JPH0996514A - Measuring apparatus for surface shape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a measuring apparatus by which the uneven shape of a face to be inspected can be measured easily by making a parallel luminous flux incident from a direction at a prescribed angle to the normal direction of the face to be inspected and making the parallel luminous flux; which is focused by an image- formation lens, a peripheral-edge light source. SOLUTION: When the uneven shape of a face 2a to be inspected on an object 2 to be inspected is measured, a tilt stage 20 is turned by a prescribed angle around the axial line (Y-axis) in the length direction of the face 2a to be inspected. Thereby, a parallel luminous flux from a collimating lens 18 enters the face 2a, to be inspected, from a direction at an angle θ to the normal direction of the face 2a to be inspected inside a plane (Z-X plane) at a right angle to the Y-axis. Consequently, reflected light from the face 2a to be inspected becomes a beam in a direction at an angle 2θ to the Z-axis (optical axis). Thereby, when reflected light from every part on the face 2a to be inspected is at a different angle to the direction of the optical axis due to its wavy uneven shape, an image height is changed largely with reference to change in the angle. Thereby, the wavy shape of the face 2a to be inspected, which is image- picked up by an image-pickup part 24 can be monitored 26 clearly so as to be measured easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface shape measuring apparatus for measuring the uneven shape of a test surface of a test object having an elongated test surface.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a magnetic head, a magnetic head material is formed in an elongated block shape,
A method of slicing this and cutting out a magnetic head is known. In the magnetic head, the surface shape of the head surface is important for quality, but when the surface to be the head surface at the stage of the elongated block has an uneven shape wavy in the longitudinal direction, A magnetic head having an excellent surface shape cannot be obtained even by cutting out from this elongated block. Therefore, if the uneven shape of the surface is measured in advance at the stage of the elongated block and only the good product is cut out, it is possible to manufacture a magnetic head of guaranteed quality.

[0003]

As a method of measuring the uneven shape of the surface of the elongated block, a method of forming an interference fringe by using an interferometer and observing the fringe pattern is conceivable. It is not easy to read the shape from the striped pattern, and in particular, it is difficult to determine the presence / absence of surface unevenness in a short time in a magnetic head manufacturing line. The present invention has been made in view of the above circumstances, and provides a surface shape measuring apparatus capable of easily measuring the unevenness shape of a test surface of a test object having an elongated test surface. The purpose is.

[0004]

The surface profile measuring apparatus according to the present invention is a surface profile measuring apparatus for measuring the uneven shape of the test surface of a test object having an elongated test surface, The subject supporting means for supporting the specimen, the parallel light irradiating means for irradiating the surface to be examined with parallel light, and the imaging lens for forming an image on the surface to be examined are provided. Is carried out so that the parallel light is incident on the surface to be inspected from a direction forming a predetermined angle with the normal direction of the surface to be inspected in a plane orthogonal to the longitudinal direction of the surface to be inspected, It is characterized in that the image forming lens is arranged in the parallel light incident direction, and spherical aberration is generated in a substantially parallel light beam formed by the image forming lens.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing an embodiment of the surface profile measuring apparatus according to the present invention. As shown in the figure, the surface shape measuring apparatus 10 is provided with an elongated surface 2 to be measured.
It is an apparatus for measuring the unevenness shape of a test surface of a test object 2 having a (a magnetic head material formed in an elongated block shape). That is, the surface shape measuring device 10 includes a laser device 12, a diverging lens 14, a half mirror 16, a collimator lens 18, a tilt stage 20, an image forming lens 22, an image pickup unit 24, and a monitor 26. Be prepared.

After the laser light emitted from the laser device 12 is diverged by the diverging lens 14, the diverging light is reflected by the half mirror 16 and collimated by the collimator lens 18 into parallel light, which is placed on the tilt stage 20. The collimator lens 18 focuses the reflected light from the subject on the tilt stage 20 again on the tilt stage 20, and the focused light is further focused on the imaging surface 24a of the imaging unit 24 by the condensing action of the imaging lens 22. Substantially parallel irradiation is performed, and the image of the subject obtained by this is displayed on the screen of the monitor 26. The surface profile measuring apparatus 10 is further configured such that the reference plate 28 can be arranged on the optical path between the collimator lens 18 and the tilt stage 20 (the position indicated by the chain double-dashed line in the figure). By arranging the surface 2a to be inspected horizontally with respect to the reference plate 28 with the reference plate 28 arranged in the position, it can be used as a Fizeau interferometer.

As shown in the figure, the subject 2 is supported on the tilt stage 20, but when measuring the uneven shape of the subject surface 2a of the subject 2, the tilt stage 20 is not supported. The inspection surface 2a is rotated about a longitudinal axis (Y axis when the coordinate system is set as shown) around the inspection surface 2a by a predetermined angle so that the inspection surface 2a is inclined at a predetermined angle with respect to the horizontal plane. Then, by this, the parallel light from the collimator lens 18 is directed from the direction forming the above-mentioned predetermined angle with the normal direction of the surface 2a to be detected in the ZX plane (the plane orthogonal to the longitudinal axis). It is designed to be incident. FIG. 2 is a perspective view showing the detailed structure of the tilt stage 20. As shown, the tilt stage 20 includes a Y stage 32 on the base plate 30.
The X stage 34 and the tilt stage body 36 are laminated.

