JPH04268404A - Measuring apparatus for displacement and measuring apparatus for geometry - Google Patents

Abstract

PURPOSE:To obtain a measuring apparatus for displacement having a small observation angle made by a light transmission axis and a light reception axis for measuring a distance to a surface to be measured and obtain a measuring apparatus for geometry for measuring the geometry of the surface to be measured. CONSTITUTION:A light transmission/reception lens 24 transmits an incident light beam to a surface 34 to be measured and condenses the reflected light from the surface 34 to be measured. A light spot of the surface 34 condensed by the light transmission/reception lens 24 is applied to a one-dimensional CCD sensor 28, and a signal according to a position of an image point is input to an arithmetic circuit 32. Thus an observation angle made by a light transmission system and a light reception system is not unnecessarily large, so that a distance to the surface to be measured and geometry of an object to be measured can be measured.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a displacement measuring device, and in particular, measures the distance to a measured surface by transmitting a light beam to the measured surface and receiving reflected light from the measured surface. The present invention relates to a displacement measuring device and a shape measuring device that measures the shape of a surface to be measured.

0002

[Prior Art] Displacement measuring devices that use triangulation methods, etc. to measure the displacement of irregularities, etc. on a surface to be measured in a non-contact manner have been known (Japanese Patent Publication No. 50-36374, Patent Application Publication No. 56-138204, patent application No. 57-22508
(Japanese Patent Application No. 58-52508, etc.).

As shown in FIG. 6, such a displacement measuring device includes a light source 50, a collimating lens 52, and a light transmitting lens 5.
4, a light receiving optical system including a light receiving lens 56, and a position detection sensor 58. According to this displacement measuring device, the light from the light source 50 is transmitted to the collimating lens 5.
2, the light is focused and emitted. Collimator lens 52
The light beam emitted from the light beam is irradiated onto the light transmitting lens 54, and the light emitted from the light transmitting lens 54 is irradiated onto the surface to be measured 60. The reflected light from the surface to be measured 60 is collected by the light receiving lens 56 and irradiated onto the position detection sensor 58. As a result, the position detection sensor 58 is irradiated with an image of the light spot irradiated onto the surface to be measured 60 . This position detection sensor 58 outputs an electrical signal according to the position of the image point. On the other hand, the optical axis of the light-receiving optical system is attached at a predetermined angle θ with respect to the optical axis of the light-transmitting optical system. For this reason,
When the surface to be measured 60 is displaced in the optical axis direction of the light transmission optical system, the position of the light spot on the surface to be measured 60 changes from point P1 to point P2 or point P3 as shown in FIG. , the image point position on the position detection sensor 58 moves from point Q1 to point Q2 or point Q3 as shown in FIG. In this way, when the position of the light spot on the surface to be measured changes in the direction intersecting the optical axis of the light receiving optical system, the position of the image point on the position detection sensor 58 changes in the direction perpendicular to the optical axis of the light receiving optical system. Changes to

Therefore, since the displacement of the image point on the position detection sensor 58 appears as a displacement of the image point in accordance with the displacement of the surface to be measured from the reference position, the signal output in accordance with the position of the image point on the position detection sensor 58 and The displacement of the surface to be measured is determined by determining the amount of deviation and the like based on the output signal of the preset reference light spot position.

[0005] By irradiating the above-mentioned light beam in the form of a continuous slit in a one-dimensional direction onto the surface to be measured,
Measurement of surface shape and the like using a method of optical cutting is also being carried out.

[0006]

[Problems to be Solved by the Invention] However, in the conventional displacement measuring device using the triangulation method, the light transmitting system and the light receiving system are arranged separately using a light transmitting lens and a light receiving lens, as shown in FIG. Therefore, the observation angle θ becomes large,
When measuring a concave portion, the optical path of the light receiving system may be blocked by the wall surface around the surface to be measured itself, making measurement impossible. This measurable depth H is as shown in equation 1.

[0007]

[Math 1]

However, H: Measurable depth L: Maximum radius or length of the recess necessary for measurement θa: Minimum angle between the light transmitting system and the outermost periphery of the light receiving lens.

[0009] In order to perform measurements in deeper recesses, the positional relationship between the light transmitting system and the light receiving system is changed, such as by reducing the diameter of each lens in the light transmitting system and the light receiving system. The observation angle θ formed between the optical axis and the optical axis of the light receiving system must be made small.

