JP3230963B2 - Surface profile measuring device - Google Patents

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 irregular shape of a test surface 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 a magnetic head, the surface shape of the head surface is important in quality, but in the case of the surface to be the head surface in the step of the elongated block, if the surface has a concave and convex shape wavy in the longitudinal direction, Even if cutting is performed from this elongated block, a magnetic head having an excellent surface shape cannot be obtained. Therefore, if the uneven shape of the surface is measured in advance in the step of the elongated block, and only the non-defective product is cut out, it is possible to manufacture a magnetic head with guaranteed quality.

[0003]

As a method of measuring the irregular shape of the surface of the above-mentioned elongated block, a method of forming an interference fringe using an interferometer and observing the fringe pattern can be considered. It is not easy to read the shape from the stripe pattern, and it is particularly difficult to judge the presence or absence of surface irregularities in a short time in a magnetic head production line. The present invention has been made in view of such circumstances, and provides a surface shape measuring apparatus capable of easily measuring the uneven shape of a test surface of a test object having an elongated test surface. It is intended for.

[0004]

A surface shape measuring apparatus according to the present invention is a surface shape measuring apparatus for measuring the uneven shape of the test surface of a test object having an elongated test surface. An object supporting means for supporting an object, a parallel light irradiating means for irradiating the object surface with parallel light, and an imaging lens for forming an image on the object surface; and Is performed so that the parallel light is incident on the test surface from a direction that forms a predetermined angle with the normal direction of the test surface in a plane orthogonal to the longitudinal direction of the test surface, The imaging lens is arranged in the direction of incidence of the parallel light, and is configured such that spherical aberration occurs in the substantially parallel light beam formed by the imaging 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 shape measuring apparatus according to the present invention. As shown in the figure, the surface shape measuring device 10 has an elongated shape of the test surface 2.
This is an apparatus for measuring the unevenness of the test surface of the test object 2 (having a magnetic head material formed in a slender block shape) having a. That is, the surface shape measuring apparatus 10 includes a laser device 12, a diverging lens 14, a half mirror 16, a collimator lens 18, a tilt stage 20, an imaging lens 22, an imaging unit 24, and a monitor 26. Equipped.

After the laser light emitted from the laser device 12 is diverged by the diverging lens 14, the divergent light is reflected by the half mirror 16, and is converted into parallel light by the collimator lens 18, and is converted to parallel light on the tilt stage 20. The reflected light from the subject on the tilt stage 20 is focused again by the collimator lens 18, and the focused light is further condensed by the imaging lens 22 onto the imaging surface 24 a of the imaging unit 24. Irradiation is performed substantially in parallel, and an image of the subject obtained by the irradiation is displayed on the screen of the monitor 26. The surface shape measuring device 10 is further configured such that a reference plate 28 can be disposed on an optical path between the collimator lens 18 and the tilt stage 20 (a position indicated by a two-dot chain line in the figure). By disposing the test surface 2a horizontally with respect to the reference plate 28 in a state where the reference plate 28 is disposed, it can be used as a Fizeau interferometer.

As shown in the figure, the subject 2 is supported on a tilt stage 20. However, when measuring the uneven shape of the test surface 2a of the subject 2, the tilt stage 20 is supported. The test surface 2a is rotated by a predetermined angle around the longitudinal axis of the test surface 2a (Y axis when a coordinate system is set as shown in the figure), and the test surface 2a is inclined by a predetermined angle with respect to the horizontal plane. Thereby, the parallel light from the collimator lens 18 is transferred to the test surface 2a from a direction at a predetermined angle with respect to a normal direction of the test surface 2a in a ZX plane (a plane orthogonal to the longitudinal axis). It is designed to be incident. FIG. 2 is a perspective view showing a detailed structure of the tilt stage 20. As shown in the figure, the tilt stage 20 has a Y stage 32 on a base plate 30.
, An X stage 34 and a tilt stage main body 36 are laminated.

The Y stage 32 can be moved in the Y axis direction with respect to the base plate 30 by an adjustment screw 38, and the X stage 34 can be moved in the X axis direction with respect to the Y stage 32 by an adjustment screw 40. The tilt stage main body 36 can be tilted around 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 acts as a fulcrum at the time of tilting.

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

As shown in FIG. 3A, the imaging lens 22 is configured so that a spherical aberration occurs in the image of the subject formed by the imaging lens 22. As shown in FIG. 3 (b), the spherical aberration
When the angle formed by the reflected light from the optical axis 6 and the Z axis (optical axis) is taken on the horizontal axis, and the image height deviation amount on the imaging surface of the imaging unit 24 is taken on 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 a test surface 2a having an uneven shape waving in the Y-axis direction as shown in FIG. In the present embodiment, the subject 2 is tilted at a predetermined angle around the Y axis by the tilt stage 20. At this time, the tilt angle of the tilt stage main body 36 is set to θ.
Then, the test surface 2a becomes as shown in FIG.
By providing the test surface 2a with such an inclination angle, the parallel light from the collimator lens 18 enters the tilt stage main body 36 at an incident angle θ.

If the tilt stage body 36 is not inclined with respect to the horizontal plane, the tilt stage body 3
The reflected light from 6 becomes a beam parallel to the Z-axis (optical axis) direction.
When the light is converged at the point (a), the light becomes a paraxial ray as shown by A in FIG. Therefore, reflected light from each part of the test surface 2a of the test subject 2 placed on the tilt stage main body 36 is reflected on the Z-axis (optical axis) by the wavy irregularities of the test surface 2a.
Even if the angle is different from the direction, as is apparent from A of FIG. 3B, there is almost no change in the image height with respect to the angle change. 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). Beam in a direction at an angle of. Therefore, when the light is converged 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 test object 2 has a different angle with respect to the Z-axis (optical axis) direction due to the wavy irregularities of the test surface 2a. , FIG.
As is clear from B of (b), since the image height greatly changes with the angle change, the image is captured by the imaging unit 24.
The wavy irregularities of the test surface 2a can be clearly projected on the monitor 26.

