JPH02145903A - Displacement measuring apparatus - Google Patents

Abstract

PURPOSE:To enable measurement in a direction vertical to the radius of a test specimen at a high accuracy in a non-contact manner by utilizing one light probe. CONSTITUTION:An area A and an area B are delimited by the centers of image sensors 6 and 7, the relation between, the difference of quantities of light obtained by the sensors 6 and 7, (A-B)/(A+B)(the difference is divided by A+B to normalize so that characteristic is made free from a total quantity of light) and the position of an objective lens 4 is as shown in Fig K. Then, a shape of a test specimen 1 is determined by characteristic in the same figure. In other words, a probe 8 is moved turning the test specimen 1 so as to be always focused and the current movement thereof is determined with a length measuring device XLM as displacement from a specified position. A focusing position of the objective lens 4 of the probe 8 is so set as to coincide with the center of rotation of the test specimen 1 beforehand and with this moment as reference, the shape of the test specimen 1 (radius) as determined from the position of the probe 8.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a displacement measuring device, and is capable of measuring physical property constants such as Young's modulus and Poisson's ratio of elastically changing members non-contactly and with high precision using an optical probe. The present invention relates to a displacement measuring device that can perform high-speed measurement.

(Prior Art) Among the physical property constants of elastic materials, Young's modulus and Poisson's ratio, for example, related to material deformation are important constants and have been conventionally measured by various methods.

When the material to be measured is formed into a cylindrical shape with a surface S and pulled with a force F, the radius γ or γ - Δγ.

Assuming that the length of the sentence changes to the intersection + Δ, the Young's modulus E and Poisson's ratio δ can be obtained from the formula.

Conventionally, the displacement measuring device used to determine physical property constants such as Young's modulus E and Poisson's ratio δ is a Schopper type tester, etc., and elongation is measured between gauge lines pre-attached to the object to be measured. Measurement was carried out by contacting the material with a measuring device such as a vernier caliper.

Generally, with conventional measurement methods, it is very difficult to obtain measurement accuracy on the order of microns, and since the measurement is performed by contacting the object to be measured, soft materials may be deformed, making it difficult to measure with high precision.

On the other hand, radius measuring instruments and linear encoders using lasers are capable of relatively highly accurate measurement, and various measurement methods have been proposed.

These measurement methods generally have problems in that they have poor operability and are difficult to perform highly accurate measurements because it is necessary to measure while applying force to the object to be measured.

(Problems to be Solved by the Invention) The present invention uses an optical probe to measure the radial direction and vertical direction of a cylindrical object to be measured with high precision in a non-contact manner. The purpose of the present invention is to provide a displacement measuring device that is compact in size and has a simple configuration with good operability.In particular, by adopting a two-beam system, it is possible to perform high-speed and highly accurate measurements. The purpose is

(Means for solving problem C) After making the light beams from the two light sources incident on different positions from the optical axis of the objective lens, the light beams are focused on the object to be measured, and the beams of light from the objective lens relative to the object are focused. A probe configured to receive the deviation in the direction perpendicular to the optical axis of the reflected light from the object to be measured due to the deviation in the optical axis direction, a moving mechanism Xs for moving the probe in the optical axis direction, and a moving mechanism Xs for moving the probe in the optical axis direction. moving mechanism xs
Length measuring device X L ) i'l and the length measuring device 'a
It has a $+ control circuit section that processes data from the XLM and controls the entire device, and a storage section that stores various information from the length measuring devices XL, M, the control circuit section, etc. The shape of the object to be measured is determined using the following elements.

(Example) FIG. 1 is a schematic diagram of essential parts of an embodiment of the present invention.

In the figure, reference numeral 1 denotes an object to be measured, and a part of the object is provided with two underwater gauge lines for use in measurement.

