JP2012107978A - Thickness measurement apparatus of translucent tubular object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and accurately measure the thickness of a translucent tubular object over the whole region.SOLUTION: A measuring laser beam is reflected by a galvano mirror 35, the reflected light beam is applied to a glass tube G, the reflected light beam reflected on the outer peripheral surface of the glass tube G and the reflected light beam reflected on the inner peripheral surface are received by a line sensor 39, and the thickness of the glass tube G is detected from receiving positions of respective reflected light beams. A servo laser beam from a servo laser light source 40 is reflected by the galvano mirror 35 and the reflected light beams is applied to a measuring laser beam irradiation position on the glass tube G or its nearby position from a Z-axis direction. By receiving the reflected light beam of the servo laser beam from the glass tube G by a photodetector 48 and controlling the drive of a motor 36 by a Y-axis direction error signal generation circuit 119, a Y-axis direction servo circuit 120 and a Y-axis direction drive circuit 121, the rotation of the galvano mirror 35 around an X axis is servo-controlled so that the optical axis of the measuring laser beam intersects with a center axis of the glass tube G.

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. As a measuring apparatus for this purpose, for example, as described in Patent Document 1 below, the translucent object is used. Many apparatuses are used that irradiate laser light obliquely to the surface of the light, receive reflected light reflected by the front surface and the back surface with a light receiving sensor, and determine the thickness of the translucent object from the difference between the light receiving positions. Further, the apparatus for measuring the thickness of the translucent object is not limited to this. For example, as described in Patent Document 2 below, a wide wavelength band from a super luminescent diode light source (SLD light source) is used. The surface of the inspection object is irradiated with laser light, and the reflected light from the surface of the inspection object interferes with the reflected light from the reference surface provided in the laser light irradiation path to the surface of the inspection object. It is also possible to employ a device that obtains the displacement of the object to be inspected by guiding to the diffraction grating and performing spectroscopy for each wavelength with the diffraction grating. That is, irradiate a translucent object with a laser beam in a wide wavelength band, cause reflected light on the front and back surfaces of the translucent object to interfere with each other, guide the light to a diffraction grating, and split the wavelength with the diffraction grating for each wavelength. Light is received and the light intensity at each light receiving position is acquired. The light intensity at each light receiving position (that is, the light receiving curve) is determined by the relationship between the reflected laser light wavelength and the distance between the front and back surfaces of the translucent object and the reflection of the same wavelength. Since it is brought about only by the interference between the laser beams, it varies depending on the distance (ie, thickness) between the front and back surfaces of the translucent object. Therefore, the thickness of the translucent object is obtained by analyzing the light receiving curve.

  The translucent object includes a tubular object such as a glass tube. In this case as well, the thickness and the thickness of the tubular object are measured by applying the methods and apparatuses described in Patent Document 1 and Patent Document 2 below. be able to. For example, the following Patent Document 3 describes an apparatus for measuring the thickness of a tubular object by the method and apparatus described in Patent Document 1 below. In Patent Document 3 below, it is described that the incident angle of the laser beam is changed to detect the refractive index and thickness of the tubular object. However, if the refractive index of the tubular object is known, the incident light is incident. The thickness can be measured with a fixed angle.

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

  When measuring the thickness of the translucent tubular object, the reflected light of the laser light irradiated on the tubular object needs to be received by an optical device that analyzes the light. For this purpose, it is necessary to irradiate the laser beam so that the angle formed by the laser beam and the surface of the tubular object is constant. When the translucent object is a tubular object, it is necessary to irradiate the laser beam so that its optical axis intersects the central axis of the tubular object, as described in Patent Document 3 above. If the central axis of the tubular object is a straight line and the diameter of the tubular object is large, as shown in Patent Document 3 above, the tubular object is set in the setting mechanism so that the central axis is at the set position, The laser beam may be moved relative to the tubular object along the set path, but this is done when there is a non-straight part on the central axis of the tubular object or the diameter of the tubular object is small However, the optical axis of the laser beam cannot always be made to intersect the central axis of the tubular object, and there is a problem that there is a portion where the thickness cannot be measured.

  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 too, simply moving the laser beam along the set path will not always allow the optical axis of the laser beam to intersect the central axis of the tubular object, and there are places where the thickness cannot be measured. There is a problem of doing. 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. It is difficult to always set the central axis of the tubular object to the set position, and the optical axis of the laser beam can always intersect the central axis of the tubular object only by moving the laser light along the set path. There is a problem that there may be a portion where the thickness cannot be measured.

  The present invention has been made to cope with the above-described problem, and an object of the present invention is to move a laser beam relative to the translucent tubular object in the central axis direction of the translucent tubular object, thereby translucent tubular object. When measuring the thickness of the entire area, the reflected light is always returned to a predetermined position (an optical device for analysis processing) even when there is a portion where the central axis of the translucent tubular object is deviated from the predetermined position. It is an object of the present invention to provide a thickness measuring device for a translucent tubular object that can measure the thickness of the entire area of the translucent tubular object in a short time. 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 object, the present invention provides a measurement laser that irradiates a translucent tubular object (G) with an optical component (35, 81) that changes the optical axis position of the laser beam. Light irradiation means (30 to 34, 60, 61, 70 to 75, 78 to 80, 83), reflected light of the measurement laser beam reflected on the outer peripheral surface of the translucent tubular object, and the translucent tubular object Measurement laser light receiving means (39, 76, 77) for receiving the reflected light of the measurement laser light reflected by the peripheral surface with the first light receiving sensor via the optical component, and the reflected light received by the first light receiving sensor Thickness detecting means (117, 200, S142, S148) that generates a signal corresponding to the received light state and detects the thickness of the translucent tubular object at the position irradiated with the measurement laser light from the generated signal. 140) and the laser beam irradiation means for measurement. The laser beam irradiation position moving means (11, 110) for moving the irradiation position of the measurement laser beam irradiated on the light transmitting tubular object in the direction of the central axis of the light transmitting tubular object is provided. In the object thickness measurement apparatus, a means for irradiating a translucent tubular object with servo laser light via an optical component, the irradiation position of the measuring laser light with respect to the translucent tubular object or a position in the vicinity thereof Servo laser light irradiating means (40 to 43, 62, 63, 70 to 75, 78 to 80) for condensing and irradiating servo laser light with an objective lens (44, 83), and servo laser light First deviation amount detection optical means (42, 47, etc.) for receiving the reflected light through the objective lens and the optical component and outputting a signal representing the deviation amount of the servo laser light from the central axis of the translucent tubular object. 48, 80, 84, 85 And the first servo means (36) for driving and controlling the optical component based on the signal from the first deviation amount detecting optical means so that the optical axis of the measuring laser beam intersects the central axis of the translucent tubular object. , 82, 119 to 121).

  In the present invention configured as described above, the measurement laser beam and the servo laser beam are transmitted through the optical component (for example, a rotatable mirror) that can change the optical axis position of the translucent tubular object. Based on a signal representing the amount of deviation of the servo laser light detected by the first deviation amount detection optical means from the central axis of the translucent tubular object, the measurement laser beam is irradiated on the surface. The optical component is driven and controlled so that the optical axis of the light beam intersects the central axis of the translucent tubular object. Thus, even when the central axis of the translucent tubular object is deviated from the set position, the optical axis of the laser beam for measurement can be always intersected with the central axis of the translucent tubular object. Thus, the thickness of the entire area of the translucent tubular object can be accurately measured.

