JPH0626831A - Method and apparatus for measuring surface shape - Google Patents

Abstract

PURPOSE:To make it possible to measure the shape of a surface under the state close to the actual using state by pushing the surface of a material to be measured on a light transmitting contact body, casting a light ray on the surface of the material to be measured, and measuring the surface shape of the material to be measured by an optical method. CONSTITUTION:A material to be measured 1 is supported on a pushing container 2 thorugh a packing ring 2 in the tightly sealed state. The material 1 is brought into contact with the surface of a light transmitting contact body 5 with a sample pushing part 4 or held through a spacer ring 6 so that the material 1 approaches a part at the distance of 0.1mm from the surface. Pushing fluid 9, which is compressed by a pressure with a regualtor 8, is supplied into the container 3. The rear surface of the material to be measured 1 is pushed, and the front surface of the material to be measured 1 is pushed to the contact body 5. The light from a light source 11 is reflected with a splitter 13 and focused on the surface of the material to be measured 1 with a lens 16. The reflected light passes splitters 15 and 13 and advances upward. Meanwhile, part of the incident light into an interferometer 14 is reflected with the splitter 15 and focused on a reference surface 19 with a lens 17. The reflected light is reflected with the splitter 15 and advances upward. Two reflected light interfere, and the interference fringes corresponding to the irregularities of the surface of the material to be measured 1 are generated. The fringes are converted into the electric image signal, and the surface shape can be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring the surface shape of soft materials such as magnetic tapes, floppy disks, plastic films, polishing sheets and the like, and composite materials thereof, and more specifically, The present invention relates to a method and an 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 a practical state while contacting an abutting 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.
For this reason, it is desirable to make the surface of the magnetic layer as smooth as possible. However, if the surface of the magnetic layer is too smooth, sliding noise may be increased, or the friction and wear characteristics of the magnetic head and the guide member may be deteriorated.

For this reason, attempts have been made to precisely measure and analyze the shape of the surface of the magnetic layer and control it so that it has a smooth and fine uneven shape. Examples of the method include a stylus type surface profile measuring instrument such as Tallystep and Tallysurf manufactured by Rank-Tera-Hobson, Tokyo Seimitsu Co., Ltd .; Surfcom, and a scanning tunneling microscope such as Digitalscope II; Nanoscope II. Manufactured by Elionix; ERA-
An electron microscope such as 3000 is used.

[0004]

However, all of these conventional surface shape measuring instruments are for measuring the surface of a magnetic layer in a non-contact state by fixing a sample piece in the atmosphere or in a vacuum. Is unable to measure the surface shape when it is in contact with the magnetic head or the like. Since the surface of the magnetic layer in practical use is in contact with the magnetic head, etc., elasto-plastic deformation due to contact force occurs compared with the surface shape in the non-contact force state measured by these conventional surface shape measuring machines. ing. Also, in soft materials such as magnetic tapes and floppy disks, or in composite materials thereof, the deformation of the convex portion is particularly large among the surface irregularities due to the contact force, so the conventional surface profile measurement results show various characteristics of the magnetic recording medium. There was a problem that could not be fully clarified.

[0005]

The present invention has been made as a result of various studies for improving such a drawback, and a light beam is applied to the surface of an object to be measured, and the reflected light is utilized to perform an optical method. In a measuring method for measuring the surface shape of an object to be measured, at least a part of the surface of the object to be measured is brought into contact with or brought close to a distance of 0.1 mm or less at the same time with a light-transmitting contact body that transmits a measuring ray. The back surface of the object to be measured is pressed with a fluid pressurized to atmospheric pressure or higher, and while the surface of the object to be measured is pressed against the light-transmitting contact body, a light beam is applied to the surface of the object to be measured through the light-transmitting contact body. By measuring the surface shape of the object to be measured by an optical method, the surface shape of the object to be measured can be measured under a contact condition close to a practical state.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the surface shape 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 in a sealed state on the pressing container 2 via a packing ring 3 and is brought into contact with the surface of a light-transmissive abutting body 5 which is supported by a sample holder 4 so as not to rise.
It is sandwiched via a spacer ring 6 so as to be close to a distance within 0.1 mm.

The pressure vessel 2 is connected to a pressure regulator 8 by a pressure tube 7, and when a pressure fluid 9 such as gas or liquid pressurized to atmospheric pressure or higher is supplied by the pressure regulator 8,
The back surface of the DUT 1 is pressed by the pressing fluid 9 supplied to the pressing container 2 as indicated by an arrow, and the surface of the DUT 1 is pressed against the light-transmitting contact member 5. The pressing force at this time is detected by the pressure gauge 10 attached to the pressure tube 7.

