JPH01174905A - Length measuring device - Google Patents

Abstract

PURPOSE:To enhance measuring accuracy by fixing the measuring reference position of an object to be measured at the center part of the visual field of a microscope, by moving the fine adjustment mechanism due to a parallel distortion beam displacement mechanism by the deviation of the measuring reference position with the center line of the microscope and performing the fixation of the measuring reference position and the calculation of deviation at every moment of said mechanism. CONSTITUTION:A base plate 9 as an object to be measured is placed on a table 6 and moved by a motor 7 to be introduced into the visual field of a microscope 10 and the image thereof is converted to an electric signal to be inputted to an image processor 16. Herein, not only an image is formed based on the input signal but also a measuring reference position is fixed and the deviation of said position with the center of the visual field is calculated. This deviation is outputted to a fine adjustment mechanism 18 constituted of a parallel distortion beam displacement mechanism and the mechanism 18 is displaced by said deviation. Thereafter, the image processor 16 again fixes the measuring reference position and calculates deviation at the displacement position on the basis of the order of a control means 17. This deviation is inputted to the mechanism 18 to displace the table 6 by the deviation. This operation is repeated for the predetermined number of times or until the deviation becomes 0 by the means 17.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measuring device that measures minute lengths with high precision.

[Conventional technology]

In recent years, devices in various technical fields have become smaller or more precise, and as a result, strict control of the dimensions of each part during device manufacturing is required. The equipment is now in demand.

Here, as an object for which highly accurate length measurement is required as described above, a liquid crystal display device used for displaying televisions, computers, etc. will be exemplified and explained.

FIG. 5 is a diagram showing the arrangement of electrodes of a liquid crystal display device.

In the figure, 1 is a substrate, and 2 is a large number of electrodes arranged vertically and horizontally on the substrate 1. For example, in the figure, 6700 electrodes 2 are arranged in one row in the horizontal direction on a substrate 1 having a horizontal length of 400 mm. Each of these electrodes 2 must be arranged at precise intervals from each other. That is, the dimension X++ yi between adjacent electrodes 2 shown in FIG. 5 must be accurate. Therefore, the above-mentioned dimension X1. of the original plate (mask) for manufacturing such an electrode pattern. )'l must be strictly controlled. For this purpose, a highly accurate length measuring device is required. For example, in the example above, dimension x1
is 60 μm, so a length measuring device with accuracy on the order of sub μm is required.

A length measuring device used for measuring such a device will be explained with reference to FIG.

FIG. 6 is a system diagram of a conventional length measuring device. In the figure, 5 is a stage supported on an air surface plate (not shown), 6 is a movable table that can move from side to side on the stage 5, and 7 is a motor that drives the movable table 6. The moving table 6 has a screw that is connected to the rotating shaft of the motor 7 and is screwed onto a shaft (screw shaft) having a spiral thread formed on the circumferential surface, and is configured to move left and right as the motor 7 rotates. It has become. Reference numeral 8 indicates a table fixed to the movable table 7, and reference numeral 9 indicates an original plate placed on the table 8, which is an object to be measured. 9p is an electrode pattern formed on the original plate 9 to create the electrode 2 shown in FIG. The electrode pattern 9p is arranged equally to the arrangement of the electrodes 2 shown in FIG. 10 is a microscope for observing these electrode patterns 9p, 11 is a stand that supports the microscope 10, 12 is a light source that illuminates the original plate 9, and 13 is a light guide tube that supports the light source 12 and guides the light to the microscope 10. 14 is microscope 1
This is a camera that captures an image within the field of view of 0, and outputs an electrical signal according to the image.

15 is a linear encoder, which is composed of a scale 15a and a sensor 15b. The scale 15a is composed of a large number of reflective films arranged on the side surface of the table 8.

This reflective film has a width of, for example, 5 μm and is arranged at intervals of 5 μm. The sensor 15b is composed of a light emitting element slit plate and a light receiving element, and is configured such that the light from the light emitting element reflected by the reflective film is received by the light receiving element via the slit plate. With this linear encoder 15, the moving distance of the table 8 can be measured with accuracy on the order of sub-μm. Such linear encoders are well known.

