JP7252019B2 - Image measuring device - Google Patents

Description

The present invention relates to an image measuring device.

The image measuring apparatus captures an image of a work (object to be inspected) to generate a work image, and measures the dimensions of the work based on the work image. According to Patent Document 1, an image measuring apparatus (image dimension measuring apparatus) equipped with a high-magnification camera in addition to a low-magnification camera is proposed.

Japanese Patent No. 5679560

By the way, it would be convenient if the height of a workpiece placed on a stage could be measured in the image measuring apparatus. For example, the height of the workpiece is obtained from the amount of drive in the height direction of the stage when a probe with a sphere attached to the tip of the support rod is brought into contact with the workpiece and the amount of drive when the probe is brought into contact with the stage. can be considered. However, in this case, a probe becomes essential.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to measure the height of a work by a simpler method.

The present invention, for example,
a mounting table having a light-transmitting plate on which a workpiece is placed on a first surface of the light-transmitting plate;
a transmissive illumination unit provided below the translucent plate for irradiating transmissive illumination light onto the workpiece placed on the translucent plate;
an epi-illumination unit provided above the translucent plate for irradiating epi-illumination light onto the workpiece placed on the translucent plate;
an imaging unit provided above the mounting table;
an adjustment unit that adjusts the focus of the imaging unit;
height of the work with respect to the light-transmitting plate based on the control parameter of the adjusting unit when the work is in focus and the control parameter of the adjusting unit when the light-transmitting plate is in focus; A processor that seeks
further comprising a memory storing imaging conditions applied when the imaging unit is focused on the first surface of the transparent plate;
When the imaging unit is focused on the first surface of the translucent plate, the processor controls the imaging unit, the transmitted illumination unit, and the epi-illumination unit according to the imaging conditions, and controls the imaging unit. Provided is an image measuring device that dynamically controls imaging conditions when focusing on a work placed on the transparent plate .

According to the present invention, it becomes possible to measure the height of a work by a simpler method.

Diagram showing the outline of the image measuring device Cross section of measuring unit Diagram explaining the controller Flowchart showing height measurement Diagram explaining the user interface Diagram explaining the user interface Diagram explaining the user interface Diagram explaining the user interface Diagram explaining the user interface Diagram showing the relationship between processing and measurement error Enlarged view showing unevenness provided on the surface of the transparent plate The figure which shows the profile of the unevenness given to the surface of a translucent plate. A diagram explaining the pitch of the unevenness

Embodiments are described in detail below with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the features described in the embodiments may be combined arbitrarily. Identical or similar configurations are given the same reference numerals, and duplicate descriptions are omitted.

<Image measuring device 1>
FIG. 1 is a perspective view showing one configuration example of the image measuring apparatus 1. As shown in FIG. The image measuring apparatus 1 is an image measuring apparatus that captures an image of a workpiece, generates a workpiece image, and measures dimensions of the workpiece within the workpiece image. In FIG. 1, the image measuring apparatus 1 has a measuring unit 10, a control unit 20, a keyboard 31 and a pointing device 32. As shown in FIG. A workpiece is an object whose shape and dimensions are measured by the image measuring apparatus 1 .

The measurement unit 10 has a display device 11 , a movable stage 12 , an XY adjustment knob (not shown), a Z adjustment knob 14 , a power switch 15 and an execution button 16 . The measurement unit 10 irradiates illumination light onto a work placed on a movable stage 12 and receives light transmitted through or reflected from the work to generate a work image. The work is placed on the transparent plate 13 of the movable stage 12 . The measurement unit 10 displays the work image on the display screen 18 of the display device 11 .

The display device 11 is a display device that displays workpiece images, measurement results, setting UI (user interface), etc. on a display screen 18 . The user operates the keyboard 31 and pointing device 32 while looking at the workpiece image displayed on the display device 11 to set characteristic points for pattern search, measurement points for dimension measurement, and the like. The movable stage 12 is a mounting table for mounting a work. The light-transmitting plate 13 is a region made of translucent glass. The movable stage 12 moves in the Z-axis direction parallel to the imaging axis of the camera, and in the X-axis and Y-axis directions perpendicular to the imaging axis.

