JP2595821B2 - 3D 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 three-dimensional shape measuring apparatus, and more particularly to a three-dimensional shape measuring apparatus for objects having a surface condition close to a mirror surface to objects having irregularities or inclined surfaces.

[0002]

2. Description of the Related Art FIG. 9 is a perspective view illustrating a conventional three-dimensional shape measuring apparatus.

The three-dimensional shape measuring apparatus shown in FIG. 9 has a scanning optical system for scanning a measuring object 55 placed on a measuring table 50 having a uniaxial stage.

The scanning optical system includes a laser 51, a beam expander 52 for expanding the beam diameter of the laser 51 to a required beam diameter, and a laser beam from directly above the measurement table 50.
A galvanomirror 53 for scanning in a direction orthogonal to the feed direction of the laser beam, and an fθ lens 54 for converging the laser beam scanned by the galvanomirror 53 to a required beam diameter on the measurement surface of the measuring table 50 and scanning at a constant speed. And

[0005] Among the reflected light of the scanned laser light from the object 55 to be measured, a part of the light reflected in a direction perpendicular to the scanning direction is condensed by a condenser lens 57 from obliquely above.
7 is condensed in the scanning direction by a cylindrical lens 58, and the laser light is further condensed by a condensing lens 57.
Is received by the light receiving element 59 located at the focal position of the cylindrical lens 58.

FIG. 10 is a plan view for explaining the principle of measuring the height of the object 55 to be measured.

[0007] A laser beam is applied to the measuring object 55 from directly above, and the reflected light from the measuring object 55 is tilted at an angle θ from the incident direction of the laser through the light-receiving element 57 via the condenser lens 57.
When the magnification of the condenser lens 57 is m,
The height t of the measuring object 55 and the distance d on the light receiving element 59
The relationship between (the distance between the light receiving position of the reflected light from the height t and the light receiving position of the reflected light from the surface of the measuring table 50) is as follows.

[0008]

[0009] Therefore, the height of the measuring object 55 can be measured by measuring the displacement of the light receiving position on the light receiving element 59.

FIGS. 11 (a) and 11 (b) are plan views showing the state of reflection of a laser beam 60 on a measurement object 55 'having a rough surface and a measurement object 55 "which is close to a mirror surface.

In the case of a measurement object 55 'having a rough surface as shown in FIG. 11 (a), since the laser light is irregularly reflected, a relatively large amount of reflection occurs in a light receiving direction 61 which is set obliquely. In the case of the measurement object 55 ″ whose surface is close to the mirror surface as in b), the specular reflection component increases and the reflection in the light receiving direction 61 decreases. Therefore, in the conventional three-dimensional shape measuring apparatus shown in FIG. It is difficult to measure the height of the near surface because the S / N ratio deteriorates.

[0012]

In this conventional three-dimensional shape measuring apparatus, the laser is scanned from directly above the object to be measured, and the height is measured from above obliquely by using a part of the irregularly reflected light. On the other hand, a measurement object having a surface close to a mirror surface has a problem in that the amount of irregularly reflected components in the light receiving direction is small, and the S / N ratio of the reflected light amount is deteriorated, making measurement difficult.

[0013]

