JP2012220343A - Apparatus for measuring thickness of translucent tubular object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the thickness of a translucent tubular object over its whole region in a short time and with high accuracy.SOLUTION: An apparatus for measuring a thickness of a translucent tubular object is provided. In the apparatus, a laser beam emitted to a glass tube G is condensed by an objective lens 57 and the reflected light is received by a diffraction grating 35 and a line sensor 36 to measure a thickness of the glass tube G. The objective lens 57 is made to have a relation: (1/a)+(1/b)=1/Fx, where a focal distance in an X-axis line direction is Fx, an optical distance from a galvano mirror 52 rotating around a Y-axis line to the objective lens 57 is a, and an optical distance from the objective lens 57 to a surface of the glass tube G is b. Even when servo control for an angle around the Y-axis line is performed so that an optical axis of the laser beam is perpendicular to a central axis of the glass tube G, an irradiation position of the laser beam to the glass tube G in the X-axis line direction can be fixed at one position so as not to be changed, to prevent servo from becoming unstable due to the degree of inclination of the glass tube G around a Z-axis line.

Description

  The present invention measures the thickness of a translucent tubular object by irradiating the surface of the translucent tubular object such as a glass tube with laser light and receiving reflected light from the surface of the translucent tubular object. The present invention relates to a thickness measuring device for a translucent tubular object.

  Conventionally, in order to inspect whether or not the thickness of a translucent object such as a glass product is manufactured according to a standard, the thickness of the translucent object is measured. Since such measurement does not damage the surface of the translucent object, it is often performed in a non-contact manner. For example, as described in Patent Document 1 below, the measurement method is performed on the surface of the translucent object. On the other hand, there is a method of irradiating laser light obliquely, receiving reflected light reflected on the front surface and the back surface by a light receiving sensor, and determining the thickness of the translucent object from the difference between the light receiving positions. This method can be applied even if the translucent object is a tubular object such as a glass tube. For example, in Patent Document 2 below, the thickness of the tubular object is set by the method described in Patent Document 1. An apparatus for measuring is described. However, this method needs to be adjusted so that the light-transmitting object is irradiated with the laser beam at the set irradiation angle. If the adjustment accuracy is poor, there is a problem that the measurement accuracy is deteriorated.

  On the other hand, if the method is to measure the thickness of the translucent object by irradiating the translucent object with the laser beam perpendicularly, it returns in the same optical path as the laser beam irradiated with the reflected light. Since adjustment may be performed so that light is received at a predetermined location, the adjustment accuracy is good. As this method, as described in Patent Document 3, for example, a laser beam of a wide wavelength band such as a super luminescent diode light source (SLD light source) interferes with light reflected at different locations, and is diffracted. There is a method of obtaining the displacement by spectroscopically separating each wavelength with a grating or the like. That is, irradiate a translucent object with laser light in a wide wavelength band, cause reflected light on the front and back surfaces of the translucent object to interfere with each other, and separate each wavelength with a diffraction grating and receive it with an image sensor such as a CCD. The light intensity for each light receiving position is acquired. The light intensity at each light receiving position (that is, the light receiving curve) differs depending on the way in which the reflected light interferes, and therefore varies depending on the distance (that is, the thickness) between the front surface and the back surface of the translucent object. Therefore, the thickness of the translucent object is obtained by analyzing the light receiving curve. In this method, even if the translucent object is a tubular object such as a glass tube, the laser beam is irradiated with the reflected light by irradiating the laser beam so as to intersect the central axis of the translucent object perpendicularly. It can be applied because it only needs to be returned in the same optical path.

JP 2009-222428 A JP 09-504875 A JP 2010-121977 A

  When the translucent object is a tubular object, in order to irradiate the laser beam perpendicularly to the central axis over the entire area of the translucent object, the setting mechanism is set so that the central axis of the tubular object is at a set position. And the laser beam may be moved relative to the tubular object along the set path. However, if the center axis of the tubular object is randomly deviated from the straight line, the laser beam optical axis always intersects the center axis of the tubular object perpendicularly only by moving the laser beam along the set path. There is a problem that there is a portion where the thickness cannot be measured because the reflected light cannot be received by the light receiver.

  In addition, when the thickness of the entire area of the tubular object is measured while rotating the tubular object, and the diameter of the tubular object is small, the tubular object is rotated so that the central axis of the tubular object is always at the set position. In this case as well, simply moving the laser beam along the set path does not always allow the optical axis of the laser beam to intersect the central axis of the tubular object perpendicularly. There is a problem that there are places that cannot be measured. Also, when the tubular object cannot be set in the setting mechanism for some reason (for example, the tubular object is hot or avoids foreign matter adhering to the tubular object), and only the one end of the tubular object is gripped. The center axis of the tubular object cannot always be set to the set position, and the laser beam always intersects the center axis of the tubular object perpendicularly only by moving the laser beam along the set path. There is a problem that there is a portion where the thickness cannot be measured.

  The present invention has been made to cope with the above-described problems, and its purpose is to irradiate a translucent tubular object with laser light so that the laser beam perpendicularly intersects the central axis of the translucent tubular object. When measuring the thickness of the entire area of the translucent tubular object by moving the laser light relative to the translucent tubular object in the direction of the central axis, the central axis of the translucent tubular object is shifted from a predetermined position. Even when there is a spot, the reflected light can always be returned to the predetermined position (the optical receiver for analysis), and the thickness of the entire area of the translucent tubular object can be measured in a short time. An object of the present invention is to provide a thickness measuring device for a translucent tubular object. In addition, in the description of each constituent element of the present invention below, in order to facilitate understanding of the present invention, reference numerals of corresponding portions of the embodiment are described in parentheses, but each constituent element of the present invention is The present invention should not be construed as being limited to the configurations of the corresponding portions indicated by the reference numerals of the embodiments.

  In order to achieve the above-described object, the present invention provides a translucent tubular object support device that supports a translucent tubular object (G) by extending a central axis in a predetermined first axial direction (X-axis direction). 10, 15), laser light irradiation means (30, 31, 40, 57) for irradiating the transparent tubular object with laser light from the second axial direction (Z-axis direction) perpendicular to the first axial direction, A light receiving means (35, 36) for receiving the reflected light of the laser light reflected by the outer peripheral surface of the optical tubular object and the reflected light of the laser light reflected by the inner peripheral surface of the translucent tubular object; Thickness detection means (117) for detecting the thickness of the translucent tubular object at the position irradiated with the laser light from the signal corresponding to the light receiving state of the received reflected light, and the laser irradiated by the laser light irradiation means The irradiation position of the light on the translucent tubular object is moved in the first axis direction. In the apparatus for measuring a thickness of a translucent tubular object provided with a laser beam irradiation position moving means (11, 12, 13), the position of the laser beam irradiated to the translucent tubular object is determined in the first axial direction and the first direction. Third axial position changing means (54, 55, 25) for changing to a third axial direction orthogonal to both of the two axial directions, and a translucent tubular object of the laser light irradiated to the translucent tubular object Third-axis-around angle changing means (52, 53) for changing the angle around the third axis with respect to the central axis, and a part of the reflected light from the light-transmitting tubular object is divided and incident, and the light-transmitting tubular Third axis direction positional deviation amount detection means (51, 60, 118) for detecting a deviation amount of the third axial direction position with respect to the central axis of the translucent tubular object in the irradiation direction of the laser beam on the object; A part of the reflected light from the tubular object is split and incident, Third-axis angle deviation detecting means (51, 51) for detecting the deviation amount of the angle around the third axis with respect to the perpendicular line around the third axis of the central axis of the translucent tubular object in the irradiation direction of the laser light with respect to the conductive tubular object 60, 121) and the displacement amount of the third axial position detected by the third axial displacement detection means, the optical axis of the laser light applied to the translucent tubular object is the translucent tubular. The third axial position servo control means (119, 120) that servo-controls the third axial position changing means so as to coincide with the center axis position of the object, and the third axial angle deviation detecting means detected by the third axis position detecting means. Using the amount of deviation of the angle around the three axes, the third-axis angle changing means is servoed so that the optical axis of the laser light applied to the translucent tubular object is perpendicular to the central axis of the translucent tubular object. Control angle angle around third axis The control unit (122, 123) is provided, and the laser beam irradiation unit includes an objective lens that condenses the laser beam. From the focal length Fx in the first axis direction of the objective lens and the third axis angle change unit The relationship between the optical distance a to the objective lens and the optical distance b from the objective lens to the surface of the translucent tubular object is (1 / a) + (1 / b) = 1 / Fx. As described above, the objective lens and the third axis rotation angle changing means are arranged.