  Another feature of the present invention is that the reflected light from the translucent tubular object of the servo laser light is incident, and the focal position of the servo laser light by the objective lens and the transparent laser light irradiated. Second shift amount detection optical means (42, 47, 49 to 51, 80, 84, 86 to 88) for outputting a signal indicating the shift amount from the surface position of the optical tubular object, and second shift amount detection optical means Based on the signal from the optical axis of the servo laser light so that the focal position of the servo laser light by the objective lens coincides with the surface position of the translucent tubular object irradiated with the servo laser light. The second servo means (122 to 124, 44a, 83a) for driving control in the direction is provided.

  According to this, the second servo means determines the focus position of the servo laser light by the objective lens based on the signal indicating the focus position deviation detected by the second deviation amount detection optical means. The objective lens is driven and controlled in the optical axis direction of the servo laser light so as to coincide with the surface of the irradiated transparent tubular object. Therefore, since the fluctuation of the central axis of the translucent tubular object can be detected with higher accuracy, the optical axis of the measurement laser light can be controlled to intersect the central axis of the tubular object with higher accuracy. .

  Another feature of the present invention is that a splitting optical element (62) for splitting the incident laser light is provided, and the laser light from one laser light source is split by the splitting optical element to obtain the measurement laser light. The servo laser beam is generated.

  According to this, since the number of laser light sources, optical components, and the number of laser drive circuits can be reduced, the manufacturing cost of the apparatus can be suppressed.

  Further, another feature of the present invention is that a splitting optical element (80) for splitting the incident laser beam is provided, and the laser beam emitted from one laser light source is common to the measurement laser beam and the servo laser beam. As the laser beam, the measurement laser beam and the servo laser beam irradiated to the translucent tubular object from the direction perpendicular to the central axis of the translucent tubular object through the objective lens and reflected by the translucent tubular object, In other words, the common laser beam is split by the splitting optical element to generate the reflected light of the measuring laser beam and the reflected light of the servo laser beam.

  This also reduces the number of laser light sources, optical components, and laser drive circuits, thereby reducing the manufacturing cost of the apparatus.

It is a whole block diagram of the thickness measuring apparatus of the translucent tubular object which concerns on 1st Embodiment of this invention. It is a block diagram which shows the structure of the optical head of FIG. 1 in detail. It is a block diagram which shows in detail the structure of the optical head seen along the BB line of FIG. 2A. It is explanatory drawing for demonstrating the relationship between the displacement of a glass tube, and the position change of the reflected light irradiated to the photodetector. 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 block diagram which shows in detail the structure of the optical head in the thickness measuring apparatus of the translucent tubular object which concerns on 2nd Embodiment of this invention. It is a block diagram which shows in detail the structure of the optical head seen along the BB line of FIG. 5B. It is a whole block diagram of the thickness measuring apparatus of the translucent tubular object which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the structure of the spectroscopy unit of FIG. 6 in detail. It is a block diagram which shows the structure of the measuring head of FIG. 6 in detail. It is a flowchart which shows the first half part of the thickness measurement program performed by the controller of FIG. It is a flowchart which shows the latter half part of the said thickness measurement program.

a. First Embodiment Hereinafter, a first 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 a first embodiment. 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 holds and moves the glass tube G, and irradiates the glass tube G with a measuring laser beam to measure the thickness of the glass tube G and reflects it from the glass tube G. An optical head 100 that receives light, a work driving device 10, and a support device 20 that supports the optical head 100 are 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 left movement limit position in this 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.

  An optical head 100 is fixed on the table 23. FIG. 1 is a conceptual diagram of an optical head 100 that covers all components in a plane. 2A and 2B show the optical head 100 in detail. FIG. 2A is a view of the optical head 100 viewed from the central axis direction (X-axis direction) of the glass tube G, and FIG. It is the figure which looked at along the arrow BB line of FIG. 2A. In FIGS. 2A and 2B, components overlapping in the viewed direction are omitted as appropriate. Specifically, in FIG. 2A, the measurement laser light source 30, the line sensor 39, and components on the optical path of the measurement laser light described later are omitted. In FIG. 2B, components on the optical path of the reflected light of the servo laser light are omitted.

  The optical head 100 has a measurement laser light source 30. The measurement laser light emitted from the measurement laser light source 30 is converted into parallel light by the collimator lens 31, most of which passes through the beam splitter 32 and enters the galvanometer mirror 35 through the relay lenses 33 and 34. Then, the light is reflected by the galvanometer mirror 35 and applied to the glass tube G. The relay lenses 33 and 34 are used to reduce the cross-sectional diameter of the measurement laser beam. The galvanometer mirror 35 has a rotation axis that is parallel to the X-axis direction and is assembled to the drive shaft of the motor 36. As a result, the galvanometer mirror 35 is driven to rotate forward / reversely by the motor 36, reflects the incident measurement laser beam, and changes its optical axis direction. The optical axis of the laser beam for measurement irradiated on the glass tube G is parallel to the XZ plane and is inclined by a predetermined angle with respect to the axis of the glass tube G (that is, the X axis).

  On the other hand, a part of the measurement laser light reflected by the beam splitter 32 is condensed on the light receiving surface of the photodetector 38 by the condenser lens 37. The photodetector 38 is a light receiving element that outputs a light reception signal corresponding to the intensity of light collected on the light receiving surface. The light reception signal from the photodetector 38 is supplied to the measurement laser drive circuit 116. The measurement laser drive circuit 116 is controlled by the controller 200 to drive and control the measurement laser light source 30. In this case, the measurement laser drive circuit 116 feedback-controls the intensity of the measurement laser light using the light reception signal from the photodetector 38, so that the measurement laser light source 30 always emits the measurement laser light with an appropriate intensity. .

  The measurement laser light applied to the glass tube G is first reflected by the outer peripheral surface of the glass tube G, enters the galvano mirror 35, is reflected by the galvano mirror 35, and is received by the line sensor 39. Further, the laser beam for measurement irradiated on the glass tube G is refracted on the surface of the glass tube G, enters the thick portion of the glass tube G, is reflected on the inner peripheral surface of the glass tube G, and is reflected on the glass tube G. Guided to the outer peripheral surface. The measurement laser light guided to the outer peripheral surface of the glass tube G is refracted again by the outer peripheral surface of the glass tube G, guided to the outside, reflected by the galvanometer mirror 35, and reaches the line sensor 39. The line sensor 39 is a light receiving element in which pixels such as a CCD and a CMOS are arranged in a straight line. The measurement laser beam reflected on the outer peripheral surface of the glass tube G and the measurement laser beam reflected on the inner peripheral surface of the glass tube G are used. The light receiving position of the laser light varies depending on the thickness of the glass tube G.

  A sensor signal extraction circuit 117 is connected to the line sensor 39. The sensor signal extraction circuit 117 is controlled by the controller 200 to derive a signal of each pixel of the line sensor 39 at a predetermined cycle. For each pixel, digital data corresponding to the signal intensity and digital data at the pixel position are obtained. Are output to the controller 200 as a pair.

