JP3899623B2 - Image inspection / measurement equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image inspection / measurement apparatus that projects an inspection object onto an imaging device via an optical system and inspects or measures the inspection object using a photoelectrically converted image signal.
[0002]
[Prior art]
An object to be inspected placed on a stage movable in the horizontal direction is enlarged and projected onto an imaging device via an optical system, and the surface shape and defects of the object to be inspected using an image signal obtained by photoelectric conversion of the projection image Image inspection / measuring devices that measure inspections, coordinates, dimensions, etc. are widely used. In such an image inspection / measurement apparatus, it is desirable to be able to change the magnification of the optical system in as wide a range as possible so that inspection objects of various sizes can be inspected / measured with a necessary resolution.
[0003]
In particular, in order to search for an inspection point from the entire inspection object, and then to enlarge a part of the inspection object and inspect and measure with a high resolution, the inspection object is projected with a wide field of view, that is, a low magnification, and a high resolution. That is, an optical system capable of projecting an inspection object at a high magnification is required. Therefore, an objective lens switching method using a so-called revolver or turret, or a variable magnification optical system using a zoom optical system is used.
[0004]
However, the magnification obtained by the objective lens switching method is determined by the type of the mounted objective lens, and a magnification suitable for the object to be inspected may not be obtained. On the other hand, the zoom optical system can continuously change the magnification, so that the optimum magnification can be obtained for the object to be inspected, and the zooming operation is intuitive and easy to operate. is there.
[0005]
FIG. 5 is a general configuration diagram of a lens barrel 52 using such a zoom optical system. This zoom optical system 33 is an example using an afocal zoom optical system. An objective lens 31 is provided below the zoom optical system 33. The light beam from the inspection object 32 is collimated by the objective lens 31 and enters the zoom optical system 33. The light beam incident on the zoom optical system 33 passes through the lens 43 and is zoomed by the zoom lenses 42 and 41 and becomes parallel light again by the lens 40. The parallel light is projected onto the imaging surface 35 by the imaging lens 34 to form a surface image of the inspection object.
[0006]
The zoom optical system 33 has lens chambers 36 and 37 in which variable magnification lenses 41 and 42 are housed. The lens chambers 36 and 37 are driven by the positioning drive mechanism 39 with a predetermined relationship, and move in the optical axis direction along the movement guide mechanism 38.
[0007]
[Problems to be solved by the invention]
However, the zoom ratio of the zoom optical system has a practical limit of about 10. The zoom optical system must realize a low magnification to a high magnification with a single objective lens, and it is difficult to design and manufacture the lenses and mechanisms that make up the zoom in proportion to the increase in zoom ratio. Because it becomes.
[0008]
However, in actual operation of the inspection / measurement apparatus, particularly teaching work for automatic operation, it is desirable to have a wider field of view, that is, a lower magnification, when searching for initial positioning and inspection locations. On the other hand, when the inspection / measurement target is very fine, or in order to detect the end face position with high resolution, a higher magnification is desired. From a practical aspect, this zoom magnification ratio is desired to be about 100.
[0009]
If the objective lens switching method is used, larger zooming is possible depending on the configuration, but the flexibility to set the optimum magnification according to the object to be inspected is poor, and continuous zooming is not possible, resulting in poor operability. There is a drawback.
[0010]
Accordingly, an object of the present invention is to provide an image inspection / measurement apparatus that can obtain a large zoom ratio while taking advantage of the flexibility of a zoom optical system.
[0011]
[Means for Solving the Problems]
The above object is to provide an image inspection / measurement apparatus that inspects or measures the inspection object using an image signal of the inspection object imaged by the imaging apparatus via the optical system. , A light branching means for branching the light beam from the objective lens, a first optical system for changing the magnification of one light beam branched by the light branching means on the high magnification side, and the other light beam branched by the light branching means This is achieved by providing an image inspection / measuring device having a second optical system that changes the magnification on the low magnification side.
