JP2002048522A - Scanning type shape analyzer for analyzing space of wide inspection face - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably shorten a measuring time. SOLUTION: This scanning type shape analyzer calculates the next obtaining position P' using a face shape calculated based on a measured image data obtained n the present obtaining position P and the present obtaining attitude, controls to move to the next obtaining position where an intersection position Ro of an optical axis Oa of a beam and a reference face 1e in a measuring head 1 is calculated, and calculates the next obtaining attitude in the next obtaining position P' using the face shape obtained in the present obtaining position P and the present obtaining attitude to conduct controlling to make a reference axis Ra in the measuring head 1 consistent with the calculated obtaining attitude.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a scanning-type wide-area inspection surface shape analyzing apparatus which scans an inspection surface and calculates the surface shape of the inspection surface by measuring means having a built-in interferometer.

[0002]

2. Description of the Related Art As a method for measuring the surface shape of a test surface having a substantially planar shape with high accuracy, an interferometer projects light beams from a light source onto a reference surface and a substantially planar test surface, respectively. There is an apparatus that generates an optical interference fringe image of light reflected from a reference surface and light reflected from a test surface, and measures a surface shape of the test surface using the optical interference fringe image. In the method using this interferometer, high-precision measurement is possible, but if there is a vertical undulation of several μm or more in one observation region on the surface to be measured, the number of interference fringes in the observation region is reduced. Increase, making measurement difficult.

In general, the larger the area of the surface to be inspected, the greater the amount of undulation in the vertical direction of the surface to be inspected. When measuring the surface shape of a wide area to be inspected with large undulation in the vertical direction,
It is necessary to use a scanning device provided with a scanning mechanism for moving the interferometer relative to the observation area on the surface to be measured. However, this scanning device also has a limitation on the amount of undulation in the vertical direction.

In order to measure a surface shape with high accuracy using an interferometer, the posture of the interferometer with respect to the test surface is maintained such that the reference surface of the interferometer and the test surface are parallel or nearly parallel. Is preferred. In other words, since the number of interference fringes included in the acquired interference fringe image represents the acquisition attitude with respect to the surface to be measured, it is desirable that the number of interference fringes be equal to or less than the number corresponding to the required measurement accuracy. It is.

[0005] Therefore, as a device for measuring the surface shape of a wide-area test surface using an interferometer, a scanning mechanism for moving the interferometer relative to the test surface, a reference surface and the test surface being parallel or parallel. It is conceivable to provide an apparatus provided with a mechanism for changing the posture of the interferometer with respect to the surface to be measured so as to be close to the surface. In this apparatus, when measuring the surface shape of the wide-area test surface, a preliminary measurement is performed to obtain a predetermined number or less of interference fringes, and a predetermined measurement is performed for each acquisition region of the measurement image data obtained from the preliminary measurement. A measurement cycle is executed in which a posture control amount for obtaining the number of interference fringes equal to or less than the number is obtained, and the main measurement is performed while controlling the posture of the interferometer using the posture control amount.

[0006]

However, in the above-described apparatus, a preliminary measurement for obtaining a predetermined number or less of interference fringes on the same test surface and a posture control amount obtained from the preliminary measurement are performed. Since it is necessary to perform the main measurement while controlling the attitude of the interferometer using this method, the time required for measuring the surface shape of the test surface is doubled.

An object of the present invention is to provide a scanning-type wide-area surface shape analyzing apparatus capable of greatly shortening the measuring time.

[0008]

According to the first aspect of the present invention,
The light flux from the light source is projected onto the test surface of the test object placed on the reference surface and the optical support surface, and the optical interference fringes between the reflected light from the reference surface and the reflected light from the test surface A measuring unit that incorporates an interferometer for generating an image and acquires an optical interference fringe image generated by the interferometer as measurement image data, and scans an intersection of the optical axis of the light beam in the measuring unit and the reference surface. A scanning unit for moving the measurement unit in parallel with the optical support surface so that the scanning reference position sequentially reaches each acquisition position when the measurement image data is acquired, and a starting point at the scanning reference position. As a reference axis, a direction vector extended along the optical axis is used as a reference axis, and an acquisition posture of the measurement unit when acquiring the image data is changed so that an inclination direction of the reference axis changes with respect to the test surface. Attitude change means and front A surface shape analysis calculating unit that analyzes and calculates a surface shape of an acquisition area of a test surface corresponding to the acquisition position and the acquisition posture based on the measurement image data acquired at the acquisition position and the acquisition posture; the scanning unit and the posture And control means for driving and controlling the variable means, wherein the control means calculates a next acquisition position using the measurement image data acquired at the current acquisition position and the acquisition posture, and calculates the next acquisition position. It is characterized in that an acquisition posture at a position is calculated.

According to a second aspect of the present invention, in the scanning wide-area surface shape analyzing apparatus according to the first aspect, the control means includes an object to be measured obtained from the measurement image data at the current acquisition position and the current orientation. Based on the surface shape of the inspection area acquisition area,
A position corresponding to an end position of the acquisition area of the test surface on a scanning line from the current acquisition position to the scanning direction of the measuring unit is determined, and a linear distance from the current acquisition position to the next acquisition position is determined. The next acquisition position is calculated so as to be within twice the linear distance from the current acquisition position to the position corresponding to the obtained end position of the acquisition area of the test surface.

[0010] The third aspect of the present invention is the first or second aspect.
In the scanning-type wide-area inspection surface shape analyzing apparatus according to the aspect, the control unit may be configured to control the measurement surface of the inspection surface corresponding to the measurement image data acquired at the current acquisition position and the acquisition posture from the calculated next acquisition position. Obtain a perpendicular vector at an intersection point between a line parallel to the reference axis at the current acquisition position and the acquisition posture drawn toward the acquisition area or an extension area thereof and the acquisition area or an extension area thereof. The inclination direction of the reference axis that coincides with or is parallel to the obtained perpendicular vector is set as the acquisition posture at the next acquisition position.

