JP4060494B2 - Three-dimensional surface shape measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a three-dimensional surface shape measuring apparatus for measuring a three-dimensional shape of an object surface, and more particularly to a three-dimensional surface shape measuring apparatus using a confocal method.
[0002]
[Prior art]
Various methods have been proposed as a method for accurately measuring a fine three-dimensional shape (unevenness) of the object surface, for example, on the order of μm.
[0003]
Among these methods, a three-dimensional surface shape measuring apparatus that employs a confocal method and uses a microlens array and a pinhole array has been put into practical use. This three-dimensional surface shape measuring apparatus is configured as shown in FIG.
[0004]
Irradiation light 2 output from a light source 1 such as a halogen lamp is converted into light whose traveling directions are parallel to each other by a collimator lens 3 and is incident on a polarization beam splitter 4 disposed in a 45 ° direction with respect to the optical axis. To do. The polarization beam splitter 4 reflects a light component whose polarization direction is the reference direction (0 ° direction) of the incident light, and the polarization direction of the incident light is 90 ° different from the reference direction (0 ° direction). Transmits light components.
[0005]
Of the irradiated light 2 incident on the polarization beam splitter 4, the directly polarized irradiated light 2 having a light component in a direction different by 90 ° from the reference direction (0 ° direction) is incident on the microlens array 5.
[0006]
As shown in FIG. 4A, the microlens array 5 includes a plurality of unit lenses 5a arranged in a matrix. A pinhole array 6 is installed adjacent to the microlens array 5. As shown in FIG. 4B, the pinhole array 6 is composed of a plurality of through holes 6a arranged in a matrix. And the installation position of each unit lens 5a of the microlens array 5 and the drilling position of each through-hole 6a of the pinhole array 6 have a one-to-one correspondence. Then, as shown in FIG. 3, the microlens array 5 and the pinhole array 6 are positioned so that the focal position of each unit lens 5a of the microlens array 5 is located in each through hole 6a of the pinhole array 6. ing.
[0007]
Each illumination light 2 output from each unit lens 5 a of the microlens array 5 is focused at the position of each through hole 6 a of the pinhole array 6 and then incident on the distance adjusting lens 7. The distance adjusting lens 7 converts the incident illumination light 2 from each through-hole 6a into the illumination light 2 whose traveling directions are parallel to each other and enters the objective lens 9 through the quarter-wave plate 8. As is well known, the quarter (λ / 4) wave plate 8 converts incident linearly polarized light into circularly polarized light.
The distance adjusting lens 7 and the objective lens 9 constitute a confocal lens.
[0008]
The objective lens 9 irradiates each position of the measurement target surface 10 with each illumination light 2 from each through-hole 6a incident through the lens 7 for distance adjustment. Each illumination light 2 is reflected at each irradiation position on the surface 10 to be measured, and enters the objective lens 9 as each reflected light 12 from each position. Each reflected light 12 incident on the objective lens 9 passes through the same path as each irradiation light 2, and each unit lens 5 a of the microlens array 5 via the distance adjusting lens 7 and each through hole 6 a of the pinhole array 6. Incident from the opposite direction. Each reflected light 12 is converted into light whose traveling directions are parallel to each other by each unit lens 5a, and is incident on the polarization beam splitter 4 at an angle of 45 ° from the reverse direction.
[0009]
The reflected light 12 incident on the polarization beam splitter 4 becomes circularly polarized light in the reverse direction and passes through the ¼ (λ / 4) wave plate 8 again including the irradiation light 2. The polarization direction of the light 12 is linearly polarized light in a reference direction (0 ° direction) rotated by 90 °. As a result, each reflected light 12 is reflected by the polarization beam splitter 4 and enters the condenser lens 11.
[0010]
The condenser lens 11 causes each incident reflected light 12 to enter the collimator lens 14 through the slit 13. The collimator lens 14 makes each incident reflected light 12 incident on each element on the two-dimensional CCD 16 of the CCD camera 15.
[0011]
Since each element on the two-dimensional CCD 16 of the CCD camera 15 corresponds to each position of the measurement target surface 10, the received light intensity at each element on the two-dimensional CCD 16 of the CCD camera 15 is the same as that of the measurement target surface 10. It becomes the light intensity of the reflected light 12 from each position.