  In this case, the third axial direction position changing means is interposed in the laser beam irradiation path for the translucent tubular object, and rotates around the first axis to change the irradiation position of the laser light to the translucent tubular object. It is good to comprise with the rotation optical component (54, 55) changed to a 3rd axis direction. The third axial direction position changing means is a third axial direction actuator that moves the laser light irradiating means in the third axial direction to change the irradiation position of the laser light on the translucent tubular object in the third axial direction. (25) may be used. The third axis-around angle changing means may be constituted by a rotating optical component (52, 53) that is interposed in a laser beam irradiation path with respect to the translucent tubular object and rotates around the third axis.

  In the present invention configured as described above, the third axial position servo control means uses the third axial position deviation amount detected by the third axial position deviation amount detection means, and uses the translucent tubular shape. The third axial direction position changing means is servo-controlled so that the optical axis of the laser light applied to the object coincides with the center axis position of the translucent tubular object. Further, the third axis angle servo control means uses the amount of deviation of the third axis angle detected by the third axis angle deviation detection means to use the light of the laser light irradiated to the translucent tubular object. Servo-controlling the angle changing means around the third axis so that the axis is perpendicular to the central axis of the translucent tubular object. As a result, even when the central axis of the translucent tubular object is deviated from the set position, the optical axis of the laser light can always be perpendicularly intersected with the central axis of the translucent tubular object, thereby measuring the thickness. It is possible to prevent a portion that cannot be generated. Further, the focal length Fx of the objective lens in the first axis direction, the optical distance a from the third axis rotation angle changing means to the objective lens, and the optical distance b from the objective lens to the surface of the translucent tubular object, The objective lens and the third axis angle changing means are arranged so that the relationship of (1 / a) + (1 / b) = 1 / Fx. Thereby, even if servo control of the angle around the third axis is performed, the optical axis of the objective lens is set so that the irradiation position of the laser beam on the translucent tubular object in the first axis direction is not changed. Therefore, it is possible to obtain a measurement result at a set position with high accuracy. Further, the servo does not become unstable due to the degree of inclination of the translucent tubular object around the second axis.

  Another feature of the present invention is that, as described above, the third axial position changing means is interposed in the laser light irradiation path with respect to the translucent tubular object, and rotates around the first axis. Rotating optical component that is configured by a rotating optical component that changes the irradiation position of the laser light on the translucent tubular object in the third axis direction, and the focal length Fy of the objective lens in the third axis direction rotates around the first axis The rotating optical component is arranged so as to be equal to the optical distance c from the lens to the objective lens.

  According to this, even if the rotation optical component that changes the irradiation position of the laser light on the translucent tubular object in the third axis direction is rotated around the first axis and the servo control of the third axis direction position is performed, Since the optical axis of the laser beam is always parallel to the second axis direction, even if the position of the translucent tubular object changes slightly in the second axis direction, the reflected light with respect to the third axial position of the translucent tubular object There is almost no change in the relationship between the light receiving positions, and stable servo control of the position in the third axial direction can be performed.

It is a whole block diagram of the thickness measuring apparatus of the translucent tubular object which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the spectroscopy unit of FIG. 1 in detail. It is a block diagram which shows in detail the structure of the optical head of FIG. 1 seen from the X-axis direction. It is a block diagram which shows in detail the structure of the optical head seen along CC line of FIG. 2B. (a) is explanatory drawing for demonstrating the focal distance of the X-axis direction of an objective lens (toroidal lens), (b) is description for demonstrating the focal distance of the Y-axis direction of an objective lens (toroidal lens). FIG. It is a figure which shows the displacement of the Y-axis direction of a glass tube, and the light-receiving state of the reflected light in the 4-part photodetector of an optical head. It is a figure which shows the change of the inclination around the Y-axis of a glass tube, and the light reception state of the reflected light in the 4-part photodetector of an optical head. FIG. 2 is a flowchart showing a first half of a thickness measurement program executed by the controller of FIG. It is a flowchart which shows the latter half part of the said thickness measurement program. It is a whole block diagram of the thickness measuring apparatus of the translucent tubular object which concerns on the modification of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of a translucent tubular object thickness measuring apparatus according to an embodiment of the present invention. This thickness measurement apparatus irradiates a transparent tubular object with a laser beam to the thickness of a transparent tubular object such as a glass tube, and receives reflected light from the transparent tubular object. Measure. In this embodiment, the translucent tubular object is a thin glass tube G. The thickness measuring device includes a work driving device 10 that holds and moves the glass tube G, an optical head 100B that measures the thickness of the glass tube G in cooperation with the spectroscopic unit 100A, a work driving device 10 and A support device 20 that supports the optical head 100B is provided.

  The support device 20 is integrally formed in an L shape including a horizontal portion 20a and a vertical portion 20b. An X-axis direction feed motor 11 is assembled on the left end side of the horizontal portion 20a in the figure. The X-axis direction feed motor 11 connects the output rotation shaft to the lower end of the screw rod 12 extending in the X-axis direction (vertical direction in the drawing), and rotates the screw rod 12 around the X-axis by rotation. The Y-axis direction is the direction perpendicular to the paper surface, and the Z-axis direction is the left-right direction of the drawing. The upper end of the screw rod 12 is rotatably supported by a protruding portion that protrudes at the upper end of the vertical portion 20b. A moving body 13 is screwed to the screw rod 12 via a nut. The moving body 13 is restricted from rotating with respect to the screw rod 12, and moves in the axial direction of the screw rod 12 by the rotation of the screw rod 12. In other words, the moving body 13 constitutes a screw feed mechanism in combination with the screw rod 12.

An encoder 11 a is incorporated in the X-axis direction feed motor 11. The encoder 11a outputs pulse train signals Φ _A and Φ _B whose output is alternately switched between a high level and a low level each time the X-axis direction feed motor 11 rotates by a predetermined minute rotation angle. Note that the pulse train signals Φ _A and Φ _B are signals that are out of phase with each other by π / 2, and the rotational direction of the X-axis direction feed motor 11 is determined by this phase difference. The pulse train signals Φ _A and Φ _B output from the encoder 11 a are input to the X-axis direction feed motor control circuit 110 and the movement position detection circuit 111. The movement position detection circuit 111 starts to operate in response to an instruction from the controller 200, which will be described later. After the operation starts, when the pulse train signals Φ _A and Φ _B output from the encoder 11a are not input, a signal indicating the movement limit position is displayed as X. Output to the axial direction feed motor control circuit 110 and set the count value to “0”. Thereafter, the number of pulses of the pulse train signals Φ _A and Φ _B output from the encoder 11 a is counted according to the rotational direction of the X-axis direction feed motor 11. Count up or down. Then, the moving position of the moving body 13 is calculated from the accumulated count number and output to the controller 200 and the X-axis direction feed motor control circuit 110. The movement limit position where the count value is “0” is the origin position for controlling the movement position of the moving body 13 (the upper movement limit position in this embodiment).

  The X-axis direction feed motor control circuit 110 starts to operate in response to an instruction from the controller 200, and inputs a movement position output from the movement position detection circuit 111 at predetermined time intervals when a set value of the movement position is input from the controller 200. The moving body 13 is moved by driving the X-axis direction feed motor control circuit 110 until the input movement position reaches the set value input from the controller 200. When a set value of the movement position is input immediately after the start of operation, the X-axis direction feed motor 11 is driven to move the moving body 13 in the movement limit position direction, and the movement limit detection circuit 111 represents the movement limit position. When the signal is input, the output of the drive signal to the X-axis direction feed motor 11 is stopped. Thereafter, the moving body 13 is moved by driving the X-axis direction feed motor 11 until the movement position output from the movement position detection circuit 111 reaches the set value of the movement position input from the controller 200.

Also, the controller 200 inputs a set value (set speed) of the moving speed of the moving body 13 to the X-axis direction feed motor control circuit 110. When a movement start instruction is input from the controller 200, the movement of the moving body 13 is determined from the number of pulses per unit time including the rotation direction of the X-axis direction feed motor 11 of the pulse train signals Φ _A and Φ _B output from the encoder 11a. The moving speed including the direction is calculated, and the X-axis direction feed motor 11 is driven and controlled so that the calculated moving speed becomes the set speed.