According to a fourth aspect of the present invention, in the scanning wide-area surface shape analyzing apparatus according to the third aspect, the control means performs the measurement when the measuring means is moved to the next acquisition position. When the position at which the means is moved is slightly different from the calculated next acquisition position, the object corresponding to the measurement image data acquired at the current acquisition position and the acquisition posture from the position at which the measurement means is moved is obtained. A perpendicular line at the intersection of the line parallel to the reference axis at the current acquisition position and orientation at the current acquisition position and acquisition orientation drawn toward the acquisition area of the inspection surface or an extension area thereof. A vector is obtained, and a tilt direction of a reference axis which is coincident with or parallel to the obtained perpendicular vector is set as an acquisition posture at the next acquisition position.

[0012] The invention according to claim 5 is the invention according to claim 1 or 2.
In the scanning-type wide-area inspection surface shape analyzing apparatus according to the aspect, the control unit may be configured to control the measurement surface of the inspection surface corresponding to the measurement image data acquired at the current acquisition position and the acquisition posture from the calculated next acquisition position. Obtain the intersection point between the current acquisition position and the line parallel to the reference axis at the acquisition orientation drawn toward the acquisition area and the acquisition area, and calculate the least squares based on the obtained intersection position and the position in the vicinity thereof. An approximate plane is calculated, and the inclination direction of the reference axis that is coincident with or parallel to the normal vector of the calculated least-squares approximate plane is set as the acquisition posture at the next acquisition position.

The invention according to claim 6 is the first or second invention.
In the scanning-type wide-area surface shape analyzing apparatus according to the above aspect, the control unit, after positioning the measurement unit to the next acquisition position, sets the measurement image data based on measurement image data acquired at the next acquisition position. The number of interference fringes represented by the following formula is calculated, and the acquisition posture at which the calculated number of interference fringes is equal to or smaller than a predetermined number is set as the acquisition posture at the next acquisition position.

According to a seventh aspect of the present invention, in the scanning type wide-area surface shape analyzing apparatus according to the first aspect, the surface shape analysis calculating means includes a surface shape corresponding to the measured image data at each of the acquisition positions. Adjacent to each other in the acquisition area of
An intermediate area surface shape calculation function for calculating a surface shape of an area portion where the two acquisition regions overlap each other, wherein the intermediate area surface shape calculation function combines the surface shapes of the two acquisition regions adjacent to each other to form the area. It is characterized in that the surface shape of the portion is calculated.

According to an eighth aspect of the present invention, in the scanning-type wide-area surface shape analyzing apparatus according to the seventh aspect, the region portions whose surface shapes are calculated by the intermediate region surface shape calculation function are two adjacent regions. An area portion existing between a first position corresponding to an acquisition position in one of the acquisition areas and a second position corresponding to an acquisition position in the other acquisition area, and the intermediate area surface The shape calculation function
When calculating the surface shape at the target position between the first position of the one acquisition region and the second position of the other acquisition region, the surface shape is calculated from the first position of the one acquisition region. Using the weighting factor defined by the ratio of the distance to the target position and the distance from the target position to the second position of the other acquisition region, the surface shape of the one acquisition region and the surface shape of the other acquisition region The surface shape at the target position is calculated by combining the surface shape with the surface shape.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 2 is a perspective view schematically showing a configuration of a scanning-type wide-area inspection surface shape analyzer according to the embodiment. FIG. 2 shows a configuration of a measuring head mounted on the scanning-type wide-area inspection surface shape analysis apparatus of FIG. FIG.

As shown in FIG. 1, the scanning-type wide-area surface shape analyzing apparatus is placed on an optical surface plate 6 having an optical support surface formed on the upper surface, and on the optical support surface of the optical surface plate 6. A measuring head 1 for acquiring measurement image data for obtaining a surface shape of a surface 5a to be inspected of the inspection object 5, and an optical head such that the measurement head 1 scans the inspection surface 5a of the inspection object 5 Surface plate 6
A scanning mechanism 2 for sequentially moving to each acquisition position in parallel with the optical support surface of the above, and a posture to be measured for varying the acquisition posture of the measurement head 1 when the measurement head 1 acquires measurement image data at each acquisition position And a variable mechanism 3.

As shown in FIG. 2, the measuring head 1 converts a light beam from a light source 1a into a lens 1b, a beam splitter 1c,
Optical interference between the reflected light from the reference surface 1e and the reflected light from the test surface 5a by projecting onto the reference surface 1e and the test surface 5a (shown in FIG. 1) having a substantially planar shape via the lens 1d. A built-in interferometer for generating a fringe image and data acquisition means 7 for acquiring an optical interference fringe image generated by the interferometer as measurement image data.

As shown in FIG. 1, the scanning mechanism 2 has a supporting portion 4 which can move in the y-direction while being guided by a guide rail 2b provided on an optical surface plate 6. It is configured. The support portion 4 has x which is orthogonal to the y direction.
A guide rail 2a extending in the direction is provided, and a movable table 2c is movably supported on the guide rail 2a. The movable table 2c has a drive source (not shown), and is configured to be able to travel in the x direction while being guided by the guide rail 2a by the drive source. The movement of the support 4 of the scanning mechanism 2 allows the measurement head 1 to scan the surface 5a in the y direction, and the movement of the movable table 2c causes the measurement head 1 to move in the x direction with respect to the surface 5a. Can be scanned. When the measurement head 1 is moved to the corresponding acquisition position by this scanning, as shown in FIG. 2, the intersection point R0 between the optical axis Oa of the measurement head 1 and the reference surface 1e coincides with the corresponding acquisition position. Will be moved to

The movable table 2c has a mechanism 3
Is installed. The object-to-be-tested surface posture varying mechanism 3 varies the acquisition posture of the measurement head 1 by swinging the measurement head 1 around the start point R0 of the reference axis Ra. Here, as shown in FIG. 2, the reference axis Ra is a directional vector extending along the optical axis Oa with the intersection point between the optical axis Oa of the light beam of the light source 1a in the measuring head 1 and the reference plane 1e as a starting point R0. The inclination direction of the reference axis Ra with respect to the optical support surface of the optical surface plate 6 indicates the acquisition posture when the measurement head 1 acquires the measurement image data with respect to the test surface 5a.

