WO2013051147A1 - Image acquisition apparatus adjustment method, image acquisition apparatus, and image acquisition apparatus manufacturing method - Google Patents

Abstract

The purpose of the present invention is to accurately calibrate positional deviations of imaging devices on an image acquisition apparatus having a plurality of imaging devices. An image acquisition apparatus adjustment method for achieving the above-described purpose as an aspect of the present invention is a method for adjusting an image acquisition apparatus which uses a plurality of imaging devices to capture images of different regions of a subject projected by an imaging optical system, said method being characterized by comprising a first step for capturing an image of a test sample with the image acquisition apparatus, a second step for acquiring calibration values for positions of the plurality of imaging devices on the basis of a reference image and the captured image of the test sample, and a third step for calibrating the positions of the plurality of imaging devices on the basis of the calibration values.

Description

Method of adjusting image acquisition device, image acquisition device, and method of manufacturing image acquisition device

The present invention relates to the adjustment of an image acquisition device having a plurality of imaging elements.

2. Description of the Related Art In recent years, in the field of pathology and the like, an image acquisition apparatus capable of imaging a subject (preparet) including a specimen to acquire an image and performing digital processing has attracted attention.

According to Patent Document 1, in a microscope in which a specimen is enlarged and imaged by an imaging optical system (objective lens) and imaged using a plurality of imaging elements, an image of a large specimen which does not fit within the field of view of the imaging optical system can be acquired. The system configuration is disclosed. Here, an image of a large area of a large sample is acquired by moving either the sample or the imaging element in the horizontal direction, imaging a plurality of times, and performing stitching processing to connect acquired images.

Further, Patent Document 2 discloses a method of adjusting the position (the position in the optical axis direction or the inclination with respect to the optical axis) of the imaging element in the imaging device. Specifically, after temporarily arranging the imaging optical system and the imaging device, one of them is moved in the optical axis direction, and the test samples arranged on the optical axis are captured and acquired at a plurality of predetermined positions. The adjustment is performed by calculating the optimum position of the position of the imaging element based on the imaging information.

JP, 2009-3016, A JP, 2005-136743, A

In the sample to be observed, there may be a case where the surface shape has a waviness, but according to the image acquisition device having a plurality of image sensors, the respective image sensors are individually driven according to the waviness. The whole area can be well focused. However, if installation errors during assembly of the image acquisition apparatus or thermal expansion of the structural material due to temperature changes in the surrounding environment occur, the positions of the respective imaging elements fluctuate with respect to the design values, as described above. Even if the focusing operation is performed by driving each imaging element, blurring occurs in the acquired image.

Therefore, it is necessary to calibrate the positional deviation of each imaging device, but applying the adjustment method for a single imaging device as disclosed in Patent Document 2 to each of a plurality of imaging devices. It is difficult. In addition, particularly in an image acquisition apparatus having a plurality of imaging elements, positional deviations occur in the rotational direction of the imaging elements in the imaging plane, which makes it difficult to perform stitching processing of acquired images corresponding to each of the positional deviations. Will occur. However, Patent Document 2 does not disclose a calibration method for positional deviation of a plurality of imaging devices in consideration of such a stitching process.

Therefore, an object of the present invention is to perform calibration with high accuracy for positional deviation of each imaging device in an image acquisition apparatus having a plurality of imaging devices.

In order to achieve the above object, an adjustment method of an image acquisition device according to one aspect of the present invention is an image acquisition device for imaging different regions of an object formed by an imaging optical system with a plurality of imaging elements. An adjustment method, comprising: a first step of imaging a test sample with the image acquisition device to acquire a captured image; and a position of the plurality of imaging elements based on a reference image of the test sample and the captured image. It has a second step of acquiring a calibration value, and a third step of performing calibration on the positions of the plurality of imaging elements based on the calibration value.

Further objects or other features of the present invention will be made clear by the preferred embodiments described below with reference to the accompanying drawings.

According to the present invention, in an image acquisition apparatus having a plurality of imaging elements, calibration for positional deviation of each imaging element can be performed with high accuracy.

FIG. 1 is a schematic view of an image acquisition apparatus 100 according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS The schematic of the preparation 20 which concerns on embodiment of this invention. FIG. 2 is a top view of an imaging unit 23 according to an embodiment of the present invention. Explanatory drawing of the imaging operation which concerns on embodiment of this invention. Explanatory drawing of the stitching process which concerns on embodiment of this invention. FIG. 2 is a schematic view of an imaging unit 26 according to an embodiment of the present invention. FIG. 2 is a schematic view of an imaging unit 26 according to an embodiment of the present invention. 6 is a flowchart showing an adjustment method of the image acquisition device according to the embodiment of the present invention. FIG. 2 is a schematic view of a test sample 28 according to an embodiment of the present invention. FIG. 2 is a schematic view of a test sample 28 according to an embodiment of the present invention. FIG. 2 is a schematic view of a test sample 28 according to an embodiment of the present invention. The schematic of the calibration curve which concerns on Example 1 of this invention. FIG. 5 is a diagram of an image acquisition apparatus 100 including a re-imaging unit 42 according to a second embodiment of the present invention. Schematic of the re-imaging unit 42 which concerns on Example 2 of this invention. Schematic of the re-imaging unit 42 which concerns on Example 2 of this invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following.