[0012]
Next, the principle of measuring the distance to the measurement target surface 10 in the confocal method will be described. Each illumination light 2 output from each through-hole 6a of the pinhole array 6 is irradiated onto the measurement target surface 10 through a confocal lens including a distance adjusting lens 7 and an objective lens 9, and the reflected light 12 thereof is reflected. Light is received by each element on the two-dimensional CCD 16 through each through hole 6 a of the same pinhole array 6.
[0013]
Here, as shown in FIG. 5, when the distance between the optical system and the measurement target surface 10 is changed, the lens system in which the position of the measurement target surface 10 in the optical axis direction is composed of the unit lens 5a and the confocal lens. The reflected light 12 forms an image at the position of the same through-hole 6a of the pinhole array 6 and the light intensity detected by the corresponding element on the CCD 16 shows the maximum value.
[0014]
Therefore, if the measurement target surface 10 or the optical system is moved in the optical axis direction and the movement position at which the detected light intensity of each element shows the maximum value is specified, the corresponding movement position becomes the optical axis direction position of the measurement target surface 10. Become.
[0015]
Thus, if each moving position where the detected light intensity at each element shows the maximum value is obtained, the three-dimensional surface shape of the entire measurement target surface 10 can be obtained.
[0016]
[Problems to be solved by the invention]
However, the three-dimensional surface shape measuring apparatus shown in FIG. 3 still has the following problems to be solved.
[0017]
That is, as described above, in order to obtain each moving position at which the detected light intensity at each element has the maximum value, it is necessary to move the measurement target surface 10 or the optical system in the optical axis direction. Alternatively, since it is necessary to construct a mechanism for moving the entire optical system including the microlens array 5, the pinhole array 6, and the confocal lens in the optical axis direction with a high system on the order of μm, there is a problem that the entire apparatus becomes complicated. .
[0018]
In particular, since the microlens array 5 and the pinhole array 6 are composed of a large number of unit lenses and a large number of through holes arranged in a matrix, it is not only necessary to move with high accuracy in the optical axis direction, Since the position in the direction orthogonal to the optical axis needs to be moved in the optical axis direction while maintaining high accuracy, a higher moving mechanism is required.
[0019]
The present invention has been made in view of such circumstances, and by providing a simple optical mechanism that varies the distance from the microlens array to the confocal lens, the number of optical members to be moved can be reduced as much as possible. It is an object of the present invention to provide a three-dimensional surface shape measuring apparatus capable of simplifying the measurement and greatly improving the measurement accuracy with a simple configuration.
[0020]
[Means for Solving the Problems]
In order to solve the above problems, the three-dimensional surface shape measuring apparatus of the present invention includes a light source that outputs linearly polarized irradiation light and a first optical axis that is an optical axis of irradiation light output from the light source. A microlens array comprising a plurality of unit lenses arranged in a matrix and arranged in a matrix, and a first pinhole array in which a through hole is formed at the focal position of each unit lens of the microlens array; The polarization beam splitter inserted at an angle of 45 ° with respect to the first optical axis, and the second optical axis orthogonal to the first optical axis, and the irradiation light from the light source reflected by the polarization beam splitter. A plane mirror that turns back to the beam splitter, a first quarter-wave plate interposed between the plane mirror and the polarization beam splitter, and a plane that is provided on the second optical axis and passes through the beam splitter. The irradiation light reflected by the mirror is applied to the surface to be measured, and a confocal lens that causes the reflected light from the surface to be measured to enter the polarizing beam splitter, and is inserted between the measuring surface and the polarizing beam splitter. The second quarter-wave plate, the second pinhole array provided on the first optical axis and formed with a plurality of through holes arranged in a matrix, the first optical axis, A light receiving device comprising a plurality of light receiving elements arranged in a matrix for receiving each reflected light transmitted through each unit through-hole of the pinhole array of 2, a mirror moving unit for moving the plane mirror in the second optical axis direction, A data processing unit that calculates a three-dimensional shape on the measurement target surface from each mirror position from which the maximum light intensity of each light receiving element of the light receiver can be obtained when the position of the plane mirror is changed by the mirror moving unit. With things is there.
