JP2001272212A - Distortion measuring method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distortion measuring method and apparatus which achieve a lower cost, a fast measurement and a smaller shape. SOLUTION: The apparatus contains a polarized beam splitter 15, which makes a measuring beam from a measuring light source 11 pass intact to irradiate a work 14, a corner cube prism 16 which receives the reflected beam of the measuring beam from the work 14 and returns the beam at an angle parallel therewith to re-irradiate the work 14, a return mirror 18 which receives the beam re-reflected of the measured beam which is re-irradiated to be returned back in the direction prescribed by an angle of incidence thereof and a quarter- wave λ plate 17. The beam returned by the return mirror 18 is put back to a polarized beam splitter 15 in a path opposite top the previous path thereof, so as to extract the return beam deviated by half the wavelength λ from the polarized beam splitter. Thus, the amount of positional deviation of the return beam is measured, to determine the distortion of the work 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for measuring a strain, and more particularly to a method and a device for measuring a strain suitable for measuring a minute strain in a minute object.

[0002]

2. Description of the Related Art Recently, a laser processing apparatus for irradiating a workpiece with a laser beam to apply distortion has been proposed (for example, Japanese Patent Application No. 10-103920). This laser processing device
The irradiated portion is locally heated by irradiating one main surface of the plate-shaped work with laser light. Then, tensile (shrinkage) stress accompanying cooling after local heating is left in the irradiated portion,
The work is deformed so that the main surface on the side including the irradiated portion becomes concave.

[0003] Such processing is applied to a minute magnetic head slider used in a magnetic recording device such as a hard disk drive. This is because the magnetic head slider needs to be curved with a small curvature so that the surface facing the recording medium becomes convex in order to avoid adhesion to the recording medium.

[0004]

In the above-described laser processing apparatus, it is necessary to measure the amount of distortion of the processed work. In this case, if the workpiece is transported to another location after processing and the amount of distortion is measured, the number of steps, transport systems, and locations for measuring the amount of distortion increase, which is not preferable.

On the other hand, when the object to be measured, that is, the work is a minute object such as the magnetic head described above, the amount of distortion is on the order of several nm to several tens nm, and precise measurement accuracy is required. As the distortion amount measuring device, for example, a device called a scanning white interferometer using an interferometer is provided. In this interferometer, a light-dark line interference fringe generated from a difference in optical path between the reference light and the measurement light is used. That is, the light beam from the light source is split into two in the interferometer, and one is irradiated on the internal reference surface and the other is irradiated on the measurement object. The two reflected lights reflected from the internal reference surface and the measurement object surface are recombined inside the interferometer and generate interference fringes through synthesis. The amount of distortion is measured by observing the interference fringes.

However, the measuring apparatus using such an interferometer has problems that the cost is high, the measuring speed is low, and the shape is large.

Therefore, an object of the present invention is to reduce the cost,
It is an object of the present invention to provide a strain amount measuring method and a measuring device capable of increasing the measuring speed and reducing the shape.

Another object of the present invention is to provide a strain amount measuring method and a measuring device capable of measuring a strain amount with high accuracy without being affected by a tilt angle of a work.

Still another object of the present invention is to provide an in-line type distortion amount discriminating apparatus capable of measuring a distortion amount at the same station as laser processing.

Another object of the present invention is to provide a distortion amount discriminating apparatus which can be used in a state of being incorporated in a laser processing apparatus.

[0011]

According to the present invention, a measuring beam from a measuring light source is irradiated on a measuring object, and a reflected beam from the measuring object is passed through a prism to form an angle parallel to the reflected beam. Returning the measurement object to the measurement object and irradiating the measurement object again, and measuring a displacement amount of a re-reflected beam from the measurement object from a reference position, thereby measuring distortion of the measurement object. A method is provided.

According to the present invention, the measuring beam from the measuring light source is irradiated to the measuring object through the isolator means, and the reflected beam from the measuring object is returned at an angle parallel to the reflected beam by passing through the prism. The object to be measured is re-irradiated, and the re-reflected beam from the object to be measured is turned back by the beam reflecting means. And measuring the amount of displacement of the return beam from the reference position to thereby measure the distortion of the object to be measured.

According to the present invention, there is further provided a measuring light source for generating a measuring beam and irradiating the measuring object, and receiving a reflected beam of the measuring beam from the measuring object, and forming the reflected beam in parallel with the reflected light beam. A prism for returning the object at an angle to re-irradiate the object to be measured, and a unit for receiving a re-reflected beam of the re-irradiated measurement beam and measuring a positional shift amount of the re-reflected beam from a reference position. Is provided.