  The optical head 100 also has a servo laser light source 40. Servo laser light emitted from the servo laser light source 40 is converted into parallel light by the collimator lens 41, and most of the light passes through the polarization beam splitter 42 and enters the galvanometer mirror 35. The servo laser light reflected by the galvanometer mirror 35 is applied to the outer peripheral surface of the glass tube G through the quarter-wave plate 43 and the objective lens 44. In this case, the optical axis of the measurement laser light irradiated on the outer peripheral surface of the glass tube G is the Z axis, and the measurement laser light is condensed on the outer peripheral surface of the glass tube G so as to form a small light spot. Is set to

  On the other hand, a part of servo laser light from the servo laser light source 40 reflected by the polarization beam splitter 42 is condensed on the light receiving surface of the photodetector 46 by the condenser lens 45. The photodetector 46 is a light receiving element that outputs a light receiving signal corresponding to the intensity of light collected on the light receiving surface. The light reception signal from the photodetector 46 is supplied to the servo laser drive circuit 118. The servo laser drive circuit 118 is controlled by the controller 200 to drive and control the servo laser light source 40. In this case, the servo laser drive circuit 118 feedback-controls the intensity of the servo laser light using the light reception signal from the photodetector 46, so that the servo laser light source 40 always emits the servo laser light with an appropriate intensity. .

  The reflected light from the glass tube G of the servo laser light is converted into parallel light by the objective lens 44, enters the galvano mirror 35 through the quarter wavelength plate 43, is reflected by the galvano mirror 35, and is polarized beam splitter. 42 and reflected by the polarization beam splitter 42. Half of the servo laser light reflected by the polarization beam splitter 42 is transmitted through the beam splitter 47 and the remaining half is reflected by the beam splitter 47. The reflected light of the servo laser light transmitted through the beam splitter 47 is received by the two-divided photodetector 48. As shown in FIG. 3, the photodetector 48 includes two light receiving elements whose light receiving area is divided into right and left (Y-axis direction), and is proportional to the intensity of servo laser light incident on the light receiving areas A and B. The detected signal is output as a received light signal (a, b). Further, the photodetector 48 has a servo Z-axis direction laser beam as shown in FIG. 3B when the center axis of the glass tube G coincides with the rotation axis of the spindle motor 14 when viewed from the Z-axis direction. Is arranged at a position divided into two by the dividing line DIV of the light receiving region.

  The light reception signals (a, b) output from the photodetector 48 are input to the Y-axis direction error signal generation circuit 119. The Y-axis direction error signal generation circuit 119 amplifies the received light signals (a, b), calculates the difference in light intensity (ab) using these signals, and calculates the calculation result as the Y-axis direction error signal. The result is output to the Y-axis direction servo circuit 120 as (ab). When the position of the glass tube G fluctuates in the Y-axis direction, as shown in FIGS. 3A, 3B, and 3C, the servo Z-axis direction laser irradiated on the glass tube G according to the fluctuating position. The position of the light changes, and the position of the reflected light RL received by the photodetector 48 changes accordingly. For this reason, the magnitude of the Y-axis direction error signal (ab) represents the amount of deviation in the Y-axis direction between the central axis of the glass tube G and the rotation axis of the spindle motor 14.

  Regarding the operations of the Y-axis direction servo circuit 120 and the Y-axis direction drive circuit 121, the Y-axis direction servo circuit 120 is based on the Y-axis direction error signal (ab) input from the Y-axis direction error signal generation circuit 119. The Y-axis direction servo signal is generated so that the Y-axis direction error signal (ab) becomes “0”, and the Y-axis direction drive circuit 121 outputs the drive signal to the motor 36 based on the Y-axis direction servo signal. Then, the galvanometer mirror 35 is rotated around the X axis. Accordingly, the rotation angle of the galvano mirror 35 around a straight line parallel to the X-axis direction is servo-controlled so that the reflected light of the servo Z-axis laser light received by the photodetector 48 is maintained at the center of the light receiving surface. It will be. For this reason, the optical axes of the servo Z-axis direction laser beam and the measurement laser beam are maintained so as to intersect the central axis of the glass tube G.

  Half of the servo laser light reflected by the beam splitter 47 is condensed by the condenser lens 49 onto the two-divided photodetector 50. A knife 51 is provided between the condenser lens 49 and the photodetector 50. The condensing lens 49, the photo detector 50, and the knife 51 are used for focus servo by a knife edge method often used in an optical disk apparatus. The two-divided photodetector 50 outputs a signal indicating the intensity of the incident servo laser beam for each region to the Z-axis direction error signal generation circuit 122.

  The Z-axis direction error signal generation circuit 122 outputs the difference between the two input signals to the Z-axis direction servo circuit 123 as a Z-axis direction error signal. The Z-axis direction error signal is a so-called focus error signal. The Z-axis direction servo circuit 123 generates a Z-axis direction servo signal based on the Z-axis direction error signal and outputs it to the Z-axis direction drive circuit 124. The Z-axis direction drive circuit 124 is based on the Z-axis direction servo signal. The focus actuator 44a is driven and controlled. The focus actuator 44a displaces the objective lens 44 in the optical axis direction, and displaces the focal point of the objective lens 44 in the optical axis direction. In this case, since the diameter of the glass tube G is somewhat large, the focus of the objective lens 44 can be made coincident with the surface of the glass tube G by this method, and the displacement of the glass tube G in the Y-axis direction can be detected with high accuracy. it can. The reason for using the knife edge method is that the difference between the two signals output from the two-divided photodetector 50 is caused only by the displacement of the glass tube G in the Z-axis direction.

  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 200 operates the input device 202 to cause the controller 200 to execute the thickness measurement program of FIGS. 4A and 4B.

  The controller 200 starts the execution of the thickness measurement program in step S100 in FIG. 4A, and sets the variable n to “0” in step S102. This variable n defines the timing for taking in the sensor signal from the line sensor 39, the rotation angle data from the rotation angle detection circuit 113, and the position data in the X-axis direction 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 measurement 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 optical axis of the servo laser beam: the 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 100 to the measurement setting position. Specifically, the Z-axis direction position where the servo laser beam is focused on the outer peripheral surface of the glass tube G to form a spot is output to the Z-axis direction feed motor control circuit 114 as a 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. Move in the axial direction toward the set position for measurement. During the movement of the table 23 and the optical head 100 in the Z-axis direction, the Z-axis direction feed motor control circuit 114 performs the Z-axis direction representing the Z-axis direction position of the table 23 (ie, the optical head 100) from the movement position detection circuit 115. 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 100 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 starts the operation of the measurement laser drive circuit 116. Thereby, the measurement laser drive circuit 116 drives the measurement laser light source 30 to emit the measurement laser light. In this case, the measurement laser drive circuit 116 feedback-controls the intensity of the measurement laser light using the light reception signal from the photodetector 38, so that the measurement laser light source 30 always emits the measurement laser light with an appropriate intensity. .

  The measurement laser light emitted from the measurement laser light source 30 is converted into parallel light by the collimator lens 31, most of which passes through the beam splitter 32 and enters the galvanometer mirror 35 through the relay lenses 33 and 34. The glass tube G is reflected by the galvanometer mirror 35. The measurement laser light irradiated on the glass tube G is first reflected by the outer peripheral surface of the glass tube G, reflected by the galvanometer mirror 35 and received by the line sensor 39. Further, the laser beam for measurement irradiated on the glass tube G is refracted on the surface of the glass tube G, enters the thick portion of the glass tube G, is reflected on the inner peripheral surface of the glass tube G, and is reflected on the glass tube G. Guided to the outer peripheral surface. The measurement laser beam guided to the outer peripheral surface of the glass tube G is refracted again on the outer peripheral surface of the glass tube G, guided to the outside, enters the galvanometer mirror 35, is reflected by the galvanometer mirror 35, and is reflected by the line sensor 39. To reach.

