JP2001215200A - Optical measuring apparatus and surface state inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical measuring apparatus such as a surface state inspection apparatus capable of obtaining the data of a detection position high in reliability at a high speed. SOLUTION: The optical measuring apparatus is equipped with at least two light receiving elements arranged in mutually different directions to detect the reflected light from the detection light spot on the surface of an object to be measured. A judge processing circuit is provided so that, when two detection position data obtained by these light receiving elements coincide with each other in an allowable error range, either one of two detection position data is selected as the primary effective detection position data at the projection point of the detection light spot and, when the primary effective detection position data is not selected, the detection position data approximate within the range set with respect to the detection position data stored as the effective detection position data at the projection point of a just-before measuring place is selected as the secondary effective detection position data at the projection point of the detection light spot.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical measuring device using a light spot for detection, such as a surface condition inspecting device for detecting a surface shape or a coordinate position of a measured object.

[0002]

2. Description of the Related Art At present, for example, when measuring a coordinate position or an uneven shape on the surface of an object to be measured by an optical method, for example, a light spot for detection is formed on the surface of the object to be measured, and this light spot for detection is formed. By imaging the reflected light on the light receiving element, detecting the amount of displacement of the reflected light image from the reference position on the light receiving surface of the light receiving element, and converting this to the amount of displacement on the surface of the measured object, 2. Description of the Related Art An optical triangulation method for measuring a coordinate position and an uneven shape on a surface of an object to be measured is used.

In such an optical triangulation method, for example, a digital light position detecting element such as a CCD, a MOS, or a PCD in which minute photodiodes are closely arranged, or a light is diverted from an incident light point on a light receiving surface. An analog optical position detecting element such as a PSD utilizing the property of a photocurrent is used. In particular, the PSD is capable of obtaining a continuous electric signal, and is excellent in position detection resolution and responsiveness. Is preferably used because it has These light position detection elements are configured to detect detection position information according to the amount of displacement of the light barycentric position of the incident light on the light receiving surface or the highest light amount position from the reference position, and the detected position information is calculated. By the processing by the means, for example, a coordinate position and a displacement amount on the surface of the measured object can be obtained.

In an optical measuring apparatus for measuring the surface state and detecting the position of an object to be measured by such an optical method, the reflection state on the surface of the object to be measured is, in principle, an ideal state such as specular reflection. In the case of reflection, the position can be accurately detected by the optical position detecting element.However, when the surface of the object to be measured is a rough surface and the reflection state is not ideal reflection, that is, for detection, When the reflected light from the projection point in the light spot is scattered and spreads,
There has been a problem that position detection by the light position detection element cannot be performed accurately.

[0005] Such a problem is caused by the fact that the reflected light is scattered and spread due to the reflection state on the surface of the object to be measured, thereby causing an error in determining the position of the center of gravity of the light on the light receiving surface of the light position detecting element. Was thought to be. For example, Japanese Unexamined Patent Publication No. Hei 6-109421 discloses that reflected light of laser light projected on the surface of a measured object is reflected by a plurality of PSDs.
A displacement measuring device is disclosed in which the accuracy of position displacement information is improved by averaging the data obtained by each PSD by receiving light by the above method.
No. 426 discloses that the reflected light of a laser beam projected on the surface of a measured object is received by a PSD via a lens array to reduce an image of the reflected light formed on the light receiving surface, thereby obtaining positional displacement information. A displacement measuring device in which the accuracy of the displacement measurement is improved is disclosed. In such a displacement measuring device, any, a projection point projected on the surface of the measured object,
It is assumed that the center of gravity of the light reflected by the surface of the object to be measured matches the center of gravity.

[0006]

However, in practice, the surface of the object to be measured is often an undulating uneven surface larger than the beam diameter of the projection light, and the reflection state on the surface is complicated. is there. For example, when the surface of the object to be measured is a glossy surface having irregularities, as shown in FIG. Is reflected on the reverse slope of the other convex portion 52 located apart from the convex portion 51 in the surface direction, and the light is reflected on the light receiving surface 54 of the light receiving element via the light receiving lens 53.
And thus the light receiving surface 54 of the light receiving element
Is displaced from the light center of gravity G on the light receiving surface 54 when the projection point S and the reflection center of gravity R match. In FIG. 7A, L is the light amount distribution on the light receiving surface 54 of the light receiving element, and FIG.
8 is a reflected light distribution D on the surface of the measured object, which is shown in association with FIG. The same applies to the case where the surface F of the object to be measured is a rough surface having irregularities as shown in FIG. 8A or the case of a translucent multilayer printed circuit board P as shown in FIG. Thus, the optical center of gravity G 'on the light receiving surface 54 of the light receiving element is displaced from the optical center of gravity G on the light receiving surface 54 when the projection point S and the reflection center of gravity R match. FIG. 8B is a reflection light distribution D on the surface of the measured object shown in association with FIG. 8A, and 56 in FIG. 9 is a translucent insulating layer, and 57 is a wiring portion made of, for example, copper foil. is there.

