JPH11344329A - Three dimensional shape measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three dimensional measuring device capable of easily and accurately measuring the three dimensional shape of each surface of an optical element and the like constituted of a plurality of surfaces of two or more. SOLUTION: By the indexing drive of an indexing device 7 provided with a rotary shaft 7a supported by an air bearing 7b and a motor 7c with encoder, a measuring jig 2 fixed to the rotary shaft 7a rotates to be accurately indexed and positioned. By scanning the measuring surface of a work 15 loaded on the measuring jig 2 with a probe 1, three dimensional shape of each measuring surface of the work 15 is measured. By measuring the shape of three or more reference balls 11a, 11b arranged on the measuring jig 2, the hypothetical plane passing the center point of each reference ball obtained as a reference plane, the relative position of each measuring surface of the measuring work 15 to the reference plane can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional shape measuring apparatus for measuring a three-dimensional shape of an object having one or more curved surfaces.

[0002]

2. Description of the Related Art Conventionally, a three-dimensional shape measuring device has been used for measuring the surface shape of an optical lens or the like having an aspherical surface.
A measuring device described in Japanese Patent No. 5346 is known. As shown in FIG. 5, a three-dimensional shape measuring apparatus of this type includes a probe 103 for tracing a work 101, which is a measurement target placed on a work mounting table 102, and holding the probe 103 in a vertical direction. The laser measuring device 1 includes a Z stage 104 that moves, an XY stage 105 that can move in the horizontal direction while holding the Z stage 104, and a laser length measuring device 106 provided on the XY stage 105.
A beam splitter 107 and a plurality of mirrors 108, 109, and 110 for reflecting laser light are arranged on the optical path 06, and one of the plurality of mirrors 108 holds the probe 103 as a laser length measuring mirror. The other mirror 109 is disposed on the stage 104, and another mirror 109 is disposed at a fixed position at a predetermined distance H from the work mounting table 102 so as to face the mirror 108. The probe 103 scans the surface of the work 101 by moving the XY stage 105 in the horizontal direction.
The Z stage 104 is moved up and down according to the height of the surface in the Z direction of 01, and the mirror 108 for laser length measurement fixed to the Z stage 104 is moved up and down. The movement of the laser length measuring mirror 108 is measured by the laser length measuring device 106, and the three-dimensional shape of the workpiece 101 is calculated from the measurement result.

[0003]

By the way, the object to be measured is not limited to an object composed of only one upper surface. For example, a normal optical lens has two front and rear surfaces. In today's optical components, there are optical elements such as prisms composed of a plurality of two or more surfaces each having an aspherical surface or a free-form surface.

[0004] When an optical element such as a prism composed of two or more surfaces is measured by the above-described conventional three-dimensional shape measuring apparatus, each measuring surface is set to face the probe. Setup is required. This setup is troublesome and requires skill, so that the measurement is very complicated.

Further, when measuring an optical element such as a prism composed of a plurality of two or more surfaces using a conventional three-dimensional shape measuring apparatus as described above, the relative position error of each surface of the optical element is measured. That was impossible.

Accordingly, the present invention has been made in view of the above-mentioned unsolved problems of the prior art,
It is an object of the present invention to provide a three-dimensional shape measuring apparatus capable of easily and highly accurately measuring a three-dimensional shape of an object to be measured such as an optical element composed of two or more surfaces. .

[0007]

In order to achieve the above object, a three-dimensional shape measuring apparatus of the present invention scans a three-dimensional shape of a measurement object with a contact or non-contact probe to thereby change the shape of the measurement object. In a three-dimensional shape measuring apparatus for measuring, a means for performing rotation indexing of the object to be measured is provided, and a rotating shaft of the means is supported by an air bearing.

[0008] In the three-dimensional shape measuring apparatus of the present invention, the means for indexing the object to be measured includes: a holder for the object to be measured attached to a rotating shaft supported by an air bearing; It is preferable that the device for indexing and driving the tool be provided with an encoder for detecting the rotation angle of the rotary shaft.

Further, in the three-dimensional shape measuring apparatus of the present invention, it is preferable that at least three or more spheres are arranged on the measuring object holder of the means for indexing the measuring object.

