JPH0412212A - Comb-shaped light projector and surface shape measuring instrument using the same - Google Patents

Abstract

PURPOSE:To improve the work efficiency by providing the device so that optical axes of a condensing lens placed in the tip of an optical fiber of an optical fiber band are parallel to each other and exist in one plane. CONSTITUTION:A video signal outputted from a CCD camera 18 is stored in an image memory 29 through an A/D converter 28. In an image processor 30, image data is read in from the memory 29, a center point P of each light spot 17a is determined, height H of each center point P is calculated by using a prescribed expression, a surface shape of a sample 10 is measured, and its result is supplied to a plotter 32 and a monitor TV 34. By such a constitution, in accordance with the kind of the sample 10 or the area, magnification of a zoom lens 18a of the camera 18 is changed. As a result, the number of picture elements (u) corresponding to the distance (d) is changed. This number of picture elements (u) is proportional to the photographing magnification. Also, the num ber of picture elements (u) is the number of picture elements between the center points P of the adjacent light spots 17a, and this number of picture elements (u) can be derived by the same method.

Description

[Detailed Description of the Invention] rSummary] Regarding a light projector that projects comb-shaped light onto a sample surface and a surface shape measuring device using the same, a lens that images a light sporat formed on the sample surface into a light sensor force. In order to avoid the need to recalibrate the equipment even if the magnification of It has a condensing lens arranged and a light source disposed at the base end of the optical fiber band and introducing light into the optical fiber, and the optical axis of each condensing lens is parallel to each other and exists in one plane. A comb-shaped light projector is arranged, and a camera that photographs a row of light spots formed on the sample surface by the projection of light from the comb-shaped light projector and outputs a video signal, and a camera that receives the video signal and converts it into a digital image. means for converting into a value and outputting it as pixel data, receiving the pixel data, determining the number of pixels between the adjacent light spots, and forming the light spot by a light cutting method using the number of pixels and the constant interval. A surface shape measuring device is constituted by means for detecting and outputting the height at the position.

The present invention relates to a light projector that projects comb-shaped light onto the surface of a sample such as a printed wiring board with or without components mounted thereon, and a surface shape measuring device using the same.

2. Description of the Related Art There are the following types of surface shape measuring devices that measure the surface shape by optically detecting the height of each point on the surface of a sample.

■Project a light beam onto the sample surface to form a light spot,
This light spot is detected by a PSD (optical position detector) using an imaging lens.
The height of the light spot is detected by scanning the light beam to measure the shape of the sample surface.

■Project a light beam onto the sample surface to form a light spot,
This light spot is photographed with a CCD camera or the like, the video signal is digitized, image processing is performed, and the surface shape is measured using a light cutting method.

According to such a surface shape measuring device, it is possible to measure an uneven shape having a height of several μm to several mm with high precision.

(Problems to be Solved by the Invention) However, with any of the above-mentioned surface shape measuring devices, if the magnification of the lens that focuses the light spot on the optical sensor is changed, the device cannot be operated by measuring the surface shape of the standard sample. It was necessary to calibrate the measurement (the original work was 4tl&).

In view of these problems, an object of the present invention is to eliminate the need to recalibrate the apparatus even if the magnification of the lens that images the light spot formed on the sample surface onto the optical sensor is changed. An object of the present invention is to provide a comb-shaped light projector and a surface shape measuring device using the same.

1. Means for Solving the Problems and Their Effects] The present invention will be explained with reference to embodiment drawings.

The comb-shaped light projector of the present invention includes, for example, as shown in FIG. / lenses 26 and a light source 24 arranged at the base end of the optical fiber band 20 and introducing light into the optical fiber 20a, so that the optical axes of the respective condensing lenses 2G are parallel to each other and exist in one plane. It is placed.

According to the comb-shaped light projection device 14 having such a configuration, the interval between the light spots 17 is equal to the pitch d of the optical fibers 20'a.

For example, as shown in FIG. The shape of the optical fiber 2 is oval, but the distance between the two optical spora) 17b remains unchanged, and the optical fiber 2
It is equal to the pitch d of 0a.

According to this comb-shaped light projector 14A, when the thickness of the sample 10 changes depending on the type, the long optical fiber band 20
Since it is only necessary to adjust the height of the cylindrical lens 35 while fixing the condensing lens 26 integral with the comb-shaped light projector 14A, it becomes easy to adjust the comb-shaped light projector 14A.