As described above, in actuality, on the surface of the measured object, the projection point S in the detection light spot projected on the measured object and the reflection center of gravity R in the reflected light of the detection light spot are determined. Are extremely many places, and as a result, the light center of gravity G ′ on the light receiving surface 54 of the light receiving element
Is displaced from the optical center of gravity position G relating to the projection point S, and eventually the position displacement information detected by the light receiving element is
It has been found that the reliability of the coincidence of the position, which is the position displacement information at the true target measurement point, is low.

SUMMARY OF THE INVENTION The present invention has been made based on the above-described circumstances, and an object of the present invention is to project a projection point on a detection light spot formed on an object to be measured and a reflection point of the detection light spot. By considering the degree of inconsistency with the reflection center of gravity, the degree of reliability of the detected position information can be confirmed, and therefore, a surface state inspection device that can obtain highly reliable detected position information at high speed, etc. To provide an optical measuring device.

[0009]

An optical measuring device according to the present invention comprises at least two light receiving elements arranged in different directions from each other for detecting light reflected from a light spot for detection on the surface of an object to be measured. When two pieces of detection position information obtained by these light receiving elements match within the set allowable error range, one of the two pieces of detection position information is determined at the projection point of the detection light spot. It is characterized by having a judgment processing circuit for selecting as primary effective detection position information.

In the above optical measuring device, when the primary effective detection position information is not selected, the judgment processing circuit stores the effective detection position information stored as the effective detection position information at the projection point of the immediately preceding measurement point. On the other hand, it is possible to adopt a configuration in which detection position information that approximates within the set range is selected as secondary effective detection position information at the projection point of the detection light spot.

When the secondary effective detection position information is not selected, the judgment processing circuit converts the stored detection position information stored as the effective detection position information at the immediately preceding projection point into the detection light information. It is preferable that the information is selected as the tertiary effective detection position information at the spot projection point.

A surface condition inspection apparatus according to the present invention comprises: a beam projector for forming a surface state detection light spot on a surface of an object to be measured; scanning means for scanning the surface state detection light spot by the beam projector; The reflected light from the surface state detection light spot is detected, at least two light position detection elements arranged in different directions from each other, and position displacement information obtained by these light position detection elements are arithmetically processed,
In a surface state inspection apparatus comprising: an arithmetic processing unit that outputs effective position displacement information at a projection point of a surface state detection light spot, the arithmetic processing unit includes the above-described determination processing circuit.

In this surface condition inspection apparatus, the light position detecting element is preferably a linear position detecting element for detecting a linear displacement.

[0014]

According to the optical measuring apparatus having the above-described configuration, when two pieces of position information detected by at least two light receiving elements coincide with each other within the set allowable error range by the determination processing circuit, any one of the two pieces of information is used. One of the detection position information is
Since it is selected as the primary effective detection position information at the projection point of the detection light spot, regardless of the surface condition of the object to be measured, the error caused by the disturbance of the reflection state will be as small as less than a certain level. Since the identity of the projection point in the light spot and the reflection center of gravity in the reflected light of the detection light spot is guaranteed within a certain range, the reliability as the detection position information at the target measurement point is sufficient. It will be expensive.

If the primary effective detection position information is not selected, the judgment processing circuit sets a predetermined range for the stored detection position information stored as the effective detection position information at the immediately preceding projection point at the projection point. The detection position information that is approximated within is selected as the secondary effective detection position information at the projection point of the detection light spot, so that the secondary effective detection position information becomes the projection point and the detection light spot at the detection light spot. Since the coincidence of the reflected light with the reflection center of gravity is guaranteed within a certain range by the continuity of the surface of the object to be measured, the reliability of the detection position information at the target measurement point is considerably high. It will be.

