JPS5899705A - Noncontact roughness measuring instrument - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention uses a microscope objective lens to illuminate the surface of an object with a point light source, and uses a semi-transparent mirror to project the reflected light onto two image planes. , the total amount of light is measured by a light receiver, and on the other hand, a cylindrical lens (or'LxwD
This is a roughness measuring device that uses the fact that the light that passes through the rice field is measured by a rice receiver, and the ratio of the measured light is proportional to the surface roughness of the object to be measured.

In other words, the conventional surface roughness measuring device that uses a diamond needle, which is considered the standard, comes into contact with the surface of the object during measurement, so it not only leaves scratches on the surface of the object to be measured, but also damages soft objects. Measuring the surface roughness of objects and the gentle heights of highly polished surfaces without damaging the surface is
It's impossible.

Furthermore, many conventional optical roughness measuring instruments, such as interferometer 1 scattered light measuring instrument, holography, etc., have limited applications because the value display is different from the standard one using a diamond needle, and the measurement There are disadvantages such as insufficient accuracy or being limited to measuring only slowly changing surface roughness.

In contrast, although the present invention is an optical roughness measuring instrument, it not only compensates for the above-mentioned drawbacks of the measuring device using a diamond stylus, but also improves its accuracy and display of measured values. It has the same excellent advantages as the conventional optical measuring instruments, thus compensating for the disadvantages of conventional optical measuring instruments.

Since the apparatus according to the present invention performs non-contact measurement, even if a hole is formed on the object surface, the measurement is not affected at all. Furthermore, with the measuring instrument according to the present invention, the resolving power required for roughness measurement can be selected simply by changing the magnification of the objective lens of the microscope used. However, since the measuring instrument according to the present invention uses a cylindrical lens, it is necessary to set the cylindrical lens so that the direction of the cylindrical lens is as perpendicular to the groove on the surface of the object to be measured when performing S measurement.

Inventions similar to the present invention are assigned (U.S. Patent No. 4017,
188) is a modification of the well-known conventional method of SIMON.

Simon's method uses a microscope objective lens to illuminate the surface of the object as a point image, and the light reflected from that point is
The light is focused by the same objective lens, and the amount of light at positions before and after the focal point is measured by a light receiver through a needle hole placed on the optical axis.

This measuring device uses the fact that the difference between the two measured amounts of light and the ratio of the sum is proportional to the distance between the irradiated point of the object to be measured and the objective lens. When used as a measuring device, large errors occur. In order to reduce this error, the transfer method changed the needle hole used by Simon to a receiver with a larger light-receiving surface, and also placed a slit in the front of one of the receivers to measure the amount of light in front of the focal point. did. The surface roughness measuring device uses the fact that the ratio of the amount of light passing through the slit to the total amount of reflected light is proportional to the position of the object point.

However, in the S transfer method, the diameter of the light receiving surface of the light receiver is required to be larger than the length of the slit (for example, 5ffiII) in order to measure the total amount of light passing through the slit. The generated electrical noise is proportional to the size of the light-receiving surface, and the error in measurement values increases in proportion to the noise. If the device is used in the production of industrial parts, it is usually necessary to increase the intensity of the light source. However, using a high-intensity light source may damage the surface of the object to be measured.

The present invention uses one cylindrical lens (for example, focal side 1111!2
mm ) (5”+am/0.5”mn+) is clearly reduced. This shows that the device according to the invention can measure 100 times faster than the device according to the transfer method without damaging the surface of the object to be measured.

Next, the present invention will be explained in detail with reference to examples. Fig. 1 is a schematic diagram of a measuring instrument according to the present invention, where ■ is a light source, (to) is a focusing lens, (c) is a reflecting mirror, and (g) is a schematic diagram of a measuring instrument according to the present invention. is a needle hole, (c) is a semitransparent mirror, 6 is another reflecting mirror, aS is a microscope objective lens, and QrJ is an object to be measured, which is irradiated with a point light source. (11
and (120) are light receivers, and (115) is a cylindrical lens. That is, the light beam (5J) emitted from the needle hole stem passes through a semi-transparent mirror lens (c), is reflected by the mirror group, passes through the objective lens α9 of the microscope, and forms a point image on the surface of the object to be measured at 0°. do.

