JPH02124412A - Position measuring apparatus - Google Patents

Abstract

PURPOSE:To continuously measure the position and displacement of a point on the surface of an object to be measured by scanning said surface by light beams in one dimension and moving said object to be measured relatively in one direction to a position measuring apparatus. CONSTITUTION:When a polygon mirror 25 is rotated, a light spot of a scanning light beam 27 is swept along a scanning locus passing points Q1, S1 on a surface 5b of an object 5 to be measured. The reflecting light 7 passes a condensing lens 6 to be incident upon a photoreceptor 9, whereby an image is formed on the receiving surface of the photoreceptor 9. When the image of the light spot irradiating the surface of the object 5 to be measured is formed on the receiving surface of the photoreceptor 9, a detection signal 20a indicating data of coordinates of the position corresponding to the position where the image is formed is output through an operating unit 20. When the signal 20a and a direction signal 29a of the light are input to a signal processing unit 31, the unit 31 calculates a constant based on the value of the signal 20a, and also extracts and operates a function stored beforehand in a memory for every angle alpha on the basis of the signal 29a, with outputting a measurement signal 31a corresponding to each irradiating point of the beam 27.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention measures the position and displacement of an object to be measured by emitting a light beam with good directionality toward an object to be measured and emitting the reflected light. The present invention relates to a position measuring device, and particularly to a position measuring device suitable for measuring the surface contour of an object to be measured having an uneven surface.

[Conventional technology]

In this type of position measuring device, a light beam emitted from a projecting optical system is irradiated toward the object to be measured, and the reflected light is sent to the light receiving element of the receiving optical system, which is placed on a different optical axis from that of the projecting optical system. A system in which an image is formed on a light-receiving surface and the position and displacement of the object to be measured are detected as a change in the image-forming position on a light-receiving element is disclosed in, for example, Japanese Patent Application Laid-Open No. 119006/1983. be.

Next, in Fig. 5 which shows the configuration of the optical system of the position measuring device described above, 1 is a light source using a laser oscillator or the like that emits illumination light 2 with good directionality, and the irradiation light emitted from light source l is Light 2 passes through a projection lens 3 and becomes a focused light beam 4
A part of the reflected light 7 that is irradiated onto the surface 5b of the object to be measured 5 and reflected and scattered at the irradiation point 5a is reflected by the condenser lens 6.
The light becomes focused light 8 through the light, and is incident on a light receiving element 9 as a -dimensional position detecting element. Further, 2o in the figure is a calculation unit that performs a predetermined calculation based on the output signal from the light receiving element 9 and outputs the position detection signal 20a.
In combination, the one-dimensional position detection section 21 is configured. Furthermore, 22 is a signal value correction section that performs a predetermined signal value correction calculation on the position detection signal 20a and outputs a measurement signal 22a, and a combination of these components constitutes the position measuring device 23.

On the other hand, the light receiving element 9 is a diffused type PIN photodiode 10 as shown in FIG.
is a p-type semiconductor region, and a pn junction 13 between the two is formed in a plane perpendicular to the plane of the paper. In addition, 14 is the pn junction 1
Electrodes 15 and 16 are provided on the outer surface of the substrate 11 facing the center position A of 3, and electrodes 15 and 16 are provided on the outer surface of the p-type semiconductor region 12 facing both ends of the p-n junction 13. Also,
17 and 18 are resistors whose one ends are connected to the electrodes 15 and 16, and 19 is a power source. With this configuration, the focused light 8 reflected from the object to be measured 5 shown in FIG. 5 enters the pn junction 13 from the p-type semiconductor region 12 side.

When the focused light 8 enters the light receiving element 9 from the outside onto the WB above the pn junction 13, a photocurrent 11+ts is generated in the electrodes Is, 16 corresponding to the incident position B. Further, if the distance between the incident position B and the center position A is D, then the formula +1) of Kiki holds true.

D−L−′−(ir −1d/ (l + + is
) --(tl Note that II+ 1m is each resistor 1
7.18 The photocurrent flowing through , , is a proportionality constant. Then, the above-mentioned calculation unit 20 calculates the equation (1) and outputs the detection signal 20a corresponding to the value 2 expressed by the equation (21) of the rise.

