JP2019163946A - Noncontact surface profile measurement device - Google Patents

Abstract

To provide a noncontact surface profile measurement device which can switch incident direction of laser light to an optimum direction without putting in/taking out an optical element.SOLUTION: A first and second laser lights Lx, Ly different in incident direction are made to have a different wavelength from each other. A first and second reflected lights Rx, Ry of the lights are caused to be received only by first and second light position detection means 10x, 10y, respectively, via optical filter means 11a, 11b, 12. Out of position signals obtained with two orientations, the one having a higher intensity, is selected for measurement, and thereby a switch of measurement direction is fulfilled only by a switch of an electrical signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-contact surface shape measuring apparatus.

  Laser probe type non-contact surface shape measuring devices using laser autofocus are used to measure the shape and roughness of precision parts. In other words, the surface of the measurement workpiece to be measured is scanned in a predetermined direction while autofocusing with a laser beam is applied, and the measurement workpiece is calculated from the amount of movement of the autofocus optical system in the focus direction of the objective lens. It is the structure which acquires the measurement data regarding the surface shape of.

  The laser light is incident on the measurement workpiece in an incident direction along a predetermined direction (for example, the X-axis direction), and then reflected to obtain a surface shape having characteristics in the incident direction. If the surface shape of the measurement workpiece cannot be accurately measured in the incident direction of the laser beam, for example, if the return of the reflected light is obstructed by the shape of the surface of the measurement workpiece, the incident direction of the laser beam is changed by 90 degrees.

  As a method of changing the incident direction of the laser beam by 90 degrees, two measuring systems having different incident directions of the laser beam by 90 degrees are prepared, and the directionality in which measurement is performed by taking in and out some of the shared optical elements Are switched by 90 degrees (see, for example, Patent Document 1).

Japanese Patent No. 5346670

  However, in such a conventional technique, since some optical elements can be freely inserted and removed in order to change the incident direction of the laser beam by 90 degrees, a structure for accurately inserting and removing the optical elements is very difficult. It became complicated and caused an increase in the overall cost.

  The present invention has been made paying attention to such a related technique, and provides a non-contact surface shape measuring apparatus capable of switching the incident direction of laser light to an optimum direction without taking in and out an optical element. It is an object.

  According to the first technical aspect of the present invention, as the three-dimensional orthogonal coordinate axis XYZ, the first and second laser beams parallel to the vertical Z axis are in the X-axis direction and the Y-axis with respect to the optical axis coincident with the Z axis. First and second irradiation system means for irradiating each from a position displaced in the axial direction; and first and second laser beams from the first and second irradiation system means, supported movably along the optical axis; An objective lens that transmits the first and second reflected light beams of the first and second laser beams reflected on the surface of the measurement workpiece disposed on the optical axis in a state in which the directions are 90 degrees different from each other; and an objective lens First and second imaging optical system means for forming an image of the first reflected light and the second reflected light transmitted through the first and second reflected light images formed by the first and second imaging optical system means First and second light receiving light and outputting a position signal of each reflected light with an intensity corresponding to the amount of received light of each reflected light In order to make the focal points of the first and second laser beams as the reference coincide with the surface of the measurement work, based on either the optical position detection means and each position signal from the first or second optical position detection means. A non-contact surface shape measuring apparatus comprising: a focusing unit that moves the objective lens in the optical axis direction; and a movement amount detection unit that detects a movement amount of the objective lens in the optical axis direction by the focusing unit, The first and second laser lights have different wavelengths, and the first and second imaging optical system means are provided with first and second optical filter means for transmitting only the first and second reflected lights, respectively. The focusing means moves the objective lens based on only the stronger one of the position signals from the first or second light position detecting means.

  According to the second technical aspect of the present invention, the first or second laser beam is irradiated from either the first or second irradiation system unit, and the focusing unit has a light position corresponding to the irradiated laser beam. The position signal from the detection means is input first, and when the intensity of the position signal is higher than a predetermined value, the objective lens is moved with reference to the position signal. Instead, the other laser beam is irradiated, and the objective lens is moved with reference to the position signal of the other.

  According to the third technical aspect of the present invention, the first and second irradiation system means simultaneously irradiates the first and second laser beams, and the focusing means is a position from the first and second light position detection means. Both signals are input simultaneously, the intensity of both position signals is compared, the position signal having the stronger intensity is selected, and the objective lens is moved with reference to only that position signal.

  According to the first technical aspect of the present invention, the wavelengths of the first and second laser beams having different incident directions are made different from each other, and the first and second reflected lights corresponding to the respective laser beams are the first and second. Only the corresponding first and second optical position detecting means receive light via the first and second imaging optical system means by the optical filter means, respectively. By doing so, it is possible to perform measurement with the direction of incidence different by 90 degrees. If the stronger intensity is selected in the focusing means among the position signals obtained by the measurement in two directions, accurate measurement in the optimum direction becomes possible. Since only the switching of the electric signal is required, it is not a physical switching by putting in and out the optical element, so that the structure is simple and advantageous in terms of cost.

