JPS62238403A - Apparatus for measuring surface shape - Google Patents

Abstract

PURPOSE:To enhance measuring accuracy and a measuring range and to shorten a measuring time, by finely adjusting a precise detection means corresponding to the detection result of a rough detection means receiving the reflected light from a measuring surface. CONSTITUTION:Light is allowed to irradiate a measuring surface such as a rotary surface and the reflected light therefrom is received by a rough detection part 16 having a wide measuring range and rough detection output corresponding to a surface state is converted to a digital value by an A/D converter 27 through an amplifier 25 to be supplied to a memory 28 or a display device 29. The output of the amplifier 25 is also supplied to a piezoelectric element 20 through a switching circuit 26 and the precise detection part 19 having a small opening of an objective lens is automatically and finely adjusted corresponding to the rough detection result to detect the surface state with high accuracy. By this method, measuring accuracy is enhanced and a measuring range is enlarged and a measuring time is shortened by automatic adjustment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surface shape measuring device that measures the state of the surface shape of a surface to be measured, and particularly relates to a surface shape measuring device that can improve measurement accuracy. .

[Prior Art] Fig. 4 is a block diagram showing the configuration of a conventional surface profile measuring device. In the figure, (1) is a light source, and (2) is a beam expander for converting light into parallel light. , (3) is a polarizing beam splitter for separating incident light and reflected light, (4
) is the lunar wave plate, (5) is the objective lens to focus the light, (
θ) is the object to be measured, (7) is a beam splitter that separates the light reflected on the surface of the object to be measured (6) into two directions, (8
a) and (ab) are cylindrical lenses for imparting astigmatism to the reflected light; (9a) and (9b) are four-segment photodiodes for photoelectrically converting the amount or intensity fluctuation of the reflected light;
(13) is a mounting base for fixing the object to be measured (8);
14) is a fine movement table for moving the object to be measured (6), (
15) is a pulse motor that operates the fine movement table (14).

Next, the operation of the above-mentioned conventional device will be explained. light 8 (1)
The light emitted by the beam expander (2) expands the light into parallel light, and then passes through the polarizing beam splitter (2).
3) and the substrate wavelength plate (4), a spot light of about 2 gm is imaged onto the object to be measured (6) by the objective lens (5).

Next, the light reflected on the surface of the object to be measured (θ) passes through the objective lens (5) and the three-wavelength plate (4), is reflected by the polarizing beam splitter (3), and is transmitted to the beam splitter (7).
), the optical path is divided into two, and the cylindrical lens (8a) and (8
After astigmatism is imparted by b), the amount of light is converted into an electrical signal by the four-segment photodiodes (8a) and (θb).

When the light emitted by the light source (1) is focused on the object to be measured (6), the reflected light forms a circular image (10) on the four-split photodiodes (9a) and (9b). become.

Also, when the object to be measured (6) approaches the objective lens (5) and is located within the focal point, it forms an elliptical image (11) with the long axis vertical, and when the object to be measured (6) moves away from the objective lens (5), When located out of focus, the long sleeve becomes a horizontal elliptical image (12). The shape of the light image, which changes depending on the position of the surface of the object to be measured (6), is measured by four-split photodiodes (9a) and (9).
By performing photoelectric conversion and calculation according to b), an electrical output signal corresponding to the surface position of the object to be measured (6) is obtained.

Next, the object to be measured (8) is attached to the fine movement table (14) via the mounting base (13), and the fine movement table (14) is driven by the pulse motor (15) to move the object to be measured.

The surface shape of the object to be measured (8) is measured by moving the object to be measured (8) and recording changes in the output of the four-part photodiode on a pen recorder (not shown) or the like.