In the surface shape measuring device of the present invention, for example, as shown in FIG.
A row of light spots 17 formed on the sample surface 10 by the projection of light.
A camera 18 that photographs the image and outputs a video signal, a means for receiving the video signal, converting it into a digital value, and outputting it as pixel data, such as an A/D converter 28 or a binarization circuit, and a means for converting the pixel data. The number of pixels 1 between adjacent optical spora) 17a is determined, and the height of the position where optical spoiler) 17a is formed is detected and output using the optical cutting method using the pixel number U and the constant interval d. and means 30 for doing so.

In the configuration described above, when the imaging magnification of the camera 18 is changed depending on the type of the sample 10 or the area of the sample 10, the number of pixels U corresponding to the interval d of the light spots 17 changes.

However, this number of pixels U is proportional to the imaging magnification.

Further, the number of pixels U is the number of pixels between adjacent light spots 17a, and this number of pixels U (proportional to the photographing magnification) can be obtained using the same method (same computer program).

Therefore, according to the surface shape measuring device having such a configuration, even if the photographing magnification of the camera 18 is changed, the complicated operation of measuring the surface shape of the standard sample and recalibrating the device as in the past can be avoided. There's no need to do it.

In another surface profile measuring device of the present invention, for example, the sixth
As shown in the figure, the comb-shaped light projector 14 configured as described above, the first and second line sensors 40, 42, and the comb-shaped light projector 14
an imaging optical means 36.38 that images a row of light spots formed on the sample surface 10 by the projection of light onto the first and second line sensors 40.42; and a light receiving element 40a of the first line sensor 40. a filter 40b which is arranged at the second line and whose transmittance changes monotonically along the direction perpendicular to the arrangement direction of the light receiving elements 40a; - receives the output of the second line sensor 42;
Means 48 for determining the number of pixels U between adjacent optical spora) 17a
．． 28B, 29B, and 30Δ, and the outputs of the first and second line sensors 40.42, and from the outputs of the corresponding pair of light receiving elements 40a, 42a of both insensors and the number of pixels, optical spoiler) 1. 7. Means for calculating and outputting the height of the position where a is formed 46 to 50.28 A, 2
9A and 30A.

In this surface profile measuring device as well, the number of pixels U can be determined by the same method regardless of the magnification of the imaging lens 36 in the same way as described above, so even if the magnification of the imaging lens 36 is changed, it can be There is no need to perform any complicated operations such as measuring the surface shape of the standard sample and recalibrating the device.

r Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

(1) First Embodiment FIG. 1 shows a surface shape measuring device using a comb-shaped light projector.

The sample 10 is, for example, a printed wiring board with no components mounted or components mounted thereon, and is mounted on an x-y stage 12 for scanning. A comb-shaped light 16 is projected onto the surface of the sample 10 by a comb-shaped light projector 14, and a light spot row 17 in which light sporaters 17a are arranged in a line is formed. This light spot row 1
7, a CCD camera 18 equipped with a zoom lens 18a is arranged, and the surface shape of the sample 1o is measured by photographing the light spot array 17 and processing the image.

The comb-shaped light projector 14 is connected to an optical fiber 2 as shown in FIG.
It is provided with an optical fiber band 20 in which fibers 0a are bundled into a strip at regular intervals d of several tens to hundreds of μm.

One end of the optical fiber band 20 is fixed to a connector 22, and the connector 22 is connected to a light source 24. At the other end of the optical fiber band 20, a condensing microlens 26 is integrally formed on the end face of each optical fiber 20a. The condensing microlens 26 is arranged on a straight line, and this straight line is parallel to the surface of the sample 1o, and the light emitted from the light source 24 passes through the optical fiber 20a and the condensing microlens 26 to the sample 1o. They are placed at a height that converges on the surface of 10. Therefore, the light emitted from the condensing microlens 26 becomes a comb-shaped light 16 as shown in FIG.

The angle between the optical axis of the condensing microlens 26 and the surface of the sample 10 is set to be an acute angle.

When the sample surface shape is as shown in FIG.
The photographed image No. 7 is as shown in FIG. Photospora) 17
The distance y from the reference line of the center point P of a is the optical spora h 1
It is proportional to the height H of the position where 7 a is formed relative to the reference plane, and the relationship between the two is, as is clear from Fig. 4, H = y sin θ, /5in (θ1 + θ2) - (],
). Here, θ1, angle θ2 between the comb light 16 and the sample 10: CC
D is the angle between the optical axis of the camera 18 and the sample 10.

On the other hand, the distance between adjacent optical spora) ], 7a is equal to the pitch d of the optical fiber 20a. In Figure 3,
If the number of pixels corresponding to dly is 1j, , n, then y = nd / u...
(2) holds true.

