JP7131792B2 - inspection system - Google Patents

Description

The present invention relates to an inspection system for inspecting the surface of an object to be inspected by irradiating the object with an inspection laser beam from an inspection head.

In Patent Document 1, a shaft-shaped inspection head provided with a mirror at its tip is moved along the axis while being rotated around the axis by a drive mechanism, and inspection light incident along the axis into the inspection head is detected. The optical path of is changed by a mirror, and the inspected object is irradiated with the inspection light whose optical path has been changed. In the surface inspection apparatus for detection, it is described that the inspection head includes a head body attached to a drive mechanism, and a holding section detachably provided on the head body and holding a mirror.

JP 2007-315821 A

In recent years, there has been a demand for the inspection of the surface of microfabricated articles. In particular, inspection of the surface of an inspection object (object to be inspected) having a small diameter (ultrafine) hole with a diameter of about several millimeters has become possible. is requested.

One aspect of the present invention is a hollow inspection head extending in a rod shape along a central axis, the inspection head being rotated around the central axis, and a laser for inspection along the central axis passing through the inspection head. an optical system for providing light and receiving reflected light from the surface of the inspected object returned along the central axis. The inspection head includes a rotating part that is driven to rotate, a holder part having a cylindrical front wall attached to the rotating part, and a very fine hollow needle part attached to the front wall along the central axis. , the needle portion is an optical element disposed at the tip, and includes an optical element that emits an inspection laser beam toward the object to be inspected with respect to the central axis and guides the reflected light in the direction of the central axis. .

In order to inspect the inner surface of a small diameter (ultrafine) hole with a diameter of several millimeters, an ultrafine head with a diameter of about 1mm is inserted into the hole to be inspected. It is necessary to rotate the ultra-fine head stably in order to avoid interference with the In the present invention, the tip of the inspection head is formed in the shape of an ultra-thin hollow needle, which is supported by a thick holder and rotated. To provide an inspection system capable of inspecting the inner surface of a hole in a

The diameter Dn of the ultrafine needle portion may satisfy the following condition (1), and the diameter Dh of the front wall of the holder portion or its vicinity may satisfy the following condition (2).
0.5mm≦Dn≦1.5mm (1)
5≦Dh/Dn≦40 (2)

Also, the diameter Dn of the needle portion and the thickness L of the front wall of the holder portion may satisfy the following conditions.
5≦L/Dn≦30 (3)

The optical system includes a non-rotating fiber optic bundle inserted into the needle portion, the needle portion being a photochromic lens disposed between the tip of the fiber optic bundle and the optical element, the needle It may also include a photochromic lens that rotates with the unit.

The inspection system may have a rotation unit that rotates the inspection head around a central axis. The inspection system may further include a moving unit that relatively moves the inspection head and the inspection object including the hollow portion into which the needle portion is inserted along the central axis. The inner diameter Di of the hollow portion to be inspected may satisfy the following condition (4).
Dn+0.5 mm≦Di≦Dn+3.0 mm (4)

The perspective view which shows the outline|summary of an inspection apparatus. FIG. 2 is a cross-sectional view (II-II cross-sectional view) showing a schematic configuration of the inspection apparatus; FIG. 2 is a perspective view showing an outline of an inspection head; FIG. 2 is a cross-sectional view (IV-IV cross-sectional view) showing a schematic configuration of an inspection head; FIG. 5 is an enlarged cross-sectional view showing the configuration of the tip of the inspection head shown in FIG. 4 ; FIG. 6 is a cross-sectional view showing a further enlarged configuration of a needle portion of the inspection head shown in FIG. 5;

FIG. 1 shows the appearance of an inspection apparatus (inspection system) 1, and FIG. 2 shows a schematic configuration of the inspection apparatus 1 using a cross section. This inspection apparatus (surface inspection apparatus) 1 is suitable for inspecting the shape or state of the inner surface 4 of a hollow portion 3 such as a hole or a recess provided in an object 2 to be inspected. An example of the hollow portion 3 is a through hole with a diameter of several millimeters.

The inspection apparatus 1 includes a hollow inspection head 10 extending in a bar shape along a central axis 11 , a rotation unit 20 rotating the inspection head 10 around the central axis 11 , an optical system 30 for supplying inspection laser light and receiving reflected light from the surface 4 of the inspection object 2 returned along the central axis 11; 11, and a housing 5 containing the rotation unit 20, the optical system 30 and the movement unit 25. As shown in FIG.