[0012]
According to the present invention, a zoom ratio of about 100 is obtained substantially by the first optical system on the high magnification side and the second optical system on the low magnification side. Moreover, there is a single objective lens, and an illumination system, a drive mechanism, etc. can be used in common. Furthermore, it can be operated in the same manner as a single zoom optical system, and the operability is good.
[0013]
The first optical system of the image inspection / measurement apparatus according to the present invention includes an intermediate magnification optical system that adds a predetermined magnification to the light beam from the light branching unit, and a variable light beam from the intermediate magnification optical system. And a first zoom optical system.
[0014]
According to the present invention, the first optical system on the high magnification side does not obtain a large zoom ratio only by the zoom optical system, but has an intermediate magnification optical system having a predetermined magnification and a zoom ratio of about 10. Since it can be configured with the first zoom optical system, it is easy to design and manufacture.
[0015]
The second optical system of the image inspection / measurement apparatus of the present invention includes a relay lens that adjusts an angle of view of the light beam from the light branching unit, and a second zoom that scales the light beam from the relay lens. And an optical system.
[0016]
According to the present invention, a light beam having a large angle of view at a low magnification can be guided to the second zoom optical system without leakage by the relay lens. The second zoom optical system is easy to design and manufacture because a zoom ratio of about 10 is sufficient.
[0017]
Further, the first and second zoom optical systems of the image inspection / measurement apparatus of the present invention are driven by a common drive mechanism.
[0018]
According to the present invention, since the first and second zoom optical systems can be driven by a common drive mechanism, the drive mechanism is simplified, and the operation can be performed similarly to the single zoom optical system, so that the operability is good. .
[0019]
Further, in the image inspection / measurement apparatus for inspecting or measuring the inspection object using an image signal of the inspection object imaged by the imaging apparatus via the optical system,
The optical system includes an objective lens, an intermediate magnification optical system that adds a predetermined magnification to a light beam from the objective lens, a relay lens that adjusts an angle of view of the light beam from the objective lens, the intermediate magnification optical system, and a relay There is provided an image inspection / measurement apparatus comprising: a selection unit that selects a lens; and a zoom optical system that varies a light flux from an intermediate magnification optical system or a relay lens selected by the selection unit. Is achieved.
[0020]
According to the present invention, since the intermediate magnification optical system and the relay lens can be selected by the selection means, a large zoom ratio can be realized with a single zoom optical system. For this reason, the configuration is simplified, and downsizing and cost reduction are possible.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention.
[0022]
FIG. 1 is an overall configuration diagram of an image inspection / measurement apparatus according to an embodiment of the present invention. A lens barrel 52 having a zoom optical system on the low magnification side and a zoom optical system on the high magnification side is attached to the main body support portion 63. The lens barrel 52 is driven in the vertical direction (Z direction) by a vertical drive mechanism (not shown), and focusing is mainly performed.
[0023]
The inspection object 2 is placed on a table 50 of a stage 51 that can move in the horizontal direction (XY direction). The stage 51 is driven in the horizontal direction by a horizontal drive mechanism (not shown) in order to put the position of the inspection object 2 to be inspected or measured into the field of view of the optical system in the lens barrel 52. The vertical drive mechanism and the horizontal drive mechanism each have a drive mechanism, a guide mechanism, and a position reading mechanism (not shown). These drive mechanisms are controlled by a Z-direction drive signal and an XY-direction drive signal output from the CNC drive unit / position coordinate reading unit 62.
[0024]
In the present embodiment, a single objective lens is used for the two zoom optical systems, and the lens barrel 52 has a single objective lens storage portion 54. The light beam that has passed through the objective lens is branched into a low-magnification side zoom optical system and a high-magnification side zoom optical system by an internal light branching means.