  After the process of step S112, the controller 200 starts operating the servo laser drive circuit 118 in step S114. Accordingly, the servo laser drive circuit 118 drives the servo laser light source 40 to emit servo laser light. In this case, since the servo laser drive circuit 118 feedback-controls the intensity of the servo laser light using the light reception signal from the photodetector 46, the servo laser light source 40 always emits the measurement laser light with an appropriate intensity. .

  Servo laser light emitted from the servo laser light source 40 is converted into parallel light by the collimator lens 41, most of which passes through the polarization beam splitter 42 and enters the galvanometer mirror 35, and is reflected by the galvanometer mirror 35. Then, the outer peripheral surface of the glass tube G is irradiated through the quarter wavelength plate 43 and the objective lens 44. The reflected light from the glass tube G of the servo laser light is converted into parallel light by the objective lens 44, enters the galvano mirror 35 through the quarter-wave plate 43, is reflected by the galvano mirror 35, and is a polarized beam. The light is guided to the splitter 42 and reflected by the polarization beam splitter 42. Half of the servo laser light reflected by the polarization beam splitter 42 passes through the beam splitter 47 and is received by the two-divided photodetector 48. The remaining half is reflected by the beam splitter 47, collected by the condenser lens 49, and guided to the photodetector 50 through the knife 51. A light reception signal indicating the amount of received servo laser light received by the photodetector 48 is supplied to a Y-axis direction error signal generation circuit 119, and the Y-axis direction error signal generation circuit 119 is based on this light reception signal. (Ab) is generated. On the other hand, the received light signal indicating the received light amount of the servo laser light received by the photodetector 50 is supplied to the Z-axis direction error signal generating circuit 122, and the Z-axis direction error signal generating circuit 122 is based on this received light signal. An error signal (that is, a focus error signal) is generated.

  After the process of step S114, the controller 200 instructs the Y-axis direction servo circuit 120 to start operation in step S116. In response to this, the Y-axis direction servo circuit 120 starts to operate and outputs a Y-axis direction servo signal based on the Y-axis direction error signal (ab) input from the Y-axis direction error signal generation circuit 119. The motor 36 is driven and controlled via the Y-axis direction drive circuit 121, and the rotation of the galvano mirror 35 around a straight line parallel to the X-axis direction is servo-controlled. Accordingly, the rotation angle of the galvano mirror 35 around a straight line parallel to the X-axis direction is servo-controlled so that the reflected light of the servo Z-axis laser light received by the photodetector 48 is maintained at the center of the light receiving surface. Thus, even if the glass tube G is displaced in the Y-axis direction, the galvano mirror 35 is rotationally controlled around a straight line parallel to the X-axis direction in accordance with the displacement, and the servo Z-axis laser light and the measurement laser light are controlled. Is always maintained so as to intersect the central axis of the glass tube G.

  After the process of step S116, the controller 200 instructs the Z-axis direction servo circuit 123 to start operation in step S118. In response to this, the Z-axis direction servo circuit 123 starts operation, generates a Z-axis direction servo signal based on the Z-axis direction error signal input from the Z-axis direction error signal generation circuit 122, The focus actuator 44a is driven via the direction drive circuit 124 to servo-control the objective lens 44 in the Z-axis direction (that is, focus servo control). Thereby, the focal position of the servo laser beam can be made coincident with the surface of the glass tube G, and the displacement of the glass tube G in the Y-axis direction can be detected with high accuracy.

  After the process of step S118, the controller 200 instructs the sensor signal extraction circuit 117 to start operation in step S120. In response to this, the sensor signal extraction circuit 117 starts operation, derives the signal of each pixel of the line sensor 39 at a predetermined cycle, and for each pixel, the digital data corresponding to the signal intensity and the pixel position A pair of digital data starts to be output to the controller 200. The controller 200 inputs digital data representing the signal intensity and pixel position output from the line sensor 39 in step S122. In this case, as shown in FIG. 2B, the reflected light input to the line sensor 39 is reflected light on the outer peripheral surface of the glass tube G and reflected light on the inner peripheral surface of the glass tube G, and the signal intensity has two peaks. Has a value. In step S122, the position (peak position) on the line sensor 39 where one of the two peak values is located is calculated. In the present embodiment, the peak value related to the measurement laser beam reflected by the outer peripheral surface of the glass tube G, that is, the position (peak position) on the line sensor 39 where the peak value on the upper side of the line sensor 39 in FIG. calculate.

  After the process of step S122, the controller 200 subtracts a predetermined set position on the line sensor 39 from the calculated peak position in step S124, and the absolute value of the subtraction result is less than a predetermined small allowable value. It is determined whether it is. In this case, the predetermined setting position is a position slightly higher in FIG. 2B than the center position of the line sensor 39 in the longitudinal direction. This position is a position where the displacement of the objective lens 44 by focus servo control is performed around the origin position. If the absolute value is less than or equal to the allowable value, the controller 200 determines “Yes” in step S124 and proceeds to step S132 in FIG. 4B. On the other hand, if the absolute value is greater than the allowable value, the controller 200 determines “No” in step S124 and proceeds to step S126.

  In step S126, the controller 200 detects the movement distance in the Z-axis direction from the subtraction result (peak position−setting position), adds the movement distance to the current Z-axis direction position, and moves in the Z-axis direction of the table 23. Calculate the moving position. In calculating the movement distance, a conversion function or conversion table indicating the movement distance in the Z-axis direction of the table 23 with respect to the subtraction result (peak position−setting position) is prepared in advance, and this conversion function or conversion table is prepared. Is used. Next, the controller 200 outputs the movement position of the table 23 to the Z-axis direction feed motor control circuit 114 in step S128. The Z-axis direction feed motor control circuit 114 controls the operation of the Z-axis direction feed motor 21 and inputs the position of the table 23 in the Z-axis direction from the movement position detection circuit 115, so that the table 23 is moved to the input movement position. Move up. After the process of step S128, the controller 200 inputs the movement position of the table 23 from the movement position detection circuit 115 in step S130, and the input movement position instructs the Z-axis direction feed motor control circuit 114. It is determined whether or not the movement position has been reached. Until the movement position of the table 23 reaches the instructed movement position, the controller 200 continues to determine “No” in step S130 and continue the process of step S130. On the other hand, when the moving position of the table 23 reaches the instructed moving position, the controller 200 determines “Yes” in step S130 and executes the processes of steps S122 and S124 described above. By the processing of these steps S122 to S130, the optical axis position of the measurement laser light reflected on the outer peripheral surface of the glass tube G is positioned slightly above the longitudinal center position of the line sensor 39. In this state, the center of the optical axis of the measurement laser light reflected on the outer peripheral surface of the glass tube G and the optical axis of the measurement laser light reflected on the inner periphery of the glass tube G is the longitudinal direction of the line sensor 39. Located almost in the center. Note that the processing from step S122 to step S130 is performed because the diameter of the glass tube G for thickness measurement varies slightly depending on the glass tube G, so that the distance from the optical head 100 to the surface of the glass tube G is constant. This is because the laser beam for measurement is irradiated to the position where the servo laser beam is condensed.

In step S132, the controller 200 instructs the spindle motor control circuit 112 to start rotation about 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, the controller 200 instructs the rotation angle detection circuit 113 to start operation in step S134. 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 S134, 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 S136. 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 S138.