In the three-dimensional shape measuring apparatus according to the present invention, it is preferable that the three-dimensional shape measuring apparatus includes a plurality of means for determining an object to be measured.

[0011]

According to the three-dimensional shape measuring apparatus of the present invention, there are provided means for indexing an object to be measured, and the rotating shaft of the means for indexing is supported by an air bearing, whereby a plurality of two or more surfaces are measured. When measuring the three-dimensional shape of each surface of the measurement object such as an optical element by scanning with a contact or non-contact probe, the measurement surface of the measurement object is appropriately set with respect to the measurement probe Setup can be simplified and time can be shortened, and furthermore, it is possible to accurately determine each measurement surface of a measurement object without requiring an operation requiring skill for setup. Furthermore, by measuring the three-dimensional shape of each surface of the measurement object composed of a plurality of surfaces of two or more surfaces with high precision, and by adopting a configuration in which the rotating shaft is supported by an air bearing, The eccentricity error of the movable part can be eliminated, the rotation accuracy can be improved, and the relative position error of each surface of the measurement object composed of a plurality of two or more surfaces can be measured extremely accurately. .

Furthermore, using at least three or more true spheres as reference spheres arranged on the object holder, the shapes of these true spheres are measured to determine the center points of the true spheres, and the centers of the true spheres are determined. A virtual plane passing through a point is used as a reference plane, and the relative position of each surface of a measurement target such as an optical element composed of a plurality of two or more surfaces from the reference plane can be measured. The measurement operation is simplified, and the measurement time can be reduced.

Further, by providing a plurality of means for determining the object to be measured, each measuring surface of the object to be measured such as an optical element composed of a plurality of two or more surfaces can be optimized accurately and accurately. It is possible to set the indexing position to a certain value, and it is possible to accurately measure each measurement surface.

[0014]

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

FIG. 1 is a schematic view of the overall configuration of a three-dimensional shape measuring apparatus according to the present invention, and FIG. 2 is an enlarged view of an indexing device and a measuring jig in the three-dimensional shape measuring apparatus according to the present invention. FIG. 3 is a schematic perspective view showing the indexing device and the measuring jig in a state where the measuring object is being measured.

In FIG. 1, reference numeral 1 denotes a probe for scanning the surface of an object to be measured (not shown in FIG. 1) mounted on a measuring jig 2, and the probe 1 is moved in a Z direction (vertical direction in FIG. 1). Is held by a Z slide 3 which can be moved to The probe 1 has a built-in sensor for contacting and tracing the measurement surface of the measurement object mounted on the measurement jig 2.
The one having a structure as disclosed in Japanese Unexamined Patent Publication (Kokai) No. HEI 10-301 is used. In this embodiment, a contact-type probe will be described as an example, but a non-contact probe may be used instead of the contact-type probe.

A Y slide 5 is provided on a mount 6 of the three-dimensional shape measuring apparatus so as to be movable in the Y direction.
Are supported by a Y slide 5 so as to be movable in the X direction, and a Z slide 3 that is movable in the Z direction is supported by an X slide 4. These Z slide 3, X slide 4, and Y The slide 5 is an electrical equipment rack 8 described later.
By each drive driver arranged in, Z, respectively
It is configured to be driven in the X and Y directions. By driving these slides 3, 4, and 5, the probe 1 held by the Z slide 3 can be moved on the gantry 6 in the X direction and the Y direction, and can be moved in the Z direction. The amount of movement of the Z slide 3 in the Z direction (vertical direction in FIG. 1) and the amount of movement of the X slide 4 in the X direction (FIG. 1)
Of the Y slide 5 (the direction perpendicular to the plane of FIG. 1) of the Y slide 5 is measured by a laser length measuring machine or a scale such as an optical scale (not shown).

