JP3103946B2 - Surface shape measuring method and surface shape 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 method and an apparatus for measuring a surface shape of a soft material such as a magnetic tape, a floppy disk, a plastic film, a polished sheet and the like and a composite material thereof. The present invention relates to a method and apparatus for measuring the surface shape of these materials used in sliding contact with a magnetic head or the like under contact conditions close to practical use while contacting a contact body.

[0002]

2. Description of the Related Art In a high-density magnetic recording medium such as a magnetic tape or a floppy disk, the recording / reproducing output is improved and the S / N ratio is increased.
Due to the ratio, it is desirable to make the surface of the magnetic layer as smooth as possible. However, if the surface of the magnetic layer is made too smooth, the sliding noise may increase, or the friction and wear characteristics with respect to the magnetic head and the guide member may deteriorate. For this reason, the shape of the magnetic layer surface is precisely measured and analyzed, and an attempt has been made to control it so as to have a smooth and fine irregular shape. As a method for measuring the surface shape of such a magnetic layer, For example, manufactured by Rankella Hobson;
Taristep and Tarisurf, manufactured by Tokyo Seimitsu Co., Ltd .; Stylus type surface profile measuring machine such as Surfcom; WYKO; TO
Optical interference type surface shape measuring device such as PO-3D, manufactured by Kosaka Laboratory Co., Ltd .; Optical focus error detecting type surface shape measuring device such as ET-30HK, manufactured by Digital Instruments; Nan
Scanning tunneling microscopes such as oscope II and electron microscopes such as ERA-3000 manufactured by Elionix are used.

[0003]

However, since all of these conventional surface shape measuring instruments are capable of performing measurement after fixing the magnetic layer surface in a non-contact state in the air or in a vacuum, The surface shape of the magnetic layer surface when it comes into contact with a magnetic head or the like cannot be measured.Since the magnetic layer surface in practical use is in contact with a magnetic head or the like, it can be measured with these conventional surface shape measuring instruments. Elasto-plastic deformation due to the contact force has occurred compared to the state where In the case of a soft material such as a magnetic tape or a floppy disk, or a composite material thereof, deformation of a convex portion in the surface irregularities due to a contact force is particularly large. Therefore, according to the conventional surface shape measurement results, various characteristics of the magnetic recording medium are obtained. There was a problem that was not able to sufficiently elucidate.

[0004]

SUMMARY OF THE INVENTION The present invention has been made as a result of conducting various studies to improve the above drawbacks. The present invention is directed to irradiating a light beam on the surface of an object to be measured and using an optical method by utilizing the reflected light. In a measurement method for measuring the surface shape of an object to be measured, a light-transmissive abutment that transmits a measuring light beam is brought into contact with the surface of the object to be measured, and between the light-transmissive abutment and the surface of the object to be measured. The difference in the refractive index with respect to the light transmissive abutment is
By filling a liquid filler of 0.3 or less, through these light-transmissive abutment and liquid filler, by irradiating a light beam on the surface of the measured object and measuring the surface shape of the measured object by an optical method, This enables measurement of the surface shape of an object under contact conditions close to practical use.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a surface profile measuring apparatus according to the present invention will be described below with reference to FIG. In FIG.
Reference numeral 1 denotes an object to be measured, which is supported on a backing 2, and is in contact with a light-transmissive contact body 4 which is supported by a sample holder 3 so as not to be lifted. The liquid filler 5 is filled between the light transmissive contact body 4 and the surface of the DUT 1 having irregularities.

The backing 2 is supported by an elastic body 9 on a load cell 8 installed on a swing support plate 7 of a fine moving table 6,
The fine moving table 6 is provided on the sample stage 10. 11
Is an adjustment photograph attached to the fine movement table 6, and the swing of the adjustment photograph 11 causes the rocking support plate 7 pivotally supported by the pin 12 to swing, thereby loading the load cell 8 and the elastic body. 9. An arbitrary contact force is applied to the surface of the DUT 1 that is in contact with the light-transmissive contact member 4 via the backing 2. This contact force is detected by the load cell 8.

Reference numeral 13 denotes a light emitting body 13a, a lens 13b, a lens 13c, an aperture stop 13d, and a lens 13.
e, a field stop 13f, and a lens 13g. The light from the light source 13 passes through the spectral filter 14 and then passes through the light source beam splitter 1.
5 is reflected downward.

A part of the downward reflected light passes through the interferometer beam splitter 17 of the linic interferometer 16 and reaches the sample side objective lens 18, where the sample side objective lens 1
8 focuses on the uneven surface of the DUT 1 through the light transmissive abutment 4 and the liquid filler 5. Then, the light reflected on the surface of the DUT 1 passes through the liquid filler 5 and the light-transmitting abutment 4 again, returns to the sample-side objective lens 18, and further passes through the interferometer beam splitter 17. And head upward.