  A spindle motor 14 is assembled to the moving body 13. A fixing tool 15 for fixing one end (upper end) of the glass tube G is assembled to the tip of the output rotation shaft of the spindle motor 14. Therefore, by rotating the spindle motor 14 with the glass tube G fixed to the fixture 15, the glass tube G rotates around the axis.

An encoder 14 a is incorporated in the spindle motor 14. As in the case of the X-axis direction feed motor 11, the encoder 14a outputs pulse train signals Φ _A and Φ _B including information on the rotation direction of the spindle motor 14. The encoder 14a also outputs an index signal Index for each reference rotational position. The pulse train signals Φ _A and Φ _B output from the encoder 14 a are input to the spindle motor control circuit 112. The spindle motor control circuit 112 starts to operate in response to an instruction from the controller 200, calculates the rotation speed of the spindle motor 14 from the number of pulses per unit time of the pulse train signals Φ _A and Φ _B output from the encoder 14a, and calculates The rotation of the spindle motor 14 is controlled so that the rotation speed becomes equal to the rotation speed set by the controller 200.

The pulse train signals Φ _A and Φ _B and the index signal Index output from the encoder 14 a are input to the rotation angle detection circuit 113. The rotation angle detection circuit 113 resets the count value to “0” when the index signal Index arrives, increases the count value every time the pulse train signal Φ _A or Φ _B arrives, and sets the count value to the rotation angle of the spindle motor 14. Is output to the controller 200 as a signal representing.

  A Z-axis direction feed motor 21 is assembled to the right end portion of the horizontal portion 20a of the support device 20 in the figure. The Z-axis direction feed motor 21 connects its output rotation shaft to the right end of a screw rod 22 extending in the Z-axis direction, and rotates the screw rod 22 around the Z-axis by rotation. The left end of the screw rod 22 is rotatably supported by a protruding portion that protrudes from the upper surface of the horizontal portion 20a. A table 23 is screwed to the screw rod 22 via a nut. The table 23 is restricted from rotating with respect to the screw rod 22, and moves in the axial direction of the screw rod 22 by the rotation of the screw rod 22. In other words, the table 23 constitutes a screw feed mechanism in combination with the screw rod 22.

An encoder 21 a is incorporated in the Z-axis direction feed motor 21. This encoder 21a also outputs the same pulse train signals Φ _A and Φ _B as those of the X-axis direction feed motor 11. The pulse train signals Φ _A and Φ _B output from the encoder 21 a are input to the movement position detection circuit 115. The movement position detection circuit 115 starts to operate in response to an instruction from the controller 200. After the operation starts, when the pulse train signals Φ _A and Φ _B output from the encoder 21a are not input, a signal indicating the movement limit position is transmitted in the Z-axis direction. Output to the feed motor control circuit 114, the count value is set to “0”, and thereafter, the number of pulses of the pulse train signals Φ _A and Φ _B output from the encoder 21a is counted up according to the rotation direction of the Z-axis direction feed motor 21 or Count down. Then, the movement position of the table 23 is calculated from the accumulated count number and is output to the controller 200 and the Z-axis direction feed motor control circuit 114. The movement limit position where the count value is “0” is the origin position for controlling the movement position of the table 23 (the right movement limit position in the present embodiment).

  The Z-axis direction feed motor control circuit 114 starts to operate in response to an instruction from the controller 200, and when the set value of the movement position is input from the controller 200, the movement position output from the movement position detection circuit 115 is input at a predetermined time interval. The table 23 is moved by driving the Z-axis direction feed motor 21 until the input movement position becomes the set value input from the controller 200. When a set value of the movement position is input immediately after the start of operation, the Z-axis direction feed motor 21 is driven to move the table 23 in the movement limit position direction, and a signal indicating the movement limit position is sent from the movement position detection circuit 115. Is input, the output of the drive signal to the X-axis direction feed motor 21 is stopped. Thereafter, the Z-axis direction feed motor 21 is driven to move the table 23 until the movement position output from the movement position detection circuit 115 reaches the set value of the movement position input from the controller 200.

  As shown in detail in FIG. 2A, the spectroscopic unit 100 </ b> A includes a super luminescent diode light source 30 (hereinafter referred to as an SLD (Super Luminescent Diode) light source 30) that emits laser light in a wide wavelength band. The laser light emitted from the SLD light source 30 is converted into parallel light by the collimator lens 31, the cross-sectional diameter is reduced by the relay lenses 32 and 33, and the light is guided to the polarization beam splitter 34. The polarization beam splitter 34 transmits the incident light from the relay lenses 32 and 33 as it is, and guides it to the optical head 100 </ b> B via the optical fiber 40. A laser drive circuit 116 is connected to the SLD light source 30. The laser drive circuit 116 is instructed by the controller 200 to drive and control the SLD light source 30. Note that the light amount of the SLD light source 30 is actually feedback controlled, but this feedback control is not shown.

  The laser light guided from the optical head 100B to the polarization beam splitter 34 via the optical fiber 40 is reflected by the polarization beam splitter 34, guided to the reflective diffraction grating 35, and dispersed into a series of spectrums. Guided to sensor 36. The line sensor 36 is formed by a CCD, a CMOS, or the like. Note that a translucent diffraction grating may be used in place of the reflective diffraction grating 35, and the reflected light from the polarization beam splitter 34 may be guided to the line sensor 36 via the translucent diffraction grating.

  A data processing device 117 is connected to the line sensor 36. In response to an instruction from the controller 200, the data processing device 117 performs A / D conversion on a signal output from each pixel of the line sensor 36 at a set frequency into digital size data representing the signal size, and performs A / D conversion. The D-converted magnitude data is stored in correspondence with the pixel position. Then, the data processor 117 calculates the thickness of the glass tube G by processing the stored size data (that is, the light reception curve), and outputs the thickness data representing the calculated thickness to the controller 200. Repeat that.

  The calculation of the thickness of the glass tube G will be briefly described. Laser light applied to the glass tube G by an objective lens 57 to be described later is reflected on both the front and back surfaces of the glass tube G, and the reflected light on both surfaces interfere with each other. In this case, the laser light emitted from the SLD light source 30 and guided to the glass tube G is laser light in a wide wavelength band (that is, laser light including components having different wavelengths), and the interference occurs between laser lights having the same wavelength. The intensity of the laser beam for each wavelength due to this interference depends on the thickness of the glass tube G. The numerical aperture (NA) of the objective lens 57 is small, specifically 0.2 or less (for example, 0.05) in both the X-axis direction and the Y-axis direction, and the focal depth is equal to or greater than the thickness of the glass tube G. It is. Therefore, the reflected light of the laser light on the front and back surfaces of the glass tube G returns to the original optical path and interferes.

  On the other hand, the diffraction grating 35 varies the way of diffraction depending on the wavelength of the incident laser light, so that the light receiving position of the line sensor 36 and the wavelength of the laser light have a corresponding relationship. That is, since the diffraction grating 35 changes the reflection angle of the laser light having different intensities due to the interference depending on the thickness of the glass tube G, the relationship between the position of the line sensor 36 and the received light intensity is determined. The light receiving curve to be represented is related to the thickness of the glass tube G. As a result, if the thickness of the glass tube G is different, the light intensity for each wavelength as a result of the interference is different, so the light reception curve by the line sensor 36 is also different, and the thickness of the glass tube G is determined by analyzing the light reception curve. Can be calculated. Accordingly, thickness data representing the thickness of the glass tube G is supplied from the data processing device 117 to the controller 200. When the thickness of the glass tube G cannot be calculated from the light receiving curve, data representing “measurement impossible” is supplied from the data processing device 117 to the controller 200.

  The optical head 100B is fixed to the table 23, and is shown in FIG. 1 by a conceptual diagram that covers all components in a plane. 2B and 2C show the optical head 100B in detail. FIG. 2B is a view of the optical head 100B as seen from the central axis direction (X-axis direction) of the glass tube G. FIG. It is the figure which looked at the optical head 100B along CC line of FIG. 2B (from the Z-axis direction). In FIG. 2B, parts that overlap in the viewed direction are omitted as appropriate for easy understanding. Specifically, in FIG. 2B, the beam splitter 51 and parts on the optical path of the laser light reflected by the beam splitter 51 are omitted.