2- Kl -(D -K1)-Kl -D -・-(
21 Note that Km and L in equation (2) are both proportionality constants. That is, when the focused light 8 reflected by the object to be measured 5 enters the light receiving element 9, the 1jlX section 20 performs calculation based on the photocurrent 1+t it, and calculates the position 1 coordinate corresponding to the incident position 1B of the focused light 8. detection signal 20 having information of
Output a.

As shown in FIG. 7, when the object to be measured 5 is displaced back and forth along the optical axis of the light beam 4 during measurement, the imaging position of the focused light 8 incident on the light receiving element 9 corresponds to the amount of displacement. (
The incident position 2B) is now displaced on the pn junction 13 of the photodiode 10.

Here, each point on the axis of the light beam 4 that has an optical conjugate relationship with points A and B on the pn junction 13 is ^.

If the distance between these two points B^,, B1 is L, then the distance j
The relationship expressed by equation (3) holds true between lL and D in equation (2) above.

D-f(L) ---・-・・・(3) Furthermore, (
In equation 3), f is a monotone function. Therefore, as mentioned above (
From the equation 2) and the +31 equation, the equation (41) of Kiki is obtained.

L=f (z/Kt) ・−・−(4) Note that (4) Take’s calculation is performed by the signal value correction unit 22 shown in FIG.
is performed based on the detection signal 20a and output as a measurement signal 22a.

Therefore, from the measurement signal 22a obtained by the position adjustment VT position 23, PI! Reference point As of measurement object 5 (7th
(see figure) can be used to measure displacement. For example, for a measured object 5 having an uneven surface, the height of the unevenness corresponding to the irradiation position position B of the light beam 4 on the measured object 5 is moved to the position 〇, using the above-mentioned position as a reference. It can be measured by comparing

[Problem to be solved by the invention]

By the way, when measuring and inspecting the state of the surface of the object to be measured 5 (the surface contour of the uneven surface 1, etc.) using the conventional position measuring device 23 described above, a series of steps are required.

That is, when measuring the surface state of the object to be measured 5, the surface of the object to be measured is irradiated with a light beam while the position measuring device 23 and the object to be measured 5 are moved relatively and two-dimensionally. It is necessary to measure continuously. To do this, conventionally, the object to be measured is mounted on an X-Y table, etc., and faced to a position measuring device, and the surface of the object to be measured is scanned with a light beam emitted from the measuring device by moving the X-Y table. Measurements are made in this way.

However, this method has the problem of requiring a long time for measurement and inspection, and if the object to be measured 5 cannot be mounted on an X-Y table and can only be moved in a specific direction, Surface measurement cannot be carried out in this state. Therefore, as shown in FIG. By performing measurements while linearly moving in the direction of arrow P, it is possible to measure the two-dimensional surface of the object to be measured 5. However, this measurement method requires a large number of position measuring devices 23, so surface measurement is not possible. The device Ft24 is large in size and the cost of the device is high (in addition, there is a drawback that measurement blank areas remain between adjacent position measurement values [23]).

In other words, in the conventional position measuring device 23, since the optical axis of the light beam emitted from the light source toward the object to be measured is fixed, it is difficult to measure surfaces such as surface irregularities 1 and contours of the object to be measured. However, this method required many complicated procedures, making it difficult to carry out measurements efficiently.

The present invention has been made in consideration of the above points, and by combining a light beam scanning means with a light projecting section, the uneven surface of the object to be measured can be easily moved by moving the object to be measured one-dimensionally in a fixed direction. An object of the present invention is to provide a position measuring device that can easily measure surface conditions such as surface contours.

(Means for Solving !l1fi) In order to solve the above problems, the fifth aspect of the present invention is to provide a measuring device which consists of a combination of a light source and a light beam scanning means, and a highly directional light beam emitted from the light source. a light projecting section that scans the light beam one-dimensionally toward the object to be measured, and a light receiving section that deflects the reflected light of the scanning light beam irradiated onto the object to be measured and makes it enter the light receiving element of the one-dimensional position detection section. a light direction detection section that outputs a light direction signal corresponding to the direction of the scanning light beam emitted from the light projection section; and a position detection signal that is outputted from the one-dimensional position) and light direction detection section, respectively. and a signal processing section that performs a predetermined calculation based on the light direction signal and outputs the amount of displacement of the light beam irradiation position on the object to be measured with respect to the reference position.