The inspection apparatus 1 includes a moving unit 25 for the inspection head 10 housed in the housing 5 as a moving unit 25 for relatively moving the inspection head (inspection probe) 10 and the object 2 to be inspected. The moving unit 25 includes a carriage 28 on which the inspection head 10, the rotating unit 20 and the optical system 30 are mounted, and a combination of a ball screw 26 and a moving motor 27 for moving the carriage 28 back and forth (left and right in FIG. 2). The inspection head 10 includes a fixed portion 19 serving as a proximal end and a rotating portion 18 mounted so as to rotate with respect to the fixed portion 19. The fixed portion 19 is mounted on a carriage 28 via a mounting unit 29. there is The inspection head 10 includes, at its tip, a fine needle portion 12 protruding forward 16 along a central axis (rotational axis, axial center) 11 . The needle part 12 is fixed to the front wall 14a of a thick cylindrical holder part 14 so as to protrude along the central axis 11 with respect to the needle part 12, and is fixed to the rotating part 18 via the holder part 14. It rotates around the central axis 11 together with the rotating part 18 .

The configuration of the moving unit 25 is an example, and may be a slider, a moving table, or the like. The moving unit 25 moves the inspection head 10 between a position P<b>1 where the inspection head 10 projects forward from the housing 5 and a position P<b>2 where the inspection head 10 retreats inside the housing 5 . Instead of moving the inspection head 10 back and forth, or while moving the inspection head 10 back and forth, the object to be inspected 2 may be moved using a robot or the like.

The optical system 30 includes a semiconductor laser (laser diode, LD) 31 that generates laser light for inspection, a light receiving element (for example, photodiode, CCD, CMOS, etc.) 32 that receives reflected light, and driving of the semiconductor laser 31. and a control unit 33 including circuits, circuits for processing signals received by the light receiving element 32, and the like. Signals received by the optical system 30 are sent to a computer (personal computer) (not shown) via the control unit 33, where they are further processed and used for analysis of the surface 4 of the object 2 to be inspected. Optical system 30 further includes an optical fiber 35 inserted inside inspection probe 10 .

An example of a rotating unit 20 is a motor 21 mounted on a carriage 28 . A pulley 22 driven by a motor 21 is connected to the rotating portion 18 of the inspection head 10 by a drive belt 23 , and the motor 21 rotates the rotating portion 18 of the inspection head 10 around the central axis 11 via the drive belt 23 . It rotates at high speed (with the central axis 11 as the center of rotation).

The inspection head (inspection probe) 10 is extracted and shown in FIG. FIG. 4 shows a schematic configuration of the inspection head 10 using a cross section. Further, FIG. 5 shows an enlarged cross section of the tip portion (front portion) of the inspection head 10, and FIG. 6 shows an enlarged cross section of the configuration of the needle portion 12 at the tip of the inspection head 10. .

The inspection head 10 is a hollow cylindrical body that extends along the rotation axis 11 as a whole, and is coaxially attached to a fixed portion 19 at the proximal end so as to rotate with respect to the fixed portion 19 via a bearing 17 . , and a rotating portion 18 extending toward the tip 16 . The rotating portion 18 is rotationally driven and includes a relatively thick driving portion 15 to which rotational force is transmitted via a driving belt 23, a holder portion 14 attached to a front portion 16 of the driving portion 15, and a front wall 14a of the holder portion 14. and a needle portion (insertion portion) 12 extending thinly from the center of the needle portion (insertion portion) toward the tip (forward). An opening (notch) 13 directed radially is provided at the tip 12 a of the needle portion 12 , and an inspection laser beam (probe beam) 61 is emitted through the opening 13 to the hollow portion 3 of the object 2 to be inspected. , and reflected light 62 from the surface 4 of the object to be inspected 2 is returned from the needle portion 12 to the inspection head 10 .

An optical fiber bundle 35 is inserted inside the inspection head 10 to guide the probe light 61 and the reflected light 62 along the central axis 11 . The optical fiber bundle 35 that constitutes the optical system 30 is a bundle of a plurality of fibers. and a light receiving fiber 35 b leading to the light receiving element 32 . Furthermore, the optical system 30 includes a holding cylinder 34 that holds the optical fibers 35 in a bundled state inside the inspection head 10 .