FIG. 1 is a schematic view of an image acquisition apparatus 100 according to the present embodiment. The image acquisition apparatus 100 controls the microscope unit 1 for imaging the preparation 20 as a subject, the preliminary measurement unit 2 for performing preliminary measurement of the preparation 20, and controls the microscope unit 1 and the preliminary measurement unit 2 and processes the acquired image. Control and processing means 3 for In the image acquisition apparatus 100, after the preliminary measurement unit 2 performs preliminary measurement of the preparation 20 to determine the imaging conditions, the stage device 15 transports the preparation 20 to the microscope unit 1, and the preparation 20 is obtained based on the obtained imaging conditions. Get an image of Furthermore, the image acquisition apparatus 100 according to the present embodiment includes storage means 4 for storing in advance the reference image of the test sample 28 used for calibration (the details will be described later).

First, the microscope unit 1 will be described.
The microscope unit 1 includes an imaging light source 10 for illuminating the preparation 20 via the illumination optical system 11, an imaging optical system 21 for imaging the preparation 20, and an imaging unit 26 for imaging the preparation 20. The stage device 15 is a member that holds and moves the slide 20.

A white light source, an LED light source or the like can be used as the imaging light source 10, and a combination of a white light source and a color filter is used to generate light of each wavelength of RGB or an LED having each wavelength is switchable It is good also as composition.

The stage device 15 includes a holding unit 12 for holding the preparation 20, a fine movement stage 13 for adjusting the preparation 20 in the XYZ directions, and a coarse movement stage 14 for moving the preparation 20 between the microscope unit 1 and the preliminary measurement unit 2. Including. Here, the Z direction corresponds to the optical axis direction of the imaging optical system 21, and the XY direction corresponds to the direction perpendicular to the optical axis. The holding unit 12, the fine movement stage 13 and the coarse movement stage 14 are provided with openings for passing the light from the imaging light source 10.

The imaging optical system 21 is arranged such that the preparation 20 and the imaging surface of the imaging unit 26 are optically conjugate so as to magnify the preparation 20 at a predetermined magnification and form an image on the imaging surface of the imaging unit 26. It is done. Further, by providing the NA stop 22 in the imaging optical system 21, it is desirable that the NA (numerical aperture) on the imaging surface side can be adjusted (details will be described later).

FIG. 2 is a view showing the upper surface and the cross section of the preparation 20. As shown in FIG. The preparation 20, which is an example of the test object, has a configuration in which the sample 18 (such as a biological sample such as a tissue section) disposed on the slide glass 19 is sealed with the cover glass 17 and an adhesive (not shown). There is. Further, even if a label (bar code) 29 on which information necessary for managing the preparation 20 such as the identification number of the specimen 18 and the thickness of the cover glass 17 are recorded is attached on the slide glass 19. Good. In the present embodiment, although the slide 20 is illustrated as the test object to be an image acquisition target, for example, a substrate or the like is used as a test object for the purpose of performing an appearance inspection (foreign substance attachment, flaw inspection, etc.) It is also good.

As shown in FIG. 1, the imaging unit 26 includes an adjustment means 25 and an imaging unit 23. A top view of the imaging unit 23 viewed from the Z direction is shown in FIG. As shown in FIG. 3, the imaging unit 23 is configured of a plurality of imaging elements 24 arranged in a two-dimensional array, and each imaging element 24 images a different area of the slide 20 to obtain a plurality of images at one time. It can be acquired. A CCD, a CMOS, or the like can be used as the imaging device 24. The arrangement and the number of the plurality of imaging elements 24 are not limited to those shown in FIG. 3, and are appropriately determined depending on the shape and area of the field of view of the imaging optical system 21 and the shape and configuration of the imaging element 24. In addition, it is assumed that the imaging unit 26 is held by a main body frame (not shown) or a lens barrel of the imaging optical system 21.