Reference numeral 16 denotes an image processing device, which is composed of an image processing section 16a and a display section 16b. The image processing section 16a performs a process of displaying an image within the field of view of the microscope 10 on the display section 16b based on a signal from the camera 14, and also performs various processes on the image as described later. The display section 16b is composed of fine particles (pixels) arranged vertically and horizontally at equal intervals. These pixels are light emitting units in the display section 16b, and each pixel selectively emits light,
An image is formed and displayed. Normally, each pixel corresponds to an address in a memory built into the image processing section 16a. The selection of which pixel is to emit light is performed by the image processing section 16a based on a signal from the camera 14. Reference numeral 17 denotes a control device that performs predetermined calculation control in the length measuring device.

Next, the operation of the length measuring device will be explained with reference to the images displayed by the image processing device shown in FIGS. 7(a) and 7(b). First, the original plate 9 is set on the table 8, and the magnification of the microscope 10 is set low (for example, 5 times) to the extent that the entire image of the electrode pattern 9p and its surroundings can be grasped. Next, while observing the field of view of the microscope 10 photographed by the camera 14 and displayed on the display section 16b, the table 8 is moved via the control device 17 (or manually), and the electrode pattern 9p at the end (this electrode 9p+ pattern) is captured in the field of view of the microscope 10. In this state, the magnification of the microscope 10 is set to a high magnification (for example, 200 times). At this time, an image within the field of view of the microscope 10 displayed on the display section 16b is shown in FIG. 7(a). In FIG. 7(a), A is the field of view of the microscope 10, C is a center line corresponding to the center line of the microscope 10, and 9pI' is an image of the electrode pattern 9p+.

Since the electrode pattern 9p+ is magnified by the microscope 10, the image 9p+' is a part of the electrode pattern 9p+, and its edges appear uneven as shown in the figure.By the way, The length measurement on the original plate 9 is
Since measurements are made between the edges of each electrode pattern 9p, if there are irregularities on the edges, measurement is impossible. Therefore, it is necessary to determine the edges by some means.

This edge is determined by detecting the positions of a large number of light emitting pixels at the edge of the image 9p1' in the image processing section 16a and calculating the average value thereof. Note that this edge determination method is well known as the projection distribution method, so a detailed explanation will be omitted. In FIG. 7(a), the determined edge is indicated by the symbol E. The image processing unit 16a determines the interval lI between the center line C and the edge E by counting the number of pixels therebetween (calculating the difference in memory addresses), and outputs the value 11 to the control device 17.

Next, the control device 17 outputs a command signal to the motor 7, moves the table 8, brings the next electrode pattern 9p (this electrode pattern is 9pg) into the field of view of the microscope 10, and displays this on the display section 16b. to be displayed. The amount of movement i of the table 8 at this time is detected by the linear encoder 15 and output to the control device 17. FIG. 7(b) shows the state when the electrode pattern 9pz comes into view.

The same parts in FIG. 7(b) as in FIG. 7(a) are given the same reference numerals. 9pt' shows an image of electrode pattern 9pz. For the image 9p2' of the electrode pattern 9pz, the edge E is determined in exactly the same way as for the image 9p1' of the electrode pattern 9p+, and the distance l! from the center line C is determined. is determined, and this value β2 is output to the control device 17. Here, the amount of movement l detected by the linear encoder 15 is determined by the position on the original plate 9 facing the center line of the microscope 10 in the first field of view and the position on the original plate 9 facing the center line of the microscope 10 in the next field of view. Equal to the distance between the positions. Therefore, in the case of the field of view shown in FIGS. 7(a) and 7(b), the control device 17 controls the input value β,...! l! , 1 are added to obtain the measured value L (L=
'Z, +z, +1). The spacing between each electrode pattern 9p is the spacing between the electrodes 2 shown in FIG.
Similarly to x=..., the edge E of the electrode pattern (9p+) at the end is used as a reference, and is measured as the distance from the edge E using the method described above.

Each electrode pattern 9 in a direction orthogonal to the length measurement direction
Measurement of the interval is performed by once removing the original plate 9 from the table 8, changing the mounting direction by 900 degrees, and placing it on the table 8 again.In order to save this time, the original plate 9 is moved below the stage 5. Stages whose directions are perpendicular to each other are stacked, and another linear encoder is provided on the side surface adjacent to the side where the linear encoder 15 is arranged, so that two axes (X-axis, Y-axis
It is also possible to configure a length measuring device for the axis).

