JP3228458B2 - Optical three-dimensional measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical three-dimensional measuring apparatus, and more particularly, to an optical three-dimensional measuring apparatus for performing three-dimensional measurement on a surface or an internal state of an object such as a light wave interference apparatus and a moire fringe analyzer. It relates to a measuring device.

[0002]

2. Description of the Related Art An interferometer or a moire fringe analyzer has been used as a means for measuring the flatness or the shape of a curved surface of an object such as various parts and products with high accuracy. For example, when measuring the flatness of an object on a flat plate using an interferometer, a light beam is irradiated to the surface to be inspected of the object, and interference formed based on the light beam reflected from the object and returned. The unevenness of the test surface is accurately measured from the stripe pattern.

In recent years, in analyzing such interference fringes and moiré fringes, a fringe pattern is taken into a computer from an imaging device such as a CCD camera and the like, and the phase is calculated to determine the surface shape or wavefront shape of the subject. However, since the optical resolution is generally higher than the resolution of the image sensor,
The density of fringes that can be analyzed is determined by the resolution (resolution) of the image sensor. Therefore, in order to analyze interference fringes having a high fringe density using an image sensor, it is necessary to optically increase the magnification of the subject image and lower the fringe density on the image sensor before analyzing. However, in this case, since the observation range of the subject is narrowed, it is difficult to measure the shape of the entire subject.

[0004] For this reason, while enlarging the subject image,
An image is divided and taken in such that adjacent regions overlap each other, and after analyzing each divided region, an aperture is used to connect the divided object images to each other by using data of the overlapped portion. It is known to measure the shape of the whole subject by a synthesis technique. The purpose of this technique is to measure the entire test surface using an interferometer having a smaller opening (measurement size) than the size of the test surface.

[0005]

However, according to such an aperture synthesizing technique, each time an image capturing operation from one small region of the subject is completed, an imaging system such as a camera and the subject are relatively moved. Environmental conditions for capturing images differ due to disturbances such as air fluctuations and vibrations for each of the divided regions, and it becomes difficult to capture images under the same conditions for all regions. . In addition, since it is necessary to sequentially capture a plurality of images, it takes a long time to capture the entire image of the subject. For this reason, it has been difficult to quickly and accurately capture the subject image by the above-described method using aperture synthesis.

Further, there has been proposed a method in which an image pickup device is moved on an image forming plane on which an object image is once formed, and each time an object image in a predetermined area is captured. According to this method, although the imaging time can be reduced as compared with the above-described method in which the measurement system and the subject are relatively moved, the speed cannot be significantly improved. Furthermore, since environmental conditions for capturing an image are different for each of the divided areas, it has been difficult to accurately capture the entire image of the subject.

The present invention has been made in view of such circumstances, and ensures high-resolution image analysis when performing three-dimensional measurement on the surface or inside of a subject based on image information from the subject. It is another object of the present invention to provide an optical three-dimensional measuring device that improves the speed and accuracy of capturing image information.

[0008]

SUMMARY OF THE INVENTION An optical three-dimensional measuring apparatus according to the present invention captures an image of a light beam carrying information on the surface or inside of an object from the object by an image sensor, and outputs the image on the surface of the object or on the surface of the object. Optical 3 that measures the inside three-dimensionally
In the dimension measurement device, the two
A plurality of image sensors that receive light beams from different subject areas of the subject at substantially the same time as light beams carrying two-dimensional image information, and a plurality of two-dimensional images captured by the plurality of image sensors. Storage means for storing reference image screen information including a position reference image used for alignment when combining images with each other.

In addition, two-dimensional image information of the surface or inside of each subject obtained by the plurality of imaging elements is synthesized,
It is preferable that an image information synthesizing unit that obtains image information of a subject area larger than each of the subject areas is provided. Further, it is preferable that the image information synthesizing means is means for synthesizing the two-dimensional image information on the surface or inside of each of the subject after performing the alignment of each of the subject areas.