In the image acquisition apparatus 100 having such a plurality of imaging elements 24, it is necessary to take images of the preparation 20 a plurality of times in order to acquire an image without omission in consideration of the gaps between the respective imaging elements 24. Therefore, in the present embodiment, as shown in FIG. 4A, for example, the specimen 18 is imaged in a plurality of steps while moving at least one of the slide 20 or the imaging unit 23 in the horizontal direction to change the relative position. And as shown to FIG. 4B, the image of the whole area | region of the test object 18 can be acquired by carrying out the stitching process of the several image acquired without clearance.

Next, the preliminary measurement unit 2 will be described with reference to FIG. The preliminary measurement unit 2 measures the presence area of the specimen 18 in the preparation 20 and measures the surface shape of the cover glass 17 (specimen 18).

First, light from the preliminary measurement light source 31 is shaped into parallel light by the collimator lens 32, and this parallel light is deflected by the beam splitter 33 and enters the preparation 20. An LED light source or a semiconductor laser can be used as the preliminary measurement light source 31, and at least the entire cover glass 17 is illuminated. The parallel light incident on the preparation 20 is divided into a transmission light T transmitted through the preparation 20 and a reflection light R reflected by the surface of the cover glass 17. Then, the transmitted light T is incident on the camera 30 for measuring the region where the subject 18 is present, and the reflected light R is transmitted through the beam splitter 33 and is incident on the Shack-Hartmann sensor 35 for measuring the surface shape of the subject 18 . In the present embodiment, the transmitted light T is used to measure the presence area of the specimen 18, and the reflected light R is used to measure the surface shape of the specimen 18. However, the reflected light R is used to measure the presence region, The transmitted light T may be used to measure the surface shape.

The camera 30 on which the transmitted light T is incident is, for example, a CCD camera, and is configured to image at least the entire area of the cover glass 17. Of the transmitted light T incident on the camera 30, the amount of light transmitted through the subject 18 is smaller than the amount of light not transmitted through the subject 18. Therefore, the presence area of the specimen 18 in the preparation 20 is determined using the contrast difference between the light transmitted through the cover glass 17, the specimen 18 and the slide glass 19, and the light transmitted only through the cover glass 17 and the slide glass 19. be able to. Then, the image information captured by the camera 30 is input to the control and processing means 3, and the control and processing means 3 performs an operation of recognizing an area where the luminance is equal to or less than a predetermined threshold L as the existence area of the specimen 18.

On the other hand, the reflected light R enters the Shack-Hartmann sensor 35 that measures the wave front of the incident light through the afocal system 34. Here, the preparation 20 and the Shack-Hartmann sensor 35 are disposed at optically conjugate positions. The wavefront of the reflected light R has a shape corresponding to the waviness of the surface of the cover glass 17. Therefore, the surface shape of the cover glass 17 can be measured at high speed and accurately by detecting the surface of the cover glass 17 at once by the Shack-Hartmann sensor 35. Note that, instead of the Shack-Hartmann sensor 35, an interferometer (for example, a shearing interferometer or the like) may be used to detect the wavefront of the reflected light R.

Next, the control and processing means 3 will be described in detail.
The control / processing means 3 is configured by a computer including a CPU, a memory, a hard disk and the like, and performs control at the time of preliminary measurement and imaging, and processing digital data of the prepared slide 20 to create digital images. Do. Specifically, the control / processing means 3 captures an image of the sample 18 a plurality of times while moving the stage device 15 in the X and Y directions, and performs alignment between the images and a stitching process to obtain an image of the entire sample 18 Control and process when acquiring

First, the control and processing means 3 controls the microscope unit 1 and the preliminary measurement unit 2 so that the microscope unit 1 captures an image of the preparation 20 based on the measurement result of the preparation 20 by the preliminary measurement unit 2. That is, the control / processing means 3 determines the range to be imaged by the microscope unit 1 based on the presence area of the specimen 18 obtained using the preliminary measurement unit 2 and performs control to image only the imaging range. As a result, only an area necessary for pathological diagnosis and the like can be imaged, and the volume of digital image data of the slide 20 can be reduced, so that data handling becomes easy. Usually, the imaging range is determined so as to be equal to the region where the sample 18 is present. Further, the control / processing means 3 calculates the in-focus plane of the image of the subject 18 based on the surface shape of the cover glass 17 and the magnification of the imaging optical system 21 obtained using the preliminary measurement unit 2.