The light reflected by the object (IG) passes through the original microscope objective lens αS, a portion of which passes through the semi-transparent mirror (c) and is received by the light receiving surface (110) of the light device (110). An image of the hole (to) is created and the total amount of light is measured by a light receiver (110).On the other hand, the light reflected by the semi-transparent #I (c) is
The light is focused to form an image on the image plane, but due to the cylindrical lens (115) placed in front of it, only part of the light is focused on the light receiving surface (120) of the light receiver (120), which has a small light receiving surface (120). 1
The image is imaged and measured on the second image. Note that the light receiving surface of the light receiver (No. 11) is required to be relatively large;
Since the amount of light measured by the receiver (110) is much larger than the amount of light measured by the receiver (12), the relative signal (measured amount of light) to noise ratio remains similar and therefore The surface size 110) does not significantly affect measurement accuracy.

FIG. 2 shows the relationship between the image (150) projected onto the light receiving surface (120) of the light beam condensed by the cylindrical lens (115) and the received light 1l (120). Projected image (11
), the amount of light corresponding to the part (135) is on the receiver (
120).

The third ffl shows an example of a method for processing signals obtained from two photoreceivers (11 and (120). In other words, in one home country, (110) (12)
0) (120), (200) (205)
) is an amplifier, (210) is an element that performs analog (or digital) division, (22 is the recording device 1 and GC (22
5) is a mechanical device that measures the movement of an object to be measured. That is, the signal obtained by the photoreceiver (11G) (12) is appropriately amplified by the amplifier (200) (205), and the signal from the photoreceiver (110) is converted by an analog (or digital) divider (210). A signal of the optical receiver (12) is obtained which is normalized (divided) by . This signal is used as the vertical axis signal of the recorder. Information on the position of the measured object is sent to the recorder as a signal on the horizontal axis.

The information thus recorded represents the roughness profile of the surface of the measured object.

It will be explained below that the measured value thus corresponds to the roughness of the object.

According to the movement of the object (1 (l), the position of the point image moves back and forth in the optical axis direction due to the roughness and unevenness of the surface of the object. The amount of light passing through the cylindrical lens, that is, the light receiver (1
20), the amount of light measured changes. The rate of this signal change is proportional to the roughness.

FIG. 4 is a schematic diagram of the cormorant embodiment, showing the semi-transparent mirror 14Q (first
The light beam that has passed through the translucent mirror (corresponding to the translucent mirror in the embodiment shown) is reflected by two mirrors (175) (18) (in the embodiment shown in Fig. 1) before being directly received by the receiver. The light is collected by a cylindrical lens (185), and the total amount of light is measured by a light receiver (110) having a small light receiver 1117 (11).

According to this embodiment, the electrical noise caused by the photoreceiver (110) is further reduced.

Returning to 1st FIl, the part surrounded by the dotted line in Fig. 1 is
Reflection tilted 145° with respect to three optical axes - continuation (155) (
160) (165) and an eyepiece (170), and is a device for making the present invention more effective,
Used for positioning the object to be measured during actual measurements.

In other words, the part surrounded by dotted lines is designed to move up and down in the figure, and when placed upwards (the figure shows the downward position), the reflecting mirror (155) is a light source. It stops at the same height as the kiln.

The light from the light source (a) is reflected in a straight line (without passing through the condensing lens or needle hole) by the reflecting mirrors (155), (160) and at right angles, and passes through the semi-transparent mirror 14G (c), etc., to the object surface. a
[Irradiates with objective lens a9. At this time, the object surface is illuminated not by a point light source but by diffused light.