The needle portion 12 extends forward 16 along the central axis 11 from the front wall 14a of the holder portion 14, and an optical element 50 for controlling the emission direction of the probe light 61 is attached to the tip (near the tip) 12a. An example of the optical element 50 is a plane mirror, and may be another optical element such as a prism that has a reflecting surface capable of controlling the direction of emergence and incidence of light. In the inspection apparatus 1 of this example, the angle of the mirror surface (reflecting surface) 51 of the optical element 50 is set to 45 degrees, and the probe light 61 emitted from the optical fiber 35 with the central axis 11 as the optical axis is directed to the central axis (light axis) 11 in a direction perpendicular to the direction. In addition, the mirror surface 51 of the optical element 50 reflects the light (reflected light) 62 reflected from the inner surface 4 to be inspected toward the optical fiber 35 of the central axis 11 . An optical fiber 35 supported by a holding cylinder 34 is inserted into the needle portion 12 to a position retracted from the tip 12a. It is attached so as to be supported by the needle portion 12 .

The photochromic lens 36 is an objective lens having a focal length suitable for condensing the probe light 61 output from the tip 35c of the optical fiber 35 onto the inspection target surface 4 via the reflecting surface 51. FIG. The photochromic lens 36 also has a function of condensing the reflected light 62 introduced into the inspection head 10 via the reflecting surface 51 onto the tip 35 c of the optical fiber 35 . The optical system 30 that supplies the probe light 61 along the central axis 11 of the inspection head 10 and detects the reflected light 62 is not limited to the one using the optical fiber 35, and is equipped with a dichroic prism or the like, such as an optical pickup. Other known optical systems may be used. An optical system 30 using an optical fiber 35 is suitable for inputting and outputting the probe light 61 and the reflected light 62 inside the fine needle portion 12 .

In recent years, the precision of microfabrication has improved, and products or products with ultrafine through holes or bottomed holes processed in various applications, such as nozzles and paths through which fluids such as liquids pass, optical devices, and mechanical devices. parts are manufactured. An example of the ultrafine hole 3 has a diameter Di of several mm or less, for example, 5 mm or less, or 3 mm or less, or even 2 mm or less. Considering the clearance from the inner surface 4, the diameter Dn of the needle portion 12 for irradiating the inner surface 4 of the hole (hollow portion) 3 with such dimensions with the probe light 61 and collecting the reflected light 62 is determined according to the condition (1 ), it is desired to be 1.5 mm or less. In particular, when the diameter Di of the hole 3 to be inspected is about 3 mm or less, the diameter (outer diameter) Dn of the needle portion 12 is preferably 1.2 mm or less, for example 1.0 mm. At present, the diameter (inner diameter) Di of the hole 3 that can be inspected by this type of inspection apparatus 1 is about 1.0 mm or more, and including the clearance, the range shown in Equation (4) is preferable.

An example of the needle portion 12 is a stainless steel needle-like cylinder having an outer diameter Dn of 1.0 mm and an inner diameter of 0.8 mm. The inspection device 1 having this needle portion 12 can inspect the condition of the inner surface 4 of the hole 3 having a diameter Di of 3 mm or less. An optical fiber 35 supported by a non-rotating holding cylinder 34 having a diameter (outer diameter) of about 0.6 mm is inserted inside the needle portion 12 . The holding cylinder 34 extends from the needle portion 12 to the inside 14b of the holder portion 14 and is fixed to the forwardly extending portion 19a of the fixing portion 19 . On the other hand, the needle portion 12 is connected to the rotating portion 18 via the holder portion 14 and is rotated around the central axis (rotating shaft) 11 by the rotating unit 20 . The optical element 50 attached (arranged) to the tip 12a rotates together with the needle part 12, and the probe light 61 reflected by the optical element 50 is radially emitted through the aperture 13, and the inner surface 4 of the hole 3 is scanned in the circumferential direction. Reflected light 62 from the inner surface 4 is returned to the interior of the needle portion 12 via the aperture 13 and the optical element 50, reflected along the central axis 11, and input to the optical fiber 35. FIG.

A photochromatic lens 36 is fixed to the needle portion 12 , and the photochromatic lens 36 rotates around the central axis 11 together with the needle portion 12 , that is, together with the optical element 50 . Therefore, the probe light 61 and the reflected light 62 are input to and output from the inner surface 4 via the photochromic lens 36 and the optical element 50 that rotate together (rotate synchronously). For this reason, the optical path formed by the photochromic lens 36 and the optical element 50 has little dependency on the rotation angle, and the inspection apparatus 1 directs the probe light 61 and the reflected light 62 to the inner surface 4 with little angle dependency. can be input and output at the same time, and a stable signal can be sampled. It is difficult to fix the lens 36 inside the very fine needle part 12, which has a diameter Di of about 1 mm and an inner diameter of less than 1 mm, with little dependency on the rotation angle. In the inspection apparatus 1 of this example, the probe light 61 and the reflected light 62 can be input and output under the same conditions with respect to the rotation angle by rotating the lens 36 attached to the needle portion 12 .