On the other hand, the level of the displacement signal obtained is highly dependent on the aperture of the lens, and it is necessary to set the aperture of the lens to a predetermined value or more. In other words, when the lens apertures of the light transmitting system and the light receiving system are made smaller, the amount of light at the image point irradiated onto the sensor becomes smaller, so the S/N of the obtained displacement signal,
Resolution, stability, etc. will deteriorate. in this way,
In order to maintain the above displacement signal in an appropriate state, the aperture of the lens is determined, and the size of a holding fitting such as a holder for holding the lens is determined. For this reason, the sizes of the effective diameter of the light transmitting system and the effective diameter of the light receiving system are limited, and the observation angle θ formed by the optical axis of the light transmitting system and the optical axis of the light receiving system cannot be made small. There is a problem in that there are areas where light cannot be received depending on the depth.

The present invention has been made to solve the above problem, and it is possible to measure the distance to the surface to be measured by reducing the observation angle formed by the light transmitting axis and the light receiving axis, increasing the measurable area. The present invention aims to provide a displacement measuring device for measuring the shape of a surface to be measured, and a shape measuring device for measuring the shape of a surface to be measured.

0012

Means for Solving the Problems In order to achieve the above object, the invention of claim 1 provides a displacement measuring device that includes a light source that irradiates a light beam, and a light beam that is irradiated from the light source and that sends the light beam to a surface to be measured. a single condensing lens that illuminates with light and forms an image of the illuminated portion of the surface to be measured; and position detection means for outputting a signal.

[0013] According to a second aspect of the invention, in the shape measuring apparatus, there is provided a light source for emitting a light beam, and a light beam emitted from the light source is transmitted to and illuminates a surface to be measured, and an illumination portion of the surface to be measured is illuminated. A single condensing lens that forms an image, a diverging means that diverges an incident light beam in only one direction and irradiates the light beam as a slit-shaped light onto a surface to be measured, and a condenser of the condensing lens. A position detecting means is provided on the image side and outputs a signal according to the position of the irradiated light beam.

[0014]

[Operation] According to the invention of claim 1, a single condensing lens is used to transmit a light beam to a surface to be measured for illumination and to form an image of the illumination portion from the surface to be measured. There is. Also,
A position detection means is provided on the imaging side of the condenser lens. This position detection means outputs a signal according to the position of the irradiated light beam.

According to the second aspect of the invention, a single condensing lens is used to transmit the light beam to the surface to be measured for illumination and to form an image of the illumination portion from the surface to be measured. There is. The diverging means diverges the incident light beam in only one direction and irradiates the measured surface with the light beam as a slit-shaped light. Further, a position detecting means is provided on the image forming side of the condensing lens. This position detection means outputs a signal according to the position of the irradiated light beam.

In this way, since the light transmission to the surface to be measured and the imaging of the illumination part of the surface to be measured are performed by a single condensing lens, the observation angle formed by the light transmission system and the light reception system can be made small. can do. Therefore, it is possible to increase the measurable area and measure the displacement of the surface to be measured and the shape of the surface to be measured.

[0017]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the first embodiment, the present invention is applied to a displacement measuring device 10.
This shows that. As shown in FIG. 1, a light source 20 composed of a semiconductor laser is attached to a housing of a displacement measuring device 10 (not shown), and a light beam emitted from the light source 20 is focused by a collimating lens 22. A light transmitting/receiving lens 24 is disposed on the exit side of the collimating lens 22, and a small diameter light beam emitted from the collimating lens 22 is irradiated onto the periphery of the transmitting/receiving lens 24. A surface to be measured 34 is installed on the emission side of the light transmitting/receiving lens 24, and the light beam emitted from the light transmitting/receiving lens 24 is
The light is irradiated onto the surface to be measured 34 to form a light spot A on the surface to be measured 34 .

The small-diameter light spot irradiated onto the surface to be measured 34 is focused by the light transmitting/receiving lens 24. A one-dimensional linear sensor 28 is disposed on the imaging side of the light transmitting/receiving lens 24. The one-dimensional linear sensor 28 is arranged at a predetermined distance from the light transmitting/receiving lens 24 and is attached to the displacement measuring device 10 so that the light receiving surface is perpendicular to the optical axis of the light transmitting/receiving lens 24. It is attached to the housing and outputs an electrical signal depending on the position of the image point. Also,
The one-dimensional linear sensor 28 is connected to an arithmetic circuit 32.