The light from the opposite side is again focused by the objective lens α9, and then passed through the semi-transparent mirror (
It is reflected by reflection m (16-5) (placed between the semitransparent mirror (c) and the cylindrical lens (115)) toward the eyepiece. The object surface is observed through the eyepiece, and the object to be measured can be easily positioned.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the mode of use of the non-contact roughness measuring instrument of the present invention, and FIG. 2 is an illustration of the relationship between a pinhole and an image of a non-measurable object used in the non-contact measuring instrument of the present invention. Diagram showing relationships, 3rd
The figure is an explanatory diagram showing an electric circuit for performing signal processing of the non-contact roughness measuring instrument of the present invention, and FIG. 4 is an explanatory diagram showing another embodiment, a mode of use of the non-contact measuring instrument. (5;... Luminous flux 2... Object to be measured a9... Objective lens ■... Light source (c)... Reflector (to)
・・Focal lens (to) ・・Needle hole −・・Semi-transparent mirror
(c)...Semi-transparent mirror (110)...Receiver (11)
0)... Light receiving surface (115)... Cylindrical lens (1
20)...Receiver (120)...Small light receiving surface (1
30)...Image (155)...Reflector (160)
...Reflector (165)...Reflector (17G)...
Eyepiece (Figure 1, Figure 2, Figure 4) 21-

Claims (1)

[Claims] t A non-contact optical roughness measuring instrument that generates a signal corresponding to the surface roughness of an object to be measured, and projects a point image onto the surface of the object to be measured. To project the point image, a microscope objective is used, and a fluorophore is positioned behind the objective to obtain a signal proportional to the reflectance of the point on the object being illuminated by the point image. , in order to collect the light reflected from a point on the surface that is illuminated as a point image with a cylindrical lens placed in front of the focal point of the objective lens, and to obtain a signal proportional to the amount of light at the center of the light. A receiver with a small light-receiving surface is placed near the focal point of the cylindrical lens, and the signal measured by the receiver of the cylindrical lens is converted into 1 total reflected light (measured by the receiver for measuring the reflectance). a device for measuring the position of the point image on the object to be measured, by means of which the signal is proportional to the distance from a constant reference plane to the position of the point image on the object to be measured. A device that generates a signal. 2. A non-contact roughness measuring device as claimed in claim 1, in which a device that can be observed with the naked eye to position the object to be measured is added. , several reflecting mirrors are used to illuminate a wide range of the surface of the object to be measured, and a lens is used so that the irradiated surface of the object to be measured can be observed with the naked eye. On the surface of an object,
A reflecting mirror is located in front of the cylindrical lens stated in claim 1 so as to receive the reflected light and focused by the objective lens, and when performing the measurement stated in claim 1, A device that has a mechanism that mechanically shifts the position of the observation device so that it does not get in the way. 5-It is a non-contact optical roughness measuring device that generates a signal corresponding to the surface roughness of the object to be measured, and projects a point image onto the surface of the object to be measured. The objective lens of the microscope is used to project a point image, and the light reflected from the point on the surface is focused by a cylindrical lens placed in front of the focal point of the objective lens, and the center of the light is focused. In order to obtain a signal proportional to the amount of light in the area, a light receiver with a small light-receiving surface is arranged near the focal point of the cylindrical lens, and a second cylindrical lens is used to move the light receiver with a small light-receiving surface to the focus of the objective lens. and position its receiver to receive the central portion of the light focused on the focal plane of the cylindrical lens; It is equipped with a device that generates the ratio of the difference and sum of the signals measured by the receiver of the cylindrical lens, and has a position for measuring the position of a point image on the object to be measured. A device that generates a signal that is proportional to the distance to the position of the point image above. 4. A non-contact roughness measuring device that is equipped with the measuring device described in claim 5 and the observation device described in claim 5. 5. A method of measuring roughness using a non-contact roughness measuring device that irradiates a point image onto the surface of an object to be measured. A point image is projected onto the object plane by an objective lens, and the image of the irradiated point image, which is re-formed by the objective lens, is divided into two parts using a semi-transparent mirror, and the signal is compared with the total reflected light. , generate another signal proportional to the central part of the reflected image focused by the cylindrical lens, generate a new electrically processed signal from the above signal, and transfer that signal to the illuminated surface of the surface to be measured. Includes methods for displaying points as a function of position.