According to the present invention, there is provided a three-dimensional shape measuring apparatus comprising: (A) a measuring table on which an object to be measured is placed and stepped in one direction; (B) a laser; A beam expander that expands the diameter to a required beam diameter, a scanner that scans the laser beam passing through the beam expander in a direction orthogonal to the feed direction of the measuring table, and finally scans the laser beam scanned by the scanner. Fθ that converges to a required beam diameter on the measurement surface of the measurement table and keeps the scanning speed constant
A lens, a galvanomirror that switches the optical path of the laser light that has passed through the fθ lens in two directions in synchronization with the scanning of the scanner, and a laser beam reflected at one end point of the switching motion of the galvanomirror. A first reflection mirror that reflects a scanning trajectory from directly above to a vertically downward direction so as to be orthogonal to the feed direction of the measurement table; and a laser beam reflected at the other end point of the switching movement of the galvanometer mirror. The scanning trajectory is reflected from above so that the scanning trajectory coincides with the scanning trajectory by the first reflecting mirror, and the optical path length from the galvanomirror to the measurement surface of the measuring table is the same as the optical path length at the first reflecting mirror. (C) reflection in a reflection angle direction having an angle equal to the laser incident angle by the second reflection mirror; A condensing lens for condensing laser light, a cylindrical lens on the optical axis of the condensing lens, and condensing laser light passing through the condensing lens in a scanning direction, the condensing lens and the cylindrical lens (D) a stage control circuit for stepping the measuring table for each scan in synchronization with scanning by the scanner, and a laser beam. A first height calculating circuit for calculating the height of the object to be measured from the light receiving position of the light receiving element when the light is scanned by being reflected by the first reflecting mirror;
A second height calculating circuit for calculating the height of the object to be measured from the light receiving position of the light receiving element when the light is reflected and scanned by the reflecting mirror, and the laser light reflected by the first and second reflecting mirrors. The amount of light received by the light receiving element at the same position when scanning is performed, and the height of the first or second height calculating circuit when reflected by the first or second reflection mirror having the larger amount of received light And a signal processing circuit including a height determination circuit for selecting an operation result.

A three-dimensional shape measuring apparatus according to the present invention comprises: (A) a measuring table for placing an object to be measured; (B) a first laser;
A first beam expander for expanding a beam diameter of the first laser to a required beam diameter, a second laser having a different wavelength from the first laser, and a required beam diameter of the second laser. A second beam expander that expands to a beam diameter, a superposition optical system that superimposes two laser beams expanded by the first beam expander and the second beam expander on one beam, A scanner that scans the laser light superimposed by the superposition optical system in a direction orthogonal to the feed direction of the measurement table, and finally scans the laser light scanned by the scanner on a measurement surface of the measurement table. An fθ lens that focuses light to a beam diameter and keeps the scanning speed constant;
One of the laser light of the first laser and the laser light of the second laser that has passed through the lens transmits one of the laser lights, and the other laser light is scanned obliquely from above the measurement table by a scanning trajectory of the measurement table. The first that reflects perpendicular to the feed direction
And a reflection mirror that reflects one of the laser beams passing through the first filter from directly above the measuring table to vertically downward so that the scanning trajectory matches the trajectory of the first laser beam. A scanning optical system, and (C) a condenser lens for condensing laser light reflected in a reflection angle direction having an angle equal to the incident angle of the other laser light reflected by the first filter. A cylindrical lens that is on the optical axis of the condenser lens and condenses the laser light passing through the condenser lens in the scanning direction, and a second lens that disperses the one and the other laser lights that have passed through the cylindrical lens. A filter, and first and second light receiving elements for receiving the one and the other laser beams split by the second filter at focal positions of the condenser lens and the cylindrical lens, respectively. A light receiving optical system configured; (D) a first height calculating circuit for obtaining a height from a light receiving position of the first light receiving element; and a second height calculating circuit for obtaining a height from the light receiving position of the second light receiving element. Of the first and second height calculating circuits for comparing the amount of light received by the first light receiving element and the amount of light received by the second light receiving element and receiving the signal of the light receiving element having the larger amount of received light A signal processing circuit comprising a height determination circuit for selecting a height calculation result.