The XY adjustment knob adjusts the relative position of the movable stage 12 with respect to the camera (the position in the X-axis direction and the position in the Y-axis direction) by moving the movable stage 12 in the X-axis direction or the Y-axis direction. The Z adjustment knob 14 adjusts the relative position (position in the Z-axis direction) of the movable stage 12 with respect to the camera by moving the movable stage 12 in the Z-axis direction. The power switch 15 is an operation unit for switching the main power of the measurement unit 10 and the control unit 20 between an on state and an off state. The execution button 16 is an operation unit for starting dimension measurement.

The control unit 20 is a controller that controls imaging and screen display by the measurement unit 10, analyzes the workpiece image, and measures the dimensions of the workpiece. The control unit 20 is connected to a keyboard 31 and pointing device 32 and receives user input through the keyboard 31 and pointing device 32 . The keyboard 31 and pointing device 32 form an operating section 30 . The control unit 20 activates the measurement unit 10 when the power switch 15 is switched on. When the execution button 16 is operated, the control unit 20 controls the measurement unit 10 according to setting data prepared in advance, searches for a work within the transparent plate 13, and measures the dimensions of the work.

<Measurement unit 10>
FIG. 2 is a cross-sectional view schematically showing a configuration example of the measurement unit 10. As shown in FIG. Here, a cut plane when the measuring unit 10 cuts along a vertical plane (YZ plane) parallel to the imaging axis is shown. The measurement unit 10 has a display device 11 , a movable stage 12 , a housing 100 , a stage driving section 101 , a lens barrel section 102 , a low magnification camera 110 , a high magnification camera 120 , coaxial epi-illumination 130 and transmissive illumination 150 . . Low magnification camera 110 and high magnification camera 120 are used for dimensional measurements and may be referred to as measurement cameras.

The lens barrel section 102 , the low-magnification camera 110 , the high-magnification camera 120 , the coaxial epi-illumination 130 and the transmissive illumination 150 are arranged inside the housing 100 . The stage drive unit 101Z moves the camera head 103 in the Z-axis direction with respect to the movable stage 12 to adjust the distance between the low-magnification camera 110, the high-magnification camera 120, and the movable stage 12. FIG. Note that the stage driving section 101Z may move the movable stage 12 in the Z-axis direction. The stage drive unit 101Z may move the camera head 103 in order to focus the low-magnification camera 110 and the high-magnification camera 120 on a work or the like. The stage drive unit 101XY moves the movable stage 12 in the X-axis direction and the Y-axis direction.

The low-magnification camera 110 is an imaging device with a low imaging magnification compared to the high-magnification camera 120 . The low-magnification camera 110 has an imaging device 111 , an imaging lens 112 , an aperture plate 113 and a light receiving lens 114 . The imaging lens 112, diaphragm plate 113 and light receiving lens 114 form a low-magnification optical system. The imaging device 111 receives illumination light and generates a workpiece image. The imaging device 111 is arranged with its light receiving surface facing downward. The imaging lens 112 is an optical member that forms an image of illumination light on the imaging device 111 . A diaphragm plate 113 is an optical diaphragm that controls the amount of transmitted illumination light and the depth of field, and is arranged between the imaging lens 112 and the light receiving lens 114 . The light-receiving lens 114 is an optical member that collects the illumination light from the work, and is arranged so as to face the movable stage 12 . Imaging lens 112, aperture plate 113, and light receiving lens 114 are arranged around a central axis extending in the vertical direction.