2.3 is a laser as a light source, 4 is an objective lens, and the light beams 2a and 3a from the laser 2.3 are incident at different incident angles from off-axis, and the reflected light beam from the object to be measured l is off-axis. It is re-injecting from Reference numeral 5 represents an imaging lens, and reference numerals 6 and 7 each represent an image sensor such as a COD. Among these, the image sensor 6 is arranged in a substantially conjugate relationship with the object to be measured 1 through the objective lens 4, and the image sensor 7 is arranged in an approximately conjugate relationship with the object to be measured 1 through the objective lens 4 and the imaging lens 5. ing.

Among the reflected light beams from the object to be measured 1, a light beam 2a reflected at a large angle is condensed by the objective lens 4 and focused on the surface of the image sensor 6. Among the reflected light beams from the object to be measured 1, the light beam 3a reflected at a small angle is reflected by the objective lens 4.
After the light is focused, it is reflected by the reflection jllll, and is focused by the imaging lens 5 onto the surface of the image sensor 7.

The LD uses a laser driver to drive and control the laser 2.3. SD is a sensor driver that drives and controls the image sensor 6.7.

8 is a probe, which includes two lasers 2.3 and an objective lens 4. It has an imaging lens 5, two image sensors 6, 7, a laser driver LD, and a sensor driver SD.

xs and zs are pulse stages each serving as a moving mechanism. Of these, the pulse stage XS drives the probe 8 in the optical axis direction of the objective lens 4, and the pulse stage z
S drives the probe 8 in a direction perpendicular to the optical axis.

XLM and ZLM are length measuring devices, among which length measuring device
LM measures the length in the optical axis direction of the objective lens 4, and ZLM measures the length in the direction perpendicular to the optical axis of the objective lens 4. EC is an expander, which applies force to the object to be measured 1 to extend or contract it.

LC is a load cell, which measures a stretching force of 11Ec.

θS1. Each of θS2 is a pulse stage, which rotates the object 1 to be measured.

CR is a controller and pulse stages xs, zs,
Drive control city θS1 and es2.

GOMP is a control circuit unit that processes various measurement data and controls the entire device. AS is an analog switch, and selects No. 53 from image sensor 6.7 as necessary.

A/D is an analog-to-digital converter that converts the output signal from the image sensor 6.7 from an analog quantity to a digital quantity. MEMO is a storage unit and the length measurement 'aXL
It stores various information from M, ZLM, control circuit section COMP, etc.

1) P is a display of CRTW, and PR is a printer, which prints out signals from the control circuit section COMP.

Next, a method for measuring the radius γ and the cross-sectional area S when the object to be measured l is formed into a cylindrical shape in this example will be described.

The object to be measured 1 and the image sensor 6 are now connected through the objective lens 4.
．． 7 is in focus, the image sensor 6
．． It is adjusted so that the distribution of light on the seven surfaces is as shown by a curve 21 shown by a solid line in FIG. 2, and when the lens is out of focus, there is a horizontal shift as shown by a curve 22 shown by a dotted line.

At this time, the focal length of the imaging lens 5 is set so that the amount of lateral deviation on the image sensor 6 is, for example, 100 times the amount of lateral deviation on the image sensor 7 for the same lateral deviation. If an attempt is made to use the image sensor 6 in common without the imaging lens 5 and to obtain the same difference in displacement amount, the effective diameter of the objective lens 4 will increase. For this reason, when the imaging lens 5 is not used, it is preferable to set the amount of deviation on the image sensor 6 to about 10 times the amount of deviation on the image sensor 7.

Also, although it is possible to obtain different shift products using only one light beam, in order to achieve the purpose of the present invention, the amount of shift on the image sensor will decrease and the sensitivity will deteriorate, so two light beams are used. It's better to be there.

Divided into area A and area B with the center of the image sensor as the border, the difference in light layer obtained by the sensor at this time (A - B) /
The relationship between (A + B) (normalized by dividing by A + 8 so that the characteristics are not affected by golden light) and the position of the objective lens 4 is shown in FIG. 3. In the figure, the distance between points P3 and P24 is 100 times the distance between points P1 and P2. The shape of the object to be measured l is determined from the characteristics shown in the figure.