In another optical three-dimensional measuring apparatus according to the present invention, a light beam carrying information on the surface or inside of the subject from a plurality of subjects is imaged by an image pickup device, and the surface of each subject is imaged. Alternatively, there is provided an optical three-dimensional measuring apparatus for three-dimensionally measuring a two-dimensional image of the inside, wherein a plurality of light-receiving devices each of which receives light beams carrying information on the surface or inside of the plurality of subjects at substantially the same time and images them. And a storage unit for storing reference image screen information including a position reference image used for alignment when synthesizing a plurality of two-dimensional images captured by the plurality of imaging devices. It is characterized by the following.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a first embodiment of an optical three-dimensional measuring apparatus according to the present invention.

As shown in FIG. 1, an optical three-dimensional measuring apparatus according to a first embodiment of the present invention is applied to a Fizeau-type interferometer, and outputs a He- beam which outputs a light beam 1a having a predetermined wavelength. Ne laser 1, divergent lens 2 for diverging light beam 1a, pinhole plate 3, half mirror 4 for dividing divergent light 1a into two light beams, light beam 1a
And a TV camera 6A, 6B having a CCD as an image sensor. A reference plate 7 made of glass is arranged downstream of the collimator lens 5 via a not-shown micro-vibration means for phase scanning. The reference plate 7 has a reference surface 7a on which surface processing has been performed with high precision. Reference plate 7
In the subsequent stage, a subject 8 having a test surface 8a is held by holding means 9 so as to face the reference surface 7a.

The TV cameras 6A and 6B include a TV camera 6
Monitors 10A and 10B such as a CRT for displaying an image of the test surface 8a captured by the A and 6B, and the TV cameras 6A and
A computer 11 for processing an image of the test surface 8a captured by 6B and a frame memory 12 for storing an image synthesized as described later are connected. TV
The cameras 6A and 6B are optical positions such that the TV camera 6A magnifies and captures the upper half area of the test surface 8a, and the TV camera 6B magnifies and captures the lower half area of the test surface 8a. It is arranged keeping the relationship.

The computer 11 combines the image information of the upper half area and the image information of the lower half area of the surface 8a to be inspected to obtain image information of an area larger than each area. Thus, the surface shape of the test surface 8a is measured.

Next, the operation of the optical three-dimensional measuring apparatus according to the first embodiment of the present invention will be described. First,
A light beam 1 a is emitted from the He-Ne laser 1, and the light beam 1 a is converged by a diverging lens 2 at a pinhole position of a pinhole plate 3. A part of the light beam 1a passing through the pinhole passes through the half mirror 4 and is converted into a parallel light by the collimator lens 5. The collimated light beam 1a passes through the reference plate 7 and a part thereof
a and the remaining part is reflected by the subject 8
Are irradiated on the test surface 8a, reflected on the test surface 8a, and interference occurs between the light beams reflected on the reference surface 7a and the test surface 8a.

The light beam in which the light interference occurs as described above is partially reflected by the half mirror 4 via the collimator lens 5 and is simultaneously incident on the TV cameras 6A and 6B.

Here, the TV camera 6A magnifies the upper half area of the surface 8a to be imaged and takes an image, and the TV camera 6B magnifies the lower half area of the surface 8a and takes an image. A light beam carrying information of an enlarged image (hereinafter referred to as an upper region image) of interference fringes in the upper half region of the test surface 8a is incident on the TV camera 6A because the arrangement is maintained. Then, a light beam carrying information of an enlarged image of interference fringes (hereinafter referred to as a lower region image) in a lower half region of the test surface 8a enters the TV camera 6B. In this manner, the TV camera 6A captures the upper region image of the test surface 8a to obtain upper region image information, and the TV camera 6B captures the lower region image of the test surface 8a and obtains the lower region image. Information is obtained. At this time, imaging is performed such that the upper region and the lower region of the test surface 8a slightly overlap with each other.

The inspection surface 8 captured by the TV camera 6A
The upper region image information a is input to the monitor 10A, and information on interference fringes in the upper half region of the test surface 8a is displayed as a visible image. On the other hand, the lower area image information of the test surface 8a captured by the TV camera 6B is input to the monitor 10B, and information on interference fringes in the lower half area of the test surface 8a is displayed as a visible image. The monitors 10A, 10A
The image information displayed on B is taken into a frame memory built in the computer.

Next, the computer 11 performs predetermined arithmetic processing on the upper region image information taken into the frame memory, and synthesizes the information. Here, as shown in FIG. 2, the memory 13 of the computer 11 has a mark 13 indicating the boundary between the upper area and the lower area handled by the TV cameras 6A and 6B (if the boundary can be recognized, the mark 13 may be used instead of the mark by roughening. Is obtained, and the boundary is specified on the image. Two TV cameras 6 are used to acquire the reference image.
A reference object having a size larger than the image area that can be covered by A and 6B is used.