The high-magnification camera 120 is an imaging device with a higher imaging magnification than the low-magnification camera 110 . The high magnification camera 120 has an imaging device 121 , an imaging lens 122 , an aperture plate 123 , a half mirror 124 and a light receiving lens 114 . The imaging lens 122, diaphragm plate 123, half mirror 124 and light receiving lens 114 form a high magnification optical system. The imaging device 121 receives illumination light and generates a workpiece image. The imaging element 121 is arranged with its light receiving surface directed in the horizontal direction. That is, the light receiving surface and the horizontal direction are orthogonal. The imaging lens 122 is an optical member that forms an image of illumination light on the imaging device 121 . A diaphragm plate 123 is an optical diaphragm that limits the amount of transmitted illumination light, and is arranged between the imaging lens 122 and the half mirror 124 . The light receiving lens 114 is shared by the low-magnification camera 110 and the high-magnification camera 120 . The illumination light transmitted through the light receiving lens 114 is bent in the horizontal direction by the half mirror 124 and forms an image on the imaging device 121 via the aperture plate 123 and the imaging lens 122 .

Image sensors such as CCDs (Charge Coupled Devices) and CMOSs (Complementary Metal Oxide Semiconductors) are used as the imaging devices 111 and 121, for example. As the light-receiving lens 114, a telecentric lens is used which has the property of not changing the size of the image of the work even if the distance between the light-receiving lens 114 and the work changes. That is, the low-magnification optical system and the high-magnification optical system each have telecentricity. The workpiece distortion in the workpiece image acquired by the telecentric optical system is very small compared to the workpiece distortion in the workpiece image acquired by the non-telecentric optical system. Therefore, the workpiece can be measured with high accuracy.

The coaxial epi-illumination 130 is an illumination device that irradiates the work on the movable stage 12 with illumination light from above. Instead of the coaxial epi-illumination 130, epi-illumination such as ring illumination may be employed. The optical axis of the light emitted from the coaxial epi-illumination 130 coincides with the imaging axis. The coaxial epi-illumination 130 has a light source 131 that is arranged to output illumination light in the horizontal direction, and a half mirror 132 that bends downward the illumination light emitted from the light source 131 . Illumination light from the coaxial epi-illumination 130 is advantageous in obtaining irregularities and patterns on the work surface.

Imaging lenses 112 , 122 , aperture plates 113 , 123 , half mirrors 124 , 132 , and light receiving lens 114 are arranged inside lens barrel 102 .

The transmitted illumination 150 is an illumination device that illuminates the workpiece on the movable stage 12 with illumination light from below. Transmitted illumination 150 is composed of light source 151 , mirror 152 and condenser lens 153 . The light source 151 is arranged to output illumination light in the horizontal direction. Illumination light emitted from the light source 151 is reflected by the mirror 152 and condensed by the condensing lens 153 . The illumination light passes through the movable stage 12 and irradiates the workpiece. A part of the illumination light is blocked by the work, and another part of the illumination light enters the light receiving lens 114 . The illumination light of the transmitted illumination 150 is advantageous when acquiring the outer edge of the workpiece.

As each light source of the coaxial epi-illumination 130 and the transmissive illumination 150, an LED (light-emitting diode) or a halogen lamp is used.

A bird's-eye view camera 17 is an imaging device used to acquire a bird's-eye view image of the movable stage 12 . The bird's-eye view camera 17 has an optical system such as an imaging lens and an imaging device such as a CMOS image sensor. A bird's-eye view image is an image that includes almost the entire movable stage 12 . The imaging field of view of the overhead camera 17 is wider than the imaging fields of the low-magnification camera 110 and the high-magnification camera 120 . Therefore, the bird's-eye view camera 17 is suitable for acquiring images of a wider range than the low-magnification camera 110 and the high-magnification camera 120 . On the other hand, the telecentricity of the overhead camera 17 is low compared to the telecentricity of the low-magnification camera 110 and the high-magnification camera 120 . Therefore, the overhead camera 17 may be called a non-telecentric camera. Since the shape of the workpiece is distorted in the workpiece image acquired by the bird's-eye camera 17, the bird's-eye camera 17 is not suitable for workpiece measurement compared to the low-magnification camera 110 and the high-magnification camera 120. FIG. The field of view of the optical system is circular, and the object within the field of view forms an image circle on the imaging device. On the other hand, the range that can be imaged by the imaging element is a rectangle. That is, the imaging area is a partial rectangular area within the image circle. Here, a rectangular area on the movable stage 12 corresponding to the imaging area of the imaging element is called an imaging field of view.