The indexing device 7 arranged on the gantry 6
A rotating shaft 7a having a measuring jig 2 attached to a tip thereof; and a motor 7c with an encoder configured to rotationally drive the rotating shaft 7a and detect a rotation index angle thereof,
The rotating shaft 7a is supported by an air bearing 7b (see FIGS. 2 and 3). By driving a motor 7c with an encoder, the rotating shaft 7a and the rotation of the measuring jig 2 attached to the tip thereof are rotated. In addition, indexing can be performed with high accuracy, and as a result, the measurement target mounted on the measuring jig 2 can be accurately indexed and positioned such that each measurement surface thereof faces the probe 1. 8
Is a driver for driving the X, Y, and Z axes of the X slide 4, the Y slide 5, and the Z slide 3 and a driving driver of the indexing device 7, and measuring the amount of movement of each of the X, Y, and Z slides. The electrical equipment rack is equipped with an electrical system or the like that takes in laser measurement data to be measured and output data of an encoder that measures the rotation index amount.
A control computer for instructing a driving amount and a driving method to a driver for driving each of the X, Y, and Z axes, a driving driver of the indexing device 7, and the like. 10 is a computer having a man-machine interface. It has a function of setting design values and measurement procedures necessary for measurement, a function of displaying measurement results on a monitor, and a function of recording the results in a storage device.

As shown in FIGS. 2 and 3, the measuring jig 2 holds each surface of the measuring work 15 to be measured, which is to be measured, upward so as to face the probe 1. It is configured in a rectangular frame that can
The indexing device 7 is attached to the tip of the rotating shaft 7a. Then, as described above, the indexing device 7 rotationally drives the rotary shaft 7a supported by the air bearing 7b by the motor 7c with the encoder, detects the rotation index angle, and sets the rotary shaft 7a to a predetermined rotation index angle. Position. Therefore, when the indexing device 7 is driven in accordance with the indexing command transmitted from the control computer 9 to the drive driver, the measuring jig 2 is rotated via the rotating shaft 7a and sequentially by the encoder of the motor with encoder 7c. The rotation angle is read, and when the rotation angle reaches a predetermined rotation index angle, the rotation drive is stopped, and the measurement surface of the measurement work 15 mounted on the measurement jig 2 is indexed and positioned so as to face the probe 1.

Further, at least three or more true spheres as reference spheres are attached to the measuring jig 2, and FIGS.
, Three reference spheres (true spheres) 11a, 11b, and 11c are provided on three sides of the rectangular frame of the measuring jig 2 except for the side mounted on the rotating shaft 7a.
And 12c. At least three reference spheres (true spheres) 11a, 11b, 11c
As will be described later, the probe 1 measures the surface shape of each reference sphere to determine the center coordinates of each reference sphere, calculates a virtual plane formed by the center coordinates, and sets this virtual plane as the reference plane. Thus, the relative position of each measurement surface of the measurement work 15 can be measured.

Next, the three-dimensional shape measuring apparatus of the present invention configured as described above will be described with reference to the measurement flow shown in FIG. The measurement work 15 in the present embodiment will be described using an optical element that measures the shape of two surfaces, a front surface and a back surface, as an example.

When measurement is selected by the computer 10 in FIG. 1, the control computer 9 starts the measurement flow shown in FIG. Step S01 (read design data)
In step (2), design condition data and measurement condition data such as a measurement range of the measurement work 15 stored in the control computer 9 in advance are read. When the design data and the measurement condition data are not stored in advance, the computer 10 can input various data from a keyboard or the like. In step S02 (index drive), the measurement condition data is transmitted from the control computer 9 to the computer 1
0, and a command is sent from the control computer 9 to the drive driver of the indexing device 7 of the electrical equipment rack 8 to determine the first surface of the measurement work 15. Thus, the indexing device 7 starts rotating. Step S0
In 3 (index OK?), The rotation data is read by the encoder of the indexing device 7 and it is determined whether or not the indexing rotation angle has reached the command value. The rotational drive of the device 7 is continued. When the indexing rotation angle reaches the command value, the first surface of the measurement work 15 mounted on the measuring jig 2 faces in the direction as the command (that is, the direction facing the probe 1), and measurement is possible. State.