The measurement image data acquired by the data acquisition means 7 of the measurement head 1 is input to the image processing controller 8 via the cable 8a. The image processing control device 8
The apparatus includes a CPU, a memory, and a device including an interface, such as a computer. The image processing control unit 8
The input measurement image data is analyzed, and a surface shape analysis calculation process of calculating the surface shape of the acquisition area of the corresponding test surface is performed. Further, the image processing control device 8 performs scanning posture control for controlling the acquisition position and the acquisition posture of the measurement head 1. In this scanning posture control, specifically, the next acquisition position is calculated using the measurement image data obtained at the current acquisition position and the acquisition posture or the calculated surface shape, and the optical axis Oa of the measurement head 1 is determined. An acquisition position control signal for driving and controlling the movable base 2c to move to the next acquisition position at which the intersection point R0 of the reference plane 1e is calculated is calculated,
Using the measured image data obtained at the current acquisition position and the acquired orientation or the computed surface shape, the acquisition orientation at the next acquisition position is calculated, and the reference axis Ra of the measurement head 1 matches the calculated acquisition orientation. Then, an acquired attitude control signal for driving and controlling the test subject attitude variable mechanism 3 is calculated. The obtained position control signal is input to the scanning driver 9, and the obtained attitude control signal is input to the subject surface attitude variable driver 10. A monitor 11 is connected to the image processing control device 8, and the monitor 11 has a set measurement condition,
It is possible to selectively display an optical interference fringe image acquired as measurement image data, a calculated surface shape, and the like.

The scanning driver 9 moves the moving table so as to move to the next acquisition position where the position of the intersection of the optical axis Oa of the light beam and the reference surface 1e in the measuring head 1 is calculated based on the input acquisition position control signal. A driving signal for driving the scanning mechanism 2c is generated, and the driving signal is output to the moving table 2c of the scanning mechanism 2 via the signal cable 9a.

The object-to-be-tested surface attitude variable driver 10 drives the object-to-be-tested surface attitude varying mechanism 3 so that the reference axis Ra of the measuring head 1 matches the calculated obtained attitude based on the input acquired position control signal. To generate a drive signal for
This drive signal is input to the mechanism 3 for changing the posture of the surface to be measured via the signal cable 10a.

Next, the measuring operation in the scanning type wide-area surface shape analyzing apparatus of this embodiment will be described with reference to FIGS. FIG. 3 is a flowchart showing a procedure of scanning attitude control in the scanning type wide-area object shape analyzing apparatus of FIG. 1, and FIG. 4 is a flowchart showing a procedure of surface shape calculating processing in the scanning type wide-area object face analyzing apparatus of FIG. ,
FIG. 5A is a diagram schematically showing the relationship between the acquired position and the acquired attitude of the measuring head and the surface to be inspected in the scanning-type wide-area inspected surface analyzer of FIG. 1, and FIG. 5B is the scanning type of FIG. FIG. 6 is a diagram schematically showing a method of combining and calculating a surface shape of an area where two adjacent acquisition areas of each acquisition area overlap with each other in the wide area surface analysis apparatus, and FIG. 6 is a scanning wide area of FIG. FIGS. 7 and 8 schematically show a method of calculating the next acquisition position of the measurement head in the apparatus for analyzing the shape of a test surface. FIGS. FIG. 5 is a diagram schematically showing a calculation method of an acquisition posture in FIG.
FIG. 9 is a diagram schematically illustrating a method of calculating the surface shape of an area where two adjacent acquisition regions overlap with each other in the scanning-type wide-area surface shape analysis apparatus of FIG.

In this scanning type wide-area inspection surface analyzing apparatus,
As shown in FIG. 5A, three-dimensional coordinates (x, y, z) in which the optical support surface of the optical surface plate 6 is an xy plane and the height direction is the z direction are defined in advance, and The table 2c is moved in parallel with the optical support surface of the optical surface plate 6 with the x direction, that is, the measurement scanning direction ds of the measuring head 1 (the direction indicated by the arrow in the drawing) as the main scanning direction. The sub-scanning direction is the y direction, and the sub-scanning is performed by moving the support unit 4 along the guide rail 2b.

Here, the reference axis Ra of the measuring head 1 is
If the z-coordinate value of the starting point R0 is z0 (= constant value), since the coordinate value z0 of the starting point R0 does not change due to the scanning of the measuring head 1, the acquired position of the measuring head 1 is the coordinate value (x,
y, z0). That is, assuming that the coordinate value of the current acquisition position P is (x, y, z0), the measurement head 1 is positioned such that the coordinate value of the start point R0 of the measurement head 1 matches the coordinate value of the acquisition position P. Will be.
In addition, the inclination of the reference axis Ra of the measurement head 1 indicates the acquisition posture of the measurement head 1, and at the current acquisition position P, the reference axis Ra of the measurement head 1 is inclined in a corresponding direction with respect to the starting point R0. become.

When the measurement image data is acquired by the measuring head 1 at the current acquisition position P and the acquisition posture, the acquisition area S on the surface 5a to be detected corresponding to the current acquisition position P and the acquisition posture is based on the measurement image data. Is calculated. Next, the next acquisition position P 'is calculated based on the surface shape of the acquisition region S, and the measuring head 1 is moved so that the starting point R0 coincides with the next acquisition position P'. Further, regarding the acquisition posture at the next acquisition position P ′, the next acquisition posture of the measuring head 1 is set such that the reference axis Ra is substantially orthogonal to the acquisition region S having the surface shape obtained at the current acquisition position P. Is calculated.

When the next acquisition position P 'and the next acquisition posture are calculated, the measuring head 1 is moved to the calculated next acquisition position P', and the next acquisition posture in which the acquisition posture is calculated is calculated. The measurement image data is acquired by the measurement head 1 held at the next acquisition position and at the next acquisition posture. Then, based on the measurement image data acquired at the next acquisition position P ', the surface shape of the acquisition area S' of the test surface 5a corresponding to the next acquisition position P and the acquisition posture is calculated. In this way, the measurement head 1 is sequentially moved to each acquisition position, and the acquisition posture (reference axis Ra) of the measurement head 1 is changed at each acquisition position, and the measurement head 1 is held at the corresponding acquisition posture at each acquisition position P. The measurement image data is obtained by the measurement head 1.