<Principle of height measurement>
The control unit 20 adjusts the height of the camera head 103 with respect to the movable stage 12 to focus (autofocus) the measurement cameras such as the low-magnification camera 110 and the high-magnification camera 120 . The stage drive unit 101Z grasps the adjustment amount of the height of the camera head 103 with respect to the movable stage 12. FIG. Therefore, the control unit 20 can measure the height of the workpiece W based on the height adjustment amount. More specifically, the control unit 20 is based on the difference between the adjustment amount when the measurement camera is focused on the surface of the translucent plate 13 and the adjustment amount when the measurement camera is focused on the workpiece W. Calculate the height of the workpiece W. Since the work W is placed on the light-transmitting plate 13, the light-transmitting plate 13 serves as a reference for height. The adjustment amount may be called an AF drive amount.

<Controller>
FIG. 3 is a diagram for explaining the functions of the controller 60 mounted on the control unit 20. As shown in FIG. The controller 60 is composed of a processor (eg, CPU, etc.) and controls the measurement unit 10 . CPU is an abbreviation for central processing unit. Some or all of the functions of controller 60 may be realized by hardware such as ASIC and FPGA. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array. The illumination controller 81 is mounted on the control unit 20 or the measurement unit 10 and controls the illumination unit 84 (the coaxial epi-illumination 130 and the transmitted illumination 150) according to control signals from the controller 60. FIG. The imaging control section 82 is mounted on the control unit 20 or the measurement unit 10, and controls the camera unit 85 (the low-magnification camera 110, the high-magnification camera 120, and the overhead cameras 17R and 17L) according to control signals from the controller 60. The storage device 70 has a memory, a hard disk drive, and the like, and stores setting data, low-magnification images, overhead images, and the like. The controller 60 measures the dimensions of the workpiece W using the workpiece image acquired by the camera unit 85, and determines whether the measurement result satisfies the non-defective product conditions (eg, tolerances, etc.). As described above, the controller 60 has a dimension measuring function and a non-defective product determining function.

The UI unit 61 of the controller 60 creates a user interface, displays it on the display device 11, and receives user input from the keyboard 31 or the like. The AF unit 62 performs autofocus for the measurement camera by causing the measurement camera (low-magnification camera 110 or high-magnification camera 120) to acquire an image. As is well known, the AF section 62 drives the Z motor M1 so that the contrast of the image acquired by the measurement camera is maximized. The height measurement unit 63 acquires the drive amount of the Z motor M1 from the AF unit 62, and measures the height of the workpiece W based on the drive amount. The drive amount of the Z motor M1 may be the number of drive pulses supplied to the Z motor M1, the number of rotations of the Z motor M1 obtained by an encoder (not shown), or the like. The storage device 70 may have a function or conversion table that converts the drive amount to height. The height measurement unit 63 may convert the drive amount into height using a function or a conversion table. The height measurement unit 63 may measure the height of a part of the surface of the work W set by the UI unit 61 .

The stage driving section 101Z has a Z motor M1 that drives at least one of the movable stage 12 and the camera head 103. FIG. By moving at least one of the movable stage 12 and the camera head 103 in the Z direction with the Z motor M1, the distance in the Z direction between the movable stage 12 and the camera head 103 is adjusted. The stage driving unit 101XY includes an X motor M2 that moves at least one of the movable stage 12 and the camera head 103 in the X direction, and a Y motor M3 that moves at least one of the movable stage 12 and the camera head 103 in the Y direction. and The storage device 70 includes memories for storing various setting data, bird's-eye view images, low-magnification images, high-magnification images, connected images, and the like. The low magnification image, high magnification image and concatenated image may be referred to as work images. A concatenated image is an image created by concatenating a plurality of low-magnification images or a plurality of high-magnification images.