  According to the second technical aspect of the present invention, since an optimal incident direction is first selected on the basis of a predetermined value, it is only necessary to irradiate the selected direction with laser light during measurement.

  According to the third technical aspect of the present invention, in order to perform the measurement in both directions different by 90 degrees at the same time and automatically select and measure the optimum one automatically, Even when the optimum directionality frequently changes during scanning, it can be automatically handled.

The schematic side view (partial direction change) which shows a non-contact surface shape measuring apparatus. The schematic plan view which shows a non-contact surface shape measuring apparatus. The perspective view which shows the incident direction of a laser beam.

  1 to 3 are diagrams showing a preferred embodiment of the present invention. In the figure, the X axis and the Y axis are two directions orthogonal to each other on a horizontal plane, and the Z axis is a vertical direction. FIG. 1 shows a schematic side view, and a part thereof is shown along the Y direction as the X direction.

  The measurement workpiece 1 has a block shape having a lower surface 1a and an upper surface 1b, and a standing wall 1c is formed between the lower surface 1a and the upper surface 1b along the Y-axis direction. The measurement workpiece 1 is placed on an XY axis stage (not shown). The XY-axis stage is movable in the X-axis direction and the Y-axis direction together with the measurement work 1, but in this embodiment, the XY-axis stage moves with the Y-axis direction as the scanning direction. The lower surface 1a and the like of the measurement workpiece 1 cannot be visually confirmed, but are slightly uneven. The apparatus of this embodiment is for measuring the slight uneven shape along the scanning direction (Y-axis direction).

  Above the measurement workpiece 1, an objective lens 2 is supported by a drive unit 3 so as to be movable in the Z-axis direction. The central axis of the objective lens 2 coincident with the Z axis is the optical axis K, and the movement amount in the optical axis direction can be detected by the AF scale 4 as the movement amount detecting means.

  Above the objective lens 2, a dichroic mirror 5x, a half mirror 6x, and a dichroic mirror 7x are arranged in the X-axis direction. The dichroic mirrors 5x and 7x reflect only the wavelength region of the first laser light Lx, which will be described later, and transmit the other wavelength regions. The half mirror 6x reflects half of the first laser beam Lx and transmits half.

  Laser light irradiation means 8x for irradiating a semiconductor laser (wavelength 635 nm) as the first laser light Lx is provided above the central half mirror 6x.

  Above the dichroic mirror 7x, a first light position detecting means 10x is provided via an imaging lens 9x.

  Two optical filters 11a and 11b are provided between the dichroic mirror 7x and the imaging lens 9x. One optical filter 11a transmits only light having a wavelength of 600 nm or more, and the other optical filter 11b has a characteristic of transmitting only light having a wavelength of 650 nm or less.

   The first light position detecting means 10x is a divided photosensor, and the center part coincides with the image forming point of the image forming lens 9x, and each spot divided into two when the center of gravity of the spot of the first laser light Lx coincides with this center part. The output of the photo sensor is balanced.

  In this embodiment, the first irradiation system means is constituted by the laser beam irradiation means 8x, the half mirror 6x, and the dichroic mirror 5x, and the first imaging optical system means is constituted by the dichroic mirrors 5x and 7x and the imaging lens 9x, The optical filters 11a and 11b constitute first optical filter means.

  Similar dichroic mirror 5y, half mirror 6y, and dichroic mirror 7y are provided side by side in the Y-axis direction above dichroic mirror 5x, half mirror 6x, and dichroic mirror 7x in the X-axis direction. In FIG. 1, these are shown in the X-axis direction for convenience. The dichroic mirrors 5y and 7y reflect only the wavelength region of the second laser light Ly described later, and transmit the other wavelength regions. The half mirror 6y reflects half of the second laser light Ly and transmits half.

  Further, similarly to the above, a laser beam irradiation means 8y, an imaging lens 9y, and a second light position detection means 10y are provided. The second laser beam Ly is emitted from the laser beam irradiation means 8y. The second laser beam Ly is a semiconductor laser having a wavelength of 690 nm different from that of the first laser beam Lx. An optical filter 12 is provided between the dichroic mirror 7y and the imaging lens 9y. The optical filter 12 has a characteristic of transmitting only light having a wavelength of 640 nm or more.

  In this embodiment, the laser beam irradiation means 8y, the half mirror 6y and the dichroic mirror 5y constitute a second irradiation system means, and the dichroic mirrors 5y and 7y and the imaging lens 9y constitute a second imaging optical system means. The optical filter 12 constitutes second optical filter means.