The operation of the first embodiment will be explained below. The light beam focused by the collimating lens 22 is
The light is incident on a portion of the light transmitting/receiving lens 24 separated by a distance h from the central axis L1. The light beam emitted from the transmitting/receiving lens 24 forms an angle α with the central axis L1 and reaches the surface to be measured 3.
4, and a light spot A is formed on the surface to be measured 34. This light spot A is focused by the light transmitting/receiving lens 24, and an image point is formed on the one-dimensional linear sensor 28. The center of this image point is located at a distance between the central axis L1 and Sx.

Here, the one-dimensional linear sensor 2 of this embodiment
8 is installed at the imaging position of the light transmitting/receiving lens 24, the imaging relationship will be described with reference to FIG. Injection angle α
And the relationship between the incident height h and the position where the light beam shines is as shown in Equation 2,

[0022]

[Math 2]

However, h: Incident height of the light beam from the central axis of the transmitting/receiving lens 24 X: Distance in the X-axis direction from the central axis of the transmitting/receiving lens 24 to the light spot position on the surface to be measured α: Transmission height The central axis of the light receiving lens 24 and the light transmitting/receiving lens 24
It can be expressed as the angle formed by the optical axis of the light beam emitted from the surface to the surface to be measured. Also, the imaging magnification (lateral magnification) m is as shown in Equation 3 using Newton's formula:

[0024]

[Math 3]

[0025] However, m: imaging magnification (lateral magnification) f
: Focal length Sx of the transmitting/receiving lens 24 : Image height Z in the X-axis direction of the light spot on the surface to be measured : Distance b from the transmitting/receiving lens 24 to the position of the light spot on the surface to be measured : From the transmitting/receiving lens 24 to the surface to be measured is the distance to the image point position.

For this reason, when the one-dimensional linear sensor 28 is disposed at the image forming position and the distance of Sx is detected from the obtained electric signal, from the above equations 2 and 3, the received signal is calculated as shown in the following equation 4. The distance Z to the measurement surface is determined.

[0027]

[Math 4]

Similarly, by using Equations 2 and 3 above, the distance X in the X-axis direction from the central axis of the light transmitting/receiving lens 24 to the position of the light spot on the surface to be measured can be determined.

The above distances X and Z have been explained for the case where the one-dimensional linear sensor 28 is arranged at the imaging position where the light spot on the surface to be measured is formed. A case will be described in which the installed detection surface K is fixed and the light spot on the surface to be measured is displaced in the optical axis direction.

As shown in FIG. 8, the light spot position on the surface to be measured is from the light spot position A1 where the imaging point is on the detection surface K to the light spot position A2 which is further away from the light transmitting/receiving lens 24 in the optical axis direction. A3
When the light spot positions A2 and A3 are displaced to , the images of the light spot positions A2 and A3 are formed at positions K2 and K3 distant from the detection surface K. At this time, the imaging points K1, K2, and K3 are located approximately on a straight line unless the measurement range is too large.

Therefore, even if the position of the light spot changes and the image formation position changes by tilting the one-dimensional linear sensor, the image can always be formed on the sensor. Therefore, even if the measurement position changes, SX
can be determined from the position on the sensor, so the distance can be calculated.

[0032]

[Math 5]

[0033]

[Math 6]

[0034] As a result, the displacement measuring device 10 of this embodiment
Now, using Equation 5 and Equation 6, one-dimensional linear sensor 2
From the output of step 8, the distance Z from the amount of displacement from the reference position to the surface to be measured is calculated.

As explained above, since both light transmission and reception are carried out in one lens system, the observation angle α formed by the light transmission axis or the light reception axis can be made small without being affected by mutual interference between the light transmission and reception systems. can do. Therefore, when measuring the depth of a recess, etc., the angle of incidence to the surface to be measured can be made small, which increases the measurable area by reducing the area where the optical axis is blocked by the surface to be measured. By doing so, it is possible to measure a deeper distance to the surface to be measured.

The first embodiment described above measures the distance to the surface to be measured, but the second embodiment described below applies the present invention to the cross-sectional shape measuring device 12. In this second embodiment, whereas the light spot of the first embodiment was irradiated onto the surface to be measured, a light beam is formed into a slit shape using the rod lens 26 and is irradiated onto the surface to be measured. Furthermore, since the second embodiment has substantially the same configuration as the first embodiment, the same parts are given abbreviations and detailed explanations are omitted.