  The optical head 100 </ b> B has a beam splitter 51 that receives the laser light propagated by the optical fiber 40. The beam splitter 51 transmits the incident laser light and guides it to the galvanometer mirror 52. The galvanometer mirror 52 is rotationally driven by a motor 53 around a straight line parallel to the Y axis. The Y-axis in this case is a case where the Y-axis is viewed from the coordinate axis after reflection by the galvano mirror 54 described later, and the same applies to the Y-axis in the case where the rotational drive of the galvano mirror 52 is described below. The laser beam reflected by the galvanometer mirror 52 is guided to the galvanometer mirror 54. The galvanometer mirror 54 is rotationally driven by a motor 55 around a straight line parallel to the X axis. The laser beam guided to the galvanometer mirror 54 is reflected by the galvanometer mirror 54 and irradiated onto the surface of the glass tube G through the quarter-wave plate 56 and the objective lens 57. Since the laser light incident on the objective lens 57 is guided by the relay lenses 32 and 33 with the cross-sectional diameter being reduced and guided through the optical fiber 40, the light beam diameter is small.

  The objective lens 57 is composed of a toroidal lens having different focal lengths in the Y-axis direction and the X-axis direction. In this case, the focal length in the Y-axis direction is from the center position of the objective lens 57 on the optical axis (Z-axis direction) to the position where the laser light incident in parallel to the optical axis is condensed in the Y-axis direction. Is the distance. The focal length in the X-axis direction is the distance from the center position of the objective lens 57 on the optical axis to the position where laser light incident parallel to the optical axis is condensed in the X-axis direction. As shown in FIG. 3A, the focal length Fy in the Y-axis direction is equal to the optical distance c from the reflection point of the galvano mirror 54 that changes the angle around the X-axis to the objective lens 57, that is, Fy = c. Is set to The optical distance is the total distance traveled by the laser light. Thereby, even if the galvano mirror 54 rotates around the X axis, the laser light incident on the objective lens 57 becomes laser light parallel to the Z axis direction when viewed on the YZ plane. Further, as shown in FIG. 3B, the focal length Fx in the X-axis direction is defined as “a” as the optical distance from the reflection point of the galvano mirror 52 that changes the angle around the Y-axis to the objective lens 57. If the optical distance from 57 to the surface of the glass tube G is b, it is set so as to satisfy the relationship of (1 / a) + (1 / b) = 1 / Fx. This relationship is a relationship in which the surface of the glass tube G becomes an image point when the reflection point of the galvano mirror 52 that changes the angle around the Y axis is an object point. As a result, the laser light incident on the objective lens 57 is one point where the optical axis of the objective lens 57 intersects the surface of the glass tube G when viewed in the XZ plane even when the galvanometer mirror 52 rotates around the Y axis. It becomes the laser beam which goes to. Further, as described above, the numerical aperture (NA) of the objective lens 57 is set to a small value of 0.2 or less (for example, 0.05) in both the X-axis direction and the Y-axis direction, and the focal depth of the objective lens 57 is set. Long and long focal length. In FIG. 3, the quarter wavelength plate 56 is omitted.

  The reflected light from the glass tube G of the laser light is incident on the galvanometer mirror 54 through the objective lens 57 and the quarter wavelength plate 56 in an optical path substantially equal to the optical path of the laser light irradiated on the glass tube G, and the galvanometer mirror. The light is reflected by 54 and guided to the galvanometer mirror 52. The laser beam guided to the galvanometer mirror 52 is reflected by the galvanometer mirror 52 and guided to the beam splitter 51. A part of the laser light reflected by the galvanometer mirror 52 and incident on the beam splitter 51 is transmitted through the beam splitter 51, guided into the optical fiber 40, and guided to the spectroscopic unit 100A via the optical fiber 40 for thickness measurement. Used. A part of the laser light reflected by the galvanometer mirror 52 and incident on the beam splitter 51 is reflected by the beam splitter 51 and used for servo control.

  The laser beam reflected by the beam splitter 51 is increased in cross-sectional diameter by the relay lenses 58 and 59 and set to an appropriate diameter, and is received by the four-divided photodetector 60. As shown in FIGS. 4A and 4B, the quadrant photodetector 60 includes four light receiving elements whose light receiving areas are divided into four parts in the vertical and horizontal directions on the XY plane, and are incident on the light receiving areas A, B, C, and D. Detection signals proportional to the intensity of the laser beam are output as received light signals a, b, c, and d, respectively.

  FIG. 4A is a diagram illustrating the displacement of the glass tube G in the Y-axis direction and the light reception state of the reflected light in the quadrant photodetector 60 of the optical head 100B. In addition, the glass tube G is the figure seen from the X-axis direction, and the 4 division | segmentation photodetector 60 is the figure seen from the Z-axis direction. If the glass tube G is in the neutral position in the Y-axis direction, the laser beam is irradiated on the center position in the Y-axis direction on the surface of the glass tube G and formed on the four-divided photodetector 60 as shown in FIG. The light spot is located at least in the center in the horizontal direction of the figure in the four-divided region of the four-divided photodetector 60. At least the sum (a + b) of the light reception signals a and b is equal to the sum (c + d) of the light reception signals c and d. On the other hand, when the glass tube G is displaced from the neutral position in the Y-axis direction, the laser light is displaced in the Y-axis direction from the center position in the Y-axis direction on the surface of the glass tube G as shown in FIGS. 3A4 (a) (c). Referred to as the position. Then, as shown in FIGS. 4A (a) and 4 (c), the light spot formed on the quadrant photodetector 60 is shifted from the center position in the horizontal direction in the figure, and the sum (a + b) of the light reception signals a and b is received. The sum (c + d) of the signals c and d is greater, or the sum (c + d) of the light reception signals c and d is greater than the sum (a + b) of the light reception signals a and b.

  FIG. 4B is a diagram showing a change in the inclination of the glass tube G around the Y axis and the light reception state of the reflected light in the quadrant photodetector 60 of the optical head 100B. In addition, the glass tube G is the figure seen from the Y-axis direction, and the 4 division | segmentation photodetector 60 is the figure seen from the Z-axis direction. If the glass tube G is in a neutral position around the Y axis, that is, if the glass tube G is parallel to the X axis direction, the laser beam is perpendicular to the extending direction of the glass tube G as shown in FIG. And is reflected vertically. Then, as shown in FIG. 4B (b), the light spot formed on the four-divided photodetector 60 is positioned at least in the center in the vertical direction in the figure in the four-divided region of the four-divided photodetector 60, and at least the light reception signals a and d. The sum (a + d) is equal to the sum (b + c) of the received light signals b and c. On the other hand, when the glass tube G is tilted around the Y-axis direction from the neutral position, as shown in FIGS. 4B (a) and 4 (c), the laser light is tilted with respect to the extending direction of the glass tube G, and Reflected in the opposite direction. Then, as shown in FIGS. 4B (a) and 4 (c), the light spot formed on the quadrant photodetector 60 is shifted from the center position in the vertical direction in the figure, and the sum (b + c) of the light reception signals b and c is received. The sum of the signals a and d (a + d) is greater, or the sum of the received light signals a and d (a + d) is greater than the sum of the received light signals b and c (b + c).

  The light reception signals a, b, c, and d output from the quadrant photodetector 60 are input to the Y-axis direction error signal generation circuit 118 and the Y-axis rotation angle error signal generation circuit 121. The Y-axis direction error signal generation circuit 118 amplifies the light reception signals a, b, c, and d, and then generates a Y-axis direction error signal (a + b) − (c + d) by calculation. This Y-axis direction error signal (a + b)-(c + d) represents the amount of deviation from the neutral position in the Y-axis direction at the measurement location of the glass tube G (see FIGS. 4A (a) to (c)). The Y-axis direction error signal (a + b) − (c + d) is supplied to the Y-axis direction servo circuit 119. The Y-axis direction servo circuit 119 generates a Y-axis direction servo signal so that the Y-axis direction error signal (a + b) − (c + d) becomes “0”, and outputs it to the Y-axis direction drive circuit 120. The Y-axis direction drive circuit 120 servo-controls the motor 55 based on the Y-axis direction servo signal to rotate the galvano mirror 54 around the X axis. Accordingly, the galvanometer mirror 54 is controlled to rotate around the X axis so that the Y-axis direction error signal (a + b) − (c + d) becomes “0”. Thereby, the irradiation position of the laser beam on the glass tube G is servo-controlled in the Y-axis direction. The servo control in the Y-axis direction can be regarded as servo control of the angle around the X axis because the galvano mirror 54 is driven to rotate around the X axis by the motor 55.