When the scanning of the test surface 5a is completed, the surface shape of the acquisition region corresponding to each acquisition position is obtained, and the entire surface shape of the test surface 5a is calculated from the surface shape of each acquisition region.
When calculating the overall surface shape of the inspection surface 5a from the surface shape of each acquisition region, for example, as shown in FIG. 5B, two acquisition regions S, S adjacent to each other in each acquisition region. Are calculated by synthesizing the surface shapes of the regions where 'overlaps. Specifically, by combining the surface shapes of the overlapping portions Sm and S'm of the two acquisition regions adjacent to each other, the surface shape of the region where the two acquisition regions S and S 'adjacent to each other overlap is calculated. . Then, the surface shape Si of the region composed of the two acquisition regions S and S ′ adjacent to each other is calculated.

Next, a method of calculating the next acquisition position P 'will be described with reference to FIG. In the present embodiment, as shown in FIG. 6, assume that the current acquisition position of the measurement head 1 is P, and the acquisition area on the test surface 5a at which the measurement image data has been acquired at the current acquisition position P is S. A position R on the acquisition region S corresponding to the current acquisition position P is obtained, and a straight line extending from this position R in the measurement scanning direction ds is obtained.
A position Rm that intersects with the boundary of is obtained. Next, a position Q on the reference surface 1e corresponding to a position Rm on a straight line extending from the acquisition position P in the measurement scanning direction ds is determined, and a linear distance | PQ | from the acquisition position P to the position Q is calculated. You. Then, assuming that the next acquisition position is P ′, a linear distance | PP ′ | and a linear distance | PQ | along the measurement scanning direction ds from the current acquisition position P to the next acquisition position P ′ An arbitrary acquisition position that satisfies the relationship shown in the following equation (1) is obtained as the next acquisition position P ′.

| PP ′ | ≦ 2 | PQ | (1) Next, a method of calculating the next acquired attitude is shown in FIGS. 7 and 8.
This will be described with reference to FIG. In the calculation of the next acquisition posture, as shown in FIG. 7, the current acquisition position of the measurement head 1 is P, and the acquisition area of the surface shape calculated based on the measurement image data acquired at the acquisition position P is shown in FIG. Assuming that S, the next acquisition posture is calculated such that the reference axis Ra of the measurement head 1 is orthogonal to the acquisition area S at the next acquisition position P ′ obtained by the above-described method. Specifically, as shown in FIG. 8, the current acquisition position P from the next acquisition position P ′ and the current acquisition position P toward the acquisition region S corresponding to the measurement image data acquired in the acquisition posture are obtained. A line parallel to a line drawn at the position R on the acquisition area S corresponding to the acquisition position P is lowered, a position R 'where the line and the acquisition area S intersect is obtained, and a perpendicular vector V starting from the position R' is obtained. Is calculated, and the acquisition posture in which the reference axis Ra of the measuring head 1 matches or becomes parallel to the perpendicular vector V 'is calculated as the next acquisition posture. Here, a tangent plane at the position R 'is calculated, and a normal vector at the tangent plane is obtained as a perpendicular vector V'.

Here, as shown in FIG. 8, for example, a straight line representing a measurement scanning path extending on the xz plane along the measurement scanning direction ds from the current acquisition position P to the next acquisition position P 'is shown. If the measurement head 1 is positioned at a position P "on the measurement scanning path ls slightly past the next acquisition position P ', the actual acquisition position becomes the position P". It is preferable to correct the acquisition posture at the next acquisition position obtained from the measurement image data in the acquisition posture. This is because the calculated acquisition posture at the next acquisition position P ′ may not be appropriate for the acquisition posture at the acquisition position P ″. This is performed according to the amount of deviation from P ". As described above, when the measurement head 1 is positioned at the position P "slightly after the next acquisition position P ', the measurement head 1 corresponds to the acquisition position P and the measurement image data obtained at the acquisition posture from this position P". A line parallel to a line drawn from the current acquisition position P to the position R on the acquisition region S corresponding to the acquisition position P is lowered toward the acquisition region S, and a position R at which this line intersects the acquisition region S Next, a tangent plane at this position R "is calculated, and a normal vector at this tangent plane is obtained as a perpendicular vector V". The acquisition posture at the acquisition position P "is corrected so as to match or become parallel to the direction.

Next, two adjacent ones of the acquisition areas
A specific example of a method of calculating the surface shape of the area where the two acquisition areas S and S ′ overlap will be described with reference to FIG. When calculating the surface shape of the region where the two adjacent acquisition regions S and S ′ overlap, as described above, the surface shapes of the two adjacent acquisition regions are calculated using the weighting factors (A (x, y), B (x, y)) to obtain two adjacent acquisition areas S,
The surface shape of the region where S 'overlaps is calculated.

In the present embodiment, as shown in FIG. 9, two adjacent acquisition areas S and S ′ are overlapped with each other as a part of the acquisition area S corresponding to the acquisition position P and the acquisition area S ′. Is obtained between the position R ′ corresponding to the acquisition position P ′ and the position R ′ corresponding to the acquisition position P ′, and the distance from the position R of the acquisition region S to the target position of the region part and the other from the target position Position R 'of the acquisition area S'
The surface shape of an area where two adjacent acquisition areas S and S ′ overlap with each other is calculated according to the ratio to the distance to.
Here, the target position is a position on an area part where the two acquisition areas S and S ′ overlap each other, and is a candidate position when calculating the surface shape of the overlapping area part. The height (z coordinate) in the acquisition area S is represented by a function of A (x, y), and the xy coordinate value of the position R of the acquisition area S is (x1,
y), and the height (z coordinate) in the acquisition area S ′ is B
Expressed as a function of (x, y), x- of the position R ′ of the acquisition area S ′
Assuming that the y coordinate value is (x2, y), the position R of the acquisition area S
The height (z coordinate) of the region (the hatched portion in the drawing) existing between the position and the position R ′ of the acquisition region S ′ is a function H (x, y) expressed by the following equation (2). And the function H
An area portion existing between the position R of the acquisition area S and the position R 'of the acquisition area S' by (x, y) (hatched part in the figure)
Is required.

