JPH10132549A - Form measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a form measuring device which can obtain measurement data at fixed sampling positional intervals even if a scanning speed changes. SOLUTION: Curves A, B, C shows relation between the scanning position (axis of abscissas) of a displacement gage to the shape of a measured face of the measured object 7 and a scanning speed (axis of ordinate). First, the displacement gage of a measuring device is set up at the measurement start position S of the measured object 7 to start measurement. In the case where the measured object 7 has a shape shown in the Figure 1, an inclination angle becomes larger at both the ends than that at the middle. Thus the displacement gage is low in scanning speed at both the ends of the measured object 7. In addition, when the scanning speed is variable, its changing locus is not restricted in its form (curves B, C). The position of the displacement gage during scanning in the direction of X is measured at equal spaces in a scanning direction (sampling) with a positional space kept at a constant value in nondependance on the scanning speed of the displacement gage to carry out form analysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring device, and more particularly, to a shape measuring device capable of measuring the shape of the surface of an object in a non-contact and highly accurate manner.

[0002]

2. Description of the Related Art Conventionally, many shape measuring devices using an optical displacement meter as a shape measuring probe have been proposed. The principle is that the optical displacement meter follows the surface of the object to be measured and measures the motion trajectory at that time,
In other words, the shape of the surface to be measured is measured indirectly.

FIG. 6 is a schematic diagram showing a main part of an example of a shape measuring apparatus to which the present invention is applied.
Is a diagram showing the overall configuration (the stage section A is shown in a side view),
FIG. 6B is a plan view of the stage section A. In FIG. 6, reference numeral 1 denotes an optical displacement meter used as a shape measuring probe, 2a and 2b denote an X stage and a Y stage, respectively.
a and 3b are actuators; 4a and 4b are controller drivers; 5a and 5b are length measuring means such as linear encoders; 6 is control / computing means for controlling an XY stage and analyzing measured data; is there.

FIG. 7 is a view for explaining a measuring operation procedure of the shape measuring apparatus shown in FIG. 6. First, the measuring object 7 is set, and the optical displacement meter 1 is moved to the measuring start position S in the X direction. (FIG. 7A). The light source of the optical displacement meter 1 is turned on, and the surface of the optical displacement meter 1 and the surface of the object 7 are measured so that the surface of the object 7 is located within the measurement range of the optical displacement meter 1 at the measurement start position. Is finely adjusted in the Y direction (FIG. 7B). At the set speed, scanning of the X stage is started, and the Y stage is operated so as to perform a copying operation while keeping the distance between the optical displacement meter 1 and the surface of the DUT 7 constant (FIG. 7A). . The output of the length measuring means 5a, 5b is sequentially taken into the control / arithmetic means 6 to measure the trajectory of the XY stage during the copying operation. After the measurement is completed, the motion trajectory, that is, the shape of the DUT 7 is analyzed using the control / calculation means.

In the above measuring operation procedure, the higher the scanning speed in the X direction, the shorter the measuring time.
The direction (focus direction) cannot be followed. Since the scan speed that can be followed differs depending on the inclination angle of the surface to be measured, the scan speed may be changed in accordance with the shape of the object to be measured.

[0006]

When the scanning speed is changed in accordance with the shape of the object to be measured as described above, the inclination angle of the surface to be measured is large as shown at both ends of the object to be measured 7 shown in FIG. (The smaller the radius of curvature, the lower the scanning speed. Generally, a sampling is often performed using a timer, and thus the sampling interval differs depending on the scanning speed. The lower the scanning speed, the smaller the sampling interval, that is, the larger the sampling data. However, it is generally desirable that the sampling interval be constant from the viewpoint of shape analysis.

The present invention has been made in view of the above circumstances, and the invention of claim 1 is to acquire measurement data at a constant sampling position interval regardless of a change in scanning speed. The present invention obtains more accurate measurement data at a constant sampling position interval irrespective of the shape of an object to be measured.
It is an object of the present invention to acquire measurement data at a constant sampling position interval at a high speed and at a constant sampling position interval. It was done.