Here, when the surface of the cover glass 17 is undulated, the focusing surface of the specimen 18 is also a curved surface corresponding to the undulation. In such a case, when the image of the subject 18 is captured in a state where the imaging surfaces of the imaging unit 23 are arranged on the same plane, a part of the imaging surface does not fall within the focal depth of the image of the subject 18. As a result, the image of the subject 18 projected on a part of the imaging plane is blurred. Therefore, in order to suppress the influence of the waviness of the preparation 20, a focusing operation by individually adjusting each of the plurality of imaging elements 24 in accordance with the surface shape of the sample is required. However, if the positions of the plurality of imaging elements 24 fluctuate with respect to the design values due to installation errors at the time of assembly or thermal expansion of the structural member due to temperature changes in the surrounding environment, etc., as described above Even if the adjustment is performed, blurring occurs in the acquired image. Furthermore, in particular, when positional deviation in the rotational direction in the imaging surface of each imaging element 24 occurs, the stitching processing of the images acquired by each becomes difficult, and it becomes impossible to acquire one image. .

Therefore, in order to solve such a problem, the image acquisition apparatus 100 according to the present embodiment performs calibration on the positional deviation of the plurality of imaging elements 24 before performing the image acquisition operation of the slide 20, and the positional deviation. Reduce the impact of

Hereinafter, the adjustment method of the image acquisition apparatus in the present embodiment will be described in detail.
In the image acquisition apparatus 100 according to the present embodiment, as shown in FIG. 5A, the adjustment unit 25 in the imaging unit 26 has a plurality of driving units 40, which drive the respective positions of the plurality of imaging elements 24. It is configured to adjust. The drive unit 40 is provided on a surface plate 39, and is configured to be able to drive the position of each imaging element 24 in the optical axis direction (Z direction) and the rotational direction in the imaging surface. Furthermore, as shown in FIG. 5B, the drive unit 41 may be provided for the drive unit 40 so that the inclination of the imaging device 24 with respect to the optical axis can also be adjusted. Examples of the adjustment means 25 include a mechanism using a linear actuator having a linear motor, an air cylinder, a stepping motor, an ultrasonic motor, and the like. When manual adjustment is possible, it is possible to adopt a mechanism or the like capable of performing adjustment with a screw by applying a preload by a spring or the like to fix each imaging element 24.

In the present embodiment, when imaging the slide 20, each image sensor 24 is adjusted by the adjustment unit 25 based on the surface shape measured by the preliminary measurement unit 2. Specifically, by adjusting the position of the imaging element of the plurality of imaging elements 24 in which the imaging surface and the focusing surface of the specimen 18 are separated, the imaging surface of the imaging element is brought closer to the focusing surface. The influence of the swell of the preparation 20 can be suppressed. However, as described above, even if the position of the imaging device fluctuates from the design value before imaging, even if adjustment is made to drive each of the imaging devices 24 based on the imaging conditions and approach the focusing plane, Blurring occurs in the acquired image. In addition, due to the deviation of the rotational direction in the imaging plane of each imaging element, stitching processing of a plurality of images becomes difficult. Therefore, in the present embodiment, before performing the image acquisition operation of the slide 20, adjustment of the image acquisition apparatus 100 is performed in order to perform calibration for positional deviation of the plurality of imaging elements 24.

Hereinafter, the adjustment method of the image acquisition apparatus in the present embodiment will be described using the flowchart shown in FIG. Note that the processing in each step of this flowchart is performed by the control and processing unit 3 in the image acquisition apparatus 100 unless otherwise noted.

First, in step S601, a reference image of the test sample 28 used for calibration is acquired by another device and stored in the storage unit 4 in advance. The reason for using the reference image is that, at the time of calibration, it is not clear how much each of the imaging elements 24 fluctuates with respect to the design value, so a reference image is set, It is because it is necessary to grasp via information. In this embodiment, this standard is obtained by imaging the test sample 28 under a stable temperature environment by a normal apparatus other than the image acquisition apparatus 100 to be adjusted and in which no deviation occurs in the imaging device. I have acquired an image. Here, it is assumed that the other devices described above also have a plurality of imaging devices, which correspond to the respective imaging devices 24 in the image acquisition device 100 as a reference imaging device. That is, by comparing the reference image with the captured image acquired by the image acquisition device 100 by the control / processing means 3, the amount of displacement of the imaging device 24 with respect to this reference imaging device can be grasped, and a calibration value is acquired. (Details will be described later).

The reference image may be generated by creating image data serving as a reference with no deviation using an image simulator or the like and storing the image data in the storage unit 4 without using another device as described above. Alternatively, the reference image may be stored in a server on a network connected to the image acquisition apparatus 100 without providing the storage unit 4 in the image acquisition apparatus 100 itself. As the test sample 28, by using a pattern having a lattice pattern or a circle mark as shown in FIGS. 7A, 7B and 7C, the amount of displacement of the position of the imaging element 24 and the distortion value of the image are calculated from the captured image. can do. As described above, step S601 is a preparation stage of adjustment of the image acquisition apparatus 100, and may be performed each time the adjustment is performed, or may be performed only at the first adjustment such as at the time of manufacturing.