According to the present invention, further, a measurement light source for generating a measurement beam and irradiating the measurement object, isolator means disposed between the measurement light source and the measurement object, A prism for receiving the reflected beam of the measurement beam from the object, returning the reflected beam at an angle parallel thereto and re-irradiating the object to be measured, and receiving a re-reflected beam of the measurement beam re-irradiated by the prism Beam reflecting means that returns in a direction defined by the incident angle, and returns the beam returned by the beam reflecting means to the isolator means in a path opposite to the path described above, and returns a beam from the isolator means. And a means for measuring the amount of displacement of the return beam from the reference position is provided.

In any of the distortion amount measuring method and the distortion amount measuring apparatus, the isolator means is a polarizing beam splitter, and is provided in a path from passing through the polarizing beam splitter to returning to the polarizing beam splitter. The method is characterized in that it includes a phase difference plate arranged and extracts a return beam having a phase shift.

In each of the distortion amount measuring method and the distortion amount measuring apparatus, the phase difference plate is (（).
A λ plate (where λ is the wavelength of the measurement beam), and the phase of the extracted return beam is shifted by (１ ／) · λ.

In the distortion measuring apparatus, an optical path between the prism and the beam reflecting means may be formed by one optical medium.

In the distortion measuring apparatus, the prism is a corner cube prism, the beam reflecting means is a reflecting film, and the optical medium is defined in a hexagonal shape having at least an upper side and a lower side parallel to each other. In a polyhedron, a reflection film is formed on a part of a surface defined by one of two sides adjacent to the upper side, and a corner cube prism is integrally formed on a surface defined by the other side. The object to be measured is arranged on the lower side, and the remaining portion of the surface on which the reflection film is formed is an incident surface of the measurement beam.

According to the present invention, there is further provided a measurement light source for generating a measurement beam and irradiating the measurement object with the light source, and an isolator means disposed between the measurement light source and the measurement object. A prism that receives a reflected beam of the measurement beam from the measurement object, returns the reflection beam at an angle parallel thereto and re-irradiates the measurement object, and a re-reflected beam of the measurement beam re-irradiated by the prism. And a plurality of sets of beam reflecting means that return in a direction defined by the incident angle.The measuring beam from the measuring light source is split into a plurality of beams by a light splitting means. The folded beam is returned to each set of the isolator means in a path opposite to the path in each set, and the return beam is returned from the isolator means. And a means for measuring the amount of displacement of the return beam from the reference position in each set, and a distortion amount measuring device characterized by measuring the distortion of the measurement object on a plurality of axes. Provided.

In this distortion amount measuring apparatus, the isolator means is a polarizing beam splitter, and further includes a plurality of phase difference plates arranged in a path from passing through the polarizing beam splitter to returning to the polarizing beam splitter. Each set includes a beam that is passed through a retarder in each set to extract the out-of-phase return beam.

Also in this distortion measuring apparatus, the retardation plate is a (1/4) .lambda. Plate (where .lambda. Is the wavelength of the measurement beam), and the phase of the extracted return beam is (1/1). 2) It is shifted by λ.

In this distortion amount measuring apparatus, an optical path between the plural sets of prisms and the plural sets of beam reflecting means may be formed by one optical medium.

In this distortion amount measuring apparatus, the plural sets are two sets, the prism is a corner cube prism, the beam reflecting means is a reflection film, and the optical medium has an upper surface and a lower surface which are square and parallel to each other. A reflecting film is formed on at least a part of one of two faces adjacent to two sides of one of the two sets of two sides parallel to each other on the upper surface, and the other face is a polyhedron. Is formed integrally with a corner cube prism to form one set of optical paths, and one of two faces adjacent to the other two sides of the two sets of two parallel sides of the upper surface. A reflection film is also formed on at least a part of the surface, a corner cube prism is integrally formed on the other surface to form another set of optical paths, and a measurement object is arranged on the lower surface side,
The remaining portion of the surface on which the reflection film of each set is formed is an incident surface of the measurement beam in each set.

According to the present invention, there is further provided an optical medium characterized by being a polyhedron including a surface reflecting a laser beam and three surfaces forming a corner cube prism.

This optical medium further includes a surface transmitting the laser beam, and the surface transmitting the laser beam and the surface reflecting the laser beam form one surface. I do.

According to the present invention, further, the measuring beam from the measuring light source is irradiated on the measuring object, and the reflected beam from the measuring object is returned at an angle parallel to the reflected beam by passing through the prism. A deformation amount measuring method is provided, wherein the deformation of the measurement object is measured by irradiating the object again and measuring the amount of displacement of a re-reflected beam from the measurement object from a reference position. .

According to the present invention, further, the measuring beam from the measuring light source is irradiated to the measuring object through the isolator means, and the reflected beam from the measuring object is returned at an angle parallel to the reflected beam by passing through the prism. The object to be measured is re-irradiated, and the re-reflected beam from the object to be measured is turned back by the beam reflecting means. And measuring the amount of displacement of the return beam from the reference position to measure the deformation of the measurement object, thereby providing a deformation amount measuring method.