The display control unit 83 displays a user interface that displays an overhead image on the display device 11 according to instructions from the controller 60, displays various images, and displays measurement results (inspection results).

<Flowchart and UI>
FIG. 4 is a flow chart showing height measurement. 5-9 are diagrams showing a user interface 160 relating to height measurement. Here, it is assumed that the workpiece image is acquired by the low-magnification camera 110 and the high-magnification camera 120 is used for height measurement, but this is only an example. A low magnification camera 110 may be used for height measurement. Also, the workpiece image may be acquired by the overhead camera 17 . Also, basically, the workpiece image W is acquired by epi-illumination.

In S<b>401 , the controller 60 (UI unit 61 ) displays the user interface 160 on the display device 11 according to the instruction input from the operation unit 30 . The user interface 160 shown in FIG. 5 has an image display area 168 that displays the workpiece image acquired by the measurement camera.

In S<b>402 , the controller 60 (UI unit 61 ) accepts designation of the measurement point 162 . For example, the UI unit 61 controls the stage driving unit 101XY according to the operation of an XY adjustment knob (not shown) to move the movable stage 12 in the X direction and the Y direction. In addition, the UI unit 61 sets the measurement points 162 on the work W according to the operation of the pointer 161 through the operation unit 30 .

In S<b>403 , the controller 60 (AF section 62 ) performs autofocus on the measurement point 162 . The AF unit 62 captures an image of the measurement point 162 with the high-magnification camera 120, obtains a focus evaluation value based on the acquired high-magnification image, and drives the Z motor M1 so that the focus evaluation value becomes maximum. A focus evaluation value may be, for example, a contrast value. FIG. 6 shows a state in which the measurement point 162 is in focus. In order to indicate that the measurement point 162 is in focus, the UI unit 61 may change the shape of the frame indicating the measurement point 162 from a square to a circle.

In S404, the controller 60 (height measurement unit 63) acquires from the AF unit 62 the AF driving amount of the Z motor M1 when the focus evaluation value becomes maximum. For example, the AF drive amount may be the drive amount of Z motor M1 with respect to the home position of movable stage 12 .

In S<b>405 , the controller 60 (AF unit 62 ) performs autofocus on the translucent plate 13 of the movable stage 12 . For example, as shown in FIG. 7, the UI section 61 may have an instruction section 163 for instructing height measurement for the transparent plate 13 (stage glass surface). In this example, the indicator 163 is implemented by a control object (eg, check box). The UI unit 61 sets the second measurement point 164 on the transparent plate 13 when the pointer 161 gives a check to the instruction unit 163 . For example, the user may operate the XY adjustment knob so that the measurement point 164 is positioned on the translucent plate 13 . Alternatively, the user may adjust the position of the measurement point 164 with the pointer 161 so that the measurement point 164 is positioned on the transparent plate 13 . Alternatively, as shown in FIG. 8, the UI unit 61 turns on the transmitted illumination of the workpiece W to acquire a transmitted illumination image, specifies the position of the transparent plate 13 based on the transmitted illumination image, and determines the specified position. The measurement point 164 may be arranged at the position of the translucent plate 13 . As shown in FIG. 8, in the transmitted illumination image, the portion where the work W is present is black (shadow), and the portion where the work W is not present is bright. The UI unit 61 may specify the position of the transparent plate 13 by using such a difference in brightness. The AF unit 62 captures an image of the measurement point 164 with the high-magnification camera 120, obtains a focus evaluation value based on the acquired high-magnification image, and drives the Z motor M1 so that the focus evaluation value becomes maximum. In order to indicate that the measurement point 164 is in focus, the UI unit 61 may change the shape of the frame indicating the measurement point 164 from a square to a circle.