In the next step S602, the preliminary measurement unit 2 in the image acquisition device 100 to be adjusted performs preliminary measurement of the test sample 28 used in step S601. By this preliminary measurement, the focal plane and the imaging range of the test sample 28 at the time of imaging are determined. When the test sample 28 is placed on the stage device 15 of the preliminary measurement unit 2, a transport unit (not shown) may be used.

Then, in step S603, the stage device 15 holding the test sample 28 is moved to the microscope unit 1. Here, as shown in FIG. 1, the test sample 28 is positioned to correspond to the focal position of the imaging optical system 21, and this position is used as the reference position in the optical axis direction of the stage device 15. Furthermore, when the slide 20 is installed on the stage device 15, a position where the focal position of the imaging optical system 21 is at the center of the slide 20 may be obtained in advance, and it may be used as a reference position in the horizontal direction of the stage device 15.

Furthermore, in step S604, imaging processing is performed with the test sample 28 as a test object. Here, the control / processing means 3 controls the adjustment means 25 as shown in FIGS. 5A and 5B, for example, to drive the position of each imaging element based on the preliminary measurement result in step S602. At this time, in the vicinity of the focal plane of the test sample 28, imaging is performed multiple times while changing the positions of the plurality of imaging elements 24 by a method such as wobbling. Note that the position referred to here indicates at least one of the position in the optical axis direction (Z direction) of each imaging element 24 and the inclination with respect to the optical axis. Then, the control / processing means 3 acquires, as a calibration curve, the relationship between the parameter indicating the image quality such as contrast and the position of each imaging device 24 at the time of imaging from the plurality of captured images acquired in each imaging device 24 . For example, it is assumed that a curve as shown in FIG. 8 is obtained for certain imaging devices A and B among the plurality of imaging devices 24, and this is acquired for all the imaging devices 24.

In the subsequent step S605, a calibration value for the position of each imaging device 24 is acquired based on the reference image of the test sample 28 and the captured image. First, the control and processing unit 3 derives the position of the image sensor 24 at the highest image quality from the calibration curves for the plurality of image sensors 24 acquired in step S604. At this time, based on the reference image in each reference imaging element acquired in step S601 and the calibration curve in each of the imaging elements 24 corresponding to each reference imaging element, imaging having the same image quality value as the image quality of the reference image The position of the imaging device 24 with respect to the image may be derived. The position of the image sensor 24 derived in this manner is used as a calibration position of the position in the optical axis direction or the inclination with respect to the optical axis, and a calibration value for adjusting positional deviation with respect to this calibration position is controlled and processed. Acquired by means 3.

Further, the control / processing means 3 compares the one at the calibration position among the captured images obtained in step S604 with the corresponding reference image acquired in step S601, and selects the imaging surface of each imaging element 24. The position shift amount in the rotation direction in the inside is acquired. Here, the amount of positional deviation in the rotational direction of each captured image with respect to the reference image is acquired by comparing the patterns of the test samples 28 of the respective images. Then, the calibration value of the position in the rotational direction of the imaging device 24 can be acquired from the positional displacement amount of each captured image. As described above, based on the reference image of the test sample 28 and the captured image, the calibration value for the position (optical axis direction, inclination, rotation direction) of each imaging element 24 can be acquired.

In the final step S606, calibration for positional deviation of each image sensor 24 is performed based on the calibration value obtained in step S605. In this embodiment, based on the calibration value, the control / processing means 3 controls the adjustment means 25 to drive the position of each imaging device 24 in the optical axis direction, the inclination with respect to the optical axis and the position in the rotational direction. Perform calibration by positioning the at the calibration position.

Here, a sequence may be adopted in which the test sample is imaged again after calibration, and the adjustment of the image acquisition apparatus 100 is ended if the value of the image quality of the acquired captured image is a predetermined value for obtaining a good image. In this case, it is determined in S607 whether the image quality of the captured image has reached a predetermined value. If the image quality has not reached the predetermined value, the process returns to step S603, and adjustment is repeated until the predetermined value is obtained. In this sequence, when the stage device 15 is deformed due to a temperature change or the like and the position of the test sample 28 in step S603 fluctuates from the focal position of the imaging optical system 21, a good image is obtained by one adjustment. It is effective when not possible.

By performing calibration with respect to the respective positional deviations of the imaging device 24 in this manner, the focusing operation by the individual driving of each imaging device 24 as described above is performed at the time of imaging of the slide 20, You can get a good image with less. In particular, by performing calibration with respect to positional displacement in the rotational direction within the imaging surface of each imaging element 24, displacement of each acquired image can be suppressed, and stitching processing of a plurality of images can be favorably performed. .