[Problem that the invention seeks to solve]

By the way, it is known that the lens has spherical aberration in -i, and the image at the peripheral part of the lens is distorted with respect to the image at the center of the lens. Therefore, an image that enters the field of view of the microscope 10 will be distorted to some extent in the peripheral areas of the field of view. This image is then photographed by the camera 14 with distortion,
This will be displayed on the display section 16b. Therefore, since the image 9p1' of the electrode pattern 9p+ shown in FIG. 7(a) is located near the periphery of the visual field, it is an image with considerable distortion. On the other hand, since the edge of the image 9p2' of the electrode pattern 9pz shown in FIG. 7(b) is close to the center line C of the visual field, the distortion is small, but the presence of a slight distortion cannot be avoided. As a result, the determined edge E is not an accurate edge, and as a result, there is a problem in that the measurement includes an error and the measurement accuracy decreases.

Furthermore, the microscope 10 has a difference in resolving power between the central part and the peripheral part of its field of view, which causes a difference in the brightness of the image part, and even if the image is the same, the brightness when it is in the central part of the field of view differs. The brightness at the periphery is lower than that at the periphery. By the way, the camera 14 outputs an image existing within the field of view of the microscope 10 to the image processing section 16a as an electric signal proportional to its brightness. Then, the image processing section 16a compares this electric signal (voltage) with a certain voltage level, and when the input voltage is higher than the level, performs a process of causing the corresponding pixel in the display section 16b to emit light. in this case,
The voltage level is usually set to 1/2 of the maximum and minimum values of the input voltage, taking into consideration the reduction in brightness of the light source, the incidence of reflected light from the periphery, and the like. The above process is performed in the 8th step.
Figure (a).

This will be explained using (b) and (c).

FIG. 8(a) is a plan view of the electrode pattern 9p, and FIG. 8(b) is a plan view of the electrode pattern 9p.
) and (C) are waveform diagrams of input signals of the image processing unit, in which the horizontal axis represents the distance within the field of view of the microscope, and the vertical axis represents the voltage of the input signal. The waveform shown in FIG. 8(b) is the waveform when the electrode pattern 9p is in the center of the field of view of the microscope 10 (
FIG. 8(c) shows the waveform (F2) at the peripheral portion. - Voltage level VS+ shown by the dotted chain line
is 1/ of the maximum value and minimum value in each voltage waveform Ft, Ft.
2, which is the set level described above.

Now, if the electrode pattern 9p is located at the center of the visual field as shown in FIG. 8(b), if the brightness decreases for some reason, the input voltage level will also decrease, changing to the waveform FI' shown by the broken line. do. According to this, the setting level v
, 1 also changes to the setting level v3o shown by the two-dot chain line. As a result, a small error ΔlI occurs in the image of the edge portion of the electrode pattern 9p displayed on the display section 16b. However, in the figure, this error Δβ is exaggerated for ease of understanding, and the actual value ΔJ is approximately O.

Next, when the electrode pattern 9p is located at the peripheral part of the visual field as shown in FIG. It changes to the level VSZ shown by the dotted chain line. Therefore, an error Δff1z is generated in the image of the edge portion of the electrode pattern 9p displayed on the display section 16b in the same way as above. This error Δ2□ is also exaggerated in the drawing. However, Fig. 8(b)
An extremely large value (Δ12) compared to the error Δl shown in
Δ2+). That is, if the electrode pattern 9p is located at the periphery of the visual field, a slight change in brightness will cause an error Δ12 in the image at the edge. As a result, the determined edge E lacks accuracy as in the case of the spherical aberration described above, and there is a problem in that the measurement accuracy decreases.

Regarding these problems, we can control the motor 7 to
It is also possible to move the edge of the electrode pattern 9p to the center of the field of view of the microscope 10 by moving the motor 7, the screw shaft connected to the motor 7, and the screw provided on the moving stage 6 and screwed into the screw shaft. The moving mechanism consisting of the above has a slow reaction speed and large inertia due to the weight of the moving stage 6 and table 8. Therefore, when an attempt is made to position the edge in the center of the field of view, hunting occurs, and such positioning is almost impossible. Also, there is a slight play between the screw shaft and the screw,
This also makes the above positioning impossible. Further, even if it were possible to center the edge in the field of view by other means, such as manually, it would take a considerable amount of time. A light source with considerably high output is used as the light source 12 of the microscope 10, and the electrode pattern 9p is irradiated by this light source, so if the above alignment takes time, the electrode pattern 9p will expand due to the radiant heat of the light source. , when the alignment is completed, it means that the alignment has been performed on the expanded edge, and the alignment itself becomes meaningless. Also, if the electrode pattern 9
However, if a considerable amount of time is consumed for alignment (without taking into account the thermal expansion of p), a problem arises in that it takes a long time to measure thousands of electrode patterns 9p.