According to the present invention, there is further provided a measuring light source for generating a measuring beam and irradiating the measuring object, and receiving a reflected beam of the measuring beam from the measuring object, and forming the reflected beam into a parallel beam. A prism for returning the object at an angle to re-irradiate the object to be measured, and a unit for receiving a re-reflected beam of the re-irradiated measurement beam and measuring a positional shift amount of the re-reflected beam from a reference position. Is provided.

According to the present invention, further, a measurement light source for generating a measurement beam and irradiating the measurement object, isolator means disposed between the measurement light source and the measurement object, A prism for receiving the reflected beam of the measurement beam from the object, returning the reflected beam at an angle parallel thereto and re-irradiating the object to be measured, and receiving a re-reflected beam of the measurement beam re-irradiated by the prism Beam reflecting means that returns in a direction defined by the incident angle, and returns the beam returned by the beam reflecting means to the isolator means in a path opposite to the path described above, and returns a beam from the isolator means. And a means for measuring the amount of positional deviation of the return beam from the reference position is provided.

An optical path between the prism and the beam reflecting means, including the beam reflecting means, may be formed by one optical medium.

The prism is a corner cup prism,
The beam reflecting means is a reflecting surface, and the corner cube prism has at least seven surfaces including three surfaces, a surface facing the object to be measured, the beam reflecting surface, and two surfaces adjacent thereto. An optical medium comprising a polyhedron is disposed in a path between the isolator means and the object to be measured.

Preferably, the measuring light source is a He-Ne laser light source or a semiconductor laser light source.

The means for measuring the amount of displacement may include a CCD camera.

Further, as a means for measuring the amount of the positional deviation, a PSD (Position Sensing Degree) is used.
(Tector).

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. In FIG. 1, the distortion amount measuring apparatus includes a measuring light source 11 for generating a measuring beam having a wavelength λ, a beam expander 12 for enlarging a cross-sectional shape of the measuring beam, and a cross-sectional shape of the expanded measuring beam. 13 for narrowing the workpiece to a desired diameter, and the work 1
4, that is, a polarizing beam splitter 15 that irradiates the object to be measured at an angle θ1. As the measurement light source 11, a He-Ne laser light source called a pointing laser or a semiconductor laser light source is used.

The measurement beam applied to the work 14 is reflected at an angle θ2. A corner cube prism 16 is arranged in this reflection direction. The corner cube prism 16 is, for example, well known,
Although a triangular pyramid-shaped glass body is integrally formed on one surface side of the cylindrical glass body, it is simplified in the drawings referred to hereinafter.

The reflected beam of the measurement beam from the work 14 is incident on the other surface of the cylindrical glass body and is reflected on one surface of the triangular pyramid, and the reflected light is incident on an adjacent surface and is reflected there. Further, it is incident on the adjacent surface. Then, the light is reflected on the other surface of the cylindrical glass body on that surface. As described above, the reflected beam that has entered the corner cube prism 16 is reflected three times inside, is returned at an angle parallel to the incident reflected beam, and is re-irradiated to the work 14 at an angle θ3.

The re-irradiated measuring beam is applied to the work 1 again.
4 at an angle θ4. A (1/4) .lambda. Plate 17 and a folding mirror 18 are arranged in the reflection direction of the re-reflected beam. The (1/4) .lambda. Plate 17 is for shifting the phase of the incident beam by (1/4) .lambda. The folding mirror 18 reflects the incident beam in a direction defined by the incident angle, as will be described later in detail. In particular, when the upper surface of the work 14 is a completely flat surface, the return mirror 18 receives the beam from the (1/4) .lambda. Plate 17 at an incident angle of 90 degrees and reflects the beam in the same direction as the incident direction. It is arranged to let. The beam that has been turned back by the turning mirror 18 and passed through the (１ ／) · λ plate 17 is
It has a phase shift of (1/2) · λ. Such a plate is called a retardation plate.

From another point of view, the deflection beam splitter 15 transmits the S deflection and reflects the P deflection. On the other hand, the (1/4) .lambda. Plate 17 is for, for example, making the S-deflection a right-handed circular deflection and the left-handed circular deflection a P-deflection. As a result, the deflection beam splitter 1
When the S-polarized measurement beam is made incident on 5, the P-polarized light can be extracted on the screen 20 side described later.