As shown in FIG. 2, a light source 20 composed of a semiconductor laser is attached to the housing of the cross-sectional shape measuring device 12 (not shown), and the light beam emitted from the light source 20 is condensed by a collimating lens 22. be done. A light transmitting/receiving lens 24 is disposed on the exit side of the collimating lens 22 , and the small diameter light beam emitted from the collimating lens 22 is irradiated onto the transmitting/receiving lens 24 . A cylindrical rod lens 26 is disposed on the exit side of the light transmitting/receiving lens 24, and diverges the incident light beam into a slit shape to emit the light beam. Moreover, this rod lens 26 is attached so that the divergence direction is in the Y-axis direction orthogonal to the X-axis and Z-axis directions. A surface to be measured 34 is installed on the exit side of the rod lens 26, and the slit-shaped light beam emitted from the rod lens 26 is irradiated onto the surface to be measured 34. That is, as shown in FIG. 3, the light beam is irradiated from the rod lens 26 toward the surface to be measured 34 in a fan shape.

Therefore, the surface to be measured 34 is irradiated with a slit-like beam of light, and the intersection of the light beam and the surface to be measured 34 shines, that is, the surface to be measured shines. It is illuminated in a shape corresponding to the shape of 34. A two-dimensional CCD sensor 30 is disposed on the imaging side of the light transmitting/receiving lens 24. The slit-shaped beam of light irradiated onto the surface to be measured 34 is condensed by the light transmitting/receiving lens 24 and irradiated onto the two-dimensional CCD sensor 30 . This two-dimensional CCD sensor 30 has a light transmitting/receiving lens 2
4, the X-axis direction of the measurement axis is parallel to the direction of the light spot irradiated onto the surface to be measured 34, and the Y-axis direction of the measurement axis is attached to the housing of the cross-sectional shape measuring device 12 so as to be parallel to the Y-axis direction in which the rod lens 26 diverges the light beam into a slit shape and emits it. Further, this two-dimensional CCD sensor 30 has CCD elements arranged two-dimensionally, and outputs an electric signal according to the position and shape of the light beam irradiated onto the two-dimensional CCD sensor 30. Note that the two-dimensional CCD sensor 30 is connected to an arithmetic circuit 32.

For example, light that shines at a point B, which is spaced x in the X-axis direction and y in the Y-axis direction from the central axis L2 of the light transmitting and receiving lens 24, is condensed by the light transmitting and receiving lens 24, and is converted into a two-dimensional C
The CD sensor 30 is irradiated with light. 2D CCD sensor 30
As shown in FIG. 4, the light beam irradiated upward is, for example, Sx in the X-axis direction and Sy in the Y-axis direction with respect to the central axis L2.
The beams are irradiated at positions separated by . Therefore, two-dimensional C
The CD sensor 30 converts it into an electrical signal according to the position of the two-dimensional light beam, and inputs it to the arithmetic circuit 32 . The shape of the surface to be measured is measured according to the electrical signal from the two-dimensional CCD sensor 30.

The operation of the second embodiment will be explained below. The light beam focused by the collimating lens 22 is
The light is incident on a portion separated by a distance h from the central axis L2. The light beam emitted from the transmitting/receiving lens 24 forms an angle α with the central axis L1, is diverged into a slit shape through the rod lens 26, and is irradiated in the direction of the surface to be measured 34. A slit-shaped light beam is formed at 34. This light beam is focused by the light transmitting/receiving lens 24 and irradiated onto the two-dimensional CCD sensor 30. For example, as shown in FIG. 4, on the two-dimensional CCD sensor 30, point B on the surface to be measured is spaced apart from the central axis L2 by Sx in the X-axis direction and Sy in the Y-axis direction. get into position.

In the second embodiment, FIG.
According to the imaging relationship described with reference to , since the two-dimensional CCD sensor 30 is used as the position detection element, two-dimensional output is possible. Therefore, similarly to the first embodiment, the distance Y can be determined using Equations 2 and 3.

Therefore, the imaging position of the surface to be measured is two-dimensional CC
Taking into account the amount of correction in the case of deviation from the D sensor 30, the following Equation 7 can be obtained. Note that the distance X in the X-axis direction from the central axis of the light transmitting/receiving lens 24 to the light spot position on the surface to be measured, and the distance Z from the light transmitting/receiving lens 24 to the light spot position on the surface to be measured are the same as in the first embodiment. Similarly, the above equations 5 and 6 are used.