In addition, as another means, the one-dimensional position detection section and the light direction extraction section in the above configuration can be used to detect information on position coordinates corresponding to the scanning locus of the light beam irradiated onto the object to be measured, and to correspond to the displacement of the object to be measured. It is also possible to replace it with a two-dimensional value '11 detection section that outputs two types of position detection signals including information on position coordinates.

[Effect]

In the above configuration, for example, a polygon mirror is used as the light beam scanning means, and by rotating the polygon mirror, the light beam emitted from the light source is reflected on the mirror surface to one-dimensionally scan the surface of the object to be measured. scan in a straight line. In addition, the optical system consisting of the light emitting part and the light receiving part satisfies the Scheimpflug condition and at least reflects light from the object to be measured even if the object to be measured is displaced within the scanning range of the light beam described above. The light beam 7) is arranged so that its trajectory is incident on the light-receiving surface of the position detection section.

With this configuration, during measurement, the light beam emitted from the light projecting section scans the surface of the object to be measured in a one-dimensional manner, and the light receiving section detects the position corresponding to the irradiation position of the light beam scanning the surface of the object to be measured. The value of the position detection signal output from the unit changes. Further, in the position detection unit 13, a conversion calculation corresponding to the scanning direction of the light beam is performed in the signal processing section, and the result is output as a measurement signal proportional to the displacement of the light beam irradiation position with respect to the reference position. Therefore, by scanning the surface of the object to be measured one-dimensionally with a light beam and at the same time moving the object to be measured relatively one-dimensionally by illuminating the positioning device, it is possible to scan the surface of the object to be measured with a light beam. It is possible to continuously measure the surface contour of an object, or the position and displacement of points on the surface.

〔Example〕

1, 2, 3, and 4 show different embodiments of the present invention, and the same members corresponding to FIG. 5 are given the same reference numerals.

First, in the embodiments of FIGS. 1 and 2, 25 is the light a1
A polygon mirror 28 is configured to reflect the light beam 4 emitted from the mirror, and to manipulate the surface 5b of the object to be measured 5 one-dimensionally to scan the surface 5b of the object to be measured 5 by using the light beam 4 as a scanning light beam 27 by rotating the motor 26. light s1. Projection lens 3. Polygon mirror 25. This is a light projecting unit that is combined with a drive motor 26. Further, 29 is coupled to the shaft of the drive motor 26 of the polygon mirror 25, and is connected to the shaft of the drive motor 26 of the polygon mirror 25, so that the object to be measured is
This is a light direction detection section that detects the irradiation angle α of the scanning light beam 27 irradiated toward the light direction and outputs a light direction signal 29a.

Note that the irradiation angle α represents the angle between the scanning light beam 27 and a vertical imaginary line erected on the surface 5b of the object to be measured 5.

With this configuration, the surface of the object to be measured 50 is one-dimensionally scanned by the scanning beam 27 by rotating the polygon mirror 25.

On the other hand, the light receiving unit 30 includes a light receiving lens 6 that focuses the reflected light 7 from the object to be measured 5 and converts it into a focused light 8, a light receiving element 9 as a -dimensional position detecting element, and arithmetic processing of the output signal of the light receiving element 9. 31 is a signal processing section, which detects the detection signal 20a outputted by the -dimensional position detection section 21 and the light direction signal from the light direction detection section 29. 29a, performs predetermined calculations to be described later based on these two inputs (No. 8), and outputs a measurement signal 31a representing the amount of displacement of the object to be measured 5 with respect to a predetermined reference position. In combination, a vertical measuring device 32 is configured.