An object of the present invention is to provide a length measuring device that solves the above-mentioned problems of the prior art, is capable of determining the length measurement reference position of an object to be measured at the center of the field of view of a microscope, and is capable of improving measurement accuracy. is to provide.

[Means for solving problems]

In order to achieve the above object, the present invention includes a table on which an object to be measured is placed, a microscope that faces the table and views the object to be measured,
an image processing device that determines a measurement reference position of an image in the field of view of the microscope and calculates a deviation between the measurement reference position and the center line of the microscope; a moving mechanism that moves the table; A length measuring device comprising a measuring means for measuring, a fine movement mechanism constituted by a parallel deflection beam displacement mechanism, and the fine movement mechanism is moved by the deviation, and each movement determines the measurement reference position and calculates the deviation. A feature [effect] characterized in that the object to be measured is placed on a table, the object to be measured is moved by a moving mechanism to bring it into the field of view of the microscope, and its image is captured. is converted into an electrical signal and input to an image processing device. The image processing device creates an image based on the input signal, determines a measurement reference position serving as a measurement end, and determines the deviation between this measurement reference position and the center of the field of view. This deviation is output to the fine movement mechanism, and the fine movement mechanism is displaced by the deviation. After this displacement is completed, the image processing device again determines the measurement reference position and calculates the deviation at the displaced position according to a command from the control means. The calculated deviation is input to the fine movement mechanism and the table is displaced by the deviation.

This operation is repeated by the control means a predetermined number of times or until the deviation becomes O.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a system diagram of a length measuring device according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 6 are given the same reference numerals, and explanations thereof will be omitted. X indicates the coordinate axis. 17' is the 6th
This is a control device corresponding to the control device 17 shown in the figure. 18
is a fine movement mechanism provided between the moving table 6 and the table 8. The structure of this fine movement mechanism 18 will be explained in detail with reference to FIG.

A fine movement controller 19 controls the driving of the fine movement mechanism 18.

Here, the configuration of the fine movement mechanism 18 shown in FIG. 1 will be explained.

FIG. 2 is a perspective view of the fine movement mechanism. In the figure, 25 is a central rigid body part made of a highly rigid member, and 26a is a central rigid body part 25.
26b is an overhanging portion extending from the central rigid body portion 25 in the direction opposite to the overhanging portion 26a, 27a is an overhanging portion extending from the central rigid body portion 25 in the X-axis direction, and 27b is a central rigid body portion. This is an overhanging portion that overhangs from 25 in the opposite direction to the overhanging portion 27a. 28a and 28b are fixed parts provided at the lower end of the overhanging parts 26a and 26b, respectively, and fixed to the moving table 6; 29a and 29b are tables provided at the upper end of the end parts of the overhanging parts 27a and 27b, respectively, and connecting the table 8. This is the connecting part.

Overhanging parts 26a, 26b, 27a, 27b, fixed part 28
a, 28b, and the table connecting parts 29a, 29b are each made of the same material as the central rigid body part 25, and are processed and formed together with the central rigid body part 25 from one block.

26 FX, , 26 F-b are respectively overhang parts 2
6a.

26b (the parallel flexible beam displacement mechanism will be described later), and are configured symmetrically with respect to the central rigid body portion 25. Parallel deflection beam displacement mechanisms 26 FX, 26F, b work together to
Translational displacement in the axial direction (displacement in the X-axis direction of the central rigid body part 25)
occurs. 27F□ and 27F'yb are parallel deflection beam displacement mechanisms constructed on the projecting portions 27a and 27b, respectively, and are constructed symmetrically with respect to the central rigid body portion 25. The parallel deflection beam displacement mechanisms 27F□ and 27Fyb work together to generate translational displacement in the Y-axis direction (displacement of the central rigid body portion 25 in the Y-axis direction). The above parallel deflection beam displacement mechanism 26
F--226FXb, 27Fy, and 27Fyb are constructed by forming predetermined through holes at predetermined locations of each of the overhang portions 26a, 26b, 27a, and 27b.