  The Y-axis angle error signal generation circuit 121 amplifies the light reception signals a, b, c, and d, and then generates a Y-axis angle error signal (a + d) − (b + c) by calculation. The Y-axis angle error signal (a + d) − (b + c) represents the amount of deviation (shift angle) from the neutral position around the Y-axis of the glass tube G (see FIGS. 4B (a) to (c)). . The Y-axis angle error signal (a + d) − (b + c) is supplied to the Y-axis angle servo circuit 122. The Y-axis rotation angle servo circuit 122 generates a Y-axis rotation angle servo signal so that the Y-axis rotation angle error signal (a + d) − (b + c) becomes “0”, and sends it to the Y-axis rotation angle drive circuit 123. Output. The Y-axis rotation angle drive circuit 123 servo-controls the motor 53 based on the Y-axis rotation angle servo signal to rotate the galvanometer mirror 52 about the Y axis. Accordingly, the galvanometer mirror 52 is controlled to rotate about the Y axis so that the Y axis angle error signal (a + d) − (b + c) becomes “0”. Thereby, the irradiation direction of the laser beam to the glass tube G is servo-controlled around the Y axis. By such Y-axis direction servo control and Y-axis rotation angle servo control, the laser light is irradiated perpendicularly to the central axis of the glass tube G.

  Here, as described above, the peculiarity of servo control due to the objective lens 57 being composed of a toroidal lens will be described. As described above, the focal length Fy of the objective lens 57 in the Y-axis direction is equal to the optical distance c from the reflection point of the galvano mirror 54 that changes the angle around the X-axis to the objective lens 57, that is, Fy = c. The laser light set and incident on the objective lens 57 becomes laser light parallel to the Z-axis direction when viewed in the YZ plane even when the galvano mirror 54 rotates around the X-axis (FIG. 3A )reference). Therefore, even if the surface position of the glass tube G slightly changes in the Z-axis direction, the glass tube G of the glass tube G when viewed from the optical axis position of the laser light by changing the optical axis position of the laser light in the Y-axis direction. Since the relationship of the reflection angle of the laser beam with respect to the position in the Y-axis direction does not change, the relationship between the position in the Y-axis direction of the glass tube G and the light receiving position in the quadrant photodetector 60 described later hardly changes. As a result, the amount by which the optical axis position of the laser beam is changed in the Y-axis direction so that the Y-axis direction error signal becomes “0” is almost the same even if the surface position of the glass tube G is slightly changed in the Z-axis direction. Therefore, stable Y-axis direction servo control (X-axis rotation angle servo control) can be performed.

  Further, as described above, the focal distance Fx in the X-axis direction is defined as “a” as the optical distance from the reflection point of the galvanometer mirror 52 that changes the angle around the Y-axis to the objective lens 57, and from the objective lens 57 to the glass tube G. If the optical distance to the surface is b, it is set so as to satisfy the relationship of (1 / a) + (1 / b) = 1 / Fx, and therefore the galvanometer mirror 52 that changes the angle around the Y axis. When the reflection point is an object point, the surface of the glass tube G becomes an image point (see FIG. 3B). Therefore, when viewed in the XZ plane, the laser light is directed to one point where the optical axis of the objective lens 57 intersects the surface of the glass tube G. Therefore, even if the galvano mirror 52 is rotated around the Y axis for Y-axis angle servo control, which will be described later, the laser beam is irradiated perpendicularly to the central axis of the glass tube G and the laser beam in the X-axis direction is irradiated. Since the irradiation position on the glass tube G does not change, the thickness of the position set with high accuracy can be measured, and the surface of the glass tube G can be measured regardless of the degree of inclination around the Z axis of the glass tube G. Since it can be regarded as a plane and angle servo control around the Y axis can be performed with high accuracy, stable servo control can be performed.

  In this case, the numerical aperture (NA) of the objective lens 57 is small, and as described above, specifically, it may be set to 0.2 or less in both the X-axis direction and the Y-axis direction. As a result, the focal depth is increased and the focal length of the laser light is increased, and the change in the light beam diameter of the laser light can be reduced so that the light beam diameter does not change. By doing so, as described above, stable Y-axis servo control (X-axis rotation angle servo control) can be performed even if the surface position of the glass tube G slightly changes in the Z-axis direction, and Y-axis angle servo control can be performed with high accuracy. If the numerical aperture (NA) is 0.2 or less, almost satisfactory results have been obtained by experiments, but preferably about 0.05. In FIG. 3, the quarter wavelength plate 56 is omitted.

  The translucent tubular object thickness measuring device also includes a controller 200, an input device 202, and a display device 204. The controller 200 is configured by a computer device having a large-capacity nonvolatile memory such as a CPU, ROM, RAM, timer, and hard disk, and controls various circuits by executing the thickness measurement program shown in FIGS. 4A and 4B. The thickness of the glass tube G is measured. The input device 202 includes a keyboard, and an operator inputs various information and gives an instruction to the operation of the controller 200. The display device 204 displays various information controlled by the controller 200.

  Next, the operation of the thickness measuring apparatus configured as described above will be described. First, the operator fixes the upper end of the glass tube G to the fixture 15 and operates the input device 202 to input the length of the glass tube G. Then, the operator operates the input device 202 to cause the controller 200 to execute the thickness measurement program of FIGS. 5A and 5B.

  The controller 200 starts the execution of the thickness measurement program in step S100 of FIG. 5A, and sets the variable n to “0” in step S102. This variable n defines the timing for taking in the thickness data from the data processing device 117, the rotation angle data from the rotation angle detection circuit 113, and the X-axis direction position data from the movement position detection circuit 111.

After the process of step S102, the controller 200 instructs the X-axis direction feed motor control circuit 110 to move the glass tube G to the measurement start position in step S104. Specifically, the X axis direction position where the X axis direction center position of the laser beam is irradiated to the measurement start point of the glass tube G is output to the X axis direction feed motor control circuit 110 as the measurement start position. The measurement start position can be obtained by calculating A−B + C from the following A, B, and C. A and C are stored in the controller 200 in advance.
A: When the glass tube G is fixed to the fixing tool 15 in a state where the X-axis direction position of the moving body 13 is at the origin position (that is, the upper movement limit position of the moving body 13), the glass in the fixing tool 15 X-axis direction distance B from the upper end position of the tube G to the X-axis direction center position of the laser beam: length of the glass tube G input using the input device 202 (B <A)
C: Distance from the lower tip position of the glass tube G to the measurement start point

  The X-axis direction feed motor control circuit 110 rotates the X-axis direction feed motor 11 to rotate the screw rod 12 around the axis to move the moving body 13 in the X-axis direction, and move the glass tube G in the X-axis direction. To move toward the measurement start position. During movement of the glass tube G in the X-axis direction, the X-axis direction feed motor control circuit 110 sends X-axis direction position data representing the X-axis direction position of the moving body 13 (that is, the glass tube G) from the movement position detection circuit 111. Is entered. When the input X-axis direction position data indicates the measurement start position input from the controller 200, the X-axis direction feed motor control circuit 110 stops the rotation of the X-axis direction feed motor 11, and the moving body 13 and The movement of the glass tube G in the X-axis direction is stopped.

  On the other hand, the controller 200 also inputs the X-axis direction position data from the movement position detection circuit 111 in step S106 after the process of step S104, and checks whether the input X-axis direction position data is equal to or greater than the measurement start position. judge. If the X-axis direction position data is not equal to or greater than the measurement start position, the controller 200 continues to determine “No” in step S106, and repeatedly executes the process of step S106. Then, when the X-axis direction position data is equal to or greater than the measurement start position, the controller 200 determines “Yes” in step S106, and proceeds to step S108.

  In step S108, the controller 200 instructs the Z-axis direction feed motor control circuit 114 to move the optical head 100B to the measurement setting position. Specifically, the Z-axis direction position at which the laser beam is focused on the outer peripheral surface of the glass tube G is output to the Z-axis direction feed motor control circuit 114 as the measurement setting position. The Z-axis direction feed motor control circuit 114 rotates the Z-axis direction feed motor 21 to rotate the screw rod 22 around the axis line to move the table 23 in the Z-axis direction, thereby moving the table 23 and the optical head 100B to Z. Move in the axial direction toward the set position for measurement. During the movement of the table 23 and the optical head 100B in the Z-axis direction, the Z-axis direction feed motor control circuit 114 moves from the movement position detection circuit 115 to the Z-axis direction position of the table 23 (that is, the optical head 100B). Position data is input. When the input Z-axis direction position data indicates the measurement setting position input from the controller 200, the Z-axis direction feed motor control circuit 114 stops the rotation of the Z-axis direction feed motor 21, and the table 23 and The movement of the optical head 100B in the Z-axis direction is stopped.