[0025]
Imaging devices 56 and 57 are provided at the upper ends of the low-magnification side and high-magnification side zoom optical systems in the lens barrel 52. Images projected by the low-magnification side and high-magnification side zoom optical systems are photoelectrically converted via the respective imaging devices 56 and 57, and the image signals thereof are connected to the control unit side image processing unit via the cables 58 and 59. 60. The image processing unit 60 switches each image signal according to an instruction from the correction calculation / operation unit 61, and displays an image based on one of the image signals on the monitor 64.
[0026]
The correction calculation / operation unit 61 outputs a control signal according to the operation command from the operation command including the magnification designation from the operator to the image processing unit 60 and the CNC drive unit / position coordinate reading unit 62. Further, the correction calculation / operation unit 61 performs a correction calculation associated with a magnification change in the zoom optical system.
[0027]
In the correction calculation, for example, an arbitrary number of use magnifications corresponding to the inspection object 2 are set in advance, and the size of a reference template having a reference size is measured for each use magnification. Then, the magnification of the zoom optical system is calibrated so that the reference value of the reference template matches the measured value.
[0028]
FIG. 2 is a detailed configuration diagram of the lens barrel 52 according to the first embodiment of this invention. The zoom optical systems 13 and 23 of the present embodiment are configured based on an afocal zoom optical system.
[0029]
The objective lens 1 has a relatively large numerical aperture (NA) and a large angle of view at an appropriate focal length. The light beam from the surface or end surface of the inspection object 2 is converted into parallel light by the objective lens 1. A half mirror 10 is provided behind the objective lens 1 to branch the light beam from the objective lens 1 into an optical system on the high magnification side and an optical system on the low magnification side.
[0030]
The light beam going to the optical system on the high magnification side is reflected by the half mirror 10, further reflected by the mirror 11, and enters the intermediate magnification optical system 16. On the other hand, the light beam going to the optical system on the low magnification side passes through the half mirror 10 and enters the relay lens 26.
[0031]
Since this embodiment uses the objective lens 1 common to the optical system on the high magnification side and the low magnification side, the focal length of the objective lens 1 is relatively long for the optical system on the high magnification side. In addition, the beam diameter of the parallel portion is increased. For this reason, the high magnification side optical system is provided with, for example, a Galileo intermediate magnification optical system 16 including a convex lens 16a and a concave lens 16b. Then, an objective optical system is configured by a synthesis system of the intermediate magnification optical system 16 and the objective lens 1, and a light beam diameter, an optical path length, and the like going to the zoom optical system 13 are appropriately set.
[0032]
Behind the intermediate magnification optical system 16 is provided a zoom optical system 13 on the high magnification side and an imaging lens 14 with an appropriate focal length. The overall magnification on the high magnification side is mainly set by the product of the magnifications of the intermediate magnification optical system 16, the zoom optical system 13, and the imaging lens 14.
[0033]
On the other hand, for the optical system on the low magnification side, the focal length of the common objective lens 1 is relatively short, and the angle of view at a low magnification, that is, a wide field of view is large. For this reason, the relay lens 26 comprised by the convex lens 26a and the convex lens 26b is provided, and a pupil position and an optical path length are set appropriately. Thereby, a light beam having a large angle of view can be guided to the zoom optical system 23 without omission.
[0034]
Behind the relay lens 26, a low-magnification zoom optical system 23 and an imaging lens 24 with an appropriate focal length are provided. The overall magnification on the low magnification side is set mainly by the product of the magnifications of the relay lens 26, the zoom optical system 23, and the imaging lens 24.
[0035]
The high-magnification side optical system and the low-magnification side optical system have zoom optical systems 13 and 23 having the same configuration. In the present embodiment, for example, the zoom optical system 13 on the high magnification side includes variable power lenses 13b and 13c that are movable in the vertical direction between the lenses 13a and 13d. Further, the zoom optical system 23 on the low magnification side includes variable power lenses 23b and 23c that are movable in the vertical direction between the lenses 23a and 23d. The variable power lenses 13 b and 23 b are stored in the same lens chamber 6, and the variable power lenses 13 c and 23 c are stored in the same lens chamber 7.