The parallel flexible beam displacement mechanism 26F, includes two mutually parallel flat flexible beams 31 formed by forming a through hole 30, and protrudes from the central rigid body portion 25 and the overhang portion 26a into the through hole 30. It consists of a piezoelectric actuator 32) mounted between the protrusions and a strain gauge G affixed to a predetermined location on the flexible beam 31. The other parallel deflection beam displacement mechanisms 26FXb, 27Fy□ 27Fyb have similar configurations. The configuration and operation of the parallel deflection beam displacement mechanism are described in, for example, Japanese Patent Application Laid-Open No. 61-209846.
It is presented in the publication No.

Next, the operation of this fine movement mechanism will be explained. Now, when an equal voltage is applied to each piezoelectric actuator 32 of the parallel deflection beam displacement mechanisms 26F and 26FXb, the parallel deflection beams 31 are deformed in accordance with the applied voltage, and the fine movement mechanism is translated in the X-axis direction. This displacement is caused by the central rigid body portion 25, the parallel deflection beam displacement mechanism 27F, .

27Fyb and the fixed parts 29a and 29b to the table 8, and the table 8 is translated by the same amount in the X-axis direction. Similarly, parallel deflection beam displacement mechanism 27 Fy
When the same voltage is applied to the piezoelectric actuators of - and 26Fyb, the table 8 is translated in the Y-axis direction. Although not used in this embodiment, by driving these parallel deflection beam displacement mechanisms simultaneously, a combined translational displacement can be obtained.

During the displacement operation described above, each strain gauge G detects the deflection of the deflection beam 31 to detect the actual displacement amount of the fine movement mechanism. Therefore, by performing feedback control based on the detected displacement amount, accurate displacement of the fine movement mechanism can be performed.

The configuration and operation of the fine movement mechanism 18 have been described above. Next, the measurement operation in the X-axis direction of this embodiment shown in FIG. 1 will be explained with reference to the flowchart shown in FIG. 3.

First, a predetermined interval E between the electrode patterns 9p is set in the control device 17', and the number N of ears at the measurement interval is set.
Also, the numerical value i at a predetermined address in the memory of the control device 17' is set to 0, and the linear encoder is reset (step S shown in FIG. 3). Note that the above numerical value i is a value for counting the number of measurements.

Next, the control device 17' drives the revolver (not shown) of the microscope 10 to increase the magnification of the microscope 10 to 5 times (step SZ). Thereby, the entire image of the electrode pattern 9 at the end can be visually observed within the field of view of the microscope 10. The measurer manually selects the endmost electrode pattern 9p.
capture it in your field of view and focus on it. The control device 17' stores the focus position at that time (step S3). In this state, the magnification of the microscope 10 is increased from 5x to 20x using the revolver.
The magnification is switched to 0x (step S4), and the previously stored focus position is automatically set (step SS). As a result, the image within the field of view of the microscope 10 is input as an electrical signal to the image processing unit 16a via the camera 14, and the display unit 1
6b as shown in FIG. 7(a).

In this state, the control device 17' controls the image processing section 16a.
to determine the edge and calculate the deviation between the determined edge and the center of the field of view (Step Sa)
. The image processing unit 16a executes edge determination and deviation calculation through the processing described above, and sends the calculated deviation to the control device 17'.
Output to.

The control device 17' determines whether the deviation is O, that is, whether the determined edge is in the center of the field of view (step S
? ). In many cases, this deviation will not be O. If the deviation is O, the process moves to step SII, which will be described later.

If the deviation is not 0, the control device 17' outputs the deviation to the fine movement controller 19, and drives the fine movement mechanism 18 (step S8). The fine movement controller 19 accurately displaces a predetermined parallel deflection beam displacement mechanism by the above deviation by feedback control. As a result, the table 8 moves by that amount, and the previously determined edge coincides with the center of the field of view.

By the way, since the previously determined edge was determined at a position shifted from the center of the field of view, it contains errors as described above and is not an accurate edge.

Therefore, the control device 17' again controls the image processing section 17 with the edge positioned at the center of the field of view as described above.
6a to determine the edge and calculate the deviation (step S9).

In response to this command, the image processing unit 16a again performs edge determination processing at the center of the field of view (this determined edge is
(different from the previously determined edge), the deviation is calculated and outputted to the control device 17'.

The control device 17' determines whether this deviation is 0 or not in step S.
,. ), if not 0, repeat steps S, ~SIG. By repeating this, the edge is determined closer to the center of the field of view, and the finally determined edge coincides with the center of the field of view.