[0021]
In the three-dimensional surface shape measuring apparatus configured as described above, the irradiation light output from the light source is incident on the microlens array and the first pinhole array. Each irradiation light focused at each through hole of the pinhole array is reflected by the polarization beam splitter, folded back by a plane mirror provided so as to be movable along the second optical axis, and again incident on the polarization beam splitter. Is done. Each irradiation light passes through the polarization beam splitter and is irradiated onto the surface to be measured through the confocal lens system.
[0022]
Each reflected light from the measurement target surface enters the polarization beam splitter through the same path as the irradiation light. Each reflected light is reflected by the polarization beam splitter, is incident on each through hole of the second pinhole array, and is incident on each light receiving element of the light receiver located behind each through hole.
[0023]
In such a configuration, by changing the position of the plane mirror in the second optical axis direction, the distance from the microlens array to the confocal lens, that is, the unit lens of the microlens array and the confocal lens are configured. The focal length of the lens system changes. Therefore, the same effect as moving the entire optical system in the conventional apparatus in the optical axis direction can be obtained.
[0024]
Therefore, the position in the second optical axis direction at the irradiation position of each irradiation light on the measurement target surface from each mirror position where the maximum light intensity is obtained by each light receiving element of the light receiver when the plane mirror is moved, that is, measurement A three-dimensional shape of the target surface is obtained.
[0025]
In this case, since only the plane mirror moves, the moving mechanism is greatly simplified as compared with the conventional apparatus that moves the entire optical system.
[0026]
In another invention, the three-dimensional surface shape measuring apparatus of the invention described above is further interposed between the second pinhole array and the light receiver, and each of the second pinhole array And a second microlens array including a plurality of unit lenses for guiding each reflected light transmitted through the through hole to each light receiving element of the light receiver.
[0027]
In the three-dimensional surface shape measuring apparatus configured in this way, by using the second microlens array, the distance between the second pinhole array and the light receiver can be arbitrarily set, and the light receiver Can be designed to any size.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a three-dimensional surface shape measuring apparatus according to an embodiment. FIG. 2 is a diagram showing the polarization directions of the irradiation light 22 and the reflection light 36 that are input to and output from the polarization beam splitter 27 incorporated in the three-dimensional surface shape measuring apparatus.
[0029]
For example, the irradiation light 22 whose polarization direction is set to the reference direction (0 °) output from the light source 21 made of a laser light source is converted into light whose traveling directions are parallel to each other by the collimator lens 24, and the light of the irradiation light 22 The light is incident on a first microlens array 25 disposed in a plane orthogonal to the first optical axis 23 that is an axis.
[0030]
This first microlens array 25 is composed of a plurality of unit lenses 25a arranged in a matrix like the microlens array 5 shown in FIG. 4A. In addition, a first pinhole array 26 is installed adjacent to the first microlens array 25. Similar to the pinhole array 6 shown in FIG. 4B, the first pinhole array 26 includes a plurality of through holes 26a arranged in a matrix. And the installation position of each unit lens 25a of the 1st micro lens array 25 and the drilling position of each through-hole 26a of the 1st pinhole array 26 respond | correspond 1: 1. The first microlens array 25 and the first pinhole array are arranged so that the focal position of each unit lens 25a of the first microlens array 25 is positioned in each through hole 26a of the first pinhole array 26. 26 is positioned.
[0031]
Each illumination light 22 output from each unit lens 25 a of the first microlens array 25 is focused at each through hole 26 a position of the first pinhole array 26, and then with respect to the first optical axis 23. The light is incident on the polarization beam splitter 27 inserted with an inclination of 45 °. The polarizing beam splitter 27 has the same configuration as the polarizing beam splitter 4 of the conventional apparatus shown in FIG.
[0032]
As shown in FIG. 2, the irradiation light 22 whose polarization direction is the reference direction (0 °) is reflected by the polarization beam splitter 27 and travels in the direction of the second optical axis 28 orthogonal to the first optical axis 23. Reflected. Irradiation light 22 reflected in the direction of the second optical axis 28 is disposed in a direction orthogonal to the second optical axis 28 via a first quarter (λ / 4) wave plate 29. It is turned back by the flat mirror 30.
[0033]
The plane mirror 30 is fixed to a moving mechanism 31a provided so as to be movable in the direction of the second optical axis 28. The moving mechanism 31a is controlled to move in the direction of the optical axis 28 by the drive unit 31b. Therefore, the moving mechanism 31a and the drive unit 31b constitute the mirror moving unit 31. A piezoelectric element is used in order to ensure the movement accuracy of the order of μm in the direction of the second optical axis 28.