Next, a measurement operation by the position measuring device 32 having the above configuration will be explained. First, in the measurement state shown in the figure, the polygon mirror 2
5, if the surface 5b of the object to be measured 5 is in a solid line state, the light spot of the scanning light beam 27 is scanned on the surface 5b along a scanning locus passing through points Q, , Sl, and the reflected light 7 The light passes through the condenser lens 6 and enters the light receiving surface 9, where it is imaged on the light receiving surface. Here, the above point Q,
The image of the light spot formed at S is located at a position Q on the light-receiving surface of the light-receiving element 9, which is in an optical conjugate relationship with points Q,, Q□.
++ Imaged on Sl.

Furthermore, if the surface of the object to be measured 5 is bulged in a convex shape as shown by the tI line at the points Q+ and St, then the scanning light beam 27 forms a convex surface at a point Ql+58 on these bulges. The image of the light spot is located at the position Q! on the light-receiving surface of the light-receiving element 9! It comes to be imaged at 131.

In this way, when the image of the light spot irradiated onto the surface of the object to be measured 5 is formed on the light receiving surface of the light receiving element 9, the image forming position q++Qx+ 5++ is determined through the arithmetic unit 20.
Detection signal 20a representing information of position coordinates corresponding to sj
is output. In addition, in this case, the above (31 formula, (4
) It is clear that the function f shown in the equation differs depending on the irradiation angle α of the scanning light beam 27. In addition, in the above, it was assumed that 8 shown in equation (4) is a constant, but in reality, this is 2 due to the nonlinearity of the signal conversion characteristics in each of the light receiving element 9 and the arithmetic unit 20. It is a function of

On the other hand, the signal processing unit 31 receives the detection signal 20a described above.
, and the optical direction signal 29a are input, the signal processing unit 31 calculates 8 for the above-mentioned constant based on the value 2 of the detection signal 20a, and also calculates a signal for each angle α in advance based on the optical direction signal 29a. Function f stored in the memory of the processing unit 31
is extracted, the calculation of equation (4) is performed, and a measurement 4g number 31a corresponding to each irradiation point of the scanning light beam 27 on the surface of the object to be measured 5 is output.

Therefore, if the surface 5b of the object to be measured 5 shown by the solid line in FIG.
Displacement of , (distance between points Q, , Q), L8-1
The surface condition M (uneven surface) of the object to be measured 5 along the scanning locus of the scanning light beam 27 including the distance m> 1Jl+s.

contour) can be measured continuously. In addition to the scanning of the light beam by the rotation of the polygon mirror 25 described above, by relatively moving the target fixed object 5 in the direction of the arrow P as shown in the second [1], the target dl! The state of the surface 5b of the constant object 5, that is, the surface irregularities 1 and the surface contour can be measured two-dimensionally.

Next, FIGS. 3 and 4 show another embodiment of the present invention. This embodiment is basically the same as the previously described embodiment, but
Light receiving element 9 as a one-dimensional position detecting element in the first U4. and a two-dimensional position detection section that can simultaneously obtain information on position coordinates corresponding to the scanning locus of the scanning light beam and information on position coordinates corresponding to the displacement of the object to be measured, in place of the light direction extraction section 29. The structure was simplified by adopting the following. That is, in FIG. 3, reference numeral 33 indicates a two-dimensional position detection element (light-receiving element), and a two-dimensional position detection unit 35 of the light-receiving unit 30 is constituted by a calculation unit 34 connected at the subsequent stage, and a second In combination with the light projecting section 28 similar to that shown in FIG. 1, the main part of the position measuring device 36 is configured. Note that the same parts as in the embodiment shown in FIG. 1 are given the same reference numerals.

On the other hand, the aforementioned two-dimensional position detection element 33 employs a diffused PIN photodiode having the structure shown in FIG.
In the figure, 11 and 12 are an n-type semiconductor substrate and a p-type semiconductor substrate, respectively.
type semiconductor region, and a pn junction 13 is formed in a rectangular shape between the two. Reference numeral 14 denotes an electrode provided on the outer surface of the substrate 11 facing the center position A of the pn junction 13;
a, 15b, and 16a, 16b are pn
ti arranged so as to face each other perpendicularly to the periphery of the joint 13, and each of the molds 115a described above.
, 15b, and 16a, 16b are connected to resistors 17a, 17b, and 18a, 18b, respectively, and a power source 19 is connected between them and the center electrode 14.