A three-dimensional shape measuring apparatus according to the present invention comprises: (A) a measuring table for placing an object to be measured; (B) a laser; and a beam expander for expanding a beam diameter of the laser to a required beam diameter. A scanner that scans the laser light expanded by the beam expander in a direction orthogonal to the feed direction of the measurement table, and finally transmits the laser light scanned by the scanner on a measurement surface of the measurement table. An fθ lens that converges to a beam diameter and keeps the scanning speed constant; a first polarization beam splitter that disperses the laser light passing through the fθ lens;
A first reflection mirror for reflecting the P-polarized laser light passing through the polarization beam splitter from directly above the measurement table to vertically downward so that a scanning trajectory is orthogonal to a direction in which the measurement table is fed; and the polarization beam splitter. The scanning trajectory of the S-polarized laser beam reflected from the
And the optical path length from the polarizing beam splitter to the measurement surface of the measuring table is equal to the optical path length of the P-polarized laser light by the first reflecting mirror. (C) a reflection angle having an angle equal to the oblique angle of the S-polarized laser light reflected by the second reflection mirror; A condensing lens for condensing the laser light reflected in the direction, a cylindrical lens on the optical axis of the condensing lens and condensing the laser light passing through the condensing lens in a scanning direction, and passing through the cylindrical lens. A second polarizing beam splitter for splitting the separated laser beam, and a condensing lens for each of the P-polarized laser beam and the S-polarized laser beam split by the second polarizing beam splitter. And a first and second light receiving element for receiving light at the focal position of the cylindrical lens, and (D) a first height for obtaining a height from the light receiving position of the first light receiving element An arithmetic circuit, a second height arithmetic circuit for calculating a height from a light receiving position of the second light receiving element, and a light receiving amount of the second light receiving element of the first light receiving element are larger by comparing the light receiving amounts of the second light receiving elements. A signal processing circuit including a height determination circuit for selecting a height calculation result of the first or second height calculation circuit that receives a signal from the light receiving element.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIGS. 1 and 2 are a perspective view and a block diagram of a signal processing circuit, respectively, showing an embodiment of the present invention.

In this embodiment, a measuring table 1 having a uniaxial stage is used.
A scanning optical system that scans the measurement target 6 placed in the scanning optical system, and a light receiving optical system that receives reflected light of the laser light scanned by the scanning optical system from the measurement target.

This scanning optical system comprises a laser 2 and a laser 2
Beam expander 3 for expanding the beam diameter of the beam to a required beam diameter
A first galvanometer mirror 4 for scanning the laser beam passing through the beam expander 3 in a direction parallel to the measurement table 1 in a direction parallel to the measurement table 1, and a first galvanometer mirror 4
Fθ which converges the laser beam scanned at the end to a required beam diameter on the measuring surface of the measuring table 1 and keeps the scanning speed constant.
A lens 5 and a second galvanometer mirror 6 that intermittently rotates the optical path of the laser beam passing through the fθ lens 5 in the forward and reverse directions and periodically switches in two directions in synchronization with scanning by the galvanometer mirror 4. A first reflecting mirror 7 for reflecting the laser beam reflected at one end point of the rotation of the galvanometer mirror 6 from directly above the measuring table 1 to directly below the lead so that the scanning trajectory is orthogonal to the feeding direction of the measuring table 1; The laser beam reflected at the other end point of the rotation of the second galvanometer mirror 6 is reflected from obliquely above the measuring table 1 so that the scanning trajectory coincides with the scanning trajectory of the first reflecting mirror 7, and the second. And a second reflection mirror 8 having an optical path length from the galvanometer mirror 6 to the measurement surface of the measurement table 1 equal to the same optical path length at the first reflection mirror 7.

The light receiving optical system includes a condenser lens 11 for condensing laser light reflected on the measuring table 1 in a direction of a reflection angle equal to the laser incident angle by the second reflection mirror 8, and an optical axis of the condenser lens 11. It has a cylindrical lens 12 that is located above and condenses the laser light that has passed through the condenser lens 11 in the scanning direction, and a light receiving element 13 that is placed at the focal position of the condenser lens 11 and the cylindrical lens 12 and that receives the laser light.

The signal processing circuit shown in FIG. 2 scans with the stage control circuit 14 for stepping the measuring table 1 every two scans in synchronization with the scan of the first galvanometer mirror 4 and the first reflection mirror 7. A first height calculating circuit 16 for obtaining the height of the measuring object 9 from the light receiving position of the light receiving element 13 at the time, and the measuring object 9 based on the light receiving position of the light receiving element 13 when scanning with the second reflecting mirror 8. A second height calculating circuit 17 for determining the height of the first and second switches, and a switching circuit 15 for switching between the first height calculating circuit 16 and the second height calculating circuit 17 in synchronization with the first galvanomirror 4; The light receiving element 13 at the same position when scanning with the first reflection mirror 7 and the second reflection mirror 8
And a height judging circuit 18 for comparing the light receiving amounts of the above and selecting the height calculation result obtained from the larger light receiving amount.