H (x, y) = [│x2-x││A (x, y) + │x1-x│ ・ B (x, y)] / │x2-x1│ (2) Two acquisition areas S, S adjacent to each other according to the ratio of the distance from the position R of the acquisition area S to the target position of the area part and the distance from this target position to the position R 'of the other acquisition area S'. Is calculated, the discontinuity in the region where the two adjacent acquisition regions S and S 'overlap with each other is eliminated, and there is no discontinuity in the measurement result for the test surface 5a. A smooth surface shape can be obtained.

Next, the procedure of scanning attitude control and surface shape calculation processing by the image processing control unit 8 will be described with reference to FIGS.
This will be described with reference to FIG. Here, the description will be made while omitting the above-described correction of the acquisition posture.

When the measurement operation is started, the image processing control unit 8 calculates the scanning posture control task for the measurement head 1 and the surface shape of the surface 5a to be inspected based on the measurement image data acquired by the measurement head 1. Is performed in parallel with the surface shape calculation processing task.

In the scanning posture control task, as shown in FIG. 3, first, an initialization process is performed in step S11. In this initialization processing, an acquisition position control signal for positioning the measurement head 1 at the initial acquisition position and an acquisition posture control signal for holding the measurement head 1 in the initial acquisition posture are generated. Then, the process proceeds to step S12, in which an acquisition posture generated by a surface shape calculation processing task described later and data necessary for calculating the acquisition posture are acquired. The data acquired here includes data indicating the calculated surface shape. The data acquired from the surface shape calculation processing task includes the initial acquisition position of the measuring head 1 in accordance with the completion of the scanning,
Data for returning to the initial acquisition posture is included.

Next, the process proceeds to step S13, where the next acquisition position is calculated based on the data acquired in step S12, and the position of the intersection between the optical axis Oa of the light beam in the measuring head 1 and the reference surface 1e is calculated. An acquisition position control signal for driving and controlling the movable base 2c to move to the next acquisition position is generated. In the following step S14, the acquisition posture at the next acquisition position is calculated based on the data acquired in the above-described step S12, and the position of the test surface is set so that the reference axis Ra of the measuring head 1 matches the calculated acquisition posture. An acquisition attitude control signal for driving and controlling the variable mechanism 3 is generated.

Then, the process proceeds to a step S 15, wherein the acquisition position control signal is output to the scanning driver 9. Thereby, the scanning driver 9 drives the moving table 2c of the scanning mechanism 2 based on the acquisition position control signal so that the measuring head 1 moves to the next acquisition position. In the following step S16,
The obtained attitude control signal is transmitted to the surface attitude variable driver
Output to As a result, the object-to-be-tested surface posture variable driver 1
0 drives the mechanism for changing the posture of the surface to be measured 3 so that the reference axis Ra of the measuring head 1 matches the calculated acquisition posture based on the acquisition posture control signal.

Then, the process proceeds to step S17. In step S12, it is determined whether or not the data for returning the measuring head 1 to the initial acquisition position and the initial acquisition posture due to the completion of the scanning has been acquired from the surface shape calculation processing task. It is determined whether or not the scanning has been completed in accordance with, and if the scanning has not been completed, the process proceeds to step S12, and data necessary for calculating the next acquisition position and acquisition attitude is acquired. When the scanning is completed, the process ends.

In the surface shape calculation processing task, as shown in FIG. 4, first, initialization processing is performed in step S21.
In this initialization process, clear the memory for holding the measured image data, the calculated surface shape, input the measurement conditions,
Processing such as setting an initial acquisition position and an initial acquisition posture of the measurement head 1 according to the input measurement conditions is performed.

Next, the process proceeds to step S22, in which the measurement image data acquired by the measuring head 1 is input, and in step S23, the acquired measurement image data is analyzed.
The surface shape of the acquisition area of the test surface 5a corresponding to the measurement image data is calculated. The calculated surface shape is defined by three-dimensional coordinate values (x, y, and y) defined in advance on the optical support surface of the optical surface plate 6.
z), and these coordinate values (x, y, z) are stored in the memory. Then, the process proceeds to step S24 to generate data necessary for calculating the next acquisition position and acquisition posture based on the acquired measurement image data or the calculated surface shape, and passes the generated data to the scan control task. Here, when the measurement image data acquired in step S22 is the measurement image data at the final acquisition position, the scanning has been completed, so the data necessary for calculating the next acquisition position and acquisition posture is: This is data for returning the measuring head 1 to the initial acquisition position and the initial acquisition posture.

Next, proceeding to step S25, it is determined whether or not scanning of the surface 5a has been completed, depending on whether or not the measurement image data acquired in step S22 is the measurement image data at the final acquisition position. If it is determined that the scanning of the test surface 5a has not been completed, the above-described step S2
Returning to step 2, the measurement image data is acquired at the next acquisition position, and the processing from step S23 is repeated. On the other hand, when the scanning of the test surface 5a is completed, the process proceeds to step S26.

In step S26, the surface shape of an area where two adjacent acquisition regions overlap each other in each acquisition region having a surface shape obtained from each measurement image data at the acquisition position is calculated. Specifically, the surface shape of the region portion is calculated by combining the surface shapes of two acquisition regions adjacent to each other with the surface shape corresponding to the region portion from each of the acquisition regions. Then, the process proceeds to step S27, where the entire surface shape of the test surface 5a including the surface shape of the region calculated in step S26 is output to the monitor 11, a printer, or the like, and the process ends.

As described above, in the present embodiment, the next acquisition position is calculated using the surface shape calculated from the measurement image data obtained at the current acquisition position and the current orientation, and the luminous flux of the measurement head 1 is calculated. The drive of the movable table 2c is controlled so that the intersection point R0 of the optical axis Oa and the reference plane 1e moves to the next calculated position, and the next position is calculated using the surface shape obtained at the current obtained position and obtained posture. Is calculated, and the drive of the variable mechanism 3 for measuring the posture of the surface to be measured is controlled so that the reference axis Ra of the measuring head 1 coincides with the calculated obtaining posture. It is not necessary to perform a preliminary measurement for obtaining the amount of attitude control, and the time required for measuring the surface shape of the test surface 5a can be greatly reduced.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
The embodiment will be described with reference to FIG.
FIG. 10 is a diagram schematically illustrating a method of calculating the acquisition attitude at the next acquisition position of the measurement head in the scanning-type wide-area surface shape analyzing apparatus according to the second embodiment of the present invention.