When the spacer ring 6 presses the surface of the DUT 1 against the light-transmissive abutment body 5 by the pressing fluid 9, the space between the DUT 1 and the light-transmissive abutment body 5 is reduced. An air venting gap is provided so that the air therebetween is not sealed to cancel the pressing force.

Reference numeral 11 denotes a light emitter 11a, a lens 11b, a lens 11c, an aperture stop 11d, and a lens 11.
e, a field stop 11f, and a lens 11g. The light from the light source 11 passes through the spectral filter 12 and then the light source beam splitter 1
It is reflected by 3 and goes downward.

A part of the reflected light traveling downward is transmitted through the interferometer beam splitter 15 of the lnic interferometer 14 to reach the object-to-be-measured side objective lens 16, and this object-to-be-measured side objective lens 16 causes The light-transmitting abutment body 5 is used to focus on the uneven surface of the DUT 1. Then, the light reflected on the surface of the DUT 1 is again transmitted through the light-transmitting contact body 5.
After that, it returns to the object-side objective lens 16 and further passes through the interferometer beam splitter 15 and goes upward.

A part of the light incident on the lnic interferometer 14 is reflected by the interferometer beam splitter 15 and reaches the reference surface side objective lens 17, which corrects the optical path length. A reference surface 19 is focused through the plate 18. Then, the reflected light from the reference surface 19 is
After passing through the optical path length correction plate 18, it returns to the reference surface side objective lens 17 and is reflected by the interferometer beam splitter 15 to travel upward.

At this time, the interferometer beam splitter 15
And the reflected light reflected upward by the object to be measured 1
Light reflected by the surface of the object, transmitted through the interferometer beam splitter 15, and reflected upwards to overlap and interfere with each other.
Interference fringes corresponding to the unevenness of the surface of the. Then, this interference fringe is transmitted through the camera-side objective lens 20 to the camera 21.
Then, it is converted into an electric image signal by the camera 21.

From this interference fringe, for example, K
aterine Cream: COMPARISO
N OF PHASE-MEASUREMENT AL
The surface shape of the DUT 1 can be obtained by using the fringe scanning method described in GORITHMS, SPIE Vol (1986), and the surface of the DUT 1 is in contact with the light-transmitting contact body 5. The surface shape of the DUT 1 can be measured.

Therefore, according to this method and apparatus, when the DUT 1 is used in a contact state such as a magnetic recording medium used in sliding contact with a magnetic head or the like, contact conditions close to a practical state are used. The surface shape of the DUT 1 can be measured.

Here, as the light-transmitting contact member 5, various shapes and materials that give the surface of the object to be measured 1 a contact condition close to a practical state can be used. It is necessary to select the one that transmits the measurement light beam for surface shape measurement to the minimum. Further, it is preferable that the light-transmitting contact member 5 is brought into contact with at least a part of the surface of the DUT 1, or is brought close to the surface of the DUT 1 within a distance of 0.1 mm.

When the object to be measured 1 is pressed against the light transmissive abutting body 5 with the pressing fluid 9, care must be taken not to exceed the measurement range in the height direction of the object side objective lens 16 and the like, and the surface It is necessary to correct the error in which the DUT 1 has a curved shape with respect to the shape measurement data.

Further, the pressing fluid 9 for pressing the back surface of the DUT 1 is preferably a gas or a liquid pressurized to atmospheric pressure or more, and a gas such as air, nitrogen gas, carbon dioxide gas, argon gas or water. Liquids such as oil are used.

Further, the reference surface 19 of the lnic interferometer 14
The optical path length correction plate 18 provided on the front side is such that, when the optical path length of the measuring light beam on the sample side is transmitted through the inside of the light transmissive abutting body 5, the optical path length is twice as long as the refractive index as compared with normal atmospheric measurement. Reference plane 19
It 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 that of the light-transmitting contact member 5. However, the optical path length correction plate 18 and the light transmissive abutting body 5 do not necessarily have 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 18 may be appropriately separated from the reference surface 19, and further, the same effect can be obtained by inserting it between the interferometer beam splitter 15 and the reference surface objective lens 17.

When the fringe scanning method is used as a method for obtaining the surface shape from the interference fringes, the reference surface side objective lens 1 is used.
It is preferable that the optical path length correction plate 18 and the reference surface 19 are integrally structured so that the piezoelectric element can finely move in the optical axis direction.

In the above embodiments, the optical interference method is used as the optical surface shape measuring method. However, the optical surface shape measuring method is not limited to the optical interference method.
Other methods such as an optical focus error detection method using an optical focus error detection type surface profile measuring instrument such as T-30HK may be used. -When the detection type surface profile measuring instrument is used, it can be used as it is without the need for an optical path length correction plate and the like, so it is more preferable to apply it to the optical focus error detection method.