Here, the control device 17' reads the detection signal of the sensor 15b of the linear encoder 15 (step S++).

Let this value be L. Next, the control device 17' calculates the measured value (that is, the calculation of the length measurement result) by subtracting the previously read value L' from the above read value (
Step S, 2). In this case, since the endmost electrode pattern 9p is within the field of view of the microscope 10 and length measurement has just started, the value and the value L' are equal, and step S
The calculation result of 1□ is naturally O. The value read in step St+ is then stored as value L' (step S, 3
). Next, the controller 17' adds 1 to the value i stored at a predetermined address in the memory (step 514).

Then, it is determined whether the value i has become (N +'l) (step 514). In this case, since the value i is not (N+1), the process moves to step SI&. Procedure SI6
, the control device 17' drives the motor 7 and drives the table 8 only to the set value. This drive is performed by sensor 15b
This is done by reading the output value of and using feedback control. As a result, the next electrode pattern 9p will move into the field of view of the microscope 10. For this electrode pattern 9p, the control device 17' repeats the steps S and S+s again.

As a result of the above processing, the edge of each electrode pattern 9p is determined at the center of the visual field, and the finally determined edge always coincides with the center of the visual field. Therefore, the moving distance of the table 8 from the previous final edge determination to the current final edge determination is the interval between adjacent electrode patterns 9p, which can be determined by the calculation in step S. In step SI5, the value i is a number (N+1)
All measurements are completed when the value is equal to .

Note that when measuring only in the X-axis direction as described above,
It is clear that the fine movement mechanism may also consist of only a pair of parallel flexure beam displacement mechanisms in symmetrical positions.

In this way, in this embodiment, the fine movement mechanism consisting of the parallel deflection beam displacement mechanism is operated to repeatedly determine the edge at the center of the field of view until the center of the field of view and the edge coincide. Accurate edge determination can be performed without causing errors due to spherical aberration of the lens or differences in resolution between the central and peripheral parts of the microscope, and as a result, highly accurate measurements can be performed. In addition, since a parallel deflection beam displacement mechanism driven by a piezoelectric element is used, the fine movement mechanism can be operated at high speed and is less affected by the heat of the light source, which also improves measurement accuracy. Can be done.

FIG. 4 is a system diagram of a length measuring device according to another embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. X and Y indicate coordinate axes. This embodiment is a two-axis length measuring device capable of measuring in the X-axis and Y-axis directions. 5x and 5y are stages each equipped with a moving mechanism in the X-axis and Y-axis directions, and the stage 5X
is installed on the stage 5Y so as to be movable in the Y-axis direction. 7X is a motor that moves the moving table 6 in the X-axis direction, 7Y is a motor that moves the moving table 6 in the X-axis direction, 7
Y is a motor that moves the stage 5X in the Y-axis direction. 17" is a control device. This control device 17" is the first
The only difference is that the control device 17 shown in the figure is a control device for only one axis (X-axis), whereas it is a control device for two axes (X-axis, Y-axis), and the basic operations are the same for both. It's the same.

36 is a laser head, for example, a two-frequency laser head is used. This laser head outputs laser beams with slightly different frequencies f, , f2.

37 is a beam splitter that splits the laser beam from the laser head 36 into a linear direction and a direction perpendicular thereto.

38X and 38Y are interferometers that output only the laser beam of frequency f1 among the laser beams. Reference numeral 39 denotes an L-shaped mirror fixed to the table 8, and has a portion 39X that performs reflection in the X-axis direction and a portion 39Y that performs reflection in the Y-axis direction. 40X and 40Y are the X axis and Y axis, respectively.
axis receiver and interferometer 38X.

A predetermined signal is output based on the frequency of the laser beam sent from 38Y. 41 is a pulse comparator, which connects the signal from the laser head 36 and the receivers 40X, 40
The amount of displacement in the X-axis direction and the Y-axis direction is calculated based on the signal from Y, and is outputted to the control device 17''. Laser head 36, beam splitter 37, interferometer 38X, 38YSL type mirror 39, receiver 40x
.

40Y1 and the pulse comparator 41 constitute a laser length measuring device.

The length measurement in this embodiment is performed by the same operation as the length measurement operation in the previous embodiment for each of the X-axis and Y-axis, except that the displacement amount of the table 8 is detected by a linear laser measurement instead of the linear encoder 15. The only difference is that it is performed with long tools. Therefore, the explanation of the operation of this embodiment will be limited to an outline of the X-axis length measurement operation of the laser length measurement device.