Further, when the secondary effective detection position information is not selected, the stored detection position information at the projection point of the immediately preceding measurement point is selected as the tertiary effective detection position information at the projection point of the detection light spot by the judgment processing circuit. As a result, tentative detection position information at a target measurement point can be obtained. As a result, it is possible to continuously perform the measurement process at the measurement location on the scanning line on the surface of the measured object. By storing that the detected position information is the tertiary effective detected position information, at the stage of finally confirming the shape of the surface of the object to be measured, the validity of the measurement points before and after the measurement point is determined. From the position detection information, the reliability of the tertiary effective detection position information can be reconfirmed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical measuring apparatus according to the present invention projects, for example, a detection light spot and detects a surface shape of a measurement object, a coordinate position on the surface of the measurement object, by using the reflected light. Alternatively, it is useful to ensure the reliability of the position accuracy when performing various measurements such as detection of the amount of position displacement, but the surface condition inspection device of the measured object will be specifically described below.

FIG. 1 is an explanatory side view showing a schematic configuration of an example of an optical system constituting the surface condition inspection apparatus, and FIG. 2 shows an operation state of the optical system of the surface state inspection apparatus shown in FIG. FIG. 3 is an explanatory perspective view, and FIG. 3 is an explanatory view showing an operation state of one system of the optical system of the surface state inspection apparatus shown in FIG. The optical system in the surface condition inspection apparatus includes a beam projector 1 that forms a minute surface condition detection light spot (hereinafter, simply referred to as “light spot”) having a diameter of 30 μm or less on the surface of the measurement object 15.
0, a deflector 11 that linearly deflects and scans the light spot of the beam projector 10 on the object 15 to be measured, and a projection device that projects the projection light from the beam projector 10 in parallel with the scanning direction. First condensing optics for converging light reflected from an optical lens 12 and a light spot and forming an image on a light receiving surface of an optical position detecting element irrespective of a position on a scanning line 15 a on a surface of a measurement object 15. A system 22 and a second condensing optical system 23 are provided, and are also used in other optical measurement devices. In FIG. 1, reference numeral 16 denotes a measurement object mounting table.

As shown in FIG. 3, the first condensing optical system 22 includes a first light receiving lens 25 formed of, for example, a convex lens,
For example, the light receiving section 22 including the second light receiving lens 26 and the third light receiving lens 27 formed of a cylindrical lens
A and the first light position detecting element 20, and the second light collecting optical system 23 has the same configuration as that of the first light collecting optical system 22, and the light receiving section 23A and the second light position It is constituted by a detection element 21.

As the deflector 11, for example, a polygon mirror, a galvanometer, an A / O element or the like can be used. The deflector 11 is provided with a scanning point detector 13 for detecting the deflection angle of the projection light. For example, when a polygon mirror is used as the deflector 11, an encoder is used as the scanning point detector 13 be able to.

A first light position detecting element 20 for detecting the reflected light of the light spot on the measured object 15 through the light receiving portion 22A constituting the first condensing optical system 22 is provided. The second light receiving lens 26 and the third light receiving lens 27 in the condensing optical system 22 allow one direction of the surface of the object 15 to be measured regardless of the position of the surface of the object 15 on the scanning line 15a in the scanning direction. Is detected only. In this optical system, the direction in which the displacement of the measurement object 15 is detected by the optical position detection element 20 is a direction perpendicular to the surface of the measurement object 15 (Z direction). Further, a second light position detecting element 21 for detecting the reflected light of the light spot on the measured object 15 through the light receiving portion 23A constituting the second condensing optical system 23 is arranged, and the surface of the measured object 15 is arranged. Is configured to detect only the displacement in one direction (Z direction). The first light position detecting element 20 and the second light position detecting element 21 are arranged at positions facing the light spot from different directions, in the example shown, on different sides with respect to the projected light.

Each of the first light position detecting element 20 and the second light position detecting element 21 can be constituted by a linear position detecting element for detecting a linear displacement.
In this surface condition inspection apparatus, for example, a one-dimensional PSD having a linear light receiving surface 20a as shown in FIG. 4 is used. For example, a displacement of 5 mm is measured with an error (resolution) of 0.1% or less. You can do it. Here, the width d of the light receiving surface 20a is, for example, 1 mm.

The line-shaped light receiving surface 20a is formed as shown in FIG.
As shown by an arrow in FIG. 1, the surface is arranged so as to extend in a direction perpendicular to the scanning direction of the projection light.
Is detected. Here, the reference plane can be freely set, but in practice, it is convenient to set it on the surface of the measured object 15. For example, the DUT 1
If the component 5 has a component disposed on its surface or has a coating applied thereto, the component placement surface or the coating application surface is set as the reference surface.