[0008]

According to a first aspect of the present invention, an optical displacement meter is provided as a non-contact probe, and the non-contact probe is caused to scan along the surface of the object using the output of the displacement meter. A non-contact type shape measuring device for measuring the surface shape of the object to be measured, in a shape measuring device for changing the scanning speed of the displacement meter, regardless of the scanning speed of the displacement meter,
A characteristic feature is that a measurement sampling position interval is set to a constant interval, so that shape analysis of measurement data can be performed more accurately and easily.

According to a second aspect of the present invention, in the first aspect of the invention, sampling data obtained at different sampling position intervals depending on the scanning speed of the displacement meter is averaged to obtain measurement data at a fixed position interval. Thus, more accurate measurement data with less measurement error components due to the characteristics of the optical displacement meter can be obtained.

According to a third aspect of the present invention, in the first aspect of the present invention, data obtained at different sampling position intervals depending on the scanning speed of the displacement meter is selected to be measured data at a constant position interval. Therefore, the amount of calculation is small, the amount of stored data is small, the load on the CPU is small, the configuration can be made cheaper, or the sampling can be performed at a higher speed with less calculation.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the sampling time interval is changed in accordance with the scanning speed of the displacement meter to set the sampling position interval to a constant interval. Thus, the processing of the measurement data is simplified without having to perform the above steps, so that the configuration can be made easier.

According to a fifth aspect of the present invention, in the first aspect of the invention, averaging means for averaging sampling data obtained at different sampling position intervals depending on the scanning speed of the displacement meter, and selection for selecting the sampling data. Means, having means for switching between the averaging means and the selection means according to the shape of the object to be measured, the shape of the object to be measured, so that the optimal method can be selected according to the purpose, This enables measurement that is appropriate for the shape and purpose.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described in the prior art, the shape measuring apparatus of the present invention scans a displacement meter along the surface of an object to be measured, and measures the trajectory of the displacement meter to measure the trajectory. This is for measuring the shape of the measured object. In the prior art, the scanning direction is described as the X direction, but the measurement system may be two-dimensional or three-dimensional, and the scanning direction may be any of the X, Y, and Z directions. In the following, as an example, a description will be given of a measurement system in which the displacement meter finely moves so as to keep a certain distance in the Y direction while scanning in the X direction described as the related art.

(Invention of Claim 1) FIG. 1 is a view for explaining the invention of claim 1, which shows a scanning position of a displacement meter (horizontal axis) with respect to a shape of a measured surface of an object 7 to be measured. ) And the scanning speed (vertical axis) are shown by curves A, B, and C. First, the displacement meter of the measuring device is set at the measurement start position S of the DUT 7 and measurement is started. In the case where the DUT 7 has a shape as shown in FIG. 1, both ends thereof have a larger inclination angle than the center.
Therefore, the displacement meter has a low scanning speed at both ends as shown by a curve A, for example. The curve A is merely an example, and any change locus may be used as long as the scanning speed is variable (the dotted curve B and the broken curve C in the figure).
etc).

According to the first aspect of the present invention, the sampling (measurement) position interval is set to a constant interval irrespective of the scanning speed of the displacement meter, and the position of the displacement meter during scanning in the X direction in FIG. The shape is analyzed by measuring at equal intervals in the scanning direction.

(Invention of Claim 2) FIG. 2 is a diagram for explaining the invention of Claim 2, and FIG. 2 shows the relationship between the scanning position, the scanning speed, and the time. Here, the sampling data is measured at regular time intervals by a timer. Therefore,
As shown in FIG. 2, when sampling is performed at regular time intervals, when viewed from the position, data can be obtained densely at a large inclination angle (both ends) and coarsely at a small inclination (center).

According to a second aspect of the present invention, the sampling data obtained at different sampling position intervals depending on the scanning speed of the displacement meter is averaged to obtain measurement data at a fixed position interval. Are averaged to obtain measurement data.

