above.

[0084]

According to the present invention, it is possible to provide an image input apparatus capable of inputting an optical image of a target portion in a short time with high contrast and high S / N.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of first to third embodiments of the present invention.

FIG. 2 is a diagram showing a specific configuration of an illumination light generation unit and a spectrum conversion unit shown in FIG.

FIG. 3 is a diagram for explaining a method of performing a minus operation on electrical spectrum processing including negative values by electrical signal processing.

FIG. 4 is a diagram showing a configuration of a processor for implementing a minus operation.

FIG. 5 is a configuration diagram showing a modification of the first embodiment.

FIG. 6 is a diagram showing another specific configuration of the spectrum converting means shown in FIG.

FIG. 7 is a diagram showing another configuration of the spectrum conversion means shown in FIG. 1;

FIG. 8 is a diagram showing an internal configuration of a spectrum conversion unit according to a third embodiment of the present invention.

FIG. 9 is a diagram illustrating an example of a reflection spectrum of a bonding pad portion and a resist portion.

10 is a diagram showing changes in characteristics with respect to the central wavelength lambda _p of the observation intensity ratio γ due to a change of the half value width lambda _h bandpass color filter.

11 is a diagram showing changes in characteristics with respect to the central wavelength lambda _p index C due to a change of the half value width lambda _h bandpass color filter.

FIG. 12 is a diagram illustrating an observation light intensity spectrum of a bonding pad portion in accordance with a change in a half width λ _h of a bandpass color filter.

FIG. 13 is a diagram showing a gold-plated bonding pad portion and a resist portion on a printed circuit board as objects.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Bonding pad part, 11 ... Resist part, 12 ... Printed circuit board 100 ... Illumination light generation means, 101 ... Spectrum conversion means, 140 ... Illumination optical system, 142 ... Object, 144 ... Second imaging optical system, 145 ... image input means, 146 ... first imaging optical system, 147 ... spectral spectrum acquisition means, 148 ... processor, 149 ... movable mirror

Claims (3)

[Claims] 1. An image input apparatus for inputting an optical image of an object including a plurality of different types of parts, comprising: illumination light generating means for generating illumination light for illuminating the object; An optical system for guiding an image of the illuminated object; a first image forming optical system for forming an image of the illuminated object; and an image of a target portion of the object formed by the first image forming optical system. Spectral spectrum obtaining means for acquiring each spectral spectrum in an image of a non-attention part adjacent to the part of interest; and the attention to the non-attention part based on a plurality of spectral spectra obtained by the spectral spectrum obtaining means. A spectrum calculating means for calculating a spectrum for observing the part with high contrast and observing the part of interest with high S / N; A spectrum converting means for converting a spectrum of an optical image of the object based on the obtained spectrum, and a wavelength sensitivity characteristic equivalent to that of the first imaging optical system, wherein the spectrum is converted by the spectrum converting means. A second imaging optical system for forming an image of the object; and image input means for inputting an optical image of the object formed by the second imaging optical system. An image input device characterized by the above-mentioned. 2. An image input apparatus for inputting an optical image of an object including a plurality of different types of parts, comprising: illumination light generating means for generating illumination light for illuminating the object; An optical system for guiding an image of the illuminated object; and a plurality of different types of attention sites formed by the first image forming optical system. Spectral spectrum acquiring means for acquiring each spectral spectrum in the image; and based on the plurality of spectral spectra acquired by the spectral spectrum acquiring means, the sites of interest are observed with low contrast, and each of the sites of interest has a high S
/ N: a spectrum calculating means for calculating a spectrum to be observed at / N; a spectrum converting means for converting a spectrum of an optical image of the object based on the spectrum calculated by the spectrum calculating means; A second imaging optical system having the same wavelength sensitivity characteristic as that of the imaging optical system for forming an image of the object whose spectrum has been converted by the spectrum conversion means; and a second imaging optical system. Image input means for inputting an optical image of the object formed by the image input device. 3. The spectrum calculation means calculates light intensity obtained from each part of the object, calculates the spectrum based on the light intensity, and the light intensity is expressed by the following equation. 1) S (λ): transmission spectrum of the spectrum conversion means, e (λ): light source spectrum, t (λ): characteristic spectrum of the optical transmission system, k (λ): sensitivity of the image input means 3. The image input device according to claim 1, wherein f (λ) is a reflection spectrum of the object.