The surface condition inspection apparatus is provided with arithmetic processing means for arithmetically processing the detected position displacement information obtained by the light position detecting elements 20 and 21 and outputting the position displacement information at the projection point of the light spot. ing.

FIG. 5 is an explanatory diagram showing a specific example of the circuit configuration of the arithmetic processing means. When the reflected light of the light spot formed on the surface of the measured object 15 is incident on the light receiving surface of the first light position detecting element 20, the light reaches the output terminals at both ends from the position of the center of gravity of the reflected light on this light receiving surface. The detected position displacement information outputs I _a1 and I _a2 corresponding to the distance are detected, and the addition circuit 30
Addition processing outputted by the A and the subtraction circuit 31A V _{a +} and subtraction output V _a- is obtained, setting the output of this adding process output V _{a +} size is defined by the upper output value V _X and the lower output value V _N The determination as to whether or not it is within the range is made by the addition processing output determination unit 32A. Here, the magnitude of the addition processing output Va ₊ represents the magnitude of the amount of light reflected by the surface of the measured object 15. The set output range of the addition processing output is a range in which the arithmetic processing means can perform processing.

[0026] When it is confirmed that the addition processing outputted V _{a +} is within the set output range, the divider 33A divides processing base position displacement information output Z _a 'obtained by by,
Correction for errors such as the observation direction and sensitivity of the reflected light of the light spot is performed by the correction unit 34A on the basic position displacement information output Z _a ′, so that the position displacement information by the first light position detecting element 20 is obtained. output Z _a is obtained.

Similar processing is performed for the detected position displacement information outputs I _b1 and I _b2 by the second light position detecting element 21. That is, the addition circuit 30B and the subtraction circuit 3
Adding process output V _{b +} and is the subtraction output V _b-by 1B, after the addition process output V _{b +} a determination process in the addition processing output determination unit 32B is made, basic positional displacement information output by the division circuit 33B Z _b ' Is obtained, and the basic position displacement information output Z _b ′ is corrected by the correction unit 34B.
Positional displacement information output Z _b by the optical position detecting element 21 can be obtained.

The arithmetic processing means of the surface condition inspection apparatus calculates the position displacement information output Z _a by the first light position detecting element 20 and the position displacement information output Z _b by the second light position detecting element 21. From the viewpoint of the coincidence between the two, the primary determination unit 40 that determines the primary effective position displacement information output at the projection point of the light spot, and the secondary determination at the projection point of the light spot from the viewpoint of the continuity of the surface of the measured object 15 A determination processing circuit including a secondary determination unit 41 that determines the output of the effective position displacement information is provided.

In the judgment processing circuit, first, the position displacement information output Z by the first optical position detecting element 20 is output.
_a is the absolute value | Z _a −Z _n−1 | of the difference between a and the stored position displacement information output Zn _-1 selected as the effective position displacement information output of the projection point in the light spot at the immediately preceding measurement point. positional displacement information output [Delta] Z _a, and, second and positional displacement information output Z _b by the optical position detecting element 21, the absolute value of the difference between the stored positional displacement information output _{Z n-1 | Z b -Z} n-1
| Differential position displacement information output [Delta] Z _b is a is calculated. The first is input to the position displacement information output Z _a and both primary determination unit 40 of the positional displacement information output Z _b by the second light position detecting element 21 by the light position detecting element 20, the light position detecting element positional displacement information output Z _a by 20, 21, Z
The determination processing of _b is performed.

[0030] Specifically, in the primary determination unit 40, the both the first position displacement information output by the PSDs 20 Z _a positional displacement information output Z _b by the second light position detecting element 20 It is determined whether or not they match within the set allowable error range. Here, the allowable error range is
For example, it is set based on the required measurement accuracy. For example, when the required measurement accuracy is ± 20 μm, the maximum value of the allowable error is set to 10 μm.

[0031] Then, it was confirmed that both the first positional displacement information output by the light position detecting element 20 Z _a positional displacement information output Z _b by the second light position detecting element 21 matches within an allowable error range when the can, one of the positional displacement information output of the first positional displacement information output by the light position detecting element 20 Z _a and positional displacement information output Z _b by the second light position detecting element 21, the object to be measured It is selected as the primary effective position displacement information output _Zn1 of the projection point in the 15 light spots.

On the other hand, if the primary determination unit 40 does not select the primary effective position displacement information output Z _n1 ,
Differential position when both the position displacement information output Z _b by the position displacement information output Z _a and a second light position detecting element 21 by the light position detecting element 20 does not coincide within an acceptable error range, which has been calculated in advance of magnitude of the displacement information output [Delta] Z _a and differential position displacement information output [Delta] Z _b are compared by the primary determination unit 40, the secondary determination unit 41 differential position displacement information output is a minimum difference position displacement information output [Delta] Z _x smaller Is entered.