A test example in which the surface shape of the magnetic layer surface of the video tape is measured by using the surface shape measuring apparatus shown in FIG. 1 will be described below. Test Example 1 Ferromagnetic iron metal powder (coercive force 1600 oersted, saturation magnetic 100 parts by weight 120 emu / g, major axis diameter 0.18 μm, axial ratio 10) Hydroxyl group-containing vinyl chloride resin 10〃 Thermoplastic polyurethane resin 7〃 Alumina (Particle size 0.2 μm) 8 〃 myristic acid 2 〃 red iron oxide (particle size 0.8 μm) 2 〃 cast 5H (Tokai Carbon Co., Ltd .; carbon black, particles 2 〃 diameter 20 mμ) cyclohexanone 70 〃 toluene 70 〃

This composition was mixed and dispersed in a ball mill for 96 hours, and then 5 parts by weight of a trifunctional polyisocyanate compound was added, followed by stirring for 5 minutes to prepare a magnetic paint. This magnetic coating was applied onto a biaxially oriented polyethylene terephthalate film with a thickness of 10 μm and the thickness after drying was 2.5 μm.
m after coating, drying and calendering
A video tape was made by cutting it into a predetermined width. In order to make it easier to confirm the effect of the surface profile measuring device, the calendering process was adjusted weakly, and the surface of the magnetic layer was rougher than that of a commercially available metal video tape.

Next, in the surface shape measuring apparatus shown in FIG. 1, each member shown in correspondence with the following: Light-transmitting contact member 5: Cover glass for microscope (refractive index
1.52) Pressing fluid 9: Air Measuring optical system: WYKO; TOPO-3D Linic interferometer 14: WYKO; Objective head LX-
40 partially modified and inserted with an optical path length correction plate 18 Optical path correction plate 18: Cover glass for microscope (refractive index
1.52) each, the reading of the pressure gauge 10 is set to 0 g.
/ Mm ² , 100 g / mm ² , 200 g / mm ² The surface shape of the video tape when adjusted in 3 steps was measured, and Ra (center line average roughness) and Rt (maximum height) were measured as the surface roughness. I asked.

Test Example 2 The video tape used in Test Example 1 was adhered to an optical flat surface by wetting the back surface with water so that wrinkles did not occur, and was made by WYKO; TOPO-3D on a Linic interferometer L.
An X-40 (without an optical path length correction plate) was attached, the surface shape was measured in the atmosphere, and the surface roughness Ra and Rt were obtained. Table 1 below shows the results.

[0025]

As is clear from Table 1 above, in the surface profile measuring method according to the present invention (Test Example 1), when the indicated value of the pressure gauge 10 was set to 0 g / mm ² , a test example of a normal surface profile measuring method was obtained. The result almost equal to the result of 2 was obtained. Further, when the indicated value of the pressure gauge 10 is 100 g / mm ² and 200 g / mm ² , Rt is particularly decreased as compared with the case of 0 g / mm ^2.
It can be seen that the convex portion on the surface of the tape is elastically deformed and collapsed by the contact force.

[0027]

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

[Brief description of drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measured object 2 Pressure container 3 Packing ring 4 Sample holder 5 Light transmissive abutment body 6 Spacer ring 7 Pressure tube 8 Pressure regulator 9 Pressurizing fluid 10 Pressure gauge 11 Light source 12 Spectral filter 13 Light source beer Beam splitter 14 Linic interferometer 15 Interferometer beam splitter 16 Object to be measured side objective lens

Claims (2)

[Claims] 1. A measuring method in which a surface of an object to be measured is irradiated with a light beam and the reflected light is used to measure the surface shape of the object to be measured. The light-transmitting abutting body that transmits the working light is brought into contact with or brought close to a distance within 0.1 mm, and at the same time, the back surface of the measured object is pressed by a fluid pressurized to atmospheric pressure or higher, and the surface of the measured object is exposed to light. A surface shape measuring method characterized by measuring the surface shape of an object to be measured by an optical method by irradiating a light beam on the surface of the object to be measured through the transparent object while pressing the transparent object. 2. An optical measuring means for irradiating a surface of an object to be measured with a light beam and measuring the surface shape of the object to be measured by an optical method using the reflected light, and at least a part of the surface of the object to be measured. The surface of the object to be measured is provided with means for bringing a light-transmitting contact body that transmits the measuring light beam into contact with the object or bringing the object into contact with the object within 0.1 mm and a fluid pressing means for bringing the fluid into contact with the back surface of the object to be pressed. A surface shape measuring device for measuring the surface shape of an object to be measured by an optical method by irradiating a light beam on the surface of the object to be measured through the optically transparent contact body while pressing the light-transmitting contact body.