The Y stage 32 can be moved in the Y axis direction with respect to the base plate 30 by the adjusting screw 38, and the X stage 34 can be moved in the X axis direction with respect to the Y stage 32 by the adjusting screw 40. The tilt stage body 36 can be tilted about the Y axis and the X axis with respect to the X stage 34 by adjusting screws 42 and 44, respectively. The tilt stage main body 36 is provided with a spring 46 that functions as a fulcrum when tilting.

The tilt stage 20 is further provided with four adjusting screws 48 supported by the base plate 30 thereof.
A shielding plate 50 is attached to the height adjustable member. The shielding plate 50 is formed with an elongated slit 50a extending in the Y-axis direction, and the slit 50a defines the shape of the surface 2a to be inspected of the subject 2. The shielding plate 50 is adjusted by adjusting the four adjusting screws 48 with respect to the subject 2 whose position and inclination angle are set by the Y stage 32, the X stage 34 of the tilt stage 20, and the tilt stage body 36. It is arranged in the vicinity of the surface to be the test surface 2a.

As shown in FIG. 3A, the imaging lens 22 is constructed so that an image of the subject formed by the imaging lens 22 has spherical aberration. This spherical aberration is caused by the tilt stage body 3 as shown in FIG.
When the angle formed by the reflected light from 6 and the Z axis (optical axis) is taken as the horizontal axis and the image height shift amount on the image pickup surface of the image pickup unit 24 is taken as the vertical axis, the aberration increases as the angle increases in a higher-order function. Is set to increase.

Next, the operation of this embodiment will be described.
It is assumed that the subject 2 has an uneven surface 2a to be inspected, which is corrugated in the Y-axis direction as shown in FIG. In the present embodiment, the subject 2 is tilted by the tilt stage 20 about the Y axis by a predetermined angle. The tilt angle of the tilt stage body 36 at that time is θ.
Then, the surface to be inspected 2a becomes as shown in FIG.
By allowing the surface 2a to be inspected to have such an inclination angle, the parallel light from the collimator lens 18 enters the tilt stage body 36 at an incident angle θ.

If the tilt stage body 36 is not tilted with respect to the horizontal plane, the tilt stage body 3 is assumed.
Since the reflected light from 6 becomes a beam parallel to the Z-axis (optical axis) direction, it passes through the collimator lens 18 and the imaging lens 22.
When it is focused on, it becomes a paraxial ray as shown by A in FIG. Therefore, the reflected light from each part of the test surface 2a of the test object 2 placed on the tilt stage body 36 is Z-axis (optical axis) due to the wavy uneven shape of the test surface 2a.
Even if they have different angles with respect to the direction, as is clear from A in FIG. 3B, there is almost no change in the image height with respect to the change in the angle, and therefore the wavy unevenness of the surface 2a to be inspected on the monitor 26. The shape cannot be projected.

On the other hand, in the present embodiment, since the tilt stage body 36 is inclined at an angle θ with respect to the horizontal plane, the reflected light from the tilt stage body 36 is 2θ with respect to the Z axis (optical axis). It becomes a beam in the direction that makes an angle of. Therefore, when it is focused by the imaging lens 22 via the collimator lens 18, it becomes a marginal ray as shown by B in FIG.
If the reflected light from each part of the test surface 2a of the test object 2 placed on the surface of the test object 2 has a different angle with respect to the Z-axis (optical axis) direction due to the corrugated uneven shape of the test surface 2a. , Fig. 3
As is clear from B in (b), since the image height changes greatly with respect to the change in the angle, the image is captured by the image capturing unit 24.
The wavy uneven shape of the surface 2a to be inspected can be clearly displayed on the monitor 26.

FIG. 5 is an image of the surface 2a to be inspected on the monitor 26 obtained by the surface shape measuring apparatus 10 according to this embodiment. FIG. 5A shows a large wavy unevenness on the surface 2a to be inspected. FIG. 2B is a diagram showing a defective product having no shape, and FIG. 6B is a diagram showing a defective product having a large corrugated uneven shape on the surface 2a to be tested. In addition,
The reason for making such a quality determination from each image on the monitor 26 is as follows. That is, the subject 2 in this embodiment is formed by forming the magnetic head material into an elongated block shape, and the magnetic head is cut out by slicing the magnetic head material in the longitudinal orthogonal direction. Even if there is a shape, this is
If the wave has a long period as shown in (a), the effect of the corrugated uneven shape does not remain on the surface of the cut magnetic head, and no particular problem occurs in the performance of the magnetic head. On the other hand, in the case of a wave having a short period as shown in FIG. 5B, the effect of the corrugated uneven shape remains on the surface of the cut magnetic head, which causes a problem in the performance of the magnetic head. Become.