By controlling the signal processing circuit, the measuring table 1
The scanning of the galvanomirror 4 with the laser beam is performed twice at each position of the laser beam. During one of the two scans, the laser beam is moved from the galvanomirror 6 to the measuring table 1 via the reflecting mirror 7 to be true. The light is incident from above, and the output is switched so as to transmit the output of the light receiving element 13 to the arithmetic circuit 16. During the other one scan, the laser beam is obliquely moved from the galvanometer mirror 6 to the measurement table 1 via the reflection mirror 8. The incident light and the output of the light receiving element 13 are transmitted to the arithmetic circuit 17. Also, the judgment circuit 1
Reference numeral 8 denotes a calculation result of the arithmetic circuit 16 when the amount of light received by the light receiving element 13 in one scan is greater than the amount of light received by the light receiving element 13 in another scan, and an arithmetic circuit 17 when the amount of light is opposite. Is selected as the height of the object 9 to be measured.

FIG. 3 is a plan view for explaining the principle of measuring the height of the normal incidence and oblique incidence optical systems.

The incident angle of the laser beam reflected by the reflection mirror 8 and the incident angle of the laser beam received through the condenser lens 11 are assumed to be θ, and the magnification of the image of the measuring object 9 at the light receiving element 13 is assumed to be m. If the height t of the measurement object 9 is

[0025]

Is given by The arithmetic circuit 16 calculates the height of the measuring object 9 according to the above equation (1), and calculates the height of the arithmetic circuit 17.
Calculates the height of the measurement object 9 according to the equation (2).

FIGS. 4A and 4B are plan views for explaining reflection on a slope.

FIG. 4A shows the case of normal incidence, and FIG. 4B shows the case of oblique incidence. The light receiving direction 21 when the measuring surface 20 has an inclination of the angle α and the strongest reflection directions 22 and 2
The deviation angles △ θ1 and △ θ2 from 2 ′ are: vertical incidence: △ θ1 = θ-2α oblique incidence: △ θ2 = 2α. Here, when solving as と し て θ1 = △ θ2, α = θ / 4
Becomes That is, when the inclination of the measurement surface 20 is smaller than θ / 4, △ θ2 ≦ △ θ1, and the oblique incidence optical system can receive more reflected light, while the inclination of the measurement surface 20 is θ
If it is larger than / 4, △ θ2 ≧ △ θ1, and the normal incidence optical system can receive more reflected light. Therefore, the same position of the measuring table 1 is alternately scanned at both the vertical incidence and the oblique incidence, and the height is determined at the side having the larger light receiving amount of the light receiving element 13 so that the height can be increased at a higher S / N ratio for each slope. In addition to being able to measure depth, it can handle a wide range of objects, from those close to a flat mirror surface to those with unevenness or inclination.

FIGS. 5 and 6 are a perspective view and a block diagram of a signal processing circuit of another embodiment of the present invention, respectively.
This embodiment also includes a measuring table 1, a scanning optical system, and a light receiving optical system.

The scanning optical system of the present embodiment includes a first laser 2
A first beam expander 3 for expanding the beam diameter of the first laser 2 to a required beam diameter, a second laser 30 having a different wavelength from the first laser 2, and a beam of the second laser 30 Second beam expander 31 for expanding the diameter to a required beam diameter
A superimposing optical system composed of a mirror 32 and a beam splitter 33 for superimposing the laser beams of the first laser 2 and the second laser 30 on one beam, and A galvanomirror 4 that scans in the plane in a direction perpendicular to the feed direction of the measuring table 1, and finally the laser beam scanned by the galvanomirror 4
Lens 5 that collects light to a required beam diameter on the measurement surface and keeps the scanning speed constant;
The laser beam of the second laser 30 is transmitted through the laser beam of the second laser 30 and the laser beam of the second laser 30, and the scanning trajectory of the laser beam of the first laser 2 is moved obliquely from above the measuring table 1 in the direction of the measurement table 1 A first filter 34 that reflects so as to be orthogonal to
A reflection mirror 3 that reflects the laser light of the second laser 30 that has passed through the first filter 34 from directly above the measuring table 1 to vertically downward so that the scanning trajectory matches the trajectory of the first laser 2.
And 5.