That is, in this embodiment, the probe 8 is rotated while the object to be measured 1 is rotated.
is moved so that it is always in focus, and the movement at this time is determined as a displacement from a predetermined position using length measurement 3X LM.

Alternatively, set the focusing position of the objective lens 4 of the f-th probe 8 to match the center of rotation of the object to be measured l, and use this time as a reference to determine the shape (radius) of the object to be measured l from the position of the probe 8. ing.

In addition, in this embodiment, in order to improve measurement accuracy, points PL and P2 are
If the width between points P3 and P4 is configured to be, for example, [μm], it will be difficult to determine the position of the objective lens 4 if the distance is more than ±05 μm from the in-focus state, but the width of points P3 and P4 is equal to the width of point P1.
Since it is set so that t 0 Ount is 100 times as large as that between P2, the deviation can be determined from this characteristic, and focusing control can be performed with high precision and high speed as follows.

FIG. 4 is a flowchart of an embodiment in which focusing control is performed in this embodiment.

In the figure, when the laser 3 is turned on, the reflected light beam from the object to be measured 1 enters the image sensor 7.

The control circuit unit COMP reads information regarding the deviation ID from the in-focus state from the image sensor 7, calculates the deviation amount from the characteristics shown in FIG. ). If it is outside the range, pulse stage XS is driven as necessary from the value of shift ID. Also, if it is within the range, the laser 2 is turned on and the deviation ID from the output of the image sensor 6 is detected.
Calculate.

The amount of deviation is the length S of one step of the pulse stage XS.
If it is larger than L, the pulse stage XS is further driven to bring it closer to the in-focus state. ■When the step length becomes smaller than SL, proceed to the next step.

FIG. 5 shows 70 charts of an example for determining the radius γ and cross-sectional area S of the object to be measured l.

The radius γ of the object to be measured 1 is calculated as the sum or difference between the output signal from the length measuring device Measure.

If the measurement point N is to be measured at intervals of θ radians, it will be N, 2x-1θ.In this case, the radius γ and the cross-sectional area S will be stored in the memory MEMO and displayed on the mDP or printer as necessary. It is output from PR.

Next, in this embodiment, a method for measuring the height of a crab to be measured will be described.

The diameter of the beam incident on the multiplexing measurement object l becomes smaller as the incident position on the objective lens 4 is farther from the optical axis.

For example, in FIG. 1, the spot diameters 2P and 3P of the light beam from the laser 2.3 on the surface of the object to be measured are as shown in FIG. At this time, the reflected light flux when the marked line provided on the surface of the object to be measured is optically scanned from above to below with the spot diameter decreases monotonically.

The entire spot is f! "l" means 1 o'clock when there is no 1 on the A line, and rO means when the entire spot is on the marked line.
If it is indicated as J, it becomes a curve 71.72 as shown in FIG.

The interval between the vertical lines corresponds to one step of the pulse stage ZS, and can be approximately 0.1 μm.

Both tracks 1i71 and 72 intersect at a point 1''.The height β can be determined by measuring between the T points of the upper and lower marked lines at this time.

The position of the intersection T is determined by the length from a certain reference point to the measurement point (measured with a length measuring device) and the length Δρ from the measurement point to point T.

If the length of one step of the pulse stage is 01 .mu.m, the minimum value of the delta flood can be about 0.1 .mu.m.

FIG. 8 is a block diagram of an embodiment for determining the height 2 at this time.

The pulse stages θ31 and θS2 are adjusted to O radians corresponding to the measurement position of the height β. Pulse stage ZS is driven to move probe 8 in the height direction until it passes over a marked line provided on object to be measured l. The reflected light beams Ll-A and L2.A from the laser 2.3 when they cross the marked line are respectively stored in the storage unit MEMO.