As described above, according to the adjustment method of the image acquisition apparatus according to the present embodiment, in an image acquisition apparatus having a plurality of imaging elements, calibration for positional deviation of each imaging element can be performed with high accuracy. By this, it is possible to suppress the influence of the positional deviation with respect to the design value of each imaging device, which is caused by the thermal expansion of the structural material, the installation error at the time of assembly, or the like.

In this embodiment, as shown in FIG. 9A, a method of adjusting the image acquisition apparatus 100 having a system configuration in which the reflection member 43 and the re-imaging system 44 are provided on the light path will be described. In the following description, the description of the same or equivalent parts as in the first embodiment will be simplified or omitted.

In the image acquisition apparatus 100 according to the present embodiment, each of the plurality of imaging elements 24 is separately disposed, and each one is configured as an imaging unit 26. Furthermore, each imaging unit 26 transmits a different region of the slide 20 and reflects a plurality of light fluxes formed through the imaging optical system 21, and the light fluxes from the respective reflection members 43 as respective imaging elements And a plurality of re-imaging systems 44 for forming images on 24 imaging planes. Here, it is assumed that a plurality of re-imaging units 42 are configured by each imaging unit 26 and each reflecting member 43 and each re-imaging system 44 corresponding to each imaging unit 26. The position of each re-imaging unit 42 may be adjusted by providing a drive system 45 in each re-imaging unit 42 and controlling each with the control / processing means 3. The drive system 45 can also use the same mechanism as the adjustment unit 25 in the first embodiment. In addition, by configuring the control and processing means 3 so that focusing of each re-imaging system 44 is possible, focusing on each imaging device 24 may be performed. In this embodiment, each re-imaging system 44 is provided with the correction optical element 46, and the focal position can be changed by driving each correction optical element 46 in the optical axis direction (Y direction) by a drive mechanism (not shown). There is.

Here, as shown in FIG. 9B, by providing the drive unit 40 as the adjustment means 25 in each imaging unit 26, the position of the optical axis direction (Y direction) of each imaging element 24 and the rotational direction in the imaging plane are driven. It can be configured as possible. Furthermore, as shown in FIG. 9C, the drive unit 41 may be provided for the drive unit 40 so that the inclination of each image sensor 24 with respect to the optical axis can also be adjusted. In the present embodiment, the drive unit 40 may not be driven in the optical axis direction (Y direction) (details will be described later).

Even when the image acquisition apparatus 100 is configured as shown in FIGS. 9A to 9C, it is possible to perform calibration on the positional deviation of each imaging element in the same manner as the method in the first embodiment. Furthermore, in the configuration provided with the re-imaging unit 42 as shown in FIG. 9B and FIG. 9C, in particular, the adjustment method of the image acquisition device in the case of not driving the inclination of each imaging element 24 with respect to the optical axis explain.

First, in step S601, as in the first embodiment, the reference image of the test sample 28 is stored in the storage unit 4 in advance. In the next steps S602 and S603 as well, after preliminary measurement of the test sample 28 is performed as in the first embodiment, the test optical system is moved to the focal position of the imaging optical system 21.

Then, in step S604, an imaging process of the test sample 28 is performed. In the first embodiment, imaging is performed a plurality of times while changing the positions of the plurality of imaging elements 24. However, in the present embodiment, imaging is performed only once based on the preliminary measurement result in step S602. Acquire a captured image.

In the subsequent step S605, a calibration value for the position of each imaging device 24 is acquired based on the reference image of the test sample 28 and the captured image. First, a reference image by each imaging device serving as a reference in another apparatus acquired in step S601 is compared with a captured image acquired in step S604 corresponding to each of the reference images. Specifically, the control / processing means 3 derives the shift amount of the image quality (contrast etc.) value between the reference image and the captured image and the positional shift amount in the rotational direction. Then, the control / processing means 3 calibrates the optical axis direction and the rotational direction of each image sensor 24 corresponding to each image based on the amount of displacement of the image quality value derived from each image and the positional displacement amount in the rotational direction. Calculate the position. Based on the calibration position obtained in this manner, the calibration value with respect to the position (optical axis direction, rotation direction) of each imaging element in the image acquisition device 100 can be acquired by the control and processing means 3.

In the final step S606, the image acquisition apparatus 100 is adjusted based on the calibration value obtained in step S605. That is, based on the calibration value, the control / processing means 3 controls the adjustment means 25 to drive the position of each imaging element 24 in the optical axis direction (Y direction) and rotational direction, It is possible to perform calibration for positional deviation.

Here, in the configuration as shown in FIGS. 9A to 9C, the focus adjustment by driving the imaging device 24 in the Y direction may be performed by driving the re-imaging unit 42 in the Z direction, or the correction optical element 46. By driving in the Y direction. That is, in the image acquisition apparatus 100 according to the present embodiment, calibration is performed for positional deviation of each imaging element 24 in the optical axis direction without driving each imaging element 24 itself in the optical axis direction (Y direction). be able to.