In the present embodiment, as shown in FIG.
From the current acquisition position P extending from the next acquisition position P ′ toward the acquisition region S, an acquisition region S corresponding to this acquisition position P
The plane Sp approximated by the least-squares method based on the three-dimensional coordinate values of the position R 'and the neighboring positions around the position R' is obtained by finding the position R 'where the line parallel to the line drawn at the upper position R and the acquisition area S intersect. Is calculated, and a normal vector V ′ with respect to the approximated plane Sp is calculated, and an acquisition posture in which the reference axis Ra of the measurement head 1 matches or becomes parallel to the normal vector V ′ is calculated as the next acquisition posture. This is different from the above-described first embodiment. Note that other configurations are the same as those of the above-described first embodiment, and a description thereof will be omitted.

With this configuration, the normal vector V 'representing the acquisition posture of the measuring head 1 with respect to the surface 5a to be measured is calculated with higher accuracy without being affected by the high frequency unevenness component of the acquisition region S. Consequently, at the next acquisition position P ', the parallelism between the reference surface 1e of the interferometer of the measurement head 1 and the corresponding acquisition region S' of the test surface can be further improved.

(Third Embodiment) Next, a third embodiment of the present invention will be described.
The embodiment will be described with reference to FIGS. 11 (a) and 11 (b). FIG. 11A shows the next acquisition position of the measurement head when the number of interference fringes calculated by the scanning-type wide-area surface shape analyzing apparatus according to the third embodiment of the present invention is equal to or less than a predetermined number. FIG. 11B is a diagram schematically showing a calculation method of the acquired attitude, and FIG. 11B is a diagram showing a case where the number of interference fringes calculated by the scanning-type wide-area surface shape analyzing apparatus according to the third embodiment of the present invention is a predetermined number FIG. 11 is a diagram schematically illustrating a calculation method of an acquisition posture at a next acquisition position of the measurement head when the number of the measurement heads exceeds the limit.

The present embodiment is different from the above-described first embodiment in that the measuring head 1 is moved to the next obtaining position P 'and then the obtaining posture of the measuring head 1 is obtained.
In this embodiment, points different from the above-described first embodiment will be described, and description of the same configuration as the above-described first embodiment will be omitted.

In the present embodiment, as shown in FIG. 11A, the next acquisition position P ′ is held in a state where the measuring head 1 holds the acquisition posture from the current acquisition position P to the acquisition position P.
First, the measurement image data for the acquisition area of the test surface 5a corresponding to the acquisition position P ′ is
The acquired measurement image data is input to the image processing control device 8 via the cable 8a.
The image processing control device 8 controls the interference fringe image IG indicated by the input measurement image data to be displayed on the monitor 11, calculates the number of interference fringes included in the input measurement image data, and calculates this calculation. It is determined whether the number of interference fringes is equal to or less than a predetermined number (for example, three). Here, if the calculated number of interference fringes is equal to or less than a predetermined number, the acquisition posture at the acquisition position P is set as the acquisition posture at the acquisition position P ′. Then, at the acquisition position P ′, the measurement image data is acquired in the same acquisition posture as the acquisition posture at the acquisition position P, and the corresponding acquisition region S ′ is obtained based on the measurement image data.
Is analyzed and calculated.

On the other hand, when the calculated number of interference fringes exceeds a predetermined number, as shown in FIG.
At the acquisition position P ′, measurement image data is acquired while sequentially changing the inclination and the direction of the reference axis Ra of the measurement head 1, and the measurement image acquired each time the inclination and the direction of the reference axis Ra of the measurement head 1 changes The number of interference fringes is calculated based on the data, and it is determined whether or not the calculated number of interference fringes is equal to or less than a predetermined number (for example, three). These series of processes are repeated until the number of interference fringes becomes equal to or less than a predetermined number. When the inclination and direction of the reference axis Ra in which the number of interference fringes is equal to or less than the predetermined number are obtained, the inclination and direction are changed to the reference axis Ra. Is held. That is, the measurement head 1 is held in the acquisition posture in which the number of interference fringes is equal to or less than the predetermined number. Then, the measurement image data in this acquisition posture is acquired, and the corresponding acquisition area S ′ based on the measurement image data is acquired.
Is analyzed and calculated.

[0055]

As described above, according to the present invention,
The light flux from the light source is projected onto the test surface of the test object placed on the reference surface and the optical support surface, and the optical interference fringe image of the reflected light from the reference surface and the reflected light from the test surface is formed. A measuring unit that incorporates an interferometer to be generated and acquires an optical interference fringe image generated by the interferometer as measurement image data, and an intersection between the optical axis of the light beam in the measuring unit and the reference surface is set as a scanning reference position. A scanning means for moving the measuring means in parallel with the optical support surface so that the scanning reference position sequentially reaches each acquisition position when acquiring the measurement image data, and extending along the optical axis with the scanning reference position as a starting point. An orientation variable unit that varies an acquisition orientation when acquiring image data of the measurement unit so that the direction of inclination of the reference axis changes with respect to a surface to be inspected, using a direction vector as a reference axis, and an acquisition position and an acquisition orientation. The measured image data Surface position analysis and calculation means for analyzing and calculating the surface shape of the acquisition area of the test surface corresponding to the acquisition position and the acquisition posture, and control means for driving and controlling the scanning means and the attitude variable means, and the control means The next acquisition position is calculated using the measurement image data acquired at the current acquisition position and the acquisition posture, and the acquisition posture at the calculated next acquisition position is calculated. It is not necessary to perform preliminary measurement for obtaining the attitude control amount, and it is possible to greatly reduce the time required for measuring the surface shape of the surface to be inspected.

The control means scans from the current acquisition position in the scanning direction of the measurement means based on the surface shape of the acquisition area of the test surface obtained from the measurement image data at the current acquisition position and the acquisition attitude. The position corresponding to the end position of the acquisition area of the test surface on the line is determined, and the linear distance from the current acquisition position to the next acquisition position is the end position of the acquisition area of the test surface obtained from the current acquisition position By calculating the next acquisition position so as to be less than twice the linear distance to the position corresponding to, the acquisition region corresponding to the current acquisition position overlaps with the acquisition region corresponding to the next acquisition position The region is reliably present, and it is possible to prevent the occurrence of an unmeasured region on the test surface.