Then, the secondary judgment section 41 judges whether or not the minimum difference position displacement information output ΔZ _x is within the set difference output range (hereinafter, referred to as “set difference output range”) H. When it is confirmed that the minimum difference position displacement information output ΔZ _x is within the set difference output range H, the position displacement information output by the optical position detection element according to the minimum difference position displacement information output ΔZ _x is performed. Z _x is selected as the secondary effective position displacement information output _Zn 2 of the projection point on the light spot of the measured object 15. Here, the allowable difference output range H is, for example, 2 to 10 times, preferably 3 to 7 times the allowable error range in the primary determination unit 40. For example, the scanning resolution by the projection light on the scanning line 15a is 20 μm.
In the case of, the maximum value of the amount of displacement when converted to the amount of displacement of the measured object 15 is set to 50 μm, whereby the measurement is performed at the measurement point on the convex portion having the slope with an inclination angle of up to 68 °. be able to.

The secondary effective position displacement information output _Zn 2 selected by the secondary judgment section 41 is 100% reliable for the effective position displacement information output _{Zn 1} selected by the primary judgment section 40.
Is assumed to have, for example, 80% reliability.

Further, in the secondary judgment section 41, when the secondary effective position displacement information output Z _n2 is not selected, that is, it is confirmed that the minimum difference position displacement information output ΔZ _x deviates from the allowable difference output range H. In this case, the stored position displacement information output Z stored as the effective position displacement information output of the projection point in the light spot at the immediately preceding measurement point.
_n-1 is selected as the tertiary effective position displacement information output Z _n3 of the projection point in the light spot of the measured object 15.

In addition to the above-described position displacement information output determination operation, the position of the light spot formed on the surface of the measured object 15 is detected by the scanning point detector 13 and the counter 42 determines the position of the light spot. On the other hand, a number is assigned and encoded. Then, any one of the effective position displacement information outputs selected by the primary judgment unit 40 or the secondary judgment unit 41 is stored in the memory in a state where it is associated with the encoded light spot position information. Alternatively, it is recorded in the control unit, and is positioned as the stored position displacement information output Zn _-1 when the determination process of the detected position displacement information output by the optical position detecting element at the immediately following measurement point is performed.

The projection light from the beam projector 10 is scanned by the deflector 11 and the same processing is repeated for each of the detected position displacement information output by the light position detecting elements 20 and 21 at the successive measuring points. By doing so, the amount of positional displacement of the surface of the measured object 15 on the scanning line 15a, for example, in the height direction is detected. Here, the separation distance between the measurement points on the scanning line 15a originally differs depending on the measurement purpose, but is, for example, 10 to 100 μm. Thereby, the reliability of the determination processing in the secondary determination unit 41 that selects the secondary effective position displacement information from the viewpoint of the continuity of the surface of the measured object can be increased. The scanning interval in the plane direction of the measured object 15 (X direction in FIG. 2) is, for example, 10 to 100 μm.

The above-described arithmetic processing means is used when a detected position displacement output that can be processed is not obtained, that is, when it is confirmed that the magnitudes of the addition processing outputs V _{a +} and V _{b +} deviate from the set output range. Is abnormal, the output of the projection light from the beam projector 10 is adjusted, and the output of the detected position displacement information is adjusted by the optical position detecting element by the amplifier, and the measurement at the same measurement point is again determined by the arithmetic processing means. Processing is performed. Even if the output of the projection light from the beam projector 10 is adjusted, and the output of the detected position displacement information by the optical position detecting element is adjusted by the amplifier, the detected position displacement information output that can be processed by all the optical position detecting elements. Is not obtained, the storage position displacement information output Zn _{-1 at} the immediately preceding measurement point is adopted.

[0039] As described above, in the primary determination unit 40 in the determination processing circuit, a first position displacement information output Z _a and the second by the optical position detecting element 20 PSDs 21
When both of the positional displacement information output Z _b by the match within the tolerance range set, by selecting either one of the positional displacement information output as a primary effective positional displacement information output in the projection point of the beam spot, the Irrespective of the surface condition of the measuring object, the error caused by the disturbance of the reflection state is surely small below a certain value. As a result, the identity of the projection point in the light spot and the reflection center of gravity in the reflected light of the light spot is constant. It will be guaranteed within the range,
The primary effective position displacement information output Z _n1 selected by the primary determination unit 40 has sufficiently high reliability as the detected position information at the target measurement location. Therefore, according to the optical measuring device having such a determination processing circuit, highly reliable detected position displacement information can be obtained.