  On the other hand, after the processing of step S108, the controller 200 also inputs the Z-axis direction position data from the movement position detection circuit 115 in step S110, and whether the input Z-axis direction position data is equal to or greater than the set position for measurement. Determine. If the Z-axis direction position data is not equal to or greater than the measurement set position, the controller 200 continues to make a “No” determination at step S110 and repeatedly executes the process at step S110. Then, when the Z-axis direction position data is equal to or greater than the measurement setting position, the controller 200 determines “Yes” in step S110 and proceeds to step S112. In step S112, the controller 200 operates the laser driving circuit 116 to drive the SLD light source 30, thereby emitting laser light in a wide wavelength band that is used for both measurement and servo. In this case, feedback control regarding the intensity of the laser beam is omitted.

  The laser beam for measurement emitted from the SLD light source 30 is converted into parallel light by the collimator lens 31, the sectional diameter is reduced by the relay lenses 32 and 33, propagates through the optical fiber 40, and is transmitted from the spectroscopic unit 100 A to the optical head 100 B. Led to. In the optical head 100 </ b> B, the laser light propagated by the optical fiber 40 enters the galvanometer mirror 52 via the beam splitter 51. The galvanometer mirror 52 reflects this incident laser beam and makes it incident on the galvanometer mirror 54. The galvanometer mirror 54 reflects the incident laser light and makes it incident on the objective lens 57 via the quarter-wave plate 56. The objective lens 57 collects the incident laser light and irradiates the surface of the glass tube G with the laser light. Part of the laser light irradiated on the glass tube G is first reflected on the outer peripheral surface of the glass tube G and enters the objective lens 57. Further, a part of the laser light irradiated to the glass tube G enters the thick portion of the glass tube G, is reflected by the inner peripheral surface of the glass tube G, and passes through the thick portion of the glass tube G. 57 enters. Therefore, the laser light reflected on the outer peripheral surface of the glass tube G and the laser light reflected on the inner peripheral surface of the glass tube G interfere with each other and enter the objective lens 57. Therefore, the interference laser light having different intensities depending on the wavelength is incident on the objective lens 57 depending on the thickness of the glass tube G.

  The laser light incident on the objective lens 57 has its traveling direction changed and is guided to the galvanometer mirror 54 via the quarter-wave plate 56 in an optical path substantially equal to the optical path of the laser light irradiated to the glass tube G. The light is reflected by the galvanometer mirror 54 and enters the galvanometer mirror 52. The galvanometer mirror 52 reflects the incident laser beam and guides it to the beam splitter 51. The beam splitter 51 guides the measurement laser light to the spectroscopic unit 100A via the optical fiber 40. In the spectroscopic unit 100 </ b> A, the measurement laser light propagated by the optical fiber 40 is reflected by the polarization beam splitter 34 and is incident on the diffraction grating 35. The diffraction grating 35 makes the incident measurement laser light incident on the line sensor 36 with a reflection angle different depending on the wavelength.

  On the other hand, the beam splitter 51 reflects a part of the laser light incident from the galvanometer mirror 52, increases the cross-sectional diameter by the relay lenses 58 and 59, and then guides it to the quadrant photodetector 60 as servo laser light. The received light signals a, b, c, and d representing the received light amount of the servo laser light received by the four-divided photodetector 60 are supplied to the Y-axis direction error signal generation circuit 118 and the Y-axis rotation angle error signal generation circuit 121. The Y-axis direction error signal generation circuit 118 generates a Y-axis direction error signal (a + b) − (c + d). The Y-axis angle error signal generation circuit 121 generates a Y-axis angle error signal (a + d) − (b + c).

  After the process of step S112, the controller 200 instructs the Y-axis direction servo circuit 119 to start operation in step S114. In response to this, the Y-axis direction servo circuit 119 starts operation, and based on the Y-axis direction error signal (a + b) − (c + d) input from the Y-axis direction error signal generation circuit 118, the Y-axis direction servo circuit 119 A signal is generated and the motor 55 is driven and controlled via the Y-axis direction drive circuit 120 to servo-control the rotation of the galvano mirror 54 around a straight line parallel to the X-axis direction. Therefore, the rotation angle around the straight line parallel to the X-axis direction of the galvanometer mirror 54 is servoed so that the reflected light of the servo laser light received by the four-divided photodetector 60 is maintained at least in the center in the left-right direction of the light-receiving surface. Even if the glass tube G is displaced in the Y-axis direction, the galvanometer mirror 54 is rotationally controlled around a straight line parallel to the X-axis direction according to the displacement, and the optical axis of the laser light is changed to the glass tube G. It is maintained so as to intersect the central axis.

  Next, in step S116, the controller 200 instructs the Y-axis rotation angle servo circuit 122 to start operation. In response to this, the Y-axis rotation angle servo circuit 122 starts operation, and based on the Y-axis rotation angle error signal (a + d) − (b + c) input from the Y-axis rotation angle error signal generation circuit 121 An axis rotation angle servo signal is generated, and the motor 53 is driven and controlled via the Y axis rotation angle drive circuit 123 to servo-control the rotation of the galvano mirror 52 around a straight line parallel to the Y axis direction. Therefore, the rotation angle around the straight line parallel to the Y-axis direction of the galvanometer mirror 52 is servoed so that the reflected light of the servo laser light received by the four-divided photodetector 60 is maintained at least in the vertical center of the light receiving surface. Even if the glass tube G is tilted around the Y axis, the galvanometer mirror 52 is controlled to rotate around a straight line parallel to the Y axis direction according to the tilt angle, and the optical axis of the laser beam is adjusted to the glass tube G. To be perpendicular to the central axis of

  After the processing in step S116, the controller 200 instructs the data processing device 117 to start operation in step S118. In response to this, the data processing device 117 inputs a signal indicating the magnitude of the signal output from each pixel of the line sensor 36 at a set frequency, and the thickness of the glass tube G is based on the input signal. The thickness is calculated and thickness data representing the calculated thickness is output to the controller 200 at a predetermined cycle.

Next, in step S120, the controller 200 instructs the spindle motor control circuit 112 to start rotation around the axis of the glass tube G and also instructs the rotation speed. The spindle motor control circuit 112 uses the rotation speed of the spindle motor 14 calculated based on the pulse train signals Φ _A and Φ _B from the encoder 14a so that the glass tube G rotates at the instructed rotation speed. The motor 14 starts to rotate. As a result, the glass tube G starts to rotate around the axis at the instructed rotational speed. Next, in step S122, the controller 200 instructs the rotation angle detection circuit 113 to start operation. Thereby, the rotation angle detection circuit 113 starts to output rotation angle data representing the rotation angle of the spindle motor 14 (rotation angle around the axis of the glass tube G) to the controller 200.

After the process of step S122, the controller 200 instructs the X-axis direction feed motor control circuit 110 to start moving the glass tube G in the X-axis direction and also the moving speed in step S124. The X-axis direction feed motor control circuit 110 uses the rotation speed of the X-axis direction feed motor 11 calculated based on the pulse train signals Φ _A and Φ _B from the encoder 11a to move the glass tube G at the instructed moving speed. The X-axis direction feed motor 11 starts to rotate so as to move in the X-axis direction (downward in the figure). Thereby, the glass tube G starts to move in the X-axis direction at the instructed moving speed.

  Next, the controller 200 starts time measurement by a timer in step S130 of FIG. 5B. In step S132, the controller 200 determines whether the measurement time is equal to or greater than a multiplication result nT obtained by multiplying the predetermined short time T by the variable n. Now, since the variable n is “0”, the controller 200 determines “Yes” in step S132, and fetches the thickness data representing the thickness of the glass tube G from the data processing device 117 in step S134. The acquired thickness data is stored in the memory. Next, the controller 200 takes in the rotation angle data from the rotation angle detection circuit 113 in step S136, and takes in the X-axis direction position data from the movement position detection circuit 111 in step S138. The acquired rotation angle data and X-direction position data are stored in the memory in association with the thickness data.