[0043]

[Math 7]

Here, Sy: Image height of the light spot on the surface to be measured in the X-axis direction.
Now, from the output Sx of the two-dimensional CCD sensor 30, the distance Z to the surface to be measured 34 is calculated by the arithmetic circuit 32 using Equation 5.
is calculated. In addition, the output S of the two-dimensional CCD sensor 30
From y, the distance of the surface to be measured 34 from the central axis L2 is calculated by the arithmetic circuit 32 using Equations 6 and 7, and the position and distance of the measurement point B on the surface to be measured 34 (
X, Y, Z values) are determined. For this reason, the two-dimensional CC
Across all detection surfaces of the D sensor 30, the corresponding measurement surface 3
By determining the positions and distances of the measurement points No. 4, the shape of the surface to be measured 34, such as a step, etc., can be determined.

As described above, in the second embodiment, both light transmission and reception are performed using one lens system, and the angle of incidence to the surface to be measured is reduced to a small angle without being affected by mutual interference between the light transmission and reception systems. Since it is possible to perform shape measurements such as depth measurements of recesses, a large measurable area can be obtained, and it is possible to measure deeper distances to the surface to be measured and shapes with steps and the like.

In the second embodiment, an example was explained in which a rod lens is used to obtain slit-shaped light, but a cylindrical lens, a cylindrical mirror, etc. can also be used as an element for obtaining slit-shaped light, and a rotating polygon Slit-shaped light can also be obtained by scanning a light beam from a mirror or the like.

Furthermore, in the second embodiment, a case was explained in which the rod lens was arranged on the exit side of the light transmitting and receiving lens.
It may be used on the incident side of the light transmitting/receiving lens, or a slit or the like may be provided on the light source side to irradiate the surface to be measured with a slit image.

In the second embodiment, two position detectors are used.
Although we have explained the case where a dimensional CCD sensor is used, the position detector is not limited to a 2-dimensional CCD sensor, and it is possible to detect a 2-dimensional position on the sensor using a position detection method using a television system using an image pickup tube. It is also possible to use an element that can output .

Note that in the first and second embodiments described above, the case where the light transmitting optical system and the light receiving optical system are fixed and the position detector is also fixed is explained, but the light transmitting optical system and the light receiving optical system are fixed. The viewing angle may be changed by changing the angle of at least one of the optical systems with respect to the measurement term, and the position detector may be moved.

[0050]

Effects of the Invention As explained above, according to the present invention, even when measuring a measurement surface with steps, etc., the measurable area can be improved by reducing the observation angle formed by the light transmitting system and the light receiving system. It has the excellent effect that it can increase the amount of light and reduce the light blocking area of the light transmitting system or the light receiving system due to the measurement surface itself.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the vicinity of an optical system of a displacement measuring device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing the front view of the periphery of an optical system of a shape measuring device according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a side view of the periphery of an optical system of a shape measuring device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing the irradiation state of the light beam on the position detector (light receiving surface) of the shape measuring device.

FIG. 5 is a diagram showing the relationship between a surface to be measured and a position detector in the imaging optical system.

FIG. 6 is a schematic diagram showing the periphery of an optical system of a distance measuring device using a conventional triangulation method.

FIG. 7 is a diagram showing the spot diameter of the light beam irradiated onto the detection surface when the surface to be measured is displaced in the optical axis direction in the imaging optical system.

FIG. 8 is a diagram showing the relationship between a surface to be measured, a detection surface, and an imaging surface.

[Explanation of symbols]

10 Displacement measuring device 12 Cross-sectional shape measuring device 20 Light source 22 Collimating lens 24 Transmitting and receiving lens 26 Rod lens 28 One-dimensional linear sensor 30 Two-dimensional CCD sensor 32 Arithmetic circuit 34 Surface to be measured

Claims (2)

[Claims] 1. A light source that irradiates a light beam, and a single condenser that sends the light beam irradiated from the light source to a surface to be measured to illuminate it and forms an image of the illuminated portion of the surface to be measured. A displacement measuring device comprising: a lens; and a position detecting means that is disposed on the imaging side of the condensing lens and outputs a signal according to the position of the irradiated light beam. 2. A light source that irradiates a light beam, and a single condenser that sends the light beam irradiated from the light source to a surface to be measured to illuminate it and forms an image of the illuminated portion of the surface to be measured. a lens, a diverging means that diverges the incident light beam in only one direction and irradiates the light beam as a slit-shaped light onto the surface to be measured; A shape measuring device comprising: a position detecting means for outputting a signal according to the position of a light beam.