Here, assuming that the upper surface of the work 14 is a completely flat surface, θ1 = θ2 = θ3 = θ4, and
The beam turned back by the turning mirror 18 is the work 1
9-corner cube prism 16-work 19 path
That is, the light beam reaches the polarizing beam splitter 15 along a path exactly the same as the path at the time of incidence and in the opposite direction. This is the same (θ1 = θ2 = θ3 = θ4) even if the work 14 is totally tilted due to the tilt of the table 19 on which the work 14 is placed. In other words,
The optical path configured as described above means that it is not affected by the inclination of the work 14.

The polarization beam splitter 15 has a function of extracting a return beam shifted from the incident beam by (1/2) .lambda. The extracted return beam is emitted at an angle of 90 degrees. A screen 20 is arranged in this emission direction, and the return beam is projected as a spot. A CCD camera 21 with a microscope is arranged adjacent to the screen 20. The CCD camera 21 captures an image of the spot projected on the screen 20.

When the work 14 is distorted, the upper surface is not flat. In this case, the angles θ2, θ
3 and θ4 are different from the angle θ1, and the beam turned back by the turning mirror 18 reaches the CCD 21 through a path in a direction slightly different from the path at the time of incidence. Therefore, when the work 14 is distorted, the position of the projected spot slightly deviates from the position where the upper surface of the work 14 is a flat surface. The position when the upper surface of the work 14 is a flat surface is set as a reference position.

The captured image is sent to an image processing device (not shown), and the amount of distortion is calculated from the position of the spot in the image, that is, the amount of displacement from the reference position.

The relationship between the amount of distortion and the amount of displacement will be described with reference to FIG. Here, for the sake of convenience, the measurement beam from the polarizing beam splitter 15 is incident on and reflected from the work 14 in a path shown by a two-dot chain line, and the beam from the corner cube prism 16 is re-worked in a path shown by a thick line.
4 is assumed. In FIG. 2, the thin line indicates the work 1
When there is no distortion in the mirror 4, the mirror 1 is turned back from the work 14.
8 shows the path of the re-reflected beam incident on the reference numeral 8. On the other hand, the thick line indicates that the workpiece 14 has a distortion amount of θ (= 0.0055 degrees and 2
4 shows a path of a re-reflected beam that enters the return mirror 18 from the work 14 and is reflected when the distortion amount is 4 nm).

As described above, when there is no distortion in the work 14, the re-reflected beam is applied to the folding mirror 18 by 90 degrees.
The light enters at an angle of degrees and is reflected in a direction completely opposite to the incident direction. On the other hand, when the work 14 has distortion, the angle between the incident direction and the reflection direction with respect to the work 14 is 2θ.
And the angle between the incident direction and the reflection direction with respect to the reflecting mirror 18 is 4θ (= 0.0220 degrees). 4
Assuming that θ = Δθ and the optical path length from the exit end face of the corner cube prism 16 to the screen 20 is 500 mm, the amount of displacement is 1000 × sin Δθ = 0.384
mm. In this way, the distortion angle, and thus the distortion amount, can be calculated back from the displacement amount. Of course, the correspondence between the amount of distortion and the amount of displacement is measured in advance for each type of the work 14, and the correspondence and the table are stored in a storage device. You can also know.

Here, for example, if the work 14 is square, the irradiation position of the measurement beam on the work 14 is
As shown in FIG. 3 (a), A1, A near the corner
2, B1, or B2. Then, FIG. 3 (b)
Alternatively, as shown in FIG. 3 (c), the amount of distortion in which the main surface is convex or concave can be measured.

Note that instead of the CCD camera 21, a PSD
(Position Sensing Detecto
What is called r) may be used. This PSD is
The position of the spot on the screen 20, is measured on X-Y coordinate is to be output, expressed in the coordinate data from the reference position coordinates (x = 0, y = 0 ) (x 1, y 1). The (1/4) .lambda. Plate 17 is a polarizing beam splitter 1
5 may be arranged near the exit side.

The deflection beam splitter 15 and (1 /
4) The λ plate 17 and the folding mirror 18 may be omitted. The reason for using these is that the path of the measurement beam at the time of incidence and the path of the measurement beam at the time of reflection have substantially the same optical axis so as to reduce the size of the device configuration. . For this purpose, the above-described components are used as an example of an isolator for isolating the measurement beam at the time of incidence and the measurement beam at the time of reflection. If miniaturization can be ignored, the deflection beam splitter 15, the (1/4) .lambda. Plate 17, and the folding mirror 18 may be omitted, and the screen 20 and the CCD camera 21 may be arranged at the position of the folding mirror 18. good.

A second embodiment of the present invention will be described with reference to FIGS. In FIG. 4, the distortion amount measuring apparatus according to the second embodiment is different from the first embodiment in that the (1/4) .lambda.
5 near the exit side, and the measurement beam
4) A path from exiting the λ plate 17 to returning therefrom is formed by a polygonal optical medium. This is shown in FIG.
In the configuration (1), the corner cube prism 16 and the turning mirror 18 are required to be arranged with an accurate positional relationship, and the alignment work becomes more difficult as the distance from the work 19 increases.

