JP2012078133A - Inspection head of surface inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection head for a surface inspection device, capable of detecting minute defects of the surface of an object to be inspected.SOLUTION: An inspection head 1 of a surface inspection device includes a projection/reception optical fiber 11 for guiding inspection light emitted from a laser diode 14 to project it to the surface of an object 100 to be inspected, and receiving the reflected light to guide it to a photodetector 15 for detecting the intensity of the reflected light, and inspects the surface of the object 100 to be inspected based on the detection result of the photodetector 15. The projection/reception optical fiber 11 is an optical fiber coupler that includes a molten elongation part 11c formed by melting, drawing and joining a part of two optical fibers 11a and 11b. One optical fiber 11a branched from the molten drawing part 11c guides inspection light from the laser diode 14, the other optical fiber 11b guides reflected light to the photodetector 15, inspection light is projected from the end surface 11f of the molten drawing part 11c to the surface of the object 100 to be inspected, and the reflected light is received by the end surface 11f.

Description

  The present invention relates to an inspection head for projecting and receiving inspection light in a surface inspection apparatus that irradiates the surface of an inspection object with inspection light and inspects the surface state based on the amount of received reflected light.

  There is known an apparatus for inspecting the surface of a cylindrical inspection object by irradiating inspection light from an inspection head onto the inner peripheral surface of the inspection object (for example, see Patent Document 1). This inspection apparatus has an inspection head in which a plurality of light receiving fibers for receiving reflected light are adjacent to each other around a light projecting fiber for projecting inspection light, and these optical fibers are held by a fiber holding cylinder, Based on the amount of reflected light, a two-dimensional image of the surface is generated to inspect defects such as surface scratches.

JP 2007-147324 A

  When inspecting the surface of an object to be inspected using the above-described inspection head, the focus of the inspection light connected on the surface is shifted so that the reflected light is received by the light receiving fiber, and the spot diameter to be irradiated is increased. Reflected light can be incident on a light receiving fiber provided around the optical fiber. In recent years, there has been an increasing demand for inspecting finer defects. However, when the spot diameter is increased as in the above-described inspection apparatus, the acquired two-dimensional image becomes unclear and defects such as fine scratches cannot be detected. There is a fear.

  Accordingly, an object of the present invention is to provide an inspection head of a surface inspection apparatus capable of detecting minute defects on the surface of an object to be inspected.

  The inspection head of the surface inspection apparatus of the present invention guides the inspection light emitted from the light source (14), projects the light onto the surface of the inspection object (100), receives the reflected light, and detects the intensity of the reflected light. An inspection head (1) of a surface inspection apparatus that has a light projecting / receiving fiber (11) for guiding reflected light to a detection means (15) that inspects the surface of the object to be inspected based on the detection result of the detection means. The light projecting / receiving fiber is an optical fiber coupler having a melt-stretching part (11c) in which a part of two optical fibers (11a, 11b) is melt-stretched and joined, and one of the lights branched from the melt-stretching part The fiber (11a) guides the inspection light from the light source, the other optical fiber (11b) guides the reflected light to the detecting means, and the inspection light is transmitted from the end surface (11f) of the melt-drawn portion to the surface of the inspection object. The reflected light is projected on Serial end face to solve the above problems by receiving.

  According to the inspection head of the surface inspection apparatus of the present invention, the melt extending portion projects inspection light onto the surface of the object to be inspected and receives reflected light of the inspection light. In addition, the light receiving fiber is shared. Therefore, there is no need to increase the spot diameter, and the focus of the inspection light can be used with the minimum value. Therefore, the acquired two-dimensional image becomes clear and a finer defect can be detected.

  In one form of the inspection head of the present invention, the end surface of the melt extension part may be inclined with respect to the normal direction of the optical path of the inspection light incident on the end surface. According to this aspect, when the inspection light is incident on the end face of the melt extending portion, it is possible to prevent a part of the inspection light from being reflected and incident on the detection means.

  In the form in which the end surface of the melt extending portion is inclined, the fiber holding tube (12) for holding the light projecting and receiving fiber is provided, and the incident direction of the inspection light incident on the end surface is in the axis (AX) direction of the fiber holding tube. The optical path of the inspection light emitted from the end face may be along the axial direction of the fiber holding cylinder. According to this aspect, when the end surface is inclined to prevent the inspection light from entering the detection means, the inspection light incident on the end surface is inclined with respect to the axial direction of the fiber holding cylinder, thereby The optical path can be adjusted along the axial direction of the sensor head.