In S406, the controller 60 (height measurement unit 63) acquires from the AF unit 62 the AF drive amount of the Z motor M1 when the focus evaluation value for the measurement point 164 is maximized. This AF drive amount may also be the drive amount of the Z motor M1 with respect to the home position of the movable stage 12 .

In S407, the controller 60 (height measurement unit 63) obtains the difference between the AF drive amount for the measurement point 162 (workpiece W) and the AF drive amount for the measurement point 164 (translucent plate 13).

In S408, the controller 60 (height measurement unit 63) converts the difference into height. A function or table stored in the storage device 70 may be used for conversion of .

In S409, the controller 60 (height measurement unit 63) displays the height, which is the measurement result, on the display device 11. FIG. As shown in FIG. 9, the user interface 160 may display the measurement result 165 superimposed on the image of the work W, or may display the measurement result 165 at a position separated from the image of the work W. In addition, when the pass/fail determination is performed using the measurement result, the user interface 160 may have a pass/fail threshold setting unit 166 . The controller 60 may determine whether the workpiece W is a non-defective product (accepted product) by comparing the pass/fail threshold value (tolerance) set by the setting unit 166 with the measurement result.

<Ingenuity to make it easier to focus on the translucent plate>
The translucent plate 13 is required to have high translucency. This is because a transmission plate with low translucency that causes black dots to appear in the image causes erroneous detection of the edge of the workpiece. On the other hand, when the translucent property of the translucent plate 13 becomes high, it becomes difficult for the AF section 62 to focus on the translucent plate 13 . Therefore, it is required to solve this contradictory problem. The inventors came up with the idea of facilitating focusing on the light-transmitting plate 13 while maintaining high light-transmitting properties by processing the surface of the light-transmitting plate 13 made of glass. Etching, dry blasting, and wet blasting were adopted as processing methods, and evaluations were carried out for these. Etching, dry blasting, and wet blasting can increase the degree of scattering (diffusivity) of light at the surface of the glass. As evaluation methods, evaluation of the measurement error of the pin gauge and evaluation of the shape of the surface profile of the transparent plate 13 were adopted.

FIG. 10 shows evaluation results of pin gauge measurement errors. The horizontal axis indicates the nominal diameter of the pin gauge. The vertical axis indicates the measurement error. It was found that the measurement error of the wet-blasted light-transmitting plate 13 is smaller than the measurement error of the etched light-transmitting plate 13 and the dry-blasting light-transmitting plate 13 .

Such a light-transmitting plate 13 does not easily provide contrast to an image captured by a measurement camera using transmitted illumination. That is, the translucent plate 13 hardly affects normal imaging and measurement. The translucent plate 13 uses epi-illumination to provide contrast to the image captured by the measurement camera, which facilitates focusing. Transmitted illumination is used when measuring the outer shape of the workpiece. Therefore, there is no problem even if the image of the stage glass of the translucent plate 13 picked up by epi-illumination has contrast.

FIG. 11 is an enlarged view of the surface of the transparent plate 13 that has been wet-blasted. According to this, it can be seen that the surface of the transparent plate 13 has fine irregularities. FIG. 12 shows an example of an uneven profile. The horizontal axis indicates the distance in the X direction, and the vertical axis indicates the height of the unevenness. Here, illustration of the profile of the light-transmitting plate 13 that has been etched and the profile of the light-transmitting plate 13 that has been dry-blasted is omitted. In these profiles, the height of the unevenness exceeding 2 [um] was found here and there, which was much larger than the height of the unevenness of the wet-blasted light-transmitting plate 13 . A different tendency was observed for the pitch of the unevenness. It is more advantageous for focusing when the unevenness of the surface changes sharply than when the unevenness of the surface changes gently. If the difference between the depth of the concave portion and the height of the convex portion is too large, the unevenness will appear as a black and white pattern in the transmitted illumination image. Therefore, the smaller the difference, the better.