That is, the corner cube prism 16,
The optical path between them, including the folding mirror 18, is
It is formed of an optical medium 30 made of two glasses. Therefore, the optical medium 30 is a nine-sided body whose cross-sectional shape is defined by a hexagon whose at least upper and lower sides are parallel to each other, and a surface 30-defined by one of two sides adjacent to the upper side.
A reflection film 32 is formed on one half of the surface, and a corner cube prism 33 is integrally formed on a surface defined by the other side. And the other half of the surface 30-1 is (1/4)
An incident surface 34 for the measurement beam from the λ plate 17. Further, the work is arranged below the surface defined by the lower side of the hexagon.

The measurement beam emitted from the (1/4) .lambda. Plate 17 passes through the optical medium 30 from the incident surface 34 and irradiates a work disposed below the same. The measurement beam applied to the work is reflected by the work and enters the corner cube prism 33. The corner cube prism 33
As described above, the reflected beam from the work is received, and the reflected beam is reflected three times so that the reflected beam is returned at an angle parallel to the incident reflected beam and the work is re-irradiated.

The re-irradiated measurement beam is reflected again by the work, and this re-reflected beam is reflected by the reflection film 32 acting as a return mirror. The reflected beam travels through the optical medium 30 in a path opposite to the above,
The light is emitted from the incident surface 34. The emitted beam is (1 /
4) The light enters the polarization beam splitter 15 through the λ plate 17. The components in the subsequent paths and their operations are exactly the same as those in FIG.

Referring to FIG. 6, in the second embodiment, the present distortion amount measuring apparatus can be used in a state of being incorporated in a laser processing apparatus. This is realized by setting the upper surface 30-2 defined by the upper side in the above-mentioned hexagonal cross-sectional shape as an incident surface of a laser beam (for example, a YAG laser beam) for giving distortion to the work 14. The amount of distortion measured in this case is
The amount of distortion is such that the upper surface becomes concave. FIG. 6 shows an example of a specific size of the optical medium 30 when the optical medium 30 is incorporated in a laser processing apparatus. The unit of length is mm
It is. By using such an optical medium 30, immediately after performing the distortion processing by the laser beam, it is possible to measure the amount of distortion caused thereby. This allows
If the measured value of the distortion amount is smaller than the reference value, it is possible to realize the additional irradiation of the laser beam.

Incidentally, also in the second embodiment, the deflection beam splitter 15 and the (1/4) .lambda. Plate 17 may be omitted. However, in this case, the reflection film 32 in the optical medium 30 is deleted, and the configuration is such that the re-reflected beam from the workpiece is incident on the screen 20 described with reference to FIG. In practice, the path of the measurement beam entering the optical medium 30 and the path of the measurement beam emerging from the optical medium 30 are very close, so that the measurement beam emerging from the optical medium 30 is reflected by means such as a reflecting mirror. In addition, it is necessary to provide a structure in which the angle is changed once by 90 degrees with respect to the optical axis and then guided to the screen.

By the way, as described with reference to FIG.
In the second embodiment, the work 14 is irradiated with the measurement beam at only one location. This means that the measurable distortion amount is in one axis direction as shown in FIGS. 3 (b) and 3 (c). On the other hand, there is a case where the workpiece 14 is subjected to processing in which not the distortion in the one-axis direction but the synthesis in the orthogonal two-axis directions, that is, a process of giving a torsion. In order to measure the amount of such distortion,
As shown in FIG. 7A, the irradiation of the measurement beam is performed at A1.
And B1 or A2 and B2.
According to such two irradiations, the amount of twist distortion as shown in FIG. 7B can be measured.

Referring to FIGS. 8 and 9, a description will be given of a third embodiment in which the amount of distortion on two axes can be measured. According to the principle of the third embodiment, it can be considered that two sets of the distortion amount measuring devices shown in FIG. 1 are provided. However, the measurement light source 11 can be shared. In this case, the measurement beam from the measurement light source 11 may be split into two by a light splitting unit such as a semi-transmissive mirror, and may be incident on the polarization beam splitters in each set.

The distortion amount measuring apparatus according to the third embodiment is also the same as the (1/4) .lambda. Plate 17 in the first embodiment.
Are arranged near the exit side of each set of polarization beam splitters 15, and the measurement beam of each set is (（) of each set.
A path from exiting the λ plate 17 to returning therefrom is formed by a polygonal optical medium common to two sets. That is, the optical path between them including the two sets of corner cube prisms 16 and the two sets of folding mirrors 18 is formed by an optical medium 40 of one glass.