Next, in step S04 (reference sphere measurement),
The central coordinates of the three reference spheres 11a, 11b and 11c are measured. That is, first, the X slide 4 and the Y slide 5 are driven to position the probe 1 at a predetermined center position of the reference sphere 11a, and then the Z slide 3 is driven to move the probe 1 to the surface of the reference sphere 11a. Contact. The reference sphere 1 for positioning the probe 1 first
Since the position relative to 1a only needs to be able to measure the reference sphere 11a by the probe 1, it is not necessary to accurately set the center position of the reference sphere 11a, and the coordinate position read from the design drawing is usually sufficient. Thereafter, the X slide 4 and the Y slide 5 are held in a state where the probe 1 is in contact with the surface of the reference sphere 11a.
Is driven to capture the length measurement data of the Z slide 3, the X slide 4, and the Y slide 5, and the surface shape of the reference sphere 11a is measured from the length measurement data. Reference sphere 1
When the shape measurement of 1a is completed, the surface shapes of the reference spheres 11b and 11c are similarly measured in order. Then, an accurate center position of each reference sphere is calculated from the shape measurement data of each of the reference spheres 11a, 11b, 11c and stored.

Next, in step S05 (workpiece first surface measurement), the shape of the first surface of the measurement work 15 is measured. That is, first, the X slide 4 and the Y slide 5 are driven to position the probe 1 at the preset measurement start point of the measurement work 15, and then the Z slide 3 is driven to move the probe 1 to the measurement work 15. Contact the surface. Thereafter, the X slide 4 and the Y slide 5 are driven in accordance with the data previously sent from the control computer 9 as the measurement condition data, and the respective length measurement data of the Z slide 3, the X slide 4 and the Y slide 5 are taken. Thus, the three-dimensional shape of the first surface of the measurement work 15 is measured from the length measurement data. When step S05 (workpiece first surface measurement) is completed, step S0
In 6 (calculation processing), a coordinate conversion processing operation is performed.
The shape of the first surface of the measurement work 15 has three reference spheres 11a,
It is calculated based on the center of the reference sphere 11a on the reference plane passing through the three center points of 11b and 11c.

Thereafter, step S07 (index driving)
, The indexing drive is performed so that the second surface of the measurement work 15 can be measured. Measurement work 1 from control computer 9 to drive driver of indexing device 7 of electrical equipment rack 8
A command is sent to determine the second surface 5, and in response to the command, the indexing device 7 rotates to rotate the measurement work 15 together with the measurement jig 2. In step S08 (index OK?), As in step S03, it is determined whether or not the rotation angle matches the command value for measuring the second surface of the measurement work 15 based on the data from the encoder of the indexing device 7. I do. If the command value has not yet been reached, the flow returns to step S07 to continue the rotation drive. When the indexing rotation angle matches the command value, the second surface of the measurement work 15 mounted on the measuring jig 2 faces in the direction as the command (that is, the direction facing the probe 1), and measurement is possible. State. In this embodiment, since the measurement work 15 is an optical element having two front and back surfaces, the indexing drive of 180-degree rotation is performed.

Next, in step S09 (measurement of the second surface of the work), the shape of the second surface of the measurement work 15 is measured as in step S05 (measurement of the first surface of the work). Calculation)
From the reference sphere coordinate position with respect to the first surface measured in step S04 (reference sphere measurement) and the reference coordinates calculated by the index rotation angle when the second surface is indexed, measurement is performed in the same manner as in step S06 (calculation processing) described above. The shape of the second surface of the work 15 is calculated based on the reference sphere. The three-dimensional shape of the first surface and the three-dimensional shape of the second surface of the measurement work 15 are planes formed by the center coordinates of the same reference spheres 11a, 11b, and 11c, and are based on the center of the same reference sphere 11. Also, the positional relationship between the first surface and the second surface of the measurement work 15 can be calculated.

When step S10 (calculation processing) is completed,
At step 11 (result output), the results of the measurement and calculation are output via a computer 10 by an output device (not shown) such as a monitor or a printer. Further, at step S12 (measurement data storage), the results of the measurement and calculation are output. A storage device built in the control computer 9 or the computer 10 or an external storage device (not shown)
And the shape measurement of the front and back surfaces of the measurement work 15 is completed.