As described above in detail, in the present embodiment, the tilt stage body 36 is tilted by an angle θ with respect to the horizontal plane, so that the reflected light from the tilt stage body 36 is directed to the imaging lens 22 by the marginal ray. Since a lens having spherical aberration is used as the imaging lens 22, a wavy uneven shape is formed on the surface 2a of the subject 2 mounted on the tilt stage body 36. Therefore, if the reflected light from each part of the surface to be inspected 2a has a different angle with respect to the Z-axis direction, the image height changes greatly with respect to the change in the angle. The wavy concavo-convex shape of the surface 2a to be inspected can be clearly displayed on the screen. Therefore, according to the present embodiment, in the magnetic head manufacturing line, it is possible to easily determine the presence or absence of the surface unevenness of the elongated block to be the magnetic head in a short time.

In this embodiment, since the laser device is used as the light source, the reflected light from the tilt stage body 36 is also a beam having a strong directivity. Therefore, only the marginal ray shown by B in FIG. 3A is incident on the image pickup surface, which makes it possible to more clearly project the wavy uneven shape of the test surface 2a on the image pickup surface 24a.

Further, in the present embodiment, the shape of the test surface 2a of the subject 2 is defined by the slit 50a of the shield plate 50 attached to the tilt stage 20, so that the same standard is always used. The wavy uneven shape of the surface 2a to be inspected can be projected, and the observation and evaluation thereof can be facilitated. Further, if the X-stage 34 is moved in the X-axis direction by the adjusting screw 40, even if the subject 2 has a wide surface, it is divided into the elongated test surface 2a and the It is possible to successively observe the wavy uneven shape. If the contour itself of the surface to be the test surface 2a of the test object 2 is an elongated shape, the entire surface of the test object 2 is used as the test surface 2a without using the shielding plate 50 as described above. Of course, shape measurement may be performed.

Further, in the above embodiment, the uneven state on the surface to be inspected 2a is qualitatively judged from the wavy shape displayed on the monitor 26. However, by measuring the amplitude amount of this wavy shape. It is possible to quantitatively detect the amount of unevenness of the surface to be inspected 2a based on the amount of spherical aberration of the imaging lens. The surface shape measuring device of the present invention is not limited to the above embodiment, and various other modifications can be made.

[0019]

According to the present invention, the subject is supported by the subject supporting means so that the subject is tilted to form a predetermined angle with the normal direction of the subject surface in a plane orthogonal to the longitudinal direction of the subject surface. Is arranged so that parallel light is incident on the surface to be inspected from the direction, and an imaging lens for focusing the reflected light from the surface to be inspected irradiated with the parallel light is arranged in the parallel light incident direction. In addition, since the focused beam formed by the imaging lens has a spherical aberration, it is possible to easily measure the uneven shape of the test surface of the test object having the elongated test surface.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a surface profile measuring apparatus according to the present invention.

FIG. 2 is a perspective view showing a tilt stage of the above embodiment.

FIG. 3 is an explanatory view showing the operation of the above embodiment.

FIG. 4 is a perspective view showing a test surface to be measured in the above embodiment.

FIG. 5 is a diagram showing the measurement results of the above-mentioned embodiment.

[Explanation of symbols]

 2 subject 2a surface to be inspected 10 surface shape measuring device 12 laser device 14 diverging lens 16 half mirror 18 collimator lens 20 tilt stage 22 imaging lens 24 imaging unit 24a imaging surface 26 monitor 28 reference plate 30 base plate 32 Y stage 34 X stage 36 Tilt stage body 50 Shield plate 50a Slit

Claims (4)

[Claims] 1. A surface shape measuring apparatus for measuring the uneven shape of the test surface of a test object having an elongated test surface, the test object supporting means for supporting the test object, and the test surface. Parallel light irradiating means for irradiating parallel light to the object, and an imaging lens for forming an image on the surface to be inspected, and the support of the object by the object supporting means is orthogonal to the longitudinal direction of the surface to be inspected. The parallel light is incident on the surface to be inspected from a direction forming a predetermined angle with the normal direction of the surface to be inspected in the plane, and the imaging lens is arranged in the parallel light incident direction. In addition, the surface shape measuring device is characterized in that a spherical aberration is generated in the substantially parallel light flux formed by the imaging lens. 2. A shield plate, in which a slit having the same shape as the elongated shape of the surface to be inspected is formed, is arranged near the surface of the object to be the surface to be inspected. 1. The surface shape measuring device according to 1. 3. The support of the subject by the subject support means can move the subject relative to the shielding plate in a direction along the subject surface orthogonal to the longitudinal direction of the slit. The method according to claim 2, wherein
The surface shape measuring device described. 4. The surface shape measurement according to claim 1, wherein a reference plate for forming interference fringes is arranged at a predetermined position within the light flux of the parallel light. apparatus.