FIG. 5 is an image of the test surface 2a on the monitor 26 obtained by the surface shape measuring apparatus 10 according to the present embodiment, and FIG. 5A shows large wavy irregularities on the test surface 2a. FIG. 4B shows a non-defective product having no shape, and FIG. 4B shows a defective product having a large wavy uneven shape on the test surface 2a. In addition,
The reason why the quality is determined from each image on the monitor 26 is as follows. That is, the test object 2 in this embodiment is formed of a magnetic head material in an elongated block shape, and the magnetic head is cut out by slicing the magnetic head material in a direction orthogonal to the longitudinal direction. Even if there is a shape, this is
In the case of a long-period wave as shown in (a), the influence of the wavy irregularities does not remain on the surface of the cut magnetic head, and there is no particular problem in the performance of the magnetic head. On the other hand, in the case of a short-period wave as shown in FIG. 5B, the effect of the wavy irregularities remains on the surface of the cut magnetic head, which causes a problem in performance as the magnetic head. Become.

As described in detail above, in the present embodiment, the tilt stage main body 36 is inclined at an angle θ with respect to the horizontal plane, so that the reflected light from the tilt stage main body 36 is transmitted to the imaging lens 22 by the marginal rays. Since a lens having a spherical aberration is used as the imaging lens 22, a wavy irregular shape is formed on the test surface 2 a of the test object 2 mounted on the tilt stage main body 36. Therefore, if the reflected light from each part of the test surface 2a has a different angle with respect to the Z-axis direction, the image height greatly changes with respect to the change in the angle. Thus, the wavy irregularities of the test surface 2a can be clearly projected. Therefore, according to the present embodiment, in the manufacturing line of the magnetic head, it is possible to easily determine in a short time the presence / absence of surface unevenness of the elongated block to be the magnetic head.

In this embodiment, since the laser device is used as the light source, the reflected light from the tilt stage main body 36 also becomes a beam having strong directivity. For this reason, only the marginal rays shown by B in FIG. 3A are incident on the imaging surface, whereby the wavy irregularities of the test surface 2a can be more clearly projected on the imaging surface 24a.

In the present embodiment, the shape of the test surface 2a of the subject 2 is defined by the slit 50a of the shielding plate 50 attached to the tilt stage 20, so that the same reference is always used. The wavy irregularities of the test surface 2a can be displayed, and the observation and evaluation thereof become easy. Furthermore, if the X stage 34 is moved in the X-axis direction by the adjusting screw 40, even when the subject 2 has a wide surface, the X stage 34 is divided into the elongated test surface 2a, It is possible to sequentially observe the wavy irregularities. When the contour of the surface to be the test surface 2a of the test object 2 has an elongated shape, the entire surface of the test object 2 is used as the test surface 2a without using the above-described shielding plate 50. Needless to say, shape measurement may be performed.

In the above embodiment, the state of the irregularities on the test surface 2a is qualitatively determined from the wavy shape projected on the monitor 26. However, the amplitude of the wavy shape is measured. In addition, it is possible to quantitatively detect the amount of unevenness of the test surface 2a based on the amount of spherical aberration of the imaging lens. It should be noted that the surface shape measuring apparatus of the present invention is not limited to the above-described embodiment, and various other modifications can be made.

[0019]

According to the present invention, the subject is inclined by the subject supporting means, so that the subject forms a predetermined angle with the normal direction of the surface in a plane perpendicular to the longitudinal direction of the surface. An imaging lens that is configured to make parallel light incident on the surface to be inspected from a direction, and that focuses reflected light from the surface to be irradiated with the parallel light, is arranged in the parallel light incident direction. In addition, the configuration is such that spherical aberration occurs in the focused beam formed by the imaging lens. Therefore, it is possible to easily measure the uneven shape of the test surface of the test subject having the elongated test surface.

[Brief description of the drawings]

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

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

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

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

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

[Explanation of symbols]

 Reference Signs List 2 subject 2a surface 10 to be measured 10 surface shape measuring device 12 laser device 14 divergent 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Sho 62-199616 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 11/00-11/30

Claims (4)

(57) [Claims] 1. A surface shape measuring apparatus for measuring an uneven shape of a test surface of a test object having an elongated test surface, a test object supporting means for supporting the test object, and the test surface. A parallel light irradiating means for irradiating the object with parallel light, and an imaging lens for forming an image on the surface to be inspected, wherein the support of the object by the object supporting means is orthogonal to a longitudinal direction of the surface to be inspected. It is performed so that the parallel light is incident on the test surface from a direction forming a predetermined angle with a normal direction of the test surface in a plane, and the imaging lens is disposed in the parallel light incident direction. A surface shape measuring apparatus characterized in that a spherical aberration is generated in a substantially parallel light beam formed by the imaging lens. 2. A shielding plate having a slit formed in the same shape as the elongated shape of the test surface is disposed near the surface of the test object to be the test surface. 2. The surface shape measuring device according to claim 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 test surface orthogonal to a longitudinal direction of the slit. 3. The method according to claim 2, wherein
The surface shape measuring device according to the above. 4. The surface shape measurement according to claim 1, wherein a reference plate for forming an interference fringe can be arranged at a predetermined position in the light beam of the parallel light. apparatus.