[0036]
The lens chambers 6 and 7 are driven by the common positioning drive mechanism 9 and the common movement guide mechanism 8 in accordance with the drive signal from the CNC drive unit 62 shown in FIG. For this reason, the zoom optical systems 13 and 23 on the high-magnification side and the low-magnification side are simultaneously driven by the drive signal from the CNC drive unit 62 and controlled to the same magnification.
[0037]
For the movement guide mechanism 8, a mechanism with very little mechanical play and hysteresis, for example, a preload type finite orbit ball race or roller race, is used in order to sufficiently suppress the optical axis shift due to zooming. Also for the positioning drive mechanism 9 of the lens chambers 6 and 7, a preload type drive mechanism and positioning mechanism with very little play and hysteresis are used in order to ensure the reproducibility of the optical image magnification by zooming.
[0038]
The light beams that have passed through the zoom optical systems 13 and 23 on the high-magnification side and the low-magnification side are projected onto the imaging surfaces 15 and 25 such as CCD image sensors of the imaging devices 57 and 56 via the imaging lenses 14 and 24, respectively. Is done. The image signal photoelectrically converted by the CCD image sensor is displayed on the monitor 64 as described above, and the shape and the like of the inspection object 2 are inspected and measured.
[0039]
In the present embodiment, the magnification range of the optical system on the low magnification side is about 0.5 to 5 times, and the magnification range of the optical system on the high magnification side is about 5 to 50 times. This zoom range is configured by zoom optical systems 13 and 23 having a zoom ratio of about 10 by appropriately setting the magnifications of the intermediate magnification optical system 16, the relay lens 26, and the imaging lenses 14 and 24. Accordingly, by appropriately selecting the two optical systems on the low magnification side and the high magnification side, the overall magnification range is 0.5 to 50 times, and a magnification ratio of about 100 is obtained.
[0040]
As another example, by setting the magnification range to partially overlap between the low-magnification side optical system and the high-magnification side optical system, switching between both optical systems at the boundary of the magnification range Can be reduced and operability can be improved. For example, when the frequency of use of a magnification of around 5 times is high, if the optical system on the low magnification side is set to 0.5 to 5 times and the optical system on the high magnification side is set to 4 to 40 times, 5 The magnification before and after the magnification can be set without switching only by the optical system on the high magnification side.
[0041]
In another example, a special use is possible by omitting between the magnification range on the low magnification side and the magnification range on the high magnification side. For example, the low magnification side is 0.5 to 5 times, and the high magnification side is 50 to 500 times. It is set according to each application and type of inspection object. Such setting is performed mainly by appropriately selecting the magnifications of the intermediate magnification optical system 16, the relay lens 26, and the imaging lenses 14 and 24.
[0042]
FIG. 3 is a detailed configuration diagram of the lens barrel 52 according to the second embodiment of this invention. In the present embodiment, the light beam that has passed through the intermediate magnification optical system 16 or the relay lens 26 is imaged by the common zoom optical system 13 and the imaging lens 14. Description of the parts common to the first embodiment is omitted, and different parts will be described.
[0043]
The light beam that has passed through the objective lens 1 is branched by the half mirror 10 into the high magnification side intermediate magnification optical system 16 and the low magnification side relay lens 26. However, in this embodiment, a mirror 16c is placed in the intermediate magnification optical system 16 to reflect the light beam in the vertical direction. A mirror 26c is placed in the relay lens 26 to reflect the light beam in the horizontal direction.
[0044]
The light beam that has passed through the intermediate magnification optical system 16 or the relay lens 26 is transmitted or reflected by the half mirror 70 and enters the zoom optical system 13. However, for switching between the high magnification side and the low magnification side, for example, a shutter mechanism is provided on the optical path of the intermediate magnification optical system 16 and the relay lens 26. Then, the shutter mechanism is opened and closed by a selection means (not shown), and one of the light beams branched by the half mirror 10 is alternatively guided to the zoom optical system 13 via the half mirror 70.