Further, the control means pulls from the calculated next acquisition position to the acquisition area of the test surface corresponding to the measurement image data acquired at the current acquisition position and the acquisition attitude, or an extension area thereof. The perpendicular vector at the intersection of the line parallel to the reference axis at the current acquired position and the acquired orientation and the acquired area or an area on the extension thereof is obtained, and it becomes coincident with or parallel to the obtained perpendicular vector. By setting the inclination direction of the reference axis to the acquisition posture at the next acquisition position, the acquisition posture at which the reference surface of the interferometer of the measuring means and the corresponding acquisition region of the inspection surface become substantially parallel at the next acquisition position Can hold the measuring means.

Further, when the measuring means is moved to the next acquisition position and the position at which the measuring means is moved is slightly different from the calculated next acquisition position, the control means moves the measuring means. The current acquisition position and the reference axis at the acquisition orientation drawn toward the acquisition area of the test surface corresponding to the measurement image data acquired at the current acquisition position and the acquisition attitude from the set position, or an extension area thereof The perpendicular vector at the intersection of the line parallel to and the acquired area or the area on the extension thereof is obtained, and the inclination direction of the reference axis that matches or becomes parallel to the obtained perpendicular vector is obtained at the next acquisition position. By setting the posture, when the measuring unit is moved to a position slightly different from the calculated next acquisition position, the acquiring posture of the measuring unit can be corrected.

Further, the current acquisition position drawn by the control means from the calculated next acquisition position toward the acquisition area of the test surface corresponding to the current acquisition position and the measurement image data acquired in the acquisition posture. And an intersection point between the line parallel to the reference axis in the acquisition posture and the acquisition area is calculated, a least square approximation plane is calculated based on the obtained intersection position and positions in the vicinity thereof, and the calculated least square approximation is calculated. By setting the inclination direction of the reference axis that is coincident with or parallel to the normal vector of the plane as the acquisition posture at the next acquisition position, the surface within the acquisition region is not affected by the high-frequency unevenness component of the acquisition region. Can be calculated with higher accuracy. That is, the parallelism between the reference surface of the interferometer of the measuring means and the corresponding acquisition area of the test surface can be further improved.

Further, the control means calculates the number of interference fringes indicated by the measurement image data based on the measurement image data acquired at the next acquisition position after positioning the measurement means at the next acquisition position. By setting the acquisition posture at which the calculated number of interference fringes is equal to or less than the predetermined number as the acquisition posture at the next acquisition position, the next acquisition posture at the next acquisition position can be made appropriate.

Further, the surface shape analysis calculating means calculates an intermediate surface shape of an area where two adjacent acquisition regions overlap each other among the acquisition regions of the surface shape corresponding to the measured image data at each of the acquisition positions. An area surface shape calculation function is provided, and the intermediate region surface shape calculation function calculates the surface shape of the region portion by synthesizing the surface shapes of the two acquisition regions adjacent to each other. It is possible to obtain a smooth surface shape without discontinuity in the region where the acquisition regions overlap.

Further, the area portion for which the surface shape is calculated by the intermediate region surface shape calculation function includes a first position corresponding to an acquisition position in one of two acquisition regions adjacent to each other and an acquisition position of the other. The area portion existing between the second position corresponding to the acquisition position in the area, and the intermediate area surface shape calculation function performs the first position of one acquisition area and the second position of the other acquisition area. When calculating the surface shape at the target position between the two, the ratio of the distance from the first position to the target position in one acquisition region and the distance from the target position to the second position in the other acquisition region By calculating the surface shape at the target position by synthesizing the surface shape of one acquisition region and the surface shape of the other acquisition region using the weight coefficient defined by Overlap As the surface shape in the Hare area portion,
A smooth surface shape without discontinuities can be obtained, and the surface shape can be easily calculated.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a configuration of a scanning-type wide-area inspection surface shape analyzing apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a measuring head mounted on the scanning-type wide-area inspection surface shape analyzer of FIG. 1;

FIG. 3 is a flowchart showing a procedure of scanning attitude control in the scanning-type wide-area inspection surface shape analyzer of FIG. 1;

FIG. 4 is a flowchart illustrating a procedure of a surface shape calculation process in the scanning-type wide-area inspected surface shape analyzer of FIG. 1;

FIG. 5A is a diagram schematically illustrating a relationship between an acquisition position and an acquisition posture of a measurement head and a test surface in the scanning-type wide-area test surface analysis apparatus in FIG. 1; FIG. 2B is a diagram schematically showing a method of combining and calculating a surface shape of an area where two adjacent acquisition areas of each acquisition area overlap in the acquisition area analysis apparatus of FIG. 1. is there.

6 is a diagram schematically illustrating a method of calculating a next acquisition position of a measurement head in the scanning-type wide-area inspection surface shape analyzing apparatus of FIG. 1;

FIG. 7 is a diagram schematically illustrating a method of calculating an acquisition posture at a next acquisition position of the measurement head in the scanning-type wide-area inspection surface shape analyzing apparatus in FIG. 1;

8 is a diagram schematically illustrating a method of calculating an acquisition attitude at a next acquisition position of a measurement head in the scanning-type wide-area inspection surface shape analyzing apparatus in FIG. 1;

9 is a diagram schematically illustrating a method of calculating a surface shape of an area portion where two adjacent acquisition regions overlap with each other in the scanning-type wide-area inspection surface shape analysis apparatus in FIG. 1;

FIG. 10 is a diagram schematically illustrating a method of calculating an acquisition posture at a next acquisition position of a measurement head in the scanning-type wide-area inspection surface shape analyzing apparatus according to the second embodiment of the present invention.