For this purpose, the optical medium 40 has an upper surface 40-.
The two surfaces 1 and the lower surface 40-2 are square and parallel to each other, such as an octahedron, and are adjacent to one of the two sides of the two sets of two parallel sides of the upper surface 40-1. A reflection film 42 is formed on one half 40-3 of 40-3, 40-4, and a corner cube prism 43 is integrally formed on the other surface 40-4, so that one set of optical paths is formed. Is formed. A reflection film is also formed on one half of two surfaces 40-5, 40-6 adjacent to the other two sides of the two sets of two sides parallel to each other on the upper surface 40-1. And the other surface 40-6 is integrally formed with a corner cube prism 44 to form another set of optical paths. Each set of faces 40-3, 40-
The other half of 5 is the entrance surface 45 (only one is shown) of the measurement beam from the (1/4) .lambda. Plate 17 in each set. In addition, a work is arranged below the lower surface 40-2 of the optical medium 40.

The optical medium 40 shares the medium between the upper surface 40-1 and the lower surface 40-2 with two sets of optical paths. Note that, in the octahedron shown in FIG. 9, for example, the medium is also interposed between the surface 40-3 and the surface continuing below it, and the surface 40-6 and the surface continuing below it,
This portion does not need to be provided because it does not function as an optical path. In this case, as shown by a broken line in FIG.
A space is formed between the triangular prism-shaped body defined by 3 and the surface continuous below the same, and the triangular prism-shaped body defined by the surface 40-6 and the surface continuous below the same. The same applies to the remaining part, and the shape is still polyhedral.

According to the optical medium 40, in one set, the light incident surface 4 along the path indicated by the arrow I 1 shown in FIG.
The measurement beam incident on 5 is reflected by the corner cube prism 43 via the work and reaches the reflection film 42, where it is reflected and exits from the entrance surface 45 through the reverse path. In the other set, the measurement beam incident on the incident surface along the path indicated by the arrow I2 shown in FIG. 8 is reflected by the corner cube prism 44 via the work and reaches the reflective film, where it is reflected and reversed along the reverse path. The light exits from the same plane of incidence. The emitted beams enter each polarization beam splitter through each set of (1/4) .lambda. Plates.

The components on the subsequent paths and their operations are exactly the same as in FIG. However, it is desirable that one CCD camera 21 and one image processing device are installed for each axis, and the two CCD cameras 21 each capture an image of a spot projected on the screen 20. The image processing apparatus detects the amount of displacement from the reference position set for each spot, and calculates the amount of distortion for two axes from these two amounts of displacement. Of course, in the case of PSD, one unit is preferable for one axis.

In any case, by setting the irradiation positions of the two measurement beams to, for example, A1 and B1 as described with reference to FIG. 7A, it is possible to measure the amount of distortion about two axes, for example, the amount of twist. Can be.

As described with reference to FIG. 6, this optical medium 40 also has an upper surface 40-1 serving as an incident surface of a laser beam for imparting distortion to a work. It can be used in a state where it is incorporated in

Further, also in the third embodiment, the deflection beam splitter 15 and the (1/4) .lambda. Plate 17 may be omitted. The reason is the same as described above.

Although the embodiments of the present invention have been described with reference to the measuring device and measuring method of the distortion amount, the present invention can be applied to the measurement of not only the distortion amount but also other deformation amounts.

[0066]

As described above, according to the present invention, it is possible to provide an apparatus for measuring the amount of distortion, which has a low cost, a high measuring speed and a small shape. Further, the amount of distortion can be measured with high accuracy without being affected by the inclination angle of the work. Further, since the apparatus can be used even when it is incorporated in a laser processing apparatus, it is possible to provide an in-line type distortion amount discriminating apparatus for measuring a distortion amount at the same station as laser processing.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a distortion amount measuring device according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a principle of calculating a distortion amount by the device of FIG. 1;

FIG. 3 is a diagram for explaining the relationship between the irradiation position of a measurement beam on a work and the strain in order to measure the amount of strain of the work.

FIG. 4 is a diagram showing a configuration of a distortion amount measuring device according to a second embodiment of the present invention.

FIG. 5 is a perspective view of the optical medium shown in FIG. 4;

FIG. 6 is a longitudinal sectional view of the optical medium shown in FIG.

FIG. 7 is a diagram for explaining the relationship between the irradiation position of a measurement beam on the work and the strain in order to measure the amount of strain of the work in two axial directions.

FIG. 8 is a diagram showing an optical medium used in a distortion amount measuring device according to a third embodiment of the present invention.