  After the process in step S138, the controller 200 determines in step S140 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 S140, fetches the latest sensor signal from the sensor signal fetch circuit 117 in step S142, and rotates it in step S144. The rotation angle data is taken from the angle detection circuit 113, and the X-axis direction position data is taken from the movement position detection circuit 111 in step S146. And the controller 200 calculates the thickness of the glass tube G in step S148.

  In the calculation of the glass tube G, the positions (peak positions) of the peak values of the two reflection measurement laser beams on the outer peripheral surface and the inner peripheral surface of the glass tube G received by the line sensor 39 are detected. In this case, the peak value corresponds to the optical axis of the laser beam for measurement reflected on the outer peripheral surface and the inner peripheral surface of the glass tube G, respectively. Next, a distance between the two peak positions is obtained using the two detected peak positions. Then, the thickness of the glass tube G at the position where the measurement laser beam is irradiated is calculated from the distance between the peak positions using a conversion function or conversion table prepared in advance. This conversion function or conversion table is uniquely determined if the refractive index of the glass tube G and the angle of the laser beam for measurement with respect to the axis of the glass tube G are determined, and when the refractive index of the glass tube is not known. Is determined by measuring and inputting the refractive index of the glass tube G. The angle of the measuring laser beam with respect to the axis of the glass tube G is determined by the apparatus according to the present embodiment. In step S148, the calculated thickness of the glass tube G is stored in the memory in association with the previously input rotation angle data and X-direction position data.

  After the process of step S148, the controller 200 determines in step S150 whether the X-axis direction position represented by the acquired X-axis direction position data is equal to or greater than the measurement end position, 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. Further, in step S152, the controller 200 determines that there is no light reception data indicating an intensity higher than a set value in the acquired sensor signal, that is, the irradiation position of the measurement laser light has passed the end of the glass tube G. Or whether servo control is not being performed. If the X-axis direction position does not indicate the measurement end position or more and the received light data indicating the intensity greater than the set value is present in the sensor signal, the controller 200 determines “No” in steps S150 and S152. In step S154, “1” is added to the variable n, and the process returns to step S140. Then, every time the measurement has started is nT or more, the controller 200 repeats the processes of steps S142 to S148 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.

  When the X-axis direction position indicates the measurement end position or more, or when there is no received light data indicating the intensity greater than the set value in the sensor signal, the controller 200 determines “Yes” in step S150 or S152, Proceed to step S156 and subsequent steps. In step S156, the controller 200 instructs the spindle motor control circuit 112 to stop the operation of the spindle motor 14. 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 S158. 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 120 to stop the operation in step S160, and instructs the Z-axis direction servo circuit 123 to stop the operation in step S162. With these processes, the servo control of the rotation angle around the straight line parallel to the X-axis direction of the galvano mirror 35 (servo control in the Y-axis direction of the Z-axis laser beam for servo) and the servo of the objective lens 44 in the Z-axis direction are performed. Control (focus servo control) is also stopped.

  After the processing in step S162, the controller 200 instructs the measurement laser drive circuit 116 to stop driving the measurement laser light source 30 in step S164, and in step S166, instructs the servo laser drive circuit 118 to drive the servo laser light source 40. To stop driving. Thereby, the irradiation of the measurement laser light from the measurement laser light source 30 to the glass tube G and the irradiation of the servo laser light from the servo laser light source 40 to the glass tube G are stopped. Next, the controller 200 instructs the rotation angle detection circuit 113 to stop operating in step S168, and instructs the sensor signal extraction circuit 117 to stop operating in step S170. As a result, the rotation angle detection circuit 113 stops operating and angle data is not input to the controller 200, and the sensor signal extraction circuit 117 also stops operating and sensor signals are not input to the controller 200.

  After the process of step S170, 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 S172, and in step S174, 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, an operator removes the glass tube G from the fixing tool 15, sets the measured glass tube G, and again performs the thickness measurement mentioned above. It can be carried out. And the controller 200 displays the measurement result of the thickness of the glass tube G mentioned above on the display apparatus 204 in step S176, and complete | finishes execution of a thickness measurement program in step S178.

  As can be understood from the above description, according to the thickness measuring device for a transparent tubular object according to the first embodiment, the measurement laser beam and the servo laser beam can change the optical axis position. The surface of the glass tube G is irradiated through the galvanometer mirror 35. The measurement laser beam reflected on the surface of the glass tube G is again guided to the line sensor 39 via the galvanometer mirror 35. That is, the line sensor 39 receives both the reflected light of the measurement laser light reflected on the outer peripheral surface of the glass tube G and the reflected light of the measurement laser light reflected on the inner peripheral surface of the glass tube G, Output light reception signal. The controller 200 detects the thickness of the glass tube G at the irradiation position of the measurement laser beam based on the light reception signal from the line sensor 39. On the other hand, the servo laser light reflected on the surface of the glass tube G is guided to the photo detector 48, and the photo detector 48 detects the amount of deviation of the servo laser light in the Y-axis direction from the central axis of the glass tube G. Then, a signal representing the detected deviation amount is output. The Y-axis direction error signal generation circuit 119, the Y-axis direction servo circuit 120, and the Y-axis direction drive circuit 121 drive and control the motor 36 so that the optical axes of the servo laser beam and the measurement laser beam are glass tubes. The rotation angle around the straight line parallel to the X-axis line of the galvanometer mirror 35 is servo-controlled so as to intersect the central axis of G. As a result, even when the central axis of the glass tube G is deviated from the set position, the optical axes of the servo laser beam and the measurement laser beam can always intersect the central axis of the glass tube G. The thickness of the entire area of the glass tube G can be accurately measured over time.

  In the first embodiment, servo laser light is received by the photodetector 50 via the condenser lens 49 and the knife 51, and on the basis of this light reception, the Z-axis direction error signal generation circuit 122, the Z-axis direction servo are received. The circuit 123 and the Z-axis direction drive circuit 124 drive the focus actuator 44a to servo-control the objective lens 44 in the Z-axis direction (that is, focus control). Thereby, the focal position of the servo laser beam can be made coincident with the surface of the glass tube G, and the displacement of the glass tube G in the Y-axis direction can be detected with high accuracy.

b. Second Embodiment In the first embodiment, the measurement laser light source 30 that emits the measurement laser light and the servo laser light source 40 that emits the servo laser light are separately provided. However, the translucent tubular object thickness measuring apparatus according to the second embodiment emits the measurement laser beam and the servo laser beam in common as one laser beam, as shown in FIGS. 5A and 5B. A laser light source 60 is provided. 6A and 6B show the optical head 100 in detail in accordance with the display modes of FIGS. 2A and 2B.

  The laser light emitted from the laser light source 60 is incident on the beam splitter 62 via the common collimating lens 61 instead of the collimating lenses 31 and 41 of the first embodiment. The beam splitter 62 divides the laser light emitted from the laser light source 60 so as to have an appropriate intensity ratio, and generates measurement laser light and servo laser light. The measurement laser light enters the same beam splitter 32 as in the first embodiment. The servo laser light is reflected by the newly provided mirror 63 and is incident on the polarization beam splitter 42 as in the case of the first embodiment. Other configurations are the same as those of the first embodiment, and the same reference numerals as those of the first embodiment are given and description thereof is omitted.