In FIG. 1, a video signal output from a CCD camera 18 is supplied to an A/D converter 28, digitized, and then stored in an image memory 29. The image processing device 30 reads image data from the image memory 29,
The surface shape of the sample 10 is measured by determining the center point P of each light spot 17a, and then calculating the height H of each center point P using the above equations (1) and (2). , and supplies the results to the plotter 32 and monitor TV 34.

In configuration 1, the magnification of the zoom lens 18a of the CCD camera 18 is changed depending on the type of sample 10 or the area of the sample 10. This changes the number of pixels U corresponding to the distance d.

However, this number of pixels U is proportional to the imaging magnification.

In addition, the number of pixels U is the center point P of the adjacent light spots 17a.
This number of pixels U can be determined using the same method (using the same computer program).

Therefore, even if the magnification of the zoom lens 1.8a is changed, there is no need to carry out the complicated process of measuring the surface shape of the standard sample and recalibrating the apparatus as in the conventional method.

(2) Second Embodiment FIG. 5 shows the state of light emitted by the comb-shaped light projector 14A of the second embodiment.

In this comb-shaped light projector 14A, a cylindrical lens 35 is arranged in front of the condensing microlenses 26 with its elongated direction parallel to the arrangement direction of the condensing microlenses 26. The other points are the same as the first embodiment.

In the third embodiment, by fixing the position of the condensing microlens 26 and changing the position of the cylindrical lens 35 with respect to the condensing microlens 26, the convergence position of the comb-shaped light 16 is made to coincide with the reference plane of the sample 10. I can do it.

In this case, the shape of the light spot 17b becomes an ellipse, but the distance between adjacent light spots 17b remains unchanged and is equal to the pitch d of the optical fibers 20a.

Therefore, if the thickness of the sample 10 changes depending on the type of sample 10, the height of the cylindrical lens 35 can be adjusted while keeping the condensing microlens 26 integrated with the long optical fiber band 20 fixed. Adjustment of the comb-shaped light projector 14Δ becomes easy.

(3) Third Embodiment FIG. 6 shows a surface shape measuring device using a comb-shaped light projector 14.

This comb-shaped light projector 14 is the same as that of the first embodiment, but its arrangement is different from that of the first embodiment, so that the optical axis of the condensing microlens 26 is perpendicular to the surface of the XY stage 12. A comb-shaped light projector 14 is arranged.

A pair of line sensors 40 and 42 are arranged diagonally above the light spot row 17, and an imaging lens 36 and a half mirror 38 are further arranged to form an image of the light spot row 17 on these. . (Optical Spora) - The reflected light from the column 17 passes through the imaging lens 36 and enters the half mirror 3.
The image is divided into two by 8, and each is imaged by a line sensor 40 and 42''.

As shown in FIG. 7, in this line sensor 40, elongated photodiodes 40a are arranged in a row, and the longitudinal direction of the photodiodes 40a is perpendicular to the arrangement direction. For example, the photodiode 40a has a width of 20 μm.
, 2500 μm in length, and 1024 of these are arranged in the line sensor 40. As such a line sensor 40, a commercially available one for spectrum measurement can be used. A filter 4 is provided in front of the photodiode 40a.
0b is arranged and is fitted into the frame of the package of the line sensor 40. The transmittance of the filter 40b is
It changes linearly along the longitudinal direction of the photodiode 40a (X-axis direction in FIG. 7) as shown in FIG.

On the other hand, the line sensor 42 uses a protective glass plate 4 with a uniform transmittance of almost 100% instead of the filter 40b.
2b is provided, and the other points have the same configuration as the line sensor 40.

The intensity of the light received by the photodiode 40a is the same as that of the light spot 17a.
The output of the photodiode 40a divided by the output of the corresponding photodiode 42a is determined by the brightness of the filter 40b and the light transmission position X on the filter 40b.
It depends only on the light transmission position X.

Therefore, the driver 44 electrically scans the line sensors 40 and 42 to detect the corresponding pair of photodiodes 40a.
, 42a are taken out from the amplifiers 46 and 42a, respectively.
．． 48 and converts it into voltage values A and B, and divides it into a dividing circuit 50.
supply to The division circuit 50 divides this A by B and outputs a height signal A/B. When the position of the reference plane of the sample 10 corresponds to the center of the light-receiving surface of the sample 10 as shown in FIG. 6, the height signal A/B is proportional to the height H of the above equation (1). are doing. Height signal A/B is A,/D converter 2
After being digitized at 8A, it is stored in the height memory 29Δ.