If the primary effective detected position information is not selected, the secondary position judging section 41 stores the stored position displacement information output Z _n-1 stored as the effective position displacement information output at the projection point at the immediately preceding measurement point. _Is selected as the secondary effective position displacement information output _{Zn2 at} the projection point of the light spot by approximating one of the position displacement information outputs within the set difference output range H, thereby reflecting the projection point and the light spot at the light spot. Since the coincidence of the light with the reflection center of gravity is guaranteed within a certain range by the continuity of the surface of the measured object 15, the secondary effective position displacement information output Z selected by the secondary determination unit 41. _{When n2} is used, the reliability of the detected position information at the target measurement point is considerably high. The reason for this is that since the surface of the measured object 15 is continuous within a range of a certain displacement width, each of the position displacement information at adjacent measurement points should be approximated to each other within a certain range. is there. Therefore, according to the optical measuring device having such a determination processing circuit, it is possible to obtain detection position displacement information with considerably high reliability.

Further, when the secondary effective detection position information is not selected, the position displacement information output by the optical position detection element includes a large error in the measurement.
In this case, the determination processing circuit selects the storage position displacement information output Zn _-1 at the projection point at the immediately preceding measurement point as the tertiary effective position displacement information output _{Zn3 at} the projection point of the light spot. A temporary displacement information output at the measurement point is obtained. As a result, it is possible to continuously perform the measurement process at the measurement location on the scanning line on the surface of the measured object. By storing that the detected position information is the tertiary effective detected position information, at the stage of finally confirming the shape of the surface of the object to be measured, the validity of the measurement points before and after the measurement point is determined. From the position detection information, the reliability of the tertiary effective detection position information can be reconfirmed.

As the light position detecting elements 20 and 21,
By using the linear position detecting element that detects a linear displacement, it is easy to transform the detected position displacement information obtained as an electric signal into a state corresponding to the purpose, and instantaneously, the detected position Since the measurement and the determination processing of the output of the position displacement information can be performed, the response time is, for example, 1
High speed of less than μS and high resolution of, for example, 0.1 μm or less can be realized.

Hereinafter, an experimental example using the surface condition inspection apparatus of the illustrated example will be described. The coordinate position in the height direction with respect to the reference plane is known for all points on the surface,
Using a printed circuit board (surface condition: rough surface with irregularities, reflectance 10%) on which the solder paste is printed on the surface, the height direction (Z direction) of the surface of the sample is measured. The coordinate position was measured. Here, the size of the light spot formed on the surface of the sample to be measured is 10 μm.
m.

<Experimental Example 1> When measurement was performed at a measurement point where the coordinate position in the height direction from the reference plane on the surface of the sample to be measured was 200 μm, the position by the first optical position detecting element (20) was measured. The displacement information output (Z _a ) and the second
Output of position displacement information (Z
_b ) are coincident with each other within an allowable error range of ± 10 mV, and the primary determination unit (40) outputs the position displacement information output (Z _a ) by the first optical position detecting element (20) to the effective position displacement information. Selected as output (Z _n1 ). The coordinate position in the height direction from the reference plane on the surface of the sample to be measured, obtained from the effective position displacement information output (Z _n1 ), is 198.
μm, and the error was 1% or less.

<Experimental Example 2> The position of the light spot was scanned from the measuring point in Experimental Example 1, and measurement was performed at a measuring point where the coordinate position in the height direction from the reference plane was 158 μm. The position displacement information output (Z _a ) by the light position detecting element (20) and the second light position detecting element (2
The position displacement information output (Z _b ) according to 1) is ± 1
Although the values did not match within the allowable error range of 0 mV, the differential position displacement information output (Δ
The difference position displacement information output (ΔZ _a ) of the first optical position detection element (20) smaller than Z _b ) is within the set difference output range H of ± 50 mV, and the first judgment is made by the secondary judgment section (41). The position displacement information output (Z _a ) by the optical position detecting element (20) is selected as the secondary effective position displacement information output (Z _n2 ). Obtained from the secondary effective position displacement information output (Z _n2), the coordinate position in the height direction from the reference plane at the surface of the object to be measured the sample is 162Myuemu, the error was 2.5%.