Specifically, first, in step S605, based on the calculated calibration value of each imaging element 24 in the Y direction, the calibration value in the Z direction of each reimaging unit 42 corresponding to each or each correction optical element 46 Get the calibration value in the Y direction of. Then, in step S606, the control / processing means 3 controls the drive system 45 or a drive mechanism (not shown) to adjust the position of each reimaging unit 42 (Z direction) or adjust the position of each correction optical element 46 (Y Direction). As described above, the position adjustment of each re-imaging unit 42 or the focus adjustment of each re-imaging system 44 is performed by the control / processing means 3 to calibrate the positional deviation of each image sensor 24 in the Y direction. be able to. In addition, with respect to positional deviation in the rotational direction of each image sensor 24, calibration is performed by rotating each image sensor 24 by the drive unit 40. In the case where the re-imaging system 44 is a variable focus lens that does not have the correction optical element 46, such as when the re-imaging system 44 is a liquid lens or a liquid crystal lens, calibration values are obtained according to each configuration. Calibration for positional deviation of each imaging element 24 is possible.

By performing calibration with respect to the respective positional deviations of the imaging device 24 in this manner, the focusing operation by the individual driving of each imaging device 24 as described above is performed at the time of imaging of the slide 20, You can get a good image with less. In particular, by performing calibration with respect to positional displacement in the rotational direction within the imaging surface of each imaging element 24, displacement of each acquired image can be suppressed, and stitching processing of a plurality of images can be favorably performed. .

As described above, according to the adjustment method of the image acquisition apparatus according to the present embodiment, in an image acquisition apparatus having a plurality of imaging elements, calibration for positional deviation of each imaging element can be performed with high accuracy. In particular, even in a configuration in which the position of each imaging element in the optical axis direction and the inclination with respect to the optical axis are not driven, it is possible to suppress the influence of the positional deviation on the design value of each imaging element.

In step S606 in the first and second embodiments, each image sensor 24 is rotated based on the calibration value. However, with respect to the positional deviation in the rotational direction of each image sensor 24, calibration using image processing is performed. You may That is, for the displacement of each captured image caused by the positional displacement in the rotational direction of each imaging element 24, the control / processing means 3 calculates the correction amount by image processing based on the calibration value obtained in step S605. The correction amount is obtained as an offset value. As a result, when imaging the preparation 20 to be observed and performing a stitching process, the control / processing means 3 performs correction with the offset value taken into consideration, so that the influence of the positional deviation of the imaging device 24 is suppressed. Can. Therefore, by using image processing, calibration can be performed for positional deviation in the rotational direction of each imaging element without driving each imaging element.

Other embodiments

Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the present invention.

For example, in the adjustment method of the image acquisition apparatus according to each embodiment described above, it is highly accurate to set the NA of the imaging optical system 21 to different values at the time of imaging of the test sample 28 and at the time of imaging of the slide 20. It is an effective means for performing calibration.

Specifically, in the case of imaging a test sample 28 having a small degree of flatness, a higher resolution image can be obtained by setting the NA to a higher NA than when imaging the preparation 20 having a wave, so that high accuracy is achieved. Calibration values can be obtained. Also, when performing distortion correction in order to obtain a more accurate calibration value, adjusting the NA can be considered as an effective means. In order to calculate the distortion correction amount, it is necessary to detect the barycentric position of the round mark in each captured image when capturing a test sample as shown in FIGS. 7B and 7C. At this time, the NA can be changed by the NA stop 22 to adjust the contrast of the captured image, and the detection accuracy of the center-of-gravity position of the round mark can be enhanced.

As described above, adjusting the NA stop 22 according to the application can be said to be an effective means to realize high-precision calibration of the image acquisition apparatus. In addition, as the NA stop 22 for adjusting the NA, it is possible to use one capable of arranging a field blocking plate with a plurality of different apertures according to the application, an iris diaphragm comprising a plurality of field blocking blades, or the like.

The present invention is not limited to the above embodiment, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Accordingly, the following claims are attached to disclose the scope of the present invention.