9 is an exploded perspective view of the optical medium shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Measurement light source 12 Beam expander 13 Mask 14 Work 15 Polarization beam splitter 16, 33, 43, 44 Corner cube prism 17 (1/4) and λ plate 18 Folding mirror 19 Table 20 Screen 21 CCD camera 30, 40 Optical medium 32 , 42 Reflective film 34, 45 Incident surface

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA46 AA65 CC37 DD02 DD06 DD11 GG05 GG06 JJ03 JJ16 JJ26 LL09 LL17 LL30 LL36 LL37 LL47 LL49 PP24 QQ31 5D042 NA01 PA10 RA10

Claims (23)

[Claims] 1. A measuring beam from a measuring light source is irradiated to a measuring object, and a reflected beam from the measuring object is returned at an angle parallel to the reflected beam by passing through a prism to re-irradiate the measuring object. Measuring the amount of displacement of the re-reflected beam from the measurement object from the reference position to measure the distortion of the measurement object. 2. A measuring beam from a measuring light source is irradiated to an object to be measured through an isolator means, and a reflected beam from the object to be measured is returned at an angle parallel to the reflected beam by passing through a prism. By re-irradiating the reflected beam from the object to be measured with the beam reflecting means, returning the beam to the isolator means in a path opposite to the path described above, and extracting a return beam from the isolator means. A distortion amount measuring method, wherein a distortion of a measurement object is measured by measuring a positional deviation amount of a return beam from a reference position. 3. A distortion measuring method according to claim 2, wherein said isolator means is a polarizing beam splitter, and further includes a phase difference in a path from passing through said polarizing beam splitter to returning to said polarizing beam splitter. A method for measuring a distortion amount, wherein a return beam having a phase shift is extracted by interposing a plate. 4. The distortion amount measuring method according to claim 3, wherein the retardation plate is a (1/4) .lambda. Plate (where, .lambda. Is the wavelength of the measurement beam), and A method for measuring the amount of distortion, wherein the phases are shifted by (1/2) .lambda. 5. A measurement light source for generating and irradiating a measurement object with a measurement beam, receiving a reflection beam of the measurement beam from the measurement object, returning the reflection beam at an angle parallel to the measurement beam, and Distortion amount measurement, comprising: a prism for re-irradiating the object to be measured; and a means for receiving a re-reflected beam of the re-irradiated measurement beam and measuring a displacement amount of the re-reflected beam from a reference position. apparatus. 6. A measurement light source for generating and irradiating a measurement object with a measurement beam, isolator means disposed between the measurement light source and the measurement object, and the measurement from the measurement object. A prism for receiving the reflected beam of the beam, returning the reflected beam at an angle parallel thereto and re-irradiating the object to be measured, receiving a re-reflected beam of the measurement beam re-irradiated by the prism, and receiving the reflected beam at the incident angle. Beam reflecting means for returning in a defined direction, returning the beam reflected by the beam reflecting means to the isolator means in a path opposite to the path, and extracting a return beam from the isolator means. And a means for measuring a displacement amount of the return beam from a reference position. 7. The distortion measuring apparatus according to claim 6, wherein the isolator is a polarizing beam splitter, and is disposed in a path from passing through the polarizing beam splitter to returning to the polarizing beam splitter. A distortion amount measuring device including a phase difference plate and extracting a return beam having a phase shift. 8. The distortion amount measuring apparatus according to claim 7, wherein the phase difference plate is a (1/4) .lambda. Plate (where, .lambda. Is the wavelength of the measurement beam), and A distortion amount measuring apparatus characterized in that the phases are shifted by (1/2) .lambda. 9. The distortion measuring apparatus according to claim 6, wherein an optical path between the prism and the beam reflecting means is formed by one optical medium. Strain amount measuring device. 10. The distortion measuring device according to claim 9, wherein the prism is a corner cube prism, the beam reflecting means is a reflection film, and the optical medium has a hexagonal cross section having at least upper and lower sides parallel to each other. Wherein a reflecting film is formed on a part of a surface defined by one of two sides adjacent to the upper side, and a corner cube prism is formed on a surface defined by the other side. Are formed integrally, the object to be measured is arranged on the lower side, and the remaining part of the surface on which the reflection film is formed is an incident surface of the measurement beam. Quantity measuring device. 11. A measurement light source for generating a measurement beam and irradiating the measurement target with an isolator means disposed between the measurement light source and the measurement target. A prism for receiving the reflected beam of the measurement beam, returning the reflected beam at an angle parallel thereto and re-irradiating the object to be measured, receiving a re-reflected beam of the measurement beam re-irradiated by the prism, and receiving the reflected beam; A plurality of sets of beam reflecting means that return in a direction defined by an angle, wherein the measuring beam from the measuring light source is split into a plurality of beams by a light splitting means, and the beams are turned back by the respective sets of the beam reflecting means. Is returned to the isolator means of each set in a path opposite to the above-mentioned path in each set, and a return beam is extracted from the isolator means. Unishi, comprising means for measuring the positional deviation amount from the reference position of said return Ri beam in each set, the strain amount measuring apparatus characterized by measuring the strain of the measuring object at a plurality of axes. 12. The distortion measuring device according to claim 11, wherein the isolator is a polarizing beam splitter, and is disposed in a path from passing through the polarizing beam splitter to returning to the polarizing beam splitter. A distortion measuring apparatus comprising a plurality of sets of phase difference plates, wherein the beams are passed through the phase difference plates in each set to extract the return beam having the shifted phase. 