When the probe 8 is moved further downward from that point and the reflected light flux from the laser 2 begins to decrease, the pulse stage ZS 1
At each step, the reflected light beams L1 . The data of L2 and the length measuring device ZLM are stored in the storage unit MEMO.

When the probe 8 is further moved downward and there is no change in the reflected light flux from the laser 2.3, each reflected light 1iL
1.! , L2·l are stored in the storage unit MEMO.

Reflected photoelectricity L], L2 data using the above-mentioned constants, z-1,! -Ll・I Normalize as Ll・A−Ll・I. The intersection point T of the double-sided lines is determined from this normalized data.

At this time, the length 2 is calculated by regarding the curves 71 and 72 near the intersection T as substantially straight lines.

In this embodiment, the boundary between the object to be measured and the holder of the object may be used as the gauge line.

(Effects of the Invention) As described above, according to the present invention, it is possible to measure the radial direction and the target direction of the object to be measured with high accuracy without contact using one optical probe, and moreover, It is possible to achieve a displacement measuring device that is compact and has a simple configuration with good operability.

Furthermore, by adopting the two-beam method, it is possible to measure the displacement of the object to be measured at high speed and with high accuracy.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the main parts of an embodiment of the present invention, Figures 2 and 3.
The figure is an explanatory diagram of the light distribution on the image sensor according to the present invention and the output from the image sensor, Figure 4 is a flowchart of focusing control of the probe according to the present invention, and Figure 5 is A flowchart for determining the radius and cross-sectional area of the object to be measured, FIG. 6 is an explanatory diagram when a light beam crosses the marked line on the object to be measured in the present invention, and FIG. 7 is an explanation showing changes in reflected light in FIG. 6. 8 is a flowchart for determining the length β of the object to be measured in the present invention.
In the figure, 1 is the object to be measured, 2.3 is the light source, 4 is the objective lens, and 5
is an imaging lens, 6.7 is an image sensor, 8 is a probe, xs, zs are pulse stages, XLM, ZLM are length measuring devices, LD is a laser driver, SD is a sensor driver, COM-P is a control circuit, MEMO is a This is the storage section. Figure Figure

Claims (6)

[Claims] (1) After the light beams from the two light sources are incident on different positions from the optical axis of the objective lens, they are focused on the object to be measured, and Determining a probe configured to receive the amount of deviation in the direction perpendicular to the optical axis of the reflected light from the object to be measured using two image sensors, a moving mechanism XS that moves the probe in the optical axis direction, and the amount of movement of the moving mechanism XS. Length measuring device XLM and the length measuring device XLM
A displacement device characterized by having a control circuit unit that processes data from the XLM and controls the entire device, and a storage unit that stores various information from the length measuring device XLM, the control circuit unit, etc. measuring device. (2) A moving mechanism ZS that moves the probe in a direction perpendicular to the optical axis, and a length measuring device ZL that measures the amount of movement of the moving mechanism ZS.
2. The displacement measuring device according to claim 1, further comprising: M. (3) Displacement measurement according to claim 2, further comprising a telescoping mechanism that applies a force to the object to be measured in a direction perpendicular to the optical axis, and a measuring device LC that measures the amount of force at this time. Device. (4) irradiation means for irradiating the first and second light beams onto the object whose displacement along a predetermined direction is to be detected; and a second detection means that roughly detects the displacement of the test object along the predetermined direction by receiving a second light beam reflected from the test object. A displacement measuring device characterized by: (5) The first detection means includes means for moving the irradiation means until the first light beam reflected from the object is received near a predetermined position, and detecting the amount of movement of the irradiation means at the time of the movement. and a movement amount detection means, the second detection means comprising:
5. The displacement measuring device according to claim 4, wherein displacement is detected based on a receiving position of the second beam reflected from the object after movement by the moving means. (6) The displacement measuring device according to claim 4, wherein the irradiation means irradiates the test object with the first beam and the second beam at different incident angles.