The light receiving optical system collects the laser light reflected in the direction of the reflection angle equal to the incident angle of the laser light of the laser 2 reflected by the first filter 34 in the reflected light of the object 9 to be measured. An optical lens 11, a cylindrical lens 12 that is on the optical axis of the condenser lens 11 and condenses the laser light passing through the condenser lens 11 in the scanning direction, and a first laser 2 and a second laser 2 that pass through the cylindrical lens 12. Laser 30
A second filter 3 that transmits the laser light of the second laser 30 and reflects the laser light of the first laser 2
6 and a first for receiving the laser beams of the first and second lasers 2 and 30 separated by the second filter 36 at the focal positions of the condenser lens 11 and the cylindrical lens 12, respectively.
And the second light receiving element 13.

The signal processing circuit shown in FIG. 6 calculates a height from the light receiving position of the first light receiving element 37 and a first height calculating circuit 38 which calculates the height from the light receiving position of the second light receiving element 13. A second height calculating circuit 39, a height calculating circuit 38 which compares the light receiving amounts of the first light receiving element 37 and the second light receiving element 13 and receives a signal of the light receiving element 13 or 37 having the larger light receiving amount.
Or a height determination circuit 18 for selecting the height calculation result of 39 as the height of the measurement object 9 which is finally determined. The height calculation circuit 16 calculates the measurement object 9 according to the equation (2).
Is obtained, and the height calculating circuit 17 obtains the height of the measuring object 9 according to the equation (1).

FIGS. 7 and 8 are a perspective view and a block diagram of a signal processing circuit, respectively, of still another embodiment of the present invention.

The scanning optical system of the present embodiment includes a laser 2, a beam expander 3, a galvanometer mirror 4, and an fθ lens 5, and further includes a first polarizing beam splitter 40 for dispersing the laser beam passing through the fθ lens 5. A first reflection of a laser beam (hereinafter referred to as a P-polarized laser beam) that has passed through the polarization beam splitter 40 from directly above the measurement table 1 to vertically below so that the scanning trajectory is orthogonal to the feed direction of the measurement table 1. The reflecting mirror 42 and the laser beam reflected by the polarization beam splitter 40 (hereinafter referred to as S-polarized laser beam) are reflected from obliquely above the measuring table 1 so that the scanning trajectory coincides with the first reflecting mirror 42 and An optical path length from the polarization beam splitter 40 to the measurement surface of the measuring table 1 is constituted by a second reflection mirror 41 equal to the optical path length of the first reflection mirror.

The light receiving optical system includes a condenser lens 1 for condensing laser light reflected in the direction of the reflection angle equal to the laser incident angle of the S-polarized laser light reflected by the second reflection mirror 41.
1, a cylindrical lens 10, a second polarizing beam splitter 11 for splitting a laser beam passing through the cylindrical lens 10, and a second polarizing beam splitter 1.
The first light-receiving element 13 and the second light-receiving element 37 receive the P-polarized laser light and the S-polarized laser light separated at 1 at the focal positions of the condenser lens 9 and the cylindrical lens 10, respectively. .

The signal processing circuit shown in FIG.
The first height calculating circuit 16 for obtaining the height from the light receiving position of No. 3
And a second height calculating circuit 17 for obtaining a height from the light receiving position of the second light receiving element 37, and a height determining circuit 18.

[0037]

As described above, according to the present invention, one scanning optical system alternately switches between normal incidence and oblique incidence scanning at high speed or simultaneously, thereby obtaining the amount of reflected light in both scanning at the same scanning position. By measuring the height with the one with the larger amount of reflected light, it is possible to measure the three-dimensional shape with high S / N ratio with high accuracy and high speed over a wide range from objects with a mirror-like surface to those with a slope. Has an effect.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a block diagram of the signal processing circuit of the embodiment shown in FIG.