[0045]
In the present embodiment, the half mirrors 10 and 70 are used to split and synthesize the light beam. However, in order to suppress the loss of the light amount, a total reflection mirror that can be moved in the horizontal direction at the position of the half mirrors 10 and 70 is used. It can also be used. In this case, when the total reflection mirror is inserted into the light beam from the objective lens 1, the light beam enters the intermediate magnification optical system 16 and the high magnification side is selected. On the other hand, when the total reflection mirror moves out of the light beam, the light beam enters the relay lens 26 and the low magnification side is selected.
[0046]
FIG. 4 is a detailed configuration diagram of a lens barrel 52 according to the third embodiment of the present invention. In the present embodiment, a mechanism for exclusively inserting / removing both the intermediate magnification optical system 16 and the relay lens 26 is used in order to minimize the light loss.
[0047]
In the lens barrel 52, one of the intermediate magnification optical system 16 and the relay lens 26 is configured to be able to be inserted and removed in the direction of the arrow 71. Then, one is inserted into the light beam by a selection means (not shown), and the high magnification side or the low magnification side is selected. However, since the mechanical insertion / removal mechanism generates an error such as an optical axis shift according to the positioning performance, it is suitable for an application that does not require highly accurate positioning in image processing.
[0048]
【The invention's effect】
As described above, according to the present invention, a zoom magnification ratio of about 100 can be obtained with a single objective lens. In addition, a low magnification is obtained for the initial positioning of inspection or measurement, and a high magnification is obtained for high-resolution detection, so that the workability of inspection and measurement is improved with high accuracy.
[0049]
Further, since the objective lens, the illumination system, the drive mechanism, and the like are common, the configuration can be simplified. Furthermore, since it can be operated without a difference from a single zoom optical system, operability is good.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an image inspection / measurement apparatus according to an embodiment of the present invention.
FIG. 2 is a detailed configuration diagram of a lens barrel according to the first embodiment of this invention.
FIG. 3 is a detailed configuration diagram of a lens barrel according to a second embodiment of the present invention.
FIG. 4 is a detailed configuration diagram of a lens barrel according to a third embodiment of the present invention.
FIG. 5 is a general configuration diagram of a lens barrel using a zoom optical system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Objective lens 2 Inspected object 10 Half mirror 13 Zoom optical system 14 and 24 on the high magnification side Imaging lens 15 and 25 Imaging surface 16 Intermediate magnification optical system 23 Zoom optical system 26 on the low magnification side Relay lens

Claims (4)

In an image inspection / measurement apparatus that inspects or measures an inspection object using an image signal of the inspection object imaged by an imaging device via an optical system,
The optical system includes an objective lens,
Light branching means for branching the light beam from the objective lens;
A first optical system including a first zoom optical system that changes the magnification of one of the light beams branched by the light branching unit on the high magnification side;
Have a second optical system including a second zoom optical system for zooming the other light beam branched by said optical branching means at a low magnification side,
The image inspection / measurement apparatus, wherein the first zoom optical system and the second zoom optical system are driven by a common drive mechanism . In claim 1,
The first optical system includes an intermediate magnification optical system that adds a predetermined magnification to the light beam from the light branching unit and guides the light beam to the first zoom optical system. . In claim 1,
The image inspection / measurement apparatus , wherein the second optical system includes a relay lens that adjusts an angle of view of a light beam from the light branching unit and guides the light beam to the second zoom optical system . In an image inspection / measurement apparatus that inspects or measures an inspection object using an image signal of the inspection object imaged by an imaging device via an optical system,
The optical system includes an objective lens,
An intermediate magnification optical system for adding a predetermined magnification to the light beam from the objective lens;
A relay lens for adjusting the angle of view of the light beam from the objective lens;
Selecting means for selecting the intermediate magnification optical system and the relay lens;
An image inspection / measurement apparatus comprising: an intermediate magnification optical system selected by the selection means; or a zoom optical system that varies a light flux from a relay lens.

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