  In the translucent tubular object thickness measuring apparatus according to the second embodiment configured as described above, the laser light emitted from the laser light source 60 is incident on the beam splitter 62 via the collimator lens 61, and the beam splitter is obtained. 62 generates measurement laser light and servo laser light. The measurement laser light is incident on the beam splitter 32, and the servo laser light is incident on the polarization beam splitter 42 via the mirror 63. Other operations are the same as those in the first embodiment. Therefore, according to the second embodiment, similarly to the case of the first embodiment, even when the central axis of the glass tube G is deviated from the set position, the light of the servo laser beam and the measurement laser beam is emitted. Since the axis can always intersect the central axis of the glass tube G, the thickness of the entire region of the glass tube G can be accurately measured in a short time. Further, the focal position of the servo laser light can be matched with the surface of the glass tube G, and the displacement of the glass tube G in the Y-axis direction can be detected with high accuracy. Further, in the second embodiment, as compared with the first embodiment, a common laser light source 60 and a laser beam for measurement and a servo laser beam can be obtained by simply adding a mirror 63 and a beam splitter 62. Since the collimating lens 61 is used, the number of laser light sources, the number of optical components, and the number of laser drive circuits can be reduced, so that the manufacturing cost of the apparatus can be reduced.

c. Third Embodiment In the first and second embodiments described above, the measurement laser beam and the servo laser beam are separately applied to the glass tube G. However, the translucent tubular object thickness measuring apparatus according to the third embodiment irradiates a glass tube G with a single laser beam as shown in FIG. It divides | segments so that it may become an appropriate intensity | strength ratio, and one is used for thickness measurement and the other is used for servo control. In the third embodiment, laser light is irradiated from a direction perpendicular to the central axis of the glass tube G, and the thickness of the glass tube G is measured using reflected light. As explained in the background section, a laser beam in a wide wavelength band is irradiated like a super luminescent diode light source (hereinafter referred to as SLD (Super Luminescent Diode) light source), and the reflected light is spectrally separated by a diffraction grating. A known technique for deriving the thickness of the glass tube G from the received light curve is used.

  Furthermore, in the third embodiment, in order to avoid the increase in the size of the optical head 100 used in the first and second embodiments, the function of the optical head 100 is changed between the spectroscopic unit 100A and the measurement head 100B. It is distributed in two. The spectroscopic unit 100A and the measurement head 100B are optically connected by an optical fiber 70. The measurement head 100B is fixed to the table 23 as in the case of the first embodiment.

  As shown in detail in FIG. 7A, the spectroscopic unit 100A includes an SLD light source 71 that emits laser light in a wide wavelength band. The laser light emitted from the SLD light source 71 is converted into parallel light by the collimator lens 72, the sectional diameter is reduced by the relay lenses 73 and 74, and the light is guided to the beam splitter 75. The beam splitter 75 transmits the incident light from the relay lenses 73 and 74 as it is, and guides it to the measurement head 100B via the optical fiber 70. Conversely, the laser light guided from the measuring head 100B to the beam splitter 75 via the optical fiber 70 is reflected by the beam splitter 75, guided to the reflective diffraction grating 76, and dispersed into a series of spectra to be line sensors. 77. The line sensor 77 is formed by a CCD, a CMOS, or the like. Note that a light transmissive diffraction grating may be used instead of the reflective diffraction grating 76, and the reflected light from the beam splitter 75 may be guided to the line sensor 77 via the light transmissive diffraction grating.

  The measurement head 100B includes relay lenses 78 and 79 for increasing the cross-sectional diameter of the laser light propagated by the optical fiber 70. The laser light whose cross-sectional diameter is increased by the relay lenses 78 and 79 passes through the beam splitter 80 and enters the galvanometer mirror 81. The laser beam reflected by the galvanometer mirror 81 is applied to the outer peripheral surface of the glass tube G through the objective lens 83. The galvanometer mirror 81 is driven to rotate around a straight line parallel to the X-axis by the motor 82 as in the first embodiment. The objective lens 83 is driven in the Z-axis direction by an actuator 83a similar to the actuator 44a of the first embodiment. In this case as well, the optical axis of the laser light applied to the outer peripheral surface of the glass tube G is the Z-axis direction, and the laser light is condensed on the outer peripheral surface of the glass tube G to form a small light spot. Is set to

  The reflected light from the glass tube G of laser light is converted into parallel light by the objective lens 83, enters the galvanometer mirror 81, is reflected by the galvanometer mirror 81, and is guided to the beam splitter 80. A part of the laser light reflected by the galvanometer mirror 81 and incident on the beam splitter 80 is transmitted through the beam splitter 80, reduced in cross-sectional diameter by the relay lenses 79 and 78, guided into the optical fiber 70, and passed through the optical fiber 70. Are guided to the spectroscopic unit 100A and used for thickness measurement. A part of the laser light reflected by the galvanometer mirror 81 and incident on the beam splitter 80 is reflected by the beam splitter 80 and guided to the beam splitter 84 to be used for servo control.

  Part of the laser light (corresponding to servo laser light) reflected by the beam splitter 80 passes through the beam splitter 84 and part of it is reflected by the beam splitter 84. The servo laser light transmitted through the beam splitter 84 is received by the two-divided photodetector 85. The photo detector 85 is the same as the photo detector 48 of the first embodiment, and the output of the photo detector 85 is supplied to the Y axis direction error signal generation circuit 119, and the Y axis direction error signal is the same as in the case of the first embodiment. Used to generate The servo laser light reflected by the beam splitter 84 is condensed on a two-divided photodetector 87 by a condenser lens 86. A knife 88 is provided between the condenser lens 86 and the photo detector 87. Similar to the condensing lens 49, the photo detector 50, and the knife 51 of the first embodiment, the condensing lens 86, the photo detector 87, and the knife 88 are used for focus servo by the knife edge method, and are in the Z-axis direction. It is output to the error signal generation circuit 122 and used to generate a Z-axis direction error signal.

  Further, the third embodiment includes a laser drive circuit 131 that replaces the measurement laser drive circuit 116 and the servo laser drive circuit 118 of the first embodiment, and a direct current that does not exist in the first embodiment. The second embodiment is different from the first embodiment in that a component detection circuit 132 and a thread servo circuit 133 are provided, and a data processing device 140 is provided in place of the sensor signal extraction circuit 117 in the first embodiment. Since other configurations are the same as those in the above-described embodiment, the same configurations are denoted by the same reference numerals, and the description thereof is omitted.

  The laser drive circuit 131 is instructed by the controller 200 to drive and control the SLD light source 71. In the third embodiment, the feedback control of the light amount of the SLD light source 71 is omitted. The DC component detection circuit 132 detects a DC component included in the Z-axis direction servo signal and outputs it to the sled servo circuit 133. The sled servo circuit 133 is instructed by the controller 200 to generate a servo control signal for controlling the DC component from the DC component detection circuit 132 to be “0”, and feed the generated servo control signal to the Z-axis direction. This is supplied to the motor control circuit 114. In addition to the control of the Z-axis direction feed motor 21 by the controller 200, the Z-axis direction feed motor control circuit 114 performs feedback control of the Z-axis direction feed motor 21 according to this servo control signal. Thereby, regardless of the diameter of the glass tube G, the distance from the measuring head 100B to the glass tube G is always a distance at which the objective lens 83 fluctuates in the Z-axis direction around the neutral position.