FIG. 3 is a plan view for explaining the principle of height measurement of the embodiment shown in FIG. 1;

FIG. 4 is a plan view for explaining a comparison of the amount of light received by the light receiving element 13 in the case of the embodiment shown in FIG.

FIG. 5 is a perspective view showing another embodiment of the present invention.

6 is a block diagram of the signal processing circuit of the embodiment shown in FIG.

FIG. 7 is a perspective view showing still another embodiment of the present invention.

FIG. 8 is a block diagram of the signal processing circuit of the embodiment shown in FIG. 7;

FIG. 9 is a perspective view showing a conventional three-dimensional shape measuring apparatus.

FIG. 10 is a view for explaining the principle of measuring the height of a measuring object of the three-dimensional shape measuring apparatus shown in FIG.

11 is a diagram illustrating a difference in reflected light when measuring a measurement target having a different surface state with the three-dimensional shape measuring apparatus illustrated in FIG. 9;

[Explanation of symbols]

 1,50 Measurement stand 2,30,51 Laser 3,31,52 Beam expander 4,6,53 Galvano mirror 5,54 fθ lens 7,8,32,35,41,42 Reflection mirror 9,55,55 ' 55, object to be measured 11, 57 condenser lens 12, 58 cylindrical lens 13, 37, 59 light receiving element 14 stage control circuit 15 switching circuit 16, 17, 38, 39 height calculation circuit 18 height determination circuit 19, 60 Laser light 20 Measurement surface 21, 61 Light receiving direction 22, 22 'Strongest reflection direction 33 Beam splitter 34, 36 Filter 40, 43 Polarization beam splitter 62, 62' Reflection intensity distribution

Claims (3)