3 Control / Processing Means 5 Storage Means 20 Preparate 21 Imaging Optical System 22 NA Aperture 24 Imaging Element 25 Adjustment Means 28 Test Sample 100 Image Acquisition Device

Claims (19)

1. An adjustment method of an image acquisition apparatus, which images different areas of an object formed by an imaging optical system with a plurality of imaging elements, respectively.
   A first step of imaging a test sample with the image acquisition device to acquire a captured image;
   A second step of acquiring calibration values for the positions of the plurality of imaging elements based on the reference image of the test sample and the captured image;
   A third step of performing calibration on the positions of the plurality of imaging devices based on the calibration value;
   A method of adjusting an image acquisition apparatus, comprising:
2. The image acquisition apparatus according to claim 1, wherein the third step is a step of adjusting a position in a rotational direction in each imaging surface of the plurality of imaging elements based on the calibration value. How to adjust the
3. The third step is a step of adjusting at least one of the position in the optical axis direction and the inclination with respect to the optical axis in each of the plurality of imaging elements based on the calibration value. The adjustment method of the image acquisition apparatus as described in 2.
4. The third step is
   Based on the calibration value, the plurality of imaging elements, the plurality of reflecting members disposed on the optical path between the imaging optical system and the plurality of imaging elements, and the plurality of reflecting members respectively reflect Adjusting the positions of a plurality of re-imaging systems for imaging the test object on the respective imaging surfaces of the plurality of imaging elements by the light beam thus produced;
   Or focusing each of the plurality of reimaging systems based on the calibration value;
   The adjustment method of the image acquisition device according to claim 1 or 2, characterized in that:
5. The third step is a step of calculating a correction amount for positional deviation in the rotational direction in the plane of the captured image based on the calibration value, and acquiring the correction amount as an offset value in image processing. The adjustment method of the image acquisition device according to claim 1 or 3 characterized by the above-mentioned.
6. In the first step, the numerical aperture of the imaging optical system is adjusted to a numerical aperture different from that at the time of imaging of an object other than the test sample. The adjustment method of the image acquisition apparatus as described.
7. The adjustment method of the image acquisition apparatus according to any one of claims 1 to 6, wherein in the first step, a numerical aperture of the imaging optical system is adjusted according to the captured image.
8. An imaging optical system for imaging an object to be examined;
   An image acquisition apparatus comprising: a plurality of imaging elements respectively imaging different areas of the test object imaged by the imaging optical system;
   Storage means in which a reference image of a test sample is stored;
   Processing means for acquiring calibration values for the positions of the plurality of imaging devices based on the reference image and the captured image of the test sample acquired by the image acquisition device;
   An image acquisition apparatus characterized by performing calibration on positions of the plurality of imaging devices based on the calibration value.
9. 9. The image acquisition apparatus according to claim 8, further comprising an adjustment unit configured to adjust the position of each of the plurality of imaging elements based on the calibration value.
10. 10. The image acquisition apparatus according to claim 9, wherein the adjustment unit is capable of adjusting the position in the rotational direction in each imaging surface of the plurality of imaging elements based on the calibration value.
11. 11. The apparatus according to claim 9, wherein the adjusting unit is capable of adjusting at least one of the position in the optical axis direction and the inclination with respect to the optical axis in each of the plurality of imaging elements based on the calibration value. Image acquisition device as described.
12. A plurality of reflecting members disposed on an optical path between the imaging optical system and the plurality of imaging elements;
    A plurality of re-imaging systems for forming an image of the subject on respective imaging surfaces of the plurality of imaging devices by light beams reflected by the plurality of reflecting members;
    The image acquisition apparatus according to any one of claims 9 to 11, characterized in that
13. 13. The image according to claim 12, further comprising: a drive system that adjusts the positions of the plurality of imaging elements, the plurality of reflecting members, and the plurality of reimaging systems based on the calibration value. Acquisition device.
14. The image acquisition apparatus according to claim 12, wherein the plurality of reimaging systems are capable of focusing based on the calibration value.
15. The processing means calculates a correction amount for positional deviation in a rotational direction within the plane of the captured image based on the calibration value, and acquires the correction amount as an offset value in image processing. Item 12. The image acquisition device according to item 8 or 11.
16. The numerical aperture of the imaging optical system at the time of imaging of the test sample is characterized by having an NA stop that can be adjusted to a numerical aperture different from that at the time of imaging of an object other than the test sample. The image acquisition device according to any one of the above.
17. The image acquisition apparatus according to claim 16, wherein the NA stop is capable of adjusting the numerical aperture of the imaging optical system in accordance with the imaged image of the test sample.
18. The image acquisition apparatus according to any one of claims 8 to 17, wherein the reference image is acquired by an apparatus different from the image acquisition apparatus.
19. Assembling an image acquisition device for respectively imaging different regions of the object by a plurality of imaging elements;
    Imaging the test sample with the image acquisition device to acquire a captured image;
    Acquiring calibration values for positions of the plurality of imaging devices based on the reference image of the test sample and the captured image;
    Calibrating the position of the plurality of imaging devices based on the calibration value;
    A method of manufacturing an image acquisition apparatus, comprising:

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