  After the process of step S138, the controller 200 determines in step S140 whether the X-axis direction position represented by the captured X-axis direction position data indicates the measurement end position or more, that is, the length of the glass tube G. It is determined whether or not the glass tube G has already been moved beyond the measurement end position set. In step S142, the controller 200 determines whether or not a signal indicating “measurement impossible” is input from the data processing device 117. If the position in the X-axis direction does not indicate the measurement end position or more and a signal indicating “not measurable” is not input from the data processing device 117, the controller 200 determines “No” in steps S140 and S142. In step S144, “1” is added to the variable n, and the process returns to step S132. Then, every time the measurement has started is nT or more, the controller 200 repeatedly performs the processes of steps S134 to S144 described above. Thereby, in the memory, data representing the thickness of the glass tube G for each of the angle around the axis of the glass tube G represented by the rotation angle data and the axial position of the glass tube G represented by the X-direction position data. Will be remembered.

  Further, during the cyclic processing consisting of the steps S132 to S144, when the position in the X-axis direction indicates the measurement end position or more, or when a signal indicating “measurement impossible” is input from the data processing device 117, the controller 200 In S140 or step S142, it is determined as “Yes”, and the process proceeds to step S146 and subsequent steps.

  The controller 200 instructs the spindle motor control circuit 112 to stop the operation of the spindle motor 14 in step S146. As a result, the spindle motor control circuit 112 stops the rotation of the spindle motor 14 and stops the rotation around the axis of the glass tube G. Next, the controller 200 instructs the X-axis direction feed motor control circuit 110 to stop the operation of the X-axis direction feed motor 11 in step S148. Thereby, the X-axis direction feed motor control circuit 110 stops the rotation of the X-axis direction feed motor 11, and the movement of the glass tube G in the axial direction (X-axis direction) stops. Next, the controller 200 instructs the Y-axis direction servo circuit 119 to stop the operation in step S150, and instructs the Y-axis rotation angle servo circuit 122 to stop the operation in step S152. By these processes, the servo control of the rotation angle around the straight line parallel to the X-axis direction of the galvanometer mirror 54 (Y-axis direction servo control) and the servo control of the rotation angle around the axis parallel to the Y-axis direction of the galvano mirror 52 ( Y-axis angle servo control) is also stopped.

  After the process of step S152, the controller 200 instructs the laser drive circuit 116 to stop driving the SLD light source 30 in step S154. As a result, irradiation of the laser light onto the glass tube G by the SLD light source 30 is stopped. Next, the controller 200 instructs the rotation angle detection circuit 113 to stop operating in step S156, and instructs the data processing device 117 to stop operating in step S158. As a result, the rotation angle detection circuit 113 stops operating and angle data is not input to the controller 200, and the data processing device 117 also stops operating and thickness data is not input to the controller 200.

  After the process of step S158, the controller 200 instructs the X-axis direction feed motor control circuit 110 to move the movable body 13 to the X-axis direction drive limit position in step S160, and in step S162, the Z-axis direction feed motor. The control circuit 114 is instructed to move the table 23 to the drive limit value in the Z-axis direction. In response to these movement instructions, the X-axis direction feed motor control circuit 110 moves the movable body 13 to the X-axis direction drive limit position, and the Z-axis direction feed motor control circuit 114 moves the table 23 to the Z-axis direction drive limit value. . Thereby, since it will be in the same state as before the thickness measurement start of the glass tube G, the operator removes the glass tube G from the fixture 15, sets the glass tube G to be measured next, and repeats the above-described thickness measurement. It can be carried out. And the controller 200 displays the measurement result of the thickness of the glass tube G mentioned above in step S164 on the display apparatus 204, and complete | finishes execution of a thickness measurement program in step S166.

  As can be understood from the above description, according to the thickness measuring device for a transparent tubular object according to the above embodiment, the laser light emitted from the SLD light source 30 of the spectroscopic unit 100A is converted into parallel light by the collimator lens 31. The light is converted and guided to the optical head 100B via the optical fiber 40. In the optical head 100 </ b> B, the guided laser light is condensed on the surface of the glass tube G by the objective lens (toroidal lens) 57, and the reflected light from the glass tube G is spectrally dispersed through the optical head 100 </ b> B and the optical fiber 40. Returned to unit 100A. In the spectroscopic unit 100 </ b> A, the thickness of the glass tube G is measured by the data processing device 117 guided to the line sensor 36 through the diffraction grating 35 and connected to the line sensor 36.

  In this case, the four-divided photo detector 60 divides a part of the reflected light from the glass tube G via the beam splitter 51 and enters it. Then, the Y-axis direction error signal generation circuit 118 uses the amount of received light detected by the quadrant photodetector 60 to shift the amount of laser beam irradiated to the glass tube G in the Y-axis direction with respect to the central axis of the glass tube G. Is detected as a Y-axis direction error signal. Further, the Y-axis angle error signal generation circuit 121 uses the amount of received light detected by the four-divided photodetector 60 in the central axis of the glass tube G and the Y-axis direction of the laser light irradiated to the glass tube G. A deviation amount of the rotation angle around the Y axis with respect to the perpendicular perpendicular is detected as an angle error signal around the Y axis. The Y-axis direction servo circuit 119 and the Y-axis direction drive circuit 120 use the detected Y-axis direction error signal so that the laser beam applied to the glass tube G is applied to the central axis of the glass tube G. Servo-controls a motor 55 that rotationally drives the galvanometer mirror 54. Further, the Y-axis rotation angle servo circuit 122 and the Y-axis rotation angle drive circuit 123 use the detected Y-axis rotation angle error signal to cause the laser beam irradiated to the glass tube G to be the central axis of the glass tube G. Servo-controls a motor 53 that rotationally drives the galvanometer mirror 52 so as to irradiate vertically. Thereby, even when the central axis of the glass tube G is deviated from the set position, the optical axis of the laser light can always intersect the central axis of the glass tube G perpendicularly. As a result, according to the embodiment, the thickness of the entire area of the glass tube G can be accurately measured in a short time.

  In the above embodiment, the focal length Fx of the objective lens 57 in the X-axis direction, the optical distance a from the galvano mirror 52, which is a rotating optical component rotating around the Y-axis, to the objective lens 57, and the objective lens 57 The objective lens 56 and the galvanometer mirror 52 are arranged so that the relationship with the optical distance b from the surface of the glass tube G to the surface of the glass tube G is (1 / a) + (1 / b) = 1 / Fx. ing. That is, when the reflection point of the galvanometer mirror 52 that changes the angle around the Y axis is an object point, the surface of the glass tube G becomes an image point. Thereby, even if servo control of the angle around the Y axis is performed, the irradiation position of the laser beam on the glass tube G in the X axis direction can be fixed at one point so that the position set with high accuracy Measurement results can be obtained. Further, the servo does not become unstable due to the degree of inclination of the glass tube G around the Z axis.

  In the above embodiment, the focal length Fy of the objective lens 57 in the Y-axis direction is equal to the optical distance c from the galvanometer mirror 54, which is a rotating optical component rotating around the X-axis, to the objective lens 57. The objective lens 57 and the galvanometer mirror 54 are arranged. As a result, even if servo control around the X axis is performed, the optical axis of the laser light is always parallel to the Z axis direction, so that the glass tube G moves in the X axis direction while rotating. Even if the surface position slightly changes in the Z-axis direction, the relationship of the light receiving position of the reflected light with respect to the Y-axis direction position of the glass tube G hardly changes, and stable servo control around the X-axis line can be performed.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the object of the present invention.

  In the above embodiment, the focal length Fy in the Y-axis direction of the objective lens 57 composed of a toroidal lens is made equal to the optical distance c from the reflection point of the galvano mirror 54 to the objective lens 57, and the galvano mirror 54 rotates. However, the laser beam incident on the objective lens 57 is a laser parallel to the Z-axis direction when viewed in the YZ plane. However, if the focal length Fy of the objective lens 57 in the Y-axis direction and the optical distance c are approximated, the focal distance Fy and the optical distance c do not necessarily match, that is, a galvanometer mirror. When 54 rotates, the laser beam incident on the surface of the glass tube G may not be always parallel to the Z-axis direction and may slightly deviate from the Z-axis direction. In this case, as described above, even if the position of the surface of the glass tube G slightly changes in the Z-axis direction, the servo control in the Y-axis direction is hardly affected if the degree of change is small.