(57) [Claims] (A) a measuring table on which an object to be measured is placed and stepped in one direction; (B) a laser; and a beam expander for expanding a beam diameter of the laser to a required beam diameter.
A scanner that scans the laser beam that has passed through the beam expander in a direction orthogonal to the feed direction of the measurement table, and finally converts the laser beam scanned by the scanner to a required beam diameter on the measurement surface of the measurement table. Lens that converges light at a constant scanning speed, a galvanomirror that switches the optical path of laser light passing through the fθ lens in two directions in synchronization with scanning by the scanner, and an end point of a switching motion of the galvanomirror A first reflection mirror that reflects the laser beam reflected by the scanning trajectory from directly above the measuring table to a vertically downward direction so that the scanning trajectory is orthogonal to the feed direction of the measuring table, and at the other end point of the switching motion of the galvanomirror. The reflected laser light is reflected from obliquely above the measuring table so that the scanning trajectory coincides with the scanning trajectory by the first reflecting mirror, and measurement of the measuring table from the galvanometer mirror is performed. A scanning optical system including a second reflecting mirror that reflects light so that the optical path length up to the surface becomes equal to the same optical path length in the first reflecting mirror; and (C) the second reflecting mirror. A condenser lens for condensing laser light reflected in a reflection angle direction at an angle equal to the laser incident angle, and a laser beam on the optical axis of the condenser lens and passing through the condenser lens in a scanning direction. (D) scanning in synchronization with scanning of the scanner, and a light receiving optical system including a cylindrical lens for condensing light, a light receiving element placed at a focal position of the cylindrical lens and receiving a laser beam, and A stage control circuit for step-feeding the measuring table each time, and a first height for obtaining a height of the measuring object from a light receiving position of the light receiving element when the laser light is reflected by the first reflecting mirror and scanned. An arithmetic circuit; A second height calculating circuit for obtaining a height of a measuring object from a light receiving position of the light receiving element when the laser beam is reflected by the second reflecting mirror and scanned, and the first and second reflecting mirrors Comparing the amount of light received by the light receiving element at the same position when scanning with the laser light reflected by the first and second reflection mirrors when the light is reflected by the first or second reflection mirror having the larger amount of received light A signal processing circuit including a height determination circuit for selecting a height calculation result of the height calculation circuit. (A) a measuring table for placing an object to be measured;
(B) a first laser, a first beam expander for expanding a beam diameter of the first laser to a required beam diameter, a second laser having a different wavelength from the first laser, 2
A second beam expander for expanding the beam diameter of the laser beam to a required beam diameter, and two laser beams expanded by the first beam expander and the second beam expander are superimposed on one beam. A superimposing optical system to be combined, a scanner that scans the laser light superimposed by the superimposing optical system in a direction orthogonal to a feed direction of the measurement table, and finally measures the laser light scanned by the scanner for the measurement. An fθ lens that converges to a required beam diameter on the measurement surface of the table and keeps the scanning speed constant; and any one of the laser light of the first laser and the laser light of the second laser that has passed through the fθ lens A first filter that transmits one of the laser beams and reflects the other laser beam from obliquely above the measurement table so that a scanning trajectory is orthogonal to a feed direction of the measurement table; and the first filter has passed through the first filter. on the other hand A scanning optical system comprising: a reflecting mirror that reflects the laser beam from directly above the measurement table to vertically downward so that the scanning trajectory coincides with the trajectory of the first laser light; A condenser lens for condensing laser light reflected in a reflection angle direction having an angle equal to the incident angle of the other laser light reflected by the filter, and the condensing lens on the optical axis of the condenser lens. A cylindrical lens that condenses the laser light that has passed through the optical lens in the scanning direction, a second filter that disperses the one and the other laser light that has passed through the cylindrical lens, and the second light that is separated by the second filter. A light receiving optical system including first and second light receiving elements for receiving one and the other laser light at the focal positions of the condenser lens and the cylindrical lens, respectively; A first height calculation circuit for obtaining a height from the light receiving position of the child, a second height calculation circuit for obtaining a height from the light receiving position of the second light receiving element, the first light receiving element and the second And a height determination circuit that selects the height calculation result of the first or second height calculation circuit that receives the signal of the light receiving element having the larger light receiving amount by comparing the light receiving amounts of the two light receiving elements. A three-dimensional shape measuring device, comprising: a signal processing circuit. 3. A measuring table for placing an object to be measured,
(B) a laser, a beam expander for expanding the beam diameter of the laser to a required beam diameter, and a scanner for scanning the laser light expanded by the beam expander in a direction orthogonal to the feed direction of the measuring table. An fθ lens that finally focuses the laser beam scanned by the scanner to a required beam diameter on the measurement surface of the measurement table and keeps the scanning speed constant;
A first polarization beam splitter that splits the laser beam that has passed through the fθ lens, and a scanning trajectory of the P-polarized laser beam that has passed through the polarization beam splitter moving vertically from directly above the measurement table to below the measurement table. A first reflection mirror that reflects the light perpendicular to the direction, and a scanning locus of the S-polarized laser light reflected by the polarization beam splitter obliquely from above the measurement table and coincides with the scanning locus of the first reflecting mirror. A second reflection mirror that reflects light so that the optical path length from the polarizing beam splitter to the measurement surface of the measuring table is equal to the optical path length of the P-polarized laser light by the first reflection mirror. And (C) reflection in a reflection angle direction having an angle equal to the incident angle of the S-polarized laser light reflected by the second reflection mirror. A condensing lens for condensing laser light, a cylindrical lens on the optical axis of the condensing lens and condensing laser light passing through the condensing lens in a scanning direction, and a laser light passing through the cylindrical lens A second polarizing beam splitter for splitting the laser beam; and a second polarizing beam splitter for receiving the P-polarized laser beam and the S-polarized laser beam split by the second polarizing beam splitter at focal positions of the condenser lens and the cylindrical lens, respectively. A light receiving optical system composed of first and second light receiving elements; (D) a first height calculating circuit for obtaining a height from a light receiving position of the first light receiving element; A second height calculating circuit for calculating a height from a light receiving position; and a first height receiving circuit for comparing a light receiving amount of the second light receiving element of the first light receiving element and receiving a signal of a light receiving element having a larger light receiving amount. Or A signal processing circuit comprising a height determination circuit for selecting a height calculation result of the second height calculation circuit.