Meanwhile, at the same time, the brightness signal B from the amplifier 48A
is digitally converted by the A/D converter 28B and then stored in the brightness memo 1J29B.

The image processing device 30Δ calculates the number of pixels U based on the brightness data stored in the brightness memo IJ 29B in the same manner as in the first embodiment. This process is performed by the imaging lens 3
It is sufficient to perform this once every time the magnification of 6 is changed.

The image processing device 30A also calculates the height t which is proportional to (A/B-Δ). Here, Δ is the reference plane height correction value of the sample 10, which is determined, for example, by the average value of the height signals A/B corresponding to the reference plane near the measurement position.

In this third embodiment as well, the number of pixels U can be determined in the same manner as in the first embodiment, that is, the number of pixels U can be determined using the same method, so the magnification of the imaging lens 36 can be Even if the change is made, there is no need to perform the complicated operations of measuring the surface shape of the standard sample and recalibrating the device as in the past.

r Effects of the Invention) As explained above, according to the comb-shaped light projector and the surface profile measuring device using the same according to the present invention, the magnification of the lens that images the light spot formed on the sample surface on the optical sensor can be changed. However, it has the excellent effect of eliminating the need to recalibrate the measuring device, which greatly contributes to improving work efficiency.

[Brief explanation of the drawing]

1 to 4 relate to a first embodiment of the present invention, in which FIG. 1 is a configuration diagram of a surface profile measuring device using a comb-shaped light projector, and FIG. 2 is a whistle showing the state of light projection by the comb-shaped light projector. FIG. 3 is a photographed image of a row of light spots corresponding to this light projection state, and FIG. 4 is an explanatory diagram of height detection using the light cutting method. FIG. 5 is a diagram showing a light emitting state by a comb-shaped light projector according to a second embodiment of the present invention. 6 to 8 relate to a third embodiment of the present invention, FIG. 6 is a configuration diagram of a surface shape measuring device using a comb-shaped light projector, and FIG. 7 is a partially exploded perspective view of the line sensor of FIG. 6. 8 is a transmittance distribution diagram along the X-axis direction of the filter of FIG. 7. In the figure, 10 is the sample 14, 14A is the comb-shaped light projector 16, the comb-shaped light 17 is the light spot row 17a, 17b is the light spot 18, the CCD camera 18a, the zoom lens 20, the optical fiber band 20a, the optical fiber 24, the light source 26 is Condensing microlenses 28, 28A and 28B, Δ/D converter 29, image memory, 29A, height memory 29B, brightness memory 30, 30A, image processing device 35, cylindrical lens 6, imaging lens 8, half mirror. 0142 is the line sensor Oa, 42a is the photodiode Ob, and the filter 2b is the glass plate.

Claims (1)

[Claims] 1) An optical fiber band (20) in which optical fibers (20a) are bundled at a certain interval (d), and a condenser lens (26) disposed at the tip of the optical fiber of the optical fiber band. )
and a light source (24) disposed at the proximal end of the optical fiber band to introduce light into the optical fiber, arranged so that the optical axes of the condenser lenses are parallel to each other and exist in one plane. A comb-shaped light projector. 2) The comb-shaped light projector according to claim 1, further comprising a cylindrical lens (35) arranged in front of the condenser lens (26) with its longitudinal direction parallel to the arrangement direction of the condenser lens. 3) A comb-shaped light projector (14) according to claim 1 or 2; a camera ( 18); means (28) for receiving the video signal, converting it into a digital value and outputting it as pixel data; receiving the pixel data, determining the number of pixels (u) between the adjacent light spots; A surface shape measuring device comprising: means (30) for detecting and outputting the height of the position where the light spot is formed by a light cutting method using the number of pixels and the constant interval (d). 4) The comb-shaped light projector (14, 14) according to claim 1 or 2.
a), the first and second line sensors (40, 42), and the light spot array (17) formed on the sample surface (10) by the light emitted from the comb-shaped light projector. an imaging optical means (36, 38) for forming an image on the line sensor; and an imaging optical means (36, 38) disposed on the light receiving element (40a) of the first line sensor (40), along a direction perpendicular to the arrangement direction of the light receiving element. a filter (40b) whose transmittance changes monotonically; and means (48, 2) for receiving the output of the second line sensor (42) and calculating the number of pixels (u) between the adjacent light spots;
8B, 29B, 30A) and the outputs of the first and second line sensors, the light spot is formed from the outputs of the corresponding pair of light receiving elements of both line sensors and the number of pixels (u). Means for calculating and outputting the height of the position (46
~50, 28A, 29A, 30A), A surface shape measuring device characterized by having these.