[Problems to be solved by the invention] Since the light spot diameter of the conventional surface shape measuring device is about 2 pm, it is necessary to move the object to be measured at a rate of 1 m in order to measure the shape of a wide surface. Therefore, measurements must be taken for several hundred to several years, and the measurement range is 0.
．． 001 gm to 2 gm, there were problems such as it being impossible to measure the shape of a machined surface having surface irregularities of gm grade or higher.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a surface shape measuring device that can improve measurement ability, particularly measurement accuracy and range, and shorten measurement time.

[Means for Solving the Problems] The surface shape measuring device according to the present invention has the ability to irradiate a surface to be measured with light and detect the state of the surface shape of the surface to be measured based on the reflected light from the surface to be measured. The present invention is configured to include a plurality of detection means having different values, and to detect the state of the surface shape of the surface to be measured by finely adjusting the detection of the other detection means based on the detection result of the one detection means.

[Function] The surface shape measuring device according to the present invention measures irregularities and waviness of ILm grade or higher on the surface of the object with one detection means forming a rough detection section, and further finely detects signals corresponding to the irregularities and waviness. It is sent to the detection section, and is driven to follow the irregularities and undulations by another detection means forming a fine detection section, and detects surface roughness on a metmeter level and minute protrusions.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In Figure 1, (1B) is a coarse detection section with a wide measurement range, and (17) is a fine movement table for moving the coarse detection section (18).This fine movement table (17) is driven by a pulse motor (18). be done. (19) is the rough detection part (
(20) is a piezoelectric element for driving the fine detection part (18) in the vertical direction, and the other end of this piezoelectric element (20) To,
Fine movement table (17) driven by pulse motor (1B)
) is attached. A fine detection section (19) is arranged on the opposite surface of the coarse detection section (1B), and (21) is an objective lens for narrowing down the light.
), the aperture ratio is set larger than that of the (22) is a stage that fixes the object to be measured (6), (23) is a motor that rotates the stage (22), and (24) is a rotation that generates a pulse signal according to the rotation of the stage (22). It is a number detector.

In FIG. 2, (25) is an amplifier for amplifying the electrical signals of the coarse detection section (16) and the fine detection section (19);
26) is a switching circuit that corrects the deviation in relative position between the coarse detection section (16) and the fine detection section (19). After correcting the amount of deviation, voltage is applied to the piezoelectric element (20) and the fine detection section (19) is driven. (27) is the rough detection part (1B)
and an A/D converter for digitizing the electrical signal from the microdetector (18), (28) is a memory for storing the signal from the A/D converter (27), and (29) is a signal This is a display device for processing.

Next, the operation of this embodiment will be explained. Rough detection part (1
In B), the aperture ratio of the objective lens (21) is set so that the measurement range is about 4 m to 80 pm, and the undulations and irregularities of the object to be measured (6) of 7 tm class or higher are detected, and the fine detection part (
1θ), the aperture ratio of the objective lens (5) is set so that the measurement range is about 0.001 pm to 2 ILm, and surface roughness and minute protrusions below the GM grade are detected.

First, the object to be measured (6) is attached to the stage (22), and the zero rotation detector (24) is rotated by the motor (23).
The rotational speed of the stage (22) is detected, and after the rotational speed has settled to a certain level, the surface shape of the object to be measured (8) is measured by the rough detection section (1B) and the fine detection section (19). . At this time, as shown in FIG. 2, the electrical signal corresponding to the surface shape of the object to be measured (6) detected by the rough detection section (16) is amplified through the amplifier (25) and transmitted to the piezoelectric element (2).
0) and detected by the coarse detection section (1B).
6) Fine detection part (18) to follow the undulations and unevenness of
is driven by a piezoelectric element (20), and the surface of the object to be measured (8) is controlled to fall within the measurement range of the W1 detection section (19).

The coarse detection section (1B) and the fine detection section (18) are arranged at opposing positions, and these two detection sections (1B) and (t8)
The relative positional shift between the amplifier (25) and the piezoelectric element (2
A switching circuit (26) is provided between the piezoelectric element (20) and a switching circuit (26) is provided between the piezoelectric element (20) to electrically correct the signal from the rough detection part (16) by delaying the signal by a time corresponding to the amount of relative position deviation and sending it to the piezoelectric element (20). Therefore, the coarse detection section (1B) and the fine detection section (
Even if there is a relative positional shift of the object to be measured (8)
It becomes possible to measure the surface shape of the same location.