  In addition, in the above description, in order to make an understanding of this invention easy, the reference sign of the accompanying drawing was attached in parenthesis, but this invention is not limited to the form of illustration by it.

  As described above, in the inspection head of the surface inspection apparatus according to the present invention, the melt extending portion projects the inspection light on the surface of the object to be inspected and receives the reflected light of the inspection light. The previously used light projecting fiber and light receiving fiber are made common. Therefore, there is no need to increase the spot diameter, and the focus of the inspection light can be used with the minimum value. Therefore, the acquired two-dimensional image becomes clear and a finer defect can be detected.

1 is a schematic view of an inspection head of a surface inspection apparatus according to an embodiment of the present invention. An enlarged view of a light emitting / receiving fiber. The plane schematic diagram which showed the end surface of the melt extension part. Sectional drawing of a sensor head.

  FIG. 1 shows a schematic diagram of an inspection head of a surface inspection apparatus according to an embodiment of the present invention. The surface inspection apparatus is an apparatus suitable for inspecting a cylindrical inner peripheral surface 100 a provided on the inspection object 100. The surface inspection apparatus includes an inspection head 1 for inspecting the inner peripheral surface 100a, and further performs a drive mechanism for driving the inspection head 1, operation control of the drive mechanism, processing of detection results by the inspection head 1, and the like. A control device is provided. The surface inspection apparatus inserts the inspection head 1 into the inner peripheral surface 100a of the inspection object 100, and rotationally drives either the inspection object 100 or the inspection head 1 to connect the surface of the inner peripheral surface 100a and the inspection head 1 together. Move relative. The inspection head 1 irradiates the inner peripheral surface 100a with inspection light and inspects the surface, and based on the detection result of the reflected light, the control device generates a two-dimensional image and determines the presence or absence of a defect. In addition, you may apply a well-known technique about the drive mechanism and control apparatus of a surface inspection apparatus.

  The inspection head 1 includes a sensor head 2 that projects and receives inspection light and reflected light, and a hollow shaft-shaped mirror holding cylinder 3 provided coaxially (axis line AX) outside the sensor head 2. The mirror holding cylinder 3 is rotatably supported on the outer side of the sensor head 2. A mirror 4 is fixed to the tip of the mirror holding tube 3, and a light projection window 3 a is provided on the outer periphery of the mirror holding tube 3 so as to face the mirror 4. The mirror 4 changes the optical path of the inspection light emitted from the sensor head 2 toward the projection window 3a, and directs the optical path of the reflected light entering the sensor head 2 from the projection window 3a toward the sensor head 2. To change.

  The sensor head 2 includes a light projecting / receiving fiber 11 and a fiber holding cylinder 12 that holds the light projecting / receiving fiber 11. At the tip of the fiber holding cylinder 12, the inspection light guided through the light projecting / receiving fiber 11 is emitted in the form of a beam along the axis AX direction of the mirror holding cylinder 3, and along the axis AX direction of the fiber holding cylinder 12. A lens 13 that collects the reflected light traveling in the direction opposite to the inspection light on the light projecting / receiving fiber 11 is provided.

  FIG. 2 shows an enlarged view of the light projecting / receiving fiber 11. As the light projecting / receiving fiber 11, an optical fiber coupler having a melt extending part 11c obtained by melt extending and joining a part of two optical fibers 11a and 11b is applied. The end portions 11d and 11e of the two optical fibers 11a and 11b branched from the melt extending portion 11c of the light projecting / receiving fiber 11 are reflected by the laser diode 14 as a light source of inspection light and the reflection reflected from the inspection object 100, respectively. A photodetector 15 is connected as detection means for outputting an electric signal having a current or voltage corresponding to the amount of light per unit time (reflected light intensity). The inspection light emitted from the laser diode 14 is received by the end portion 11, guided to the optical fiber 11a and the melt extending portion 11c, and emitted from the end surface 11f of the melt extending portion 11c toward the axis AX direction of the sensor head 2. The Further, the reflected light from the object to be inspected 100 travels in the sensor head 2 in the axis AX direction, enters the end surface 11f of the melt extending portion 11c, is guided to the melt extending portion 11c and the optical fiber 11b, and enters the photodetector 15. . The melt extending portion 11 c branches the reflected light incident from the end surface 11 f at a ratio of 50:50 and distributes it to the photodetector 15.