In other words, based on the structure of the photodiode shown in Figure 6,
Two sets of electrodes 15a and 6a are provided around the p-type semiconductor region 12.
15'b and 16b are installed perpendicularly to each other.

With such a configuration, an X-Y axis with the central position ':It,A on the light receiving surface as the origin, the direction in which the electrodes 15a and 16a face each other as the X axis, and the direction in which the electrodes 15b and 16b face each other as the Y axis.
In the orthogonal coordinate system, when a light beam is incident from the outside at position B of (D x, D y) in the same way as the light receiving element described in Fig. 6, the coordinate values (D x, D y) and the light generated in the element are There is a revolt between the current and the current.

Dx −KIi= (++ −Its) / (1+a
+ 1ta)・---(51 oy 'K+b= (f+b-1zb)/(i+
b+ 1zJ In addition, in the above formula, 'la+ f2m +'l
b+ lzb are resistors 17a, 17b, 1, respectively
Light flowing through 8a and 18b? It style, Kla+Klk
is a proportionality constant.

Further, the optical signal '1m+ '□a+llk+ 11 outputted from the two-dimensional position detecting element 33 is taken into the arithmetic unit 34 at the subsequent stage shown in FIG. The calculation is performed to output position detection signals 34a and 34b represented by za and zb in the following equations.

Za"Koa' (+a to DX') = to! +1・I
)x−-(71zb=Kob・(DY・K+b)=
Kzb・Dy"-' [slIn addition, in the above formula, Kta+Kx
h is a proportionality constant.

On the other hand, when scanning the surface 5b of the fixed object 5 with the scanning light beam 27, the two-dimensional position detection element 33 moves along a scanning trajectory 37 using a reference position A defined on the surface (Xo
The reflected light spot of the scanning light beam 27 traveling in the force direction is arranged so as to move on the X-axis of the orthogonal coordinate system on the light receiving surface of the two-dimensional position detection element 33. Therefore, the irradiation position 5a, which is distanced by x from the reference position A6 on the scanning locus 37, is determined by the following equation (9) in the two-dimensional position detection unit 35 from the relationship of the above equation (61, T7+). Information on the first coordinate corresponding to the scanning locus of the light beam irradiated onto the object to be measured is output from the calculation unit 34 as a detection signal 34a.

L x = Ka - D x = Ka ・(za-Kta
”) −・−19+In addition, in FIG. 3, if the surface of the object to be measured 5 is displaced (dashed line) in the direction perpendicular to the scanning locus 37 of the scanning light beam 27 (Yo force direction), then the 1. The reflected light spot of the scanned light beam 27 moves in the Y-axis direction of the above-mentioned orthogonal coordinate system on the light receiving surface of the two-dimensional position detection element 33.Therefore, the irradiation position 5a of the object to be measured 5 is the reference point. In a state where the distance Ly is displaced from the surface in the Yo direction, the irradiation position 5a is determined by the following equation based on the above-mentioned relationship (8) 2, and information on the position coordinates corresponding to the displacement of the object to be measured is obtained. is the detection signal 34
It is output from the arithmetic unit 34 as b.

Ly=fb(Dy)=Kb・(zb−K,)−
-Ql Note that in the above equation, rb is a predetermined function.

Therefore, in the position measuring device 36 having the above configuration, when the surface 5b of the object to be measured 5 is scanned with the scanning light beam 27, the locus of the irradiation position 5a on the surface 5b is the object to be measured 5 in a plane parallel to Xo-Yo. This will match the cross-sectional contour. Then, Xo− with the origin at the reference position Ao on the surface
The coordinate value (L
x, Ly) have a one-to-one correspondence with the coordinates (1(Dx, Dy) on the light-receiving surface of the two-dimensional position detection element 33. Therefore, the detection signal 34a output from the calculation unit 34,
34b, the surface contour of the object to be measured 5 along the scanning locus 37 of the scanning light beam 27 is measured. Moreover, the scanning of the scanning light beam 27 described above is performed by the polygon mirror 25.
By moving the object to be measured 5 relatively in the direction of the arrow P shown in the figure, the surface condition of the object to be measured 5, that is, the surface contour of the uneven surface 2 can be measured.
Alternatively, position measurements of points on the surface can be carried out continuously.