  A camera 14 is provided above the dichroic mirror 5y via the imaging lens 13, and the surface state of the measurement workpiece 1 can be photographed.

  The first light position detection means 10x and the second light position detection means 10y output position signals Px and Py to the control unit 15, respectively. The control unit 15 can detect and compare the intensities of the position signals Px and Py from the first optical position detection unit 10x and the second optical position detection unit 10y, and can also compare the intensities of the position signals Px and Py. It can be compared with a predetermined value set in advance. Further, the control unit 15 outputs the moving direction and moving amount of the objective lens 2 necessary for focusing on the basis of the detected position signals Px and Py to the driving unit 3 as a signal S. In this embodiment, the control unit 15 and the drive unit 3 constitute a focusing unit.

  Next, the operation will be described.

  First, the first laser beam Lx having a wavelength of 635 nm is irradiated from the laser beam irradiation unit 8x, and the measurement workpiece 1 is scanned in the Y axis direction by an XY axis stage (not shown). The first laser light Lx is reflected by the half mirror 6x and the dichroic mirror 5x, and enters the objective lens 2 in a state parallel to the optical axis K and displaced from the optical axis K in the X-axis direction.

  The first laser light Lx that has passed through the objective lens 2 hits the lower surface 1a of the measurement workpiece 1 at a predetermined incident angle in the X-axis direction, and is reflected there to become the first reflected light Rx, which again travels in the direction that passes through the objective lens 2. .

  Originally, the first reflected light Rx passes through the objective lens 2, is reflected by the dichroic mirror 5x, passes through the half mirror 6x, is reflected by the dichroic mirror 7x, and forms the imaging lens 9x and two optical filters. The light is received by the first light position detecting means 10x through 11a and 11b. Since one optical filter 11a transmits only light having a wavelength of 600 nm or more, and the other optical filter 11b transmits only light having a wavelength of 650 or less, the first optical position detection means 10x has a first reflection having a wavelength of 635 nm. Only the light Rx is received.

  However, since the upright wall 1c is near the reflection point of the lower surface 1a of the first laser beam Lx, the first reflected light Rx reflected by the lower surface 1a is blocked by the upright wall 1c and reaches the original light position detecting means 10x. Does not return with strength. Therefore, the position signal Px detected from the first reflected light Rx and output from the first light position detecting means 10x becomes weaker than a predetermined value set in advance. The predetermined value corresponds to the intensity of the first reflected light Rx that is the minimum necessary for moving the objective lens 2 in the optical axis direction by the drive unit 3 to focus the first laser light Lx on the lower surface 1a of the measurement workpiece 1. The strength of the position signal Px.

  When the control unit 15 determines that the position signal Px from the first light position detection means 10x is weaker than a predetermined value, the irradiation of the first laser light Lx from the laser light irradiation means 8x is stopped, and then the directionality Is irradiated with the second laser light Ly from the laser light irradiation means 8y in the Y-axis direction different by 90 degrees.

  The second laser light Ly passes through the objective lens 2 with a direction different from that of the X-axis by 90 degrees and strikes the lower surface 1 a of the measurement workpiece 1. Since the second reflected light Ry reflected by the lower surface 1a is along the Y-axis direction, the second reflected light Ry passes through the objective lens 2 again without hitting the standing wall 1c, is reflected by the dichroic mirror 5y, and passes through the half mirror 6y. The light is reflected by the dichroic mirror 7y and is received by the second optical position detection means 10y through the optical filter 12 and the imaging lens 9y. Since the optical filter 12 has a characteristic of transmitting only light having a wavelength of 640 nm or more, the second light position detection unit 10y receives only the second reflected light Ry having a wavelength of 690 nm.

  When the second reflected light Ry deviates from the center of the second light position detection means 10y (when it is out of focus), the position signal Py from the second light position detection means 10y is used to correct the deviation. The receiving control unit 15 outputs a signal S for controlling the driving unit 3 and moves the objective lens 2 in the focus direction (optical axis direction) to focus the second laser beam Ly on the lower surface 1a.

  Since the measurement workpiece 1 is scanned in the Y-axis direction, the objective lens 2 reciprocates in the optical axis direction to keep focusing in accordance with the slight uneven shape on the Y-axis of the lower surface 1a. The AF scale 4 detects the amount of movement of the objective lens 2 in the optical axis direction. The amount of movement of the objective lens 2 detected by the AF scale 4 is height information of the lower surface 1 a along the Y-axis direction of the measurement workpiece 1. By repeating this measurement along the Y-axis direction while changing the position in the X-axis direction, the three-dimensional surface shape of the lower surface 1a can be acquired.