A part of the light incident on the linic interferometer 16 is reflected by the interferometer beam splitter 17 and reaches the reference surface side objective lens 19, which corrects the optical path length. The focus is focused on the reference plane 21 through the plate 20. Then, the reflected light from the reference surface 21 is
The light returns to the reference surface side objective lens 19 via the optical path length correction plate 20, and is further reflected upward by the interferometer beam splitter 17 and travels upward.

At this time, the interferometer beam splitter 17
The reflected light reflected upward and reflected upward, and the object to be measured 1
The reflected light that is reflected by the surface of the device 1 and transmitted through the interferometer beam splitter 17 and upwards interferes, and interferes with each other.
An interference fringe corresponding to the unevenness of the surface is generated. The interference fringes are transmitted to the camera 23 via the camera-side objective lens 22.
And the camera 23 converts it into an electric video signal.

From this interference fringe, for example, K
another Creat: COMPARISO
N OF PHASE-MEASUREMENTALG
The surface shape of the DUT 1 can be obtained by using the fringe scanning method described in ORITHMS, SPIE Vol (1986), and the light-transmissive abutment 4 is brought into contact with the surface of the DUT 1. The surface shape of the DUT 1 can be measured. Therefore, according to this method and apparatus, like a magnetic recording medium used in sliding contact with a magnetic head or the like,
When the DUT 1 is used in a contact state, the surface shape of the DUT 1 can be measured under a contact condition close to a practical state.

Here, as the light-transmissive abutment 4, various shapes and materials that can provide a contact condition close to a practical condition to the surface of the DUT 1 can be used. It is necessary to select a material that transmits the measuring light beam for measuring the surface shape at a minimum. Further, the light transmissive contact member 4
In addition to being used in contact with the surface of the object 1 to be measured, it is preferable that the device can be appropriately separated and left in order to enable comparative measurement with a non-contact and stress-free state. If bubbles occur in the filler 5, the measurement will be inconvenient. Therefore, the separation distance from the surface of the DUT 1 is 0.1 mm.
It is preferably within the range.

Further, the liquid filler 5 contains the light-transmitting abutment 4
The surface facing the surface of the DUT 1 is provided in order to prevent the measurement light beam from being reflected and to prevent noise, error, error, and the like from being generated when measuring the surface shape. Therefore, it is desirable that the refractive index is as close as possible to the refractive index of the light transmissive abutment 4, and it is preferable that the difference in the refractive index from the light transmissive abutment 4 is 0.3 or less even when separated. Specific examples include, for example, water and liquids used for immersion microscope observation, and are not particularly limited as long as they have chemical properties that do not change the surface shape of the DUT 1. Can be used.

Further, the reference surface 21 of the linic interferometer 16
The optical path length correction plate 20 provided on the front surface has an optical path length of the measuring light beam on the sample side, which is twice as long as the refractive index when compared with ordinary atmospheric measurement, when transmitting through the inside of the light transmissive abutment 4. Reference surface 21
This is provided to correct the optical path length on the side. Therefore, it is preferable to use a material having substantially the same material, thickness, and finish as the light transmissive contact member 4. However, the optical path length correction plate 20 and the light transmissive contact body 4 do not necessarily need to be made of the same material, and the optical path length can be corrected by adjusting the thickness. Further, the optical path length correction plate 20 may be appropriately separated from the reference surface 21, and the same effect can be obtained by inserting the optical path length correction plate 20 between the interferometer beam splitter 17 and the reference surface objective lens 19.

When a fringe scanning method is used as a method for obtaining a surface shape from interference fringes, the reference surface side objective lens 1 is used.
9. It is preferable that the optical path length correction plate 20 and the reference surface 21 are integrally formed so that they can be finely moved in the optical axis direction by a piezo element.

In the above embodiment, the optical interference method is used as the optical surface shape measuring method. However, the present invention is not limited to the optical interference method. For example, other methods such as an optical focus error detection method may be used. You may use it.

Hereinafter, a test example in which the surface shape of the magnetic layer surface of a video tape was measured using the surface shape measuring apparatus shown in FIG. 1 will be described. Test Example 1 Ferromagnetic metal iron powder (1600 Oe, coercive force, 100 parts by weight of saturated magnetism, 120 emu / g, major axis diameter: 0.18 μm, axis ratio: 10) Hydroxyl group-containing vinyl chloride resin 10 {thermoplastic polyurethane resin 7} alumina (Particle size: 0.2 μm) 8 {myristinic acid 2} Bengala (particle size: 0.8 μm) 2 〃 Seat 5H (manufactured by Tokai Carbon Co., Ltd .; carbon black, particle size: 2 mm 20 μm) cyclohexanone 70 〃 toluene 70 〃 After this composition was mixed and dispersed in a ball mill for 96 hours,
Further, 5 parts by weight of a trifunctional polyisocyanate compound was added, and the mixture was stirred for 5 minutes to prepare a magnetic paint. This magnetic paint was coated on a biaxially oriented polyethylene terephthalate having a thickness of 10 μm.
The film was applied to a thickness of 2.5 μm after drying, dried, calendered, and cut into a predetermined width to produce a video tape. In order to make it easier to confirm the effect of the surface shape measuring apparatus, the calendering treatment was adjusted slightly, and the surface of the magnetic layer was made rougher than a commercially available metal video tape.