<Experimental Example 3> Further, the position of the light spot was scanned from the measuring point in Experimental Example 2, and measurement was performed at a measuring point where the coordinate position in the height direction from the reference plane was 94 μm. in the positional displacement information output by the optical position detecting element (20) and (Z _a), the second positional displacement information output by the optical position detecting element (21) and (Z _b), but within the tolerance range of ± 10 mV from each other Do not match and also the first
The smaller minimum difference position displacement information of the differential position displacement information output according to the optical position detecting element (20) (ΔZ _a) the difference positional displacement information output of the second optical position detecting element (21) (ΔZ _b) of Since the output (ΔZ _x ) was not within the set difference output range (H) of ± 50 mV, the secondary judgment section (41) outputs the storage position displacement information output (Z _n-1 ) at the immediately preceding measurement point to the tertiary effective position information. ( _Zn3 ). The coordinate position in the height direction from the reference plane on the surface of the sample to be measured, determined from the tertiary effective position information ( _Zn3 ), was 32 μm, and the error was 66%.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.
For example, in the surface condition inspection apparatus of the illustrated example, the number of light receiving units including the condensing optical system and the light position detecting element and the observation direction of the reflected light of the light spot are not particularly limited. FIG. 6 is a side view showing a configuration example of an optical system having three systems of light collecting optical systems. The three systems of light collecting optical systems are arranged on the same side with respect to the projection light. The determination processing of the detected position displacement information output by each of the light position detecting elements 45a to 47a constituting each condensing optical system is performed by combining two detected position displacement information selected from the three detected position displacement information outputs. The above-described determination processing is sequentially performed for each of them. At this time, for example, in the primary determination unit, if only two pieces of position displacement information match within the set permissible error range and one piece of position displacement information deviates from the permissible error range, this one position No displacement information is employed.

The object to be measured by the surface condition inspection apparatus is the height direction (Z in FIG. 2) on the surface of the object to be measured.
Direction), it is also possible to use the amount of positional displacement of the measured object in the plane direction. When detecting the amount of displacement of the measured object in the plane direction (X direction or Y direction in FIG. 2), the linear light receiving surface of the optical position detecting element is arranged in a state extending in the plane direction (X direction or Y direction). do it.

The scanning of the projection light may be performed by moving the mounting table of the object to be measured, instead of using the deflector and the light projection lens. In this case, the detection of the scanning point is performed, for example, by scanning. This can be performed by using a unit with a point output, or by measuring a signal from a drive voltage of a drive mechanism for moving the object mounting table.

Further, it is not necessary to perform the determination processing of the detected position displacement information by the light position detecting element for each measurement point.

As described above, the optical measuring device of the present invention
For example, even in the measurement of the surface state of an object to be measured in which the reflection state on the surface is a reflection that is not ideal and the reflectance is 0.1% or less, the effective detection position information obtained is not a true purpose. It has a high degree of reliability with regard to the position information at the measurement location to be measured, so when, for example, the purpose is to measure the shape of the solder paste printed on a printed circuit board, for example, Reliability will be evaluated.

[0052]

According to the optical measuring apparatus of the present invention, the detection light spot is used for detecting the detected position information in which at least two pieces of the detected position information of the at least two light receiving elements coincide within the set allowable error range by the determination processing circuit. Is selected as the primary effective detection position information at the projection point, the error caused by the disturbance of the reflection state is surely small below a certain level regardless of the surface state of the measured object. As a result, the projection point at the detection light spot And the center of gravity of the reflected light of the detection light spot are guaranteed within a certain range, so that the detection position information having sufficiently high reliability as the detection position information at the target measurement point is obtained. Can be detected with high accuracy.

If the primary effective detection position information is not selected, the judgment processing circuit sets the range of the stored detection position information stored as the effective detection position information at the immediately preceding projection point at the projection point. The detection position information that is approximated within is selected as the secondary effective detection position information at the projection point of the detection light spot, so that the projection point in the detection light spot and the reflection centroid point in the reflected light of the detection light spot are Is guaranteed within a certain range by the continuity of the surface of the object to be measured, so that the detection position information having a considerably high reliability as the detection position information at the target measuring point can be obtained with high accuracy. Can be detected.

If the secondary effective detection position information is not selected, the judgment processing circuit selects the stored detection position information at the immediately preceding projection point as the tertiary effective detection position information at the projection point of the detection light spot. As a result, tentative detection position information at a target measurement point can be obtained. As a result, it is possible to continuously perform the measurement process at the measurement location on the scanning line on the surface of the measured object. By storing that the detected position information is the tertiary effective detected position information, at the stage of finally confirming the shape of the surface of the object to be measured, the validity of the measurement points before and after the measurement point is determined. From the position detection information, the reliability of the tertiary effective detection position information can be reconfirmed.