  The data processing device 140 performs A / D conversion on the digital size data representing the size of the signal output from each pixel of the line sensor 77 at a set frequency in accordance with an instruction from the controller 200, and performs A / D conversion. The obtained size data is stored in correspondence with the pixel position. Then, the data processing device 140 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. The laser light applied to the glass tube G by the objective lens 83 is reflected on both the front and back surfaces of the glass tube G, and the reflected lights on the both surfaces interfere with each other. In this case, the laser light emitted from the SLD light source 71 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 light 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. In the third embodiment, the numerical aperture (NA) of the objective lens 83 is small, and the depth of focus is equal to or greater than the thickness of the glass tube G. 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 76 changes the way of diffraction depending on the wavelength of the incident laser beam (corresponding to the measurement laser beam), so that the light receiving position of the line sensor 77 and the wavelength of the laser beam have a corresponding relationship. That is, the diffraction grating 76 changes the reflection angle of laser light having different intensity levels due to interference depending on the thickness of the glass tube G, so that the relationship between the position of the line sensor 77 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 77 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 140 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 140 to the controller 200.

  The operation of the translucent tubular object thickness measuring apparatus according to the third embodiment configured as described above will be described. In the third embodiment, the thickness of FIGS. 4A and 4B of the first embodiment is described. Instead of the measurement program, the thickness measurement program shown in FIGS. 8A and 8B is executed by the controller 200. The execution of the thickness measurement program is started in step S200 of FIG. 8A, and the controller 200 sets the variable n to “0” in steps S202 to S210 similar to the processes in steps S102 to S110 of the first embodiment. The glass tube G is moved to the measurement start position in the X-axis direction, and the measurement head 100B instead of the optical head 100 of the first embodiment is moved to the measurement setting position in the Z-axis direction. Next, in step S212, the controller 200 operates the laser drive circuit 131 and drives the SLD light source 71 to emit 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 measurement laser light emitted from the SLD light source 71 is converted into parallel light by the collimator lens 72, the cross-sectional diameter is reduced by the relay lenses 73 and 74, propagates through the optical fiber 70, and is transmitted from the spectroscopic unit 100A to the measurement head 100B. Led to. In the measurement head 100 </ b> B, the laser beam propagated by the optical fiber 70 is increased in cross-sectional diameter by the relay lenses 78 and 79 and enters the galvanometer mirror 81 through the beam splitter 80. The galvanometer mirror 81 reflects this incident laser light and makes it incident on the objective lens 83. The objective lens 83 condenses the incident laser light and irradiates the glass tube G. 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 83. 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. 83 is incident. 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 83. Accordingly, interference laser light having different intensities depending on the wavelength is incident on the objective lens 83 depending on the thickness of the glass tube G.

  The laser light incident on the objective lens 83 is converted into parallel light by the objective lens 83, guided to the galvanometer mirror 81, reflected by the galvanometer mirror 81, and incident on the beam splitter 80. The beam splitter 80 transmits a part of the incident laser light, reduces the cross-sectional diameter by the relay lenses 79 and 78, and guides it to the spectroscopic unit 100A through the optical fiber 70 as measurement laser light. In the spectroscopic unit 100 </ b> A, the measurement laser light propagated by the optical fiber 70 is reflected by the beam splitter 75 and is incident on the diffraction grating 76. The diffraction grating 76 makes the incident measurement laser light incident on the line sensor 77 with a reflection angle different depending on the wavelength.

  On the other hand, the beam splitter 80 reflects part of the laser light incident from the galvanometer mirror 81 and makes it incident on the beam splitter 84 as servo laser light. The beam splitter 84 reflects a part of the incident servo laser light and guides it to the condenser lens 86, the knife 51, and the photodetector 87. The received light signal indicating the received light amount of the servo laser light received by the photodetector 87 is supplied to the Z-axis direction error signal generation circuit 122 to generate the Z-axis direction error signal, as in the first embodiment. Used. The beam splitter 84 transmits a part of the incident servo laser light and guides it to the photodetector 85. The light reception signal indicating the amount of servo laser light received by the photodetector 85 is supplied to the Y-axis direction error signal generation circuit 119 to generate the Y-axis direction error signal, as in the first embodiment. Used.

  After the process of step S212, the controller 200 operates the Y-axis direction servo circuit 120 and the Z-axis direction servo circuit 123 by the processes of steps S214 and S216 similar to the processes of steps S116 and S118 of the first embodiment. Let it begin. Thereby, as in the case of the first embodiment, the rotation of the galvano mirror 81 around a straight line parallel to the X-axis direction is servo-controlled, and the optical axis of the laser beam for measurement and servo is always the glass tube. It is maintained so as to intersect the central axis of G. The objective lens 83 is also servo-controlled in the Z-axis direction (that is, focus servo control), and the focal position of the laser light is maintained so as to coincide with the surface of the glass tube G.

  After the processing in step S216, the controller 200 instructs the sled servo circuit 113 to start operation in step S218. The sled servo circuit 113 starts operating in response to the start of the operation, and detects the DC component included in the Z-axis direction servo signal supplied from the Z-axis direction servo circuit 123 detected by the DC component detection circuit 132 as “ A servo control signal to be controlled to “0” is generated, and the generated servo control signal is supplied to the Z-axis direction feed motor control circuit 114. The Z-axis direction feed motor control circuit 114 controls the rotation of the Z-axis direction feed motor 21 in accordance with the servo control signal, and servo-controls the table 23, that is, the measuring head 100B in the Z-axis direction. Thereby, regardless of the diameter of the glass tube G, the distance from the measuring head 100B to the glass tube G is always a distance at which the objective lens 83 fluctuates in the Z-axis direction around the neutral position.

  After the processing in step S218, the controller 200 instructs the data processing device 140 to start operation in step S220. In response to this, the data processing device 140 inputs a signal indicating the magnitude of the signal output from each pixel of the line sensor 77 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, the controller 200 starts rotating the glass tube G around the axis line at a predetermined rotation speed by the processing of steps S222 to S226 similar to steps S132 to S136 of the first embodiment, and causes the rotation angle detection circuit 113 to rotate. The controller 200 starts outputting rotation angle data representing the rotation angle around the axis of the glass tube G, and starts moving the glass tube G in the X-axis direction at a predetermined moving speed.

  After the processing of steps S222 to S226, the controller 200 performs processing at steps S228 to S234 and S242 similar to the processing of steps S138, S140, S144, S146, and S154 of the first embodiment at predetermined time intervals. The rotation angle data is taken in from the rotation angle detection circuit 113 and the X-axis direction position data is taken in from the movement position detection circuit 111. And in this 3rd Embodiment, the controller 200 took in the thickness data showing the thickness of the glass tube G from the data processor 140 in every said predetermined time interval in step S236, and took in this. The thickness data is stored in the memory in association with the acquired rotation angle data and X-direction position data.

  In addition, during the circulation process including the steps S230 to S236 and S242, the controller 200 determines that the irradiation position of the measurement laser beam is the end of the glass tube G by the determination process of the same step S238 as the step S150 of the first embodiment. If it has passed, the process proceeds to step S244. Also, when a signal indicating “measurement impossible” is input from the data processing device 140, the process proceeds to step S244 by the determination process in step S240.