Each laser beam from the laser head 36 is split by a beam splitter 37, one of which is sent to the interferometer 3.
8X and frequency f.

The portion 39X of the mirror 39 is irradiated with only the laser beam.

When the table 8 is displaced in this state, Doppler modulation occurs in the irradiated laser beam due to the Doppler effect, and the frequency of the laser beam reflected from the mirror portion 39X is (r+
±Δf1). This reflected laser light passes through an interferometer 38X and is input to a receiver 40X together with a laser light having a frequency of ft.
Based on the frequency of two laser beams (fz − (fl ±Δ
f.

)) is calculated, and a signal corresponding to the calculation is output.

On the other hand, the laser head 36 outputs a signal Cft r+) corresponding to the difference in frequency between the respective laser beams, and inputs it to the pulse comparator 41 together with the signal from the receiver 40X. The pulse comparator 41 calculates ((rz −fl ) −ft (, fl±Δfl
) ) is executed, and as a result, a signal ±Δf is extracted. This signal ±Δf1 is a signal proportional to the displacement of the table 8, and is input to the control device 17'' and used as a numerical value in step P in the previous embodiment.

In this way, in this example, the displacement in the X-axis and Y-axis directions is measured using a laser length measuring device instead of the linear encoder in the previous example, so that more accurate measurement is possible. In addition, in the case of two-axis measurement, it is possible to save the time and effort of once removing and then attaching the original plate.

In the above embodiments, the determination of the edge at the center of the field of view is repeated until the deviation becomes O, but the edge is moved almost to the center of the field of view by one drive of the fine movement mechanism. Therefore, the edge at the center of the visual field can be determined a predetermined number of times, from once to several times.

Furthermore, in the description of each of the above embodiments, an example of measuring the distance between electrode patterns has been described, but the present invention is not limited to this, and can be applied to various other length measurements.

〔Effect of the invention〕

As described above, in the present invention, the length measurement reference position of the object to be measured is moved to the center of the field of view of the microscope using the parallel deflection beam displacement mechanism, and the position is determined. It is possible to accurately determine the length measurement reference position without being affected by resolution, and thereby the measurement accuracy can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a length measuring device according to an embodiment of the present invention, and FIG.
The figure is a perspective view of the fine movement mechanism shown in FIG. 1, FIG. 3 is a flow chart explaining the operation of the device shown in FIG. 1, and FIG. 4 is a system diagram of a length measuring device according to another embodiment of the present invention. FIG. 5 is a layout diagram of electrodes of a liquid crystal display device, FIG. 6 is a system diagram of a conventional length measuring device, and FIG. 7 is a diagram of its signal waveform. 5X, 5Y... Stage, 6...
...Motor, 8
......Table, 9...Original plate, 9p...Electrode pattern, 10...
・・・・・・Microscope, 14・・・・・・Camera,
15X, 15Y... Near encoder, 16... Image processing device, 17', 17
”・・・・・・・・・Control device, 18・・・・・・・・・
・Fine movement mechanism, 19...Fine movement controller, 36...Laser head, 38X, 38
Y/Old...Interferometer, 39...
...L type mirror, 40X, 40Y...
・Receiver, 41...Pulse comparator. Figure 1 6; Platform 8: Tea Ishi 9: #, Board 10: Field I Soft Ken 14: f7 Metsu 15: Rini R+Shicode Figure 2 31: Tawa Gai 32: Miden Ryo Gutuator No. 4 Figure 40X+40Y 'L Sits- 5thffl Figure 7 Figure 8・12

Claims (3)

[Claims] (1) A table for mounting the object to be measured, a microscope facing the table for viewing the object to be measured, and determining a measurement reference position of an image in the field of view of this microscope, and a center between this measurement reference position and the microscope. In a length measuring device that includes an image processing device that calculates a deviation from a line, a moving mechanism that moves the platform, and a measuring device that measures the moving distance of the platform, a micro-movement device that includes a parallel deflection beam displacement mechanism is used. A length measuring device comprising: a mechanism; and a control means for moving the fine movement mechanism by the deviation and determining the measurement reference position and calculating the deviation every time the fine movement mechanism is moved. (2) The length measuring device according to claim (1), wherein the measuring means is a linear encoder. (3) A length measuring device according to claim (1), wherein the measuring means is a laser length measuring device.