[Brief description of the drawings]

FIG. 1 is an explanatory side view showing a schematic configuration of an example of an optical system constituting a surface state inspection apparatus.

FIG. 2 is an explanatory perspective view showing an operation state of an optical system of the surface condition inspection apparatus shown in FIG.

FIG. 3 is an explanatory diagram showing an operation state of one system of the optical system of the surface state inspection apparatus shown in FIG. 1;

FIG. 4 is a perspective view showing an example of an appearance structure of a one-dimensional PSD.

FIG. 5 is an explanatory diagram showing a specific example of a circuit configuration of an arithmetic processing unit for outputting detected position displacement information by an optical position detecting element.

FIG. 6 is a side view showing a configuration example of an optical system having three condensing optical systems.

FIG. 7A is an explanatory side view showing an example of a reflection state on the surface of the measured object, and FIG. 7B is a reflected light distribution shown in association with FIG.

FIG. 8A is an explanatory side view showing another example of the reflection state on the surface of the measured object, and FIG. 8B is a reflected light distribution shown in association with FIG.

FIG. 9 is an explanatory side view showing still another example of the reflection state on the surface of the measured object.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Beam projector 11 Deflector 12 Projection lens 13 Scanning point detector 15 Measurement object 15a Scanning line 16 Measurement object mounting table 20, 21 1st optical position detection element, 2nd optical position detection element 22, 23 1st condensing optical system, 2nd condensing optical system 22A, 23A Light receiving part 25, 26, 27 Light receiving lens 30A, 30B Addition circuit 31A, 31B Subtraction circuit 32A, 33B Addition processing output determination part 33A, 33B Division circuit 34A, 34B Correction unit 40 Primary determination unit 41 Secondary determination unit 42 Counter 45a, 45b, 45c Optical position detection element 51 Convex part 52 Other convex part 53 Light receiving lens 54 Light receiving surface of light receiving element 56 Insulating layer 57 Wiring part P print Substrate S Projection point R Reflected center of gravity G Light center of gravity related to reflected center of gravity G 'Light center of gravity related to projected point

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 2F065 AA02 AA24 AA51 BB05 CC01 DD06 FF65 HH04 HH13 JJ01 JJ05 JJ16 LL05 LL08 LL13 LL15 LL57 LL62 LL65 MM16 PP11 QQ13 QQ23 QQ25 QQ26 QQ27 QF08 DA07 DA03 FA14 FA27 FA45 2G051 AA65 AB14 BA10 BB09 CA03 CA08 CB01 EA14 EB01

Claims (5)

[Claims] An apparatus for performing optical measurement by forming a detection light spot on a surface of a measurement object, wherein the reflection light is detected from the detection light spot on the surface of the measurement object and arranged in different directions. At least two light receiving elements, and when two of the detected position information obtained by these light receiving elements match within a set allowable error range, any one of the two detected position information is detected. An optical measurement device comprising: a determination processing circuit for selecting the information as primary effective detection position information at the projection point of the detection light spot. 2. The method according to claim 1, wherein when the primary valid detection position information is not selected, the determination processing circuit sets the stored detection position information stored as the valid detection position information at the projection point at the immediately preceding measurement point. 2. The optical measuring device according to claim 1, wherein the detection position information that is approximated within the range is selected as secondary effective detection position information at the projection point of the detection light spot. 3. When the secondary effective detection position information is not selected, the determination processing circuit converts the stored detection position information stored as the effective detection position information at the immediately preceding projection point into the detection light. 3. The optical measuring device according to claim 2, wherein the optical measuring device is selected as tertiary effective detection position information at a spot projection point. 4. A beam projector for forming a light spot for surface condition detection on the surface of the object to be measured, scanning means for scanning the light spot for surface condition detection by the beam projector,
At least two light position detecting elements arranged in different directions for detecting reflected light from the surface state detecting light spot, and position displacement information obtained by these light position detecting elements are arithmetically processed to detect the surface state. A surface condition inspection apparatus comprising: an arithmetic processing unit that outputs effective position displacement information at a projection point of a light spot for use. The arithmetic processing unit includes a determination processing circuit according to any one of claims 1 to 3. A surface condition inspection device characterized by having: 5. The surface condition inspection apparatus according to claim 4, wherein the optical position detecting element is a linear position detecting element for detecting a linear displacement.