13. The distortion amount measuring apparatus according to claim 12, wherein the phase difference plate is a (1/4) .lambda. Plate (where, .lambda. Is the wavelength of the measurement beam) and the phase difference plate of the extracted return beam. A distortion amount measuring apparatus characterized in that the phases are shifted by (1/2) .lambda. 14. The distortion amount measuring apparatus according to claim 11, wherein the plurality of sets of prisms and the plurality of sets of beam reflecting means are included in one optical path including the plurality of sets of beam reflecting means. A strain amount measuring device characterized by being formed of a medium. 15. The distortion amount measuring apparatus according to claim 14, wherein the plural sets are two sets, the prism is a corner cube prism, the beam reflecting means is a reflection film, and the upper and lower surfaces of the optical medium are square. In addition, a reflecting film is formed on at least a part of one of two surfaces adjacent to one of the two sides of the two sets of the two parallel sides of the upper surface, which are polyhedrons parallel to each other. The other surface is formed integrally with a corner cube prism to form one set of optical paths, and the two surfaces adjacent to the other two sides of the two sets of two parallel sides of the upper surface. A reflection film is formed on at least a part of one of the surfaces, and a corner cube prism is integrally formed on the other surface to form another set of optical paths. Things are placed, each A distortion measuring apparatus, wherein the remaining portions of the surfaces on which the reflection films are formed are the incident surfaces of the measurement beams in the respective sets. 16. An optical medium characterized by being a polyhedron including a surface reflecting a laser beam and three surfaces forming a corner cube prism. 17. The optical medium according to claim 16, wherein
An optical medium further including a surface that transmits a laser beam, wherein the surface that transmits the laser beam and the surface that reflects the laser beam form one surface. 18. A measuring beam from a measuring light source is irradiated on a measuring object, and a reflected beam from the measuring object is returned at an angle parallel to the reflected beam by passing through a prism to re-irradiate the measuring object. And measuring a deformation of the measurement object by measuring a displacement amount of a re-reflected beam from the measurement object from a reference position. 19. A measuring beam from a measuring light source is irradiated to an object to be measured through an isolator means, and a reflected beam from the object to be measured is returned at an angle parallel to the reflected beam by passing through a prism. By re-irradiating the reflected beam from the object to be measured with the beam reflecting means, returning the beam to the isolator means in a path opposite to the path described above, and extracting a return beam from the isolator means. A deformation amount measuring method, wherein a deformation of a measurement object is measured by measuring a displacement amount of a return beam from a reference position. 20. A measuring light source for generating a measuring beam and irradiating the measuring object with a measuring beam, receiving a reflected beam of the measuring beam from the measuring object, returning the reflected beam at an angle parallel thereto, and Deformation measurement comprising: a prism for re-irradiating an object to be measured; and a means for receiving a re-reflected beam of the re-irradiated measurement beam and measuring a displacement of the re-reflected beam from a reference position. apparatus. 21. A measurement light source for generating and irradiating a measurement object with a measurement beam; isolator means disposed between the measurement light source and the measurement object; and measuring the measurement from the measurement object. A prism for receiving the reflected beam of the beam, returning the reflected beam at an angle parallel thereto and re-irradiating the object to be measured, receiving a re-reflected beam of the measurement beam re-irradiated by the prism, and receiving the reflected beam at the incident angle. Beam reflecting means for returning in a defined direction, returning the beam reflected by the beam reflecting means to the isolator means in a path opposite to the path, and extracting a return beam from the isolator means. A deformation amount measuring device, comprising: means for measuring a displacement amount of the return beam from a reference position. 22. The deformation amount measuring apparatus according to claim 20, wherein an optical path between the prism and the beam reflecting means is formed by one optical medium, including the prism and the beam reflecting means. measuring device. 23. The deformation amount measuring apparatus according to claim 22, wherein the prism is a corner cup prism, the beam reflecting means is a reflecting surface, and three surfaces constituting the corner cube prism are provided on the object to be measured. An optical medium composed of a polyhedron having at least seven surfaces of which two surfaces are opposed to each other, the beam reflection surface, and the surface adjacent thereto,
A deformation amount measuring device arranged on a path between the isolator means and the object to be measured.