FIG. 3 is a flowchart for explaining the second aspect of the present invention. First, the position in the scanning direction of data measured at a fixed sampling time is compared with a fixed position interval a (S).
1). While the measurement data is smaller than the fixed position interval a, the measurement data is temporarily stored (S2). If the measured data exceeds a certain position interval, the total of the temporarily stored measured data is divided by the number of measurement points to obtain an average value and stored (S3).
As a result, data at fixed position intervals can be obtained from data measured at fixed time intervals.

Here, the data is selected and averaged so as to have a constant position interval according to the scanning direction position of the measurement data. However, it is not always necessary to determine the data based on the scanning direction position.
For example, as shown by a dotted curve B in FIG. 1, when the number of measurement points at a fixed interval from the scanning speed is previously obtained, such as when the scanning speed is switched at a predetermined position, the determination may be made from the number of measurement points.

(Invention of claim 3) In the invention of claim 3, data obtained at different sampling position intervals depending on the scanning speed of the displacement meter is selected to be measured data at a constant position interval. Hereinafter, description will be given according to the flowchart shown in FIG.

As described in the second aspect of the invention, the position in the scanning direction of data measured at a constant sampling interval is compared with the constant position interval a (S1). While the measured data is smaller than the fixed position interval a, the measured data is not stored (S
4). When the measured data exceeds the fixed position interval, the measured data is stored (S5). That is, data at a fixed position interval is extracted from data measured at a fixed time interval and stored. As a result, data at fixed position intervals can be obtained from data measured at fixed time intervals.

Also in this case, the data is selected so as to have a constant position interval depending on the position of the measurement data in the scanning direction.
It is not always necessary to determine the position in the scanning direction. For example,
As shown by the dotted curve B in FIG. 1, when the number of measurement points at a fixed interval from the scanning speed is previously obtained, such as when the scanning speed is switched at a predetermined position, the determination may be made from the number of measurement points.

(Invention of Claim 4) In the invention of Claim 4, when the scanning speed is changed stepwise with respect to the position shown by the dotted curve B in FIG. By switching the (timer setting time), measurement data can be obtained at fixed position intervals. FIG. 5 is a diagram showing an example thereof. In FIG. 5, the speed is switched to two stages, but the speed is not limited to two stages and may be switched to any number of stages. The first speed is Va, the second speed is Vb, the first sampling time is Ta,
Assuming that the second sampling time is Tb and the sampling position interval is Ps, the sampling times Ta and Tb are

[0024]

(Equation 1)

At the speed switching point A, the scanning speed is switched from Va to Vb, the sampling time is switched from Ta to Tb, and at the speed switching point B, the scanning speed is changed from Vb to Vb.
At a, the sampling time is switched from Tb to Ta. The timer for determining the sampling time may be software-based or hardware-based.

According to a fifth aspect of the present invention, a fixed position interval is measured by averaging sampling data obtained at different sampling position intervals depending on the scanning speed as described in the second aspect of the present invention. Means to be data,
A means for selecting data obtained at different sampling position intervals depending on the scanning speed as described in the invention of claim 3 and making it as measurement data at a constant position interval, and setting an object to be measured; Before starting the measurement, which means to use is selected according to the shape and purpose of the object to be measured. This may be selected at the time of software or by hardware such as a button.

When the change in the inclination angle of the object to be measured is large, or when more accurate measurement is required, more data is measured and averaged during a fixed position interval to thereby reduce the error. Small data can be obtained. Conversely, when the change in the inclination angle of the object to be measured is small, or when it is desired to perform measurement at a higher speed with a certain degree of accuracy, the data is switched by software or hardware, and data at fixed position intervals is extracted as measurement data.

[0028]

According to the first aspect of the present invention, an optical displacement meter is provided as a non-contact probe, and the output of the displacement meter is used to scan the non-contact probe along the surface of the object to be measured. A non-contact type shape measuring device for measuring a surface shape, wherein in a shape measuring device for changing a scanning speed of the displacement meter, regardless of a scanning speed of the displacement meter, a measurement sampling position interval is set to a constant interval. Thus, the shape analysis of the measurement data can be performed more accurately and easily.