The signals output from the coarse detection section (16) and the fine detection section (19) are digitized by the A/D converter (27) and stored in the memory (28), and also displayed on the display device (28). The surface shape can be monitored and visually observed. As shown in Figure 3, the surface shape (3o) of the object to be measured (6) has waviness (31) of 7zm class or higher and gm
It has a surface roughness below grade 32). Rough detection part (1B
), the surface shape detected is the waviness (3
1), and the fine detection section (19) detects surface roughness 32) of JLm grade or below.

Since the fine detection part (19) is driven by the piezoelectric element (2o) to follow the waviness (31) below the GM grade, the waviness component is removed and the surface roughness (32) below the GM grade is removed. Only the components are detected. Rough detection part (1B
) Waviness (31) of pm grade or higher detected by the microdetector (19) and surface roughness of g, m grade or lower detected by the fine detection part (19) 3
2) by the display device (29),
The surface shape (3o) of the object to be measured (6) is obtained.

After the measurement at a predetermined position of the object to be measured (8) is completed, the coarse detection section (16) and the fine detection section (19) are controlled by a fine movement table (17) driven by a pulse motor (18). The object to be measured (6) is moved and the above operations are repeated until the entire surface of the object (6) to be measured is scanned to determine the shape of the surface 311 times.

In the above embodiment, the piezoelectric element (2o) is used in order to make the fine detection part (19) follow the undulations of GM grade or higher, but the objective lens (5) in the fine detection part (19) is It is also possible to follow undulations of a magnitude of jLm or higher by moving the coil in the vertical direction.

In addition, although the above embodiment has a configuration including two detection units, it is also possible to include two or more detection units, and to sequentially or alternatively transmit the detection results of other detection units between the plurality of detection units. It is also possible to adopt a configuration in which detection is finely adjusted by using the above.

[Effects of the Invention] As described above, the surface shape measuring device according to the present invention has the ability to irradiate a surface to be measured with light and detect the state of the surface shape of the surface to be measured based on the reflected light from the surface to be measured. The present invention has a configuration in which a plurality of detection means are provided for detecting differently, and the state of the surface shape of the surface to be measured is detected by finely adjusting the detection of the other detection means based on the detection result of the above-mentioned one detection means. Therefore, the detection means can be adjusted to match the surface shape of the surface to be measured, and the state of the surface shape of the surface to be measured can be measured with high precision. Moreover, there is an effect that the measurement time can be shortened.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a surface shape measuring device according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a control section according to an embodiment of the invention, and FIG. FIG. 4 shows a signal waveform diagram for shape signal processing and a configuration diagram of a conventional surface shape measuring device. (16)... Coarse detection section, (17)... Fine movement table, (1
8)...Pulse motor, (19)...Fine detection section, (
2G)...piezoelectric element, (5), (21)...objective lens, (22)...stage, (23)...motor, (24)...rotation speed detector. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] (1) Equipped with a plurality of detection means for irradiating light onto the surface to be measured and detecting the state of the surface shape of the surface to be measured based on the light reflected from the surface to be measured, with different detection capabilities; A surface shape measuring apparatus characterized in that the surface shape measuring device is configured to finely adjust the detection of another detection means based on the detection result of the detection means to detect the state of the surface shape of the surface to be measured. (2) Surface shape measurement according to claim 1, wherein the detection means is configured to detect the state of the surface shape of the surface to be measured based on variations in the amount and intensity of the reflected light. Device. (3) Surface shape measurement according to claim 1 or 2, characterized in that the other detection means has a detection range and detection ability that is higher in accuracy than the first detection means. Device.