FIG. 13 shows the pitch and depth conditions of the unevenness derived from the experimental results. It was found that the depth Rz should be 2 [um]. Here, the distance B1 from edge to edge of one recess and the distance B2 from the edge of a recess to the edge of the adjacent recess were adopted as parameters related to the pitch. The unit of the distances B1 and B2 is the size of one pixel in the high-magnification image. This is because the influence of the unevenness pitch on AF depends on the resolution of the high-magnification camera 120 . It was found that the distance B1 should be 2 pixels or more and 20 pixels or less. Also, it was found that the distance B2 should be 5 pixels or more. As a result, wet blasting was favored over etching and dry blasting to create features that meet these conditions.

By increasing the diaphragm amounts of diaphragm plate 113 and diaphragm plate 123, a reflected image with enhanced contrast can be obtained. That is, by narrowing down the diaphragm plate 113 and the diaphragm plate 123 (increasing the diaphragm amount), an epi-illumination image with increased contrast is acquired so that the fine pattern pattern processed on the transparent plate 13 is emphasized. be.

When generating the control parameters for the adjustment unit, the imaging unit is focused on the first surface of the transparent plate. At this time, the throttle amount for adjustment is also determined. In order to obtain a contrast reflected light image of a fine pattern processed on a transparent plate, it is important to appropriately set the diaphragm amount of the light receiving diaphragm such as diaphragm plate 113 and diaphragm plate 123 . This throttle amount may be determined in advance. On the other hand, during normal measurement (when measuring a workpiece), the focus is adjusted to the surface of the workpiece. Therefore, the amount of diaphragm at this time is controlled by the amount of received light in the imaging unit, exposure conditions, and the like.

<Summary>
The movable stage 12 has a light-transmitting plate 13 and functions as a mounting table on which the workpiece W is placed on the first surface of the light-transmitting plate 13 . The first surface is the surface on which the workpiece W is placed (the surface in contact with the workpiece W). The transmitted illumination 150 is provided below the transparent plate and functions as a transmitted illumination section that irradiates the workpiece placed on the transparent plate with the transmitted illumination light. The coaxial epi-illumination 130, ring illumination, etc. are provided above the translucent plate and function as an epi-illumination unit that irradiates the work placed on the translucent plate with epi-illumination light. A measurement camera such as the low-magnification camera 110 and the high-magnification camera 120 functions as an imaging unit provided above the mounting table. The AF section 62, the stage drive section 101Z, and the Z motor M1 function as an adjustment section that adjusts the focus of the imaging section. The controller 60 and the height measurement unit 63 are based on the control parameters of the adjustment unit when the work is in focus (eg, AF drive amount) and the control parameters of the adjustment unit when the light-transmissive plate is in focus. , is an example of a processor that obtains the height of the workpiece with reference to the transparent plate. As described above, according to the present embodiment, the height of the workpiece can be measured more easily because the probe is not required.

As described with reference to FIGS. 10 to 13, the light-transmitting plate 13 may be processed to facilitate focusing of the imaging unit on the first surface of the light-transmitting plate. For example, the first surface of the translucent plate may be processed so as to transmit the transmitted illumination light from the transmissive illumination section and scatter the epi-illumination light from the epi-illumination section. As a result, the work W can be measured using transmitted illumination, and focusing on the translucent plate 13 will be easier. For example, the first surface of the light-transmitting plate 13 is more likely to scatter light when it is irradiated with epi-illumination light from the epi-illumination unit than when it is irradiated with transmitted illumination light from the transmissive illumination unit. It is processed to be

For example, the surface roughness of the first surface of the light-transmitting plate may be rougher than the surface roughness of the second surface of the light-transmitting plate. This means that the first surface is roughened, but the second surface may not be roughened. For example, the first surface of the translucent plate may be processed by wet blasting.

The pitch (distance B1) of the unevenness provided on the first surface of the transparent plate may be 2 pixels or more and 20 pixels or less. The height difference of the unevenness provided on the first surface of the light-transmitting plate may be, for example, greater than 0 and 2 [um] or less.