  Next, the operation of the inspection head 1 will be described. FIG. 3 is a schematic plan view showing the end face 11f of the melt-extending portion 11c. The light projecting / receiving fiber 11 receives the inspection light and receives the reflected light at the melt extending portion 11c. The optical fiber of the inspection head in the conventional surface inspection apparatus is divided into a light projecting fiber for guiding the inspection light and a light receiving fiber for guiding the reflected light, and a plurality of light receiving fibers are provided around one light projecting fiber. Arranged and used. In this case, in order to receive the reflected light reflected by the inner peripheral surface 100a of the inspection object 100 with the light receiving fiber, the focal point connected by the inner peripheral surface 100a is shifted, and the spot diameter irradiated on the inner peripheral surface 100a is increased. Thus, the reflected light is adjusted to enter the light receiving fiber. However, when the spot diameter is increased, the acquired two-dimensional image tends to be unclear. In recent years, the accuracy of defect detection required by users of surface inspection apparatuses has increased, and it has become necessary to detect minute defects of φ0.1 [mm] or less. In the inspection head 1 of the present invention, since the inspection light can be emitted and the reflected light can be received by the melt extending portion 11c of the light projecting / receiving fiber 11, it is not necessary to increase the spot diameter, and the focus is used at the minimum value. Can do. For this reason, the acquired two-dimensional image becomes clear and a fine defect can be detected.

  FIG. 4 shows a cross-sectional view of the sensor head 2. The end surface 11f of the melt extending portion 11c of the sensor head 2 is inclined by θ2 with respect to the normal direction N of the inspection light L incident on the end surface 11f. Thereby, the inspection light L reflected by the end face 11 f is prevented from entering the photodetector 15. On the other hand, tilting the end surface 11f by θ2 shifts the optical path of the inspection light after exiting from the end surface 11f from the axis AX. In order to prevent this, the incident direction of the inspection light L incident on the end surface 11f is inclined by θ1 with respect to the direction of the axis AX of the sensor head 2, so that the optical path of the inspection light emitted from the end surface 11f is changed to the axis AX of the sensor head 2. It is adjusted along the direction. The end of the melt extending portion 11c is fixed so as to maintain the angles θ1 and θ2 with respect to the fiber holding cylinder 12. As a result, the inner peripheral surface 100a can be inspected by relative movement and rotation between the sensor head 2 and the mirror holding cylinder 3. As an example, θ1, θ2, and θ3 are 3 °, 8 °, and 79 °, respectively.

  The present invention is not limited to the above-described form and can be implemented in various forms. For example, in this embodiment, the present invention is applied to the inspection of the cylindrical inner peripheral surface 100a. However, the present invention is not limited to this. For example, the mirror holding cylinder 3 is moved in the axis AX direction without rotating, and the direction orthogonal to the axis AX direction is used. It can also be used as an inspection device for an inspection object having a flat surface by moving the surface.

DESCRIPTION OF SYMBOLS 1 Inspection head 2 Sensor head 3 Mirror holding | maintenance cylinder 11 Light transmitting / receiving fiber 11c Melt extending part 11f End surface 12 Fiber holding cylinder 14 Laser diode (light source)
15 Photodetector (detection means)
100 Inspected object 100a Inner peripheral surface AX axis

Claims (3)

A light-receiving / receiving fiber that guides the inspection light emitted from the light source, projects the light onto the surface of the object to be inspected, and receives the reflected light to detect the intensity of the reflected light; An inspection head of a surface inspection apparatus that inspects the surface of the object to be inspected based on the detection result of the means,
The light projecting / receiving fiber is an optical fiber coupler having a melt-stretched portion obtained by melt-stretching a part of two optical fibers, and one optical fiber branched from the melt-stretched portion guides inspection light from the light source. The other optical fiber guides the reflected light to the detection means, the inspection light is projected onto the surface of the object to be inspected from the end face of the melt-drawn portion, and the end face receives the reflected light. head.   The inspection head according to claim 1, wherein an end face of the melt extending portion is inclined with respect to a normal direction of an optical path of inspection light incident on the end face. A fiber holding cylinder for holding the light emitting and receiving fiber;
The incident direction of the inspection light incident on the end face is inclined with respect to the axial direction of the fiber holding cylinder, and the optical path of the inspection light emitted from the end face is along the axial direction of the fiber holding cylinder. 2. Inspection head according to 2.

Images