  In step S240 and subsequent steps, the controller 200 performs rotation around the axis of the glass tube G and the axial direction of the glass tube G (X-axis direction) by the same processes of steps S244 to S250 as steps S156 to S162 of the first embodiment. , The servo control of the laser beam in the Y-axis direction by the galvanometer mirror 81 and the servo control (focus servo control) of the objective lens 83 in the Z-axis direction are stopped. In step S <b> 252, the controller 200 instructs the laser driving circuit 131 to stop driving the SLD light source 71 and stops emission of the laser light from the SLD light source 71. Further, the controller 200 stops the operation stop of the rotation angle detection circuit 113 by the process of step S254 that is the same as step S168 of the first embodiment, and also stops the operation of the data processing device 140 by the process of step S256.

  After the process of step S256, the controller 200 moves the movable body 13 to the X-axis direction drive limit position and moves the table 23 through the processes of steps S258 and S260 similar to steps S172 and S174 of the first embodiment. Move to Z-axis direction drive limit value. Then, the controller 200 displays the measurement result of the thickness of the glass tube G on the display device 204 by the process of step S262 similar to step S176 of the first embodiment, and the thickness is measured in step S264. Terminates program execution.

  In the translucent tubular object thickness measuring apparatus according to the third embodiment operating as described above, the same Y-axis direction servo control and Z-axis direction servo control as in the first embodiment are performed. Therefore, also in the third embodiment, as in the case of the first embodiment, even when the central axis of the glass tube G is deviated from the set position, the optical axis of the measurement laser beam is always set to the glass tube. Since it can intersect with the central axis of G, the thickness of the entire area of the glass tube G can be accurately measured in a short time. Further, the focal position of the servo laser beam (same as the measurement laser beam in this embodiment) can be made coincident with the surface of the glass tube G, and the displacement of the glass tube G in the Y-axis direction can be detected with high accuracy. . Further, in the third embodiment, one laser beam is irradiated onto the glass tube G, the reflected light is divided by the beam splitter 80 so as to have an appropriate intensity ratio, one is used for thickness measurement, and the other is Is used for servo control. Thereby, since the number of laser light sources, optical components, and the number of laser drive circuits can be reduced, the manufacturing cost of the apparatus can be kept low.

  In the third embodiment, the glass tube G is irradiated with a wide wavelength band laser beam, and the thickness of the glass tube G is obtained from the light receiving curve when the reflected light from the glass tube G is dispersed by a diffraction grating. The method was 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.

d. Other Modifications The first to third embodiments of the present invention have been described above. However, the present invention is not limited to the first to third embodiments, and departs from the object of the present invention. Various modifications are possible as long as they are not.

  In the first to third embodiments, Y-axis direction servo is performed by driving the galvanometer mirrors 35 and 81. However, any mirror can be used as long as the position of the optical axis of the laser beam can be changed. Also good. 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.

  In the first to third embodiments, the knife edge method is used for the Z-axis servo in which the objective lenses 44 and 83 for converging servo laser light are driven in the Z-axis direction. However, any other servo may be performed as long as Z-axis direction servo is possible. For example, Z-axis servo by the astigmatism method may be performed, or Z-axis servo by the spot size detection method (SSD method) may be performed. If there is no need to increase the measurement accuracy, the Z-axis direction servo need not be performed.

  In the first and second embodiments, the irradiation position of the measurement laser beam and the irradiation position of the servo laser beam in the glass tube G are combined. If the fluctuation of the central axis of the glass tube G is small, the irradiation is performed. You may just make a position into the vicinity.

  In the first to third embodiments, the thickness of the entire area of the glass tube G is measured by moving the glass tube G in the X-axis direction while rotating the glass tube G. For example, the thickness of the glass tube G may be measured without rotation.

  In the first to third embodiments, the glass tube G is moved in the X-axis direction. However, the glass tube G is fixed and the optical head 100 or the measurement head 100B is moved in the X-axis direction. Good.

  Further, in the first to third embodiments, the movement mechanism in the Z-axis direction is provided, but the movement mechanism in the Z-axis direction can be eliminated, and the glass tube G can be set with the drive limit position in the X-axis direction further upward. You may do it.

DESCRIPTION OF SYMBOLS 10 ... Work drive device, 11 ... X-axis direction feed motor, 13 ... Moving body, 14 ... Spindle motor, 20 ... Support device, 21 ... Z-axis direction feed motor, 23 ... Table, 30 ... Laser light source for measurement, 35, 81 ... Galvano mirror, 39, 77 ... Line sensor, 40 ... Laser light source for servo, 60 ... Laser light source, 70 ... Optical fiber, 76 ... Diffraction grating, 100 ... Optical head, 100A ... Spectroscopic unit, 100B ... Measuring head, 140 ... Data processing apparatus, 200 ... controller

Claims (4)

A laser beam irradiation means for measurement that irradiates the translucent tubular object with an optical component that changes the optical axis position of the laser beam,
The reflected light of the measurement laser light reflected on the outer peripheral surface of the translucent tubular object and the reflected light of the measurement laser light reflected on the inner peripheral surface of the translucent tubular object are passed through the optical component. Laser light receiving means for measurement received by the first light receiving sensor;
A signal corresponding to the light receiving state of the reflected light received by the first light receiving sensor is generated, and the thickness of the translucent tubular object at the position irradiated with the measurement laser light is detected from the generated signal. A thickness detecting means;
Laser light irradiation position moving means for moving the irradiation position of the measurement laser light irradiated by the measurement laser light irradiation means to the translucent tubular object in the central axis direction of the translucent tubular object. In the thickness measuring device of the translucent tubular object,
Means for irradiating the translucent tubular object with a servo laser beam through the optical component, wherein the servo laser beam is applied to a position where the measurement laser beam is irradiated on the translucent tubular object or in the vicinity thereof; Servo laser light irradiation means for condensing and irradiating laser light with an objective lens;
First, the reflected light of the servo laser light is received through the objective lens and the optical component, and a signal representing the amount of deviation of the servo laser light from the central axis of the translucent tubular object is output. Deviation amount detection optical means;
First servo means for driving and controlling the optical component so that the optical axis of the laser beam for measurement intersects the central axis of the translucent tubular object based on a signal from the first shift amount detection optical means. 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,
The reflected light from the translucent tubular object of the servo laser light is incident, the focal position of the servo laser light by the objective lens, and the translucent tubular object irradiated with the servo laser light Second deviation amount detection optical means for outputting a signal representing the deviation amount from the surface position of
Based on a signal from the second shift amount detection optical means, the focal position of the servo laser beam by the objective lens is made to coincide with the surface position of the translucent tubular object irradiated with the servo laser beam. And a second servo means for driving and controlling the objective lens in the optical axis direction of the servo laser light. In the thickness measuring apparatus of the translucent tubular object according to claim 1 or 2,
A splitting optical element for splitting the incident laser light is provided,
Thickness measurement of a translucent tubular object characterized in that laser light from one laser light source is split by the splitting optical element to generate the measurement laser light and the servo laser light apparatus. In the thickness measuring apparatus of the translucent tubular object according to claim 1 or 2,
A splitting optical element for splitting the incident laser light is provided,
The laser light emitted from one laser light source is used as the laser light common to the measurement laser light and the servo laser light, and is transmitted through the objective lens from the direction perpendicular to the central axis of the translucent tubular object. Irradiate a translucent tubular object,
The laser beam common to the measurement laser beam and the servo laser beam reflected by the translucent tubular object is divided by the dividing optical element, and the reflected light of the measurement laser beam and the servo beam are divided. An apparatus for measuring a thickness of a translucent tubular object, wherein reflected light of laser light is generated.

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