  In the above embodiment, the Y-axis direction servo and the Y-axis angle servo control are performed by driving the two galvanometer mirrors 52 and 54. However, instead of this, the Y-axis direction servo control by driving the galvano mirror 54 may be changed to servo control using an actuator that displaces the optical head 100B in the Y-axis direction. In this case, as shown in FIG. 6, the optical head 100B is assembled to the table 23 so as to be displaceable in the Y-axis direction, and a linear actuator 25 (for example, a linear actuator constituted by a piezoelectric actuator) is provided on the table 23. Thus, the optical head 100B may be displaced in the Y-axis direction. In this case, the linear actuator 25 is controlled by the Y-axis direction drive circuit 120, and the galvanometer mirror 54 and the motor 55 are omitted. In this case, since the optical axis of the laser light irradiated to the glass tube G is always parallel to the Z-axis direction, as described above, the glass tube G moves in the X-axis direction while rotating. Even if the surface position of the tube G is slightly changed in the Z-axis direction, the relationship between the light receiving position of the reflected light and the Y-axis direction position of the glass tube G is hardly changed, and stable servo control around the X-axis can be performed. .

  Further, in the above embodiment, the change in the optical axis position or the optical axis direction of the laser light is performed by driving the galvanometer mirrors 52 and 54, but what if the optical axis position or the optical axis direction of the laser light can be changed? A simple mirror may be used. For example, it may be a micro electro mechanical system mirror (MEMS mirror), a rising mirror whose angle of the reflecting surface can be changed by an actuator, or a polygon mirror. Further, the optical axis position of the laser beam may be changed by an AOD (acousto-optic deflector) or EOD (electro-optic polarizer) without using a mirror.

  Moreover, in the said embodiment, the method of calculating | requiring the thickness of the glass tube G from the light reception curve when irradiating the laser beam of a wide wavelength band to the glass tube G, and the reflected light from the glass tube G was disperse | distributed with the diffraction grating. Adopted. However, any other method can be adopted as long as the thickness of the glass tube G can be calculated using the reflected light generated when the laser light is irradiated perpendicularly to the central axis of the glass tube G. For example, the glass tube G is irradiated while changing the wavelength of the laser light at a high speed, the light intensity of the reflected light from the glass tube G with respect to the wavelength of the laser light is detected, and from the relationship between the wavelength and the light intensity, the glass tube G You may employ | adopt the method of calculating thickness.

  In addition, the laser beam that interferes only when the optical path length is the same with low coherency is divided by the beam splitter, one is irradiated to the glass tube G and reflected, the other is reflected by the reference mirror, and the reference mirror is A method of detecting the thickness of the glass tube G by detecting the two positions of the reference mirror that are driven and both interfere to increase the intensity may be employed.

  In the above embodiment, the glass tube G is moved in the X-axis direction while rotating, and the thickness of the entire area of the glass tube G is measured. However, if only one line measurement in the central axis direction is sufficient, rotation is accompanied. Instead, the thickness of the glass tube G may be measured.

  Moreover, in the said embodiment, although the glass tube G was moved to the X-axis direction, you may make it fix the glass tube G and to move the optical head 100B to an X-axis direction.

  In the above embodiment, the Z-axis direction moving mechanism is provided, but the Z-axis direction moving mechanism may be eliminated so that the glass tube G can be set with the drive limit position in the X-axis direction further upward. .

  Further, in the above embodiment and the modification, the measurement head divided by the spectroscopic unit 100A and the optical head 100B is used for the irradiation and incidence of the laser light. According to this, the optical head 100B arranged on the table 23 can be reduced in size, but if there is no problem in this reduction in size, the spectroscopic unit 100A and the optical head 100B are configured integrally and placed on the table 23. It may be arranged.

DESCRIPTION OF SYMBOLS 10 ... Work drive device, 11 ... X-axis direction feed motor, 12, 22 ... Screw rod, 13 ... Moving body, 14 ... Spindle motor, 20 ... Support device, 21 ... Z-axis direction feed motor, 23 ... Table, 25 ... Linear actuator, 30 ... SLD light source, 34 ... Polarizing beam splitter, 35 ... Diffraction grating, 36 ... Line sensor, 40 ... Optical fiber, 54, 56 ... Galvano mirror, 57 ... Objective lens, 60 ... Quadrant photo detector, 100A ... Spectroscopic unit , 100B ... Optical head, 112 ... Spindle motor control circuit, 114 ... Z-axis direction feed motor control circuit, 116 ... Laser drive circuit, 117 ... Data processor, 118 ... Y-axis direction error signal generation circuit, 119 ... Y-axis direction Servo circuit 121... Y-axis angle error signal generation circuit 122. Around the axis angle servo circuit, 200 ... controller

Claims (5)

A translucent tubular object support device that supports a translucent tubular object by extending a central axis in a predetermined first axis direction;
Laser light irradiation means for irradiating the translucent tubular object with laser light from a second axis direction perpendicular to the first axis direction;
A light receiving means for receiving the reflected light of the laser light reflected by the outer peripheral surface of the translucent tubular object and the reflected light of the laser light reflected by the inner peripheral surface of the translucent tubular object;
A thickness detecting means for detecting a thickness of the translucent tubular object at a position irradiated with the laser light from a signal corresponding to a light receiving state of the reflected light received by the light receiving means;
An apparatus for measuring the thickness of a translucent tubular object, comprising: a laser beam irradiation position moving unit that moves an irradiation position of the laser beam irradiated by the laser beam irradiation unit on the translucent tubular object in the first axis direction. In
Third axial position changing means for changing the position of the laser light irradiated to the translucent tubular object to a third axial direction orthogonal to both the first axial direction and the second axial direction;
Third-axis angle changing means for changing an angle around the third axis with respect to the central axis of the light-transmissive tubular object of the laser light irradiated to the light-transmissive tubular object;
Deviation of the position of the third axial direction relative to the central axis of the translucent tubular object with respect to the central axis of the translucent tubular object by splitting incident part of the reflected light from the translucent tubular object A third axial displacement detecting means for detecting the amount;
A part of the reflected light from the translucent tubular object is divided and made incident, and the irradiation direction of the laser light on the translucent tubular object is perpendicular to the third axis of the central axis of the translucent tubular object A third axis angle deviation detecting means for detecting an angle deviation amount around the third axis;
The optical axis of the laser beam applied to the translucent tubular object using the shift amount of the third axial position detected by the third axial position shift detecting means is the center of the translucent tubular object. Third axial position servo control means for servo-controlling the third axial position changing means so as to coincide with the axial position;
The optical axis of the laser beam applied to the translucent tubular object is the center of the translucent tubular object using the deviation amount of the angle around the third axis detected by the third axial angle shift detecting means. A third axis angle servo control means for servo-controlling the third axis angle change means so as to be perpendicular to the axis;
The laser light irradiation means includes an objective lens that condenses the laser light, the focal length Fx of the objective lens in the first axis direction, and the optical distance from the third axis rotation angle changing means to the objective lens The objective is such that the relationship between a and the optical distance b from the objective lens to the surface of the translucent tubular object is (1 / a) + (1 / b) = 1 / Fx. An apparatus for measuring a thickness of a translucent tubular object, wherein a lens and an angle changing means around the third axis are arranged. In the thickness measuring apparatus of the translucent tubular object according to claim 1,
The third axial direction position changing means is interposed in the laser light irradiation path for the translucent tubular object, and rotates around the first axis to change the irradiation position of the laser light to the translucent tubular object. An apparatus for measuring a thickness of a translucent tubular object constituted by a rotating optical component that changes in the third axial direction. In the thickness measuring apparatus of the translucent tubular object according to claim 2,
The rotating optical component is arranged so that a focal length Fy in the third axis direction of the objective lens is equal to an optical distance c from the rotating optical component rotating around the first axis to the objective lens. An apparatus for measuring the thickness of a light-transmitting tubular object. In the thickness measuring apparatus of the translucent tubular object according to claim 1,
A third axis for changing the irradiation position of the laser beam on the translucent tubular object by moving the laser beam irradiation unit in the third axis direction by moving the third axis direction position changing unit in the third axis direction. An apparatus for measuring the thickness of a translucent tubular object composed of a directional actuator. In the thickness measuring apparatus of the translucent tubular object according to any one of claims 1 to 4,
The thickness of the translucent tubular object configured by the rotating optical component that rotates around the third axis, the angle changing means around the third axis being interposed in the irradiation path of the laser beam to the translucent tubular object measuring device.

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