As described above, in the indexing device 7 of this embodiment, the rotating shaft 7a is attached to the air bearing 7
b and driven by the motor with encoder 7c, it is possible to accurately index and position at a predetermined rotation index angle, and to measure the three-dimensional shape of each surface of the measurement work composed of a plurality of surfaces. It is possible to eliminate the eccentricity error of the movable portion by improving the accuracy of the rotation and supporting the rotating shaft 7a with the air bearing 7b, to improve the rotation accuracy, and to be constituted by a plurality of surfaces. It is possible to measure the relative position error of each surface of the measurement work with extremely high accuracy.

In this embodiment, the measurement work 1
Although an optical element having two front and back surfaces has been described as 5, even in the case of an optical element such as a prism composed of three or more surfaces, similarly, each surface can be appropriately determined by an indexing device and each surface can be accurately measured. Needless to say. In addition, depending on the shape of the measurement surface, if the inclination of the measurement surface with respect to the measurement probe is gentler when the measurement surface is inclined than at the reference position, it is possible to appropriately select the optimal index angle under the measurement conditions. is there.
Further, in the present embodiment, the indexing device has a mechanism for performing an indexing rotation about the X axis.
By providing another indexing mechanism or a tilting mechanism, it is possible to further add a mechanism for performing indexing by rotation about the Y axis.

[0030]

As described above, according to the present invention,
A three-dimensional shape measuring device that measures the three-dimensional shape of a measurement target by scanning with a contact or non-contact probe is provided with a means for determining the measurement target, thereby comprising a plurality of two or more surfaces. When measuring the three-dimensional shape of each surface of an object to be measured, such as an optical element, the setup for properly installing the measurement surface with respect to the measurement probe can be simplified and the time can be shortened. This also eliminates the need for highly skilled work.

Further, using at least three or more spheres as reference spheres arranged on the object holder, the shape of these spheres is measured to determine the center point of the sphere.
A virtual plane passing through these center points is defined as a reference plane, and the relative position of each surface of a measurement target such as an optical element composed of a plurality of surfaces of two or more from the reference plane can be measured.
Also in this case, the measurement operation is simplified, and the measurement time can be shortened.

Further, in the means for determining the object to be measured, the rotation axis thereof is supported by an air bearing, so that the eccentricity error of the movable part can be eliminated and the rotation accuracy can be improved. By providing an encoder for detecting the rotation angle of the rotation shaft, it is possible to accurately determine and position the rotation at a predetermined rotation index angle, and a measurement object such as an optical element composed of a plurality of two or more surfaces The three-dimensional shape of each surface can be measured with high accuracy, and the relative position error of each surface can be measured with extremely high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of the overall configuration of a three-dimensional shape measuring apparatus according to the present invention.

FIG. 2 is an enlarged schematic perspective view showing an indexing device and a measuring jig in the three-dimensional shape measuring apparatus of the present invention.

FIG. 3 is a schematic perspective view showing a part of an indexing device and a measuring jig in the three-dimensional shape measuring apparatus according to the present invention in a state where an object to be measured is measured.

FIG. 4 is a measurement flowchart of the three-dimensional shape measuring apparatus of the present invention.

FIG. 5 is a schematic view of a conventional three-dimensional shape measuring apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Probe 2 Measurement jig 3 Z slide 4 X slide 5 Y slide 7 Indexing device 7a Rotating shaft 7b Air bearing 7c Motor with encoder 8 Electrical rack 9 Control computer 10 Computer 11a, 11b ... Reference sphere (true sphere) 15 Measurement work (Measurement target)

Claims (4)

[Claims] 1. A three-dimensional shape measuring apparatus for measuring the shape of a measuring object by scanning the three-dimensional shape of the measuring object with a contact or non-contact probe, comprising means for rotating and indexing the measuring object. A three-dimensional shape measuring apparatus, wherein the rotating shaft of the means is supported by an air bearing. 2. The means for determining an object to be measured includes:
A measuring object holder attached to a rotating shaft supported by an air bearing, and a device for indexing and driving the measuring object holder, wherein the index driving device detects a rotation angle of the rotating shaft. The three-dimensional shape measuring apparatus according to claim 1, further comprising an encoder. 3. The three-dimensional shape measuring apparatus according to claim 1, wherein at least three or more spheres are arranged on the measuring object holder of the means for determining the measuring object. 4. The three-dimensional shape measuring apparatus according to claim 1, further comprising a plurality of means for determining an object to be measured.