[0034]
The irradiation light 22 turned back by the plane mirror 30 is incident on the polarization beam splitter 27 again via the first quarter (λ / 4) wave plate 29 again. In this case, as shown in FIG. 2, since the polarization direction of the irradiation light 22 is rotated by 90 °, the irradiation light 22 passes through the polarization beam splitter 27 as it is and is arranged on the second optical axis 28. The light enters the lens 32 for adjusting the distance. The distance adjusting lens 32 converts the incident illumination light 22 into the illumination light 2 whose traveling directions are parallel to each other and enters the objective lens 33. The distance adjusting lens 32 and the objective lens 33 constitute a confocal lens.
[0035]
The objective lens 9 irradiates each position of the measurement target surface 35 with each incident illumination light 22 through a second quarter (λ / 4) wavelength plate 34.
[0036]
Therefore, the mirror moving unit 31 described above changes the focal length (focal position) of the lens system configured by the unit lenses 25a of the first microlens array 25 and the confocal lens.
[0037]
Each illumination light 22 is reflected at each irradiation position on the surface 35 to be measured, and enters the objective lens 33 through a second quarter (λ / 4) wavelength plate 34 as each reflected light 36 from each position. Each reflected light 36 incident on the objective lens 33 passes through the same path as each irradiation light 22 and enters the polarization beam splitter 27 again via the distance adjustment lens 32.
[0038]
In this case, each reflected light 36 passes through the second ¼ (λ / 4) wave plate 34 twice including the irradiation light 22, so that the polarization of each reflected light 36 is polarized as shown in FIG. 2. The direction is further rotated 90 ° to the original reference direction (0 °).
[0039]
Accordingly, each reflected light 36 incident on the polarization beam splitter 27 is reflected by the polarization beam splitter 27 in the direction of the first optical axis 23, and is provided in a plane orthogonal to the first optical axis 23. The light enters the unit lenses 38 a of the second microlens array 38 through the through holes 37 a of the second pinhole array 37 having the same configuration as the one pinhole array 26.
[0040]
Each reflected light 36 output from each unit lens 38 a of the second microlens array 38 is incident on a distance adjusting lens 39. The distance adjusting lens 39 converts the incident reflected light 36 into reflected light 36 whose traveling directions are parallel to each other and enters the condenser lens 40.
[0041]
The condenser lens 40 causes each incident reflected light 36 to be incident on each light receiving element 41 a of the light receiver 41 provided in a plane orthogonal to the first optical axis 23.
[0042]
Since each light receiving element 41 a arranged in a matrix in a plane orthogonal to the first optical axis 23 of the light receiver 41 corresponds to each position of the measurement target surface 35, each light receiving element of the light receiver 41. Each received light intensity at 41 a becomes the light intensity of the reflected light 36 from each position of the measurement target surface 35. Each light receiving intensity of each light receiving element 41a of the light receiving device 41 is converted into a digital value by the input IF 42 and input to the data processing unit 43 including a micro computer.
[0043]
The data processing unit 43 including a micro computer drives the mirror moving unit 31 including the moving mechanism 31a and the driving unit 31b, and moves the plane mirror 30 in the direction of the second optical axis 28 in units of μm while receiving light. Each light intensity of each light receiving element 41a of the detector 41 is measured.
[0044]
Then, from the relationship between each moving position d of the plane mirror 30 in each light receiving element 41a and each light intensity I at the corresponding moving position, a moving position dm where the light intensity becomes maximum is obtained, and the moving position where this light intensity becomes maximum. dm becomes the second optical axis direction position D in the two-dimensional position of the measurement target surface 35 corresponding to the corresponding light receiving element 41a. That is, the mirror moving unit 31 is controlled to change the focal position of a lens system including the unit lenses 25a of the first microlens array 25 and the confocal lens. This provides the same effect as moving the entire optical system in the conventional apparatus shown in FIG. 3 in the optical axis direction.
[0045]
Therefore, if the optical axis direction position D at each position of the measurement target surface 35 corresponding to all the light receiving elements 41a of the light receiver 41 is obtained by the above-described method and arranged two-dimensionally, it is the same as the conventional device shown in FIG. The three-dimensional surface shape of the other measurement target surface 35 is obtained.