FIG. 11 (a) shows the next acquisition of a measuring head when the number of interference fringes calculated by the scanning-type wide-area surface shape analyzing apparatus according to the third embodiment of the present invention is equal to or smaller than a predetermined number. It is a figure which shows typically the calculation method of the acquisition attitude | position in a position. (B) Acquisition at the next acquisition position of the measuring head when the calculated number of interference fringes exceeds a predetermined number in the scanning-type wide-area surface shape analyzing apparatus according to the third embodiment of the present invention. It is a figure which shows the calculation method of a posture typically.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Measurement head (measurement means) 2 Scanning mechanism (scanning means) 3 Variable mechanism for posture to be inspected (variable attitude means) 5 Object to be inspected 5a Surface to be inspected 6 Optical surface plate 7 Data acquisition means 8 Image processing control device (surface) (Shape analysis calculation means, control means) 9 scanning driver (scanning means) 10 variable driver for posture to be inspected (posture variable means) 11 monitor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Nobino F-term (reference) 2F065 AA04 AA53 DD06 FF52 FF61 FF65 FF67 HH03 HH13 EJ03 JJ09 LL04 LL46 MM07 NN20 PP03 PP05 PP11 QQ00 QQ17 QQ18 QQ23 QQ24 SS02 SS03 SS13

Claims (8)

[Claims] 1. A light flux from a light source is projected on a reference surface and a test surface of a test object placed on an optical support surface, respectively, and reflected light from the reference surface and reflected light from the test surface. A measuring unit that incorporates an interferometer for generating an optical interference fringe image of the optical interferometer, and acquires an optical interference fringe image generated by the interferometer as measurement image data; and an optical axis of a light beam in the measuring unit and the reference surface. Scanning means for moving the measuring means in parallel with the optical support surface so that the intersection with the scanning reference position, the scanning reference position sequentially reaches each acquisition position when acquiring the measurement image data, A direction vector extending along the optical axis with a scanning reference position as a starting point is used as a reference axis, and when acquiring the image data of the measuring means so that the inclination direction of the reference axis changes with respect to the surface to be measured. Possible to change the acquisition posture Transforming means, analyzing the surface shape of the acquisition area of the test surface corresponding to the acquisition position and the acquisition posture based on the measurement image data acquired at the acquisition position and the acquisition posture, surface shape analysis calculation means, Control means for controlling the driving of the scanning means and the attitude varying means, wherein the control means calculates the next acquisition position using the current acquisition position and the measurement image data acquired at the acquisition posture, and A scanning-type wide-area inspection surface shape analyzing apparatus for calculating an acquisition attitude at a next acquired acquisition position. 2. The control device according to claim 1, wherein the control unit scans the measurement unit from the current acquisition position based on a surface shape of an acquisition area of the test surface acquired from the measurement image data at the current acquisition position and the acquisition posture. A position corresponding to an end position of the acquisition area of the test surface on the scanning line in the direction is obtained, and a linear distance from the current acquisition position to the next acquisition position is obtained from the current acquisition position. 2. The scanning wide area surface shape analysis according to claim 1, wherein the next acquisition position is calculated so as to be within two times a linear distance to a position corresponding to an end position of the measurement surface acquisition region. apparatus. 3. The acquisition area of the test surface corresponding to the measurement image data acquired at the current acquisition position and the acquisition attitude from the calculated next acquisition position, or an area on an extension thereof from the next acquisition position. The perpendicular vector at the intersection of the line parallel to the reference axis at the current acquisition position and orientation at the current acquisition position and the acquisition area or an area on an extension thereof is calculated. 3. The scanning-type wide-area inspection surface shape analyzing apparatus according to claim 1, wherein the inclination direction of the reference axis that is coincident or parallel is set as the acquisition posture at the next acquisition position. 4. The method according to claim 1, wherein when the measuring unit is moved toward the next acquisition position, a position where the measuring unit is moved is slightly different from the calculated next acquisition position. The current acquisition position drawn from the position to which the measurement unit is moved toward the acquisition area of the test surface corresponding to the measurement image data acquired at the current acquisition position and the acquisition attitude or an area on an extension thereof, And a perpendicular vector at an intersection position between a line parallel to the reference axis in the acquisition posture and the acquisition area or an extension area thereof, and the inclination direction of the reference axis that is coincident with or parallel to the obtained perpendicular vector. 4. The scanning type wide-area surface shape analyzing apparatus according to claim 3, wherein? 5. The control means is drawn from the calculated next acquisition position to an acquisition area of the test surface corresponding to the measurement image data acquired at the current acquisition position and the acquisition posture. The intersection point between the line parallel to the reference axis at the current acquisition position and the acquisition posture and the acquisition region is obtained, and a least square approximation plane is calculated based on the obtained intersection position and positions in the vicinity thereof. 3. The scanning-type wide-area inspection according to claim 1, wherein the inclination direction of the reference axis that is coincident with or parallel to the normal vector of the least-squares approximation plane is set as the acquisition posture at the next acquisition position. Surface shape analyzer. 6. The control means, after positioning the measuring means to the next acquisition position, determines the number of interference fringes indicated by the measurement image data based on the measurement image data acquired at the next acquisition position. 3. A scanning wide area inspection surface shape analysis according to claim 1 or 2, wherein an acquisition posture at which the calculated number of interference fringes is equal to or less than a predetermined number is determined as an acquisition posture at the next acquisition position. apparatus. 7. The surface shape analysis calculation means calculates a surface shape of an area portion where two adjacent acquisition regions overlap with each other among acquisition regions of a surface shape corresponding to measurement image data at each of the acquisition positions. The intermediate region surface shape calculation function calculates the surface shape of the region portion by combining the surface shapes of the two acquired regions adjacent to each other. A scanning-type wide-area inspection surface shape analyzing apparatus according to claim 1. 8. An area portion whose surface shape is calculated by the intermediate region surface shape calculation function is a first position corresponding to an acquisition position in one of the two adjacent acquisition regions and the other position. Is an area portion existing between the second position corresponding to the acquisition position in the acquisition area, and the intermediate area surface shape calculation function is configured to perform the first position of the one acquisition area and the second position of the other acquisition area. When calculating the surface shape at the target position between the second position, the distance from the first position of the one acquisition region to the target position and the second position of the other acquisition region from the target position are calculated. The surface shape at the target position is calculated by combining the surface shape of the one acquisition region and the surface shape of the other acquisition region using a weight coefficient defined by a ratio to the distance to the position 2. Features to The scanning-type wide-area inspection surface shape analyzing apparatus according to claim 7.