〔Effect of the invention〕

Since the position measuring device according to the present invention is configured as described above, it exhibits an excellent effect.

(1) Incorporating a light beam scanning means into the position detection device,
By scanning the light beam emitted from the light projector one-dimensionally over the surface of the object to be measured during measurement, the measuring device,
In this state, the surface condition of the object to be measured along the scanning locus of the scanning light beam can be measured without relatively moving the object to be measured.

(2) In addition to the above-mentioned light beam scanning, by linearly moving the object to be measured in a fixed direction relative to the measurement Surface Roughness 9 The surface contour or the position of a point on the surface can be measured continuously and in a short time.

(3) Therefore, in terms of equipment, such as mounting the object to be measured on an X-Y table or arranging multiple measuring devices in an array to measure the object as in conventional measurement methods A position measuring device with high practical value in terms of function and use can be obtained, since there are no restrictions on the measurement area, and there is no occurrence of measurement blanks on the surface to be measured.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the position measuring device of the present invention, FIG. 2 is an explanatory diagram of the operation of the embodiment shown in FIG. 1, and FIG. 3 is a block diagram of a different embodiment of the present invention. Fig. 4 is a detailed structural diagram of the two-dimensional position detection element in Fig. 3, Fig. 5 is a structural diagram of a conventional position measuring device, Fig. 6 is a detailed structural diagram of the light receiving element in Fig. 5, and Fig. 7 is a detailed structural diagram of the light receiving element in Fig. 5. FIG. 5 is an explanatory diagram of the measurement operation, and FIG. 8 is a configuration diagram of a conventional surface measuring device. 1: Light source, 2: Irradiation light, 3: Projection lens, 4: Light beam, 5: Measured object, 6: Condensing lens, 7: Reflected light, 8:
0 focused beam, 9 1-dimensional position detection light receiving element, 20: calculation section, 20a 2 detection signal, 21 2 1-dimensional position detection section, 25:
Polygon mirror (light beam scanning means), 27: scanning light beam, 28: light projecting section, 29: light direction detecting section, 30: light receiving section, 31: signal processing section, 31a: measurement signal, 33: two-dimensional position Detection element, 34: calculation section, 35: two-dimensional position detection section. Ao 13Figure 4Figure 6

Claims (1)

[Claims] 1) A position measuring device that measures the position and displacement of an object to be measured by irradiating a light beam onto the object to be measured and detecting the reflected light, the device comprising a light source and a light beam scanning means. Consisting of a combination,
A light projection unit that scans a highly directional light beam emitted from a light source toward the object to be measured in a one-dimensional manner, and one-dimensional position detection by condensing the reflected light of the scanning light beam irradiated on the object to be measured. a light receiving section that makes the light enter the light receiving element of the section; a light direction detecting section that outputs a light direction signal corresponding to the direction of the scanning light beam emitted from the light projecting section; and the one-dimensional position detecting section and the light direction detecting section. and a signal processing section that performs predetermined calculations based on the position detection signal and the light direction signal that are output, respectively, and outputs the amount of displacement of the light beam irradiation position on the object to be measured with respect to the reference position. measuring device. 2) A position measuring device that measures the position and displacement of an object to be measured by irradiating a light beam onto the object to be measured and detecting the reflected light, comprising a combination of a light source and a light beam scanning means,
There is a light projection part that scans a highly directional light beam emitted from a light source toward the object to be measured in a one-dimensional manner, and a position detection part that focuses the reflected light of the scanning light beam irradiated on the object to be measured. A light receiving section that makes the light enter the light receiving element, and a signal processing section that performs predetermined calculations based on the position detection signal output from the position detector and outputs the amount of displacement of the light beam irradiation position on the object to be measured with respect to the reference position. and the light receiving element of the position detection unit detects two types of positions, including information on position coordinates corresponding to the scanning locus of the light beam irradiated onto the object to be measured, and information on position coordinates corresponding to the displacement of the object to be measured. A position measuring device characterized by being a two-dimensional position detecting element that outputs a detection signal.