The synthesized image information thus obtained is
It is developed in a memory (not shown) so as to be easily operated. Then, interference fringe analysis is performed on the synthesized image information,
The surface shape of the test surface 8a can be measured.

Here, since the upper area image information and the lower area image information are respectively enlarged and imaged by the TV cameras 6A and 6B, the TV area is compared with that obtained without enlarging the test surface 8a. The stripe density on the imaging elements provided in the cameras 6A and 6B is low. Therefore, in the composite image information, the interference fringes can be analyzed with high resolution as compared with the image obtained without imaging the test surface 8a.

Since the upper area image information and the lower area image information are simultaneously captured by the TV cameras 6A and 6B, they are captured under the same environmental conditions. For this reason, it is possible to obtain accurate composite image information while eliminating the influence of fluctuations in environmental conditions due to disturbances such as air fluctuations and vibrations. Furthermore, since the upper region image information and the lower region image information are simultaneously captured, it is possible to quickly and accurately capture the image of the test surface 8a without taking a long time to capture the entire image of the test surface 8a. Can be.

Next, an optical three-dimensional measuring apparatus according to a second embodiment of the present invention will be described. FIG. 5 is a diagram illustrating a configuration of an optical three-dimensional measurement apparatus according to the second embodiment. In FIG. 5, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description will be omitted. The device of the second embodiment divides the surface 8a to be inspected into four regions, irradiates each region to the screen 17, and outputs the four TV cameras 16A to 16A to
16D simultaneously captures four monitors 20A-20
D is different from the device of the first embodiment in that it is indicated by D.

As described above, the surface 8a to be inspected is divided into four regions, and the image information of each region is transmitted to the TV cameras 16A to 16D.
By taking an image according to the first embodiment, image information of each area can be obtained under the same environmental conditions as in the first embodiment, and moreover, compared to the first embodiment,
Furthermore, since the apparent fringe density can be reduced, it is possible to quickly, accurately, and accurately capture the image of the test surface 8a and analyze the interference fringes with high resolution to calculate the shape of the test surface 8a with high accuracy. it can.

By slightly moving the reference plate stepwise in the light beam direction, the TV cameras 6A, 6B, 16A-
By changing the phase of the interference fringe captured in 16D in a stepwise manner and capturing a plurality of interference fringe images with the changed phase, it is possible to analyze the interference fringe by the phase scanning method in the composite image information.

In each of the above embodiments, the present invention is applied to a Fizeau interference fringe analyzer, but the present invention may be applied to other interference fringe analyzers or moiré fringe analyzers. Also in this case, it is possible to satisfactorily analyze the surface shape of the surface to be inspected as in the above embodiment. If the present invention is applied to a transmission type interference fringe analyzer, it is possible to satisfactorily perform three-dimensional measurement on a change in the density inside the subject.

Further, in the above-described embodiment, one test surface 8a is divided into a plurality of regions and imaged, and the images are combined to obtain the entire image of the test surface 8a. The surfaces of a plurality of optical components such as lenses and mirrors constituting one optical system, or the surfaces of three dichroic mirrors mounted on a color liquid crystal projector are simultaneously imaged by a plurality of TV cameras, and each of the optical components is imaged. Image information of interference fringes representing the surface shape may be obtained, and the surface shape of each optical component may be analyzed based on the image information. Accordingly, image information on the surface of each optical component can be obtained under the same environmental conditions, and the relative relationship between the surface shapes of the optical components used at the same time can be obtained well and easily. In addition, since the image information of the surface of each optical component is imaged at the same time, the processing can be performed quickly.

Further, in the above-described embodiment, information on the mark 13 as shown in FIG. 2 is stored in the memory of the computer 11 as a reference of the boundary of the area, which is used when synthesizing image information of a plurality of areas. However, instead of this, a masking member that enables imaging of only a predetermined region is arranged in the optical path, and image information of each region obtained through this masking member is connected so that edges thereof are in contact with each other. By doing so, the operation of synthesizing image information of a plurality of areas can be facilitated.