In order to accurately inspect the state of the inner surface 4 of the hole 3 having an inner diameter Di of several millimeters or less, the needle portion 12 having a diameter Dn of 1.5 mm or less must be accurately displaced or aged around the central axis 11 . It is desirable to rotate without differential motion. For this reason, in the inspection apparatus 1, as shown in an enlarged view in FIG. A mounting hole 14c having an inner diameter approximately equal to the outer diameter Dn of 12 and a length L of about 1 mm is provided. By supporting the needle portion 12 along the central axis 11 with the mounting hole 14c having a length L sufficient for the diameter Dn of the needle portion 12, the ultrafine needle portion 12 can be stably rotated. The needle part 12 is assembled with the holder part 14 using a special jig and shipped.

The diameter (outer diameter) Dh of the holder portion 14 is a size that is easy to handle on site, and preferably satisfies the following condition (5).
5mm≦Dh≦30mm (5)
The lower limit of condition (5) is preferably 10 mm, while the upper limit is more preferably 20 mm in consideration of weight, cost, and the like. Therefore, the outer diameter Dh of the holder portion 14 with respect to the diameter Dn of the needle portion 12 preferably satisfies the condition (2) described above. The lower limit of condition (2) is preferably 10, the upper limit is preferably 30, and 25 is more preferable.

In order to stably hold the needle portion 12, the length of the mounting hole 14c (the wall thickness of the front wall 14a) L should be set in relation to the outer diameter Dn of the needle portion 12 in the condition (3) described above. is preferably satisfied. Furthermore, the lower limit of condition (3) is preferably 10, and the upper limit is preferably 20 considering weight, cost, and the like. Specifically, the length (thickness of the front wall 14a) L of the attachment hole 14c preferably satisfies the following condition (6).
5mm≦L≦30mm (6)
The lower limit of condition (6) is preferably 10 mm, and the upper limit is preferably 20 mm.

As described above, the inspection apparatus (inspection system) 1 according to the present invention has an extremely fine needle portion 12 with a diameter of about 1 mm attached to the tip of an inspection head (inspection probe) 10, and has a diameter of several millimeters, for example. It is possible to inspect the inner surface 4 of the hollow portion 3 with a diameter of 3 mm or less, and to evaluate the state of the inner surface (surface).

1 inspection device (inspection system), 10 inspection head

Claims (5)

a hollow inspection head extending in a bar shape along a central axis, the inspection head being rotated around the central axis;
an optical system for supplying inspection laser light along the central axis through the inspection head and receiving reflected light from the surface of the object to be inspected returned along the central axis;
The inspection head includes a rotating portion that is driven to rotate, a holder portion that is mounted on the rotating portion and has a cylindrical front wall with a sufficient thickness L, and a holder portion that is attached to the front wall along the central axis. and a very thin hollow needle portion having a diameter Dn, the needle portion having the same length as the thickness L provided along the central axis only on the front wall of the holder portion. The needle portion is an optical element disposed at the tip, and the needle portion is an optical element that directs the inspection laser light to the object to be inspected with respect to the central axis. and an optical element that guides the reflected light in the central axis direction, the thickness L of the front wall of the holder portion, the diameter Dn of the needle portion, and the front wall of the holder portion or an inspection system in which the diameter Dh of its vicinity satisfies the following conditions.
5≦L/Dn≦30
0.5mm≤Dn≤1.5mm
5≤Dh/Dn≤40 In claim 1 ,
the optical system comprises a non-rotating fiber optic bundle inserted into the needle portion;
The inspection system according to claim 1, wherein the needle portion includes a photochromic lens disposed between the tip of the optical fiber bundle and the optical element, the photochromic lens rotating together with the needle portion. In claim 1 or 2 , further,
An inspection system comprising a rotation unit that rotates the inspection head around the central axis. In any one of claims 1 to 3 ,
The object to be inspected includes a hollow portion into which the needle portion is inserted,
An inspection system, further comprising a moving unit that relatively moves the inspection head and the object to be inspected along the central axis. In claim 4 ,
An inspection system, wherein the inner diameter Di of the hollow portion satisfies the following conditions.
Dn+0.5 mm≦Di≦Dn+3.0 mm

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