The storage device 70 may function as a memory that stores in advance imaging conditions that are applied when the imaging unit is focused on the first surface of the translucent plate. The processor may control the imaging section, the transmission illumination section, and the epi-illumination section according to the imaging conditions read from the memory when the imaging section is focused on the first surface of the translucent plate. That is, the imaging condition applied when the imaging unit is focused on the first surface of the transparent plate may be fixed. On the other hand, the processor may dynamically control the imaging conditions when focusing the imaging unit on the work placed on the translucent plate. The imaging condition may include turning off the transmitted illumination unit and turning on the epi-illumination unit. For example, the use of transmitted illumination for the measurement point 164 and the use of epi-illumination for the measurement point 162 are applied as imaging conditions. The imaging conditions may also include camera selection information indicating which measurement camera to use, the low-magnification camera 110 or the high-magnification camera 120 .

The invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the invention.

Claims (9)

a mounting table having a light-transmitting plate on which a workpiece is placed on a first surface of the light-transmitting plate;
a transmissive illumination unit provided below the translucent plate for irradiating transmissive illumination light onto the workpiece placed on the translucent plate;
an epi-illumination unit provided above the translucent plate for irradiating epi-illumination light onto the workpiece placed on the translucent plate;
an imaging unit provided above the mounting table;
an adjustment unit that adjusts the focus of the imaging unit;
height of the work with respect to the light-transmitting plate based on the control parameter of the adjusting unit when the work is in focus and the control parameter of the adjusting unit when the light-transmitting plate is in focus; A processor that seeks
further comprising a memory storing imaging conditions applied when the imaging unit is focused on the first surface of the transparent plate;
When the imaging unit is focused on the first surface of the translucent plate, the processor controls the imaging unit, the transmitted illumination unit, and the epi-illumination unit according to the imaging conditions, and controls the imaging unit. An image measuring device that dynamically controls imaging conditions when focusing on a work placed on the transparent plate . 2. The image measuring apparatus according to claim 1, wherein said light-transmitting plate is processed to facilitate focusing of said imaging unit on said first surface of said light-transmitting plate. a mounting table having a light-transmitting plate on which a workpiece is placed on a first surface of the light-transmitting plate;
a transmissive illumination unit provided below the translucent plate for irradiating transmissive illumination light onto the workpiece placed on the translucent plate;
an epi-illumination unit provided above the translucent plate for irradiating epi-illumination light onto the workpiece placed on the translucent plate;
an imaging unit provided above the mounting table;
an adjustment unit that adjusts the focus of the imaging unit;
height of the work with respect to the light-transmitting plate based on the control parameter of the adjusting unit when the work is in focus and the control parameter of the adjusting unit when the light-transmitting plate is in focus; and a processor that requires
The image measuring apparatus according to claim 1, wherein the light-transmitting plate is processed so that the imaging unit can be easily focused on the first surface of the light-transmitting plate. 4. The first surface of the translucent plate is processed so as to transmit the transmitted illumination light from the transmitted illumination section and to scatter the epi-illumination light from the epi-illumination section . The image measuring device according to . The first surface of the translucent plate emits more light when irradiated with the epi-illumination light from the epi-illumination unit than when irradiated with the transmitted illumination light from the trans-illumination unit. The image measuring device according to any one of claims 2 to 4 , which is processed so as to be easily scattered. The image measuring device according to any one of claims 2 to 5 , wherein the surface roughness of the first surface of the light-transmitting plate is rougher than the surface roughness of the second surface of the light-transmitting plate. The image measuring device according to any one of claims 2 to 6 , wherein said first surface of said transparent plate is processed by wet blasting. The image measuring apparatus according to any one of claims 2 to 7 , wherein the pitch of the unevenness provided on the first surface of the light-transmitting plate is 2 pixels or more and 20 pixels or less. 3. The image measuring apparatus according to claim 1 , wherein said imaging condition includes turning off said transmission illumination unit and turning on said epi-illumination unit.

Images