  When the position signal Py from the second light position detecting means 10y becomes a predetermined value or less during measurement by receiving the second reflected light Ry, the measurement is switched again to the measurement using the first reflected light Rx, and the first reflected light Rx is used. If the position signal Px is less than or equal to the predetermined value, the measurement point is like the bottom of a deep hole, so stop the measurement and adjust the incident angles of the first and second laser beams Lx and Ly. To do.

  As described above, if the control unit 15 selects the stronger one based on the predetermined value as in the present embodiment, it is possible to perform an accurate measurement with the optimum directionality. Only the switching of the electric signal is required, and not the physical switching by putting in and out the optical element as in the prior art, so that the structure is simple and advantageous in terms of cost. Further, as in this embodiment, if an optimum directionality is first selected based on a predetermined value, it is only necessary to irradiate the selected direction with laser light during measurement.

  As described above, the intensity of the reflected light from the measurement workpiece 1 is compared with a predetermined value, and instead of first selecting the optimum directionality, both X-axis and Y-axis laser beam irradiation means 8x, 8y are selected. The first laser beam Lx and the second laser beam Ly are simultaneously irradiated, and the first reflected light Rx and the second reflected light Ry returned from the measurement workpiece 1 are simultaneously irradiated with the first light position detecting means 10x and the second light position. You may make it detect with the detection means 10y. Then, the strengths of the position signals Px and Py may be compared by the control unit 15 to automatically select the stronger one and perform measurement while switching the optimum directionality during scanning. By doing so, it is possible to automatically cope with the case where the surface shape of the measurement workpiece is complicated and the optimum directionality frequently changes during scanning.

DESCRIPTION OF SYMBOLS 1 Measurement workpiece 1a Lower surface 1b Upper surface 1c Standing wall 2 Objective lens 3 Drive part (focus means)
4 AF scale (movement amount detection means)
5x dichroic mirror (first irradiation system means / first imaging optical system means)
5y Dichroic mirror (second irradiation system means / second imaging optical system means)
6x half mirror (first irradiation system means)
6y half mirror (second irradiation system means)
7x Dichroic mirror (first imaging optical system means)
7y Dichroic mirror (second imaging optical system means)
8x laser light irradiation means (first irradiation system means)
8y Laser light irradiation means (second irradiation system means)
9x imaging lens (first imaging optical system means)
9y imaging lens (second imaging optical system means)
10x first light position detection means 10y second light position detection means
11a, 11b Optical filter (first optical filter means)
12 Optical filter (second optical filter means)
15 Control unit (focusing means)
Lx 1st laser light Ly 2nd laser light Rx 1st reflected light Ry 2nd reflected light K Optical axis Px, Py Position signal

Claims (3)

As the three-dimensional orthogonal coordinate axis XYZ, the first and second laser beams parallel to the vertical Z axis are irradiated from the positions displaced in the X axis direction and the Y axis direction with respect to the optical axis matching the Z axis, respectively. A second irradiation system means;
The first and second laser beams supported so as to be movable along the optical axis and reflected by the first and second laser beams from the first and second irradiation system means and the surface of the measurement workpiece disposed on the optical axis. An objective lens that transmits the first and second reflected lights of the laser light in a state in which the directions are 90 degrees different from each other;
First and second imaging optical system means for imaging the first reflected light and the second reflected light transmitted through the objective lens;
First and second reflected light imaged by the first and second imaging optical system means, and a position signal of each reflected light is output at an intensity corresponding to the amount of received reflected light. Second light position detecting means;
Using either one of the position signals from the first or second light position detecting means as a reference, the objective lens is placed on the optical axis in order to make the first and second laser beams of the reference one coincide with the surface of the measurement workpiece. Focusing means to move in the direction;
A non-contact surface shape measuring apparatus comprising: a moving amount detecting unit that detects a moving amount of the objective lens in the optical axis direction by the focusing unit;
The first and second laser beams have different wavelengths;
The first and second imaging optical system means are provided with first and second optical filter means for transmitting only the first and second reflected lights, respectively.
The non-contact surface shape measuring apparatus characterized in that the focusing means moves the objective lens with reference to only the stronger one of the position signals from the first or second light position detecting means. Irradiating the first or second laser beam from either one of the first or second irradiation system means,
The focus means first inputs a position signal from the optical position detection means corresponding to the irradiated laser light, and when the intensity of the position signal is higher than a predetermined value, the objective lens is moved based on the position signal, 2. The non-contact surface shape according to claim 1, wherein, when the value is equal to or less than a predetermined value, the other laser beam is irradiated instead of the one laser beam, and the objective lens is moved with reference to the other position signal. measuring device. The first and second irradiation system means simultaneously irradiates the first and second laser beams,
The focus means inputs both the position signals from the first and second optical position detection means at the same time, compares the intensity of both position signals, selects the position signal with the stronger intensity, and selects only the position signal. 2. The non-contact surface shape measuring apparatus according to claim 1, wherein the objective lens is moved as a reference.

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