Further, in the above embodiment, a frame memory is provided for each area image information. Instead, each area image information is fetched into the frame memory in a time-division manner by a video signal switching means, and each information is stored. It is also possible to configure so that data is transmitted to the main memory.
When a single frame memory is used in this way, it is not possible to capture all the area image information at the same time, but compared with a conventional technique that captures each area image information every time the image sensor is physically moved, for example. For example, it can be considered that each area image information is taken in almost simultaneously.

In the above embodiment, each area image information of the surface to be inspected is taken in by two or four image pickup elements. However, each area image information is taken in by a plurality of other image pickup elements. Of course it is possible.

[0031]

As described in detail above, according to the optical three-dimensional measuring apparatus of the present invention, light beams from different object regions of the object are simultaneously received and imaged. Therefore, it is possible to obtain image information of each subject area under the same environmental condition, thereby performing three-dimensional measurement of the surface or the inside of the subject with high resolution without being affected by the fluctuation of the environmental condition. Can be. In addition, since each subject region is imaged simultaneously, image information of each subject region can be obtained quickly,
Thereby, measurement on the surface or inside of the subject can be performed quickly.

Further, by simultaneously receiving and imaging light beams from different object regions of the plurality of objects at the same time, image information of the plurality of objects can be obtained under the same environmental conditions. For example, for a plurality of optical elements used in one optical system, the surface or the inside of each subject can be three-dimensionally measured without being affected by fluctuations in environmental conditions. In addition, since a plurality of subjects are simultaneously imaged, image information of each subject can be quickly obtained, and thereby, the surface or the inside of the plurality of subjects can be measured quickly. . Note that by using a plurality of image sensors, the substantial resolution can be increased in accordance with the number of image sensors.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an optical three-dimensional measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing reference image information marked with a boundary between an upper region and a lower region of a surface to be inspected;

FIG. 3 is a diagram for explaining synthesis of upper region image information and lower region image information.

FIG. 4 is a diagram showing composite image information of upper region image information and lower region image information.

FIG. 5 is a diagram showing a configuration of an optical three-dimensional measuring device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 He-Ne laser 1a Light beam 2 Divergent lens 3 Pinhole plate 4 Half mirror 5 Collimator lens 6A, 6B, 16A-16B TV camera 7 Reference plate 7a Reference surface 8 Subject 8a Subject surface 10A, 10B, 20A-20D Monitor 12 frame memory

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B 11/00-11/30 102 G06T 1/00 G06T 7/00 G06T 7/60

Claims (4)

(57) [Claims] An optical device for imaging a light beam from a subject carrying information on the surface or inside of the subject with an image sensor, and three-dimensionally measuring the surface or inside of the subject.
In dimension measurement apparatus, a plurality of image pickup elements that respectively substantially imaged by receiving simultaneously a light beam from different subject areas of the analyte surface or inside of the two-dimensional image information with a light beam carrying the analyte
And a plurality of two-dimensional images captured by the plurality of image sensors.
Positions used for alignment when combining images with each other
An optical three-dimensional measuring apparatus , comprising: storage means for storing reference image screen information including a reference image . 2. An image information synthesizing unit that synthesizes two-dimensional image information of the surface or inside of each subject obtained by the plurality of imaging elements and obtains image information of a subject area larger than each of the subject areas. 2. The method according to claim 1, further comprising:
The optical three-dimensional measuring apparatus according to claim 1. 3. The method according to claim 2, wherein the image information synthesizing unit adjusts the position of each of the object areas, and then adjusts the surface of each of the object.
3. An optical three-dimensional measuring apparatus according to claim 2, wherein the optical three-dimensional measuring apparatus is means for synthesizing two-dimensional image information inside . 4. An optical three-dimensional image pickup device that picks up an image of a light beam carrying information on the surface or inside of the subject from a plurality of subjects using an image sensor, and three-dimensionally measures the surface or inside of each subject. A measurement device, comprising: a two-dimensional image of a surface or inside of a plurality of subjects.
A plurality of image sensors that receive light beams carrying image information at substantially the same time and capture images, and an image captured by the plurality of image sensors ;
Alignment when combining multiple two-dimensional images
Stores reference image screen information including the image of the position reference used
Optical 3 to the storage means and characterized in that it comprises a
Dimension measurement device.