Next, in the surface shape measuring device shown in FIG. 1, each member shown below corresponds to the backing 2: polyethylene terephthalate film (length 1 mm × width 1 mm × thickness 0.075 mm) Light transmitting abutment 4 : Cover glass for microscope (refractive index)
1.52) Liquid filler 5: water (refractive index: 1.33) Fine movement table 6: Chuo Seiki Co., Ltd .; TS-201 Load cell 8: TMI Co .; T7 Elastic body 9: Silicon rubber plate (length 1 mm × width 1 mm)
× thickness 2 mm) Sample stage 10: WYKO; Tip tilt stage TT-100 Measurement optical system: WYKO; TOPO-3D Linic interferometer 16: WYKO; Objective head LX-
40 partially modified and optical path length correction plate 20 inserted Optical path correction plate 20: Cover glass for microscope (refractive index)
1.52), the surface shape of the video tape when the load read from the output voltage of the load cell 8 was 0 g and 25 g was measured, and Ra (center line average roughness) was used as the surface roughness.
And PV (Peak to Valley) were determined. In this test example, since the surface shape of the DUT 1 was optically measured in water, the value of the refractive index of the water was twice as large as that in the atmosphere. Thus, the surface roughness was calculated by multiplying the measured value by 1 / 1.33.

Test Example 2 The videotape used in Test Example 1 was attached to the optical flat with the back side wet with water so as not to cause wrinkles, and manufactured by WYKO; TOPO-3D;
X-40 (without an optical path length correction plate) was attached, and its surface shape was measured in the air to determine the surface roughness Ra and PV. Table 1 below shows the results.

[0020]

As is clear from Table 1 above, in the surface shape measuring method according to the present invention (Test Example 1), when the load indicating the contact force is set to 0 g, the result obtained by the normal surface shape measuring method according to Test Example 2 is obtained. Almost equivalent results were obtained. Also, when the load indicating the contact force is 25 g, especially the PV decreases as compared with the load of 0 g, and it can be seen that the convex portion of the video tape surface is elastically deformed and collapsed by the contact force. .

[0022]

As described above, according to the surface shape measuring method and the surface shape measuring apparatus of the present invention, the surface shape of a material used in sliding contact with a magnetic head or the like is adjusted to a contact condition close to a practical condition. It can be measured below.

[0023]

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one embodiment of a surface shape measuring device of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 object to be measured 2 backing 3 sample holder 4 light transmissive abutment 5 liquid filler 6 fine moving table 7 swing support plate 8 load cell 9 elastic body 10 sample stage 11 adjustment shooting 13 light source 14 spectral filter Reference Signs List 15 light source beam splitter 16 linic interferometer 17 interferometer beam splitter 18 sample side objective lens 19 reference plane objective lens 20 optical path length correction plate 21 reference plane 23 camera

Claims (2)

(57) [Claims] 1. A measuring method for irradiating a light beam on a surface of an object made of a soft material and a composite material thereof and measuring a surface shape of the object by an optical method using reflected light, on the surface of, with contacting the light transmitting abutting member which transmits the measurement light beam, between the surface of the light-transmitting contact member and the object to be measured, the difference in refractive index with respect to light transmitting abutment body 0.
Fill up to 3 liquid fillers and set the contact force of the light transmissive contact body to the surface of the object
The surface shape of the object under arbitrary contact force adjusted by an optical method by irradiating a light beam on the surface of the object through these light-transmissive abutting bodies and the liquid filler in an adjusted state Surface shape measuring method characterized by measuring the surface 2. A material comprising a soft material and a composite material thereof.
Light is applied to the surface of the measurement object, and the reflected light
Measurement that measures the surface shape of the object to be measured by a statistical method
Means and a distance of 0.1 mm or less from the surface of the DUT.
A light-transmissive abutment that is placed and transmits the measurement light beam, and is filled between the light-transmissive abutment and the surface of the object to be measured.
The difference of the refractive index with respect to the transmissive abutment is set to 0.3 or less.
Liquid filler, and a light-transmissive abutment on the surface of the object to be measured via the liquid filler.
Means for variably adjusting the contact force to an arbitrary contact force and detecting the contact force of the light-transmissive contact body against the surface of the object to be measured
And means for, by an optical method by applying a light beam on the surface of the object to be measured, adjusted
The surface shape of the object under arbitrary contact force
Surface profile measuring device to measure