[0046]
In the three-dimensional surface shape measuring apparatus configured as described above, since the optical member to be moved is only the plane mirror 30, the moving mechanism is greatly simplified as compared with the conventional apparatus that moves the entire optical system. Can be
[0047]
Furthermore, since most of the optical components including the microlens arrays 25 and 38 and the pinhole arrays 26 and 37 can be fixed on one base, the conventional apparatus in which the entire optical system can be moved is used. The measurement accuracy can be greatly improved by comparison.
[0048]
【The invention's effect】
As described above, in the three-dimensional surface shape measuring apparatus of the present invention, by providing a simple optical mechanism that varies the distance from the microlens array to the confocal lens system, it is possible to confocal with the unit lens of the microlens array. The focal position of a lens system composed of lenses is variable. Therefore, the optical system to be moved can be only a plane mirror, the moving mechanism can be greatly simplified, and the measurement accuracy can be improved with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a three-dimensional surface shape measuring apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating irradiation light input to and output from a polarization beam splitter incorporated in the three-dimensional surface shape measuring apparatus. FIG. 3 is a schematic configuration diagram of the three-dimensional surface shape measuring apparatus in a state. FIG. 4 is a diagram showing a microlens array and a pinhole array incorporated in the three-dimensional surface shape measuring apparatus. FIG. 5 is a diagram showing the relationship between the position of the measurement target surface in the optical axis direction and the light intensity of the element measured by the three-dimensional surface shape measuring apparatus.
DESCRIPTION OF SYMBOLS 21 ... Light source 22 ... Irradiation light 23 ... 1st optical axis 24 ... Collimator lens 25 ... 1st micro lens array 26 ... 1st pinhole array 27 ... Polarizing beam splitter 28 ... 2nd optical axis 29 ... 1st 1/4 wavelength plate 30 ... plane mirror 31 ... mirror moving parts 32 and 39 ... distance adjusting lens 33 ... objective lens 34 ... second 1/4 wavelength plate 35 ... measurement object surface 36 ... reflected light 37 ... first 2 pinhole array 38 ... second micro lens array 40 ... condenser lens 41 ... light receiver 42 ... input IF
43 ... Data processing section

Claims (2)

A light source (21) for outputting linearly polarized irradiation light;
A microlens array (25) comprising a plurality of unit lenses arranged in a matrix and arranged in a plane orthogonal to the first optical axis that is the optical axis of the irradiation light output from the light source;
A first pinhole array (26) having a through-hole formed at the focal position of each unit lens of the microlens array;
A polarizing beam splitter (27) inserted at an angle of 45 ° with respect to the first optical axis;
A plane mirror (30) provided on a second optical axis orthogonal to the first optical axis and configured to fold back irradiation light from the light source reflected by the polarizing beam splitter to the beam splitter;
A first quarter wave plate (29) interposed between the plane mirror and the polarizing beam splitter;
Irradiation light provided on the second optical axis and transmitted through the beam splitter and turned back by the plane mirror is irradiated onto the measurement target surface (35), and reflected light from the measurement target surface is irradiated with the polarization beam splitter. A confocal lens (32, 33) to be incident on
A second quarter-wave plate (34) interposed between the measurement object surface and the polarization beam splitter;
A second pinhole array (37) provided on the first optical axis and having a plurality of through holes arranged in a matrix;
A light receiver (41) provided on the first optical axis and comprising a plurality of light receiving elements arranged in a matrix for receiving each reflected light transmitted through each unit through-hole of the second pinhole array;
A mirror moving part (31) for moving the plane mirror in the second optical axis direction;
A data processing unit (43) that calculates a three-dimensional shape on the measurement target surface from each mirror position at which the maximum light intensity of each light receiving element of the light receiver is obtained when the position of the plane mirror is changed by the mirror moving unit. 3D surface shape measuring device. A plurality of light sources interposed between the second pinhole array and the light receiver, and for guiding each reflected light transmitted through each through hole of the second pinhole array to each light receiving element of the light receiver. The three-dimensional surface shape measuring apparatus according to claim 1, further comprising a second microlens array (38) comprising unit lenses.

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