According to a second aspect of the present invention, in the first aspect of the present invention, the sampling data obtained at different sampling position intervals depending on the scanning speed of the displacement meter is averaged to obtain measurement data at a fixed position interval. The measurement data is small in the portion where the inclination angle of the surface is small, and the larger the inclination angle, the more data is measured within a fixed position interval and the average is used as the measurement data (the surface to be measured due to the characteristics of the optical displacement meter). Conventionally, the error depending on the inclination angle becomes larger as the inclination angle of the surface to be measured becomes larger), and more accurate measurement data with less measurement error components due to the characteristics of the optical displacement meter can be obtained.

According to a third aspect of the present invention, in the first aspect of the present invention, data obtained at different sampling position intervals depending on the scanning speed of the displacement meter is selected and used as measurement data at a constant position interval. The burden is small and the configuration can be made at lower cost. Further, since the number of operations is small, sampling at a higher speed becomes possible.

According to a fourth aspect of the present invention, in the first aspect of the present invention, since the sampling position interval is made constant by changing the sampling time in accordance with the scanning speed of the displacement meter, measurement can be performed without wasteful sampling. Data processing is simplified and can be configured more easily.

According to a fifth aspect of the present invention, in the first aspect of the invention, averaging means for averaging sampling data obtained at different sampling position intervals depending on the scanning speed of the displacement meter, and selection for selecting the sampling data. Means, having means for switching between the averaging means and the selection means according to the shape of the DUT, the shape of the DUT, the optimal method can be selected according to the purpose, the shape of the DUT, You can make measurements that meet your purpose.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the invention of claim 1;

FIG. 2 is a diagram for explaining the invention of claim 2;

FIG. 3 is a flowchart for explaining a measurement procedure according to the invention of claim 2;

FIG. 4 is a flowchart for explaining a measurement procedure according to the invention of claim 3;

FIG. 5 is a diagram illustrating a relationship between a scanning position and a speed of a displacement meter for explaining the invention of claim 4;

FIG. 6 is a schematic configuration diagram of an essential part for explaining an example of a shape measuring apparatus to which the present invention is applied. FIG. 6A is a diagram showing an entire configuration (a stage part A is shown in a side view), 6 (B)
Is a plan view of the stage section S.

FIG. 7 is a view for explaining a measuring operation procedure of the shape measuring apparatus shown in FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical displacement meter, 2a ... X stage, 2b ... Y stage, 3a, 3b ... Actuator, 4a, 4b ... Controller driver, 5a, 5b ... Length measuring means, 6 ... Control / arithmetic means, 7 ... DUT .

Claims (5)

[Claims] An optical displacement meter is provided as a non-contact probe, and the output of the displacement meter is used to scan the non-contact probe along the surface of the object to measure the surface shape of the object. A contact-type shape measuring device, wherein the scanning speed of the displacement meter is changed, wherein the measurement sampling position interval is constant regardless of the scanning speed of the displacement meter. . 2. The shape measuring apparatus according to claim 1, wherein sampling data obtained at different sampling position intervals according to the scanning speed of the displacement meter is averaged to obtain measurement data at a fixed position interval. 3. The shape measuring apparatus according to claim 1, wherein data obtained at different sampling position intervals according to the scanning speed of the displacement meter is selected and used as measurement data at a fixed position interval. 4. The shape measuring apparatus according to claim 1, wherein a sampling time is changed in accordance with a scanning speed of the displacement meter to make a sampling position interval constant. 5. An averaging means for averaging sampling data obtained at different sampling position intervals depending on a scanning speed of the displacement meter, a selecting means for selecting the sampling data, and the averaging based on a shape of a measured object. 2. The shape measuring apparatus according to claim 1, further comprising means for switching between the means and the selecting means.